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North Star QRA Update Chlorine and VCM plant (Rafnes)

Report for: Wood

Report no: PRJ11090011 Rev: Final

Date: 11 January 2019

Document history

Revision Date Description/changes Changes made by

Draft 30.11.2018 First issue of report Andrea Risan / Ingebjørg Valkvæ / Stian Jensen

Final 11.01.2019 Comments from client incorporated

Andrea Risan / Ingebjørg Valkvæ

Executive summary Lloyds Register (LR) has been engaged by Wood and INOVYN Norge to conduct an update of the quantitative risk assessment (QRA) of the Chlorine and VCM plant at the Rafnes Industrial Site (Grenland, Norway) to accommodate any changes in the risk picture due to the North Star project. The North Star project includes implementation of several modifications to the facility which will increase the total production capacity with around 10 %.

The QRA update is conducted by using the existing risk model of the facility and adding the events potentially caused by the planned modifications. A similar approach as applied in the existing QRA is applied in the risk assessment of the North Star modifications. In that manner the risk level before and after the modification can be compared. The risk acceptance criteria proposed by DSB are applied in the study. Hence, the focus in the study is directed towards major accident events that may cause fatal exposure outside of the boundary of the facility.

The main conclusion of the study is that the North Star project only contributes with a modest risk increase to third parties, and that the main risk drivers remain unchanged after the update. It is still toxic releases of chlorine and HCl that dominates the risk picture, in addition to BLEVE events in the VCM storage area. The calculated risk picture is shown in the below figure.

Report no: PRJ11090011 Rev: Final Page ii

Date: 11 January 2019 ©Lloyd’s Register 2019

Glossary/abbreviations ALARP As Low As Reasonably Practicable

AT The Norwegian Labour Inspection Authority (Arbeidstilsynet). A governmental agency under the Ministry of Labour, focused on occupational safety and health

BLEVE Boiling Liquid Expanding Vapour Explosion

CFD Computational Fluid Dynamics

DSB Norwegian Directorate for civil protection (Direktoratet for Samfunnssikkerhet og Beredskap)

EDC Ethylene DiChloride, 1,2-dichloroethane

ESD Emergency Shut Down

EX Ex-equipment or explosive protected equipment, both electric and mechanical.

FTM Forslag Til Modifikasjoner

Hazardous substances Flammable, reactive, pressurised and explosive substances

HAZID Hazard Identification

Report no: PRJ11090011 Rev: Final Page iii


HCl Hydrogen Chloride

HTDC High Temperature Direct Chlorination

IR Individual Risk

LFL Lower Flammability Limit

LNF Landbruk-, Natur- og Friluftsområde

LOC Loss Of Containment

OHCL Oxy HydroChlorination

PSD Process Shut Down

QRA Quantitative Risk Analysis

RAC Risk Acceptance Criteria

Safeti Safeti QRA software tool - A user-friendly, industry standard method for carrying out Quantitative Risk Assessments (QRA) of onshore process, chemical and petrochemical facilities. Developed by DNV-GL.

Third party (3rd person) People outside the production plant that may be affected by its activities.

(2nd person: People that are not directly related to the operation of the plant, but benefit from being close to the plant

1st person: People who are directly involved in the operations of the plant, i.e. the employees at the plant)

VCM Vinyl Chloride Monomer

Report no: PRJ11090011 Rev: Final Page iv


Table of contents Page

1 Introduction 1

1.1 Background 1

1.2 Objective 1

1.3 Scope of work 1

1.4 Presumptions and limitations 1

1.4.1 Presumptions 1 1.4.2 Limitations 1

1.5 Regulations and standards 2

2 Framework 2

2.1 Methodology 2

2.2 Assumptions and input data 4

2.3 Acceptance criteria 4

3 System description 5

3.1 General description 5

3.2 Process description 5

3.2.1 Chlorine – INOVYN scope 5 3.2.2 VCM – Wood scope 6

3.3 North Star project 7

3.3.1 VCM plant modifications 7 3.3.2 Safety measures for the new HTDC module 8 3.3.3 Water curtain in the HTDC module 8 3.3.4 Chlorine plant modifications 9

3.4 Safety measures 9

3.4.1 Pressure monitoring and shutdown 9 3.4.2 Chlorine absorption system 9 3.4.3 Gas detection and emergency shutdown 9 3.4.4 Fire proofing of storage spheres 9 3.4.5 Emergency preparedness 9

4 Selection of hazardous events 9

4.1 Existing QRA 9

4.2 Scenarios for the new HTDC module 11

4.3 Scenarios for the new OHCL reactor 12

4.4 Risk screening of other North Star modifications 12

5 Frequency analysis 14

6 Consequence analysis 15

6.1 Event tree 15

6.2 Fatality criteria 16

6.3 Consequence modelling 16

7 Risk picture and risk evaluation 18

7.1 Total risk picture 18

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7.2 Risk from the chlorine plant 19

7.3 Risk from the VCM plant 21

7.4 Individual risk at nearest resident 24

8 Uncertainties 26

9 Potential conservatism in the QRA 26

9.1 Release durations and transient effects 26

9.2 Terrain effects 27

9.3 Release modelling 27

9.4 Event frequencies 27

9.5 BLEVE 27

9.6 Flash fire envelope 27

10 Conclusion and recommendations 28

10.1 Recommendations 28

10.2 Conclusions 28

11 References 29

Appendix A – Assumptions and input data Appendix B – Risk screening workshop – VCM plants Appendix C – Risk screening workshop – Chlorine plant

Report no: PRJ11090011 Rev: Final Page vi


1 Introduction

1.1 Background Lloyd’s Register (LR) has been engaged by Wood and INOVYN Norge to carry out an update of the quantitative risk assessment (QRA) for INOVYN’ s Chlorine and Vinyl Chloride Monomer (VCM) plant at the Rafnes Industrial Site (Rafnes) conducted in 2015 (Ref. /1/).

The North Star project introduces several modifications to the Chlorine and VCM plant in order to increase the production capacity of the plant. The modifications include:

• Installation of a new High Temperature Direct Chlorination (HTDC) module

• Replacing the existing Oxy HydroChlorination (OHCL) reactor with a new one

• Several other modifications to process vessels and equipment in the VCM plant to allow for the increased capacity

• Installation of a new electrolyser in the chlorine plant

• Replacement of the hydrogen compressor, chlorine compressor and chlorine cooler.

INOVYN Norge is classified as a so called major accident facility according to “Storulykkeforskriften” (Ref. /9/). Hence, the facility is required by regulations to minimize the risk for major accidents. The QRA can be seen as part of the effort to reach this objective.

1.2 Objective The objective of the QRA update is to investigate the impact of the North Star project on the existing risk picture at INOVYN’s facility at Rafnes. The modifications will be assessed and included in the existing QRA of the facility. Potential risk drivers will be identified, and it will be evaluated if the project introduces significant change in the risk for third parties. The proposed risk acceptance criteria by DSB (Ref. /2/) are applied in the risk assessment.

1.3 Scope of work The scope of work involves using the risk model developed in the existing QRA of INOVYN’s facility at Rafnes as a starting point. The risk model is implemented using the Safeti software. Events introduced by the North Star project will be handled in a similar manner as in the existing QRA by using, e.g., the same event frequency references, fatality criteria and overall assumptions as a basis. The focus in the QRA is to address major accidental events that may influence the extent of risk zones (“hensynssoner” in Norwegian) around the facility.

1.4 Presumptions and limitations

1.4.1 Presumptions

The following presumptions apply to the study:

1. Normal operation including regular shut down and maintenance and start up activities are the base of the QRA.

2. If risk reducing measures are disengaged during operation, it is a prerequisite that compensating measures are implemented so that the barrier’s function is kept. If compensating measures are not taken, the QRA is not valid.

1.4.2 Limitations

The following limitations apply to the study:

1. Events while ship is at sea or mooring are not included

2. The ships on-board systems (tanks, pumps, piping) are not included

Report no: PRJ11090011 Rev: Final Page 1


3. The tunnel with export pipelines to Herøya is not included. A separate risk assessment for the tunnel has been conducted, Ref. /3/

4. Escalation effects have not been quantified. An escalation is defined as an initial event on the site, e.g. a fire that impairs other equipment containing flammable or toxic material on the same site. Thereby leading to a larger fire or more severe toxic effects. One exception is the inclusion of Boiling Liquid Expanding Vapour Explosion (BLEVE) events in the QRA. A BLEVE can be considered as an escalated event, since a prerequisite for such a scenario to occur is long exposure time to relatively high heat loads, i.e. fire exposure.

5. Domino effects, e.g. events where fire and explosion triggers new release scenarios (or other effects) from equipment in adjacent facilities, have not been calculated specifically. Domino effects are discussed in the risk analysis from 1991 and 1998 (Ref. /4/ and /5/) and in the report "Vurdering av dominoeffekter mellom fabrikkanleggene på Borealis AS, Noretyl AS og Hydro Polymers AS i forbindelse oppdatering av Sikkerhetsrapporten for Hydro Polymers og Noretyl", Ref. /6/.

1.5 Regulations and standards The most central regulations related to health, safety and the environment (HSE) for the onshore chemical process industry which come under the supervisory authority of the DSB and AT are found in the HSE regulations and the working environment regulations.

The following relevant regulations apply for INOVYN Norge and set the premise for the current risk assessment:

• DSB: "Forskrift om håndtering av brannfarlig, reaksjonsfarlig og trykksatt stoff samt utstyr og anlegg som benyttes ved håndteringen (forskrift om håndtering av farlig stoff) ", FOR-2009-06-08-602, 8. juni 2009, Ref. /7/.

• DSB Temaveileder ”Sikkerheten rundt anlegg som håndterer brannfarlige, reaksjonsfarlige, trykksatte og eksplosjonsfarlige stoffer: Kriterier for akseptabel risiko”, May 2013, Ref. /8/.

• Storulykkeforskriften FOR-2005-06-17-672, Council Directive 96/82/EC of 9 December 1996 on the control of major-accident hazards involving dangerous substances, Ref. /9/.

Also note, that since the QRA was established, DSB has introduced a new guideline for conducting QRAs, i.e. “Retningslinjer for kvantitative risikovurderinger for anlegg som håndterer farlig stoff” (Ref. /10/). Those new guidelines are not adopted at the present stage.

2 Framework

2.1 Methodology The overall methodology used in the QRA is illustrated in Figure 2.1.



Figure 2.1 - QRA methodology

The building blocks of the study are briefly discussed below.

1. Risk acceptance criteria

The acceptance criteria are used to evaluate the risk and aid in decisions regarding need for risk reducing measures. The acceptance criteria applicable for this project are presented in Chapter 2.3.

2. System definition

A presentation of the system included in the scope of the QRA and its limitations are presented in Chapter 3.

3. Hazard identification

A hazard identification (HAZID) workshop was performed at Rafnes during the previous QRA update in 2015 and was used to define relevant scenarios for the QRA.

A risk screening workshop identifying the possible hazards related to the modifications of the North Star project was performed at Rafnes in October 2018. The results from the risk screening workshop are summarized in Chapter 4 and documented in Appendix B and C.

4. Frequency analysis

The frequency analysis is performed to select and define a set of scenarios that represent the risk posed by the Chlorine and VCM plant. The frequency analysis is described in Chapter 5.

5. Consequence analysis

The possible consequences from each scenario from the frequency analysis are simulated using the software Safeti. The consequence analysis is described in Chapter 6.

6. QRA results – Risk picture and risk evaluation

The risk picture is the result of the frequency analysis and the consequence analysis. The resulting risk picture for the Chlorine and VCM plant is presented in Chapter 7. The risk is evaluated by comparing the resulting risk picture with the applied RAC.

7. Risk-reducing measures

Risk-reducing measures are recommended in order to meet the acceptance criteria or to further reduce the risk in line with ALARP. Recommendations are given in Chapter 10.



2.2 Assumptions and input data All assumptions made in the study are presented in the assumption sheets in Appendix A together with any data used for the study including wind data, population data and vulnerabilities.

2.3 Acceptance criteria This study applies the Risk Acceptance Criteria (RAC) proposed by Norwegian authority DSB (Ref. /8/) in their guidance document regarding RAC for facilities storing and handling hazardous substances. The RAC are based on the individual risk contours calculated for the facility, and defines a number of zones for special consideration. The RAC are presented in Table 2-1 and Figure 2.2.

Table 2-1 - Acceptance criteria, defined zones for consideration

Zone for consideration

Acceptance criteria Provisions for the zone (accepted object and activities in the zone)

Inner zone IR is higher than 1E-5 per year

Primarily within the facility’s property limits, extension into LNF-areas may be allowed.

Intermediate zone IR is in between 1E-5 and 1E-6 per year

Public roads, railway, quays are accepted and also industries and offices.

No permanent housing is permitted, though some scattered housing may be permissible under certain circumstances

Outer zone IR is in between 1E-6 and 1E-7 per year

Housing, public facilities, shops, smaller overnight accommodations and other usage for the general public accepted

Outside outer zone IR is lower than 1E-7 per year

Schools, hospitals, shopping centres, hotels, large venues etc. should be outside the outer zone

Figure 2.2 - Illustration of safety zones around a plant with marked iso-contours that defines the zones (Ref. /8/)



3 System description

3.1 General description The INOVYN Norge production plant for vinyl chloride monomer, VCM, is located at Rafnes industry facility in Bamble community in Norway. Figure 3.1 show an overview of the Rafnes industrial site and the surrounding areas of the Chlorine and VCM plants. The closest residential area, Herre, is located west of the chlorine plant. The closest house is approximately 400 m from the fence around the chlorine plant. Highway 353 marks the property boundary towards west. The road is at a higher elevation than the plant and there is also a ridge between the plant and the road. There is also a smaller road that goes alongside the plant fence before it connects to the highway again. This road is public, but can be blocked in case of an emergency.

Figure 3.1 – Overview of the Chlorine/VCM plant and the surrounding areas

Located southeast on the Rafnes industrial site and neighbouring the VCM plant is Noretyl AS ethylene plant. A polyethylene plant owned by INOVYN Bamble AS lies further to the southeast, at the Rønningen industrial site (not shown in Figure 3.1).

This report presents the risk introduced from the North Star project associated with the Chlorine and VCM plant.

3.2 Process description

3.2.1 Chlorine – INOVYN scope

There are two almost identical production lines (Chlorine 1 and 2) with membrane electrolysers for production of chlorine. Chlorine is produced on the anode side and hydrogen and caustic soda on cathode side. The moist chlorine gas is cooled, filtered and dried with sulphuric acid before being compressed to approx. 5.5 bar(g) and sent to the VCM plant. The chlorine gas from both line 1 and 2 is delivered in a single 250 mm header.



The hydrogen gas is cooled, filtered, dried and compressed and sent to the VCM plant and to the neighbouring industry Noretyl to be used as raw material or fuel gas.

The caustic soda is concentrated to 50 % using evaporation and then stored. The caustic soda is exported by trucks and shipped by boats to several customers.

The chlorine plant is divided into the following areas:

• Water purification

• Brine

• Cell room

• Caustic soda

• Hydrogen

• Lean brine dechlorination

• Emergency scrubber/recovery chlorine

• Chlorine.

3.2.2 VCM – Wood scope

VCM is produced from the intermediate substance Ethylene DiChloride (EDC). EDC is produced in two separate processes in the VCM plant. The first process is by direct chlorination, using ethylene gas from Noretyl and chlorine gas from the chlorine plant. The second is by oxychlorination, using hydrogen chloride, hydrogen gas, ethylene gas and air. The EDC from the direct chlorination and oxychlorination is purified (distilled to remove light and heavy bi products) and intermediately stored before being sent to the cracking furnaces.

VCM is produced by cracking EDC to VCM and Hydrogen Chloride (HCl) at a temperature of approx. 500 °C and 20 bar(g) pressure. The gas out of the cracking furnaces still holds a large amount of EDC and a number of steps are needed to separate VCM, HCl and EDC from the raw gas. The EDC is condensed by cooling and HCl stripped off by reducing the pressure. Finally a distillation process removes the last traces of HCl and EDC and by-products from VCM. The pure VCM is stored as liquid in pressurized spherical tanks before being offloaded by ship or pumped through piping under the Frierfjord to INOVYN Norge PVC plant at Herøya.

Utility systems include steam and condensate system, cooling water system, waste water treatment, incinerators for vented gases and fuel gas system.

The VCM plant is divided into process area, tank farm, control centre, flare and quay. Production, as well as sewage treatment and combustion of bi-products, takes place in the process area. The process area is further divided into a number of plant areas as listed below:

• 1100 - Oxychlorination

• 1200 - EDC-recovery

• 1300 - EDC purification

• 1400 - Cracking

• 1500 - VCM-purification

• 1600 - Direct chlorination

• 1700 - HCl-unit

• 1800-1900 - Waste water treatment

• 1800 - Incinerator

• 2700 - EDC/VCM/by-product storage

• 3000 - Jetty 2.



3.3 North Star project The North Star project introduces several modifications to increase the capacity of the Chlorine and VCM plant. The modifications are designed to increase the overall production rate of the plant with around 10 %.

3.3.1 VCM plant modifications

The main modifications to the VCM plant are installation of a new HTDC module and an OHCL reactor:

• The HTDC module is a new module at INOVYN and will operate in parallel to the existing LTDC module. It is expected to have a footprint of approximately 28 m x 8 m with three levels. The module is relatively congested with process equipment and reactors. A process flow diagram of the new HTDC module located in the VCM plant is shown in Figure 3.2

• The OHCL reactor will replace an existing reactor. The flow throughput and the volume of the reactor will be increased. The existing reactor will be put out of operation and work as a spare reactor.

In addition, several minor modifications, or FTMs (“Forslag Til Modifikasjoner”), will be made to allow for the increased production capacity. Details of the scope of these modifications can be found in Appendix B. Figure 3-3 illustrates the locations of the North Star modifications in the VCM plant.

Figure 3.2 – Process flow diagram (PFD) of HTDC module



Figure 3-3 – VCM plant – Location of FTMs. The yellow box (left) is the location of the new HTDC module, and the orange box (right) is the location of the OHCl reactor

3.3.2 Safety measures for the new HTDC module

The North Star modifications include installation of gas detection systems in the new HTDC module. The following gas detection systems will be installed:

• EX detectors for explosive gas detection

• Chlorine gas detectors (point detectors)

• Sniffing detectors for detection of toxic gas releases (low concentrations).

Further, there will be replacement of the existing flame arrestor and fire water monitor for the HTDC module. Fire water monitor X1032/12 shall be replaced by a new remotely controlled fire water monitor (X1032/16). Fire water monitor X1032/10 will be moved to ensure better coverage of the HTDC area in addition to the originally covered process areas.

3.3.3 Water curtain in the HTDC module

There is a discussion in the North Star project regarding the possible implementation of a water curtain between the HTDC module and the vessels in area 1600. The main purpose of such a water curtain would be to reduce the likelihood of escalation from an accidental event in the HTDC module to the wash tanks in area 1600.

In general, water curtains are used to protect personnel from high heat radiation levels during, e.g. escape or other special events such as an ignited flare during a blow down situation. For protection of vessel containing hazardous substances, it is probably more optimal to apply a deluge system. Fire water can then be applied over the tanks to enhance the cooling effect.

The HTDC module is already covered be two remotely controlled fire monitors. One of which has a direct line of sight to the abovementioned vessels. This is likely to be sufficient. However, to further quantify the benefit of a deluge system, in addition to fire monitor, one could establish:

• The consequence of vessel ruptures.

• The probability, or frequency, of fires that may lead to loss of containment of hazardous substances in the 1600 area.



If INOVYN has a criteria for an unacceptable escalation this can be applied in the decision making, when the consequence and likelihood of vessel rupture (escalation) has been established.

If the consequence of a vessel rupture is low, i.e., if it does not significantly increase the severity of the event, a deluge system is unlikely to be in the ALARP range of measures. A similar argument can be made if the frequency of fires that may cause an escalation is low.

The above discussion assumes that there is no BLEVE potential in area 1600. The matter should be assessed in more detail if that is not the case.

3.3.4 Chlorine plant modifications

The modifications to the chlorine plant are:

• Installation of a new electrolyser

• Increased capacity of the chlorine compressor, hydrogen compressor and chlorine cooler.

Details of the scope of these modifications can be found in Appendix C.

3.4 Safety measures

3.4.1 Pressure monitoring and shutdown

The pressure is monitored in the chlorine header and many other places in the process. Detected very low pressures, e.g. in case of a larger leak, lead to automatic shutdown.

3.4.2 Chlorine absorption system

In an event of leak or failure in the chlorine plant the production in the cells are stopped and the emergency absorption system is started. The chlorine gas is absorbed in sodium chloride, producing sodium hypochlorite. A low pressure is created with ejectors and the produced chlorine gas is sucked through the absorption system.

3.4.3 Gas detection and emergency shutdown

Chlorine gas detectors are located both indoors in the chlorine plant and outdoors in the chlorine and VCM plant. There is no automatic shutdown but an operator will directly suit up in gas protection gear and look for the leak.

There is also VCM gas detectors located in the process area and around pumps in the storage area. The detectors are very sensitive and detect at ppm level. No automatic shutdown and procedures are the same as for chlorine.

3.4.4 Fire proofing of storage spheres

The VCM storage spheres are fitted with fire detection and deluge in order to minimize risk of escalation and possible BLEVE event in the storage area.

3.4.5 Emergency preparedness

At Rafnes and Rønningen there is a common emergency preparedness plan and organisation. Norward is a company providing services within industrial emergency preparedness and they are localized in the fire station at Rafnes. They provide their services to the plants on Rafnes and Rønningen.

4 Selection of hazardous events

This section selects the units or process segments that may cause hazardous events that can influence the risk picture around the facility.

4.1 Existing QRA The events included in the present study are based on evaluations made in the previous QRA update in 2015, Ref. /1/. The general assumptions regarding each subsystem are presented in Table 4.1.



Table 4.1 – General assumptions regarding scenario selection, ref. /1/

Part of plant Scenarios included in the QRA

General assumption

Chlorine plant

Water purification No scenarios No (or limited) hazardous substances

Brine No scenarios No (or limited) hazardous substances

Cell room Cl2 header in the cell room is considered

Leaks from individual cells and anolyte/ catolyte solutions are not considered to pose a threat outside the cell room

Leak of H2 is assumed to give fire in the cell room with only local effects. Domino effects towards Cl2 system is considered negligible

Caustic soda No scenarios Leaks of NaOH solution is assumed to give only local effects

Hydrogen H2 header to VCM is considered

Leaks of H2 from compressors etc. are assumed to give only local effects.

Domino effects towards Cl2 system is considered negligible

Lean brine dechlorination

No scenarios Small amounts of Cl2, low pressures vacuum-0.2 bar(g) and leaks are assumed to give only local effects.

Leaks of anolyte solution is assumed to give only local effects

Emergency scrubber/recovery chlorine

If pumps P3704, P3706 stops while production trips

Pumps are connected to emergency power.

Small amounts of Cl2, low pressures vacuum-0.2 bar(g) and leaks are assumed to give only local effects

Chlorine All leak points of Cl2 gas are considered

Leak of H2SO4 is assumed to give only local effects.

No liquid Cl2 at any point assumed

VCM plant

1100 oxychlorination

Leaks of C2H4 is considered

Leaks of HCl is considered

Leaks of H2 is considered

NH3-tank considered

Leak of EDC (C2H4Cl2) is assumed to give only local effects and no scenarios for EDC (incl. reactor V1101/V1106 (OHCL)) are included in the calculations

1200 EDC-recovery No scenarios Leak of EDC and by-products are assumed to give only local effects

1300 EDC purification

No scenarios Leak of EDC and by-products are assumed to give only local effects



Part of plant Scenarios included in the QRA

General assumption

1400 cracking Fuel gas considered

No scenarios for EDC/VCM/HCl according to comments

Release from crackers will be above auto ignition and a jet flame with local effects is assumed for all releases.

Gaseous release from top system with HCl, VCM and EDC assumed to only give local effects.

EDC is the main component in bottom system and refluxes and the same consequences as 100 % EDC (only local effects) are assumed

1500 VCM-purification

All liquid leaks considered (except for liquid in C1502 and EDC return)

Gaseous releases of pure HCl are considered

Leaks of EDC are assumed to only give local effects.

Gaseous releases of HCl/VCM/EDC mixtures are assumed to give only local effects

1600 direct chlorination

Leaks of C2H4 is considered

Leaks of Cl2 is considered

Leaks of EDC are assumed to only give local effects and no scenarios for EDC (incl. reactors V1601A/B (LTDC) and V1651 (HTDC)) are included in the calculations

1700 HCl-unit Fuel gas considered Leaks of chlorinated waste, fuel gas, HCl and NaOH solutions are assumed to give only local effects

1800-1900 waste water treatment

No scenarios No (or limited) hazardous substances

1800 incinerator Fuel gas considered Pressure in vents etc. is assumed to be ~ atmospheric and leaks are assumed to give only local effects

2700 EDC/VCM/by-product storage

VCM storage considered (liquid releases)

Leak of EDC and by-products are assumed to give only local effects

3000 Jetty 2 Loading/unloading of VCM considered (liquid releases)

The total annual time of operation for VCM loading arms are 115 hour per year

4.2 Scenarios for the new HTDC module All streams downstream the HTDC reactor consists of mainly EDC and some nitrogen. As stated in Table 4.1, leaks of EDC in area 1600 (Direct chlorination) are assumed to only give local effects and no scenarios for EDC are included in the risk evaluation. Neither is Nitrogen a hazardous substance in the context of the QRA. Hence, only leak from the feed lines of ethylene and chlorine, upstream the HTDC reactor (including process tie-ins), are evaluated as additional hazardous events in the update of the risk analysis for the VCM plant.



4.3 Scenarios for the new OHCL reactor The existing OHCL reactor (V1101) will be replaced by a new reactor (V1106) to allow for increased capacity. As stated in Table 4.1, leaks of EDC in area 1100 (Oxychlorination) are assumed to only give local effects and no scenarios for EDC, including the OHCL reactor V1101/V1106, are included in the calculations. Hence, replacement of the reactor itself does not cause any additional hazardous events. The ethylene and chlorine streams towards the existing OHCL reactor are already included in the risk model, however, process tie-ins to the new reactor will create additional leak potential and are therefore also evaluated in the update of the risk analysis for the VCM plant.

4.4 Risk screening of other North Star modifications A risk screening workshop was held at Rafnes to evaluate the potential risk contribution of each FTM in the context of the QRA. Representatives from Wood, INOVYN and LR were present at the workshop. In addition, two representatives from Bilfinger participated in the site walk through of the chlorine plant. The workshop participants are listed in Table 4.2.

Table 4.2 – Participant list for the risk screening workshop

Name Company

Kjetil Kristoffersen Wood

Roger M. Pettersen INOVYN

Øystein Palmgren INOVYN

Stian Jensen LR

Andrea Risan LR

Ingebjørg Valkvæ LR

Table 4.3 summarises the FTMs and their relevance to the QRA. A detailed evaluation of the FTMs and their risk contributions is documented in Appendix B and C.

Table 4.3 – Summary of risk evaluation of FTMs for the Chlorine and VCM plant

FTM No.

Area Scope description Medium Inclusion in QRA?

VCM plant

FTM 01 1100 Replacement of line 400-RP 1069 to DN500

EDC gas No

FTM 02 1100 V1105 modifications HCl gas Yes

FTM 03 1100 H1104 replacement HCl gas, condensate and steam

Yes

FTM 04 1100 Increase oxygen feed to OHCL with new heat exchanger H1151

Condensate, steam, N2, enriched air and LOX

No

FTM 05 1100 OHCL reactor cooling loop Boiler feed water

No

FTM 06 1000, 51 New IPS line to Chlorine plant Steam No

FTM 07 1300 P1305A/B/S replacement EDC gas No



FTM No.


FTM 08 Several Replacement of several control valves

Fuel gas, NaOH, Ethylene, Crude EDC liquid, EDC liquid, EDC/VCM/HCl condensate, VCM liquid

No

FTM 09 1100 V1102 Modification of demister Steam No

FTM 11 1400 Replacement of RP4015, RP4057 and RP4124

EDC gas, VCM, HCl

No

FTM 12 1400 New P1404S EDC liquid No

FTM 13 1400 New H1405C and new V1407 (new balcony on str. 6)

EDC/VCM/HCl condensate and cooling water

No

FTM 14 1400 Replacement of H1403 EDC/VCM/HCl gas

No

FTM 16 2700 Replacement of RP5081 EDC liquid No

FTM 17 1500 Replacement of valves on C1501 EDC/VCM liquid, EDC/VCM gas, steam, condensate

No

FTM 18 1500 DBB on C1502 EDC/VCM gas and liquid

Yes

FTM 19 1500 New H1541 with access platform EDC/VCM 2-phase

Yes

FTM 20 1500 Replacement of H1551 and increase diameter on RP5056 and RP5190

EDC, EDC liquid

No

FTM 21 1500 Install by-pass of H1512 EDC liquid No

FTM 22 1500 Replacement of H1510 Cooling water, VCM liquid

Yes

FTM 23 2700 Existing FTM (M50913-06) Replacement of P2752

EDC No

FTM 29 2700,1300 New impeller P1507 EDC No

FTM 31 Utility tie-ins Various Yes

FTM 32 Process tie-ins Various Yes

FTM 33 1800 Vent gas scrubber ANH Nitrogen No

FTM 34 1650 Analyser house modifications N/A No

FTM 35 Underground piping H2O No



FTM No.


FTM 36 1600 Pipe rack HTDC bridge N/A No

FTM 37 Fire and gas N/A Yes

FTM 38 1600,1800 New flame arrestor for HTDC Nitrogen, oxygen, ethylene

No

FTM 39 Fire water system

New fire water monitor H2O Yes

FTM 40 1100 Tie-in of new OHCL reactor and required modifications due to preservation of existing reactor

HCl, C2H4, EDC, Air

Yes

FTM 41 New HPN vessel for emergency purging

Nitrogen No

Chlorine plant

FTM 262 Cell room Installation of new electrolyser Brine, H2, Cl2, NaOH

Yes

FTM 361 Chlorine Increased capacity on chlorine cooler Cl2 gas Yes

FTM 366 Chlorine Increased capacity on chlorine compressor

Cl2 gas Yes

FTM 421 Hydrogen Increased capacity on hydrogen compressor

H2 Yes

5 Frequency analysis

Three leak scenarios (small leak, major leak and rupture) are typically defined for each segment, vessel, specific equipment and transport pipe. Table 5.1 below presents the method to calculate leak frequencies and representative equipment hole sizes for the different parts of the plant.

Note that calculated leak frequencies are presented in Appendix A. The different areas where the selected hazardous events are located are presented in Figure 5.1.

Table 5.1 – Method for calculating leak frequencies

Part of plant Method Reference

Chlorine plant – process segments

Leak frequencies and representative hole sizes are calculated using the LRC spreadsheet tool ULF (Utregning av Lekkasje Frekvenser).

The frequencies are based on Offshore statistics

ULF (Ref. /11/)

Offshore QRA – Standardised Hydrocarbon Leak Frequencies (Ref. /12/)

Chlorine plant –

Vessels and specific equipment

The scenarios and frequencies are calculated using the Hydro Handbook

HES-HB-002 (Ref. /13/)

VCM plant – process segments

Leak frequencies and representative hole sizes are calculated using the LRC spreadsheet tool ULF (Utregning av Lekkasje Frekvenser).


ULF (Ref. /11/)





VCM plant - Vessels and specific equipment

The scenarios and frequencies are calculated using the Hydro Handbook.

Loading arm frequencies are adjusted for estimated annual time of operation

HES-HB-002 (Ref. /13/)

Transport piping The scenarios and frequencies are calculated using the Hydro Handbook

HES-HB-002 (Ref. /13/)

Figure 5.1 – Illustration of location of hazardous events in QRA

6 Consequence analysis

Consequence modelling and risk calculations are performed using the software Safeti 8.11.

6.1 Event tree The event tree in Figure 6.1 illustrates the different outcomes a release of a hazardous substance may lead to. The outcome is a set of end events such as, e.g., fireball, jet fire or dispersion of toxic gases. Parameters and assumptions for the probability for each branch in the event tree are documented in Appendix A.

A BLEVE is an escalated event caused by an initial jet- or pool fire. If a pressurized vessel with liquefied gas is exposed to heat radiation it can lead to a BLEVE event with consequence of both a large fireball and explosion pressure from the expanding vapour. A BLEVE event may occur in the storage area for VCM if the deluge system fails on demand and no other cooling is applied during a severe fire in the area.



For INOVYN’s facility, the dimensioning events for the risk zones (cf. Figure 2.2) are dispersion of toxic gases (such as chlorine, ammonia and HCl) and fire exposure of VCM storage tanks leading to a BLEVE. This is further detailed in the subsequent section.

Figure 6.1 – Event tree

6.2 Fatality criteria The TNO probit functions are used as fatality criteria. These are inherent in the Safeti software.

The process involves several toxic chemicals, where the most severe are listed in Table 6.1. The table offers acute exposure guideline levels (AEGL) for life threatening health effects or death, as proposed by US EPA (https://www.epa.gov/aegl). It can be seen that fairly low concentrations may cause fatal consequences.

Table 6.1 – AEGL for airborne chemicals used in INOVYN’s process at Rafnes

Chemical AEGL 3 (10 min exposure limit) [ppm]

AEGL 3 (30 min exposure limit) [ppm]

AEGL 3 (60 min exposure limit) [ppm]

Chlorine (Cl2) 50 28 20

Hydrogen chloride (HCl)

620 210 100

Ammonia (NH3) 2700 1600 1100

6.3 Consequence modelling Consequences for the outcomes in the event tree are calculated with Safeti. Two examples of consequence computations are given below. The first example addresses a toxic release event and the second example is a consequence computation of a BLEVE event.

Figure 6.2 shows downwind distances to different levels of toxic lethality given a rupture of the piping/process equipment on the high pressure side of chlorine compressor #1 for wind conditions 2 m/s wind and Pasquille stability class F. The chlorine gas cloud with concentration corresponding to a toxic lethality of 1 extends approximately 180 m downwind of the rupture location. A toxic lethality of 0.001 may occur up to 1.2 km downwind of the rupture.



Figure 6.3 shows ellipses of lethality levels for a BLEVE event in the VCM storage area for wind conditions 2 m/s wind and Pasquille stability class F. Note that the consequence of BLEVE event is not sensitive to the wind speed. A lethality of 1 (100 % probability of fatality) occurs in a circle around the BLEVE event with a radius of approximately 400 m. The lethality is reduced to 0.01 in a circle with a radius of approximately 1.1 km.

Figure 6.2 – Toxic lethality footprint for a rupture of the piping/process equipment on the high pressure side of chlorine compressor 1 for wind conditions 2 m/s wind and Pasquille stability class F

Figure 6.3 – Lethality ellipses for a BLEVE fireball event in the VCM storage area for wind conditions 2 m/s wind and Pasquille stability class F



7 Risk picture and risk evaluation

The results from the QRA are presented as Location Specific Individual Risk (LSIR) contours, or simply risk contours, which allow comparison with the risk zones stipulated by DSB in "Tema 13" (Ref. /8/) as shown in Section 2.3.

The definition of LSIR is expressed as the frequency at which an individual may be expected to sustain a given level of harm from the realization of specific hazards. It is usually taken to be the risk of fatality, and normally expressed as risk per year. Individual risk is the risk experienced by a single individual in a given time period and reflects the severity of hazards and the amount of time the individual is exposed.

When calculating the risk, it is assumed that an individual is present at a particular location 24 hours per day, and 365 days per year.

Vulnerability of humans regarding exposure to toxic releases and from impact of heat loads are used to calculate the lethality from each branch in the event tree. To calculate the individual risk, all the resulting consequences are added for a given point and constitute the combined effect of the frequencies for loss of containment, atmospheric conditions, wind direction, and ignition probability.

The resulting risk contours for the facility including the North Star contribution are shown in the subsections below.

7.1 Total risk picture The combined risk contours for the chlorine and VCM plant are shown in Figure 7.1. The black lines represent each contour when the North Star modifications are included. An immediate observation is that the North Star project does not increase the risk for third parties considerably.

A few observations can be made when comparing the calculated risk to the RAC:

1. The RAC suggests that only the facility itself should be exposed to a risk of 1E-5 per year, with a possible exception for LNF areas. As seen in the figure, Noretyl’s premises and a part of what is denoted other industry lie within the contour of 1E-05 per year. One could argue that Noretyl and INOVYN is the same company with an integrated production. Then it would probably be acceptable that the 1E-5 per year contour expands into the Noretyl area. It is also noted that a public road is located within the risk contour of 1E-05 per year. DSB’s RAC suggests that public roads should be exposed to a risk below 1E-5 per year

2. Parts of the nearest residential area are located within the contour of 1E-06 per year. Permanent housing should primarily be located in the outer risk zone, but scattered houses may be acceptable under certain circumstances

3. The nearest vulnerable object, a school, is located outside the 1E-07 per year risk contour.

The North Star modifications do not cause any changes to the risk picture with respect to the acceptance criteria.



Figure 7.1 – Combined risk contours for the VCM and chlorine plant. The black lines represent each contour when the North Star modifications are included. The grey areas in the figure mainly indicate LNF areas

7.2 Risk from the chlorine plant The risk contribution from events in the chlorine plant, including transport piping of chlorine and hydrogen to the VCM plant, is shown in Figure 7.2.

The main contributors to the risk from the chlorine plant are leaks from piping/process equipment on the high-pressure side of chlorine compressor 1 and 2 (KLOR1-003 and KLOR2-003). The consequences of these events are larger than for leaks from low-pressure piping/equipment. These segments also have higher leak frequencies than e.g. the chlorine transport pipe to the VCM plant. The contributions from one of the segments are visualized in Figure 7.3.

The chlorine plant modifications have been included in the risk model by assuming an overall increased mass flow rate of 10 %. This increase is the cause of the delta risk due to the North Star modifications. However, the delta risk is close to negligible.



Figure 7.2 – Risk contribution from the chlorine plant

Figure 7.3 – Risk contribution from the segment after the chlorine compressor #1, Klor1-003.



7.3 Risk from the VCM plant The risk contribution from events in the VCM plant is shown in Figure 7.4. Here, as in the figures above, the black risk contours elucidate the increase in risk due to the North Star project. Again, the North Star contribution is modest. There are several events that contribute to the risk picture of the VCM plant. However, the main contributors to the risk are:

• BLEVE in the VCM storage area (the risk contribution is shown in Figure 7.5)

• Leaks from the HCl column V1501containing liquid HCl (the risk contribution is shown in Figure 7.6)

• Leaks from piping/process equipment with Cl and HCl, e.g.:

o The chlorine feed to the LTDC and HTDC modules (1600-Cl-017, 1600-Cl-HTDC). The risk is shown in Figure 7.7.

o The HCl feed to C1501 (1500-HCL-011). The risk is shown in Figure 7.8.

By comparing the below figures, it can be seen that BLEVE events has the longest reach in terms of exposure of adjacent land areas. As was calculated in the consequence section above (Section 6.3) the analysed BLEVE can cause a fatal exposure up to 1.1 km away from the VCM vessels.

Except for BLEVE events, toxic releases dominate the risk picture for the VCM plant. Releases of VCM, ethylene and EDC that ignites and leads to pool-, jet- or flash fires are less critical to the risk for third parties.

As an example of events that are not dimensioning for the risk zones, the risk associated with the vessel containing liquid ammonia (NH3), vessel V1012, is shown in Figure 7.9.

The main driver of the delta risk is the 10 % increase in overall mass flow rate. The additional feed lines of ethylene and chlorine to the new HTDC module and the additional leak points on existing segments do not contribute significantly to an increase in the overall risk.

Figure 7.4 – Risk contribution from the VCM plant



Figure 7.5 – Risk contribution from BLEVE events in the VCM storage area

Figure 7.6 – Risk contribution from major releases from the HCl column V1501. Release of liquid HCl



Figure 7.7 – Risk posed by the chlorine feed to the LTDC and HTDC modules

Figure 7.8 – Risk posed by the HCl feed line to the LTDC and HTDC modules. Release of HCl in liquid phase



Figure 7.9 – Risk contribution from the liquid ammonia vessel V1012

7.4 Individual risk at nearest resident To further substantiate the discussion above, individual risk due to both the VCM and chlorine plants is measured at two points located at the nearest residential houses as shown in Figure 7.10.

Figure 7.10 – Locations of the nearest residential houses



The total individual risk at the northernmost of the two locations is 2.88E-06 per year with the North Star project modifications included. The total risk before including the North Star modifications was 2.58E-06. Hence, the North Star modifications cause an increase in the total risk at this point of approximately 12 %. Table 7.1 present the largest contributors to the risk at this point before and after including the North Star modifications. The main risk drivers in this point are the chlorine piping segments. The modifications do not change the main risk drivers.

Table 7.1 – Risk contribution at resident location#1 before and after the North Star modifications are included

Model name Description Risk contribution

before North Star

Risk contribution after North

Star

Chlorine KLOR1-003 RU

Rupture of piping/process equipment on high-pressure side of chlorine compressor 1

36 % 35 %



36 % 35 %


Rupture of piping/process equipment on chlorine header from cell room 1

6 % 7 %


Rupture of piping/process equipment between chlorine dryer and compressor 1

6 % 6 %


Rupture of piping/process equipment on chlorine header from cell room 2

4 % 4 %


Rupture of piping/process equipment between chlorine dryer and compressor 2

3 % 4 %

The total individual risk at resident location #2 is 7.09E10-7 per year with the North Star project modifications included. The total risk before including the North Star modifications was 6.87E-07. Hence, the North Star modifications cause an increase in the total risk at this point of approximately 3 %. Table 7.2 present the largest contributors to the risk at nearest resident 2 before and after including the North Star modifications. The main risk driver in this point is a BLEVE event in the VCM storage area. When the mass flow rate in the piping/process equipment segments is increased due to the North Star modifications, the contribution to the total risk from the HCl column (V1501) becomes negligible compared to other segments.

Table 7.2 – Risk contribution at resident location #2 before and after the North Star modifications are included


before North Star


Star

BLEVE fireball VCM BLEVE in the VCM storage area 70 % 68 %



7 % 8 %



7 % 8 %




before North Star


Star

1500-HCl-011 RU Rupture of HCl feed to C1501 5 % 7 %

V1501 RU Rupture of HCl column V1501 4 % ~0 %

1600-Cl-017 RU Rupture of the chlorine feed to the LTDC module

2 % 4 %

8 Uncertainties

When performing a QRA of a complex industry facility, such as the chlorine and VCM plant at Rafnes, a number of uncertainties need to be handled. Three categories of uncertainties are discussed to present the major uncertainties of this study:

1. Uncertainties in parameters and data used as input and modelling assessments, e.g. duration of process leaks.

2. Uncertainties in modelling tools

3. Uncertainties related to hazards that are not included in the QRA – this could be hazards deliberately excluded or hazards that are not identified.

There is uncertainty in the use of generic leak scenarios and frequencies. The QRA cannot predict events that will happen in the plant. The uncertainties are controlled by using a large statistical basis for the generic data.

The applied modelling tool is a semi-empirical tool, and uses simplified mathematical equations representing experience of natural phenomena. The modelling tool is verified against large scale tests of releases of chemical substances. One example of uncertainty is that topography cannot be specifically modelled.

Leaks from EDC and mixtures with EDC as the main medium are excluded due to the assumption that release and possible ignition will only give local effects, i.e. within the plant boundary. A few test releases of EDC have been modelled, albeit not reported, and the gas dispersion distances have been found minimal. There is, however, a significant uncertainty regarding escalation and if a local fire in an EDC release can cause equipment failure and release of e.g. HCl or VCM.

9 Potential conservatism in the QRA

This section addresses potential conservatism embedded in the QRA. Note, however, that there are factors that may not be conservative, such as the exclusion of events with EDC.

9.1 Release durations and transient effects In general, for process leaks the durations are fixed to either 3 min or 10 min depending on the event. Also, the release rate is fixed for the duration of the event. For ruptures and large leaks, this can potentially be conservative. It is typically such events that contribute to the risk contours defining the risk zones. Hence, it could be worthwhile to investigate if transient effects introduce conservatism.

In order to do so, additional information (or assessment) is needed regarding process segmentation volumes, flow rates, detection time, initiation of emergency or process shutdown, isolation of segments, time for closing ESD/PSD valves etc.



9.2 Terrain effects Terrain effects, other than surface roughness, are not captured by the study. The terrain could potentially provide shielding for some adjacent areas for some of the accidental events (see Figure 9-1). Chlorine, for example, is a relatively heavy gas compared to air. Hence, it could be expected to follow the terrain in dispersion scenarios. On the other hand, chlorine is toxic at low concentrations (~50 ppm) and the terrain may not be that influential once the chlorine is diluted in air. Terrain effects can be addressed by, e.g., executing CFD simulations of a selected set of scenarios. In addition, the parameter value for surface roughness applied in the risk model is probably set in a conservative manner.

Figure 9.1 – Risk contours plotted on the terrain around INOVYN’s facility to illustrate the topography in the area

9.3 Release modelling The jet direction follows the wind direction in Safeti. This implies that the probability of jet to face the wind is not included. A jet facing headwind is likely to result in shorter hazard distances. In addition, all releases are modelled as free, i.e., as non-obstructed jets. In reality, some jets will be pointed downwards or into process equipment or other obstacles. This will reduce the momentum of the jet, leading to shorter hazard distances.

9.4 Event frequencies One could consider adapting the event frequencies for the facility, if INOVYN has historic data over accidental events.

9.5 BLEVE A major risk driver for the VCM plant is BLEVE events with the VCM storage tanks; cf. Figure 7.5 in Section 7.3. The BLEVE frequency is based on the fire frequency in the relevant area and a probability of failure on demand of the deluge system (see Appendix A). However, fire water can also be supplied by fire trucks and other means, which has not been credited. Also, the durations of the initial fires may be too short to cause a BLEVE. Hence, the BLEVE event frequency might be conservative, and could be investigated further in subsequent studies.

9.6 Flash fire envelope The main risk drivers are not flash fires. Still, there is some conservatism in the model with respect to how flash fire risks are modelled. The lethality range of a flash fire is linked to the extent of the 50%LFL cloud size. With the new QRA guidelines (Ref. /10/), this would typically be reduced to 100%LFL.



10 Conclusion and recommendations

10.1 Recommendations It is recommended to address potential conservatism in the risk model in the next revision of the QRA. Section 9 above lists some aspects to investigate in that respect. Following such an update one can look into potential risk reducing measures. For example, avoiding a BLEVE event is obviously important, and if there is a potential to reduce the risk of such an event, this could be addressed in the update. Risk reducing measures regarding toxic releases could also be discussed.

One new process module, the HTDC module, is installed as part of the North Star project. A measure to potentially reduce the probability of escalation from an accident in this module has been briefly discussed in this report, i.e. the cooling effect of fire water. If INOVYN is uncomfortable with this assessment, more detail studies can be executed to quantify the escalation potential.

For completeness, the recommendations from the existing QRA are included. These are:

• It is recommended to further develop and maintain systems and procedures to ensure fast detection and minimisation of duration of a release in case of an accidental scenario involving chlorine gas

• Emergency preparedness and quick notification (alarm) to the public to move indoors and close all doors and windows are essential to avoid severe 3rd party injuries, in case of a large toxic release

• INOVYN needs to make sure that the risk from the Chlorine and VCM plant are ALARP, As Low As Reasonably Practicable.

10.2 Conclusions Overall, the North Star project does not contribute with a significant risk increase compared to the existing risk picture at INOVYN’s facility at Rafnes. The main risk drivers remain unchanged from the existing QRA. Hence, toxic releases and BLEVE events in the VCM storage area dominate the risk picture and are dimensioning for the risk contours that will define the risk zones around the facility.

When comparing the calculated total risk picture for the chlorine and VCM plant at Rafnes against the DSB suggested RAC (Ref. /8/), the following are noted:

• Public roads and neighbouring industries are within the 1E-5 per year risk contour

• Parts of the neighbouring residential area are within the 1E-6 per year risk contour. However, scattered houses may be permitted within the 1E-6 per year risk curve under certain circumstances.

The North Star modifications do not cause any changes to the risk picture with respect to the suggested RAC.



11 References

/1/ Lloyd’s Register Consulting: "Total risk assessment (QRA) for the Chlorine ad VCM plant – INOVYN Norge AS, Rafnes", Report No. 105797/R1, Rev. Final, 15 September 2015

/2/ DSB: "Forskrift om håndtering av brannfarlig, reaksjonsfarlig og trykksatt stoff samt utstyr og anlegg som benyttes ved håndteringen (forskrift om håndtering av farlig stoff)", FOR-2009-06-08-602, 8 June 2009.

/3/ Lloyd’s Register Consulting: "Update of risk assessment for the tunnel between Rafnes and Herøya", Report No. 104947/R1, Rev. Final, 16 June 2015

/4/ Hydro Forskningssenter Porsgrunn: "Kvantitativ risikoanalyse – Hydro Rafnes", 91B.DZ8, 15.08.1991.

/5/ Hydro Forskningssenter Porsgrunn: "Oppdatering av kvantitativ risikoanalyse – Petrokjemi Rafnes", 98P_BA8.DOC, 22.01.1998.

/6/ Norsk Hydro: "Vurdering av dominoeffekter mellom fabrikkanleggene på Borealis AS, Noretyl AS og Hydro Polymers AS i forbindelse oppdatering av Sikkerhetsrapporten for Hydro Polymers og Noretyl", Report No. F75578-000, 28.09.2005.

/7/ DSB: "Forskrift om håndtering av brannfarlig, reaksjonsfarlig og trykksatt stoff samt utstyr og anlegg som benyttes ved håndteringen (forskrift om håndtering av farlig stoff)", FOR-2009-06- 08-602, 8 June 2009.

/8/ DSB Temaveileder: "Sikkerheten rundt anlegg som håndterer brannfarlige, reaksjonsfarlige, trykksatte og eksplosjonsfarlige stoffer: Kriterier for akseptabel risiko", May 2013.

/9/ Storulykkeforskriften FOR-2005-06-17-672, Council Directive 96/82/EC of 9 December 1996 on the control of major-accident hazards involving dangerous substances.

/10/ DSB: “Retningslinjer for kvantitative risikovurderinger for anlegg som håndterer farlig stoff”, LR report no. 106535/R1, 2017.

/11/ Lloyd’s Register Consulting: "ULF (Utregning av LekkasjeFrekvenser) ", Version 2015_v1.03

/12/ DNV: "Offshore QRA – Standardised Hydrocarbon Leak Frequencies", Report No./DNV Reg. No. 2008-1768/1241Y35-16 - Rev. 1, 2009-05-19.

/13/ Hydro: "Handbook of Risk Assessment", HES-HB-002, July 2000.



Appendix A

Assumptions and input data

Report no: PRJ11090011/R1 Rev: Final


Table of contents Page

1 Introduction A1

2 Selection of hazardous events A1

2.1 Scenario selection - general assumptions A1

2.2 Chlorine plant A3

2.2.1 Process piping and equipment A3 2.2.2 Vessels and specific equipment A3

2.3 VCM plant A4

2.3.1 Process piping and equipment A4 2.3.2 Vessels and specific equipment A5

2.4 Transport piping A6

3 Leak scenarios and frequency analysis A6

3.1 Chlorine plant segments A7

3.2 VCM plant segments A9

3.3 Storage and jetty A11

3.4 Transport piping A12

4 Operation and emergency shutdown A12

5 Area conditions A13

5.1 Wind conditions and distribution A13

5.2 Temperature and humidity A14

5.3 Topography and ground surface A14

6 Ignition model A14

6.1 Immediate ignition A15

6.2 Delayed ignition A15

6.2.1 Hydrogen A15 6.2.2 Flares and cracker furnaces A15 6.2.3 Cars A15 6.2.4 Factory areas A15 6.2.5 Ships at berth A15

6.3 Probability of explosion given ignition A16

7 Consequence analysis and risk calculations A16

7.1 Discharge and dispersion A16

7.2 Fire A17

7.2.1 Jet fire A17 7.2.2 Pool fire A17 7.2.3 Fire ball A17 7.2.4 Flash fire A17

7.3 Explosion A17

7.4 Human vulnerability A18

7.5 BLEVE A19

8 References A20

Report no: PRJ11090011/R1 Rev: Final Page Ai


1 Introduction

The purpose of this appendix is to document all the assumptions made to model all leak scenarios and perform calculations of consequences and risk for the INOVYN Chlorine and VCM plant at Rafnes.

This appendix also list the references used for the assumptions and input data.

2 Selection of hazardous events

The theory of QRA is that a selection of representative scenarios will form the basis for calculating the risk picture. The scenario selection is based on HAZID evaluations made in the previous QRA update performed for the Chlorine and VCM plant, Ref. /1/.

2.1 Scenario selection - general assumptions First a few general assumptions are made regarding the different parts of the Chlorine and VCM plant and the chemicals and mixtures in different steps of the production. The general assumptions are based on the overall process flow diagrams of the Chlorine and VCM plant. A summary of the general assumptions are presented in Table 2.1.

All parts of the plant are covered. For some parts of the plant there are no scenarios to be assessed due to no or less dangerous chemicals involved in that part of the process.

For other parts of the plant there are no scenarios to be assessed due to the fact that the consequence of the scenario will have no effect outside the defined part of the process. The consequence of a given scenario will have a local effect on the equipment or personnel present.

Table 2.1 – General assumptions regarding scenario selection

Part of plant Scenarios in the QRA General assumption

Chlorine plant

Water purification No scenarios No (or limited) hazardous substances

Brine No scenarios No (or limited) hazardous substances

Cell room Cl2 header in the cell room is considered

Leaks from individual cells and anolyte/ catolyte solutions are not considered to pose a threat outside the cell room.

Leak of H2 is assumed to give fire in the cell room with only local effects. Domino effects towards Cl2 system is considered negligible

Caustic soda No scenarios Leaks of NaOH solution is assumed to give only local effects

Hydrogen H2 header to VCM is considered

Leaks of H2 from compressors etc. are assumed to give only local effects.

Domino effects towards Cl2 system is considered negligible

Lean brine dechlorination

No scenarios Small amounts of Cl2, low pressures vacuum-0.2 bar(g) and leaks are assumed to give only local effects.

Leaks of anolyte solution is assumed to give only local effects

Report no: PRJ11090011/R1 Rev: Final Page A1



Emergency scrubber/recovery chlorine

If pumps P3704, P3706 stops while production trips

Pumps are connected to emergency power.

Small amounts of Cl2, low pressures vacuum-0.2 bar(g) and leaks are assumed to give only local effects

Chlorine All leak points of Cl2 gas are considered

Leak of H2SO4 is assumed to give only local effects.

No liquid Cl2 at any point assumed

VCM plant

1100 Oxychlorination

Leaks of C2H4 are considered.

Leaks of HCl are considered.

Leaks of H2 are considered.

NH3-tank considered

Leak of EDC (C2H4Cl2) is assumed to give only local effects and no scenarios for EDC (incl. reactor V1101/V1106 (OHCL)) are included in the calculations

1200 EDC-recovery No scenarios Leak of EDC and by-products are assumed to give only local effects

1300 EDC purification

No scenarios Leak of EDC and by-products are assumed to give only local effects

1400 cracking Fuel gas considered.

No scenarios for EDC/VCM/HCl according to comments

Release from crackers will be above auto ignition and a jet flame with local effects is assumed for all releases.

Gaseous release from top system with HCl, VCM, EDC assumed to only give local effects.

EDC are the main component in bottom system and refluxes and the same consequences as 100 % EDC (only local effects) are assumed

1500 VCM-purification

All liquid leaks considered (except for liquid in C1502 and EDC return).

Gaseous releases of pure HCl are considered

Leak of EDC is assumed to only give local effects.

Gaseous releases of HCl/VCM/EDC mixtures are assumed to give only local effects

1600 direct chlorination

Leaks of C2H4 are considered.

Leaks of Cl2 are considered

Leak of EDC is assumed to give only local effects and no scenarios for EDC (incl. reactors V1601A/B (LTDC) and V1651 (HTDC)) are included in the calculations

1700 HCl-unit Fuel gas considered Leaks of chlorinated waste, flue gas, HCl and NaOH solutions are assumed to give only local effects

1800-1900 waste water treatment

No scenarios No (or limited) hazardous substances

1800 incinerator Fuel gas considered Pressure in vents etc. is assumed to be ~ atmospheric and leaks are assumed to give only local effects




2700 EDC/VCM/By-product Storage

VCM storage considered (liquid releases).

BLEVE as a result of pool fire or jet fire considered

Leak of EDC and by-products are assumed to give only local effects.

Assumptions of likelihood and consequences for the BLEVE event are presented in Chapter 7.5

3000 Jetty 2 Loading/unloading of VCM considered (liquid releases)

The total annual time of operation for VCM loading arms are 115 hour per year

2.2 Chlorine plant

2.2.1 Process piping and equipment

Table 2.2 present the segments in the Chlorine process area. Parameters are taken from the process description of the chlorine systems 1 and 2.

Table 2.2 – Chlorine process plant segments included in QRA

Segment Flow ID Gas/liquid P (barg) T (oC) P&ID

Klor1-001 Wet chlorine Gas 0.239 88 06-CL-UDO-C78-00023

Klor1-002 Dry chlorine Gas 0.205 19 06-CL-UDO-C78-00024

Klor1-003 Chlorine compressor Gas 5.77 29.5 06-CL-UDO-C78-00044

Klor2-001 Wet chlorine Gas 0.183 81 6F-28002-3845

Klor2-002 Dry chlorine Gas 0.096 19 6F-28002-3846

Klor2-003 Chlorine compressor Gas 5.77 29.5 6F-28002-3847

2.2.2 Vessels and specific equipment

Table 2.5 present all vessels and specific equipment in the Chlorine plant.

Table 2.3 – Vessels and specific equipment

Vessel/ equipment

Media (gas/liquid)

P (barg) T (oC) P&ID

H3650 Cl2 (G) 0.239 88 06-CL-UDO-C78-00023

U3650 Cl2 (G) 0.239 18.5 06-CL-UDO-C78-00023

C3650 Cl2 (G) 0.205 19 06-CL-UDO-C78-00024

U3651 Cl2 (G) 0.205 13.8 06-CL-UDO-C78-00024

K3201 Cl2 (G) 5.77 29.5 06-CL-UDO-C78-00044

T3101 Cl2 (G) 0.183 81 6F-28002-3845

H3104-5 Cl2 (G) 0.183 81 6F-28002-3845

U3113 Cl2 (G) 0.183 19.6 6F-28002-3845



Vessel/ equipment

Media (gas/liquid)


C3110 Cl2 (G) 0.096 19.6 6F-28002-3846

U3127 Cl2 (G) 0.096 18.8 6F-28002-3846

K3206 Cl2 (G) 5.77 29.5 6F-28002-3847

2.3 VCM plant

2.3.1 Process piping and equipment

Table 2.4 present the segments in the VCM process area. Parameters are taken from mass balance sheets for the existing VCM plant and the new HTDC module.

Two new segments, 1100- C2H4-HTDC and 1600-Cl-HTDC, have been introduced as a result of installation of the new HTDC module.

Other segments that have been exposed to change due to the North Star modifications are listed below:

• 1100- C2H4-002: Change in operating pressure. Additional leak points due to process tie in of new HTDC module (including FTM 32)

• 1100-HCl-003: Additional leak points due to tie in of new OHCL reactor

• 1500-EDC/VCM-012: Additional leak points due to FTM 19

• 1600-Cl-017: Additional leak points due to process tie in of new HTDC module (including FTM 32).

Table 2.4 – Process segments


6F-28001

1100-H2-001 1110 Gas 10 90 11C

1100-C2H4-002 1101, 1102, 1103, 1104A, 1104 (including FTM 32 and part of HTDC module)

Gas 10 (1103) -10 (1103) 11C, 11E, 16A, 16B,

16E

1100-C2H4-HTDC

01C* Gas 2 (HTDC) ~0 (HTDC) 16E, 16F

1100-HCl-003 1107, 1108 (including inlet to new OHCL reactor)

Gas 7.4 180 11C, 11E, 11L

11/14/1500-HCl-004

1501, 1521, 1106 Gas 11.9 (1501)

-25 (1501) 11C, 14F, 15B

1500-HCl-011 C1501 reflux Liquid 17 -25 15A, 15B

1500-EDC/VCM-012

1502 (including FTM 19)

Liquid

(50% EDC/ 50% VCM)**

12.8 100 15A, 15C

1500-VCM-013 C1502 OVDH, C1504 OVDH

Gas 3.7 (C1502)

31 (C1502) 15C, 15D




6F-28001

1500-VCM-014 C1502 reflux Liquid 9 (1507) 23 (1507) 15A, 15C, 15D, 15G,

15H

1500-VCM-015 1508, 1509 Liquid 13.2 (1508)

33.4 (1508) 15G, 15H

1400-FG-016 Fuel gas system (composition: 66vol% Hydrogen 34 vol% methane)

Gas 3 40 14A/B/C

17B

18K, 18L

1600-Cl-017 1602 (including FTM 32 and part of HTDC module)

Gas 5.5 90 16A, 16B, 16E, 16N

1600-Cl-HTDC 02C* Gas 2 (HTDC) 20 (HTDC) 16E, 16F

2700-VCM-018 VCM storage and loading pumps and equipment in the storage area

Liquid Sat*** 10 27D/F/FA

2700-VCM-019 Liquid from VCM vapour recovery in storage area

Liquid Sat*** 10

* Streams from HTDC module Heat and Mass Balance

** Modelled as 100 % VCM

*** Saturation pressure for VCM at 10°C used in consequence calculation

2.3.2 Vessels and specific equipment

Table 2.5 present all vessels and specific equipment in VCM plant. Vessels and equipment with mainly EDC content are excluded according to the general assumption. Vessels with no liquid volume in normal operation are excluded.

Table 2.5 – Vessels and specific equipment

Vessel/ equipment

Media (gas/ liquid)

Liquid volume (m3)

max/operation


6F-28001

V1012 NH3 (L) 3.3/3 11 20 10QA

C1501 EDC/VCM (L)

(50% EDC/ 50% VCM)

109/15 11/11.4 -24/98 15A

V1501 HCl (L) 272/110 10.7 -25 15B

V1502 VCM (L) 21.2/10 3.7 38 15D

C1504 VCM (L) 28.4/7 4/4.3 41/47 15G

H1509 VCM (L) 0.22/0.15 3.3 16 15H

2708A/BC VCM (L) 395/100 Sat* 10 27C/D/E

2709 VCM (L) 5200/3500 Sat* 10 27F

2710 VCM (L) 5200/3500 Sat* 10 27G



Vessel/ equipment

Media (gas/ liquid)

Liquid volume (m3)

max/operation


6F-28001

X3002A/B VCM (L) - Ship pump pressure

4.5

10

* Saturation pressure for VCM at 10°C used in consequence calculation

2.4 Transport piping Assumptions regarding transport piping defined as separate segments are presented in Table 2.6.

Table 2.6 – Transport piping segments

Segment Length Dimension Gas/liquid P (barg) T (oC) P&ID

Cl2 header (replaces Stg14-34003-VCM2-5)

400 m 350 mm Gas 5.77 29.5 06-CL-UDO-C78-00026

H2 header(s) 150 mm Gas 6.5 15

VCM line from production to storage

100 mm Liquid 12.7 25 6F-28001-15H,-27C

VCM line from storage are to jetty

200 mm Liquid Ship pump

pressure

4.5

10

3 Leak scenarios and frequency analysis

Three leak scenarios, small leakage (SM), medium leakage (ME) and rupture (RU) are defined for each segment, vessel, specific equipment and transport pipe. These are the same definitions for leak scenarios used by Hydro in earlier risk assessments.

Table 3.1 below presents the method to calculate leak frequencies and representative hole sizes on equipment for the different parts of the plant.

Table 3.1 – Method for calculating leak frequencies


Chlorine plant – process segments

Leak frequencies and representative hole sizes are calculated using the LR spreadsheet tool ULF (Utregning av Lekkasje Frekvenser).


ULF (Ref. /2/)


Chlorine plant - Vessels and specific equipment

The scenarios and frequencies are calculated using the Hydro Handbook

HES-HB-002 (Ref. /4/)




VCM plant – process segments

Leak frequencies and representative hole sizes are calculated using the LR spreadsheet tool ULF (Utregning av Lekkasje Frekvenser).


ULF (Ref. /2/)


VCM plant - Vessels and specific equipment

The scenarios and frequencies are calculated using the Hydro Handbook.

Loading arm frequencies are adjusted for estimated annual time of operation

HES-HB-002 (Ref. /4/)

Transport piping The scenarios and frequencies are calculated using the Hydro Handbook

HES-HB-002 (Ref. /4/)

Note that even though the following FTMs for the North Star project were found relevant for the update of the QRA, the FTMs are evaluated to not have an impact on the leak frequency picture:

VCM plant: FTM 02, FTM 03, FTM 17, FTM 18, FTM 22, FTM 31, FTM 37, FTM 39 and FTM 40

Chlorine plant: FTM 262, FTM 361, FTM 366 and FTM 421

3.1 Chlorine plant segments Leak frequencies for the Chlorine plant segments are presented in Table 3.2. There is no change in leak frequency as a result of the North Star modifications. Hence, the leak frequencies are kept unchanged from the frequencies given in the QRA from 2015, Ref. /1/.

Table 3.2 – Chlorine plant leak scenarios and frequencies

Scenario Frequency Reference

Process piping and equipment

KLOR1-001 SM 8.68E-03

Leak frequency results for the Chlorine plant are implemented with calculations from the chlorine feed stream to the VCM plant, Ref. /1/ (Draft B update)

KLOR1-001 ME 2.14E-03

KLOR1-001 RU 3.44E-04

KLOR1-002 SM 8.68E-03

KLOR1-002 ME 2.14E-03

KLOR1-002 RU 3.44E-04

KLOR1-003 SM 8.68E-03

KLOR1-003 ME 2.14E-03

KLOR1-003 RU 3.44E-04

KLOR2-001 SM 8.68E-03

KLOR2-001 ME 2.14E-03

KLOR2-001 RU 3.44E-04

KLOR2-002 SM 8.68E-03

KLOR2-002 ME 2.14E-03

KLOR2-002 RU 3.44E-04

KLOR2-003 SM 8.68E-03




KLOR2-003 ME 2.14E-03

KLOR2-003 RU 3.44E-04


H3650 RU 2.00E-06

Pressurized vessels according to HES-HB-002 (Ref. /4/)

H3650 ME 1.00E-05

H3650 SM 1.00E-03

U3650 RU 2.00E-06

U3650 ME 1.00E-05

U3650 SM 1.00E-03

C3650 RU 2.00E-06

C3650 ME 1.00E-05

C3650 SM 1.00E-03

U3651 RU 2.00E-06

U3651 ME 1.00E-05

U3651 SM 1.00E-03

K3201 SM 6.00E-03

K3201 ME 2.00E-04

K3201 RU 2.00E-05

T3101 RU 2.00E-06

T3101 ME 1.00E-05

T3101 SM 1.00E-03

H3104-5 RU 4.00E-06

H3104-5 ME 2.00E-05

H3104-5 SM 2.00E-03

U3113 RU 2.00E-06

U3113 ME 1.00E-05

U3113 SM 1.00E-03

C3110 RU 2.00E-06

C3110 ME 1.00E-05

C3110 SM 1.00E-03

U3127 RU 2.00E-06

U3127 ME 1.00E-05

U3127 SM 1.00E-03

K3206 SM 6.00E-03

K3206 ME 2.00E-04

K3206 RU 2.00E-05



3.2 VCM plant segments Leak frequencies for the VCM plant segments have been updated according to the North Star modifications, and are presented in Table 3.3. The total percentage increase in leak frequency for the process piping and equipment is 9 %.

Table 3.3 – VCM plant leak scenarios and frequencies


Process piping and equipment

1100-H2-001 SM 3.75E-03

Calculation of leak points on P&ID and use of ULF (Ref. /2/) to calculate frequencies and representative hole sizes.

Offshore QRA – Standardised Hydrocarbon Leak Frequencies (Ref. /3/) reference for leak frequencies per equipment type.

1100-H2-001 ME 1.31E-03

1100-C2H4-002 SM 2.63E-02

1100-C2H4-002 ME 7.35E-03

1100- C2H4-002 ME 10 min 8.17E-03

1100- C2H4-002 RU 8.97E-04

1100- C2H4-HTDC SM 1.46E-03

1100- C2H4- HTDC ME 4.44E-04

1100- C2H4- HTDC ME 10 min 4.93E-05

1100- C2H4-002 RU 1.67E-05

1100-HCl-003 SM 1.36E-02

1100-HCl-003 ME 3.68E-03

1100-HCl-003 ME 10 min 4.09E-03

1100-HCl-003 RU 3.83E-04

11/14/1500-HCl-004 SM 1.65E-02

11/14/1500-HCl-004 ME 5.17E-03

11/14/1500-HCl-004 ME 10 min 5.74E-04

11/14/1500-HCl-004 RU 1.23E-03

1500-HCl-011 SM 1.11E-02

1500-HCl-011 ME 2.50E-03

1500-HCl-011 ME 10 min 2.78E-04

1500-HCl-011 RU 3.67E-04

1500-EDC/VCM-012 SM 1.36E-02

1500-EDC/VCM-012 ME 3.52E-03

1500-EDC/VCM-012 ME 10 min 3.91E-04

1500-EDC/VCM-012 RU 8.48E-04

1500-VCM-013 SM 6.22E-03

1500-VCM-013 ME 1.62E-03

1500-VCM-013 ME 10 min 1.80E-04

1500-VCM-013 RU 1.72E-04




1500-VCM-014 SM 3.86E-02

1500-VCM-014 ME 9.91E-03

1500-VCM-014 ME 10 min 1.10E-03

1500-VCM-014 RU 1.76E-03

1500-VCM-015 SM 1.58E-02

1500-VCM-015 ME 4.01E-03

1500-VCM-015 ME 10 min 4.45E-03

1500-VCM-015 RU 5.52E-04

1400-FG-016 SM 1.38E-02

1400-FG-016 ME 3.84E-03

1400-FG-016 ME 10 min 4.27E-04

1400-FG-016 RU 3.35E-04

1600-Cl-017 SM 1.44E-02

1600-Cl-017 ME 3.61E-03

1600-Cl-017 ME 10 min 4.01E-04

1600-Cl-017 RU 5.75E-04

1600-Cl-HTDC SM 1.51E-03

1600-Cl- HTDC ME 4.54E-04

1600-Cl- HTDC ME 10 min 5.04E-05

1600-Cl- HTDC RU 1.80E-05


V1501 RU 2.00E-06


V1501 ME 1.00E-05

V1501 SM 1.00E-03

C1501 RU 2.00E-06

C1501 ME 1.00E-05

C1501 SM 1.00E-03

V1502 RU 2.00E-06

V1502 ME 1.00E-05

V1502 SM 1.00E-03

C1504 RU 2.00E-06

C1504 ME 1.00E-05

C1504 SM 1.00E-03



3.3 Storage and jetty Leak frequencies for the storage and jetty segments are presented in Table 3.4. There is no change in leak frequency as a result of the North Star modifications.

Table 3.4– Storage and jetty (VCM) leak scenarios and frequencies


2708A/B/C RU 6.00E-06


2708A/B/C ME 3.00E-05

2708A/B/C SM 3.00E-03

2709/10 RU 4.00E-06

2709/10 ME 2.00E-05

2709/10 SM 2.00E-03

X3002A/B RU 3.54E-06

Loading arm according to HES-HB-002 (Ref. /4/)

X3002A/B RU 10 min 3.94E-07

X3002A/B ME 3.60E-05

X3002A/B ME 10 min 3.94E-06

X3002A/B SM 3.94E-04

2700-VCM-018a SM 2.98E-02

Calculation of leak points on P&ID and use of ULF (Ref. /2/) to calculate frequencies and representative hole sizes

Offshore QRA – Standardised Hydrocarbon Leak Frequencies (Ref. /3/) reference for leak frequencies per equipment type

2700-VCM-018a ME 7.21E-03

2700-VCM-018a ME 10 min 8.01E-04

2700-VCM-018a RU 7.70E-04

2700-VCM-018a RU 10 min 8.56E-05

2700-VCM-018b SM 9.33E-03

2700-VCM-018b ME 2.11E-03

2700-VCM-018b ME 10 min 2.35E-04

2700-VCM-018b RU 2.20E-04

2700-VCM-018b RU 10 min 2.45E-05

2700-VCM-019b SM 1.70E-02

2700-VCM-019b ME 3.82E-03

2700-VCM-019b ME 10 min 4.24E-04

2700-VCM-019b RU 4.02E-04

2700-VCM-019b RU 10 min 4.47E-05



3.4 Transport piping Leak frequencies for the transport piping segments are presented in Table 3.5. There is no change in leak frequency as a result of the North Star modifications.

Table 3.5 – Transport piping leak scenarios and frequencies


Cl2 header RU 6.68E-09 /m

Pipeline (transport) according to HES-HB-002 (Ref. /4/)

Cl2 header ME 2.00E-07 /m

Cl2 header SM 6.68E-07 /m

VCM header RU 2.00E-08 /m

VCM header ME 5.40E-07 /m

VCM header ME 10 min 6.00E-08 /m

VCM header SM 2.00E-06 /m

H2 header RU 2.00E-08 /m

H2 header ME 6.00E-07 /m

H2 header SM 6.00E-07 /m

VCM jetty header RU 6.00E-09 /m

VCM jetty header RU 10 min 6.67E-10 /m

VCM jetty header ME 1.80E-07 /m

VCM jetty header ME 10 min 2.00E-08 /m

VCM jetty header SM 6.67E-07 /m

4 Operation and emergency shutdown

Assumptions regarding operation of the Chlorine and VCM plant and time for shut down are summarized in Table 4.1.

Table 4.1 – Operation and ESD assumptions

Parameter Assumption/estimate Comment

Plant in operation It is assumed the Chlorine and VCM plant is in operation 8,760 hours per year

Start and shutdown, maintenance etc. are included in operation

VCM loading/ unloading frequency

VCM is loaded/unloaded at jetty 2 approx. 1,152 hours/year

Used to adjust leak frequencies for loading/ unloading scenarios

Total time of ship at berth at jetty 2

Jetty 2 is occupied approx. 3,336 hours/year

Used for estimate of probability of ignition at Jetty 2

ESD Chlorine plant – Time for shutdown

(also applies for chlorine and hydrogen transport piping)

Small leaks – 10 min

Major leaks – 3 min

Ruptures – 3 min

Detector pick up but no automatic shutdown.

Pressure drop and automatic shutdown.

Pressure drop and automatic shutdown



Parameter Assumption/estimate Comment

ESD VCM Plant Cl2, C2H4, VCM – Time for shutdown

Small leaks - 10 min

Major leaks – 3 min 90 %, 10 min 10 %

Ruptures – 3 min

Detector pick up but no automatic shutdown.

Disturbance trigger automatic shut down in 90 % of the cases, in 10 % of the cases manual shutdown after 10 min is assumed.

All ruptures are assumed to lead to a disturbance with automatic shutdown

ESD VCM Plant HCl Small leaks – 30 min

Major leaks - 3 min 90 %, 10 min 10 %

Ruptures 3 min

No HCl detectors

Disturbance trigger automatic shut down in 90 % of the cases, in 10 % of the cases manual shutdown after 10 min is assumed.

All ruptures are assumed to lead to a disturbance with automatic shutdown

ESD VCM storage area

(also applies for VCM line from production to storage area)

Small leaks - 10 min

Major leaks – 3 min 90%, 10 min 10%

Ruptures – 3 min 90%, 10 min 10%

Detection at PPM level and all leaks will be detected. For small leaks operator need to go out and check. Major leaks and ruptures are assumed to be able to detect on camera and shutdown within 3 min in 90 % of the cases

ESD vessels Release of whole liquid content

ESD loading/ unloading – Time for shut down

(also applies for transport piping between jetty and storage)

Small leaks – 3 min 90 %, 10 min 10 %

Major leaks – 3 min 90 %, 10 min 10 %

Ruptures – 3 min 90 %, 10 min 10 %

Loading/unloading is supervised and manual shutdown is assumed within 3 min 90 % of the cases.

In 10 % of the cases it is assumed that supervisor is compromised and manual shutdown instead takes 10 min

5 Area conditions

5.1 Wind conditions and distribution Three different weather scenarios are assumed to represent the actual weather conditions at Rafnes:

• 2 m/s with Pasquille stability class F

• 2 m/s with Pasquille stability class D

• 6 m/s with Pasquille stability class D.

The distribution of wind speed and directions is based on wind data from eKlima.no (Ref. /5/) covering the last 10 years of observations from Porsgrunn - Ås. Figure 5.1 presents the wind rose for the weather station at Porsgrunn - Ås. Statistics for 12 wind sectors of 30° and 4 m/s parts has been used. Wind speeds of 0-4 m/s are represented by 2 m/s wind speed and wind speeds above 4 m/s are represented by 6 m/s.



Figure 5.1 – Wind rose for Porsgrunn – Ås

For stability class it is assumed that class F is prevailing for 40 % of the time for 0-4 m/s and class D for 60 % of the time for 0-4 m/s and 100% of the time for wind speeds > 4 m/s. Pasquille class distribution is based on stability class data from Porsgrunn - Ås as documented in the 1991 QRA report for Rafnes (Ref. /7/).

5.2 Temperature and humidity Air temperature and ground temperature is set to 10°C and a relative air humidity of 70 % are assumed in all cases (Ref. /7/).

5.3 Topography and ground surface The topography and ground surface is represented by surface roughness parameter of 0.1 representing a surface height of 182.6 mm according to 1991 QRA report for Rafnes (Ref. /7/). The surface roughness parameter is used by Phast Risk to model ground surface turbulence and the impact on gas dispersion (Ref. /6/).

6 Ignition model

The ignition model applies to leak scenarios for flammable substances (H2, C2H4, VCM and Fuel Gas).

The assumed ignition model is a combination of the assumptions from the 1991 QRA (Ref. /7/), the risk based explosion load calculations for Noretyl (Ref. /8/) and new assumptions for cracker furnaces, ships at berth and electrical high voltage cable and flares.



6.1 Immediate ignition The probability (Pi) of a release of H2 being ignited immediately in the event of the release is assumed to be 0.05 (Ref. /9/)

The probability (Pi) of a release of C2H4 and VCM being ignited immediately in the event of the release is assumed to be (Ref. /9/):

• Pi = 1 for release over auto ignition temperature

• Pi = 0.007 for releases from a pump

• Pi = 0.00015 for all other cases.

6.2 Delayed ignition The delayed ignition model in Phast Risk is based on the formula:

Pi,t = fi(1-e-ωit)

Pi,t = Probability of ignition by source i in the duration of time step t

fi = Operating probability of source i, (i.e. if the ignition source only is present part of the time)

ωi = Effectiveness factor for ignition source i

t = Duration of time step.

6.2.1 Hydrogen

For all hydrogen releases the ignition probability is adjusted so that total ignition probability always reaches 1.

6.2.2 Flares and cracker furnaces

Flares and cracker furnaces are defined as point sources with effectiveness factor = ∞ and operating probability 100 % giving 100 % ignition if a flammable gas cloud reaches the point source. The flare is assumed to be elevated to 70 m above ground.

6.2.3 Cars

A car running is assumed to have a 40 % probability of ignition in 60 s (Ref. /10/). The operating probability is dependent on traffic density (number of cars and speed). Numbers from the explosion analysis (Ref. /8/) are used for defining ignition from cars near the INOVYN plant and figures from vegvesen.no (Ref. /11/) is used for FV 353. The traffic density is presented in table. Only total number of cars is used and no detailed analysis of differences between day, night and weekends are assumed.

Table 6.1 – Traffic density around Noretyl

Road Number of cars per day Assumed speed

Main road Rafnes 226 40 km/

FV 353 3700 70 km/h

6.2.4 Factory areas

In accordance with the 1991 QRA ignition areas are defined for the Chlorine plant, VCM plant and Noretyl plant. The ignition probability is assumed to be 75 % in 60 s and the operating probability 20 %. The probability is based on an area of 25 m x 25 m (625 m2).

6.2.5 Ships at berth

The probability of a gas cloud being ignited if it spreads to a ship is assumed to be 50 % in 60 s. Only ships at berth at jetty 2 are considered as ignition sources. The operating probability is equal to the discharge and loading times used for leak frequencies.



6.3 Probability of explosion given ignition The probability of explosion (Pe) given ignition depends on the volume of the flammable part of a gas cloud on ignition and the laminar burning velocity of the flammable material according to Table 6.2 (Ref. /12/).

Table 6.2 – Volume based probability of explosion

Obstructed cloud volume

Pe low flame speed (< 0.45 m/s)

Pe medium flame speed (0.45 m/s - 0.75 m/s)

Pe high flame speed (> 0.75 m/s)

H2,C2H4

200 m3 0 0.3 0.6

3,000 m3 0.3 0.6 0.9

6,000 m3 0.6 0.9 1

7 Consequence analysis and risk calculations

7.1 Discharge and dispersion The leak rates and dispersion of gas/vapours from the defined leak scenarios are calculated in SAFETI.

The 10 % increase in overall mass flow rate, due to the North Star project, is accounted for by increasing the pressure in process piping and equipment segments by 10 % and the inflow rate for long pipeline segments by 10 %.

The leak models used for the study are summarized in Table 7.1.

Table 7.1 – SAFETI models used

Scenarios Leak model in SAFETI Comment

All small and medium leaks (both liquid and gas)

Leak Constant leak rate with full pressure maintained.

VCM vessels are modelled with a fixed volume (maximum leak duration is 1 hr).

Process piping and equipment and chlorine vessels are modelled as fixed duration leaks according to the emergency shut down philosophy in chapter 4.

Ruptures from liquid process equipment

Leak Constant leak rate with full pressure maintained:

• Fixed duration leaks according to the emergency shut down philosophy in chapter 4.

• Maintaining full pressure is regarded conservative

• on the other hand the model assumes no back flow from equipment downstream rupture

Ruptures from vessels with liquid

Catastrophic rupture Instantaneous release of full content



Scenarios Leak model in SAFETI Comment

Ruptures from liquid VCM transport piping between plant and storage and to jetty

Line rupture Average leak rate over the duration (3 min) used.

Rupture on chlorine feed to 1600 (1600-Cl-017 RU and 1600-Cl-HTDC RU)

Long pipeline

• Distance to break 400 m and 200 m respectively*

• Inflow of 10.3 kg/s

Average leak rate over the duration (3 min) used

Rupture on chlorine header

Long pipeline

• Inflow 10.3 kg/s

• Distance to break 200 m

Average leak rate over the duration (3 min) used.

Rupture on hydrogen header

Line rupture Average leak rate over the duration (3 min) used

Rupture on chlorine segments

Long pipeline

• Inflow 4.7 kg/s for vessels and 5.2 kg/s for piping and equipment (10% increase)

• Distance to break 10 m*

Average leak rate over the duration (3 min) used.

* Assumed length of pipelines

7.2 Fire

7.2.1 Jet fire

A jet fire occurs if an ongoing continuous release of flammable substance is ignited. The extent of the jet is assumed to be to the stoichiometric concentration of the release.

7.2.2 Pool fire

A pool fire occurs if there is a pool of flammable material is present on ignition (the pool needs to be in contact with the ignited flammable vapour).

7.2.3 Fire ball

A fire ball occurs on immediate ignition of an instantaneous release (or as a short duration effect of a continuous release) of flammable substance.

7.2.4 Flash fire

A flash fire occurs if a flammable gas cloud is ignited. The extent of the gas cloud is assumed to be to half LFL to take into account the nonconformities in the gas cloud. Ignition can also lead to additional explosion effects (see Chapters 6.3 and 7.3)

7.3 Explosion Vapour cloud explosions are modelled in Phast Risk using the TNO – Multi Energy Method (ME). Two categories of explosion are modelled:



1. Confined vapour cloud explosion

2. Unconfined vapour cloud explosion

Confined explosions are assumed to be able to happen in the VCM plant process area where flammables are present and process equipment creates volumes of congestion. Two volumes are defined according to figure. Explosion within these volumes are calculated using ME curve number 5.

7.4 Human vulnerability The assumed vulnerability of humans exposed to fire and explosion are according to Table 7.2. The assumptions is based on an unprotected person located outdoors (Ref. /13/).

Table 7.2 – Human vulnerability on exposure (outdoor vulnerability)

Effect Probability of death (P)

Flash fire P = 1 within flammable envelope

Fire radiation dose (time t in s and heat radiation/ area q in W/m2)

P = Probit function of Pr

Pr = -36.38 + 2.56·ln(t·q·1.333)

Explosion (side on pressure in barg) P = 0 for p < 0.3 barg

P = 1 for p > 0.3 barg

Chlorine toxic dose (concentration c in ppm and time t in minutes)


Pr = -4.81 + 0.5·ln(t·c^2.75)

Hydrogen chloride toxic dose (concentration c in ppm and time t in minutes)


Pr = -15.69 + 1.69·ln(t·c^1.18)

Figure 7.1 – Obstructed regions (congested areas) in the VCM plant

For unconfined explosion ME curve number 2 is chosen.



7.5 BLEVE The BLEVE event can happen in case of jet fire or large pool fire in the storage area and if the deluge system fails on demand.

The likelihood of a BLEVE is calculated using the SAFETI risk calculations for jet fire and pool fire outcomes from releases of VCM in the storage area = 8·10-4 (all ignited rupture and medium leak scenarios in storage area contributes). A generic probability of failure on demand for fire proofing is according to CCPS (Ref. /14/) in the order of 10-2 and multiplying that factor to the jet fire and pool fire frequencies sets the frequency of a BLEVE event in the storage area.

BLEVE frequency = 8·10-6

A BLEVE scenario is simulated using a fireball and an explosion event in parallel.

Vessel volume = 5,000 m3

Stored liquid volume = 3,500 m3

Pressure at time of BLEVE = 1.21 x PSV set point (absolute pressure) (Ref. /10/) = 8.92 bar(g)

Liquid fraction on release = 0.73 (calculated using SAFETI for release of VCM at 8.92 bar(g))



8 References

/1/ Lloyd’s Register Consulting: «Total risk assessment (QRA) for the Chlorine ad VCM plant – INOVYN Norge AS, Rafnes», Report No. 105797/R1, Rev. Final, 15 September 2015

/2/ Lloyd’s Register Consulting: «ULF (Utregning av LekkasjeFrekvenser)», Version 2015_v1.03

/3/ "Offshore QRA – Standardised Hydrocarbon Leak Frequencies", Report No./DNV Reg. No. 2008-1768/1241Y35-16 - Rev. 1, 2009-05-19.

/4/ "Handbook of Risk Assessment", HES-HB-002, Hydro, July 2000.

/5/ eklima.no, Norwegian Meteorological Institute, 2014-07-02.

/6/ "Unified Dispersion Model (UDM) Theory", DNV Software, June 2011.

/7/ Hydro Forskningssenter Porsgrunn: "Kvantitativ risikoanalyse – Hydro Rafnes", 91B.DZ8, 15.88.1991.

/8/ Scandpower AS: "Risk-based Calculations of (Design) Explosion Loads on manned Buildings – Rafnes", Report No. 80.102.017/R2, 24 September 2009.

/9/ Lloyd’s Register Consulting: “Modelling of ignition sources on land based process facilities operated by Statoil”, Report No. 103381/R1, 24 October 2014.

/10/ RIVM: "Reference Manual Bevi Risk Assessments", Version 3.2, 2009-07-01.

/11/ https://www.vegvesen.no/vegkart/vegkart/, 2014-07-02

/12/ "MPACT Theory", DNV Software, December 2010.

/13/ "Methods for the determination of possible damage", CPR 16E, TNO, 1992.

/14/ “Layer of Protection Analysis”, CCPS Concept Book, CCPS, 2001.



Appendix B

Risk screening workshop - VCM plant

Page B1 Report no: PRJ11090011 Rev: Final


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Memo

Risk screening workshop - VCM scope

To: Wood Cc:

From: Ingebjørg Valkvæ/Andrea Risan/

Stian Jensen/Ane Kristiansen

Date: 30 November 2018

Project no: PRJ11090011

Table of Contents 1 Introduction ..................................................................................................................................... 3

2 Process description .......................................................................................................................... 4

3 VCM plant modifications ................................................................................................................. 5

3.1 FTM 01 - Replacement of line 400-RP 1069 to DN500........................................................... 6

3.2 FTM 02 - V1105 modifications .............................................................................................. 6

3.3 FTM 03 - H1104 replacement ................................................................................................ 6

3.4 FTM 04 – Increase oxygen feed to OHCL with new heat exchanger H1151 ........................... 7

3.5 FTM 05 – OHCL reactor cooling loop ..................................................................................... 8

3.6 FTM 06 – New IPS line to Chlorine plant ................................................................................ 8

3.7 FTM 07 - P1305A/S replacement ........................................................................................... 8

3.8 FTM 08 - Replacement of several control valves ..................................................................... 9

3.9 FTM 09 - V1102 Modification of demister ............................................................................. 9

3.10 FTM 11 - Replacement of RP4015, RP4057 and RP4124 ......................................................10

3.11 FTM 12 - New P1404S .........................................................................................................10

3.12 FTM 13 - New H1405C and new V1407 (new balcony on str. 6) .........................................11

3.13 FTM 14 - Replacement of H1403 .........................................................................................11

3.14 FTM 16 – Replacement of RP5081 .......................................................................................12

3.15 FTM 17 – Replacement of valves on C1501 .........................................................................12

3.16 FTM 18 – DBB on C1502 .....................................................................................................12

3.17 FTM 19 – New H1541 with access platform ........................................................................13

3.18 FTM 20 – Replacement of H1551 and increase diameter on RP5056 and RP5190 ...............13

3.19 FTM 21 – Install by-pass of H1512 .......................................................................................13

3.20 FTM 22 – Replacement of H1510 ........................................................................................14

3.21 FTM 23 – Existing FTM (M50913-06) Increase capacity of P2752 .........................................14

3.22 FTM 29 – New impeller P1507 (reduce efficiency requirement) ............................................14

3.23 FTM 31 – Utility tie-ins .........................................................................................................16

Memo: Risk screening workshop - VCM scope Page 1 of 23

Date: 30 November 2018 ©Lloyd’s Register 2018

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3.24 FTM 32 – Process tie-ins ......................................................................................................16

3.25 FTM 33 – Vent gas scrubber ANH ........................................................................................16

3.26 FTM 34 – Analyser house modifications ...............................................................................17

3.27 FTM 35 – Underground piping ............................................................................................17

3.28 FTM 36 – Pipe rack HTDC bridge .........................................................................................18

3.29 FTM 37 – Fire and gas .........................................................................................................18

3.30 FTM 38 – New flame arrestor for HTDC ...............................................................................18

3.31 FTM 39 – New fire water monitor ........................................................................................19

3.32 FTM 40 – Tie-in of new OHCL reactor and required modifications due to preservation of existing reactor ..............................................................................................................................20

3.33 FTM 41 – New HPN vessel for emergency purging ...............................................................20

4 Summary .......................................................................................................................................21

5 References .....................................................................................................................................23



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1 Introduction

INOVYN operates a vinyl chloride monomer (VCM) and chlorine plant at the Rafnes industrial area, marked in Figure 1.1. At present, the implementation of several modifications to the facility is ongoing as part of the North Star project. Of special interest for the risk analysis work, which LR is contracted to, is:

• a new HTDC module and

• a new OHCL reactor

The HTDC module is a new module at INOVYN. It is expected to have a footprint of approximately 28 m x 8 m with three levels. The module is relatively congested with process equipment and reactors.

The OHCL reactor replaces an existing reactor. This will increase both the flow throughput and the volume of the reactor.

In addition to the new HTDC module and new OHCL reactor, several minor modifications are planned for the plants. In order to ensure that all risk contributors associated with the project are accounted for in the QRA update, a one-day workshop was held at Rafnes with a scope including up to 40 modifications. In the workshop, Wood and INOVYN presented the various modifications and replacements planned for the VCM plant. The workshop also included a guided tour around the plant.

This memo presents the planned minor modifications (FTMs – “Forslag til modifikasjoner”) for the VCM plant with a comment on their potential as risk contributors in the context of the QRA. The QRA focus on the “delta” risk, i.e. increase or decrease in risk potential of implementing the FTM. As an example, if a new valve replaces an existing valve, the delta risk is assessed to be negligible. However, if new valves are installed or if pipes are replaced with larger ones, increasing the volume of hazardous material, the risk potential will increase. The modifications with a considerable delta risk potential will be passed on to the QRA update activity.

The selection of modifications to be included in the QRA is based on the information from the Risk screening workshop and general assumptions made in the previous QRA performed for INOVYN Chlorine and VCM plant in 2015 (Ref. /1/)



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Figure 1.1 – Overview of the Rafnes industrial area. The VCM and chlorine plants are highlighted in orange

2 Process description

VCM is produced from the intermediate substance EDC. The EDC is produced in two separate processes in the VCM plant. The first process is by direct chlorination, using ethylene gas from Noretyl and chlorine gas from the chlorine plant. The second is by oxychlorination, using hydrogen chloride, hydrogen gas, ethylene gas and air. The EDC from the direct chlorination and oxychlorination is purified (distilled to remove light and heavy bi products) and intermediately stored before being sent to the cracking furnaces.

VCM is produced by cracking EDC to VCM and HCl at a temperature of approx. 500 °C and 20 bar(g) pressure. The gas out of the cracking furnaces still holds a large amount of EDC and a number of steps are needed to separate VCM, HCl and EDC from the raw gas. In a number of steps the EDC is condensated out by cooling and HCl stripped off by reducing the pressure. Finally a distillation process removes the last traces of HCl and EDC and by-products from VCM. The pure VCM is stored as liquid in pressurized spherical tanks before being offloaded by ship or pumped through piping under the Frierfjord to INOVYN Norge PVC plant at Herøya.

Utility systems include steam and condensate system, cooling water system, waste water treatment, incinerators for vented gases and fuel gas system.

The VCM plant is divided into process area, tank farm, control centre, flare and quay. Production, as well as sewage treatment and combustion of bi-products, takes place in the process area. The process area is further divided into a number of plant areas as listed below:

• 1100 - Oxychlorination

• 1200 - EDC-recovery

• 1300 - EDC purification

• 1400 - Cracking

• 1500 - VCM-purification

• 1600 - Direct chlorination

• 1700 - HCl-unit



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• 1800-1900 - Waste water treatment

• 1800 - Incinerator

• 2700 - EDC/VCM/by-product storage

• 3000 - Jetty 2

3 VCM plant modifications

The FTMs for the VCM plant are presented in the following sections. Each FTM is presented with area, medium, description and risk evaluation. Locations of the different FTMs in the VCM plant are shown in Figure 3.1.

Note that the following FTMs were voided prior to, or after, the Risk screening workshop and will not be a part of the QRA scope:

• FTM 10

• FTM 15

• FTM 24

• FTM 25

• FTM 26

• FTM 27

• FTM 28

• FTM 30

Figure 3.1 - VCM plant - Location of FTMs



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3.1 FTM 01 - Replacement of line 400-RP 1069 to DN500 Area: 1100

Medium: EDC gas

Description

Line RP1069 connects the overhead of Oxy hot quench column, C-1101, to the crude EDC condensers, H1106 A/B. The linear velocity in this line will be too high following the VCM production increase, and it must be increased to DN500. The material in the line is SAF2507, this shall be kept. Temperature measurement TI1406 and pressure transducer PT1106 are installed on the line; these functions must be maintained in the new line. The outlet nozzle on C-1101 is DN 500, i.e. no modifications to the nozzle. The inlet nozzles on H1106A is DN600, i.e. the existing 400/600 expander must be replaced by a 500/600.

Risk evaluation

The line replacement reduces the amount of potential leak sources, but increases the mass flow and segment volume due to increased line diameter.

However, it is assumed that leaks of EDC will only give local effects, Ref. /2/. Hence, FTM 01 will not be included in the QRA.

Inclusion in QRA: No

3.2 FTM 02 - V1105 modifications Area: 1100

Medium: HCl gas

Description

Acetylene hydrogenation reactor V1105 should be modified to take a higher catalyst loading to allow the increase throughput. An insert is welded to the existing DN250 inlet nozzle in accordance to the recommendations from OxyVinyls and the internal grid is removed to allow increased catalyst inventory.

Risk evaluation

The modification does not impart any new potential leak sources, but the mass flow will increase.

Based on previous evaluations (Ref. /2/) leaks of HCl in area 1100 will be included in the QRA.

Inclusion in QRA: Yes

3.3 FTM 03 - H1104 replacement Area: 1100

Medium: HCl gas, condensate and steam

Description

Existing HCl preheater, H1104, is too small for the increased throughput and must be replaced. HCl outlet pipe, 250-RP1014-A25 shall be increased to DN300 up to NRV1014 Increased diameter on MPS feed nozzle, DN80 feed line expanded to DN100 Minor modifications to steam trap on condensate outlet from H1104.



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Risk evaluation

The replacement of H1104 and related modifications will lead to an increased mass flow and increased segment volume.

Based on previous evaluations (Ref. /2/) leaks of HCl in area 1100 will be included in the QRA.


3.4 FTM 04 – Increase oxygen feed to OHCL with new heat exchanger H1151 Area: 1100

Medium: Condensate, steam, N2, enriched air and LOX

Description

The increased HCl conversion in the oxychlorination section will be covered by increased oxygen enrichment of the air feed. The air compressor does not have any spare capacity. Oxygen will be supplied by the same means as currently, i.e. from evaporation of liquid oxygen (LOX). The LOX will be supplied by AGA, or another supplier, by trucks to the LOX unit outside the plant fence at Rafnes. The oxygen evaporator (E3902) in the LOX unit has sufficient capacity for the increased consumption of oxygen.

The scope of the FTM is:

• Remove existing oxygen feed line to VCM plant

• Install oxygen preheater, H1151, below Structure 2 in the VCM plant. Heating medium is MPS. Heat required: 90 kW

• Install a DN80 oxygen line from E3902 to H1151

• Install a DN100 line from H1151 to the air feed line to the oxychlorination reactor

• Reroute the condensate return line from H1108 to condensate tank, V1005, to avoid hammering

• Connect high pressure N2 purge to the O2 line upfront H1151

• Connect N2 purge to the O2 line upfront H1151 (from 7 barg N2 net)

Risk evaluation

In this context, neither steam nor LOX can cause major accidents. Hence, FTM 04 will not be analysed in the QRA update.




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3.5 FTM 05 – OHCL reactor cooling loop Area: 1100

Medium: Boiler feed water

Description

Forced circulating steam boiler is used to cool the oxychlorination reactor. The current BFW circulation rate results in about 13% evaporation per pass. To keep the steam quality unchanged the circulation of BFW should be increased by 10%. This is achieved by reducing the pressure drop in the circulation loop and reducing the P1101 impeller diameter from 380 to 360 mm. The last is necessary to reduce the load on the motor. A spectacle blind will be installed between P1101 and BFW header. Blind will be replaced by orifice if required. This is a backup solution if the chosen orifices, 23 mm, is too large.

Risk evaluation

No (or limited) hazardous substances, hence FTM 05 will not be analysed in the QRA.


3.6 FTM 06 – New IPS line to Chlorine plant Area: 1000, 51

Medium: Steam

Description

Following the HTDC installation there will be a surplus of Intermediate Pressure Steam (IPS) in the VCM plant. This IPS can be utilised in the NaOH concentration unit in Klor 2. A new DN200 pipe must be installed between the VCM plant and Klor 2. The pipe shall be installed on existing pipe racks. A control valve with bypass possibilities and a flow meter is foreseen, but location and control philosophy is not decided.

Risk evaluation



3.7 FTM 07 - P1305A/S replacement Area: 1300

Medium: EDC gas

Description

Pumps P1305A and P1305S are old and needs to be repaired to be kept in operation. They will therefore be replaced with identical pumps. The new pumps will be installed on the existing pump skid.

A new motor will be installed for pump P1305A, and a recertified pump will be installed for pump P1305S.

Risk evaluation

The replacement will not impart any new leak sources. In addition, it is assumed that leaks of EDC will only give local effects, Ref. /2/. Hence, FTM 07 will not be analysed in the QRA.




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3.8 FTM 08 - Replacement of several control valves Area: Several

Medium: Fuel gas, NaOH, Ethylene, Crude EDC liquid, EDC liquid, EDC/VCM/HCl condensate, VCM liquid

Description

The following control valves needs to be replaced:

ID P&ID no DN

Current New

LCV202 12A 50 80

FCV313 13D 25 50

FCV450 14E 100 150

FCV518 15D 80 100

PCV114 11C 80 100

FCV148 11G 25 25

PCV053 10SA 150 200

PCV135 11C 200 200

Risk evaluation

Number of leak sources and pipe dimension is kept unchanged, only the valve dimension will increase. The impact on the risk contours will be negligible. Hence, FTM 08 will not be evaluated in the QRA.


3.9 FTM 09 - V1102 Modification of demister Area: 1100

Medium: Steam

Description

Oxy steam drum, V1102, has a demister pad at the steam outlet. This demister is too small for the increased steam production following a capacity increase and a bigger demister must be installed.

Risk evaluation





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3.10 FTM 11 - Replacement of RP4015, RP4057 and RP4124 Area: 1400

Medium: EDC gas, VCM, HCl

Description

The gas outlet line (RP4124) from H1406 to H1402 A/B is DN250. This gives a too high linear velocity in the line. The line shall be increased to DN350. The outlet nozzle on H1406 is DN250, therefore the spare outlet head must be modified with a larger outlet nozzle. The inlet nozzles on H1402 A/B are DN350 so no modifications are required. The condensate outlet lines from H1402A and H1402B are DN200 up to where they are expanded to DN250 and merged together. The DN200 part of these lines (200-RP4066-BA40 and 200-RP4015-BA40) shall be expanded to DN250. Outlet temperature is controlled by the by-pass lines. These have sufficient capacity.

Risk evaluation

The replacement will not impart any new leak sources, but the mass flow and the segment volume will increase due to increased dimensions.

However, these lines are a part of the top system in the cracking area and release from top system with HCl, VCM, EDC is assumed to only give local effects, Ref. /2/. Hence, FTM 11 will not be analysed in the QRA.


3.11 FTM 12 - New P1404S Area: 1400

Medium: EDC liquid

Description

In case of insufficient condensation in H1401 and H1406, reflux to the quench columns C1401 A/B/C can be supplied by P1404. Currently this is a single pump installation. By installing spare pump, P1404S, and allowing for auto start of the pump from the control room, increasing the size of quench reflux drum V1406 can be avoided. The pump shall be a copy of the existing pump. KSB has supplied a price for this. A new foundation for the spare pump must be constructed. Existing P1404 is on Variabel Speed Drive, but is normally operated at fixed RPM and HIC499 is used for flow control. Existing will be rebuilt to operate with fixed RPM. The new pump will also be operated on fixed RPM. The flow will be manually controlled by HIC499. HIC499 must be moved to allow control of either pump – See red marked P&ID 14107DA for instrument details.

Risk evaluation

A new spare pump may lead to an increase in potential leak sources. However, leak of EDC is assumed to only give local effects (Ref. /2/) and will not be analysed in the QRA.




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3.12 FTM 13 - New H1405C and new V1407 (new balcony on str. 6) Area: 1400

Medium: EDC/VCM/HCl condensate and cooling water

Description

The capacity of the quench overhead vent condensers H1405 A/B needs to be increased to reduce the load on the reflux on C1501.To allow the increased load a third parallel exchanger, H1405C, should be installed. This will be a copy of the larger condenser, H1405B, and will be installed on a new balcony west of the existing H1405B. Three H1405 in parallel will allow cleaning of the CW side of the heat exchangers while the VCM plant is running at high load. In addition a larger quench vapour separator, V1407, shall be installed to allow better separation of the H1405 A/B/C outlet. The new V1407 shall be installed below H1405 A/B/C on a skirt. RP4055 from V1407 bottom to C1501 shall be increased from DN80 to DN100. For further details on the scope of this modification, please refer to the individual FTM descriptions, Ref. /2/.

Risk evaluation

Additional equipment will lead to an increased total leak frequency.

However, the new heat exchanger and the new separator are a part of the top system in the cracking area and release from top system with HCl, VCM, EDC is assumed to only give local effects, Ref. /2/. Hence, FTM 11 will not be analysed in the QRA.


3.13 FTM 14 - Replacement of H1403 Area: 1400

Medium: EDC/VCM/HCl gas

Description

HCl exchanger H1403 is too small for the increased capacity and must be replaced. The new exchanger will have a larger diameter than the current exchanger. The top flange connections to the exchanger shall be kept as they are, and the exchanger must be expanded downwards. The height of the steel foundation will be reduced.

Risk evaluation

The replacement will not impart any new potential leak sources and the replacement is assumed to be “one to one”. Segment volume will increase due to increased dimensions.

Heat exchanger H1403 is a part of the top system in the cracking area and release from top system with HCl, VCM, EDC is assumed to only give local effects, Ref. /2/. Hence, FTM 11 will not be analysed in the QRA.




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3.14 FTM 16 – Replacement of RP5081 Area: 2700

Medium: EDC liquid

Description

Pipeline RP5081 from X1503 to T2707 is partially in pipe class LC25 and partially in A25.The scope of this FTM is to replace the A25 part with LC25. This is a long DN100 pipeline from the north/south main pipe rack in the VCM plant to the recycle EDC tank, T2707, in the south tank farm. There is no instrumentation on the pipeline.

Risk evaluation

The change in pipe class will increase the robustness of the pipe and have a benign effect on risk. However, the pipe class is not a parameter in the risk model, and this modification will therefore not be reflected in the QRA.


3.15 FTM 17 – Replacement of valves on C1501 Area: 1500

Medium: EDC/VCM liquid, EDC/VCM gas, steam, condensate

Description

Valves on the inlet and outlet of the reboiler on HCl column, H1501, will be replaced.

Risk evaluation

Replacing the valves will not introduce additional leak points. The modification will not be considered in the QRA.


3.16 FTM 18 – DBB on C1502 Area: 1500

Medium: EDC/VCM gas and liquid

Description

VCM column, C1502, has two reboilers, H1503 A and B. To avoid stopping the VCM production during reboiler replacement, double block and bleed valves shall be installed on the inlet and outlet of the reboilers. Butterfly valves are preferred. Hand operated valves are accepted. Valves are DN400 and DN900, thus long lead items. Bleed to Slop System (SS).

Risk evaluation

The DBB valves will introduce additional leak points. The modification will be considered in the QRA.




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3.17 FTM 19 – New H1541 with access platform Area: 1500

Medium: EDC/VCM 2-phase

Description

The feed from the HCl column to the VCM column should be cross exchanged with the bottom stream of the VCM column. This will reduce the steam consumption in the VCM column, which is a requirement to reach the 1700 t/d target. A new cross exchanger that cools the bottom outlet of the VCM column by preheating the feed to the column, H1541, shall be installed. The location of the cross exchanger is tight, and a structure that allows installation and removal of the heat exchanger from underneath the main pipe rack is required.

Risk evaluation

This FTM introduce new leak points of 2-phase EDC/VCM, and increase the segment volume. The FTM will be considered in the QRA.


3.18 FTM 20 – Replacement of H1551 and increase diameter on RP5056 and RP5190 Area: 1500

Medium: EDC, EDC liquid

Description

Dry crude EDC exchanger H1551 has too small heat transfer area, too small nozzles and a triangular pitch that makes cleaning very difficult. A new H1551 is designed to increase the heat transfer and avoid tube bundle vibrations. The new H1551 shall be installed in the same physical location as the existing one. In addition this FTM contains the replacement of RP5056 from C1502 to H1551 from DN100 to DN150 and the replacement of RP5190 from downstream LCV517 from DN100 to DN150.

Risk evaluation

Although the segment volume will increase, EDC leaks are assumed to only give local effects, Ref. /2/, and the modification will not be considered in the QRA.


3.19 FTM 21 – Install by-pass of H1512 Area: 1500

Medium: EDC liquid

Description

A bypass of Dry crude EDC cooler H1512 will allow plant operation with the heat exchanger out for maintenance.

Risk evaluation

Although the segment volume will increase, EDC leaks are assumed to only give local effects, Ref. /2/, and the modification will not be considered in the QRA.




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3.20 FTM 22 – Replacement of H1510 Area: 1500

Medium: Cooling water, VCM liquid

Description

VCM production cooler H1510 must be replaced as the pressure drop limits the capacity of the VCM stripper bottom pump P1507.

Risk evaluation

Replacing H1510 does not introduce any new leak points, but the mass flow rate will increase. The modification will therefore be considered in the QRA.


3.21 FTM 23 – Existing FTM (M50913-06) Increase capacity of P2752 Area: 2700

Medium: EDC

Description

Increase the capacity of P2752A/S for return EDC. The scope includes electrical modifications on existing pumps.

Risk evaluation

Although the mass flow rate will increase, EDC leaks are assumed to only cause local effects, Ref. /2/.


3.22 FTM 29 – New impeller P1507 (reduce efficiency requirement) Area: 2700 and 1300

Medium: EDC

Description

For the P-2703 position we need installation of two new and bigger pumps, and one pump in spare. We will also in this FTM add a number of valves to the existing scope in order to separate the content in T2702 and T2703 from each other.

• Today the pumps P2703 A/S operate as follows:

o P2703A takes full furnace feed from T2702 to V2704

o P2703S takes imported EDC from T2703 to V2704 via the same pipe as P2703A (flow limited by position of manual valve on discharge P2703 S)

o Pumps are equipped with check valve in discharge line

o Each existing pump P2703 is considered to be able to take 100% of current capacity, but not more (discharge valve fully open)



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• Additional valves to be foreseen to prevent contamination of import/export EDC in T2703 by purified EDC in T2702 (also in case P2703A out of service and switched to position P2703S). See drawing for valve positions:

o Valve position 1: Double valve needed to avoid contaminating T2703 with EDC coming from C1302. Zwick-valve is designed to block-> will install it instead of two valves

o Valve position 2: double valve needed. In case P2703A is switched to position S, EDC from T2702 can contaminate T2703 when not double blocked. Zwick-valve

o Valve position 3: double valve needed. In case P2703A is switched to position S and HTDC is sent to T2703, EDC from T2702 can contaminate T2703 when not double blocked

o Valve position 4: Double valve needed. Separation of purified and import/export EDC in normal operation (P2703A from T2702 and P2703S from T2703 to V2704) Zwick-valve

o Valve position 5: Is it is today, no change

o Valve position 7: In case of normal operation and unloading of vessel to T2703, this position can contaminate T2703. Existing manual valves from Jetty line to T2703 are closed in normal operation double valve required

o Valve position 6: In case P2703A is switched to position S and unloading of vessel to T2703, this position can contaminate T2703. Rare scenario double valve not required. No, change from current configuration

o In addition, not a numbered valve on the drawing. We will need a extra line from the new HTDC line from HTDC-unit to cracker-feed tank. There is a spare nozzle on top of the cracker-feed tank. This line will need a dip-tube. One valve on top of the tank

o Need blinds on two valves near sampling station 27-03 (not on the drawing)

o Supply benzene free EDC to HTDC

Risk evaluation

EDC leaks are assumed to only give local effects, Ref. /2/. This modification will therefore not be considered in the QRA.




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3.23 FTM 31 – Utility tie-ins Area:

Medium:

Description

Utility tie-ins to the new HTDC module. Extent of modifications will be identified in the QRA update.

Risk evaluation

All tie-ins to the new HTDC module will be considered in connection with installing the new HTDC module. This FTM will be further analysed in the QRA to identify if the utility tie-ins include any hazardous substances.

The blowdown system is assumed not to be pressurized.


3.24 FTM 32 – Process tie-ins Area:

Medium:

Description

Process tie-ins to the new HTDC module. Extent of modifications will be identified in the QRA update.

Risk evaluation

All tie-ins to the new HTDC module will be considered in connection with installing the new HTDC module.


3.25 FTM 33 – Vent gas scrubber ANH Area: 1800

Medium: Nitrogen

Description

The HTDC unit will run at lower pressure than the LTDC, to be able to absorb the vent gas in ANH in case of incinerator S/D a vent gas scrubber system shall be installed on HCl neutralization tank, T1801. A new pump, P1859S, will be installed to allow circulation of caustic in the scrubber in case of electrical black out.

Risk evaluation

Nitrogen is not considered as a hazardous substance in the context of the QRA. Also, input from Wood shows that the pressure in the vent gas scrubber system will be low, and a leak should not cause any large scale effects. Therefore, this FTM will not be considered in the QRA update.




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3.26 FTM 34 – Analyser house modifications Area: 1650

Medium: N/A

Description

The existing analyser house needs to be extended to accommodate the new HTDC analysers (fig.1). The additional room has a simple metal roof which needs to be replaced by a reinforced concrete roof. Some equipment has to be relocated when opening the wall between the existing and new room. Final location of the new analysers in the new room has to be done based on final sample system and analyser layout. There are five available slots on the walls in the new room. The existing bottle room will be reduced to one small compartment suitable for the required number of bottles.

Risk evaluation

Only structural changes, not relevant for the QRA.


3.27 FTM 35 – Underground piping Area:

Medium: H2O

Description

Underground piping must be rerouted due to conflict with the foundation of the HTDC module.

The following pipes must be rerouted:

• 150-RP8315-LC16

• 150-FW0010-LC16

• 200-FW0003-LC16

• 200-FW0001-LC16

• 160-CS1041-ZD10

• 50-CS0025-ZD10

Risk evaluation

Non-hazardous substances (drain water, fire water etc.) The modifications will not be included in the QRA.




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3.28 FTM 36 – Pipe rack HTDC bridge Area: 1600

Medium: N/A

Description

New steel pipe rack bridge from battery limit at HTDC module to battery limits at wash area pipe rack.

Risk evaluation

Only structural changes, not relevant for the QRA.


3.29 FTM 37 – Fire and gas Area: New HTDC module

Medium: N/A

Description

Installation of gas detection systems in the new HTDC module:

• EX detectors for explosive gas detection

• Chlorine gas detectors (point detectors)

• Sniffing detectors for detection of toxic gas releases (low concentrations)

Risk evaluation

Gas detection in the new HTDC module will be considered as a barrier in the QRA.


3.30 FTM 38 – New flame arrestor for HTDC Area: 1600, 1800

Medium: Nitrogen, oxygen, ethylene

Description

Replacement of existing flame arrestor and RP6045 from 1600 to incinerator F1821.



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Risk evaluation

Input from Wood shows that there is only a small fraction of ethylene in this pipe (9 vol%). Nitrogen and oxygen are not considered in the QRA, so it is assumed that this FTM will have a negligible effect on the risk contours. Therefore, the FTM will not be considered in the QRA update.


3.31 FTM 39 – New fire water monitor Area: Fire water system

Medium: H2O

Description

Monitor X1032/12 shall be replaced by new remotely controlled fire water monitor X1032/16 in TAR 2019.

Risk evaluation

The fire water monitor will be considered as a barrier/risk reducing measure in the QRA.




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3.32 FTM 40 – Tie-in of new OHCL reactor and required modifications due to preservation of existing reactor Area: 1100

Medium: HCl, C2H4, EDC, Air

Description

The following items to be included in the work description of FTM40 - Tie-in of OHCL:

• Tie-in of new reactor V1106

• Preservation of existing reactor V1101

• Modify Y-piece of existing reactor or purchase new y-piece

• Removable spool on RP1055 to the existing reactor to be included

• New ladder from platform on top of existing OHCL reactor

• Access to existing ladder from platform on top of OHCL reactor to be closed

Risk evaluation

Tie-ins of OHCL reactor will be considered in connection with the installation of the new OHCL reactor.


3.33 FTM 41 – New HPN vessel for emergency purging Area:

Medium: Nitrogen

Description

One new nitrogen tank V1107 shall be installed. Location is north of existing tanks. The tank shall have an access platform at the top, similar to those which are located on existing tanks. These platforms shall be connected with bolts. There is good access for cranes in the particular area.

Risk evaluation

Nitrogen is not a hazardous substance in the context of the QRA.




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4 Summary

Table 4.1 presents a summary of the VCM FTMs and comment on their potential as risk contributors in the context of the QRA update.

Out of the 33 FTMs presented in this memo, 11 FTMs/modifications will be analysed further in the update of the QRA. In addition, risk assessment of the new HTDC module and OHCL reactor will be included.

Table 4.1 – Summary of risk evaluation of FTMs

FTM No.


FTM 01 1100 Replacement of line 400-RP 1069 to DN500

EDC gas No

FTM 02 1100 V1105 modifications HCl gas Yes

FTM 03 1100 H1104 replacement HCl gas, condensate and steam

Yes

FTM 04 1100 Increase oxygen feed to OHCL with new heat exchanger H1151

Condensate, steam, N2, enriched air and LOX

No

FTM 05 1100 OHCL reactor cooling loop Boiler feed water

No

FTM 06 1000, 51 New IPS line to Clorine plant Steam No

FTM 07 1300 P1305A/B/S replacement EDC gas No

FTM 08 Several Replacement of several control valves

Fuel gas, NaOH, Ethylene, Crude EDC liquid, EDC liquid, EDC/VCM/HCl condensate, VCM liquid

No

FTM 09 1100 V1102 Modification of demister Steam No

FTM 11 1400 Replacement of RP4015, RP4057 and RP4124

EDC gas, VCM, HCl

No

FTM 12 1400 New P1404S EDC liquid No

FTM 13 1400 New H1405C and new V1407 (new balcony on str. 6)

EDC/VCM/HCl condensate and cooling water

No



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FTM No.


FTM 14 1400 Replacement of H1403 EDC/VCM/HCl gas

No

FTM 16 2700 Replacement of RP5081 EDC liquid No

FTM 17 1500 Replacement of valves on C1501 EDC/VCM liquid, EDC/VCM gas, steam, condensate

No

FTM 18 1500 DBB on C1502 EDC/VCM gas and liquid

Yes

FTM 19 1500 New H1541 with access platform EDC/VCM 2-phase

Yes

FTM 20 1500 Replacement of H1551 and increase diameter on RP5056 and RP5190

EDC, EDC liquid

No

FTM 21 1500 Install by-pass of H1512 EDC liquid No

FTM 22 1500 Replacement of H1510 Cooling water, VCM liquid

Yes

FTM 23 2700 Existing FTM (M50913-06) Replacement of P2752

EDC No

FTM 29 2700,1300 New impeller P1507 EDC No

FTM 31 Utility tie-ins Unknown Yes

FTM 32 Process tie-ins Unknown Yes

FTM 33 1800 Vent gas scrubber ANH Nitrogen No

FTM 34 1650 Analyser house modifications N/A No

FTM 35 Underground piping H2O No

FTM 36 1600 Pipe rack HTDC bridge N/A No

FTM 37 Fire and gas N/A Yes

FTM 38 1600,1800 New flame arrestor for HTDC Nitrogen, oxygen, ethylene

No

FTM 39 Fire water system

New fire water monitor H2O Yes

FTM 40 1100 Tie-in of new OHCL reactor and required modifications due to preservation of existing reactor

HCl, C2H4, EDC, Air

Yes

FTM 41 New HPN vessel for emergency purging

Nitrogen No



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5 References

/1/ Lloyd’s Register Consulting: «Total risk assessment (QRA) for the Chlorine and VCM plant – INOVYN Norge AS, Rafnes”, Report no. 105797/R1, Rev. Final, 15 September 2015

/2/ INEOS Norge AS/Noretyl AS: “Arbeidsbeskrivelse FTM 13”, Doc. No. 10113993-I50477-I-TF-0002, 10113993-I50477-L-TF-0013, 10113993-I50477-N-TF-0013 and 10113993-I50477-R-TF-0013, Rev. 01



Appendix C

Risk screening workshop - Chlorine plant

Page C1 Report no: PRJ11090011 Rev: Final


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Memo

Risk screening workshop - Chlorine plant

To: Inovyn Cc:

From: Ingebjørg Valkvæ/Andrea Risan/

Stian Jensen/Ane Kristiansen

Date: 30 November 2018

Project no: PRJ11091548

Table of Contents 1 Introduction ..................................................................................................................................... 2

2 Process description .......................................................................................................................... 3

3 Chlorine plant modifications ............................................................................................................ 3

3.1 FTM 262 - Installation of new electrolyser ............................................................................. 3

3.2 FTM 361 - Increased capacity on chlorine cooler .................................................................... 4

3.3 FTM 366 - Increased capacity on chlorine compressor ........................................................... 4

3.4 FTM 421 - Increased capacity on hydrogen compressor ......................................................... 4

4 Summary ......................................................................................................................................... 5

5 References ....................................................................................................................................... 5

Memo: Risk screening workshop - Chlorine plant Page 1 of 5


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1 Introduction

INOVYN operates a vinyl chloride monomer (VCM) and chlorine plant at the Rafnes industrial area, marked in Figure 1.1. At present, the chlorine plant is upgraded to higher production rates as part of the North Star project. LR is contracted by Inovyn to investigate the impact on the risk picture as a result of this upgrade.

In addition to the new HTDC module and new OHCL reactor, several minor modifications are planned for the plants. In order to ensure that all risk contributors associated with the project are accounted for in the QRA update, a one-day workshop was held at Rafnes with a scope including up to 40 modifications. In the workshop, Wood and INOVYN presented the various modifications and replacements planned for the chlorine and VCM plants. The workshop also included a guided tour around the plants.

This memo presents the planned modifications (FTMs – “Forslag til modifikasjoner”) for the chlorine plant with a comment on their potential as risk contributors in the context of the QRA. The QRA focus on the “delta” risk, i.e. increase or decrease in risk potential of implementing the FTM. As an example, if a new valve replaces an existing valve, the delta risk is assessed to be negligible. However, if new valves are installed or if pipes are replaced with larger ones, increasing the volume of hazardous material, the risk potential will increase. The modifications with a considerable delta risk potential will be passed on to the QRA update activity.

The selection of modifications to be included in the QRA is based on the information from the Risk screening workshop and general assumptions made in the previous QRA performed for INOVYN Chlorine and VCM plant in 2015 (Ref. /1/)

Figure 1.1 – Overview of the Rafnes industrial area. The VCM and chlorine plants are highlighted in orange



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2 Process description

Chlorine is produced in two almost identical plants, Chlorine 1 and 2, with membrane electrolysers. Chlorine is produced on the anode side and hydrogen and caustic soda on the cathode side. The moist chlorine gas is cooled, filtered and dried with sulphuric acid before being compressed to approx. 5.5 bar(g) and sent to the VCM plant. The Chlorine gas from both plant 1 and 2 is delivered in a single 250 mm header.

The Hydrogen gas is cooled, filtered, dried and compressed and sent to the VCM plant and to the neighbouring industry Noretyl to be used as raw material or fuel gas.

The caustic soda is concentrated to 50 % using evaporation and then stored. The caustic soda is exported by trucks and shipped by boats to several customers.

The chlorine plant is divided into the following areas:

• Water purification

• Brine

• Cell room

• Caustic soda

• Hydrogen

• Lean brine dechlorination

• Emergency scrubber/recovery chlorine

• Chlorine

3 Chlorine plant modifications

3.1 FTM 262 - Installation of new electrolyser Area: Cell room

Medium: Brine, H2, Cl2, NaOH

Description

Installation of a new electrolyser in the existing cell room for Klor 1. Process design and material delivery is part of tkUCE's contract. Follow-up of technical conditions and delivery as such are carried out in the modification.

Risk evaluation

Leaks from individual cells are not considered to pose a threat outside the cell room, Ref. /1/. The new electrolyser will however result in increased mass flow rate in the chlorine header, and will therefore be included in the QRA.




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3.2 FTM 361 - Increased capacity on chlorine cooler Area: Chlorine

Medium: Cl2 gas

Description

The capacity of existing chlorine cooler is too low and must be replaced. Process and mechanical design as well as material / equipment delivery are part of tkUCE's contract. Follow-up of technical conditions and delivery as such are carried out in the modification. Potential solution: Replacement of existing cooler with new cooler with sufficient capacity

Risk evaluation

Replacing the chlorine cooler will increase the segment volume and will therefore be included in the QRA.


3.3 FTM 366 - Increased capacity on chlorine compressor Area: Chlorine

Medium: Cl2 gas

Description

The capacity of existing chlorine compressor is not sufficient to handle increased production and thus capacity must be increased. Modification work on the compressor is performed in TAR2019. The modification follows up on contract, preparation work, and work carried out on site. The K3201 is a single-handed 3-speed radial turbo compressor manufactured by Demag (Siemens AG).

Risk evaluation

Revamping the chlorine compressor will increase the segment volume and will therefore be included in the QRA.


3.4 FTM 421 - Increased capacity on hydrogen compressor Area: Hydrogen

Medium: H2

Description

The capacity of existing hydrogen compressor is insufficient and the capacity must thus be increased. There are two current alternatives:

• New compressor train in parallel with existing (most likely not this option)

• Replacement of existing compressor train

Risk evaluation

Leaks of hydrogen from compressors are assumed to give only local effects. However, replacing the hydrogen compressor will increase the mass flow rate in the hydrogen header, and will therefore be included in the QRA.




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4 Summary

Table 4.1 presents a summary of the chlorine plant FTMs and comment on their potential as risk contributors in the context of the QRA update.

All 4 FTMs presented in this memo will be analysed further in the update of the QRA.

Table 4.1 – Summary of risk evaluation of FTMs

FTM No.


FTM 262 Cell room Installation of new electrolyser Brine, H2, Cl2, NaOH

Yes

FTM 361 Chlorine Increased capacity on chlorine cooler Cl2 gas Yes

FTM 366 Chlorine Increased capacity on chlorine compressor

Cl2 gas Yes

FTM 421 Hydrogen Increased capacity on hydrogen compressor

H2 Yes

5 References

/1/ Lloyd’s Register Consulting: «Total risk assessment (QRA) for the Chlorine and VCM plant – INOVYN Norge AS, Rafnes”, Report no. 105797/R1, Rev. Final, 15 September 2015



north star qra update - dsb · the qra can be seen as part of the effort to reach this objective....

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