Process Department

SSE-06COMPARATIVE STUDY OF THE USE OFVISUAL FLOW, INPLANT AND OTHER SIMULATORS IN THE RELIEF SYSTEM

DESIGN

Invensys User Group Series, Houston, October 15-16

Copyright © 2012. Inelectra SACA.- All rights reserved

Prepared by: Pedro CeballosRevised by: Edgar Alfonso / Carmelo Trezza / María Pereira / Fernando Azuaje

Content

• DA-1/ DA-2/ VDU Relief System Hydraulic Evaluation

• Relief System Hydraulic Evaluations

• Comparison of Simulators

• Relief Systems

• Conclusions

• Relief System Components

• Installing a pressure relief device, lines and means for transport and disposal of the relief fluid in gaseous phase, liquid or both.

• It is used when the presence of liquid, toxic properties or other factors would make it dangerous to discharge into the atmosphere

Relief Systems

Definition:

Standards Applicable to Relief Systems:

API 520 I. Sizing, Selection, and Installation of Pressure-Relieving Devices in Refineries. Part I—Sizing and Selection

API 520 II. Sizing, Selection, and Installation of Pressure-Relieving Devices inRefineries. Part II—Installation

API 521. Pressure-relieving and Depressuring Systems

API 526. Flanged Steel Pressure Relief Valves

API 537. Flare Details for General Refinery and Petrochemical Service

API 576. Inspection of Pressure-relieving Devices

Relief Valves

Discharge Lines

KnockOut Drum

Flare

KnockOut Drum Pumps

Subheaders

Header

Protected Equipments

Relief System Components

KnockOut Drum

Relief System Hydraulic Evaluations

P2= 0 psig

DPtip= 3 psig

DPsello= 2 psig

P1= ? psig

(Set pressure)

(Backpressure)

Relief Valve

Flare

Criteria to define the relief valve type:

Conventional: BP/SP<10%

Balanced: 10%<BP/SP<30%

Pilot:30%<BP/SP<75%

(%) =BP Backpressure (psig)SP Set Pressure (psig)

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

Description:

Project: Deep Conversion

Location: Puerto La Cruz Refinery

Engineering: Detail

UnitsInvolved:

DA-1/DA-2 (Atmospheric Distillation Units)VDU (Vacio Unit)

Flare Type: Ground Flare

Darwin LNG; Australia

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

* Validate the results obtained during the basic engineering of hydraulic calculations associated with the main header of Ground Flare Relief System and DA-1/DA-2/VDU referred to in the Deep Conversion Project of Puerto La Cruz.

Main Objective:

* Compare the use, advantages and disadvantages of simulators available in the Company (INELECTRA) for Relief Systems Analysis (VISUAL FLOW, INPLANT, Aspen Flare and Superchems).

Secondary Objective :

* Pressure of 10 psi at Ground Flare.

* In the General Electric Power Failure DA-1, DA-2 and VDU discharge simultaneously.

* Maximum speed (Mach): Discharge Line: 0.75 / Header-SubHeader: 0.50.

* Backpressure criteria: Conventional: 10% / Balanced: 30% / Pilot: 75%.

Design Basis:

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

Relief System Design :Main Contingency: General Electric Power Failure

Total Relief Load: 782392 lb/h

Size Head: 42’’

Equipment InvolvedDA-1: Atmospheric TowerDA-2: Atmospheric TowerVDU: Vacuum Tower

GroundFlare

DA-2

DA-1

VDUTRAIN 1 & 2

42’’

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

Relief System Scheme:

VISUAL FLOW Simulation:

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

DA-1 Tower

DA-2 Tower

VDU Towers

INPLANT Simulation

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

DA-1 Tower

DA-2 Tower

VDU Towers

Aspen Flare Simulation

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

DA-1 Tower

DA-2 Tower

VDU Towers

SuperChems Simulation

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

SIMULATOR PARAMETER PSV-05391-A PSV-05391-B PSV-05391-CSP= 30 psig SP= 31.5 psig SP= 31.5 psig

BASIC ENG.(SUPERCHEMS)

Outlet Line Mach Nro 0.169 0.169 0.169Backpressure (psig) 21.5 21.5 21.5Back P / Set P (%) 71.5 68.1 68.1

DETAIL ENG.(VISUAL FLOW)

Outlet Line Mach Nro 0.192 0.192 0.192Backpressure (psig) 15.4 15.4 15.7Back P / Set P (%) 51.3 48.8 49.8

Results. General Power Failure (DA-2 Tower)

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

SIMULATOR PARAMETERPSV-04416A PSV-04416B PSV-04416C PSV-04416D PSV-04416E PSV-04416FSP=30psig SP=31.5psig SP=31.5psig SP=31.5psig SP=31.5psig SP=31.5psig

BASIC ENG.(SUPERCHEMS)

Outlet Line Mach Nro 0.191 0.191 0.191 0.191 0.191 0.191Backpressure (psig) 21.9 21.9 21.9 21.9 21.9 21.9Back P / Set P (%) 73.1 69.6 69.6 69.6 69.6 69.6

DETAIL ENG.(VISUAL FLOW)

Outlet Line Mach Nro 0.216 0.214 0.214 0.313 0.313 0.313Backpressure (psig) 15.0 15.3 15.3 14.7 14.7 14.6Back P / Set P (%) 49.9 48.6 48.6 46.6 46.6 46.5

Results. Cooling Water Failure (DA-1 Tower)

Elbow 90° 90 deg. 1 Weld. 90 deg angleElbow 45° 45 deg. Standard (R/D=1), all typesT branch Used as elbow. Standard, screwed

T run Run through tee. Screwed

Elbow 90° Long-Radius (R/D=1.5), all typesElbow 45° 45 deg. Long radius (R/D=1.5), all typesT branch Used as elbow. Standard, flanged/welded

T run Run through tee. Flanged/welded

Origin of differences (Basic Eng. – Detail Eng.)

Header Inside Diameter 42’’:

K(12”)=1.247

K(12”)=0.217

Fittings (Basic Eng.):

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

Fittings (Detail Eng):

Basic Eng.: Detail Eng. (Piping Classs) 40’’ 41.188’’

SIMULATOR PARAMETER PSV-04416A PSV-04416B PSV-04416C PSV-04416D PSV-04416E PSV-04416FSP=30psig SP=31.5psig SP=31.5psig SP=31.5psig SP=31.5psig SP=31.5psig

VISUAL FLOWOutlet Line Mach Nro 0.216 0.214 0.214 0.313 0.313 0.313Backpressure (psig) 15.0 15.3 15.3 14.7 14.7 14.6Back P / Set P (%) 49.9 48.6 48.6 46.6 46.6 46.5

INPLANTOutlet Line Mach Nro 0.209 0.209 0.209 0.209 0.209 0.209Backpressure (psig) 15.9 15.9 15.9 15.9 15.9 15.9Back P / Set P (%) 52.8 50.3 50.3 50.3 50.3 50.3

ASPEN FLAREOutlet Line Mach Nro 0.209 0.212 0.211 0.210 0.210 0.210Backpressure (psig) 16.3 15.9 16.1 16.1 16.1 16.1Back P / Set P (%) 54.4 50.4 51.0 51.2 51.3 51.1

SUPERCHEMSOutlet Line Mach Nro 0.210 0.210 0.210 0.210 0.210 0.210Backpressure (psig) 15.0 15.0 15.0 15.0 15.0 15.0Back P / Set P (%) 50.1 47.7 47.7 47.7 47.7 47.7

Results. Cooling Water Failure (DA-1 Tower)

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

SIMULATOR PARAMETER PSV-05391-A PSV-05391-B PSV-05391-CSP= 30 psig SP= 31.5 psig SP= 31.5 psig

VISUAL FLOWOutlet Line Mach Nro 0.192 0.192 0.192Backpressure (psig) 15.4 15.4 15.7Back P / Set P (%) 51.3 48.8 49.8

INPLANTOutlet Line Mach Nro 0.185 0.185 0.185Backpressure (psig) 16.2 16.1 16.1Back P / Set P (%) 54.1 51.0 51.0

ASPEN FLAREOutlet Line Mach Nro 0.185 0.185 0.186Backpressure (psig) 16.3 16.3 16.3Back P / Set P (%) 54.3 51.9 51.7

SUPERCHEMSOutlet Line Mach Nro 0.187 0.187 0.187Backpressure (psig) 15.8 15.8 15.8Back P / Set P (%) 52.6 50.1 50.1

Results. General Power Failure (DA-2 Tower)

DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation

Comparision of Simulators

Mounting the Model:

VISUAL FLOW INPLANT ASPEN

FLARE SUPERCHEMS

Allows change the method of thermodynamic YES YES YES NOAllows added viscosity experimental data. NO YES NO NOEasy to add components and uses them when performing the simulation on other computers NO YES YES NO

Allows to create pseudocomponentes with PM>1000 NO YES NO YES

Allowsto add over 50 pseudocomponentes in a line YES NO YES YES

Allows to add pipes to the library YES YES YES NOAllows to copy valves and equipments YES YES YES NOAllows to enable and disable lines and equipments NO YES YES NOEase of data entry YES YES YES NO

Comparision of Simulators

Simulator Flexibility:

VISUAL FLOW INPLANT ASPEN

FLARE SUPERCHEMS

Evaluation of the pressure drop at the entrance of the safety valve YES NO NO YES

Can simulate various scenarios (contingencies) with a single run YES NO YES NO

Sizing Relief Valves YES YES YES YESSizing Relief Headers YES YES YES YESAllows isometric drawings YES NO NO NODynamic Evaluation of Fire Contingency NO NO NO YESRadiation Evaluation NO NO NO YESIt takes into account energy losses to the environment NO NO YES YES

Comparision of Simulators

Results Report:

VISUAL FLOW INPLANT ASPEN

FLARE SUPERCHEMS

Getting quick results (duration of the run) YES YES YES NOReports the pressure drop in each segment / fitting YES YES NO YESCalculation of relief temperature YES NO NO NOEasy to calculate backpressure on PSV YES YES YES NO

General recommendations for use of simulators according to the case study

Case Simulator

Simulation of gas reliefVISUALFLOWSuperchems

Simulation of viscous liquid relief Inplant

Simultaneous evaluation of several cases where contingency is involved one relief valve

VISUALFLOW Aspen Flare

Quick estimate of the backpressure INPLANT

Evaluation of the pressure drop at the entrance to the relief valveVISUALFLOW Superchems

Evaluation of Fire event when multiple loads are involved (dynamic simulation)

Superchems

Evaluation of heat loss to the environmentSuperchems, AspenFlare

Comparision of Simulators

* The diameters established for the main header (42"), for DA-1 subheader (42") and DA-2 subheader (30") during basic engineering are according with the design basis.

Conclusions

* It should verify that the fittings on the pipes do not create an excessive pressure drop avoid unnecessary overdesigns.

* According to the system under study, each relief systems simulator offers particular advantages, among them are the INPLANT by the facilities in the model assembly and VISUAL FLOW for flexibility and good results.

Thanks for your attention!!