2b0565g1 m143 d001 rev 1 leak searching proceedure

DC Document No.Bhushan Document No.

2B0565G1-M143-D001Rev. 1

BHUSHAN - GREEN FIELD B/F

MERAMANDALI, ORISSA, INDIA

New Blast Furnace No.1 - 2005

Blast Furnace

Process

LEAK SEARCHING PROCEDURE

FOR

A PLATE COOLED FURNACE

All rights reserved; confidential. This document is prepared by Danieli Corus BV entailing valuable know-how owned by DanieliCorus BV and is supplied only for the specific use as authorized by written agreement. This document shall not be disclosed, used orreproduced either wholly or in part except in connection with such authorized use and then only with the prior written consent ofDanieli Corus BV. This document must not be used until signed as checked and approved by Danieli Corus BV.© 2010 Danieli Corus BV

1 Feb 02, 2010 Revised R. Putten J. Plooij A. Bol

Rev. Date Description Prepared by Checked ApprovedY:\Exact Projects\B - BF\2B05650 Greenfield BF Bhushan\02 - Engineering\01-Engineering NEW\G1 Eng FCE\M- Mec\143-0 Furnace Cooling\2B0565G1 M143 D001Rev 0 - Leak Searching Prodedure.doc

Bhushan Project No.:DC Project No.: 2B05650

of 34

Bhushan, Green Field B/FDocument No.: 2B0565G1-M143-D001

of 34 Feb 02, 2010Rev.: 1

REVISION SHEET

Rev Date Section Page Description1 Feb 02, 2010 Second Issue - Revised


of 34 Feb 02, 2010Rev.: 1

Table of Contents

REVISION SHEET..........................................................................................................................2

1. INTRODUCTION ........................................................................................................5

2. DEFINITIONS .............................................................................................................6

3. GENERAL REMARKS ................................................................................................8

3.1 Safety Remarks.........................................................................................................8

3.2 Organization Remarks...............................................................................................8

3.3 Job Preparation.........................................................................................................8

3.4 "No Flow" Condition or Pressure Test .......................................................................9

3.5 Water Spillage...........................................................................................................9

3.6 Heat Flux Monitoring .................................................................................................9

4. ELEMENT REPLACEMENT SCHEDULE .................................................................10

5. MAINTENANCE ROUNDS........................................................................................11

5.1 Shift Rounds ...........................................................................................................11

5.2 Preventive Maintenance Rounds.............................................................................11

6. INDICATIONS OF A LEAK........................................................................................12

6.1 Expansion Tanks.....................................................................................................12

6.2 Secondary Indications.............................................................................................12

6.3 Magnetic Flow Meter ...............................................................................................13

7. PROCEDURES FOR LEAK SEARCHING ................................................................14

7.1 Procedure 1 – Detection by Flow Meter Readings...................................................15

7.2 Procedure 2 – Detection by Closing Manifold Supply Valve ....................................16

7.3 Procedure 3 – Detection by Partially Closing Manifold Supply Valve.......................17

7.4 Procedure 4 – Detection by Pressure Indication......................................................18

7.5 Procedure 5 – Detection by CO Measuring .............................................................19

7.6 Procedure 6 – Element Detection in Circuit .............................................................22

8. LEAK SEARCH SCHEDULE.....................................................................................24

9. CIRCUIT AND ELEMENT ISOLATION .....................................................................25

9.1 Circuit Isolation........................................................................................................25

9.2 Element Isolation.....................................................................................................27

9.3 Possibilities for Continuation ...................................................................................28


of 34 Feb 02, 2010Rev.: 1

10. TUYERES LEAK SEARCHING AND DETECTION ...................................................29

10.1 General ...................................................................................................................29

10.2 Tuyere Nose ...........................................................................................................31

10.3 Tuyere Body............................................................................................................34

10.4 Tuyere Cooler .........................................................................................................34

11. PLATES LEAK SEARCHING AND DETECTION ......................................................34


of 34 Feb 02, 2010Rev.: 1

1. INTRODUCTION

This document provides information on how leak searching can and should be performed ontypical Danieli Corus design "CLOSED" plate cooler systems.

It further contains organizing and safety remarks based on experience, which might be useful forusers.

This document has not the intention to dictate explicitly how leak searching shall be performed ororganized but allows the user to prepare his own procedures, based on specific information fromthis document and specifically adapted by him to traditional plant related job procedures and safetyregulations.


of 34 Feb 02, 2010Rev.: 1

2. DEFINITIONS

Zone The blast furnace cooling is vertically devided in zones: Bosh / Tuyere, Belly,Lower Lower Stack, Upper Lower Stack, Lower Middle Stack, Upper MiddleStack and Upper Stack & Throat.

Section Each zone is divided into eight sections in the circumference of the blast furnace.Each section is served by a manifold for cooling water.

Circuit Each section consist of multiple circuits of cooling water. Each circuit is ahorizontal series of four or five plates and are connected with each other by smallbore stitch piping

Element One individual cooled item.

Tuyere Nose Element that forms together with the tuyere body the tip of the tuyere assembly.The nose is the front most cooling channel of the element and is served by theHP tuyere cooling water system.

Tuyere Body Element that forms together with the tuyere nose the tip of the tuyere assembly.The body is the cooling channel behind the tuyere nose and is served by the LPtuyere cooling water system.

Tuyere Cooler Element behind the tuyere nose and body served by the LP tuyere cooling watersystem.

Plate Element in the Bosh / Tuyere, Belly, Lower Lower Stack, Upper Lower Stack,Lower Middle Stack and Upper Middle Stack zone.

Manifold Cooling water supply or return header with valves to control the water flow to thecircuits. Each supply and return manifold serves one section.

Supply Line Cooling water line between the supply manifold and the first element in a circuit.

Return line Cooling water line between the last element in a circuit and the return manifold.

Stitch Piping Small bore interconnecting piping between elements in a circuit. A typical stitchpiping assembly consist of a piping assembly with a ball joint or a hoseassembly.

3-Way Ball Valve “Closed”The valve handle or wrench on the manifold is moved to isolate the flow towardsthe circuits or elements.

3-Way Ball Valve “Open”The valve handle or wrench on the manifold is moved to maintain the flowtowards the circuits or elements.


of 34 Feb 02, 2010Rev.: 1

3-Way Ball Valve “Throttling”Gradually closing or opening the 3-way ball valve to manipulate the flow towards,and the pressure in the circuits or elements. Throttling is done between the“open” and “closed” position of the 3-way ball valve.


of 34 Feb 02, 2010Rev.: 1

3. GENERAL REMARKS

3.1 Safety Remarks

Warnings to potential dangerous situations are indicated in the text with the following:

WARNING

BF gas danger requires continuous attention and the use of gas (CO, CO2, etc.) detectors is anessential item to be included in detailed procedures.

Make sure that all required safety precautions will be taken, and that full crew will be instructed onactions to be taken in case an alarm phase is initiated.

Be aware of progressing pressure built up and steam danger during "No Flow" condition of circuitsto be checked.Never leave such a circuit unobserved and be sure to minimize "No Flow" condition, see furthersection 3.4.

3.2 Organization Remarks

It is recommended to work with specialized teams, for example for fitting or welding, thus gainingexperience.It is important to work in teams, which are responsible for their own furnace areas.

All repaired circuits must be recorded on a drawing, which is kept on a central location.

A foreman must be fully convinced that a circuit he released for use, does not contain any leakingelement.

In case a detection procedure overlaps shifts, the next foreman has to be fully informed of thestatus of the work. This prevents passing by of unchecked circuits or double-checking of repairedones.

3.3 Job Preparation

It is required to perform the best possible job preparation and crew instruction to be fully preparedas soon as the actual work starts.

All required material, equipment, power, labor, illumination, etc. should be ready or stand by.

A number of hoses have to be prepared of sufficient pressure class and length, provided withcorrect couplings to make all the required connections as described in the different procedures tofollow.


of 34 Feb 02, 2010Rev.: 1

3.4 "No Flow" Condition or Pressure Test

By performing leak searching on a section or circuit, the flow will be blocked by closing theupstream and downstream valves.The section or circuit will act as a steam boiler and the resulting pressure will be taken as anindicator.

WARNING

The "No Flow" condition shall be held no longer than strictly necessary. Unnecessary pressurebuilt up can cause leakage in an element!

Be sure to open both valves (downstream valve first) as soon as readings have been finished.

In case work has to be interrupted unexpectedly, do not leave the job without opening both valvesas mentioned above.

With a new or relined Furnace the "No Flow" leak searching condition can be used in the bosh,belly and stack.In case the furnace ages and the bosh plates become directly exposed to high temperatures in therace way and melting zone, a quick burn out can be the result when stopping the water flow.It can be dangerous to use this condition in the bosh and tuyere area.For this reason on old furnaces, no-flow or pressure testing is not recommended in the bosh.

3.5 Water Spillage

In several of the following procedures a certain amount of water is withdrawn from the system,temporarily or continuously.Prior to start any of these procedures the treated water make-up system has to be checked oncapacity and availability.

3.6 Heat Flux Monitoring

In case the cooling system is provided with a Heat Flux Monitoring System, be aware that leaksearching actions will influence readings of the affected Heat Flux Monitoring areas. Blast furnaceoperators shall therefore be informed about leak searching actions.


of 34 Feb 02, 2010Rev.: 1

4. ELEMENT REPLACEMENT SCHEDULE

Depending on the area the leaking element is located and the type of element under concern thereplacement shall be done according to the following schedule:

Blast Furnace Zone Type of Element Action

Tuyere Tuyere Nose and Body Nose can be set dry and shall bereplaced in a planned BF Shut-down. When the body is leakingthe Tuyere Nose and Body shall bereplaced immediately / within 24hours. (1)

Tuyere Tuyere Cooler Immediately / Within 24 Hours (1)Tuyere Plate Immediately / Within 24 Hours (1)Bosh Plate Immediately / Within 24 Hours (1)Belly Plate Immediately / Within 24 Hours (1)LS Plate Immediately / Within 24 Hours (1)MS Plate Planned BF Shut-down (2)US Plate Major BF Overhaul

Notes:(1) Large leaks must be handled immediately as soon as possible as the furnace allows.(2) A plate can be set dry in the higher part of the blast furnace without jeopardizing the

refractory. This shall be restricted to one or two non ajacent scattered plates in an area orzone. Too many dry plates in an area will endanger the lifetime of the refractory.

Elements that have large leaks cannot be put on back-up water because large quantities of waterwill enter the blast furnace.

The element replacement method is described in a separate procedure.


of 34 Feb 02, 2010Rev.: 1

5. MAINTENANCE ROUNDS

5.1 Shift Rounds

At the beginning of each new shift it is recommended to perform “water search rounds”. Theserounds shall be performed by the maintenance crew and the first smelter individually.The rounds will start in the control room where H2 values and make-up water consumption arechecked. The H2 value in top gas is a useful indicator of a cooling water leakage into the blastfurnace. The H2 value increases.At the tuyere floor the connections between the tuyere cooler holder and the tuyere cooler shall bechecked on water spillage.

It is important to record findings in a logbook.

5.2 Preventive Maintenance Rounds

With performing regular preventive maintenance rounds (once a week one level or system) aleaking cooling water circuit can be detected in an early stage. It is strongly recommended to set-up an maintenance check programme for the furnace cooling water system to be performed by adedicated team. The furnace cooling system shall be divided in practical parts which can bechecked every four weeks.

When Hearth Bottom Drains are present these drains should be checked on regular intervals.Regular intervals are:

o Once a week when NO water is drained,o When water is drained the interval time should be shortened to, let say, every day,

depending on the amount of water that is drained off.Be aware of leaving CO-gas when opening the Hearth Bottom Drain valves.

The checks shall be performed from the top of the furnace downwards.

It is important to record findings in a logbook.

An example of such a 4 weeks scheme is shown below:

Week Blast Furnace Zone Rows Tuyere

Week 1 US Plate Cooling Row 48-54 Tuyere Nose & Cooler 01-05Week 2 MS Plate Cooling Row 33-47 Tuyere Nose & Cooler 06-10Week 3 LS & Belly Plate Cooling Row 13-32 Tuyere Nose & Cooler 11-15Week 4 Tuyere & Bosh Plate Cooling Row 1-12 Tuyere Nose & Cooler 16-20

Repeat the above schedule


of 34 Feb 02, 2010Rev.: 1

6. INDICATIONS OF A LEAK

6.1 Expansion Tanks

A gradual or sharp drop in water level in the expansion tanks is an indication of a leak in thecooling water system. Also make-up water consumption is an indication of leakages in the system.

6.1.1 Make-Up Water Consumption

If make-up water consumption strongly exceeds the normal amount, it can be concluded that wateris leaving the system, either inside or outside the furnace. This can be an indication of a big leak,especially in combination with one or more of the phenomena described in the following sections.

The cooling system is provided with an alarm system at the cooling water expansion / pressurizingvessel. Based on a level transducer sensitivity of 0.4% the process control system senses acooling water loss of 96 l/h.An Alert signal will be activated when the water consumption becomes above 1 m3/h and whenthe water consumption exceeds 2 m3/h an Danger signal will be activated.

When the Alert or the Alarm signal of the make-up water consumption is activated, it is necessaryto check the readings and trends of the supply and return line flow meters of all sections.All sections are equipped with calibrated flow meters. Flow meter FE-1 is located in the manifoldsupply line and FE-2 is located in the manifold return line.

6.2 Secondary Indications

6.2.1 Tuyere Peephole Observation

Substantial leaks can be noticed if tuyere flame color reduces in intensity (peephole turns dark).

6.2.2 Water Leaving the Furnace

Around the TuyeresThe best indication for a leak is when a green dreg comes out of the seal of the tuyere ortuyere cooler.Also ammonia can leave the seals. This ammonia can be smelt, and it will leave white tracesbehind.

At the TapholeA not operated taphole (at "cold" side of the furnace) can moisten visibly, which is anindication of a leak.Be aware that the leak can occur at any location and has not necessarily to be close to thistaphole.


of 34 Feb 02, 2010Rev.: 1

If taphole leaks are detected, a specific search shall be performed. Start with the tuyere above thetaphole and expand the search to five plate circuits above the tuyere. If nothing is found, expandthe search area progressively sideways by including the next tuyeres beside the starting tuyere.

6.2.3 Flame Colour at Taphole and Tapping Behaviour

An indication that water enters the furnace can also be seen by the flame color at the taphole,which turns from blue into yellow.Also irregular tapping behavior can be observed like abnormal splashing or other irregularities tobe noticed by experienced furnace operators.

6.2.4 Blast Furnace Gas Analyses

Water leaks that appear in the lower furnace, like the tuyere and bosh area, can be noticed bydeviations of the H2-content of the BF-gas analyses. The accuracy of Hydrogen measurement isdepending on measuring principle, make and type. Accuracy is typical 0.4% which gives a leakdetection larger than 1.5m3/hr. If the leak is in the lower part of the furnace, leaks in the upperfurnace cannot be detected in this way as the water is not connected to hydrogen gas.

6.3 Magnetic Flow Meter

Magnetic flow meters are able to show large leaks only. Therefore in case make-up waterconsumption increases, flow meters will be the first instruments for a quick scan for leaks on asection.Note that although flow meters are installed extensively, leak searching by operators with the helpof tests in this report should be done at all times.

Calculating with 100m3/hr (normal flow is 75% of full scale) and 90 seconds of tolerance time(typical value for a plate cooling panel) gives an alarm of respectively 7.5 ltr and 10 ltr for E&H andKrohne measuring devices. This means that operators will not be warned until this value isreached and this indicates that operators always should follow the conventional leak searchingprocedures irrespective of using two flow meters.

A possible leak as a flow rate will not be detected directly in case the leak will not exceed 0.3% or0.4% of the full scale of the flowmeter.

Other method is actual reading versus history, see chapter 7.1.


of 34 Feb 02, 2010Rev.: 1

7. PROCEDURES FOR LEAK SEARCHING

When it is evident that a leak or leaks occur in the cooling water system by analysing the data fromsection 6, detailed leak searching procedures can be performed according to the different stagesas mentioned in this chapter. The procedures are described below and shall be performed in thecorrect order as stated below.

The normal operation situation is shown below. This situation is similar for tuyere cooling. Thetuyere cooling however is not connected in series, each tuyere is served by a dedicated supplyfrom the manifold.

Normal Operation


of 34 Feb 02, 2010Rev.: 1

7.1 Procedure 1 – Detection by Flow Meter Readings

Flow Meter Readings

Of each section, the flow meter reading history shall be carefully compared with the actualreadings. When the actual readings of the FE-1 and FE-2 flow meters differs more than the normalreading trends, it is a strong indication of a possible leaking element in the particular section.The status of the flow circuit flow monitors shall be assessed from alarm status list in the processcontrol system. The flow monitor alarms will be set at 80% of the nominal flow. The setting israther course, 20% could be as high as 2 m3/h.

Each individual tuyere nose and body have their own flow meter in the supply and return line. Theflow meter reading can therefore be compared on a much more detailed level.Each individual tuyere cooler have their own flow meter in the return line only. The flow meterreadings can therefore not be used to surge for a leak in the tuyere cooler.


of 34 Feb 02, 2010Rev.: 1

7.2 Procedure 2 – Detection by Closing Manifold Supply Valve

This procedure shall only be performed on a circuit and for the shortest time possible and cannotbe performed in areas with high heat loads (Tuyere, Bosh, Belly and LS zone) and can only bedone if the heat loads are acceptable at the time of the test. If the test is done with high heat loads,damage to the cooling elements and refractory can occur.

Remove the cap from the circuit return 3-way valve and turn it to obtain an open outlet. Dischargereturn water to the trough.Now turn the circuit supply 3-way valve to stop the flow and simultaneously watch the opendischarge jet.If the discharge jet stops immediately, there will be no leaking element in this circuit. Turn bothvalves to their original position, the supply valve first, and place back the cap.Continue with this procedure on further circuits until the leaking circuit is found as described below.If the discharge jet does not stop immediately after turning the supply valve, so water keepscoming out, there is a leaking element in this circuit.This water is driven out by the BF gas that is entering the leaking element.

If after a while the return water starts sputtering and the gas can be measured or lit, there is nodoubt, the leaking circuit is found.

If this approach is not successful, because the leak is too small, proceed with section 7.4 and/orsection 7.5.


of 34 Feb 02, 2010Rev.: 1

7.3 Procedure 3 – Detection by Partially Closing Manifold Supply Valve

Instead of fully closing the supply valve as per section 7.2 this procedure describes the partialclosure of the manifold supply valve. This procedure shall be performed on the tuyere nose, bodyand cooler to maintain cooling water flow on these elements at all times.

Remove the cap from the circuit return 3-way valve and turn it to obtain an open outlet. Dischargereturn water to the trough.Now turn the circuit supply 3-way valve to partially stop the flow and simultaneously watch theopen discharge jet.

In case of a substantial leak, this leak can be detected by throttling the 3-way ball valve. Smallbubbles of gas will be entrained in the water resulting in a “milky” color. If there is no substantialleak the water stream is completely transparent.

WARNING

The return water shall never exceed a temperature of 60oC.


of 34 Feb 02, 2010Rev.: 1

7.4 Procedure 4 – Detection by Pressure Indication

Procedure by Pressure Indication

For detection of small leaks the normal operating pressure of the return manifold has to bemeasured by reading the pressure indicated on the temporary installed portable PI’s on theindividual circuits.

Connect a portable pressure device to the free port of the 3-way circuit return valve.Turn the supply and return valve to isolate the circuit and wait until circuit starts to heat up.

The following guidelines should be used during the procedure:

If the pressure starts to rise there is no leak; If the pressure drops and stabilizes at furnace gas pressure, which is close to normal

operating water pressure there is a leaking element; If the pressure drops significantly below furnace gas pressure or to zero, there is a leak in a

coupler or pipe fitting. Locate failure, take action and repeat the test.

WARNING

Interruption of flow, especially in high temperature zones, shall be done in the shortest possible


of 34 Feb 02, 2010Rev.: 1

time. Pressure rise in a circuit might cause damaged elements and burned elements.Never leave the area unattended. See section 3.4.

7.5 Procedure 5 – Detection by CO Measuring

Leak Detection Vessel

An alternative for leak detection is with the aid of a Gas Leakage Detection Vessel or CO vessel.The method can be used to detect small leaks on tuyeres, circuits of plates, individual plates andcooling boxes. This specially designed vessel is connected to the discharge. The vessel will trapair/BF gas which can be sampled. The vessel is always ready for operation because four vesselsshould be available on each floor and attached to the return troughs.

The vessel can only be used when the water pressure is reduced to below furnace pressure. Thiscan be achieved by throttling the supply valve. Never close the supply valve completely when theprocedure is performed on tuyeres.

The duration of the flow over this vessel shall be maximum 10 minutes for plate coolers and 3 tomaximum 5 minutes for the tuyeres. The time shall be reduced when the water temperatureexceeds 60oC.

WARNING


of 34 Feb 02, 2010Rev.: 1

Use the appropriate protective measures when working in a CO contaminated area.

Position the portable Leak Searching (LS) vessel on a support frame, which is hinged to the troughof the section to be investigated.

For general remarks see section 3.

Procedure: Connect with a hose the LS vessel to the free port of the 3-way circuit return valve; Turn the 3-way return valve in a position that water flows through the LS vessel; Let the water leave the vessel at the side into the trough; Throttle the 3-way supply valve till there is a reduced water flow (no steam allowed), this to

ensure the cooling water pressure is under the blast furnace pressure, so that gas will leakinto the water;

While the water runs through the vessel, wait for a short time (5-10 minutes), enabling CO gasto separate from the water;

Open the ball-valve on top of the LS vessel and measure, with a CO-meter, the possiblepresence of CO above the water level in the vessel;

When CO gas is detected, than this is a clear indication of a leak in the particular circuit. Onan average, 500 to 1000 ppm CO gas will be measured in case of a leaking circuit;

After each circuit check the vessel shall be emptied by draining the water and release thetrapped air/gas, otherwise CO will be measured on all consecutive circuits;

Return valves to the original positions after the test.


of 34 Feb 02, 2010Rev.: 1

Searching Procedure by Detecting CO


of 34 Feb 02, 2010Rev.: 1

7.6 Procedure 6 – Element Detection in Circuit

Element Detection

Once a leaking circuit has been detected, see section 7.2, 7.4 and 7.5, the following elementdetection procedure can be performed.During this procedure the circuit will be divided into smaller parts to detect the leaking element.


Procedure: Close the circuit supply and return 3-way valve of the circuit; Separate the circuit in two parts by disconnecting one of the ball-couplers in the middle of the

circuit; Connect the discharge hoses (lines) to both open coupler parts (* see note below); Open the supply and return valve; Connect Leak Searching vessel; The second part of the circuit will now run in back-flow, see figure above; Discharge water to a convenient location.

* Note: Both temporary discharge hoses (lines) requires discharge valves at the end andconnection lines with isolation valves for connecting the LS Vessel.


of 34 Feb 02, 2010Rev.: 1

Each part of the circuit can be easily checked for normal leakages by Procedure A. If this is notsuccessful (in case of a small leak) apply Procedure B.

7.6.1 Procedure 6A - Detection of Larger Leaks

Apply procedure as described in section 7.2 on both circuit parts for finding the part with theleaking element.

7.6.2 Procedure 6B - Detection of Small Leaks

Check first circuit part Open the valve of the first circuit part to the Leak Searching vessel; Close the discharge valve of the first circuit part; Connect with a hose the LS vessel to the free port of the 3-way circuit return valve; Turn the 3-way return valve in a position that water flows to the LS vessel; Let the water run through the LS vessel and leaving the vessel at the side into the through; Throttle the 3-way supply valve till there is a reduced water flow (no steam allowed); While the water runs through the vessel, wait for a short time (5-10 minutes), enabling CO gas

to separate from the water; Open the ball valve on top of the LS vessel and measure, with a CO-meter, the possible

presence of CO above the water level in the vessel; When CO gas is detected, than this is a clear indication of a leak in the particular circuit. On

an average, 500 to 1000 ppm CO gas will be measured in case of a leaking circuit; After each circuit check the vessel shall be emptied by draining the water and release the

trapped air/gas, otherwise CO will be measured on all consecutive circuits.

Even when a leaking element is found in the first part the second part has to be checked as well toassure that this part has no leaking elements as well.The same procedure has to be applied on the second circuit part.


of 34 Feb 02, 2010Rev.: 1

8. LEAK SEARCH SCHEDULE

The procedures described in section 7 shall only be performed for the elements in the schemebelow.

Blast Furnace Element Procedure

Zone 1 2 3 4 5 6

Tuyere Tuyere Nose X X X

Tuyere Tuyere Body X X X

Tuyere Tuyere Cooler X X X

Tuyere Plate X X X X X

Bosh Plate X X X X X

Belly Plate X X X X X

LS Plate X X X X X

MS Plate X X X X X X

US Plate X X X X

HB & BD Valve(1) X

(1) See QMMC manual for hot blast valves, to be confirmed by supplier.

Procedure 1 – Detection by Flow Meter Readings Section 7.1Procedure 2 – Detection by Closing Manifold Supply Valve Section 7.2Procedure 3 – Detection by Partially Closing Manifold Supply Valve Section 7.3Procedure 4 – Detection by Pressure Indication Section 7.4Procedure 5 – Detection by CO Measuring Section 7.5Procedure 6 – Element Detection in Circuit Section 7.6


of 34 Feb 02, 2010Rev.: 1

9. CIRCUIT AND ELEMENT ISOLATION

Application of this section is only to be considered if other circumstances make it impossible tocontinue with the Element Detection procedure according to section 7.6.

9.1 Circuit Isolation

Circuit on Back-up

A leaking circuit will be connected to an alternative back-up water source and operates underreduced flow and pressure conditions. This reduces the amount of water entering the furnace butinsures the area will still be cooled.

WARNING

Be aware that, by applying this option, the elements downstream the leaking element areendangered by reduced cooling capacity due to the fact that gas can enter the leaking elementand that this dangerous CO gas will leave the cooling system and is discharged into the open airat the platforms.In this situation special protection measurements have to be taken to avoid poisoning of people in


of 34 Feb 02, 2010Rev.: 1

the area. It is strongly advised to reduce the time period of this undesirable situation to a minimum.

There is still a change that water enters the furnace. Cooling water in the furnace will cause severerefractory lining damage and will negatively influence blast furnace operation.


Procedure: Connect the free port of the circuit supply valve with a back-up water source, using a hose; Turn the supply and return valve into "isolation-position”, this is the position where the 3-way

ball valve is closed from water supply and return manifolds.; Provide the isolated circuit with alternative water by opening the back-up water valve; Throttle this valve to obtain a circuit pressure below the furnace gas pressure as follows:

Use the discharge jet as an indicator and trim the valve until it is sure that a mixture ofwater and gas is leaving the circuit;

Perform regular checks on the discharge jet to see if the isolated circuit is still runningunder stable conditions.

.During the circuit isolation mode the circuit outlet has to be checked regularly (and trottled ifnecessary) until it is possible to perform a element detection procedure according to section 9.2.

In case the leak increases, (to be noticed by the need to correct the flow) the urge to performelement detection and isolation will be growing.

WARNING

Be aware that the whole circuit will be subject to progressing reduction of cooling capacity, peakheat loads cannot longer be covered and the other elements in the circuit can be damaged easily.

Final decision how to proceed has to be based on balancing of risks depending on circumstances.It is strongly advised to restrict a circuit isolation period as short as possible.

This procedure shall never be performed on the tuyere elements.


of 34 Feb 02, 2010Rev.: 1

9.2 Element Isolation

Element Isolation

A leaking element will be connected to an alternative water source and operated under reducedflow and pressure conditions. This reduces the amount of water entering the furnace.An isolated Element shall be replaced according to the schedule in section 4.


Procedure: Close the supply and return valve; Uncouple the couplings to the left and to the right of the leaking element; By-pass the leaking element, using a hose (take care that the amount of trapped air is as

small as possible); Recover the water flow on remaining elements by opening supply and return valve; Connect the leaking element with alternative back-up water using a hose; Connect a hose to the leaking element return water to allow water discharge to a convenient

location; Provide isolated leaking element with water by opening alternative back-up water valve; Throttle this valve to obtain leaking element pressure below furnace gas pressure as follows:

Use the discharge jet as an indicator and trim the valve until it is sure that a mixture ofwater and gas is leaving the leaking elements discharge hose;

Perform regular checks on the discharge jet to see if isolated element is still running under


of 34 Feb 02, 2010Rev.: 1

stable conditions.

9.3 Possibilities for Continuation

During circuit isolation mode, the discharge jet has to be checked regularly (and trimmed ifnecessary) until it is possible to replace the element.In case the leak increases (to be noticed by the need to correct the flow steadily downward) theurge to perform element replacement will be growing.In late campaign life it can be considered to set an element dry, if it is clear that the element isleaking substantially and a lot of water is entering the furnace. Especially if no further elementreplacements are planned due to furnace age, fill the element with grout and use spray water onthe outside of the furnace.


of 34 Feb 02, 2010Rev.: 1

10. TUYERES LEAK SEARCHING AND DETECTION

10.1 General

A good and leak-free functioning of tuyere equipment is essential for a stable operation of the blastfurnace. Early detection of leaks is therefore of great importance. Preventive leak detection withthe leak searching vessel is strongly encouraged, see section 7.5.

Each tuyere consist of a tuyere nose, a tuyere body and a tuyere cooler. The tuyere nose andbody are integrated in one piece of equipment, referred to as the tuyere tip. Each of these itemsare served by its own dedicated cooling water supply and return system. The tuyere nose by thehigh pressure cooling water system and the tuyere body and cooler by separate low pressurecooling water systems.The location of each of the items are clarified in the picture below.

Built-up of pressure and steam in a closed cooling section shall at all times be prevented. Thiscondition is a high risk for personnel and equipment. If such a situation is taking place after all,ensure that the pressure is released gradually by opening the return valve first and opening thesupply valve directly after that until a healthy stream is re-instated.

WARNING


of 34 Feb 02, 2010Rev.: 1

WARNING

A pressure test is never done on a tuyere installed in the blast furnace, due to the high heat loads,even with a shutdown furnace. This is considered an unacceptable risk that is not necessary asother more accurate leak detection methods are available as described in this section.

Likewise the cooling water flow to the tuyere can never be stopped completely.

All leak detection methods for the tuyeres maintain a sufficient flow of cooling water to the tuyereat all time.

The normal operation situation is shown below and is similar for the HP tuyere nose and the LPtuyere body and tuyere cooler cooling systems.


of 34 Feb 02, 2010Rev.: 1

10.2 Tuyere Nose

Perform the actions in the following order and only these actions to prevent damages to the tuyerenose: Perform Procedure 1 – Detection by Flow Meter Readings, see section 7.1; Perform Procedure 3 – Detection by Partially Closing Manifold Supply Valve, see section 7.3; Perform Procedure 5 – Detection by CO Measuring, see section 7.5.

When a leak in the tuyere nose is detected this element shall be set dry and the HP cooling watersupply and return lines shall be diverted to the tuyere body according to the procedure describedhereafter.

WARNING

A tuyere nose can only be set dry on a Danieli-Corus design of tuyere nose design with therelatively small tuyere nose channel. On other types of tuyere noses, with spiral cooling channelsfor instance this shall never be done because of the risk of large burning back of the nose. Thismust be checked with the tuyere supplier or designer.

10.2.1 Connecting Tuyere Body to HP System

With the two canal (low pressure body, high pressure nose) tuyere design, a leaking nose can beset dry and sacrificed to prevent water leakage into the furnace. In this case the body isrecommended to be connected to the high pressure supply of the nose to increase the water flowand pressure in the body, resulting in increased cooling for the individual tuyere.


of 34 Feb 02, 2010Rev.: 1

Normal Operation

10.2.2 Setting the Tuyere Nose Dry

WARNING

A safety valve (PSV) is to be set on the Camlock coupling of the spare connections in the supplyand return lines of the tuyere nose. The safety valves should operate at 900 kPa(g) and a max.temperature of 150 oC, with water/steam.

The two safety valves are required to prevent the chance that any pressure build-up in the tuyerenose occurs if water is still present and it cannot escape into the furnace, as this can lead to apotentially dangerous situation. Any blockage in the tuyere nose by slag or molten copper of thenose require two PSV’s to protect both the supply and return lines and hoses.

The relief opening of the PSV’s shall always be directed away from personnel.

Operating in this situation can be continued until the next furnace shutdown when the tuyere shallbe replaced. During this period the tuyere should be more regularly inspected and tested for aleaking body and any unusual behaviour.

10.2.3 Re-directing HP Tuyere Cooling Water to Tuyere Body

For a safe re-direction of the HP tuyere cooling water supply from the tuyere nose to the tuyerebody it is recommended to follow the following steps:


of 34 Feb 02, 2010Rev.: 1

WARNING

Hoses can become hot so handle with care and wear heat protective cloves and other personalprotective equipment like face covers against steam or hot water.

Connect a hose of suitable length between the spare HP cooling water supply and the LPsupply 3-way ball valve of the tuyere body under concern;

Install PSV’s with camlocks on the HP supply and return to the drain (open connection); Switch the LP supply 3-way ball valve to HP cooling water and open the spare valve the

hose is connected to. The tuyere body is now on HP cooling water; Switch the HP tuyere nose supply and return to the closed position simultaneously, thus

the safety valves are now connected to the blocked (dry) tuyere nose; Install warning signs on LP and HP manifold which states “Tuyere Body on HP”.

WARNING

Before installing the PSV’s be sure that the PSV’s are functioning correctly and the dischargeopening is free. After use and before storing the spare PSV’s shall be cleaned and serviced.

The created situation is shown below.

Tuyere Nose Isolated – Body on High Pressure

PSV

PSV

PSV


of 34 Feb 02, 2010Rev.: 1

WARNING

When the tuyere nose and body are to be replaced the pressure built-up in the HP and LP circuitsshall be released at the headers in a controlled way. The hose shall be unlocked from a distancewith a hook at both sides simultaneously. Hot water, steam or even molten slag could dischargefrom the uncoupled hose. Personnel shall be made aware of this dangerous situation. Thereplacement of the tuyere is part of another procedure and is not part of this procedure.

10.3 Tuyere Body

Perform the actions in the following order and only these actions to prevent damages to the tuyerebody:

Perform Procedure 3 – Detection by Partially Closing Manifold Supply Valve, see section 7.3; Perform Procedure 5 – Detection by CO Measuring, see section 7.5.

If a leaking tuyere body is found the furnace should be shutdown as soon as possible to replacethe tuyere.

10.4 Tuyere Cooler

Perform the actions in the following order and only these actions to prevent damages to the tuyerecooler: Perform Procedure 3 – Detection by Partially Closing Manifold Supply Valve, see section 7.3; Perform Procedure 4 – Detection by Pressure Indication, see section 7.4; Perform Procedure 5 – Detection by CO Measuring, see section 7.5.

If a leaking tuyere cooler is found the furnace should be shutdown as soon as possible to replacethe tuyere.

11. PLATES LEAK SEARCHING AND DETECTION

Perform the actions in the following order: Perform Procedure 1 – Detection by Flow Meter Readings, see section 7.1; Perform Procedure 2 – Detection by Closing Manifold Supply Valve, see section 7.2; Perform Procedure 3 – Detection by Partially Closing Manifold Supply Valve, see section 7.3; Perform Procedure 4 – Detection by Pressure Indication, see section 7.4; Perform Procedure 5 – Detection by CO Measuring, see section 7.5; Perform Procedure 6 – Element Detection, see section 7.6.

When a leaking element is detected the procedure can be continued by replacing the element witha new one. However, if circumstances require so, the element can be isolated according to section9.2, waiting for a more convenient time to replace the element.

2b0565g1 m143 d001 rev 1 leak searching proceedure

Documents

bhushan document

element detection

dc document

green field bf document

tuyeres leak searching

bhushan project

d001 page

element isolation