PRESENTATION PRESENTATION ON ON

COKE DRY COOLING COKE DRY COOLING PLANTPLANT

(CDCP) BOILERS, (CDCP) BOILERS, COKE OVEN’S ZONECOKE OVEN’S ZONE

THERMAL THERMAL POWER POWER PLANTPLANTByBy

M.SRINIVASM.SRINIVAS, , A.M , A.M ,

E.NO:105358E.NO:105358

CDCP –Boilers,CDCP –Boilers, T.P.PT.P.P

Coke Dry Quenching TechnologyCoke Dry Quenching Technology

Overview of CDQ (Coke Dry Quenching) Overview of CDQ (Coke Dry Quenching) system_system_

The coke oven consists of plate-like carbonization chambersThe coke oven consists of plate-like carbonization chambers alternately arranged in a sandwich form to achieve higher thermalalternately arranged in a sandwich form to achieve higher thermal efficiency in carbonization.efficiency in carbonization. Raw material placed in the carbonization chambers is heated to aRaw material placed in the carbonization chambers is heated to a temperature between approximately 1100 and 1350oC through thetemperature between approximately 1100 and 1350oC through the combustion of blast furnace /coke oven gas in the combustion combustion of blast furnace /coke oven gas in the combustion

chambers,chambers, which are located on both sides of the carbonization chamberswhich are located on both sides of the carbonization chambers beyond the refractory brick.beyond the refractory brick. The heated raw material is not exposed to air for approximately 12 The heated raw material is not exposed to air for approximately 12

to 14 hours to allow carbonization to proceed. to 14 hours to allow carbonization to proceed. In this process, the fixed carbon contained in the raw material fuses In this process, the fixed carbon contained in the raw material fuses

and solidifies to become redhot coke in the lower section of the and solidifies to become redhot coke in the lower section of the carbonization chambers. carbonization chambers.

The volatile component in the raw material vaporizes and The volatile component in the raw material vaporizes and decomposes,decomposes,

becoming gas. After escaping from the coke surface, the gas isbecoming gas. After escaping from the coke surface, the gas is collected through a pipe located in the upper section of thecollected through a pipe located in the upper section of the carbonization chambers. carbonization chambers.

When carbonization is complete, the red hot coke When carbonization is complete, the red hot coke (approximately 1,050oC) is discharged from the coke (approximately 1,050oC) is discharged from the coke oven and then carried to the top of the chambers. oven and then carried to the top of the chambers.

The coke is then fed to the chambers and while it The coke is then fed to the chambers and while it

descends through the chamber, is cooled with descends through the chamber, is cooled with circulating gas blown from the bottom of the circulating gas blown from the bottom of the chamber.chamber.

After it has cooled to approximately 200oC, the coke After it has cooled to approximately 200oC, the coke is ejected from the bottom, while the circulating gas is ejected from the bottom, while the circulating gas that has been heated to 800oC or higher generates that has been heated to 800oC or higher generates high-temperature and high pressure steam in the high-temperature and high pressure steam in the boiler. boiler.

The gas is purified by a dust collector and then sent The gas is purified by a dust collector and then sent back to the chambers for recycling. back to the chambers for recycling.

The generated steam is used as process steam or for The generated steam is used as process steam or for powerpower

JUST LOOK AT THE JUST LOOK AT THE OVERVIEW OF COKE OVERVIEW OF COKE DRYCOOLING PLANTDRYCOOLING PLANT

ADVANTAGES OF DRY ADVANTAGES OF DRY COOLING OF COKECOOLING OF COKE

FEATURES OF OUR FEATURES OF OUR CDCPCDCP

WE HAVE THREE CDCP’S AND NEW CDCP NO 4WE HAVE THREE CDCP’S AND NEW CDCP NO 4 EACH CDCP HAS FOUR COOLING CHAMBERS WITH EACH CDCP HAS FOUR COOLING CHAMBERS WITH

BIOLERSBIOLERS EACH CHAMBER COOLING CAPACITY IS 50-52T/HREACH CHAMBER COOLING CAPACITY IS 50-52T/HR TWO CHAMBERS ARE IN OPERATIONTWO CHAMBERS ARE IN OPERATION ONE CHAMBER IS ON HOT STAND BYONE CHAMBER IS ON HOT STAND BY ONE MORE CHAMBER IS IN REPAIRONE MORE CHAMBER IS IN REPAIR INCOMING COKE TEMPERATURE :1000-1050 INCOMING COKE TEMPERATURE :1000-1050 ooCC COOLED COKE TEMPERATURE :160-180COOLED COKE TEMPERATURE :160-180ooCC STEAM PRESSURE :40 ATASTEAM PRESSURE :40 ATA STEAM TEMPERATURE :440STEAM TEMPERATURE :440ooCC STEAM PRODUCTION OF EACH BOILER:25 T/HrSTEAM PRODUCTION OF EACH BOILER:25 T/Hr CIRCULATING GAS COMPOSITION :CIRCULATING GAS COMPOSITION :

CO2 : 6-12%, O2 : MAX 1%, CO : 6-14%, H2 : 3-5% , CO2 : 6-12%, O2 : MAX 1%, CO : 6-14%, H2 : 3-5% , N2 : REST N2 : REST

BOILER FEED WATER QUALITY : BOILER FEED WATER QUALITY : Ph value:9 to 9.5,Conductivity: <100 Micro Mhos, PO4: Ph value:9 to 9.5,Conductivity: <100 Micro Mhos, PO4:

< 20 PPM, Si:<1 PPM< ,Total Dissolved Salts : <1 PPM.< 20 PPM, Si:<1 PPM< ,Total Dissolved Salts : <1 PPM. POWER GENERATION :11-14 MWPOWER GENERATION :11-14 MW

DRAWBACKS OF WET DRAWBACKS OF WET QUENCHING QUENCHING

SENSIBLE HEAT LOSS TO ATMOSPHERESENSIBLE HEAT LOSS TO ATMOSPHERE

AIR POLLUTIONAIR POLLUTION

WATER POLLUTIONWATER POLLUTION

COKE QUALITY DETERIORATIONCOKE QUALITY DETERIORATION

WASTE HEAT RECOVERY BOILERWASTE HEAT RECOVERY BOILER

In waste heat recovery boiler the steam is In waste heat recovery boiler the steam is produced by utilizing waste heat in the produced by utilizing waste heat in the circulating gases coming out of cooling circulating gases coming out of cooling chamber. The gases first pass through chamber. The gases first pass through superheater, then through evaporator superheater, then through evaporator and then through economizer.and then through economizer. The gases The gases after leaving the economizer pass after leaving the economizer pass through cyclones and then re-circulated through cyclones and then re-circulated to the chamber by running the mill fan. to the chamber by running the mill fan.

BOILER DRUM

CHAMBER

DCB

CWP”S

MILL FAN

SAFETY VALVE

HOT COKE

N 2

3TON

TOBPTS

ECONOMISER

EVEPORATOR

SH

126 VALVEG1,3

G2, 4

CDCP SCHEMATIC DIAGRAM

VENT

Slime Separater

CYCLONE

FEED UNIT

DRUM LEVEL NORMAL

LOWER LEVEL

BOILER DRUM

CHAMBER DCB

CWP”S

MILL FAN

SAFETY VALVE

HOT COKE

N 2

2TON3TON TO

3TON BKR.

TOBPTS

ECONOMISER

EVEPORATOR

SH

126 VALVEG1,3

G2, 4

CDCP SCHEMATIC DIAGRAM

VENT

Slime Separater

CYCLONE

FEED UNIT

PROCESS DESCRIPTIONPROCESS DESCRIPTION The waste heat recovery boiler used in coke dry The waste heat recovery boiler used in coke dry

cooling plant is forced circulation type boiler.cooling plant is forced circulation type boiler. In In this the de-mineralized water after de-aeration this the de-mineralized water after de-aeration enters the feed pump, which pumps the water to enters the feed pump, which pumps the water to the feed unit, and then to the boiler.the feed unit, and then to the boiler. The purpose The purpose of feed unit is to regulate the flow of water.of feed unit is to regulate the flow of water.

The water first enters into the economizer, The water first enters into the economizer, receives sensible heat from circulating gases receives sensible heat from circulating gases passing over the tubes, and then enters into passing over the tubes, and then enters into drum.drum. The water from drum goes to circulating The water from drum goes to circulating pump, which pumps the water to evaporator pump, which pumps the water to evaporator through slime separator. As the name indicates, through slime separator. As the name indicates, the slime separator separates the slime from the slime separator separates the slime from water.water. The slime from separator should be The slime from separator should be removed periodically. removed periodically.

In evaporator the water at saturation In evaporator the water at saturation temperature receives latent heat of evaporation temperature receives latent heat of evaporation from circulating gases passing over the tubes from circulating gases passing over the tubes and enters into the drum.and enters into the drum. In drum the steam In drum the steam will be separated from water particles by steam will be separated from water particles by steam separators and the dry saturated steam goes to separators and the dry saturated steam goes to the superheater and the water is circulated the superheater and the water is circulated again and again through circulating pump and again and again through circulating pump and slime separator.slime separator. The circulation ratio used here The circulation ratio used here is 5:1. is 5:1.

The dry saturated steam entering into the The dry saturated steam entering into the superheater gets superheated by receiving heat superheater gets superheated by receiving heat from circulating gases passing over the from circulating gases passing over the superheater tubes.superheater tubes. The superheated steam is The superheated steam is then supplied to then supplied to BACK PRESSURE TURBINE STATIONBACK PRESSURE TURBINE STATION..

BACK PRESSURE TURBINE BACK PRESSURE TURBINE STATIONSTATIONThe back pressure turbine station is the name indicates, the steam in The back pressure turbine station is the name indicates, the steam in

which is expanding above the atmospheric pressure that steam can which is expanding above the atmospheric pressure that steam can be utilized as a process steam.be utilized as a process steam.

Generally in conventional turbines in thermal power plant the steam is Generally in conventional turbines in thermal power plant the steam is expanded up to condenser pressure in turbine. The same steam is expanded up to condenser pressure in turbine. The same steam is condensed and re-circulated. But here BPTS the steam is expanding condensed and re-circulated. But here BPTS the steam is expanding up to 2.5ata, after recovering the power in back pressure turbine.up to 2.5ata, after recovering the power in back pressure turbine.

There are two back pressure turbines for utilizing the steam produced There are two back pressure turbines for utilizing the steam produced in all waste heat boilers.in all waste heat boilers.

After recovering the power by expanding steam in turbine, exhaust After recovering the power by expanding steam in turbine, exhaust steam is feed to chilled water plant-1 for refrigerating purpose (now steam is feed to chilled water plant-1 for refrigerating purpose (now those are under shut-down, this steam is bleeding to atmosphere). those are under shut-down, this steam is bleeding to atmosphere). One controlled extraction (7ata steam) is provided after HP stages One controlled extraction (7ata steam) is provided after HP stages of the turbine to supply process steam to coal chemical plant.of the turbine to supply process steam to coal chemical plant.

Speed of the turbine is reduced to generator to operating speed by a Speed of the turbine is reduced to generator to operating speed by a reduction gear box. reduction gear box.

Power generated at 11kv is feed to GSB-4 of electrical control room of Power generated at 11kv is feed to GSB-4 of electrical control room of TPP and after getting stepped up to 220kv by transformer-4, it is TPP and after getting stepped up to 220kv by transformer-4, it is connected to grid. connected to grid.

Back Pressure Turbine Station parametersBack Pressure Turbine Station parameters

Turbine Type : EG 400-2Turbine Type : EG 400-2 Make : BHELMake : BHEL Capacity : 2 Capacity : 2 X X 7.5 MW 7.5 MW No of Stages : 1+13+ 4No of Stages : 1+13+ 4Steam Consumption : 70 tones/ hr per turbine at full load Steam Consumption : 70 tones/ hr per turbine at full load Steam Pressure : 35ata (live steam pressure) Steam Pressure : 35ata (live steam pressure) Steam Temperature : 430ºC Steam Temperature : 430ºC Extraction Steam Pressure : 7ata Extraction Steam Pressure : 7ata Extraction Steam Temperature : 250ºCExtraction Steam Temperature : 250ºCExtraction Steam Flow : 45 tones/hrExtraction Steam Flow : 45 tones/hrExhaust Steam Pressure : 2.5ata Exhaust Steam Pressure : 2.5ata Exhaust Steam Temperature : 163ºCExhaust Steam Temperature : 163ºCExhaust Steam Flow : 25 tones/hrExhaust Steam Flow : 25 tones/hrTurbine Speed : 8083 rpmTurbine Speed : 8083 rpmGenerator Speed : 3000 rpmGenerator Speed : 3000 rpmStator Voltage : 11kv Stator Voltage : 11kv Maximum Current : 492 AmpsMaximum Current : 492 Amps

BACK PRESSURE TURBINE BACK PRESSURE TURBINE STATIONSTATION

COKE OVEN BATTERY –COKE SIDECOKE OVEN BATTERY –COKE SIDE

COKE CARCOKE CAR

TIE ROD

BUCKET

HOOKS

BUFFER

PEDASTRAL

ROPE

ROPE PULLEY

LOWER TRAVERSE

UPPER TRAVERSE

LIFTING OF BUCKET WITH HOT COKE

M1 M2 M3 M4

R1 R2 R3 R4

THREE STAGEGEAR COUPLING

GEAR COUPLING ROPE DRUM

GEAR BOX

BRAKES

DRUMCONTROLER

MOTOR RESISTANCE BOXES R1, R2, R3, R4

COOLING CHAMBER

Charging of hot coke in to Charging of hot coke in to chamberchamber

Cyclone Separator

Waste Heat Boiler

MILL FAN &AUXIALLARY FANSMILL FAN &AUXIALLARY FANS

MILL FAN or SMOKE FANMILL FAN or SMOKE FAN

RESERVE FANRESERVE FAN

OLD DISCHARGING DEVICE

ROTARY DISCHARGING ROTARY DISCHARGING DEVICEDEVICE

ROTARY DISCHARGEROTARY DISCHARGE

Rotary Discharge

Rotary Discharge

No Gas Leakage

Rotary Discharge

Rotary Discharge

Conventional Discharging

HYDRAULIC REGIME BEFORE ROTARY DEVICEHYDRAULIC REGIME BEFORE ROTARY DEVICE

HYDRAULIC REGIME AFTER RORARY DEVICEHYDRAULIC REGIME AFTER RORARY DEVICE

2T BUNKER

3T BUNKER2TBUNKER

127128

LOCKGATE

WATER COOLED

CYCLONES02 NOS.

TO MILL FAN

DPTSTATION

HOT AIR COMING FROM CHAMBER

CHAMBER

DCB

BOILER TUBES

FLOW DIAGRAM OF CDCPFLOW DIAGRAM OF CDCP

MAIN PROCESS PARAMETERS IN MAIN PROCESS PARAMETERS IN CDCPCDCP

01. Gross yield of coke/chamber (dry):01. Gross yield of coke/chamber (dry): 52 T/Hr.52 T/Hr. 02. Temperature of cooled coke: 180 – 200 °C 02. Temperature of cooled coke: 180 – 200 °C 03. Temperature of charged coke: 1000 – 1100 °C 03. Temperature of charged coke: 1000 – 1100 °C 04. Temperature of Circulating gas before boiler : 600 04. Temperature of Circulating gas before boiler : 600

–800 °C –800 °C 05. Temperature of Circulating gas before 05. Temperature of Circulating gas before

Chamber:180 – 200 °C Chamber:180 – 200 °C 06. Steam production for one chamber:22 – 25 T/Hr.06. Steam production for one chamber:22 – 25 T/Hr. 07. Pressure of Super heated steam:39 – 40 ata07. Pressure of Super heated steam:39 – 40 ata 08. Temperature of super heated steam:430 – 450 °C 08. Temperature of super heated steam:430 – 450 °C 09. Amount of circulating gas/Tone of coke:1460-1540 09. Amount of circulating gas/Tone of coke:1460-1540

Nm3Nm3 10. The load on exhauster:40 – 43 A10. The load on exhauster:40 – 43 A

11. Residence time of coke in chamber:2 – 2.1 Hrs.11. Residence time of coke in chamber:2 – 2.1 Hrs. 12. Pressure after exhauster:+ 260 MM of WC12. Pressure after exhauster:+ 260 MM of WC 13. Vacuum before exhauster:- 240 MM of WC 13. Vacuum before exhauster:- 240 MM of WC 14. Capacity of main exhauster (smoke fan):160000 14. Capacity of main exhauster (smoke fan):160000

m3/Hr.m3/Hr. 15. Capacity of Reserve exhauster:40000 m3/Hr.15. Capacity of Reserve exhauster:40000 m3/Hr. 16. Quantity of coke for each discharge:1.7 Tones.16. Quantity of coke for each discharge:1.7 Tones. 17. Heating surface of Economizer:1180 m217. Heating surface of Economizer:1180 m2 18. Heating surface of Evaporator :1250 m218. Heating surface of Evaporator :1250 m2 19. Heating surface of superheater:135 m219. Heating surface of superheater:135 m2 20. Boiler drum parameters, :OD & L1600 MM, 5500 MM20. Boiler drum parameters, :OD & L1600 MM, 5500 MM 21. Pressure reducing Desuperheater-I (PRDS-I):39/12 21. Pressure reducing Desuperheater-I (PRDS-I):39/12

kg/cm2, 440/300 °C kg/cm2, 440/300 °C 22. Pressure reducing Desuperheater-II: (PRDS-II)39/6 22. Pressure reducing Desuperheater-II: (PRDS-II)39/6

kg/cm2, 440/250O Ckg/cm2, 440/250O C 23. Pressure reducing Desuperheater-IV: (PRDS-IV)12/6 23. Pressure reducing Desuperheater-IV: (PRDS-IV)12/6

kg/cm2, 300/250O Ckg/cm2, 300/250O C

CHAMBER AND AUXILARY CHAMBER AND AUXILARY UNITSUNITS

WASWAS

CIRCULATION WATER PUMPS & CIRCULATION WATER PUMPS & PHOSPHATE SOLUTION PUMPPHOSPHATE SOLUTION PUMP

DEAERATORDEAERATOR

DEAERATORDEAERATOR PRINCIPLE : A PRINCIPLE : A DeaeratorDeaerator is a device for air removal is a device for air removal

and is used to remove dissolved gases from boiler and is used to remove dissolved gases from boiler feedwater to make it non-corrosive. feedwater to make it non-corrosive.

Two basic types of deaerators exist today.Two basic types of deaerators exist today. One type of deaerator includes a vertical domed One type of deaerator includes a vertical domed

deaeration section mounted on top of a horizontal deaeration section mounted on top of a horizontal cylindrical vessel which serves as the deaerated boiler cylindrical vessel which serves as the deaerated boiler feedwater tank. This type is usually referred to as tray-feedwater tank. This type is usually referred to as tray-type (also cascade-type). type (also cascade-type).

The second type of deaerator is constructed without the The second type of deaerator is constructed without the trayed section. It has only one horizontal (or vertical) trayed section. It has only one horizontal (or vertical) vessel, in which one or more sprayers are placed to vessel, in which one or more sprayers are placed to vaporize the water. This more robust and less space vaporize the water. This more robust and less space consuming form is referred to as spray-type deaerator.consuming form is referred to as spray-type deaerator.

An alternate for this way of deaeration would be the An alternate for this way of deaeration would be the use of water treatment chemicals. Costs and use of water treatment chemicals. Costs and environmental matters have to be observed environmental matters have to be observed

Our deaerator is (tray-type, with vertical, domed Our deaerator is (tray-type, with vertical, domed aeration section and horizontal water storage aeration section and horizontal water storage

section)section)

Domed deaeration section (tray-type only)Domed deaeration section (tray-type only) At the top and in the mid portion of the feed tank an At the top and in the mid portion of the feed tank an

inverted domed vessel of sufficient size as dictated, is inverted domed vessel of sufficient size as dictated, is attached which is called the deaerator. This portion attached which is called the deaerator. This portion has internals something like perforated trays to has internals something like perforated trays to breakdown the down flow of condensate water from breakdown the down flow of condensate water from the top into fine globules to separate dissolved gases. the top into fine globules to separate dissolved gases. The heating steam, which is fed at the lower level of The heating steam, which is fed at the lower level of the dome, passes upwards to give good intermixing. A the dome, passes upwards to give good intermixing. A small vent pipe at the topmost point of this dome is small vent pipe at the topmost point of this dome is provided for venting out the dissolved gases. Some provided for venting out the dissolved gases. Some designs may have a vent condenser to trap and designs may have a vent condenser to trap and recover any water particles escaping through this recover any water particles escaping through this vent. The typical vent rate is in the range of 0.1% to vent. The typical vent rate is in the range of 0.1% to 0.25% of total deaerator capacity.0.25% of total deaerator capacity.

The deaerator dome therefore has connections for The deaerator dome therefore has connections for condensate water inlet (at one side of the dome near condensate water inlet (at one side of the dome near the top end) from previous LP feed heater and also a the top end) from previous LP feed heater and also a connection for the deaerating steam from the bottom connection for the deaerating steam from the bottom of the dome (which also heats the feed water).of the dome (which also heats the feed water).

Storage section Storage section This is generally a horizontally mounted cylindrical steel This is generally a horizontally mounted cylindrical steel

vessel with dished ends, with internal and external vessel with dished ends, with internal and external fittings and in the tray-type style with a dome on the top. fittings and in the tray-type style with a dome on the top. The size of the same depends on the unit capacity it is The size of the same depends on the unit capacity it is associated with. The storage section acts as a buffer for associated with. The storage section acts as a buffer for boiler feedwater supplying to the suction of the boiler boiler feedwater supplying to the suction of the boiler feed pumps from a pipe connected to the bottom of the feed pumps from a pipe connected to the bottom of the tank, generally in the mid portion.tank, generally in the mid portion.

During a cold start of the unit, it is possible that the During a cold start of the unit, it is possible that the water in the feed tank may be cold. At that time, the water in the feed tank may be cold. At that time, the water has to be heated to bring it up to normal operating water has to be heated to bring it up to normal operating temperature so as to expel the dissolved gases. For this, temperature so as to expel the dissolved gases. For this, a sparger pipe is provided inside the tank at the bottom a sparger pipe is provided inside the tank at the bottom level. Low pressure steam supplied to the sparger pipe level. Low pressure steam supplied to the sparger pipe provides the small amount of heat needed to increase provides the small amount of heat needed to increase the temperature of the feedwater.the temperature of the feedwater.

The storage tank is also provided with connections for The storage tank is also provided with connections for the injection of chemicals, level sight glasses, a drain, the injection of chemicals, level sight glasses, a drain, etc.etc.

DEAERATORDEAERATOR

DEAERATOR COLUMN WITH STORAGE DEAERATOR COLUMN WITH STORAGE TANK AND SAFETY DIVICE TANK AND SAFETY DIVICE

DEARATOR TANK EFFECTIVE CAPACITY : 25 m3DEARATOR TANK EFFECTIVE CAPACITY : 25 m3 D.M. WATER FROM NET WORK DEARATOR PIPE DIA :150 mmD.M. WATER FROM NET WORK DEARATOR PIPE DIA :150 mm DEARATED WATER FROM DEARATION TANK PIPE DIA : 200 mmDEARATED WATER FROM DEARATION TANK PIPE DIA : 200 mm

DEAERATORDEAERATOR

BOILER FEED PUMPBOILER FEED PUMP

BOILER FEED PUMPBOILER FEED PUMP

Feed pump is to supply the feed water to Feed pump is to supply the feed water to boiler. The feed pump is run by a H.T. boiler. The feed pump is run by a H.T. motor coupled to it. The de-mineralized motor coupled to it. The de-mineralized water after getting de-aerated is supplied water after getting de-aerated is supplied to the boiler by the feed pump through to the boiler by the feed pump through feed unit. The feed pump used is of feed unit. The feed pump used is of capacity 100 T/Hr. and discharge capacity 100 T/Hr. and discharge pressure of 58 Kg/cm2. The water from pressure of 58 Kg/cm2. The water from feed pump discharge goes to feed unit. feed pump discharge goes to feed unit. Temperature of bearings of pump is Temperature of bearings of pump is reduced by using lubricating oil SS-32.reduced by using lubricating oil SS-32.

BOILER FEED PUMPSBOILER FEED PUMPS

BOILER FEED PUMPS & BOILER FEED PUMPS & MOTORSMOTORS

BOILER FEED PUMP VIEWSBOILER FEED PUMP VIEWS

BOILER FEED PUMPBOILER FEED PUMP

BOILER FEEDING SYSTEMBOILER FEEDING SYSTEM

BOILER FEEDING SYSTEMBOILER FEEDING SYSTEM through feed unit. The feed unit has 3 through feed unit. The feed unit has 3

lines. In those 3 lines, two lines are 100% lines. In those 3 lines, two lines are 100% (one is main line and the other is bypass (one is main line and the other is bypass line) aFeed water from feed pumps is line) aFeed water from feed pumps is supplied to economizer nd the third line is supplied to economizer nd the third line is 30% line. The bypass line i.e. standby 30% line. The bypass line i.e. standby line serves the purpose, when the main line serves the purpose, when the main line is taken for any maintenance work. line is taken for any maintenance work. The 30% line is used to fill the boiler The 30% line is used to fill the boiler drum at the time of preheating the boiler drum at the time of preheating the boiler or while testing the boiler for its pressure or while testing the boiler for its pressure withstanding capacity i.e. hydraulic test. withstanding capacity i.e. hydraulic test.

BOILER FEEDING SYSTEMBOILER FEEDING SYSTEM

WATER ECONOMISERWATER ECONOMISER

The economizer of waste heat recovery The economizer of waste heat recovery boiler is of non-steaming type economizer. boiler is of non-steaming type economizer. This water economizer consists of 4 This water economizer consists of 4 bundles arranged in the second shaft, bundles arranged in the second shaft, which is having upstream gas flow. The which is having upstream gas flow. The input bundle is arranged in the upper part input bundle is arranged in the upper part and the output bundle in the lower part and the output bundle in the lower part and hence water flows in down stream. and hence water flows in down stream. Each bundle consists of two similar Each bundle consists of two similar transportable blocks. Blocks of each transportable blocks. Blocks of each bundle is supported and suspended to the bundle is supported and suspended to the boiler frame by means of beams. Each boiler frame by means of beams. Each block consists of 32 coils of 28 x 3 mm dia block consists of 32 coils of 28 x 3 mm dia steel 20 connected in parallel. steel 20 connected in parallel.

Water economizer coils are designed as S Water economizer coils are designed as S – turns with the inlet holes and they are – turns with the inlet holes and they are arranged in pairs forming the pipe bundle arranged in pairs forming the pipe bundle in staggered manner, S1 = 70 mm and in staggered manner, S1 = 70 mm and S2 = 50 mm. Lower bundles are made of S2 = 50 mm. Lower bundles are made of pipe steel 15. The economizer chambers pipe steel 15. The economizer chambers are arranged in the path of gas flue at the are arranged in the path of gas flue at the temperature zones of 170 O C approx. of temperature zones of 170 O C approx. of gases as input and at 300 O C approx. as gases as input and at 300 O C approx. as output. Water speed at the input of output. Water speed at the input of economizer is 0.4 m/sec. with water economizer is 0.4 m/sec. with water economizer heating surface is 1180 m2. economizer heating surface is 1180 m2.

BOILER DRUMBOILER DRUM

BOILER DRUMBOILER DRUM It is arranged over the roofing of the boiler and It is arranged over the roofing of the boiler and

positioned on two supports positioned on two supports Major diameter is 1600 mm, wall thickness is 40 Major diameter is 1600 mm, wall thickness is 40

mm, the drum active part length is 4400 mm, mm, the drum active part length is 4400 mm, overall length of cylindrical part is 5500 mm overall length of cylindrical part is 5500 mm and elevation of the drum axis is +23040mm.and elevation of the drum axis is +23040mm.

Having separating devices i.e. to divide steam Having separating devices i.e. to divide steam and water, the phosphate introducing, and water, the phosphate introducing, continuous blow down devices and emergency continuous blow down devices and emergency discharge are arranged in the drum.discharge are arranged in the drum.

The water steam mixture is supplied to the The water steam mixture is supplied to the drum from two sides over whole length by 4 drum from two sides over whole length by 4 pipes, branching at the inlet to the drum to pipes, branching at the inlet to the drum to from 8 inlets of 100 mm dia. from 8 inlets of 100 mm dia.

BOILER DRUM AND INTERNALSBOILER DRUM AND INTERNALS

The Separators inside the boiler drum are The Separators inside the boiler drum are designed using cyclones, which are installed in designed using cyclones, which are installed in pairs of four incoming ducts, which receive the pairs of four incoming ducts, which receive the steam / water mixture.steam / water mixture. In these cyclones, the In these cyclones, the water and steam will be separated, steam goes water and steam will be separated, steam goes to the upper part of drum and water falls to the to the upper part of drum and water falls to the lower part of drum.lower part of drum.

The steam is then collected through the steam The steam is then collected through the steam trap, situated at the top inside the boiler drum, trap, situated at the top inside the boiler drum, and sent to the superheater. Feed water is and sent to the superheater. Feed water is supplied to drum via economizer by means of supplied to drum via economizer by means of the perforated distribution pipe the perforated distribution pipe

Presidium Phosphate(Na3Po4)are introduced Presidium Phosphate(Na3Po4)are introduced into the drum through another perforated pipe.into the drum through another perforated pipe. In the lower part of the drum provision for In the lower part of the drum provision for permanent purging is provided. permanent purging is provided.

CIRCULATION PUMPCIRCULATION PUMP

CIRCULATION PUMPCIRCULATION PUMP As the boiler is forced circulation type, circulation As the boiler is forced circulation type, circulation

pump is required for the circulation of water. In pump is required for the circulation of water. In natural circulation type boilers the water natural circulation type boilers the water circulation is due to density difference only. Here circulation is due to density difference only. Here the density difference is not sufficient for the density difference is not sufficient for circulation; hence the forced circulation is circulation; hence the forced circulation is preferred. The circulation ratio is 5:1. Two preferred. The circulation ratio is 5:1. Two pumps are provided for each boiler, one is in pumps are provided for each boiler, one is in running condition and other in emergency running condition and other in emergency standby. The pressure of circulating water is 3 - standby. The pressure of circulating water is 3 - 4 Kg/cm2 more than that of actual drum pressure 4 Kg/cm2 more than that of actual drum pressure and temperature is saturation temperature.and temperature is saturation temperature.

CIRCULATION PUMPCIRCULATION PUMP

CIRCULATION PUMPCIRCULATION PUMP

CIRCULATION PUMP - MECANICAL SEALCIRCULATION PUMP - MECANICAL SEAL

SLIME SLIME SEPARATOSEPARATO

RR

Slime separator is a filter with a Slime separator is a filter with a cylindrical mesh made of stainless steel. cylindrical mesh made of stainless steel. Water from the circulation pumps is Water from the circulation pumps is supplied to the inner part of the mesh, supplied to the inner part of the mesh, and goes out through the mesh walls. and goes out through the mesh walls. Sludge falls down and is removed through Sludge falls down and is removed through a periodical purging point. For cleaning a periodical purging point. For cleaning and replacing the net the lower bottom of and replacing the net the lower bottom of the slime collector body is manufactured the slime collector body is manufactured as removal flange.as removal flange.

EVAPORATOREVAPORATOR

Evaporating surface for boiler Evaporating surface for boiler heating consists of two basic parts:heating consists of two basic parts:

a.a. Upper radiation part, arranged in Upper radiation part, arranged in the revolving gas flue of boiler before the revolving gas flue of boiler before steam superheater, andsteam superheater, and

b.b. Main part consisting of Main part consisting of evaporator bundles, situated below evaporator bundles, situated below the steam superheater.the steam superheater.

The upper part of evaporating surface The upper part of evaporating surface consists consists of the outlets of the tubes of the outlets of the tubes which rise from the main which rise from the main evaporating surface. The outlet evaporating surface. The outlet parts of the tube parts of the tube are welded to the are welded to the collecting mains which are situated inside collecting mains which are situated inside the brickwork of the boiler walls at the the brickwork of the boiler walls at the boiler revolving gas flue area. First four boiler revolving gas flue area. First four pipes, for the sake of protection against pipes, for the sake of protection against wear out are made of pipe 28 x 5. The wear out are made of pipe 28 x 5. The size of others is 28 x 3. Material of pipe size of others is 28 x 3. Material of pipe is steel – 20. The upper evaporating part is steel – 20. The upper evaporating part is the elongation of the upper bundle at is the elongation of the upper bundle at evaporating surface.evaporating surface.

Blocks are composed of 200 coils Blocks are composed of 200 coils connected in parallel which are fixed on connected in parallel which are fixed on the frame of the unit.the frame of the unit.

In input chamber of boiler In input chamber of boiler evaporating surface is fixed at lower evaporating surface is fixed at lower block frame. Block coils are made of block frame. Block coils are made of 28 x 3 dia located in staggered manner 28 x 3 dia located in staggered manner and from the staggered bundle S1 = 70 and from the staggered bundle S1 = 70 mm and S2 = 50 mm. The total area of mm and S2 = 50 mm. The total area of evaporating part is 1250 m2.evaporating part is 1250 m2.

STEAM SUPERHEATERSTEAM SUPERHEATER

SteamSteam superheater is arranged in gas superheater is arranged in gas flue, where the hot gas entered into the flue, where the hot gas entered into the boiler.boiler. It consists of two parts assembled in It consists of two parts assembled in blocks inter connected by 3 pipes.blocks inter connected by 3 pipes. The first The first down stream superheater part consists of down stream superheater part consists of the saturated steam chamber, intermediate the saturated steam chamber, intermediate chamber and of 48 coils, connected in chamber and of 48 coils, connected in parallel – 32 x 3 dia, steel-20.parallel – 32 x 3 dia, steel-20. The second The second down stream superheater part consists of down stream superheater part consists of intermediate chamber, steam super heated intermediate chamber, steam super heated chamber and of 48 coils connected in chamber and of 48 coils connected in parallel – 32 x 3 dia, steel – 12 parallel – 32 x 3 dia, steel – 12

The temperature of super heated steam The temperature of super heated steam is 430-440 O C.is 430-440 O C. Heating surface of steam Heating surface of steam superheater makes 135 msuperheater makes 135 m2. 2. The The temperature of superheater steam is temperature of superheater steam is controlled by the changing of controlled by the changing of temperature of gases entering the boiler.temperature of gases entering the boiler. The quantity of cooled gases taken The quantity of cooled gases taken behind from the boiler which are behind from the boiler which are necessary for controlling is supplied to necessary for controlling is supplied to the gas flue before steam superheater by the gas flue before steam superheater by means of the control valve and smoke means of the control valve and smoke suction device.suction device. Temperature control Temperature control limits are 10 – 12°Climits are 10 – 12°C. .

PHOSPHATE DOZING PHOSPHATE DOZING SYSTEMSYSTEM

PHOSPHATE DOZING PHOSPHATE DOZING SYSTEMSYSTEM

For this the equipment required is phosphate For this the equipment required is phosphate mixer, solution filter, strong tank, phosphate mixer, solution filter, strong tank, phosphate dozing pump and wash water tank. Phosphate dozing pump and wash water tank. Phosphate dozing is done to maintain pH of water. In this dozing is done to maintain pH of water. In this system phosphate and hydrazine in specified system phosphate and hydrazine in specified quantities are added to the water in the mixer quantities are added to the water in the mixer and thoroughly mixed, so that the solution was and thoroughly mixed, so that the solution was prepared with equal concentration. Then the prepared with equal concentration. Then the solution was send to a storage tank through solution was send to a storage tank through suction filter. Whenever required this solution suction filter. Whenever required this solution was dozed by a pump called phosphate dozing was dozed by a pump called phosphate dozing pump into the boiler drum. Wash water is pump into the boiler drum. Wash water is flushed into the mixer after mixing the solution flushed into the mixer after mixing the solution and into the dozing pump after dozing to flush and into the dozing pump after dozing to flush out lines. This is to avoid choking. out lines. This is to avoid choking.

BLOW DOWN SYSTEMBLOW DOWN SYSTEM

Blowing down of water from boiler at various Blowing down of water from boiler at various stages is done in three modes.stages is done in three modes.

CONTINUOUS BLOW DOWN: CONTINUOUS BLOW DOWN: Here the water Here the water from drum is blow down continuously to from drum is blow down continuously to remove silica deposit in the drum and reduce remove silica deposit in the drum and reduce conductivity of water. The increased conductivity of water. The increased conductivity means, accumulation of dissolved conductivity means, accumulation of dissolved salts in water. This slag is bad conductor of salts in water. This slag is bad conductor of heat. By this is long run, the tubes will be heat. By this is long run, the tubes will be damaged. In keeping this view we should blow damaged. In keeping this view we should blow down water from drum. It down water from drum. It

CONTINUOUS BLOW DOWNCONTINUOUS BLOW DOWN

PERIODIC BLOW DOWN: PERIODIC BLOW DOWN: As its name As its name indicates, the water is blow down indicates, the water is blow down periodically. Usually 2-3 times in a shift periodically. Usually 2-3 times in a shift for 2-3 minutes. This is to be done to for 2-3 minutes. This is to be done to remove un-dissolved salts in the water in remove un-dissolved salts in the water in the pipelines. The purpose served by this the pipelines. The purpose served by this other than C.B.D. is, here water is blow other than C.B.D. is, here water is blow down from economizer (one point), slime down from economizer (one point), slime separator (one point) and evaporator (4 separator (one point) and evaporator (4 points). All these points are connected to points). All these points are connected to bubbler.bubbler.

EMERGENCY BLOW DOWNEMERGENCY BLOW DOWN The EBD The EBD line is arranged to drum. Whenever line is arranged to drum. Whenever water level in the drum exceeds the safe water level in the drum exceeds the safe limit, the EBD valve limit, the EBD valve

opens automatically and the water flows opens automatically and the water flows down. The other end of EBD also down. The other end of EBD also connected to the bubbler. connected to the bubbler.

EMERGENCY BLOW EMERGENCY BLOW DOWNDOWN

BUBBLERBUBBLER

In bubbler all the water from CBD, PBD In bubbler all the water from CBD, PBD and EBD is collected and cooled by and EBD is collected and cooled by mixing some service water from outside mixing some service water from outside and then sent to the sump, from where it and then sent to the sump, from where it is sent to sludge separation plant by a is sent to sludge separation plant by a centrifugal pump. The use of bubbler is centrifugal pump. The use of bubbler is to reduce the temperature of water; to reduce the temperature of water; otherwise this high temperature causes otherwise this high temperature causes many problems.many problems.

CONTROL SYSTEMS IN CDCP CONTROL SYSTEMS IN CDCP

While operating coke dry cooling plant, the While operating coke dry cooling plant, the following parameters should be controlled following parameters should be controlled in efficient manner. Automisation takes in efficient manner. Automisation takes vital role in recent plants, to reduce vital role in recent plants, to reduce manual alertness in processing. The manual alertness in processing. The accuracy of this automisation can be accuracy of this automisation can be visualized by the added graphical trends visualized by the added graphical trends for the parameters drum level and steam for the parameters drum level and steam temperature.temperature.

GAS TEMPERATURE GAS TEMPERATURE CONTROLCONTROL

Circulating gas temperature has to be Circulating gas temperature has to be controlled due to the following reasons:controlled due to the following reasons:

If the temperature of gas entering the If the temperature of gas entering the chamber is more than the rated temperature, chamber is more than the rated temperature, overheating of the superheater tubes takes overheating of the superheater tubes takes place in turn resulting in the increase of place in turn resulting in the increase of superheated steam temperature.superheated steam temperature.

If the temperature of gas before boiler is If the temperature of gas before boiler is lesser than the rated value then the lesser than the rated value then the production of steam will be reduced.production of steam will be reduced.

The consumption of gas will be varied The consumption of gas will be varied depending on coke cooling rate.depending on coke cooling rate.

The control of circulating gas temperature The control of circulating gas temperature is done by operating guide vane, which is done by operating guide vane, which controls the circulating gas flow through controls the circulating gas flow through the mill fan. In case the chamber running the mill fan. In case the chamber running with reserve fan (in case of failure of mill with reserve fan (in case of failure of mill fan) another guiding apparatus, with fan) another guiding apparatus, with controls the gas flow through reserve fan controls the gas flow through reserve fan will be operated. By opening the guide will be operated. By opening the guide vanes the gas flow will increase, which vanes the gas flow will increase, which causes the reduction in gas temperature causes the reduction in gas temperature and by closing the guide vanes the gas and by closing the guide vanes the gas flow decreases causes increase in gas flow decreases causes increase in gas temperature.temperature.

DRUM LEVEL CONTROLDRUM LEVEL CONTROL

Water level high in drum causes the water Water level high in drum causes the water entering into superheater and low level of entering into superheater and low level of water may leads to starvation problem. water may leads to starvation problem. Drum level control is done by 3 element Drum level control is done by 3 element control. These elements senses the actual control. These elements senses the actual drum level of boiler, actual rate of steam drum level of boiler, actual rate of steam production, rate of feed water supply. The production, rate of feed water supply. The drum level is then controlled by measuring drum level is then controlled by measuring difference in steam production and feed difference in steam production and feed water supply and actual drum level.water supply and actual drum level.

STEAM TEMPERATURE STEAM TEMPERATURE CONTROLCONTROL

Steam temperature is to be maintained in the Steam temperature is to be maintained in the rated limits. The control of steam temperature rated limits. The control of steam temperature can be done by two methods:can be done by two methods:

By operating guiding apparatus :- By operating By operating guiding apparatus :- By operating guiding apparatus, the gas temperature can be guiding apparatus, the gas temperature can be controlled and by that steam temperature will controlled and by that steam temperature will be controlled.be controlled.

Bypassing the chamber :- Circulating gas will Bypassing the chamber :- Circulating gas will be directly supplied to a point after dust be directly supplied to a point after dust catching bunker by bypassing the chamber. catching bunker by bypassing the chamber. This causes the reduction in temperature of This causes the reduction in temperature of circulating gas entering into the boiler and circulating gas entering into the boiler and hence reduction in steam temperature.hence reduction in steam temperature.

ROOF SPACE PRESSURE ROOF SPACE PRESSURE CONTROLCONTROL

While passing circulating gas at the time While passing circulating gas at the time of charging of coke the pressure in roof of charging of coke the pressure in roof space may increase. This pressure will space may increase. This pressure will be controlled by opening the bleeder be controlled by opening the bleeder which is arranged after mill fan. By this, which is arranged after mill fan. By this, some gas will be let into atmosphere. By some gas will be let into atmosphere. By closing the valve gas flowing out will be closing the valve gas flowing out will be reduced. This is to maintain roof space reduced. This is to maintain roof space pressure in safe limit.pressure in safe limit.

PROTECTIONS & INTERLOCKS PROTECTIONS & INTERLOCKS

Every waste heat boiler has protection Every waste heat boiler has protection and signaling systems. Protection devices and signaling systems. Protection devices are installed to increase safety of the are installed to increase safety of the equipment. Also the boiler may be equipment. Also the boiler may be operated with lesser personnel. If any operated with lesser personnel. If any emergency arises, the personnel are emergency arises, the personnel are given signals in the form of alarms and given signals in the form of alarms and the boiler is stopped if the problem is not the boiler is stopped if the problem is not rectified within the safe limits of working.rectified within the safe limits of working.

BOILER OVER FEEDING BOILER OVER FEEDING PROTECTIONPROTECTION

If this protection is not there the over feeding of If this protection is not there the over feeding of water causes the water entering into superheater water causes the water entering into superheater and in turn water enters the steam line and and in turn water enters the steam line and thereby into turbine which causes damage to the thereby into turbine which causes damage to the turbine blades. On receiving an impulse from turbine blades. On receiving an impulse from water level sensor of level rising in the boiler water level sensor of level rising in the boiler drum by 100 mm higher than the normal level of drum by 100 mm higher than the normal level of 0-0, the emergency discharge valve opens and 0-0, the emergency discharge valve opens and passes the signal to control room and this signal passes the signal to control room and this signal closes the feed unit control valve. When level closes the feed unit control valve. When level falls down to +50 mm (upper permissible level) falls down to +50 mm (upper permissible level) emergency discharge valve is automatically emergency discharge valve is automatically closed. If the water level rises up to +150 mm, closed. If the water level rises up to +150 mm, second protection is activated; and the boiler is second protection is activated; and the boiler is stopped through stoppage of main mill fan. stopped through stoppage of main mill fan.

WATER LEVEL LOWER WATER LEVEL LOWER PROTECTIONPROTECTION

On receiving the pulse of the level On receiving the pulse of the level lowering in the drum by 150 mm lower lowering in the drum by 150 mm lower than the normal level the main exhauster than the normal level the main exhauster will trip. If this protection is not there, will trip. If this protection is not there, and if steam generation is more than and if steam generation is more than feed water flow, the boiler starts feed water flow, the boiler starts emptying. After continuous running like emptying. After continuous running like this, the tubes become dry and due to hot this, the tubes become dry and due to hot gas flow, the tubes get starved and this gas flow, the tubes get starved and this leads to major breakdown of boiler.leads to major breakdown of boiler.

LOW CIRCULATING WATER LOW CIRCULATING WATER PROTECTIONPROTECTION

Low circulating water flow protection Low circulating water flow protection protects the tubes of evaporating surface protects the tubes of evaporating surface from burning out as a result of stoppage from burning out as a result of stoppage or lowering of water supply. Impulse or lowering of water supply. Impulse comes from all instruments measuring comes from all instruments measuring water flow. Protection has two levels. If water flow. Protection has two levels. If flow falls to 100 m3/hr, first protection flow falls to 100 m3/hr, first protection switches on standby pump. If flow falls switches on standby pump. If flow falls further (65 m3/hr) second protection further (65 m3/hr) second protection switches off the main mill fan.switches off the main mill fan.

MAIN EXHAUSTER INTER MAIN EXHAUSTER INTER LOCKSLOCKS

The interlocks are of two types as given below:The interlocks are of two types as given below: Starting interlocksStarting interlocks Tripping interlocksTripping interlocks FOR STARTING MAIN EXHAUSTER THE FOR STARTING MAIN EXHAUSTER THE

FOLLOWING CONDITIONS ARE NECESSARY:FOLLOWING CONDITIONS ARE NECESSARY: Boiler drum level should be within limitsBoiler drum level should be within limits Circulation water pump should runCirculation water pump should run Circulation water flow should be more than 100 T/Hr.Circulation water flow should be more than 100 T/Hr. The guiding apparatus should be in closed conditionThe guiding apparatus should be in closed condition Feed water pressure should not be less than 48 Feed water pressure should not be less than 48

Kg/cm2.Kg/cm2. The main exhauster will trip in the following The main exhauster will trip in the following

casescases The drum level falls below 150 mmThe drum level falls below 150 mm If circulation water pump stopped and the standby If circulation water pump stopped and the standby

pump have not picked uppump have not picked up If circulation water flow falls below 65 T/Hr.If circulation water flow falls below 65 T/Hr. If boiler feed water pressure falls below 48 Kg/cm2.If boiler feed water pressure falls below 48 Kg/cm2.

DISCHARGING DEVICE INTERLOCKSDISCHARGING DEVICE INTERLOCKS

• The discharging of cooled coke through discharging The discharging of cooled coke through discharging device will be stopped automatically in following cases:device will be stopped automatically in following cases:

• If main exhauster tripped.If main exhauster tripped.• If ventilation fan is not running.If ventilation fan is not running.• If coke conveyor is stopped.If coke conveyor is stopped.• If discharged coke temperature raises above 200O CIf discharged coke temperature raises above 200O C• If air gates for ventilation fan are closedIf air gates for ventilation fan are closed• If coke level in the cooling chamber falls below If coke level in the cooling chamber falls below

minimum level known as lower level.minimum level known as lower level.• If the conveyor to conveyor changeover is not opened If the conveyor to conveyor changeover is not opened

on the running conveyor.on the running conveyor.

OTHER INTERLOCKSOTHER INTERLOCKS If main exhauster trips, the reserve If main exhauster trips, the reserve

exhauster will start automatically.exhauster will start automatically. The auto circulation pump starts The auto circulation pump starts

automatically when the circulation water automatically when the circulation water flow falls below 100 T/Hr. or when the flow falls below 100 T/Hr. or when the running circulation pump fails.running circulation pump fails.

The coke bucket will not get lifted, if coke The coke bucket will not get lifted, if coke in the cooling chamber reaches upper level.in the cooling chamber reaches upper level.

The main exhauster will trip, if running The main exhauster will trip, if running circulation pump tripped and standby circulation pump tripped and standby circulation water pump does not picked up.circulation water pump does not picked up.

HEAT BALANCE OF CDCPHEAT BALANCE OF CDCP

No. of Coke oven Batteries No. of Coke oven Batteries = 3= 3 No. of ovens per battery No. of ovens per battery = 67= 67 Capacity of each oven Capacity of each oven = 25 T= 25 T Temperature of charged coke Temperature of charged coke = 1100 °C= 1100 °C Temperature of cooled coke Temperature of cooled coke =200 °C=200 °C Specific rate of steam production Specific rate of steam production = 0.45 = 0.45

– 0.52 T/ton of coke– 0.52 T/ton of coke Pressure of steam Pressure of steam = 40 = 40

kg/cm2kg/cm2 Temperature of steam Temperature of steam = 440 °C= 440 °C

CalculationsCalculations Coke pushed per ovenCoke pushed per oven = 25 T= 25 T Steam producedSteam produced = 0.45 * 25 = 0.45 * 25 = 11.25 T= 11.25 T Heat Inputs:Heat Inputs: Heat content of hot coke:Heat content of hot coke: Coke chargedCoke charged = 25 T = 25 T = =

25,000 kg25,000 kg Specific heat of coke Specific heat of coke = 0.383 kcal / kg °C= 0.383 kcal / kg °C Temperature of hot coke = 1100 °CTemperature of hot coke = 1100 °C Heat content = m*c*t Heat content = m*c*t = 25000 * 0.383 * = 25000 * 0.383 *

11001100 = = 10532.5 × 103 kcal10532.5 × 103 kcal

While transferring hot coke from oven to While transferring hot coke from oven to chamber, hot coke reacts with air. This value chamber, hot coke reacts with air. This value is taken as 4% of the total heat content.is taken as 4% of the total heat content.

Heat of reaction Heat of reaction = 0.4 * 10532.5 × 103= 0.4 * 10532.5 × 103 = = 421.3 × 103 kcal421.3 × 103 kcal Sensible heat of de-aerated water:Sensible heat of de-aerated water: Specific heat of waterSpecific heat of water = 1.03 kcal / kg °C= 1.03 kcal / kg °C Temperature of waterTemperature of water = 105 °C= 105 °C Mass of waterMass of water = 11.25 T= 11.25 T = 11250 = 11250

kgkg Sensible heatSensible heat = 11250 * 1.03 * 105= 11250 * 1.03 * 105 = = 1216.7 × 103 kcal1216.7 × 103 kcal Total heat inputTotal heat input = H1 + H2 + H3= H1 + H2 + H3 = = 12170.5 × 103 kcal12170.5 × 103 kcal

Heat outputs:Heat outputs: Heat of steam producedHeat of steam produced Pressure of steamPressure of steam = 40 kg/cm2 = 40 kg/cm2 Temperature of steamTemperature of steam = 440 °C= 440 °C Mass of steam Mass of steam = 11.25 T= 11.25 T = 11250 kg= 11250 kg From steam tables, at 40 kg/cm2 & 440 °CFrom steam tables, at 40 kg/cm2 & 440 °C Hsup = 784.15 kcal / kg Hsup = 784.15 kcal / kg Heat of steam produced = Hsup * mHeat of steam produced = Hsup * m = =

11250 * 784.1511250 * 784.15 = = 8821.7 × 8821.7 ×

103 kcal103 kcal Sensible heat of cooled coke discharged:Sensible heat of cooled coke discharged: Temperature of cooled coke dischargedTemperature of cooled coke discharged = 200 °C= 200 °C Amount of coke dischargedAmount of coke discharged = 25 T =25000 kg= 25 T =25000 kg Sensible heatSensible heat = 200 * 25000 * 0.383= 200 * 25000 * 0.383 = = 1915 × 103 kcal1915 × 103 kcal

Heat loss due to continuous blow down of water:Heat loss due to continuous blow down of water: As per Russian standards 5% of feed water As per Russian standards 5% of feed water

supplied is blown down as CBD.supplied is blown down as CBD. From steam tables,From steam tables, Hf = 258.4 kcal / kgHf = 258.4 kcal / kg Heat loss due to CBDHeat loss due to CBD = 0.05 * 11250 * = 0.05 * 11250 *

258.4258.4 = = 145.35 × 103 kcal145.35 × 103 kcal Heat loss from bleeder:Heat loss from bleeder: As per Russian standards, heat loss due to As per Russian standards, heat loss due to

bleeding of steam is 2% of total heat,bleeding of steam is 2% of total heat, Heat loss due to bleedingHeat loss due to bleeding = 0.02 * 12170.5 = 0.02 * 12170.5

× 103× 103 = = 243.41 × 103 kcal243.41 × 103 kcal

Heat loss due to coke charging hole:Heat loss due to coke charging hole: As per Russian standards, heat loss while As per Russian standards, heat loss while

charging coke into chamber is taken as 1% charging coke into chamber is taken as 1% of the total heat.of the total heat.

Heat lost during chargingHeat lost during charging = 0.01 * = 0.01 * 12170.5 × 103 12170.5 × 103

= = 121.7 × 103 121.7 × 103 kcalkcal

Heat loss due to radiation, periodical blow Heat loss due to radiation, periodical blow down and other losses,down and other losses,

Other lossesOther losses = [12170.5 – (8821.7 + 1915 = [12170.5 – (8821.7 + 1915 + 145.35 + 243.41 + 121.71)] × 103 + 145.35 + 243.41 + 121.71)] × 103

= 923.33 × 103 kcal= 923.33 × 103 kcal

HEAT BALANCE SHEET OF CDCPHEAT BALANCE SHEET OF CDCP

Heat energy I/PHeat energy I/P kcalkcal Heat energy O/PHeat energy O/P kcalkcal

Sensible heat of hot cokeSensible heat of hot coke 10532.510532.5 Enthalpy of steam producedEnthalpy of steam produced 8821.78821.7

Heat of reactionHeat of reaction 421.3421.3 Sensible heat of coke dischargedSensible heat of coke discharged 19151915

Sensible heat of feed waterSensible heat of feed water 1216.71216.7 Heat loss due to CBDHeat loss due to CBD 145.35145.35

Heat loss due to bleedingHeat loss due to bleeding 243.41243.41

Heat lost while charging cokeHeat lost while charging coke 121.71121.71

Other lossesOther losses 923.33923.33

____________12170.512170.5

____________12170.512170.5

Thermal Efficiency of CDCP = Thermal Efficiency of CDCP = Heat Heat content of steam producedcontent of steam produced

Heat input to plantHeat input to plant == 8821.7 ×8821.7 × 100 100 12170.512170.5 == 72.48 %72.48 %

VARIOUS SECTIONS OF VARIOUS SECTIONS OF CO&CCPCO&CCP

COKE OVEN SECTIONSCOKE OVEN SECTIONS

COAL PREPARATION COAL PREPARATION COKE OVEN BATTERYCOKE OVEN BATTERY COKE DRY COOLING OF HOT COKECOKE DRY COOLING OF HOT COKE COKE SORTING COKE SORTING

LAYOUT OF CO&CCPLAYOUT OF CO&CCP

CO&CCPCO&CCPPROCESS FLOW CHARTPROCESS FLOW CHART

COKE GAS

LIGHT OIL WASH OIL HP NAPHTHALENE ANTHRACENE OIL PHENOL PITCH CT FUEL

BENZENE TOLUENE H.B.F SOL 110 SOLVENT NAPTHA STILL BOTTOMS

COKING COAL FROM RMHP

COKE OVENBATTERIES

RUN OF OVEN COKE (HOT)

COKE DRY COOLING PLANT

STEAM

BPTS

COOLED COKE

COKE SORTING PLANT

BREEZE COKE0-10 MM

NUT COKE10-25 MM

BF COKE25-80MM

COKE DUST0-3 MM

BURDEN HANDLINGSECTION(B.F)

TO S.P

SINTERPLANT

COKE SLUDGE0-3 MM

TO SALE

COAL PREPARATION PLANT

TO YARD

TO YARD

SEPARATOR

FLUSHING LIQUOR

RAW COKE OVEN GAS

PRIMARY GAS COOLERTO GCM

TO DECANTER EXHAUSTER

AMMONIUMSULPHATE

FINAL GAS COOLER

CLEAN COKE OVEN GAS

CONSUMER

BATTERY UNDER FIRING

CRUDE BENZOL

BENZOL RECTIFICATION PLANT

TAR DISTILLATION PLANT

COKE BUCKET COKE BUCKET ALIGNMENT/LOWERINGALIGNMENT/LOWERING

Keep the selection in ground controlKeep the selection in ground control

Centre the bucket properlyCentre the bucket properly

Close the hooksClose the hooks

Ensure proper closing of hooks on both the Ensure proper closing of hooks on both the sidessides

Change the selection to the lifter control Change the selection to the lifter control and then give signal to the lifter operator and then give signal to the lifter operator to lift the bucket by pressing bell push to lift the bucket by pressing bell push buttonbutton

COKE BUCKET COKE BUCKET ALIGNMENT/LOWERINGALIGNMENT/LOWERING

Lower the bucket from RP-6 level Lower the bucket from RP-6 level after ensuring proper alignment of after ensuring proper alignment of empty carriage with the stationary empty carriage with the stationary guide until hooks are fully open.guide until hooks are fully open.

Keep the selection switch in off Keep the selection switch in off position.position.

SOP LIFTERSOP LIFTER Switch on the power to the respective lifter Switch on the power to the respective lifter Keep the selection in ground controlKeep the selection in ground control Wait for alignment operator signal (BUZZAR)Wait for alignment operator signal (BUZZAR) After receiving signal from Alignment operator, After receiving signal from Alignment operator,

change the selection to lifter mode and then charge change the selection to lifter mode and then charge the circuit and lift the bucket in FOURTH notchthe circuit and lift the bucket in FOURTH notch

Observe for any abnormal sounds and inform to Observe for any abnormal sounds and inform to S/ICS/IC

Ensure full lifting of bucket and then travel towards Ensure full lifting of bucket and then travel towards chamber axis ,lower the bucket in FIRST notch after chamber axis ,lower the bucket in FIRST notch after ensuring hatch open and exact axis.ensuring hatch open and exact axis.

SOP OF LIFTER (contd.)SOP OF LIFTER (contd.) Ensure total discharge of coke from bucket Ensure total discharge of coke from bucket Check for any over lowering or hooks open Check for any over lowering or hooks open

and if any inform to S/I or C/M to take and if any inform to S/I or C/M to take necessary action and lift the empty bucket in necessary action and lift the empty bucket in 22ndnd notch notch

Back travel the bucket after ensuring full Back travel the bucket after ensuring full lifting of the bucketlifting of the bucket

Ensure hatch close and exact axis at well and Ensure hatch close and exact axis at well and and check for arrows matching and then and check for arrows matching and then lower the bucket in third notchlower the bucket in third notch

Ensure bucket stoppage at RP-6 levelEnsure bucket stoppage at RP-6 level

After hooks are opened full , Switch off the After hooks are opened full , Switch off the power of the lifterpower of the lifter

Empty screen liftingEmpty screen lifting Ensure no loco movement below lifter Ensure no loco movement below lifter

while lifting /lowering empty screen. while lifting /lowering empty screen. During empty screen lifting screen load(5 During empty screen lifting screen load(5

tons) is coming on screen chains. So, while tons) is coming on screen chains. So, while lifting the screen inching operation is lifting the screen inching operation is advised to be done till chains are advised to be done till chains are tightened to avoid sudden load on chainstightened to avoid sudden load on chains

Ensure chain healthiness and further lifting Ensure chain healthiness and further lifting is performed in first notch and stop lifting is performed in first notch and stop lifting around one meter below the actual liftingaround one meter below the actual lifting

Further lifting is to be done by Further lifting is to be done by inching to avoid hitting of the rope inching to avoid hitting of the rope clamps.clamps.

After lowering of the empty screen After lowering of the empty screen rope slackness is to be ensured by rope slackness is to be ensured by the lifter operator.the lifter operator.

During opening of the hooks During opening of the hooks alignment operator should ensure alignment operator should ensure full opening of hooks and avoid loco full opening of hooks and avoid loco movement to avoid loco hitting with movement to avoid loco hitting with the hooksthe hooks

EMPTYING OF CDCP COOLING CHAMBER EMPTYING OF CDCP COOLING CHAMBER

1.1. Stop charging hot coke into cooling Stop charging hot coke into cooling chamber and inform to boiler people.chamber and inform to boiler people.

2. Open nitrogen ~300nm3 /hr2. Open nitrogen ~300nm3 /hr

3. Continue discharging of coke up to lower 3. Continue discharging of coke up to lower level.level.

4. Bypass lower level and temperature inter-4. Bypass lower level and temperature inter-locks.locks.

5. Keep guiding apparatus in manual mode at 5. Keep guiding apparatus in manual mode at 50% opened.50% opened.

6. Keep bleeder after mill fan in closed 6. Keep bleeder after mill fan in closed condition.condition.

EMPTYING OF CDCP EMPTYING OF CDCP COOLING CHAMBER COOLING CHAMBER

7. Keep observer at DD area for any hot pieces.8. Open water at conveyor gallery on running conveyor.9. Completely empty the coke and ensure the same through triangular manhole.10.Stop mill fan and close nitrogen and blank.11.Keep lid open for further natural cooling.12.Normalize all inter locks.

WORKING AT CHARGING DEVICEWORKING AT CHARGING DEVICE Take shut down to lifter if required.Take shut down to lifter if required. Stop charging and bring down coke Stop charging and bring down coke

to lower level.to lower level. Bring down before boiler Bring down before boiler

temperature to~500degree C.temperature to~500degree C. Maintain suction at roof space --Maintain suction at roof space --

5mmwc minimum.5mmwc minimum. Open bleeder after mill fan full.Open bleeder after mill fan full. Run mill fan/reserve fan to maintain Run mill fan/reserve fan to maintain

suction as per requirement.suction as per requirement. Open guiding apparatus full if Open guiding apparatus full if

reserve fan is running.reserve fan is running. Open guiding apparatus as per Open guiding apparatus as per

requirement if mill fan is runningrequirement if mill fan is running..

WORKING AT DISCHARGING WORKING AT DISCHARGING DEVICE AREADEVICE AREA

While working at discharging device area for opening While working at discharging device area for opening of manholes for inspection do as follows:of manholes for inspection do as follows:

Stop charging and bring down coke level to lower Stop charging and bring down coke level to lower level o nly for level o nly for long durationlong duration..

For urgentFor urgent inspection stop charging and discharging inspection stop charging and discharging temporarily.temporarily.

•Close guiding apparatus and open bleeder after mill fan in manual mode.

•Open required manhole inspect and do the needful and close manhole

•For going inside discharging device check for carbon monoxide presence.

•For doing cutting or welding works inside discharging device area bring down temperature before boiler to~500degreeC.

•Empty coke from gate3&4 and close gates above the working area and take shutdown to discharging device•.Check for carbon monoxide presence by EMD or with our meter. •Take electrical shut down whenever required.

CHARGING HOT COKE INTO COLD CHARGING HOT COKE INTO COLD CHAMBERCHAMBER

ENSURE ALL MANHOLES ARE IN CLOSED CONDITION.ENSURE ALL MANHOLES ARE IN CLOSED CONDITION.

ENSURE BEFORE BOILER TEMPERATURE IS AT 90-100DEGREE C.ENSURE BEFORE BOILER TEMPERATURE IS AT 90-100DEGREE C.

ENSURE COKE LEVEL MINIMUM SIX BUCKETS IN CHAMBER.ENSURE COKE LEVEL MINIMUM SIX BUCKETS IN CHAMBER.

ENSURE ALL ENSURE ALL INTERLOCKSINTERLOCKS OF LIFTER AND DISCHARGING DEVICE. OF LIFTER AND DISCHARGING DEVICE.

ENSURE SMOOTH OPERATION OF LIFTER, CHARGING DEVICE, MILL ENSURE SMOOTH OPERATION OF LIFTER, CHARGING DEVICE, MILL FAN, RESERVE FAN, BLEEDERS AND DISCHARGING DEVICE.FAN, RESERVE FAN, BLEEDERS AND DISCHARGING DEVICE.

TAKE CLEARENCE FROM BOILER PERSONNEL BEFORE CHARGING TAKE CLEARENCE FROM BOILER PERSONNEL BEFORE CHARGING HOT COKE.HOT COKE.

KEEP GUIDING APPARATUS AND BLEEDER AFTER MILL FAN IN KEEP GUIDING APPARATUS AND BLEEDER AFTER MILL FAN IN CLOSED CONDITION.CLOSED CONDITION.

CHARGE ONE BUCKET OF HOT COKE IN COOLING CHAMBER AND CHARGE ONE BUCKET OF HOT COKE IN COOLING CHAMBER AND KEEP LID OPEN FOR 5-6 MINUTESKEEP LID OPEN FOR 5-6 MINUTES..

OPEN GUIDING APPARATUS AND MAINTAIN OPEN GUIDING APPARATUS AND MAINTAIN PRESSURE AFTER MILL FAN AT 60-70MMWC.PRESSURE AFTER MILL FAN AT 60-70MMWC.

START DISCHARGING COKE AFTER ONE HOUR AS START DISCHARGING COKE AFTER ONE HOUR AS FOLLOWS:FOLLOWS:

SNO HRSSNO HRS ROTARY TONNAGE ROTARY TONNAGE PRESSURE PRESSURE 1 1ST1 1ST 3TONS/HR 3TONS/HR 60-70MMWC 60-70MMWC 22 2ND2ND 5 TONS/HR 5 TONS/HR 80MMWC 80MMWC 33 3RD3RD 7TONS/HR 7TONS/HR 100MMWC 100MMWC 44 4--6TH4--6TH 8-12TONS/HR 8-12TONS/HR 110MMWC 110MMWC 55 7-107-10THTH 3TONS/HR TO RAISE3TONS/HR TO RAISE120MMWC120MMWC 66 11-1311-13THTH 25 TONS/HR 25 TONS/HR 150MMWC 150MMWC 77 14TH14TH 30 TONS/HR30 TONS/HR 175MMWC 175MMWC 88 15TH15TH 35TONS/HR.35TONS/HR. AUTO MODE AUTO MODE

AT THIS STAGE BOILER MAY BE AT THIS STAGE BOILER MAY BE

CONNECTED TO HEADER AND PUT IN TO NORMAL CONNECTED TO HEADER AND PUT IN TO NORMAL OPERATION. IN ROTARY DD INCREASING IS TO BE OPERATION. IN ROTARY DD INCREASING IS TO BE DONE GRADUALLY EVERY 15MTS ONCE AND NOT DONE GRADUALLY EVERY 15MTS ONCE AND NOT ONCE IN ONE HOUR.ONCE IN ONE HOUR.

WEDING OR CUTTING AT WEDING OR CUTTING AT CIRCULATING GAS TRACKCIRCULATING GAS TRACK

Stop charging and, discharge coke up to lower levelStop charging and, discharge coke up to lower level

Bring down temperature before boiler upto 400-Bring down temperature before boiler upto 400-425degreeC.425degreeC.

Start reserve fan and stop mill fan.Start reserve fan and stop mill fan.

Close guiding apparatus of reserve fan after some Close guiding apparatus of reserve fan after some time Open bleeder after mill fan fully in manual time Open bleeder after mill fan fully in manual mode.mode.

Open nitrogen at dust catching bunker ~300-Open nitrogen at dust catching bunker ~300-400cu.meter/hr.400cu.meter/hr.

Keep minimum gap of charging to welding work ~2-3 hrs. If reserve fan is running before give more gap of 3-4 hrs.

Close nitrogen after work is completed. Normalize system after work is completed

Ensure reserve fan guiding apparatus and bleeder after mill fan are normalized

Then only give protocol for start of work for safe work.

MAINTENANCE AT MILL MAINTENANCE AT MILL FANS/RESERVE FANSFANS/RESERVE FANS

1.. FOR ONLY MAN HOLES OPENING1.. FOR ONLY MAN HOLES OPENING a) Stop charging and bring down coke to lower level a) Stop charging and bring down coke to lower level b) Stop mill fan after bringing the temperature before b) Stop mill fan after bringing the temperature before

boiler to ~500degreeC.boiler to ~500degreeC. c) Keep open bleeder after mill fan 100%.c) Keep open bleeder after mill fan 100%. d) See that opening of manhole and previous charging gap d) See that opening of manhole and previous charging gap

at least 2hrs.at least 2hrs. e) Close guiding apparatus of reserve fan to avoid gas e) Close guiding apparatus of reserve fan to avoid gas

leakage.leakage. f) For opening manhole at mill fan f) For opening manhole at mill fan suction side onlysuction side only

open guiding apparatus of mill fanopen guiding apparatus of mill fan) Open the ) Open the manhole, check for any gas leak.manhole, check for any gas leak.

h)Change the gasket etc. or inspect inside if any.h)Change the gasket etc. or inspect inside if any. i) Close manhole properly and normalize system.i) Close manhole properly and normalize system. j) j) If reserve fan man hole is to be opened stop reserve fan If reserve fan man hole is to be opened stop reserve fan

alsoalso

2. FOR DOING CUTTING OR WELDING WORKS (On 2. FOR DOING CUTTING OR WELDING WORKS (On the body etc.)the body etc.)

a) Stop charging and bring down coke level to lower level.a) Stop charging and bring down coke level to lower level. b) Stop mill fan after bringing the temperature before b) Stop mill fan after bringing the temperature before

boiler to ~400degreeC.boiler to ~400degreeC. c) Open nitrogen at DCB by 300-400 cub. meters/hr half c) Open nitrogen at DCB by 300-400 cub. meters/hr half

an hour before Work and close after work is completed.an hour before Work and close after work is completed.

d) Keep open bleeder after mill fan 100%.

e) Before stopping mill fan take sample for explosive mixture by EMD people.

f) Close guiding apparatus of reserve fan while doing welding works.

g) Normalize the system after work is completed.

FLAMES IN DISCHARGING DEVICEFLAMES IN DISCHARGING DEVICEReasons:Reasons:1.1.Insufficient air supply and green coke Insufficient air supply and green coke

charging leading to high CO&Hydrogencharging leading to high CO&HydrogenAction to be taken:Action to be taken: 1.1. Stop discharging Stop discharging 2.2. Close the guiding apparatusClose the guiding apparatus3.3. Restore air supply, if required open extra Restore air supply, if required open extra

lidlid4.4. Wait for some time and normalize the Wait for some time and normalize the

chamber slowlychamber slowly

IN CASE OF DUST AND IN CASE OF DUST AND

GAS EMISSIONS AT GAS EMISSIONS AT DDDD

Check the rotary bleeder for its Check the rotary bleeder for its openingopening

Check the running of the ventilation Check the running of the ventilation fan and opening of its guiding fan and opening of its guiding apparatusapparatus

Check the opening of the air-gatesCheck the opening of the air-gates Check the ventilation line for any Check the ventilation line for any

holesholes

Flames at charging deviceFlames at charging device Reasons:Reasons: 1. Improper seating of lid1. Improper seating of lid 2. Malfunction of MF bleeder2. Malfunction of MF bleeder 3. Potential boiler leakage3. Potential boiler leakage 4. Safety flap burst4. Safety flap burst

Action to be takenAction to be taken

1.1. Break the prechamber bleeder water seal if requiredBreak the prechamber bleeder water seal if required

2.2. Rectify the abnormality found Rectify the abnormality found

BLEEDERSBLEEDERS 1. After MF bleeder- For maintaining the 1. After MF bleeder- For maintaining the

hydraulic regime. For healthy chamber hydraulic regime. For healthy chamber bleeder opening should not be more than bleeder opening should not be more than 30%30%

2. Pre-chamber Bleeder- It acts as a safety 2. Pre-chamber Bleeder- It acts as a safety valve when high pressures are devoleped valve when high pressures are devoleped at roof space.at roof space.

3. Rotary Bleeder- To maintain suction at 3. Rotary Bleeder- To maintain suction at the discharging devicethe discharging device

Purging Bleeder- To ventilate circulating Purging Bleeder- To ventilate circulating gas during emergency situations like total gas during emergency situations like total power failure and heavy boiler leakagepower failure and heavy boiler leakage

DPT SYSTEMDPT SYSTEM Dust is carried by circulating gas during Dust is carried by circulating gas during

cooling process must be separated in order cooling process must be separated in order to prevent chamber equipments i.e. to prevent chamber equipments i.e. impeller vanes,ducts,boiler tubes etc. from impeller vanes,ducts,boiler tubes etc. from erosion.erosion.

DPT is used to transport the dust collected DPT is used to transport the dust collected from DCBfrom DCB

And cyclones to red bunker at DPT stationAnd cyclones to red bunker at DPT station SOPSOP Find the bunkers which are full with dust by Find the bunkers which are full with dust by

hammering runner pipes or moving sensors.hammering runner pipes or moving sensors. Empty the 3-T bunkers first then 2-T bunkers Empty the 3-T bunkers first then 2-T bunkers

after having necessary instructions from after having necessary instructions from shift I/Cor shift C/Mshift I/Cor shift C/M

CONCLUSIONCONCLUSION The various modifications suggested in coke The various modifications suggested in coke

dry cooling plant for increasing the boiler life dry cooling plant for increasing the boiler life are as follows:are as follows:

1.1. PROVISION OF S.S. SHIELDS AT THE PROVISION OF S.S. SHIELDS AT THE ENTRANCE OF ECONOMISER, EVAPORATOR ENTRANCE OF ECONOMISER, EVAPORATOR AND SUPER HEATER IN GAS FLOW PATHAND SUPER HEATER IN GAS FLOW PATH

2.2. Stop modification for dust collection Stop modification for dust collection at the bottom of second path of gas (i.e. at the bottom of second path of gas (i.e. below economiser) or provided vibration below economiser) or provided vibration at boiler bottom.at boiler bottom.

3.3. Closing of all gaps in economiser Closing of all gaps in economiser bundle area where low resistance path or bundle area where low resistance path or preferential path are createdpreferential path are created

4.4. PROVISION OF PH CHECKING IN PROVISION OF PH CHECKING IN CONTROL ROOM AT OPERATOR’S DESKCONTROL ROOM AT OPERATOR’S DESK