birla copper part 1

TITLE : INTRODUCTION

A 0 - 0 - 0 - 0

INTRODUCTION

BIRLA COPPER – B008 1


A1.0.0.0 INTRODUCTION

In ever growing industrialisation of developed and developing nations, electric

power generation through boilers of thermal power station have played very

important role over a century. Coal, lignite, fuel oil, natural gas etc. are some of

the fuels available as natural resources and these are being consumed for steam

generation. Combustion in conventional stoker fired, pulverised coal fired as well

as oil /gas fired boilers release pollutants like SOx, NOx, CO etc invariably in

much larger quantities which are harmful to human life. This aspect has been

attracting more and more attention of governments as well as people and the

main focus is now on generation of steam with environmentally friendly system of

firing in boilers.

"CFBC Boiler" offers valuable solution to reduce ill effects of pollution. Salient

advantages of this system are :

a) Fuel of different types/origin and quality can be burnt without any problems

at high degree of efficiency.

b) Sulphur dioxide, Hydrogen chloride, Hydrogen fluoride released during

combustion are retained in the ash with the help of Limestone.

c) Due to low combustion temperature and combustion in stages there is only

a little development of Nitrogen monoxide.

Thus reduction of gaseous pollutants produced during combustion is achieved by

combustion process itself, which is speciality of this technology and process

steps are integrated into firing system. Flue gas cleaning systems, which are

unavoidable in conventional boilers, are not necessary in Circofluid system and

thus eliminate additional efficiency losses.



The advantages of stationary fluidised bed firing system such as:

Low investment cost.

Simple and reliable firing arrangement.

Easy fuel processing.

Short start up periods are combined with advantages of circulating fluidised bed

firing system which are:

High firing efficiency

High sulphur retention with low limestone consumption

Lower NOx formation helped by staged firing.

CFBC technology also offers highly reliable means of steam generation burning

wide range of fossil fuels without any problems.


TITLE : SYSTEM AND FUNCTION DESCRIPTION

B0 - 0 - 0 - 0

SYSTEM AND FUNCTION DESCRIPTION


TITLE : CFBC FIRING SYSTEM

B1 - 0 - 0 - 0

CFBC FIRING SYSTEM


TITLE : CFBC FIRING SYSTEM

B1.0.0.0 CFBC FIRING SYSTEM

In the CFBC firing system about 50% of the combustion of lignite and/or coal is

effected in a stationary fluidised bed of coarse bed ash and about 50% in the fine,

circulating ash above the fluidised bed, in the so called freeboard. The exact split

of the combustion can be influenced by means of controllable stages of the

combustion air supply with regard to primary, secondary and tertiary air.

Mixture of circulating ash and flue gases flow upwards and pass over the radiant

and convection heating surfaces of the 1st pass and is thereby cooled down to

270 to 420ºC depending on the boiler load. Subsequently it is separated from the

flue gas flow in cyclone separators connected in parallel. Ash collected in

cyclones drops in the siphons. Nozzles in siphon fluidise this ash and it spills

over into the chutes where mixture of fuel and limestone (if required) is added

before it returns to fluidised bed.

The cyclone ash circulation causes isothermal combustion to take place in wide

area of bed at temperatures in the range of 840 - 880ºC for Coal. An optimum

desulphurisation reaction takes place in this temperature range, which is

facilitated by the inherent content of calcium compounds in the lignite, and/or any

additionally fed limestone.

The cyclone ash circulation with flue gases, substantially contribute in heat

transfer from the fluidised bed to the heating surfaces of Screen, Evaporators,

Superheater and part of Economiser.

The high ash load of the flue gases facilitates intensive heat transfer by means of

radiant heat emission.


TITLE : PROCESS AND PLANT STRUCTURE

B2 - 0 - 0 - 0

PROCESS & PLANT STRUCTURE



B2.0.0.0 PROCESS & PLANT STRUCTURE

The plant basically consists of two boiler passes, electrostatic precipitator, one

induced draft fan, one primary air fan, one secondary air fan and 2 hot gas

generators. Cyclones and siphons are provided for circulating the ash.

The equipment for fuel transport, limestone feeding (not included for this project)

and ash removal are located on the periphery of the plant. The ash removal is

divided into removal systems for bed, cyclone and ESP ash.

Generally, 60% of air required for combustion, is supplied by primary air fans at

about 1500mmWG pressure. Primary air, flows through tubular air heater, wind-

box and enters the combustor simultaneously fluidising the bed ash during

normal operation of the boiler. Air heater is provided with by-pass arrangement

for start up.

Secondary fan supplies air at about 450 mmWG, which forms the remaining 40%

of the combustion air, i.e the secondary and tertiary air. This fan is also equipped

with suction and discharge dampers like P.A. fan and the air, flows through air

heater. Air splitting - secondary and tertiary takes place after air heater outlet.

Secondary air enters combustor through nozzles located at lower elevation than

that for tertiary air. This method is known as "air staging". Secondary and

primary air has independent paths through air heater.

Fuel (coal or lignite) with grain size <8.0 mm (fines i.e. <1.0 mm not exceeding

40%) falls in combustor mixed with circulating ash through fuel chutes from

siphon. The location where fuel-ash mixture enters combustor is partly immersed

in fluidised bed.

In the stationary state, approximately 800 to 1000 mm thick layer of ash (initially

bed material) is lying in the bottom of combustor. This mass is fluidised by the

force of incoming air from primary air nozzles (fitted on the distribution plate)

inflating the height of bed. Primary air pressure reduces more or less linearly (10


mmWG per 15 mm height of bed material) from nozzles to the top of the bed.

Fuel percentage in bed during combustion is roughly 2 to 3%.


In combustion process, fines are carried away upwards from fluidised bed with

flue gas. Secondary air and tertiary air is pushed through number of nozzles at

10.3 m and 13.8 m elevation respectively to provide plenty of oxygen and burn

them in free board during upward flow of flue gas with ash. Flue gas temperature

in free board may be around 1000ºC depending on volatiles and quantity of fines

in fuel.

Heating surfaces of Screen, Superheaters, Evaporator and Economiser II absorb

heat from flue gases travelling upwards and approximate temperature of flue

gases entering cyclone is 420ºC. In cyclones, ash (grain size approximate 0.8

mm) is separated from flue gas and drops into siphons in course of its travel back

to combustor. Flue gas enters Economiser I and water flowing through its coils

absorb heat. Flue gas temperature at air heater inlet is approximately 260ºC. Air

from primary and secondary fans gain heat in air heater and the flue gas further

loses heat in turn with AH exit temp around 145ºC.

Circulating cyclone ash not only helps heat transfer to pressure parts, but it also

substantially controls the bed temperature. Higher circulating ash from cyclones

(400ºC) reduces the bed temperature and vice-versa.

Primary air from air heater enters combustor through hot gas generator (during

start up or otherwise), wind box and large number of specially designed air

nozzles. I.D. fan is designed to handle flue gases for 100% MCR steam

generation maintaining balance draft in free board area.

Hot gas generators, which are attached to the wind box are provided for cold start

up. HSD oil is used in the oil burners, which get combustion air and dilution air

from Primary air fans. Hot flue gas generated by HGG mainly assists to raise bed

temperature, to a level, which is slightly higher than ignition temperature of fuel.

During cold start up, flue gas temperature at air heater outlet is generally below

the acid dew point and therefore air is pushed through air heater by-pass

duct/damper arrangement to avoid cold end corrosion.


TITLE : CONTROL FUNCTIONS

B3 - 0 - 0 – 0

CONTROL FUNCTIONS



B3.0.0.0 CONTROL FUNCTIONS

Instrumentation and control philosophy of CFBC boiler incorporates control loops,

which are mostly common with other conventional boiler control systems.

Broadly total scheme can be split into:

1. Boiler protection

2. Boiler interlock

3. Auto control

B3.1.0.0 BOILER PROTECTION:

During cold or hot start up of the boiler as also normal operation of the unit,

certain parameters e.g. drum level, final steam temperature, bed temperature etc.

are monitored on continuous basis and ensures that unit will be pulled out of

service in cases of deviations beyond set limits. The unit will be restarted only

after normal values are established.

B3.2.0.0 BOILER INTERLOCKS:

In order to start the boiler smoothly safely and in a desired sequence, certain

interlocks are provided. The contacts / sources to achieve sequential start are

drawn from MCC, transmitters, actuators etc. The unit can also be shut down

safely as per desired sequence and same contacts will mostly be useful in normal

shut down sequence.

B3.3.0.0 AUTO CONTROLS:

The steam generator is normally expected to maintain operating parameters at

desired levels from approximately 35% MCR to 100% MCR by tuning the

standard control loops as described below:



B3.3.1.0 THREE – ELEMENT CONTROL:

Steam flow, feed water flow (including attemperation) and drum level are

conventional parameters which form the operating circuit to regulate feed water

flow to maintain the drum level at a steady state. In specific application, basic

elements are pressure and temperature compensated.

The steam generator is normally expected to maintain operating parameters at

desired levels from approximately 35% MCR to 100% MCR by tuning the

standard control loops as described below :

B3.3.2.0. FURNACE DRAFT CONTROL:

Usually, furnace draft is measured from a point few metres below the screen and

fed in control circuit to maintain it at a steady desired value by regulating Induced

draft MLPB Suction dampers. Some anticipatory signals from total air may help

controlling furnace draft better.

B3.3.3.0 STEAM TEMPERATURE CONTROL:

At higher load say above 60% MCR, mass flow of flue gases and heat absorption

in superheater, reaches a stage when it is possible not only to achieve final

steam temperature, but at times it becomes necessary to cool the steam in

stages to maintain superheater outlet steam temperature within few degrees from

rated temperature. Spray attemperator is interposed between SH I & SH II such

that SH I outlet steam is cooled by water spray to enter SH II at the desired

temperature. Attemperation is further provided between SH II and SH III to control

the Final SH Outlet Steam temperature to the desired value.



STEAM TEMPERATURE CONTROL

Spray Attemperator – 1

Spray Attemperator – 2

M MS Outlet

SH3


Outet

Inlet

Outlet

SH 2

SH 1

Inlet

Outlet


As the load increases, the quantity of water spray also increases. In the event of

only one spray nozzle, it is likely that at higher water flow, instead of very fine

particles (atomisation) of water, to achieve quick evaporation, big drops may

come off causing adverse effect on life of attemperator. Multi spray nozzle

system incorporated in CFBC boiler ensures spray of water within specific limits

through each nozzle.

B3.3.4.0 BED TEMPERATURE CONTROL:

To regulate the emission of pollutants such as CO and NOx it is necessary to

control the bed temperature. Also if desulphurisation of fuel with Limestone is

required, such reaction takes place in the bed and the effectiveness depends on

the temperature of the bed ash.

Normally bed temperature for coal is around 840 to 880°C. The ash temperature

at cyclone outlet is approximately 4000C and therefore increase or decrease of

cyclone circulating ash quantity (at 4000C) will decrease or increase the bed

temperature from its present level.

In other words, quantity of cyclone ash put back in circulation through siphon or a

portion of it extracted through cyclone ash screw will help control the bed

temperature. It is therefore speed regulation of cyclone ash screw, which will

govern bed temperature effectively.

Bed temperature is one of the important parameters in boiler protection. Main

fuel cannot be charged, unless bed attains minimum set value of ignition

temperature. Similarly in case, the bed temperature increases beyond safe limit

e.g. 940°C approximately, the boiler should be tripped.



As long as bed temperature is less than ignition temperature of fuel, HGGs have

to be pressed in service. After a short shut down, main fuel may be charged

directly when bed temperature is at least 20°C above ignition temperature of main

fuel. Approximately 3 to 4 hours will suffice to raise the bed temperature to

ignition value in cold starts through HGG.

B3.3.5.0. BED HEIGHT CONTROL:

Ash generated during combustion has three outlet/ extraction points namely bed

drain, cyclone ash screw and fly ash from ESP hoppers. Almost 85 to 95% of

ash is removed through cyclone ash coolers and ESP hoppers put together and

remaining portion gets gradually accumulated in bed. Static head required for

fluidising will increase with increase in bed ash and therefore bed ash is drained

intermittently (say once in a shift). This is purely remote - manual operation. Bed

ash screw cooler is started from control room and gate valves are opened to

drain excessive ash accumulated. Soon after bed differential drops to minimum

desired value, bed ash drain is stopped by closing the gate valves.

B3.3.6.0. STEAM PRESSURE CONTROL :

The control room operator sets the desired pressure of final steam for automatic

controls. Steam flow signal is used for feed flow in derivative action. The signal

thus generated is command signal for firing normally called as Load signal.

B3.3.7.0. COAL FLOW CONTROL :

Coal flow signal is compared with total primary air flow. The output of this

controller is compared with the load signal to develop set point to coal controller.

The summation of coal feeder (actual) speeds is worked out and compared with

coal controller set point to determine/change the actual value of coal controller.

Control room operator may modify the set point of the coal controller, after

observing the O2 content of flue gas.



B3.3.8.0. AIR FLOW CONTROL:

The ratio of total air to boiler load can be changed by the control room operator.

The load dependant total air (including excess air) is impressed on the output

signal. The signal receives an absolute and fuel dependant minimum value

limitation.

Command signal for primary air is generated in similar fashion with a difference

that a portion of a coal signal is of significance for fuel dependant minimum value

limitation. Pressure and temperature corrected actual (total) P.A flow is compared

with lead P.A. flow and controller sends output to reposition the P.A. suction

vanes.

The difference between total air and P.A. is command signal for secondary +

tertiary air. The ratio of secondary air to tertiary air is pre-determined by control

room operator. However, free board temperature control can trim this ratio in

favour of tertiary air i.e. increase in tertiary air quantity to a limited extent when

free board temperature is too low.

The secondary air set point is deducted from common set point i.e. sum of

secondary + tertiary air. The remaining value is for tertiary air.


TITLE : CONSTRUCTIONAL FEATURES

C - 0 - 0 - 0 – 0

CONSTRUCTIONAL FEATURES


TITLE : BOILER DATA AND EQUIPMENT SPECIFICATIONS

C1 - 0 - 0 – 0

BOILER DATA AND EQUIPMENT SPECIFICATIONS



C1.0.0.0 BOILER DATA AND EQUIPMENT SPECIFICATIONS

C1.1.0.0 TYPE

Natural Circulation, Single Drum, Top Supported, Balanced Draft, Tower Type,

Membrane Panel Constructed, Outdoor Unit Equipped with Two Cyclones,

having Economiser and Tubular Air-Preheater as back end heat traps and 1 x

100% Draught Plant (Primary Air fan, Secondary Air Fan and Induced Draught

Fan).

C1.2.0.0 GENERAL INFORMATION

Steam Flow : MCR 150 TPH

Steam Pressure at outlet of Steam Stop Valve : 96 kg/cm2 (g)

Steam Temp at outlet of Steam Stop Valve : 535+50C

(60to100%MCR)

Feed Water Temp at inlet of Economiser : 2200C

Design Pressure : 114 Kg/cm²g

C1.3.0.0 PERFORMANCE GUARANTEE

MCR : 150 TPH

Final Steam Pressure : 96Kg/cm²g

Final Steam Temp. : 535 + 50C

Efficiency at MCR based on GCV of design fuel (Coal) : 87.9 + 1%

Performance Test will be carried out as per ASME PTC 4.1

(Indirect abbreviated method).

Thermal efficiency on GCV of design coal as evaluated w.r.t. an ambient

temp. of 30°C and 60% relative humidity.



C1.4.0.0 PLANT DETAILS :

C1.4.1.0 Site Data :

Avg. Max. Min.

Ambient air temperature °C 30

Ambient air temperature Design. °C 30

Ambient air temperature (for motors) 50

Ambient air temperature 47(Fans & thermal Insulation)

Relative Humidity % 60 100 20

Altitude 285 M above MSL

Wind Velocity Km/hr 7.2 2.2

Horizontal Seismic Coefficient as per IS-1893 - Zone III

C1.4.2.0 Electrical Supply :

Variations : Voltage + 10%Frequency + 5%Combined + 10%

HT : 3.3 KV /50 HZ(above160 KW rating)

LT : 415V / 50 HZ for LT motors

Instrumentation : 230 V AC system, single phase



C1.4.4.0 Compressed Air :

Pressure Kg/cm²(g) Normal

Instrument air supply pr.(dry)free from

moisture, traces of oil and other impurities 7.0

Service air supply pr. free from moisture,

traces of oil content 7.0

C1.4.4.1 Cooling Water

Pressure : 4.5 kg/cm2(g)

Temperature : 33°C

C1.5.0.0 INPUTS FROM BIRLA COPPER

Range Design

C1.5.1.0 Fuel Analysis (Coal)

Proximate Analysis :

Fixed Carbon % 25-35 29.8

Volatile Matter % 22-29 27.4

Ash % 35-42 35.9

Moisture % 4-9 6.9

GCV KCal/Kg. 4100

Grindability Index HGI 64-69 69



Ultimate Analysis:

Carbon % 43.3

Hydrogen % 2.7

Nitrogen % 1.0

Sulphur % 0.6

Oxygen % 9.6

Ash % 35.9

Moisture % 6.9

Coal Size :

a) 100 % < 8.0 mm

b 40 % (max.) < 1.0 mm (fines)

C1.5.2.0 Ash Analysis:

SiO2 % 58.6

Fe2O3 % 4.1

TiO2 % 1.8

Al2O3 % 26.3

CaO % 1.4

MgO % 0.9

SO3 % Traces

P2O5 % 2.4

Alkalies (by difference) 4.5

C1.5.3.0 Start-up Fuel :

Type of fuel : HSD

GCV : 10000 Kcal/kg



C1.5.4.0 Feed Water (as per Vd TUV/VGB directive)

1. Boiler working pressure > 80 kg/cm2(g)

2. General requirement Clear and colourless

3. Specific electrical conductivitiy at 25°C Guide values of boiler water

are to be respected.

1. Hardness mVal/kg Not detectable

2. Total Iron mg/kg <0.02

3. Total Copper mg/kg <0.003

4. Total silica mg/kg <0.02

5. Oxygen mg/kg <0.02

6. PH at 25°C >9

8. Permanganate mg/kg <5(possible consumption)

Total carbonic acid

9. Total Co2

10. Oil mg/kg <0.5

C1.5.4.1 Boiler Water

P Value m Val/kg <0.3

pH value at 25°C 9 – 10.5

Silica SiO2 mg/kg <4.0

In case of phosphate injection PO4 mg/kg 2-6

Conductivity at 25°C s/cm <300



C1.6.0.0 MAJOR EQUIPMENT SPECIFICATIONS

C1.6.1.0 Fan

C1.6.1.1 Primary Air Fan

Quantity : One No.

Make : TLT Engg.(I) Pvt. Ltd.

Volume Flow : 11.4 Nm³/sec per fan

Static Pressure : 2000 mmwg

Temperature : 50°C

Speed : 1480 RPM

Damper Control : Inlet Vane Control

C1.6.1.2 Secondary Air Fan

Quantity : One No.


Volume Flow : 10.3 Nm³/sec per fan

Static Pressure : 820 mmwg

Temperature : 50°C

Speed : 1480 RPM

Damper Control : Inlet Vane Control

C1.6.1.3 Induced Draught Fan

Quantity : One No.


Volume Flow : 22.8 Nm3/sec per fan

Static Pressure : 645 mmWC

Temperature : 160°C

Speed : 980 RPM

Damper Control : Inlet MLPB Damper



C1.6.2.0 Roots Blowers

Quantity : 2 nos.(1Working+ 1Standby)

Make : Kulkarni Engg. Asso. Ltd.

Volume Flow : 1529 Nm3/Hr

Discharge Pressure : 468m bar (at blower outlet)

Temperature : 50°C

Control : Variable Speed.

C1.6.3.0 Coal Feeders

Quantity : 2 nos.

Make : Methods

Capacity : 25 TPH

Width : 800 mm

Conveying speed : 0.07 m/sec (max)

Turn Down : 1:5

Control : Variable Speed.

Particle size distribution : 100 % < 8mm

max. 40% < 1mm

Bulk Density : 800 kg/m³ - Coal



C1.6.5.0 Safety Valves :

Quantity : 03 nos

Make : F.M.C. SANMAR Ltd..

SET PRESSURE

Drum-1 : 113 kg/cm²g (60 TPH)

Drum-2 : 112 kg/cm²g (60 TPH)

Super-heater : 100.8 kg/cm² g (30 TPH)

EMRV : 100.3 kg/cm2 (30 TPH)

C1.6.6.0 Start-up Vent

Quantity : 1 no.

Make : BHEL

Type : Globe, regulating

Size : 100 mm

C1.6.7.0 ESP

Number of streams : 2

Make : ACC

Volume of Flow of flue gases : 45.6 Nm3/sec

Temperature of glue gases : 160°c

Dust loading at ESP inlet : 100 gm/Nm3

Dust loading at ESP outlet : 150 mg/Nm3

System pressure : -480 mmWC

Max. permissible pressure drop : 25 mm

SO2 content in flue gas : 0.000948 kg/kg

H2O content in flue gas : 0.0534 kg/kg



C1.6.8.0 Hot Gas Generators

Quantity : 2 nos

Make : Coen Bharat

Fuel oil : HSD

Max. Fuel oil Consumption : 900kg/hr

Gas temp. at HGG outlet : 850o C at outlet.

Turn Down : 1 : 5

C1.6.9.0 Fuel Oil Pumps

Fuel oil : HSD

Flow rate : 1700 kgs/hr

Discharge Pressure : 8.0 kgs/cm2(g)

C1.6.10.0 Cyclone Ash Cooling System

C1.6.10.1 Cyclone Ash Screw Feeder

Quantity : 2 nos.

Make : Methods

Arrangement : Horizontal

Trough Dia. : 300 mm - U

Conveying length : 2225 mm.

Temperature : 450o C at inlet max.350 - 375°C at outlet.

Capacity : 3 TPH

Jacket cooling water pressure : 4.5kg/cm² at inlet (max.)

Turn down : 1 : 5



C1.6.11.0 Bed Ash Screw Cooler.

Capacity : 0.6 TPH

Inlet temp of ash : 850°C

Outlet temp of ash : 300°C

Inlet temp of water : 30°C

Outlet temp of water : 39°C

C1.6.12.0 Chemical Dosing System

C1.6.12.1 HP Dosing System

a) Tank Dosing Tank

i) No. of tanks : One

ii) Capacity (Litres) : 400

b) Pumps

i) Quantity : 2 x 100%

ii) Make : V.K. Pump. Bombay

iii) Type / mode : Positive Displacement / PR-10

iv) Max. dosing reqd. : 20 LPH

v) Discharge Pr. at full stroke : 85 kg/cm2g

vi) No. of strokes/min. : 185



C1.6.12.2 Hydrazine L.P. Dosing System

a) Tank Dosing Tank

i)) No. of tanks One

ii) Capacity (Litres) 400

b. Pumps

i) Quantity : 2 nos x 100%

ii) Make : V.K. Pumps, Bombay

iii) Type/Model : Positive displacement / PR-10

iv) Max. Dosing : 20 LPH

v) Discharge pressure : 6 kg/cm2(g)

vi) No. of strokes/min : 185

C1.6.12.3 Cyclo Hexamin L.P. Dosing System

a) Tank Dosing Tank

i)) No. of tanks One

ii) Capacity (Litres) 400

b. Pumps

i) Quantity : 2 nos x 100%

ii) Make : V.K. Pumps, Bombay

iii) Type/Model : Positive displacement / PR-10

iv) Max. Dosing : 20 LPH

v) Discharge pressure : 6 kg/cm2(g)

vi) No. of strokes/min : 185



SCHEDULE OF PRESSURE PARTS

Sr. No. Description Sizes Material Specification

1 Steam drumShell 1810 O.D x 75 thk BS 1501-224 Gr. 490 BDished Ends 70 mm thk BS 1501-224 Gr. 490 B

2 FurnaceF.W. membrane panels 44.5 O.D x 5 thk BS3059 PII GR440R.W memrane panels 44.5 O.D x 5 thk BS3059 PII GR440L.H side wall memrane panels 44.5 O.D x 5 thk BS3059 PII GR440R.H side wall memrane panel 44.5 O.D x 5 thk BS3059 PII GR440Roof panel 44.5 O.D x 5 thk BS3059 PII GR440Air box 44.5 O.D x 5 thk BS3059 PII GR440

3 Furnace headersFront wall bottom header 219.1O.D X 23 thk SA 106 Gr BRear wall bottom header 219.1O.D X 23 thk SA 106 Gr BS.W bottom header Right 219.1O.D X 23 thk SA 106 Gr BS.W bottom header Left 219.1O.D X 23 thk SA 106 Gr BSide wall top header 219.1O.D X 23 thk SA 106 Gr BFront & rear wall top header 219.1O.D X 23 thk SA 106 Gr B

4 Screen Panels 38.1 O.D x 5 thk 15 Mo 3Screen tube inlet header 273 O.D x 25.4 thk SA 106 Gr B

5 SH1,SH2,SH3 supporting tubes 44.5 O.D x 5 thk BS3059 PII GR440

6 EVAP. supporting tubes 44.5 O.D x 5 thk BS 3059 PII Gr 440

7 ECO 2 supporting tubes 44.5 O.D x 5 thk BS3059 PII GR440

8 Supporting tubes above ECO-2 44.5 O.D x 5 thk BS3059 PII GR440

9 Outlet header for supporting tubes 273 X 25.4 thk SA 106 Gr B

10 Main downcomer 298 O.D X 28 thk SA 106 Gr B

11 Main downcomer header 298 O.D X 28.6 thk SA 106 Gr B

12 Evporator inlet & outlet header 273 X 28.6 thk SA 106 Gr B

13 Evaporator coils 44.5 O.D x 4.5 thk BS3059 PII GR440

14 Saturated steam header 219.1 O.D X 23 thk SA 106 Gr B




15 Economiser 11)Economiser 1 inlet header 219.1O.D X 23 thk SA 106 Gr B2)Economiser 1 outlet header 219.1O.D X 23 thk SA 106 Gr B3)Economiser 1 coil 38.1O.D X 3.6 thk BS3059 PII GR440

16 Economiser 21)Economiser 2 inlet header 219.1 O.D X 23 thk SA 106 Gr B2)Economiser 2 outlet header 219.1 O.D X 23 thk SA 106 Gr B3) Economiser 2 coils 38.1O.D X 3.6 thk BS3059 PII GR440

17 Superheater 11)Superheater 1 inlet header 219.1 O.D X 23 thk SA 106 Gr B2)Superheater 1 outlet header 219.1 O.D X 23 thk 13 Cr Mo 443)Superheater 1 coil 31.8 O.D X 4 thk 15 Mo 3

31.8 O.D X 4 thk 13 Cr Mo 4418 Superheater 2

1)Superheater 2 inlet header 219.1O.D X 20 thk 15 Mo 32)Superheater 2 outlet header 273 O.D X 32 thk 13 Cr Mo 443)Superheater 2 coil 31.8 O.D X 5 thk 10 Cr Mo 910

19 Superheater 31)Superheater 3 inlet header 273O.D X 32 thk 15 Mo 32)Superheater 3 outlet header 273 O.D X 45 thk 13 Cr Mo 443)Superheater 3 coil 31.8 O.D X 5 thk 10 Cr Mo 910

20 Interconnecting piping from ECO1 168.3 O.D X 14.3 thk SA 106 Gr Bto ECO 2.

21 Piping from SH1 outlet to ATTEMP 219.1 O.D X 20 thk 13 Cr Mo 441 & from ATTEMP 1 to SH2 inlet

23 Piping from Saturated steam header 219.1 O.D X 23 thk SA 106 Gr Bto SH-1 inlet header

24 Riser tubes from header to drum 88.9 O.D X 6.3 thk BS3059 PII GR440

25 Connecting tubes from downcomer 88.9 O.D X 6.3 thk BS3059 PII GR440to membrane wall bottom header

26 Connecting tubes from drum to 88.9 O.D X 6.3 thk BS3059 PII GR440evap. inlet header and to drum

27 Tubes from ECO2 to drum 88.9 O.D X 6.3 thk BS3059 PII GR440

28 Tubes from drum to saturated 88.9 O.D X 6.3 thk BS3059 PII GR440steam header




29 Connecting tubes from drum to 88.9 O.D X 6.3 thk BS3059 PII GR440screen tube inlet header

30 Feed water line upto feed control 168.3 O.D x 14.3 thk SA106 Gr Bstation & to ECO-1

31 Spray Attemperator – 1st Stage 210.1 O.D X 20 thk 13 Cr Mo 44

32 Spray Attemperator – 2nd Stage 273 O.D X 32 thk 13 Cr Mo 44



SCHEDULE OF VALVES

Sl. No.

Item NB mm

H/M

End Conn.

Class Matl Valve Qty.

Duty / Remarks Tag No.

A : GATE VALVES

1 outlet of CBD. TANK 50 H SW 800 A105 2 CBD. level control 50-V-140

2 EMSV 65 H BW 900 WC9 1 Isolation 65-V-154

3 30 % FCV 80 H BW 600 WCB 1

For downstream isolation(100NB valve with ends suitable for 80NB pipe)

80-V-143

4 30 % FCV 80 M BW 900 WCB 1

For upstream isolation(100NB valve with ends suitable for 80NB pipe)

80-V-144-MO

5 Start up vent 100 H BW 900 WC9 1 For isolation 100-V-154

6 30-100 %FCV 150 H BW 600 WCB 1 For downstream isolation 150-V-143

7 Economiser inlet 150 H BW 600 WCB 1 For feed Isolation 150-V-143

8 On FCV bypass line 150 H BW 600 WCB 1 For downstream isolation 150-V-143

9 30-100 %FCV 150 M BW 900 WCB 1 For upstream isolation150-V-

144-MO

10 On FCV bypass line 150 M BW 900 WCB 1 For upstream isolation150-V-

144-MO

11 Mainsteam stop 200 M BW 900 WC9 1With integral bypass both motorised

200-V-154-MO

Total no. of Gate Valves : 12

B : GLOBE VALVES

12 On CBD.& IBD tank 15 H SW 800 A105 2 PG. isolation 15-V-240

13 Instrument isolations 15 H SW 800 A105 6For pr. measurement on upstream of fcs

15-V-240

14 Instrument isolations 15 H SW 800 A105 8For flow measurement on upstram of fcs

15-V-240

15 Instrument isolations 15 H SW 800 A105 4For pr.measurement on feedwater line eco inlet

15-V-240

16Feedwater/Dearator sampling

15 H SW 800 A105 6For isolation, at Eco1 inlet& for deaerator

15-V-240

17 Instrument isolations 15 H SW 800 A105 6For pr. measurement on drum

15-V-240

18 HP dosing line 15 H SW 800 A105 2 For isolations 15-V-240

19 W.L.I. drains 15 H SW 800 A105 4 Drain 15-V-240

20 sat steam sampling 15 H SW 800 A105 3 ISOLATION 15-V-240

21 Blow down sampling 15 H SW 800 A105 3 For isolations 15-V-240

22 Instrument isolations 15 H SW 800 A105 4For pr. measurement on spray line

15-V-240

23 Instrument isolations 15 H SW 800 A105 8For flow measurement on spray line

15-V-240


Sl. No.

ItemNB mm

H/M

End Conn.

Class MatlValve Qty.


24 Instrument isolation 15 H SW 1500 F22 8Root valves for flow measurement.(main steam)

15-V-255A

25 Instrument isolation 15 H SW 1500 F22 6Root valves for pr. measurement.(msl to turbine)

15-V-255A

26 Main steam sampling 15 H SW 1500 F22 3 For isolation 15-V-255A

27 Eco vent 25 H SW 800 A105 2 On header 25-V-240

28 FCV Vent 25 H SW 800 A105 6 On header 25-V-240

29 Instrument isolations 25 H SW 800 A105 24For level measurement on drum

25-V-240

30 Sat steam header vent 25 H SW 800 A105 2 Vent 25-V-240

31 N2 Capping 25 H SW 800 A105 2 For isolations 25-V-240

32 On CBD. tank 25 H SW 800 A105 2 Isolation on LG 25-V-240

33 Sample cooler 25 H SW 800 A105 11 sample cooler cooling water

25-V-240

34 On CBD. tank 25 H SW 800 A105 2 LT. isolation 25-V-240

35 oulet of IBD. tank 25 H SW 800 A105 2IBD. tank outlet & effluent discharge pump inlet

25-V-240

36Att.control valve drain line isolation

25 H SW 800 A105 4 Drain 25-V-240

37Attemp.stn bypass isolation

32 H SW 800 A105 2 Upstream & downstream 32-V-240

38 Attemp. station 32 M SW 800 A105 1 For upstream32-V-240-

MO

39 Attemperator bypass 32 M SW 800 A105 1Bypass, Regulating type,inching with position transmitter

32-V-240B-MI

40 Attemp. station 32 M SW 800 A105 1 For downstream32-V-240-

MO

41 Att.#1 spray nozzle 32 M SW 1500 F22 2 For isolation32-V-

255A-MO

42 0-30% FCV 40 H SW 800 A105 4Drain upstream/downstream

40-V-240

43 30-100% FCV 40 H SW 800 A105 4Drain upstream/downstream

40-V-240

44 Filling line 40 H SW 800 A105 2 For upstream 40-V-240

45 Eco2 drain 40 H SW 800 A105 2 Drain 40-V-240

46 Eco1 drain 40 H SW 800 A105 2 Drain 40-V-240

47 FCV bypass drain 40 H SW 800 A105 4 Drain 40-V-240

48 FCV drain line 40 H SW 800 A105 2 Drain 40-V-240

49 Evap bdl,wall,screen drain

40 H SW 800 A105 5 For isolations 40-V-240

50 Evap drain hdr to IBD 40 H SW 800 A105 1 For isolations 40-V-240

51 Main downcomer to IBD 40 H SW 800 A105 1 For isolation 40-V-240


Sl. No.

ItemNB mm

H/M

End Conn.

Class MatlValve Qty.


52 Soot blower isolation 40 H SW 800 A105 2 Line inlet to superheater-2 40-V-240

53 Emergency Blowdown 40 H SW 800 A105 1 Isolation 40-V-240

54 CBD valve 40 H SW 800 A105 1 ISOLATION 40-V-240

55 Main downcomer to IBD 40 M SW 800 A105 1 40-V-240-

MO

56 Spray water line 40 M SW 800 A105 1Block Valve(CLIENT TO CONFIRM)

40-V-240-MO

57 Emergency Blowdown 40 M SW 800 A105 1Regulating type,inching with position transmitter

40-V-240B-MI

58 CBD line 40 M SW 1500 A105 1Regulating type blow down valve,inching,with position transmitter

40-V-245A-MI-

CBD

59 Evap bdl,wall,screen drain

40 H SW 1500 F22 7 For isolations 40-V-255A

60 SH drain hdr to IBD 40 H SW 1500 F22 1 Drain 40-V-255A

61 SH1 drains 40 H SW 1500 F22 2 Drain 40-V-255A

62 SH2 drain 40 H SW 1500 F22 2 Drain 40-V-255A

63 Main steam piping drain 40 H SW 1500 F22 2 Drain 40-V-255A

64 S.H. # 2 header 50 H SW 1500 F22 2 Vent 50-V-255A

65 CBD. level control 50 M SW 800 A105 1bypass, Regulating type,inching with position transmitter

50-V-240B-MI

66 Start up vent 100 M BW 1500 WC9 1Regulating type, inching with position transmitter

100-V-255-MI

67 On FCV bypass line 150 M BW 2500 WCB 1bypass, Regulating type, inching with position transmitter

150-V-246-MI

Total no. of Globe Valves : 191

C : NRV

68 HP dosing 15 --- SW 800 A105 1 Feed check valve 15-V-340

69 On spray att. #1 32 --- SW 1500 F22 1 Feed check valve 32-V-355A

70 Spray water line 40 -- SW 800 A105 1 Feed check valve 40-V-340

71 Filling line 40 --- SW 800 A105 1 Feed check valve 40-V-340

72 Economiser inlet 150 --- BW 1500 WCB 1 Feed check valve 150-V-345

73 Main steam 200 --- BW 1500 WC9 1 Feed check valve 200-V-355

Total no. of NRVs : 6

Total no. of Valves : 209



SCHEDULE OF ELECTRICAL EQUIPMENTS

SR. NO.

TAG NO. ITEM MOTOR RATING

(kW)

RPM FIXED / VAR.

SPEED

FLC Amp

REMARKS

A) H.T.MOTORS (3.3kV +/- 10%, 50Hz -5% to +5%)

1 PA-FN-001 P.A.FAN # 1 400 1480 F

2 PA-FN-002 P.A.FAN # 2 400 1480 F

3 ID-FN-001 I.D.FAN # 1 360 980 F

4 ID-FN-002 I.D.FAN # 2 360 980 F

B) L.T.MOTORS (415V +/- 10%, 50Hz -5% to +5%)

1 RB-001 ROOTS BLOWER #1 22 1500 V

2 RB-002 ROOTS BLOWER #2 22 1500 V

3 CL-F-001 COAL FEEDER #1 5.5 750 V

4 CL-F-002 COAL FEEDER #2 5.5 750 V

5 BA-SC-001 BED ASH COOLER #1 7.5 750 V

6 BA-SC-002 BED ASH COOLER #2 7.5 750 V

7 CA-SF-001 CYCL ASH SCREW FEEDER #1 3.7 1480 V

8 CA-SF-002 CYCL ASH SCREW FEEDER #2 3.7 1480 V

9 SA-FN-001 S.A.FAN # 1 160 1480 F

10 SA-FN-002 S.A.FAN # 2 160 1480 F

11 LDO-P-001 LDO PUMP #1 3.7 1440 F

12 LDO-P-002 LDO PUMP #2 3.7 1440 F

13 BDT-P-001 BLOWDOWN TRANSFER PUMP#1

1.5 1480 F

14 BDT-P-002 BLOWDOWN TRANSFER PUMP#2

1.5 1480 F

C) FRACTIONAL H.P. MOTORS (415V +/- 10%, 50Hz +/- 5%)

1 SB-001 SOOT BLOWER #1 0.1 1480 F

2 SB-002 SOOT BLOWER #2 0.1 1480 F |

3 SB-003 SOOT BLOWER #3 0.1 1480 F Future provision.

4 SB-004 SOOT BLOWER #4 0.1 1480 F |

5 SB-005 SOOT BLOWER #5 0.1 1480 F |

6 SB-006 SOOT BLOWER #6 0.1 1480 F

7 SB-007 SOOT BLOWER #7 0.1 1480 F


SR. NO.


(kW)

RPM FIXED / VAR.

SPEED

FLC Amp

REMARKS

8 SB-008 SOOT BLOWER #8 0.1 1480 F

9 SB-009 SOOT BLOWER #9 0.1 1480 F |

10 SB-010 SOOT BLOWER #10 0.1 1480 F Future provision.

11 SB-011 SOOT BLOWER #11 0.1 1480 F |

12 SB-012 SOOT BLOWER #12 0.1 1480 F

13 HPD-P-001 H.P. DOSING PUMP #1 0.75 1480 F

14 HPD-P-002 H.P. DOSING PUMP #2 0.75 1480 F

15 HPD-ST-001 STIRRER 0.37 1480 F

16 CHD-P-001 CYCLOHEXAMINE DOSING PUMP #1

0.37 1480 F

17 CHD-P-002 CYCLOHEXAMINE DOSING PUMP #2

0.37 1480 F

18 CHD-ST-001 STIRRER 0.37 1480 F

19 LPD-P-001 L..P. DOSING PUMP #1 0.75 1480 F

20 LPD-P-002 L..P. DOSING PUMP #2 0.75 1480 F

21 LPD-ST-001 STIRRER 0.37 1480 F

D ) MOTORISED ACTUATORS FOR VALVES

1 100-V-255 START UP VENT REGLN. 2.2 1480 modulating, inching

2 200-V-154 MAIN STEAM STOP VALVE ISLN.

5 1480 on / off

3 200-V-154-BY

MAIN STEAM STOP VALVE BYP.

0.12 1480 on / off

4 40-V-240 QUICK SHUT OFF VALVE 0.12 1480 on / off

5 32-V-255-001

ATTEMP.-1 NOZZLE ISOLN. VALVE # 1

1.1 1480 on / off

6 32-V-255-002

ATTEMP.-1 NOZZLE ISOLN. VALVE # 2

1.1 1480 on / off

7 32-V-240-001

ATTEMP FCS BYPASS MODULATING

0.12 1480 Modulating inching

8 32-V-240-002

ATTEMP FCS UPSTREAM ISOLATION

0.12 1480 on / off

9 32-V-240-003

ATTEMP FCS DOWNSTREAM ISOLATION

0.12 1480 on / off

10 40-V-CBD CONTINUOUS BLOW DOWN VALVE # 1

0.55 1480 modulating, inching

11 40-V-240-001

EMERGENCY BLOW DOWN VALVE(EBD) MODULATING

0.12 1480 modulating, inching

12 80-V-144 30 % FCV UPSTREAM ISOLATION

1.1 1480 on / off


SR. NO.


(kW)

RPM FIXED / VAR.

SPEED

FLC Amp

REMARKS

13 150-V-144-001

30 TO 100 % FCV UPSTREAM ISOLATION

1.1 1480 on / off

14 150-V-144-002

100 % FCV BYPASS UPSTREAM ISOLATION

1.1 1480 on / off

15 150-V-24_ 100 % FCV BYPASS MODULATING

4 1480 modulating, inching

16 40-V-240-002

MAIN DOWNCOMER TO CBD ISOLATION

0.12 1480 on / off

17 50-V-240 CBD LEVEL CONTROL BYPASS VALVE

0.12 1480 on / off

E ) MOTORISED ACTUATERS FOR DAMPERS

1 PA-DMP-209 HGG # 1 AIR BYPASS DAMPER 0.5 1480 F

2 PA-DMP-212 HGG # 2 AIR BYPASS DAMPER 0.5 1480 F

3 CL-G-001 SLIDE GATE AT BUNKER # 1 O/ L 1.0 1480 F

4 CL-G-002 SLIDE GATE AT BUNKER # 2 O/ L 1.0 1480 F

5 CL-G-003 SLIDE GATE AT FEEDER # 1 O / L 1.0 1480 F

6 CL-G-004 SLIDE GATE AT FEEDER # 2 O / L 1.0 1480 F

7 PA-DMP-205 AH BYPASS DAMPER #1 1.0 1480 F

8 PA-DMP-206 AH BYPASS DAMPER #2 1.0 1480 F

F ) MISCELLANEOUS

1 HGG PANEL 2.0 KVA

2 SOOT BLOWER PANEL 0.5 KVA Future provision should be made in LT MCC for these feeders.

3 ANALYSER 0.65KVA

4 SOLENOID VALVES 0.7 KVA

5 BUNKER LEVEL SWITCHES 1 KVA

6 ESP SYSTEM 450 KVA

7 OTHER INSTRUMENTS 4 KVA

G) SPARES

1 SPARE 1 1 1480 F

2 SPARE 2 1 1480 F

3 SPARE 3 1 1480 F

4 SPARE 4 1 1480 F C


SR. NO.


(kW)

RPM FIXED / VAR.

SPEED

FLC Amp

REMARKS

5 SPARE 5 1 1480 F C

6 SPARE 6 1 1480 F C

7 SPARE 7 1 1480 F C

8 SPARE 8 1 1480 F C

NOTE : 1) Roots blowers will be 1 working & 1 standby.

2) V - variable speed , F- fixed speed motors.



SCHEDULE OF DAMPERS

Sl.No. Item Description Medium Size in mm Tag No. Operation Type

1 PA fan # 1 suction air dia 800 PA-DMP-201 Pneumatic control

2 PA fan # 2 suction air dia 800 PA-DMP-202 Pneumatic control

3 PA fan # 1discharge air 1000x1000 PA-DMP-203 Manual Isolation

4 PA fan # 2 discharge air 1000x1000 PA-DMP-204 Manual Isolation

5 Air Heater bypass air 1700x850 PA-DMP-206 Motorised Isolation

6 PA to Air Heater air 2092x850 PA-DMP-205 Motorised Isolation

7 Combustion air HGG # 1 air 765x765 PA-DMP-210 Pneumatic control

8 Dilution air HGG # 1 air 560x700 PA-DMP-211 Pneumatic control

9 Bypass HGG # 1 air 1700x850 PA-DMP-212 Motorised Isolation

10 Combustion air HGG # 2 air 765x765 PA-DMP-207 Pneumatic control

11 Dilution air HGG # 2 air 560x700 PA-DMP-208 Pneumatic control

12 Bypass HGG # 2 air 1700x850 PA-DMP-209 Motorised Isolation

13 SA fan # 1 suction air dia 950 SA-DMP-201 Pneumatic control

14 SA fan # 2 suction air dia 950 SA-DMP-202 Pneumatic control

15 SA fan # 1discharge air 900x900 SA-DMP-203 Manual Isolation

16 SA fan # 2discharge air 900x900 SA-DMP-204 Manual Isolation

17 SA near Furnace air 1010x1520 SA-DMP-205 Pneumatic control

18 TA near Furnace air 1520x600 TA-DMP-201 Pneumatic control

19 ESP # 1 to ID fan # 1 inlet flue gas 1550x1550 FG-DMP-205 Manual Isolation

20 ESP # 2 to ID fan # 2 inlet flue gas 1550x1550 FG-DMP-206 Manual Isolation

21 ID fan # 1 discharge flue gas 1550x1550 FG-DMP-209 Manual Isolation

22 ID fan # 2 discharge flue gas 1550x1550 FG-DMP-210 Manual Isolation

23 ID fan # 1 suction flue gas 840x 2300 FG-DMP-207 Pneumatic control

24 ID fan # 2 suction flue gas 840x 2300 FG-DMP-208 Pneumatic control

25 ID Fans Cross-over Duct flue gas 1550 x 1550 FG-DMP-…... Manual Isolation

26 ESP # 1inlet flue gas 1200 x 1200 FG-DMP-201 Manual Isolation

27 ESP # 2 inlet flue gas 1200 x 1200 FG-DMP-202 Manual Isolation

28 ESP # 1 outlet flue gas 1550 x 1784 FG-DMP-203 Manual Isolation

29 ESP # 2 outlet flue gas 1550 x 1784 FG-DMP-204 Manual Isolation


TITLE : WATER STEAM CIRCUIT

C2 - 0 - 0 – 0

WATER STEAM CIRCUIT



C2.0.0.0 NATURAL CIRCULATION STEAM GENERATION

C2.1.0.0 Natural Circulation Steam Generation

Feed water from feed pump is supplied to economiser I via feed control

station where piping and valves layout is such that alternative/ facility (with

proper isolation) is available to allow feed water through main line (100%), or

its by pass or low feed line or its by pass. Economiser I is located in upper

portion of Pass II and interconnecting piping takes feed water to inlet header

of economiser II in upper portion of combustor. Drum receives feed water

from Economiser II. Drum is connected to bottom headers of combustor via

downcomers and supply pipes for feeding water. The furnace walls headers

located in upper portion of combustor convey mixture of steam and water to

drum through riser tubes.

Initially water is filled upto drum and thus entire water circuit is filled with

water. Water level in the drum is kept approximately 100 mm below NWL

prior to lighting up of boiler. Soon after boiler is lit up, furnace walls,

economiser etc start heat absorption and heat up water in system. The water

becomes lighter. In the other words, difference in density gives rise to

circulation of water in the entire system. As the water in furnace walls rises,

its place is taken by denser/colder water from downcomers. Thus natural

circulation is established and continues.

As the water - steam mixture flowing upwards through furnace tubes, top water

wall headers and risers enters the drum, separation of steam from water takes

place.

Steam from upper portion of drum flows to saturation steam header

located slightly above the steam drum.



Steam then flows through Superheater I, Superheater II and Superheater III

absorbing the heat from outgoing flue gases of combustor.

The water separated from water-steam mixture obviously mixes with water in

lower portion of drum and process of natural circulation continues.

Feed water regulating system ensures water in the integral parts and

maintains desired water level in the drum. There is no circulation of water in

the absence of density variation caused by heat absorption.

C2.2.0.0 SCREEN

Screen coils are placed above the free board and below Superheater coils to

have more heating surface and proper heat balance. Inlet header is provided

for feeding water to these screen tubes. Water is fed to this inlet header from

drum. The outlet tubes of screen form the support tubes on which

superheater, evaporator and economiser II coils rest and maintain proper

distance (Pitch) between them. Water flows upwards in evaporator and flue

gases also flow upwards. In the other words it is parallel flow of flue gas and

water.

C2.3.0.0 EVAPORATOR

These coils are placed above superheater section. Feed water from drum

enters at inlet header of evaporator. Mixture of water and steam proceeds to

drum via evaporator outlet header



C2.4.0.0 ECONOMISER I

In economiser I, flue gases from cyclones flow downwards towards air heater

whereas the feed water moves upwards. The economiser coils are suspended

from steel structure.

C2.5.0.0 ECONOMISER II.

The flue gases flow upwards through gaps between economiser II coils. The

water also moves upwards to economiser outlet header. Feed water flows from

economiser II outlet header to drum through nozzles with thermal sleeves.

Inside the steam drum, perforated feed pipes ensure even distribution of feed

water.

C2.6.0.0 FURNACE

Rear wall forms the roof of furnace. Right, left and front sides of rectangular

furnace have virtually upright walls. Riser tubes carry water steam mixture to

drum and impact deflection plate inside the drum separates the steam from

water. Saturated steam tubes, evenly spaced along the length of drum,

ensures uniform steam conveyance to saturated steam header and from here,

the steam goes to Superheater I inlet header through connecting pipe.



C2.7.0.0 SUPERHEATERS

Superheaters are so arranged in the first pass that fairly flat characteristic is

ensured. Also, the steam velocities and internal heat transfer are such that

even on partial load, the metal temperature of all Superheaters are well within

the acceptable limits. Constant Superheater outlet steam temperature from

60% MCR onwards can be maintained by cooling the steam by the two spray

attemperators placed between Superheater-I and Superheater – II and

Superheater – II and Superheater – III respectively.

The saturated steam extracted evenly along the whole length of the drum flows

via connecting pipes to the Superheater – I bank, which is arranged on the flue

gas side in the counter flow.

After superheater I there is spray-type attemperator I followed by superheater

II which is similarly arranged on the flue gas side in the parallel flow for

regulating the superheater outlet temperature. Attemperator – II is placed

between SH-II Outlet header and SH- III Inlet Header. This attemperator is

used to adjust the Final SH Steam temperature so that the temperature can be

maintained at a constant set point. SH – III bank tubes are also arranged in

the flue gas path above SH – II bank tubes in parallel flow.

Final steam at around temperature of 535ºC & pressure of 96kg/cm²(g) is fed

via a pipe into the steam mains and supplied to the users. (Turbine alternator

set or process).

A main steam stop valve with bye pass as well as non-return valves, are

located close to SH III outlet header.

The steam generator is fitted with a safety valve system and electrically

operated start up vent valve.



C2.8.0.0. ATTEMPERATORS :

Under even and good combustion conditions, the level of the steam

temperature changes with the boiler load. Additional influences on the final

superheated steam temperature amongst others, from varying fuel

compositions, oscillations in the excess air and alternating fouling of the

heating surfaces are a common experience.

Maintaining the superheated steam temperature is therefore only possible by

using auxiliary equipment. This is the reason why attemperators are arranged

between the individual superheater sections. By spraying in water, they keep

the steam at a reasonably constant temperature.



WATER AND STEAM CIRCUIT



BASIC CIRCUIT DIAGRAM NATURAL CIRCULATION TYPE STEAM GENERATOR


TITLE : STRUCTURAL DESIGN AND SPECIAL FEATURES

C3 - 0 - 0 – 0

STRUCTURAL DESIGN AND SPECIAL FEATURES



C3.1.0.0 SUSPENSION SYSTEM

The entire boiler load of the Ist pass, the 2nd pass to the expansion joint and

the cyclone is taken up by the suspension beams at the top of boiler structure.

Cup springs are provided on four water cooled walls of combustor (Ist pass).

Pre-compressed cup springs to installation load adequately accommodate the

sagging of main suspension beams due to static loads, any possible fouling of

Ist pass water walls, superheaters, Economiser II and evaporators.

2nd pass is separated from first pass by using expansion joints. Entire air

heater (tubular type) is supported on Boiler Steel Structural members.

Besides, fouling is not expected in view of relatively low temperature of flue

gases. Cup springs are therefore not deemed necessary in the second pass

with smooth plain sheet casing.

Over 70% of supporting tubes used to position superheater and economiser

coils in Ist pass do not need any special springs due to insignificant differential

expansion between water wall and roof. The vertical water walls of the 1st

pass and the smooth plate casing of the 2nd pass are able to take up the

entire load without any additional reinforcement.

C3.2.0.0 CYCLONES

The theoretical fixed point for the vertical expansion is at the centre of the cyclones

for the horizontal expansion. Expansion joints, at the connecting ducts of the boiler

passes, accommodate any difference in expansion, between the cyclones and the Ist

and 2nd passes.



C3.3.0.0 2ND PASS

The 2nd pass consists of 2 parts (economiser upper section and tubular air

heater lower section) separated by means of expansion joints to accommodate

thermal expansion. Whilst the economiser II (convection pass) is hung from

the boiler roof, the tubular air heater is propped up in the steel support

structure.

The 2nd pass tubular air heaters are each propped up in the support structure

by means of sliding bearings, permitting of horizontal thermal expansion. The

course of thermal expansion in each instance is upwards to the expansion

joint.

Airheater is comprised of four banks of primary air and four banks of

secondary air. Steel structure supports upper and lower sections separately.

However, metallic expansion joints interposed between them, accommodates

thermal expansion.

For all parts of the 2nd pass, the theoretical fixed point for the horizontal

expansion is at the centre of the 2nd pass front wall. The lateral expansion of

air heater is therefore sideways and towards rear side.



C3.4.0.0 SPECIAL FEATURES OF DESIGN - IST PASS

The boiler body is constructed in self-supporting manner without any support

from constant hangers. This avoids any compressive strains in the walls.

For taking up the gas-side pressures and any explosion forces arising, the

boiler is provided with buckstays following the course of vertical expansion.

Clamping angles connect the buckstays with the channel secured on the

walls. The clamping angles permit a horizontal differential expansion

between the buckstays and the channels fixed to the wall. However, they

transfer forces acting on the attendant wall to the buckstays and direct these

same forces via corner connections to the adjacent walls.

The entire boiler 1st pass is designed to attain fully leak proof arrangement for

flue gas. All bank heating surfaces, at the wall penetrations are welded

directly into the membrane wall using protection sleeves. All the other wall

penetrations are sealed off on the flue gas side by employing sheet metal

cases or fillers.

Lowest tubes of Superheater I, Superheater II, Superheater III, Screen and

Economiser II are fitted with stainless steel flats - known as "armour". Similar

arrangement is given to top tubes of Economiser I. This prevents erosion of

tubes facing flue. Gas diversion plate assemblies are fixed to furnace walls in

spaces between screen, superheaters, evaporator and economiser II. This

minimises the "stack effects" or erosion due to continuous ash mass flow

through spaces between furnace wall and ends of heating surfaces. Similar

arrangement of gas diversion plate is on the top side of economiser I.



In order to minimise the difference in thermal expansion between combustor

water walls and evaporator/ superheater / economiser II coils, the latter is

supported from support tubes. The headers and the interconnecting pipes of

superheater/ economiser II are supported from combustor walls.

Buckstays are used at various levels with corner connections as well as

anchor points for more rigidity against bowing due to suction or pressurisation

of furnace.

Wind box or air box form the bottom portion of combustor. It is also a

membrane construction having top portion fitted with primary air nozzles

(made of high temperature resistant cast steel) for fluidising the bed comprised

of ash, coal and limestone mixture effectively. Hot gas generator is connected

to air box.

The lower section of the combustor water walls is provided with "SIC"

refractory. This is done for 3 reasons :

a. To prevent erosion damage, due to the circulating fluidised bed.

b. Regulating heat transfer.

c. Preventing damage at the evaporator tubes due to the sub-

stoichiometrical mode of operation in the lower section of the evaporator.

Low cement castable refractory is also applied on all combustor walls just

above "SIC" and below screen tubes for technical reasons similar to

application of "SIC".

Roots blower supplies air through nozzles located inside siphon for fluidising

the ash coming from cyclones and pushing it into the bed through coal chutes.



Drop pipe with one end approximately 50 mm above the top of primary air

nozzle, passing through air box and terminating (with expansion joint) on the

underside of air box is used for draining bed ash occasionally. There is of

course proper sealing with air box at entry and exit points.

C3.5.0.0 SPECIAL FEATURES OF DESIGN - 2ND PASS

In view of the lower flue gas temperature at economiser I inlet, unlike furnace

water-cooled walls, plain casing suffices to enclose economiser I. Tubular

slings are used to suspend economiser I coils from roof.

The cyclones are of a self-supporting plate constructional design complete with

wear protection. Expansion joints offset any difference in expansion between

the two boiler passes.

Ash laden flue gas enters from combustor exit into cyclones. The raw gas

passes via the raw gas duct into the raw gas spiral. At this entry, the flue gas

is centrifugally deflected. Due to the centrifugal forces the ash particles are

flung out from the gas flow towards shell of cyclone

They overcome the flow resistance, which is caused by the sinking flow to the

immersion pipe inlet. At the cyclone shell, the ash moves downwards into the

stand pipes and finally in the siphon. The clean gases leave the cyclone via a

centrally arranged immersion pipe. The cyclone does not require special

maintenance. During long outages ash deposits should be removed.



Technical data (per cyclone) :

Boilers Load Unit

Fuel - Coal 30% MCR 100% MCR

Gas mass flow at inlet Kg/sec 7.0 23

Gas temperature at inlet Deg.C 300 440

Inlet dust loading Kg/NM3 2.4 2.4

Draft loss MMWC 13 130



CYCLONE


TITLE : COMBUSTION - AIR FLUE GAS SYSTEMS

C4 - 0 - 0 – 0

COMBUSTION - AIR FLUE GAS SYSTEMS



C4.0.0.0 COMBUSTION AIR FLUE GAS SYSTEMS

C4.1.0.0 AIR PATH

The entire combustion air comprises of

- Ignition air for burners of the hot gas generators.

- Primary air

- Dilution air (through hot gas generators)

- Secondary air

- Tertiary air

The combustion air required for the fluidised bed combustion is admitted from

primary air fans and secondary air fans, and supplied to the furnace. The air-

flow is adjusted to the respective requirement through radial vane control

(RVC) at the fan suction.

Individual suction ducts of both primary and secondary air direct the fresh air

to the respective fans. The flow off ducts, come to a junction on discharge

side before entering air pre-heater.

Air flows through the tubular air heater in 4 stages on the primary, secondary

and tertiary air side and is heated in the cross flow pattern. After the tubular

air heater, primary air bifurcates in two branches for two hot gas generators.

Further split up into combustion air, dilution air and HGG bypass is arranged

in the vicinity of the individual hot gas generator. The primary air is blown into

the fluidized bed via the P.A. nozzles. Generally, primary air is routed

through combustion air, dilution air during cold start up and then switch over

to HGG by-pass path.



Secondary air is further split into secondary and tertiary air ducts with

isolation/control dampers after air pre-heater. The secondary air is injected

into the boiler by means of 16 nozzles located above the fluidised bed. The

tertiary air is supplied to the boiler through 16 nozzles, located above the

secondary air nozzles.

This staged combustion air supply and low combustion temperature are

responsible for largely preventing the formation of thermal NOx.

To the extent that they are required, access doors and various pressure and

temperature & flow monitoring points are provided over the entire primary and

secondary/tertiary air path.

C4.2.0.0 FLUE GAS PATH

The flue gas-side pressure in the freeboard, above the fluidised bed is around

- 30 mmwg. From here, the fly ash charged flue gases from combustion are

conveyed to induced-draught fan. In the first boiler pass flue gas passes over

screen, the final-stage, superheater (SH3), superheater (SH2), superheater

(SH1), evaporator and Eco 2 reaching the 2nd boiler pass via cyclone

separators. The cyclone separator recirculate the ash discharged from the

fluidised bed a number of times. Approximately 95% of the ash contained in

the flue gases is being separated in the cyclones.

In the second boiler pass, the flue gases first flow through Eco 1 and then the

tubular air heater. The primary air and secondary/tertiary air is heated here.



On leaving the tubular air heater the flue gases, now only charged with

extremely fine dust, reach electrostatic percipitator where, depending on the

dust load, their dust is precipitated.

The induced-draft fan directs the flue gas coming from the electrostatic

precipitator to the stack.

The damper control at the suction of the induced-draft fan adjusts the flue gas

flow/furnace pressure to the respective requirements. Adequate

inspection/access doors and various pressure and temperature monitoring

points are provided over the whole of the flue gas path.


TITLE : COAL FEEDING SYSTEM

C5 - 0 - 0 – 0

COAL FEEDING SYSTEM


TITLE : COAL FEEDING SYSTEM

C5.1.0.0 COAL FEEDING SYSTEM

Internal coal feeding system in the scope of TKIIPL starts, with two rod type

cut off gates fitted just below the bunkers of 700 mt3 capacity for continuous

feeding of coal to boiler. Plate type cut off gate each 2050mm x 750 mm is

located below the rod type cut off gate for isolation purpose. This ensures a

flooded section of coal at the entry to both coal feeders fitted under the

isolation gates.

The coal feeders are equipped with chain tension adjusting arrangement, no

coal flow alarm, chain scrapping arrangement, and coal bed height adjustment.

The last of these is of manual type and for the purpose of commissioning. The

electric prime mover drives the coal feeder with variable speed control through

gearbox and chain drive.

Downstream end of coal feeder is feeding the coal straight into "Y" piece fitted

under the siphon. Here also, plate type electrically operated cut off gates are

interposed.

Emergency gates 600mm x 600mm provided on each coal feeder chutes fixed

on underside of each coal feeder facilitates loading on transport truck directly.

Provision of "on line" sampling of coal/lignite is also available.


TITLE : ASH HANDLING SYSTEM

C6 - 0 - 0 – 0

ASH HANDLING SYSTEM



C6.0.0.0 ASH HANDLING SYSTEM

C6.1.0.0 REQUIREMENTS ON THE ASH HANDLING SYSTEM

In contrast to ash handling systems in conventional power plants the ash

conveying system in fluidised bed boilers has - apart from performing removal

functions - to meet boiler-specific requirements. These include:

a) At all boiler loads the corresponding ash quantities in the fluidised bed

must be capable of being maintained between two limit values, i.e. it

must be possible to remove the oversize portion of the fuel ash not

elutriated with the flue gas from the fluidised bed. The control criteria

are the pressure drops through the fluidised bed between the air

distribution grid and freeboard; this ash handling system is described in

the following under the heading "Bed Ash Handling System".

b) It must be possible to reduce the circulating cyclone ash flow via a lock

facility. In practice, this means that the cyclone ash collecting efficiency

can be adjusted to the varying ash quantities and properties of the fuel

range.

The system should be capable of varying the recirculating ash for regulating

the bed temperature. Portion of the ash separated in cyclones, therefore has

to be extracted, cooled and transported to storage silos.

These ash handling systems are explained in the following under the

headings "Cyclone Ash Circulation and Cyclone Ash Extraction".



C6.2.0.0 BED ASH HANDLING SYSTEM

The bed ash handling system is designed for intermittent operation. In the

process, the bed ash is drained from the fluidised bed through two drain

pipes.

The two bed ash drain systems, are shut off by pneumatically operated gates,

directly below the wind box.

The expansion joints below the cut off gates are designed to accommodate

total downward thermal expansion of furnace.

Below each bed ash discharge pipe, a cooling screw cooler serving as

discharge device is arranged. In the water-cooled screw cooler, the bed ash

is cooled down from about 850°C to about 300°C. The screw coolers are

provided with variable speed drives. The speed variation is based on the feed

back signal from bed ash level.

Note:

Dismantling of the bed ash system is only allowed during boiler downtime.

Since hot ash may be in the drain pipes, between fluidised bed bottom and

cut off gates, utmost care and caution should be exercised.



C6.3.0.0 CYCLONE ASH CIRCULATION

The cyclone ash circulation system comprises the path of the cyclone ash

through the first pass of the steam generator, through the cyclones and via

siphons back to the fluidised bed. The cyclone ash separated from the flue

gas in the cyclones flows downwards by gravity through vertical gravity pipes

to the siphons.

A siphon is assigned to each cyclone separator. The function of the siphon is

to isolate the area of the fluidised bed under positive pressure from the

negative pressure area of the cyclones.

To ensure optimum ash flow through the siphon, fluidising air from the roots

blowers (air blowers) is admitted to the siphons. The air flow is adjusted to

the operating conditions prevailing in each case via the variable speed of the

roots blowers. The cyclone ash passes from the outlet of the siphon into the

mixing chamber.

The area of the cyclone outlet up to and including the mixing chamber is

provided with a heat insulation for 4500C and the coal / ash pipes downstream

of the siphons up to the inlet of the steam generator with a heat insulation for

about 6000C.

C6.4.0.0 CYCLONE ASH EXTRACTION

To control the fluidised bed temperature the mass flow of the circulating

cyclone ash has to be changed. For this purpose cyclone ash can be

extracted from two loop seals. To lower the fluidised bed temperature the

extraction quantity is reduced; to raise the temperature the extraction flow is

increased.


birla copper part 1

Documents

combustion process

friendly system of firing

cfbc firing system b1

ash removal

combustion air supply

esp ash

circofluid system

high ash load