a verification on design performance of 300mw class … · a verification on design performance of...

KEPRI, Plug-in Future

A Verification on Design Performance

of 300MW Class CFB Boiler

Jae-Sung Kim, Jong-Min Lee, Dong-Won Kim

October 29, 2010

Korea Electric Power Research Institute

1


Contents

1. Introduction of the 300MW class CFB boiler design

2. Steam & design coal conditions

3. Heat and mass balance calculations

4. Calculation results

5. Summary

2


Motivation and Objectives

1. First construction of 340MW Yeosu CFB boiler in Korea

2. Necessity of a verification on the boiler design & performance

3. Evaluation of design & performance characteristics of the CFB boiler

4. Development of heat & mass balance calculation modules

• As a reverse engineering

3


Introduction of the 300MW class CFB Boiler design

4


Boiler outline

SCR

AH EP

5


FurnaceHeight : 41,500

Width : 34,010

Depth : 8,138

Bed Depth : 4,069

Cyclone Height(長) : 26,031

Cyclone Height(短): 16,055

Cyclone Diameter : 6,854

Return leg : 561 + 561

Side view

Plane view

Evap. Division wall : 2

Total Wing Wall : 31

Evap. WW : 4

SH WW : 27

Rear view

Cyclone: 4

Return leg: 4

6


Furnace, Division Wall, Wing Wall

FurnaceHeight : 42m

Width : 34m

Depth : 8.1m

Bed Depth : 4.1m

Wing WallSuperheater

Height : 21m

Depth : 2.5m

Pitch : 1.1m

Number : 27

Wing WallEvaporator

Height : 23m

Depth : 2.7m

Pitch : 1.1m

Number : 4

Division WallEvaporator

Height : 35m

Depth : 3.5m

Number : 2

3.5m

35m

23m

2.7m2.5m

21

m

42m

8.1m

4.1m

6m

34m

8.1m

7


Cyclone arrangement

34m

8.13m

8.06m

1.37m 7.45m 7.45m1.43m

8


Cyclone specification

2808

2808

2600

2704

3224

2600

4828

1210

1825

R3382

10401

4100

7446

30845

12901

16055

60˚

9


Distributor

124.8mm

124.8mm

176mm

Φ42.2mm180mm

100mm

Fluidized bed

Grid Nozzle Arrangement Grid Nozzle

ⅹ32 ⅹ31

ⅹ95 ⅹ95

4.1m

34m

Ash Drain

10


Return Leg

40˚

561561

10401

4100

7446

30845

11


Furnace model

12


Steam & design coal conditions

13


Water/steam circuitry

Furnace Walls

(Division Wall

Evaporator)

Drum

Cyclone Crossover

duct

Convection

cage

SH Ⅰ WW

SHⅡWW

SHⅢ

RHⅡ

RH Ⅰ

Economizer Ⅱ

Feed tank

HP-HeatersFeed Water Pump

Economizer Ⅰ

T(℃)

P(kg/cm2g)

358.2

184.9

366.1

184.6

368.8

182.9

376.4

178.6

385.8

174.9

453.0

172.9

541.0

171.5

308.5

32.33

419.5

30.87

541.0

30.26

229.1

191.3

256.3

190.4

358.3

187.5

303.6

187.5

In Furnace

14


Steam conditions

Steam condition BMCR MGR NR 75%MGR 50%MGR 30%MGR

SH outlet steam flow

1,000kg/hr1,025 1,025 1,005.3 884.1 672.2 499.8

SH outlet steam

temperature, ℃541 541 541 541 541 541

SH outlet steam pressure,

kg/cm2g171.5 171 171 169 167.3 166.3

RH outlet steam flow

1,000kg/hr821.5 800.3 799.8 592.5 412.2 263

RH outlet steam

Temperature, ℃541 541 541 541 532 526

RH steam pressure

kg/cm2g33 32.2 32.2 23.6 16.1 9.9

Final Feedwater

temperature, ℃229.1 228.3 228.2 212.5 194.6 174.2

15


Design coal analysis

Proximate Analysis(Air dry Basis)

Design Coal

RangeCoal

Moisture(%,wt) 15.3 22.0

Volatile matter(%,wt) 40.5 17.0

Fixed Carbon(%,wt) 41.7 67.3

Ash(%,wt) 2.5 1.6~18.7

Ultimate Analysis(Air Dry Basis)

Design Coal

Carbon(%,wt) 69.8

Hydrogen(%,wt) 4.9

Nitrogen(%,wt) 1.0

Sulfur(%,wt) 0.3

Oxygen(%,wt) 21.0

Ash(%,wt) 3.0

TGA

0 200 400 600 800 1000

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

M/M

oTemperature(

oC)

Subbituminous

Bituminous

Anthracite

Design Coal

16


Schematic diagram of supplied fuel & air

Upper lever SA

22 nozzles

Lower level SA

26 nozzles

×3× 3

× 4

Coal silo

A

Limestone silo

Coal silo

B

Bed

Material

Make up

Primary

Air Fans

Secondary

Air Fans

Fluidizing

Air Blowers

17


Conditions of supplied fuel & air

BMCR MGR 75%MGR 50%MGR 30%MGR

Coal

(t/h)162 159 139 108 83

Limestone

(t/h)5.58 5.43 4.53 2.71 2.75

Excess air 1.2 1.2 1.2 1.3 2

Primary air

(t/h)704 695 607 608 604

Secondary air

(t/h)564 554 482 313 480

2ndary air

ratio0.44 0.44 0.44 0.34 0.44

18


Heat and mass balance calculations

19


Methods of heat and mass balance calculation

Combustion calculations

Selection of calculations conditions

Basic equation of heat balance

Calculation of enthalpy of gas phase

Input and Output in a furnace

Heat balance equations in a furnace

Calculation of flue gas temperature

20


Flue gas composition

BMCR NR MGR 75%MGR 50%MGR 30%MGR

Excess air(%) 20 20 20 20 30 100

CO2(volume %) 14.35 14.35 14.35 14.35 13.32 8.95

O2(volume %) 3.12 3.12 3.12 3.12 4.35 9.72

N2(volume %) 70.69 70.69 70.69 70.69 71.22 73.40

SO2(volume %) 0.0245 0.0245 0.0245 0.0245 0.0228 0.0153

H2O(volume %) 11.84 11.84 11.84 11.84 11.11 7.93

21


Selections of calculation conditions

Item unit Symbol On literature Selection

Excess air - αfu 1.1~1.2 1.2

Primary air ratio % x 50~75 56

Dense zone combustion rate - δ 0.75~0.85 0.75

Chemical incomplete combustion loss

% q3 0~1 0.5

Unburned carbon loss % q4 2~6 6

Carbon contents of fly ash % Cf,a <10 8

王敦恩 et al., “工业锅炉设计计算方法”, 中国标准出版社, 200522


Basic equation of heat balance

Simple heat balance equation

Determination of control volume Every heat exchanger had a control volume except of a furnace

Furnace was divided into a dense zone and a dilute zone

abs in outQ Q Q

Control Volume

Qin(Total heat input)

Qout(Enthalpy of flue gases

leaving the control volume)

Qabs (Total heat absorbed in a control volume)

Prabir Basu, Cen Kefa, Louis Jestin, “Boiler and Burners”, Springer-Verlag New York, 200023


Enthalpy calculation of gas phase Enthalpy of flue gas or supplied air

Polynomial expression of Specific heat

Gas species a b c d

(1) CO2 22.26 0.05981 -0.00003501 7.469E-09

(2) H2O 32.24 0.001923 0.00001055 -3.595E-09

(3) SO2 25.78 0.05795 -0.00003182 8.612E-09

(4) O2 25.48 0.0152 -0.000007155 1.312E-09

(5) Ar 20.92 0.05981 -0.00003501 7.469E-09

(6) N2 28.9 -0.001571 0.000008081 -2.873E-09

(7) CO 28.16 0.001675 0.000005372 -2.222E-09

(8) Air 28.11 0.001967 0.000004802 -1.966E-09

0,

1

N Ti

gas p iT

i total

mI C dT

m

2 3

pC a bT cT dT

Calculation of enthalpy of gas phase

Yunus A. Cengel and Michael A. Boles, “Thermodynamics - An Engineering Approach, Fifth Edition in SI Unit”, McGraw-Hill, 200624


Input and Output in a furnace

Recycled solid,Flue gas of Dense phase

Fuel, Recycled solid,Primary air

Recycled solid,Flue gas

2ndary air

Total heat input(Qi)Sensible heat of primary air(xαIai)

Enthalpy of recycled solid(Irs)

Enthalpy of gas & solid leaving the dense zone(Ido)

Heat absorbed in dense zone(Qm)

Sensible heat of 2ndary air(1-x)αIai

Heat absorbed in dilute zone(Qw)

Enthalpy of flue gas and solid(Ife)

Dilute zone

Dense zone

程乐鸣, 岑可法, 倪明江, 骆仲泱, “循环流化床锅炉炉膛热力计算”,中国电机工程学报, Vol.22 No.12 Dec. 200225


Heat balance equations in a furnace

Total heat input(Qi)Sensible heat of primary air(xαIai)

Enthalpy of recycled solid(Irs)

Enthalpy of gas & solid leaving the dense zone(Ido)

Heat absorbed in dense zone(Qm)

Sensible heat of 2ndary air(1-x)αfuIai

Heat absorbed in dilute zone(Qw)

Enthalpy of flue gas and solid(Ife)

Dilute zone

Dense zone

程乐鸣, 岑可法, 倪明江, 骆仲泱, “循环流化床锅炉炉膛热力计算”,中国电机工程学报, Vol.22 No.12 Dec. 2002

w dilute feQ Q I

m dense doQ Q I

Heat input into Dilute zone(Qdilute)

(1 ) (1 )dilute do i fu airQ I Q x I

dense i fu air rsQ Q x I I

Heat input into Dense zone(Qdense)

26


• Assumption of exit gas temperature

• Heat transfer calculation

– Difference between heat input and output

• Calculation of temperature

– with polynomial expression of specific

heat

• Iteration until the same of previous

exit gas temperature

Calculation of exit gas temperature

27


Results

Furnace

Wing Wall Superheater

Cyclone, Cross over duct, Convection cage

Backpass – Reheater , Primary Superheater

Backpass – Economizer

28


Furnace heat & mass balance

Separation between Dense zone and Dilute zone

Assumption of combustion rate, unburned carbon, heat transfer

Dense Zone

INPUT

Heating value of coal [kW] 583685

Sensible heat of coal [kW] 1728

Sensible heat of primary air [kW] 50232

Total heat input [kW] 635645

OUTPUT

Unburned carbon loss [kW] 1206

Sensible heat of ash [kW] 533

Moisture heat loss [kW] 5054

Sensible heat of dense zone exit gas [kW] 628852

Total heat output [kW] 635645

Dilute Zone

INPUT

Sensible heat of dense zone exit gas [kW] 628852

Heating value of coal [kW] 389123

Sensible heat of 2ndary air [kW] 42744

Total heat input [kW] 1060719

OUTPUT

Moisture heat loss in 2ndary air [kW] 3961

Chemical incomplete combustion loss [kW] 2280

Heat transfer [kW] 595000

Sensible heat of flue gas [kW] 459477

Total heat output [kW] 1060719

Furnace exit gas temperature [℃] 871

29


Wing wall superheater

Furnace(Wing Wall) Secondary Superheater

Inlet gas temperature ℃ 871 Operation condition

Out gas temperature ℃ 871 Operation condition

Flue gas flow rate Nm3/h 2,494 Imported(Proximate)

Inlet steam temperature ℃ 386 Operation condition

Enthalpy of inlet steam kJ/kg 2,851 Steam Table

Outlet steam temperature ℃ 471 Operation condition

Enthalpy of outlet steam kJ/kg 3,193 Steam Table

Steam flow rate kg/h 1,025,000 Operation condition

Heat duty in secondary superheater kJ/h 350,750,366

Furnace(Wing Wall) Final Superheater



Flue gas flow rate Nm3/h 1,127,870 Imported(Proximate)






Heat duty in final superheater kJ/h 277,178,818

30


Cyclone, Cross Over Duct, Convection Cage

Cyclone









Heat duty in cyclone kJ/h 77,914,450

Cross over duct


Out gas temperautre ℃ 825 Operation condition







Heat duty in COD superheater kJ/h 22,847,510

Convection cage









Heat duty in CC kJ/h 54,876,047

31


Backpass - RH, SH

Final ReheaterInlet gas temperature ℃ 777 Operation condition







Steam flow rate kg/h 821,500 Operation condition

Heat duty in final Reheater kJ/h 322,858,983

Primary ReheaterInlet gas temperature ℃ 642 Operation condition







Steam flow rate kg/h 821,500

Heat duty in primary reheater kJ/h 326,281,726

Primary SuperheaterInlet gas temperature ℃ 513 Operation condition


Flue gas flow rate Nm3/h 3,016 Imported(Proximate)





Steam flow rate kg/h 1,025,000

Heat duty in primary superheater kJ/h 35,971,046

32


Backpass - Economizer

Secondary Economizer




Inlet water temperature ℃ 256 Operation condition


Outlet water temperature ℃ 304 Operation condition



Heat duty in Secondary Eco kJ/h 255,875,764

Primary Economizer




Inlet water temperature ℃ 229 Operation condition

Enthalpy of inlet steam kJ/kg 989 Steam Table

Outlet water temperature ℃ 256 Operation condition



Heat duty in Primary Economizer kJ/h 135,505,607

33


Heat calculation results

Heat duty

Heat transfer

Comparison of temperature between design value and calculation

34


Heat duty calculation from steam condition

Using an overall heat transfer coefficient(U) with Log Mean Temperature Difference(∆LMTD)

Q=UA∆LMTD

Heat duty and Heat transfer calculations

Unit furnace2ry

SH

Final

SHcyclone

Cross

over duct

Convectio

n cage

Final

RH

Primary

RH

Primary

SH2ry Eco

Primary

Eco

Inlet gas temperature ℃ 871 871 871 871 853 825 777 642 513 450 344

Outlet gas temperature ℃ 871 871 871 853 825 777 642 513 450 344 269

Inlet water/steam temp. ℃ 303 386 453 358 366 369 420 309 376 256 229

Enthalpy kJ/kg 1352 2851 3133 2642 2718 2741 3273 3010 2794 1116 989

Outlet water/steam temp. ℃ 358 471 541 366 369 376 541 420 392 304 256

Enthalpy kJ/kg 2642 3193 3403 2718 2741 2794 3547 3273 2883 1355 1115

LMTD ℃ 541 443 374 500 471 428 203 188 92 98 47

Heat duty kW 367399 97431 76994 21643 6347 15243 62485 60211 25144 68218 35980

Heat absorbtion GJ/h 1160 368 292 148 38 85 234 229 103 184 127

Heat absorbtion Gcal/h 278 88 70 35 9 20 56 55 25 44 31

Heat absorbtion rate kcal/m2h 58753 61917 53722 17147 9515 20228 10708 9145 4931 6778 3489

Calculated area m2 4723 1423 1301 2059 956 1004 5230 5992 4989 6477 8742

Heat transfer coefficient W/m2K 144 155 158 21 14 36 59 53 55 108 88

35


Heat duty and Heat transfer

0

50

100

150

200

250

300

350

400 Heat Duty(MW)

0

20

40

60

80

100

120

140

160

180 Heat transfer

coefficient(W/m2K)

36


Comparison of temperature

0

100

200

300

400

500

600

700

800

900

1000

Furnace Cyclone Convection cage

Final RH Primary RH Primary SH 2ndary Eco. Primary Eco.

AH ˚C

Calculation

Design value

Furnace Furnace CycloneConvection

cageFinal RH Primary RH Primary SH 2ndary Eco. Primary Eco. AH

Calculation 871 855 786 654 520 459 349 270 136

Design value 871 853 777 642 513 450 344 269 141

Δt 0 +2 +9 +12 +7 +9 +5 +1 -5

37


Summary

1. Get the Input conditions from Technical Specification (Performance & Technical Data) and drawing

2. Establishing Heat balance equation of each control volume

3. Calculating heat and mass balance

4. Acquiring results of heat transfer coefficients, heat duty, exit gas temperature and so on

38


39

a verification on design performance of 300mw class … · a verification on design performance of...

Documents