234 pradip

Presented By: P MondalPhD Scholar

Co-author: Dr. S GhoshAssociate Professor

BENGAL ENGINEERING & SCIENCE UNIVERSITY, SHIBPURDEPARTMENT OF MECHANICAL ENGINEERINGHOWRAH-711103, W.B.

IV th International Conference on Advances in Energy Research

Overview

Introduction and perspective

Schematic of the proposed plant

Model development

Results and discussions

Conclusions

INTRODUCTION

AND

PERSPECTIVE

Introduction-Present Energy Introduction-Present Energy ScenarioScenario

4

Energy consumptions in the Asian developing countries are increasing rapidly.

Indian power sector is strongly dependent on the fossil fuels.

Reserve of fossil fuels are getting depleted day-to-day. Burning of fossils fuels is a major source of greenhouse gas

emissions. Need to pay more attention towards the development of

reliable, economic and environment friendly technologies in converting the renewable energy resources in useful work.

Introduction-Biomass & Bio-Introduction-Biomass & Bio-energyenergy

5

Biomass has a very high potential as renewable energy source in rural India.

Total projected capacity of production/reserve is about 889.71 Million Tones for the year 2010.

Solid biomass is converted into combustible synthetic gas through it’s gasification.

Major components of synthetic gas are CH4, H2, CO, CO2, H2O and N2.

Overall efficiency of power production from biomass can be increased to 35-40% using gas turbine-steam turbine (GT-ST) combined cycle integrating a gasifier in the system.

Introduction-Directly Heated GT Introduction-Directly Heated GT CycleCycle

6

Tar and Moisture

Particulate Matter

Sulphur Content

Corrosion , Erosion and Deposition on the turbine bladings

Lower in longevity of the GT

Problems

Introduction-Indirectly Heated GT Introduction-Indirectly Heated GT CycleCycle

7

No need of cooling arrangements

GT bladings are safe from corrosion and erosion

GT bladings are safe from particulate deposition

Long , Economic and Reliable Operation

Solutions

Operates on low cost and dirt fuels

LAYOUT OF THE PROPOSED

PLANT

9

Pel = 30.00 kW

3535

3434

3333

3232

31313030

2929

2828

2727

2626

2525

24242323

2222

2121

2020

1919

1818

1717

1616

1515

1414

1313

1212

11111010

99

88

77

66

55

44

33

22

11

28

27

26

H

25

24

23

22

2120

19

18

17

16

15

H

14

13

H

12

11

10

9

8

H

7

6

H

5

43

2

1

Economizer

Evaporator

Superheater

Steam Turbine Block

Indirectly Heated Gas Turbine Block

Combustor-Heat Exchanger Block

Air Gasifiication Block

Wood Based Indirectly Heated Combined Cycle Plant

MODEL DEVELOPMENT

Model DevelopmentModel Development11

Characteristics of fuel used:

Parameter Unit Value

Ultimate Analysis Mass percentage on wet basis

C % 50

H % 6

O % 44

LHV (MJ/kg) MJ/kg 16.3

Moisture % 7.2

Model DevelopmentModel Development12

Assumptions in the present study:

Post combustion temperature is limited to a value about 13000C.

The plant component operates at steady state.

No pressure and heat loss is assumed for the tubing and heat exchangers.

The compression and expansion processes are adiabatic (isentropic efficiencies of

90% for topping compressor and gas turbine, while the value is 85% for bottoming

steam turbine).

The inlet steam condition is 10 bar, 3500C. The condenser pressure is 0.1 bar.

For the HRSG, minimum pinch point temperature difference is set to150C. The

stack temperature is 1200C.

Thermodynamic Analyses-EnergyThermodynamic Analyses-Energy13

Gasifier Unit:Gasification reaction:

Water gas shift reaction and methane reaction:

Gasification efficiency:

Assumptions: Tar formation is not considered in this model.

The bed temperature of the gasifier is set to 8000C and the oxidant (air)/biomass ratio xOF is 1.8

2 2 1 2 2 3 2 4 2 5 4 6 2( 3.76 ) a bCH O m O N X H X CO X CO X H O X CH X N

2 2 2

2 42

CO H O CO H

C H CH

gasi p.g p.g

biomass biomass

m LHV

m LHV


CHX unit:

Combustion equation:

Post combustion temperature:

Heat exchanging:

Where Xg represents the number of moles of hot exhaust gases leaving the combustor

1 2 2 3 2 4 2 5 4 6 2 2 2

7 2 8 2 6 2 9 2

( 3.76 )

( 3.76 )

X H X CO X CO X H O X CH X N m O N

X CO X H O X m N X O

( ) ( ) ( ) o o oj fj producergas j fj air j fj fluegas

j j jX h h X h h X h h

'. .4.76 ( ) ( ) air g f g mm h X h

6 7 8 9 3.76 gX X X X X m


Combined cycle unit:

Compressor:

Gas turbine:

Net GT output:

Gas mixture:

Steam generation rate:

. , . . , f g m p f g m sm C T m h

c p,a c,o c,iw = c (T -T )

GT p,a GT,i GT,ow c (T -T )

G( ) net GT cw w w

f.g,m f a

f p, f a p,a f.g,m p, f.g,m

m = m +m

m c ΔT +m c ΔT = m c ΔT


Steam turbine:

Pump:

Net combined output:

First law efficiency:

GST ST,i ST,ow (h - h )

pp p,o p,iw = (h - h )

G( ) ( ) net GT c ST pw w w w w

netCC

biomass biomass

wη =

m LHV

Thermodynamic Analyses-ExergyThermodynamic Analyses-Exergy17

Thermo-mechanical exergy:

Where,

Fuel exergy:

Where multiplication factor-β ,

fuel biomass biomassEx =m LHV β

i i o o i oe = (h - h )-T (s - s )

i

o

i

o

T

i o pT

Ti

i o pT

o

h - h = c dT

PdTs - s = c - Rln

T P

H O H1.044+0.0160 -0.34493 (1+0.0531 )

C C Cβ =O

1-0.4124C

Thermodynamic Analyses-ExergyThermodynamic Analyses-Exergy18

Specific chemical exergy of producer gas :

Exergetic efficiency:

Where ,

2

4

1

1 2 3 4 5 6

2

1 2 3 4 5 6

5

1 2 3 4 5 6

ch chbiomass H

chCO

chCH

Xe e

X X X X X X

Xe

X X X X X X

Xe

X X X X X X

outexergetic

in

Exn Ex

( ) ( ) in i in i inEx Ex W

( ) ( ) out i out i outEx Ex W

RESULTS AND DISCUSSIONS

Results & DiscussionsResults & Discussions20

Product gas composition of the gasifier


Gas Composition( mole fraction)

H2 % 20.88

CO % 26.78

CO2 % 6.88

N2 % 40.03

CH4 % 0.3

H2O % 4.92

Oxidant-fuel ratio (xOF) - 1.8

LHV of product gas mixture MJ/kg 5.44

Gasification efficiency % 80.45


Base case performance of the plant


Biomass flow rate kg/hr 23.4

Topping cycle pressure ratio - 4

GT inlet temperature 0C 1000

GT cycle output kW 30

Percentage of valve opening to CHX % 75

ST cycle output kW 15.56

Combined work output kW 45.56

Plant efficiency % 37.383


4 6 8 10 12 14 1635.0

35.5

36.0

36.5

37.0

37.5

38.0

38.5

39.0

TIT=9000C

TIT=10000C

TIT=11000C

Pla

nt e

ffici

ency

(%

)

Topping cycle pressure ratio

2 4 6 8 10 12 14 1613.0

13.5

14.0

14.5

15.0

15.5

16.0

16.5

17.0

Ste

am tu

rbin

e el

ectr

ical

out

put (

kW)


TIT=9000C

TIT=10000C

TIT=11000C

Fig: Variation of plant efficiency with GT block pressure ratio.

Fig: Variation of steam turbine electrical output with GT block pressure ratio.


4 6 8 10 12 14 1610

12

14

16

18

20

22

24

GT

cyc

le s

pece

fic a

ir flo

w b

y m

ass

(kg/

kWh)


TIT=9000C

TIT=10000C

TIT=11000C

2 4 6 8 10 12 14 162

4

6

8

10

12

14

16

18

20

CH

X (

tube

sid

e) s

pece

fic a

ir flo

w b

y vo

lum

e (m

3/k

Wh)


TIT=9000C

TIT=10000C

TIT=11000C

Fig: Variation of CHX (tube side) specific air flow by volume with pressure ratio.

Fig: Variation of specific air flow by mass with pressure ratio.


Percentage of valve opening to CHX

Turbine Inlet Temperature (0C)

Percentage of valve opening (%)

900 58

1000 75

1100 97


35.86%

4.22%

7.72%

6.62%

3.92%

1.35%

3.43%

17.84%

19.04%

CHX Gasifier Condenser Compressor Stack GT &ST HRSG Auxaliaries Useful

Fig: Component exergy loss and useful exergy of the plant at TIT=10000C.

1 2 3 40

20

40

60

80

100

120

Exe

rge

tic e

ffici

en

cy (

%)

TIT=9000C

TIT=10000C

TIT=11000C


1: CHX 2: Gasifier 3: HRSG 4: GT & ST

Fig: Exergetic efficiency of the plant components at different TIT’s.

CONCLUSIONS

ConclusionsConclusions28

Thermodynamic analyses of a novel configuration (biomass based indirectly heated combined cycle ) has been carried out in this paper.The efficiency of the proposed plant attains a maximum at particular pressure ratio range (6-9) and individual turbine inlet temperature (TIT).For a particular pressure ratio the efficiency value increases at higher TIT.Size of the topping cycle components as well as CHX unit decreases as pressure ratio increases at individual TIT. Also the size of the said units are getting lowered at higher TIT’s

ConclusionsConclusions29

Major exergy losses occur at the gasifier, CHX unit, GT & ST unit and HRSG unit for the plant.

Exergy loss for the other plant components are insignificant.

The exergetic efficiency of the gasifier and the CHX unit are lower than that of other plant components due to the chemical reactions takes place at the said units.

The exergy efficiency value of CHX unit is above 90% for the plant at higher TIT.

ReferencesReferences30

1. Syred C., Fick W., Griffiths A.J., Syred N. (2000) Cyclone gasifier and cycle combustor for the use of biomass derived gas in the operation of a small gas turbine in co-generation plant, Fuel, 83, pp. 2381-2392. 2. Cycle-Tempo Software, (2012) Release 5 (TU Delft) (Website: http://www.cycle-tempo.nl/.)3. Datta A., Ganguli R., Sarkar L. (2010) Energy and exergy analyses of an externally fired gas turbine (egft), cycle integrated with biomass gasifier for distributed power generation, Energy, 35, pp. 341-350.4. Vera D., Jurado F., Mena de B., Schories G. (2011) Comparison between externally fired gas turbine and gasifier-gas turbine system for the olive oil industry, Energy, 36, pp. 6720-6730.5. Barman N.S., Ghosh S., De S. (2012) Gasification of biomass in a fixed bed downdraft gasifier-A realistic model including tar, Bioresource Technology, 107, pp. 505-511.6. Ghosh S., De S. (2004) First and second law performance variations of coal gasification fuel-cell based combined cogeneration plant with varying load, Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, pp. 477-485.

ReferencesReferences31

7. Roy P.C. (2013) Role of biomass energy for sustainable development of rural India: case studies, International Journal of Emerging Technology and Advanced Engineering, Special Issue 3, ICERTSD 2013, pp. 577-582. 8. Energy Statistics (2012, Nineteenth Issue), Ministry of Statistics and Programme Implementation, Govt. of India, 2012 (Website: http://mospi.nic.in/Mospi_New/site/home.aspx).9. Datta A., Mondal S., Dutta Gupta S. (2008) Perspective for the direct firing of biomass as a supplementary fuel in combined cycle power plants, International Journal of Energy Research, 32, pp. 1241-1257.10. Soltani S., Mahamoudi S.M.S., Yari M., Rosen M.A. (2013) Thermodynamic analyses of an externally fired gas turbine combined cycle integrated with biomass gasification plant, Energy Conversion and Management, 70, pp. 107-115.11. Fracnco A., Giannini N. (2005) Perspective for the use of biomass as a fuel in combined cycle power plants, International Journal of Thermal Sciences, 44, pp.163-177.12. Bhattacharya A., Manna D., Paul B., Datta A. (2011) Biomass integrated gasification combined cycle power generation with supplementary biomass firing: Energy and exergy based performance analysis, Energy, 36, pp. 2599-2610.

Pradip MondalPhD Scholar

Dept of Mechanical EngineeringBengal Engineering and Science University, Shibpur

Howrah-711103, West Bengale-mail: [email protected]