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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
Thermodynamic Analyses-EnergyThermodynamic Analyses-Energy14
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
Thermodynamic Analyses-EnergyThermodynamic Analyses-Energy15
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
Thermodynamic Analyses-EnergyThermodynamic Analyses-Energy16
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
Parameter Unit Value
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
Results & DiscussionsResults & Discussions21
Base case performance of the plant
Parameter Unit Value
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
Results & DiscussionsResults & Discussions22
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)
Topping cycle pressure ratio
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.
Results & DiscussionsResults & Discussions23
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)
Topping cycle pressure ratio
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)
Topping cycle pressure ratio
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.
Results & DiscussionsResults & Discussions24
Percentage of valve opening to CHX
Turbine Inlet Temperature (0C)
Percentage of valve opening (%)
900 58
1000 75
1100 97
Results & DiscussionsResults & Discussions25
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
Results & DiscussionsResults & Discussions26
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]