Modelling & Experimental Study of Biomass Gasifier For
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Transcript of Modelling & Experimental Study of Biomass Gasifier For
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MODELLING & EXPERIMENTAL
STUDY OF BIOMASS GASIFIERFOR ELECTRIC POWER
APPLICATION
By-
Tarun Kumar (MEB11034)
Ankur Gupta (MEB11040)
Avinash K. Singh (MEB11044)
Project Supervisor-
Partha Pratim Dutta
Assistant Professor
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INTRODUCTION Biomass is biological material derived from living organisms. It most
often refers to plants or plant-based materials.
As an energy source, biomass can either be used directly viacombustion to produce heat, or indirectly after converting it tovarious forms of biofuel.
Wood remains the largest biomass energy source to date.
Gasification is a process that converts organic or fossilfuel based carbonaceous materials into carbonmonoxide, hydrogen ,carbon dioxide, methane and rest is Nitrogenin limited supply of air.
The resulting gas mixture is called syngas (from synthesis gas orsynthetic gas) or producer gas and is itself a fuel.
The power derived from gasification and combustion of the
resultant gas is considered to be a source of renewable energy if thegasified compounds were obtained from biomass.
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Objective of study
Theoretical study of biomass gasification.
Experimental study of biomass gasification
for electrical application
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DOWNDRAFT BIOMASS GASIFIER
Sectional view
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Experimental Setup
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Literature Review
Equivalence ratio ()
=(Flow rate of air supply)(Duration of the run)
(Mass input of wood)(A/F for = 1)
(A/F) for = 1 is 5.22 m3of air/kg of wood.
The equivalence ratio for the gasifier was found to be inthe range 0.2680.43, which was within the range for
ideal and theoretical gasification (0.190.43).
The average gas composition is:
1.69% O2, 43.62% N2,
14.05% H2, 24.04% CO,
14.66% CO2, 2.02% CH4
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Variation of percentage of
oxygen with equivalence ratio[1]
Variation of percentage ofnitrogen with equivalenceratio[1]
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Variation of percentage of
hydrogen with equivalence ratio
[1]
Variation of percentage of CO
with equivalence ratio [1]
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Variation of percentage of carbon
dioxide with equivalence ratio. [1]Variation of percentage of methanewith equivalence ratio [1]
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Variation of caloric value withequivalence ratio [1]
Variation of gas production ratewith equivalence ratio [1]
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Variation of gas production rate per unit weight of the
fuel with equivalence ratio [1]
Therefore the optimum equivalence ratio for the best
performance of downdraft biomass gasifier is 0.388
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The above experimental analysis and research
led to the following results-
Overall efficiency = 11.15 % (average)
Maximum efficiency = 15.46 %
Specific consumption of biomass material = 1.98
kg/kWh Minimum consumptions of biomass material = 1.49
kg/kWh
Carbon content in ash is about 10% of carboncontent in feed at optimum equivalence ratio.
Minimum carbon content at optimum equivalence
ratio
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Steps of GASIFICATION
Drying (the moisture content of biomass we will usewill be 15%-20%)
Pyrolysis
Gasification
Combustion
BIOMASS to be used by us are---
1) Jack Fruit (Artocarpus heterophyllus)wood
2) Mango Tree (Mangifera indica) wood3) Drumstick (Moringa Oleifera) wood
4) Ashok tree (Polyalthia Longifera) wood
5) Jamun (Syzygium cumini) wood
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MATHEMATICAL MODELLING [2]
The main gasification reaction is
n
H2)
H
2
+ n
CO)
CO + n
CO2)
CO
2
+ n
H2O)
H
2
O + n
CH4)
CH
4
+
z/2+3.76m)N
2
All inputs on the left-hand side of the eq. are
defined at 25C. On the right-hand side, niis thenumber of moles of the species i which areunknown.
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Molar quantity of water per one kmol of biomass
can be written as
w = M
bm
x MC
M
H2O
x 1-MC)
where MC is moisture content
Mbmandare the masses of biomass and
water.
Air/fuel ratio can be calculated as +0.25-0.5)
for a fuel with a chemical formula of CHON.
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The following simplified Chemical formulas describe the basic
gasification process :
1) Boudouard reaction : C + CO2 2CO
2) Water-gas reaction : C+H2OCO + H2
3)Hydrogenating gasification : C + 2H2CH4 (+75 KJ/mol)
4)Water-gas shift : CO+H2OCO2+H2 (+41.2 KJ/mol)5)Steam reforming : CH4+ H2OCO+3H2
Water gas shift reaction together with hydrogenating
gasification is chosen to play the role of two
independent equations.
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These equations with their equilibrium constants generate
two of five equations required to obtain the five unknown
species of the produced syngas (H2, CO, CO2, H2O, and CH4).
The remaining three equations are formulated by balancing
each chemical element consisting of carbon, hydrogen and
oxygen.
where R is universal gas constant
GT is the standard Gibbs function of formation
Fi ll t
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Finally we get
dt + I
where hfis the enthalpy/heat of formation
ALSO
where I is constant of integration
J is a const.
A, B, C and D are the coefficients for determining the
specific heats.
Having known the I and J constants together with hfandG, theequilibrium constant (k) can be determined.
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For instance, the equilibrium constant for water-gas shift
reaction is obtained as follows:
If the temperature in the Gasification Zone is T and the inlet state
is
assumed to be 298 K , the enthalpy balance for this process can bewritten as
nj ( h
f,j+
hT,j) =
nj ( h
f,i+
h
T,i)where h
T
represents the enthalpy difference between any given
state and reference state.
j= react i= prod
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When the equilibrium constants are defined, a system of
non linear equations are obtained which can be solved by
NewtonRaphson method together with convergencestrategies.
The equations are solved with the use of iterative
methods.
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References http://www.sciencedirect.com/science/article/pii/S0961953
402000594
[1] Zainal, Z.A,Rifau, Ali, Quadir, G.A , Seetharamu, K.N.
Experimental investigation of a downdraft biomass gasifier ,
Biomass and Bioenergy 23(4) ,2002
profdoc.um.ac.ir/articles/a/1008098.pdf
[2] Vaezi,M. ,Passandideh-Fard,M. ,Moghiman ,M. ,Charmchi,
M. MODELING BIOMASS GASIFICATION:A NEW APPROACH
TO UTILIZE RENEWABLE SOURCES OF ENERGY , Energy, 2008
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THANK YOU