CHAPTER ONE
INTRODUCTION
Most of the rural Indian families
depend heavily on biomass to meet their household cooking energy requirements. Fuel
wood often accounts for a major fraction of the total biomass use. Fuel wood is
generally preferred to non-wood biomass residues due to its higher energy
density and convenience in use and transportation. Large quantities of biomass
residues are available in India. These include rice husk, rice straw, wheat
straw, corncob, coconut shell, bagasse, and many other agricultural residues.
The residues are normally difficult to use, particularly in small-scale
systems, due to their uneven and troublesome characteristics. Although biomass
offers itself as a sustainable and carbon-neutral source of energy, its
inefficient use in household cooking results in wastage, indoor air pollution
and related respiratory and other health problems. Excessive use of fuel wood
is also exerting pressure on the region’s forest cover. Although large quantities
of surplus biomass residues are available in India, due to certain difficulties
experienced in using them in the traditional cooking devices, their use has
been severely restricted. The non-availability of suitable cost-effective
technologies for utilizing biomass residues for household cooking has resulted
in gross under utilization and neglect of biomass residues as a potential
energy source in this sector.
However, energy from biomass can be efficiently
used by means of gasifier stoves. Many different types of gasifier stoves have
been designed and constructed so far and they are showing good performance too.
Wood
gas cook stove developed by Thomas Reed and Ron Larson[1], Charcoal making wood
gas cook stove developed by Elsen Carstad[2], IISc gasifier stove by Indian
Institute Of Science[3], San San rice husk gasifier stove developed by U Tin
Win[4] and many others have led to an efficient harnessing of biomass energy.
Gasification is the process that
converts carbonaceous materials such as coal, petroleum, biofuel, or biomass
into carbon monoxide and hydrogen by reacting the raw materials, such as house
waste, or compost at high temperatures with a controlled amount of oxygen and/or
steam. The resulting gas mixture is called synthesis gas or syngas and is
itself a fuel. Gasification is a method for extraction of energy from many
different types of organic materials.
Pyrolysis is a form of
incineration that chemically decomposes organic materials by heat in the
absence of oxygen. Pyrolysis typically occurs under pressure and at operating
temperatures above 430 °C (800 °F). In practice, it is not possible to achieve
a completely oxygen-free atmosphere. As some oxygen is present in any pyrolysis
system, a small amount of oxidation occurs. The word is coined from the Greek-
derived elements, pyre meaning “fire” and lysis meaning “loosening”.
1.1 Biomass as
an energy source for cooking in Asia:
Domestic cooking accounts for the
major share of the total biomass use for energy in Asia. However, use of
biomass fuels in traditional stoves is characterised by low efficiency and
emission of pollutants. In an effort to address these problems, many of the
Asian countries have initiated national programs to promote improved cook
stoves. Although significant achievements have been reported in some of these
countries, the potential for further efficiency improvements is still very
large. A study by Bhattacharya et al[7] estimated that the biomass saving potential
in seven Asian countries (China, India, Pakistan, Nepal, Philippines, Sri Lanka
and Vietnam) as 152 million tons of fuel wood and 101 million tons of
agricultural residues, in the domestic cooking sector alone in early nineties.
The amount of biomass that can be saved through efficiency improvement can
serve as a source of additional energy and can potentially substitute for
fossil fuels to reduce net GHG emission. With the escalating costs of fossil
fuels and gas as a preferred cooking fuel (than fuel wood, residues, kerosene
etc.), biomass gasifiers are attracting renewed interest. The possibilities for
biomass gasification technology for cooking applications are leading to a
number of initiatives to demonstrate the potential benefits of introducing them
in developing countries. Wider use of the gasifiers stoves in developing
countries could save on cooking fuel costs, improve the reliability of fuel
supply by making rural communities more self-reliant and improve indoor air
quality. Gasifier-based cooking systems have some very attractive features,
i.e., high efficiency, smoke free clean combustion, uniform and steady flame,
ease of flame control, and possible attention-free operation over extended
duration. While these make them an attractive choice in the kitchens of the
developing world, there are cost and technology barriers which limit their
wider adoption.
1.2 Difference between gasifier stoves
and conventional stoves:
Apart
from being fuel efficient, gasifier stoves are also emission efficient in
comparison to traditional cook stoves. The traditional cook stoves, because of
their very low efficiency, emit more than 10% of their carbon as products of
incomplete combustion (PIC) comprising varying amount of tars. In addition,
about 100-180 g of carbon monoxide and 7.7 g of particulate matter are also
emitted per kg of wood. Gases such as methane, total non-methane organic
compounds (TNMOC) and N2 O are added to this. These PIC emissions
are even higher in the case of loose biomass or cow dung used as fuel in these
stoves. Some of the natural draft stoves (based on combustion of gas produced
from biomass) developed so far are listed in Table 1. The capacity of these
stoves ranges from 3kWth to 20kWth, making them suitable for domestic as well
as community cooking applications. Compared to the 5-15% efficiency of
traditional cook stoves in the Asian region, the efficiency of these gasifier
stoves is in the range of 25-35%.
1.3 History:
The
gasification process was originally developed in the 1800s to produce town gas
for lighting and cooking. Electricity and natural gas later replaced town gas
for these applications, but the gasification process has been utilized for the
production of synthetic chemicals and fuels since the 1920s. Wood gas
generators, called Gasogene or Gazogène, were used to power motor
vehicles in Europe during World War II fuel shortages.
Four
types of gasifier are currently available for commercial use:
1.3.1. The counter-current fixed bed ("up draft") gasifier: It consists of a fixed bed
of carbonaceous fuel (e.g. coal or biomass) through which the
"gasification agent" (steam, oxygen and/or air) flows in
counter-current configuration. The ash is either removed dry or as a slag. The
slagging gasifiers have a lower ratio of steam to carbon , achieving temperatures higher than the ash
fusion temperature. The nature of the gasifier means that the fuel must have
high mechanical strength and must ideally be non-caking so that it will form a
permeable bed, although recent developments have reduced these restrictions to
some extent. The throughput for this type of gasifier is relatively low.
Thermal efficiency is high as the gas exit temperatures are relatively low.
However, this means that tar and methane production is significant at typical
operation temperatures, so product gas must be extensively cleaned before use.
The tar can be recycled to the reactor.
1.3.2. The co-current fixed bed ("down draft") gasifier: It is similar to the counter-current type,
but the gasification agent gas flows in co-current configuration with the fuel
(downwards, hence the name "down draft gasifier"). Heat needs to be
added to the upper part of the bed, either by combusting small amounts of the
fuel or from external heat sources. The produced gas leaves the gasifier at a
high temperature, and most of this heat is often transferred to the
gasification agent added in the top of the bed, resulting in energy efficiency
on level with the counter-current type. Since all tars must pass through a hot
bed of char in this configuration, tar levels are much lower than the
counter-current type.
1.3.3. The fluidized bed reactor: Here, the fuel
is fluidized in oxygen and steam or air. The ash is removed dry or as heavy
agglomerates that defluidize. The temperatures are relatively low in dry ash
gasifiers, so the fuel must be highly reactive; low-grade coals are
particularly suitable. The agglomerating gasifiers have slightly higher
temperatures, and are suitable for higher rank coals. Fuel throughput is higher
than for the fixed bed, but not as high as for the entrained flow gasifier. The
conversion efficiency can be rather low due to elutriation of carbonaceous
material. Recycle or subsequent combustion of solids can be used to increase
conversion. Fluidized bed gasifiers are most useful for fuels that form highly
corrosive ash that would damage the walls of slagging gasifiers. Biomass fuels
generally contain high levels of corrosive ash.
1.3.4. The entrained flow gasifier: Here, a
dry pulverized solid, an atomized liquid fuel or a fuel slurry is gasified with
oxygen (much less frequent: air) in co-current flow. The gasification reactions
take place in a dense cloud of very fine particles. Most coals are suitable for
this type of gasifier because of the high operating temperatures and because
the coal particles are well separated from one another. The high temperatures
and pressures also mean that a higher throughput can be achieved; however
thermal efficiency is somewhat lower as the gas must be cooled before it can be
cleaned with existing technology. The high temperatures also mean that tar and
methane are not present in the product gas; however the oxygen requirement is
higher than for the other types of gasifiers. All entrained flow gasifiers
remove the major part of the ash as a slag as the operating temperature is well
above the ash fusion temperature. A smaller fraction of the ash is produced
either as a very fine dry fly ash or as a black colored fly ash slurry. Some
fuels, in particular certain types of biomasses, can form slag that is
corrosive for ceramic inner walls that serve to protect the gasifier outer
wall. However some entrained bed type of gasifiers do not possess a ceramic
inner wall but have an inner water or steam cooled wall covered with partially
solidified slag. These types of gasifiers do not suffer from corrosive slags.
Some fuels have ashes with very high ash fusion temperatures. In this case
mostly limestone is mixed with the fuel prior to gasification. Addition of a
little limestone will usually suffice for the lowering the fusion temperatures.
The fuel particles must be much smaller than for other types of gasifiers. This
means the fuel must be pulverized, which requires somewhat more energy than for
the other types of gasifiers.
1.4. Natural vs Forced convection
1.4.1.
Natural convection: provides poor mixing of air with fuel
gases and can result in incomplete combustion, soot and emissions in open wood
stoves. A chimney can supply 1 mm water pressure per meter of height. Addition
of a chimney for cooking can greatly improve wood combustion in closed models,
but also adds complication and requires wasting heat to operate[7].
1.4.2.
Forced convection: provides good mixing and combustion for
gas cooking and is widely used in homes and camping stoves. The 3 W blower used
in the Turbo Stove provides 7.5 mm water pressure and makes clean cooking
possible[7].
CHAPTER TWO
OBJECTIVE
AND SCOPE
2.1. Objective
of the work
The basic aim of
the project is to design a gas stove working on biomass energy for domestic use
that is cheaper, cleaner and more efficient than the conventional cooking
methods used in rural areas. Therefore the objectives of our work are:
2.1.1.
To design a gasifier stove for domestic purpose.
2.1.2.
To construct the stove using locally available materials.
2.1.3.
To carries out experimentations to evaluate the performance of the stove.
2.2. Scope
2.2.1. Study of existing designs of producer gas stoves.
2.2.2. Carry out comparison of different existing designs.
2.2.3. Selection of a particular design and carry out study for
modifications of the design to fit into our local conditions.
2.2.4. Selection of locally available cheap materials for practical
implementation of the design.
2.2.5. Construction of the designed gas stove.
2.2.6. Experimentation to evaluate efficiency of the stove.
CHAPTER
THREE
METHODOLOGY
3.1. Chemistry
of Gasification
In
a gasifier, the carbonaceous material undergoes several different processes:
1.
The pyrolysis (or de-volatilization) process occurs as the carbonaceous
particle heats up. Volatiles are released and char is produced, resulting in up
to 70% weight loss for coal. The process is
Figure 3.1: Pyrolysis of carbonaceous fuel
Figure 3.2: Gasification of char
dependent
on the properties of the carbonaceous material and determines the structure and
composition of the char, which will then undergo gasification reactions.
2.
The combustion process occurs as the volatile products and some of the
char reacts with oxygen to form carbon dioxide and carbon monoxide, which
provides heat for the subsequent gasification reactions. Letting C represent
a carbon-containing organic compound, the basic reaction here is
C
+ 1/2O2 = CO2
3.
The gasification process occurs as the char reacts with carbon dioxide
and steam to produce carbon monoxide and hydrogen, via the reaction,
C + H2O = H2 + CO
4. In addition, the reversible gas phase water
gas shift reaction reaches equilibrium very fast at the temperatures in a
gasifier. This balances the concentrations of carbon monoxide, steam, carbon
dioxide and hydrogen.
H2O + CO = CO2 + H2
In essence, a limited amount of oxygen or air
is introduced into the reactor to allow some of the organic material to be
"burned" to produce carbon monoxide and energy, which drives a second
reaction that converts further organic material to hydrogen and additional
carbon dioxide. Further reactions occur when the formed carbon monoxide and
residual water from the organic material react to form methane and excess
carbon dioxide. This third reaction occurs more abundantly in reactors that
increase the residence time of the reactive gases and organic materials, as
well as heat and pressure. Catalysts are used in more sophisticated reactors to
improve reaction rates, thus moving the system closer to the reaction
equilibrium for a fixed residence time.
Gasifier-based
cooking systems have some very attractive features, i.e., high efficiency,
smoke free clean combustion, uniform and steady flame, ease of flame control,
and possible attention-free operation over extended duration. While these make
them an attractive choice in the kitchens of the developing world, there are
cost and technology barriers which limit their wider adoption.
3.2. Safety Measures to follow:
Producer gas was the only gas fuel
widely available until 1940 when natural gas pipelines became common. Since
producer gas contains 10-30% CO, it is a real health hazard if the flame is
extinguished or incomplete combustion occurs [8]. (Smoky open fires and
insufficient cooking fuel are also major health hazards in the world today.)
Therefore it is necessary to mandate good practice in using the Producer Gas
Stove. In the volatile combustion mode CO is a minor hazard because if the
flame should go out, the copious smoke warns the operator to re-ignite the fire
or move the stove outside. However, in the charcoal combustion mode the CO is
odorless and could pose a health hazard. It is recommended that all stoves
including the Producer Gas Stove should be operated under a hood carrying the
cooking odors and possible stove emissions to the outside by natural or forced
convection. That is the practice in most kitchens in developing countries today
and should be followed as the rest of the world develops.
3.3.
Producer Gas Stove Emissions:
Producer-gas cooking has very low
emissions and can be operated indoors with proper precautions once established
[9]. However, if the fire is extinguished for any reason the production of
smoke and CO continues, so that it is important to be able to extinguish it
completely or take
it
outside. The stove is difficult to extinguish but can be done by closing the
primary air supply at the bottom and outer cylinder side. During gasification
of wood, if the fire is extinguished the acrid tars in the wood make it
unlikely that one would breathe too much CO. However, after the wood is
gasified the stove contains hot charcoal and so can be a major source of CO.
For this reason it is important to either continue to burn the charcoal or to
cut off all air to the stove.
3.4. Study of existing stoves and search
for a suitable design:
i.
The Wood-Gas Cook Stove of Reed and Larson
use small wood chips and sticks for operation, and produce very low CO
emission, and hence suitable for indoor cooking. The rate of gas production can
be controlled by controlling the primary air supply to the gasifier. The
gasifier produces charcoal as a by-product [1].
Figure 3.3: Wood-Gas Cook Stove developed by Reed and Larson
ii.
Elsen Karstad’s Charcoal Making Wood Gas
Cooking Stove is a simple stove developed for the East African households [2].
Figure 3.4: Elsen Karstad's Charcoal Making Wood-Gas
Cook Stove
iii.
The Holey Briquette Gasifier Stove
developed by Stanley and Venter (2003) operates using a single biomass
briquette with a central hole (typically produced in extrusion type briquetting
machines) placed in the middle of the combustion/gasification chamber. At about
1.1 kW power, the stove offers efficiency of up to 35%[5].
PROTOTYPE OF BRIQUETTE GASIFYING STOVE
Figure 3.5: Holey Briquette
Gasifier Stove developed by Stanley and Venter
(1.1kW power; 35% efficiency).
iv. The IISc Gasifier
Stove can be operated using small wood sticks and pelletised waste, and has a
thermal output of 3-4 kW. Offering a water-boiling efficiency of 25-35%, the
stove can operate continuously for about 2 hours for a single fuel loading.
Emission from the stove has been found to be low[3] .
Figure 3.6: IISc’s Gasifier Stove
v.
The San San Rice husk Gasifier Stove
developed in Myanmar offers smokeless combustion ofrice husk in an efficient
manner. Gasification can be improved by mixing kitchen wastes suchas potato
peels, green leaves and fresh biomass, chopped into half inch pieces, with the
rice husk[4].
Figure 3.7: San San rice husk gasifier stove
developed in Myanmar
vi.
The three models of gasifier stoves developed
at AIT (Institutional Gasifier Stove/IGS2, Domestic Gasifier Stove/DGS2 and
Commercial Gasifier Stove/CGS3) operate on cross-draft principle, using wood
chips, wood twigs, coconut shells and ricehusk/sawdust briquettes as fuel
(Figures 6 and 7). Water-boiling efficiency is in the range of 22-31%,
depending on the type of stove and fuel used. Combustion is clean and steady,
and no tending is generally required during operation[6].
Figure 3.8: Institutional Gasifier Stove
IGS2 Figure 3.9: Commercial Gasifier Stove CGS3
developed at AIT
developed at AIT
(5.5 kW; 29% efficiency with
woodchips) (11.5 kW; 31% efficiency with
woodchips)
vii. Wood gas stove developed by College of
Engineering and Technology, Maharana Pratap University of Agriculture and Technology,
Udaipur, Rajasthan India, which has a capacity of 5 kw and works on natural
draft gasification mode[7].
Figure 3.10: Wood gas stove.
3.5. Methodology of production of our design:
Modification of presently available stoves
We
have designed a producer gas stove working on natural draft + inverted
downdraft gasification mode. For our design we took references from the
following natural draft gasifier stoves developed.
i.
Primary
air mechanism: primary air is the air which is
utilized in the initial burning of the biomass fed to the stove. Instead of
providing separate inlets for air and fuel feed, we have used a sliding door
for both entry of primary air as well as feeding biomass. Amount of air can be
controlled by sliding the door.
ii.
Ash
removal mechanism: a separate hollow
cylindrical shell is fitted at the bottom of the stove. The ash produced due to
the burning of biomass falls from the grate and gets collected in this shell.
The shell can be removed to discard the wastes and then refitted to the stove
easily for use again.
iii.
Secondary
air control: this is the air which helps in
the proper burning of the producer gas generated in the stove thereby producing
the flame. Minute holes along the periphery of the top part of the cylinder are
provided for the purpose.
iv.
Producer
gas outlet: very small holes, about seven to eight
in number, are provided at the top of the small cylinder over the main reactor
of the stove for the producer gas to come out and get burned to produce the
flame.
v.
Calculation
of critical radius of insulation: This is
calculated with the knowledge of thermal conductivity of fire clay brick(k),
the convective heat transfer coefficient between air and fire clay brick(h) and
finally applying the formula to calculate critical radius of insulation(rc);
which is, rc=k/h. Now the radius of insulation provided in the stove
must be greater than the critical value so as to minimize heat loss to the
surrounding. By Studying all the above stoves we have designed a producer gas
stove which works on the natural draft gasification mode and the design is
prepared considering the availability of the materials.
rc
= 1/8 = .125m = 12.5cm
where,
k = 1W/mK , h = 8W/m2K
By
Studying all the above stoves we have designed a producer gas stove which works
on the natural draft gasification mode and the design is prepared considering
the availability of materials and fuels in rural areas.
Figure 3.11: Solid works design of the producer gas
stove.
3.6. Construction:
·
Construction
of the stove have been done using
locally available materials which are listed below
|
Serial No.
|
Part of stove
|
Material used
|
|
1.
2.
3.
4.
5.
6.
7.
8.
|
Reactor Core
Grate
Insulation
Reactor outer cover
Biomass feeding door cum primary air
inlet
Removable portion at the bottom
Upper portion for combustion of the
producer gas
Tripod stand
|
Galvanized Steel
Galvanized Steel
Normal Crushed Brick
Galvanized Steel
Galvanized Steel
Galvanized Steel
Galvanized Steel
Mild Steel flattened bar
|
Table 3.1
The whole unit has been constructed in our college
workshop. The various shop we used for construction are Fitting shop, Welding
Shop, Carpentry Shop, Blacksmith Shop etc.
3.6.1. Construction Procedure:
·
Construction of the
Reactor Core: A
hollow galvanized steel cylinder of diameter 21cm, height 44cm having a grate
inside and a feed door on the body forms the main reactor core inside which
pyrolysis leading to the formation of producer gas takes place.
Figure 3.12: Reactor
core
· a) Construction of the
Grate: it is made by cutting a number of longitudinal slots on a galvanized
steel plate having diameter same as that of the internal diameter of the
reactor core. It is then welded at a suitable height above the bottom of the
core.
Figure 3.13: Grate
· b) Cutting primary air
inlet cum fuel feeding door on the reactor core the door dimensions (8×12cm)
are first marked on the body of the core on the outside and carefully cut out using
a chisel and hammer.
Figure 3.14: Primary
Inlet
· d) Preparation of
insulating material: A stainless steel sheet having lap joint surrounds the
core. The space between the core and the stainless steel cylinder is filled
completely with crushed normal brick which acts as a very good insulating
material.
· e) Construction of Reactor
Outer Cover: A stainless steel sheet is bent in the form of a cylinder and is
fixed by lap joints having a diameter of 38 cm.
Figure 3.15: Insulation
cover
·
Construction of upper portion
of the Reactor: A small cylinder of diameter 10.16cm of galvanized
steel is welded to the top of the core and there are holes on the top sheet for
the gas to come out.
Figure 3.16: Reactor
upper potion
· g) Construction of lower
portion of the Reactor: a circular sheet of the same material as the core is
slide fitted at the bottom for removal of ash that falls from the grate fitted
above.
· h) The tripod stand has
been constructed using MS flattened bars and it is basically for holding the
pot during cooking.
· i) Assembly: All the above
mentioned parts are assembled to get the stove. Below is the Stove with
different parts of it.
3.6.2. Structural Modification of the Design:
After construction of
the stove, we tried to fire it by feeding dry wood and coke but due to
deficiency in our design it did not work as expected. Therefore the seven
semester design has been modified in the present semester by consulting our
guide, and the whole modified design with its mechanisms is given below.
Figure 3.17: Modified Design
3.6.3.
Construction of modified design:
- The number of secondary
inlet holes has been increased for better generation of the cooking flame.
- The holes in the top portion
of the stove have been replaced by a LPG burner for getting a uniform and intense flame.
CHAPTER FOUR
EXPERIMENTATION
4.1.
Experimental set-up and procedure
The
efficiency of a stove is usually defined as the ratio of heat transferred to
the cooking medium to heat supplied by fuel. The stove efficiency could be
evaluated by a number of standard methods such as Constant Heat Output Method,
Constant Temperature Rise Method, Constant Time Method, and [10]Water Boiling
Test (Prasad and Verhaart, 1983). Of these, the Water Boiling Test appears to
be most commonly used and this very test method is used in the performance
evaluation of our producer gas stove as well. The test is designed as a simple
method with which stoves made in different places and for different cooking
applications can be compared through a standardized and replicable test.
However,
the WBT also has weaknesses. In order to be applicable to many different types
of stoves, the WBT is only a rough approximation of actual cooking. Therefore,
the efficiency of the stove as found out by WBT will vary when the stove will
be subjected to real cooking.
In
a Water Boiling Test, a known quantity of water is heated on the cookstove. No
lid is used to cover the vessel so that evaporated water freely escapes from
the vessel. The quantity of water evaporated after complete burning of the fuel
is determined. Also the quantity of fuel burnt is found out by measuring the
amount of fuel left unburnt inside the reactor core.
4.1.1. Apparatus
for water boiling test:
1. A pan without lid.
2. Thermometer for measuring the ambient and
boiling
water temperature.
3. A balance for measuring the weight of fuel,
water
and pan.
4.1.2. Procedure
The
fuel and pan to be used in the test were separately weighed. The pan was
partially filled up with water and weighed again. The initial temperature of
water was recorded. The stove was ignited to initiate heating of the pan. After
letting the heating process to continue for about one hour and thirty minutes the
burning coal in the reactor core was put off and the process of heating was
thus terminated. The unburnt fuel, i.e., unburnt wood pieces were taken out and
weighed in order to find out the amount of fuel actually exhausted during the
test. The temperature to which water was heated was also recorded. The
calorific value of dry wood was taken from standard table.
All
these values are then put in the formula shown above in order to find out the
efficiency of the stove. The efficiency thus found out was the theoretical
efficiency of the designed stove. However, the actual performance of the stove
may vary to some extent when used for real cooking.
The
efficiency of the stove is calculated by using the following formula:
where,
mw,i
= initial mass of water in the cooking vessel, kg
=6 kg
cp,w
= specific heat of the water, kJ/kg°C
=4.2 KJ/ kg °C
mw,evap
= mass of water evaporated, kg
=0.3 kg
mf
= mass of fuel burned
=0.55 kg
Te
= temperature of boiling water, °C
= 100 °C
Ti
= initial temperature of water, °C
=29 °C
Hl
= latent heat of evaporation at 100°C and 105 Pa, kJ/kg
= 2257 KJ/kg
Hf
= Calorific value of fuel, kJ/kg
= 17400 KJ/ kg
Ƞ =
= 25.77%
4.2. Comparisons of the performance of
different gasifier stoves:
|
Sl no.
|
Name of the stove
|
Efficiencies
|
|
1
|
Briquette gasifying stove, by
Thomas Reed and Ron Larson.
|
35%
|
|
2
|
Institutional gasifier stove,
AIT.
|
29%
|
|
3
|
Domestic gasifier stove, AIT.
|
25%
|
|
4
|
Commercial gasifier stove, AIT.
|
31%
|
|
5
|
San San rice husk gasifier
stove, by U Tin Win.
|
29%
|
|
6
|
Charcoal making wood gas cook
stove, by Elsen Carstad.
|
30%
|
Table 4.1
The
efficiency of our stove is 25.77% due to availability of limited scope during
construction. A better performance can be achieved from the stove by using
still better and precise tool and techniques for construction of the same.
Figure 4.1: Producer gas stove in
operation
Figure 4.2: Evaporation of water due to tremendous heat formation
CHAPTER FIVE
CONCLUSION
We have come up with a new design
which is economically viable for rural households by studying some of the
existing designs. Several modifications have been made in the construction of
the producer gas stove which is necessary for getting much higher performance.
All the materials utilized in the construction of the stove are locally
available and cheap. This type of stove has the potential to save fuel wood
because it can work on a great variety of non-wood or waste-wood fuels. Improvements in household’s biomass burning stoves
potentially bring three kinds of benefits, i.e. reduced fuel demand, with
economic and time saving benefits to the household and increase sustainability
of the natural resources base; reduced
human exposure to health damaging air pollutants; and reduced emission of the greenhouse gases that
are contributing towards global climate change.
REFERENCES
Research Papers:
[1]T. B. Reed
and Ronal Larson. A wood-gas stove for
developing countries. Presented at the “Developments in Thermochemical
Biomass Conversion” Conference,Banff, Canada, 20-24 May, 1996.
[2]Karstad,
Elsen., 1997. Elsen Karstad's Charcoal Making Wood Gas Cooking Stove (Sept 97).
http://www.ikweb.com/enuff/public_html/ELK.htm
[3] IPOBIS.,
2004. Portable Wood/Biomass Stoves. Combustion, Gasification and Propulsion
Laboratory,
Indian Institute of Science, Bangalore. http://cgpl.iisc.ernet.in/stv_final.pdf
[4] SSIC, 2005.
San San Industrial Cooperative., Ltd., Myanmar. Accessed 20 Feb 2005.
http://www.benergyssic.com/sansanrice.htm.
[5]Stanley,
Richard., and Venter, Kobus., 2003. Holey Briquette Gasifier Stove Development.
Aug.2003. http://www.repp.org/discussiongroups/resources/stoves/Stanley/BriqGassstove.htm.
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