Contents • Introduction • Gasification Process • Types of Gasifiers Downdraft Gasifier Updraft Gasifier • Classification Of Smokeless Chulha • Forced draft smokeless chulha • Natural draft smokeless chulha • Factors affecting the properties of biomass solid fuel • Types of fuels used in Smokeless Chulha • Conversion of agricultural waste into compressed fuel by briquetting • Conversion of agricultural waste into compressed pellets • Design of Smokeless Chulha INTRODUCTION • Major part of India's population heavily depends on Biomass/Fuelwood for households cooking. • Fuelwood: higher energy density, ease in use/ transportation. • Biomass Residues: Rice husk, wheat straw, rice straw, coconut shell and husk, and many other agricultural wastes. Its efficient burning for cooking leads wastage, air pollution and health problems. Biomass residues availability is high in India. • Conventional stoves/ chullah: are not suitable for efficient and smokeless burning of biomass fuel. • Cost of LPG: Now a days petroleum products are so costly( day by day cost is increasing ) for household cooking. • Need: Suitable cost effective, efficient burning technologies / chullah design based on biomass residues for household cooking, shortage of fuel. • Gasification: Technology is required for proper utilization of biomass residues. It consumes 40-50% less fuel compared to its traditional counterpart. Thus is saves labour, money as well as environment. Current Indian Market Scenario •Biomass is a major source of energy for cooking applications in India. Large quantities of biomass residues are available in India. •Lots of biomass gasifier based cook stoves have been developed both for household cooking and community cooking and been successfully demonstrated. •“Four pilot projects for coal gasification and conversion of coal into chemicals required for the industry will be set up for technical and financial viability,” Union finance minister Nirmala Sitharaman said while presenting the budget in the Lok Sabha February 1, 2022. •Several Domestic Gasifier based Smokeless Chulhas are present in the market and in e-commerce websites like Amazon, Flipkart, Meesho and others. •Adaptability of Chulha to different biomass fuels from wood to cow dung, also briquettes, pellets, rice husks, coconut shells. •Thus, it has a scope of serving millions of people and aim towards effective, efficient, smokeless combustion. Gasification Process Gasification steps 1) Drying 2) Pyrolysis 3) Combustion and 4) Reduction • Drying: moisture content present in fuel gets vaporized100150C. • Pyrolysis: Biomass is heated in controlled amount of air and biomass breaks into tar(liquid and gas) and charcoal(solid) at 200-500C. • Combustion: Heat tar + charcoal in sufficient amount of air due to which tar cracks in H2O & CO2 and charcoal gets heated. • Reduction: CO2 and H2O passes over red hot charcoal and convert into flammable gases(CO & H2). Types of Gasifiers • Updraft Gasifiers- In updraft gasifier the fuel is supplied at the top and the air at the bottom so that fuel moves in opposite direction of producer gas. These are simple and gases are released at top therefore they are used to make gasifier chulha. • Downdraft Gasifiers– The downdraft design is essentially the same as the updraft design except that feed and air move concurrently from top to bottom of the gasifier. Advantage of the downdraft fixed-bed gasifier is that the tars are cracked down in the oxidation zone due to high temperature, thus the producer gas has lower tar content compared to other types of gasifiers. • Cross-draft Gasifiers- In this design, the biomass feed is introduced from the top and the air is from the side of the gasifier. The biomass moves down as it gets dried and finally, gasified while the gas exits from the opposite side of the unit. The exit for the gas is more-or-less at the same level as that of entrance. Updraft Gasifier Downdraft Gasifier Cross-draft Gasifier Updraft Gasifier • In updraft gasifier fuel is added from the top and primary air is added from the bottom first of all combustion takes place at the bottom. Since combustion is exothermic process so heat generated by is used for drying , pyrolysis and reduction as these are endothermic reactions. • In drying moisture gets vaporized from fuel and dry fuel goes downwards for pyrolysis where it converts into char(solid) + tar(liquid and gas) and this further goes for the combustion. • After combustion tar cracks into (H20+ CO2) and in reduction cracked passes over hot charcoal(C) where it converts into flammable gases(CO,H2). • Since produces release from the top and we add fuel also from top so need to be careful to prevent leakage of flue gases Downdraft Gasifier • • • • • First of all we need to understand how downdraft gasifiers works. We add fuel from the top and start the supply of primary air then combustion occurs and it is a exothermic process so it generates heat. This heat transfer to the upwards and pyrolysis and drying process occurs. When drying occurs water vapors moves towards downward and gaseous products are generated in pyrolysis also moves downward with the char where tar cracks and forms CO2 + H2O. That goes into the reduction zone and passes over the red hot charcoal and convert into flammable gas or producer gas. Forced Draft Smokeless Chulha • We have done the analysis of a forced draft smokeless chulha. In which gasification process is involved. • We add fuel from the upside and burn with the help of paper or kerosene oil and then we switch on the fan the air supplied is divided in two parts for pyrolysis and combustion. • We have outer cylinder made of metal and combustion made of cement. • The air enter at the bottom of combustion chamber in controlled amount as we made two holes at the bottom and fuel converts into flammable gases as we discussed in previous slides. • And secondary air enters from top of combustion chamber as we have made many holes at the top and air reacts with flammable gases and start to burn. • We have also installed a battery for poer supply for the fan so that it can be used in rural areas. Natural Draft Smokeless Chulha • Natural Draft Smokeless chulha is designed in such a manner that it prevents wastage of flammable gases. • In conventional chulha due to deficiency of oxygen proper combustion of fuel does not take place. It leads generation of toxic gases(CO) and smoke. • As we know carbon mono-oxide(CO) is not good for our health but it is flammable too. • In natural draft we burn fuel at the bottom as we do in conventional chulha • But we also design a duct and certain holes at bottom due to which secondary air enters from bottom and flows towards top in a separate chamber. • Secondary air enters into inner cylinder due to holes at the top of inner cylinder. In this way combustion takes place. • Due to flow of secondary proper combustion of fuel takes place and smoke generation decreases. • As we control the wastage of fuel therefore we need less fuel in comparison with conventional chulha. Factors affecting the properties of biomass solid fuel • Basically People use wood as a solid fuel in conventional chulha that is not economical. • Using wood as a solid fuel is also the cause of deforestation that is also not good for environment. • In smokeless chulha we can use agriculutral waste as a solid fuel like rice husk , straw , pellets etc. • But first we should know about the factors affecting the properties of solid biomass fuel. The solid biomass fuel should have : • 1) Dry: The fuel should be dry with moisture content preferably below 20%.High moisture content result in less stable stive operation and decrease the available energy output of fuel. • 2) Convenient Shape: The fuel have consized particle shape that enable convenient loading of fuel in the container. • 3) Uniform Partical SIze Distribution: The fuel should have uniform particle size distribution to avoid compacted zones or oversized voids within the fuel container. • 4) Sufficient Energy Density: The fuel have sufficient energy density in order to balance the heat output of the burnable mass Types of fuels used in Smokeless Chulha Dry Leaves Sawdust Cow Dung Wheat Straw Coconut Husk Rice Husk Conversion of agricultural waste into compressed fuel by briquetting • Instead of chopping down trees for firewood, we can make a fuel for cooking by using woody waste materials. • Carbonizing: First we carbonize the material in barrel with limited air (like making charcoal), then grid it into powder and mix with binder. Compress the mixture in briquette mold and then dry the briquettes in the sun to make cheap and effective alternative to wood or charcoal fuel for cooking. • Waste Materials: Dried leaves, twigs, straw, coconut shells, baobab shells, maize cobs , groundnut shells and sawdust. Do not use any thing that is too wet or anything else other than dry leaves or woody again. 2.Barrel by cutting a large hole in the top and a series of small hole sin the bottom 3.Fill the barrel with woody waste material 4.Allow the material to carbonise but do not let it burn completely 5. Binding of char 1.Waste Materials 6.Converting char into briquettes by using mould. Conversion of agricultural waste into compressed Pellets Design of Smokeless Chulha • As we have discussed before updraft gasifier is suitable for smokeless chulha as it release gas from top. • In conventional chulha due to deficiency of oxygen proper combustion does not take place so we have designed a duct for secondary air flow so that proper combustion will occur i.e. natural draft smokeless chulha. • We have discussed the design of natural draft smokeless chulha but we have made some changes in it. • They used wood as a fuel but we make it for agricultural waste. • As there is constant diameter of both inner and outer cylinder but we change the diameter of outer cylinder. The diameter at the bottom is more and at the top is less so that volume gets decreased and pressure will increase and velocity of air flow also increase. • And we made a stand of 0.5 ft. high so that air can easily flow through holes. Front View 3D View BottomView Computer Aided Design of Smokeless Chulha • This design here is a CAD model which was drawn using Solidworks. • The design consists of one hollow cylinder and an outer frustum whose dimensions are specified in the following slide. • The bottom area is perforated with a number of holes for passage of primary and secondary air. • It is also supported on a stand for better passage of air . Dimensions of Design • 1. 2. 3. 4. Outer Cylinder Diameter of bottom 300mm Diameter of top 150mm Height of cylinder 300mm Diameter of holes 20mm • Mesh 1. Height of mesh from bottom 50mm • 1. 2. 3. 4. Inner Cylinder Diameter of cylinder 100mm Height of cylinder 300mm Diameter of holes at bottom 15mm Diameter of holes at top 8mm • Stand 1. No. of supports 3 2. Height of support 150mm Conclusion • Clean Energy use and Human Development are closely linked. For successful clean energy technologies adoption, serious planning should be made to select appropriate technologies suitable in local context. • The technology should be need based, easy to adopt and capable of generating employment and income, leading to sustainable livelihood. • The technology should be launched as a part of the on-going development programs, involving efficient agricultural extension network to ensure backward and forward linkages. • Financial and technical support should be available to overcome the initial hurdles before wider replication. References • Philibert. Cédric, International Energy Agency, “Barriers to Technology Diffusion: The Case Of Solar Thermal Technologies” • Energy Statistics Report 2013 • Odisha Economic Survey 2014-15 • https://dir.indiamart.com/search.mp?ss=biomass+pellets+10mm&prdsrc=1&src=aspopular%3Akwd%3Dbiomasspel%3Apos%3D2%3Acat%3D-2%3Amcat%3D-2 • Kim and Nag, “The Diffusion of Technology, experience of Industrial countries and lessons for developing countries”. • Michael R. Hagerty , “Testing Maslow Need: National Quality of Life Across Time”, Vol. 46, No.3, (March 1999) • “Biogas Technology in India: More than Gandhi's Dream?” By Jo Lawbuary, HES
