Design and Development of Downdraft Gasifier for Rural Area

Biomass is the main source of energy for a large number of small, rural, and cottage industries along with the majority of rural households. The biomass-consuming industries can be divided into two categories, namely traditional industries and new or potential industries. Traditional biomass-based industries are essentially rural cottage and small scale industries. These industries depend predominantly on biomass fuels such as wood, agricultural residues, and animal dung because biomass is cheap and its supply is assured. Biomass energy is used in these industries for direct heating (firing of bricks, lime), indirect firing (drying, baking), boiling, steam raising and distillation. The production of generator gas (producer gas) called gasification, is partial combustion of solid fuel (biomass) and takes place at temperatures of about 1000 C. The reactor is called a gasifier. The combustion products from complete combustion of biomass generally contain nitrogen, water vapor, carbon dioxide and surplus of oxygen. However in gasification where there is a surplus of solid fuel (incomplete combustion) the products of combustion are combustible gases like Carbon monoxide (CO), Hydrogen (H2) and traces of Methane and non useful products like tar and dust. The production of these gases is by reaction of water vapor and carbon dioxide through a glowing layer of charcoal. Thus the key to gasifier design is to create conditions such that a) biomass is reduced to charcoal and, b) charcoal is converted at suitable temperature to produce CO and H2.Biomass gasification means incomplete combustion of biomass resulting in production of combustible gases consisting of Carbon monoxide (CO), Hydrogen (H2) and traces of Methane (CH4).This mixture is called producer gas. Producer gas can be used to run internal combustion engines (both compression and spark ignition), can be used as substitute for furnace oil in direct heat applications and can be used to produce, in an economically viable way, methanol - an extremely attractive chemical which is useful both as fuel for heat engines as well as chemical feedstock for industries Think of the 18 000 Indian villages that will continue to be without electricity for at least the next 10 years. Though they fall under the government's rural electrification programme, it is not feasible at present to connect them to the grid. Then, there are other 62 000 villages that are still waiting to be wired and in villages that are already wired, supply continues to be erratic. To electrify rural India so as to usher in development uniformly is an uphill task India being a large agrarian economy, biomass - wood, agricultural residues, animal dung, etc. - is available in enormous quantities. And, hence, over 40% of India's total energy requirement is met through biomass burning. However, biomass burning has been characterized with energy inefficiency and environmental hazards. Working towards a sustainable solution to the energy scarcity in rural India, researchers have arrived at a technological innovation to exploit the vast biomass resource and generate power in an environment-friendly and profitable proposition. Biomass- based power generation systems for rural applications could effectively make up for the absence of grid electricity supply in many remote areas. 1. THEORY OF GASIFIER A gasifier is a reactor that converts biomass into clean gaseous fuel called producer gas (having calorific value of the order of 1000-1200 kilocalories per normalized cubic meter). biomass gasifier system optimally utilizes biomass for power generation. It consists of a downdraft gasifier, a gas-cleaning train, and an engine. The technological innovation provided users with the option of dual-fuel operation. The existing diesel genset could run on both diesel and producer gas, instead of running only on diesel. The producer gas is fed into the diesel engine to let the engine operate in a dual-fuel mode, thereby reducing diesel consumption by more than 70%. The production of generator gas (producer gas) called gasification, is partial combustion of solid fuel (biomass) and takes place at temperatures of about 10000C. The reactor is