Cows rest on the bedding that is an odorless byproduct of their manure that has been renewed through an anaerobic digester on Kenn Buelow’s farm north of Chilton, WI.
Cows rest on the bedding that is an odorless byproduct of their manure that has been renewed through an anaerobic digester on Kenn Buelow’s farm north of Chilton, WI.
IISc(Indian Institute of Science) Biomass Gasification Process
DESI Power's analysis at the start of its programme was that biomass gasification was the most promising technology for providing affordable and competitive electricity supply and energy services to rural areas where agricultural and plantations wastes were available. A large parts of the wastes are, of course, being used in various forms for cooking, drying, fodder and building materials, with the largest part being burnt at very low efficiencies. In addition to such a waste of a valuable raw material, there are other serious adverse effects resulting from the traditional ways of burning biomass: exposure of women to smoke and carbon monoxide which causes respiratory and asthmatic disease, indoor and outdoor air pollution and smog, and the traditional servitude of girls and women for the collection and processing of cooking fuel.
DESI Power's aim was to look at modern new technologies which utilise the available agro and plantation residues at much higher efficiencies than in the traditional usage to generate electricity in a reliable manner. The goal was to utilise the selected and proven energy technology in a socially fair commercialisation system which enabled the villagers to establish and own local value addition chains for the production of goods and services which also generated local jobs. Energy services for cooking, lighting, water supply and social services was planned to be provided as an integral part of the village project.
Principles of Gasification
Biomass is a natural substance, which accumulates solar energy as chemical energy by the process of photosynthesis in the presence of sunlight. Biomass chiefly contains cellulose, hemi-cellulose and lignin, having an average composition of C6H10O5, with slight variations. For the complete combustion of biomass the theoretically amount of air required (defined as the stoichiometric quantity) is 6 to 6.5 kg of air per kg of biomass and the end products are CO2 and H2O. In gasification, biomass is subjected to partial pyrolysis under sub-stoichiometric conditions with the air quantity being limited to 1.5 - 1.8 kg of air per kg of biomass. The resultant mixture of gases generated during the gasification process is called producer gas, contains CO and H2 and is combustible. The raw producer gas also contains tar and particulate matter which have to be removed as they are harmful to the engine.
A typical gasifier plant based on IISc technology consists of a reactor, which receives air and solid fuel and converts them into gas, followed by a cooling and washing train where the impurities are removed. The clean combustible gas at a nearly ambient temperature is available for running diesel-generator sets in dual fuel mode or gas engine generator sets suitable for running on producer gas alone. In thermal applications, the cooling and cleaning of the raw gas is limited to the requirements of the thermal process.
In the down draft reactor, biomass feedstock undergoes drying and de-volatilisation in the upper zones and produces char. The volatile matters undergo oxidation in the combustion zone, with air being partially drawn from the open top and partially supplied by air nozzles located after the de-volatilisation zone. The gas then flow through a hot charcoal bed in which the tar produced earlier is burnt. This is the special feature of the IISc gasification process which enables the tar in the raw producer gas to be maintained at relatively low levels. Special washing and cleaning systems developed as an integral part of the gasification system further reduce the levels of tar and particles in the cold producer gas to very low levels. These are the features which are responsible for enabling the engines to run for long operating hours with maintenance requirements which are similar to those specified for pure diesel or pure gas firing.
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CO: 20 + 2%; CH4 : 3 + 1%; H2 : 20 + 2%; CO2: 12 + 1% ; Rest: N2 The lower calorific value is about 4.5- 5.0 MJ/kg (1000 - 1200 kcal/ m3). |
Applications
Obtained by the process of gasification, can be employed in thermal application or for mechanical / electrical power generation. Like any other gaseous fuel, producer gas affords much better control over power levels when compared to solid fuel. This also paves the way for more efficient and cleaner operation.
For thermal applications, gasifiers are a good option as a gasifier can be retrofitted with existing devices such as ovens, furnaces, boilers, etc. Thermal energy of the order of 4.5 to 5.0 MJ is released by burning 1 m3 of producer gas in the burner. Flame temperatures as high as 1200° C can be obtained by optimal air preheating and pre-mixing of air with gas. Producer gas can thus replace fossil fuels in a wide range of devices. A few of the devices which could be retrofitted with gasifiers are furnaces for melting non-ferrous metals and for heat treatment, tea dryers, ceramic kilns, boilers for process steam and thermal fluid heaters.
A diesel engine can be operated on dual fuel mode using producer gas. Diesel substitution of over 80% at high loads and 70 - 80% under normal load variations can be achieved. The mechanical energy thus derived can be used either for driving water pumps for irrigation or for coupling with an alternator for electrical power generation. Alternatively, a gas engine can be operated with producer gas on 100% gas mode with suitably modified air / fuel mixing and control system.
I'm involved with a project at NC State doing this very thing, except on hog waste. We've come up with a couple of really interesting wrinkles that should (in theory) reduce the residuals, increase the production of methane and remove the nitrogen before water effluent is discharged. Of course, bovine waste is somewhat simpler because you can dry it and burn it for fuel directly. Pigs are pretty nasty animals.
This is all bull$#!+ :)
(/lame attempt at humor)
Chilton and manure in the same sentence???
Billy Rubin must be laughing his head off.