Bio Gas Plant Process


There are regular waste disposal problems in almost all institutions like hostels, hospitals, convents,old age-homes, etc where more peoples are staying together. In the same time the cooking fuel consumption of these institutions is also very high. Fairly large quantities of firewood and other cooking fuels are consumed for routine cooking purposes. WCES is keen to educate these institutions about the advantage of using non-conventional energy sources. Most of these institutions rear cattle, the dung of which can also be utilized as a feed material to the biogas plant. The biogas generated will sufficiently reduce the regular consumption of other cooking fuels like firewood and LPG.

 
A biogasplant is an anaerobic digester that produces biogas from animal wastes or energy crops. Energy crops are cheap crops grown for the purpose of biofuels, rather than food. Biofuels are liquid, gaseous, or solid fuel made from live or recently dead organic material known as biomass, as opposed to fossilfuels, which are composed of ancient biological materials. Biogas is a type of biofuelcreated via anaerobic, or oxygen-free, digestion of organic matter by bacteria. A biogas plant is composed of a digester and a gas holder.
 
The digester is an airtight container in which the waste is dumped and decomposed, and the gas holder is a tank that harnesses the gases emitted by the slurry. Bacteria within the digester tank breaks down the waste and, as it decomposes, gases such as carbon monoxide, methane, hydrogen, and nitrogen, are released. Through a pressurized system, the gas holder conducts the flow of these gases upward into a hole in its drum. The hole is specially designed to allow gases to pass freely into the holder while prohibiting any gases from escaping back into the digester. In a controlled environment, the gases are later combusted, or reacted, with oxygen to create an energy source for such processes as heating and vehicle propulsion.
 
For the effective operation of a bio waste treatment plant, electricity is quite essential. The main advantage of waste to electricity project is that no external power is required for the operation of the plant. The power generated in the treatment plant can be utilized to meet the in-house requirement completely. Excess quantity can be utilized for any type of off-grid application, such as street lighting.
 
The generation of electricity through conventional method is a costly affair. Severe environmental problems will be caused on account of electricity generation through coal, diesel etc. Even in the case of hydro electric projects, many environmental problems will arise in and around project area through deforestation.
 
The generation of electricity using biowaste treatment plant is not a costly concern. Of course the installation cost of a waste to electricity project may be a little high. But the recurring expenses will not be substantial for the operation of the plant. In the plant, biogas is being generated everyday through anaerobic decomposition of waste.
 
Normally 1.5 kilo watt electricity can be produced from one cubic metre biogas. Depending upon the percentage of methane content in biogas, the power generation may slightly vary. The size of the generator can be fixed depending upon the availability of gas and quantity and duration for the requirement of the power. The gas can be utilized as operation fuel in gensets. Before feeding biogas as fuel in gensets the gas has to be passed through a gas scrubber to remove unwanted particles, gases, moisture etc.
 
There are two types of generators used to generate electricity from biogas. One is the duel fuel model and the other is 100% biogas model. Duel fuel models are diesel gensets. In this system the biogas is connected to the generator through air mix. Once the biogas is passed through the gensets, automatically consumption requirement of the diesel is reduced. Normally duel fuel gensets are working in 80% - 20% mode.
 
In 100% biogas engines, no other fuel is required either for starting or for operation. Any type of petrol engine can be modified for operating the same using biogas as operation fuel. The imported models of 100% biogas engines are very costly ones and the maintenance of such systems is very expensive. WCEShas developed 100% biogas engines. These engines are installed in various projects and the performance of all of them is very good.

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