Bio-waste gasifier that works out cheaper than grid power

Many ingenious innovations in agriculture do not require an IITian’s brain, but are by humble, poor peasants across the country.

From Kashmir to Kanyakumari, several hundreds of these innovators endowed with their curiosity, traditional knowledge and skills have made farming easier for themselves and their ilk.

Mr. Rai Singh Dahiya in Rajasthan never stepped into a school, but it did not stop him from receiving an award from the local District Collector for building a unique biomass gasifier for operating modified diesel engines.

The biomass-based gasifier unit processes about 20 kg of bio-waste to run an engine of 30 HP for an hour. So far about 50 gasifiers have been sold in the village.

Shape of the unit

The gasifier is conical in shape, compact in design and surrounded by a water jacket with the capability to handle multiple fuel sources.

Fuel wood or agricultural residues are fed into it. An air inlet is provided at the bottom. The system comprises two stages, one for removing ash, and the other, for charred residue and tar.

The primary filter unit comprises a series of rows of filtration units. Perforation becomes progressively smaller from the first to the third filtration unit.

The filter can be easily cleaned and is surrounded by a water jacket. The secondary filter has layers of different sizes of sieves ranging from 2 inches to a fine size with the cleaning gate at the bottom.

Detailing its operation the farmer says, “first, the bio-waste must be deposited from the top. This unit acts as a furnace and heats up to 200 degree centigrade to generate gas.

The gasifier is monitored and fed continuously first for about 30 minutes. An aspirator is turned on for sucking producer gas until the flame appears.

Water cooling

“Next, the air supply from the bottom is cut off. The produced gas is made to pass through the first cyclone where water-cooling is done; the gas is cooled and partial cleaning is also achieved.

“The gas then passes through the second cyclone, which removes carbon and ash based residues, and enters the filtration unit consisting of sieve grills and cloth.” This cleans up the gas completely. After cleaning, the gas is fed into the mixer unit, which mixes the gas with air in the right “fuel-air ratio”, which is set for the engine and power rating.

Calibration mark

There is a calibration mark for optimal ratio set by the innovator, but the user can override that and choose his settings.

Alternatively, the nature of the knocking sound, which changes at optimal ratio, can also be used as a cue for optimal mixing ratio.

The fuel mixer then feeds the fuel-air mixture into the modified engine, which runs on this clean fuel.

The furnace in the gasifier unit can be built to different capacities as per availability of biomass and agricultural residue. “Considering the cost of machine, fuel-biomass and local labour, this arrangement is estimated to cost less than half the cost per unit of power when compared to normal electricity grids costing 4 Rs per unit.

“It can be used to operate pump sets in remote fields, pump up water in homes, operate basic machines such as saw mills, flour mills and generate electricity by charging an alternator,” explains Mr. Dahiya.

Fuel consumption

He claims that the fuel consumption to be almost 30-40 per cent less than other available designs. The prices vary from Rs. 1,25,000 for 10 kW unit to Rs. 3,25,000 for 35 kW unit.

For more details contact Mr. Rai Singh Dahiya, Thaldak village, Taluka Bohar, Hanumangarh, Rajasthan 335 524, 09414535665.

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Printable version | Jul 30, 2021 11:15:41 AM |

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