Case study on Bio Gas Plant Installed at Hingoniya Gaushala, Jaipur (Rajasthan), by Sai Nath Renewable Energy Pvt. Ltd

India is a land of religions. There are multiple believes and description of cattle in society related with the religion as well as in agriculture. India has the largest number of Cattle/ cows in the world. Livestock in India is increasing every year with increasing awareness. Most part of the India the slaughtering of Cattle specially cow is ban. To protect the cows Animal welfare Board of India (AWBI) works for them and also the state government has established many Gaushalas (an affiliated shelter). Cow shelters (gaushalas) are unique traditional institutions in India, where aged, infertile, diseased, rescued, and abandoned cows are sheltered for the rest of their life, until they die of natural causes. These institutions owe their existence to the reverence for the cow as a holy mother goddess for Hindus, the majority religion in India. The other aspect of running a gaushala is not simple as day-to-day expense is required to overcome the demand of food / fodder for cows, medicine for the cows, the infrastructure, staff salary taking care of the cows, electricity expenses, etc. Gaushalas are getting some fund from central as well as state governments and also in our country many private / individuals also provide fund to the gaushalas.

Details of Bio gas Plant

The process of bio gas involves processing of organic waste in anaerobic condition, the fermentation of the organic waste is done in absence of the oxygen, the bacteria grow over the waste to break it in simpler form separating CH4, H2O, H2S, CO2, CO leaving the fibre and water as the left over.

1. The total capacity of the plant is 240 cumtr. The plant installed is based on the KVIC floating dome and daily it can produce 240 cumtr of bio gas which is equivalent to 120 kg of LPG (as 1 cumtr of bio gas = 0.465 kg of LPG)
2. There are 4 nos. of digester having 60 cumtr capacity each there are four different digesters placed one after the other near by so that each plant can be feed separately and the gas from each plant is connected with the single pipe line.
3. Gas from the Holder the gas from the holders travels through 3 GI pipe line to the compressor (low pressure compressor), one line from the compressor is attached to the scrubber, another line is directly attached with the kitchen. The filtered bio gas is supplied to the DG set through 2 CPVC pipe lines. The supply line of raw bio gas to kitchen is 2 CPVC. The Pipe lines are controlled by pressure valves/ ball valves.
4. Each digester is having an intake of 1500 kg of cow dung per day + 1500 ltr of water i.e. 3000 ltr of slurry. The HRT is 45 days (as per the old design)
5. The Plant is having 5 major parts
   1. Mixer / Agitator
   2. Digesters.
   3. Compressor.
   4. Bio gas Supply Line.
   5. Filters / Scrubbers.

Present Working of Bio Gas Plant done by SNRE

1. Mixer / Agitator

The capacity of the bio gas plants digester already installed in gaushala was to treat 6000 kg of cow dung per day. Manual handling of such a huge quantity is not easy and time taken to complete the activity is also more. So overcome the time and the labour we introduce mechanical mixing system (to mix cow dung with water). The pits were already constructed, modification made.

The mixing area/ Platform is introduced with the ramp so that cow dung can be transported on the platform with tractor. The cow dung from the tractor is pulled manually by 2 labours on the metal platform / stand made of MS Channel and the water is added to the cow dung with the 2 pipe line at the side of the pit. After some time, the agitator motor is switched (7.5 HP motor each operating on 3 phase) on, the work of the agitator blades is to mix the cow dung with water, to have a homogenous slurry. The agitator is having 3 blades of 12 mm thick MS flat patti, attached with MS solid rod of 18 mm dia, with top Pully 9 dia and another pully on the motor of 3 dia. Both the pully are connected with 2 V type belts number 103. The vertical rod is free to rotate when the motor is switched on, the vertical road is having bush with bearing at top at middle and with a brass bush at the bottom (floor). The agitator rotates at the 50 to 120 RPM (to reduce the speed of the mixer, no spilling at the time of mixing takes place). There are 4 outlets present in the pit (with gates) to feed each digester separately.

After the slurry get ready the gate no. 1 is open so that the slurry enters in the digester no (1) time taken (in emptying the tractor and mixing with agitator/ mixer and making the slurry) is around 45 to 55 minutes. Similarly, the process of mixing is repeated till feeding of the all the 4 digester is completed. Total time taken to complete the feeding of all the 4 plants will be take about 4 to 5 hours.