Waste To BioCNG - Retap Solutions Pvt Ltd

Retap BioCNG Plant

Wet waste in Mangalore is presently been dumped into landfills releasing huge quantities of harmful greenhouse (methane) gas into the atmosphere. Also some wet waste ends up on the roads where it lies in open there and some of the bulk generator are washing out the wet waste into the city drain which in turn discharges toxic leachate into river streams. These discharges carry an appreciable organic load during rainy season and results in irreversible deterioration to soil and water thereby resulting in people’s displacement from their ancestral lands.

The objectives of Retap BioCNG Plant is to ensure scientific and safe disposal of Segregated Wet Waste by converting it efficiently into green BioCNG fuel and high quality Organic Fertilizer, thereby preventing degradation of local flora & fauna.

BioCNG Process:

The BioCNG technology works on a collection-flow-process. Biodegradable municipal waste with the cow dung is guided into the continous bio-digesters with the help of a pumps, several times per day. Additionally, recycled and treated water from the same plant is pumped into these bio-digesters.The bio-digester are mixed by submersible agitators and will be operated in a mesophilic (38°C – 40°C) temperature range. The bio-digesters are standing cylindrical tanks made of reinforced concrete or Glass lined tanks etc and are equipped with a heating system. The biodegradable feed is efficient converted into Biogas via bio-methanation process using patented technology within the bio-digestors. The bio-digesters are covered with a double membrane for the collection of Biogas.

BiogasUpgradation to BioCNG:

Biogas that is produced after the bio-methanation process consists of Methane (CH4) and Carbon-dioxide (CO2) along with some traces of water vapour, Hydrogen Sulphide, Nitrogen, Hydrogen and Oxygen. Carbon Dioxide, water vapour and H2S must be removed before the biogas can be used.The scrubbing is done by using patented Pressure Swing Adsorption(PSA) technology which guarantees less than 1% methane loss during the process (only 1% or less than 1%) The produced gas will be scrubbed further to contain minimum 97% (+-1%) methane and the rest of CO2 at the end of scrubbing cycle.

BioCNG Product Specifications (as per BIS standards):

Methane :> 97% ±1%

Carbon Dioxide :< 3% ±1%

Nitrogen: 1-2%

Hydrogen Sulfide: less than 10 ppm

Water vapour: Dew point (-70 Deg C)

Wobbe Index : 44.6 to 44.7

Bio-CNG Storage System:

The upgraded and compressed BioCNG storage cylinders (cascades) are placed on specially designed trucks and brought to a fueling station or at the customer site, where it can be distributed into vehicles or use for their application in furnaces. The cascades are made up of high strength stainless steel, which can handle pressure up to 400 bars but the working pressure is considered to be 250 bar only. The cascade of capacity 100 kg, 300 kg, 400 kg and 500 kg are used for transportation. The total No’s of cylinders, to be packed into cascades shall range between 30 – 40 of each with a volume of 75 liters, which have a capacity of 11 kg each at 250 bars. At costumer end site Pressure Reducing System (PRS) is installed, which again reduces pressure to 1 bar or the usable pressure at the clients end use.