Biogas Upgrading and Bottling Technology for Vehicular and Cooking Applications - Management of Natural Resources in a Changing Environment - page 139

biogas with methane content of <90 % was bottled using high pressure compressor
at 200 bar and fi lled in biogas operated car and three-wheeler using CNG dispensing
system. The car was tested for its performance with biomethane as fuel.
Biogas Upgrading and Bottling Experimental Setup at IIT Delhi
To meet the gaps in existing biogas purifi cation plant installed at Indian Institute of
Technology Delhi, the research was done to minimize losses to yield high purity
methane by automated controlling system. The whole setup was divided into two
main components: (i) Packed tower for removal of CO 2 and H 2 S and (ii) High-
pressure compressor and cylinder cascade for storage of purifi ed gas.
Packed Tower for Removal of CO 2 and H 2 S
Water scrubbing based biogas upgradation system developed at IIT Delhi is shown
in Fig. 5 . Raw biogas is fi rst compressed using intermediate compressor and fed to
the bottom of the packed bed at 10 bar pressure. Rotor pump was used to pressurize
water so as to get constant fl ow rate and then fed to the top of the packed bed. In the
packed bed, gas and water come into contact and water physically absorbs the CO 2
of the biogas. Water sealing is maintained in the bottom section of tower in order to
prevent the gas to escape from water outlet. Due to high turbulence inside the tower,
purifi ed gas contains water droplets with it; a mist eliminator is used to prevent it.
Water coming from the packed tower goes in to a fl ash tower, which is hollow vessel
at near atmospheric pressure. At the normal pressure, water releases the absorbed
CO 2 and H 2 S into another tower, where after further upgradation CO 2 can be used
for other purposes. After releasing the absorbed gases, same water is recycled for
further upgradation. The H 2 S level of up to 1,000 ppm can be purifi ed satisfactorily
along with CO 2 in water scrubbing method.
Compression and Bottling Unit
Bottling consists of a high pressure compressor having suction at 0.1 bar, discharge
pressure at 200 bar and having capacity 5 Nm 3 /h. Compressed natural gas cylinders
are used having water volume of 60 l capacity. Dispensing nozzle NZ type is used
for fi lling the compressed purifi ed gas in the vehicles. Dried and purifi ed gas goes
into the suction of high-pressure compressor, where it compresses the gas to desired
(~20 Mpa) pressure and fi ll into the storage cylinders. In the system, a multi-stage
compressor is used for the compression of methane-enriched biogas at 200 bar pres-
sure in CNG cylinder. Pressure swing adsorption (PSA) is used for the moisture