Background:
Many modern and state-of-the-art technological interventions have been developed and incorporated into the gasification systems for biomass-based power generation. In this way, it looks to be a complete technology. However, in the recent biomass-based power generation systems, portability seems to be an important aspect as it eliminates the requirement of water for scrubbing. The compact gasifier will occupy lesser space and give higher efficiency. It will be portable to any site and can be used remotely with the help of pellets as fuel like a diesel generator set. The system will have more adaptability than the current gasifier-based stationary power generation plant in small-scale applications such as agricultural pumping, and irrigation, and also in need of rural electrification because of its hassle-free operation. The cost of electricity production will be significantly lower than conventional diesel-based generators. Dry-type producer gas cleaning systems (which can be easily replaced) for biomass-based power generators will reduce the requirement of water for cleaning producer gas. The low-cost catalytic tar cracking system will enhance the quality of producer gas which will improve the power production efficiency. This system will also cause value addition to the biomass char and will open business opportunities.:
Technology Details:
It is a portable downdraft gasifier for the production of low-tar producer gas without the active use of water for scrubbing. The main reactor is throat type. It has a grate area of 0.16 m2 and a throat diameter of 250 mm. The conical throat has a slope of 60? for easy falling of fuel material from the storage area. The storage tank has a capacity of 60 kg of fuel loading in the form of pellets. A stirrer has been used for the intermittent stirring of the grate for easy fuel flow as well as to prevent clinker formation. The catalyst bed has been placed at the periphery of the oxidation zone which is at the throat. The bed height is 300 mm and the depth is 150 mm. There are two large ports of 200 mm × 200 mm at either side of the gasifier for loading catalysts. Nickel-loaded char catalysts are used for cracking of tars in producer gas. Char's can be prepared from pigeon pea stalks or any material; of a similar kind. Char stalks were impregnated with nickel nitrate by incipient wetness method using the solution with a nickel concentration of 0.035 g/cm3. Impregnated char pellets were then dried in the oven at 105 ?C for 6 hours. Gas immediately after passing through the reduction zone comes in contact with the catalyst bed and a considerable amount of tar is cracked in this zone. It is then passed through a cyclone to separate fine char particles. Gas is cooled down in two cooling towers by indirect cooling using water. The cooling towers are made of stainless steel pipe. Gas attains a temperature of 55?C in these cooling towers. The final tar content achieved in the gas is 6 mg/Nm3.