Experimental Investigation of Downdraft Gasifier with Co-firing of Wood and Lignite

Abstract

Gasification is an alternative for fossil fuels. It can contribute to the demand for heat, electricity and syngas. Various biomass have been used extensively as a fuel for gasifiers. Extensive literature is also available on coal gasification. Lignite being low grad coal forms clinker when used as a fuel in boilers of thermal power stations. India has large reserves of lignite. In this work, an attempt is made to evaluate lignite as a fuel in downdraft gasifier for decentralized power generation gasifier. Clinker formation and reduction of syngas are drawbacks with lignite gasification. Co-firing with lower ash and higher fixed carbon fuel (with lignite) is one of the possible ways to reduce clinker formation. This study presents the experimental investigations on effect of fuel size on gas generation rate, calorific value of producer gas and gasifier efficiency in 10 kWe downdraft gasifier. For the experimental purpose, three different sizes of lignite were selected. They were in the range of 25-28 mm, 28-31 mm, and 31-35 mm. It was observed that better calorific value (885.99 kcal/m3) and efficiency of gasifier (67.88%) were obtained with particle size 25-28 mm. Experiments were also performed with co-firing of lignite and uneven sized wood (1:1) to evaluate the effect of different parameters. The experimental results prove that co-firing in a downdraft gasifier is an effective and better solution in different parameters like efficiency and calorific value of syngas compare to pure lignite gasification.