Investigation of Pollutants from Producer Gas for Downdraft Gasifier

Abstract

Gasification lays its main emphasis on gasifying solid feedstocks with partial amount of oxygen. Gasification leads to generation of medium calorific value gas known as producer gas. Gasification can be used as an alternative for fossil fuels because of the growing demands not meeting supply of developing county like India. Pollutants such as tar, particulate matter (pm), dust, etc are major unwanted elements which are carried along with the Producer gas. There are various techniques such as physical, catalytic and noncatalytic methods which can lead to destruction of these pollutants. Among these ways, catalytic techniques boost a much higher potential to destruct pollutant intuitively and at the same time, it has ability to increase the conversion efficiency significantly. The experimentation on 10 kWe downdraft gasifier has been carried out with feedstocks such as lignite & sawdust briquette and catalysts such as Dolomite (CaMg(CO3)2) & Magnesium carbonate (MgCO3). Effect of catalyst (5% & 7 % catalyst to biomass ratio (C/B)) on performance of gasifier were studied in present work. This study represented experimental investigations on downdraft gasifier including temperature profile, content of Tar and PM in producer gas, gas composition and gasifier efficiency. The fuel consumption rate was found to be increasing slightly because of higher catalyst reactivity of fuel. The gas flow rate was in range of 23 m3/hr to 27 m3/hr. By addition of catalyst, it was observed that H2 and CO yield increased by 37% and 25% respectively in producer gas. The Gross calorific value of the producer gas increases from 1080 kcal/m3to 1334 kcal/m3 with the inclusion of catalyst. The gas efficiency increases from 65% to 78% with the addition of catalyst. Tar content of the producer gas was reduced with the addition of catalyst from 607.80 mg/m3 to 110.1 mg/m3. Particulate content was reduced from 65.35 mg/m3 to 30.11 mg/m3. Effect of MgCO3 was better compared to CaMg(CO3)2. Lignite with MgCO3 (7%) gives better result as per cold gas efficiency, tar, particulates and no major clinker problem as per present work.