Design,Fabrication and Testing of Downdraft Gasifier

Abstract

High prices of oil and natural gas are leading to increased interest in "Energy con- version" technologies such as biomass gasi cation, methanation, liquefaction, and solidi cation. Heating systems based on wood, fuel, electricity coal/lignite are com- mon in some industries. Environmental pollution, poor process control and high cost are some of the limitations of these system. On the other hand biomass gasi er tech- nology o ers high thermal e ciency,good process controllability, economic viability and environmental acceptability. Gasi cation is also a possibility for future energy use, as it generally burns hotter and cleaner than conventional biomass. Gasi cation produces a much higher concentration of carbon dioxide than direct combustion of coal in air (which is mostly nitrogen). The higher concentrations of carbon dioxide make carbon capture and storage more economical than it otherwise would be. In view of this, it is planned to design, fabricate and test a downdraft gasi er working with wood as well as lignite. The e ciency of gasi er is 70%. The performance of gasi er is evaluated with wood and lignite as a fuel and by varying ow rate. The temperature across the oxidation zone, reduction zone, pyrolysis zone are measured. The temperature with wood as a fuel across reduction, oxidation zone are 1165oC, 840oC and 400oC respectively whereas in lignite same are 970oC,950oC and 430oC. The gas generation rate (GGR) is 37 Nm3/h which is equivalent to 9 kWe.