Effect of Absorbent for Gas Purification Unit in Biomass Gasification Process with Downdraft Method

Abstract

The development of industry causes energy needs to increase. So that fossil energy reserves are increasingly depleting. This resulted in the growth of various alternative energies. One alternative energy that is being developed is biomass-based energy. Biomass is a renewable energy source that comes from plants both directly and indirectly. Indonesia is a country with a tropical climate that has a very large biomass potential. One of the methods that can be used in processing biomass is gasification, which is a process to convert solid biomass raw materials into fuels (syngas). The problem from the gasification process is the syngas produced has a low purity level. This is because there are still impurities that are contained in syngas. Therefore, a purification unit is needed in the gasification device. This research aims to make absorbents that can be used in gasification purification units. The types of absorbent used is coconut shell activated carbon. The pore structure of carbon is characterized by using an N2-sorption analyzer (Nova 2000, Quantachrome). Based on the results of characterization, it can be seen that the specific surface area of activated carbon absorbent from the coconut shell is 1320 m2/gram with an average pore diameter of 1.82 nm. The experiment device mainly consisted of gasification reactor, filter, and blower. The gasification reactor was installed to heating the biomass with the supply oxygen. The reactor had a height of 170 cm and a diameter of 50 cm in which the bagasse with the capacity of 15 kg/h was quickly burned. The gas filter contains the absorbent to clean the syngas product. The absorbent was installed in upper four holes. The blower was used to suck up the syngas. Some thermocouple and gas indicator were installed to monitor the condition in the system. The syngas production was analyzed by the GC/MS analysis. The effect of absorbent is to improve the syngas composition such as CO, H2, and CH4. The syngas contents in our experiment were CO, CH4, and H2 with a percentage of 9.294%, 1.348%, and 7.773%, respectively. These results are better than the previous research with the syngas contents are 7.891% of CO, 0.100% of CH4, and 0.889% of H2 because the previous research was not equipped the absorbent.