Study Of Plasma Pyrolysis And Gasification Process To Recover Energy From Organic Waste

Abstract

In the present study, main focus was on plasma pyrolysis and gasification of organic waste specifically polyethylene and cotton waste and exploring the energy recovery possibilities from the gases obtained after the plasma pyrolysis and gasification. In pyrolysis the gases formed used to be Syn gas (H2 + CO), CH4, higher hydrocarbons along with soot particles. The waste is disintegrated using thermal plasma (which is generated using graphite plasma torch) in oxygen starved environment (pyrolysis) and also in partial oxidation condition (gasification). In this study attempts have been made to determine the pyrolysis gases formed in these two different conditions. In addition, it has been tried to understand that between plasma pyrolysis and plasma gasification which one would be economically attractive. Experiments have been carried out by varying pyrolysis chamber temperature from 5000C to 7000C and polyethylene and cotton are fed in the pyrolysis chamber. It has been observed that plasma pyrolysis of polyethylene in temperature range of 500 to 700 0C yields H2 as main component around 30-40% volume basis along with CO, CO2, CH4, C2H6, C2H4, C2H2 and soot particles whereas pyrolysis of cotton on the other hand provides less H2 around 15-20 %. Partial combustion (gasification) produces some amount of energy in primary chamber and it was thought that it may increase overall temperature of the primary chamber which in turn will increase the decomposition rate. However, it has also been observed that in plasma gasification H2, CO, CH4 content in the exhaust gases reduces to some extent (2-5%) due to partial combustion which may be due to short duration of experimental trials. Continuous operation of plasma system in gasification mode increases the primary chamber temperature which ultimately enhances waste to gas conversion efficiency. The theoretical and experimental energy recovery comparisons have also been done. SEM analysis of soot particles reveals the presence of nano soot particles.