Effects Of Operating Conditions And Additives On Plasma Coal Gasification

The importance of plasma coal gasification was summarized in this paper. By comparing ordinary gasification with plasma coal gasification, it was thought that plasma coal gasification was a promising technology because it had many advantadges such as high carbon conversion, many active species, high temperature, high quality gas, and little pollution. It was proved that this study of plasma coal gasification was very significant.Some basic parameters about plasma coal gasification were short and a blank field in catalytic effects of additives in China was still found. Then, the paper mainly explored the effects of operating conditions and additives on plasma coal gasification.Operating conditions were gained as follows: high quality coal gas could be abtained in the vertical reactor when plasma power was 45kW, feeding coal rate was 6.66kg/h, feeding air rate was between 14Nm3/h and 15Nm3/h, feeding steam rate was 10.0kg/h, coal granularity was 75m, temperature was about 1200K, and the concentration of O2 was higher. The vertical reactor was superior to the horizontal one.Catalytic effects of additives including CaCO3, Na2CO3 CaO, CaSO4, NaHCO3 and NH4C1 which were selected as some representative materials from ordinary catalytic coal gasification were studied. Some gasification indexes which consisted of the concentration, selectivity, quality of products and carbon conversion were examined. The results showed that the catalytic effects of Na2CO3 and CaCO3 were worse. When the mass content of NaHCO3 was between 5% and 20%, that of CaO was 5%, that of CaSO4 was 15% and that of NH4C1 was 15%, the catalytic effects of them were much better.Referring to the characteristic of plasma coal gasification and catalytic mechanism of ordinary coal gasification, possible catalytic mechanisms of additives were disscussed. Main mechanisms were possiblely that additives decomposed and released active species by high temperature of plasma and they accelerated the chain reactions The catalytic actions lied on the species, quantity and easiness of producing active particles. In addition the quantity of additives had a limit when they could catalyse coal gasification well.