Experimental Study On MSW Pyrolysis And Gasification In Fixed Beds

The disposal of municipal solid waste becomes more and more important in environment protection area as the quick development of economy and urbanization of our country. Sanitary landfill is the major treatment method in China. The technology is simple and it can be used in large quality, but it occupies land resources and has the pollution threaten of percolate, also doesn’t make use of utilization of MSW. Thermal disposal of MS W possesses advantages of volume reduction, resource utilization and pollution reduction, for example, the new technology of MSW combustion. So, thermal treatment draws more and more attention in China. MSW gasification is one of thermal treatments with significant advantage of zero emission. And the syngas can be used both in chemical industry and thermal power generation. Solid waste is converted into gas, which can be transported and stored conveniently. So, the gasification of MSW becomes valuable. The research of gasification of MSW has great meaning in social benefit, economic benefit and environment protection. At first, this paper made a simple introduction of MSW in our country. We found the advantages of gasification technology by a comparison of different treatment methods. And gasification in fixed-bed is adequate for the disposal of MSW in small towns with less production of MSW than big cities.The reduction of tar is one of the toughest problems in gasification. Catalyst additive is the main way to reduce tar production. TG-FTIR experiments were performed in order to study the catalytic effects of CaO on MSW gasification. There were there typical components:PE (in place of plastic material), paper and bamboo (in place of biomass). The effects of CaO additives and heating rates on tar generation during MSW pyrolysis were studied. CaO additives can reduce the content of acids, phenols and hydrocarbons in bamboo and paper pulp, but there is no obvious effect on PE. Compared with TG-FTIR with low heating rates, tube furnace experiments were closer to actual temperature conditions. Based on TG-FTIR, more experiments were performed on tube furnace in order to study the affection of temperatures, catalyst additives on syngas components, LHV and gas production. CaO additives have an significant catalyze effect on bamboo and paper pulp. The content of H2and CH4increases with CaO additives increase. At the same time, CaO absorbs CO2and CO. But no obvious effect is observed on PE.At last, in self-designed continues fixed-bed gasification reactor, experiments with air and steam atmosphere were conducted. The aim is to find the regulation of syngas components and LHV variation with change of air equivalence ratio, steam/material ratio and gasification temperature under these two atmospheres. At the same time, the influence of CaO additive on syngas components and LHV were also obtained. Combustible gases reduced with the increase of air equivalence ratio, and LHV goes down as a result. Higher temperature can promote both pyrolysis and oxidation of combustible gases. The content of H2is higher under steam atmosphere compared with air. CaO can absorb CO2to increase the LHV of synthesis gas. CaO additives can raise the contents of CO and H2in gasification of bamboo, and CO, CH4in gasification of PE with little effect on H2percentage.