하수슬러지의 마이크로웨이브 가열 가스화 및 바이오가스 개질 특성

Abstract

Due to the development of industrial development, the properties of wastewater and wastewater are diversified at high concentration, and the amount of waste sludge generated by solid waste is also increasing rapidly. Energy The reduction of energy consumption and the reduction of waste sludge in the current wastewater treatment facilities, which are living in an era of climate change, are now becoming very important issues. It is a study to utilize sewage sludge and biogas, which are waste generated in sewage treatment plant, as a renewable energy source. It is the technology of recycling sewage sludge through pyrolysis / gasification process. Both pyrolysis and gasification produced gas, char, and tar. The gas produced for the gasification contained mainly hydrogen and carbon monoxide with a small amount of methane and hydrocarbons (C2H4, C2H6, C3H8). The microwave gasification generated higher heavy tar, compared to other processes. The sludge char showed a vitreous-like texture for the microwave process, and a deep crack shape for the conventional heating process. Through the results, the produced gas from the microwave processes of wet sewage sludge might be possible as a fuel energy. But the produced gas has to be removed the condensable PAH tars. And the sludge char produced can be used as a solid fuel or adsorbent. It is a pyrolysis / gasification gas microwave reforming device. Methane(CH4) and carbondioxide(CO2) are the components of a produced gas from biomass pyrolysis gasification and a biogas from bioreactor. The both gases are known main greenhouse gas affected world climate change. This study tried to investigate the characteristics of a microwave heating reforming to convert the produced gas to the valuable fuel energy. Through the microwave reforming, a carbon receptor was used as two types of sludge char and commercial activated carbon. For the case of CH4 reforming, H2 was produced by a thermal decomposition with generating a carbon(C) which adsorbs on the active catalytic plate and reduces activate catalytic reaction. For the case of CO2 reforming, CO was produced by reacting with the carbon on the surface of the carbon receptor. This can solve the problem by removing the adsorbed carbon on the carbon receptor. The sludge char as the carbon receptor showed higher gas yields of H2 and CO than the commercial activated carbon receptor, while giving comparatively higher heating value for the sludge char receptor. And for the cases of lower temperature and residence time in the carbon captor, the CH4 and CO2 conversions and the reforming gas yield had lower values. The pyrolysis and gasification technology uses diverse waste resources, including biomass, urban solid waste, and sewage sludge, to produce synthetic gases for industrial use. The tar in the thermal decomposition gas from the pyrolysis and/or gasification process, however, damages synthetic gas facilities and causes operation trouble. Comparing tar conversion over for each case of tar cracking decomposition and carbon dioxide, carbon dioxide-steam, and steam reforming conversion. In order to obtain the tar conversion and the high-quality product gas, it was advantageous to modify the carbon dioxide-water vapor simultaneously, but the carbon dioxide reforming conversion was excellent in terms of the continuous use of the carbon acceptor. It is hydrogen production technology through biogas reforming. First is a super-adiabatic compression spark ignition reformer. When the oxygen enrichment rate and input gas temperature increased, hydrogen and carbon monoxide were increased. But the biogas CO2 ratio and engine revolution increased, the syngas were reduced. For the reforming of methane 100 % only, generation of hydrogen and carbon monoxide was 58 % and 17 %, respectively. However when the biogas CO2 ratio was 40%, hydrogen and carbon monoxide concentration were about 20 % each. The second reformer is a 3D-IR Matrix burner reformer. The nickel catalyst was used inside a reformer. Parametric screening studies were achieved as Steam/Carbon ratio, biogas component ratio, Space velocity and Reformer temperature. When the condition of Steam/Carbon ratio, CH4/CO2 ratio, Space velocity and Refomer temperature were 3.25, 60%:40%, 19.32 L/g･hr and 700℃ respectively, the hydrogen concentration and methane conversion rate were showed maximum values. Under the condition mentioned above, H2 concentration was 73.9% and methane conversion rate was 98.9%. The third reformer is the plasma dump reforming. A plasma dump reformer was proposed to produce H2-rich synthesis gas by a model biogas. The three-phase gliding arc plasma and dump combustor were combined. Screening studies were carried out with the parameter of a dump injector flow rate, water feeding flow rate, air ratio, biogas component ratio and input power. As the results, methane conversion rate, carbon dioxide conversion rate, hydrogen selectivity, carbon monoxide yield at the optimum conditions were achieved to 98%, 69%, 42%, 24.7%, respectively. Sewage sludge and biogas are identified as energy sources, and a distributed generation system can be constructed in connection with fuel cells such as SOFC.