Study On The Prolysis Characteristics Of Sewage Sludge

Pyrolysis of sewage sludge, as a thermochemical process including several complicated chemical reactions, is mainly influenced by operating conditions and the characteristics of sewage sludge itself. Sewage pyrolysis technology is efficient and occupies small areas. It can also reduce the the potential secondary pollutants and the emission of hazardous material. The gas products and the oil produced by sludge pyrolysis have high value, and they can be used as fules or chemical materials. Therefore pyrolysis thechnology is one of the effective methods of sewage sludge conversion and utilization.The main content and result are as follows:Researches chose three kinds of Shanghai municipal sewage sludge as the sample. Experiments on pyrolysis proeess and kineties of sewage sludge were done on an automatic thermogravimetic analysis, and the optimal kinetics reaction order was obtained by comparison of different reaction orders,then the activation energy and frequeney factor are solved.The pyrolysis experiments were carried out in a fixed-bed reactor. The results indicate that the non-condensable gas, mainly composed of H₂,CO,CH₄,CO₂,changed regularly with the reaction temperature. The oil was analyzed by gas chromatography and mass spectrometry(GC-MS), and a qualitative analysis was made. The oxygenated compounds were the biggest component,and the nitrogenated compounds were also the main compounds. Polycyclic aromatic hydrocarbons (PAHs) were hardly found.The surface pores of char particles change complicated as the temperature increases.The Curie-point pyrolyzer that directly connected with gas chromatography and mass spectrometry(GC-MS) was to on-line analyze the pyrolysis liquid products. The research shows that the composition of sludge Curie-point pyrolysis liquid products were very complicated,which are made up of substantial oxygenated compounds, especially long chain carboxylic acids and ester, and other monoaronatics,steroids. The products also contained small concentrations of PAHs, even at the low temperature of 315, supperessed by short detention time.