Research On Composition Of Gases And Liquids Obtained From Different Pyrolysis Conditions Of Sewage Sludge

Due to the fast increasing of municipal sewage sludge in recent years andincreasingly stringent environmental quality standard, the traditional routs of sludgedisposal are more and more restricted.While, the sludge pyrolysis technology as a newtype of sludge disposal attracts more and more attention because of its high energyrecovery. Especially, the gas obtained from sewage pyrolysis has excellent fuel featureand the liquid is similar to petroleum-based fuels, they are more meaningful to energyrecovery. However the influence of different pyrolysis conditions on gas and liquidfractions is serious, so the research on the different conditions is necessary and by thiswe can get the variation of pyrolysis product yield and composition. Finally it lays agood foundation of pyrolysis products for the energy utilization.In this paper, an account of the state of the art of sewage sludge treatment anddisposal methods is provided, and then it has briefly discussed the research on thesludge pyrolysis technology in recent years.The small-scale test of swage pyrolysis carried out on the platform set up byourselves, from this, sludge pyrolysis mass balance is established. And through theresearch on final pyrolysis temperature, holding time and heating rate, the law of sludgepyrolysis is definited, moreover, the best pyrolysis condition of maximum oil yield isfound.The pyrolysis charcacteristics of sweage sludge was studied by analyzing theTG,DTG and DSC curves from a thermo garvimetric analyzer.The ultrasonic extraction technology used in the organic extraction of the liquidobtained from sewage pyrolysis has not only saved the time, but also got a betterextraction efficiency.GC-MS was used to determine the main components of the gases and liquidsobtained from different pyrolysis conditions. From this method, fistly, the pyrolysiscondition which can obtain maximun yield of methane in pyrolysis gas is found.Secondly, variation of the aliphatic, aromatic and heterocyclic compounds in thepyrolysis liquids is discovered with the change of different pyrolysis condition.Comparing two kinds of extractant,n-hexane and dichloromethane, the results of thevariation of the constituents are similar. With the increase of temperature, holding timeand the heating rate, the aliphatic compounds decreased, aromatic and heterocycliccompounds increased gradually，while，content of the nitrogen compounds in the liquidobtaind from diffident sludge pyrolysis conditions is always higher. However, fordifferent kinds of compounds in the pyrolysis liquid, the effects of the extractionobtained from the two solvents are different.Therefore, it’s conductive to the further understanding of the mechanism of sludgepyrolysis and the future application of sludge pyrolysis technology.