Impact of the feedstock properties and the operating conditions on the sewage sludge gasification process in the fixed bed gasifier
This work presents results of the experimental studies on the gasification process of sewage sludge in laboratory fixed bed gasifier.The granulated sewage sludge(GS)samples used in this work were produced in a Polish urban wastewater treatment plant.Today,there is a rising interest in many countries in “traditional(e.g.agro and forest)biomass and waste biomass(e.g.sewage sludge)utilization processes(e.g.combustion,co-combustion,gasification and pyrolysis).During the last twenty years,there has been a major change in the way that sludge is disposed.For example,in the European Union(EU)landfill or water deposition of the sewage sludge with the e.g.lower heating value(LHV)equal to 6 MJ/kg is prohibited.In light of there is a large and pressing need for the development of thermal methods for the disposal of sewage sludge.Gasification has several advantages over traditional combustion process.Gasification leads to combustible gas,which can be used for the generation of useful form of final energy.It can be also used in such processes as the drying of sewage sludge directly on waste treatment plant.Additionally,volume of produced gas is lower in comparison of volume of flue gas from combustion process.For all of these reasons,gasification requires smaller and less expensive gas-cleaning facilities.There are limited studies on downdraft type gasifiers gasification process of sewage sludge with complex measurements for different operating conditions.In present work,operating parameters were varied over a wide range.Parameters such as air excess ratio λ=0.12 to 0.27,temperature air preheating t=50°C to 250°C and gasification agent composition(zO2=0.21 and zO2>0.21)were found to influence on temperature distribution,syngas HHV and composition.The operating conditions of sewage sludge gasification greatly influence the gasifier temperature profile and the syngas composition distribution.The results indicate that syngas heating value was found to decrease with increase air excess ratio for all analyzed cases: cold and preheated air and cold enriched air.The increase in the percentage of the main combustible components was accompanied by a decrease in the concentration of carbon dioxide.Increasing oxygen concentration increased the temperature,which tended to favour the formation of smaller molecules in the gas mixture.Thus,the enriched air medium produced a gas with a higher HHV.In contrast to conventional gasification,gasification process with gasification agent preheating causes that the flux of heat necessary to support endothermic gasification reactions is producing more effective.Air preheating causes increases hydrogen and carbon monoxide production.
sewage sludge fixed bed gasifier air gasification preheating enriched air gasification syngas composition
Sebastian Werle
Institute of Thermal Technology,Silesian University of Technology,Gliwice,Poland
国际会议
桂林
英文
1-10
2013-07-16（万方平台首次上网日期，不代表论文的发表时间）