Experimental Research On Municipal Sewage Sludge Briquette Fuel

In this experimental research, the sewage sludg together with coal and rice straw were molded to sludg briqutte fuel(SBF). First, the were analyzed to determine its fundamental characteristics. Second, the physical properties of SBF were found out through molding experiments of raw materials. Then, the pyrolysis mechanism and combustion kinetics of raw materials sewage, rice straw, coal and SBF were investigated through the thermal analysis. In the end, combustion of SBF in electric furnace was done to simulate the real condition in boilers and get a reasonable combustion parameters. The purpose of this study was providing valuable basic data for the production and combustion of SBF, thereby, finding a new method to the disposal of sewage sludge.Due to its low calorific value and high ash,sludge is difficult to combust alone. After adding coal and rice straw and molding, the calorific value and volatile of SBF are similar to lignite and bituminous coal, and SBF could be used in lignite and bituminous coal-fired industrial boiler directly .The optimum relaxed density,compressive strength and falling strength of SBF is obtained when the Ratio of raw materials is sample N50M45C5, molding pressure is 100kN, moisture content is 12.5%. While furnace temperature is controled at 900 to 1000℃,excess air coefficient is controled between 1.3 to 1.7, the sample N50M45C5 under 50kkN was at the fastest rate of combustion. Therefore, ensured the SBF with the necessary physical performance, it should be focused on how to reduce the molding pressure while molding, and how to control suitable excess air coefficient while combustion.The ash melting point of SBF is approximately 1250℃,it is between soluble and insoluble .Therefore,the temperature of flue gas at the exit of SBF-fired boiler furnace should be controled under 1150℃to avoid the problem of heating surface slagging.Thermogravimetric analysis technology is used to characterize the thermal decomposition of raw materials and SBF. According to the TGA curves, the ignition temperature, ignitability number and combustion characteristic number of different samples are obtained to assess the combustion of SBF. Ignition temperatures of different SBF are between 230℃~ 245℃,which is lower than the ignition temperature of sludge.The more volatile SBF has, the easier ignition and combustion are. Among all samples, the sample N50M45C5 combusted at 20℃/ min heating rate showed the best flammability and combustion performance.Moreover, the reaction kinetics of the combustion of SBF is studied by the integration method of Coats-Redfern. The SBF combustion reaction can be divided into low temperature stage(reaction order is 2) and high temperature stage(reaction order is 0.5)...