Pilot Scale Experimental Study On SDF Gasification And Melting

With the rapid growth of industrial sludge production,sludge treatment and disposal application have also developed rapidly.However,the current sludge disposal capacity is still insufficient,and there is still a broad space for development of sludge disposal.The solid waste high-temperature gasification and melting technology has been used abroad due to its advantages of good reduction effect,small secondary pollution and slag recycling.Although it is difficult to directly process the sludge alone,co-processing of sludge(such as sludge and coal,garbage mixed-burning power generation,cement kiln co-processing,etc.)has made some progress and application.Therefore,it is a feasible route to obtain uniform and stable sludge-derived fuel(SDF)with reasonable formula and use it for high-temperature gasification and melting treatment.Based on the development and application of the gasification melting technology of SDF,the bed characteristics of SDF in the gasification melting furnace was firstly studied.The resistance characteristics of the reaction bed with air flow passing through the bulk material bed and the thermal environment under load pressure were analyzed.Then the pilot scale SDF gasification melting furnace and system were designed,and the material balance and energy balance were calculated.According to the theoretical research results,the pilot scale experimental study of SDF gasification and melting process was further conducted.The bed resistance characteristics and thermal environment tests showed that the design height of the gasification melting furnace could resist the pressure of the SDF above,and it was further verified in the subsequent pilot test.The test of the air flow through the bulk material layer showed that the porosity of SDF in the stacking mode during the random entry into the furnace could ensure the amount of air entering the furnace and maintain the micro positive pressure operation.The capacity of the SDF gasification and melting pilot scale experimental system is 1.5 t/d,which mainly includes gas control system,gasification and melting system,condition monitoring system and residue recovery system.Pilot experiments were conducted for the gasification and melting treatment of SDF.The flue gas pollutants in the gasification melting process and the molten slag were analyzed.The results showed that the content of dioxins in the flue gas was only 0.01 TEQ ng/m3.The slag toxicity leaching test showed that most heavy metals can be effectively cured after molten disposal,which was far below the upper limit stipulated by national standard.The feasibility of preparing slag-free bricks by slag was preliminarily studied.With 70%slag content,the sinter-free bricks can meet the MU15 level requirements of concrete solid bricks(GB/T 21144-2007).In addition,a series of state data of the pilot test process were obtained,and the weakness in the operation of the furnace body were observed,which provided a technical basis for the subsequent design transformation and expansion of the gasification melting system.The research results show that the industrial sludge-derived fuel SDF gasification melting technology can achieve the expected goals of harmlessness,reduction and resource utilization of sludge disposal,and has good application prospects.