Study On Synergistic Preparation Of Multi-Stage Biomass Energy And Generation Characteristics Of Process Associated By-Products In Urban Steel Mills

Biomass energy is one of the alternative clean energy sources,and its utilization and promotion have attracted worldwide attention.Developing the synergistic disposal of biomass wastes in urban steel plants can not only prepare various forms of biomass energy,but also effectively reduce CO2 emissions and promote the green,low-carbon and high-quality development of iron and steel industry.In this context,taking the coordinated development of steel mills and cities,realizing the deep utilization of resources and energy as the starting point,relying on a major research topic of a well-known domestic steel plant,this paper took the municipal solid waste(MSW)as the main research object,and carried out a series of basic experimental studies on the preparation of hydrogen-rich syngas and solid waste-based biochar via pyrolysis and gasification of MSW,and the preparation of liquid derived fuels from hydrogen-rich syngas via Fischer-Tropsch synthesis.The paper also studied and analyzed the generation characteristics of environmental load organisms in the process of multi-stage biomass energy preparation,and explored the purification technology process.The research results can provide a certain theoretical research and technical reserve for the development of potentially available biomass energy and fuel products in iron and steel metallurgical process,to realize the "waste disposal,absorption and recycling" function of urban steel mills and build an environment-friendly steel mill ecological industrial chain.The main research results were as follows.(1)The technical route to prepare multi-stage biomass energy for urban steel mills to coprocess MSW was systematically studied.and based on a large number of basic experiments,the preparation and process catalytic mechanism were analyzed,and a complete set of process parameters for the preparation of hydrogen-rich syngas in urban steel mills was formed.With the MSW as the raw material,when the pyrolysis and gasification temperature was 850?,the reforming temperature was 850?,oxygen supply ER(Equivalent Ratio)was 0.15,and steam addition S/C(Steam/Carbon,mol/mol)was 3.6,for the alumina-supported catalyst with the active component Ni content of 15%and the additive Ce addition of 5%,the concentration of H2 in the H2-rich syngas reached the highest 37.38%,and the ratio of H2/CO was up to 2.75.For the carbon material-supported catalyst with the active component Ni content of 15%and a molar ratio of the additive Ce to the active component Ni of 0.25,the concentration of H2 in the H2-rich synthesis gas reached the highest 37.76%,and the ratio of H2/CO was up to 2.57.(2)The synthesis chemical conversion reaction process from MSW to liquid-derived fuels was also systematically studied,focusing on the action mechanism of catalysts in the synthesis of liquid biodiesel from MSW.The liquid derived fuel diesel containing linear alkanes C9?C21,paraffins and heavy alkanes can be generated from MSW via gasification and catalytic reforming,Fischer-Tropsch synthesis process.The process of preparing liquid derived fuels from syngas was mainly affected by operational factors including synthesis temperature,pressure,and composition of the catalyst.For the Co/Al2O3 catalyst system,at 260?,1.5 MPa and 8%loading of active component Co,the components of the synthesized liquid derived fuel were mainly straight-chain alkanes C16?C25.For the Cu-Co/Al2O3 catalyst system,at 240?,1.5 MPa,8%loading of active component Co and 2%loading of promoter Cu,the main components of the synthesized liquid derived fuel were linear alkanes C10?C21,and a small amount of branched alkanes,paraffins and heavy alkanes were also generated,and the composition of liquid products was closer to the composition of diesel oil.For Ce-Cu-Co/Al2O3 catalyst system,at 200?,1.5 MPa,8%loading of active component Co,2%loading of promoter Cu,and 8%loading of the promoter Ce,the main components of the synthesized liquid derived fuel were linear alkanes C10?C21,and a small amount of branched alkanes,paraffins and heavy alkanes were also generated.The composition of the liquid products was the closest to that of diesel oil.(3)The highly efficient Ce-containing Ni-based catalysts suitable for gasification and reforming of MSW were developed.The supported catalysts with alumina or activated carbon materials as carriers,Ni as active component and Ce as promoter,can effectively promote the cracking of tar.Among the catalysts,whether alumina-supported catalysts were prepared by impregnation method or co-precipitation method,when the active component Ni content was 15%,and the promoter Ce content was 5%,the catalytic cracking effect of the catalyst on tar was the most significant,and and the tar concentration was reduced from 30.12 g/Nm3 to 14.65 g/Nm3 and 14.21 g/Nm3,respectively.Carbon material-supported catalysts can effectively promote the breakage of the benzene ring in the polycyclic aromatic hydrocarbons to convert into the alkane substances in the extended chain,which was beneficial to the subsequent treatment and utilization of the tar.However,excessive amount of Ce can inhibit the catalytic cracking performance of catalysts for tar.From the point of view of promoting the cracking conversion of tar,the molar ratio of Ce to Ni should be controlled to be no higher than 0.5.(4)The associated properties of solid waste-based biochar,tar,PAHs,H2S,SO2,NH3,NOx and other environmental load substances in the preparation of multi-stage biomass energy from MSW were analyzed in detail,and effective purification technologies were explored to ensure the environmental friendliness of the derived diesel preparation by thermal chemical conversion from MSW and Fischer-Tropsch synthesis process.The associated solid waste-based biochar can be used as activated carbon for heavy metals capture and harmful gas adsorption after being activated by steam at 850?.Catalytic reforming can effectively reduce the concentration of tar,and convert polycyclic aromatic hydrocarbons in tar into alkane species in the chain.The UVFeton treatment can promote the degradation of environmental load substances in the scrubbing water.When the UV-Feton reaction time was 40 minutes,the degradation rate of phenol reached 88.8%,and the average degradation rate of polycyclic aromatic hydrocarbons can reach 98.5%when the reaction time was 50 minutes.Activated carbon adsorption had obvious effect on the removal of SO2,NH3,NOx,but had no obvious effect on the removal of H2S,especially on the removal of low concentration of H2S.Chemical absorption can effectively remove H2S.Among them,30%MEDA/GTS compound desulfurizer can remove more than 95%of H2S in syngas,which can make the concentration of H2S lower than the allowable limit of H2S in feed gas in Fischer-Tropsch synthesis process,gas turbine and fuel cell processes(usually these processes limited the concentration of H2S to less than 75 mg/Nm3.).