Syngas Production By Chemical Looping Co-gasification Of Wheat Straw And Lignite With Iron-based Oxygen Carrier

As the basic material of the modern chemical industry,syngas mainly comes from the gasification of fossil fuels.However,CO2 emissions from the use of traditional fossil fuels have the potential to cause a "greenhouse effect".Inspired by the "double carbon" goal of "carbon neutrality" and "carbon peaking",the use of biomass feedstocks to partially replace coal to produce syngas can effectively reduce net CO2 emissions,which is a way of balancing economy and environmental protection.Compared with the traditional gasification method,chemical looping gasification is a new feasible gasification technology,which is gasified by the lattice oxygen in the oxygen carrier circulating between the fuel reactor and the air reactor to produce highquality syngas.Therefore,this paper carried out a series of studies on the partial replacement of coal by biomass and the production of syngas by combining chemical looping technology.(1)To better use biomass to partially replace coal,the thermal decomposition characteristics of wheat straw and lignite coal under different mixing ratios under copyrolysis and chemical looping co-gasification were investigated with lignite and wheat straw as feedstocks.Combined with the thermal analysis kinetic method,it was calculated and analyzed to study whether there was an interaction between feedstocks.The results showed that wheat straw and lignite have a significant synergistic effect under the condition of a mass mixing ratio of 1:1.(2)Based on this,the chemical looping co-gasification of wheat straw and lignite was carried out on the fixed bed to produce syngas.Based on this,a series of iron-based oxygen carriers were prepared by the impregnation method.The effects of reaction temperature,oxygen carrier(OC)content,and steam(S)content on the preparation of syngas were studied;Under the optimized conditions,a multi-cycle test was carried out on the oxygen carrier to investigate the stability of the reaction,and the product evaluation of the syngas and a series of characterization of the oxygen carrier were carried out.The results showed that when the reaction temperature was 950℃,OC/MF= 1,S/MF = 4,and Ca O/OC = 0.75,the gas yield,cold gas efficiency,and carbon conversion rate were 1.573Nm3/kg,70.18%,and 81.59%,respectively after 5 cycles.These results,combined with SEM-EDS and XRD characterization of oxygen carriers,strongly showed that adding an appropriate amount of calcium oxide can improve the gasification performance of chemical looping gasification by preventing the sintering of oxygen carriers.(3)Finally,the chemical looping co-gasification system model was built by Aspen Plus.Based on this model,the effects of reactor pressure,gasifier type,and gasifier flow on syngas gas distribution and LHV were studied.Through multi-factor interactive analysis of temperature,oxygen carrier content,and gasifier flow,temperature and gasifying agent flow played a decisive role in H2/CO value and LHV in syngas production.