Chemical-looping gasification of biomass in a 10 kW_(th) interconnected fluidized bed reactor using Fe_2O_3/Al_2O_3 oxygen carrier

Abstract:The aim of this research is to design and operate a 10 kW hot chemical-looping gasification(CLG)unit using Fe2O3/Al2O3as an oxygen carrier and saw dust as a fuel.The effect of the operation temperature on gas composition in the air reactor and the fuel reactor,and the carbon conversion of biomass to CO2and CO in the fuel reactor have been experimentally studied.A total60 h run has been obtained with the same batch of oxygen carrier of iron oxide supported with alumina.The results show that CO and H2concentrations are increased with increasing temperature in the fuel reactor.It is also found that with increasing fuel reactor temperature,both the amount of residual char in the fuel reactor and CO2concentration of the exit gas from the air reactor are degreased.Carbon conversion rate and gasification efficiency are increased by increasing temperature and H2production at 870℃reaches the highest rate.Scanning electron microscopy(SEM),X-ray diffraction(XRD)and BET-surface area tests have been used to characterize fresh and reacted oxygen carrier particles.The results display that the oxygen carrier activity is not declined and the specific surface area of the oxygen carrier particles is not decreased significantly.

Chemical looping gasification of sewage sludge using copper slag modified by NiO as an oxygen carrier

Chemical looping gasification(CLG) provides a novel approach to dispose the sewage sludge.In order to improve the reactivity of the calcined copper slag,NiO modification is considered as one of the good solutions.The copper slag calcined at 1100℃ doped with 20 wt% NiO(Ni20-CS) was used as an oxygen carrier(OC) in sludge CLG in the work.The modification of NiO can evidently enhance the reactivity of copper slag to promote the sludge conversion,especially for sludge char conversion.The carbon conversion and valid gas yield(V_(g)) increase from 67.02% and 0.23 m^(3)·kg^(-1) using the original OC to 78.34% and 0.29 m^(3)·kg^(-1) using the Ni20-CS OC, respectively.The increase of equivalent coefficient(Ω) facilitates the sludge conversion and a suitable Ω value is determined at 0.47 to obtain the highest valid gas yield(0.29 m^(3)·kg^(-1)).A suitable steam content is assigned at 27.22% to obtain the maximum carbon conversion of 87.09%,where an acceptable LHV of 12.63 MJ·m^(-3) and Vg of 0.39 m^(3)·kg^(-1)are obtained.Although the reactivity of Ni20-CS OC gradually decreases with the increase in cycle numbers because of the generation of NiFe_(2) O_(4-δ) species,the deposition of sludge ash containing many metallic elements is beneficial to the sludge conversion.As a result,the carbon conversion shows a slight uptrend with the increase of cycle numbers in sludge CLG.It indicates that the Ni20-CS sample is a good OC for sludge CLG.

基于Aspen Plus的生物质化学链气化耦合CO_(2)裂解模拟研究

生物质化学链气化耦合CO_(2)裂解技术能够在产生高品质合成气的同时将CO_(2)转化为CO,是可以同步实现CO_(2)增量降低和存量减少的有效手段之一。使用Aspen Plus软件,建立了生物质化学链气化耦合CO_(2)裂解过程的模型,研究了温度、压力和生物质与氧载体质量比(m(Biomass)/m(Oxygen carrier),简称m_(B)/m_(O))对反应产出合成气组分、气化特性参数和系统热负荷的影响。结果表明:随着温度的升高,反应产出的合成气中CO、H_(2)含量呈现上升趋势,CO_(2)、CH_(4)含量下降,产气热值增大,且在高于800℃时趋于稳定,反应温度在1000℃以下时,系统产热可以满足反应需要;当反应压力由0.1 MPa提高至0.5 MPa时,H_(2)、CO含量下降,CO_(2)含量提高,合成气热值下降,系统整体放热量增大;当m_(B)/m_(O)增大时,生物质进料量逐渐增多,氧载体还原产物中Fe含量增大,FeO含量降低,合成气热值上升;当m_(B)/m_(O)在0.3~1.3区间内时,系统产热可以满足系统反应所需。耦合CO_(2)裂解反应器后碳转化率有较大提升,并且在m_(B)/m_(O)为0.7时提升最为显著。

钙基复合载氧体的制备及反应性能

采用湿式混合成粒法得到了一种复合型钙基载氧体,并分别在综合热分析仪和流化床上考察了其反应活性和循环反应性能。结果如下:浸渍Ni离子能够明显降低载氧体与煤反应的起始温度,加快反应速率,缩短反应时间。增加Ni离子浸渍量对反应速率的影响不明显,但反应时间略有缩短。选择CaAlNi10载氧体进行了10次还原-氧化循环实验,固体产物和气体产物分析表明NiO在循环过程中对S的释放有一定控制作用;CaAlNi载氧体具有较高的再生率和良好的持续循环反应能力。结果表明,制备的CaAlNi载氧体适用于工业生产。