A thermodynamic study of the removal of HCl and H2S from syngas

Advanced integrated-gasification combined-cycle (IGCC) and integrated-gasification fuel cell (IFGC) systems require high-temperature sorbents that are capable of removing hydrogen chloride and hydrogen sulfide from coal derived gases to very low levels. HCl and H₂S are highly reactive, corrosive, and toxic gases that must be removed to meet stringent environmental regulations, to protect power generation equipment and to control the emissions of contaminants. The thermodynamic behavior of 13 sorbents for the removal of HCl and H₂S under various conditions including: initial toxic gas concentration (1–10000 ppm), operating pressure (0.1–11 Mpa), temperature (300 K–1500 K), and the presence of H₂O were investigated. The correlation between HCl and H₂S was also examined. Thermodynamic calculations were carried out for the reactions of the 13 sorbents using a FactSage 5.2 software package based on free energy minimization. The sorbents, Na₂CO₃, NaHCO₃, K₂CO₃, and CaO are capable of completely removing chlorine at high temperatures (up to ~1240 K) and at high pressures. Water vapor did not have any significant effects on the dechlorination capability of the sorbents. Nine of the sorbents namely; Cu₂O, Na₂CO₃, NaHCO₃, K₂CO₃, CaO, ZnO, MnO, FeO, and PbO, were determined to have great potential as desulfurization sorbents. Cu₂O and ZnO had the best performance in terms of the optimum operating temperature. The addition of water vapor to the reactant gas produces a slightly detrimental effect on most of the sorbents, but FeO exhibited the worst performance with a reduction in the maximum operating temperature of about 428 K. The dechlorination performance of the alkali sorbents was not affected by the presence of H₂S in the reactions. However, the desulfurization capability of some sorbents was greatly affected by the presence of HCl. Particularly, the performance of Cu₂O was significantly reduced when HCl was present, but the performance of FeO improved remarkably. The thermodynamic results gathered are valuable for the developments of better sorbents.     

Hydrogen-rich syngas production of urea blended with biobutanol by a thermodynamic analysis

Both biobutanol and urea are the environment-friendly hydrogen carrier. This study is to compare hydrogen production between steam reforming of biobutanol and autothermal reforming of biobutanol feed using pure steam and vaporization of aqueous urea (VAU) by a thermodynamic analysis. Hydrogen-rich syngas production, carbon formation, thermal neutral temperature (TNT), and hydrogen production cost are analyzed in both steam reforming and autothermal reforming. The results show that hydrogen-rich syngas production with the use of VAU is higher than that with pure steam not only in steam reforming but also in autothermal reforming. When the VAU/butanol molar ratio is 8, and the O₂/butanol molar ratio equals 3, the reforming efficiency reaches up to 81.42%. At the same condition, the hydrogen production cost is lower than that without blending urea. Therefore, using VAU to replace pure steam in biobutanol reforming leads to benefits of increasing the hydrogen-rich syngas yield and lowering cost.     

联合CO2捕集的生物质化学链气化制备合成气系统分析

本文提出以Fe₂O₃为载氧体、以CaO捕集CO₂的生物质化学链气化系统,利用Aspen Plus软件对该系统进行了模拟,以合成气组成（干基）、合成气氢碳比、含碳产物的碳摩尔分布、冷气效率及收率等为系统性能评价指标,重点分析了燃料反应器温度（T_FR）、载氧体Fe₂O₃与生物质碳摩尔比（Fe₂O₃/C）、水蒸气与生物质碳摩尔比（Steam/C）、CaO与生物质碳摩尔比（CaO/C）等系统参数对固体生物质化学链气化系统的影响。结果表明,在T_FR = 825℃、Fe₂O₃/C = 0.5、Steam/C = 0.71和CaO/C = 0.26条件下,合成气制备系统性能较优,合成气中H₂和CO₂含量分别为55.2%和15.4%,氢碳比为1.93,冷气效率为78.2%,被CaCO₃捕集的生物质碳为18.2%,收率（湿气基）为1.95 Nm³/kg_biomass,其中合成气中H₂和CO收率为1.24 Nm³/kg_biomass。     

Kinetics of the water-gas shift reaction over a La0.7Ce0.2FeO3 perovskite-like catalyst using simulated coal-derived syngas at high temperature

The kinetics of the water-gas shift (WGS) reaction over a novel La_0.7Ce_0.2FeO₃ perovskite-like catalyst is investigated using simulated coal-derived syngas at temperatures of 550 °C and 600 °C which are higher than the maximum operating temperature limit for conventional high temperature WGS catalysts. The influences of CO, CO₂, H₂O and H₂ concentration on WGS reaction rate are determined using selected gas compositions that might be encountered in a coal-based gasification system. An empirical power-law rate model used in this study is found to correlate well with experimental data with good accuracy. Kinetics parameters over La_0.7Ce_0.2FeO₃ obtained in this study are mostly in agreement with those previously measured using Fe-Cr based commercial catalysts in a range of relatively lower temperatures (300-500 °C).     

Optimization of syngas production by non-catalytic partial oxidation of coke oven gas

Optimization of syngas production by non-catalytic partial oxidation of coke oven gas was carried out on a self-designed reactor. Tests were carried out to study the effects of volute and partial oxidation burners on the body the distribution of temperature and conversion. It was found that the partial oxidation burner can show desirable temperature distribution compared with the volute burner, under pure oxygen condition. As a result, it can improve the methane conversion and low oxygen consumption. Methane content in product gas can be reduced from 17 to 1%. The optimum operation conditions were: oxygen flow 9 m³/h, oxygen-coke oven gas 0.24–0.26, upper temperature of rector 1200–1250°C, and outlet temperature 960–1000°C.     

载体碱性对Fe基催化剂费-托合成反应的影响

低碳烃类化合物是化学工业中重要的有机原料,通过非石油路线由费-托反应(Fischer-Tropsch)制备低碳烃类具有巨大前景,载体对于费-托合成催化剂的反应产物分布具有重要影响。探究了载体碱性对负载型Fe 基催化剂在费-托合成反应中反应性能的影响。通过浸渍法制备了Fe₂₀/AlPO₄、Fe₂₀/γ-Al₂O₃、Fe₂₀/MgAl₂O₄ 催化剂,考评结果表明,载体碱性越强,碳链增长概率(α值)越大,C₅₊选择性上升,烯烷比(O/P)增加。通过Raman 光谱和TPH 实验对由柠檬酸铁铵为前体煅烧后的催化剂表层碳物种进行分析表明,载体碱性越强,催化剂表面碳石墨化程度越高,吸附碳数量越少。并依托XRD、H₂-TPR、CO₂-TPR 表征信息构建了不同碱性载体负载的Fe 基催化剂的构效关系,表明载体给电子能力的强弱引起催化剂表面碳物质含量和金属载体相互作用的差异,最终导致了催化活性和选择性的不同。     

Carbothermic Reduction of Alumina by Natural Gas to Aluminum and Syngas: A Thermodynamic Study

The carbothermic reduction of alumina to aluminum by methane is analyzed by thermochemical equilibrium calculations in order to determine its thermodynamic constraints. Calculations predict that in the temperature range 2300–2500°C at 1 bar pressure, the reaction Al₂O₃ + 3CH₄ = 2Al +6H₂ + 3CO should occur without significant interference by the formation of unwanted byproducts such as Al₂O, Al₄C₃, and Al-oxycarbides, and with higher yields than by using solid carbonaceous compounds as reducing agent. The reaction was examined for several initial Al₂O₃/CH₄ molar ratios. The proposed process may be carried out in a fluidized bed reactor using concentrated solar energy, induction furnaces, or electric discharges as sources of high-temperature process heat. An important advantage of such a process would be the coproduction of syngas, with the molar ratio H₂/CO = 2, suitable for the synthesis of liquid hydrocarbon fuels and polymeric materials.     

工业化甲醇催化剂在CO2加氢制备甲醇过程中的应用研究

系统地将工业化甲醇催化剂应用于CO₂加氢制备甲醇反应中,考察5种工业化甲醇催化剂在CO₂加氢反应中的反应活性,运用ICP、N₂-物理吸附、XRD和H₂-TPR等手段对催化剂进行表征。结果表明,Cu/Zn/Al催化剂具有较高的CO₂加氢反应活性,在温度220 ℃和压力3 MPa条件下,CO₂转化率为22.9%,甲醇选择性为64.8%。催化剂活性与组分含量、晶粒大小、比表面积和孔结构等因素有关,CuO和ZnO组分含量越高,催化活性越好,适度晶粒大小的CuO物种可能是该反应中有效催化活性位前驱体,反应规律与甲酸铜中间体理论基本吻合;高比表面积和规整孔结构均有助于提高催化活性。     

辐射废锅内气固两相流场的冷态测试与数值模拟

采用冷态实验测量和数值模拟相结合的方法,对辐射废锅内的冷态气固两相流场进行了研究。搭建了辐射废锅冷模装置,利用恒温热线风速仪和皮托管对辐射废锅内的气相冷态流场进行测量。利用马尔文激光粒度分析仪对辐射废锅出口、底部渣池以及附壁颗粒的粒径进行了采样分析。运用Realizable k-ε湍流模型和随机轨道模型分别对气相流场和颗粒运动轨迹进行了数值模拟。研究发现:Realizable k-ε湍流模型计算得到的气相流场结果与实验值吻合较好,辐射废锅内筒顶部存在一入口射流,射流沿流向逐渐衰减,气相流场在内筒底部趋于稳定;大部分颗粒直接被辐射废锅渣池捕集,少量细小颗粒被气流携带进入辐射废锅环隙或从出口逃逸;颗粒粒径越大、密度越高,颗粒的跟随性越差,出口颗粒的停留时间越长。     

熔融盐粗燃气调质实验研究

在固定床内进行了熔融盐粗燃气成份调质实验,对熔融盐粗燃气调质实验的运行稳定性、反应过程对熔融盐的物性变化的影响、粗合成气成份对调质实验的影响等问题进行了考察.结果分析表明,350～500℃所有实验工况下,熔融盐均能有效的吸收粗燃气中的CO2,得到的合成气中CO2体积分数在2％附近,熔融盐处理技术能有效增加合成气中H2体积分数,降低CO体积分数,连续运行11h后合成气成份仍相对稳定.实验完成后熔融盐中Na2CO3分布呈现中部高两头低的分布规律,Na2CO3和NaOH比例变化时熔融盐熔点变化较小.这些特性都表明熔融盐粗燃气成份调质适合作为气化、热解制备合成气的后续工艺,提升燃气品质.