化学链重整制氢系统的过程模拟

为了评价化学链重整制氢系统的性能,针对以CH4为燃料、以化学链技术(基于NiO/NiAl2O4氧载体)为核心的2种不同工艺重整制氢系统——自热化学链重整制氢系统(autothermal chemical looping reforming,CLR(a))和蒸汽重整化学链燃烧系统(chemical looping steam reforming,CLR(s)),采用Aspen Plus软件进行了过程模拟和热力学分析。以2种系统的产气率、冷煤气效率、CH4转化率等为评判指标,得到了各系统优化的反应条件,并分析了各操作参数(包括燃料/重整反应器温度和压力、CLR(a)中氧载体甲烷摩尔比和空气甲烷摩尔比、CLR(s)中水甲烷摩尔比和燃料甲烷份额)对系统性能的影响,最后对2种制氢系统进行了定量比较和分析。结果表明:2种化学链重整制氢系统具有相近的燃料发热量和CH4转化率(98%),但自热化学链重整制氢系统工艺更为简单,所需氧载体循环流量仅为蒸汽重整化学链燃烧制氢系统的1/3,从而可节约传输能量;而后者重整气中氢含量更高(74.14%对65.81%),且具有更高的冷煤气效率(85.28%对71.19%)和产气率(4.05对2.97)。

Process Simulation of Chemical Looping Reforming Systems for Hydrogen Production

To evaluate the performances of chemical looping reforming systems for hydrogen production,two CH4-fueled hydrogen production systems using NiO/NiAl2O4 as oxygen carriers,autothermal chemical looping reforming(CLR(a)) and steam reforming(CLR(s)),were simulated and analyzed using Aspen Plus.Hydrogen production efficiency,cold gas efficiency,and CH4 conversion efficiency were calculated and compared for the two systems,in this way the optimal operation conditions were obtained.Sensitivity analysis of the two systems(including fuel/reforming reactor temperature and pressure,each molar fraction of oxygen carrier and air in CH4 in CLR(a),the molar ratio of H2O and CH4 and the percentage of CH4as fuels in CLR(s)) were also performed.According to the comparison of the two systems under optimal conditions,it is found that they have similar syngas heating values and CH4 conversion efficiencies(about 98%),and CLR(a) processing set-up is comparatively simpler,and its oxygen carriers flow rate is about one third of CLR(s),hence it is capable of saving energy for oxygen carrier transfer;The syngas in CLR(s) contents more hydrogen(74.14% vs.65.81%),more cold gas efficiency(85.28% vs.71.19%) and gas yield(4.05 vs.2.97).