The Simulation And Research On The Solar Steam Of Methane For Hydrogen Production Using Molten Salt Heat Carriers

Hydrogen is an important energy carrier and fuel with excellent properties such asabundant reserves, wide sources, renewable, pollution-free etc. Now steam methanereforming (SMR) for hydrogen production process is the most mature inindustrialization, as its relatively harsh reaction conditions, at present, to improvehydrogen yield process optimization is one of the hot topics. SMR needs an amount offossil fuels, the research of suitable clean heat source shows the developing directionof MSR for hydrogen, so it is important to improve the technique that utilize solarenergy as external heat source for methane steam reforming.By simplifying SMR for hydrogen production process and selecting theappropriate unit operation model and thermodynamic method in the process simulationsoftware Aspen Plus, the simulation of SMR for hydrogen production system wasaccomplished in this work. Effect of the water-carbon ratio, operating temperature,operating pressure in the reactor on hydrogen yield was researched. The results of thesimulation showed that hydrogen yield was increased with increasing of water-carbonratio. When the pressure was lower, the curves of operating temperature vs. hydrogenyield in the reforming reactor (R1) were similar to the exponential function. But whenthe pressure was higher, the relation between them was quadratic function. When thetemperature was lower, the curves of operating pressure vs. hydrogen yield in the R1were similar to the exponential function. However, when the operation temperaturewas higher, the relation between them was quadratic function. The result was inagreement with the reactions of SMR and transforming. It provides2optimizedsolutions to improve the production process by simulating and analyzing anddeveloping the entire process: different reaction stages in series and single reactor witha partial recirculation, both solutions could increase the methane conversion or reduce operating temperature.In order to study the differences between solar energy as external heat source andtraditional fossil fuels for hydrogen production process, influence of external heat onSMR for hydrogen production were discussed. Assuming3kmol/h as methane feedflow rate,0.25Gcal/h as external heat, methane flow rate of R1outlet was0.002258Kmol/h, hydrogen production was9.495Kmol/h, methane conversion of99.92%havebeen obtained. Combined with the thermal simulation of methane combustion process,effects of solar contribution on hydrogen production process were obtained indirectly.With the increasing of the proportion of solar heat, methane conversion was increasedwhile carbon dioxide emissions were reduced. If the external heat source was providedby solar totally, compared with the traditional SMR process for hydrogen, CH4methane was increased from71.76%to99.92%, CO2emissions were reduced from1.6798Kmol/h to0.5023Kmol/h. According to the simulation of the process, it has afar-reaching significance for guiding the practical industrial production, and couldprovide theoretical basis to the improvement of energy-efficient and to thedevelopment of the production process.