Simulation Study On Hydrogen Production From Methane Reforming With Carbon Dioxide Assisted By Molten Salt As Solar Heat Carrie

With the depletion of fossil fuels and the increasing greenhouse effect,hydrogen has attracted extensive attention from scientists as an energy carrier and clean fuel.At present,the most mature industrial hydrogen production technology is the methane hydrogen production process,including methane steam reforming,methane partial oxidation reforming and methane carbon dioxide reforming hydrogen production.Among them,carbon dioxide reforming with methane for hydrogen production process is developing very rapidly.The process uses CH4 and CO2 greenhouse gases as raw material gases to produce products with a H2/CO molar ratio of 1.However,this reaction is a strong endothermic reaction,the operating temperature is high,and a large amount of fossil fuel combustion is required to provide the heat required for the reaction.Therefore,the development of a clean and non-polluting external heat source has become the research direction of scientists.This paper uses solar energy to provide heat for the carbon dioxide reforming with methane reaction,which not only can it saves the combustion of fossil fuels,but it can also reduce the large amount of carbon dioxide emissions,which is extremely important for protecting the environment.In this paper,the chemical simulation software Aspen Plus is used,and the appropriate unit operation module and thermodynamic method are selected to simulate the hydrogen production process of carbon dioxide reforming with methane.The effects of different operating pressures,different reaction temperatures and different feed ratios on the CH4 content and H2/CO molar ratio in the synthesis gas,and the effects of different reaction temperatures on the CH4 conversion rate were analyzed.The simulation results show that the higher the CO2 content in the feed gas,the lower the CH4 content in the syngas.And as the conversion pressure increases,the content of CH4 will increase.However,when the reaction temperature reaches 900℃ and above,especially with the CO2/CH4 molar ratio in the feed gas reaches 1,the effect of the increase in reaction pressure on the CH4 content in the synthesis gas becomes smaller.When the CO2 content in the feed gas increases to a certain degree and the reaction temperature is constant,the main factors affecting the H2/CO molar ratio changes from pressure to CO2 content in the raw gas.As the reaction temperature increases,the H2/CO molar ratio in the synthesis gas will gradually decrease,but the CH4 conversion rate increases accordingly,and the chemical energy storage efficiency also increases.At the same time,the process of using solar energy as an external heat source to drive carbon dioxide reforming with methane to produce hydrogen is also simulated.In the SMR-CL and SMR processes,each generation of 1 kg H2 needs energy input of CH4 with value of 104.4 MJ and 180 MJ and the CO2 generated 5.65 kg and 8.69 kg in SMR-CL and SMR process respectively.Compared with the conventional SMR process,the energy input of CH4 in the SMR-CL process is reduced by 42%,and CO2 emissions are reduced by 34.98%.In four different seasons,the change in its solar share is similar to the trend of DNI.When the DNI is close to 800 W/m2,the solar energy share remains at around 40%.When DNI is lower than 800 W/m2,the solar energy share will rise or fall with the change of DNI.Energy efficiency and efficiency will also change with the change of DNI,and the overall trend is to increase first and then decrease.However,it should be noted that when the DNI reaches 850 W/m2,the energy efficiency and efficiency will slightly decrease.Compared with other hydrogen production processes,the solar photovoltaic hydrogen production process has an energy efficiency of 20%,the photoelectrolytic hydrogen production process has an energy efficiency of 35%,and the methanol reforming hydrogen production process has an energy efficiency of 50%.In SMR-CL process,the energy efficiency is increased to 67.13%.According to the simulation of the process,it can better guide the actual industrial production.The simulation results have important research significance and can provide a theoretical basis for the optimization of the hydrogen production process.