Study On Enhanced Reforming For Hydrogen Production In Fluidized Bed Reactor Based On Medium Temperature Adsorbent

Environmental issues and consequent reductions in fossil fuel reserves have spurred the pursuit of renewable energy,and ethanol reforming process provides an effective way to reduce fossil energy consumption.In order to increase the utilization rate of ethanol and the hydrogen yield,a sorption-enhanced reforming method was developed.The fluidized bed reactor has good mass transfer and heat transfer characteristics and is suitable for the field of hydrogen production by reforming in the presence of gas-solid two-phase flow.Since the Dense Discrete Phase Model?DDPM?method has the advantages of the Lagrangian method and is suitable for large systems,the DDPM method has a good application prospect.Therefore,based on the DDPM method,the hydrogen production process of ethanol sorption-enhanced reforming in a fluidized bed reactor was studied.Considering that the sorption-enhanced action can promote the reaction to move toward hydrogen production while absorbing the CO₂ of the exhaust gas,construct a hydrogen production system for ethanol sorption-enhanced reforming based on the DDPM method,the ethanol was reformed in a bubbling bed under different operating conditions.The effects on the hydrogen production process were analyzed.The results revealed that the DDPM method used in this paper can accurately predict the hydrogen production of ethanol reforming.The hydrotalcite-based sorption can greatly improve the hydrogen production and provide the required heat for the reforming process.The influence of particle size distribution is examined.It is found that the bed expansion height is increased considering the particle size distribution.In addition,the impacts of operating pressure and catalyst to sorbent ratio were evaluated.The results showe that the increase of pressure,particle size and catalyst to sorbent ratio will hinder the hydrogen production.In order to further improve the sorption-enhanced effect,a multifunctional particle with both catalytic and adsorption effects was introduced,and the strengthening effect was simulated and demonstrated.It found that the use of the multifunctional catalyst reduces the heat transfer and mass transfer resistance,so that the CO₂ gas is absorbed more efficiently,the bed height is lowered,the temperature of the reaction system is increased,and the chemical equilibrium is further moved to the hydrogen production direction.The flow of the particles inside the circulating fluidized bed reactor was simulated under cold conditions.Studies shown that at the bottom of the circulating fluidized bed,the pressure in the reforming reactor is higher than that in the desorption reactor.On the top of the reactor,the opposite is true.The mass flow rate of the particles gradually stabilizes with time and reaches a transient state.The larger the amount of particles deposited,the higher the bed height in the reforming reactor,the greater the circulation rate of the particles,and the less obvious the phenomenon of large particles depositing at the bottom of the desorption reactor,the greater the amount of gas leakage in the connection.Both the circulation rate of the particles and the amount of gas leakage at the two connection ports increase as the gas velocity at the bottom of the desorption reactor increases.The hydrogen production process of ethanol sorption-enhanced reforming in a circulating fluidized bed reactor using multifunctional catalyst was simulated.The results showed that there are H₂ and CO₂ leaks at the two connection ports at the bottom and top.An increase in the gas velocity at the bottom of the desorption reactor increases the leakage of feed gas,intermediates,and H₂ at the bottom connection port.An increase in the amount of stock will reduce the H₂ mass flow at the outlet of the reforming reactor.