Study On Hydrogen Power Generation System Based On Chemical Chain Combustion Heat Coupled Steam Enhanced Reforming

It is the important forward research in the current society to investigate the new principle of energy transformation and utilization and innovating the new power plant for lowering the greenhouse gas emission, e.g. CO2. This thesis conducts an intense study on the drawbacks of the improper energy utilization and huge energy penalty on CO2capture in conventional methane steam reforming on the basis of the cross field on chemical engineering, environmental engineering and engineering thermodynamics, while presenting the chemical looping combustion thermally coupled with sorption enhanced methane steam reforming for hydrogen and power cogeneration.Based on the basic principle of comprehensive and stepped utilization of chemical and physical energy in total energy system, this thesis is aimed at analyzing the main reasons of exergy destruction in dirction fuel combustion process, namely the improper energy quality utilization in combustion reaction, the huge chemical exergy destruction in combustion, and the improper utilization of reaction characters. This thesis also investigates the exergy characteristic equations in both direct fuel combustion and chemical looping combustion processes, theoretically analyzing the mechanism of fuel exergy proper utilization in chemical looping combustion system.In order to demonstrate the possibility of increasing useful work in chemical looping combustion process, this work foucses on four CO2-apture methods in energy system, i.e. pre-combustion, post-combustion, oxy-combustion and chemical looping combustion. The research results indicate that the chemical looping combustion system owns the highest exergy efficiency of50.09%, which is about9.21,5.5and7.58precentages higher than that in pre-combustion (40.88%), post-combustion (44.59%) and oxy-combustion (42.51%), respectively.To deal with the major problem, i.e. huge energy penalty, in conventional methane steam reforming for hydrogen production, this work presents the chemical looping combustion thermally coupled with sorption enhanced methane steam reforming for hydrogen and power cogeneration system on the basis of "decreasing the penalty on CO2separation and increasing the hydrogen purity in reformer gas". In terms of the thermodynamic second law analysis, this work conducts the law of internal energy transformation and utilization and mechanism for decreasing the captical cost on hydrogen production in novel cogeneration system compared with the conventional steam methane reforming. The research results indicate that this novel cogeneration system has a higher exergy efficiency of83.1%, which is obviously reducing the exergy cost of14.4%in comparision to that of conventional methane steam reforming.