Process Simulation Of The ZnSI Themochemical Cycle And Experimental Research On The Production Of ZnI₂

Excessive CO2emission should be blamed for the globe climate change. The methods to cut the emission are various, including Carbon Capture and Storage (CCS), coverting it into high value products, utilizing energy-saving technology and changing the energy structure which is a fundamental solution to this problem. The ZnSI themochemical cycle is recently proposed to decompose CO2into CO. It bases on the sulfur-iodine(SI) themochemical cycle aiming at achiving the gole of decamping CO2and H2O which producing CO and H2.In this degree paper, the software Aspen Plus is used to design and simulate the process of the ZnSI cycle. Three operating parameters has been investigated about their effects on the whole system. These parameters are composition of the Bunsen reaction products, ZnI2decomposition ratio, and hydroiodic acid concentration in ZnO-HI reaction. Results show that ZnI2decomposition ratio and HI concentration in ZnO-HI reaction have little influence on the whole system, while optimizing the Bunsen reaction to obtain a high HI concentration in the over-azeotropic HI solution is effective to increase thermal efficiency. However, high ZnI2decomposition ratio and HI concentration in ZnO-HI reaction would cut the complexity of the process and benefit the system. Moreover, thermal efficiency could exceed40%under proper operating conditions.Compared with the complete system, the open-loop cycle has a great increasing in thermal efficiency. It increases from35%to79%.92.5wt%H2SO4is also the production of the open-loop cycle, which is another advantage of this system. The thermal efficiency of the cycle using ZnI2-CO2reaction is a little lower than the complete system. However, this improving would cut off the complexity of the system. The calculated thermal efficiency of the cycle using electrochemical Bunsen reaction is relatively low. The reason of it is reaction condition coming from literature has a low HI concerntration in the outlet of cathode. But it can be increased by optimizing the electrochemical Bunsen reaction. Meanwhile, the impurities can be ignored and the I2content is greatly less than the traditional Bunsen reaction. So the cycle has the potential to be further studied.As a important part of the ZnSI thermochemical cycle, it is necessary to study the reaction of ZnI2production. In this paper, some parameters have been investigated to find out their influence on this reaction by experimental research. The results indicate that increase of reaction temperature and HI concentration raise the whole reaction rate as well as the decrease of particle size and increase of Zn content in the solid reactant.