Numerical Simulation And Optimization Of Adsorption Separation Process For Carbon Dioxide

The greenhouse effect caused by carbon dioxide has aroused to concern widespread. Combustion of fossil fuels is one of the major sources of carbon dioxide emissions, so the capture of carbon dioxide from the flue gas has become one of the main techniques to control the growth of carbon dioxide in the air. To develop a cleaner, stable and efficient new method of trapping carbon dioxide has become a hot research area for scientific community. Due to energy demand for the rapid increasement of economy in China, the number of coal-fired power station has ranked the first in the world. Therefore, to explore the new technology of energy-efficient capture of carbon dioxide in coal-fired boiler flue gas is the urgent tasks to achieve the targets reducing China's carbon dioxide emission and an important research direction of experts and scholars. Simultaneously, it has important application value.Based on previous studies on carbon dioxide adsorption separation technology, This paper made a theoretical analysis of the carbon dioxide absorption and separation process through making the physical model, which was calculated using numerical methods,such as Fortran and Comsol Multiphysics. Calculation and analysis was also carried out on carbon dioxide pipeline.Firstly, comparing the actual fixed-bed adsorption process with ideal's in physical model of fixed bed adsorption of carbon dioxide, this paper found operating time is far below the ideal state of packed bed operation time. The operation time is 70.7% of ideal fixed-bed.Secondly, establish the physical model of pressure swing adsorption carbon dioxide, using Comsol Multiphysics software simulation analysis carbon dioxide absorption process. The study found that the mass transfer zone length decreases with the feed flow rate increases and growth, with the diffusion coefficient and the porosity of the bed decreases and growth, and vice versa shortened. In the adsorbate nature of the feed composition and operating conditions (temperature, pressure, flow) is constant, the mass transfer zone length unchanged. Mass transfer zone length of the adsorbent bed design of the existence of the impact of setting a good adsorbent bed can be used for a variety of different adsorbate adsorption, adsorbate_concentration in the adsorption bed length can be ignored.Subsequently, based on the composition of carbon dioxide in flue gas and product requirements of technical indicators, a preliminary simulation for the adsorption process of the carbon dioxide from flue gas was made, and determined when the carbon dioxide level is 10% and recovery purity is 99.8% required the adsorption bed length is 0.3m.Finally, the flow of carbon dioxide in the sub-isothermal and adiabatic critical state was calculated and analyzed, the results show that isothermal transport mode is better than the adiabatic transport mode. In the case of the pressurized carbon dioxide can be transported hundreds of kilometers using subcritical isothermal pipeline, which can meet the transport requirements of carbon dioxide.