The Effect Of CO₂ Concentration And Physical Properties On Carbon Dioxide Capture By Temperature Swing Physical Adsorption

The application of CO₂ capture and storage（CCS）technology plays an important role in efforts to reduce carbon emissions.The method of post combustion capture refers to the separation of CO₂ from the flue gas generated by the combustion of fuel and air in traditional steam power plants.The captured CO₂ is compressed and transported under supercritical conditions,and stored or reused as industrial raw materials.Among them,the concentration of CO₂ in the flue gas formed by the CO₂mixture is also different.There has been a lot of research on the impact of high CO₂concentration flue gas on the temperature swing adsorption process,and the impact of low CO₂ concentration flue gas on the performance of the temperature swing adsorption process urgently needs to be studied.The physical properties of CO₂ mixtures are of great significance for predicting the CCS process,and in recent years,research has mostly focused on them.The prediction of physical properties models plays a decisive role in the CCS process,and many people have conducted some research on the impact of physical properties on regulation,transportation,and storage.However,there is still a gap in research on the impact of errors caused by physical properties model prediction on the performance of carbon capture processes,this paper will study the effects of density,heat capacity,viscosity,thermal conductivity,and diffusion coefficient models on the performance of variable temperature adsorption processes with a deviation value of±20%.The model composed of coupled partial differential equations and equilibrium equations of mass,energy,and momentum balance to simulate and verify the reliability of the four-step cycle model of temperature swing adsorption（TSA）.Based on this model,a case study of low CO₂ concentration flue gas capture is extended,and the impact of increasing CO₂ concentration in flue gas on the performance of TSA system is studied.It is found that increasing concentration in flue gas does indeed improve CO₂capture efficiency,significantly improving the purity,recovery,and productivity of the system is beneficial for reducing energy consumption.However,when the concentration exceeds 25%,the purity,productivity,and energy consumption tend to stabilize,and the recovery may show a downward trend.This may be due to the continuous input of CO₂ after reaching the maximum CO₂ adsorption capacity of the adsorbent,resulting in a decrease in the recovery.For the impact of errors in physical property models on the performance of the TSA system,this article uses common physical property prediction models for basic simulation.Based on the original model,physical property models with a deviation of±20%are respectively substituted into the simulation for calculation.The results show that density,viscosity,and diffusion coefficient all affect the simulated adsorption process,thereby affecting the performance parameters of the TSA system,with a maximum deviation of 2.2%,the heat capacity and thermal conductivity affects the performance parameters of the TSA system by affecting the simulated energy process,with a maximum deviation of 1%.Finally,in order to comprehensively analyze the impact of CO₂ concentration and physical properties on the TSA system,an economic analysis was also conducted on the system,including capture costs and fixed costs,which are mainly divided into the costs of blowers,compressors,heat exchangers,adsorption columns,and adsorbents.The capture cost changes with the performance parameters of the system,so an increase in CO₂ concentration in the flue gas will also reduce the capture cost,with a minimum capture cost of$50/ton of CO₂.The deviation caused by the physical property model also has a certain impact on the capture cost,with the diffusion coefficient model error having the greatest impact on the capture cost,which can cause the capture cost to deviate by 2.89%from the original value.