Experimental Study And Performance Evaluation Of Temperature Swing Adsorption System For CO₂ Capture

Post-combustion CO₂ capture（PCC）is considered to be an important technology for reducing carbon dioxide emissions owing to its easy retrofit to power plants.Chemical absorption,adsorption and membrane separation are typical mainstreams in PCC.In technological cluster of CO₂ adsorption,temperature swing adsorption（TSA）is one of efficient methods.In recent years,the topic on energy consumption and energy efficiency of TSA is emerging as an urgent response to the possible large-scale deployment of CCS.However,most studies apply mathematical model and simulation method for performance assessment for TSA,without enough specific supports from experiment researches.Therefore,a relatively complete research on“design-test-evaluation”of a TSA system is conducted.The contents and results are as follows:（1）As key parts of the system,it is very important to analyze the heat transfer of the adsorption column and the heat exchanger.It is proposed that the total heat transfer coefficient is a function of the thermal properties of the material and the geometry of the heat exchanger and the column under certain conditions.A column with length-diameter ratio of10 and a heat exchanger with 2 pipes are designed.The result shows that the error of desorption temperature is under 5%,indicating that the scheme can be adopted.（2）Groups of experiment results are obtained for affect analysis of a lab-scale 4-step TSA system from CO₂ concentration,desorption duration,adsorption temperature and desorption temperature to the purity,recovery rate,specific energy consumption and second-law efficiency.Results shows that increasing the CO₂ concentration,desorption temperature and decreasing the adsorption temperature benefits the separation and energy-efficiency performance.There exists a reasonable desorption time demonstrates the sufficient desorption.After the time,the improvement of the separation performance is little and the energy efficiency decreases,with an excess heat input.（3）As TSA system causes carbon emissions in its life cycle,a comprehensive environmental assessment is needed to determine whether it is a carbon-negative system.Through carbon-neutral frameworks and life cycle assessment,it is showed that the carbon neutrality index of TSA system driven by electric is only 1.88%as lots of metal,plastic and electric generated from coal-fired power plants input,far from negative carbon.The carbon neutrality index of TSA system driven by solar energy is 5.9 times of the former as the system avoids the heat driven by electric,which is predicted to be a carbon-neutral system after 9 years.