Experimental Study On Absorption Characteristic Of Carbon Dioxide By Multicomponent Amine Absorbents In The Hollow Fiber Membrane Contactor

In recent years,the energy consumption is increasing with the rapid growth of the world economy.The greenhouse effect of CO₂ becomes increasingly serious,energy conservation is urgent.The carbon capture and storage?CCS?is the most direct and effective method of carbon reduction.The hollow fiber membrane contactor is a new technology of absorption CO₂ process.The membrane does not participate in the reaction,and isolate of gas-liquid.Because of the absorbent selectivity in CO₂,and CO₂ concentration gradient in the gas and liquid phases,thus CO₂ transfers from gas phase to liquid phases through the membrane porous.With high rate of decarburization,simple operation,small volume membrane absorption technology,space requirement and low cost,the hollow fiber membrane contactor is one of the most promising decarbonization technologies.An experimental system of CO₂ abosrption and desorption using a hollow fiber membrane contactor with Polypropylene?PP?is designed and builted.Sevaral kinds of Amine solution is chosed for experimental study the absorption properties and characteristics of CO₂ from flue gas.The monoethanolamine?MEA?,ethylenediamine?EDA?,diethanolamine?DEA?and piperazine?PZ?are selected as CO₂ absorbents.The effects of absorbent concentration,absorbent velocity,flue gas velocity and CO₂ content in gas mixture on CO₂ absorption are investigated.The CO₂ removal efficiency of four absorbents is as follows: PZ>EDA>MEA>DEA.The influence of concentration is obvious to single CO₂ absorbent.The removal efficiency and mass transfer rate increased with the concentration of absorbent and the absorbent velocity.The results show the concentration of absorbents should not be greater than 600mol/m³.The absorbent velocity in 0.3-0.5m³/h is appropriate;The flue gas velocity for the single absorbents as follow: PZ and EDA under 12m³/h,MEA under 8 m³/h,DEA under10 m³/h.Analysis the affect from CO₂ content and number of cycles,the stability from large to small is PZ>EDA>MEA>DEA.For improve the CO₂ absorption performance and reduce the energy comsuption of single absorbent.Six kinds of hybrid absorption solution EDA+DEA,EDA+MEA,DEA+PZ,MEA+PZ,EDA+DEA+PZ and EDA+MEA+PZ were studied to evaluate the performace of each sbsorbing solution.The result shows the performace of hybrid absorption solution is higher than single absorbent.The CO₂ removal efficiency of four hybrid absorption solution is as follows: MEA+PZ> EDA+MEA>EDA+DEA> DEA+PZ.The best ratio of the mixed absorbent are 200 mol/m³EDA+500 mol/m³DEA;200mol/m³ EDA+300mol/m³ MEA;200mol/m³ DEA+300mol/m³ PZ;500mol/m³ MEA+50mol/m³ PZ.The optimum operating conditions as follows EDA+DEA liquid velocity at 0.3-0.6m³/h,flue gas velocity under 8m³/h;EDA+MEA liquid velocity at 0.5m³/h,flue gas velocity under 8m³/h;DEA+PZ liquid velocity at 0.7m³/h,flue gas velocity under 10m³/h;MEA+PZ liquid velocity at 0.5m³/h,flue gas velocity under 10m³/h.The CO₂ absorption process in membrane contactor is analyzed by the software of COMSOL Multiphysics.When absorbent velocity increases,CO₂ removal is improved.CO₂ removal shows a downward trend with increasing gas velocity or CO₂ content in feed gas.The results are in good agreement with those obtained from experiment.The CO₂ removal efficiency of three component hybrid absorption solution is higher than two component hybrid absorption solution.The best ratio of the mixed absorbent of EDA+DEA+PZ are 500 mol/m³ EDA + 50 mol/m³ DEA+ 200 mol/m³ PZ and liquid velocity at 0.7m³/h is appropriate.The best ratio of the mixed absorbent of EDA+MEA+PZ are EDA:MEA :PZ=0.4:0.4:0.2 and liquid velocity at 0.6m³/h is appropriateThe influence of SO₂ on the CO₂ absorb from flue gas is studied in this paper.The result show the SO₂ decreases the CO₂ removal effiency in different degrees with absorbent of EDA,EDA+MEA and EDA+MEA+PZ.The decrease degree is increasing with the SO₂ concentration.It can reduce the impact from SO₂ by hybrid sorbent or activating agent,appropriate concentration and increase ratio of liquid to gas.The absorption performace under the impact of SO₂ is as follows: EDA+MEA+PZ?0.4:0.4:0.2?>EDA+MEA?0.6:0.4?>EDA.