Study On Aborption Of CO₂ In Biogas By Alkanolamine Based On Rotating Packed Bed

Biogas is a common clean energy and is widely used at China and abroad.However,the composition of biogas contains a certain amount of carbon dioxide.Due to the presence of these carbon dioxide,the calorific value of biogas is reduced and the quality of biogas is reduced.The purified biogas can be directly used in vehicle gas,which plays a significant role in the promotion of new energy vehicles.How to purify the carbon dioxide in biogas has also become an important direction.Traditional purification methods include water elution,cryogenic fractionation,membrane separation,and hot alkali,but all have various drawbacks.In response to this problem,a set of purification equipment for rotating packed bed was designed in this paper,and corresponding experiments were carried out to study different absorbents,including MEA,MDEA,MDEA+MEA and MDEA+PZ under different parameters of biogas purification experiments,draws many useful conclusions.Under current research conditions,self-designed hypergravity rotary bed purification equipment and different absorbents were used to study rotating bed rotation speed,temperature,absorption liquid concentration,operating pressure,gas-liquid ratio,intake air volume,and other parameters.As a result of the effect of CO₂ purification,it was found that the moderate rotation speed,medium temperature,low pressure,and higher concentration of the absorption liquid,the smaller the gas-liquid ratio,and the smaller the intake air amount,the better the CO₂ removal capability of the rotating bed apparatus.Using MEA and MDEA to remove CO₂ from biogas alone,the CO₂ concentration in the absorption liquid is 0.6mol/L,the temperature is 55?,the operating pressure is 0.4Mpa,the gas-liquid ratio is 20,and the air intake is 150L/h.The highest removal rate is achieved.When MEA is used as the absorption solution,the absorption effect is best when the rotating bed speed is 1000 r/min,while the MDEA absorption solution has the best effect at 900 r/min.The absorption ratio of MEA solution is better than MDEA.When using MEA to remove CO₂,the concentration of CO₂ in the outlet gas can be reduced to less than 3%,which meets the standard for vehicle gas,and when using MDEA for removal,the outlet gas The CO₂ concentration is around 10%and cannot meet the requirements.MDEA cannot be used alone to remove CO₂.After the use of MEA and PZ to activate MDEA,the effect of the mixed alkanolamine solution on CO₂ removal has been greatly improved compared to the use of MDEA alone.The CO₂ concentration in the outlet gas has dropped below 1%,and the removal rate has increased to 98%.it shows that the activation MDEA method has achieved very good results.The MDEA+PZ systemis slightly better than the MDEA+MEA system in terms of absorption effect and regeneration capability.The effect of different experimental operating parameters on the CO₂ removal of mixed alkanolamines is similar to that of single alcohol amines.It decreases first and then increases as the rotational speed of the rotating bed increases,reaching a maximum at 900 r/min.With the increase of absorption solution concentration and pressure,the absorption effect is best when the total amine concentration is 0.6mol/L and the operating pressure is 0.4Mpa.With the increase of the intake air volume and the increase of the gas-liquid ratio,CO₂ removal rate decreased,the intake air amount was 150L/h,and the gas-liquid ratio was 20,the CO₂ removal rate was the highest.With the increase of temperature,the removal rate gradually increased,the increasing range became smaller,and the absorption rate was the highest at 45?.After the temperature exceeded 45?,the absorption rate began to decrease.The alkanolamine absorption solution was subjected to a regeneration test.The regenerated absorbent had a certain reduction in the CO₂ removal capacity.The regeneration capacity was MDEA+PZ>MDEA+MEA>MDEA>MEA.