Study On Desorption CO₂ From Rich Liquid Based On Absorption

Global warming is an environmental problem that needs to be solved urgently.As one of the main anthropogenic greenhouse gases,CO₂ contributes more than 60%to greenhouse efficiency.Therefore,CO₂ emission control has received attention from all over the world.Combined with the national CO₂ emission reduction background,China,as the world's largest carbon emission country,research on CO₂ emission reduction is an urgent task.The current emission reduction methods mainly include CO₂ removal methods such as chemical absorption method,physical adsorption method,and membrane absorption method.Among them,the desorption of the absorption liquid mainly adopts thermal desorption,membrane desorption,electrolysis,and catalysis desorption and so on.The storage and utilization of CO₂ is also an important part of CO₂ emission reduction.Generally,carbon sequestration technologies mainly include marine storage,storage in oil and gas fields,fixation of carbonate minerals,and bioabsorption and utilization.As an industrial gas,CO₂ is an important resource that can be fully utilized,which not only reduces environmental pollution,but also brings great economic benefits.In this paper,the absorption,desorption and fixation of CO₂ were analyzed.The methods of membrane absorption and membrane desorption were selected for further study.A new method,calcium desorption,was proposed for CO₂ treatment,which provided a new desorption and fixation for CO₂.In the membrane absorption experiment,MDEA+MEA and MDEA+PG were used as experiment objects,MDEA solution was used as a control experiment,and a polypropylene hollow fiber membrane was used to study the membrane absorption process in a cycle experiment mode.Taking the removal rate and mass transfer rate as the parameters to measure the experiment results,the conclusion that MDEA+PG is the best absorbent is obtained.When MDEA+PG absorbent is used,with the increase of concentration,the CO₂ removal rate is gradually increased,but after reaching a certain threshold,the removal rate remains stable or even slightly decreased.As the temperature and flow rate of the absorbent increase,the effect on the removal rate increases first,and then decreases after reaching the critical value.When the temperature is 45?and the absorbent flow rate is 1.78×10^-33 m³/s,the simulated flue gas flow rate is 0.02 m/s,the best working condition of the absorption experiment can be achieved,and the CO₂ removal rate reaches 85.95%.In the membrane desorption experiment,a non-cyclical experiment was carried out on the same experiment object to investigate the effect of the rich liquid type and concentration on the desorption effect.Desorption rate and desorption rate were used as parameters to measure the test results.It was found that under the same CO₂ loading,the desorption rate of the single hydramine-rich solution MDEA was lower than that of the mixed hydramine-rich solution,and the desorption rate was higher than that of the mixed hydramine-rich solution.Then,the cycle test was carried out to confirm that the higher the desorption temperature,the slower the flow rate of the rich liquid,and the desorption effect can be optimized within a certain range.When the temperature is 50?,the absorbent flow rate is 1.56×10^-33 m³/s,and the N₂ purge flow rate is 200 mL/min,achieving the best CO₂ desorption rate of 49.5%.In the calcium desorption,a single rich liquid?MEA,MDEA and PG?and mixed rich liquid?MDEA+MEA and MDEA+PG?were used for the experimental study.The effect of different rich liquids on the desorption effect is different.The single MEA rich liquid has a CO₂ loading of about 0.6 mol/L and the Ca?OH?₂ powder is added according to the Ca/C ratio of 1:1.Under the test condition of 20?and stirring speed of 800 r/min,the optimal desorption rate can reach 85.31%.The single amino acid salt rich liquid can obtain the best desorption rate of 72.46%and the optimum temperature of 50?under the same conditions except temperature.In the desorption experiments using mixing rich liquid,it was found that the mixed liquid has a tendency to be affected by the temperature and is substantially the same as the single alcohol amine rich liquid,and thus it can be seen that the mixed rich liquid is more affected by the alcohol amine.In the secondary absorption test,the secondary absorption load of the lean liquid can reach 80%or more of the initial absorption load,and has good reusability.