Experiments Study On Glycinate-tea Absorbing CO₂from Coal-fired Flue Gas

Environmental problems caused by global climate changes had caught attention from theGovernments around the world. Excessive emission of CO₂was the main incentive whicharouses these climate changes while coal-fired power plants were centralized sources for CO₂emission. Therefore, CO₂from flue gas produced by power plant was worthy to be captured.The experimental study on the mechanism of CO₂absorption and desorption was testedby two kinds of glycine salt （SG and PG） and TEA with a single and mixture （SG+TEA andPG+TEA） in this article, and the experimental study on wettability between polypropylenefiber membrane and the solution of SG/PG/TEA, and through acyclic run in polypropylenehollow fiber membrane absorption system to test the impact factors of the removal rate andmass transfer rate of CO₂, and the comparison test study about run a continuous loop of singleand mixture，and tested comprehensively the operation regular pattern of the absorptionsolution in the membrane absorption system. This test was also used the deionized water asthe physical absorption solution. A lot of experimental data were got from this study whichprovided some theoretical basis for the next in-depth study of glycine salt and triethanolamineas absorption solution to capture CO₂and applied to actual industrial production.The results of absorption and desorption generally aligned were SG>PG>TEA andTEA>PG>SG in the test of single solution which concentration were1,2mol/L, and the rankof absorption and desorption were PG>SG>TEA and TEA>SG>PG when their concentrationwere3mol/L. The active phase desorption of the concentration were in20-40min when thesolution was boiling. As absorbing solution mixed by SG+TEA and PG+TEA, the overallabsorption and desorption effect of SG+TEA was better than PG+TEA when mainconcentration was1mol/L, the curve of SG+TEA and PG+TEA solution in the absorption anddesorption of CO₂was denser and lead to low discrimination. Just overall absorption effect of3mol/L PG+TEA was slightly better than SG+TEA when their main concentration were2,3mol/L.The single absorption of SG and PG as well as deionized water and distilled water as acontrol with polypropylene fiber membrane contact angle were greater than90°, and bothexhibit the repellent properties with the membrane in the wettability test between absorptionsolution and polypropylene fiber membrane. The contact angles of single TEA were smallerthan90°and exhibit the phenomenon of affinity membrane. The contact angle betweenSG+TEA and PG+TEA and polypropylene fiber membrane on the whole of the contact angleof the membrane were slightly smaller than a single SG and PG. Results showed that addingTEA will reduced SG and PG on the hydrophobicity of the membrane. The optimum temperature of the liquid phase was between310-317K when Acyclicrunning test under the experimental conditions; When the liquid flow rate was less than0.048m/s, the decarburization of1mol/L PG was better than1mol/L SG, contrast to theresults when the liquid flow rate was greater than0.065m/s; When the concentration of theabsorbing liquid was under1.5mol/L, the CO₂removal rate and mass transfer rate increasedmore obvious, continue to increase in the concentration of2mol/L, CO₂removal rate andmass transfer rate remained at high level but the range of increase had greatly reduced; Theremoval rate of absorption solution dicreased significantly when the flow rate of gas from0.425m/s to0.491m/s, while the removal rate of CO₂was at a high level from0.2m/s to0.3m/s; The removal rate and mass transfer efficiency of absorption solution were at a highlevel when the content of CO₂in simulated flue gas was8%-14%, and had little change in thatsituation.In the continuous experiment, the CO₂removal rate of1mol/L SG was higher than thatof1mol/L PG, and the CO₂removal rate of SG also little higher than PG when theirconcentration were2mol/L and3mol/L in early run, but the mass transfer efficiency of1,2,3mol/L SG lower than that of1,2,3mol/L PG, and the removal rate of PG surpassed that ofSG in late run. Compared two kinds of glycinate—SG&PG，the removal rate and masstransfer efficiency of TEA were much worse than SG and PG, but which was obviouslystronger than deionized water or a lot better than simply physical absorption. In the runningtest of Mixture mixed by SG+TEA and PG+TEA, when1mol/L SG and PG were added0.1,0.2,0.3mol/L TEA, the removal rate and the mass transfer rate of SG exhibit the obviouspromotion and displayed inhibition to PG. But the whole decarburization efficiency of singlePG was still slightly lower than that of single SG, and the increased amplitude of masstransfer rate for PG was slightly higher than for SG and SG+TEA when adding TEA to highconcentration solution of them.