| Among many CO2 separation technologies,the chemical absorption method represented by organic amines is currently the most widely used.Compared with traditional monoethanolamine(MEA),binary mixed amine(NICE)absorption solvent has a 55% increase in loading and a 60% increase in circulating loading,with good application potential.However,in practical applications,NICE has problems such as unclear gas-liquid interfaces,amine escape,and corrosion of equipment.In view of this,this article has conducted targeted research,and the main work is as follows:(1)We studied the metal corrosion behavior caused by the enhanced acidity of organic amine solutions after absorbing CO2.Based on weightlessness experiments,the corrosion characteristics of monoamine solutions were investigated,and the corrosion rate of NICE under different temperature,CO2 load,and time conditions was investigated.The corrosion characteristics of MEA under the same conditions were directly compared.Research has shown that NICE solution exhibits stronger corrosiveness than MEA solution,that is,under low CO2 load,NICE solution exhibits high corrosiveness to carbon steel,and temperature increase can also accelerate this corrosion behavior.At 120 ℃ and 5 days of corrosion,the corrosion rate of50% saturated NICE solution is 2.9 mm/a,and the corrosion rate drops to 2.2mm/a on the seventh day.Through SEM-EDS and XRD characterization analysis,it was found that the main corrosion product on the surface of carbon steel is Fe CO3.After adding corrosion inhibitors,the corrosion rate of NICE solution on carbon steel was slowed down.Among them,the corrosion inhibition effect of dimethylbenzimidazole(MBI)was the best,with a maximum corrosion inhibition rate of 75% without affecting absorption/desorption performance.(2)The problem of amine liquid foaming during the countercurrent contact between organic amines and flue gas during CO2 capture was studied.Based on foaming experiments,the foaming characteristics of monoamine solutions were investigated,and the effects of different inlet flow rates,temperatures,and CO2 loads on the foaming height and defoaming time of NICE were investigated.The foaming characteristics of MEA under the same conditions were directly compared.Research has shown that as the intake flow rate increases,the foaming performance of the solution gradually increases and tends to stabilize.Increasing the temperature can significantly reduce the foaming height and defoaming time of the solution.When the temperature rises to 65 ℃,the foaming height and defoaming time of 50% NICE solution decrease to 18 cm and 22 seconds.In addition,with the increase of CO2 load,the foaming performance of the solution shows a trend of first increasing and then decreasing,and the foaming performance of NICE solution is higher than that of MEA solution.At the same time,the foaming characteristics of NICE mixed amines under different ratios were mainly investigated,and a fitting model was used to predict the foaming characteristics of the solution,with a prediction error of within 10%.By adding defoamers to improve the foaming problem of NICE solution,polyether organosilicon modified defoamers have the best effect.Without affecting absorption/desorption performance,the defoaming time of solution foaming height can be controlled within 5 seconds below 2.5 cm.(3)The amine escape behavior of the absorption solution under simulated flue gas conditions was studied.Explored the amine emission levels of monoamine solutions and evaluated the organic amine emissions of NICE and MEA solutions under different intake volumes,water washing volumes,temperatures,and CO2 loads.The results indicate that with the increase of intake air volume and temperature,the amine emissions from the solution after absorption tower and water washing increase.The washing amount has little effect on the amine emissions after the absorption tower,but when the washing amount increases from 100 m L to 500 m L,the amine emissions after washing with 50% NICE solution decrease from 38.9 ppm to 8.5 ppm;In addition,with the increase of CO2 load,the amine emissions of the solution after absorption tower and water washing decrease,and the amine emissions of the 50% saturated NICE solution after water washing are only 4.3 ppm.However,the amine emissions of NICE solution are much higher than those of MEA reference solution,and after simple water washing,they are still at a high level of amine emissions.The multi-level water washing strategy can be used to reduce the amine emissions of NICE solution.After three levels of water washing,the NICE solvent water washing removal rate reaches 99%,and the amine emissions are less than 1 ppm,eliminating the amine emissions. |
PDF Full Text Request