燃煤烟气中共存杂质对膜分离CO2性能影响的实验研究

利用自行搭建的膜分离实验台,考察了共存气态组分以及颗粒物对于聚二甲基硅氧烷/聚砜(PDMS-PSF)复合膜分离CO₂性能的影响.结果表明,共存气态组分中O₂对于膜分离CO₂有抑制作用;由于SO₂浓度显著低于CO₂,在短时间内对膜分离CO₂没影响;水汽可以促进CO₂的分离;燃煤飞灰细颗粒在分离膜表面沉积会导致膜性能的恶化.在此基础上,采用模拟湿法烟气脱硫系统装置,进行了燃煤湿法脱硫净烟气环境下的膜分离CO₂实验;在测试的50 h以内,水汽、SO₂和O₂的共同作用导致膜分离性能在前期有一定的提高,随着运行时间的延长,细颗粒物对膜的影响程度加大,导致PDMS-PSF复合膜的分离性能逐渐恶化,最终导致膜的CO₂/N₂分离因子和CO₂渗透速率分别下降了17.91%和28.21%.

Effects of the coexistent impurities in the flue gas on CO2 separation by membranes

The effects of coexistent gaseous components and fine particles on the CO₂ separation performance by polydimethylsiloxane/polysulfon (PDMS-PSF) flat sheet composite membranes were investigated in a simulated test-bed. It can be found that O₂ slightly inhibits the CO₂ separation performance, while the effect of SO₂ is negligible during the test time due to its low concentration in the flue gas. Water vapor promotes the CO₂ separation performance of PDMS-PSF composite membranes. The fly ash fine particles significantly deteriorate the CO₂ separation performance of PDMS-PSF membranes. Moreover, the CO₂ separation experiments by PDMS-PSF membranes with an actual flue gas from a desulfurization system of the coal-fired hot testing facility were conducted for 50 h. At the beginning, the CO₂ separation performance is slightly improved due to the combined effect of water vapor, O₂ and SO₂. With the extension of the test time, the impact of the fine particles deposited on the membrane surface increases, which gradually deteriorates the CO₂ separation performance of PDMS-PSF membrane. The CO₂/N₂ selectivity and the CO₂ permeation rate are decreased by 17.91% and 28.21%, respectively.