燃煤烟气中细颗粒物与共存气态组分对膜吸收CO2的影响

由于燃煤烟气中细颗粒物和气态污染物难以完全脱除,同时经湿法脱硫后烟气中水汽接近饱和状态,因此,有必要揭示细颗粒物及共存气态组分对膜吸收CO₂的影响。采用燃煤热态试验装置,考察了燃煤烟气中细颗粒物、SO₂、水汽对膜吸收CO₂性能的影响,并进行了实际燃煤湿法脱硫净烟气环境下的膜吸收CO₂试验。结果表明:细颗粒物随烟气通过膜组件后,部分细颗粒物可被膜截留,沉积于膜表面,导致膜吸收CO₂效率下降,其影响程度随细颗粒物浓度的降低而减弱,与细颗粒物物性有一定关系,通过有效降低烟气中细颗粒物浓度,可显著延长膜的稳定运行时间;SO₂的存在会与CO₂产生竞争吸收现象,但因烟气中SO₂含量远低于CO₂,对CO₂吸收效率影响不明显;对于水汽,只需在运行一段时间后对膜组件作气体干燥反吹,可基本维持膜组件的稳定运行。

Effect of fine particles and coexistent gaseous components in flue gas on CO2 absorption

Separation of CO₂ from wet-process desulfurized flue gas by membrane absorption has been the subject of many studies, but investigations on the membrane process are usually carried out under laboratory conditions using pure single gases or binary gas.Under real conditions, wet-process desulfurized flue gas contains impurities, such as fine particles, H₂O and gaseous pollutant, which will influence membrane performance.In this paper, a hollow fiber membrane contactor was put into operation in the wet-process desulfurized flue gas and the effects of fine particles, water vapor and SO₂ on the performance and integrity of the membrane were investigated.The results show that fine particles deposited on the membrane surface reduce CO₂ absorption efficiency, and the stability of membranes can be improved significantly by decreasing the concentration of fine particles in the flue gas.The competitive adsorption of SO₂ is not obvious since its content is much lower than that of CO₂.It will be helpful to eliminate the water vapor by drying with back blowing gas after some period of time, so that the membrane module can work with a good stability.