基于空冷的疏水陶瓷膜冷凝器用于烟气脱湿过程强化的实验研究

Flue gas from coal-fired power plants contains profuse water vapor. The direct emission of wet flue gas may lead to visual pollution and a series of environmental problems. Herein, we report the use of hydrophobic Al₂O₃ ceramic membrane modified by n-octyltriethoxysilane to construct air-cooling condenser for flue gas dehumidification and water recovery. Compared with conventional impermeable hydrophobic steel tube, porous hydrophobic ceramic membrane can condense vapor more efficiently. With the same water contact angle of 120°, the flue gas temperature drop of the ceramic membrane is 1.3-2.5 times higher than that of the 304 steel tube. The parametric study of the hydrophobic ceramic membrane has been done. The water flux improves with the increase of flue gas flowrate, flue gas temperature and sweeping factor, but decreases with the increase of transmembrane pressure difference and sweeping gas temperature. The water recovery efficiency decreases with the increase of flue gas flowrate, transmembrane pressure difference and sweeping gas temperature, and improves with the increase of sweeping factor. The water recovery efficiency increases first, then tends to be stable, and lastly decreases with the increase of flue gas temperature. Under experimental conditions, the water flux of 0.6-5.2 kg·m^-2·h^-1 and water recovery of 7.6%-57.4% are achieved. At low cooling medium flowrate, the condensation performance of hydrophilic ceramic membrane using water cooling is better. With the increase of cooling medium flowrate, the condensation performance of the air-cooling hydrophobic ceramic membrane rapidly improves and is gradually close to the performance of the water-cooling hydrophilic ceramic membrane. Air cooling enhanced by hydrophobic ceramic membranes is promising to replace water cooling to reduce water consumption. Hydrophobic ceramic membrane condensers can efficiently recover water from flue gas to alleviate water-energy-environment collisions in industrial processes.