燃煤电厂湿烟气余热及水分回收技术研究

Review of water recovering technologies from flue gas in coal fired power plant

为了降低燃煤电厂脱硫后烟气中的含湿量,有效回收烟气中的水分及余热,同时解决因饱和湿烟气中水蒸气凝结引起的烟囱腐蚀、"烟囱雨"及"白烟"等问题,分析了湿烟气的热力特点及能量分布的形式,介绍并对比了冷凝法、溶液吸收法及膜法3种较为可行的湿烟气除湿工艺,论述了其技术特点、研究现状、不足及研究方向。研究表明,脱硫后湿烟气中每千克干烟气含湿量约80 g,70%余热以水蒸气潜热的形式存在,冷凝法现阶段相对较为成熟,但吸收法除湿潜力更高、膜法系统简单稳定可靠,具有非常好的应用前景,是烟气除湿工艺研究的趋势;低品位余热的经济利用途径将是燃煤电厂烟气除湿技术的一个重要研究方向。

In order to reduce the water content in scrubbed gas after FGD discharged from coal-fired power plant, to recover water and waste heat from saturated flue gas, as well as to eliminate the problems of corrosion, stack liquid discharge and plume downwash caused by vapor condensation, this paper analyzed the thermal characteristic and energy distribution in wet flue gas, and made a brief introduction and comparison of three approaches on water recovering from wet flue gas. Such methods, including condensation, liquid desiccant-based dehu- midification （LDD） and membrane were feasible for the wet flue gas dehumidification, and their technical features,research status, short- comings and research progress were reviewed. It is found that the vapor concentration in wet flue is about 80 g, more than 70% of waste heat is in the form of latent heat. Condensation method is a relatively matured technology at the present stage, while LDD method has a higher water recovery capacity and the process of membrane method is relatively simple. These technologies have a promising application prospect and represent the research trend of flue gas dehumidification. The economic way of low grade heat utilization will be one of the important research directions of flue gas dehumidification.