超低排放背景下烟气消白技术路线研究

Research on wet flue gas plume elimination technology in the context of ultra low emission

超低排放背景下燃煤电厂大多采用湿法脱硫装置,装置出口饱和湿烟气排放后一般会在烟囱出口形成湿烟羽,对生态环境及人体健康造成不利影响。本文基于切线法对烟气及环境空气状态进行计算,确定湿烟羽消除的临界温度及混合空气当量比,比较不同烟气消白技术路线的适用环境条件及技术参数。研究结果表明,环境温度越低、相对湿度越高,湿烟羽消除难度越大。环境相对湿度为60%,脱硫塔出口烟气温度为50℃时,不采用任何措施的前提下可实现无湿烟羽排放的临界环境温度为37. 3℃,可见在常见环境条件下,调整湿法脱硫装置出口烟气状态参数以消除湿烟羽是有必要的。假设可适用的烟气最大降温幅度为30℃,最大升温幅度为30℃,仅采用烟气加热技术可消除湿烟羽的临界环境温度为12. 9℃;仅采用烟气冷凝技术可消除湿烟羽的临界环境温度为8. 7℃;采用烟气冷凝再热技术可消除湿烟羽的临界环境温度为-12. 9℃。对于空气加热混合技术,基于切线法对空气烟气混合过程进行热平衡计算,确定可消除湿烟羽的临界空气当量比。将烟气加热、烟气冷凝及空气加热技术组合使用可拓宽烟气消白适用的环境条件。

Wet desulphurization device is widely applied in coal fired power plant in the context of ultra low emission.The saturated wet flue gas emitted from the device outlet usually form wet plume at the chimney outlet,resulting in adverse effects on ecological environment and human health.In this paper,the state of flue gas and ambient air were calculated to determine the critical temperature of wet plume removal and the equivalent ratio of mixed air,and the applicable environmental conditions and technical parameters of different flue gas blanking technology routes were compared based on the tangential method.The result shows that the wet plume is more difficult to be eliminated with lower environment temperature and higher relative humidity.If the relative humidity is 60% and the flue gas temperature at the outlet of the wet desulphurization tower is 50 ℃,the critical temperature of 37.3 ℃ for wet plume elimination can be realized without any measures.So the flue gas parameters of the wet desulfurization unit should be adjusted for wet plume elimination under ordinary environment conditions.Assuming that the maximum cooling amplitude of applicable flue gas is 30 ℃and the maximum warming amplitude is 30 ℃,the critical environment temperature of smoke plume elimination is 12.9 ℃ only by flue gas heating technology,while the critical environment temperature of smoke plume elimination is 8.7 ℃ only by flue gas condensation technology and the critical environment temperature of smoke plume elimination is -12.9 ℃ by both flue gas condensation and heating technology.For air heating mixing technology,the heat balance of the air and flue gas mixing process was calculated to determine the critical air equivalent ratio of wet plume elimination based on the tangent method.The combination of flue gas heating,flue gas condensation and air heating technology can enlarge the applicable environmental conditions of wet flue gas plume elimination.