蒸发塔处理脱硫废水的热量衡算

Heat balance of evaporation tower for FGD wastewater treatment

湿法脱硫产生的废水杂质种类多、处理量大,其处理及回用问题亟待解决。常规的混合堆放、水力除灰、化学处理等工艺均存在一定的缺陷,喷雾蒸发法操作简单可靠,可以实现脱硫废水的近零排放,但可能由于液滴未完全蒸发对烟道和电除尘器造成腐蚀。对此,本文利用蒸发塔代替烟道蒸发,对传统喷雾蒸发法工艺进行了改进;利用MATLAB软件对蒸发塔模型进行了理论分析及热量衡算,并结合国外工业应用实例对本文热量衡算进行校核。结果表明,该热量衡算结果与工业应用实例均有较高契合度。实际应用中应结合模型对抽取的烟气流量及比例进行合理的重新分配,同时电厂应根据自身实际情况选择合适的脱硫废水处理方式。

Wastewater produced by flue gas wet desulfurization contains many kinds of impurities and the disposal volume is huge,the wastewater＇s treatment and reusing problems need to be solved urgently. Conventional methods such as mixed stack, hydraulic ash flushing and chemical processing, have certain deficiencies, while the spray evaporation method is simple and reliable in operation, which can achieve near zero discharge of the desulfurization wastewater. However, it may cause corrosion of the flue and electrostatic precipitator due to the incomplete evaporation of the liquid droplets. To solve this problem,this paper improved the conventional spray evaporation process,used evaporation tower instead of gas duct evaporation to carry out theoretical analysis and heat balance calculation for the evaporation tower model. Moreover, the MATLAB software was applied and changing curves of the evaporation wastewater amount with the flue gas flow rate and temperature was plotted. At last, the calculated heat balance was checked by using the foreign industrial application examples. The results show that, the industrial application examples agree well with the heat balance calculation results. In the practical application, reasonable redistribution of the extracted flue gas flow and its volume proportion should be performed combing with the model, and the power plant should choose the appropriate desulfurization waste water treatment process according to their actual conditions.