脱硫废水的水质特殊且水体污染性强，脱硫废水烟道蒸发技术对脱硫废水的处理具有工程实用价值。针对脱硫废水烟道蒸发技术在工程的实际应用，建立废水雾化液滴在尾部烟道内传热传质模型，采用数值模拟的方法计算在某300 MW锅炉尾部烟道内脱硫废水的蒸发特性。首先模拟计算不同喷嘴流量时喷嘴与烟道壁面的最小安全距离，确定喷嘴在烟道截面的布置区域；结合脱硫废水总量，确定喷嘴的布置数量和位置，分析烟气温度、速度和液滴粒径对液滴蒸发时间和距离的影响。结果表明，喷嘴与壁面之间的安全距离随喷射流量的增加、烟气温度的减少、烟气流速的降低和液滴粒径的增加而增加，使安全区域面积逐渐减小，且在重力作用下，喷嘴与下壁面的安全距离最大；脱硫废水总量一定时，随喷嘴数量增加，单个喷嘴喷射流量降低，雾化液滴的蒸发时间和距离缩短，使在一定距离内可处理的废水量增加；总脱硫废水量增加时，喷嘴数量越多，单个喷嘴流量的增加值较小，蒸发距离增幅较小，最大处理能力较强；相同喷嘴数量时，烟气温度升高、烟气速度增加、液滴粒径减小均会降低蒸发时间，从而缩短蒸发距离。实际应用中应结合机组的实际情况，选择合适的喷嘴布置形式，合理设计废水烟道蒸发系统。

Desulfurization wastewater has special water quality and high water pollution. Flue evaporation technology of desulfurization wastewater has engineering practical value for the treatment of desulfurization wastewater. Aiming at the application of flue evaporation technology of desulfurization wastewater in engineering practice, the heat and mass transfer model of atomized droplets in the tail flue was established, and the evaporation characteristics of a large number of desulfurization wastewater in the tail flue of a 300 MW boiler were calculated by numerical simulation. The safe distance between the nozzle and the flue wall was calculated under different nozzle flow rates to determine the layout area of the nozzle in the flue section.Combined with the total amount of desulfurization wastewater, the number and location of the nozzle were determined， and the effects of flue gas temperature, velocity and droplet size on the droplet evaporation time and distance were analyzed. The results show that the safe distance increases with the increase of the spray flow rate and the droplet size, the decrease of the flue gas temperature and velocity and the increase of droplet size, so that the safe area gradually decreases. Due to the action of gravity, the safe distance between the nozzle and the lower wall is the largest. When the total amount of desulfurization wastewater is fixed, with the increase of the number of nozzles and the decreases of the spray flow of a single nozzle, the evaporation time and distance of the atomized droplets shorten, so that more wastewater can be treated within a certain distance. When the total amount of desulfurization waste water increases, the more the number of nozzles is, the smaller the increase value of the flow of a single nozzle is, and the smaller the increase of evaporation distance is, making the maximum treatment capacity stronger. With the same number of nozzles, the increase of flue gas temperature, flue gas velocity and droplet size will reduce the evaporation time and shorten the evaporation distance. In practical application,the actual situation of the unit should be combined to choose the appropriate nozzle layout and design the waste water flue evaporation system reasonably.

0 引言

1 脱硫废水雾化蒸发数值模拟

   1.1 数学模型

   1.2 物理模型和边界条件

2 喷嘴与壁面的安全距离

   2.1 烟气温度的影响

   2.2 烟气流速的影响

   2.3 液滴粒径的影响

   2.4 安全距离的确定

3 脱硫废水烟道蒸发工艺设计

   3.1 喷嘴组布置形式

   3.2 影响因素分析

   3.3 最大处理能力

   3.4 喷嘴布置建议

4 结论