预防湿法脱硫烟气带水的措施
Measures to prevent water entrainment in wet FGD flue gas
1、保证除雾器效果
1. Ensure the effect of demister
主要保证除雾器的冲洗效果，有以下几方面：
It mainly ensures the flushing effect of the demister in the following aspects:
（1）控制除雾器冲洗水压力和流量，建议在脱硫设备停运时，打开人孔门，逐个冲洗阀门进行调整。通过不断调控除雾器冲洗水流量和压力，确保满足除雾器冲洗质量要求。并且加强巡检力度，对冲洗水量和压力进行监测，发现异常情况及时采取措施。
(1) Control the flushing water pressure and flow of the demister. It is recommended to open the manhole door and adjust the flushing valves one by one when the desulfurization equipment is shut down. By continuously regulating the flushing water flow and pressure of the demister, it is ensured to meet the flushing quality requirements of the demister. And strengthen patrol inspection, monitor the flushing water volume and pressure, and take measures in time in case of abnormalities.
（2）根据脱硫系统运行工况，可适当改变除雾器冲洗水间隔时间，保证除雾器冲洗效果。
(2) According to the operating conditions of the desulfurization system, the flushing water interval of the demister can be appropriately changed to ensure the flushing effect of the demister.
（3）实际运行过程中，建议实时监控除雾器上下压差变化，确保除雾器和脱硫设备的良好运行。
(3) During the actual operation, it is recommended to monitor the change of the upper and lower pressure difference of the demister in real time to ensure the good operation of the demister and desulfurization equipment.
2、提高净烟气温度
2. Increase net flue gas temperature
湿法脱硫后的烟气温度一般只有 45~60℃，达到了湿饱和状态。在烟气排放过程中，随着温度的降低，烟气中的水蒸气将凝结成雾。利用各种烟气加热设备将烟气加热到70~80℃，可避免水蒸气的凝结，减少烟囱周围的烟气带水现象。目前已有的烟气加热技术有下述几种:直接燃烧再热法；利用冷却塔循环水余热再加热；用高温燃烧气与低温烟气混合；用换热器再加热等方法。比较可行的方法是用锅炉二次风直接加热净烟气。
The flue gas temperature after wet desulfurization is generally only 45 ~ 60 ℃, reaching wet saturation. In the process of flue gas emission, with the decrease of temperature, the water vapor in the flue gas will condense into fog. Heating the flue gas to 70 ~ 80 ℃ by various flue gas heating equipment can avoid the condensation of water vapor and reduce the phenomenon of flue gas with water around the chimney. At present, there are several existing flue gas heating technologies: direct combustion reheat method; Reheat with the waste heat of circulating water of cooling tower; Mix high-temperature combustion gas with low-temperature flue gas; Reheat with heat exchanger. The more feasible method is to directly heat the net flue gas with the secondary air of the boiler.
3、控制浆液pH值
3. Control the pH value of slurry
石灰石浆液理想的pH值是在5.5-5.7之间。当烟气中硫含量改变较大时，建议及时调控石灰石含浆量，避免pH值超标。投入过多的石灰石浆液，不但脱硫效率没有明显提高，浆液中硫酸盐和亚硫酸盐浓度过饱和，会加重堵塞现象。因此，吸收塔pH值要精细化控制，保证脱硫系统正常运行，以期在日常工作中防疫隐患发生。
The ideal pH value of limestone slurry is between 5.5-5.7. When the sulfur content in flue gas changes greatly, it is recommended to timely adjust the slurry content of limestone to avoid exceeding the pH value. If too much limestone slurry is added, not only the desulfurization efficiency is not significantly improved, but also the concentration of sulfate and sulfite in the slurry is supersaturated, which will aggravate the blockage phenomenon. Therefore, the pH value of the absorption tower should be finely controlled to ensure the normal operation of the desulfurization system, so as to prevent potential epidemic hazards in daily work.
4、控制液气比
4. Control liquid gas ratio
液气比是指单位时间内吸收塔浆液循环量与吸收塔进口烟气量的体积比，足够的液气比是保证脱硫效率的前提，但液气比偏高会使烟气带水量增多。吸收塔的液气比一般控制在13~18 L/m3为宜。因此在满足脱硫效率的前提下，液气比越小越好。对于烟气流速，当机组带大负荷时，适当减少风量，控制炉膛负压和提升风机压力，降低烟气流量与流速，控制烟囱出口烟气流速低于18 m/s，可减少烟气对液滴的携带量。
Liquid gas ratio refers to the volume ratio between the slurry circulation volume of the absorption tower and the flue gas volume at the inlet of the absorption tower in unit time. Sufficient liquid gas ratio is the premise to ensure the desulfurization efficiency, but the high liquid gas ratio will increase the water carrying capacity of flue gas. The liquid gas ratio of the absorption tower is generally controlled at 13 ~ 18 L / m3. Therefore, on the premise of meeting the desulfurization efficiency, the smaller the liquid gas ratio, the better. For the flue gas flow rate, when the unit is under heavy load, appropriately reduce the air volume, control the furnace negative pressure and lift the fan pressure, reduce the flue gas flow and flow rate, and control the flue gas flow rate at the chimney outlet to be less than 18 m / s, which can reduce the carrying amount of liquid droplets by flue gas.
综上，湿法脱硫烟气带水的形成原因是多方面的，主要有除雾器效率不高、净烟气温度、烟囱结构不合理和环境气象条件。其中除雾器效率是主要形成原因，环境气象条件是外部原因。烟气带水会造成石膏雨，对环境造成一定影响，所以了解烟气带水的形成原因，就可以根据此方面来预防。
In conclusion, there are many reasons for the formation of water in wet desulfurization flue gas, mainly including low efficiency of demister, net flue gas temperature, unreasonable chimney structure and environmental meteorological conditions. The efficiency of demister is the main reason, and the environmental meteorological conditions are the external reasons. Water in flue gas will cause gypsum rain and have a certain impact on the environment. Therefore, understanding the causes of water in flue gas can be prevented according to this aspect.
企业二维码
2022-03-26
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