湿法脱硫烟气带水的形成原因

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1、除雾器效率不高
1. The efficiency of demister is not high
除雾器是湿法脱硫装置中关键设备之一，它的作用就是收集经喷嘴雾化后的液滴，减少烟气带水，降低经洗涤净化后的烟气所夹带的液滴量，所以若除雾效率不高就会形成烟气带水。除雾器的除雾效果优劣对烟气中夹带的水量有密切的关系。特别是在吸收塔内烟气流场不均、烟气流速过快时，以及在除雾器效率降低时，除雾器无法有效地除去烟气中携帶的液滴，并造成已捕集雾滴的二次夹带，净烟气中留存的石膏浆液或液滴会更多。湿法脱硫系统在运行过程中，虽然除雾器可除去大部分液滴，但还是有小部分液滴随烟气排出间。由于除雾器不能完全除去浆液液滴，这就导致净烟气中必然含有一定量的浆液液滴。净烟气中的这些石膏浆液和液态水是形成烟气带水的根本原因。所以除雾器效率是形成烟气带水的主要原因。
Demister is one of the key equipment in the wet desulfurization device. Its function is to collect the droplets atomized by the nozzle, reduce the water entrained in the flue gas and reduce the amount of droplets entrained in the flue gas after washing and purification. Therefore, if the demisting efficiency is not high, the water entrained in the flue gas will be formed. The defogging effect of the demister is closely related to the amount of water entrained in the flue gas. Especially when the flue gas flow field in the absorption tower is uneven, the flue gas flow rate is too fast, and the efficiency of the demister is reduced, the demister cannot effectively remove the droplets carried in the flue gas, resulting in the secondary entrainment of the captured droplets, and more gypsum slurry or droplets will be retained in the net flue gas. During the operation of the wet desulfurization system, although the demister can remove most of the droplets, there are still a small number of droplets discharged from the room with the flue gas. Since the demister cannot completely remove the slurry droplets, a certain amount of slurry droplets must be contained in the net flue gas. The gypsum slurry and liquid water in the clean flue gas are the fundamental reasons for the formation of water in the flue gas. Therefore, the efficiency of demister is the main reason for the formation of flue gas with water.
2、烟气温度过低
2. Flue gas temperature is too low
脱硫催化剂
Desulfurization catalyst
进入吸收塔前，烟气温度为100-130℃。取消了烟气换热器以后，烟囱排烟温度比较低，所以经过湿法烟气脱硫后，吸收塔出口的净烟气温度一般为45-55℃。烟气在通过烟囱的过程中，烟温不断下降。当湿烟气温度降到饱和温度以下时，烟气中的饱和态水遇到冷壁面而冷凝，并与石膏浆液迅速凝结形成雨滴。当雨滴所受重力大于烟气浮力时，便往下沉降甚至降落在烟囱出口。特别是在阴霾天或气温、气压较低时，净烟气中携带的石膏浆液液滴便沉降在烟囱附近。所以，烟气温度和所处的湿饱和状态是形成烟气带水现象的原因之一。

Before entering the absorption tower, the flue gas temperature is 100-130 ℃. After canceling the flue gas heat exchanger, the flue gas temperature of the chimney is relatively low, so after wet flue gas desulfurization, the net flue gas temperature at the outlet of the absorption tower is generally 45-55 ℃. In the process of flue gas passing through the chimney, the flue gas temperature decreases continuously. When the wet flue gas temperature drops below the saturation temperature, the saturated water in the flue gas condenses when it meets the cold wall, and quickly condenses with gypsum slurry to form raindrops. When the gravity of raindrops is greater than the buoyancy of flue gas, they will settle down and even fall at the outlet of chimney. Especially in cloudy days or when the temperature and air pressure are low, the gypsum slurry droplets carried in the net flue gas will settle near the chimney. Therefore, the flue gas temperature and the wet saturation state are one of the reasons for the formation of water entrainment in flue gas.
3、烟囱结构不合理
3. Unreasonable chimney structure
烟囱结构不合理也是造成烟气带水的原因之一。取消烟气换热器装置后，烟气中就会携带大量冷凝水。在烟气流经烟囱的过程中，烟囱内壁上会产生凝结水，部分凝结水被烟气带出排入大气，即形成烟气带水现象。烟囱设计不合理造成烟气带水，主要体现在烟囱的形状；烟囱内壁的平整度；烟囱出口直径这三方面。
Unreasonable chimney structure is also one of the reasons for water entrainment in flue gas. After canceling the flue gas heat exchanger, a large amount of condensate will be carried in the flue gas. In the process of flue gas flowing through the chimney, condensate will be generated on the inner wall of the chimney, and part of the condensate will be carried out by the flue gas and discharged into the atmosphere, that is, the phenomenon of flue gas carrying water will be formed. The unreasonable shape of chimney is mainly caused by the unreasonable design of chimney water; Flatness of inner wall of chimney; Chimney outlet diameter.
4、环境气象条件
4. Environmental meteorological conditions
环境气象条件主要指环境温度、相对湿度和大气压力，这是形成烟气带水现象的外部原因。
Environmental meteorological conditions mainly refer to ambient temperature, relative humidity and atmospheric pressure, which is the external reason for the formation of water entrainment in flue gas.
（1）环境温度。在脱硫后烟气从烟囱排出时，如果环境温度与烟气温度相差较大，烟气不能及时扩散，饱和态水遇冷就会变成过饱和状态，与烟气中其他成分一起凝结而沉降，形成烟气带水。
(1) Ambient temperature. When the flue gas is discharged from the chimney after desulfurization, if there is a large difference between the ambient temperature and the flue gas temperature, the flue gas cannot diffuse in time, and the saturated water will become supersaturated when it is cold, which will condense and settle with other components in the flue gas to form flue gas with water.
（2）相对湿度。环境相对湿度的大小反映了环境空气的饱和程度。相对湿度越大，空气越接近饱和状态。因此相对湿度越大的地区，越易形成烟气带水现象。
(2) Relative humidity. The relative humidity of the environment reflects the saturation degree of the ambient air. The higher the relative humidity, the closer the air is to saturation. Therefore, the greater the relative humidity, the easier it is to form the phenomenon of flue gas with water.
（3）大气压力。环境大气压力越低，烟气越不容易扩散，越易形成烟气带水现象。
(3) Atmospheric pressure. The lower the ambient atmospheric pressure is, the less likely the flue gas is to diffuse and the more likely it is to form the phenomenon of flue gas with water.