Views: 8 Author: China Xicheng Publish Time: 2021-06-19 Origin: China Xicheng
To choose a suitable wet scrubber type, it is necessary to go through investigation and research, fully understand the operating conditions, and choose a reasonable tower type with better characteristics. -Generally speaking, there are many choices of wet scrubber towers that meet the requirements of production tasks at the same time, but they should be summarized and considered from the economic point of view, production experience and detailed conditions. Some considerations when choosing are listed below.
1. Elements related to physical properties
2. Elements related to operating conditions
Small towers are cheaper for packed towers. Generally, packed towers should be used if the tower diameter is less than φ 800 mn.
The following are some of the key considerations when planning a wet scrubber, including:
1 Empty tower flow rate
The smaller the airflow velocity of the hollow spray dust collector, the more favorable it is for the absorbed power, which is generally 1.0~1.5m/s. 2 Packing layer thickness
In the cross-flow simulated filler scrubbing dust collector, the thickness of the filler layer clamped by the two layers of screens is generally less than 0.6m, and the maximum is 1.8m.
The height of the stopping bed of the packing beads H is about 5-8 times the diameter of the spherical packing, the maximum stopping bed height
The function of the nozzle is to spray the scrubbing liquid into fine droplets. The reasonable structure of the nozzle can fully atomize the scrubbing liquid and increase the gas-liquid contact area. On the contrary, for all huge towers, the scrubbing liquid is not well sprayed, and the gas-liquid contact area is still small, which affects the purification power of the equipment. The ideal nozzles are as follows:
1. The ejected droplets are small, and the size of the droplets depends on the nozzle structure and the pressure of the scrubbing fluid
2. The large cone angle of the sprayed liquid will cover a large area, and the entire section of the tower will be covered not far from the nozzle. A swirler is installed in the nozzle to make the liquid not only move in the forward direction, but also rotate, which helps to spread the sprayed liquid, and also helps to loosen the sprayed liquid into a fine mist.
3. If the required hydraulic pressure is small, the hydraulic pressure is low, and the power consumption is low.
Generally, the number of nozzles is arranged according to the size of the pipe diameter and cross-sectional product. The cross-sectional area of a single nozzle is multiplied by the number of nozzles and is less than 2/3 of the cross-sectional area of the water pipe.
4. Tower diameter calculation
D is the diameter of the tower, m; Q is the amount of gas processed per hour, m/h; v is the speed of flue gas passing through the tower, m/s.
5. Gas-liquid ratio selection
The water-to-air ratio is the control condition closest to the purification power, and its unit is kg a/m. When other conditions remain unchanged, the greater the water-to-air ratio, the higher the purification power, especially when the water-to-air ratio is below 0.5, the purification power increases sharply as the water-to-air ratio advances. This is because the water volume cannot meet the absorption requirements. , But after increasing to a certain extent, add
The amount of spraying is no longer necessary, but will increase the amount of air trapped. The test admits that the water-to-air ratio of the hollow tower should be 0.7~0.9. Of course, this is related to many conditions, for example, the scrubbing liquid is not well atomized, even if the water vapor is relatively large, the mass transfer effect is still not good.
6. Pump selection
The selection basis of water pump should be considered from five aspects according to the process flow and water supply and drainage requirements, including liquid transport volume, equipment lift, liquid properties, pipeline installation and operating conditions, etc.
Detailed operation of the selected water pump
1. According to the installation, terrain conditions, water level conditions, and operating conditions of the equipment, it is recognized to choose horizontal, vertical and other types (pipeline, submersible, submerged, non-blocking, self-priming, gear, etc.) .
2. According to the nature of the liquid medium, it is recognized that the clean water pump, the hot water pump is still an oil pump, a chemical pump or a corrosion-resistant pump or an impurity pump, or a non-clogging pump may be used. For pumps installed in explosive areas, corresponding explosion-proof motors should be selected according to the grade of the explosive area.
3. According to the flow rate, it is recognized that the single-suction pump is still a double-suction pump; according to the head level, the single-stage pump is still a multi-stage pump, and the high-speed pump is still a low-speed pump (air conditioning pump). The power of the multi-stage pump is better than that of a single-stage pump. If the single-stage pump and multi-stage pump can also be used, the single-stage pump should be selected first.