The proper moisture content in the dust-containing gas during use of the bag filter is an important factor for reducing the resistance of the dust collector. Increasing the relative humidity significantly reduces the resistance of the filter bag while preventing the generation of static electricity. Therefore, for the dust-removal process of filter bags with excessively low moisture content, excessive resistance, and serious electrostatic hazards, it is necessary to consider humidifying the dust-laden gas spray mist. There are three reasons for reducing resistance:
1. The dust particles that collide with the filter bag may be affected by relative humidity.
2. The adhesion between the dust particles and the filter cloth is affected by relatively moderate airflow. It is difficult to disperse the ash layer with high moisture content. This kind of dust tends to cohere with each other. The adhesion between the dust particles and the filter cloth fibers increases as the relative humidity increases. As the particle size and relative humidity increase, the initial binding force between the dust particles and the filter fibers also increases.
3. Relative humidity affects the charge of the filter fiber and the ash-attached layer. In the process of dust removal, the smoke with low humidity has a large amount of static electricity. The charge on the filter cloth or dust particles has a great influence on the resistance loss under the certain thickness of the attached ash layer.
The above-mentioned three factors can cause the dust to condense into large particles and increase the porosity of the ash layer, thereby improving the filtration performance, reducing the resistance loss of the filter bag, making the dust easy to trap, and at the same time saving a lot of energy.
Under normal temperature conditions, the wet work requires the water content of the material, or the natural water brought by the material and the moisture brought by the air under different conditions, the moisture content is not large, and the air and the material are both in saturation. In the far case, that is, the relative humidity is very small, because the glass fiber filter cloth does not absorb water, therefore, it will not hinder the normal operation of the bag filter because of the increased humidity.
At high temperatures, hydrogen and oxygen in the fuel combine to form water. In combination with natural water and water vapor in the air, it is generally several to several hundred times greater than the moisture content of air at normal temperature. The relative humidity is generally between 30-80%. When the relative humidity is higher than 80%, it is called high humidity. Under high humidity, the surface of the dust particles may form a water film to increase the adhesion, which is conducive to the capture of dust. Difficulties will arise in cleaning the bag. Therefore, it is usually stipulated that the relative humidity of the flue gas entering the bag filter is not more than 80%. On the other hand, if the humidity is below 30%, it is abnormally dry, and it is prone to static electricity, and because of its high insulation, it should not leak electricity. It will form a static electricity situation under high voltage, and thus, like high humidity, it is easy to adhere and difficult to remove dust. There is a danger of fire.
When the high-temperature flue gas containing a large amount of moisture contains acidic components such as sulfur trioxide, hydrogen chloride, or hydrogen oxide, the heat-dissipating and cooling effect of the external of the dust remover starts to trap the fine particles attached to the filter cloth and forms countless tiny particles. Void, so-called primary attachment
The layer has a porosity of 80-90% left. When the relative humidity is not more than 80%, the acid-free components of the gas will not cause condensation water and mud to die or corrode filter bags and structures. Relatively high humidity is better for dust, but it is necessary to properly control the filter cloth, so as to keep the filter cloth from sticking and easy to remove dust. It can be seen that non-absorbent filter cloth, such as glass fiber, shows that he has extremely superior dust removal performance. The right humidity is the filter cloth is not damp.
The general air is acid-free. When the moisture content is constant, the relative moderate differences appearing at different temperatures are quite different. Under the condition that the air humidity is constant, the humidity increases, and the relative humidity also increases.
Bag filter in the process of dust removal in high temperature smoke, to prevent internal condensation, especially when the bag filter starts, pay attention to the difference between the temperature of the dust collector and the temperature of the flue gas, almost any temperature of the moisture into the cold flue gas Dust collectors can cause condensation on the filter cloth. Therefore, the precipitator should be preheated before passing the flue gas and must also be kept warm. The heat preservation is not to keep the temperature of the gas in the precipitator not to drop at all, but to ensure that no dew point temperature occurs within a certain cooling limit.
The acid gas component in the flue gas increases the dew point temperature more than when it is pure water. There is a flue gas with dew point up to 200° C., and the temperature is reduced to a certain extent. The cold surface with a large temperature difference starts to stick to the ash, and the accumulated dust is lost. fluidity. Continue cooling, that is, when the flue gas temperature drops to the dew point temperature, the acid-containing condensate rapidly corrodes the structure of the dust collector and the filter bag. The salts formed by the interaction with certain components of the dust are also corrosive. Attached to the cloth bag to form a solid lump, so that the bag will lose the filtering effect, and even destroy the bag, shorten the service life of the bag, light will also make the bag The accumulation of dust on the hopper and the accumulation of dust in the hopper cause tampering with the bag, resulting in poor flow of ash deposits in the ash hopper, poor discharge, and blockage.
