Cause Analysis and Solution of Dew Condensation in Pulse Bag Dust Collector

The condensation, refers to the phenomenon that saturated moisture is precipitated from moist air at a certain pressure and temperature. The temperature point at which moisture is released is called the dew point.

The higher the gas pressure at saturation, the lower the dew point. The higher the moisture content in the air, the higher the dew point temperature. When the moisture content in the air is constant and the moisture-containing air temperature is lower than the dew point temperature, moisture will be precipitated in the supersaturated air, that is, condensation will occur; when the air temperature is higher than the dew point, moisture will not be precipitated, so No condensation will occur. In addition, if the flue gas contains SO2 components, the more SO2 content, the higher the dew point of the flue gas.

1. There is air leakage in the dust collector
Due to the phenomenon of air leakage in the dust collector, a large amount of cold air from the outside is sucked into the dust collector, so that the local air temperature of the dust collector drops sharply, and the water in the air is analyzed, resulting in condensation.
There are many reasons for the air leakage of the dust collector. There are leakage welding phenomenon of the dust collector shell during the production and installation process, which causes air leakage, air leakage caused by the unsealing of the unloading device, and air leakage caused by the leakage of non-standard pipes during the installation process. There are air leakage and so on due to the poor sealing of the flange connection between the dust collector and the non-standard pipeline.

2. The moisture content in the flue gas is too high
When the moisture content in the treated flue gas is too high and the supersaturated water is analyzed, condensation will occur. This phenomenon is particularly prominent in the kiln tail dust collector of the cement dry process line. Since the flue gas at the kiln end of the cement dry process line is generally cooled and tempered by a humidifying tower, when the amount of water sprayed is too large, it will cause the smoke in the flue gas. Condensation occurs when moisture is supersaturated.

3. The flue gas temperature is too low
When the temperature of the flue gas treated by the dust collector is close to or lower than the dew point temperature, condensation will also occur.

4. The temperature of the pulse injection gas is too low
The dust collector uses compressed air in the pulse jet cleaning process, and the compressed air itself is saturated air with a relative humidity of 100%. Since its air pressure is greater than atmospheric pressure, the dew point converted to atmospheric pressure is lower than the ambient dew point, and there is a tendency to dew condensation. When the temperature of the compressed air is not much different from the temperature of the flue gas inside the dust collector, dew condensation generally does not occur.

However, in winter, especially in northern my country, when the temperature is usually minus ten or tens of degrees, the temperature difference between the compressed air injected by the pulse and the flue gas inside the dust collector is too large. When the compressed air is instantly injected into the filter bag The temperature also drops sharply, usually in the form of a white mist spraying a high-speed airflow of condensed water mist, and the temperature within a certain distance below the nozzle is relatively low, forming a low temperature area.

Since the compressed air in the nozzle is saturated air, the temperature drop after the gas is ejected will cause the water to separate out and cause condensation in the area. At this time, the condensation is mainly concentrated on the surface of the filter bag being sprayed, and the dust adhering to the surface of the filter bag is bonded due to the absorption of the moisture precipitated by the condensation, which in turn blocks the pores of the filter bag, causing the dust collector to not work properly.

5. The dust collector shell has no thermal insulation measures or the effect is not good

The shell of the dust collector is generally made of steel plate structure, and the thermal conductivity of the steel plate is very large. When the temperature of the outside air and the temperature of the flue gas inside the dust collector form a large temperature difference, condensation will occur on the shell of the dust collector. If the shell of the dust collector does not take thermal insulation measures, or although thermal insulation measures are taken, but the effect is not good, the condensation phenomenon of the dust collector is inevitable.