The precautions of dust filter bag in high temperature flue gas

The dust filter bag is one of the important parts of the bag filter. For the important precautions of the filter bag in use, the following measures are recommended:

 One, spray water mist to cool down

In order to avoid a sudden increase in flue gas temperature due to jamming of the air preheater or other flue gas combustion failures, the service life of the filter bag is very important to take measures to cool down and spray water before the dust collector. This measure is to install a set of atomizing nozzles for cooling in the flue in front of the baffle of the dust collector, and the connecting pipe of the nozzle is connected to the pressure water source through an automatically controlled solenoid valve. Under normal circumstances, the solenoid valve is closed. When an abnormal working condition occurs (the temperature of the flue gas exceeds the temperature that the filter bag can withstand), the solenoid valve is automatically opened, and the pressure water is sprayed through the nozzle and atomized, and mixed with the flue gas to vaporize and absorb heat. Smoke temperature protects the filter bag. If you adopt this kind of protection measures, you should pay attention to several points:

1. The position of the nozzle should be as far away from the bag filter as possible, because generally the smoke velocity is relatively high, the atomized water droplets and the flue gas must be fully mixed and vaporized to absorb heat (generally it takes a few seconds to fully vaporize) , In order to achieve the cooling effect. Otherwise, it is easy to cause condensation and corrosion in some places.

2. If mechanical atomization is used, the nozzle type and water source parameters should be selected so that the diameter of the droplets after water atomization can be less than 3005m, which can reach about 505m. In addition, the water quality should be good and free of impurities. Otherwise, install a filter. When not spraying water, let a small amount of air continue to enter to prevent the nozzle from clogging.

3. If gas-phase atomization is adopted, the particle diameter of water atomization and the problem of nozzle blocking are relatively easy to solve, but in particular, it is necessary to avoid the occurrence of pressurized water pouring into the compressed air system.

4. After the flue gas is sprayed with water, the particles of the water mist will coalesce and settle with the dust particles in the flue gas before vaporization, or stick to the inner wall of the flue. Therefore, when designing, it is necessary to consider the means that can be checked, and the measures that can be added to the dust or dust.

Second, the pre-coating of the bag filter

Fuel is needed when the unit starts and low-load stable combustion. In order to avoid blockage caused by the sticky bag of oil fume, powder spraying and pre-coating measures should be adopted before the bag filter is put into use. The measures include ash storage tank, silo roof dust collector, Feeder, dust suction fan, etc.

Third, the prevention of paste bags

The main reason for the paste bag is the accumulation of water or oil in the powder layer of the filter bag. In order to avoid the paste bag, a powder spraying device is installed in the front of the dust collector, and calcium oxide powder is sprayed before the flue gas enters the dust collector. After the smoke and dust are mixed, they enter the dust collector to wrap the fine dust in the smoke and the moisture in the smoke, and at the same time play the role of desulfurization and dechlorination. If the boiler tube bursts and the moisture content in the dust exceeds the value, the precipitator PLC will control the bypass operation of the precipitator; the bypass will be opened when the flue gas temperature is too low during operation. Clean the dust after the dust collector is out of operation. The above measures prevent the occurrence of the bag-sticking phenomenon.