The difference between on-line cleaning and off-line cleaning of dust bag filter

Industrial dust filter bag

1. On-line cleaning of bag filter

The high-pressure pulsed air is ejected from the pulse solenoid valve through the air delivery pipe at a high speed from the injection hole above the center of the filter bag, and penetrates the neck of the Venturi tube above the filter bag, including the induced secondary air, and rushes to the inside of the filter bag. A short pulse pressure wave is generated in the length direction of the filter bag, and the dust deposited on the surface of the filter bag is peeled off, the dust falls into the ash hopper, and the clean gas is discharged out of the machine through the clean air chamber. When the solenoid valve is powered off, the diaphragm of the pulse solenoid valve closes, stops the high-voltage pulse air flow, and ends once cleaning.

The problem of on-line cleaning of the bag filter is that the high-pressure pulsed air generates a high-pressure air flow that is opposite to the main air flow to rush the filter bag to shake the filter bag and remove the dust accumulated on the surface of the filter bag. In the ash hopper, it is discharged out of the machine through the unloading device. In this process, the high-pressure pulsed air has to overcome the resistance of the main airflow, and its strength is bound to be weakened. The effective filter area of the dust collector is also reduced instantaneously (in milliseconds). From an industrial point of view, the impact of this area reduction on the process system is negligible. In recent years, the bag filter of Puhua Technology's bag filter on-line cleaning method has been widely used in rotary kiln exhaust gas treatment systems. middle.

2. Offline cleaning of bag filter

The off-line dust cleaning of the bag filter requires the dust collector to be designed in the form of a combination of multiple chambers to achieve chamber-by-chamber cleaning. When a filter chamber needs to be cleaned, the filter chamber is isolated from the main air flow. It is realized by the valve of the air inlet or the air outlet. This process takes about 2 to 3 minutes. As a result, the total filter area (or gross filter area) of the dust collector is reduced by the filter cloth area of one chamber during each cleaning operation, and the reduction of the total filter area also leads to the effective filter area (or net filter area). ) decrease. Obviously uneconomical, increasing infrastructure investment, contrary to the owner's wishes. In this respect, it is not as good as the bag filter for online cleaning. However, cleaning the filter bag in isolation from the main air flow has many technical advantages:

1. The amount of high-pressure pulsed air passing through the filter bag does not need to be large to effectively clean the dust, and the required pressure is low.

2. The flakes of dust removed from the surface of the filter bag have enough time to fall into the ash hopper, and the probability of flying again is very small.

3. The frequency of cleaning is reduced, and the life of the filter bag is prolonged.

4. The number of pulse solenoid valves is small, which can reduce one-time investment and maintenance workload.

5. The amount of compressed air required for fine ash is less, saving electricity.

6. The dust removal efficiency is high, and the dust collector can maintain a low pressure drop. As a result, the operating cost of the dust removal system is reduced.

Because the pulse jet bag filter for offline cleaning of the bag filter has many of the above advantages, and it has been proved to be correct in practice. Therefore, it can be fully applied in the waste gas treatment system of rotary kiln.