ZJN Series Introduction - Bag Filter (7)

Introduction for the main ash cleaning method of bag filter - pulse cleaning.

The perforated plate (flower plate) for fixing the filter bag is placed in the upper part of the dust collector case. Above each row of filter bags, there is an jet pipe on which the air injection hole (mouth) is opened against the center of each filter bag. The other end of the jet pipe is connected with a pulse control system composed of pulse valve, control valve, and compressed air storage tank. According to the specified time or resistance value, the pulse is sprayed to clean under the order of the automatic control program.

The filter bag applies the externally filtered ,and the inside is provided with a skeleton support. In that instant of ash cleaning , it can induce the air with volume of several times the amount of the jet air when the high speed jet airflow passes through the top of the filter bag. Then blowing together into the filter bags, forming an air wave, which will cause the filter bag expand sharply from top to bottom. The strong air flow which gathered during this process will clear and drop the dust. Generally, the pulse period can be adjusted to 1 minute to a few minutes.

It can be divided into three types according to the flow direction of the pulse blowing airflow and the purifying airflow: co-current spray, counter-current spray and opposite spray. Co-current spray: both airflow directions are same, and the clean air is discharged from the bottom of the filter bag after purification. Actually the spray type of opposite spray is divided into two parts, half counter-current spray and the other co-current spray.

When spraying, the dusted filter bag does not catch dust. Because the spray blowing time is short, and the filter bag is sprayed and cleaned for the first time row by row, dust collection could almost be treated as continuously working. Thus we can apply the compartmental structure for off-line cleaning, or perform online ash cleaning without a compartment.

With strong and good cleaning effect, the pulse cleaning can increase the filtration velocity. The strength and frequency are adjustable. The cleaning effect is related to the atmospheric pressure venturi structure and whether the jet center line and the filter bag center line are consistent. If with a long filter bag, a good cleaning effect can be obtained with a better blowing device as well.

Because of the strong cleaning effect, it is also effective for the viscose filter. The felt filter materials also has been widely used. In terms of microscopic view, it can be used for effective filtering, so that the apparent filtration speed will be higher than the woven fabric, accordingly to realize the device miniaturization.

The pulse jet device applies compressed air as the energy source. In the cold region, the water vapor in the compressed air is easy to condense and affect the injection effect. Therefore, it should not be placed outdoors, and the corresponding technical measures should be taken to prevent from condensation or freezing.

Finally, we will successively introduce the other dust cleaning methods such as air ring back-blowing cleaning, air box pulse cleaning and pulse back-blowing cleaning. So stay tuned!