The dust removal methods of the pulse jet bag filter can be divided into online and offline. Dust collectors with tens of thousands of air volume often use online dust removal, and dust collectors with hundreds of thousands of air volume often use offline dust removal. On-line dust removal is to remove dust while the filter bag is filtered; offline dust removal is to separate filtration and dust removal. The filter bag does not clean the dust, and the filter bag does not remove the dust. The dust removal is relatively high and the equipment is expensive.
The pulse cleaning system can be divided into timing control and resistance control. Timing control means that the pulse period is fixed, and the cleaning method does not fluctuate with the actual operation factors. It requires high initial adjustment. If the adjustment is not good, it will cause frequent spraying, reduce the service life of the filter bag and the diaphragm, and a long time interval. Blowing will affect the operation effect of the dust collector. Resistance control means that the design resistance of the dust collector is used as the operating point of the control instrument, so that the time of dust removal is related to the running resistance of the dust collector. When the pressure difference between the clean air chamber and the dust-containing chamber reaches a value (usually about 1000 to 1300 Pa), the dust removal starts. This method of constant resistance control dust removal can avoid the shortcomings of timing control and make the frequency of dust removal closer to the actual operation of the dust collector.
Due to the high concentration of dust-containing gas to be processed in the food and feed industry, a large part of the dust collector is used as an intermediate grading processing equipment, and the frequency of dust removal is high. There is no advantage in resistance control compared with timing control. Timing control cleaning can also avoid the problem of misoperation and failure caused by resistance control.
The pulse jet dust collector mainly uses the compressed air in the pressure air bag as the cleaning energy source, so that when the electromagnetic pulse valve is activated, a pulsed airflow is formed to pulse from the top of the filter bag to the bottom of the bag. The purpose is to shake the combined material on the outside of the filter bag into the dust hopper of the dust collector through pulse shaking. If the pressure or flow is insufficient and the dust removal force cannot reach the bottom of the filter bag, the material cannot be peeled off, forming local dust accumulation, resulting in equipment resistance, uneven filter material load, etc., and shortening the life of the filter bag. On the contrary, if the cleaning force is too strong, the fine particles that have penetrated into the surface of the filter material will be knocked out of the surface, resulting in secondary dust. At the same time, the filter bag may break due to excessive friction with the cage due to too strong oscillation force.
Therefore, regardless of the use of high, medium, or low pressure compressed air sources, the cleaning power and flow rate of the equipment are reasonably configured according to the process, soot and filter material properties.