The dust laden air inlet of the pulse bag filter enters the dust removal box. Due to the sudden expansion of the gas, the flow rate suddenly decreases, and the coarse particles of dust settle downwards by their own gravity and fall into the ash hopper. Fine dust is adsorbed on the outer wall of the filter bag through various effects. The purified air filtered by the filter bag enters the upper box through the Venturi tube and is discharged from the outlet. The dust adsorbed on the outer wall of the filter bag accumulates thicker over time. The resistance of the pulse bag filter gradually increases, and the amount of gas processed decreases. In order to keep the dust collector in a stable state and the equipment resistance within a certain range, it is necessary to adsorb the accumulated dust outside the filter bag.
The ash removal process is carried out by the control instrument issuing instructions to each electromagnetic pulse valve according to the specified requirements, sequentially opening the valves, and blowing high-pressure air into each group of filter bags in sequence. So, the compressed air inside the air bag passes through the holes of the blowing tube and enters the filter bag through the Venturi tube (called primary air). And when the high-speed airflow sprayed passes through the Venturi tube - the injector, at the moment, the surrounding air located at the primary level is induced to enter the bag at the same time (called secondary air). Due to the strong reverse airflow formed by the primary and secondary winds, which is opposite to the filtered airflow, the filter bag rapidly shrinks, expands, and contracts in an instant, as well as the reverse effect of the airflow, gradually removing the dust adsorbed on the outside of the bag wall. Due to the fact that high-pressure air is sprayed into the bag during dust cleaning, it is carried out sequentially between several sets of filter bags without cutting off the dusty air that needs to be treated. So during the dust cleaning process, the pressure loss of the dust collector and the amount of dust containing gas being processed remain geometrically constant. This is the nature of the pulse bag filter.
Precautions for operating pulse bag filter:
1. When starting up, the compressed air should be connected to the air storage tank first, the control power should be connected, and the ash discharge device should be started. If there are other equipment in the system, downstream equipment should be started first.
2. Regularly measure process parameters such as smoke volume, temperature, concentration, etc. If any abnormalities are found, the cause should be identified and dealt with in a timely manner.
(1) Excessive moisture can cause hydrolysis of the filter bag, so it is necessary to regularly drain the water.
(2) Especially in the cold winter, there may be icing problems that affect the overall operation of the pulse bag filter. Moreover, the usage temperature of fiberglass coated filter material is 260 degrees Celsius. Once a high temperature problem occurs, the machine should be stopped immediately to avoid burning out. In addition, some external protective measures, such as natural ventilation and other environmental conditions, should be in place.
3. The operation process is important to avoid damage and excessive use of cloth bags.
For example, in some cases of improper operation, it can cause damage to the filter bag or increase in resistance, resulting in filter bag failure, excessive emissions, and increased resistance. Alternatively, if the pressure of the pulse valve for compressed air is too high, it can cause wear and tear on the filter bag and bag cage, exacerbating the damage to the filter bag and shortening its lifespan. Additionally, the dust removal effect may also decrease.
4. The oil-water separator in the air storage tank and gas source triple component should be drained once per shift, and the oil-water separator should be cleaned every 3-6 months. The oil mist device should be checked regularly for oil storage and refilled in a timely manner.
5. When using a timed dust cleaning controller, it is necessary to regularly measure the accuracy of the dust cleaning cycle, otherwise adjustments should be made. When using a fixed resistance pulse controller, the working condition of the pressure switch, pressure tap, and whether it is blocked should be checked regularly and cleaned.
Mechanical moving parts such as reducers and ash conveying devices should be oiled and changed according to regulations. Any abnormal phenomena should be promptly eliminated.
6. When the dust removal accessories are working normally, the ash discharge device cannot stop working. Otherwise, the ash hopper will quickly accumulate dust and overflow into the bag chamber, forcing the dust removal accessories to stop working.
7. If the electromagnetic pulse valve malfunctions, it should be promptly eliminated. If there are impurities or moisture inside, it should be cleaned. If the diaphragm is damaged, it should be replaced in a timely manner.
8. When shutting down, after the process system stops, the dust removal accessories and exhaust fan should continue to work for a period of time to remove moisture and dust from the dust removal equipment. It should be noted that when the dust removal accessories stop working, the dust removal accessories should be repeatedly cleaned (manual cleaning can be used) to remove the dust on the dust removal filter bag to prevent it from being affected by moisture and sticking to the bag.
9. When shutting down, there is no need to cut off the compressed air source, especially when the fan is working, provide compressed air to the lift valve cylinder to lift the valve in the open state.
10. Pulse bag dust collector bag replacement operation method:
(1) After shutdown, hang a maintenance sign at the equipment start-up cabinet to prevent misoperation. For normal smoke and dust at room temperature, wait for a while before changing the bag. For general top suction type, carry a wrench and other tools. After personal protection is done, open the top maintenance door from the top of the dust collector to check the cage frame and cloth bag situation. Then remove the cage frame, take out the cloth bag and replace it with a new bag, and restore it;
(2) Dust collectors with high temperatures and toxic gases require forced ventilation from the exhaust fan or natural ventilation by opening the maintenance door before they can be operated.
