The normal operation of bag-type dust collectors

A large number of facts have proved that if machinery cannot be operated normally, even excellent equipment cannot fully exert its technical capabilities. Instead, various faults may occur, it may be difficult to operate normally and its service life may be shortened. Therefore, it is completely necessary and extremely important to implement operation management for bag-type dust collectors and strictly require their correct operation.

1. Precautions during operation

In order to ensure the long-term stable operation of the bag filter in the asphalt mixture mixer, the following matters must be noted during the use of the bag filter:

Before purchasing a bag-type dust collector, it is necessary to thoroughly study the technical data related to the dust collector based on the production process conditions, consider whether it can meet the strict environmental protection regulations and approximately five years of operating costs, and conduct a technical and economic comparison based on comprehensive indicators to determine the specifications and models of the bag-type dust collector.

2) Operate the bag filter strictly in accordance with the requirements of the user manual provided by the manufacturer. Do not change the operating conditions at will to prevent malfunctions caused by changes in operating conditions.

3) It is necessary to fully understand and master the technical requirements and operating procedures of bag-type dust collectors.

4) Always pay attention to the working condition of the filter bags. If any abnormality is found, analyze the cause in time and handle it properly.

5) Regularly observe and record the temperature, humidity and pressure of the gas entering the bag filter to ensure its operation under the specified technical parameters. It is strictly forbidden to operate the bag filter at a temperature lower than the dew point of the gas.

2. Correct operation

2.1 Initial operation and debugging

The initial operation of a bag-type dust collector refers to the operation within two months after the start of use. During this period, the bag-type dust collector is prone to malfunctions. Only by promptly identifying problems and properly resolving them can the stable operation of the bag-type dust collector be achieved.

1) Control the air volume. To stabilize the pressure loss of the filter bags, during the initial operation of bag-type dust collectors, a significant increase in air volume is often adopted to ensure that the gas passes through the filter bags smoothly. At this time, if the motor of the fan is overloaded, the air volume can be adjusted by using the main valve. This situation can take as little as a few minutes or as long as several days to reach a normal state. So when starting to adjust the air volume, it is best to observe the pressure gauge. You can also calculate the corresponding air volume value from the reading of the ammeter on the control panel.

2) Temperature regulation. Bag-type dust collectors generally have no problem handling normal-temperature gases, but when dealing with high-temperature and high-humidity gases, especially during the initial operation, if the filter bags are not preheated, they are prone to getting wet, the mesh will be severely clogged, and even the operation may not be possible. In addition, if the filter bags are not dried thoroughly, condensation often occurs. It is difficult to accurately predict the dew point of bag-type dust collectors. Therefore, attention must be paid to the clogging of filter bag mesh and the corrosion of the inner surface of the dust collector casing caused by condensation.

3) Adjustment of compressed air pressure. Both the reverse-blowing bag filter and the pulse-jet bag filter controlled by pneumatic valves use compressed air as the power source to complete the dust cleaning process. Therefore, only when the pressure and volume of the compressed air are adjusted to the design values can the normal start-up and operation of the bag filter be guaranteed.

4) Dust removal efficiency. After a dust adsorption layer forms on the filter bag, its dust removal efficiency should be better. However, due to the increase in the initial treatment air volume, the bag-type dust collector is in an unstable state. Therefore, it is best to measure the dust removal efficiency after several days of operation or one month. Under the stable state of the bag filter, the dust removal efficiency for very fine and low-concentration dust particles is generally above 95%.

5) Dust discharge. The dust collected in the ash hopper can be discharged either automatically or manually, but it must be discharged in the prescribed sequence. During the initial operation period, ash is often not discharged for one to several days until the maximum dust holding capacity of the bag filter is reached. At this point, the ash is discharged in sequence. If the cycle of dust discharge is inaccurate, the bag filter cannot form a stable operating state. Therefore, the data obtained from measuring the efficiency of the dust collector can be used to calculate and determine the cycle and quantity of dust to be treated, but this needs to be confirmed or corrected in production practice.

6) Adjustment of the filter bag lifting device. After 1 to 2 months of use, the filter bags of the bag-type dust collector will become loose and elongated. On the one hand, adjacent bags are prone to contact and wear each other out. On the other hand, the loose parts of the filter bags will develop holes due to dust accumulation and friction. In addition, due to the disappearance of the pulling force, the cleaning effect deteriorates, resulting in the clogging of the filter bag mesh. Therefore, the bag-type dust collector should be inspected and the working length of the filter bag lifting gear should be adjusted 1 to 2 months after installation. Although the spring-type filter bag hanging mechanism does not require adjustment, it should still be inspected frequently and unsuitable springs should be replaced if necessary.

7) Control of gas temperature. Sudden changes in gas temperature can cause variations in the fan's rotational speed, resulting in an unbalanced operating state and vibration. Moreover, if the temperature drops sharply when the operation stops, vibration will also occur when it is restarted. Therefore, the gas temperature should be stabilized as much as possible.

2.2 Normal load operation debugging

During the normal load operation of bag-type dust collectors, changes in operating conditions or malfunctions will affect the normal operation of the dust removal system. Therefore, it is necessary to regularly inspect and appropriately adjust the bag filter to extend the service life of the filter bags, reduce power consumption, and maintain its best operating condition with the lowest operating costs.

1) Use testing instruments to grasp the operating status. The operating status of bag-type dust collectors can be judged by the values and their changes displayed by testing instruments, such as system pressure, inlet gas temperature, voltage and current of the main motor, etc. The situations that can be understood through these values include: whether the dust cleaning process of the filter bags is clogged, and whether the filter bags are damaged or fall off. Whether there is any dust accumulation and whether the air volume has changed; Whether condensation occurs on the filter bag; Has the cleaning mechanism malfunctioned, such as dust leakage? Whether the fan is operating normally and whether the air volume has decreased; Whether there is any blockage or leakage in the pipeline; Whether the valve rotates flexibly and if there are any faults; Is there any leakage in the filter bag chamber and channels? Whether there is any leakage of cooling water, etc.

2) Control the variation of air volume. An increase in air volume will cause the filtration speed to rise, leading to phenomena such as filter bag damage and bag relaxation. Conversely, it slows down the air velocity in the pipeline, causing dust to deposit inside the pipe, which further reduces the air volume and affects the dust suction. Therefore, it is best to estimate the changes in wind volume in advance. The reasons for the change in the air volume of the dust removal system include: an increase in the dust content at the inlet or a relatively high viscosity of the dust. The valve opening degree for opening and closing the dust collection hood or the branch pipeline is improper. Clean the dust or carry out maintenance on a certain sub-room; There is leakage or blockage in the dust collector body or pipeline. The fan malfunctions, etc.