Precautions for using large offline bag filter

As the core equipment for industrial dust control, the stable operation of large-scale offline bag filters directly affects dust removal efficiency, filter bag life, and production safety. During use, it is necessary to strictly control the four core aspects of equipment start stop, operation monitoring, filter bag maintenance, and safety protection. Specific precautions are as follows:

1、 Equipment start stop: strictly follow the process to avoid damage to the filter bag

1. Pre startup inspection (key prerequisite steps)

System status check: Confirm the on/off status of valves/equipment such as offline valves, ash cleaning valves, ash unloading valves, induced draft fans, etc. (all offline valves need to be "open", and the ash cleaning valves need to be "closed"), check whether the connecting flanges and gaskets are intact, and prevent air leakage.

Filter bag and filter cage: Check whether the filter bag is installed flat (without wrinkles or damage), and whether the filter cage is vertical (without deformation or welding), to avoid early damage caused by friction between the filter bag and the filter cage.

Dust cleaning system: Check the air source pressure of the pulse valve, cylinder, and solenoid valve (usually stable at 0.5-0.7MPa), test whether the pulse spraying sequence is normal, and confirm that the dust cleaning function is effective.

Auxiliary system: Confirm the lubrication status of the ash unloader and star shaped discharge valve (bearing oil filling meets the standard), check whether the ash hopper heating device (if any) is normal, and prevent low-temperature condensation and bag sticking.

2. Start the process (staged operation)

Start the ash unloading system (ash unloader, conveying equipment) first, and confirm that there is no accumulation of ash in the ash hopper;

Start the induced draft fan (it is recommended to start at low load and gradually increase the air volume to the design value within 10-15 minutes) to avoid instantaneous high wind speed impact on the filter bag, which may cause the filter bag to tear;

After the system air volume and negative pressure stabilize (the negative pressure is usually controlled between -2000~-4000 Pa, adjusted according to the dust concentration), start the dust cleaning system and set the offline dust cleaning interval (usually 10-30 minutes/time, with each cleaning time of 0.1-0.3 seconds).

3. Shutdown process (to avoid residual dust clumping)

First, close the dust intake valve and keep the induced draft fan running for 5-10 minutes to thoroughly clean the residual dust on the surface of the filter bag;

Turn off the dust cleaning system and then turn off the induced draft fan;

After the system is fully depressurized, turn off the ash unloading system (it is necessary to confirm that the accumulated ash in the ash hopper is emptied to prevent dust from compacting the bag during the next start-up);

If the ambient temperature is below 5 ℃, the ash hopper heating device or insulation system should be turned on to prevent condensation.

2、 Running monitoring: Real time tracking of key parameters and timely troubleshooting of anomalies

During operation, the following parameters need to be monitored in real time through the PLC control system or on-site instruments. If there are any abnormalities, the machine should be stopped immediately for handling:

Reasons and handling measures for abnormal monitoring parameters within the normal range

System negative pressure -2000~-4000Pa, high negative pressure: filter bag blockage (need to shorten the cleaning interval), filter bag damage (need to stop the machine for inspection and replacement);

Low negative pressure: air leakage (check seals), induced draft fan malfunction (shut down for maintenance).

The surface temperature of the filter bag is 10-20 ℃ higher than the dew point temperature of the flue gas. If the temperature is too low, it may cause condensation and paste the bag (by turning on the heating device and increasing the flue gas temperature);

High temperature: If the temperature exceeds the excellent temperature resistance of the filter bag (such as polyester filter bag ≤ 130 ℃), emergency cooling or shutdown is required to avoid burning of the filter bag.

The pressure of the dust cleaning gas source is 0.5~0.7MPa, which is too low: the dust cleaning force is insufficient (check for leaks in the air compressor and gas source pipeline);

High pressure: Excessive pulse impact force (adjust the pressure reducing valve) can easily cause fiber damage to the filter bag.

The amount of ash discharged matches the amount of dust generated, and the amount of ash discharged suddenly decreases: the ash hopper is blocked (check the heating and vibration devices);

Sudden increase in ash unloading volume: The filter bag is extensively damaged (requiring shutdown for leakage inspection).

3、 Filter bag maintenance: extend lifespan, protect dust removal efficiency

The filter bag is the core consumable of the dust collector, and its lifespan is usually 1-3 years. Maintenance should pay attention to the following points:

Regularly check the status of the filter bag: stop the machine every 3-6 months for inspection, and pay attention to whether the filter bag is damaged, aged, or stuck

Damage: If the dust concentration at the air outlet suddenly increases, it is mostly due to damaged filter bags. The damaged filter bags need to be located (which can be checked one by one in the offline room) and replaced;

Aging: The filter bag has become brittle and fibers have fallen off, requiring replacement of the entire room (to avoid mixing old and new filter bags, which may affect the overall filtration effect);

Paste bag: The surface of the filter bag is covered with dust (often due to condensation or high dust humidity), which needs to be blown back with compressed air (pressure ≤ 0.3MPa). If it cannot be cleaned, it needs to be replaced.

Control dust inlet concentration: If the inlet dust concentration is too high (such as>50g/m ³), it is necessary to install pre-treatment equipment (such as cyclone dust collector) to avoid short-term blockage of the filter bag and reduce the frequency of dust cleaning.

Avoid over temperature/over humidity of filter bags: Choose suitable filter bags based on the nature of the dust (such as Flumets filter bags for high temperature dust, waterproof (based on actual reports) (based on actual reports) and oil proof (based on actual reports) filter bags for high humidity dust). It is strictly prohibited to exceed the excellent temperature and humidity resistance of the filter bags during operation.

4、 Enron and Environmental Protection: Risk Avoidance and Compliance with Regulations

Anran Protection:

When the equipment is running, it is strictly prohibited to open the maintenance door (to prevent negative pressure suction or dust leakage);

Before entering the ash hopper and filter bag room for maintenance, it is necessary to follow the "power-off, pressure relief, ventilation" process, check the indoor oxygen content (≥ 19.5%) and dust concentration (≤ occupational exposure limit), and wear protective equipment such as dust masks and safety helmets;

If dealing with flammable and explosive dust (such as aluminum powder and coal powder), explosion-proof (based on actual reports) (based on actual reports) type dust collectors (explosion-proof (based on actual reports) (based on actual reports) motors, anti-static (based on actual reports) (based on actual reports) filter bags) must be used, and sparks are strictly prohibited (such as welding operations during maintenance).

Environmental compliance:

Regularly monitor the dust emission concentration at the air outlet (in accordance with local emission standards, such as GB 16297-1996 "Comprehensive Emission Standards for Air Pollutants"), and immediately shut down for inspection if it exceeds the standard;

The collected dust should be treated according to hazardous/solid waste management regulations to avoid secondary pollution.

5、 Other daily maintenance

Regularly clean the interior of the equipment: clean the accumulated ash in the ash hopper and flue every six months to prevent pipeline blockage;

Lubrication and maintenance: Check the lubricating oil level of moving parts such as induced draft fan, ash unloader, and cylinder every month, and add suitable lubricating oil according to the instructions (such as 3 # lithium based grease for induced draft fan bearings);

Electrical system inspection: Check the wiring of PLC control cabinets, solenoid valves, and sensors every month to ensure they are secure and prevent equipment malfunctions caused by electrical faults.

In summary, the use of large-scale offline bag filters should be based on the principle of "prevention first, real-time monitoring, and timely maintenance". Through standardized operation and regular maintenance, it can not only protect the dust removal efficiency from reaching the standard, but also greatly reduce operating costs and fault risks.