1. Bag filter removes dust online
High-pressure pulsed air is ejected at high speed from the pulsed electromagnetic valve through the gas pipeline from the injection hole above the center of the filter bag, passing through the neck of the Venturi tube above the filter bag, including the induced secondary air, and rushing towards the inside of the filter bag along the A short impulse pressure wave is generated in the longitudinal direction of the filter bag, and the dust deposited on the surface of the filter bag is peeled off, and the dust falls into the ash bucket. The clean gas is evacuated through the purifying chamber. When the solenoid valve is de-energized, the pulsed solenoid valve diaphragm closes and stops the high-pressure pulsed air flow, and the end of a cleaning operation is completed.
The problem with on-line cleaning of bag filter is that high-pressure pulsed air generates high-pressure airflow in the opposite direction to the main airflow to rush the filter bag to shake the filter bag, remove the accumulated dust on the surface of the filter bag, and the dust falls into the lower part of the filter. In the ash hopper, it is discharged outside the unloading device. In this process, high-pressure pulsed air must overcome the resistance of the main air flow, and its strength must be weakened. The effective filter area of the dust collector is also instantaneously reduced (milliseconds). From an industrial point of view, the impact of this area reduction on the process system is negligible. In recent years, the bag dust collector of the Pak Hua Technology bag filter has been widely used in the rotary kiln exhaust gas treatment system. in.
2. Bag filter off-line cleaning
The off-line cleaning of the bag filter requires that the dust collector be designed as a multi-chamber combination to achieve chamber-by-room cleaning. When a filter room needs cleaning, the filter room is isolated from the main air flow. The filter room is isolated by setting The inlet or outlet valve is implemented. This process is maintained for about 2 to 3 minutes. As a result, the total filter area (or called the gross filter area) of the precipitator during each cleaning operation is reduced by the area of the filter cloth in one chamber, and the reduction in the total filtration area also results in an effective filtration area (or net filtration area). ). Obviously it is uneconomical and increases infrastructure investment, which is inconsistent with the wishes of the owners. In this respect, it is not as good as a bag filter to remove ash online. However, the isolation of the filter bag from the main airstream to clean the filter bag has technically many advantages:
(1) The amount of high-pressure pulsed air passing through the filter bag does not have to be large to effectively remove dust and the required pressure is low.
(2) The dust from the surface of the filter bag has enough time to fall into the ash bucket, and the chance of re-flying is very small.
(3) The frequency of cleaning decreased and the life of the filter bag was extended.
(4) The number of pulse solenoid valves is less, which can reduce the investment and maintenance workload once.
(5) The amount of compressed air required for refined ash is less, which saves energy.
(6) The dust removal efficiency is high and the dust collector can maintain a low pressure drop. As a result, the operating cost of the dust removal system is reduced.
The above-mentioned advantages of the pulse-jet bag filter due to off-line cleaning of the bag filter are proven to be correct by practice. Therefore, it can be fully applied in the rotary kiln exhaust gas treatment system.