1 Introduction
Cartridge-type dust collectors were already present in Japan, Europe and the United States as early as the 1970s. They have the advantages of small size, high efficiency, low investment, and easy maintenance. However, due to their small capacity, it is difficult to combine them into large air volume equipment. The low filtration speed and narrow application scope have only been applied in food, welding and other industries, so it has not been widely promoted for many years. In recent years, with the continuous development of new technologies and materials, Japanese and U.S. companies have represented improvements in the structure and filter materials of precipitators, making filter cartridges widely used in cement, steel, and electricity. In the food, metallurgy, chemical and other industrial fields, the overall capacity has increased several times, becoming a large-scale dust collector (GB6719-86) with a filtration area >2000m2. It is a solution to the difficulty of collecting ultra-fine dust by conventional dust collectors, high filtration speed, and poor cleaning. , filter bag wear and tear, high cost of the best solution, and the existing bag type, electrostatic precipitator on the market has an effective filter area, low pressure drop, low emissions, small size, long service life Such characteristics have become a new direction for the development of industrial dust collectors.
2. Structure of cartridge filter
The structure of cartridge filter is composed of air inlet pipe, exhaust pipe, box, ash hopper, cleaning device, diversion device, air flow distribution plate, filter cartridge and electric control device, similar to air bag pulse bag dust removal. structure. The arrangement of the filter cartridges in the dust collector is very important. It can be arranged vertically on the flower box plate or tilted on the flower board. From the cleaning effect, the vertical arrangement is reasonable. The lower part of the panel is the filter chamber and the upper chamber is the air chamber pulse chamber. An airflow distribution plate is installed at the inlet of the dust collector.
3. Dust collector working principle
After the dust-laden gas enters the ash hopper of the dust collector, a sudden increase in air flow section and the role of the air distribution plate cause a part of the coarse particles in the air flow to settle in the ash hopper under the action of inertial and inertial forces; dust particles with fine granularity and low density enter the dust filter room. Through the combined effect of Brown diffusion and sieve filtration, dust is deposited on the surface of the filter material, and the purified gas enters the net gas chamber and is exhausted by the exhaust pipe through the fan. The resistance of filter cartridge dust collector increases with the increase of the dust layer thickness on the filter material surface. When the resistance reaches a certain value, it is cleaned. At this point, the PLC program controls the opening and closing of the pulse valve. First, the lift valve of a sub chamber is closed, the flow of the filtered air is cut off, and then the electromagnetic pulse valve is opened. The compressed air and the short time are rapidly expanded in the upper box body and flow into the filter cartridge to make the filter cartridge. The expansion deformation generates vibration, and the dust attached to the outer surface of the filter bag is peeled off and falls into the ash hopper under the action of the reversed flow scouring. After the cleaning is completed, the electromagnetic pulse valve is closed, the poppet valve is opened, and the chamber is restored to the filtered state. Ash removal is performed in each chamber in turn, starting from the first chamber of ash cleaning to the next ash cleaning as a cleaning cycle. The falling dust falls into the hopper through the ash valve. In this process, the filter cartridge must be replaced and cleaned on a regular basis to ensure the filtering effect and accuracy, because in the filtration process, in addition to being blocked, dust will be deposited on the surface of the filter material, increasing the resistance, so it is normally replaced properly. The time is three to five months