Research and design of dust removal program of bag-type pulse dust collector

　　The design of the dust removal program is very important. It is designed based on the principle of back-blowing dust removal, the time of filter bag bulging and shrinking bag deformation, the size of the filter bag, the specific gravity of dust and other factors.

　　（1） If the execution time of the program and the design of the cleaning status are unreasonable, it will affect the cleaning effect and use effect of the dust collector.

　  At present, the most commonly used cleaning procedures are "two-state" (filtration ~ cleaning ~ filtration), and "three-state" (filtration ~ cleaning, static sedimentation ~ filtration) are also used. Both of these two cleaning states have problems. For example, the “three-state” cleaning force is not enough, which affects the cleaning effect; the dust shaken off during the “two-state” cleaning process has no free settlement time, and “secondary dust” and The phenomenon of "dust reattachment";  when the "dust reattachment" is serious, it will cause "out of control" phenomenon, causing the dust removal equipment to fail.

     In order to solve the problems existing in the "two-state" and "three-state" cleaning, a "combined state" cleaning method was re-studied and designed, that is, filtration~reverse blowing~filter cleaning~static sedimentation One filter. The “combined state” cleaning is a combination of the advantages of “two states” and “three states”. It has both the strength of “two states” and the static settlement process of “three states. The unique filter bag shaking process is added to the "combined state". The cleaning process in "combined state" is as follows: (l) Turn on the counter blower, after the fan is balanced, open the shut-off valve in front of the counter blower, lift the switching valve to close the air outlet, and open the counter blower. The reverse blower blows up the reverse ash cleaning airflow that is opposite to the filtered airflow. The reverse ash cleaning airflow replaces the filtered air in the filter bag in the small bag chamber, changing the pressure difference between the inside and outside of the filter bag, and the filter bag changes from "expansion" to "shrinkage" "State, peel off the dust layer attached to the surface of the filter bag.

(2) After the cleaning time, close the shut-off valve in front of the reverse blower, and lift the switching valve to open the air outlet while closing the reverse blower. The dust-laden gas enters the small bag room again, the filter bag expands sharply and shakes, and the filter bag is cleaned again.

(3) The lifting switch valve closes the air outlet and opens the reverse air outlet. At this time, the pouch chamber is sealed and closed and it is in an airless state. So that the dust suspended in the filter bag has enough free sedimentation time.

(4) The lift switch valve opens the air outlet and closes the anti-air outlet at the same time. At this time, the filter bag "expands" again and returns to the filtering state. The transition of various states is completed by the lift switch valve and the stop valve. "Stop cleaning, dust free sedimentation time" is related to the length of the filter bag, the volume and mass of dust, and the direction of movement of the back blow cleaning air flow. Generally, it takes 40s~90s for dust to settle. Since the blow-back airflow generated by the dust removal mechanism designed by us is in the same direction as the free sedimentation of dust, the dust sedimentation time can be shortened. The time of back blowing and cleaning is related to the length of the filter bag and the speed of back blowing.

    Generally, the deflation time of the filter bag is 10s~20s, and the swelling time is 5s. When designing the back-blowing cleaning program, the time required for each step is calculated and set accurately, otherwise it will affect the cleaning effect and use effect of the dust collector.

　　Pulse cleaning control principle diagram adopts the form of row and column matrix control. The electromagnetic pulse valve is connected between the row line and the column line. Through the connection of the row line and the column line, the injection control of the corresponding pulse valve is realized. The pulse cleaning control has two working modes: "automatic" and "on-site". In the "automatic" mode, the on and off of the row selection switch and the column selection switch are controlled by the PLC to realize the injection control of the corresponding electromagnetic pulse valve. In the "in-situ" mode, the spray control of the corresponding electromagnetic pulse valve can be realized through the row selection switch and column selection button on the operation panel on the on-site operation box.