Method for the backflushing of filters
Air filters comprising thin-walled textile filter bodies have to be cleaned periodically. According to a method known to this purpose, the filtered material is loosened using pressure pulses in a flushing air flow. According to the invention, for generating the pressure pulses a plurality of small, quick-acting valves are in each case briefly opened, the opening moments being adapted to one another in such a way that partial pulses released thereby arrive simultaneously at the inlet of a flushing line common thereto.
1. Method for the backflushing of filters made of thin-walled textile filter bodies using pressure pulses in a flushing air flow, comprising:
extending a plurality of separate withdrawal lines from a compressed air container, each withdrawal line meeting at a Y-branch pipe that combines a compressed airflow from each of the separate withdrawal lines into a single flush line;
configuring each separate withdrawal line with an individual quick-acting valve for controlling the compressed airflow through each separate withdrawal line;
measuring a pressure on the wall of the filter bodies; and
generating a single pressure pulse through the single flush line, in response to a trigger effected by a correspondingly large drop in the pressure on the wall of the filter bodies, by individually opening each of the quick-acting valves to create a series of partial pressure pulses in each separate withdrawal line, the opening time of each individual valve being separately controlled so that the partial pressure pulses travel through the Y-branch pipe and arrive simultaneously at the inlet of the common flushing line as the single pressure pulse.
2. Method according to claim 1 , wherein the small, quick-acting valves are diaphragm valves that are connected to a compressed air container via withdrawal lines,
3. Method according to one of claim 1 , wherein the total opening time of the quick-acting valves is approximately 100 milliseconds per pulse.
4. Method according to claim 3 , wherein three quick-acting valves work together.
5. Method according to claim 4 , wherein the quick-acting valves tap the same compressed air container.
6. Method according to claim 5 , wherein the partial pulses meet one another at an acute angle, α, in a Y-branch pipe.
7. Method according to claim 6 , wherein the duration for the pressure increase of the pulse is approximately equal to the duration of the maximum pressure during a pulse.
8. Method according to claim 7 , wherein the compressed air is replaced by an inert gas, for example nitrogen.
9. Method according to claim 8 , wherein the filter comprises a plurality of tubular filter bodies connected in parallel, which are successively acted on, individually or in groups, by pressure pulses.
10. Method according to claim 9 , where the filtered material is removed from the filter bodies against the direction of flow of the mixture to be filtered.