2. The back blowing ash cleaning method is also called back blowing airflow or back pressure ash cleaning method. This method mostly adopts the split-room working system. The valve is used for active adjustment to generate airflow in the direction of airflow and filter it chamber by chamber. The back-blowing ash cleaning method mostly adopts internal filtration. Due to the action of reverse airflow and reverse pressure, the cylindrical filter bag is compressed into a star-shaped section, which causes reverse wind speed and oscillation and makes the accumulated dust fall off. Because it is an internal filter type, the tension of the filter bag should be properly adjusted to shorten the deformation of the filter bag neither too much nor too little. Therefore, a metal ring is added at regular intervals in the length direction of the filter bag to control the deformation of the filter bag, so that the dust removal effect is evenly distributed to all the filter bags. During cleaning, carry out the backwashing cleaning process for more than two times. This kind of dust removal method mostly adopts 729 filter cloth and other woven filter materials, and for removing relatively simple dust, filtering viscous filter materials can also be used. For the occurrence of reverse airflow, the pressure-resistant type is to close the outlet valve and open the back-blowing valve, so that the air is sucked by the air or the exhaust pipe of the fan to form reverse airflow; For the positive pressure type, the valve at the inlet side of the ash hopper is closed, and the back blowing valve is opened, so that air can be sucked by the intake pipe leading to the fan, forming a reverse airflow. In order to increase the blowback effect, there are also methods to install special small fans. The cleaning effect of backwashing cleaning method is weak, and the damage to filter cloth is less than that of oscillating cleaning method. Therefore, this cleaning method is often used for glass fiber filter cloth.
3. The combined cleaning method of back blowing and oscillation refers to the combined cleaning method of weak oscillation when the falling dust cannot be clearly identified by the single cleaning method of back blowing, which is often used in the practice of high-temperature glass fiber filter bags.
4. The perforated plate (flower plate) for fixing filter bags by pulse jet dust removal method is arranged at the upper part of the box, and there is a jet pipe above each row of filter bags. There is a compressed air explosion hole (nozzle) on the blowing pipe facing the center of the filter bag, and the other end of the blowing pipe is connected with a pulse control system consisting of a pulse valve, a control valve and a compressed air storage tank. According to the specified time or resistance value, pulse blowing dust removal is carried out according to the active control program. Most of the filter bags adopt the external filter type, and the inner side is provided with a supporting framework, so that dust is trapped and settled on the outer surface of the filter bag. When cleaning the dust for a period of time, when the high-speed jet airflow passes through the top of the filter bag, it can induce several times as much air as the jet airflow to blow into the filter bag together, forming a air waves, which makes the filter bag expand rapidly from top to bottom and oscillate, resulting in a strong dust cleaning effect. The pulse period can be adjusted, generally 1 minute to several minutes. According to the moving direction of pulsed jet and purified air, there are three ways: forward jet, reverse jet and reverse jet. The air flow direction of the forward spray type is the same, and the purified clean air is discharged from the bottom of the filter bag: the reverse spray type is to divide the filter bag into two parts, one is reverse spray, and the other is forward spray. In the process of injection, the filter bag after dust removal has no dust catching effect. Because the injection time is very short, and the filter bags are sprayed in rows for the first time to clean the dust, the dust catching work can be regarded as continuous, so the cavity structure can be used for off-line dust cleaning, and the on-line dust cleaning can be carried out regardless of the cavity. The pulse dust removal effect is strong and good, which can improve the filtration wind speed. Its intensity and frequency can be adjusted, and the dust removal effect is related to the structure of atmospheric venturi and whether the center line of jet and the center line of filter bag are the same element. When the filter bag is long, good dust removal effect can be obtained by using the same blowing equipment. Because of its strong dust removal effect, it is also useful for viscous filter materials. The use of felt filter media has also been widely used. From the microscopic point of view, felt filter material can be used for useful filtration, so its apparent filtration speed is higher than that of woven fabric, thus making the equipment miniaturized. Pulse spraying equipment needs compressed air as power, and the spraying effect is affected by the simple condensation of water vapor in compressed air in cold areas, so it is not suitable to be placed outdoors, and corresponding technical measures should be taken to prevent condensation or freezing.
5. Air ring back-blowing dust removal method This dust removal method is to set a hollow circular ring with a slit near the outer surface of the inner-filtering circular filter bag, which can move up and down and be connected with compressed air or a high-pressure fan pipeline, and the high-speed airflow sprayed from the inward slit nozzle on the circular ring removes the dust layer accumulated on the inner side of the filter bag. The working principle of gas ring reverse blowing is that several adjacent gas rings form a group, which are fixed on a structure and driven by a chain to move up and down along the guide rail. Its structure is complex and it is easy to damage the filter bag. Due to the use of pulse soot blowing and ash cleaning, it is rarely used except for special purposes.
6. Air box pulse ash cleaning method, also called forced pulse method, is characterized in that the filter bag is divided into several chambers, which are separated by partitions in the clean air box above the filter bag to form a sub-chamber, and there is no venturi tube at the upper end of the filter bag. Dust removal shall be carried out room by room in sequence. When the exhaust valve is closed, the pulse airflow is emitted from one side to the upper part of the sub-chamber, enters each filter bag through the sub-chamber, and removes dust through its impact and expansion.
7. The pulse back-blowing ash cleaning method is a kind of ash cleaning method which gives pulsation to the reverse airflow of the above ash cleaning method. It has a strong cleaning effect, but it must have a mechanical structure that can produce pulsation. Because of the strong dust removal effect, if some filter bags are used to remove dust step by step, there is no need for compartment structure.