Filter bag pressure is too high
The high differential pressure of the filter bag means that the pressure difference between the inside and outside of the filter bag exceeds the measurement range of the online monitoring pressure gauge. The increase in the pressure difference of the filter bag can easily cause the following problems:
1 The ability of the system to process dust is significantly reduced;
2 It is easy to cause clogging of ash pipelines;
3 Caused the fan to work at high frequency for a long time, increasing the power consumption of the system.
The main reasons for the increase in the pressure difference of the filter bag of the precipitator are:
1 The dust gas temperature is too high, and the system does not use any heat insulation measures, making the dust in the pipeline, dust collector and the external environment there is a larger temperature difference, the occurrence of heat exchange and cooling and precipitation of water vapor, condensation, increased dust Humidity and viscosity should be taken thermal insulation measures.
2 Improper setting of relevant parameters of the pulse jet system, dust removal effect of the dust collector is poor. For example, the time interval between pulse jets of the filter bag is too long, the width of the pulse jet is too short, and the pressure of the compressed air is too low. As a result, the filter bag becomes less open and the dust on the filter bag also accumulates too thick. The pulse injection system related parameters should be reset.
3 Filter bag material does not match with dust characteristics, causing some air holes to be blocked. For the dust with high concentration, small particle size, high humidity, and high viscosity, the membrane filter cloth should be used. The film-covered filter cloth is made by covering the surface of a needle-punched filter cloth with a PTFE microporous film. The surface of the filter cloth is thin, smooth, microporous, small in pore size, high in porosity, and has a very low coefficient of friction. Stickiness.
4 The dust removal load of the dust collector and the filtering air velocity of the filter material are too high.
If the concentration of dust handled by the system is too high, the value of the filtration velocity of the filter material is too high, which will lead to an increase in the pressure difference of the filter bag. The dust removal load of the bag filter and the filtering air velocity of the filter should be appropriately reduced, that is, the filtration area should be increased, so that the filtration speed of the filter material can be reduced.
Damaged filter bag
Pulse bag filter is the use of dust bag filter to purify the dust flow, so the bag’s integrity is directly related to the purification efficiency. In the production, due to the wear of the dust on the surface of the bag, the bag will appear “acupuncture” holes over time. Sometimes in the cleaning process, due to the strong air flow under high pressure, the dust bag will also be damaged. Damage to the filter bag causes increased dust concentration in the discharged gas, and the airflow containing more dust passes through the fan at high speed, causing severe wear of the fan housing and the impeller. The selection of wear-resistant and corrosion-resistant filter bag materials and the improvement of the service life of the filter bags are effective methods to solve the problems. In addition, we must regularly check the dust bag wear, found that the phenomenon of broken bags should be dealt with in a timely manner, small holes can be glued and sewing, large size will be replaced.
The airtightness of dust collector main equipment and pipe network is a factor that can not be ignored influencing the effect of pulse bag dust removal.
The bag filter is operated with negative pressure. If the joint between the main equipment and the housing and the pipe is not tightly sealed, one of them will leak dust and dust, which will reduce the actual air volume and affect the improvement of the dust removal effect. Second, it will leak into the cold air. The increase in the dust-containing gas treatment capacity and the decrease in the temperature of the dust-laden gas and the appearance of condensed water will both cause the dew point of the dust-containing gas to change and cause dew condensation to occur. Check the air leakage of the dust collector, you can open an inspection hole in the box near the outlet, but it is difficult to find the air leakage point by visual inspection. At this time you can open the exhaust fan, and you should turn off the small door to enter the inspection. If you can hear the sound of the “windfall”, you can identify the problem here, and then deal with the leak. In addition, the control of air hoses, reversing valves, and poppet hoses between the aging of the flexible hose and broken air leakage can not be ignored. The air leakage will cause the poppet valve to not obtain the required compressed air and cannot be lifted or closed in time. The whole system is not smooth, and there is a large fluctuation in the negative pressure difference between the inlet and outlet of the dust collector, which makes the dust collector work abnormally. If such problems are found, the leather tube should be replaced promptly。
Poor gas source
The quality of compressed air is the key to the stable operation of the pulse bag filter. The quality of the high pressure air affects the dust removal performance in three aspects:
One is high-pressure air supply.
Under normal circumstances, if the amount of high-pressure air required for each pulse valve operation does not meet the requirements, normal dust removal will not occur, resulting in a dust bag “patch bag”.
The second is high pressure wind pressure.
At the instant of removing dust from the dust bag, only the pressure in the bag is 3 to 5 times higher than the pressure outside the bag (negative pressure in the dust collector), so that the bag can be cleaned normally.
The third is to ensure that the high pressure air is clean and dry.
The high-pressure air directly supplied by a common air compressor contains certain water and oil stains. If the water is not discharged in time, the moisture content will be blown into the dust bag with high-pressure air, which will inevitably cause a thick “porridge”-like dust layer on the surface of the cloth bag. , Which led to dust bag scrapped. In addition, if compressed air contains a lot of oil and water, it can easily cause phenomena such as the accumulation of water in the cylinder, the leakage of the pulse valve, the reduction of the air pressure in the pneumatic triad, and the inability of the cylinder solenoid valve. A refrigerated gas dryer can be installed at the outlet of the air compressor, or a gas filter with a replaceable filter cartridge can be installed at the inlet of the air receiver of the dust collector to periodically discharge water and check the pressure difference of the gas filter when the pressure loss reaches Change the filter element from 0.1 to 0.15.
Pulse valve does not work properly
Pulse valve and controller are essential auxiliary equipment for pulse bag filter, mainly responsible for dust removal of dust bag to maintain long-term and stable operation of dust collector.
If the pulse valve and control device work abnormally, it will directly appear as a “paste bag”, which will increase the resistance of the dust removal system and significantly reduce the dust removal effect.
Electromagnetic pulse valve leakage is the most common failure, the main reasons are:
1 The air pressure balance hole of the electromagnetic pulse valve is blocked.
The installation of compressed air pipelines did not clean up foreign matter such as rust and welding slag inside the pipeline, or compressed air contained a lot of oil and water.
2 The electromagnetic pulse valve diaphragm is damaged.
All the pulse valves of the dust ejector do not work, the pressure of the air bag rapidly decreases to zero, the cylinder is closed, the pressure difference of the dust collector continues to increase, and the ventilation volume rapidly decreases.
When an electromagnetic pulse valve leaks, find the cause and take measures from the following aspects.
1 Open the drain valve on the air tank and blow it to remove foreign matter such as rust and welding slag inside the pipe.
2 Replace the double diaphragm of the electromagnetic pulse valve. The diaphragm seals the compressed air of the pulse valve. If it is used for a long time, it will prone to aging and will not achieve sealing. When replacing, it is necessary to pay attention to whether the small holes on the grinding plate are breathable, and it is necessary to ensure the ventilation after installation.
3 Replace the spring used to compress the diaphragm. Due to prolonged use of high frequency, the elastic force of the spring will be weakened, making it difficult to compress the diaphragm and cause air leakage.
4 Replace the connecting spring of the electromagnetic pulse valve magnet.
The spring is apt to rust, and after rusting, the elastic force is insufficient, so that the electromagnet cannot bounce after the electromagnetic pulse valve is de-energized, resulting in continuous air leakage of the electromagnetic pulse valve.
Lift valve work abnormal
The abnormal work of the poppet valve is mainly manifested in:
1 valve plate off;
2 cylinder does not move or action is not in place.
The drop of the valve plate is mainly due to the fact that the position adjustment of the valve plate on the cylinder screw is somewhat deviated. When the cylinder runs to the bottom dead center, the valve plate is seriously deformed. Cracks occur around the center hole of the valve plate for a long time, causing the valve plate to come off. The treatment method is to increase the position of the valve plate upwards so that the valve plate will be slightly deformed (3 to 5 mm) when the cylinder is operated to bottom dead center.
Cylinder does not work may be the two-position five-way valve exhaust hole blocked or the two-position five-way valve into the dust or foreign matter, resulting in the spool can not move. Kerosene can be used to clean and grease lubrication method to eliminate, in the cleaning must pay attention to the loss of internal gadgets, according to the method of demolition reversed. The failure of cylinder operation is mostly caused by internal cylinder failures, mainly due to the accumulation of water in the cylinder and the leakage of the cylinder piston. The water in the cylinder can be opened by sequentially opening the exhaust valve on the upper and lower top cover of the cylinder and cooperating with the manual valve of the two-position and five-way valve to move the piston up and down several times to drain the water. When the piston leaks, open the cylinder. Replace the seal on the piston.