The use and maintenance of the bag filter General problems and precautions can be divided into excessive dust emissions, dust pressure higher than normal, and the filter bag is too short, and other three aspects, there is a clear correlation between the three as follows:
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First, excessive dust emissions
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Caused by excessive emissions of dust the basic reasons
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1 initial surface of filter bag is not enough;
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2 bag is damaged
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3 poor filter bag assembly;
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Described as follows:
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1, the initial surface of the bag is not enough
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In the operation of the precipitator, if the discharge is excessive and the operating pressure of the precipitator is lower than the design, it is most likely that the initial powder layer on the surface of the filter bag is insufficient. The reason may be that the filtration speed of the filter bag is too high, Cleaning cycle is too short, blowing compressed air pressure is too high, reduce the dust load and so on.
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Studies have shown that: high filtration rate, dust discharge rate will increase, too high filtration rate, the initial layer of dust will be broken, and the dust caused by excessive impact on the filter bag, if the number of times to clean the filter bag is too high Can easily lead to loose fabric filter bag, which will make excessive discharge of precipitators.
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In setting the pulse cleaning cycle, in order to ensure that the dust collector work under stable pressure, set the longest pulse cleaning cycle time is good, pulse cleaning time to ensure that the initial dust does not fall off, the set time The shortest cleaning is good, if the initial dust layer is not enough, you can extend the cleaning cycle compensation, if you use the pressure control, you can increase the import and export of dust pressure setting stability.
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If the discharge of the filter is only after the filter bag has been cleaned, just check if the pressure of the pulse-purged compressed air is excessive.
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Dust load reduction may come from the reduction of productivity, or dust collector control system maintenance, adjustment caused by the solution: you can use light load slowly start the lifting or pre-coated dust method to solve.
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2, the bag is damaged (worn, burned, corroded)
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The use of filter bags accounted for the largest maintenance costs of dust collector, up to 70% of maintenance costs above. The basic situation is wear and tear, burning, corrosion, etc., to solve the method can be used in the following ways:
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(1) wear and tear
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Too high filtration speed, resulting in dust impact, wear and tear filter bag, but also to filter bag fabric fiber tension damage, the solution: adjust the exhaust flow of the dust collector, when the expected changes in the flow rate can increase the flow of automatic control System to ensure that dust collector work in a stable amount of gas.
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Uneven dust distribution of the intake, easy to make high levels of dust emissions directly impact the local filter bag, easy to make the exhaust gas inlet part of the filter bag perforation, the use of the cycle is too short, the solution: Install the catheter in the dust collector inlet Air distribution guide plate, or for the regular wear parts of the filter bag replaced with wear-resistant filter bag.
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The distance between the filter bags is too small, keel bending and other easily lead to wear between the filter bag, for example, wear and tear of glass fibers are sensitive to each other should be adjusted, install a solid filter bag and replace the curved keel.
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The difference between the diameter of the filter bag and the keel, too little cleaning effect is poor, should increase the cleaning cycle and improve the pressure of blowing air, too much when the filter bag and keel friction, will accelerate wear and tear, the better with the filter bag ratio The keel has a circumference of 10-20mm and its length should be the same. For certain filter cloths, the change of temperature of the filter cloths should be large, and the elongation characteristics of the filter cloths require special attention.
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Keel welding holes or burrs, or due to corrosion of the rough surface, will also accelerate the wear and tear of the filter bag.
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Strict sealing of the filter bag and perforated plate, will cause the top of the filter bag anti-fold wear, the use of elastic ring is better on behalf of.
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Venturi or pulse tube relative to the filter bag is not aligned, it is easy to make the upper filter bag mechanical friction, should be adjusted.
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Filter bag cleaning is too frequent, will accelerate the wear of the filter bag, should be adjusted.
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Dust in the exhaust gas exceeds the design standards, will also make the filter bag accelerated wear and tear.
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Dust collector ash hopper stored too much dust, will accelerate the wear of the filter bag.
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The above reasons will make the excessive discharge of precipitators, but also reduce the life of components, should pay attention.
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(2) burned
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The cause of the filter bag burned, mainly due to the high temperature of the exhaust gas
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If the long-term treatment of the dust collector exhaust gas temperature exceeds the working conditions of the filter bag, it is easy to make the filter bag shrinkage hardening, or melting hole, and the influx of Mars into the air, or dust fever, may also make the filter bag hole, Filter bag is particularly important.
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If you need to cool the exhaust gas, cooling method should pay attention to the humidity of cold air, whether it contains acid-base components, while trying to ensure that the exhaust gas treated by the dust collector temperature above the dew point and to prevent water droplets directly into the filter bag.
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In order to prevent Mars from entering the precipitator, so that the filter bag is burned, pretreatment methods can be adopted, for example, precoating a protective layer on the surface of the filter bag, and kaolin, limestone powder and the like can be used. At the same time to prevent unburned carbon material in the dust collector secondary combustion.
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(3) Corrosion
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The main reason for corrosion is that the exhaust gas contains acid and alkaline components, and the dew point changes with the concentration of these chemical gases. If SO2 in the exhaust gas is turned on when H2SO2 is turned on or shut down, the filter bag fiber Deformation to lose strength, to prevent the method is to use acid, alkali filter bag, the dust collector inlet pipe, the shell insulation, under conditions can be heated to the precipitator.
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Condensed water in the exhaust gas will also cause the filter bag to be clogged. When the initial dust layer on the surface of the filter bag is dried due to the moisture, the dust will condense and solidify. As a result, the filter bag will go to elasticity. Under this condition Pulse cleaning bag will speed up the bag damage.
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After the use of dust collector and then pulse back to clean the filter bag several times, to protect the filter bag useful.
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Second, the resistance is too high
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The resistance of the precipitator has been decided in the design of the precipitator. However, if the resistance of the precipitator is found to increase sharply in a short period of time during the operation of the precipitator, it indicates that there is a problem with the precipitator and the repair and adjustment should be carried out.
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The original resistance should be divided into two types:
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1, dust collector in the system immediately after the operation;
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2, dust collector in the work after a period of time occurred;
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If it is improper design of newly installed dust collector, easily lead to the first phenomenon;
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The second reason is caused by the operation problems and maintenance: The main reason is the poor cleaning of the filter bag, the filter bag is blocked, and the air intake is unevenly distributed. Briefly as follows:
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(1) poor cleaning device adjustment
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Check the quality of compressed air, whether it contains oil, water;
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Check the gas pipeline is smooth;
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Check the pulse solenoid valve is working properly, the fastening bolts are loose, the diaphragm is damaged, the solenoid coil is loose; spool is stuck;
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Whether the sequence controller settings meet the requirements, whether any change;
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Jet manifold, venturi is installed correctly;
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(2) filter bag is blocked
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The main reason is the filter bag filter is too large, too small dust, dust has a sticky, bad filter bag, filter bag damp.
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If the dust filter operating speed exceeds the filter bag design standards, it can easily lead to the fine dust in the exhaust gas inside the filter bag stuck. As a result, the filter bag becomes clogged.
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It is a good idea to use a coated filter or to pre-cover the protective powder layer on the surface of the filter bag.
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For sticky dust, you need to reduce the filtration rate, or increase the pressure pulse injection, or the use of off-line pulse cleaning bag, but the better approach is to increase the filtration area, in order to reduce the filtration rate, to extend The service life of the filter bag.
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Poor cleaning bags, including dust cleaning frequently, cleaning time is too long. Cleaning frequency too easy to make the filter bag loose loose tissue so as to increase the fine dust in the exhaust gas clogging the filter bag, cleaning time is too long will be the initial surface of the filter bag washed together.
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If the cleaning time is too short, the filter bag surface dust has not been completely cleaned, then began to filter, the dust gradually accumulated in the surface of the bag, resulting in filter bag clogging, in solving this problem, several times Trial run to adjust.
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The reason for dampness of the filter bag: The seal of the precipitator shell is not leaky and leaks into the wet air. The compressed air used to blow back the dust is not clean (oil, water), and the compressed air used for cleaning is too cold.
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In order to prevent dampness of the filter bag, in the cold area, the compressed air used for cleaning can be added to increase the temperature, degrease and remove the water, and the cleaning can be continued for 10 to 20 minutes after the dust collector stops.
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Water is the biggest cause of the filter bag clogging, resulting in the moisture content is usually caused by condensation at low temperatures, especially in the treatment of combustion or high temperature flue gas, the following methods can be used to prevent this:
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① avoid improper boot
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② avoid dust in the resistance when the boot;
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Boot at below dew point;
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When the filter bag is shut down, the condenser bag will be restarted when there is condensate on the surface of the filter bag. In this case, a large amount of dusty air will enter and a high humidity will cause the bag surface to be muddy.
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In order to prevent this situation, the dust collector should be preheated imported dust, or pre-coated dust layer.
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③ boot below below dew point
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Precipitator below the dew point of operation, prone to problems, if the uneven distribution of intake air, easy to cause partial corrosion of the precipitator shell, therefore, should avoid dust collector work below the condensation point, the insulation device should be used.
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④ air infiltration
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Air infiltration often occurs in the dust of the flange, access door or dust collector activities, if the seal is not strict, outside air into the dust collector,
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When dealing with high temperature exhaust gas, it will produce low temperature inside the precipitator, resulting in low temperature dew, corrosion precipitator, resulting in wet bag.
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(3) Improper gas distribution
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If the dust of the imported gas is unevenly distributed, there will be great resistance when the dust collector is turned on. Therefore, it is necessary to ensure the uniform distribution of the gas in the dust collector.
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Third, the life of the filter bag is too short
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The factors that affect the service life of the filter bag are as follows:
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Improper use of filter bag types; Quality of filter bags; Filtration gas velocity; Dust load; Dust composition; Dust characteristics; Cleaning method; Cleaning frequency; System startup, downtime; and related maintenance work.
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In assessing the service life of the filter bag, should consider whether to use properly, carefully check and record the work of the precipitator, the precipitator is often below the dew point boot, shutdown, and pulse cleaning cycle, cleaning time is reasonable,
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Installation of differential pressure gauge, thermometer is a prerequisite for record keeping. Is also to ensure the normal operation of the dust collector measures.
