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Analysis and treatment of common failure causes of bag dust collectors

2019-05-08 16:05:40

Since 2017, the environmental protection policy has become more and more strict, and many policies have been introduced to control dust pollution. The efficient and stable operation of the dust removal equipment is very important. Once there is a problem with the equipment, it will directly affect the dust removal efficiency. This article describes the 11 types of faults commonly found in bag filters and their treatment methods.

 

01 filter bag blocked

 

Cause Analysis:

 


(1) The air leakage or low temperature of the flue gas causes condensation and water leakage in the pipeline, and the wet bag causes dust to adhere.

 

(2) The filtration speed is too large, the dust is too fine or too thick, the dust is sticky, and the filter bag is poorly cleaned.

 

(3) The blowing cleaning time and cycle are too short.

 

(4) The blowing pressure is too small and the blowing is weak.

 

Approach:

 

(1) The dust collector is insulated or heated, protected from rain and air leakage.

 

(2) Before the pre-collection dust is blown, reduce the filtration speed and control the cooling water spray amount.

 

(3) Observe the pressure difference and adjust the injection time and period.

 

(4) Adjust the injection pressure.

 

02 filter bag burned


Cause Analysis:

 

(1) Discharge the filter bag into small holes or branches and piles to cause dust leakage with the high-temperature particulate matter or the charged dust discharge sparks.

 

(2) The dust in the dead angle of the dust collector or the dust in the ash bucket will cause the local or whole box filter bag to burn.

 

Approach:

 

(1) Set the flame-reduction device to prevent the open flame from entering the dust collector.

 

(2) Reduce the dead angle inside the dust collector and timely discharge the ash, regularly remove the dead corner ash in the dust collector, and leave a part of the ash seal to prevent air leakage.

 

 

03 filter bag corrosion


Cause Analysis:

 

Corrosive damage caused by other chemicals such as acid or alkali, showing local or overall embrittlement, reduced strength or ulceration.

 

Approach:

 

Detection controls changes in smoke composition.

 

04 filter bag mechanical damage


Cause Analysis:

 

(1) The surface of the frame is rough and the friction and stab wound of the sharp weld.

 

(2) Improper storage, transportation and installation.

 

(3) The blowing pressure is too large and the bag is worn.

 

Approach:

 

(1) Pay attention to the maintenance of the frame and keep its surface smooth.

 

(2) Properly packaged, avoid pressure and flexion during storage and transportation, be waterproof and anti-exposure, gently handle when installing, prevent bumps, and do not pull on the ground.

 

(3) Adjust the injection pressure.

 

 

05 pulse valve blowing powerless


Cause Analysis:

 

(1) The large diaphragm orifice is too large or there is trachoma on the diaphragm, and the vent hole is partially blocked.

 

(2) The pressure of the compressed air source is too low.

 

(3) The cleaning nozzle is not centered or blocked.

 

Approach:

 

(1) Replace the diaphragm and clear the vent hole.

 

(2) Increase the pressure of the air source.

 

(3) Check if the cleaning nozzle tube is blocked and the position is centered.

 

06 solenoid valve does not move or leak


Cause Analysis:

 

The coil is damaged, open circuit, poor contact, and the controller has no signal.

 

The diaphragm is damaged and deformed, and impurities are stuck on the diaphragm. The diaphragm cannot be normally reset, the spring is broken or the vent hole is blocked.

 

How much damage is caused by the pressure of the injection.

 

Approach:

 

Repair coils and wiring.

 

Replace the diaphragm spring or rubber to clear the vent.

 

Adjust the injection pressure.

 

07 resistance increases beyond the normal value, and the resistance cannot be reduced after the cleaning operation


Cause Analysis:

 

(1) Producing a paste bag phenomenon.

 

(2) The cleaning device is faulty and has no cleaning effect.

 

(3) The cleaning effect is not good.

 

(4) The filtering speed is too large.

 

Approach:

 

(1) Dispose of the paste bag filter bag, or spray or cover an ultra-thin PTFE microporous film on the contact surface of the filter bag and the dust, or spray the surface of the filter bag with a special treatment powder to form a very thin filter cake on the surface. The porosity is relatively uniform and small; the special purpose of calendering or sintering on the surface of the filter cloth can also achieve the same purpose. Oil-proof, anti-static, waterproof filter cloth can also be used, and heat preservation measures can be used to prevent condensation. bag.

 

(2) Overhaul the cleaning device to handle the failure.

 

(3) Reduce the cleaning cycle, increase the blowing time; increase the blowing pressure.

 

(4) Find the cause, carry out the treatment, check the air leakage, and stop the leak.

 

08 Others are normal, but the emission concentration exceeds the standard.


Cause Analysis:

 

(1) The filter bag of the dust collector is damaged.

 

(2) The filtering speed is too large, causing dust leakage.

 

(3) The blowing time is too long or the cleaning is frequent, causing damage to the initial dust layer.

 

(4) The strength of cleaning is too large, resulting in secondary dust.

 

(5) The structural design of some airbags is unreasonable, and a gas leakage scene occurs in the installation of the pulse valve.

 

Approach:

 

(1) Repair and replace the filter bag. The outer diameter of the bag cage should be kept at a certain distance from the inner diameter of the filter bag. If the spacing is too large, the wear of the filter bag should be increased, so the spacing should be reduced.

 

(2) Find the cause, process it, and reduce the filtering wind speed.

 

(3) Reduce the injection time and increase the cleaning cycle.

 

(4) Reduce the intensity of cleaning.

 

(5) Make reasonable modifications to prevent air leakage.

 

(6) Appropriately increase the box body and raise the ash hopper to ensure that the slanting angle of the ash hopper is not less than 60 degrees. For places with high smoke humidity and sticky dust, install a vibrator at the ash hopper of the dust collector. The ash-proof ash is especially suitable for wet weather in the south.

 

09 flue gas temperature is too high, too low or filter bag burning


Cause Analysis:

 

(1) The high temperature of the flue gas is because the actual evaporation of the boiler exceeds the rated evaporation or the combustion adjustment is abnormal or the heated area is ashed.

 

(2) The low temperature of the flue gas may be due to various reasons such as air leakage at the tail of the boiler, combustion adjustment, and heating surface modification, resulting in low exhaust gas temperature of the furnace.

 

(3) There may be combustible particles.

 

Approach:

 

(1) The offline protection system is adopted. When the temperature of the flue gas is too high or the tail of the boiler is re-ignited, the spray cooling system is started, and the emergency water spray is cooled to avoid burning the filter bag and contacting the boiler for combustion adjustment.

 

(2) Put the air preheater bypass flue; reduce the amount of tail soot blowing to use the upper row of milling system, open the fan hot air recirculation door under low load condition, increase the cold air inlet temperature, and open low during normal operation. The hot air recirculation of the blower on the flue side of the flue gas, as far as possible to increase the trough load, etc., if it is still low, further improvements are needed in the boiler.

 

10 flower board ash


Cause Analysis:

 

Damage to the filter bag, poor sealing between the filter bag connecting the short tube and the flower plate, etc., will cause the flower board to accumulate to varying degrees.

 

Approach:

 

Check the filter bag to strengthen the seal between the filter bag connecting tube and the flower plate.

 

 

11 often breaks the bag


Cause Analysis:

 

(1) The distance between the filter bags is too close, not only the collision between the bag, the bag and the wall, but also the speed of the airflow of the box, which results in the local filter load of the filter bag is too high and the cleaning power is insufficient, and the cleaning is frequent.

 

(2) It is very sensitive to temperature, the temperature of the flue gas exceeds the allowable limit, and the filter material will be damaged in a short time. The strength of the filter material is invalid. The filter material is sensitive to oxygen at high temperature. When the oxygen content of the flue gas exceeds the critical value, The filter material is thermally oxidized and decomposed and damaged in a certain period of time.

 

(3) High injection air pressure will cause serious damage to the filter material and greatly shorten the service life of the filter material.

 

(4) The airflow is unevenly distributed.

 

Approach:

 

(1) Adjust the filter bag spacing. According to experience, the filter bag edge spacing is at least the radius of the filter bag itself.

 

(2) Adopt high temperature resistant and high strength filter media. When the boiler is in normal operation, the oxygen content of the flue gas is generally lower than the critical value of the filter material. Therefore, at the time of design, the flue gas after the bag filter is used as a gas source to avoid inhaling a large amount of fresh air.

 

(3) The blowing air pressure should be no more than 0.20 MPa and should be low at the premise of ensuring the cleaning effect.

 

(4) Find the cause and carry out the transformation.

 

In the actual operation process, standard, detailed cleaning and daily maintenance, as well as timely detection according to experience, can avoid small problems and cause major failures, which can affect the production, and save maintenance costs. Continuously improve operational skills, observe more, analyze diligently, eliminate hidden dangers, and ensure normal and continuous operation of bag filter to effectively control dust pollution, meet production needs, improve production efficiency, and reduce production costs.

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