Operation and maintenance of the hottest bag filte

2022-09-20
  • Detail

Operation and maintenance of bag filter

the operation of bag filter can be divided into trial operation and daily operation. First, during the test run, the single component of the system must be checked, and then the adaptive operation and partial performance test must be carried out. In daily operation, necessary inspections should still be carried out, especially the performance inspection of bag filter. Pay attention to the impact of the load change of the host equipment on the performance of the dust collector. After the machine starts, pay close attention to the working condition of the bag filter and make relevant records

first commissioning

during the commissioning of a new bag filter, special attention should be paid to the following points:

1, the rotation direction, speed, bearing vibration and temperature of the fan

2. Whether the treatment air volume and the pressure and temperature at each test point are consistent with the design

3. The installation of the filter bag, whether there is bag falling, opening loosening, wear and other conditions after use, can be judged by visual inspection of the emission of the chimney after putting into operation

4. Pay attention to whether there is condensation in the bag room and whether the ash discharge system is unblocked. Prevent blockage and corrosion, and serious ash deposition will affect the production of the host

5. The adjustment of ash cleaning cycle and time is an important factor affecting the dust collection performance and operation. If the dust removal time is too long, the attached dust layer will be removed, which will become the cause of filter bag leakage and damage. If the dust removal time is too short and the dust on the filter bag has not been removed, the filtration operation will be resumed, which will make the resistance recover quickly and gradually increase, and finally affect its use effect

the interval between two ash cleaning is called the ash cleaning cycle. Generally, it is hoped that the ash cleaning cycle will be as long as possible, so that the dust collector can operate under economic resistance conditions. Therefore, it is necessary to carefully study the dust properties and dust concentration, determine the ash removal cycle and time according to different ash removal methods, and adjust them in the test run to achieve better ash removal parameters

at the beginning of operation, there are often some unexpected situations, such as abnormal temperature, pressure, moisture, etc., which will cause damage to the new device

the sharp change of gas temperature will cause the deformation of fan shaft, resulting in an unbalanced state, and vibration will occur during operation. Once the operation stops, the temperature drops sharply, and then when it is restarted, vibration will occur again. It is best to choose different types of fans according to the gas temperature

the test run of the equipment directly affects whether it can be put into normal operation. If it is not handled properly, the bag filter is likely to lose its effectiveness soon. Therefore, the test run of the equipment must be careful and cautious

II. Daily operation

in the daily operation of bag filter, due to some changes in operating conditions or some failures, the normal operation and working performance of the equipment will be affected. Regular inspection and appropriate adjustment should be carried out in order to prolong the service life of the filter bag, reduce power consumption and recover useful materials. The problems that should be paid attention to are:

1. Operation record

each ventilation and dust removal system should be installed and equipped with necessary test instruments. It must be measured regularly in daily operation and accurately recorded. This can be judged according to the value and changes of the system's differential pressure, inlet and outlet gas temperature, main motor voltage, current, etc., and timely eliminate the fault to ensure its normal operation

the problems found through the record include: the working condition of the ash cleaning mechanism, the working condition of the filter bag (damage, bag pasting, blockage, etc.), and the change of the system air volume

2. Fluid resistance

u-type differential pressure gauge can be used to judge the operation condition: if the differential pressure increases, it means that the filter bag is blocked, there is water vapor condensation on the filter bag, the ash cleaning mechanism is invalid, too much ash is accumulated in the ash bucket, which leads to the blockage of the filter bag, and the number of leaders of gas flow testing machine manufacturers increases. The reduction of differential pressure, combined with the characteristics of synthetic leather, stainless steel, electrical engineering and other traditional industries, means that the filter bag is damaged or loosened, the inlet side pipe is blocked or the valve is closed. There is leakage between the box or each compartment, and the fan speed slows down

3. Safety

special attention should be paid to taking measures to prevent combustion, explosion and fire accidents. When dealing with combustion gases or high-temperature gases, incomplete combustion dust, sparks, combustion and explosive gases often enter the system. Some dust has the nature of spontaneous combustion or electrification. At the same time, most filter materials are easy to burn, friction and accumulate static electricity. Under such operating conditions, there is the danger of combustion and explosion accidents, The consequences of such accidents are often very serious. Fire prevention and explosion-proof measures should be well considered, such as:

⑴ a combustion chamber or spark catcher should be set in front of the dust collector, so as to completely burn the incompletely burned dust and gas or capture the spark

⑵ take measures to prevent the accumulation of static electricity. Each part is grounded with conductive materials, or conductive fibers are added during the manufacture of filter materials

⑶ prevent the accumulation or accumulation of dust to avoid spontaneous combustion and explosion of dust

⑷ before entering the bag room or pipeline for inspection or maintenance, be sure to ventilate to prevent CO poisoning

4. Precautions for stopping operation

before the bag filter stops running, in addition to thoroughly cleaning the ash, the following problems should also be paid attention to:

⑴ wet gas condensation often occurs in the bag room, which is caused by the cooling of wet gas, especially the gas produced by combustion. Therefore, before the system is cooled, Discharge the wet gas and completely replace it with dry air, that is, after the process equipment stops running, the exhaust fan of the bag filter should run for a period of time before it stops running

⑵ during long-term shutdown, pay full attention to the cleaning and rust prevention of the fan to prevent dust and rain from entering the bearing (pay attention to the moisture-proof of the motor). Before stopping the operation, remove the accumulated ash in the ash hopper. The ash cleaning mechanism and driving part shall be fully oiled

⑶ during the shutdown of the bag filter, regular short-term operation (idling) is the best maintenance method to ensure the normal operation of the dust removal system

5 maintenance

5.1 always check the action of control valve, pulse valve and timer

the failure of the rubber diaphragm of the pulse valve is a common fault, which directly affects the ash removal effect. The equipment is of external filtering type, and the bag is equipped with a skeleton. Check whether the parts that fix the filter bag are loose and whether the tension of the filter bag is appropriate. Whether the support frame is smooth to prevent abrasion of the filter bag. Compressed air is used for ash removal. Therefore, it is required to remove oil mist and water droplets, and the oil-water separator must be cleaned frequently to prevent movement mechanism failure and filter bag blockage

5.2 prevention of condensation

during use, it is necessary to prevent the gas from cooling below the dew point in the bag room, especially when using the bag filter under negative pressure. Because air often leaks into its shell, so that the temperature of the gas in the bag chamber is lower than the dew point, the filter bag will be damped, so that the dust is not loose, but sticky attached to the filter bag, blocking the fabric eyelets, resulting in ash removal failure, making the pressure drop of the dust collector too large to continue to operate, and some paste bags cannot be removed

to prevent condensation, the temperature of the gas in the dust collector and its system must be kept 25 ~ 35 ℃ higher than its dew point (such as the dew point temperature of the kiln mill integrated machine is 58 ℃, and the operating temperature should be above 90 ℃), so as to ensure the good use effect of the filter bag., The measures are as follows:

⑴ add raw material stacking sheds. In cement production, the moisture content of various raw materials, fuels and mixtures varies. If they are placed in a fixed shed to prevent rain, the moisture content of materials can be greatly reduced, which is an effective measure to reduce the moisture content of materials. This situation is common in cement plants in southern China, but some material sheds are too small, while others are not. Therefore, it is difficult to use bag filters

⑵ reduce air leakage. For the air leakage of the gap of the dust collector body, the air leakage of the bag type dust collector body should be controlled below 3.5%. The air leakage of process equipment in the dust collector system, such as the air leakage of the closed ash discharge valve at the discharge port of the ball mill, the air leakage of the closed ash discharge valve under the dust collector, and the pipe flange connection, are often ignored by the maintenance and management personnel. Therefore, unnecessary air leakage is increased and the operating conditions of the bag type dust collector are deteriorated

⑶ the dusty gas shall be evenly distributed in the dust collector to prevent the occurrence of eddy current at the corners, which will reduce the amount of gas passing here and form local low temperature, resulting in condensation

⑷ do a good job in heat preservation and rain prevention of dust collectors, pipelines and other relevant places. Practice has proved that good insulation measures can make the temperature difference between the inlet and outlet of the bag filter very small, which is an effective measure to prevent condensation

(5) take appropriate heating measures. If the far-infrared electric heater and electric heater are set in the dust collector, or the radiator is added in the bag room, the flue gas temperature of the host can be appropriately increased

⑥ strengthen the temperature monitoring of the dust collector and dust removal system, so as to master the service conditions of the bag type dust collector and prevent condensation

5.3 prevention of combustion and explosion

the waste gas discharged from the rotary kiln tail of the cement plant and the waste gas discharged from the preparation of coal mill will produce combustion and explosion accidents under the conditions of its content, dust concentration and certain temperature, which will not only burn the dust removal equipment, but also affect the normal operation of the production host machine. Therefore, necessary preventive measures must be taken, Mainly:

⑴ it is necessary to prevent the accumulation of combustible substances and combustible gases (CO, etc.) in the pipe and bag chamber of the bag filter in a warm atmosphere, and pay special attention to coal dust

⑵ strengthen the control of the inlet temperature of the bag filter

⑶ explosion proof valve is installed on the bag filter to ensure safe use

5.4 prevent the reduction of dust removal efficiency

⑴ block the air leakage, especially the air leakage at the ash outlet of the dust collector. Because there are a large number of dust falling slowly in the dust hopper of the dust collector, the shaft split control multifunctional experimental machine is a kind of dust with domestic new technology material detection equipment, and the countercurrent upward leakage air flow causes the falling dust to fly again and circulate for many times. Therefore, the air leakage at the ash outlet can make the dust concentration in the dust collector double that of the air inlet, which worsens the working conditions of the bag type dust collector, It affects the dust removal efficiency of the bag filter

⑵ prevent short circuit of air flow inside the dust collector. Because the dust concentration of the dust source gas is high (such as 20g/m3), even if only 1% of the short circuit escapes, it will exceed the emission standard. Dusty gas escapes directly from some cracks without passing through the filter bag, which is not allowed to happen. Therefore, attention should be paid to design, installation and maintenance

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