Introduction of cloth bag dust collector
Bag type dust collector is a dry dust filter device. Filter material after a period of time, due to screening, collision, retention, diffusion, static electricity and other effects, the surface of the filter bag accumulated a layer of dust, this layer of dust is called the first layer, in the process of movement after this, the first layer became the main filter layer of the filter material, relying on the role of the first layer, the filter material with larger mesh can also obtain higher filtration efficiency. With the accumulation of dust on the surface of the filter material, the efficiency and resistance of the dust collector are correspondingly increased, when the pressure difference on both sides of the filter material is very large, some of the fine dust particles that have been attached to the filter material will be squeezed in the past, so that the efficiency of the dust collector will be reduced. In addition, the high resistance of the dust collector will significantly reduce the air volume of the dust removal system. Therefore, after the resistance of the dust collector reaches a certain value, the dust should be cleaned in time. The primary layer should not be destroyed when cleaning, so as not to reduce the efficiency.
Working principle of cloth bag dust collector
The high dust removal efficiency of bag dust collector is inseparable from its dust removal mechanism. When the dust-containing gas enters the ash hopper through the inlet pipe at the lower part of the dust collector, the coarse dust will fall into the ash hopper due to the collision of the baffle and the reduction of the gas speed, and the rest of the fine dust particles enter the filter bag room with the gas. Due to the inertia, diffusion, barrier, hook hook, static electricity and other effects of the filter material fiber and fabric, the dust is blocked in the filter bag, and the purified gas escapes from the bag Outside, exhaust through the exhaust pipe. The ash accumulation on the filter bag is removed by gas backwashing method, and the dust removed is discharged to the ash hopper through the double-layer ash discharge valve to the ash delivery device. The ash accumulation on the filter bag can also be removed by the method of spraying pulsed air flow, so as to achieve the purpose of ash removal, and the dust removed by the ash removal device. The high dust removal efficiency of the bag dust collector is also inseparable from the filter material, and the performance and quality of the filter material are directly related to the performance and service life of the bag dust collector. The filter material is the main material for the production of filter bags, and its performance and quality are to promote the progress of bag dust removal technology, affecting its application range and service life.
The filter type dust removal device includes bag type dust collector and particle layer dust collector, the former usually uses the filter bag made of organic fiber or inorganic fiber fabric as the filter layer, and the filter layer of the latter is mostly composed of particles of different sizes, such as quartz sand, river sand, ceramic particles, slag and so on. With the powder repeatedly attached to the outer surface of the filter bag, the powder layer continues to thicken, and the resistance value of the bag dust collector also increases. The pulse valve diaphragm gives instructions, the pulse valve is opened when the left and right flood, the compressed air in the high pressure air bag is passed, if there is no dust or small to a certain degree, the mechanical cleaning work will stop working.
The gas purification method of low-pressure pulse bag dust collector is external filter type, and the dust-containing gas enters the filter chamber of each unit through the diversion pipe. Due to the vertical distance between the bottom of the filter bag and the upper entrance of the intake outlet in the design, sufficient and reasonable air flow is distributed through proper diversion and natural flow direction to achieve uniform air distribution in the entire filter chamber, and the particles and dust in the dust-containing gas fall directly into the ash hopper after natural settlement and separation. Under the guidance of the diversion system, the remaining dust enters the filter area of the middle box with the air flow and is adsorbed on the outer surface of the filter bag. The filtered clean gas is discharged through the filter bag through the upper box and exhaust duct.
The filter bag is sprayed with compressed air to clean ash, and the cleaning mechanism is composed of air bag, blowpipe and electromagnetic pulse control valve. The filter room is equipped with a spray pipe at the top of each row of filter bag outlet, and the lower side of the spray pipe is provided with a spray nozzle facing the center of the filter bag. Each spray pipe is provided with a pulse valve and communicated with the compressed air bag. When cleaning, the electromagnetic valve opens the pulse valve, the compressed air is sprayed by the cleaning control device (differential pressure or timing, manual control) according to the set program to open the electromagnetic pulse injection, compressed gas in a very short time through each pulse valve through the nozzle on the spray pipe to induce several times of the injection volume of air into the filter bag, forming air waves. The filter bag from the mouth of the bag to the bottom of the rapid expansion and shock vibration, resulting in a strong cleaning effect, shake off the dust on the filter bag.
Advantages of cloth bag filter
(1) The dust removal efficiency is high, generally more than 99%, the dust concentration of the dust collector outlet gas is within tens of mg/m3, and the fine dust with sub-micron particle size has a higher classification efficiency.
(2) A wide range of air volume treatment, small only 1min m3, large up to 1min tens of thousands of m3, can be used for industrial furnace flue gas dust removal, reduce the emission of air pollutants.
(3) Simple structure, easy maintenance and operation.
(4) Under the premise of ensuring the same high dust removal efficiency, the cost is lower than the electric dust collector.
(5) When glass fiber, polytetrafluoroethylene, P84 and other high temperature filter material is used, it can be operated under high temperature conditions above 200℃.
It is not sensitive to the characteristics of dust and is not affected by dust and resistance.
Bag dust collector basic knowledge
Basic calculation formula: A = L/V
A: filtration area m² L: processing air volume m³/h V: filtration wind speed m/s
Example: Air volume L = 10000m³/h filtration wind speed 2m/min
Filter area A = 10,000/2/60 equals 83.3m²
It is usually considered that the overlapping edge of sewing is about 1 to 2cm, and the length takes into account the mouth flanging plus 10cm.
[(d+1) X3.14]X (length +10) + bottom area = bag area (one) S1
Total area = area per bag X quantity = S1XN = S total
The initial wind resistance of the bag dust collector is 300-500pa, the operating wind resistance is 600-1200pa, and the bag needs to be replaced when it exceeds 1500pa.
Debug:
1. The lifting valve is required to close for no more than 2 seconds, preferably within 1 second, and the opening time is slower. After the valve plate is closed, the gap between the valve plate and the valve plate must not exceed 0.8mm.
2, for the dust collector with more rooms (more than 7 rooms), the cleaning sequence of each room should be jumping.
3, the air leakage rate should be less than 3% when the new filter bag is put into use, there will be trace dust escape from the discharge outlet, which is a normal phenomenon and will eliminate itself.
4, when the dust collector resistance rises to (1200-1500pa), start the cleaning controller for cleaning, and observe the pressure drop, (fixed resistance type can not be set), when the whole system is stable, you can set the cleaning cycle.
Method: Start the work in the automatic state first, and set the cleaning controller time to 1 minute, observe the change of operating resistance, if the resistance has been running below 1000pa, it is said that the Ming and Qing ash interval is too short, if the resistance rises and exceeds 1500pa, it is said that the Ming and Qing ash interval is long. (The cleaning interval should not be less than 15 seconds), and the resistance is suitable between 1200-1500pa.