How to choose industrial filter bag
The first step is to understand the temperature of flue gas to be treated: dust removal cloth bag is the core component of industrial filter bag. It is very important that the selected filter material can adapt to the temperature characteristics of flue gas. For example, if the temperature value of the normally used filter material exceeds the temperature value of the flue gas too much, the equipment investment will increase due to the high cost of the high-temperature filter material. If the temperature of the filter material in normal use is lower than that of the flue gas, it may lead to the combustion of the industrial filter bag and cause huge economic losses.
So how to select the filter material according to the temperature of flue gas? According to the degree of temperature use, the filter materials are divided into constant temperature filter materials below 130 ℃, medium temperature filter materials at 130-180 ℃ and high temperature filter materials at 180-280 ℃.
The second step is to understand the composition of flue gas: This includes dust content, specific gravity, particle size, viscosity, flue gas moisture and other parameters. Through understanding these, the dedusting method of the dust collector, the post-treatment method of the filter material and the filtering wind speed are determined. Generally, pulse industrial filter bags are selected under the working conditions of large amount of dust, viscosity and light dust. The filtering wind speed is mostly controlled above 1.2m/min, and a few working conditions are below 1m / min. Other post-treatment methods of filter materials generally include microporous coating, waterproof, oil-proof, antistatic, etc.
The ash cleaning method of industrial filter bag is another important factor in selecting the structural varieties of filter materials. Due to the different ash cleaning performance and deformation characteristics of industrial filter bags with different ash cleaning methods, different structural varieties of filter materials should be selected.
1. Mechanical vibration industrial filter bag is an industrial filter bag that uses mechanical devices to vibrate the filter bag and remove ash. This kind of dust collector is characterized by less kinetic energy and more times applied to the dust layer. Therefore, the filter material is required to be thin, smooth and soft, which is conducive to transmitting vibration waves and forming sufficient vibration force on the filter surface. Forged or twill fabrics made of chemical fiber should be selected, with a thickness of 0.3-0.7mm, a mass per unit area of 300-350g / ㎡, a filtration speed of 0.6-1.0m/min, and an increase of 1.0-1.5m/min for small units.
The chamber by chamber reverse blowing industrial filter bag adopts the chamber structure, and the valve is used to switch from one room to another to form an industrial filter bag with reverse air flow reverse blowing, so as to shrink or expand the filter bag for dust removal. It can be divided into two states and three states. The ash cleaning times are 3-5 times / h. The ash cleaning power comes from the resource pressure of the dust collector itself. In special occasions, it is equipped with reverse blowing power. It belongs to the type of low kinetic energy ash cleaning. The filter material should be thin, soft, easy to deform and stable in size. There is no difference in the selection of filter materials.
For large and medium-sized dust collectors, round bags, frameless and support rings are commonly used. The bag diameter is 120-300mm, and the length diameter ratio of the filter bag is (15-40): 1, which is better than the selection of forged woven filter material. In special occasions, thin needle felt filter material strengthened with base cloth can also be selected, with a thickness of 1.0-1.5mm. Thin needle felt filter material with good wear resistance and air permeability is preferred, with a mass of 350-400g / ㎡ per unit area. Weft double or double fabric filter material can also be selected.
2. The industrial filter bag of vibration, beating and back blowing refers to the industrial filter bag with the dual functions of vibration and reverse air flow. The vibration loosens the dust cake and the counter air flow makes the dust fall off. The two methods cooperate with each other to improve the ash removal effect, which is suitable for fine particle viscous dust. The filter material selection principle of this kind of dust remover is basically the same as that of the compartment back blowing dust remover, and the forged woven filter material is mainly selected. With the improvement of process level and product quality of needle felt, the development trend is to select thin needle felt with base cloth reinforcement and stable size.
3. The nozzle back blowing industrial filter bag uses the fan as the back blowing and ash cleaning power. When the dust collector is in the filtering state, the filter bag is sprayed successively by moving the nozzle to form a strong reverse air flow. The industrial filter bag for filter bag ash cleaning belongs to the type of medium kinetic energy ash cleaning. There are several forms of dust cleaning with nozzles for industrial filter bags, such as rotary back blowing, reciprocating back blowing and gas ring sliding back blowing. The industrial filter bag of rotary back blowing and reciprocating back blowing adopts the form of external filter flat bag with frame, with compact structure. This kind of dust remover requires the filter material with relatively soft, stable structure and good wear resistance, and the medium thickness needle felt filter material is preferred, with a unit area of 350-500g / ㎡. The gas ring sliding back blowing industrial filter bag belongs to a special form of nozzle sub blowing industrial filter bag. The inner filter round bag is adopted, and the nozzle is in the shape of annular seam, which is sleeved outside the round bag and moves up and down for injection. It is required to select thick, wear-resistant, rigid and lint free filter materials. Compressed felt and needle felt should be selected. Because the filter bag is seriously worn, this kind of dust collector is rarely used.
4. Pulse injection industrial filter bag refers to the use of pulse injection mechanism to release compressed air in an instant with compressed air as power, which induces several times of secondary air to inject into the filter bag at high speed and make it expand rapidly. The industrial filter bag relying on impact vibration and reverse air flow belongs to high kinetic energy ash cleaning. It usually adopts external filter round bag or flat bag with frame. It is required to select the filter material with thick, wear-resistant and strong tension resistance. The filter material of chemical fiber needle felt or compressed felt is preferred, and the mass per unit area is 500-650g / ㎡.
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