The membrane filter material is composed of the microporous membrane made from the dispersible ptfe resin. The main feature of this filter is surface filtration, which can improve the filtration efficiency, improve the filter pressure increasing frequently in the traditional filtration method, and the high concentration of fine dust emission. Since the 1980s, polytetrafluoroethylene membrane filter has been widely used in many fields such as industrial dust removal and liquid filtration.
1. Filtration mechanism
The mechanism of membrane surface filtration is the same as that of dust layer. Because the pore diameter of the film is very small, the large part of the dust can be resided on the surface of the film to complete the process of gas-solid separation. This process is different from the separation process of normal filter materials, and the dust does not penetrate into the fibers supporting the filter material. Its advantage is: the filter bag work can start on the membrane surface formation permeability good dust in thin layer, higher dust removal efficiency can be ensured and again to make sure that the motion resistance, low and as described above, soot also easy. It should be pointed out that the dust on the surface of the ultrathin membrane stripping, and general filter bag has a big difference between the test surface, composite filter bag dust layer peeling off easily, sometimes not to fly body movements, the dust will fall down. Another important fact is that even if the water is hard dust (such as cement ash), it will be removed at the beginning of the membrane surface. However, if the dust clumping phenomenon is serious or the flue gas is exposed, the membrane filter is powerless, and other measures must be taken to solve it.
2. Polytetrafluoroethylene (PTFE) film.
PTFE film is a three-dimensional network structure without a straight hole. Porosity and pore size distribution are important indicators of PTFE membrane. The opening rate of PTFE membrane is generally between 80% and 95%. High opening rate will improve the ventilation capacity; The pore diameter distribution is concentrated, indicating that the pore diameter is uniform. With special production process, different pore sizes can be controlled for different materials to achieve efficient filtration. Generally, the film thickness is not an indicator of PTFE film. If the thickness of the film is thick, it is easy to produce small air permeability and high operating pressure. According to many years of research, the thickness of the film does not affect the service life. The key is the composite strength, which is an important factor affecting the service life.
3. Compound pathway of membrane.
In order to improve the service life and increase the strength of the film, PTFE film needs to be combined with all kinds of filter materials, such as various needling felt, machine weaving, glass fiber, etc. Because PTFE itself has the characteristics of inadhesiveness, it is very demanding for membrane composite technology. Currently, there are two ways of compound and thermal compound.
The compound mode of the compound is lower than that of the primary compound, which is low in strength, easy to remove film and short of life. Due to the penetration of glue, the permeability is poor, and it is not suitable to clean the ash, which weakens the superior performance of PTFE.
The advanced composite method of thermal complex maintains the excellent performance of PTFE film, but it is strict to the thermal composite technology.
Author: xiechang environmental protection.
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4. Main features
The membrane filter material has excellent performance. The filtration method is membrane surface filtration, and the filter is 100% trapped. The coated press cloth is called dust and material and the new material which is indispensable for the collection and precision filtration. The advantages are as follows.
1) the surface filtration efficiency is high, and the filter material is the deep filtration. It is dependent on the construction of a dust layer on the surface of the filter material to achieve effective filtration. Establish effective filtering time is long (about 10% of the whole filter layer), and resistance is big, efficiency is low, intercept incomplete, loss is big, filtering and high back pressure, soot is frequent, high energy consumption, long service life, covers an area of large equipment. Use laminating filter cloth, dust cannot penetrate the filter material, filtering is surface, both the coarse and fine dust, all deposits on the surface of the filter material, i.e., by membrane aperture intercept itself is initial stage filter, are effective filtering, nearly one hundred percent of the time in the effective filtering.
2) low pressure and high-throughput continuous working traditional deep filtration material, once put into use, dust penetrates, and once a dust layer is established, the air permeability drops rapidly. When filtering, dust caused by internal dust can cause obstruction, thus increasing the resistance of dust equipment. Effect of filter material to micro hole and not sticky, make dust penetration rates close to zero, provide excellent filter efficiency after put into use, when the deposition in the thin film on the surface of the filter material is filter content reaches a certain thickness, can fall off automatically, Yi Qing grey, the filtering pressure is always kept a very low level, air flow always stay at a higher level, can work continuously.
3) easy to clean out any kind of pressure loss directly depends on the operation of the filter material removal by residual or stranded after the dust on the surface of the filter material, the quantity, the effect of filter cloth ash removal time only takes a few seconds, has a very clear grey characteristics of superior, soot cleaning every time to thoroughly remove dust layer, inside the filter material won't cause blockage, will not change and mass density, air voids can work regularly to maintain low pressure loss.
4) long life Effect of filter material whether using life of black fly mechanism, can play to its superior characteristics, is a kind of dust collector design can fully give play to the role of the high efficiency filter filtration material, and low cost. Effect of filter material is a kind of tough and soft fiber structure, with a strong base material compound and into, so have enough mechanical strength, and has the remarkable deashing sex, reduce the intensity of the ash removal, under the low and steady pressure loss, can use for a long time, extend the life of the filter bag.