How to Select the Proper Anti-static Polyester Filter Bag
Firstly, select it according to the nature of the dusty gas
1. Gas temperature
Dusty gas temperature is an important factor in the selection of the filter bag. Generally speaking, dusty gas of lower than 130 ℃ is called room temperature gas, and dusty gas that is higher than 130 ℃ is called high temperature gas. Therefore, anti-static polyester filter bags can be divided into room temperature filter bags of which the temperature is lower than 130 ℃ and high temperature filter bags whose temperature is higher than 130 ℃. Therefore, an appropriate anti-static polyester filter bag should be selected according to the temperature of the flue gas. In actual work, the gas at 130 ~ 200 ℃ is called medium temperature gas, but anti-static polyester filter bags are mostly selected for high temperature type.
2. Gas humidity
Dust-containing gas is classified into three states based on relative humidity. When the relative humidity is less than or equal to 30%, it is dry gas; when the relative humidity is between 30% and 80%, it is normal; when the relative humidity is more than 80%, it is high humidity gas. At high temperature, especially when the dusty gas contains SO2, gas cooling will cause the phenomenon of condensation. The surface of this anti-static polyester filter bag will not only be fouled and clogged, but also corrode materials, so extra care is required.
3. Chemical properties of the gas.
The flue gas and chemical waste gas of various stoves usually contain a variety of chemical components such as acids, alkalis, oxidants, and organic solvents, and are often affected by multiple factors such as temperature and humidity. Therefore, when choosing an anti-static polyester filter bag, we should grasp the main factors and consider them comprehensively according to the chemical composition of the dust gas.
Secondly, select it according to the nature of the dust
1. The wettability and stickiness of the dust
The wettability of dust can be characterized by the wetting angle. Generally speaking, it is hydrophilic when less than 60 and hydrophobic when greater than 90. The humidity of hygroscopic dust increases, the cohesion and viscosity of the particles increase. The fluidity and chargeability decrease, it sticks to the surface of the anti-static polyester filter bag. When it is out of date, the dust will collapse and stagnate. Some dust, such as CaCl, KCl, MGCl2, naco3, etc., can absorb moisture and cause more chemical reactions.
2. Dust flammability and charging
Some dusts will burn or explode when they encounter flames in the air at certain concentrations. The cause of dust burning or explosion is usually caused by friction sparks, static sparks, hot particles, etc., among which the high charge is more dangerous. Chemical fiber filter bags usually charge well, so dust is easy to spark when charging at the same time. For coal powder, coke powder, alumina powder, magnesium powder and other flammable dust and easy-to-charge dust, choose flame-retardant anti-static polyester filter bags and conductive anti-static polyester filter bags. Anti-static polyester filter bags woven with such fibers as PVC, PPS, p84, or PTFE which has an oxygen index greater than 30 can be impregnated with flame retardants on fibers of which oxygen index is less than 30 such as polypropylene, nylon, and polyamide.
3. Dust flow and friction
If the dust flows and the friction is strong, the anti-static polyester filter bag can be directly worn to shorten the life. The surface is rough and the abrasiveness of irregular particles is 10 times that of smooth spherical particles. Dust particles with a particle size of 90 μm are highly abrasive. If the particle size is reduced to 5 μm to 10 μm, the abrasiveness is very weak. The abrasion is proportional to the 2nd to 3rd power of the airflow speed and the 1.5th power of the particle size, so the airflow speed and its uniformity must be strictly controlled. Aluminum powder, silica fume, coke powder, carbon powder, sintered powder, etc. are usually highly abrasive dust. For abrasive dust, anti-static polyester filter bags with good abrasion resistance should be used.