PH test of dust
During the test, a small amount of dust attached to the filter bag is put into the glass dish, then completely wetted with distilled water. PH test paper pH meter is used to detect the pH value of dust. The pH results can be used to infer the acid-base corrosion of the filter bag. When the flue gas temperature is lower than the acid dew point, the surface of the filter bag is easy to condense harden, the filter bag is easy to be corroded by acid alkali, thus affecting its service life.
Appearance inspection of filter bag
New bags are often sewn according to the design drawings of the dust collector. The appearance inspection includes only the size uniformity of each sewing of filter bag, but also the needle eye size of filter bag sewing. Pin density, etc. For items with ultra clean discharge, it is also necessary to check whether the needle eye is coated with glue pasted with adhesive tape.
The appearance inspection of Engineering filter bag plays a guiding role, which is usually carried out the following aspects
1. Dust adhesion on the surface of filter bag
If the surface of the filter bag is dewed, hardened pasted, it may be related to high humidity flue gas ammonia escape. After ammonia escaping, it will form ammonium bisulfate with sulfur oxide in flue gas. Ammonium bisulfate has a high viscosity is easy to be removed by pulse injection. The cleaning effect is reduced resistance is easy to increase. the dust adhesion on the surface of the filter bag, the running resistance of the dust collector can be preliminarily judged, so as to play an early warning role in the field operation
2. Color of filter bag
When the chemical properties of the filter bag change, the color will generally change, especially when the PPS filter material is oxidized at high temperature, the color will deepen, the more serious the oxidation, the higher the temperature, the darker the color. Color change can be used as a basis for PPS filter bag to be oxidized used at high temperature.
3. Filter bag feel
When the oxidation of PPS filter bag is serious, the material will become brittle except for dark color. Although high temperature oxidation can make the color of the filter bag darker, the filter bag after high temperature is generally hard can recoil.
4. The filter bag is damaged
The damage of filter bag may occur at the head, middle tail of bag, sometimes even the whole filter bag. The cause of damage is different in different locations. Through the appearance inspection, the cause of the filter bag damage can be preliminarily judged. The damage in a small area is generally mechanical wear, which is often related to the verticality of filter bag the matching of filter bag bag cage. When the filter bag is damaged in large area can be broken by hand, it is related to the serious oxidation corrosion of the filter bag. The filter bag is easy to burn damage when it is attached to combustible materials.
Test of breaking strength elongation at break of filter bag
The elongation at break of breaking strength machine is an important index for the use of filter bags. According to the requirements of GB / T 6719-2009, for ordinary filter materials, the transverse breaking strength should be ≥ 900N, the transverse elongation at break should be ≤ 35%, the longitudinal breaking strength should be ≥ 1200n. Longitudinal elongation at break ≤ 50%. However, GB / T 6719-2009 does make special requirements for filter materials. For PPS PTFE blended filter materials other blended filter materials that are more commonly used in coal-fired power plants, the strength of the filter materials is allowed to be lower in the industry.
The sewing lapping of new filter bags generally adopts seam seam, some manufacturers also adopt hot-melt lap joint. The hot-melt lap joint is only limited to pure PPS filter material, the strength of the hot-melt part must be greater than equal to the transverse breaking strength of the filter material. the practical experience, it is suitable to use hot melt lap joint for the blended filter material.
If the engineering filter bag is damaged, but the overall breaking strength elongation at break are very low, the probability is that the service life of the filter bag has been exhausted. The strength elongation of filter bag are the important indexes to judge the life of filter bag.