Reasons for corrosion of PPS dust filter bag

Corrosion is one of the more common causes of damage to PPS dust filter bags. Because the flue gas contains a variety of corrosive substances, the corrosion effect is stronger in a high temperature environment, and the filter bag will be damaged. The main causes of corrosion are hydrolysis, oxidation, acid and alkali corrosion. Among them, due to hydrolysis and oxidation, there is more damage, less acid corrosion, and less alkali corrosion.

One is acid-base corrosion.

The main cause of corrosion is that the flue gas contains acid and alkali components, which have changed with the change of the concentration of these gases. If the dust collector starts or shuts down below, the SO2 in the exhaust gas meets water to form H2SO4, and the filter bag fibers will harden and deform, lose their strength, and be damaged. The traces of corrosion damage are mostly radial, and a large area of discoloration is formed on the surface of the filter bag, which causes the filter bag to become hard and brittle, and a small number of irregular circumferential holes appear. But it is different from the irregular circular hole produced by the spark-burning filter bag, which can be distinguished by the naked eye. In addition to acid-base corrosion, the corrosion of organic solvents on dust collection bags cannot be ignored. For example, the damage of certain micro-content substances in waste incineration exhaust gas to filter bags cannot be reasonably explained at present, because the content of these substances is indeed It is too low to be detected, but they actually exist in the exhaust gas and cause great harm. For example, although the content of bromine vapor (Br2) is very small, the damage to the filter bag is fatal.

The second is hydrolysis

Fiber hydrolysis is a process in which water molecules enter the fiber and chemically react with the polymer to break the molecular chain and produce new small molecular substances. As the molecular weight becomes smaller, the tensile strength of the fiber is weakened and damaged. Synthetic fibers produced from polymers are not resistant to hydrolysis. Commonly used filter materials such as polyester and Nomex are easy to hydrolyze. Only under the combined action of high temperature and high humidity can molecules be activated and hydrolyzed. The higher the content and temperature of water molecules in the flue gas, the more severe the hydrolysis of the filter bag. The hydrolysis temperature of different filter materials is also different. The traces of hydrolysis are turbid, and the strength of the filter bag is severely reduced and easily damaged. After the sewing thread is hydrolyzed, the filter bag cracks from the sewing thread, so that the PPS dust filter bag is no longer cylindrical.

The third is oxidation.

Fiber oxidation is a process in which molecules in the fiber lose (or dissociate) electrons, such as PPS fibers. Under high temperature (150°C) conditions, oxygen molecules attack and bind to the S in the molecule. The PPS fiber will be discolored, hardened, brittle, and damaged due to reduced strength. In severe cases, the fiber web will be broken and separated from the base fabric (as shown in Figure 10). Oxidation is another major factor in filter bag damage. The filter materials with poor oxidation resistance mainly include polyphenylene sulfide (PPS) and so on.