Four types of chemical corrosion to which baghouse filter bags are subjected
The filter bag of the bag filter filter will lose the filtration performance of the filter bag itself in the process of chemical corrosion, because the mechanical properties of the material in the filter bag are greatly reduced after corrosion, resulting in the filter bag in the process of filtering dust, because the scouring force of the air flow on the filter bag is higher than that of the filter bag after corrosion, so that the filter bag is broken by the air flow, thus losing the basic filtration capacity.
1. Acid corrosion of filter bags
Acid corrosion is caused by the acid condensation paste bag in the flue gas, and the reasons are: in the case of acid in the flue gas, there is a large amount of water in the gas environment where the filter bag is located, and the water vapor containing acidic substances adheres to the surface of the filter bag for corrosion due to the existence of water leakage defects in the equipment. The dust emitted by coal-fired boiler power plants contains a large amount of sulfide, which is replaced by sulfurous acid, sulfurous acid, Sulfuric acid and other forms adhere to the surface of the filter bag to corrode the filter bag, and eventually lead to a significant reduction in the mechanical properties of the filter bag due to corrosion, and damage to the filter bag after being subjected to air flow impact or direct strong corrosion, resulting in the failure of the filter bag, for example, when the gas contains hydrofluoric acid, it will produce strong corrosion of the filter bag of glass fiber material, so in the actual use of the filter bag, it is necessary to select appropriate materials according to the substances contained in the exhaust gas to avoid acid corrosion of the filter bag.
When the filter bag is corroded, the strength of the filter bag will be significantly reduced, and the fiber falls off on the surface of the main body of the filter bag, resulting in the tearing phenomenon of the filter bag in the process of being subjected to a small tensile force, and the corrosion types of the filter bag include acid, alkali, oxidation, hydrolysis corrosion, etc.
2. Alkali corrosion of filter bags
In special circumstances, such as cement plants, steel plants and other special locations, due to the gas emitted contains sodium salts, ammonium salts and other substances, such substances are easy to generate alkaline substances such as sodium carbonate when they encounter water vapor, and alkaline substances such as sodium carbonate are easily generated to produce alkaline corrosion of the filter bag.
3. Oxidation and corrosion of filter bags
When the filter bag is affected by oxygen, nitrogen oxides and other substances with certain oxidizing properties for a long time, the filter bag will be damaged due to oxidation corrosion, and the materials that are often oxidized and damaged are mainly concentrated in PBS materials, due to the particularity of the structure of PBS materials, they are susceptible to oxidative corrosion of oxygen, nitrogen oxides and other substances, and PBS materials are often accompanied by color deepening, brittleness increase, and mechanical properties decline after corrosion.
4. Hydrolysis of filter bags
The composition of the filter material used in some filter bags, such as polyester, NOMEX and other materials, is easy to decrease under the action of water, resulting in a decrease in the degree of polymerization of macromolecules, which greatly reduces the mechanical properties of the materials and causes the filter bag to be damaged. Due to the harsh conditions of material hydrolysis and the certain requirements for the temperature, humidity and catalysts of the hydrolysis environment, the hydrolysis process of the filter bag has a small probability of occurrence in the actual application of the filter bag. When the filter bag is hydrolyzed, it can be replaced with a filter bag made of filter materials such as PBS, PTFE and other materials, which are non-polycondensation and therefore difficult to produce hydrolysis.
The above-mentioned various chemical corrosion damage to the filter bag belongs to chemical damage, because the chemical damage includes acid, alkali, oxidation, hydrolysis and other damage forms, and these damage forms will inevitably cause certain damage to the joint of the filter bag, therefore, the joint of the filter bag needs to consider the corrosion resistance to make provisions.