Gas causing corrosion of dust filter bag

Author: Site Editor     Publish Time: 2021-08-18      Origin: Site


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As a commonly used dust and flue gas filter material, as long as the type is selected properly, the service life of the dust filter bag is generally more than one to two years, and it only accounts for 20% of the operating cost of the dust collector. When air or dust needs to be processed by a bag filter, the composition and content of corrosive gases must be carefully analyzed during the selection to ensure the long-term normal operation of the dust filter bag.

   The corrosion of dust collection bags is often caused by three gases. We have concluded that the following three gases will cause the corrosion of dust collection bags.

1. The problems that are prone to occur in the bag used in the bag filter of coal-fired boiler

Strong oxidizer: For example, when the PPS dust filter bag is working at 160℃, when the oxygen content exceeds the standard (>10%), a large amount of oxygen can attack the S bond in the PPS molecule and combine with it. The result of the reaction is: PPS fiber becomes dark and brittle, and its strength decreases. Sometimes you will find that the surface color of the PPS fiber bag exposed to the sun will turn into a brown color. If it is not treated for a long period of time, it will easily cause the fiber strength to decrease, and cause the dust filter bag to be damaged due to the decrease in strength. The air contains 21% oxygen and 79% nitrogen (volume ratio). When the temperature is not high, nitrogen is very stable, but high temperature will break the molecular chain of nitrogen and react with oxygen to form NO and NO2. NO can not be considered too much, but NO2 is a strong oxidant and can oxidize most fibers used for filtration . Oxidants include nitrogen oxides, hydrogen sulfide, ammonia, and chlorine. Enhancing control on the process and equipment can reduce oxidation corrosion.

2. The problem that the dust filter bag used in the kiln working condition bag filter is prone to occur

Acidic gas: mostly occurs in the working condition of using high temperature filter material, mainly sulfide. If the high temperature flue gas contains a lot of acid gas, it is recommended to use a dust filter bag with better acid resistance. If a common dust filter bag is used, the acidic flue gas will corrode the fiber structure in the dust bag, resulting in a decrease in the strength of the dust filter bag and eventually breakage. The damage marks are from the outside to the inside. Lowering the temperature can reduce the corrosion of the dust filter bag by acid gas. Acid gases include sulfur dioxide, sulfur trioxide, hydrogen sulfide, hydrogen chloride, hydrogen fluoride and so on.

3. The problems that are prone to occur in the bag used in the bag filter in the chemical soda industry

 Alkaline gas: mostly appear in working conditions containing ammonia gas, mainly ammonia gas. For damage and acid corrosion, lowering the temperature can reduce the corrosion of the dust filter bag bag by alkaline gas.


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