Corrosion and protection of desulfurization tower-B

15-10-2020

2. Erosion and corrosion: Waste lye contains a lot of solid particles, and solid particles such as dust in the flue gas cause erosion and corrosion. The neutralizing agent used in the flue gas desulfurization tower is magnesium hydroxide. Sodium hydroxide is not used as a neutralizing agent in order to reduce costs. Magnesium hydroxide is a colorless hexagonal crystal or white powder, which is hardly soluble in water, but soluble in dilute acid and Ammonium salt solution, so a large number of undissolved magnesium hydroxide particles are sprayed through the nozzle and sprayed onto the tower wall and part of the downcomer and the surface of the spin bead separator, causing obvious fluid erosion and corrosion. In addition, the small amount of silica impurities contained in magnesium hydroxide and the small amount of catalyst particles distributed in the flue gas also accelerate the erosion and corrosion of the fluid in the tower.

3. Flue gas corrosion: The dew point temperature of the flue gas is related to the flue gas composition. The water vapor content in the flue gas is closely related to the amount of steam introduced. Some research reports analyze that when the water vapor content in the flue gas increases from 10% to 18%, the flue gas dew point increases by 15F° (8°C). In the process operation, a large amount of water vapor is introduced to make the condensed part of the condensate adhere and deposit on the inner wall surface of the desulfurization tower. In addition, the flue gas contains a large amount of CO2 and the existence of oxygen atoms in the flue gas, which promotes the corrosiveness of the flue gas condensate .

The simplest method for desulfurization tower anti-corrosion material as an anti-corrosion layer is to isolate the fluid medium from the substrate. The traditional anti-corrosion measures are to lay stainless steel plates or use glass fiber or resin materials for anti-corrosion work. However, the disadvantages of long-term use are also obvious, such as intolerance to acid and alkali corrosion, intolerance to high temperature, severe erosion and corrosion, resulting in shedding.


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