Main Problems Existing in The Use Of Desulfurization Slurry Circulation Pump

1. Severe wear and tear of flow-passing components
When a slurry circulating desulfurization pump is used for more than one year, serious wear will occur on the impeller, mouth ring, volute and other flow-passing parts.
1) Volute wear:
The inner surface of the volute is covered with honeycomb-shaped uniform pits, and the direction of the marks is consistent with the flow direction of the medium. Consequences: The strength, hardness and toughness of the volute body are weakened, the service life is reduced, the pump return flow is increased, the pump efficiency is reduced, the original rated output cannot be reached, and the process production requirements cannot be met.
1) Impeller wear
If the slurry circulating desulfurization pump is used for more than one year, the impeller will wear, reducing the efficiency of the pump and affecting process production. The blades passing through the inlet side of the impeller are severely worn, and there are grooves on the surface of the outlet side of the blades, with a depth of more than 3mm, and the direction of the marks is consistent with the direction of the medium flow. Impeller wear will affect the dynamic balance and produce operating vibration. Long-term operation will cause process pipe cracks, pump body cracks, etc., endangering the safety of equipment or process pipes.
2. Analysis of main reasons
1) Strong grindability:
The slurry at the bottom of the desulfurization pump contains a lot of liquid particles, mainly coal ash and flue gas desulfurization medium particles. The particle size is usually 0~350 m, about 95% is 30~65 m, and the concentration value is 5%~29% (mass ratio). This kind of liquid particles (especially Al2O3 and SiO2 particles) have strong wear resistance.
2) Strong corrosion:
The circulating slurry is a solid-liquid two-phase flow medium. The main solid components in the slurry are gypsum crystals and a small amount of limestone, with a mass concentration of about 15 to 20%. The slurry is an acidic mixture with an operating pH of 4.5 to 6.0. The chloride ion concentration in the slurry is high. Therefore, the acidity of the slurry itself, the presence of particles and the high chloride ions will cause wear and corrosion of the impeller of the circulation pump. The corrosion resistance and wear resistance of the material of the flow-passing parts of the slurry circulation pump are An important indicator that determines the service life of the pump.
In a typical dolomite (lime powder)-gypsum desulfurization process, the pH value of the drilling mud at the bottom of the tower is 5-6. After adding the desulfurizer, the pH value reaches 6-9.5 (the pH value of the circulating water pump drilling mud is the same as Flue gas desulfurization actual operating standards related). Chloride ions can bioconcentrate to about 80,000mgL and can cause extremely strong corrosion under low pH conditions.
3) Cavitation:
It refers to the serious cavitation phenomenon during pump operation. Cavitation means that when the pump is running, when the absolute pressure of the pumped liquid in the local area of the overflow part is reduced to the vaporization pressure of the liquid at the current temperature, the liquid vaporizes, generating a large amount of steam, forming bubbles, and the bubbles burst and hit the metal surface for a long time. Time cycle operations cause corrosion.
In the desulfurization pump system, the slurry conveyed by the desulfurization pump therefore contains a sufficient amount of gas, while the slurry conveyed by the filtration pump is actually a gas-solid-liquid multi-phase flow. The impact of solid phase pump properties is continuous and uniform, while the impact of gas phase pumps is more complex and unpredictable than the impact of solid phase pumps.
Due to the unique working conditions of desulfurization pumps, harsh environment, severe corrosion and damage, the requirements for metal composites and repair materials are very high.