What should be noted when selecting a cooling water regulating valve for power stations? Why do vibrations and whistles often occur?

Answer: The fundamental cause of vibration and whistling is improper selection, especially an excessively high CV value and insufficient throttling level.

I. Why do vibrations and whistling occur?

• The CV value is set too high: When the valve operates at a small opening (<30%) for a long time, the medium flow rate is too high, causing high-frequency vibration and sharp whistling

• Insufficient throttling level: The pressure difference of the reheater's desuperheating water is large, and the single-layer sleeve cannot effectively reduce the pressure, resulting in flash evaporation and cavitation

• Insufficient closing force: The thrust of the actuator is too small, the valve cannot be closed tightly, and the medium continuously eroses the sealing surface

Ii. What should be noted when selecting a model?

1. Verify the actual parameters on site: Do not merely look at the design drawings; it is necessary to verify the real data such as the pressure, pressure difference, temperature, and flow rate before and after the valve

2. Accurately calculate the CV value: Ensure that the valve operates within the 30% to 80% opening range and avoid long-term operation at a small opening

3. Select an appropriate throttling structure: For high-pressure differential conditions, multi-layer sleeves or multi-stage pressure reduction structures must be chosen

4. Confirm the closing force and sealing material: The thrust of the actuator should be sufficient, and the sealing surface should be surfacing with hard alloy.

Viti Tip: Over 80% of the problems with the desuperheating water regulating valve occur during the selection process. Viti adheres to the service process of "diagnosing on-site parameters first and then precisely calculating and selecting the model", avoiding problems such as vibration, whistling and internal leakage from the source.