How to solve the noise problem of the regulating valve

Cavitation and noise are two major hazards of control valves when regulating fluids with high pressure differentials. Noise generated by control valves is a primary pollution source in petrochemical production. In application, apart from selecting control valves with low-noise structures, altering the operating conditions of the valve is a fundamental method to eliminate or reduce cavitation and noise. When a control valve is in operation, its noise level should be monitored. Analyzing the noise generation mechanism enables better monitoring of the working status of the control valve and effective resolution of emerging problems.

(1) Natural frequency vibration: The valve plug and other components each have a natural vibration frequency. This can be addressed by modifying the characteristics of the valve plug through dedicated casting or forging treatments, and other types of valve plugs can be replaced if necessary.

(2) Mechanical vibration: When the valve plug moves horizontally inside the sleeve, the clearance between the valve plug and sleeve can be minimized, or sleeves with hard surfaces can be adopted.

(3) Valve plug instability: Noise arises from fluid pressure fluctuations caused by oscillatory displacement of the valve plug. This condition is generally triggered by damping factors within the control loop actuator. The damping coefficient can be readjusted, or vibration reduction devices can be installed along the displacement direction of the valve plug.

(4) Mechanical flow characteristics of the medium: Noise can also be produced when the medium flows through pipelines or control valves. This scenario will not be elaborated here (cavitation can also generate noise).