Abstract
The internal steam fluid pressure pulse force is the excitation source of control valve. Based on the Lighthill equation and the orifice injection shunt noise reduction theory, the flow noise and air noise calculations of throttling devices are carried out for the eccentric rotary control valve and the cage sleeve control valve, and the design improvements are presented for noise control of the valves. When there is no noise reduction internals, the air noise caused by the steam control valve with a pressure of 4.5MPa in front of the valve is greater than 95dB. The preset orifice plate reduces the pressure in the control valve to 50% of that before the valve, then the small hole Shunt method for noise reduction can be employed. When the two-stage orifice plate is installed and the number of second-stage holes is greater than 100, the air noise of the eccentric rotary steam control valve is lower than 80dB, and the first-stage orifice plate is installed. The air noise of the bored sleeve type steam control valve with preset orifice plate is also lower than 80dB, but it is easier to meet the low noise design requirements of the steam control valve than the improving method used in above sleeve type steam control valve.
Highlights
When the working medium passes through the valve, the irregular pressure fluctuations and the impact of the medium on the valve components will cause some parts of the valve as the valve core, stem, bracket and the pipeline connected to vibrate, thereby radiating Mechanical noise
The principle of multi-stage pressure reduction refers to the design of a multi-stage pressure reduction structure according to the given flow and pressure drop of the system operation, and appropriately adjust the flow area and the number of pressure reduction stages of the throttling device, so as to make the original large pressure drop
Small hole injection noise reduction theory The Lighthill equation has been recognized as the basic equation for studying aerodynamic noise
Summary
When the working medium passes through the valve, the irregular pressure fluctuations and the impact of the medium on the valve components will cause some parts of the valve as the valve core, stem, bracket and the pipeline connected to vibrate, thereby radiating Mechanical noise. The principle of multi-stage pressure reduction refers to the design of a multi-stage pressure reduction structure according to the given flow and pressure drop of the system operation, and appropriately adjust the flow area and the number of pressure reduction stages of the throttling device, so as to make the original large pressure drop It becomes a multi-stage small pressure drop, and achieves the purpose of reducing valve noise. It can reduce the eddy current and cause the noise energy to be biased towards high frequency in the frequency distribution
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