Pneumatic control valve is one of the industrial process control instruments widely used in petroleum, chemical, electric power, metallurgy and other industrial enterprises. As far as its working principle is concerned, it takes compressed air as the power source, takes the cylinder as the actuator, and drives the valve with the help of electric valve positioner, converter, solenoid valve, retaining valve and other accessories to realize on-off or proportional adjustment, and receives the control signal from the industrial automation control system to complete the regulation of various process parameters such as flow, pressure, temperature, etc. The characteristics of pneumatic control valve are simple control, rapid response, and intrinsic safety, no need to take additional explosion-proof measures.
In application, the noise of pneumatic control valve is the main pollution source in petrochemical production. Cavitation and noise are two main problems in the control of high pressure differential fluid. What are the reasons for these two problems? How to solve this problem? Let's see how Xiaobian solves your puzzles one by one.
3. Mechanical vibration - for example, when the valve core of the pneumatic control valve moves horizontally in the sleeve, the clearance between the valve core and the sleeve can be minimized, or the sleeve with hard surface can be used.
2. Mechanical fluidity of medium - when the medium flows in the pipeline or pneumatic control valve, it will also make noise. For this case, we will not elaborate specifically, of course, cavitation will also produce noise.
4. Natural frequency vibration - for example, the valve core of pneumatic control valve or other components have a natural vibration frequency. For this, the characteristics of valve core can be changed by special casting or forging treatment, and other types of valve core can be replaced if necessary.
1. When the cause factor is the instability of the valve core - if the noise is caused by the pressure fluctuation of the fluid caused by the oscillating displacement of the valve core, this situation is generally caused by the damping factors of the actuator of the regulating circuit. Therefore, the damping coefficient can be adjusted again or the damping facilities can be added to the displacement direction of the valve core.