How can a control valve generate such high pressure?
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The last edit to this post was made by sxf1028102800 on 2025-1-10 at 18:02. I have a question: many chemical processing units operate under high pressure, with pressures exceeding 50 kilograms per square centimeter. For example, the pressure in a reactor in one such unit is over 80 kilograms per square centimeter, and a control valve is needed to regulate this pressure. How does the control valve generate the necessary pressure to open or close pipes under such high pressures? The wind pressure of the wind pressure control valve is generally 5-6 kilograms. I’m not quite sure about this; those who know could please provide a detailed explanation? Thank you
Pressure and force are two different concepts. To put it simply, consider this analogy: if the area of the valve plug in a globe valve is S1, the pressure of the fluid is P1, the air pressure supplied to the actuator is S2, and the cross-sectional area of the piston in the actuator’s cylinder is P2, then as long as S2*P2 > S1*P1, the valve will open
In chemical processing units, control valves are used to regulate the flow rate, pressure, and other parameters of fluids, ensuring the stable operation of the process. When dealing with high-pressure fluids, the design and operating principles of control valves are crucial. ### Working principle of control valves: 1. **Valve body structure**: Control valves typically consist of a valve body, a valve core, a valve seat, and a driving mechanism (such as pneumatic, electric, or hydraulic actuators). The valve body is designed to withstand high pressure, and is typically manufactured from materials with high strength and corrosion resistance. 2. **Actuator**: The function of the actuator is to provide sufficient force to move the valve core in order to open or close the valve. In high-pressure systems, the actuator needs to generate a considerable amount of force in order to overcome the counterforce exerted by the fluid pressure on the valve element. 3. **Force amplification**: Although the input pressure of actuators (such as pneumatic actuators) (e.g., 5–6 kilograms) is much lower than the operating pressure of the system (e.g., 80 kilograms), these forces can be amplified through proper design. Actuators typically have a large piston area; when gas pressure acts on this large area, the resulting force is sufficient to operate the valve. This is achieved through a combination of air pressure and mechanical advantage (such as the lever principle). 4. **Valve Positioner**: A valve positioner is a control device that receives control signals (such as 4-20 mA current signals) and precisely controls the operation of the actuator, ensuring that the valve opens or closes as required. ### Summary: The ability of a control valve to handle high-pressure fluids relies primarily on its structural design and the force-amplification mechanism of its actuator. By using high-strength materials and a well-designed force amplification system (such as large-area piston and lever systems), the control valve can effectively manage high-pressure fluids even at low input pressures. This design makes control valves very important and effective for high-pressure applications in industries such as chemicals, oil, and gas. .
The thrust generated by pressure times area varies
It’s not pressure, but rather the pressure difference between the front and back; as for wind pressure, it depends on the area over which the membrane head is under stress.