Application of chemical control valve in Engineering

Application of chemical control valve in Engineering

Chemical control valve uses electric control valve to play the role of variable resistance in the pipeline. It changes the turbulence of the process fluid or provides a pressure drop in the case of laminar flow. The pressure drop is caused by changing the valve resistance or "friction". This pressure reduction process is often referred to as "throttling". For gas, it is close to isothermal adiabatic state, and the deviation depends on the non ideal degree of gas (Joule Thomson effect). In the case of liquid, the pressure is consumed by turbulent flow or viscous friction, both of which convert the pressure into heat energy, resulting in a slight increase in temperature.

The common control loop includes three main parts. The first part is the sensitive element, which is usually a transmitter. It is a device that can be used to measure the adjusted process parameters, such as pressure, liquid level or temperature. The output of the transmitter is sent to the regulator, which determines and measures the deviation between the given or expected value and the actual value of the process parameters, and sends the correction signal to the final control element - the regulating valve one by one. The valve changes the flow of fluid and makes the process parameters reach the expected value.

The valve can be directly driven by an electric spring actuator or a pneumatic actuator. In this case, the energy required to determine the valve position is provided by compressed air, which shall be dried in outdoor equipment to prevent freezing, purified and filtered.

When a pneumatic regulating valve is used together with an electric regulator, an electric pneumatic valve positioner or an electric pneumatic converter can be used. The air supply system of compressed air can be considered as the same as that of full pneumatic regulation system.

Pneumatic control valve is composed of pneumatic actuator and control valve. Its main features are:

1. Beautiful, compact and modern shape, multi specification series products make the selection more economical and affordable.

2. High quality bearings are selected for all moving surfaces, with low friction, long service life and no noise.

3. Simple control and intrinsically safe. No additional explosion-proof measures are required.

4. The extruded high-strength aluminum cylinder body has a long service life, low friction coefficient and rapid action after fine grinding and hard anodizing treatment on the inner surface.

5. Two independent stroke adjustment mechanisms are installed externally to facilitate the adjustment of ± 5 ° fully open or fully closed position.

6. Changing the seal can be used in high or low temperature occasions.

7.Various angular stroke and three position pneumatic actuators can be provided as required.

8. The piston and end cap are made of die-casting aluminum alloy, with high strength and light weight.

However, its basic error and sensitivity are too low, which needs to be improved.