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Hi, this is the Industrial Control Assistant. Today we will give a brief introduction to the types of actuators used in control valves. Power generation is usually divided into two types. The first type is called a direct-flow boiler; it is designed such that the feed water turns into steam as it passes through the boiler tubes, thus eliminating the need for a separate steam drum. The pressure in boilers of this type is usually above the critical pressure of water, which is 3206 psia; most once-through boilers are \"supercritical,\" with the operating pressure of the turbine being around 3500 psi. However, there are also some sub-critical DC boilers in use. Large direct-flow supercritical boilers are more efficient than drum-type boilers, but their drawback is that they are difficult to start and have poor capacity to handle variable loads. Every Fisher control valve is a valve that may be subjected to harsh operating conditions such as cavitation, flashing, noise, or high pressure with low flow rates. The second type utilizes a drum boiler to separate steam from boiler feed water; boilers of this type are generally referred to as \"subcritical,\" with a boiler pressure lower than the critical pressure of water, and the pressure range is roughly between 2400 and 2800 psi. Water-tube boilers are widely used in commercial and industrial power plants due to their simple structure, ability to handle load fluctuations, and relative ease of startup. We divide the entire system into five subsystems, including the condensation system, feedwater system, main steam system, heater drain system, and pulp washing and ash treatment system.