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The temperature and pressure reduction device consists of components such as a temperature reduction unit (or temperature reduction system), a pressure reduction unit (or pressure reduction system), safety devices, a thermal control system, and the main steam pipe. There are a wide variety of temperature and pressure reduction devices. Based on their functional purposes, these devices can be classified into temperature reduction devices, pressure reduction devices, and temperature and pressure reduction devices ； Classified by the steam parameters at the inlet, they can be divided into medium-temperature and medium-pressure types (P1≤3.82 MPa, t1≤450 ℃), sub-high-pressure types [P1≤5.4 MPa, t1≤485 ℃], and high-temperature and high-pressure types [P1≤14 MPa, t1≤570 ℃] of temperature and pressure reduction devices ； Based on their structural design, they can be divided into integrated temperature and pressure reduction units (where the temperature reduction nozzle is located within the pressure reducing valve) and separate temperature and pressure reduction units (where the temperature reduction nozzle is separate from the pressure reducing valve). According to the control method of the valve (i.e., the pressure regulating valve), they can be classified as electric, pneumatic, or manual/self-acting types. The commonly used temperature and pressure reduction devices include the following: 1. Temperature reduction device. The temperature reduction device is composed of a control valve, a check valve, a throttle valve, a globe valve, and a nozzle assembly. Check valves are used to prevent steam from flowing back when the system loses pressure, while throttle valves are used to distribute the pressure difference created by the control valve. High-pressure desuperheating water is delivered to the nozzle in a quantified manner by a control valve, and is injected in a mist form into the high-temperature steam within the venturi tube (or adjustable nozzle), thereby reducing the steam temperature to the value required by the user or the process. The temperature signal at the outlet is transmitted to the temperature control system by a temperature sensor; it is compared with the set temperature, and the result is fed back to the actuator of the control valve in the form of an electrical signal, which adjusts the opening degree of the valve and thus controls the water supply flow rate, with the ultimate goal of precisely regulating the steam temperature. The venturi split-nozzle device is suitable for water pumps with low water delivery head. The nozzle device integrated with the pressure reduction unit is compact, occupies less space, and is widely used. 2. Pressure reduction device: The pressure reduction device consists of an electric temperature and pressure reducing valve (or simply a pressure reducing valve), which regulates pressure by changing the flow area. Secondary or higher levels of pressure reduction also require the use of pressure reduction orifice plates. The pressure regulation in pressure relief valves is accomplished through pressure transmitters and regulators; as the valve opening increases, the degree of pressure reduction decreases ； As the valve opening decreases, the pressure reduction across the valve increases. The self-acting pressure reducing valve assembly regulates the pressure at the outlet of the pressure reducing valve by adjusting the spring, while the pilot valve and diaphragm automatically adjust the opening degree of the main valve disc. Among self-acting pressure relief valve assemblies, the Spiessach type has the highest adjustment accuracy. 3. Safety devices: To prevent the outlet steam pressure from exceeding specified levels, safety valves are installed on the main steam pipeline. When the steam pressure becomes too high, these safety valves open automatically to release excess steam, thereby bringing the system pressure back to safe levels. The safety valves close reliably, ensuring the safe operation of the temperature and pressure reduction device. Safety valves are divided into direct-acting and pilot-operated types. When DN≤150 mm, direct-acting valves are generally used; for medium-pressure steam with DN≥200 mm, pilot-operated safety valves are typically employed to ensure reliable discharge ； The direct-acting type can also be used when the outlet steam is at low pressure, resulting in a simple and lightweight design for the device. 4. Thermal control system: The thermal control system is an important device for regulating and controlling steam parameters. By receiving temperature and pressure signals from the outlet of the temperature and pressure reduction device, it sets the desired pressure and temperature values for the regulators, and operates the actuators to keep the temperature and pressure parameters at the outlet of the device within the range specified by the user, thereby enabling automatic regulation. This control system can also be adjusted manually, or it can be connected to a DCS system to enable remote computer control. 5. Main steam pipe: The main steam pipe is composed of components such as the mixing pipe and steam pipe. Its specifications and structure are determined by the parameters provided by the user; it is the main device of this system, with the steam that has been cooled and depressurized being sent to the pipelines required by the user. Electric gate valves (or stop valves) must be installed at both the inlet and outlet of the temperature and pressure reduction unit for opening and closing purposes.