1. Structural characteristics
The Y-W series temperature and pressure reduction device is the third generation temperature and pressure reduction device designed by our company based on years of design and manufacturing experience, as well as the absorption of excellent product structures from abroad, through technological optimization.
The temperature and pressure reducing device consists of a pressure reducing system (pressure reducing valve, throttle orifice plate, etc.), a temperature reducing system (high-pressure differential feedwater regulating valve, throttle valve, etc.), and a safety protection device (safety valve, check valve). The main features are as follows:
1) Adopting a temperature and pressure reducing split valve structure to first reduce the pressure of steam; Then, the temperature is separately reduced and completed in different systems. The length of the device improves the reliability of operation and facilitates independent adjustment of pressure and temperature.
2) Pressure reducing system: using three different structural forms of pressure reducing valves
⑴ Adopting a straight stroke cage type pressure reducing valve structure, commonly used for t ≤ 400 ℃, P≤2.5MPa， The medium is throttled and depressurized through multiple small holes, and multi-stage throttling and depressurization can be installed inside the valve to increase the service life of the valve body, protect the valve seat and body from impact, extend the service life of the valve, and also reduce the noise of the device.
⑵ Double seat pressure reducing valves are commonly used in conventional temperature and pressure reducing devices with t ≤ 450 ℃ and P ≤ 4.3MPa. The medium throttling channel is in the form of a double seat, with a large flow area. The valve stem throttling point is welded with hard alloy, and the valve stem material is mostly stainless steel or nitride steel. After decades of testing, the double seat pressure reducing valve has not experienced any abnormal problems as long as it is used within the above parameter range. The double seat valve has small unbalanced force, wide adjustment range, smooth operation, and will not cause jamming. The sealing surface of the pressure reducing valve is welded with cobalt based ERCrMn-C-15, which is resistant to high temperature and erosion; The valve seat and disc are ground together for good sealing performance.
⑶ Piston type single seat pressure reducing valve, commonly used for pressure ≤ 9.8MPa, temperature ≥ 450 ℃ or higher parameters. This valve is an improved imported product, with the valve stem and disc as a whole. Multiple plum blossom shaped flow channels are opened at the disc to decompose the steam flow into multiple streams, which can prevent strong vibration inside the valve and reduce noise. The valve is equipped with a curved porous bell cover to prevent steam from directly impacting the inner surface of the valve body. It has the characteristics of low noise, small vibration, good sealing, good pressure reduction effect and regulation characteristics, and long service life. Thermal power plants have been adopted and have received positive feedback.
3) Cooling water spray system: using special structure nozzles, two types of valve structures can be configured
The mixing pipe is equipped with an atomizing nozzle, and the cooling water is sprayed into the pipeline through a regulating valve. Different types of water spraying devices can be flexibly set, including spiral atomizing nozzles. The pressure of the cooling water supply only needs Pb ≥ 0.6P2+0.3MPa;
⑴ Nozzle, the temperature and pressure reducing device produced by our company, is characterized by the nozzle. The steam after pressure reduction enters the temperature reducing system. The "flute shaped" tube nozzle was used earlier. The "flute shaped" tube nozzle sprays the temperature reducing water in a cylindrical shape, with a long mixing section and poor atomization effect. The secondary steam is prone to carry water, which affects the quality of the steam.
Our company has absorbed excellent foreign technology and specially designed an axial swirl mechanical atomization nozzle, which is composed of nozzle body, swirl plate, water pan and other parts. Water passes through the water tray inside the nozzle, and after high-speed rotation and spraying of water by the swirl plate, it forms a mist and is quickly mixed with high-temperature steam to reach the temperature required for secondary steam. The characteristic of swirl nozzle is that the time for water and steam to mix is short, the mixing is sufficient, and it is not easy to block; Avoiding the presence of water in the exported steam and ensuring the quality of secondary steam.
⑶ Configure the water distribution valve, which has two channels. One channel leads to the cooler through the nozzle to reduce the temperature of the secondary steam, and the other channel leads to the deaerator. Conventional temperature and pressure reduction devices are configured according to this.
⑷ Configure a regulating valve, and the outlet of the regulating valve is directly connected to the cooler through the nozzle to reduce the temperature of the secondary steam. When spraying water at a small flow rate (≤ 1.5t/h), a regular regulating valve is applicable; For high-pressure bypass, low-pressure bypass, and special temperature and pressure reduction devices, multi-stage throttling high-pressure differential regulating valves are selected. Users can freely select the valve structure form in the cooling system.
4) Valve flow characteristics: Linear or corrected percentage characteristic curves can be accurately controlled throughout the entire stroke range, ensuring that the secondary steam is within the rated output range of 10% to 100%, and the equipment operates stably for a long time.
5) The temperature water supply regulation system adopts a straight stroke high-pressure differential regulating valve+atomizing nozzle or adjustable nozzle, and the spray flow rate can be constant at 18-23m/s, so as to achieve better atomization effect even at lower steam flow rates. Can reasonably allocate the pressure difference on the water supply system; There are different flow coefficient Cv values to choose from for high-pressure differential water supply control valves of the same caliber, greatly improving the sensitivity and accuracy of temperature regulation systems.
6) The electric pressure reducing valve and electric water supply regulating valve are equipped with a straight stroke electric actuator, which eliminates the traditional lever hinge mechanism, reduces the idle stroke link, and further improves the sensitivity and accuracy of the regulating system. The adjustable nozzle is directly installed on the mixing pipeline, reducing the footprint.
2. System diagram:
