Selection and Application of Temperature and Pressure Reducing Devices - Problem Chain and Professional Answers

The desuperheating and pressure reducing device is the core equipment for converting high-temperature and high-pressure steam into the parameters required by users in cogeneration, centralized heating and industrial heating systems. It is widely used in industries such as power, chemical engineering, metallurgy, pharmaceuticals and food. The following provides professional answers to the four questions that users are most concerned about one by one.

Q1: What are the core components of a desuperheating and pressure reducing device?

Answer: The desuperheating and pressure reducing device is an integrated system, usually composed of six core parts.

1. Pressure reducing system: Composed of a pressure reducing valve and a throttle orifice plate, it reduces high-pressure steam to the required pressure by changing the flow area. When the pressure difference is large (ΔP>3MPa), a multi-stage pressure reduction design should be adopted to reduce the load of each stage.

2. Desuperheating system: The cooling water is atomized by a high-pressure differential regulating valve or a variable frequency water pump and then sprayed into the steam pipeline to reduce the steam temperature.

3. Main steam pipe body: Composed of a mixing pipe and a steam pipe, it serves as the steam transportation channel after temperature and pressure reduction.

4. Safety protection system: Equipped with a safety valve (spring type or impulse + main safety valve), which automatically releases pressure when the outlet pressure exceeds the limit.

5. Thermal control system: Signals are collected through temperature and pressure sensors, and the PID controller drives the actuator to automatically adjust the outlet parameters.

6. Auxiliary equipment: including stop valves, check valves, desuperheating pipes, flanges, fasteners, etc.

Structural form: It is mainly divided into two types: integral type (temperature reduction and pressure reduction are completed in the same valve body, with a compact structure) and split type (temperature reduction and pressure reduction are carried out separately, with higher control accuracy and more flexible layout).

The technical features of W&T: The W&T temperature and pressure reducing device adopts mature structural design and intelligent control technology, featuring high regulation accuracy, fast response speed, anti-erosion, low noise, and long service life. It is suitable for multiple fields such as cogeneration, thermal power generation, and petrochemicals.

Q2: When selecting a temperature and pressure reducing device, what key parameters should be focused on?

Answer: The selection must be based on the working condition parameters, and the core should focus on the following three major dimensions:

1. Pressure parameter matching

Clarify the inlet pressure (P1) and outlet pressure (P2), and calculate the pressure difference (ΔP=P1-P2) to determine the number of pressure reduction stages

When ΔP≤3MPa, single-stage pressure reduction can meet the requirements. When ΔP>3MPa, multi-stage pressure reduction (usually 2-3 stages) should be adopted. By gradually reducing the pressure, the pressure load of each stage is decreased to reduce the erosion of the valve core and noise

2. Temperature parameter matching

It is clear that the temperature difference between the inlet temperature (T1) and the outlet temperature (T2) determines the design of the desuperheating system

When ΔT≤100℃, simple jet cooling can be adopted. When ΔT>100℃, an enhanced atomization structure should be adopted to ensure that the desuperheating water is fully mixed and evaporated with the steam

For scenarios where superheated steam is cooled to saturation temperature, a superheat of 5 to 10 degrees Celsius should be reserved to prevent the steam from carrying water

3. Flow rate and regulation ratio

The designed flow rate of the device needs to cover the maximum flow rate (Qmax) and the minimum flow rate (Qmin), and it is usually required that the regulation ratio be ≥10:1

The outlet steam flow rate should be stably adjustable within the rated range of 30% to 100%

For systems with large flow fluctuations, devices with wide range regulation capabilities should be selected

Q3: What unique advantages does W&T have in the field of desuperheating and pressure reducing devices?

Answer: Relying on the technological heritage of Germany and the complete machine production model of the Russian production base, Viti has formed three core advantages in the field of temperature and pressure reducing devices.

1. German technological foundation

The technological heritage of Vitesse can be traced back to Frankfurt, Germany in 1932. In 1953, a regulating valve capable of simultaneously reducing temperature and pressure was developed, integrating the pressure reduction of high-temperature and high-pressure steam with water spraying for cooling. Viti has been deeply involved in the research and development project of valve materials for the "725℃" ultra-supercritical units in Europe and has always been at the forefront of global thermal power technology. The company invests 10% of its total profit in research and development every year and uses Dassault Solidworks software for advanced design methods such as motion simulation, stress analysis, and flow field analysis.

2. Complete machine production at the Russian production base

Viti has established a wholly-owned manufacturing subsidiary in Russia, equipped with a large number of first-class processing and testing equipment from Germany and Japan, including key equipment such as machining centers, CNC vertical lathes, automatic submerged arc surfacing welding machines, and electric heating heat treatment furnaces. The key components of each Viti desuperheating and pressure reducing device are all core manufactured and fully assembled in the Russian factory in accordance with German technical standards. Imported valve products are directly supplied to the Chinese market to ensure that the quality is consistent with that of the country of origin.

3. Verification of mature performance

The Viti desuperheating and pressure reducing device has accumulated mature application cases in many large-scale industrial projects. For instance, the high-precision and large-flow heat supply type desuperheating and pressure reducing device, which was tailor-made for the 2×300MW unit desulfurization flue gas waste heat recovery project of Weitai Baishan Thermal Power Co., LTD., has achieved safe and stable operation for nearly half a year continuously. The performance indicators of the equipment are excellent and have been highly recognized by users. In addition, Viti has also undertaken large-scale EP projects for temperature and pressure reduction stations, such as the heating renovation of 2×1034MW units at Huaneng Haimen Power Plant.

Qualification Assurance: The Vitti factory in Russia has officially obtained the Special Equipment Production License (TS Certification) and the Special Equipment Type Test Certificate (TSG Certification) issued by the State Administration for Market Regulation, meeting the market access requirements for domestic pressure pipeline valves.

Q4: What are the common problems of temperature and pressure reducing devices on site? How to avoid it?

Answer: The common problems encountered on-site with desuperheating and pressure reducing devices mainly include the following types, which can be avoided during the selection and installation stages.

1. Pipeline deformation and suspension of supports and hangers

Excessive temperature differences between the upper and lower sections of the pipeline will cause axial bending deformation of the pipeline, resulting in the disconnection of the supports and hangers. When selecting the type, a detailed stress analysis of the pipeline should be conducted, and the positions of the supports and hangers should be reasonably arranged. During installation, strictly follow the design drawings for construction to ensure uniform load-bearing of the supports and hangers.

2. Weld cracking

If the secondary stress generated during the thermal expansion and contraction of the pipeline exceeds the standard, cracks are prone to occur at stress concentration points such as the large and small heads. When selecting the type, it is necessary to ensure that the stress calculation of the piping system complies with the specifications, avoid sudden diameter changes in the pipeline after the pressure reducing valve, and reasonably design the flexibility of the pipeline.

3. Insufficient adjustment accuracy

If the range of flow fluctuation is not fully considered during the selection process or the response speed of the actuator is insufficient, it will cause the outlet parameters to deviate from the set values. Devices with PID closed-loop control should be selected, equipped with high-precision sensors and servo actuators to ensure that the temperature control deviation is ≤±1℃ and the pressure deviation is ≤±0.02MPa (precision process requirements).

4. Poor cooling effect

Insufficient atomization of the desuperheating water can cause the steam to carry water or the temperature to fail to drop. When selecting the model, an appropriate atomization structure should be chosen based on the temperature difference. For large temperature difference working conditions, enhanced atomization nozzles and multi-hole mixing sections should be designed.

Vitec's response strategy: Vitec offers full-process technical support from on-site parameter collection, selection calculation to installation and commissioning, adhering to the service model of "diagnosis first, selection later, and manufacturing later" to avoid on-site problems from the source.

Summary

The core logic for selecting a desuperheating and pressure reducing device is as follows: First, clearly define the parameters of the inlet/outlet steam (temperature, pressure, and flow rate), then determine the number of pressure reduction stages and the desuperheating scheme based on the pressure difference and temperature difference, and finally choose a professional brand with German technical background, Russian complete machine production qualifications, and similar project performance.

Scientific selection steps

Analyze the working condition parameters: inlet pressure/temperature, outlet pressure/temperature, and flow range

Judging the structure and regulation scheme: The pressure difference determines the number of pressure reduction stages, and the temperature difference determines the cooling method

Matching execution and control: Select the actuator and control system based on the regulation accuracy requirements

Verify the supplier's qualifications and performance: whether they have TS/TSG access qualifications and similar project cases

W&T, based on German technology and supported by the complete machine production at its Russian production base, provides reliable solutions with imported quality and full-process technical support for the selection of desuperheating and pressure reducing devices.