Heating renovation and flexibility renovation: Key valve support for Vitec

Under the impetus of the "dual carbon" goals and the "three reforms in tandem" policy, the heating and flexibility renovations of thermal power units have become the core paths for the transformation and upgrading of coal-fired power. Whether it is the shift from pure condensing units to cogeneration or the realization of deep peak shaving through zero-output technology of low-pressure cylinders, the control and protection of the extraction pipeline cannot do without the precise coordination of key valves.

In this transformation, gate valves, check valves, butterfly valves and desuperheating and pressure reducing devices are the four most core types of valve products in the heating renovation.

I. Electric Gate Valve: The "Safety Door" of the Steam Extraction Pipeline

In the heating renovation, when steam is extracted from the reheating section for external heating, a shut-off valve needs to be installed on the extraction pipeline. Electric gate valves undertake the dual responsibilities of "on-off" and "isolation".

    Typical application: In the 2×1000MW ultra-supercritical heating renovation project of the second phase of Guoneng Lingwu, the electric shut-off gate valve supplied by Viti was made of F92 material and forged as a whole. It has a working temperature of 608℃ and a pressure of 5.67MPa. It features a full bore design and bidirectional sealing with zero leakage. In the comprehensive energy steam supply renovation of Pingluo Power Plant, Viti also provided 1500LB 24" F92 electric gate valves to meet the steam extraction shut-off requirements under the high-temperature condition of 628℃.

    Technical points: The heating and steam extraction pipelines are mostly high-temperature and high-pressure steam (P92 material, above 600℃). The Viti gate valve must adopt an integral forging process, with hard alloy surfacing on the sealing surface to ensure no internal leakage or sticking during long-term high-temperature operation.

Ii. Pneumatic Check Valve: The "Safety Bolt" to Prevent Steam Backflow

The steam extraction check valve is the most crucial safety protection device in the heating renovation. When the unit is unloaded or trips due to an accident, the high-pressure steam in the extraction pipeline may flow back into the steam turbine in the opposite direction, causing overspeed or water shock - these are the two most serious accidents of steam turbines. The function of the steam extraction check valve is to forcibly close at the moment of an accident (in milliseconds), blocking the reverse flow path.

    Typical application: For the 2× 660,000-kilowatt coal-fired power infrastructure synchronous heating project of Changdong Power Generation in Xinjiang, Viti supplied 2 pneumatic check valves for the steam extraction in the hot section. This project is located in the Zhundong Economic Development Zone, Xinjiang, with a total investment of 5.6 billion yuan and a total installed capacity of 1,320 MW. It will also build a steam supply project for the hot section simultaneously, and the supply targets are industrial projects within the Zhundong Development Zone.

    Technical key points: The Viti steam extraction check valve must adopt a gas-open and spring-close structure, and have the ability to quickly and forcibly close (closing time ≤0.5 seconds). The material of the valve body must be consistent with that of the pipeline (F92/P92), and the sealing surface must be surfacing with hard alloy. It also has the function of valve activity test to prevent jamming when fully open at high temperature for a long time.

Iii. Three Eccentric Metal Hard Seal Butterfly Valve: The "All-Rounder" for Regulation and Quick Closing

In the heating system renovation, the butterfly valve of the connecting pipe is the core equipment for achieving zero output (cylinder cutting) of the low-pressure cylinder. It should not only have the normal regulation function (controlling the steam intake flow), but also quickly shut down in case of an accident to prevent the steam turbine from overspeeding.

    Typical application: For the heating renovation project of Huadian Wangting Power Plant, Viti supplied the world's first F92 1500LB hydraulic quick-closing valve, which was applied in the longest distance heating renovation project in China. This valve adopts a three-offset all-metal hard seal structure, featuring dual functions of regulation and rapid shut-off, and is responsible for the safety protection of long-distance heating pipelines.

    Technical advantages: The Viti all-metal hard-sealed butterfly valve adopts a bidirectional pressure-bearing zero leakage design. The sealing surface is surfacing with Stellite alloy, which is resistant to erosion and has a long service life. The patented structures such as drive spline connection, dynamic balance packing system and rigid self-locking have further enhanced the reliability and maintainability of the valve.

Iv. Temperature and Pressure Reducing Device: "Regulator" of Steam Parameters

The parameters of the steam extracted from the reheating hot section are often higher than the user's requirements (such as 608℃, 5.67MPa to 250℃, 2.0MPa), and it must be regulated by a desuperheating and pressure reducing device before it can be used for external heating. The desuperheating and pressure reducing device is a key piece of equipment for achieving "parameter matching" in heating renovation.

    Typical application: Viti once undertook the EP project of the largest desuperheating and pressure reducing station in China, extracting steam from multiple sources such as the superheater, reheating of the cold and hot sections, and the middle exhaust, including two process packages: emergency gas source and main line gas source. This device integrates a complete set of equipment such as pressure reducing valves, desuperheating water regulating valves, safety valves, and electric isolation valves, ensuring the stability and reliability of the heating steam parameters.

    Technical key points: The Vite desuperheating and pressure reducing device must have a wide load regulation capability to adapt to the load fluctuations of the unit. The multi-stage voltage reduction design effectively reduces noise and vibration. The safety valve configuration ensures overpressure protection.

V. Performance as Evidence: Vitai's Heating Renovation Practice

With its German technological heritage and global manufacturing layout, W&T has provided key valve matching for many large-scale heating renovation projects.

Viti - based on German technology and supported by global manufacturing, provides a complete set of valve solutions for thermal power heating and flexibility transformation, ranging from gate valves, check valves, butterfly valves to desuperheating and pressure reducing devices.