Viti Soot Blowing Steam Source Renovation: Energy Conservation from the Source, Reducing the Burden on Soot Blowing Control Valves

Against the backdrop of the continuous deepening of the "dual carbon" goals and energy conservation and emission reduction in coal-fired power, every gram of coal and every ton of steam in thermal power plants has become particularly precious. The boiler steam soot blowing system, as a crucial link to ensure the cleanliness of the heating surface and enhance thermal efficiency, its steam source selection and valve operating conditions directly affect the safety and economy of the unit.

At present, many power plants still use high-quality steam from the outlet of the separator superheater as the soot blowing steam source, with a pressure as high as 26-27 mpa and a temperature of approximately 500℃. The actual pressure required by the soot blower is only 1.0-1.5MPa, and the temperature is approximately 300℃. The use of high-grade steam for pressure reduction and utilization is itself a huge waste of energy. Meanwhile, the excessively high pressure difference causes the regulating valve of the pressure reducing station to be in a harsh working condition of small opening and high flow rate for a long time, which can easily lead to valve erosion, internal leakage, vibration and noise, and even cause the safety valve to act frequently, endangering the safety of the equipment.

"Using low-parameter steam sources to replace high-parameter main steam for ash blowing" has become a consensus among many power plants in their energy-saving renovations.

    The transformation path is not complicated: a steam channel with matching parameters (such as 5.0MPa, around 350℃) is drawn from the outlet of the low-temperature reheater of the steam turbine and other places as the soot blowing steam source, forming a parallel redundancy with the original high-pressure steam source. When the unit is operating normally, the newly added low-parameter steam source should be given priority. Several 600MW/1000MW units, including those of Datang International Fuzhou Power Plant, Huaneng Jiutai Power Plant, and Guodian Jiangyin Power Plant, have all completed such renovations, effectively reducing the loss of high-quality steam, improving the operating conditions of the ash blowing station, and enhancing the economic efficiency and reliability of unit operation.

    The economic account is clear and calculable. Taking a certain 600MW unit as an example, after thermal balance calculation, using low-temperature reheating steam to replace the original high-pressure steam source can save approximately 1.61 million kWh of steam-equivalent electricity annually. Calculated at the on-grid electricity price of 0.45 yuan /kWh, the annual economic benefit can reach 725,000 yuan (the investment estimate is about 1.2 million yuan, and the cost can be recovered within two years). More importantly, it fundamentally eliminates the safety hazards of high-pressure differential operation, extends the service life of the valve and reduces the frequency of maintenance.

Viti Solution: Ensuring the reliable operation of the soot blowing control valve

After the transformation of the soot blowing steam source, the working pressure difference of the valve has been significantly reduced, and the regulating conditions have been greatly improved. However, extremely high requirements are still placed on the sealing reliability, anti-erosion ability and stability under high-frequency opening and closing of the valve.

Viti Fluid Control offers professional solutions for the harsh operating conditions of soot control valves, including hard alloy surfacing sealing surfaces and erosion-resistant flow channel designs:

• Hard alloy surfacing sealing surface: The key sealing parts of the valve core and valve seat adopt cobalt-based hard alloy surfacing process, which maintains high hardness and excellent wear resistance at high temperatures, effectively resisting the high-speed erosion of trace impurity particles in steam, reducing the risk of sealing surface damage and internal leakage

• Erosion-resistant flow channel design: Combining the concept of multi-stage throttling and pressure reduction, the medium flow path is optimized to effectively reduce the direct impact of high-speed steam on the valve internals and extend the service life of the valve

While power plants achieve energy conservation and consumption reduction through steam source transformation, Viti is committed to making the ash blowing regulating valve, this "checkpoint", more durable, helping the units to walk more steadily and further on the path of safety, environmental protection and economy.

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