The excellent engineering value of vertical submerged long-shaft Multistage  turbine pumps in the power industry (thermal power/nuclear power)

Power industry (thermal power/nuclear power): Pumping guarantee under high-flow cooling and absolute safety

The power industry is another core area for the application of vertical submerged long-shaft pumps, where demand exhibits a "bipolar" characteristic: thermal power systems pursue high flow rates, high efficiency, and long-cycle operation, while nuclear power systems impose almost stringent "zero tolerance" standards for absolute zero leakage, extreme reliability, and nuclear-grade safety. Leveraging its structural advantages, the vertical long-shaft pump has achieved remarkable engineering value in these two distinctly different scenarios.
In the field of thermal power generation, the core challenge lies in providing cooling water circulation with ultra-high flow rate and high head for key equipment such as boilers, steam turbines, and condensers. For a one-million-kilowatt supercritical unit, the circulating water system requires a single pump flow rate of 10,000 to 15,000 m³/h and a head of 40 to 60 meters, operating continuously 24 hours a day, 365 days a year. Traditional horizontal pumps are difficult to meet the dense layout requirements of power plants due to their large footprint, complex installation, and maintenance difficulties. Vertical submerged long-shaft pumps perfectly fit the characteristics of power plants, which require compact space and deepwater intake. Their multi-stage impeller series design easily achieves high head output, with a single pump head reaching over 150 meters, meeting the water supply needs of ultra-high pressure boilers. Their efficient hydraulic model, optimized through CFD, widens the high-efficiency region (BEP) by over 20%. Even at partial loads (such as 70% of rated flow), the efficiency remains above 80%, significantly outperforming traditional pump types, resulting in annual electricity savings of tens of thousands of kWh. In terms of material, thermal power circulating water is mostly treated industrial water containing a small amount of suspended solids, and 316L stainless steel or 2205 duplex stainless steel is commonly used as the flow passage components, balancing corrosion resistance and economy. In a circulating water system renovation project for a large thermal power plant, the original system used four horizontal double-suction pumps, consuming 18 million kWh of electricity annually. After replacing them with two vertical submerged long-shaft pumps (single pump flow rate of 7500m³/h, head of 55m), the system efficiency increased by 12%, saving 2.16 million kWh of electricity annually, equivalent to reducing carbon emissions by 1700 tons. Furthermore, its extractable rotor design greatly improves maintenance efficiency: during maintenance, there is no need to disassemble the pump casing, lifting pipe, or motor. Simply extract the entire rotor assembly axially, reducing maintenance time from the traditional 24 hours to 4 to 6 hours, significantly reducing the loss due to equipment maintenance-induced unit downtime.
In the field of nuclear power, the application of vertical submerged long-shaft pumps rises to the level of "nuclear safety". The cooling water systems of nuclear power plants (such as the containment spray system and residual heat removal system) transport media that may contain radioactive substances. Any leakage could lead to radioactive contamination, and their safety standards far exceed industrial standards. Therefore, the core requirements for nuclear power pumps are absolute zero leakage, nuclear-grade materials, seismic design, and redundant configuration. The "dry motor" structure of vertical long-shaft pumps naturally avoids the risk of motor immersion and becomes the preferred choice. Its sealing system must meet nuclear-grade standards, commonly employing double mechanical seals with multiple barriers, using high-purity deionized water as the barrier fluid, with a leakage rate requirement of less than 0.001mL/h (equivalent to "the amount of water a butterfly drinks"), and equipped with an online leakage monitoring system. The materials of the flow passage components need to pass nuclear-grade material certification, such as 316L stainless steel, which must meet the stringent requirements of ASME B&PV Code Section III, Class 1 or 2, with special provisions for its chemical composition, grain size, and non-destructive testing (such as X-ray and ultrasonic). In the emergency cooling water system of a certain AP1000 nuclear power plant, vertical long-shaft pumps are used to extract cooling water from deep underground wells. The pump shaft is made of ultra-pure 316L stainless steel, the guide bearing is made of silicon carbide ceramic, and the sealing system is a double mechanical seal with bellows, equipped with a nitrogen pressure monitoring and automatic alarm system. This pump set has passed the seismic test conducted by the National Nuclear Safety Administration (NNSA) (SSE seismic acceleration of 0.3g), and is designed with a dual-pump redundant configuration to ensure that in the event of a single pump failure, the standby pump can automatically start within 30 seconds, guaranteeing uninterrupted core cooling. This full-chain nuclear-grade control of "design-material-manufacturing-verification" makes vertical long-shaft pumps an indispensable part of the safety barrier in nuclear power plants.
In terms of the common needs of nuclear power and thermal power, intelligent operation and maintenance is becoming a new engine for enhancing reliability. Modern large-scale power plants generally install IoT sensor networks on vertical long-shaft pumps to monitor key parameters such as vibration, temperature, current, and pressure in real time. For example, in a nuclear power plant, each circulating pump is equipped with three vibration sensors (horizontal, vertical, and axial) and one temperature sensor, with data transmitted to the central monitoring system via fiber optics. The system uses machine learning algorithms to establish an equipment health model. When the vibration speed exceeds 2.5mm/s or the bearing temperature continues to rise by more than 5°C per hour, the system issues an "early warning"; if the vibration speed exceeds 4.0mm/s, it triggers an "alarm" and automatically switches to the standby pump. This predictive maintenance model transforms the traditional "regular maintenance" into "on-demand maintenance", extending the mean time between failures (MTBF) of the pump by more than 30% and significantly reducing the risk of unplanned downtime. In addition, variable frequency control technology is widely used in the power industry. By dynamically adjusting the pump speed according to cooling water demand, it avoids the huge energy waste caused by traditional throttle valves. In a thermal power plant, through variable frequency control, the energy consumption of the pump during low-load periods is reduced by 40%, saving over 3 million yuan in annual electricity costs. In summary, the vertical submerged long-shaft pump is not only an "efficiency engine" for achieving high flow and high efficiency in the power industry, but also a "life guardian" for ensuring the absolute safety of nuclear power. Its value far exceeds that of an ordinary fluid conveying device.