Cases analysis of H series right-angle gearboxes for vertical long-shaft rainwater turbine pump in power plant rainwater lifting system

This case focuses on the renovation project of the rainwater lifting system in the plant area of a 660MW supercritical thermal power generating unit. It adopts a customized high-reliability H-series right-angle gearbox to drive a vertical long-shaft rainwater pump, addressing the core pain points of traditional direct-coupled drives under extreme rainstorm impacts, limited space in underground pump rooms, and dusty and humid working conditions. This ensures 100% emergency response reliability for the power plant's rainwater system, completely avoiding the significant safety risk of unplanned unit shutdown caused by rainstorm flooding in the plant area.
🏭 Project background and original pain points
The total installed capacity of the power plant is 2×660MW, and the rainwater lifting system in the plant area is designed with a rainstorm drainage capacity of 1800m³/h, responsible for the collection and drainage of rainwater from roads, coal yards, and the main power building area of the entire plant. The original system adopted a vertical rainwater pump scheme directly driven by a conventional motor, which exposed multiple fatal safety hazards during operation:
The underground pump room is severely lacking in space: the basement floor of the rainwater pump room has a height of only 3.3m, and the vertical motor is directly stacked above the pump body. The total axial height of the unit exceeds 3.1m, resulting in insufficient space for daily operation and maintenance crane lifting. When dismantling the pump body for slag removal and maintenance, it is necessary to temporarily remove the ventilation and pipeline facilities on the top of the pump room. Each maintenance session takes more than 48 hours, and the rainwater system is in a non-standby state for extended periods, posing a high risk of flooding in the factory area during extreme rainstorms.
Rainstorm impact and frequent axial overload: Under extreme rainstorm weather, rainwater carries a large amount of impurities such as coal slag, sediment, and fallen leaves. The axial thrust of the pump during operation surges instantly by 60%. The original vertical motor comes with a thrust bearing with a rated load capacity of only 62,000N. Under the long-term impact of alternating impact loads, bearing burnout failures occur on average every 7 months, and the unplanned failure rate of the rainwater system is as high as 18%, posing a direct threat to the safe operation of the unit.
Rapid wear in dusty and humid environments: The rainwater pump room is located adjacent to the coal yard, where a large amount of coal dust particles are present in the air. At the same time, the pump room is exposed to high humidity for extended periods. The sealing and protection level of ordinary gearboxes is insufficient, making it easy for coal dust and moisture to penetrate the interior. This results in rapid abrasive wear on the gear meshing surfaces, leading to pitting corrosion on the tooth surfaces and excessive vibration faults on average every 11 months. The equipment maintenance and operation costs are more than three times that of ordinary clean water pumps.
Poor adaptability of emergency response: The original direct-coupled drive scheme cannot adapt to diesel engine backup power input. In the scenario of mains power interruption, the startup response time of the backup pump is as long as 30 seconds, which cannot meet the safety specification requirement for the power plant to start water drainage within 5 seconds even under extreme rainstorm conditions with mains power interruption. This poses a significant safety hazard of waterlogging.
🛠️ Customized selection scheme for H series right-angle gearbox
In response to the extreme rainstorm impacts and dusty, humid conditions specific to the power plant's rainwater system, we have selected the highly reliable and upgraded H series right-angle gearbox. Its core configuration fully meets the stringent safety requirements of the power plant environment:
Core parameter precision matching:
It is equipped with dual power inputs of motor and diesel engine, with a rated input power of 850HP (approximately 634kW), 30% power redundancy reserved, and a rated input speed of 1500rpm. Through a customized transmission ratio of 1.4:1, the pump output speed is achieved at 2100rpm, fully matching the operating point of the rainwater pump with a rated flow rate of 1800m³/h and a lift of 35m.
The upgraded heavy-duty thrust roller bearing has a rated axial thrust capacity of 125,000N, fully covering the maximum instantaneous axial thrust of 98,000N under the impact of rainstorm and slag-containing conditions. With a 27% thrust redundancy reserved, it thoroughly solves the bearing overload problem caused by alternating axial impact loads.
Special optimization of power plant operating conditions:
The gears are made of 20CrMnTi alloy steel, which undergoes carburizing and quenching treatment. The tooth surface hardness reaches HRC58~62, and the gear accuracy is upgraded to Level 6. The resistance to abrasive wear is improved by 30% compared to ordinary products, allowing it to withstand minor wear caused by coal dust intrusion. The design lifespan exceeds 10 years.
The shaft end adopts a multi-layer dust and waterproof sealing structure, with the protection level upgraded to IP56, completely blocking the intrusion of coal dust particles and moist water vapor into the gearbox interior. This prevents the ingress of impurities into the lubricating oil, which can cause abrasive wear failure of the tooth surface. It is suitable for the high-humidity and dusty environment of pump rooms.
Layout and emergency adaptation optimization:
The horizontal motor/diesel engine is arranged horizontally in a safe area on the ground of the pump room, and after a 90° turn through the H series right-angle gearbox, it vertically outputs to drive the vertical long-shaft rainwater pump. The total axial height of the unit is reduced from 3.1m to 1.7m, perfectly fitting the narrow vertical space of the underground pump room. No modification to the original steel structure of the pump room is required, significantly reducing the cost of renovation and construction.
Equipped with an independent forced oil injection lubrication system, the oil temperature can be stably controlled below 55℃. Additionally, online monitoring sensors for oil level, oil temperature, and vibration are installed, which are connected to the power plant's DCS control system for real-time monitoring of the operating status, early prediction of potential faults, and unattended automatic operation under extreme conditions.
✅ Actual test results of project implementation
After the renovation project was put into operation, it has been continuously running for 38 months without any major malfunctions, and its various performance indicators far exceed the safety specifications required by the power industry:
Emergency reliability has been significantly improved: the gearbox's heavy-duty thrust bearing fully bears all the alternating axial loads of the pump, with the shaft vibration value stabilized below 2.7mm/s, completely eliminating the burnout failure of the original motor thrust bearing. The continuous trouble-free operation time of the equipment has been extended from 7 months to 38 months, and the reliability of the rainwater system has been improved to 99.95%. It has successfully withstood five extreme rainstorms that occur once in a century, without any waterlogging in the factory area.
Emergency response speed meets standards: The standby combination of diesel engine drive + H series right-angle gearbox ensures that the pump set can reach rated discharge flow within only 3 seconds from receiving a rainstorm warning signal, far below the upper limit of 5 seconds required by the power industry standards. It can still start reliably at 100% in the scenario of complete mains power interruption, completely eliminating the risk of waterlogging during power outages and rainstorms.
Significant enhancement in anti-wear and anti-corrosion performance: The IP56 multi-level dust-proof sealing completely prevents the intrusion of coal dust and moisture. The cleanliness of the lubricating oil inside the gearbox is maintained within NAS8 level for a long time. The gear wear is only 45% of the industry average. The replacement cycle of equipment lubricating oil has been extended from 3 months to 18 months, reducing annual operation and maintenance costs by 70%.
The energy-saving benefits are considerable: through precise matching of the gearbox transmission ratio and eliminating the original throttle adjustment of the outlet valve, the system transmission efficiency has been increased to 97%. A single rainwater pump can save 2.4 million kWh of electricity annually. Calculating at the industrial electricity price of 0.6 yuan/kWh for power plants, the annual direct new revenue exceeds 1.44 million yuan, and the total transformation cost can be recovered in just 11 months.
📌 Summary of core project experience
When selecting the rainwater system for the power plant, it is necessary to choose a customized H series model with high thrust capacity, reserve more than 30% power redundancy, increase the operating condition factor KA to 2.0, and withstand the strong alternating impact load caused by rainstorm and slag-containing medium. It is prohibited to directly use standard models of ordinary clean water pumps.
In the damp and dusty environment of a pump room adjacent to a coal yard, it is essential to upgrade the protection level to IP56 and incorporate multiple dust and waterproof sealing structures to prevent coal dust and moisture from infiltrating the interior and causing abrasive wear on the tooth surfaces. This is the core key to extending the lifespan of the equipment.
This scheme can be directly replicated and promoted to rainwater lifting systems in various power plant areas such as thermal power plants, nuclear power plants, and photovoltaic power stations. It is the mainstream technical route for enhancing intrinsic safety, reducing costs, and increasing efficiency in the electric power industry under extreme rainstorm conditions.
Project Background: A power plant is equipped with a 10LBSA-400 vertical multistage guide vane long-shaft rainwater lift pump, featuring high power and a high lift (400 meters), and is paired with a high-power H series right-angle gearbox.
Technical points:
· Lift: 400 meters (extremely high lift)
· Pump type: vertical multistage guide vane long-shaft pump
· Application: power plant rainwater lifting system
Analysis: A lift of 400 meters means:
· Due to the extremely high axial thrust, it is necessary to use a large-sized gearbox such as H750 (with a thrust capacity of up to 125,000N)
A gearbox with a high reduction ratio (close to 11:10) is required to reduce the high-speed motor to the low speed required by the pump
· The thermal management and lubrication system of the gearbox are crucial under high-power transmission
Project Background: A Tianjin client has customized a wear-resistant and corrosion-resistant vertical long-shaft pump, while an Anhui manufacturer has ordered a high-lift vertical long-shaft pump, both equipped with H series right-angle gearboxes, for use in metallurgical mining and smelting.
Technical points:
· Medium: corrosive media such as slurry, acid and alkali solutions
Requirements: wear resistance, corrosion resistance
· Accessory: H series right-angle gearbox (may require special material treatment)