Drives for power generation: TPP, hydropower, nuclear and district heating
Power generation is the baseline load of the national economy and one of the most demanding industries in terms of drivetrain uptime. A TPP induced-draught fan is not allowed to stop without a command, a boiler feed pump on an 800 MW unit must start within a few seconds on emergency automation, and a hydropower stoplog hoist must operate after twenty years of standstill. Generic general-purpose solutions do not apply here — the application calls for specialized lines of gearboxes, medium-voltage motors, brakes and couplings with multi-fold service-life margins, plus carefully matched motor-gearbox-coupling-brake trains.
Industry-typical tasks
- Drives for coal pulverizers (MPS, HP-bowl) of pulverized-coal boilers — low-speed planetary-bevel gearboxes 200 kW – 1,000 kW
- Induced-draught and forced-draught fans for boilers — MV motors 800 kW – 6,000 kW at 6/10 kV with inlet vane or VFD control
- Boiler feed and condensate pumps (BFP, CWP) of TPP units — synchronous and asynchronous motors 2,000 kW – 10,000 kW
- Coal handling conveyors of coal-fired TPPs, bucket elevators, wagon tipplers — geared motors 75 kW – 1,000 kW with backstop overrunning clutch
- Bottom-ash and ash hydrohandling systems — slurry pumps and scraper conveyors for highly abrasive slurry
- Hoists for hydropower stoplogs, bulkhead gates and radial gates — geared winches with dual brakes and backup lowering system
- Hydraulic power units for hydropower turbine wicket-gate control, HPUs for radial-gate servomotors
- Circulating and district heating network pumps — vertical and horizontal motors 200 kW – 2,000 kW
Gearboxes
Power generation relies on four classes of gearboxes: specialized planetary-bevel units for coal pulverizers, industrial bevel-helical units for coal handling and ash conveyors, low-speed high-ratio units for stoplog hoists, and general-purpose geared motors for auxiliary mechanisms. The principal requirement for a TPP gearbox is continuous S1 duty 24/7 with a 25-year service life to major overhaul; pulverizers additionally demand vibration and dust tolerance, conveyors require backstop provisions, and hydropower hoists call for absolute reliability of operation after years of standstill.
Gearboxes for MPS and HP-bowl coal pulverizers
Low-speed planetary-bevel gearboxes are the main drive of a medium-speed roller pulverizer in a pulverized-coal boiler. The reduction ratio is 30–50, output speed 18–30 rpm, torque up to 600 kN·m. The housing sits at the base of the pulverizer and simultaneously supports the grinding bowl — its thrust bearing carries the vertical load from the mill weight and the roller pressure. The CGC FM series covers the 200–1,000 kW power range.
- — Reduction ratio 30–50, output speed 18–30 rpm
- — Thrust bearing rated for vertical load up to 250 tf
- — Forced circulating lubrication with DEO oil cooler
- — Service factor at least 1.8; service life to overhaul 100,000 h
Geared winches for hydropower gate hoists
Multi-stage helical gearboxes for hoists of flat and radial gates in hydraulic structures. The distinctive feature is infrequent operation (a few times a year for routine drills) combined with mandatory actuation on a release command. The typical layout uses two independent motors with two brakes, or a single motor plus a backup hydraulic drive that lowers the gate by gravity. BONENG H/HB or CGC ZSY industrial gearboxes with an increased service factor are used.
- — Service factor at least 2.0 (allowing for shock start under load)
- — Ability to operate with two motors driving a common output
- — Anti-corrosion design (hydropower powerhouse environment)
- — Long idle intervals between starts without loss of lubrication
Geared motors for coal handling conveyors
General-purpose bevel-helical (K-series) and parallel-shaft (F-series) BONENG geared motors for belt, scraper and apron conveyors of a coal-fired TPP coal handling system. Long coal handling lines from the wagon tippler to the boiler bunkers operate with frequent starts under full load — closer to S4 than S1. Inclined sections mandate a TIANIU backstop to prevent uncontrolled reverse run of the loaded belt on shutdown.
- — K-series (90°) or F-series (parallel output)
- — Service factor at least 1.5; thermal margin for S4 duty
- — Mounting provision for a TIANIU backstop on the intermediate shaft
- — Reinforced seals against coal dust (dual lip seals, labyrinth)
Drives for bucket elevators and wagon tipplers
A bucket elevator feeding coal to a boiler bunker or carrying ash is a mechanism with a critical backstop on the drive shaft. On power loss the loaded buckets must not tip back — this would tear the chain and cause an accident. The drives use BONENG H/B-series geared motors with an integral backstop or an external TIANIU backstop. For rotary wagon tipplers — gearboxes with reversing-load compensation and a holding brake in the discharge position.
- — Mandatory backstop (TIANIU NJ/NF/GV) on the input or intermediate shaft
- — Thermal margin for S4 duty (wagon tippler — up to 30 cycles per hour)
- — Service factor 1.5–2.0 for drives with shock loads
- — Overload protection via a shear pin or an electronic torque relay
Gearboxes for bottom-ash scraper conveyors
Wet bottom-ash scraper conveyors operate in boiling water with ash slurry. The gearbox housing is protected by a corrosion-resistant coating; the output shaft is fitted with dual seals fed by sealing water. BONENG B/H-series helical gearboxes or specialized CGC heavy-duty units are used for continuous 24/7 operation in an aggressive environment.
- — Seal protection against ingress of ash slurry
- — Anti-corrosion epoxy coating of the housing
- — Forced circulating lubrication with filtration
- — Compatibility with an IP55 moisture-protected motor
High-power electric motors
The principal consumers of MV motors at a TPP are induced-draught fans, forced-draught fans, feed pumps and circulating pumps. These are 6/10 kV asynchronous motors rated 800 kW to 10,000 kW running S1 24/7. The current trend is to replace inlet-vane control with VFD control via an MV drive, which yields 20–35% energy savings and reduces fan wear. Hydropower stations use vertical generators and auxiliary asynchronous machines for plant services; nuclear plants use asynchronous motors for auxiliary systems outside the nuclear safety classification.
Motors for induced-draught and forced-draught fans
Continuous S1 duty, 800 kW – 6,000 kW, 6/10 kV, 590, 740, 990 or 1,490 rpm. Flow control via inlet vanes on the suction side or via a variable-frequency drive; the VFD option is preferred for new installations and retrofits. The motor operates with vibration transmitted from the fan, so it requires a rigid foundation, real-time vibration monitoring and Pt100 sensors on the windings and bearings. WOLONG YKK/YRKK series fit, with high efficiency at rated load and thermal margin for hot restarts.
- — Insulation class F with class B thermal reserve
- — Vibration monitoring per ISO 10816-3 (zone B)
- — Ability to start via a soft starter or an MV inverter
- — IP55 with additional protection against fly ash in ambient air
Motors for boiler feed and condensate pumps
The boiler feed pump on a TPP unit is one of the most critical machines: a trip triggers boiler protection and a unit load rejection. The motors are synchronous, 4,000 kW – 10,000 kW at 6 or 10 kV, or asynchronous with an MV inverter when fluid-coupling or frequency control is used. The WOLONG WD3000 series is purpose-built for pump applications, with forced water cooling and a starting torque of 1.8 times rated.
- — Rating 2,000 kW – 10,000 kW, 6 or 10 kV
- — Insulated bearing on the coupling end (shaft-current protection)
- — Forced IC81W cooling (water-to-air)
- — Thermal margin for a hot restart within 60–120 s
Motors for circulating and district heating network pumps
Condenser circulating pumps and district heating network pumps operate in S1 duty with few starts. Ratings 200 kW – 2,000 kW, 0.4–10 kV. Both horizontal and vertical designs are used; the vertical motor is mounted above the pump with a thrust bearing capable of carrying the vertical hydraulic load. WOLONG YE/YBX3 general-purpose series fit, as do HUALI Y2/Y3 for LV applications.
- — IP55, insulation class F
- — Vertical design with an axial thrust bearing (for vertical pumps)
- — Compatibility with soft starters
- — Efficiency at least IE2/IE3 to meet energy-efficiency regulations
Motors for nuclear and TPP auxiliary systems
Plant-wide drives — service-water pumps, oil systems, compressors, powerhouse ventilation, fire-water pumps. At a nuclear plant they serve equipment outside the nuclear safety classification (balance-of-plant systems not part of safety loops). The requirements are reliability, long mean time between failures and ease of maintenance. WOLONG YE/YBX3 and HUALI Y2/Y3 cover the full size range.
- — IP55, insulation class F
- — Long MTBF (at least 50,000 h)
- — Ease of bearing and winding replacement in field maintenance
- — Compatibility with the plant protection and DCS systems
Industrial brakes
Braking systems in power generation address three tasks: holding suspended loads (powerhouse cranes, hydropower hoists), preventing uncontrolled reverse run (inclined coal handling conveyors, bucket elevators) and protection against wind loads (open-yard coal storage cranes). Each task calls for its own class of equipment: electrohydraulic disc brakes, backstop overrunning clutches and anti-storm rail clamps. Critical applications — hydropower gates, casting cranes — use a dual independent service-and-emergency brake system.
Brakes for powerhouse overhead cranes
Powerhouse cranes at TPPs, hydropower stations and nuclear plants service turbosets and generators up to 500 tonnes. HUAWU YPZ2/YWZ5 electrohydraulic disc brakes are fitted on the hoisting drum with a two-fold braking-torque margin. For turbine teardown, where critical assemblies are lifted, a dual brake layout is used: a main (service) brake plus a backup (emergency spring-applied) brake.
- — Braking torque margin of 1.75–2.0 over the rated hoisting torque
- — Actuation time on power loss no more than 0.2 s
- — IP55 protection, operating temperature –20 °C…+50 °C
- — Dual brake set (service + emergency) for critical lifts
Brakes for hydropower gate and stoplog hoists
A hydropower gate hoist is a rarely-actuated mechanism (a few times a year), yet it must operate on a release command during a flood or emergency. A dual HUAWU brake layout is used — a service brake holds the gate at intermediate positions and a spring-applied emergency brake holds it on power loss. The design rules out a full gate release without a control command (protection against runaway water discharge).
- — Dual independent service and emergency brake system
- — Application on power loss within 0.1–0.2 s
- — Anti-corrosion design (hydropower powerhouse environment, high humidity)
- — Manual release option for routine maintenance
Backstop overrunning clutches for conveyors and elevators
A TIANIU backstop is a critical element of an inclined coal handling conveyor or a bucket elevator drive. When the motor is de-energized the backstop instantly blocks reverse rotation, preventing an avalanche-style coal runback or the belt slipping off the pulley under the weight of the load. The TIANIU NJ (sprag-roller), NF (face-locking) and GV (high-speed) series cover the size range from small conveyors to main lines.
- — Rated holding torque at least equal to the load torque on the stopped conveyor
- — Mounting on the gearbox input shaft (for NJ/GV series)
- — Long service life — millions of start-stop cycles maintenance-free
- — Compatibility with the flanged output of a BONENG/CGC gearbox
Anti-storm brakes for coal yard cranes
Open coal yards and port terminals for fuel handling are equipped with overhead and gantry cranes featuring JINGU CWZ or ZHONGHAI SB anti-storm rail clamps. The brake holds the crane on the rails in gusts up to 35 m/s during idle hours. It activates automatically on an anemometer signal and on power loss, and is released only on a regular operating command.
- — Holding capacity in winds up to 35 m/s
- — Automatic actuation on an anemometer signal
- — Backup from a dedicated power source (UPS)
- — Compliance certificate and pneumatic release
Couplings and hydraulic components
Four coupling types are used in power-generation drives: fluid couplings on coal pulverizers and coal crushers (soft start, motor overload protection), drum-type gear couplings on feed pumps and large fans (high torque plus misalignment compensation), elastic pin couplings on conveyors and pumps (damping), and KINGDA slurry pumps for ash hydrohandling as a flagship SDS offering. A separate class consists of hydraulic power units for hydropower turbine wicket-gate control and radial-gate operation: they generate the control pressure in the servomotor cylinders.
Fluid couplings for coal pulverizers and coal crushers
Oil-filled JIAOHUA YOX/COX fluid couplings are the standard solution for starting a coal pulverizer or a coal crusher under full load. Rated slip of 2–3% protects the motor against overload if the rotor jams. Variants with a fusible plug discharge the oil overboard on overheating and automatically trip the drive, which is critical for dusty applications (coal dust ignites on contact with hot oil).
- — Rated slip 2–4%
- — Fusible plug set at 145–160 °C
- — Oil fill 70–85% of the internal volume
- — Thermal margin for 4–6 starts per hour
Gear couplings for feed pumps and large fans
Drum-type double-engagement YONGJING GIICL and LONGXUAN WGZ gear couplings are the standard connection between an MV motor and a large pump or fan. They transmit torque up to 200 kN·m with compensation for radial, axial and angular misalignment after thermal growth of the housings. The crowned tooth profile permits operation at angular misalignment up to 1.5°. Grease lubrication via a fitting, with a 6-month service interval.
- — Torque 5 kN·m – 200 kN·m
- — Angular misalignment compensation up to 1.5°
- — G6.3 balancing for peripheral speeds above 15 m/s
- — Compatibility with the flanges of the motor and pump/fan
KINGDA slurry pumps for ash hydrohandling
KINGDA AH (horizontal) and SP (vertical) slurry pumps are an SDS flagship competence for TPP ash hydrohandling. They pump highly abrasive ash slurry with up to 50% solids by mass. The casing and impeller are made of wear-resistant Cr27 high-chrome iron or feature elastomer lining. Capacity 50 to 5,000 m³/h, head 20–80 m, wear-part service life 8,000–12,000 h depending on the ash composition.
- — Wear-resistant flow path (Cr27 or rubber lining)
- — Capacity 50–5,000 m³/h, head 20–80 m
- — Compatibility with WOLONG/HUALI motors 75 kW – 1,500 kW
- — Service kit of quick-change parts (impeller, casing armor)
HPUs for turbine wicket gates and radial gates
DONLY hydraulic power units generate a control pressure of 6.3–25 MPa in the cylinders of hydropower turbine wicket-gate servomotors, in radial-gate hoists and in induced-draught fan vane-control systems with hydraulic actuators. They are equipped with HUADE/INI gear or axial-piston pumps, accumulators and proportional-valve control blocks. Redundancy is provided by two pump units in a duty-plus-standby arrangement with automatic changeover.
- — Operating pressure 6.3–25 MPa depending on the application
- — Redundant pump group (duty + standby)
- — Accumulators for emergency operation on power loss
- — Compatibility with proportional valves and the plant DCS
Applications gallery
Our solutions for this industry
SDS portfolio brands that cover typical applications in this industry.
- WOLONGMV motors for induced-draught and forced-draught fans, feed pumps and circulating pumps — YKK/YRKK/WD3000 series rated 800 kW – 10,000 kW; general-purpose YE/YBX3 for auxiliary systems
- CGCheavy-duty gearboxes for coal pulverizers (FM series) and large fans; industrial ZSY units for hydropower hoists
- BONENGK/F/HB geared motors for coal handling conveyors, bucket elevators, ash scraper conveyors and hydropower gate drives
- TIANIUNJ/NF/GV backstop overrunning clutches — a critical element of inclined coal handling conveyors and bucket elevators; protection against runaway reverse motion
- HUAWUYPZ2/YWZ5 electrohydraulic disc brakes for powerhouse cranes and hydropower gate hoists; dual brake systems for critical lifts
- JINGUCWZ anti-storm rail clamps for gantry cranes at open coal yards and port fuel-handling terminals
- JIAOHUAYOX/COX fluid couplings for coal pulverizers and coal crushers — soft start under full load and motor overload protection
- YONGJINGGIICL drum-type gear couplings for connecting MV motors to feed pumps, induced-draught fans and large fans
- LONGXUANWGZ gear couplings and LX elastic pin couplings with brake drums for conveyor drives and auxiliary mechanisms
- DONLYHPUs for hydropower turbine wicket-gate control, HPUs for radial gates and stoplog hoists
- DEODFL/DFLA oil coolers for coal pulverizer gearboxes and large industrial drives; plate heat exchangers for lubrication systems
- KINGDAAH/SP slurry pumps for TPP ash hydrohandling — an SDS flagship competence, wear-resistant Cr27 design for abrasive ash slurry
- HUADEgear and axial-piston pumps for turbine wicket-gate HPUs and hydropower gate hoists
- HUALIgeneral-purpose Y2/Y3 motors for auxiliary pumps, ventilation, compressors and fire-protection systems
Image credits: Mussi Katz (CC0) · United States Atomic Energy Commission (Public domain) · The Iron Age (1925) (Public domain) · Dirk Pons (CC BY 4.0)