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The WOODWARD 9904-812 is a mechanical-hydraulic speed droop governor specifically designed for steam turbines. It is a part of the TG-17L (Lever) series and is configured for high-speed applications, typically up to 6000 rpm. This model features clockwise (CW) drive shaft rotation and its speed setting is adjusted via a lever mechanism. Crucially, it is also ATEX certified, making it suitable for hazardous environments.
WOODWARD 9904-812: Mechanical-Hydraulic Speed Droop Governor (TG-17L, 6000 rpm, CW Rotation)
The WOODWARD 9904-812 is a robust, self-contained control device vital for the stable and reliable operation of small to medium-sized steam turbines. It is particularly well-suited for applications where consistent speed control with a predictable droop characteristic is required, as opposed to strict isochronous (constant) speed. Its “Lever” designation refers to the mechanical interface for speed adjustment.
Product Overview
The 9904-812 operates as a mechanical-hydraulic governor. It continuously senses the turbine’s rotational speed and compares it to an internal setpoint. Based on this comparison, it precisely adjusts the turbine’s governor valve to regulate the steam inlet flow, thereby controlling the turbine’s speed.
- Product Type: Mechanical-Hydraulic Speed Droop Governor
- Manufacturer: Woodward
- Series: TG-17L (Lever-operated)
- Application: Small to medium steam turbines (e.g., driving pumps, compressors, generators).
- Key Feature: Speed droop control (not isochronous).
- Rated Speed: Designed for operation up to 6000 rpm.
- Speed Setting Mechanism: Lever-operated (manual adjustment).
- Drive Shaft Rotation: Clockwise (CW) rotation.
- Output: 23.7 N·m (17.5 ft-lb) rotary output. (The TG-17 series provides higher work output than the TG-13 series).
- Environmental Certification: ATEX certified (suitable for potentially explosive atmospheres).
- Rated Speed @ 2° Droop: 6000 rpm (a specific configuration point for droop, indicating the speed reduction for a given load increase).
Detailed Product Description
The WOODWARD 9904-812 provides a reliable and cost-effective solution for steam turbine speed control. It is a key member of the durable and widely recognized TG-17 governor family, which offers higher work output compared to the TG-13 series.
Here’s a breakdown of its functionality and features:
- Mechanical-Hydraulic Operation: This governor is a fully self-contained unit. It uses a drive shaft-driven ball head assembly to accurately sense the turbine’s speed. An internal, shaft-driven oil pump generates the necessary hydraulic pressure (1379 kPa / 200 psi for TG-17 governors, higher than TG-13’s 1034 kPa / 150 psi) to power the internal servomotor. This servomotor precisely controls the turbine’s steam admission valve. This robust mechanical-hydraulic design minimizes reliance on external electronic components for its core function.
- Speed Droop Control: The 9904-812 operates on the speed droop principle. This means that as the load on the turbine increases, its speed will slightly decrease proportionally. This characteristic is often desirable in applications that involve load sharing among multiple prime movers or where a slight, predictable speed variation due to load changes is acceptable for overall system stability.
- Direct Turbine Interface: The governor is designed for direct coupling to the steam turbine’s rotor or an auxiliary shaft to receive speed input. Its rotary output shaft then directly connects to the turbine’s steam admission valve, enabling precise regulation of steam flow.
- High-Speed Capability (6000 rpm): This specific model is optimally configured for turbines operating at higher rotational speeds, up to 6000 rpm. This speed capability is vital for ensuring proper integration and performance with faster-spinning prime movers.
- Lever-Operated Speed Setting: The “L” in TG-17L indicates that the speed setpoint is adjusted via a lever mechanism. This method provides a straightforward and direct way for operators to change the desired turbine speed, often preferred for manual, on-the-fly adjustments during operation or startup.
- Clockwise (CW) Rotation: The 9904-812 specifically features a clockwise drive shaft rotation and a corresponding clockwise output shaft rotation. This is a critical mechanical specification that ensures correct integration with the turbine’s drive train.
- Higher Work Output: As a TG-17 series governor, it offers a higher work output of 23.7 N·m (17.5 ft-lb). This increased capacity allows it to control larger or more demanding turbine valves compared to the TG-13 series governors.
- Rugged Construction and ATEX Certified: Built for challenging industrial environments, these governors feature a rugged construction and a self-contained oil sump. The ATEX certification confirms its suitability for use in potentially explosive atmospheres, commonly found in many industrial plants like oil & gas facilities or chemical processing plants.
In summary, the 9904-812 is a reliable, robust, and ATEX-certified mechanical-hydraulic governor, ideally suited for high-speed steam turbine applications (up to 6000 rpm) that require lever-based speed adjustment and a clockwise drive shaft rotation.
Technical Specifications (General)
Typical Applications
The WOODWARD 9904-812 is commonly found in industrial settings utilizing small to medium steam turbines for mechanical drive or power generation, especially in situations where:
- High Speeds are Present: Turbines operating at or around 6000 rpm.
- Higher Work Output is Needed: To operate larger or stiffer turbine control valves effectively.
- Speed Droop Control is Adequate: For applications where stable load sharing or predictable speed variation with load changes is acceptable and contributes to system stability.
- Mechanical-Hydraulic Simplicity is Preferred: When a robust, self-contained mechanical governor is favored over more complex electronic systems, particularly in hazardous or demanding environments.
- Lever-Based Speed Adjustment: Where operators need to manually adjust the speed setpoint via a lever, for example, during startup or load changes.
- Clockwise Rotation: The turbine’s mechanical drive interface specifically requires a CW rotating governor for proper integration.
Common use cases include controlling steam turbines that drive:
- Various process pumps.
- Compressors and turboexpanders in chemical plants, refineries, or gas processing facilities.
- Generators for power generation, often operating in parallel with other power sources.
- Large industrial fans in power plants or other heavy industries.
