What is a turbine turning gear?
A jacking gear (also known as a turning gear) is a device placed on the main shaft of an engine or the rotor of a turbine. The jacking gear rotates the shaft or rotor and associated machinery (such as reduction gears and main turbines), to ensure uniform cool-down.
What is the purpose of turning gear in steam turbine?
The turning gear of the steam turbine is an important rotating equipment to ensure that the steam turbine rotor is evenly heated and cooled when the steam turbine unit starts and stops.
Why gas turbine should come on turning gear following a shutdown?
The purpose of turning gear operation while shutting down the turbine is to prevent rotor hogging.
What is used to drive a turbine?
In a turbine generator, a moving fluid—water, steam, combustion gases, or air—pushes a series of blades mounted on a rotor shaft. The force of the fluid on the blades spins/rotates the rotor shaft of a generator. The generator, in turn, converts the mechanical (kinetic) energy of the rotor to electrical energy.
How does a turning gear work?
The turning gear assembly typically consists of an electric motor connected to a set of reduction gears that mesh with a corresponding bull gear attached to the turbine rotor. The electric motor torque is converted to slow-speed rotation of the turbine rotor through a series of gear reductions.
How long should be a turning gear be operated?
In a single S109FB turbine shaft configuration, the time that the unit must remain in turning gear, at a minimum should be four hours, before the start if the shaft is stopped.
What is turning gear operation?
marine. A reversible electric motor which, through a system of gears, can be used to turn slowly a large diesel engine or steam turbine and gearbox assembly. It enables precise positioning for overhaul or examination. The engaging and disengaging of the turning gear is accomplished by the lever.
Why we need to turning gear the engine before starting?
The turning gear is also used to turn the engine one or two revolutions prior to starting. This is a safety check to ensure that the engine is free to turn and that no water has collected in the cylinders.
How does steam spin a turbine?
In simple terms, a steam turbine works by using a heat source (gas, coal, nuclear, solar) to heat water to extremely high temperatures until it is converted into steam. The potential energy of the steam is thus turned into kinetic energy in the rotating turbine’s blades.
What is the function of barring gear?
The barring gear assembly also initiates rotation of the shaft during a startup phase prior to injection of steam in the steam turbine. The rotation speed of the shaft during turning phases is low and constant.
What is turbine hogging?
In the time it takes for a turbine to come to a complete stop following shutdown, the casing and rotor hardly cool down at all. This results in a greater contraction of the bottom of the rotor than the top. The differential contraction results in an upward bowing of the rotor called shaft hog.
How does barring gear work on a turbine?
Barring Gear. Barring gear (or “turning gear”) is the mechanism provided to rotate the turbine generator shaft at a very low speed after unit stoppages. Once the unit is “tripped” (i.e., the steam inlet valve is closed), the turbine coasts down towards standstill.
How does the turning gear work on a steam turbine?
During the shutdown, turning gear will engage at the speed around 40-60 RPM and starts to rotate the shaft until it is cool down completely. As mentioned earlier these speeds are not fixed and they will vary based on manufacturer design. Turning gears are usually installed on heavy rotors.
How many gears are in a gas turbine?
The Turn- ing Gear drive designs incorporate key features utilized in KEI’s proven Gas and Steam Turbine Turning Gears. Over 1000 Turn- ing Gears for gas and steam turbines, compressors and industrial fan applications are in the field, with outputs from 500 ft-lbs to 150,000 ft-lbs, at speeds from fractional to 200 RPM.
What kind of motor does a steam turbine use?
Turning gears can be motor driven or actuated hydraulically. There are other drivers for turning gear such as steam turbines as well but personally I haven’t seen them so far. For turning gears with high speeds, manufacturers usually use electrical motor while for low speeds, manufacturers use hydraulic power.