Steam Turbine Barring Gear/ Turning Gear

What does it say in the User Manual supplied with the equipment?

At this time, the forum wants to know:

• The maker's name
• The model
• The size
• The location
• The ambient conditions
• The steam conditions
• The speed
• Etc., etc.

Siemens, 25 MW, 7500rpm

• The model
• The location
• The ambient conditions
• The steam conditions
• What does it say in the User Manual
• Etc., etc.

Presumably to identify any mechanical problems before running it under load.

when we talk about barring gear we mean the entire assembly of turbine gear box nd generator is rotating

The barring gear provides just enough turning speed(typically 1%) to keep the shaft of the turbine from warping due to unequal heat...used during startup and shut down....

http://en.wikipedia.org/wiki/Thermal_power_station

Ha, I was assuming he meant barring it before steam was turned on for the first time, at commissioning. OP, can you clarify?

Is it normal to bar turbines (in normal operation) before applying steam?

I imagine it's run anytime there is a danger of unequal heat distribution....The top of the system tends to heat first and retain heat the longest...Depending on the design and configuration this may vary in different systems...

u r right bt where is the heat during starting the turbine from cold condition???

yes at first time as well as after shut down every time when ever we start theturbine from cold condition we start it through barring gear.

my turbine is on commissioning stage.

my turbine rpm is 7500 and barring gear rpm and for any turbine lies between 150 rpm to 300 rpm.

bt where is heating during starting time??? at comissioning stage turbine is under cold condition.

RFTM.

Before starting the Turbine, the rotor is at stationary position, and steam is to be admitted in to the turbine for warming up and once the steam enters the turbine it will give its heat to the rotor, stator blades, turbine casing etc, and steam becomes much wet and uniform heating may not take place. During warming up, minute water particles are formed and stick to the blade and will not allow the temp. to rise, uniformly.

Further if the shaft is at rest the shaft also will gain heat and the contact point at the bearing will be the area where the heat flow takes place, even though oil is circulated. Due to this, the bearing clearances get affected.

In order to achieve uniform warming up and minimise heat conduction to the bearing surface from the shaft, when the rotor is at rest, the rotor is made to revolve around 300 RPM.

DHAYANANDHAN.S