Expansion in Multistage Steam Turbines

Hi Sparky,

You answer as usual is "spot on". I continue to be amazed by your graphics. Where do you get the phenomenal animated graphics?

Hello agua_doc

I have an ever-increasing collection.

Read about it in this Topic: How to insert Graphics into your Post to make it more readable or interesting

Once an appropriate has been found, I rename so I can remember it easily, then add as necessary.

Kind Regards....

He stole it from my old merchant marine website!

Can anyone tell me the commissioning steps of a steam Turbine, please?

both the rotor and casing will expand in same direction.

our turbine is china made contain 22 stages in which first one is impulse and the rest are reaction type blade having two cotrolled extarctions .having single thrust bearing at the front side,two journal at the both end.Gear box is attached to the end of the rotor for speed reducing from 5016 t0 1500( generator speed) .i have a doubt that is the rotor and the casing expansion is in same direction or not,because at the time of cold start up we are getting DE - ve direction(DE measurement).at the normal load it is in + ve direction,

Hi, Guest!

If you are referring to the expansion of cooling steam, there is no problem. It's expansion is actually employed to run more down-line steam cylinders/turbines, and HVAC before being condensed.

So you must be referring to the expansion of parts in the system due to heating. This is addressed by size, tolerances and metallurgical considerations in the design.

Steam engines work on differential pressures. The velocity of fresh steam can be used to generate a great pressure differential with a relatively small input when injected into a small cylinder or through the blades of a small turbine. As it begins to cool the steam expands, and can then be utilized in a larger cylinder or turbine with a larger area or circumference so that its "weaker" velocity can be utilized to create an equivalent pressure differential or rotational speed to that of the smaller cylinder or turbine, and so on.

The tolerances in a steam engine's component parts are designed to account for the expansion of metal as it heats, and there are glands and piston rings to prevent steam losses. But as the energy of the steam is harnessed through expression of pressure differential, expansion of the engine's component parts so long as they don't expand/contract to the point of contact interference with each other or allow losses of steam energy through blow-by, makes little difference to the overall operation.

Metallurgical considerations and engine construction revolve mainly around high-speed reinforcement, shape retention in the turbine blades and transmission of torque through the shafting.

Does this address the question?

Mark