What is differential expansion?

Differential Expansion on a turbine is the relative measurement of the rotor’s axial thermal growth with respect to the case. Rotor Expansion on a turbine is the absolute measurement of the rotor’s axial thermal growth with respect to the turbine’s foundation.

What is absolute expansion in steam turbine?

The Absolute expansion is the lenghtening due to a normal warming-up procedure, the difference in turbine length when hot compared to that when cold. This is taken and allowed by the turbine mounting. One end is fixed to the basement and the other is sliding some way or other.

What is turbine expansion?

A turboexpander, also referred to as a turbo-expander or an expansion turbine, is a centrifugal or axial-flow turbine, through which a high-pressure gas is expanded to produce work that is often used to drive a compressor or generator.

How does steam expand in 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. As that steam flows past a turbine’s spinning blades, the steam expands and cools.

When do you use the term differential expansion?

Differential expansion is – as the term implies – the net change in relative dimension of the turbine rotor, and the turbine casing. In the vast majority of cases, when the relative dimensions of the rotor and casing in a cold,…

What is the least axial clearance for differential expansion?

1- the differential expansion is combined of both expansion casing and rotor. 2- the least axial clearance is 2.5 mm in HP turbine and 12.5 in LP turbine. 4- We checked The instrumentation is Ok.

When does the turbine differential expansion not change?

Normally for a working turbine, turbine differential expansion should not change during turbine normal running.

What does differential mean in a steam turbine?

Differential means an amount of difference between things that are compared.Here in our case comparable quantities are Shaft expansion and casing expansion. It can be positive or negative depending on the Parameters of steam and Turbine materials.