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Anonymous Poster

Steam Turbines and Speed Fluctuation

08/09/2009 2:04 AM

hello everybody, can anyone help me with the question below:

what are the causes that makes a steam turbine that drives a single stage compressor have a fluctuating speed (after a startup)?

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Guru

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#1

Re: steam turbine fluctuating speed

08/09/2009 3:07 AM

Governor problems.

Accumulator problems.

Extraction problems.

Surge control problems.

Compressor surge.

Bad speed pickup

Fluctuating compressor load

Fluctuating back pressure on the exhaust header

Unloaded compressor

It would help to know what kind of compressor and what kind of turbine (back pressure, extraction, or condensing) in what kind of service (recycle? refrig?).

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Guru

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#2

Re: steam turbine fluctuating speed

08/09/2009 4:04 AM

The fluctuating speed means is it hunting? or it settles down after the spikes?

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Anonymous Poster
#3

Re: steam turbine fluctuating speed

08/09/2009 4:47 AM

centrifugal steam turbine that uses 400psig saturated steam to drive a centrifugal single stage hi speed compressor. the compressor deliver combustion air. The problem is observed even when the turbine is uncoupled.

the fluctating dosn't settel. the flucating is btween 3450rpm and 3650rpm.

is the presence of condensate is a reason?how can we be sure about it?

is defects in steam traps (in the outlet of condensate lines ) is a rason in this problem?

i noticed som steam is leaking throgh the flange of the cover of the rotor(near the outbord carbon rings)

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#4
In reply to #3

Re: steam turbine fluctuating speed

08/10/2009 3:34 AM

Why is this level of speed fluctuation a significant problem?

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Member

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#5
In reply to #4

Re: steam turbine fluctuating speed

08/10/2009 4:11 AM

because it cause the turbine to trip on overspeed.

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Guru

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#6

Re: Steam Turbines and Speed Fluctuation

08/10/2009 5:00 AM

I doubt it is condensate, but it might be. Is this turbine way out on the end of the 400 lb header?

I would start with the governor, and the accumulator in the governor hydraulic system. It is probably a hysteresis issue.

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