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chinnu
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Join Date: Aug 2015
Posts: 2

Differential Expansion is More in Steam Turbine

08/14/2015 6:56 AM

One month back turbine(30 MW, QJPS make) casing drain gasket got damage and near to the drain flange all insulation blew off. Then bottom and top casing temperature difference increased and also differential expansion increased. On load also it did not came down and it remains around +2.3 to 2.4.

Again few days back, we stopped the plant to attend boiler problem. Before starting rolling the casing expansion was 5.2, previously it was 9.1 while on load(14 MW).On load tg got trip with differential expansion high(5.0). Again we started rolling later with low steam temperature, it went up to maximum +3.72. Now it is +3.18 with load of 14 mw.

Pl, suggest what to do to decrease this differential expansion
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SHOCKHISCAN
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Join Date: Nov 2007
Location: Eastern Arizona mountains on Route 666 about a mile from God's country
Posts: 1676
Good Answers: 122
#1

Re: Differential Expansion is more in steam turbine

08/14/2015 9:27 AM

Too much steam pressure for the established turbine speed.

Look for:

Restricted steam flow path in/through the turbine and/or extraction system piping. (Partial open valve with false position indication? broken or damaged diaphragms, vanes, fins?)

Turbine control loop out of tune/calibration.

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RAMConsult
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Engineering Fields - Power Engineering - New Member

Join Date: May 2007
Location: NYC metropolitan area.
Posts: 3230
Good Answers: 444
#2

Re: Differential Expansion is More in Steam Turbine

08/14/2015 1:09 PM

It's amazing that your turbine still spins. More than likely your bearings/casing/shaft became misaligned by not following the proper cool-down procedures after your blown gasket incident.

Your best and only source of assistance is to contact the manufacturer directly:

http://jnpower.com/enjnpower/Corporation/infoDetail.asp?cInfoId=176&dInfoId=141

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SHOCKHISCAN
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Join Date: Nov 2007
Location: Eastern Arizona mountains on Route 666 about a mile from God's country
Posts: 1676
Good Answers: 122
#3

Re: Differential Expansion is More in Steam Turbine

08/14/2015 5:08 PM

An afterthought: Have you checked the thrust detector yet? If not I suggest you do so soon as there may have been significant damage from a rub to the turbine from the first trip.

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SureshVashisth
Participant

Join Date: Aug 2015
Posts: 1
#4

Re: Differential Expansion is More in Steam Turbine

08/15/2015 3:08 PM

Please check your thrust and front bearings.
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
Good Answers: 839
#5

Re: Differential Expansion is More in Steam Turbine

08/17/2015 4:17 PM

This matter is best handled by the turbine manufacturer, whose telephone number will be found in the operation and maintenance manual that came with it.

Please explain why waiting for a bunch of random strangers on the internet to make wile-ar$ed-guesses about this matter seems a better bet to the employer than getting the manufacturer's area representative to call in to the installation immediately?

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Previous in Forum: Efficiency Evaluation and Improvement of Deep Well Submercible Pumps   Next in Forum: VRF Y-Joint Distance

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