Previous in Forum: Price construction of windturbines   Next in Forum: Is it true that marine lubes is not needed in Marine vessel anymore?
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
5 comments
Rate Comments: Nested
R Surti
Active Contributor

Join Date: Sep 2008
Location: Dubai, UAE
Posts: 11

All Electric Turbine

09/14/2008 1:43 AM

Normally GE Gas Turbines have Electro Hydraulic Actuauted (EHA) control system (Gas control valve, stop ratio valve, fuel bypass valve, fuel stop valve) which has its own problems related to oil contamination. I have heard that now-a-days EHA is replaced by Electro-Mechanical Actuated (EMA) control valves (GCV, SRV) to avoid servo valves & hence oil contamination issues. i.e. these control valves are not hydraulically operated, but motor operated. What are advantages & disadvantages of both ? Is it worth changing, technically & commercially ? Can anybody help me to find more info on this ?

__________________
 Take care & best regards. Rakesh
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".
Sparkstation
Guru
New Zealand - Member - Interested in everything- see my Profile please APIX Pilot Plant Design Project - Member - Member Engineering Fields - Electrical Engineering - Member Engineering Fields - Power Engineering - Member Engineering Fields - Civil Engineering - Member Hobbies - Musician - Autoharp and Harmonica Hobbies - Hunting - Member Hobbies - Fishing - Member

Join Date: Nov 2007
Location: Christchurch, (The Garden City), South Island, New Zealand
Posts: 4395
Good Answers: 230
#1

Re: All Electric Turbine

09/15/2008 7:19 AM

Hello R Surti

Why not ask the GE Gas Turbine experts:

They are sure to know the answer to your questions.

Find them right here: http://www.gepower.com/prod_serv/products/gas_turbines_cc/en/index.htm

Advise your progress, with

Kind Regards....

__________________
 "The number of inventions increases faster than the need for them at the time" - SparkY
Register to Reply
2
djacob
Commentator

Join Date: Oct 2007
Location: Caribbean
Posts: 79
Good Answers: 2
#2

Re: All Electric Turbine

09/15/2008 7:46 AM

I have been around GE turbines for 30 yrs.

I am considred an expert ( self diagnosed, mind you) on GE turbine systems .

GE Frame 3, Fame 5, Frame 6, Frame 7 machines with Speedtronic control system from the very old Mark I Speedtronic ( yes , you heard me correctly, Mark I Speedtronics , actually I have lots of Mark I, II Speedtronic cards to give away !!!) to the state of the art offering Mark VI.

Just returned from the GE Salem Training center .

The hydraulic controls are stable and trouble free if you keep your oil clean and avoid carbonising and other contaminants , water ingress into the lube oil tank etc( as in the case of the Frame 7 combustion with the internal third bearing) .

I have two groups of Frame 5s , installed around 1980, with the same controls on two different plant in our fleet.

In the 30 yrs, I have had two Moog servo valve failures at Plant PTLS and near 30 at Plant PNL!!!!

I have also replaced hydraulic control valves on another manufacturers machines and installed an all electric valve which worked with mathematical accuracy but is overly active ( in my opinion).

I have had to replace the electric servo valve and reinstall a hydraulic one since we change the machines loading frequenly and the machine operates ion droop so that also induces a significant amountof control corrections.base load operation is much quieter thaan part lload droop.

I guess from my experience , I am not sure one is any more reliable than the other.

Cost-wise the electric solution is cheaper.

__________________
 Learn more, Do more , Be more
Register to Reply Good Answer (Score 2)
No more Good Answers.
R Surti
Active Contributor

Join Date: Sep 2008
Location: Dubai, UAE
Posts: 11
#3
In reply to #2

Re: All Electric Turbine

09/16/2008 1:21 AM

Dear Mr Jacob,

Thanks for the detailed reply. I could get some understading. Can you please tell what is overly active ?

__________________
 Take care & best regards. Rakesh
Register to Reply
djacob
Commentator

Join Date: Oct 2007
Location: Caribbean
Posts: 79
Good Answers: 2
#4
In reply to #3

Re: All Electric Turbine

09/16/2008 8:00 AM

All our GE turbines drive electric generators in the order of 20MW for the Frame 5 to 65 MW as in the case of the Frame 7s.

Our power grid is relatively small, in the order of 1500 MW with steel and petrochemical plants.

In a situation like this , the large loads can influence the grid frequency ( just as they would if your had a couple of diesel generators in parallel on an off-shore platform) so our machine must be operated on droop control. we can also operate on fixed loading but then the machine would not be lending to the collective grid frequency correction effort.

To automatically correct the grid frequency , you operate the machine on droop ( speed control) in an attempt to maintain grid frequency , in our case 60Hz.

If the gains on the droop (speed) control loop is set high, as they should be to get effective control, you will have the control system and the final element ( the control valve, be it hydraulic or electric ) continuously making small corrections.

In the case of the hydraulic valve , well the operator do not take notice of that except to replace some seals and possibly filters in the servo .

In the case of the electric valve , this continuous duty may be excessive for the electric valve and may result in motor failure. .

Every time the valve moves the motor operates.Most valves are DDV ( direct drive valve) type with a permanent magnet motor.

In power grids in large contries where the grid freqiency do not change very quickly , the DDV valve will work fine.

In our applications which do not require very fine continuous control , the electric valve have worked fine for a very long time, as in the case of inlet guide valve positioning on the GE Frame 5 and 7 turbines.

hope this helps

Hope this helps.

__________________
 Learn more, Do more , Be more
Register to Reply
Anonymous Poster
#5
In reply to #4

Re: All Electric Turbine

09/18/2008 12:14 AM

Dear Mr Jacob,

Thank you very much. Appreciate your extensive knowledge on the subject & you deserve a title of GE turbine expert.

Will keep in touch with you to gain from your experience through this thread or if you can send me your e-mail ID. My e-mail ID is rakesh@gblenergy.com
Register to Reply
Register to Reply
Have a Different Question?
5 comments

Good Answers:

These comments received enough positive votes to make them "good answers".
Copy to Clipboard

Users who posted comments:

Anonymous Poster (1); djacob (2); R Surti (1); Sparkstation (1)

Previous in Forum: Price construction of windturbines   Next in Forum: Is it true that marine lubes is not needed in Marine vessel anymore?
You might be interested in: Control Valves, Gas Valves, Industrial Valves

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
New Technologies & Research:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (82 right now)
Show Members
Advertisement