I am a newly hired Foreman with Berry Petroleum out of Taft, CA operating a Frame 6B in combined cycle. I am new to frame turbines so forgive me if my question sounds fairly basic.
We are coming up on a quarterly water wash outage and historically (as I’m told by my lead tech who has been here since dinosaurs) after opening the breaker on the generator and shutting the unit down, the site as done a series of three 30 minute cranks followed by an hour of waiting before starting another 30 minute crank. I’m being told that we can only do 3 of these 30 minute, followed by one hour rest in a 6 hour period due to limitations on the diesel starter and/or torque converter. When I asked what those limitations were there were none provided.
Additionally, I’m told that on start-up we will need to ratchet the turbine for minimum of 8 hours before we can go for a start as the rotor may have bowed while we were down.
Unless there are defined mechanical issues with either the diesel or the torque converter I see no reason why we can’t run them indefinitely until the turbine cools down to GE spec before doing the water wash. If properly cooled down and the turbine hasn’t sat idle for days or weeks on end, I see no reason why we wouldn’t be able to go for an immediate start either.
Would really appreciate some feedback on this from users with more experience then me (which isn’t saying much)!
I don’t see any reason, either, that upon shutdown you can’t go immediately to crank and leave it on crank until the unit is cool enough to wash. That’s how we’ve always done it for years.
And I agree with Sam that you should restart the unit as soon as possible after the wash (and spin dry) to minimize rusting. Since your unit has been spinning for hours during the wash, your rotor should be straight as an arrow.
As a side note, if you get better inlet filters, you won’t have to go down every quarter for compressor washes. You could go 1-2 years between washes, maybe.
I have not performed this type of wash after the turbine has come off line as we generally have lots of time to perform one as we are a peaking unit. I would have to agree with you on your mind set on the forced cool down from just looking at the turbine. As far as a unit being on ratchet for 8 hours before a restart, I see no reason why it could not be restarted as soon as the wash was completed. After we wash we restart and run up to speed to dry out unit as we do not want water setting in unit and letting it air dry. we have started unit up right after a off line water wash with no issues. Unless for some reason your unit is off ratchet while you are washing I see no reason why you could not restart sooner. Maybe some others in your situation will respond to your question with more experience,