Rick wrote:
Well, in the mode and condition which I described, I KNOW that the
engines can run indefinitely without exceeding the condenser capacity.

OK. I'm a bit surprised to hear that, since it's definitely not true of
most plants I know about. Otherwise loss of condenser vacuum wouldn't be
given such a prominent place in the drill book.


... The circulator pump moves more water than is required to remove
the heat leaving the turbine. Reduced power operation might have been
required, just as modern plants - even military plants - but there is
no time limit associated with that condition.



???


What part of steam plant operation and construction elicited the "???" ?
Most condensers and circpumps have a larger capacity than required for
normal operation up to a sea temperature around 85* F. Under some
conditions of sea temperature and load, reduced power operation may be
required to match condenser capacity. Once the balanced is achieved
there is no time limit to operation.

Well, that's what I meant. You're taking that balance very much for
granted. "Under some conditions, reduced power operation may be
required" is definitely true, but an understatement IMHO. Sometimes you
have to shut down and start over, to restore vacuum!

Run that by again ... "compression" of the shaft? I would love to see
the figures on that one ...

Sorry about that.... got it backwards... in stopping the shaft against
the momentum of the ship, the shaft would be in tension... not going to
produce much axial load that way! Make that strain on the couplings, not
the line bearings

BTW I wonder why our brilliant Navspritjax didn't catch that mistake?

Interesting discussion, thanks for joining in.

Fresh Buckets O' Steam
Doug King

DSK wrote:

Rick wrote:

Well, in the mode and condition which I described, I KNOW that the
engines can run indefinitely without exceeding the condenser capacity.


OK. I'm a bit surprised to hear that, since it's definitely not true of
most plants I know about. Otherwise loss of condenser vacuum wouldn't be
given such a prominent place in the drill book.

Drill book?

What drill book?

Cheers

DSK wrote:

OK. I'm a bit surprised to hear that, since it's definitely not true of
most plants I know about. Otherwise loss of condenser vacuum wouldn't be
given such a prominent place in the drill book.

Loss of vacuum is a show stopper ... loss can occur for any number of
reasons unrelated to engine operating conditions ... and most often has
nothing to do with what the engine is or was doing. There is a reason
the vacuum guage is the largest and placed squarely in view of the engineer.

Well, that's what I meant. You're taking that balance very much for
granted. "Under some conditions, reduced power operation may be
required" is definitely true, but an understatement IMHO. Sometimes you
have to shut down and start over, to restore vacuum!

The balance is taken for granted, at a given vacuum I can remove a given
amount of heat ... removing a given amount of heat will produce a given
vacuum for a given steam flow, it is very simple, don't put any more in
than you can remove. Loss of vacuum equates to a loss of power in a
steam plant, it's like putting a potato in an exhaust pipe, if you can't
get the potato out quick enough the engine stops ... no magic there.
There is no need to "shut down" if you completely lose vacuum,
everything shuts down all by itself ... especially if you are relying on
SSTG's for electrical power. Have been faced with losing vacuum many
times but have never seen or heard of having to shut a plant down in
order to restore it ... most vacuum comes from the condensation of steam
in the condenser so stopping all that steam from entering is the worst
thing you can do.

Rick

Rick wrote:
The balance is taken for granted, at a given vacuum I can remove a given
amount of heat ... removing a given amount of heat will produce a given
vacuum for a given steam flow, it is very simple, don't put any more in
than you can remove.

Simple in theory, complicated in practice.

... Loss of vacuum equates to a loss of power in a
steam plant, it's like putting a potato in an exhaust pipe, if you can't
get the potato out quick enough the engine stops ... no magic there.

Exactly. That is what I've been getting at all along. If vacuum starts
going down, you have to start redcing steam in.


There is no need to "shut down" if you completely lose vacuum,
everything shuts down all by itself ... especially if you are relying on
SSTG's for electrical power.

Sure, but hopefully you don't let it get that far.

...Have been faced with losing vacuum many
times but have never seen or heard of having to shut a plant down in
order to restore it ... most vacuum comes from the condensation of steam
in the condenser so stopping all that steam from entering is the worst
thing you can do.

Never had a condenser get a slug of air from the glands? Never flooded
the hotwell when a condensate pump craps out?

Anyway, if you keep dumping too much steam into a condenser as it loses
vacuum, it can get really hot and make it difficult to restore vacuum
without shutting down and starting over with the air ejectors.

I make no bones that most of my experience, and all my training, was in
the Navy, which practices these things regularly and tends to run all
drills out to their end point. It looks to me like we agree on many
things but have widely different experiences in widely different plants.

Regards
Doug King