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