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

Nav wrote:
... Let me remind you of what you said in your usual sneering
tone:


"Please tell me what ships you've steamed where the engine could be
stopped by "opening a steam bypass valve." Also please tell me where the
steam is bypassed to... are you suggesting dumping main steam directly
into the condenser? "

And, as Rick confirmed, "opening a steam bypass valve" does not stop a
turbine. You have to open steam to the reverse element.

In other words, you were wrong, Navvie.



Another point I'd like you to explain is how do you stop the engine and
not the shaft. Push in the clutch, maybe?

And I'm still waiting for an answer on that. Did the Titanic have a
clutch? How many large steamships have clutches such as you were talking
about in an earlier post?




No confusion at all. The pressure is exactly as I stated it. It was you
who claimed that the oiperating pressure was 11 psi(a).

No, that's not what I said, which is why you're not producing another
exact quote.

.... you said
... you know more about the Titanic plant and how
it works than anyone else.

Actually, I never said any such thing at all. You must be confused....
again....



... Strange that you don't know that steam bypass
vlaves are standard in multiple engine plants...

Actually, they aren't. There is no bypass from the HP and/or IP turbine
directly into the condenser in any plant I've ever steamed, naval or
civilian. So, there may be many plants out there with such valves, but
they're certainly not standard.


... Maybe they never let
you run the engines on the ship you served on.

Maybe. Wanna bet? Oh wait, you don't pay when you lose. Never mind.

DSK

Nav wrote:
Yes. http://www.dellamente.com Here you a

"Harland & Wolff were quite limited technically, with only their own
experience to draw on. They were aware of the power and economy the
turbine offered, although still unsure of its reliability, and chose to
play it safe ..."

Or is this another site that knows less than you about the Titanic?

It conflicts with what I've read about the design parameters laid out
for the Olympic class ships and discussion between Bruce Ismay (do you
even know who he is without Google?) and Lord Pirrie. I suggest you look
further. An excellent start would be to ask the question directly on the
Encyclopedia Titanica engineering forum.

I don't think you will, because I don't think you're interested in the
answer. You seem to be more interested in Jaxlike posturing and posing.
Certainly, a person with training in naval architecture would be able to
figure out prop slip, and would probably know where to find a good
reference to condensate depression.

DSK

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

Define "condensate depression" and explain it's significance in steam
plant operations.


Nav wrote:
Good lord. How childish. No wait, it's a genuine question right? Well
Doug, it's a temperature difference

Right.

Where?

I mean, between which two points in the steam cycle?

... that is impoertant to overall
thermodynamic efficiency which can be defined as P/Qh-Qc.

How else could it be defined, in more everyday terms?

... For a steam
plant, the steam temperature and it's dryness fraction times the mass
flow rate determine heat fluxes in that equation.

Yes Doug, I did freshman thermodynamics. Did you?

Yep. But your answer is mostly gobbledy gook to me. What's a dryness
fraction? Are you saying that condensate depression relates to degree of
superheat?

Rick can you make any sense of this?

DSK

DSK wrote:

Yep. But your answer is mostly gobbledy gook to me. What's a dryness
fraction? Are you saying that condensate depression relates to degree of
superheat?

Rick can you make any sense of this?

You both have really muddled and overcomplicated the issue.

Condensate depression is simply the difference in temperature between
the temperature at which steam will condense at the pressure existing in
the condenser and the temperature of the condensate in the hotwell.

Too much cooling (beyond about 10* below condensation temperature) means
that BTU's are needlessly tossed overboard and must be replaced by
burning expensive fuel.

Rick

Rick wrote:
You both have really muddled and overcomplicated the issue.

All I did was ask the question.


Condensate depression is simply the difference in temperature between
the temperature at which steam will condense at the pressure existing in
the condenser and the temperature of the condensate in the hotwell.

Absolutely & precisely correct.


Too much cooling (beyond about 10* below condensation temperature) means
that BTU's are needlessly tossed overboard and must be replaced by
burning expensive fuel.

Yes.... although the Navy cares less than they should about fuel
economy. We used to shoot for 5 degrees.

Here's a fun thought... let's list all the unexpected things found in
main condenser headers. How about a case of beer (unfortunately mangled
& empty)?

Fresh Steam
Doug King

DSK wrote:


No confusion at all. The pressure is exactly as I stated it. It was
you who claimed that the oiperating pressure was 11 psi(a).


No, that's not what I said, which is why you're not producing another
exact quote.



Ok you asked for it:

Nav:
Wot no bypass valve? Where did the steam go Doug -into the vacuum at the
tubine inlet? Bwhahahahhahaha!! You are such a clown. The inlet pressure
was 9psi -it's on all the web sites describing the engineering -or are
they wrong too?

DSK:
Actually, they are. The design (according to Harlan & Wolff, who should
know) called for inlet to the turbine at ~ 11 psia. So, if you grant
them 9psi *a* then they're not far wrong. Or are you now going to claim
that the condenser ran at 3 psi ... even back then, hotwell pressure was
usually given in mmHg... hint hint... "

Kblam!

Cheers

DSK wrote:



... For a steam plant, the steam temperature and it's dryness fraction
times the mass flow rate determine heat fluxes in that equation.

Yes Doug, I did freshman thermodynamics. Did you?


Yep. But your answer is mostly gobbledy gook to me. What's a dryness
fraction? Are you saying that condensate depression relates to degree of
superheat?



You claim to have done freshman thermodynamics in engineering and you
don't know what the dryness fraction is? How strange. Perhaps you had
better look it up -'cos I know nothing! Try a google and you'll learn
some freshman engineering on steam plants.

Cheers

Rick wrote:

DSK wrote:

Yep. But your answer is mostly gobbledy gook to me. What's a dryness
fraction? Are you saying that condensate depression relates to degree
of superheat?

Rick can you make any sense of this?


You both have really muddled and overcomplicated the issue.


It's Dougs fault. He always does this (asking ever more arcane
irrelevant questions) when when he's painted himself into his corner of
ignorance. He goes on and on until he finds something that you can't be
bothered to answer and then he'll jump around the playground claiming he
scored some point. I can see he's trying to do it to you now...

Cheers