Neon said:
If you'd bothered to actually READ ALL of my post you'd realize that
I was talking about the added drag from raising the condenser
temperature and therefore pressure enough to make the temperature of
condenser discharge water useful.
And if you knew as much about turbines as you did about radiation monitors,
you'd know that raising the temperature/pressure at the exhaust of a loaded
turbine doesn't 'increase drag'. The last stages aren't 'dragging' the
shaft down they are pushing the shaft along the same as the rest of the
stages. Otherwise any engineer worth his salt would have the stages
removed.
Raising back-pressure certainly reduces turbine output. My objection is
your use of the term 'drag'.
The only time the last stages 'drag' is when the turbine is very lightly
loaded or unloaded.
Are you trying to make a great big impression with some teeny tiny
knowledge again? It' ain't working. We're talking about concepts
and you're trying to impress us with detail trivia you learned in AUO
school. It ain't working.
Just because I'm talking over your head doesn't mean it is of no importance.
Taking extraction steam from a turbine takes a hell of a lot more than just
'welding up some piping'. And that's my point. You're the one that knows
little about turbines and think you can 'weld up some piping' to get more
extraction steam.
Pull a lot more steam from an extraction point and you 'starve' the
downstream stages. Now they do 'drag' and you've lost a lot more turbine
output than if you did the job right.
Try to wrap your brain around the CONCEPT of extraction steam
PROBABLY being more efficient than steam from the steam generators.
I say "probably" because I'm not a thermodynamicists and you aren't
either.
Guess again about my thermodynamic skills Neon. I was pointing out that
although you *could* just weld up some piping, you would get lousy results
from such a 'half-assed' design.
And there is no doubt in any real thermo engineer's mind that *extraction
steam* would be much more efficient than steam directly from the steam
generators. Just ask yourself why they use extraction steam to pre-heat the
feed-water return to the steam generator instead of main steam. When you
can understand why that is, then the choice of which to use for this sort of
district heating is obvious. (hint: consider looking at the entropy created
if you use main steam)
Someone more qualified than either of us would have to run
the numbers for a specific design.
Hmmm, I sit here and think about how easily we backfitted a condensate
polishing system to Sequoyah and just have to laugh at such
absurdity. Hell, I can SEE the turbine extraction lines while
standing outside at the railroad dock.
What a moroooon. And just *what* does a condensate polisher have to do with
changing the steam flow through the turbine? Surely you're not *heating* it
now are you?
Polishers *are* just welding up some piping and providing some more piping
to re-generate the media. About the only concern to the rest of the steam
plant is maintaining suction pressure to the booster and feed pumps (and the
increased pumping power lost). Changing the flow through a steam turbine
and increasing extraction flow is much more complex than that.
Taking more steam from any extraction point along the turbine stages means
there is less steam flowing through the subsequent stages. So if you want
to optimize things you design the subsequent stages a bit smaller so you
still get the optimal work extraction from the remaining steam. Depending
on what stage you extract from, there is also the concern about how much
moisture is in the line. You want to remove the moisture from the turbine
to reduce erosion, but it's wasteful to send this hot water directly to the
condenser. So it is diverted to feed-water heating now but it could be used
in a 'reboiler' to make district heat.
If you didn't chose the last extraction point for your project, then you
also need to look at how drawing more extraction steam from your point will
affect the remaining extraction points. Less steam there means lower
temperatures from those feed-water heaters.
Are you posting while drunk again or something?
No, but it's obvious which one of us has spent more time actually working
around and studying steam plants and which one of us spent his life in a
highly specialized area building radiation monitors.
daestrom
That was kind of my point...
