Re: Steam turbine efficiency?

On 01 Aug 2007 15:32:07 GMT, steamer <steamer@xxxxxxxxx> wrote:

--ISTR reading somewhere that a steam turbine doesn't surpass the
efficiency of a reciprocating steam engine until it's big enough to produce
something like 50hp. Can someone cite a reference for this? I've head this
figure often but someone said 'prove it' the other day so I'm hoping someone
knows how..


I haven't seen any figures, but those numbers feel reasonable. Bear in mind
that a 50hp steam turbine would be a tiny thing. In comparison, we have a
typical 8000 hp/7000rpm boiler feed pump turbine from a 600MW set in the shop
at the moment and the bladed part of its rotor is about 18" diameter by 3'
long. This is a turbine that normally runs in parallel with the IP turbine, so
has an inlet pressure of about 500 psi and exhaust pressure of about 100 psi.
There is a single row of main steam pressure blades for starting, they have
blade heights of about 1/4". This is a very small and not particularly
efficient turbine.


Mark Rand
RTFM
.

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