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PostPosted: Apr 04, 2013 5:59 am 
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Only recently are large ships (except carriers) being designed as Brayton. They used to be HP Rankine.

Personally, I think the change over is a bad idea. It pretty much locks you into a specific fuel type.

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Last edited by KitemanSA on Apr 05, 2013 9:49 am, edited 1 time in total.

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PostPosted: Apr 04, 2013 6:50 am 
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Joined: Jul 14, 2008 3:12 pm
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KitemanSA wrote:
Only recently are large ships being designed as Brayton. They used to be HP Rankine.

Personally, I think the change over is a bad idea. It pretty much locks you into a specific fuel type.


Braytons should be able to take almost any combustible fuel. As I recall, the Abrahams M1 main battle tank uses a Honeywell Brayton, and it can guzzle just about any fuel, gasoline, diesel or peanut butter*.
Designing it for a specific type of fuel is more efficient, though.

*well maybe not peanut butter. Not that you'd have enough peanut butter around to fuel an Abrahams.


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PostPosted: Apr 05, 2013 3:48 am 
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Joined: Dec 26, 2007 11:45 am
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Cyril R wrote:
KitemanSA wrote:
Only recently are large ships being designed as Brayton. They used to be HP Rankine.

Personally, I think the change over is a bad idea. It pretty much locks you into a specific fuel type.


Braytons should be able to take almost any combustible fuel. As I recall, the Abrahams M1 main battle tank uses a Honeywell Brayton, and it can guzzle just about any fuel, gasoline, diesel or peanut butter*.
Designing it for a specific type of fuel is more efficient, though.

*well maybe not peanut butter. Not that you'd have enough peanut butter around to fuel an Abrahams.


IIRC, the lifetime and maintenance costs of gas electricity-generating gas turbines is affected quite dramatically when burning anything but natural gas.


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PostPosted: Apr 05, 2013 4:47 am 
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Yes, natural gas is very clean stuff and always in gas phase, which protects against erosion and corrosion. Burning dirty fuels with high particulate, high sulphur etc. would obviously increase wear and corrosion, but that should also be true of other engine types. Diesel engines don't like high sulphur fuel with noncombustibles in it, either, though perhaps they are more tolerant towards erosion than gas turbines?


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PostPosted: Apr 05, 2013 3:07 pm 
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Joined: Apr 28, 2011 10:44 am
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Marine, long stroke, low speed (75 RPM) diesels are designeed
burn Bunker C, about the crappiest fuel know to man-kind
-- at least this side of coal --- with modest on-board pre-treatment.
Up to 4 pct S and lots of other nasties.
This is hte same fuel we used to burn in the boilers
on the steam ships.

A gas turrbine would not last ten hours on this stuff.

Jack


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PostPosted: Apr 06, 2013 6:25 pm 
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@turbines; Every active-service navy ship I've visited uses turbines. However, I know that older ships do not. The Lexington is now a museum in San Diego, and I toured its power plant, which is an oil-fired ~100mw steam turbine. (The docent wasn't sure, and the documents disagreed.)


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PostPosted: Apr 06, 2013 11:31 pm 
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The working fluids have served us in reciprocating engines and turbines. It may be time for fuel cells and thermionic, photovoltaic, or neutronic emission of electrons for direct conversion to electricity.


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PostPosted: Apr 08, 2013 7:14 pm 
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Location: Calgary, Alberta
Just repeating djw1's comments: One of the positive reasons for using steam turbine technology in warships was that they could burn anything they could get their hands on, usually some variation of Bunker C, but burning lighter fuels or even crude oil was possible. Modern gas turbines, especially the aeroderivative GT's used by the navy do not tolerate dirty fuels for very long at all, they need clean fuels like automotive gas oil, low sulphur diesel and Jet A1 (kerosene) to avoid expensive premature failures and high wear rates on hot components. They certainly cannot tolerate Bunker C.


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