steam jet air ejector

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Ralph B
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steam jet air ejector

Post by Ralph B » Thu Dec 03, 2009 5:45 pm

Bart had mentioned steam air ejectors earlier. The large steam plants I have worked at as an operator have all used them (as well as the USN) but I never thought of them for small scale usage in a steamboat. One advantage I can see is ensuring a constant flow of steam in the superheater, but I don't know how efficient one would be to use rather than an air pump.

Any thoughts? Anyone try this?
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Re: steam jet air ejector

Post by steamboatjack » Fri Dec 04, 2009 8:51 am

never tried this but it's crossed my mind a few times, would be useful with uniflow engines to ensure a vacuum at starting. I guess a single stage ejector would suffice for a launch with perhaps a pump as well for the bulk of the condensate.
problem with an air ejector is that the heat from the steam needs to be recovered, usually by heating the condensate so you can end up with a complex plant for not much gain.
regards jack.
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barts
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Re: steam jet air ejector

Post by barts » Sat Dec 05, 2009 7:17 am

I'd only use it to help keep vacuum during docking; one generally has too much steam then anyway ;)
Normally they use too much steam in our small plants, and they do heat up the hot well when run too long.

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Re: steam jet air ejector

Post by 87gn@tahoe » Sun Dec 06, 2009 5:52 pm

Bart, doesn't Alan Gregg have a steam-jet air-ejector on the S.L. Loraine?
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Re: steam jet air ejector

Post by barts » Mon Dec 07, 2009 4:39 am

87gn@tahoe wrote:Bart, doesn't Alan Gregg have a steam-jet air-ejector on the S.L. Loraine?
I'm not sure. but that wouldn't surprise me at all. I used to have one on the Otter for emptying the bilge, but after the old compressor engine started leaking crankcase water (and a bit of oil) from its seals I removed it to prevent accidental oil discharge. They're not difficult to make work, but getting them efficient takes some engineering, as the nozzle size, etc, makes a big difference. I've looked for design details on the web, but that's hard info to find....

I have one of those air-amplifier gadgets on my oil burner, btw; those really kick out some forced draft if you're trying to make a lot of steam...

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Ralph B
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Re: steam jet air ejector

Post by Ralph B » Mon Dec 07, 2009 6:06 am

Here is a link to several articles on SJAE's http://www.graham-mfg.com/index.asp?pageId=113

I never thought of using one to dewater the bilge...my mind gets stuck in the box a lot.
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Re: steam jet air ejector

Post by steamboatjack » Tue Dec 08, 2009 2:01 pm

I doubt if there is a boat in the UK which does not use a bilge ejector.
regards jack
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