Ancillary vacuum appurtenances

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ccdewitt
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Ancillary vacuum appurtenances

Post by ccdewitt » Thu Sep 24, 2020 2:46 am

One last question for the evening: Does anyone have an opinion on the application of a steam ejector to the keel condenser for the purpose of drawing down a flooded condenser or to facilitate the starting of the engine?
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TahoeSteam
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Re: Ancillary vacuum appurtenances

Post by TahoeSteam » Thu Sep 24, 2020 3:13 am

There is at least one launch that I'm aware of that has a steam ejector specifically for that purpose.

That is Alan Gregg's "S.L. Lorraine". He has an AVL compound in her. I don't know if it's necessary as we don't have one on "Persistance" with a much larger engine. I'm certain it would make warming and starting a much faster exercise (we feel 20minutes is plenty fast...), but how fast are you going to (or needing to?) be steaming up with solid fuel and a firetube?

Might be a more relaxing exercise just cracking the throttle when you get 20# on the clock and rocking the links at random intervals until the engine ticks over by itself, or you have to give the flywheel a kick or two...
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barts
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Re: Ancillary vacuum appurtenances

Post by barts » Thu Sep 24, 2020 4:48 am

I would certainly consider a steam ejector as a good idea on a plant that needs vacuum to start reliably. The use of separate engine driven pumps to provide both vacuum and boiler feed was common in larger vessels; I don't think large triples could start w/o vacuum and a cleared condenser. Alan's set up takes hardly any space and clearing a water logged condenser is a lot nicer that way.

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Re: Ancillary vacuum appurtenances

Post by steamboatjack » Thu Sep 24, 2020 7:32 am

I have considered the use of a steam ejector for this but never got around to it, it would be particularly useful with a uniflow engine. One problem is that it was usual to condense the outlet from the ejector via a heat exchanger, this would be an added complication and perhaps not required just for start up.

Large marine engines with engine driven feed and air pumps routinely drained the condenser to bilge before starting either manually or via a check valve known as a “snifting valve” from Newcomen days (not same as a loco version).

Jack
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