How to recycle engine exhaust steam back to the boiler?

[Rocket Man]

Several years ago I built a steam condenser for my 1.5" x 1.5" steam engine. 77 feet of 1/4" copper tubing will turn steam to water but water is tapped in the copper tubing coil like water with a sealed bottle.

I know steam locomotives in the late 1940s had steam recover to reuse the same water how does that work? I am sure someone figured out the best way to do this 70 years ago?

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[Jasonb]

The condensate can be stored in a tank which supplies a pump be it axle/crankshaft driven or a separate steam pump. the pump supplies the boiler via a clack valve

 

[SmithDoor]

Try the recycle engine exhaust steam in Titanic.
The steam out main two engines was under 212°F then recycle to the third engine. But the Titanic used SEA water water for cooling the last of steam.

Dave

Several years ago I built a steam condenser for my 1.5" x 1.5" steam engine. 77 feet of 1/4" copper tubing will turn steam to water but water is tapped in the copper tubing coil like water with a sealed bottle.

I know steam locomotives in the late 1940s had steam recover to reuse the same water how does that work? I am sure someone figured out the best way to do this 70 years ago?



View attachment 133538.

 

[Steamchick]

On my boats I always have a condenser to do 2 things. Recycle the water to the boiler via an engine driven pump, and introduce some vacuum to improve efficiency. That's how all the steam ships do it since Brunel. And some steam railway locomotives where water is scarce (dessert regions) or where the steam is an inconvenience (London underground railway pre-electrification). You need to balance the pump on the engine with volume of condensate (at full steam) or the boiler will run dry. 1 boat ran between 5 and 10 mins without recycling (max to min on water gauge), but more than 20 mins and still had a good level of water, when the pump was fitted. I also recycle the warm condesate past the gas cylinder to maintain gas pressure on the boat's butane cylinder. "Proper" models are not just Toys, but replicas of real systems. IMHO. So carry on with the condenser! And fit the return feed pump.
K2

 

[chrsbrbnk]

one thing that needs addressing is the cyl oil in the condensate from a reciprocating engine , turbines don't have that problem. but there are schemes for getting it done. I saw a full size A.D. Baker traction engine where it was using both super heaters and recaptured water at like 300 psi. so it can be done

 

[Rocket Man]

I have and idea to put a piston pump in the bottom of a water catch pan. Piston will push water back into the boiler.

My biggest problem is steam in the copper tubing condenser turns to water but water will not drain out. Steam volume reduced about 1800 times when it cools to water so the whole condenser coil becomes totally full of water before 1 drop finally drips out. I can probably make condenser drain better if I use larger diameter copper tubing. Water has high surface tension air can not get into the 1/4" tubing to allow water to drain out. Maybe I need to live with a condenser coil that is always 1/2 full of water. Running engine faster 300 RPMs condenser gets hotter about 95% of the 1/4" tubing is required for cooling then only 5% of the tubing is full of water. Maybe it is a good thing water will not drain out of the condenser and I just don't know it yet. Steam engine runs good with no load on 5 psi steam. I have forgotten how to do the math but I once calculated 1 HP at a certain RPM and certain PSI the engine will turn a 24" fan blade 500 RPM for about 10 minutes when boiler gets low on water.

 

[abby]

The exhaust steam passes into a closed condenser where it is cooled by cold water. The cooling of the steam produces a partial vacuum in the system.
Air that has been released from the boiling water is removed by an air pump. The condensed water is pumped back into the boiler through non-return valve (clack)

 

[Steamchick]

I guess the vacuum in the steam side of the condenser is holding the water from draining. On my boats, the condenser fills until the back-pressure (vacuum) reaches atmospheric, when the next pulse of exhaust steam then pushes the condensate into the separator tank. The oily emulsion floats on water in the separator, and the water is extracted by the pump from the bottom of the tank. (I GUESS. I am not on the boat when running!).
I start with a full tank, so the boiler (feedpump) is being fed with fresh water while the engine and condenser are consuming steam, then the system stabilises itself, at a balanced level, when the condensate appears. It is a copy of an old simple system -which works - so I don't worry about it.
K2

 

[Gedeon Spilett]

I guess that your condenser is far too small, if it full of water...
you need several pumps, one for circulating cooling water, one for air and water and one feed pump for the boiler.

 

[Steamchick]

There is no room on my model boat for the full set-up of air-pump etc. and insufficient power! The simple system is one that has worked on model steamers since Victorian times. But the pump must be sized to just take all the steam at full throttle. No crew to change settings! (The 4" high sailors just stand there... unmoving).
K2

 

[Charles Lamont]

I know steam locomotives in the late 1940s had steam recover to reuse the same water how does that work? I am sure someone figured out the best way to do this 70 years ago?

You will need to go back 300 years to Newcomen.

Most steam engine condensers use water as the cooling medium, but there were a few air condensers too, perhaps most notably on White and Doble steam cars. What looks like a large conventional radiator is actually the condenser.

Your problem, as I think you have realised, is that your long single coil of small bore pipe is not an ideal configuration for a condenser.

 

[swarf]

The 4" high sailors just stand there... unmoving).

 

[ajoeiam]

The 4" high sailors just stand there... unmoving).

(LOL) Is that different when the sailors are taller? (LOL)

 

[SteamChEng]

A more conventional arrangement for a condenser for a steam engine (turbine or otherwise) is to have the cooling medium running through the tube bundle and the steam flowing over that bundle to be cooled and collected in the hotwell. That way the condensing steam and water don't get locked up in the long, continuous tube. It also allows a way to extract air and other non-condensable gases from the condenser via air ejector or vacuum pump.

That's probably a lot harder to implement in a model than in full-scale engines, though!