Engine runs on air but not steam

[zakman]

Hi everyone, I recently acquired a steam engine and boiler both made by Stuart Turner, the boiler is a 501 and the engine is 10V. The engine was a bit of a mess with parts missing and worn so I decided to get it running before any restoration work.

After repairs I hooked it up to my compressor and set the timing, it will run at practically zero psi and runs at high speed well, very impressed and pleased with myself as this is my first steam engine.

So I coupled it up to the boiler to try it on steam, it absolutely refuses to run, it hicks and coughs a bit and spits out water through the exhaust along with a few puffs of steam but that's it. I had the boiler at over 20psi and opened the valve fully which surely should be enough ?

Hooked it back up to the air line and it ran perfect even at very low pressure.

I'm a bit confused as to why it chucks out a load of water and not so much steam, the water sight glass is just over half way up, I checked the valve and the steam line etc. Am I missing something simple ? I'm learning all this as I go along so any help is more than welcome.

 

[werowance]

on my little steam engine, if it spits water and not steam, then its usually because I overfilled my boiler. mine will not run like that either. try filling the boiler to maybe half or little fuller (where mine likes to run but its home made and not a stuart) that way I get steam and not water. I might get a little spurt of water on the first spin over or 2 but after that its just steam.


EDIT - never mind I see where you state half full in the site glass

assuming the half the site glass = boiler half full on yours then you might try going a little less as a test

 

[Brian Rupnow]

You should pre-heat the cylinders. If they are cold or even cool when the steam is admitted, the steam immediately condenses and can hydraulic lock your cylinders. That is why full size steam engines had a drain on the bottom of the cylinders--to let the condensate out after the cylinders were heated up by the steam.

 

[zakman]

Hiya and thanks, by the time I had finished messing about the boiler was less than half full so I dont understand, it's weird, I dont know much but it doesnt make sense. I can understand how a little water might get forced up but not like a stream.
I might try lifting the engine higher just to see what happens bu it should be ok on the same level, uhhhhhhh, I thought things were going to well !

 

[zakman]

Hi Brian, didnt see your post, I've never seen that done, is that a normal thing to do ? it does make sense.

quick edit..... so thats what the 2 little cocks are for on the cylinder ? I didnt know ! will try it tomorrow.

 

[Blogwitch]

When feeding hot steam/water to an engine, you also require the correct grade of steam oil that should be fed in with it as well, usually by means of a seperate displacement lubricator in the steam line.

If you don't use any, friction may soon stop things dead or prevent it from running.

John

 

[zakman]

Ah yea the steam oil thing I knew about, I had plenty of light oil inside and out to run it on air but I've read it emulsifies when mixed with steam, I just couldn't resist wanting to see it run on steam if only for a couple of minutes. Its going to get stripped down again and restored once I know I have it sorted out.

The condensing thing sounds so obvious now that I've been enlightened :thumbup: I'll also change the length of rubber fuel pipe I was using as a steam line !

I'm learning each day and enjoying the challenges.

 

[Hopper]

I had the boiler at over 20psi and opened the valve fully which surely should be enough ?

You will get a better result if you run the boiler at its correct working pressure, about 60psi for most Stuart boilers. Then don't open the valve fully but just crack it open partially. This will "wire draw" the steam, making it less prone to condensation as soon as it hits a cooler surface.

What you then have in a nutshell is steam at almost 60psi temperature, 307 degrees F, but thanks to the partially open valve, that same steam is only at, say, 20psi or even much less when it hits the cool cylinder. In effect, the steam is super-heated and requires a much bigger drop in temperature before it condenses. Steam at 20psi will not condense until it drops below 258 degrees F.

Steam direct from a boiler running at 20psi on the main pressure gauge is only at 258 degrees F so as soon as it hits the cool cylinder and loses one degree temperature, it condenses into water. If it hasn't already done so along the steam line between boiler and cylinder.

That's why warming the cylinder and also insulating the steam line and cylinder will also help. It reduces that temperature drop before the steam has been expanded inside the cylinder.

 

[Mechanicboy]

Before start up the steam engine, let the drain cocks be open both upper and lower of the cylinder. Then open the steam from boiler to steam engine and let it warm up cylinder until all condensed water is disappeared, pure steam only (oil out of drain cocks is normal) then close the drain cocks then the steam engine will run.

 

[zakman]

Thanks guys, very helpful ! I've read a lot over the last couple of weeks but there's always gaps that dont get filled till you actually do it.

I dont have a proper burner, its a thing I made up with a double wick, I dont think its big enough as I cant get the pressure much above 20psi on the boiler gauge, so that needs changing. The steam line probably needs to be all copper and much shorter and now I know the procedure for purging condensed steam (and why it happens). Great stuff !

 

[Mechanicboy]

The steam line probably needs to be all copper and much shorter

Length is not problem: Insulate copper tubes with thick cotton or wool thread wound on copper pipes (preferably 2 layers) + woven tape around insulation to avoid heat loss.

 

[zakman]

Thanks Mechanicboy, I honestly though the lagging I've seen on some set ups was for aesthetic purposes, now I know better. When I eventually get it all sorted out and bolted down I'll be doing the same.

 

[Mike1]

If you can pre heat the steam before it gets to the engine this will dry the steam and give a better preforming engine, I run the steam feed pipe through the boiler flue as in the photo, the small diameter pipe is the steam feed to the engine which is looped in the flue, (Centre flue boiler) the larger pipe is the exhaust taken up the flue.

Mike.

 

[zakman]

Thanks Mike, what a lovely boiler and engine, my flue gets very hot so I can see the benefits of it, something else for me to consider.

I was looking at the oiler to the right of your engine, I have one similar but not connected yet. It looks like the inlet to the oiler is capped off ? I thought this was the steam inlet ? I'm puzzled again

 

[Mike1]

The cap on the top of the lubricator is the filling cap, screw off to fill with oil, the pipe for the oil and steam is the one fixed to the steam chest which has a needle valve incorporated to regulate the oil flow to the engine, the steam enters through this pipe from the steam chest and condenses displacing the oil which flows to the engine through the same pipe ( A bit of a mystery but it works ) there is a drain valve at the bottom of the lubricator to drain off the condensate,

This link will give you more idea. Mike

https://www.google.co.uk/search?q=steam+engine+displacement+oiler&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiNtfiB8araAhWlDsAKHeivA3wQsAQIiAE&biw=1536&bih=714&dpr=1.25

 

[zakman]

Ahhhh now I understand, I was wondering how these things worked......cheers Mike !

 

[Mechanicboy]

There is 2 difference lubricators for steam engine: Displacement lubricator or mechanical lubricator.

See my movie of steam engine with mechanical lubricator and feeding pump with preheater for steam boiler. The feeding water pipe between preheater and boiler is insulated to prevent loss of heat in boiler.

[ame="https://www.youtube.com/watch?v=qCdJjcHjVNQ&t=38s"]https://www.youtube.com/watch?v=qCdJjcHjVNQ&t=38s[/ame]

Displacement lubricator with window + regulating valve for amount of oil is practical and economic. Available in Ebay (seller: galglg)

 

[zakman]

Sorry to bring this thread back but I need to say thank you for all the help, I've had the little engine running on steam a few times now, its a bit noisy, it blows out steam here and there and the timing needs some adjustment, but I'm delighted ! thank you guys :thumbup:

 

[Mike1]

That's good to hear, enjoy your engine.

Mike.