Vertical Boiler Fittings

[gary arthurParticipant @garyarthur48070]

Well… I tested the above arrangement today, only to find that the setup would raise but a meagre amount of steam. Not enough though!



Trying the Trangia at different heights relative to the bottom of the boiler did make a bit of a difference, as did the steam blower, and the beginnings of steam made themselves apparent, but the pressure gauge held resolutely to zero.



Was it because the Trangia was too shut in and not getting enough oxygen? The next experiment should help to clarify that (Trangia, with boiler supported by an open framework).



Noteworthy though that again today my primitive four wick meths burner did raise decent steam ( as per video above), albeit perhaps against all odds. Maybe a way forward…?



And a forum friend has encouraged me to consider gas as an alternative. Well, no harm in keeping one's options open, I guess…



This is all more tricky than I expected but I'm not out of ideas yet…



Will keep tinkering, and post the results…

[Paul KempParticipant @paulkemp46892]

Gary,

Never having heard of a Trangia burner (sheltered life maybe lol) I consulted Mr Google! Many of the comments re suggest they are slow to boil water in a pan. I get the impression they have a relatively low heat output so in terms of a burner design for steam raising? I have not seen one burning but imagine there are many small flames from the various holes? Have you thought about a burner along the lines of the old paraffin stoves with a 'ring' wick and a large circular flame? They were designed to chuck heat out.

Paul.

[gary arthurParticipant @garyarthur48070]

Hi Paul –

I have never been given to living the high wild life either… well, not huddled round a Trangia at least 

You may be right – I'll find out when I test the Trangia in a more open setup where there will be plenty of airflow.

My crude four wick burner does the job in any case, though the flames seem a bit out of control.

Thanks for your suggestion – while I was following it up I came across this:

I know it's not the same as what you suggested but at that price it's definitely worth a try with a couple of modifications, so I bought it. If it doesn't put out enough heat it will still give me plenty of bits to play around with.

Will report back here in due course.

Thanks again.

Edited By gary.a.ayres on 05/01/2019 11:00:25

[gary arthurParticipant @garyarthur48070]

Following my unsuccessful attempt (details above) to raise steam with the Trangia in a partially enclosed housing, I made a new trial setup which is wide open in structure and tested it this evening. I decided to simply fire it and wait and see if it would get the safety valve to blow off. This evening, the Trangia slowly but surely raised steam. It took 50 minutes from cold and just over one fill of the burner with alcohol to blow off the valve without using the steam blower. The suppliers of the valve told me it was rated at 45 psi, but the gauge showed closer to 70 by the time it blew. How accurate the gauge is I do not know. I then played around with the steam blower for a bit and enjoyed the definite way in which it pulled at the flame. The Trangia throws out less heat than my crude four-wick burner but it burns in a much cleaner and more controlled way.



This was hardly a controlled experiment as I carried out this evening's test inside my workshop whereas the previous attempt took place outside. I am therefore left wondering whether tonight's firing was much better because of the burner not being shut inside a housing or because being indoors the flame wasn't being blown around (although there wasn't much wind the other day). It will be easy enough to check this tomorrow evening by firing it under the same conditions as this evening but with the burner inside the housing rather than open.



A little bit of a feeling of progress this evening. Picture below:

[duncan webster 1Participant @duncanwebster1]

I'm one of the nutters who used to commune with the clouds. Meths Trangia would boil a pan of water in a lot less than 50 minutes, we'd have got bored and given up long before that. I seem to remember a much bigger flame than you show above, but it's all a long time ago. For day trips a thermos flask was a lot easier.

I have the gas equivalent if you want to borrow it, but buying one might be less than the postage.

[gary arthurParticipant @garyarthur48070]

Hi Duncan –

Yes, I haven't tried the Trangia on a pan of water, but I believe it should boil one in about 15 minutes. I guess it's the all-important psi of steam pressure that makes the difference here. I'm new to this, but I'm guessing it could have had a small engine running quite a bit sooner than 50 minutes.

Many thanks for your kind offer, but I have ordered a gas burner that cost eleven quid and is already on its way. The plan is to have fun customizing it. I suspect it will fire up this boiler pretty fast.

I have also ordered an eight-wick kerosene camping stove to try, but I think the ring might be too big. At a tenner, though, it's a risk worth taking. I'll find out when it arrives.

At the moment I'm just trying out different firing methods with a view to ending up with a few interchangeable options/burners. I'm drawn to simplicity (e.g. meths rather than pressurized gas containers, etc.), but have come to realise the need to be practical. It took me a while…

Cheers,

gary

[Neil WyattModerator @neilwyatt]

Lagging the boiler will make a significant difference too.

Neil

[gary arthurParticipant @garyarthur48070]

Neil – yes, I'm sure it will.

Cheers.

[gary arthurParticipant @garyarthur48070]

My multifuel adventures continue.



This evening I tested the Trangia inside the cast iron housing which features a few posts above. It was tested under very similar conditions to the open structure I tried last night, i.e. indoors, same burner height, similar amount of water in boiler. Last night with the open structure it took 50 minutes from cold before the safety valve blew off. This evening with the cast iron housing an hour and a quarter in and still nowhere near. There was also an acrid smell – not overpowering but unpleasant. I'm not sure if this came from poorly combusted alcohol or from the plasticky paint inside the housing, but I gave up the ghost and turned off the heat. So, even though I thought that the housing was plenty open enough, clearly it wasn't, so I'll use the open structure if and when I fire the boiler with the Trangia in the future. I guess this could be an option for indoor use.





Meanwhile, look what landed in my back yard today:







Hitherto I have resisted gas, but I took some good advice and decided to cut myself some slack and keep my options open. When I saw how furiously this bad girl burns when you open up the throttle, I realised why it's a popular option. Doesn't look like raising steam will be a problem



Mods have already begun on the gas burner. I know each situation is different, but any advice on the optimum distance between this standard size burner and the bottom end plate of a 3 inch boiler will be welcome…



gary

[gary arthurParticipant @garyarthur48070]

I tried the boiler on my gas burner for the first time. I removed the pot stand from the stove burner and set the latter up temporarily on some bits of round stock. Way more powerful than the meths was, as expected – it blew off the safety valve in 15 minutes and I'm pretty sure it would have been much quicker than that if I had turned the flame up higher. It maintained a steady jet of steam from the steam out valve, and I noticed that when I opened the steam blower just to try it, it pulled the flame up into the tubes quite dramatically. However, I think I gave it too much blower as the whole thing went a bit out of control and started to splutter water, at which point I turned off the gas and let it cool down. Overall, though, looking good, and the colour of those flames is to die for:

 

 

Meanwhile, in preparation for my next try with coal, I bought this after a fellow forum member kindly drew my attention to it:

 

 

It's a quality little piece of British engineering from the 1970's – a cooling fan for some piece of equipment on a plane, possibly military. It appears they are quite often used as blowers. It has the kind of motor which doesn't reverse direction when the polarity of the wires is changed round, so the suction tube has to cover the fan rather than connect to the nozzle. Fortunately I had a copper plumbing reducer which wedges pretty snugly between the three housing screws. Here it is jury-rigged; I think a bit of metallic tape and/or heatproof sealant will suffice to see it working:

 

 

Having been given feedback that my last firebox for coal was too wide and not sealed enough, I got started on making a leaner, tighter one:

 

 

I am now by no means certain that this boiler – which is 3 inches in diameter with only five tubes – will run on coal (or wood or charcoal). In fact I'd say it's touch and go. But it's worth one more try…

 

Meanwhile – as I want to end up with a few options for firing – I'm waiting for a couple of things to arrive which will further my adventures with liquid fuel…

[SillyOldDufferModerator @sillyoldduffer]

Posted by Neil Wyatt on 08/01/2019 09:12:20:

Lagging the boiler will make a significant difference too.

Neil

Looking at Gary's boiler I see a massive heat-sink. The heat (from whatever source) has to lift the temperature of the boiler's metalwork as well as the water inside. Once the water approaches boiling point, significantly more heat is needed to make steam – a lot more. The boiler has a large surface area extended by pipework: if you wanted to heat a room it makes a decent radiator. Also, with only five short tubes, I would expect a lot of heat to go straight up the chimney and away. Gary has also used a lot of metal in legs or the burner: these also are likely to soak up and waste heat.

It's possible to measure how much heat is wasted by filling the boiler (burner off) with a known volume of boiling water from a kettle and – with a thermometer – measuring how long it takes to cool down. Without bothering with the sums, the more rapidly the temperature drops, the more the boiler is wasting heat rather than raising steam.  Compare the boiler's rate of heat loss with a thermos flask and the kettle.

I think it well worth insulating the boiler before trying anything else. Wooden strips on top of a layer of felt if the thing is to look good, but for experimental purposes I'd lag it in several layers of loosely wrapped aluminium kitchen foil. Blanket is an alternative but is a fire risk. I'd also start by filling the boiler with hot water from a kettle – if the burner can't keep the water boiling, it's never going to work.

Slightly worrying is what happens if a marginal boiler is asked to run an engine. The engine works by cooling steam, in effect adding a hefty thermal load to the boiler. At that point the flame has to transfer enough extra heat to keep the engine going.

In full size steam they pull every trick in the book to improve heat efficiency.

Dave

 

Edited By SillyOldDuffer on 14/01/2019 11:30:01

[gary arthurParticipant @garyarthur48070]

Uh-oh…

Dave, your message is sobering but important, and so is appreciated.

Funnily enough, I was wondering about this only this morning.

Following Neil's comment above and similar from another member, I already have my eye on this:

https://www.glrkennions.co.uk/boiler-lagging.html

I was going to leave it until later but I think it has just jumped the queue! I was aware that lagging is important, but perhaps not just how important it is. I guess I could just tie it on with wire in the first instance.

On your point about the heat escaping up the chimney – would it be helpful to put a twist of copper down the chimney (or the central fire tube)? I understand that can help sometimes…

I should reiterate that on my only testing on the gas burner thus far it certainly boiled (as it did on meths, though more slowly), and I had no sense that it was running out of steam before I shut it down. It seemed pretty fierce to me when the safety valve blew off, and afterwards. However, the real test will be with an engine, as you suggest.

I have not yet made an engine, but am thinking I should now get started on a simple single-acting oscillator to gain much-needed experience and test the boiler. Again, I was going to leave this until I have developed the boiler further but perhaps again I should shift focus. I have my eye on this version:

http://www.steves-workshop.co.uk/steammodels/simpleoscil/simpleoscil.htm

It's 12 mm bore. My plan was to build it double size but if the viability of the boiler is really in doubt, I'm wondering if I should stick to 12 mm in the first instance. Any thoughts on this question would be most welcome.

 

Edited By gary.a.ayres on 14/01/2019 11:58:28

Edited By gary.a.ayres on 14/01/2019 12:00:53

Edited By gary.a.ayres on 14/01/2019 12:01:39

[SillyOldDufferModerator @sillyoldduffer]

Hi Gary,

It's a good looking boiler and – if you can get enough heat into the water – I'd be amazed if it couldn't run a steves-workshop oscillator – they don't need a lot of puff. I've built a few more elaborate engines and run them on air – quite instructive because of two identical PottyMill engines, one runs freely on 5 psi, whereas the other takes 10. It's the better made version that doesn't work so well – it's a bit stiffer and I think the valve is leaking. Working out exactly whats wrong has so far defeated me!

So far I've been too cowardly to attempt a boiler: I had something in mind very like yours which makes your experience so interesting.

I don't know if adding copper wiring to the tubes will help or not. I know there's an optimum length diameter ratio, and number of tubes for a boiler, but not what it is in a model. What's needed is for the hot gas to be in contact with the tube for the time needed to transfer maximum heat. For full-size boilers it can be calculated. Models don't scale, and experiment is necessary. I'd copy an existing design – the old guys tried all sorts of combinations.

I'm self-taught and clumsy. When attempting stuff, I've found it pays to start with something simple. The less there is to go wrong, the easier it is to find errors! I would stick with the 12mm oscillator design, partly because someone's tested it already, but mainly because it will need much less steam than double size – the volume required rises with the square of the cylinders radius. If 12mm works then try next size up.

No experience of Kennion's lagging. I'm sure it works but it's intended for looks as much as efficiency. If you don't mind about the appearance kitchen foil is a good insulator, cheap and to hand. Wrapping it loosely traps air between the layers and the shiny surface doesn't radiate. More layers the better. Fibre glass loft insulation is OK too. With luck heavy experimental insulation will improve the boiler radically, and you can sort the looks out later.

Good project.

Dave

Edited By SillyOldDuffer on 14/01/2019 12:32:12

[Paul KempParticipant @paulkemp46892]

Gary,

Whilst lagging is important and will have an undoubtable effect on overall rate of steam production it won't make your fire burn any better. Personally I think your experiments have followed the right route so far and if you can boil water and make some steam without lagging then when you fit lagging you can be confident it will boil harder and make more steam. Twisted shim in a tube or two is not a bad idea as it will slow the passage of hot gas through the tube allowing more heat transfer. It's worth bearing in mind that with a traditional loco type boiler the greater proportion of heat transfer to the water takes place as direct radiant / conducted heat from the fire through the firebox sides and crown than from flue gasses through the tubes. Some American design traction engines also had 'wet bottom' fire boxes to give another surface around the fire! Your activities with firing are very interesting to follow, giving some direct practical experience rather than theoretical speculation.

With the engine; why not start with the 12mm bore version and follow up with a 24? I am sure your boiler is well able to run the former and most likely the latter, it might even run both!

Paul.

[gary arthurParticipant @garyarthur48070]

Thank you both, gentlemen.

I feel a bit relieved now

I will prioritise the insulation aspect. Was thinking of using a skin of shiny aluminium sheet instead of wooden strips over the fibreglass insulation, just for a 'different' kind of look, but I agree – cosmetic considerations can be addressed later on.

I think you are right about starting with the 12 mm oscillator. If the boiler does turn out to be a bit of a lame duck, I'd rather have a 'to-scale' minor success than an upscaled failure! And if it runs the 12mm well, then I can always go bigger as you both say. The Pottymill is on my list, as it happens.

Your input is much appreciated

[gary arthurParticipant @garyarthur48070]

This evening I decided to actually try running the boiler rather than just heat it up and gaze at it in stupified awe while it did its thing.



Using the gas burner, I took it up to 50 psi on the gauge. I had the gas turned up a bit higher than last night and it took me 10 minutes to reach 50.



I then opened the steam takeoff valve a bit, resulting in a steady jet of steam which made a narrow strip of paper which I held in front of it flap. The pressure stayed at 50 until I opened the takeoff a bit more, at which point it dropped a little, but it was easy to get it back up again just by restricting the steam out a bit and/or turning up the gas. I went on like this for 20 minutes, with the pressure between 40 and 50 most of the time. At one point it dropped to 30 psi, but that was mainly due to inattention on my part I think. I pumped in more cold water several times and the system recovered quite quickly from that.



That said, the gas was turned up full for most of it, but this didn't seem to do any harm other than to use more gas…



When I get to lagging the boiler it can only get better…



After 20 minutes, I decided to have a fiddle with the steam blower. I was amazed at the dramatic effect it had even with the gas turned up full. The gauge went up fast, and looking up into the bottom of the boiler I could see the flame being sucked up the tubes. I think the blower on this boiler might be useful even with gas.





I'm tempted to be pleased with this, but the one thing I do not yet know is whether or not that jet of steam will drive an engine.



There's only one way to find out…

[duncan webster 1Participant @duncanwebster1]

Posted by Paul Kemp on 14/01/2019 12:44:11:

……..Some American design traction engines also had 'wet bottom' fire boxes to give another surface around the fire! ……..

Webb tried this on the LNWR. When he found ice forming on the bit under the fire he realised he was wasting his time.

If you run it with the burner flat out and the safety valve blowing merrily and measure how much water you have to pump in to keep the level constant for a time, you know how much steam it is making and so how big an engine it will run. Allow a big margin for losses!

I would expect the twisted shim down the tubes t help, they are quite big for their length and so hot gas can get up the middle without ever touching the sides. Don't go mad, start with half a turn and it then try increasing the twist to see if it gets better.

More blower means you can burn more gas, but eventually you can have too much and have excess air which cools it all down again. Another set of experiments, but when you have enough air to be able to have the gas full on seems like a good place to stop.

[gary arthurParticipant @garyarthur48070]

Duncan – thanks for this.

I will try the twisted shim trick, as it may help but can be taken out again if it doesn't.

That, combined with lagging the boiler, might add up to a significant improvement. However, I'm feeling quite optimistic at this point about its performance on gas. I also still have another couple of firing methods to explore using liquid fuel as well as redesigning the firebox and using a blower to try coal again. How successful these will be remains to be seen, but even if this thing only runs on gas it will not be a disaster.

Rather than get too involved in measuring its output and consumption, I now plan to start with the 12 mm oscillator (which will be my first engine) as soon as I have fitted the DRO to my mill, and see how the boiler performs with that under various conditions. Proof of the pudding! If it runs easily I'll go on to make a bigger engine.

[SillyOldDufferModerator @sillyoldduffer]

Posted by gary.a.ayres on 15/01/2019 10:03:34:

…

However, I'm feeling quite optimistic at this point about its performance on gas. I also still have another couple of firing methods to explore using liquid fuel as well as redesigning the firebox and using a blower to try coal again.

…

I agree, but considering the boiler as a machine for converting water to steam it might pay to keep an eye on its limits.

You don't want an inadequate source of heat because that won't raise steam. That's been the problem so far.

On the other hand you don't want excessive heat either. Apart from being wasteful (which probably doesn't matter in this case), it risks overheating the boiler's structure, softening it and in the worst case melting solder or popping the boiler itself. It could ruin the boiler and damage your good self.

Consider what would happen if you used an oxy-acetylene torch as the burner. A gas torch that can cut steel underwater would make short work of a copper boiler's metalwork!

The boiler translates heat at high temperature to useful steam heat at a much lower temperature. As most flame temperatures are high enough to melt copper, it's important that water inside the boiler keeps the structure cool. The water has two jobs – as well as raising steam, it's crucial to keeping the boiler cool. A boiler will go badly wrong if the water inside fails to keep its structure inside safe limits (below say 250C). One cause of locomotive boiler explosions is letting the water level fall below the firebox: with nothing keeping it cool the temperature of the metal under the flame rises rapidly, softens and then bursts. Nasty.

Forcing extra heat into the boiler is OK provided it doesn't cause excessive temperatures. It's far from OK if the extra heat causes any part of the structure to get too hot, and internal overheating may not be obvious. By analogy, you can hold one end of foot length of copper wire in your hand while melting the other in a Bunsen flame. The wire melts because it can't conduct heat away fast enough to keep the temperature from rising locally.

I favour trying insulation first. You might need more heat as well, but I'd try that second. As it's a pressure vessel, albeit a small one, keep a close watch for danger signs.

Keep us posted – I'm intrigued to know more.

Dave

[gary arthurParticipant @garyarthur48070]

Dave –

Again very salient. I appreciate your alerting me to the danger of overheating.

Just to be clear – I'm planning to investigate fuels other than gas not because I think they would give more heat, but because I'd like to have options – as much for aesthetic reasons as anything.

The 'Lixada' camping gas burner certainly seems to deliver enough heat. Whether it delivers enough to risk damaging the boiler (assuming it hasn't boiled dry) I do not know, but yes – it would seem sensible to moderate the flame when possible.

To me, this points to insulating the boiler (as you suggest), trying the twisted shim trick, keeping the gas flame a bit lower and ensuring that the water level is topped up.

It also occurs to me that using a bit of steam blower might help, as it pulls the flame up the tubes rather than just letting it fry the bottom end cap, on the basis that this may allow a similar level of heat transfer with the burner turned down lower (i.e. a better distribution, requiring less heat). Any thoughts on this point would be appreciated.

The boiler has now been fired to steam-raising pressures somewhere in the region of eight times. However, I do not wish to tempt providence, and shall keep an eye on these factors and on the condition of the boiler in general as you suggest.

Will definitely keep updating the thread.

Cheers,

gary

Edited By gary.a.ayres on 15/01/2019 13:22:43

[gary arthurParticipant @garyarthur48070]

While waiting for a couple of items to arrive, I made a start on installling the DRO on my mill in preparation for starting on my first engine (which day draws constantly closer). Fixing the display with its bracket to a convenient storage unit made me feel good, and it looks pretty:

 

Unfortunately, though, it is attached to the mill's axes by nothing at all as yet and so remains decorative for the moment. That said, I did make a start on making the mounting brackets for the glass scales.

Those of you who have been following this thread will know that the Lixada camping stove gas burner seemed to raise steam with the boiler quite effectively. While I will continue to use gas as an option, I am nevertheless in pursuit of a couple of funky alternatives. I received two contenders in the post today:

In the green corner we have an eight-wick kerosene stove from China. It has a catalytic converter/secondary combustion chamber/whatever you want to call it. Although it is not a pressurised unit it vapourises the kerosene and generates a fiendish amount of heat. Unfortunately I took no photos. I did shoot some video but that comes later. It cost less than a tenner, including shipping.

In the blue corner we have a pressurised kerosene stove all the way from India. £22.99 including P&P. It took me a couple of goes to get the hang of it. For those of you who are unfamiliar with these things, it's like an old-school Primus stove – the burner needs to be preheated. In this case I filed the'spirit trough' (hidden in photo by frame of stove) with methylated spirits and ignited it, thereby pre-heating the vapourising tubes and allowing the kerosene burner to kick in under pressure:

This resulted in a seriously hot flame which rivals the gas burner and which I suspect will raise steam effectively:

Assuming these two bad boys raise steam, they will be hacked and modified as final alternative heat sources for the boiler, which will be fun and allow for some creativity. However, I will wait until I try them on the boiler before chopping them up so that if they don't work they can always be used as stoves or repurposed for something else in the future. Either way, no great loss at the price.

Trials with each of these under the boiler soon.

Meanwhile, talking of stoves, be stunned by this guy's amazing skills:

 

 

gary

Edited By gary.a.ayres on 19/01/2019 00:28:46

Edited By gary.a.ayres on 19/01/2019 00:30:11

Edited By gary.a.ayres on 19/01/2019 00:30:59

Edited By gary.a.ayres on 19/01/2019 00:51:44

[gary arthurParticipant @garyarthur48070]

So, this evening I tested the two kerosene stoves:

First

then

The blue Indian pressurising stove emerged as the winner. It's fierce, and almost up there with gas I'd say. It had the gauge up to 50 psi in 12 minutes and the safety valve blowing off in 15. It might do better yet with a bit of burner/boiler distance adjustment. It's also great fun to use and looks fabulous

In contrast, the green 8-wicker didn't even have the needle off the peg in 15 minutes. It's a nice stove of a kind I haven't seen before, and it burns with a very hot flame but a flame of the wrong size and shape. Some fiddling with heights would help, but not enough I reckon. The steam blower made a considerable difference, pulling that soft flame into a neat cone which pushed the pressure up fairly quickly, but this revealed another problem: when the safety valve blew off the flame went out. Not sure why, but it did. That's a problem with this stove because the burner assembly is such that either it or the boiler would have to be removed to relight it. The pressurising one is much easier to relight because the burner is accessible.

It will be very pleasant to use the 8-wick stove to cook a pot of couscous on the patio in France in the Summertime as the barbecue sizzles.

So… thus far the promising contenders are the gas burner and the blue kerosene stove. The square pot stand on the stove will be cut off. I intend to use these two heat sources interchangeably. The idea is to have them both set at the same height so that they can be set in position without doing anything to the boiler. I also aim to make a cool-looking boiler stand and burner supports. However, the proof of the pudding will be in testing the setup out on an engine, so I'd better get on and start building one.

Whether or not the boiler will run on coal assisted by the electric blower remains to be seen, and I intend to have a second go at making a firebox for it. I may do this in parallel with building my first engine, which I shall start once I have the DRO fitted to the mill.

Edited By gary.a.ayres on 20/01/2019 23:40:46

[gary arthurParticipant @garyarthur48070]

The youtube version of the above post:

[Neil WyattModerator @neilwyatt]

Posted by duncan webster on 15/01/2019 00:41:51:

Posted by Paul Kemp on 14/01/2019 12:44:11:

……..Some American design traction engines also had 'wet bottom' fire boxes to give another surface around the fire! ……..

I would expect the twisted shim down the tubes t help, they are quite big for their length and so hot gas can get up the middle without ever touching the sides.

I'm sure someone proved that laminar flow was impossible in 'our' sizes of boiler tube and steam flow rates.

Neil

[gary arthurParticipant @garyarthur48070]

I'm sure someone proved that laminar flow was impossible in 'our' sizes of boiler tube and steam flow rates.

Neil

Certainly if there is a scrunched up bit of metal stuck in the tube to negotiate…

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