Spiritburners

Can anyone help with getting spirit burners to produce more heat.

Thanks

Matt

what sort of spirit burners!

Martin P

Six 3/8" wicks using meths as the spirit.

Do they burn with a good flame?

What configuration are the wicks in?

What are you heating?

Mick

Hello Brian/Mick

Please see attached photo.

It's heating a 2.5" gauge loco , configuration is two rows of three.

Thanks

Matthew

A 'Rose' by any other name....

IanT

I don't run meths fired engines Matt - but I understand that some experimentation can be required to get the wick type, fuel feed and size/type of flame just right.

The kind of wick material used, its height, how tightly it's packed and the fuel feeding system are all parameters to be considered. I haven't looked closely at this design but LBSC used to recommend a 'chicken feed' system and I believe that one of the advantages is that it let's you lower the wick 'height' to allow more space between flame and the water tubes being heated - so better combustion & heat I assume.

I'm sure there are others here with more direct hands on experience of meths firing though and I'm sure they can advise you.

Good luck with your new engine -- a nice G3 project.

Regards,

IanT

Edited By IanT on 06/08/2017 10:09:47

There are a number of things to consider with meths (spirit) burners.

1) The size of the flame is directly proportional to the size (diameter) of the wick. Bigger wick = bigger flame. Cotton wick material is available in a huge variety of diameters from sellers of oil lamps. But you MUST extinguish the flame before all the fuel is used up otherwise the wick will burn away and need replacing. Fireproof wicks can be made from glassfibre rope or #400 stainless steel mesh. The wick should not be packed too tightly into the burner tube as this will impede capillary action preventing enough fuel being drawn up to burn.

2) The fuel in the tank (which requires a vent hole) must be no higher than the top of the burner tubes. (Unless it's a "chicken feed" burner.) Overfilling a fuel tank is a Viking funeral waiting to happen...

3) Meths burners produce soot. Lots and lots of soot.

4) With the wick type meths burner the flame is very susceptible to being blown around by even the slightest breeze. This is not too big a problem for those who run stationary engines indoors but can be for running a mobile steam engine outdoors.

Aside from historical authenticity there is no reason to use a meths burner when gas burner systems, and the parts for them, are readily available. The advantages of gas are that the flame does not get blown around by a breeze and so goes where it is needed - to heat the boiler. Also, when correctly set up the burner produces no soot and the flame is controllable. Contact Phil at Forest Classics to discuss your requirements - **LINK**

A spirit burner should not produce too much soot, if you try using kerosene/parafin in a similar type of burner then you will get soot. After all that, the meths available today has a fairly high water content, about 10% in UK, and this can cause a yellow flame which will be a bit dirty.

I'v not tried it, but some recommend 99% isopropyl alcohol, not rubbing alcohol which has up to 30% water.

Ian S C

Edited By Ian S C on 06/08/2017 12:02:12

I am very keen on spirit firing although no expert. I have some experience with a Smithies boiler fired with meths. Most points have already been mentioned by other contributors but I would recommend carbon fibre/fibreglass wicks packed quite loosely in the tubes with the top of the wicks about 1/2" above the top of the tubes and about 1"+ below the bottom of the inner boiler. That is a guide and some experimentation may be necessary. The flames must play on the bottom of the inner boiler tube and the flame route through to the smokebox must be clear. If there is a lot of insulation in there it will strangle the flames. Sometimes too much insulation has been packed in with a view to protecting the paintwork of the outer barrel. It does protect the paint but the loco will not steam. I use "ordinary" meths and find it well up to the job. Having said that, meths is hygroscopic and if old may have absorbed quite a lot of water from the atmosphere.....not good. Make sure also that the blastpipe is correctly positioned so that it conforms to the 1 in 6 rule. I have had no problems with soot. You may wish to experiment also with the amount of air being admitted from below and around the burner tubes. Too little air and you will have incomplete combustion and diabolical fumes which are nicknamed "poison gas". Too much cold air coming up beneath and around the burner tubes will have an adverse cooling effect.

Mick

A further thought....are you using a fan down the chimney to get steam up?

Mick

Hi all

I thought I had posted at least two reply's to people's suggestions. But now I look there not there. So here I go again,

I built Rose to the words and music as they say, having had no experience of spirit burners before I just expected it to work. It has the chicken feed system in the tender which worked well once I got the tank airtight. The burner seemed very prone to the slightest breeze and when I tried the blower the pressure dropped back drastically like it was drawing too much air. I have used glass fibre for the wicks but may have it too tight. As for 1/2"" above the burner tube and 1" below the barrel for the wick, I don't think there is room. As for soot this dose not seem to be a problem.

Regards

Matthew

For the little spirit burners that I have on some of my hot air motors I use iron florists wire, its about 24/26 swg(have not measured it), this works well as a wick. This one has a wick tube 1/8" diameter.

Ian S C

A few further thoughts Matthew........far be it for me to criticise a design by LBSC, but I would like to see the firebox extended down to about 1/2" below the tops of the burner tubes. My reasoning is that there is quite a lot of space between the frames of your loco, both side to side and front to rear. This is why the flames are so susceptible to draughts and the vagaries of the wind. Even in Gauge 1 , where the frames are only 1 1/4" apart, I find it necessary to provide a shroud for the flames. If the shroud cannot be incorporated in the actual boiler or in your case the outer boiler tube design I would consider bending up a rectangular shroud from a piece of thin brass or whatever, which extends to about 1/2" above the bottoms of the burner tubes and about 1/2" above the tops of the burner tubes or until it extends into the firebox by about 1/2". Finding a means of attachment may be fiddly but not impossible. This will protect the flames and direct them to the base of the inner boiler tube instead of being wafted around in the breeze. Experiment also with the amount of air being sucked in past the burner by temporarily blocking with something like ceramic fibre or other non flam material. Again, fiddly but worthwhile getting the air/fuel ratio correct. Have another look at the burner assembly and experiment to see whether you can increase the distance between the top of the wicks and the bottom of the boiler. I would not be at all happy unless this was a minimum of 3/4". Preferably by bending the spirit supply pipework although drastically by removing some of the tops of the tubes by small increments. 

Mick

Edited By mick H on 07/08/2017 09:10:41

The other point to consider is prevention of heat loss from the boiler shell by really good insulation.

And an absolutely perfect steam system, no leaks from unions, piston rods, or across valve faces.

You do not have any 'spare' heat to lose.

France is the cheapest place to buy your firing liquid, next time you cross the channel.

The quality of the meths has been questioned before. It does seem to vary, mostly downwards. Have you tried a different brand/ supplier ?

Hi Matthew. I run the G1MRA Surrey Group and nearly all of my engines are meths fired, including several LBSC designs.

A few points.

1. Meths can indeed be of very variable quality, especially if somebody has left the cap off since it is hygroscopic.

Most of my group use B&Q bioethanol which is sold for flame effect fires. As well as being very good quality, it is typically cheaper than most DIY available meths. Sometimes it is hard to find in store - just ask. I know the name is odd. It's not as though the ethanol in meths isn't bio in origin...

If you really want a fierce fire, then some folk like isopropanol. This makes my engines a bit too frisky so personally I stick to bioethnol.

2. Your observed loss of pressure when the blower is opened is more likely to be lack of water in the boiler than a problem with the drafting arrangements. When there is only a small amount of water inside you could still get a high registered pressure on the guage, but as soon as you take some of the steam off there isn't enough thermal mass of boiling water to replace it. On the other hand, completely filling the boiler is bad too because that leaves little steam space and will lead to priming (water in the cylinders).

For a new engine that you haven't yet got experience of running, I suggest you take the safety valve out and invert the boiler with the blower open so that it completely drains. Then use a syringe and water to fill it up completely so that you can see the top of the water in the safety valve, keeping a note of the volume of water you've put in. Now drain again, close the blower and half-fill the boiler.

3. The recomendation to use glass fibre wicks is optimistic, in my experience. Glass softens at the sort of temperatures you'll get in a meths fire box, and the ends will fuse into blobs at which point the wicking action is inhibited. The best wick material available at the moment is probably ceramic fibre. This stuff is used for very high temperature insulation but is hard to get hold of. Some folk like cabon fibre. If you contact me privately me I will send you some of my ceramic fibre. Cotton wicks are pretty much useless in high performance engines as they char away so quickly. Traditionally asbestos was used: if you have an old engine with odd looking wicks in it then I would dispoase of them carefully.

4. For most 'internally fired' meths engines, including Smithies boilers, you initially need a small suction fan to draw the combusting gases through the tubes (or through the outer shell for a Smithies). Once the boiler gets a bit of pressure up you can crack open the blower (don't open it too wide and lose all your pressure!) and the entrained air will do the job instead. If you don't use a blower, the meths flames often will just billow about under the engine, which is a hazard to paint and fingers and theormdynamically hopeless too. Some engines will, on a calm day, eventually get up to pressure without a fan - I have an LBSC Chingford express which can get going without a fan as I discovered one day when I was testing a burner and hadn't fully extinguished it...

5. I've never encountered problems with soot in G1 meths engines. Now, coal fired G1 engines are another story and need very careful cleaning after a run. However, the smokebox doors of my meths engines are rarely opened, and I've never cleaned the tubes of a meths engine.

6. If this is a new build engine, pay very careful attention to sealing the smokebox to the boiler barrel, and also to sealing the entry of the exhaust and blower jets into the smokebox. The 'entrainment' effect depends on there being essentially only one way for air to get out of a smokebox, and that's up the chimney. Most of us use bathroom sealant to give airtight seals.

Of course, you also need to make sure that the firebox door has a good seal too - I see you diagram requires a 'tight fit'

7. Check the positioning of your exhaust and blower jets. The normal way to do this is to fill the boiler with water, attach a compressor (or even just a bike bump) in place of the safety valve and open the blower or turn the wheels. You should get small jets of water shooting out of the centre of the chimney orifice. If the jets are off centre or colliding with the chimney tube then you need to bend the exhaust/blower connections at the bottom so as to get good alignment.

Adrian

Edited By Adrian Johnstone on 07/08/2017 13:10:05

Edited By Adrian Johnstone on 07/08/2017 13:10:42

Edited By Adrian Johnstone on 07/08/2017 13:12:50