Small Gas Poker Burner

[PomyMark]

Hi,

very nice would like to know more about the burner

The burner was designed many years ago and a lot have been made. They are designed to work in a quite small tube in this case the flue tube has an ID of 13.5mm (large1/2") the OD of the poker with mesh atached is about 8mm so there isn't much of a combustion space. So the flame needs to be low in height and preferrable wide. The burner itself is designed to have interchangable pokers that can have different numbers of slots of different shapes. The burner will work if necessary with no secondary air or it can be put under a pot boiler. As I make mostly model railway steam locomotives the plug of the burners being built will have a flame viewing hole drilled in the plug. This done because being slightly deaf and operating in often noisy exhibitions it is with the aid of a dental mirror to see if the flame on the burner is lit. Once the gas/air mix is correct it is possible to change pokers for different boilers this often done with my test burner shown up until now in the photographs. This test rig is used to check out locomotives when they are nearly finished without the compllcation of using their own gas burner systems. Or if it is a new design what type of burner will be needed. Now as it has been seen it was used to help design a burner. I hope to describe the construction of the remaining parts of the burner in this thread. If anything so far described isn't clear please ask.

Regards Tony.

Hi tony have to make one for a boiler I have do you have any more details on how you did the gas jet

 

[PomyMark]

Hi,

very nice would like to know more about the burner

The burner was designed many years ago and a lot have been made. They are designed to work in a quite small tube in this case the flue tube has an ID of 13.5mm (large1/2") the OD of the poker with mesh atached is about 8mm so there isn't much of a combustion space. So the flame needs to be low in height and preferrable wide. The burner itself is designed to have interchangable pokers that can have different numbers of slots of different shapes. The burner will work if necessary with no secondary air or it can be put under a pot boiler. As I make mostly model railway steam locomotives the plug of the burners being built will have a flame viewing hole drilled in the plug. This done because being slightly deaf and operating in often noisy exhibitions it is with the aid of a dental mirror to see if the flame on the burner is lit. Once the gas/air mix is correct it is possible to change pokers for different boilers this often done with my test burner shown up until now in the photographs. This test rig is used to check out locomotives when they are nearly finished without the compllcation of using their own gas burner systems. Or if it is a new design what type of burner will be needed. Now as it has been seen it was used to help design a burner. I hope to describe the construction of the remaining parts of the burner in this thread. If anything so far described isn't clear please ask.

Regards Tony.

Hi tony have to make one for a boiler I have do you have any more details on how you did the gas jet

 

[Tony Bird]

Hi Mark,

Do you have any more details on how you did the gas jet?

Not sure what you mean. The burners shown are using a commercially made gas jet No.3 which I think has a 0.15 mm hole, when designing a new burner I start with the smallest which is a No.3 and work my way up in size until I am happy with the results. Hopefully this might be the answer if not expand the question and I will do my best to answer. In the attached video the small model locomotives that are running a little fast use the burner described in the thread.



Take care.

Tony.

 

[PomyMark]

That is what I was after did you get that from Bunnings

 

[Tony Bird]

Hi Mark,

That is what I was after did you get that from Bunning.

Sorry I don't know who Bunning is, are they in the UK? I probably got the jet from 'Chuffed to Bits' a steam model supplier here.

Take care.

Tony.

 

[PomyMark]

Sorry I thought you was in Australia

 

[rickhann]

I am coming into this discussion a bit late, but I may be able to add a bit. I worked for several years developing a propane burner for my 3-1/2" Rob Roy. I found a spread sheet calculator that calculated BTU output for a burner by entering orifice size, gas pressure, & orifice coefficient. It can be found @ https://ronreil.abana.org/BTU_Calculator.xls You must download and open the file. As for burner jets, I use misting nozzles. They are cheap. You can get 20 for $10 on eBay (.3mm/.024"). If you need smaller ones, aeromist.com has smaller ones (.008" and .012") for a couple dollars each. If you have a set of number drills, you can modify existing opening to whatever size you need. Have fun playing with the BTU calculator. Hope this adds to the discussion.
Rick

 

[peter2uat]

When we got our new cooking hob (for natural gas) there was a extra small bag with four no. 3 nozzles included - they are for propane gas - perfect for the next boiler. Thread is M6x0.75. I think most people just throw them away as those nozzles are of no use for them. Just ask around when someone gets his new kitchen...

 

[Steamchick]

Hi All,
I'm curious about the burners you make for these little locos. Personally, I am not a G1 enthusiast so have no locos. But I have made many ceramic burners and a few "blow-torch" type burners, and a couple of pipe burners. In terms of the theory, there seems to be a total lack of it everywhere, but having scoured the interweb found some papers from neraly 100 years ago - which do a lot of empirical analysis and develop some odd general rules for burners. (I like theory - if I can find something I understand!).
I have seen the various web discussions about pipe burners - and the mertits of radiant heating by use of a gauze "tent" - or other description for a gauze in the hot part of the flame.
A few "standards" I find useful, that may help anyone here.

1. The amount of gas you can push into a burner is dictated by the jet size. There is a finit limit for all jets: Below that limit the amount of gas varies with the square root of pressure, (4 times pressure = double gas). But at the limit (Sonic gas velocity at the jet) you can't get any more gas - the jet cannot pass "super-sonic" gas - no matter how much more pressure is applied. Fortunately, that rarely occurs for G1 burners I guess?
2. The amount of "fire" you can push into a boiler is determined by the "exhaust volume - and pressure difference to push it". This is difficult to explain, but here goes: For a particular burner and boiler, there is a point where the "fire you push into the boiler" is more than the boiler can take, so it comes back out of the burner hole. (happens on a friend's boiler - with cross-tubes). The way to increase the amount of flame you can stuff into the boiler, is straightforward - assuming you can't increase the cross-sectional area of the "restriction" in the gas flow: (I fitted a bigger chimney on a stationary boiler to allow the use of a bigger burner) - and assuming the blower has been tried to maximum, or engine exhaust blow up the chimney is optimised to the best. The answer is to cool the flame after combustion. The use of a radiant element actually does that. On a 1kW burner, as much as 80% of the heat can be removed as radiant energy - and if you think of this as being like a light bulb - everywhere the radiant can shine will absorb heat - hopefully most radiant heat will shine on the boiler walls and make steam.The cooler gas from the rsidual flames will still pass more heat by conduction to the boiler surfaces, but the gas volume will be smaller, thus reducing the back pressure of getting the gas through the flue tubes.
3. Ceramics - for durability - need to be quite thick, to avoid overheating the underside of the burner ceramic and causing flash-back when the flame goes inside the burner. (VERY BAD!). So I ensure I have 12 mm of ceramic, 8mm space beneath the ceramic and 10 mm over the ceramic (for flames to complete combustion). so find a ceramic is no good in small tubes - less than 30 mm diameter. The pother issue is that the flat surface of the ceramic prohibits the use of all-round burning and heating inside a fire tube.
4. On tests with my Cornish stationary boiler (with a 2inch firetube) I found I could happliy use a no 8 jet on a single sided ceramic. But a blowlamp burner would take a 12 jet (double the gas) so tried a "double sided" ceramic burner. But there wasn't enough space to get the gas-air mixing chamber inside, as well as 2 thicknesses of ceramic, and enough space outside the burner for flames and exhaust. This also became limited to a no 8 jet.
5. I made a radial poker-style burner - but the volume of flame limited me to less than a no 8 jet.
6. I tried the blow-lamp burner with a cylinder of wire wool inside 2 tubes of wire mesh - This made a full length radiant burner that took a 12 jet and full pressure with no problems. I think I can even use propane at a higher pressure as the flame is so small (exhaust gas volume) when it leaves the wire wool tube.
7. SO I recommend you try the radiant gauze "tent" over your poker burners, as explained in the Southern Trains stuff - and other chat rooms.

Here endeth my "science lesson"for today.
Happy steaming chaps!
K2

 

[Steamchick]

Here's a picture or 2 of flue tube burners in a Cornish boiler.
90mm x 10 mm ceramic with 8 jet.

10 x 130 mm with additional radiant coils :

But I decided the Blowlamp burner with surrounding wire wool really increased the power significantly, so that's what I'll run. It takes twice the jet size - so double the gas power - and the radiant is very effective. (but looks scruffy!).

Blow-lamp + wire wool tube in mesh:

Note: The flame - which wpould extend beyond the wire mesh - is cooled by the radiant so effectively it does not exceed the firetube and I can effectively push much more gas combustion into the firetube. All the heat comes out of the burned gas inside the boiler: Mostly as radiant heat into firetube walls - and the rest as hot exhaust for the flue tubes. Maximising the heat exchange by using a lot of radiant increases the performance of the system.

Happy steaming!
K2