propane question

[Bill Shields]

ah..well the original idea works but has a minor drawback. (not original with me...saw it somewhere from the UK or old miniature locomotive magazine)

basically, a pressure regulator that monitors the pressure going into the steam chests control an extra blower line. as steam pressure drops going into the steam chest, the blast nozzle slowly opens up.

the idea works, but there is a 'time lag' due to the nature of the o-ring balance piston concept I used....close the throttle SLOWLY and all works well. slam the throttle closed and the system does not have time to react...and flame comes out of where you don't want it.

reducing the 'sticktion' of the o-ring helped, but after a while the system became a maintenance nightmare...so I stepped back and run with the draft valve cracked just slightly...it is a balancing act.

My current camelback has the same system....and the same problem(s)...not quite as bad (larger system)..but still there.

I intended to try a mechanical valve (rather than a pressure balanced) to open and close the draft line....but again...was a lot of work...so now I just run with the draft cracked there also.

[NP317]

I follow prototype oil-burning practice when firing my propane-fueled steamers:
I leave the stack blower "cracked open" all the time to produce a "baseline" draft, and add more blower when necessary.
Mostly, I coordinate the propane firing valve proportionally to throttle use.
In an "emergency" I can reduce propane pressure as fast as I can shut the throttle. Both are easily accessible.

You can see the red bar handle of the propane firing valve in the attached photo, just to the left of the firebox door and rising up from the cab floor (foot plate).
Right hand on the throttle, left hand on that firing valve.
I tend to lay out those controls as they are found in full-sized locomotives. Old habit.
RussN

[Chris Hollands]

I've added a second blower valve that is always open so if you turn off the main valve there is always some form of draft , the second valve is 3/16 to 3mm tube about 1/16 id that cannot be reached unless you remove a cover so no one can turn it off by accident .
I suppose the the flip side of the coin you may have to juggle slight draft against gas supply and boiler pressure , but hopefully no flames up the side of the boiler and cab - that's the theory anyway .

[Greg_Lewis]

Thanks, Bill. I couldn't figure out how that might work. Good ideas, Russ and Chris.

[Bill Shields]

you are correct...in that you need to adjust the 'fixed' blower as a function of boiler pressure.

having this valve (at least for my setup) covered would be annoying since I am always having to 'adjust' it as the boiler pressure goes up and down..

[FLSTEAM]

My blower is controlled thru a pressure regulator. Blower never changes no mater what the boiler pressure is.

JB

[Bill Shields]

that is what I was looking for...but in conjunction with throttle setting

[cbrew]

My blower is controlled thru a pressure regulator. Blower never changes no mater what the boiler pressure is.

JB

are you using an off the shelf regulator?

[FLSTEAM]

My original regulator was a McMaster mini regulator (air). It worked fine except it needed steam oil every run.
The replacement is a Clippard MAR-1BPK-3-V. The 3 is the spring range and the V is for viton rings. They are not off the shelf but only take a week to 10 days to order. They work perfect. I also used one for the atomizer when burning oil.

PS, My neighbor has two and maybe interested in selling one.

JB

[Bill Shields]

regulators with steam....especially when condensate (CRUD) can form behind the piston...can be problematic...

hence the manual valve...

[Drprez]

Well I created a hybrid design to my burners.

I added 3 square tubes for mounting the burners then I have got the burners from Titan CO2 generator machines. You get 4 for $20 it’s a great deal. Anyway, in between I mounted 1/2 size (1” tall) jets they don’t go high because of the tube length.

On top of that is a brass plate to limit where air comes in. When I did it first it was tight around each one of the nozzles but soon as I begin to move the locomotive vacuum from the exhaust steam would cause the flame out.

So it was simple redesign I ended up making three-quarter inch hole

around each one of the 4 rose burners only the rest stayed tight and then I took a grommet upside down mounted because it has a curved architecture to which helped deflect the air into and air around the fire box.

Key is about 90% of the air comes through the burners themselves.

Here it is but the grommets on the rose caps are not on I had them off.

I also added a spark generator starter which helps get everything going.

Above that about 3 inches is a steel hole punched plate. This does 2 things it helps with complete combustion of hydrocarbons because once the firebox gets hard this turns red hot which helps when in motion to do the combustion and secondly it helps also because above it I put ceramic biscuits which heat up.

The biscuits simulate as if it was coal when it’s moving and you do have more consistent heat.

Above thst I have an arch that goes from the front of my fire box all the way to the back of my firebox just about 3/4 of an inch from the end and about a quarter inch from the top works great.

Each one of the boiler tubes Are spiral stainless steel strips which help disrupt air flow and slow it down through the boiler to help increase the heating transfer.

With this design it takes about 18 minutes to bring the boiler to begin to make some pressurize steam. it then maintains the heat very well and is a good even burn and consistent. I also noticed I don’t go through too much fuel. calculation of the total BTUs are

Here is a link to a Calculator for how much water volume will be using when you’re steaming Based on conditions

http://www.smex.net.au/Reference/AxlePump01.php

It works well for some detailed steam rates.

[tornitore45]

FWIW Pressure depends on temperature and the propane mix composition
Same brand - Same temperature - same pressure