I've built a version of the Reil burner based on a drawing by Rupert Wnig.
Mine uses a 1.4" i.d. SS burner tube and 2 to 1-1/4 reducer coupling and
Tweco tips. For my version I built a butterfly choke out of a short piece of
2" SS nipple. Initial open air test burns show that the thing lights and
runs and I can get reasonable flame control with the choke although I can't
get the nice symmetrical and consistent flares that Reil shows on his site.
I am surprised, too, that even with 15-20 psi gas pressure the burner like
alot of choke, i.e. nearly closed. My question is this. How do you select
the tip or jet size. With a .8mm tip the burner sometimes wanted to burn
inside the burner tube which I know is probably because the tip was too
small. I tried one drilled out to .055" and another drilled out to .065" and
this moved the flame out to the end of my burner tube. But, how do you
optimize the jet size? I've thoroughly researched the Reil site (a bit
difficult to navigate) but couldn't find any advice on this. Others say that
they started small and worked their way up but how do you know when you're
there? Strangely, too, I tried a few nozzle flares that I machined, and get
about the same results with or without them in open air. I still haven't
made the perfect one yet though with the theoretical 2 x i.d. length and
1:12 taper.
I built one pretty much copying Brian Booorman's design at
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. The only thing I did different was
my reducer bell was 1 1/4 at the wide end (I couldn't find one that went to
1.5 in) and I didn't attach the nipple at the back where you would use a
choke (I don't have a choke of any kind). And I'm pretty sure I drilled a
#60 hole (I don't know the actual diameter in inches or mm) and left it at
that. You said you couldn't get the "nice symmetrical and consistent flares
that Reil shows," if you mean the flame isn't even, make sure the jet is in
the center of the pipe and pointed straight down it. I also had to move my
flared nozzle in and out to find the best place to put it. I don't know how
my burner runs as far at efficiency and I'm not real sure how rich/lean it
burns, but its hot and clean enough to forge weld steel, so it's good enough
for me.
-Will
My experience is that tip size only determines mixture. If you have too
large an orifice for your venturi, even with the choke fully open you'll
never even get it neutral. (Mind this is affected by the flare, which adds
a bit of back pressure. A short flare will burn much leaner than a proper
one.) Too small an orifice and velocity will be slow because the intake
will be so choked off with respect to the diameter of the burner tube.
A good flame is a short inner cone of blue color. Not a lazy green (or
worse yet, yellow tip due to carbon burning) flame, which is too rich. A
thin purple flame is lean, with a good burner you can push it very lean
indeed without it blowing out. Others, particularly with bad flares or none
at all, have a certain flame velocity and mixture limit: an open-end pipe
can be used as a burner for very slow flames, and it can burn neutral. The
low flame velocity is unstable and it might start fwooping. If it fwoops
once too hard, the flame will kick up in the tube and burn near the intake
(no good). At higher gas pressure, you have to reduce air flow (choke) to
keep velocity down, otherwise the flame will blow off. So you add a flare,
and suddenly this little pressure step at the end allows burning at very
high velocities, even fully lean. The technical name is a flame holder, and
if it's not holding the flame (at the shoulder formed between the end of the
burner tube and the flare), you can know right there it's not burning right.
I suspect you could've done as well with the smaller tip, just at higher
pressure and more choke. This boosts up the velocity, while giving more
lean headroom (if you need an oxidizing atmosphere or extra flame
temperature). It also reduces maximum power, as only so much propane is
coming in.
Try. Typical sizes are #57 for a 1" pipe, .030 for 3/4", .022" for 1/2"
conduit (no venturi needed), etc. I'd guess 1/16" for 1 1/2" pipe.
Bah, I've never made a proper flare in my life. I just bend some sheetmetal
(24ga. works good) around a size smaller pipe then spring this on the burner
tube. No taper, the step between inside of burner tube and flare (i.e.,
pipe thickness) holds the flame. (BTW, a perfectly smooth burner tube
doesn't work. It needs the abrupt step.) I let it hang out about i.d. past
the end. I'd never go with 2 x i.d., with a taper I suppose it might work
but it's just too much hot sheetmetal. Wasteful of the heat and whatnot.
However, anything shorter than i.d. will be unstable, burn extra lean, etc.
Make sure it's easy to replace, it WILL turn to scale in half an hour,
particularly if you're melting bronze or something.
Note: no flare is necessary if your furnace/forge's tuyere is a tight fit to
the burner tube.
Tim
--
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
Website @
Thanks for the thorough response. I had not picked up on the fact in my own
reading that when properly working the flame actually burns inside the flare
just off the "step" formed by the wall of the burner tube and the body of
the flare. I (and a few others whose results I have been studying) have been
trying to get the flame out of the burner tube and the flare.
Yeah, there are three modes of burning:
1. Back in the burner tube. It has a pulsating sound. Heats up the burner
tube and generally burns bad.... no good.
2. After the shoulder, as mentioned. This is normal operation, and has a
good loud burning sound.
3. After the flare. Mixture is too rich to burn at the shoulder, so burns
at the first sight of more air, namely at the end of the flare.
You're welcome. :)
Tim
--
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
Website @
I to have a through the large end of the reducer two holes for the gas line.
Is the flame tip end flared ? This is important to keep it alive. Not to much,
but an obvious flair helps. Once the furnace is hot the flame can't go out.
While
cold it can be tough.
Martin
Will wrote:
Got it working. I settled on a Tweco drilled/reamed out to .063". This was
the max size for a neutral flame at 25 psi with the choke fully open on my
design. I made just a simple flare as you suggested - just a 2" length of
slip-over SS pipe. The thing really roars and now wants all the air my choke
can give it above 25 psi. It now runs consistently with control of the choke
from a few psi all the way up to 35 psi. It does burn inside the flare now
which gets red hot but the burner pipe stays cool. Next step is to ram the
refractory in my completed furnace shell.
I've built several Reil burners, and find the following details useful:
Fuel gas is 1/8 inch pipe size, with a tee in the middle of the reducer
bell. Both ends project through the bell; one end is capped and the other
end connects to a 1/8 inch needle valve and then the supply hose. The nozzle
is a 1/8 inch solid steel plug with a drilled orifice. Easy to change
orifice sizes by switching plugs. Number 57-58-59 drill sizes seem to be ok
for 1-1/2 inch pipe size - you can experiment until the flame looks good.
Obviously, gas pressure affects this size. I find that 15 to 10 psi propane
is ok for me. Dave
.
Why 35psi.? I can melt cast iron with the Wenig Monster Burner using
20 to 22 psi of propane. Up to a certain point I think the more fuel
and air you pour to it it goes out the exhaust vent and does little
too improve melt times, as its going by too fast to be readily
absorbed and radiated back to the crucible to do much good. IMHO
Ruperts Monster burner is the best designed burner, its economical and
works great.
Visit my website:
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expressed are those of my wife,
I had no input whatsoever.
Remove "nospam" from email addy.
Also note that open air testing is not a good indication of proper
burner operation. I have seen burners that would not burn in open air
do just fine in the furnace.
Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA
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The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
And some furnaces don't burn right without the crucible in place. Ideally
you should be capable of all three. :)
Tim
--
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
Website @
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