I decided to scrap the idea of using my ring burner shown in "part 5" of my conical fermenter series of posts. Instead, I started reading about home-built propane burners for use in small metal-working forges.
These sites were very helpful:
http://www.zoellerforge.com/sidearm.htmlhttp://ronreil.abana.org/design1.shtmlhttp://www.backyardmetalcasting.com/oliverburner1.htmlI decided to follow Mr.Zoeller's design, for which he was kind enough to post a PDF and provide great instructions.
I used an 1/8" NPT brass cap to seal the end of the 1/8" pipe nipple instead of a Tweco Mig tip. I drilled a .035" hole in the center of the brass cap after machining the sides and face smooth.
I used a 3/4" to 3/4" extender as a flare. I cut out the threads on the lathe, leaving a 1:12 taper on the interior surface. I tested the burner briefly before cutting the taper, and I'm not sure how much it really helped. I never tested it without the flare.
This is really a very good design. It can be built from parts found at any hardware store, and it only requires a couple holes to be drilled. The performance seems to be quite good. I do not have any other burners to compare it to, but I am quite pleased. It doesn't like to run at very low pressures. The flame will be drawn back into the tube, and it starts to sputter (as well as heat up the tube). Above 3 or 4 psi, it runs like a champ, and the adjustable air shutter is a critical piece. Without the air shutter, the flame is very lean and might blow itself out. I kept the shutter half-closed, and this seemed to produce a very neutral flame.
I fitted the conical with its valves and added 1 gallon of tap water. The burner is mounted by simply placing it between two short stainless pipes that I welded onto the frame rail. There is currently nothing holding the burner in place except gravity. I'll probably add a pin or strap to prevent the burner from accidentally falling.
Cool!
I achieved a full rolling boil in 20 minutes (1 gallon of water). I started out fairly low with the gas pressure, and gradually increased it, as I saw nothing bad happening.
The wooden crate came from Michaels craft store ($10), and the chain was from Home Depot. I used the chain previously with a come-along winch and had it in my garage already.
Here's a picture of the lid with a thermowell that I made. The thermowell allows a temperature probe to be inserted deep into the tank without exposing the tank to the outside air. It's basically just a long stainless tube that is welded to the underside of the lid and sealed (welded) on the end.
The peltier heating/cooling module is working pretty well despite the copper block soldering mishap. The thermal conductivity is not nearly as good as it should be, but it still seems to work well enough. My original plan was to use two separate peltier modules, but so far, one seems to be sufficient. Without any insulation on the tank, the device held a 15*F difference from ambient temperature, so this project may not even need much insulation.
The temperature setpoint is 67*F. For actual beer brewing, I'm thinking 64*F will be the target ale brewing temperature. So far, I am just using proportional control with a very high proportional constant. The tank has so much volume, and the heating/cooling power of the peltier is relatively tiny, so there isn't much tendency to oscillate.
I tried to adapt this technique where the glass was moved and the part was stationary. It didn't work. The part ended up very smooth, but not flat. It's too difficult (apparently) to hold the glass at the same exact orientation for every stroke. I ended up mounting the part back in the mill and using a wide diameter end mill to flatten and smooth the surface in one pass.
I used a 3/4" to 3/4" extender as a flare. I cut out the threads on the lathe, leaving a 1:12 taper on the interior surface. I tested the burner briefly before cutting the taper, and I'm not sure how much it really helped. I never tested it without the flare.
This is really a very good design. It can be built from parts found at any hardware store, and it only requires a couple holes to be drilled. The performance seems to be quite good. I do not have any other burners to compare it to, but I am quite pleased. It doesn't like to run at very low pressures. The flame will be drawn back into the tube, and it starts to sputter (as well as heat up the tube). Above 3 or 4 psi, it runs like a champ, and the adjustable air shutter is a critical piece. Without the air shutter, the flame is very lean and might blow itself out. I kept the shutter half-closed, and this seemed to produce a very neutral flame.
I fitted the conical with its valves and added 1 gallon of tap water. The burner is mounted by simply placing it between two short stainless pipes that I welded onto the frame rail. There is currently nothing holding the burner in place except gravity. I'll probably add a pin or strap to prevent the burner from accidentally falling.
Cool!
I achieved a full rolling boil in 20 minutes (1 gallon of water). I started out fairly low with the gas pressure, and gradually increased it, as I saw nothing bad happening.
The yellow tips on the flames show that there is a lot of excess fuel. The flames are jumping off the burners probably because the mixture is too rich to start combustion inside the burner tube.
