Oil furnace build

[dallen]

on the burner the center line is for compressed air and the small line that hooks to the side of the nozzle adapter is for waste oil or fuel oil. you really don't need the spin vane that is on the nozzle but you do need some way to center it in the tube.

I'm being a little slow with getting a video up of how I operate my burner for you, its been pretty hot here lately, anyway the humidity is high enough to wring water out of the shade but I will get around to it.

you will need a regulator that can pass a pretty high volume of gas.

[Pete O]

It works! I love it when a plan comes together.
   

I got a brainstorm for as very simple air control valve, bought a little ball valve and brazed it into the oil feed line to control oil flow, inserted a LPG feed line using a BBQ regulator and compressed air fittings, put it all together and the thing roars.

The air feed valve is a 75mm Y connector that slides along the pipe, the hose clamp provides just enough friction for it to stay where it is put. I shaped the end of the air pipe so it closes off the waste port when the Y-piece is slid all the way on. With my leaf blower at idle, it provides enough air for full heat and the valve enables adjustment during starting.

   

   

   

The LPG inlet is an offcut from the oil feed pipe (truck air pipe). It extends about 3" into the air pipe with a bend to direct the gas downstream. I adjusted the BBQ regulator until it was giving a good burn for warming up.
I know my brazing looks crap, I used some coated rods I bought at a farm clearing sale about 5 years ago, don't even know what they are!

   

I had to run it on LPG for about 10 minutes to get it hot enough to start the oil, then needed to give it a burst of LPG a few times along with the oil to get it really going. Once it was warmed up and the preheater was firing well, it roared like a jet engine.

   

For initial startup I put my oxy-acetylene torch in the tap hole to get the LPG burning. I need to come up with some better ignition solution than this as I want to run the furnace on a different part of my property, away from the shed where the oxy set lives. Unfortunately my little propane torch just gets blown out by the air pressure even at the lowest air flow. I'm open to suggestions for an ignition system, I'm thinking about some sort of spark ignition, like inserting a spark plug up through the tap hole, but I need some portable way to generate the spark.

Anyway this was an absolute hoot finally getting this thing burning under full control. Thanks to those who have offered advice and suggestions.
I still need to make some tools- I've made a pair of tongs for lifting the crucible but nothing for pouring, also of course I think the moulding equipment will be a major project in itself.
So, still a little while before I'm actually pouring metal, but this put a smile on my face.

[dallen]

put some oil on a rag light it and throw in in the furnace then turn on the air, then  turn on the gas slowly until it lights after turning on the oil and making sure its not going to go out close the lid,

IF IT GOES OUT, shut off all fuel and let the blower run for a minute or two to purge any flammable vapors from the furnace before trying to relight it. This is standard precaution for any burner, and yes I've blowed the lid open on mine a couple  times. 

A Rag soaked in some oil on a wire if you think it may blow out and set the grass on fire is all it takes.

[DaveH]

Pete,
Excellent   
 
DavwH

[Mayhem]

Nice work Pete

[Pete O]

I have been making some more progress on the furnace, only thirteen and a half months on from my last post.
I've been working on my first actual pattern to cast a real part, so needed to bring the furnace up the priority list.

I did a test run not long after the last post on here, where I actually melted some aluminium scrap and poured some ingots. The furnace floor did not stand up to that burn very well, it was a mix of vermiculite and fire cement, the surface eroded badly and was not flat enough to stand the crucible upright. I broke the base out and re-cast it with my leftover castable refractory, did this before our trip to the UK in August so it has had time to cure.

The leaf blower was clearly unsatisfactory for an air supply; I've been looking out on auction sites for one of those jumping-castle blowers but have not spotted any near me. A mate has been clearing out his dad's shed and found this blower unit that was used to keep a domed swiming pool cover inflated.
   
The size might not be apparent from the photo, that inlet port is 12" diameter. One more bulky item to find a home for.
   

It was just the bare fan and housing, I had to build the plywood outlet business as well as adding a motor and mounting frame. I used a 3hp 3-phase motor that I had spare, with a VFD that used to be on my lathe. I'm thinking I'll use the VFD to establish the ideal running speed for the blower, then fit a single-phase motor with appropriate pulleys to get the desired speed. I got to use the shaper for cutting the keyway in an aluminium pulley for the blower, worked a treat.

   

Whilst I had some momentum up, I built a needle valve to control oil flow into the burner.

   

   

I gave the furnace a test firing with it's new fittings last night, the VFD coupled with the air control valve makes for good air adjustment during warm-up and the oil control valve worked very well indeed in controlling the fuel supply.
   
   

I still need to do something better to mount the oil container but this is workable. I'm hoping to be able to do another test melt tomorrow, unfortunately the weather has turned wet so it might get delayed again. Hopefully not for thirteen months this time.