I asked my question in another forum and they suggested I talk to you folks. Here's my situation.

I'm a hobby blacksmith with an oil burning forge. I runs great on straight WVO -- and I do mean veggie oil. The narrowest point of the fuel system is 1/4" inside diameter; there are no injectors or filters to clog. I use window screen to filter the oil; smaller particles won't hurt anything. It's not a picky design, but it'll get hot enough to destroy itself if I'm careless.

The problem is that my most recent fuel acquisition seems to be primarily tallow/lard. It's way too viscous to flow well through my fuel line right now; in fact I'd have trouble even filtering it. I considered converting it to biodiesel, but if there's a simple way to thin it that'd be even better. I haven't made biodiesel before, and I'd rather not have to start just to get my forge to eat a little lard.

Preheating the fuel in the tank would work, but it'd require significant reengineering, additional materials and labor -- none of which excites me right now. So what about solvent thinning? If I warmed the fat to liquefy it and mixed in some kerosene or petrodiesel**, would that thin the fat significantly (and keep it thin on cooling)? If so, what proportions should I use? If not, is there something else that'll do the job?


**I didn't mention RUG because I can't stomach the prospect of having gasoline anywhere near the forge, even if it's in some kind of solution. Kerosene scares me less, and diesel a little less than that. One of the things I like about WVO is that it's a safe fuel for my environment.

Yep, that pretty much says it.

I am assuming you are gravity feeding the oil to the burner ?

What sort of burner design are you using, how are you atomizing the oil, must be a simple pot burner design if it does not use any sort of spray nozzle, how are you injecting the air so that it does not blow out the fire ? If the smallest fuel opening is 1/4 inch how are you controlling the different amounts of oil needed for the verious heats ?

About the only usable option is to add some heat, everything will stay melted by 80 deg f so it does not have to be a LOT of heat. depending on the type tank you have it can be pretty simple. About any farm store will have small electric heaters to keep ice out of stalk watering tanks in winter, these work. I have even used the stovetop elements from electric cook stoves. These are normaly powered with 220 volts, connect them to 110 and they will only get 1/4 as hot, clamp one to the outside of the supply tank (assuming the tank is metal) and it should eventually heat up the oil.

My oil settling barrels all have electric hot water heater elements mounted in them because of this same problem. I brazed one inch pipe couplings through the side of the barrel and screw the heaters in to these. I have 2 heaters wired in series and powered with 110 volts, this gives me 500 watts of heat and that is enough to keep 50 gallons of oil at over 100 deg f even when the weather is well below freezing. I control the temp using a water heater thermostat clamped to the outside of the barrel, heaters only run maybe half the time even in cold weather.

quote:

No, the tallow/lard/animal fat will settle out below 65°F

Ah. Actually, that shouldn't be a problem at this time of year. Thinning would probably work. But Tim's preheating ideas sound pretty good, and without the additional fire concerns.

quote:

I am assuming you are gravity feeding the oil to the burner ?

Yep.

quote:

What sort of burner design are you using

,

It's a derivation of an Ursutz burner. Some folks have the combustion take place in a separate burner box, which exhausts into the forge (or casting furnace -- metalcasters are ahead of most smiths on this stuff). But that seems inefficient to me, so I do my burn right in the forge. It also gives me better control over the forge environment. (A slightly reducing environment is better for high carbon steels.)

quote:

how are you atomizing the oil, must be a simple pot burner design if it does not use any sort of spray nozzle

Pretty much. The incoming oil is preheated as it reaches the end of the fuel line to reduce its viscosity, and the fuel line ends dead center in the end of a 2" I.D. tuyere (air inlet) that's hooked to an electric blower. The tuyere is necked down to about 1.5" at its end to create a venturi (in theory), and he incoming air is also preheated with exhaust gases. The hot air picks up and partially atomizes the preheated oil, and carries it into the forge. It's fairly crude atomization, but that's fine for these purposes because the intense heat inside the forge is enough to vaporize oil in its own right. (Some guys just drip their oil straight into the combustion chamber, separate from the air flow, and get perfectly good results.) Remember that I use a charcoal preheat. With better atomization I wouldn't need it -- but with it, better atomization isn't needed.

quote:

how are you injecting the air so that it does not blow out the fire ?

See above. One additional point is that my electric blower is hooked to a motor speed control so I can continuously vary the volume of incoming air. I only use about 50-60 CFM of air when the forge is at a good forging heat.

"If the smallest fuel opening is 1/4 inch how are you controlling the different amounts of oil needed for the verious heats ?[/QUOTE]

The smallest fuel point in the fuel line is the homemade needle valve that controls fuel flow, and 1/4" is when it's wide open. I don't normally run it wide open, of course, so in effect the orifice is smaller most of the time. But highly refined fuel still isn't necessary; if the valve gets a little gunky I can always crack it a little more. This sort of design does need its fuel line and valves cleaned out out occasionally.

Good suggestions on preheating the oil in the tank. I guess t wouldn't be as complicated as I was envisioning. Thanks.

Thanks for the info. You are making a LOT more heat than the veg heaters I built over last winter.
This discussion is about a drip burner used in my wood stove to keep my shop warm.

This discussion is about a stand-alone Sanders style drip burner that kept the house warm over the winter.

Check out the other burner discussions in the "biodiesel for heating" section under the"Biodiesel" forum (Click here)

Thanks for those links, Tim. Very interesting stuff. Right now I'm keeping an eye on the scrap bin behind the local oil heating place. (Happily, it's less than a mile from my house.) Once I secure a used home heating oil burner, my next project is to figure out how to hook that up to, essentially, a super-duty thermostat made from a Type K thermocouple. The idea is to have the thermocouple cycle the burner on and off to maintain a selected temperature (say, around 1500 F) in a furnace. You've obviously played with commercial burners, so I may pop by and ask for some input once I get my hands on one.

Using a standard high pressure fuel oil burner to burn heavy oil, either veg or used engine oil, is a bit difficult, need extra heat at least. Syphon style burners work better and a normal home oil burner can be modified to a syphon burner, but this is still a bit iffy and additional fuel heating is still needed. The most promising approach I have read about so far is modifying a home heating oil burner into a Babington style burning that uses external supplied oil flowing over the outside of the spray nozzle, still likely need to preheat the oil but it looks more promising than the other type burner mods. Normal home burner units as the base for all of these different burners. I hope to test the Babington mods over this summer (past discussion here).

You may be interested in building a "Murphy" burner, It is based entirely on simple plumbing rather than a home heating burner. (discussion here, plans available), this burner will burn either veg or engine oil reliably and cleanly and shoots the flame vertically. May be able to simply place the iron into the flame through the clean-out door in the side of the burner tank.

If you can collect a few Suntec fuel oil pumps, "A" or "J" model, 1750 or 3400 RPM (1750 prefered, depends on flowrate needed), single stage, Suntec pumps, from the normal home oil burners. These can be modified into nice heavy-oil (hot or cold) fuel pumps for about any burner or vehicle project. I will be posting my mods to several of these for several different uses as veg fuel pumps here sometime over the summer.

A side from Tim's links here. Infopop member jessejames (Jesse Parris) has some yahoo groups also;
altfuelfurnace
altfuelbabington
altfuelvented
AFFBuilders

Thanks, Tim. The main reason I'm interested in a furnace burner is that it's a nice, neat little package that starts with the push of a button and is already designed to be controlled by an external sensor. For an electronics moron like me that's an attractive combination. I wouldn't mind if I had to make full-on BD for it, or even if I had to preheat the BD. I'll only use it intermittently, for relatively short periods, so keeping up with its fuel demands won't be hard. And the application I'm planning on using it for -- heat treating -- requires very good temperature control. I suspect I can get that more easily with a furnace burner than with a more, er, improvised design. Some folks could probably make what I want from scratch without breaking a sweat. Unfortunately I'm not one of those folks.

From what I have read on the Altfuelfurnace website even biodiesel is a bit harder to get to burn absolutely reliably in a stock oil burner, it lights harder than diesel, adding a bit of kerosine seems to eliminate most problems, some folks say they don't have any problems with straight biodiesel. The only problems really is that the stock suntec fuel pump shaft seal won't survive over time on biodiesel, it drips a bit eventually, may not be a concern for your use. The Suntecpumps.com website says B20 works OK but no guerantee with B100. Your local bearing and seal shop should be able to come up with a biodiesel resistant seal ? The seal is easy to replace, just pry out the old one and push in the new one. Would probably be better to disassemble the pump and push out the complete seal intact so the seal shop can match the new one, also pretty easy to do.

Great thread!