New Diesel/WO Furnace Sizing

At what furnace temperature can you switch over to wvo? I'm still running 100% diesel while I troubleshoot this beast, but hope to move to wvo in the near future.

I suspect I was pooling for at least 10 minutes during my last burn. After I shut off the fuel, it kept burning from somewhere near the drain hole for about 45 minutes.

 

That's a fair bit of excess fuel pooling at the bottom, all I can suggest is a propane preheat then switch to oil once it's hot, like most waste oil burners do. I'm using pressure fed mist nozzles so I can do a cold start but I do get a small amount hitting the walls but it's less of an issue with a solid refractory concrete base. I do notice that the dense castable in the USA seems to be a totally different product to the stuff I get which is actually a high temperature concrete.

The main reason I hope you can debug on your existing furnace is that I built two furnaces as well and the second one had the same combustion problems as the first, I just transferred the issues to a furnace made of better materials than the first one. Fortunately with some experiments I was able to get it to run well.

 

Hi Kelly, One of my refractory bags had a calcium aluminate label on it so I did some research on the topic. It actually is a type of cement made by calcining bauxite and lime in a furnace instead of the usual lime that Portland cement has.The resulting clinker gets crushed to make a very high strength cement which can then be made into concrete with roughly three times the normal strength of concrete. It's fast curing so it's used to patch airport runway potholes but the concrete ages faster than normal concrete. The refractory concrete I get has a cream coloured aggregate which may be clay or it may be lumps of the crushed aluminate clinker. It dates from 1908 but I think it wasn't commonly used as a refractory until much later. The wikipedia article says it's good for repeated cycling to 1000 odd degrees C so I'm not sure why my stuff is good to 1650 deg C, maybe it's good to that when not repeatedly cycled. The amount of water used is very little: 76 mls per kilogram so it must be just enough to chemically combine with the concrete with little left over, it's unworkable without vibration.

https://en.wikipedia.org/wiki/Calcium_aluminate_cements

 

as soon as I see the bricks turning slightly orange. It would be hard to get an exact temperature rating unless I did a shut down 30 seconds after I switched to WVO. I leave my feed lines filled with fuel between each burn. The WVO I discovered I can't leave it in the lines for a week or two. So at the end of the burn cycle, I switch back over to diesel to clear the lines of WVO. At the beginning of the run, I flush the lines with clean diesel into a peanut butter jar. The next run I dump the peanut butter jar leftovers into the WVO container and give it a little bit of a swish. I pressurize my diesel and WVO to 60 PSI. But I have a 200 W magnetic Engine block heater to get the WVO up to a closer viscosity the needle valve can control.

But I have two torches. I switch one from diesel to WVO and then I switch the other one. During the switchover I become really a rich fuel mixture until the both torches switched.

I'm really a bad person to be giving advice though. I'm using the pressurized drip system with high velocity air. As well the two different blowers I'm using exhaust really hot air. One of blower manifold has 2 inch ABS pipe and I bet it is over 60°C.

The plastic container on the left (with the tap) Is straight WVO. I use this to fill my pressurized WVO tank. The five peanut butter jars on the right are a mixture of WVO and diesel.I will use them to top up the WVO tank next run.

 

The bauxite and lime chemically reacts to form a solid that needs crushing, I can't find much on the topic but I don't think the two melt together, more like clay in a furnace.

 

@OMM



lol.. and so the nightmare begins. Just wait until some critter decides it loves your veggie oil or it starts to rot. I loved burning free shitty motor oil, but in the end, my jet fuel is just as free and I've cleared up valuable real estate in my shed (55gal drum) and in the garage. Next is to give the tower of power a hair cut! It's about to be half the size.

 

If I had unlimited jet fuel, I would take your same route. I would even consider getting rid of the whole tower of power and just use Jerry cans and possibly a miniature pump.

As for the critters, I have about a half dozen mouse traps always set with peanut butter. I usually get about four year. I am sealed up pretty solid. But, if the garage doors are open, I sometimes get them sneaking in for a peanut butter snack.

 

That's actually a brilliant idea! I bring home my jet fuel in old de-ice 5gallon jugs of prist! I should make a special tap that fits all the jugs and screw it on each time. I can salvage my valve and shit off the T.O.P and chuck it! That would save me from lugging it in and out each time I melt. Speaking of a melt.. I poured a bunch of cans today for turning... And I had a lost foam failure. I used coarse silica sand and this aluminum box filled half and caved in. I'm convinced, lost foam is not for this guy. It stinks to high hell, I'll stick to wax and shell.

This wasn't coated, it was just pour and go. I used pink foam and have NO DESIRE to revisit this. I was just trying to slap something together really fast.
If it worked, fine, if not, F it!

 

I picked up from our junk store PA, a small walbro 6000 series 7 psi 43 gallons per hour pump that is about the size of my hand. It has a fuel flow pressure bypass. This thing was built to provide diesel to a truck or boat. I forget what it ran me (maybe $20).

When I tried to pump WVO through it, it choked.

 

I think I can get away without a pump honestly. I use compressed air to drive my venturi. Maybe I'll try to suck fuel uphill (24") tomorrow.

 

I would love to see know results with water.

I did some water syphoning manometer testing with my torch/s. I used my four stage turbine as the goal setter in blue( Disregard the red). The green is the Hz. Of the Vfd, of the big blower.

1TO= one torch open.
2TO= two torches open.

 

My siphon burner finally arrived and I was able to get her setup and burning. It took a little more work than expected as I ran into a few problems along the way.

I'm still burning diesel at the moment, but the burn started out very erratic and unstable. I tracked it down to too little fuel. I read somewhere that the siphon doesn't require pressurized fuel, but elevating my fuel a couple feet above the burner didn't work for me. I'm running 1/4" line, maybe I need to go larger. Anyway, I pressurized the line to about 20psi which resolved the instability.

The next problem was too much fuel, apparently due to the pressurized line. I added a needle valve to help control the pressure, which quickly resolved this problem and got me back to burning. I need to revisit the fuel though, and get away from pressurizing the line.

In a nutshell, this siphon burner works great! I didn't have time to really tweak it, but I was impressed with how much heat it delivered. I didn't have a timer running, but I felt like I got up to 900c much, much faster than normal. It took a little more effort to reach 1000c and above, but I'll chalk that up to getting a feel for how this baby burns.

I was able to reach ~1200c, but she really didn't seem to want to go higher, and I of ran out of time and had to shut her down for the night.

Couple questions:
- I started around 25psi air pressure, but found I had to move up to 50+psi in order to continue increasing to higher temps. What are you seeing with air pressure?

- I struggled to find an ideal location for the burner nozzle. I molded a 2" refractory hole into my furnace, and have my 2" pipe sitting an inch or two outside ( behind the furnace wall). Where do you position your nozzle for optimum burn?

- I recall reading a few posts stating that the fuel never gets adjusted, only the air pressure. I guess this doesn't make sense since I pressurized my fuel. What's the best way to deal with this when using a siphon burner?

Anyway, it felt great to have some immediate success. I'm excited to see how well she'll do when I have more time to tweak her.

Thanks again for all the help and suggestions. This has been an interesting ride, and I certainly appreciate the time and discussion around helping me solve the issues I've been experiencing.

 

How close were you to maximum airflow, was there more scope to increase the airflow into the furnace?. When I was gravity feeding waste oil I had to use 1/2" copper tube for the fuel line as 1/4" had too much flow resistance. These days I use 1/2' copper pressurized to 55 PSI with a flow regulator and a needle valve to the nozzles. This is for pressure only spray nozzles. My nozzles are situated inside the tuyere/burner tube a few inches so the spray doesn't hit the tube walls.

 

I reached the point where I saw the temperature start to drop when I attempted to add more air. I'm not sure if I reached maximum airflow or if something else needed to be tweaked. I won't be able to burn until Monday, in the meantime I'll look at increasing the size of my fuel line.

 

Sounds like you have enough air flow capacity and need more fuel in the furnace chamber. Does the siphon nozzle have a rubber O ring?, you may need to have a way to withdraw it from the furnace on shutdown to avoid heat soak ruining the O ring.

 

1/4" line is too small. I dorked that one up too. Today I run 3/8" ID hose and non pressure needed for oil as long as it's not 40degrees outside. Preheating helped it flow much easier.

Wheres the photos jimmy? Or video would be handy.

 

I used gravity feed for my Delevan siphon for several years until I made a pressurized tank. I still use that method for preheat with deisel and I hang my fuel container above my shop door until the furnace is hot enough to switch over to WMO. I use a 1gph nozzle. I agree 3/8 should get you all you need. A couple of feet of elevation isn't really enough though.
Whether it's gravity or pressurized, the amount of compressed air you're delivering to your nozzle makes a big difference in terms of combustion. It affects the amount of fuel draw with a gravity feed too so it can be a bit of a balancing act. A pressurized fuel line removes one of those factors. When burning light fuel like kerosene or deisel the air provided from your compressor alone without any blower will melt aluminum. It not only atomizes the fuel and provides a measure of combustion air, but it affects the turbulence dramatically as well which is an additional factor in overall combustion.
You will find a balance with the gravity method that works for you among head height, oil metering, and atomizing air pressure as long as you're using deisel. But when you switch to thicker oils like motor oil or veg the game will change. That's where pumped or pressurized fuel line becomes a much better option.

Pete