Oil furnace for cast iron. I need help

[aonemarine]

Nick, hole 1 is .090" and 2 is .028"
What oil are you burning? used motor oil? I remember reading somewhere that some motor oils are very difficult to get and keep burning (maybe synthetic?). I have been using the oil from my truck which is a diesel and then adding diesel fuel to it to thin it. Works well for me that way but if running straight oil it was difficult to get a really good burn and sometime the oil would puddle up in the bottom and actually cool off the furnace. Maybe pre heating would have helped?

 

[aonemarine]

http://www.ebay.com/itm/DELAVAN-AIR...996?pt=LH_DefaultDomain_0&hash=item460af89144

 

[MuellerNick]

Thanks a lot aonemarine!
I will follow your advices! I think I'll make that nozzle tomorrow. As soon as I have something to report, you'll read it here.

Nick

 

[MuellerNick]

Now that looks promising!

The whole assembly with the fuel and air (thinner one) tube and the nozzle.


Inner part of the nozzle with the bore for the fuel.


Closeup of the cone. In the center is the bore for the fuel. The slots are for the air. There's a lot of lint on the grooves. Soooo much oil.

Initially, it didn't work. Well it did, but with so little fuel throughput that it would have been just enough for a doll's kitchen.
Then I increased the bore from 1 mm to 2.7 (IIRC). Well, more fuel, but dripping at the nozzle and big droplets. I was near ordering at patriot-supply, but the biggest nozzle he had was just for 4 liters per hour. That makes at about 4 kW. That's not what I want!

So I was close to throw that crap into the darkest corner of my shop … but before, I decided to cut deeper groves.
Now I have no dripping of the nozzle, get an almost invisible narrow cone that shoots out a lot of oil.
I have throttles on both the air and the fuel, so I can adjust it.

The grooves were ground on a T&C grinder with a sharp edged CBN-wheel.

Will be raining tomorrow and on Saturday, but I hope to make a real test ASAP!
If all works well, I'll post a drawing.


Nick

 

[aonemarine]

I'm not sure if the tip is quite right. When the air is on will it pull a vaccum on the fuel supply line??
I think there is supposed to be a little nipple that sits above the air slots centered in hole one so it will create a siphon effect when the air is turned on. But if it atomises fuel ok id say light it up.

 

[100model]

Hi Nick

Thank you for your Email

First of all these are the dimensions of my waste oil furnace: Inner dia. 36 cm and 37 cm high. Burner tube dia. 60 mm, Oil tube dia. 10 mm, Jet dia. 1.7 mm

____________________________________________
/
/ ß blower air
/

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40 mm jet_________________________oiltube___________________


I \
I \
I \ ______________________________________________________
I I
I -----I
19 mm

The jet size is a little on the big side, my thinking at the time was when I built the burner if the oil is too thick it will still flow from the jet. To my regret everything was welded so if I want to change anything it is too much trouble. Anyway my luck held and it works exceptionally well! 16 years later it still works so there is no need to modify the burner. I have been melting cast iron for 27 years. I started with propane and then went with waste oil because I can get it for free.

The oil I use is used hydraulic oil and is watered down with diesel, kerosene or jet fuel, whatever I can get for free at the time. The mixing ratio is: summer time 90% oil 10% diesel, winter time 80% oil 20% diesel. I pressurize my oil using an old propane bottle and compressed air. My furnace will not start on oil, propane is used to get the furnace walls red hot which takes about 2 minutes then the oil is turned on and the propane turned of. The blower air atomises most of the oil and the hot furnace vaporises the rest. From a cold start it takes 50 minutes to melt 14 kg of cast iron hot enough to pour. It uses 9-10 litres of oil for a melt, some melts use more oil to get very hot metal for thin sections. I get a lot of requests to see the furnace running and about 5 minutes after starting it is so bright they have to use a tinted visor to see inside my furnace. Kaowool is the refractory I use because it heats up very fast.

Nick, I had a good look at your photos and I can see possibly a combination of problems. Melting aluminium is so easy but when someone tries to melt cast iron with the same furnace that is when the problems will start. When the furnace temperature rises heat is lost faster than at aluminium temperatures and so the burner has to replace the heat faster than what is lost. It is like hitting a brick wall the furnace will not get any hotter.

Too much fuel cools a furnace down and too much air will cools down a furnace, a happy medium has to be found. Your blower will produce a lot of air but because you have reduced the blower opening to the burner tube size you have reduced the blower output by more than half. The blower you are using puts out a very low pressure so any back pressure drops the output. I use a 2000 watt vacuum cleaner that has a speed controller. Vacuum cleaners produce very high pressures so it can force the air through the burner. The one I use is never run at full speed because the furnace gets hot very quickly. You will have to try one thing at a time to eliminate the problems.

There is one thing that puzzles beginners at melting cast iron, the iron looks very hot but pours like honey. It can very easily fixed by adding chemicals to the melt but can create more problems than it solves for the beginner. It happens when beginners use badly rusted or oxidised cast iron such as sewer pipes and cast iron swelled up by heat. Don’t use that type of cast iron as throwing just anything into the crucible is bound to cause problems.

Here is another video I made of a iron casting party at my place two weeks ago
[ame="http://youtu.be/fCEw18evOmc"]http://youtu.be/fCEw18evOmc [/ame]
At the time of writing this post it is 42 C in the shade, it is so hot I don’t think I need a furnace to melt cast iron.

 

[100model]

Nick I see you are building another burner so disregard my failed attempts at drawing.

 

[aonemarine]

100 model, what size crucible do you use??

 

[MuellerNick]

No, the nozzle sucks in the oil, I verfied that.
T?here are two types of nozzles beinig used by others. One with the nibble, the other one without.

I also measured the throughput of thr blower with the restriction. At full throttle it makes 200 kg of air per Hour.


Nick

 

[aonemarine]

sounds like all you need now is a day where its not raining. Looking forward to seeing you melt some iron

 

[kvom]

OT question. After you pour the melt, does the crucible get a coating of iron on the inside after cooling, or does it all run out?

 

[aonemarine]

OT question. After you pour the melt, does the crucible get a coating of iron on the inside after cooling, or does it all run out?

There is usually some slag and iron in the crucible after the pour that you should scrape out while it is still hot.

 

[jasonh]

I was near ordering at patriot-supply, but the biggest nozzle he had was just for 4 liters per hour. That makes at about 4 kW. That's not what I want!
Nick

Yes 4 kW seems low for a CI capable burner....

for diesel fuel:

density = 0.832 kg/l
heat density = 43.1 MJ/kg

for a 1 US gallon per hour delavan nozzle:

1 US gallon = 3.78 litres
1 hour = 3600 seconds

power = 3.78 * 43.1 * 10^6 * 0.832 / 3600
= 37.7 kW

looks like a x10 got dropped

 

[MuellerNick]

looks like a x10 got dropped

Yes! And that happened to me.
1 l of diesel has about 10 kWh.


Nick

 

[aonemarine]

diesel has a btu around 145,000 and waste oil is lie 150,000 to 180,000 so wouldnt waste oil require less fuel?

 

[100model]

aonemarine With the waste oil furnace I a no 12 clay graphite crucible. The small furnace I use a no 1 clay graphite crucible.

 

[MuellerNick]

Hy!
It looks like we will have rain for the next few days.
As I will leave (hopefully) at the 10th of January for Karlsruhe (a steam fair), it doesn't make sense to cast the day before leaving.

So you and I will have to wait for the week following the next for further trials.
But don't worry, I WANT to cast CI, and if I want it, it will work …


Nick

 

[aonemarine]

Hey Nick, its been 10 days....got iron??

 

[MuellerNick]

Hey Nick, its been 10 days....got iron??

Hadn't the time to try yet. Last week was Karlsruhe steam fair and I wanted to show as much as possible of my MAN Diesel.
Now it's freezing and snowy. I'll have to wait for a sunny day.

I will keep you informed, don't worry! And I won't give up!


Nick

 

[aonemarine]

I know you wont give up, just eager to see your success