# My New Incinerator



## jeneje (Jun 13, 2012)

I have been working on this for few weeks and i finished the firebox just a few miniutes ago so i thought i would post a pic. Now comes the hard part, figuring out the afterburner for the smoke. Any suggestion would be greatful. Have a great night.
Ken.. :lol:


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## kjavanb123 (May 18, 2014)

I am surprised as this never got any responses. Did you finally completed this? Another pipe to remove the smoke and something similar a lot taller to burn the gases.


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## 4metals (May 18, 2014)

This is an old thread that I had missed but commenting now is better than not commenting at all. 

First, that is a nice job with the brickwork, after a discussion of afterburning I will ask a few questions about brick types and mortar and how it has held up. 

Lets discuss what an afterburner is and what it does. Classically an afterburner is placed in the path of the smoke resulting from the burning or incineration of whatever it is you are incinerating. The afterburner essentially burns the unburnt fumes or smoke after the smoke rises out of the burn chamber. This is usually accomplished with a combination of temperature and retention time. The smoke is heated by a flame and reburns, or more correctly burns to completion. If the smoke is in contact with the oxygen to burn and is in the afterburner long enough it is an effective pollution control device. Fortunately, unlike the retention time required for NOx to be scrubbed (which takes 8 seconds of retention time) the retention time for a nice hot afterburner is less than 1 second. 

After some reading on this forum about experiments done by NoIdea, I figured out a way to combine incineration by controlled pyrolysis and a common gas melting furnace to come up with an incineration device that essentially performs like an incinerator with an afterburner without actually having an afterburner. 

Your furnace as shown in the photo will need a crucible rest. A crucible rest is like a fat hockey puck made of refractory cement that raises your crucible about 2 inches off the bottom. You should be using one for crucible melts anyway to effectively heat the bottom of the crucible. You will also need a lid which I assume you have but didn't show. The lid will keep the smoke in the heat zone just a little longer to make the burn more effective. I should mention the lid needs a 2 or 3 inch diameter hole in the center for the fumes to escape in case anybody is not familiar with gas melters. 

Basically what you need to accomplish is to burn the material in a crucible but make the smoke come out the bottom. What i have done with great success is to use the tall cylindrical crucibles commonly used in induction furnaces. Some of them have an internal crucible which is graphite and a silicone carbide outer crucible. What i have done is separate the inner crucible from the outer crucible. Easier to do with an old used one by chipping out the inner crucible to preserve the liner. So the inner crucible without an outer protective shell is filled with whatever you want to incinerate. The outer crucible is inverted over the inner crucible so the smoke has to go down to the bottom of the furnace before it escapes. There the smoke encounters a hot flame (oxidizing flame if possible) which ignites the unburnt gasses and acts as an afterburner. 

The material is not actually burned as there is no oxygen to sustain a burn. Instead it gives off all of its volatile gasses, unburnt, which ignite and burn when they escape at the bottom of the outer crucible. If you pre-heat the furnace, fill the crucible and place it in the hot furnace and quickly add the inverted crucible and the furnace cover, the hot furnace walls help burning off the smoke. You can remove the furnace cover and look down to see when the load has stopped giving off burnable gasses indicating it is done. A mirror on a stick makes this easier. 

When you remove the outer inverted cover crucible the material is completely pyrolysized and still contains all of its carbon. 

If this is jewelry sweeps, you need to get rid of the carbon. This is done by spreading the pyrolysized material in a tray and lighting it with a flame. It burns like a charcoal flame, no smoke. Some guys burn this in a shallow tray and it burns completely, some burn it on a wire screen to get air under it because it doesn't burn completely without the screen. I do not know why it burns for some in a tray and not for others. 

One refiner uses bilge crucibles for this and covers it with a capped stainless pipe. The stainless lasts a few melts, I would imagine another metal, monel or titanium would have a longer service life. The straight sided crucibles with the outer crucible last a long time. 

As with anything you have to try new materials out with a degree of intelligence to determine loading to prevent smoking. 

What type of bricks were used in your furnace body? What type of mortar? Did it hold up well to the heat?


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## ericrm (Dec 21, 2014)

just trying to bring the post up to see what hapenned with the incinerator project

im looking in grf right now but if someone has some link to a good home made incinerator plan i would be interested in looking at it


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## NoIdea (Dec 22, 2014)

Hello from a warm summer evening from way down under :mrgreen: [winter for those up top ].

A cheep alternative, especially during winter, is to use two differnt sized tin cans instead of cruciples, and put them into your wood burner or fire.

Deano


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## etack (Dec 22, 2014)

ericrm said:


> just trying to bring the post up to see what hapenned with the incinerator project
> 
> im looking in grf right now but if someone has some link to a good home made incinerator plan i would be interested in looking at it



I have one of his kits and love it. I melt 100+TOZ of silver in no time.

http://www.backyardmetalcasting.com/index.html

Eric


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