# Building a pyrolysis furnace -- Need Help



## ahmadbayoumi (Oct 30, 2016)

Hello Dears,

I'm currently in the process of building a pyrolysis furnace using the propane tank shown in the below pictures:





While building this furnace, I have some queries that need to cleared to avoid any accident or explosions:

1- To avoid explosion, it was suggested to put some water to absorb oxygen and thus eliminate the chance for explosion.
The question here are: where to add this water ? Inside the tank/crucible ? or mix the chips (ICs) with water (seems not logic to me) ?

2- In the below picture the blower is used to drive the gases to the fie so that they got combusted and there should be no smoke then.
The questions here are: what is the exact design of the part the part marked in red ? 
Also, is it a good idea to mix the fuel coming from the gas tank with the gases/smoke coming from the burnt ICs together ? Is it save running the pyrolysis process that way ? will the air coming from the blower shut off the fire ?




3- What are the other recommendations/precautions that could be mentioned here to avoid explosion


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## ahmadbayoumi (Oct 30, 2016)

Just for copy rights; PLS note that above picture were taken from another post here posted by another member.

My pictures are not ready yet as as I'm still preparing the furnace.

Now, I'm waiting for your help.


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## Gratilla (Oct 30, 2016)

Ahmad, you're way overthinking your design/process. A basic pyrolysis unit consists of a reaction chamber (which you already have) and an exit pipe along which your produced hydrocarbon gases can exit. Distillation units for liquefying low volatility gases etc are optional.

Risk of explosion is caused by oxygen and flammable gases being mixed in certain proportions and activation energy (ie a flame/spark) applied. If your reactor is being heated continuously and producing hydrocarbon gases continuously (without oxygen being introduced) which are burnt at the end of your exit pipe, then your risk of explosion is pretty much eliminated.

2. I do not understand the purpose of your blower. If this is mixing air (ie 20% oxygen) with your volatile hydrocarbon gases at their point of exit from your reactor, then this is AN EXPLOSION RISK. GET RID OF IT IMMEDIATELY!

1. Water in your reactor before you start heating is optional. As you heat your reactor (containing your chips), any air expands and is expelled. If you use water, the air is replaced by steam above 100 deg C which in turn is replaced by hydrocarbon gases as the temperature increases. There is (virtually) no air/oxygen in your reactor at his point and no risk of explosion. Also a continuously heated reactor with plenty of content will produce sufficient pressure of volatile gases and no additional pressure (ie blower) is necessary.

There are a number of pretty good pyrolysis videos on YouTube. Take a look.

Gratilla


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## geedigity (Oct 30, 2016)

You want the top of the reactor to be fitted with a pipe that wraps down along the outside of the reactor and the end of the pipe exhausting the gasses beneath the reactor vessel. At the end of the pipe that is now beneath the reaction vessel, you can weld a second pipe parallel with the reactor vessel pipe to use for your mixed air and gas to start the heating process and begin pyrolysis. Once the pyrolysis reaction gets going, you can shut off the gas (*not the gasses coming from the reaction vessel*) and have the blower help provide oxygen to the gases coming out of the reaction vessel to continue heating the reaction vessel. 

I wouldn't connect the blower to the pipe coming from the reactor, since O2 could make its way into the reaction vessel and potentially cause an explosion. I have never used water in my reaction vessel so I can't comment on that.


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## ahmadbayoumi (Oct 31, 2016)

Many thanks for your answers .. However, they raised more question than answered  and this is good for me and others to learn.

1st let me describe the process as I'm expecting and then PLS advise what is wrong and what is not:

1- I'll cut the top of the empty propane tank I'm using which will be the main reactor chamber as per below:




2- Then will weld an exit tube from the top of the reactor down to the bottom directly beneath reactor chamber.
This is to provide a path for the toxic gases to get out of the reactor chamber.

3- The heating source will be also put directly beneath the reactor chamber. Thus the toxic gases out of the reactor will be fed directly through the exit tube to the fire beneath the reactor to be combusted.

3- A blower will be connected at the bottom of the exit tube to force the toxic gases to be fed to the fire under the reactor.

So there will be no oxygen inside the reactor itself but the oxygen coming from the blower will be mixed the gas used to setup the fire and the toxic/exhausted gases resulted from incinerating the chips

So the process will be as follows:

The ICs/Chips will be out inside the main reactor chamber (modified gas tank) then and initially, the gas feed will setup the fire thorough the gas tube directly beneath the main reactor chamber then once the chips started to got hot the toxic gases will start emitting and will be forced toward the exit tube in the top of the reactor. Then and using the blower these toxic gases will be forced to to be mixed with the fire gas and the air from the blower in the mix tube towards the fire beneath the reactor to be combusted as required to complete the pyrolysis process.

PLS check the below pyrolysis unit layout:




Is it save to mix all these toghter (Toxic/exhausted gases from incinerated chips + gas to setup fire + air from the blower) ?
Or should I use a separate tube for fire gas + blower air as advised by geedigity or what is the best design here .. PLS advise.'


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## Gratilla (Oct 31, 2016)

The blower is a complication (and risk) that you don't need. How do you control the mix ratio of air and combustible gases from the reactor? Pressure of gas from the reactor should be sufficient. To increase the temperature of the burn, a simple adjustable air inlet a few cm from the point of exit of the gases from the exhaust pipe (ie the point of combustion), as per a bunsen burner, should be sufficient.


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## 4metals (Oct 31, 2016)

You have a continuous loop of combustion gasses from pyrolysis and your fuel with no where for burnt gasses to escape. One thought comes to mind.......BOOM!!!! you must allow completely combusted gases to escape.


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## ahmadbayoumi (Nov 1, 2016)

Thanks for your replies 

The Blower should be used to force the the exhausted gases to the fire to be pyrolyised and also to increase the efficiency of the fire to increase the temperature. I saw this design many times in this forum.

I modified the design to take into consideration all what you have advised here
- Separated the Air inlet (without blower) from the exhausted gases and the fire gas as well.
- Made a separate pipe for the fire gas (gas used to setup the fire beneath the main reactor)
- Drilled as many as possible holes in the tank base to allow completely combusted gases to escape.




So is it ok now ? Should I go for this design?


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## 4metals (Nov 1, 2016)

You are letting the combustion gasses out at the base and taking minimal advantage of their heat by exposing it of more of the reaction vessels walls. And you are exposing the operators to the noxious fumes that come off. 

I think this design needs more thought. It's great to repurpose the old tank but this design is not very efficient.


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## ahmadbayoumi (Nov 1, 2016)

I'm not sure that if totally understand your point or not 4metals ..

This design is already in use by another member here in this forum.

I will surround the tank with fire bricks to minimize the escaped toxic fums/gases

PLS elaborate more.


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## butcher (Nov 1, 2016)

You cannot blow air into a closed container. There has to be someplace for the fumes to escape, or you cannot blow air into the container.
Drop a lit match into a coke bottle now put your lips over the bottle ant try to blow enough air into the coke bottle to keep the fire going.


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## 4metals (Nov 1, 2016)

> This design is already in use by another member here in this forum.



Well maybe the member who is using this design will speak up. I think something is missing in the interpretation of the design or the drawings you looked at. 

Where did you see it on the forum?


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## Shark (Nov 1, 2016)

The misunderstanding might be in the bottom of the container. In ahmadbayoumi drawing, the red area around the bottom, representing the flames, is not inside the container. The flames are contained in the stand that is made onto the bottom of the container. He has drilled holes in that band to allow for air flow underneath to help burn the escaping gases. 

Here is a picture of the bottom of one of the gas cylinders where he proposes to ignite the escaping gases that come from the upper end of the closed off container.




That is how it sounds like he plans to use it to me.

Found the link,

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=22581

Edit to add link.


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## ahmadbayoumi (Nov 2, 2016)

Thanks a lot Shark as you exactly described my plan and the way I intended to run this pyrolysis 

Also I'm sorry for all of you if I wasn't clear enough to you  

The link shared by Shark is exactly the one I was referring too.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=22581

So the design is already there and I wanted to understand some points about it.

SO PLS check this design and share with me your thoughts, advises.


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## Barren Realms 007 (Nov 2, 2016)

ahmadbayoumi said:


> Thanks a lot Shark as you exactly described my plan and the way I intended to run this pyrolysis
> 
> Also I'm sorry for all of you if I wasn't clear enough to you
> 
> ...



If you look at the design in the link it is showing a vessel within a vessel. The inside vessel is the material that is incinerated. The outside vessel completes the combustion of the gases produced by the burning of the material in inside vessel. 

It seem like you are trying to do this with one vessel or tank.


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## ahmadbayoumi (Nov 2, 2016)

Thanks Barren for your reply 

The design I'm referring to, is using only one vessel which is the empty propane tank modified to act as a pyrolysis reactor.

So It's only one vessel in which the chips will be put in. Then under this vessel the fire will heat this vessel and then the emitted fums/gases should be re-fed to this fire to be pyrolysised.

Thanks the whole idea in a nutshell.

My queries here is about some specific details about this design so appreciate if anyone could help


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## Shark (Nov 2, 2016)

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=22581#p237062

If you look at the second picture from this link, the brick enclosure acts as the second container that Barren Realms is talking about. The small space at the bottom of these gas cylinders is to small to contain the gasses escaping from the unit. That is just my opinion, but I have never actually built one like this. The brick box would ensure that the created gasses will burn where they can do the most good towards finishing your material with minimal wasted gas.


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## ahmadbayoumi (Nov 2, 2016)

This exactly what i mentioned above that I'll surround the reactor with fire bricks to act as a second vessel.

However, I still have some points that I need to understand:

1- The benefit of using the blower and if it's necessary of optional.

2- Should I mix the propane gas sued to setup the fire with the air coming from the blower with the toxic fums/gases (to pyrolysised) all together like the same in the link.
OR should I separate them as suggested by some experienced members in this post to be more save and to avoid explosion


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## Shark (Nov 2, 2016)

ahmadbayoumi said:


> This exactly what i mentioned above that I'll surround the reactor with fire bricks to act as a second vessel.
> 
> However, I still have some points that I need to understand:
> 
> ...



I am not sure which would be the best way to go. With the experience that 4metals, Barren Realms and butcher have I would most likely just follow their advice. My thoughts would be to use a "flap" type door that works only one way, to allow the gasses to escape but stops the air from the blower from pushing any air back inside the container. Set it up in such a way that the door would open just as the pressure begins to build inside but not allow an excess build up. That would further complicate the design, but might be a workable option.


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## Dpetes (Nov 3, 2016)

As far as I can see, The best thing for you to do is PM kjavanb123 and ask him since this is his design. 
It's better to get it done the right way than to put yourself and others in danger.

Dwayne


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## autumnwillow (Nov 3, 2016)

Think of a pressure cooker as your pyrolysis reactor (which is your gas tank), the exhaust gasses can be routed to the burner again for combustion.

Think of your normal stove pan as your burner, it needs to continuously burn thru open air as pressure will build up if you try to make this enclosed.
Imagine putting a torch tip against the wall. You would most likely be building so much pressure that it will backfire.

What kjavan did was he used firebricks as the outer vessel for the reactor. His burner is actually burning outside of the reactor and not in a sealed way. As you only need about 800degC for incineration, it shouldn't be that hard to achieve with a firebrick wall setup.

Again, do not do it in a an enclosed system. The burner should have its fumes escape somewhere. 
We would love to see the pictures before you fire it up.


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## autumnwillow (Nov 3, 2016)

Oh wait. He actually welded the burner at the bottom of the reactor. But observe that the bottom of his reactor has holes in it. I would rather have the burner go thru the sides that should create a vortex and even the heating of the reactor.


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## butcher (Nov 3, 2016)

Notice flue of fire gases heat the reaction chamber as hot gases escape from around the pyrolysis chamber past the hot fire brick out the top of the furnace, inside the reaction chamber the toxic gases are heated and forced down the tube into the burner, these gases act as fuel for combustion along with the other fuel from the burner, these gases are introduced into the flames heating the reaction chamber to complete combustion with air added from the blower.

The design should work fairly well, it could be improved by adding an afterburner, to re-burn the fumes exiting the top of the furnace…


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## ahmadbayoumi (Nov 4, 2016)

Thank you very much for all of you for the great information you shared with us 

Now, I totally understand the concept behind this design and how it works to pyrolysis the toxic fums coming from incinerating the ICs/chips.

However, I'm a little bit confused about the internal deign of the part marked in red in the below picture.




I know how it works but need to know the exact deign of this part as it's hidden in the above picture.

Now, all (Toxic fums to be pyrolysised, burner fuel, and air from the blower) are mixed together in the bottom pipe.

But how and I can mix them all together ? 
Should I make a separate pipe for each one then they all meet at the end/exit of the main pipe just before the fire ?

PLS Help


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## butcher (Nov 4, 2016)

The blower is obvious, in the tube going into the furnace, where the fuel line enters, the Y in the burner can act as a venturi.


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## ahmadbayoumi (Nov 4, 2016)

Thanks butcher 

So you mean that it's something like the below ?




And if so does the air coming from the blower affect the fire and can shut it off ?

Also, can this air finds it's way to get inside the reactor and lead to a risk of explosion ?


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## 4metals (Nov 4, 2016)

My hesitation to liking this setup is because you are not defining a simple efficient pathway for the flame to travel. Flames do not like to bounce off of things, they do much better in a circular pathway. 

The blower entering the bottom of the modified propane cylinder may produce the heat but the flame is kind of stuffed into the confined space and has to make it's way out of the space through whatever hole produces the path of least resistance. After the flame exits the base, it has minimal velocity from the blower and the heat will rise straight up the wall created by the bricks. 

If I were making this unit I would use the propane canister to hold the chips being pyrolyzed, but cut off the base completely so the propane cylinder becomes an enclosed chamber which you put into an efficient operating gas furnace. 

A gas furnace is best cast with a cylindrical inside so the entire propane cylinder canister fits inside. This will efficiently supply heat to the pyrolysis chamber. Kurtak has posted pictures of his gas furnace which would be exactly what I am trying to describe. 

Then the pyrolysis chamber can be added to the furnace just like you would add a crucible. The gasses escaping the chamber would be directed down into the flame coming into the furnace where they are burned and forced in a circular motion, slowly ascending through the space between the chamber and the furnace wall. This maximizes contact time and heat exchange to burn up more of the undesirable gasses. 

Another benefit of this approach is you will also have a gas furnace capable of melting refined metal or smelting for copper refining all by changing from a crucible to the pyrolysis chamber which will take seconds in a properly designed unit. 

I cannot find Kurt's furnace pictures, which I know he has posted, but if Kurt or someone else could provide a link this description may be a bit more understandable.


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