How to turn plastic waste into diesel fuel cheaply

[Excalibur]

The fuel turning to wax demonstrates that it is insufficiently cracked. Either the reflux is not working or other parameters are interfering with its' effectiveness.

Am still unclear on some details.
What burner type and how many kilowatts? More info on the heat shield?
Where does the reflux outlet exit? Is there any reflux packing?
Is there a temperature probe on the burner heat.? Is the burner heat volume adjustable while running?
How long does it take to bring the temperature up? Are you pausing or reducing the heat periodically during the heat up stage to allow any low boiling point fraction to boil off?

There are two other reports within the last couple of months with same/similar problem as yours. I suggest read and study those.
In any case put a temperature probe on the flame temperature to avoid superheating the steel vessel. Also if the retort probe is at the top of the vessel, it may not be showing the real temperature.

Jetijs found he had to reduce his reflux temperature to avoid the waxing. If I recall he used 150°C. See forum post #680 . (Seems very low to me though)

Hope this helps. It's difficult without more information...

[Renewable Rtesources]

OK i realized the problem was the heat shield and modified the reflux. My heat shield was right against the base of retort i moved it 2 inches off the retort with spacers. I use wood as heat source i use 2 doors on furnace in which i open and close to adjust temp. In the reflux i have added a distillation plate due to the fact that my pipe from reflux to condenser is on the side not on top, my design was originally to have plate inside but left it out, i have no idea why i left it out, reason for putting it on the side and not on top is because i put fuel in a conical flask with side arm and noticed vapour would not go through side arm as much but would condense on side near the top and run back down to boiling liquid. I tried another conical flask without side arm i put a stopper top with tube to condenser yes got more to pass through but when i put it back in the flask with side arm and added distillation plate so it would run right into side arm and condenser, in same space of time i got 250% more so decided to make it that way. But waxing was main problem of hdpe and ldpe. For anyone else experiencing waxing chances are heat shield is your best friend and spacing of the heat shield. And thanks for info will post more pics and info on set up.

[Renewable Rtesources]

The whole idea of the retort is to try and heat it evenly and not make same mistake i did and super heat the base. Notice the plants u buy online have a rotating retort to heat it evenly. Thanks allot Excalibur for info.

[Excalibur]

Nice work RR.

Your remedies sound OK. I'm not able to understand the 'conical flask/side arm' so perhaps a sketch, pic or illustration. The key function of a reflux is its' ability to separate heavy from light fractions so careful thought should be given to avoid interfering with that function..
Retort burner management could be explained with the analogy of a 'pot of food on a stove'. Initially a higher flame may be applied but once the contents is boiling, the heat is turned down to a simmer.

[wheels]

The whole idea of the retort is to try and heat it evenly and not make same mistake i did and super heat the base. Notice the plants u buy online have a rotating retort to heat it evenly. Thanks allot Excalibur for info.

Those kind of plants are usually for Vehicle Tyres and tend to be very large vessels.
The distillation process is complex. Far more complex than most realize and you need to have much greater precision with controlling temperatures. Wax can form for a number of reasons.
You need to keep all pipe work insulated till it reaches the first condenser, then you need to maintain each condenser at the appropriate temperature, with more insulation around pipe work between pots. Temperatures dependent on what kind of fractions you want.
The idea of just allowing the vapor's to flow and condense along the way will be creating many unsaturated chains and they are the ones that oxidize and may even cause waxing. One other form of wax could be a crystalization issue caused by a light fraction that does just that. Or it may be a very heavy fraction in the Parrifin range, which is caused by too much heat, or not enough cracking. For example, no reflux or fractions not being held at temperature long enough.
Whatever the cause, it varies for each and every design of plant and a lot of testing is required to find out exactly what you are producing.
One big important question. Are you extracting all the oxygen from your plant before operating???

[chacowako]

Hi has anyone had experience with a Mixer OR is a mixer really necessary?
I am building a 300liter retort per day. I already have my small scale prototype working (2liter per hour) and going to scale up my issue is with the mixer. Anyone could suggest a good way to do it?

[kedigen]

final state. hopefully no more wax

[rozier56]

rozier56

Has anybody had any experience with E V A plastics? Plastic utilized in slop manufacture.
Also have access to pv foam insulation material.

[wheels]

Hi has anyone had experience with a Mixer OR is a mixer really necessary?
I am building a 300liter retort per day. I already have my small scale prototype working (2liter per hour) and going to scale up my issue is with the mixer. Anyone could suggest a good way to do it?

There are many ideas on the Internet, but few actually work.....safely at least. There are many so called Manufacturers out there that have very little real world experience in Pyrolysis. They simply make plants and the Buyers think they are therefore buying something that works. But that is not always the case.
It is very very difficult to get a perfect seal when working with the temperatures and the vapors we are dealing with. I played with several ideas, but could not get anything to work effectively and continuously. All the tries ended up with leaks and the need for replacement with each use. Plus just thnk about how hot that motor would get sitting above the retort and the retort being heated to 400degC. I doubt the motor would last long.
I am sure that if money was no issue, it could be done, but that goes beyond what this site is all about.

[wheels]

Has anybody had any experience with E V A plastics? Plastic utilized in slop manufacture.
Also have access to pv foam insulation material.

Probably not something you want to play with. EVA Ethylene Vinyl Acetate, releases Acetic Acid for one, which is highly corrosive.
PV or I assume you mean PVA.....Poly vinyl acetate, is much the same as EVA
Just in case you are referring to Polyurathane foam, no that can not be pyrolized as it produces vast amounts of Di-isocyanate.

[Excalibur]

Hi has anyone had experience with a Mixer OR is a mixer really necessary?
I am building a 300liter retort per day. I already have my small scale prototype working (2liter per hour) and going to scale up my issue is with the mixer. Anyone could suggest a good way to do it?

No experience but I believe a mixer would help the feedstock boil more calmly something a bit like Boiling chips/Anti bumping granules
My thought is that because there is next to no pressure in the retort, the shaft could be sealed with a simplified DIY version of a Mechanical seal

final state. hopefully no more wax

Looks nice. Am wishing you best of luck from far.

[chacowako]

Excalibur my design is actually a pattern from yours so I would like to ask you
Do you have any problems you think that it needs a mixer?
AND MOST IMPORTANT how do you clean your Retort?

Also I finally found a level switch that can handle 600c yeay

[wheels]

No experience but I believe a mixer would help the feedstock boil more calmly something a bit like Boiling chips/Anti bumping granules
My thought is that because there is next to no pressure in the retort, the shaft could be sealed with a simplified DIY version of a Mechanical seal
Looks nice. Am wishing you best of luck from far.

I tried a mechanical seal as well, but then I am working with the most nasty of plastics and I can't accept even the slightest leak of gasses as those gasses are highly toxic and corrosive, not to mention not wanting any oxygen to ever creep back in. The acid levels are extremely high, so any metals (brass etc) that work as a seal in any other application, do not work with acids at 400 to 500degC. I have considered a carbon face type seal, but have not gone further, due to time being taken up in other area's at the mo. Once fully back into the Pyrolysis part when I get back from Auckland, I will be trying several ideas.
The idea of having a stirring device was two fold. Firstly was actually to solve a problem of the Carbon caking in the bottom of the retort and keeping it moving was to aid in a way of automatically removing by a small port at the bottom. But this has to be done with extreme caution, because the last thing anyone wants is for oxygen to be introduced at the bottom of the retort. It results in a loud ringing in ears and possibly Sunday afternoon harp practice on a cloud somewhere.
The other thing the idea was to aid, was keeping the plastic stirred to aid in a faster and more even melt. Plastic is a great heat insulator and keeping it moving ensures the heat is able to flow evenly and quickly through the entire retort full of plastic.
As mentioned, the turning of the retort was yet another idea, but it posses an even bigger issue of seal. The thing is, the larger and more efficient we want a plant to become, the more complex a system becomes and the result is ever increasing dangers and difficulties to overcome.

[Excalibur]

Excalibur my design is actually a pattern from yours so I would like to ask you
Do you have any problems you think that it needs a mixer?
AND MOST IMPORTANT how do you clean your Retort?
Also I finally found a level switch that can handle 600c yeay

I seriously considered a mixer when I was battling with boil-over problems but it looks increasingly likely that the feedstock was the primary cause so I dropped the idea.
Cleaning a retort that is deep and narrow presents a challenge. When the residue is dry, it will chip/scrape off and get pulverised to a coarse dust. Then I use a vacuum cleaner to suck it out.
Though untested, another thought for the future is to make a tool with the characteristics of a reamer.
The retort looks set to be shortened by a few hundred mm so this will make cleaning slightly easier.
Please share the 600°C level switch.

[chacowako]

Ok thanks for vacuum tip.
I just ordered the switch if it works as it should ill share it.
Wheels keep us posted if you ever get an easy way do get a mixer working. Thanks