How to turn plastic waste into diesel fuel cheaply

[mjohnson1]

I missed your earlier question mjohnson1. I do use a catalyst of my own formulation. It is used in the gas phase.
1 kg of mostly PE with up to 20% PP and PS will yield 1.1 litres of liquid fuel and a small residue of wax in the retort and some gas. If I push the fuel yield up to 1.2 litres I get no residual wax, just a few grams of carbon powder.
My crude fuel is made up of 75% kerosene and 25% petrol ( gasoline). I deliberately avoid producing any diesel fraction although I can if I modify the catalyst.

Very interesting that you have come up with your own formula for a catalyst. Well done.

Are you able to regenerate your catalyst?

I remember you mentioning in an early post that you had tried clay catalyst. Do you still use that with the plastics in liquid/solid form?

[Clintenergetic]

Process with biomass

Great info!

Have you tried it with biomass instead of plastic as you planned to do? If so, how did it work out?

Thanks.

[imakebiodiesel]

Although it would be possible to regenerate my catalyst the amount of heat required, 7 - 800C, would not be practical. It is relatively cheap and so can be disposed of after each batch. 1kg will process 100 kg of plastics.
I have experimented with liquid phase catalysts but found that it only worked with large amounts of catalyst, as much as 30% by volume.. I believe that so called liquid phase catalysts are really working as gas phase catalysts, reacting with bubbles of gas in the liquid as it boils. Plastics in truly liquid form do not have sufficient energy to crack, even with a catalyst.

[Ilunga23]

We made calculations, it turns out that our device, as crude as it is with much room for improvement, can produce diesel fuel at a cost of 17 US cents a liter, that is when only plastic and electricity is considered. The next machine will probably use a liquid fuel burner to heat the reactor, this could lower the costs even more as it would then run on a small percentage of the produced fuel and also the produced gas would then be used more practically - burned along with the fuel to heat the reactor. Even now, if we would get the electricity from a diesel generator that runs on the produced fuel, it would consume about 20% of the produced fuel, but those generators are never efficient and much of the potential power is lost, so heating the reactor using a burner should be even more efficient. Japan produces such units that run themselves using the produced fuel, their machines use 7-10% of the yield. But they cost more than 100 000$ for a unit the size we have. We also calculated all the materials and work involved to make this device and it comes around 1200$, but it is scalable from table top units up to industrial size units that produce several tons of fuel daily.

Here is a video I made and uploaded on a fake youtube account:
YouTube - Easy way to make your own diesel from plastic waste

Hello Jetijs!

Could you give me the schemes and drawings of this setup? And, if available, preliminary theoretical calculations which describe thermal processes inside the unit, which determines the thickness of insulation, and more.

Thank you

[Beyond Biodiesel]

My apologies to both mjohnson1 and drgoldsmith. I got you mixed up in a recent post.
drgoldsmith, in your experiments with glassware does the molten plastic foam up as it approaches the cracking temperature? In my steel retort I only put 1kg of plastic into a retort that could hold 6 or 7 kilos. My fear is the the molten would foam up and possibly block the upper outlet. Of course I cant see what is going on inside my retort so I have to be extra cautious.
Over the holidays I will be testing my larger retort. Its maximum capactiy is about 75kg but i will only half fill it for the first few batches.

Running a pyrolysis unit in glassware is highly instructive, and it is useful to do so to observe the process, but I believe the temperatures required for cracking make it necessary to quartzware, which is exceptionally expensive.

When I designed my pyrolysis unit I expected that the longer the hydrocarbon chain the larger the bubbles are, so, like you, I planned for a lot of head room. I think it is just a good design idea. The extra headroom can accommodate refluxing materials, as well as catalysts, and reduce boil-over.

So, in my pyrolysis unit I fill the excess headroom with refluxing medium which not only promote reflux, but it also promotes cracking, and it reduces boil-over by breaking the bubbles up as the rise up into the refluxing zone.

The other option is for the refluxing zone to be especially large, but I think it is easier and cheaper on a small scale unit just to consider filling ti half-way, as you are doing, and fill the top half with refluxing medium; and this is what I am doing. The results are I get little boil-over, and I get some cracking without the use of a catalyst.

[DrGoldSmith]

info, answers

IMBD, no worries, its difficult to keep track of all the info, names and tangents.

Sorry i have been away for a week or so and i believe that there are some outstanding questions and some added info that i think may be helpful so here goes-

First, the amount of feedstock that you put in the boiling flask (reactor) is critical (as i learned early on the hard way). Its best to only fill the reactor less than halfway and even better if only 1/4 from the bottom. The boiling flask is designed to retain the contents during boiling, hence its shape. This seems to help prevent boilover. I typically do not see more than 1/2 of the reactor fill with a thick bubbling foam and a there is a lot of heavy white 'smoke' that comes off for the first few mins.

Next, its is very important to use silicone stoppers. The standard rubber stoppers simply do not holdup under the intense heat. The stopper also acts a pressure relief valve... if too much pressure builds up in the reactor the stopper will pop off... this can be an issue especially if the heat source causes the reactor to ignite, however it is usually easy to extinguish but this tends to ruin the run and you will need to remove clean and restart the entire process.

It is necessary to consider the heat requirements when specking in all of the equipment. The glassware must be able to sustain the temperature, however, if you are using boiling flasks they are made for this purpose and unless they are of a 'toy' variety they are most likely made of Pyrex or a similar type of high temperature glass. The one thing to keep in mind here is the cooling of the boiling flask... it is necessary to gradually cool them or they will crack.

I have considered possibly putting a 'kit' together and making it available on ebay in order to help save people time and effort sourcing the individual parts from all of the different sources and from wasting time and money on the trial and error that i have already done. If there was enough interest in this i can look into it more and see if we could get a quantity discount in order to make this a good thing for everyone.

If i missed anyone's questions or if there is more that you would like to know feel free to ask and i will do my best to answer as soon as i can.

SY

[Beyond Biodiesel]

...First, the amount of feedstock that you put in the boiling flask (reactor) is critical (as i learned early on the hard way). Its best to only fill the reactor less than halfway and even better if only 1/4 from the bottom. The boiling flask is designed to retain the contents during boiling, hence its shape. This seems to help prevent boilover. I typically do not see more than 1/2 of the reactor fill with a thick bubbling foam and a there is a lot of heavy white 'smoke' that comes off for the first few mins...

SY

Thanks, Sy, this supports the idea of half filling the retort, and leaving the upper half as a refluxing zone, which could be packed with something that is highly conductive and highly porous, such as steel wool, or metal chips from machining, or broken terracotta tiles.

I have filled my retort with metal chips from machining from bottom to top. They seem to work as boiling chips on the bottom of the retort, and reflux on the top.

[imakebiodiesel]

Thanks for your reply drgoldsmith. Beyondbiodiesels suggestion of boiling chips has interesting possibilities. If a quantity of small pieces of broken pottery or brick was placed in the bottom of the boiling flask it might reduce boilover. I cant really test this with my steel retort. Perhaps you could give it a try. The clay pieces might also have a weak catalytic action.

[imakebiodiesel]

I have discovered a novel use for the residue left over from my process,
It consists of 90% hydrocarbon wax and 10% carbon black. It is in fact a common household product found in almost every home, can anyone guess or work out what it is?

[mjohnson1]

I have discovered a novel use for the residue left over from my process,
It consists of 90% hydrocarbon wax and 10% carbon black. It is in fact a common household product found in almost every home, can anyone guess or work out what it is?

I'd guess a candle?

[Beyond Biodiesel]

I have discovered a novel use for the residue left over from my process,
It consists of 90% hydrocarbon wax and 10% carbon black. It is in fact a common household product found in almost every home, can anyone guess or work out what it is?

Would that be boot black/shoe polish? Although it could also be a candle after it has been burnt, or maybe a black candle.

Sy, I was a little concerned that Borosilicate Glass (aka PYREX) could handle the temperatures of a retort. I know I used it in several fractionation columns, while doing post graduate work at Chevron Research back in the 80s, but I cannot recall using it as a cat cracking retort, although being able to see how the cracking and refluxing is working would be really instructive. I also recall how easy it was to shape with nothing more than a propane torch, so I looked up the MSDS for it, and found its melting point is 821C (1509F), so it is good for our use in pyrolysis.
PYREX MSDS

[imakebiodiesel]

The prize goes to Beyond biodiesel, yes, its black boot polish and its very effective.
Pyrex should be ok but I think the silicone bungs would last for only one use. the temperature at the top of my retort reaches 420c towards the end of a batch. Most silicone rubber has a safe limit use of 300C although I believe a higher temp type is available.

[Beyond Biodiesel]

The prize goes to Beyond biodiesel, yes, its black boot polish and its very effective.
Pyrex should be ok but I think the silicone bungs would last for only one use. the temperature at the top of my retort reaches 420c towards the end of a batch. Most silicone rubber has a safe limit use of 300C although I believe a higher temp type is available.

Yes, I agree, after I posted my response above I started thinking about those silicone rubbers that are common on lab glassware, being a series problems at our operating temperatures.

The glass fractionation columns I operated had o-ring seals in between the sections, and teflon o-rings could be used, but in either case they are really only good up to 400F (200c).

We used to use a boiling flask with an especially long neck on it, so that the boiling zone could be taken up to 800F (425c) while the stoppered end would be cool enough for a stopper, or an o-ring connection to the fractionation column.

[imakebiodiesel]

If you could get those boiling flasks with very long necks, you could use the neck as a reflux column so the first silicone bung would only have to withstand 260 -330 degrees C. This is just about within the safe limits for silicone.

[imakebiodiesel]

This kind of flask could work. see the ebay link below.

Pyrex 125ml Glass Distillation Flask Laboratory ASTM E133 Lab Boiling Engler NEW | eBay