How to turn plastic waste into diesel fuel cheaply

[mortimer.dan]

Polypropylene Recycling to Fuel

Dear Sir, Thank you for your great information report in Pyrolysis of waste plastics. I am keen to hear if you have any more experience recycling computer plastics, does this extend to old tv plastics. How does one test a plastic to see if it indeed polyproplene, do you know if there is any easy test. You mention brittle plastics, is this a good general test. A lot of plastic storage boxes break and are discarded, are these potential for the plastic to fuel. Thanks Daniel

[Col]

catalyst to suit desired fuel profile

mjohnston1 commercial FCC is incredibly active and even after it is "spent" by refinery standards it would overcrack in our process. However it could be a useful starter ingredient in small amounts. Natural zeolites and similar minerals would be classed as medium activity, air dried clays as low activity and fired clays as very low activity. A mixture of these will produce a catalyst with the profile to suit what you need.[/QUOTE]

Hi IMBD - sorry to ask you to spell it out but do we need a percentage of our catalyst to be a highly active one to get the cracking started, and then let the less active catalyst/s take over? or can we just use 100% of any catalyst and have more patience? (and use more heating fuel in the process).
Does the 'activity' of a catalyst refer to the SPEED of the resulting cracking process or the LENGTH OF CARBON CHAINS the cracking reaction will produce when using that particular catalyst?
As I am after diesel I expect I could just use 100% fired clays, stated as having very low activity, and condense the longest possible chain lengths depending on my reflux temperature. Obviously an oil molecule cut into a diesel molecule will also produce an offcut of naptha or gas as a by product so yield of these shorter molecules will also increase.
Thanks!

[Col]

Adding catalyst part way through, as above

Hi mjohnson1, does that sound ok to you? Do you see any complications with this? (aside from the extra heat sink of the catalyst chamber being introduced to the system part way through a batch, I guess I should pre-heat the catalyst chamber).

[Col]

Target fuel profile and catalyst preservation

Hi IMBD
That's along the lines of what I was thinking, thanks! Might still be able to use just one refluxing column - by using simple valves I could redirect the vapours through the catalyst chamber then back to the refluxing column if it was set up right.

[mtrans]

HI ALL,
I just came back from a scrap yard and got 2 rear brake drums

Not easy to weld,in my case.

[imakebiodiesel]

Col, your idea is an interesting one and may work with wmo if you can switch to catalysis without having to reheat. Perhaps a retort with 2 reflux columns one with catalyst and one without. Once the process has gone far enough without catalyst switch over to the other one.
However this may not work with plastic as thermal cracking alone produces mostly wax and gas.

mjohnston1 commercial FCC is incredibly active and even after it is "spent" by refinery standards it would overcrack in our process. However it could be a useful starter ingredient in small amounts. Natural zeolites and similar minerals would be classed as medium activity, air dried clays as low activity and fired clays as very low activity. A mixture of these will produce a catalyst with the profile to suit what you need.

[rozier56]

Derek

Hi jetijs,did you ever think you would spawn something this big? Well done to you and all the contributors.
it has been two weeks of intensive reading and taking notes.
NOW I WILL START TO LAUNCH MY PROJECT BUILD!
What determines a junior/senior member?
Hope to contribute some positive news to this thread.

[Ron Hammar]

Mjohnson1,
I am wanting to make gasoline and would like to know just what type of catalysts is it that you use to get this?

Thank you

I finally got around to testing out a batch of my new catalyst and I wanted to post my results here-

Conversion rate:73% to liquid fuel (have no way to measure noncondensable gasses but significant "smoke" was coming out)

Fuel composition-
89.5% gasoline
8.9% kerosene
1.6% diesel

No waxes.

This is far from ideal as I want a conversion rate to fuel of ~90% with the remaining ~8-9% to be gasses to power the unit.

[Ron Hammar]

HI ALL,

I just came back from a scrap yard and got 2 rear brake drums that have disk rotor and a drum for the emergence brake. I am going to use them for the opening of my boiler to add my plastic into the unit. The drum has a inside lip on it about a 1/4" hi and what I was going to do was take it to a brake shop and have them turn it down on their brake machine. Have them take off the lip on one drum with a 45* angle on it and then drill holes through the rotor for my bolts. This will make it so when I put the bolts on and nut them down the one drum will be pulled down into the other and should seal it. This is a simple way to make it like Jetis seal. It cost about $5.00 for it all.

[mjohnson1]

I expect there is a tendency for single-ingredient catalysts to preferentially react with particular molecular lengths. But could it be said that most catalysts will cut whichever hydrocarbon molecule bumps into it?
I am after the diesel fraction. So if I want to minimise the off-gas and naptha fractions wouldn't I add the catalyst to the retort / reflux column only after all the fractions down to diesel have been distilled off? I will use WMO as feedstock so I only need to boil / distil off the fractions down to diesel, then add the catalyst to the system to cut the remaining longer oily molecules into shorter ones. This way I prevent my target fuel profile from bumping into the catalyst and being cut into naptha and off-gas.
Does that sound reasonable?

That would be a very inefficient way of going about it as you would need to cool down your reactor once you want to add in your catalyst. Adding in a catalyst while the system is running complicates things.

Your best option is to find a catalyst that gives you the fuel profile you're looking for. Or like imakebiodiesel mentioned you can mix and match various catalysts.

[mjohnson1]

imakebiodiesel,

I've looked into the spent catalyst that you speak of but everything ive read says it produces too much off gas/light fractions. I managed to secure a sample and my tests matched those claims.

It never crossed my mind to mix catalysts together. Sometimes the simplest ideas escape my mind.

I was mainly referring to the percentage of off gases generated as I feel it is better to get 80% liquid fuel and 10% off gases when running a continuous unit because the off gases can be used to help maintain the temperature in the unit.

Everyone here is running a batch system, myself included, so the off gases will be somewhat wasted.

[Col]

Targeting a particular fuel profile

I expect there is a tendency for single-ingredient catalysts to preferentially react with particular molecular lengths. But could it be said that most catalysts will cut whichever hydrocarbon molecule bumps into it?
I am after the diesel fraction. So if I want to minimise the off-gas and naptha fractions wouldn't I add the catalyst to the retort / reflux column only after all the fractions down to diesel have been distilled off? I will use WMO as feedstock so I only need to boil / distil off the fractions down to diesel, then add the catalyst to the system to cut the remaining longer oily molecules into shorter ones. This way I prevent my target fuel profile from bumping into the catalyst and being cut into naptha and off-gas.
Does that sound reasonable?

[mtrans]

One problem can be the stop-start-stop-start nature of the bubbles.

It`s problem.
I use LPG burner all the time on minimum.

[Beyond Biodiesel]

so what if the boiler is still upright and there is internal heating on the top and the bottom is heated with classic way (fire).

Will this increase heat absorption efficiency ... by much worth ?

If you can work out way to have an immersion heater that can handle the temperature while maintaining a leak tight seal, you will then be only half there, because the retort as a whole needs to be heated to cracking temperature, or otherwise you will just have your boil refluxing off the sides and lid until they come up to temperature. So, I prefer to heat from the outside in, not from the inside out.

[imakebiodiesel]

Mjohnson1, interesting result with the "spent " catalyst. There are many scientific articles about converting plastic to oil using "spent" fuel cracking catalyst from refineries.
I have worked hard to reduce both the heavy and the light fractions in my fuel as I am interested in producing a kerosene,middle distillate, fuel. Removing the heavy fraction is easy and can be done simply by managing the reflux temperature. I have reduced the light fraction by using only enough high activity catalyst to get the cracking going quickly and then depending on a lower activity catalyst for most of the run.
Mixtures of catalysts can be designed to produce whatever fuel profile you want.
Reducing the light fraction also reduces the gas output , in fact when my processor is running at maximum output the gas can barely support a flame in a small gas ring.
I can do better than 90% conversion. If I continue the run to the very end I can get 98% conversion and all that is left is a dry carbon char. However it wastes time and fuel going that far and the residue has no commercial value so I stop at 90%.