How to turn plastic waste into diesel fuel cheaply

[rozier56]

rozier56

When running plastics{pe +pp} at temps around 300*c we are experiencing the smell of HCL fumes in the air, out the exhaust pipe. When the gas is burnt off too atmosphere they obviously disappear. We are not running the gas through water trap as in the passed.The water traps used, are they static vessels that are circulated with water constantly,or static vessels that you change the water daily?

[Babataku]

Not so easy

Wheels,

I agree with you. This is NOT easy at all. Especially if you are thinking of commercial (1000Ltrs + per day). I would advise on small scale units for making fuel for own use maybe 50Ltr - 100Ltr per day runs.

I have been doing this for the last 2yrs and I'm still learning. I wanted to go commercial at first but have back tracked and changed my mind, a lot can go wrong. Maybe in the future when I have gained more Experience

[wheels]

Summing up thus far.

Thinking back on my Posts of late, I seem to keep making one common statement. "The answer is varied and complex" or at least something along that line.
If we go right back to the beginning of this thread, Which was ruffly 4 and half years ago and over 4000 posts later, the entire story started off with a very simple contraption of a vessel, that was very simply heated, plastic added and melted, a cold vessel to capture condensate and a pipe joining the two together.
But over time, this has all evolved to the point of where the we now have quite complex processes. Which on one hand is great. It show's that the "hobby" can be as simple or as complex as one wants to make it. But the fact that it has evolved to the complex end for many, goes to show that to make a safe and useable fuel is not quite as simple as the very basic of hobby plants can produce. A member or two that had taken these basics and tried to go to commercial scale have found out the hard way that this is no where near as simple as they thought. With increase in scale comes increase in complexity. Not to mention that after completion of a Run, they are left with an enormous amount of waste material that needs to be removed and disposed of. I know of one commercial size plant that went bust on it's first few runs, simply because no one had understood the difficulties of cleaning the waste from the huge retort. The Plant was processing Tyres and the waste amounts to about 50% of the volume of Tyres. So 10 tonne of Tyres leaves behind some 5 tonne of Carbon waste. Under the OSH laws, the company had to hire a specialist Hazardous Waste removal firm and of course, the cost of that was something never budgeted for and the Company could not sustain itself.
For us, we don't have those concerns on that kind of scale. However, our journey here has raised the level of difficulty. We have pushed the concerns for safety and I think the vast majority have improved their designs to meet concerns. Safety is not just the risk of Fire and/or explosion, but the Fumes/Gasses are highly toxic. The waste can be Toxic and an extreme hazard and must be disposed of safely and correctly. The fuel must be cleaned and often distilled further to meet the fuel requirement of the Vehicle. Not so much a problem for old clangers of engines, but I would be very reluctant using these Fuels in modern engines if the Fuels have not met proper specs and totally clean.
There are three main aspects, with several smaller branches of each, to this entire process.
First is to ensure the right Plastic Stock is obtained, that it is as pure to the particular type required (either or both PP and PE) and that it is clean.
That the Retort Vessel and associated heating equipment is well built and safe to operate.
That the Condensing equipment is well built and well designed (because this is what creates the type of fuel you require).
That you have good filtration, so as you ensure clean fuel running through a very expensive, highly precise Fuel system.
It can all be fun. But it is also no where near as simple as many have thought and thus no where near as cheap as many had thought. The age old saying of "You can't get something for nothing" is a very true statement, even for this. Although, this process is the only one I know of where you really can get more out of than what you put in. That includes your Time, perhaps investment and the energy obtained.

[wheels]

Less reflux temperature equates to a lighter fraction produced. Logically reflux temperatures should be between 320°C - 350°C. Ultimately the temperature is determined by the Operator and based on the weight of fraction exiting the reflux.

The answer is varied and complex. The first question (Rhetorical = does not have to be answered) is how complex is the distillation part of your Plant? The Reflux should be considered as the very first part of your Distillation system. We don't have a need for very heavy weight fractions, such as heavy Oil and Tar. So those, via the reflux unit, are dropped back to the Retort to be heated again and cracked to a shorter chain length.
The next question is, how many distillation Pots do you have? One single Pot that captures all is fine, but it means you capture all condensable liquids and thus you Reflux temp needs to be more precise and controllable. Multiple Pots allows the use of electrical elements on each a precise temperature control and thus the liquids can be condensed into a more accurate range. Thus the Wax can be isolated and sent back to the retort the next time you make a run.

[Excalibur]

Less reflux temperature equates to a lighter fraction produced. Logically reflux temperatures should be between 320°C - 350°C. Ultimately the temperature is determined by the Operator and based on the weight of fraction exiting the reflux.

[dedooo]

If we return to the question what is puzzling is how efficient and effective to get rid of wax? Thanks very much

[Excalibur]

Hello all, I have a question, do you think that reflux is able to save us from the wax, if only we used polyethylene? Thank you all.

You will get wax without effective reflux capability. Reflux is the mechanism and the means by which heavy and light fractions are separated.

[dedooo]

Hello all, I have a question, do you think that reflux is able to save us from the wax, if only we used polyethylene? Thank you all.

[kenssurplus]

Wheels, Excalibur,

Thanks for the replies, and for taking the time to consider my question. My curiosity and my recycle / repourpose bug has been satisfied for now.

It looks as though my saving up plastic will continue for a while longer before I weld something together.

Thanks again,
Ken

[Excalibur]

Hi All,

Top notch information and people in this thread. I have read through this monster of a thread over the past few years, and recently searched for any post about using Mother Earth News' gasahol distillation unit. Not finding anything posted about this, my question is: Do you think these plans can be easily modified for a plastic pyrolysis unit?
What parts of the plans can be used as is without modification?

I see in the plans, sections filled with marbles, and coiled copper tubing cooling sections. I suppose that all these sections necessary for gasahol production, would be in the way and just clogging up the works so to speak.

Much of won't it apply. At best you might be able to glean a few ideas.
There's a big difference in heat requirement, about 5 times so their equipment won't be nearly robust enough. Copper isn't something I'd recommend either, even for condensers. Condensers filled with marbles has some good potential though I've never tried it.

[wheels]

Hi All,

Top notch information and people in this thread. I have read through this monster of a thread over the past few years, and recently searched for any post about using Mother Earth News' gasahol distillation unit. Not finding anything posted about this, my question is: Do you think these plans can be easily modified for a plastic pyrolysis unit?
What parts of the plans can be used as is without modification?

I see in the plans, sections filled with marbles, and coiled copper tubing cooling sections. I suppose that all these sections necessary for gasahol production, would be in the way and just clogging up the works so to speak.

Any insights would be appreciated.
ken

It's a similar method, but a very different product and thus very different parameters and processes.

[kenssurplus]

Convert Mother's gasahol unit for pyrolysis

Hi All,

Top notch information and people in this thread. I have read through this monster of a thread over the past few years, and recently searched for any post about using Mother Earth News' gasahol distillation unit. Not finding anything posted about this, my question is: Do you think these plans can be easily modified for a plastic pyrolysis unit?
What parts of the plans can be used as is without modification?

I see in the plans, sections filled with marbles, and coiled copper tubing cooling sections. I suppose that all these sections necessary for gasahol production, would be in the way and just clogging up the works so to speak.

Any insights would be appreciated.
ken

[Babataku]

cast iron

Thanks for the replies.

Will search for some scrap SST and some firbricks too.

[Excalibur]

Cast iron would be more resistant to heat. For stainless, try a scrap metal yard. Best would be refractory brick so look out for old log-fire boxes. These have thin refractory tiles lining their mild steel fireboxes. Ones I've seen are about 1" thick and are a proper firebrick.

I've only fired the rebuilt firebox set up once so far and I was constricting the flame temperature to below 800°C during warm up. This took longer than before, somewhere over 2 hours but also there was some breakdown repairs to attend to. However I was heating a full retort perhaps 40L feedstock. The insulation needs improving as well. Fuel usage was not recorded. Logically the refractory will take longer to heat up but then it will hold and release heat a lot longer as well.
Where firebrick refractory could work nicely is at the conclusion of a run. With flame shut down, residual heat from bricks would ensure the retort dried out completely.

Anyone considering alumina refractory bricks should note there are 2 types. Light weight brick which has good insulating quality and heavy dense type which is better at heat storing. Ordinarily one would choose the brick to suit the work and have the character intended. At first I couldn't decide which would be better but dense bricks turned up for free so that's what I'm using.

[wheels]

Thanks for the replies.

I was thinking of using Cast iron for the Firebox. I'm not sure though how this will affect time to heat up the retort and if this will solve steel oxidation problem. Has anyone tried this out? I don't have any local suppliers for stainless steel.

And also Excalibur, using refactories and creating a flame path like you did...how does this affect heating up time? Do you use more fuel to get to temperature and maintain that temp? And by the way on your runs how long does it take you to get to 400deg?

Cast iron is good. It is much slower to rust away. For SST, also consider scrap items like heat shields in old appliances. Toasters, Heaters etc. It does not have to be thick metal.
I have the Diesel heater blowing the hot air around the retort. I have spirals around the retort so as the hot air is swirled around and up to the exhaust outlet, so ot creates a more even heat distribution. The other jacket is insulated to retain as much heat as possible inbetween the two steel vessels.