How to turn plastic waste into diesel fuel cheaply

[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.

[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

[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.

[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]

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

[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.

[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.

[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.

[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

[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?

[wheels]

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?

You can do either with the water. For most, just static if fine.
I am not sure how you would smell HCL. HCL is the gas form of Hydrochloric Acid and you would choke rather than smell anything. It is highly dangerous and can burn your skin, eyes and throat if you inhale it. It will also eat your retort vessel quickly. HCL at 300deg is serious to Metal.
HCL comes from plastics that contain Chlorine. That is PVC plastics. PVC is used for electrical cable insulation for instance. So I would check that your Plastic stock is pure PP/PE.
To test of Acid is present, get yourself a cheap and swimming pool test kit. It is simply some little strips of Litmus paper. Test the water before use to get a bench mark and then after the process and see how strong an acid the water has become. The water will take out most of the HCL if it is present.

[dedooo]

But what about the catalyst, is there again, I've tired of wax, you benefit Perlite in this regard ?, Thank you all

[wheels]

But what about the catalyst, is there again, I've tired of wax, you benefit Perlite in this regard ?, Thank you all

Wax can be caused by several things.
First of all, the plastic itself. Wax is produced from Polyethylene. The simplest fix, to process only Polypropylene. If that is not possible, then try temperature. Wax is found in a narrow band of the hydrocarbon range produced. What range of Hydrocarbons your plant produces is firstly related to Temperature and Time. Time cannot be controlled so easily, so that leaves Temperature. You need to experiment with Temperature. Most lower the temperature, but that may not be the answer. So also try raising it. As both Temperature and Time are related the Hydrocarbon produced, either raising or lowering will alter the time and thus the cracking and thus the range.
Catalyst. This is the hardest part to play with. A Catalyst causes a Chemical reaction, but it does not get consumed in the process.
Actually, this is a complicated and important subject and I shall post a separate post following this one, to keep the subject separate and easy to spot.

[wheels]

Catalyst.
I need to go back a step.
We are playing in the World of Petrochemistry and causing a form of Chemical reaction. To explain, Fire is a Chemical reaction. The material burning is being consumed by rapid oxidation. Oxygen is reacting rapidly with the material being consumed and the result is Heat being produced. We have three components to the Reaction. Heat, Fuel and Oxygen. Take any one of those away and you cannot have Fire. Hence how a fire extinguisher works.
In our case, we are the ones providing the Heat energy and we are simply heating the plastic to where the Hydrocarbons the plastic is made up from are released and then those chains, via being "excited" by the heat energy, break apart to create shorter chains.
The term Hydrocarbon, comes from what these chains are made up from. Hydrogen and Carbon Molecules bonded together in lengths. When they are heated, they are caused to vibrate and that vibration can cause them to eventually break apart into two shorter chains. The shorter chain requires even more energy to break again, so breaking by heat tends to be a little more precise in what they break into, although the breaking point can be a little more random. It is however, somewhere towards the middle of the chain. Thus a long chain can be broken somewhat into a chain ruffly half it's length.
Another way to break the Chains is to force them to break, by removing a Molecule that joins the chains together. In this way, we are using something to cause them to break, which is normally a chemical reaction. It s possible to drop a Chemical into the Hydrocarbon mix and cause them to break at a specific place. But that is hard to do. So an easy way of doing it, is to use a Catalyst. A catalyst works on a two step process. Firstly, it gives up a little of itself to cause the reaction. In our case, the Hydrocarbon chain is broken by an Electron attracting an electron in the bonding molecule and thus the molecule can no longer hold the chain together. The second part of the process is that the electron is then taken back by the Parent catalyst material, called Regeneration and is thus the Catalyst is not consumed. But for the Catalyst to work, we need to provide the heat energy to make it work.
Another aspect of a Catalyst is what material causes the Hydrocarbon to break where we want it to. In our case, a form of Zelolite tends to be best choice. There several different types of Zeolite by the way. They all work, but some work better than others. The Hydrocarbons need to flow over or through the Zeolite particals and the temperature needs to be high, well over 400 degree to operate. The problem with using a Catalyst is that it causes the Hydrocarbon chain to break into three parts. It is far more accurate, because it tends to break in the same place for all Chains. but the three parts are not always wanted. Usually only one part is wanted and the other two shorter parts tend to be open chains. That means they want to grab another molecule to close the chain and that tends to be Oxygen. This causes Oxygenation of the captured liquid.
The design of the catalyst chamber, how the Vapor is moved through the material, the heat etc etc are all important to how well it works. So while ot is likely doing something, it may not be doing it well and so it is not as easy as it sounds.
I hope that helps.

[Excalibur]

But what about the catalyst, is there again, I've tired of wax, you benefit Perlite in this regard ?, Thank you all

Deedoo, to help solve your wax problem, please post some clear photographs of your machine. Also dimensions, operating temperatures of retort, reflux etc. and burner/heating details. There are many on the forum with vast combined knowledge but without information we are only guessing.