How to turn plastic waste into diesel fuel cheaply

[Uncorruptable]

I have just gotten through all of the thread, pretty hard to retain all the info in one sitting so i will do a job on the thread & compile all the text into one document for ease of reading at lesuire,

Regarding this set up below,

The schema is attached in jpeg format

I am looking to use this reflux column as it seems it would be very efficient space wise (i dont have a huge amount of space)

Let me ask a question, the three stages of the column are condensing the vapours at seperate temperatures to obtain the different desired fuels, i recall reading from IMBD that for diesel the temp should be 160' in the reflux to condense diesel, what are the temps in the other two sections of the column to be at?

Also, what is the best way to regluate the reflux over the space of the column? One cooling coil at the head with adjustable temperature liquid circulating & the reactor temperature then also adjustable bbetween 300' & 450'?

What is residence time?
Our 50 liter reactor took about 4 hours at 12kw of power to fully finish and yielded around 28 liters of diesel. At higher powers the time is reduced. 75% of the time is spent just to melt the stuff, when it starts boiling, everything starts going really fast. The times depend on the input powers, device design and needed liquid fraction. Gasoline will take more time, parrafins and waxes much less time.
Hope this helps.
Jetijs

I was looking at modifying an old cooker to use as heat source, the two heating elements contained within the cooker (Grill & Oven) are 2000w each, the two front rings on the top are 2000w & the two back rings are 1500w, thats a combines total power of 11000w.

Is it possible to detach the elements & rings from there supply & fit suitable coils to the power supplies which you then have very good control over to heat the reactor temp to a specific temp?

You would have 6 potential dials to increase or decrease any given element?

Does this sound like something that can be done or are the fitting no adapatbale on a cooker?

I have used broken terracotta as a catalyst and got good results from it. Its difficult to be exact about the temp of the reflux column. Remember that it is doing two jobs.
reflux column. The crucial temperature is the very top of the column. If you hold this temp at say 200c then any vapour that condenses above 200c will form a liquid and trickle back down into the reactor to be cracked again. The selected temperature will affect the eventual fuel mix.
catalyst column, in this role the temperature of the clay pieces are important. each catalyst has a different critical temp, too high and it will coke quickly, too low and it just wont work.
It really is a matter of try it and see. Also its very important to keep notes of the results. After you have done 20 or 30 experimental "burns" its very difficult to remember the early results.

I think i covered it in the question above, what are the three desired temp stages if i were to build a reflux column like the design above in order to condense the vapours at each stage, trail and error will be the only way to finally acchive it in each section, just need to know what they are.

I have not read every page on this thread, but i have read quite a lot.

The issue regarding the displacement of O2 prior to beginning, would it not be feasible to have an inlet valve located in the upper region of the reactor lid that bbefore heating any plastic you could run a pipe onto it feeding from an exhaust of car/generator for a period of time, this would fill the chamber with Co2 prior to any heating being initiated.

Having finished out the thread, it appears that my post above here only matters if it is a coninous fed system, the small amount of oxygen in the system can be pushed out by adding water, yes?

Anyone offer a guide as to quantity of water to plastic ratio?

How much would you put in to clear the O2 but not be a problem?

`A neater way to achieve the same result is to add a small amount of water to the waste plastic. This will boil long before cracking begins and evacuate any air in the reactor.
What Beyond Biodiesel proposes is to purge the whole system continuously with an inert gas.
.

Finally, i read a good few pages back you were using a mixture of plastics, what is the viability of using the likes of industrial shrink wrap, clear plastic bags & strapping like below,



The bags would be baled into compressed bales with a baler like this,



There would be an amount of O2 still in between the bags but this should not be an issue if melted slowly, should it?

[maggs]

is biodiesel an acid or a base
and also is diesel an acid or a base

[Beyond Biodiesel]

This may sound like an oversimplification, but would it be possible to remove the C by Reduction, (which is the reverse of Combustion) by heating the catalyst chamber while running CO2 and H2O through it? The result would be H2 + CO, which is combustible. In fact, if clean enough, it can run a spark ignition internal combustion engine, but for the purpose of practicality, the gas can be flared off. I'm not experienced in this field, so please feel free to critique this idea, and thank you all for this great forum

Marso Green

Interesting idea, Marso, I guess it would be especially useful if you had a use for gaseous fuels, such as running it through a gas powered electric generator. That would certainly keep making power instead of just venting off the CO2.

Uncorruptable, the drawing that you posted is in error. The reflux column should precede the condensers, and should be at the same temp the retort is. The condensers should be in series, not parallel.

On Cat Cracking, there are too many problems with cat cracking, and too little benefit from it, for it to be useful for small scale cracking. Just stick to thermal cracking and you will live long and prosper.

[Marso Green]

Since thermal cracking is less problematic, would it be suitable to build a small scale rectifying column, where temperature is progressively lower as the gases rise in elevation? With some experimentation, would it be possible to identify the location of the temperatures that are of interest, and locate a drain for the distillate? This would essentially be the equivalent of condensers in series, that are placed vertically, hence minimizing heat waste.

Would that make sense or am I off base?

Thanks

Marso Green

[thissideup]

The reflux column should precede the condensers, and should be at the same temp the retort is. .

The same temp as the retort? isn't the purpose of the reflux column to condense the gasses that condense at higher temps, so they may flow back into the retort to recrack? if the reflux column is the same temp, how would this happen?

[thissideup]

Regarding thermal cracking, as apposed to using catalyst, those of you who are cracking plastic, where are you finding your wax after the fluid cools? in the heavy or lighter fractions or is it evenly distributed among all fractions? I intended to use bentonite, ( kitty litter ) as catalyst, but am not against keeping it simple.

[Excalibur]

Fuel tested

My fuel was tested today. I run a separate fuel line to and from the injector pump of my Toyota diesel. As expected it had light fractions mixed in and it caused some running issues. The injector pump was showing a lower pressure than on it's normal diet. The fuel was noticeably thinner so little wonder really. Also it wouldn't restart after sitting for 30mins. Observing the return line, a lot of bubbles were coming out at this stage.
I then quit the test, removed the temporary fuel lines and poured the last of the fuel into the vehicles' diesel tank, diluting the fuel that was already there, a WMO blend. This improved the power I normally get so I'm satisfied.

[Uncorruptable]

Since thermal cracking is less problematic, would it be suitable to build a small scale rectifying column, where temperature is progressively lower as the gases rise in elevation? With some experimentation, would it be possible to identify the location of the temperatures that are of interest, and locate a drain for the distillate? This would essentially be the equivalent of condensers in series, that are placed vertically, hence minimizing heat waste.

Would that make sense or am I off base?

Thanks

Marso Green

Thats pretty much how i thought the pic i quoted above was intending to work,

We build a reflux column that we control the temp in three sections carefully & have a resevoir plate with outlet then in each section to drain off the fuel that has been condensed at its appropriate temp.

All Sounds very easy & sure enough it would turn out very difficult i imagine, but i would be looking to attempt this.

Any thoughts from more expperienced folks?

The same temp as the retort? isn't the purpose of the reflux column to condense the gasses that condense at higher temps, so they may flow back into the retort to recrack? if the reflux column is the same temp, how would this happen?

I also thought it quite a strange comment, the entire purpose of the reflux is to allow prior condensing & redistillation of the vapours before they are actually taken off as product

Regarding thermal cracking, as apposed to using catalyst, those of you who are cracking plastic, where are you finding your wax after the fluid cools? in the heavy or lighter fractions or is it evenly distributed among all fractions? I intended to use bentonite, ( kitty litter ) as catalyst, but am not against keeping it simple.

Could prove very handy in regards ease of acquisition, you could pick it up in any supermarket handy if you need to.

[imakebiodiesel]

It is not a question of using thermal cracking or catalytic cracking. Thermal cracking is the first stage of the process and is essential. Most of us who have built reactors so far have found that thermal cracking alone ( even with a reflux column) will produce a fuel that once it cools is waxy or semisolid. Adding the catalyst promotes the cracking process to produce a stable liquid fuel.
Some one asked is the wax in the heavy or light fractions. Wax IS the heavy fraction.
It would be great if someone could devise a system that achieved liquid fuel with thermal cracking only but so far, to my knowledge, no one has. So for the moment we are stuck with using catalysts.
These comments apply only to cracking waste plastics, cracking or distilling waste oils and other materials is quite different.

[Uncorruptable]

It is not a question of using thermal cracking or catalytic cracking. Thermal cracking is the first stage of the process and is essential. Most of us who have built reactors so far have found that thermal cracking alone ( even with a reflux column) will produce a fuel that once it cools is waxy or semisolid. Adding the catalyst promotes the cracking process to produce a stable liquid fuel.
Some one asked is the wax in the heavy or light fractions. Wax IS the heavy fraction.
It would be great if someone could devise a system that achieved liquid fuel with thermal cracking only but so far, to my knowledge, no one has. So for the moment we are stuck with using catalysts.
These comments apply only to cracking waste plastics, cracking or distilling waste oils and other materials is quite different.

Hi IMBD,

Can you advise, the reflux column i quoted above, is it theoretically feasible to construct a column that has three stages, each stage has its catalyst & reflux packing in its stage to bring the vapours the the desired stage & then drained off from the column via extraction plate as usable fuel?

Also, the metion of kitty litter as catalyst, would this be something you think is good to use?

[imakebiodiesel]

The arrangement you show in the drawing will not work. The fully cracked gases must leave the top of the reflux column and move downwards before being condensed in a series of condensers. The temperature at the top of the reflux must be controlled somewhere between 160 and 260C depending on your plastic mix etc. A three stage condensing tower may work but you wont know untill you build it, better to have 3 separate condensers so you have more control over individual temperatures.
Some of the confusion in this thread is because some people are talking about waste oil distillation instead of waste plastic cracking. These are similar but quite different processes and you need to say which you mean when asking and especially answering questions.
Bentonite is a good catalyst for plastic cracking and has worked well for me. It has a very short active life and only lasts one batch

[Uncorruptable]

The arrangement you show in the drawing will not work. The fully cracked gases must leave the top of the reflux column and move downwards before being condensed in a series of condensers. The temperature at the top of the reflux must be controlled somewhere between 160 and 260C depending on your plastic mix etc. A three stage condensing tower may work but you wont know untill you build it, better to have 3 separate condensers so you have more control over individual temperatures.
Some of the confusion in this thread is because some people are talking about waste oil distillation instead of waste plastic cracking. These are similar but quite different processes and you need to say which you mean when asking and especially answering questions.
Bentonite is a good catalyst for plastic cracking and has worked well for me. It has a very short active life and only lasts one batch

Thanks for your reply,

I am talking about plastic cracking, my understanding (which may be completely wrong), different temperatures will give us different fuels when the gas condenses, correct?

This being so, what i am saying is, if we can control the temperature in each stage of the column will it allow the vapour to condense at a particular fraction in that section to be a desired fuel?

[Beyond Biodiesel]

Since thermal cracking is less problematic, would it be suitable to build a small scale rectifying column, where temperature is progressively lower as the gases rise in elevation? With some experimentation, would it be possible to identify the location of the temperatures that are of interest, and locate a drain for the distillate? This would essentially be the equivalent of condensers in series, that are placed vertically, hence minimizing heat waste.

Would that make sense or am I off base?

Thanks

Marso Green

A properly designed reflux column is also a fractionating column; however, there is a crucial component left out of the discussion here. The sections of the distillation column typically have an aluminum collar separating one fraction from the next. That collar has a lip on the inside which collects the condensate as it drips down the walls of the distillation column. There is also a tap there where the collected condensate drains off to a collection container.

The problem with the typical design of a refluxing distillation column is they can easily be several stories high, I solved both separating the sections and the height problem by folding the sections of my condenser system.

Folding the sections of my condenser system meant that I had to have a separate sample collector at the bottom of each section.

The same temp as the retort? isn't the purpose of the reflux column to condense the gasses that condense at higher temps, so they may flow back into the retort to recrack? if the reflux column is the same temp, how would this happen?

The first stage of the distillation column should be held at the same temperature as the retort. This prevents boil-over from entering the distillation column.

Thanks for your reply,

I am talking about plastic cracking, my understanding (which may be completely wrong), different temperatures will give us different fuels when the gas condenses, correct?

This being so, what i am saying is, if we can control the temperature in each stage of the column will it allow the vapour to condense at a particular fraction in that section to be a desired fuel?

That is precisely how it works in a commercial distillation tower; however, each section of your distillation tower must be efficient at getting the vapor fluid stream to the temperature of the cut.

[Uncorruptable]

That is precisely how it works in a commercial distillation tower; however, each section of your distillation tower must be efficient at getting the vapor fluid stream to the temperature of the cut.

Thank you BBD, it wwould be a very neat and efficient design if it were possible to achieve.

Can you give me the correct condensing temps for each fuel please for each stage of the column?

[Uncorruptable]

Hi Everybody,

After looking for a good while over the net it appears to be hard to find the right condensing temps for the three fuels i asked about.

The closest i could seem to find is,

1. Diesel - 160'c
2. Kero - 100'c
3. Gasoline - 60'c

Can someone confirm this is accurate please?