How to turn plastic waste into diesel fuel cheaply

[imakebiodiesel]

Large diameter vessels present interesting problems for heat transfer. A large diameter retort will result in being too hot on the outside near the walls and too cool in the middle. A large diameter reflux is the opposite situation, too cool on the outside but with a hot interior. Its just a question of good design.

[waterboost]

Adding bolt on plate flanges is a great idea.

Don't forget... everytime you add a flange, you reduce the heat transfer.... We have one just before the top of the reflux and the temperatures before and after are considerably different...

So... we pre-heat the reflux and start off with it insulated... then the insulation is removed and a cooling fan added....

[placebo]

Hi Everyone,

New here, just reading through the thread (on page 26). Thanks to everyone for their contributions and hard work. Has anyone yet managed to reliably produce diesel for use in any car? or are you all still experimenting.

Will be building my own reactor over the next few months and hoping to contribute my findings\experiences too.#

All the best and keep up the good work - lets stick it to the man!

[Beyond Biodiesel]

Hi Everyone,

New here, just reading through the thread (on page 26). Thanks to everyone for their contributions and hard work. Has anyone yet managed to reliably produce diesel for use in any car? or are you all still experimenting.

Will be building my own reactor over the next few months and hoping to contribute my findings\experiences too.#

All the best and keep up the good work - lets stick it to the man!

Welcome placebo, there are a number of us who are making regular runs, and have used the output from our pyrolysis units to run autos. Some of us are using the same process to process other things into fuel; for instance at this time I am mostly distilling WMO, and using the output both as motor oil, and as diesel fuel.

[waterboost]

PID control help

Hi Guys,

I tried the new auger reactor machine today and it worked... it needs a few mods... one of the easiest mods is altering the PID control settings but there is too many things for my confused mind to cope with....



The basic problem is the oil burner control, it refires the burner too frequently... so I ended up manually altering it so that it had a 100 degrees of cooling before firing again....

Does anyone understand the basics, I keep reading about P, I and D and hysteresis and all the other control factors... how do I make it less responsive?

I think I am using REX C100 PIDs but the manuals vary depending on whether you have a real one or a copy... I'm pretty sure mine are copies...

anyhoo, with competent adjustment it should do the job... but today I had to resort to, manually turning the set points up and down everytime the correct temp was reached...

[imakebiodiesel]

Try this site, on Beaufort is very good at explaining how PID controllers work.
PID - what is it anyway? - PLCS.net - Interactive Q & A

[waterboost]

Derrrr.... My brain has melted, it must be the plastic

Thanks but that doesnt help at... I know what a PID is... I have read pages of waffle... no one addresses the issue of making one rubbish... they all want to tune them to make them better.... its simple... I want the burner to heat up to 400 then let the system cool to 300 and fire up again.... as opposed to what a PID is designed for controlling the temp within 0.1 of a degree regardless of the damage done to the burner firing on and off....

I'm thinking...

P=0 I-0 D=0 Ar=0 r=100 oH=100

[Beyond Biodiesel]

Hi waterboost, I am not sure how sophisticated your PID controllers are, some just go to a set point and that is it. Some will go to a set point for a period of time, before shutting down, others have ramping controles, soak, times, cycles, etc. The manual for your PID should give you programming instructions for that. If not, then you just had a simple PID controller.

Some of use are exploring Arduino computer controllers, which offer the ultimate in control, but are a lot more complicated.

Good luck.

[placebo]

Has anyone thought about or tried injecting small amounts of plastic, say plastic pellets in to a hot chamber at regular intervals. This would negate the need for a
large vat of molten plastic? and could be potentially safer ?

I'm sure we could devise a way of injecting the plastic so no air enters the chamber either?

I've seen this done on youtube with WMO, where pre-heated oil is injected in to a super hot chamber.

Any thoughts, what would be the draw back of such a system??

Regards

David.

[waterboost]

Plastic is injected all the time using augers and heated screws....

You still have to get the plastic in the auger....

My new machine can be continuously fed with shredded plastic...

But, it does need a new 'thing' adding... I have blisters from yesterdays test run... we need an auger to feed the auger otherwise the plastic stays in the hopper.....

Back to the PID controller.... its a really sophisticated one... from china... so the manual is as clear as polystyrene fuel.... it gives you the name of the various parameters... not much use to me....

The PID running the cooling fan is great, but the fan doesnt mind going on and off frequently....

[placebo]

Plastic is injected all the time using augers and heated screws....

You still have to get the plastic in the auger....

My new machine can be continuously fed with shredded plastic...

But, it does need a new 'thing' adding... I have blisters from yesterdays test run... we need an auger to feed the auger otherwise the plastic stays in the hopper.....

Back to the PID controller.... its a really sophisticated one... from china... so the manual is as clear as polystyrene fuel.... it gives you the name of the various parameters... not much use to me....

The PID running the cooling fan is great, but the fan doesnt mind going on and off frequently....

Thank You Sir for replying, your setup looks great. What sort of results are you getting?

What I was aiming at was just injecting a small amount of plastic in to the burn chamber, so effectively there is no molten mass in there at any time, each injection is used up immediately (or even literally just dropping a small load in). There would be no need for a large chamber as small amounts could be burned on a regular basis.

Of course, this would require much more preparation of the plastic prior to inserting in to the chamber but seems a much safer approach?

Am I missing something, would it not be possible to drop small amounts of plastic directly in to the reactor at regular intervals in a vacuum?


Hope that makes sense.

Regards

David

Edit, this is the video I was looking for. If you watch what this guy is doing, he injects the WMO in to the burn chamber rather than having the reactor full of WMO. Surely this could be done with plastic ?

How to make diesel from waste motor oil - YouTube

[waterboost]

Thank You Sir for replying, your setup looks great. What sort of results are you getting?

Excellent...

...What I was aiming at was just injecting a small amount of plastic in to the burn chamber, so effectively there is no molten mass in there at any time, each injection is used up immediately (or even literally just dropping a small load in). There would be no need for a large chamber as small amounts could be burned on a regular basis.

Scary... Burn Chamber? Burning a small amount at a time?

Have we got terminology issues or do you not understand whats happening?

If you run the system on a full vacuum you will vapourise the fuel that wants to condense... the system pushes air out...

If you run the system on a vacuum you run the risk of pulling air in... if you let it fill with vapour ir pushes the air out... the air doesnt explode the fuel... the reactor crackles and over heats and you loose the fuel...

[mjohnson1]

Thank You Sir for replying, your setup looks great. What sort of results are you getting?

What I was aiming at was just injecting a small amount of plastic in to the burn chamber, so effectively there is no molten mass in there at any time, each injection is used up immediately (or even literally just dropping a small load in). There would be no need for a large chamber as small amounts could be burned on a regular basis.

Of course, this would require much more preparation of the plastic prior to inserting in to the chamber but seems a much safer approach?

Am I missing something, would it not be possible to drop small amounts of plastic directly in to the reactor at regular intervals in a vacuum?


Hope that makes sense.

Regards

David

Edit, this is the video I was looking for. If you watch what this guy is doing, he injects the WMO in to the burn chamber rather than having the reactor full of WMO. Surely this could be done with plastic ?

How to make diesel from waste motor oil - YouTube

For plastic, a heated auger feed works well. It has been used on commercial units and I have done a few tests using it.

All i did was buy a 1 1/2 inch auger bit and a piece of steel pipe that fit around it. Cut a rectangular hole in the top and welded on a hopper.

I use a variable speed high torque drill to power it. Make sure you use a purge gas when you use any type of feed system. CO2 or N2 both work well.

You waste a lot of energy heating up a giant mass of plastic and then letting the reactor cool down.

To add on to that, I have come across several journals documenting the increased liquid yields from rapid pyrolysis compared to slow pyrolysis.

[placebo]

Excellent...



Scary... Burn Chamber? Burning a small amount at a time?

Have we got terminology issues or do you not understand whats happening?

If you run the system on a full vacuum you will vapourise the fuel that wants to condense... the system pushes air out...

If you run the system on a vacuum you run the risk of pulling air in... if you let it fill with vapour ir pushes the air out... the air doesnt explode the fuel... the reactor crackles and over heats and you loose the fuel...

Yes, must stick to the right terminology... sorry about that. I mean reaction chamber.

When I said vacuum I meant in the delivery chamber

I've drawn a picture, hope that explains it a bit better. Would welcome comments

[placebo]

For plastic, a heated auger feed works well. It has been used on commercial units and I have done a few tests using it.

All i did was buy a 1 1/2 inch auger bit and a piece of steel pipe that fit around it. Cut a rectangular hole in the top and welded on a hopper.

I use a variable speed high torque drill to power it. Make sure you use a purge gas when you use any type of feed system. CO2 or N2 both work well.

You waste a lot of energy heating up a giant mass of plastic and then letting the reactor cool down.

To add on to that, I have come across several journals documenting the increased liquid yields from rapid pyrolysis compared to slow pyrolysis.

Many thanks for your reply. Your design sounds very promising and well worth investigating.
What about air bubbles in the argur? Does this occur? or is it very minimal?

My idea is not to heat the plastic at all but just to drop it in the reaction chamber via a vaccum chamber on top of the reactor so it just drops down via gravity to the bottom of the reaction chamber so pyrolysis occurs very quickly.

I think this approach would be less dangerous and a smaller reaction chamber would be needed and hence less energy.

I've attached a drawing in my previous post t illustrate what i mean.

Regards