How to turn plastic waste into diesel fuel cheaply

[Col]

cooling condensate and bubbling vapours through condensate

oil has less heat capacity than water, so you will need to increase the surface area of your heat exchangers.

every inch of head increases the upstream pressure, this is why bubble caps are very low profile.

I was considering what material to use to make a shell and tube heat exchanger, like the one Excalibur has made. I figured because standard stainless steel has poor heat transfer properties it would not be the material of choice, and that carbon steel would be better. If you were to use carbon steel, and water to cool the condensate, you would also need to give consideration to water treatment, as for a boiler, to prevent corrosion and other related issues. I expect making the heat exchanger larger and using oil to cool it would require less maintenance. But what about if the feedstock is not pre-heated and you have water in it - will that lead to corrosion in the carbon steel heat exchanger? Any oxygen in the water in the feedstock will pass through the system first, followed by water, followed by hydrocarbons. Perhaps the pipes will not have time to rust before they are coated in hydrocarbon?? I understand there is little to no oxygen content in water above a certain temperature but if you start from ambient temperature then the oxygen has to pass through the system at some point. Does it present a problem?
Does anyone have any experience / feedback on this? I expect the condition of pipes running from vessel to vessel will be in the same condition as pipes in a heat exchanger.

Has anyone tried running bubbles up through the condensing vessel? I am interested to know what kind of extra pressure it creates.

Thanks
Col

[Excalibur]

as l say before my retort tempreture was 316 degrees c and reflux 90 degrees c know i open my retort and find about 6 inch like carbon but not solid from 30 litres waste oil. l am asking this because l like to learn.l was thinking because reflux tempreture is to low and waste oil comes out as gas.

It sounds as though you have a good understanding of the process. With a reflux at only 90°C, any diesel vapors would be excessively refluxing. In order for you to get a usable reflux temperature, the retort temperature needs to be increased. The reason is, vapor from the boiling feedstock carries heat to the reflux. If the reflux temperature is low, vapor will condense there and the liquid will run back to the retort. The fact that it condenses there means it gives up its' heat to the reflux column. It's a fine balance. On the face of it, you have not got enough rising heat in the vapor.

Greetings.... So i was surfing mr Excalibur's website(wich i recommend to all), i was looking at the turk design, when i had an ideea. What if we could use the same sistem, but to pulverize wmo (preheted) on a 400c hot plate, or heat exchanger of some sort. I have made a diagram to better explain my ideea. My main concern is that the wmo will jam the injectors, but maybe if is hot enough it will be thin enough. And if the injectors run on turns, the plate will never lose the temperature. Theoretically...

Spray onto a hot plate idea has been chewed over and over. It has some really good things going for it. One thought is that any condensate refluxing back to the hot plate will need heat compensation. The injector pump shut-off valve could be wired so to cut feed and allow the hotplate heat to recover. It could be a job for an Arduino microcontroller and a MAX31875 breakout board to monitor the thermocouple on the hotplate. The Arduino is infinitely programmable,,,setpoints, time delays, you name it.
BTW, my injectors seized last run. I guess I found their limit. I did manage to fix them but one spring was looking decidedly collapsed.

Has anyone tried running bubbles up through the condensing vessel? I am interested to know what kind of extra pressure it creates.

Not tried but studied the prospect after seeing a diagram of an alcohol still which used the principle. According to the Engineering Toolbox, fluid head pressure calculation is 27.7 inches of water equals 1 psi.

[jonathan]

retort problem

thanks a lot excalibur next time l will try to heat my reflux with electric heater and try to heat my retort 380-425 degrees c. and see what happened.

[knighty]

the reason I was thinking of oil cooled heat exchangers over water cooled is because I was worried about water boiling off when cooling the diesel to @120'C (I'm assuming this is why other people are doing / thinking about the same thing ?)

but... now I think about it some more... I could either run with salt water, or with some antifreeze mixed in to raise the boiling point... or even run at pressure ? (if the water is pumped, this would be easy to do with a pressure release valve on the return to your water storage tank set to the desired pressure)

I guess another option is less efficient heat exchangers ? if they're not as efficient, there can be a larger gap between the hot side and cold side temperatures ?

I was thinking about using a "plumbers delight" heat exchanger, the same as the bio diesel guys use to condense methanol out of there bio diesel when they're bubbling it / after reacting it

Plumbers delight condenser - Biopowered

and/or using some flat plate heat exchangers


anyone know how much vapour to expect from 1 litre of WMO ?


for the dual electric and gas heating...

I was thinking of a tall 8inch pipe for a dual reactor/retort, electrically heated with band heaters... I could run another pipe up inside it, the full length of it, and have the flame at the bottom going up this tube ? (or the heat from the flame anyway)

if I use a venturi to run a vacuum, I could make it dual purpose if instead of pumping water I pumped the final stage / anything that condensed out after the diesel... sucking in through the venturi and mixing with the pumping liquid should be enough to condense anything out of the vapour (I'm half tempted to try condensing the diesel out like this too)

the vent from the tank for that would be the gas supply to the burner (with a mains gas pilot light/flame)

the venturi would also mean I could have a bit of positive pressure for the burner, which would mean I could use an off the shelf burner (probably with a bit of modification)

I'd be happy with about 5litres/hour, 10 would be better

[Excalibur]

knighty
The dual heat reactor/retort idea reminds me of the gas water heaters with the central flue. The one I saw had a neat looking baffle in the flue pipe. The object seems to be to slow the exhaust down for better heat exchanging. I got that baffle before the rest was sent out for scrap metal .I'm going to test it next week in my new feedstock preheater.

The plumbers delight would be fine for cooling the vapor stream assuming it had adequate capacity. One means of control you'll have is the speed of the water flow. A variant I once used for condensing petrol vapor, I set the flow to 'minimum to achieve the temperature target' as a means only to save water.

about 5litres/hour

A reasonable 1st target. You've clearly been thinking a lot about details and that's a good thing. Getting a working machine is more difficult than it looks.
Step by step. Get a small prototype running as a 1st step.

[fox32]

Quote:

I was thinking of oil cooled heat ctor/retort, electrically heated with band heaters... I could run another pipe up inside it, the full length of it, and have the
flame at the bottom going up this tube ? (or the heat from the flame anyway)

This way i created my sistem inspired by a wood fired water heater. Now i would do it different, with the exhaust coming out on one side of the reactor so i could put another door next to my reflux, for feeding cleaning and maintaining so i won't have to get my reflux down(is very heavy), but there are advantages, the flue can be directed to the reflux to heat it. Still youl need some baffle, or corkscrew inside the heat exchanger to be more efficient. And the welds should be extra strong.


About the condenser, you should not use anything that is glued with ?fludor(the stuff electronists use), because it will melt at high temperatures. And copper from what i understand affects the quality of the final product.

[Excalibur]

?fludor(the stuff electronists use),

Fox32, Google tells me this is solder. Its' melting point would be around 180°C so totally unsuitable for use with heat. A soldered joint will suddenly lose strength once the melting point is reached. A good reminder and warning for the unwary!!
Thanks for bringing it up.

[fox32]

Fox32, Google tells me this is solder. Its' melting point would be around 180°C so totally unsuitable for use with heat. A soldered joint will suddenly lose strength once the melting point is reached. A good reminder and warning for the unwary!!

Yes, that is correct, it is solder.Thnaks for clearing that up!

I was searching for some pirolysis unit for sale under 10.000 euros, and got across this interesting article from Japan... https://staff.aist.go.jp/tohru-kamo/...SFR99/DE-3.pdf

Btw are there any companies that manufacture and sell pyrolisis plants? for under 10k E.

[wheels]

Intro

Hi guy's, this is my first post here. I have been working through all the thread and am upto page 61. Very interesting seeing the progression. A little info about me. I have three trades qualifications. One Electronics, another Engineering and the third not relevant to this topic. I have spent several years designing and building equipment for Lipid Oil extraction. During that time I had to learn a lot of Chemistry and Physics, which are both still ongoing educations. The knowledge has gone a long way toward understanding Pyrolysis. What I am now involved in is actually the back end of what you guys are doing. We haven't really been interested in making the Fuels as such. Well not till now anyway. After reading here, I am kind of keen in playing with that. But what we actually do is reduce what you guy's would call Toxic Plastics. Mainly the ABS plastics from Ewaste. Ewaste recycling is part of what we do and the disposal of the Plastics is expensive here in NZ. We also break down PVC from Electrical cable. Our Machine is small, at least at the moment. Not any bigger than most of the ones here. But a little more sophisticated in the end filtering stages. We have been carrying out a lot of research and testing in taking care of all the Toxins and noxious byproducts from the processes.
Regards.

[Beyond Biodiesel]

Welcome wheels, it sounds like you could make a valuable contribution here. I look forward to what you have to offer us. By the way, Excalibur is a fellow Kiwi, so maybe you 2 will do some real time show and tell.

[ladanivaca]

Video

Hello friends
Here you first news item first, as always looking for the latest. Greetings from Spain.

How to get diesel from waste plastic - Bang Goes the Theory - Series 7 - BBC - YouTube

[wheels]

concerns

Thank-you Beyond Biodiesel. (I will use BBD as an abbreviation from now on) I do have one concern and was wondering if the Board software allows a "Sticky". That is where a thread remains at the head of the Topic so as it could be easily seen by all posters, especially newbies. I think some general safety needs to posted where everyone can see it, instead of trying to stumble through weeks worth of reading and missing important comments. I have noted many times where warnings have been stated and then a page or two later, someone makes some comment that would suggest they have never ever read that warning post. Often it has been the same subject and still the information has not gotten through.
I also have some additional warnings that have (from what I have read so far) never been considered/discussed. I think it is extremely important that readers understand the potential hazards working with this stuff, beyond the obvious of Fire and potential Explosion, although I do see issues with some designs that could be addressed in that area also.

Excalibur, would love to talk more with you. Where are you located?
Still getting used to this Board Design, does this place allow Private Email???

Righty, back to more reading of the Forum.

[wheels]

Metals

I seem to be regularly coming across a common comment. That is about using Copper in these systems.
DON'T USE COPPER!
In fact, don't use any "reactive" type metal. That includes Brass, Bronze, Aluminium etc.
The two safest metals to use are Stainless Steels (some SST's can be better than others also) or plain ole Steel.
During the Pyrolysis stage, many complex acids are produced. They eat pretty much everything., including all synthetics, hence why you can not use any form of synthetic Seal, it just breaks down and you have a reactor head leaking.
Some of you must have noticed Copper leaching and Copper pipes blocking surely. Be very weary of any hard crusty Coppery Pink residue blocking copper pipes/fittings. That can be explosive. All these metals react quickly with Acids. Yes ordinary plain Steel reacts as well, but it is slower compared to the more reactive Acids. No Oxygen, no oxidation, so no rust, but you will probably have noticed sometimes, the Reactor walls can look like really clean or etched Steel.
Later I want to discuss the outputs of Gasses at the end of the Machines and what to be careful of.
Please ask questions.I don't want to just woffle on.

[fox32]

Greetings Wheels, and welcome to the forum, your inshight will be highly appreciated!

I see you have a background in fuels and chemestry, i haven't seen a solution to the very strong smell of the product which i find very offending, maybe you have any ideas?

All the best!

[Col]

Pressure

Hi Excalibur.

Thanks for putting your pics and info on your site. I am just trying to determine pipe diameters for my system and wonder, when you were producing 20L/hr, did you have any pressure increase?

You go from an 8" retort, to a 6" reflux, to a 1 1/2" (or 40mm ID) outlet from the reflux to a long pipe which also seems to be 1 1/2", so I presume your condenser inlet is also 1 1/2", your condensing tubes appear to be roughly 16mm diameter? then it looks like you have a 1" outlet, or maybe 3/4", to your sight glass, then vapours leave the drum via the 3/4" bung.

Are those dimensions right? Was there a pressure change during the process or do you think those dimensions were capable of handling even more throughput?

Thanks
Col