How to turn plastic waste into diesel fuel cheaply

[wheels]

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!

Hi Fox32. That's a really difficult one to answer, because it depends on what is meant by "offending smell". Are we talking Rotten Eggs?(Hydrogen Sulphide) or something more "Petrol" like? Is this from the "Off Gas" or the Fuel itself?
Many of the lighter Hydrocarbons have their own smell signature. Hence why they are called Aromatics. Aromatic does not mean the smell is pleasant. Ethyl Benzene is the one that smells most common to Petrol, (as it is a major ingredient of Petrol, it gives Petrol it's Octane rating) and can smell very strong and smelt a long way away from the machine. I find that even a few very slight wiffs of the stuff makes me feel quite sick.
One big issue is the Feedstock purity. Especially if you are using recycled, it is sometimes not 100% pure. Something other than the desired plastics may slip through. This possibility is why we should always treat all outputs from these devices with great respect. Even the carbon left in the Reactor needs to be treated as highly toxic, whetehr it is or not. You just can't tell and I can not stress enough to make sure you were a Dust mask at minimum, respirator at best and Gloves and Overalls to protect your Skin. You just never know what kinds of plastic may have slipped through the sorting. The only time anyone could ever truly trust the Feedstock is if it came from Pure Virgin Pellets, but I suspect no one is ever going to be using that.
But I am side tracking myself, so in the case of recycled waste plastics, if something other than PE and PP has slipped through, it could be a source for an unwanted Chemical in the end product and a resulting smell that is not normal or desired.
For instance, ABS plastics produce Styrene, which is Methyl Benzene, along with a very Toxic Hydrogen Cyanide, which smells like Bitter Almonds. Never smelt it and never want to. It's one of those Gasses that can send you off to Wednesday Evening Harp practice at No777 The Pearly Gates.
Hydrogen Chloride gives a very Pungent smell.

[Col]

Sludge

I made an attempt at cracking wmo to diesel a couple of years ago before I came across this forum. I wasn't satisfied and shelved it. Now that I am getting hands on I cut open the old retort (it was a 10" pipe welded shut both ends, 20L total capacity) to make improvements to it. I agree with Fox32 - the smell is bad, I guess it might smell like burned oil, but with a lot of other smells in the mix. I put the fuel from the process through activated carbon which did remove most of the smell. But what surprised me today was the amount of sludge left in the retort. I only put 3L of wmo into the retort but had enough sludge left to pack it together like a fist-sized snowball. The sludge was still 'wet' with oil because the retort wasn't insulated so once the vapour flow rate dropped off there wasn't enough heat going up to the baffle pipe to keep it hot enough so it kept refluxing back on itself (BBD pointed this out - thx).

Are you guys getting that much sludge per 3L of wmo?? It seems like a crazy amount of sludge. Maybe it reduces somewhat if allowed to boil dry, or maybe I just started with a poor 3L batch. Pre-filtration will need to be designed into my system.

Col

[David007]

ecco l' immagine

bel lavoro, complimenti!

in fatti e piu bella che ho mai visto, hai provato, funzziona?

[wheels]

Smell

Arr, if the smell is when using Waste Motor Oil, then it could very easily be Sulphur compounds. For a start off, some Oils have Sulphur in them as part of their additive package. But one other place Sulphur is going to get into WMO is during combustion. For a Petrol Engine, every 10ltrs of Fuel burned, 1ltr of water will be produced and about 10mls of Sulphuric Acid is produced. Most of that all goes out the exhaust, but over time, some of that acid gets down into the Oil Sump. There are additives in Motor Oils that neutralize the Acid, but the Sulphur remains and also over time, the Additive eventually gets used up and so if a regular Oil change has not been carried out, you will have Sulphuric Acid in the Oil. When that goes through Pyrolysis, you are going to have all sorts of issues, depending on what else the Sulphur is reacting with.
What quite likely is happening is, at high temperature and/or in the presence of catalysts, sulfur dioxide can be made to react with hydrogen sulfide to form elemental sulfur and water. So in a Nutshell, if the smell issue is Sulphur'ish smelling, it could be one of any number of Sulphur compounds and reactions. The Only real way of knowing is to have a sample analyzed to find exactly which one it is.
Only thing is, all you are going to get from that is that there is Sulphur present, which you already knew by the Smell anyway. There is very little you can do about it if it is in the processed Fuel. There is a process that can remove it, but it is requires heat and pressure and a machine slightly more complex than a standard Pyrolysis unit. The process is called Hydrodesulfurization.
If the smell is in the Gas, then there are two easy ways to dispose of it. Either flare it off, which is easiest or use an Activated Carbon Filter, which removes it.
I hope that helps

[fox32]

The problem is i haven't encountered anythin that smells closley related to this and i can't describe it, i don't find the smell to be sulfurish, but even a few breaths cand make one sick.Or maybe i'm more senisble. The fuel and gas smell the same, but when burnin the smoke smells like diesel. I didn't tried the activated carbon filter, but definetley will try now... I only use plastics, that float(not all of them are marked) but not polystirene.

Col what type of charcoal are you using, will work with hommemade charcoal or i have to buy a specific one?

Cheers!

[Excalibur]

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.
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???

The sticky seems like a reasonably good idea. It's common for newbies to ask about issues that are already covered over and over again, sometimes just a couple of pages back too! Partly I think non native English speakers struggle with translation. I expect it to be quite tedious for them. Also the forum search function needs revision. Despite the problems we are lucky to have a forum and the ability to communicate worldwide in a way never before possible.

Wheels, welcome. I'm about to email you (aka PM).

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?

Col. please use any ideas on my website that appeal. The material is for anyone and everyone to utilize. I remind that the device is a prototype.
The only "pressure to speak of" would be from the bubbler and gasjar which would amount to about 1psi. The condenser tubes are 1/2" from memory otherwise your summary is accurate. The diesel receiver reservoir has been upgraded to a 500L vessel with same size fittings as before. In my opinion the system could handle a liter a minute throughput. At times it does that speed though it isn't sustainable because as the retort level drops so does the volume of vapour.

Are you guys getting that much sludge per 3L of wmo?? It seems like a crazy amount of sludge. Maybe it reduces somewhat if allowed to boil dry, or maybe I just started with a poor 3L batch. Pre-filtration will need to be designed into my system.
Col

My retort will boil completely dry to carbon char. It's likely due to the sheer size of vessel, with its' heavy 8mm wall thickness, 10mmbottom and 20mm flanges. It's a solid chunk of steel! Once I decide to shutdown operations, any remaining liquid, tar, etc bubbles and gas's away for hours just from residual heat.

Arr, if the smell is when using Waste Motor Oil, then it could very easily be Sulphur compounds. For a start off, some Oils have Sulphur in them as part of their additive package. But one other place Sulphur is going to get into WMO is during combustion. For a Petrol Engine, every 10ltrs of Fuel burned, 1ltr of water will be produced and about 10mls of Sulphuric Acid is produced. Most of that all goes out the exhaust, but over time, some of that acid gets down into the Oil Sump. There are additives in Motor Oils that neutralize the Acid, but the Sulphur remains and also over time, the Additive eventually gets used up and so if a regular Oil change has not been carried out, you will have Sulphuric Acid in the Oil. When that goes through Pyrolysis, you are going to have all sorts of issues, depending on what else the Sulphur is reacting with.
What quite likely is happening is, at high temperature and/or in the presence of catalysts, sulfur dioxide can be made to react with hydrogen sulfide to form elemental sulfur and water. So in a Nutshell, if the smell issue is Sulphur'ish smelling, it could be one of any number of Sulphur compounds and reactions. The Only real way of knowing is to have a sample analyzed to find exactly which one it is.
Only thing is, all you are going to get from that is that there is Sulphur present, which you already knew by the Smell anyway. There is very little you can do about it if it is in the processed Fuel. There is a process that can remove it, but it is requires heat and pressure and a machine slightly more complex than a standard Pyrolysis unit. The process is called Hydrodesulfurization.
If the smell is in the Gas, then there are two easy ways to dispose of it. Either flare it off, which is easiest or use an Activated Carbon Filter, which removes it.
I hope that helps

According to wiki, H2S is soluble in water. I wondered whether simple hot water washing the fuel would help. Elsewhere in the 'Shell Petroleum Handbook' is says caustic is used as a H2S treatment.

[wheels]

The problem is i haven't encountered anythin that smells closley related to this and i can't describe it, i don't find the smell to be sulfurish, but even a few breaths cand make one sick.Or maybe i'm more senisble. The fuel and gas smell the same, but when burnin the smoke smells like diesel. I didn't tried the activated carbon filter, but definetley will try now... I only use plastics, that float(not all of them are marked) but not polystirene.

Col what type of charcoal are you using, will work with hommemade charcoal or i have to buy a specific one?

Cheers!

Fox32, OK so you are using plastic. I was unclear on that.
OK, try adding Caustic Soda (Sodium Hydroxide, commonly found as Drain Cleaner) to your bubbler. See if that decreases or even totally removes the smell from the Fumes. Let me know your results and I can go further.


It's important for everyone to understand that pretty much every fume that is produced from Pyrolysis of any form of Hydrocarbon (including the nice plastics that float) can and will make you sick and some fumes can be deadly.
For those playing with WMO, the problem with WMO is that you just don't really know what can be in the suff. Unless it is Oil from your own vehicles. But WMO that comes from the Local service guy could have all sorts of stuff dropped into the waste tank, such as solvents and so on.

[Beyond Biodiesel]

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...
It's important for everyone to understand that pretty much every fume that is produced from Pyrolysis of any form of Hydrocarbon (including the nice plastics that float) can and will make you sick and some fumes can be deadly.
For those playing with WMO, the problem with WMO is that you just don't really know what can be in the suff. Unless it is Oil from your own vehicles. But WMO that comes from the Local service guy could have all sorts of stuff dropped into the waste tank, such as solvents and so on.

Thank-you, wheels, for another voice in favor of safety. I look forward to what you have to contribute. A safety sticky would be greatly appreciated.

However, while I agree that steel and stainless steel are wise choices in metals, copper and aluminum have not posed a problem for my pyrolysis unit as long at they are not used in the retort, due to excessive oxidation above 800f (425c). Below 700F (370c) they seem to be acceptable, but they do react to any HCL in the process, which seems to help neutralize the HCL.

[wheels]

Thanks BD.
Re the Metal Material used in Piping, this is an interesting point to discuss. It's not just about whether you see issues with corrosion in the Tubing and fittings or not. There are Acids in the Fuel and many of the Gasses that pass through are Acids. Slightly aside, that is one other issue we need to address sometime, the Fuel being very Acidic. Anyway, before I get Side tracked, the issue with Acids traveling through pipes is that with any Metals, Ions get stripped away and carried along with the Fuel. It may never be seen in the Finished product, but it is there. Then that goes into a Fuel tank to feed an engine and we are now burning Heavy Metals and blowing that out the exhaust. Aside from other possible chemical reactions that could be taking place during combustion and possible effects on Catalytic Convertors in the Exhaust systems. We need to think about the Finished product a lot more and what we are possibly putting back into the Atmosphere as pollutants.
Here's a little background and side story as to why we are trying Pyrolysis.
NZ had been exporting to China all our Waste plastics from Ewaste. When it was discovered what was going on over there and that both People and Environment were being placed at risk from excessive toxic pollution, all Export was banned. So the result is that it all now goes into our own Landfills.
When we started our own little Project, it was a key question I posed to the group. They guy doing the Ewaste recycling was very keen and excited about finding an alternative to having Toxic Plastics going into our Landfills. But my comment to him was, there is no point in fooling ourselves as being "Clean and Green" by reducing the amount going to Landfill if we are just putting toxins into the Atmosphere. In fact it may be safer to leave many of the Toxins locked up within the Plastics and buried, rather than releasing them into the Air. And hence my journey down the Path of learning what is produced and trying to mitigate those Toxins from the process.
Don't get me wrong, I am far from an expert yet. Still learning heaps.

[wheels]

metals

Maybe one of you guys with access to Lab testing could do a test for us on metals and quantity of such on the Finished products.
With copper, it is fairly easy to note if there is a possible problem. You just need to look for any of the following.
On the inside of the Tubing, either Shiny new looking, or Pink looking Copper, which mean the Copper Ions are being stripped away.

Even SST is not without issues. First of all, SST needs oxygen to be stainless. It is the reaction with Oxygen that produces the protective Chromium Oxide Gas that self protects itself. Remove the Oxygen and you remove its protection and then other Metals can be leaved out. Also with SST, the Environment is Hydrogen Rich and SST is subject to Hydrogen embrittlement. Not so much of an issue because we are not working with Pressure, but something to keep in the back of ones mind if a pressure situation should ever accidentally develop. Plus this very issue has resulted in some of the biggest accidents around the world in the Commercial Machines. Over a long time of heating and cooling over these huge Retort Vessels, Welds have failed and Oxygen has got in turning the device into a Huge Bomb and resulting in many serious injuries and deaths.
But the more important issue for us, I think, is what Metal Ions are being stripped away and carried along in the product stream and what that may do. So you have Chromium, Nickle, Molybdenum and so on.
Not saying we should no use such metals, but it still a consideration and thought required as to where certain metals are used in the Machine design. Sometimes you can't beat just plain old steel and I highly recommend Steel being used a in the Reactor Vessel.

[wheels]

Dioxin

I am now up to page 70. So sorry if this has been discussed between there and here. I note that the subject of Dioxin has come up a couple of times and the concern with using PVC platics.
Well actually Dioxin is NOT produced. Dioxin needs Oxygen to be created and temperatures over 400degC. Some parts of the Reactor may get to those temperatures, but there just isn't really enough Oxygen to react with the Chlorine to create Dioxin, at least in any real amounts.
Even in a complete vacuum or an Inert Gas filled Reactor, there is likely to be small amounts of Oxygen still. You just can not have a totally Oxygen free environment. But it is very small trace amounts and not really enough to produce anything of worry. If by some chance a Dioxin Molecule is produced, it can be destroyed but extreme heat/total combustion. So flaring the Off Gas with plenty of oxygen to produce a very hot Gas flame will burn up any possible Dioxin.
HOWEVER, melting PVC produces Chlorine and that brings along many other issues to have to deal with.

[David007]

can help me !!!!!

hi, i have 1 moonshine about 35 L
can use it, to make fuel from plastic?
have pression inside?

[David007]

what happened

what happened if i mix, all plastic?
have probem?
or i have and paraffin in condesser tank?
what is right time for range the temp. 400 °C?

[Col]

Activated carbon / charcoal

Col what type of charcoal are you using, will work with hommemade charcoal or i have to buy a specific one?

Hi Fox32. See my post #3079 for details on the activated carbon trial I did. I spoke to the sales rep about my application and he recommended that particular product as the pore size was a good match to "grab" the longer, stringy / "fibrous", greasy molecules from the solution. I believe it is made from charcoal derived from burning coconut husks (maybe from the Philippines?) cooked at high temperature to expand the charcoal / carbon so it has a much larger surface area available to interact with the solution. A bit like a corn kernel compared to a popped corn kernel, much larger and porous surface area after popping.
I expect we could make it at home but I can get it for $4.20/kg if I buy a pallet or so at a time (I use it for other stuff at work) so I wouldn't bother doing it myself.
Col

[Excalibur]

hi, i have 1 moonshine about 35 L
can use it, to make fuel from plastic?
have pression inside?

Not suitable.

what happened if i mix, all plastic?
have probem?
or i have and paraffin in condesser tank?
what is right time for range the temp. 400 °C?

Bad idea to use all/any plastic. Use PE/PP.
Parrafin in the condenser suggests you have a reflux problem.