How to turn plastic waste into diesel fuel cheaply

[piccolo chimico]

ciao dedooo il mio parere è che potresti avere un riscaldamento troppo lento quindi separare troppo le frazioni leggere a bassa temperatura e questo potrebbe spiegare anche il gocciolio a flebo. prova a dare potenza al tuo reattore.

[dedooo]

Please help, reactor his 30-liter gas cylinder Propane old around insulator wool thermal, and placed inside the 5 kg plastic, but the stove was a torch Propane, after an hour it seemed diesel drip for an hour, then slow down very, toll 3 liters of diesel, I am not satisfied with the the result because the output is very small, Is there a way to increase the output per hour, thank you

[jonathan]

pyrolysis fuel types

thanks excalibur and beyond biodiesel my proplem is that in malta is dificult to find insulation and when l find its very expensive l will try waste oil maybe its more easy then plastic to heat it to 425

[Beyond Biodiesel]

thanks excalibur.....l am going to try my pyrolysis with waste oil l thing tempreture is lower to crack waste oil and heats more qiuckly then plastic..l ask for fuel types it is posiple to do whitespirit,methanol,etanol from waste oil and plastic? or maybe from wood? thanks

The differences between distilling waste oils and solvents; and cracking plastics; and extraction of volatiles from wood (wood-gas); and extraction of volatiles from coal; are all much the same process. Just bring your product up to 800F (425c), and run the vapors through a fractionation system/tower, and see what you have. Trying to get specific products is harder than learning to work with what you have extracted.

[Excalibur]

Using waste oil is an OK idea, especially when trying to iron out problems.

Yes for white spirits. The other two are alcohols, though extraction from petroleum is possible the process looks rather complicated. See "Synthetic Chemicals from Petroleum" section of Shell Petroleum Handbook for more info.

[jonathan]

pyrolysis fuel types

thanks excalibur.....l am going to try my pyrolysis with waste oil l thing tempreture is lower to crack waste oil and heats more qiuckly then plastic..l ask for fuel types it is posiple to do whitespirit,methanol,etanol from waste oil and plastic? or maybe from wood? thanks

[Excalibur]

, this is why they reflux needs to be kept at the temperature of your first condenser, whatever that is.

With respect, this recommendation would not suit every set up. At this moment I think matching reflux and 1st condenser temperatures would be a situation where double distilling was required. This would have the benefit of making the fuel extra pure at the expense of requiring additional heat energy.
To illustrate, my reflux is targeted at 350°C while my 1st condenser is held at 80° ~ 120°C range. The reflux temperature dictates the heaviest fraction that is allowed to exit downstream while the 1st condenser temperature drives off only the most unwanted volatile fractions. So in this instance I want say 98% of condensate to stay trapped in the 1st condenser and 2% volatile balance to be shunted downstream.

hellooooo l wish to know what fuel types can we get and @ what tempretures? l know from plastic we take diesel,kerosene,petrol.can we take more fuels types?..from waste oil we can take diesel,petrol..what about kerosene? or other fuels thanks

Diesel, kerosene, petrol, naptha, LPG to name a few can be extracted from both waste oil or plastic. Think of these raw materials as being the same hydrocarbon with different carbon chain lengths.
diagram on this page with temperatures

[jonathan]

pyrolysis fuel types

hellooooo l wish to know what fuel types can we get and @ what tempretures? l know from plastic we take diesel,kerosene,petrol.can we take more fuels types?..from waste oil we can take diesel,petrol..what about kerosene? or other fuels thanks

[Beyond Biodiesel]

So the reflux serves both as a wetting surface for the heavier fractions to condense upon and separate from the lighter fractions, and as a contaminant removal, like a filter, to remove free-carbon which has been carried over from boil-over.

Yes and no. Boil-over is liquid plus vapors that carries particles of solids up in a boiler. The function of reflux is to allow the liquid to wet, as you said, and along with that wetting particles of solids in the boil-over are captured and both fall back down into the boiler. This allows only vapors to escape the reflux, this is why they reflux needs to be kept at the temperature of your first condenser, whatever that is.

With this in mind, as you might expect, the pad of stainless steel packing which I retrieved from the gas-liquid separator I cut open was fouled with crusty carbon-like material. The pad is 200mm thick by 800mm diameter, has been difficult to clean. Think I might have to separate the mesh into individual sheets to get a proper clean. I guess if we are using something cheaper we would need to just throw it away once the reflux efficiencies decline. And if we have chosen to use rusty iron in the reflux the surface of rust would be covered by carbon and need replenishing.
Col

There is no reason to clean this baffle in your reflux, but a baffle does not have to be thick. I can see it more like 800mm in diameter, if your reflux zone is 900mm in diameter, but it need only be 1-3mm thick. The baffle is not meant to have a great deal of thermal mass. It should be light, with almost no thermal mass, just a lot of surface area to pose as an obstacle to the movement of the flow of liquid containing particles of dirt, ash and carbon.

[Excalibur]

Thanks Col.

Last run, I'd made a big step with eliminating smoke emissions from the burner. The gain was in a number of tweaks. The fuel for the injector pump that fires the burner was blended much thinner than before so when the fuel sprayed it instantly vaporized and burned. Unlike before when fuel was puddling, creating smoke. Because of this efficiency improvement, the burner housing was running red hot so ignition was no problem. The off-gases was another refinement and the moving of the gas feed nozzle to the door of the burner worked a treat. I ran one fuel circuit at a time only. The gases was the best for heat and quiet because there was no injector pump running.
So, yes a little smoke on initial starting up. Once up to temperature the air control was in a sweet spot and was barely touched. I had fitted a TC to the burner to read the flame temperature. It recorded up to 800°C.
As for automation, it doesn't appear to need it although it's only been one run with the tweaks. I thought perhaps an 02 sensor in the flue stack connected to one of my proposed alarm circuits. The stack top is out of sight of the air control so I wondered about fitting a mirror to view the emission or else a Bowden cable for remote adjustment.
Incidentally, my Arduino controlled servo isn't in use and has been discontinued.

Yes, it might be the case with the final stages for cracking. There can be lots of gas and I'd ideally like to store some so I can restart on it from cold. Just how well gas would store in a gasjar isn't known. Another thought was to compress some into a LPG cylinder.

Earlier you were asking about vacuum. I'd picked up a Thomas WOB-L piston pump which does vacuum. I think it pulls 27inch HG. The idea of vacuum has some appeal for possible energy savings and lower BP. I used it on 2 early experiments, neither was particularly successful. I'm sure it could be developed though.

[Col]

Location of cracking along the chain

I recall IMBD saying about snipping the run before the retort dried out to char. One thing about the final stages is that I get disproportionally more off-gases so the process is "feeding on itself" even more-so than ever.

Nice article!
I have in my notes that "temperature, to some extent, will determine where along the length of the molecule the cracking will occur. Higher temperatures tend to crack pieces off the end of molecules resulting in lighter products such as gas and naptha."
It seems in your final stage, when your retort is at its hottest, you are losing the ends off your heavy molecules, repeatedly. I understand that if you were to maintain a lower temperature, for longer, you could get less gas / naptha and more diesel because a lower temperature will tend to crack the longer chains into medium chains rather than short ones. However, that doesn't sit well with my recent posts about trying to avoid instability in the final product.
Col

[Col]

fuel to air mixture for clean emmissions

Hi Excalibur

Just confirming, when you start your retort from cold, in order to keep emissions clean, you need to baby sit the fuel - air mixture while it's cold, then when it is hot you can leave it alone. Then when you want to raise or lower the temperature you need again to manage the fuel - air mixture.

Do you think you will automate this process? Or does it not rate high enough on the priority list at the moment?

Col

[Excalibur]

With the mention of specific gravity recently, I wrote an article with the belief that it would be helpful. Sort of a self help for newcomers. click here for article

Col, good description of the reflux as a separator of the lighter and heavier fractions.
Also interesting point on the continuous fed reactors ending up full of heavier and heavier feedstock. I'd expect those heavier fractions to have higher and higher boiling points too, basically the reciprocal of lighter fractions having correspondingly lower and lower.
I recall IMBD saying about snipping the run before the retort dried out to char. One thing about the final stages is that I get disproportionally more off-gases so the process is "feeding on itself" even more-so than ever.

[Col]

Fuel Stability

If fuel stability issues arise from prolonged exposure to high heat - can we work around these issues? The higher the heat in the retort the shorter the time required for pyrolysis to work. But heating to a high temperature too fast will cause boil-over, and the reflux is sensitive to temperatures and rate of vapour flow. Can we apply a vacuum so we can drop the temperature and get the feedstock to that 'equivalent' temperature faster? This nomograph indicates that if we have feedstock of BP 425C, and apply a vacuum of 2 torr we could boil it off at 220C. But I understand 2 torr is the practical limit of what an operational refinery can achieve, which we could not achieve. I am told we could expect to achieve a vacuum of 600-675 torr using a common blower. But that only allows us to reduce the 'equivalent' temperature to 410C. It doesn't seem worth it. I would have thought that we would want to aim for a temperature below 350C, as that is the temperature Excalibur said the Shell Petroleum Handbook states as the start of thermal cracking. Which raises another question - If we lower the BP by applying a vacuum, will the heavier hydrocarbon chains even break at the lower temperature? We use heat for two purposes here - one to distil the liquid, and two to crack the longer chains. If we use a lower heat what will instigate cracking of the longer chains? I guess this is where the catalyst comes in. It facilitates cracking at lower temperatures, limiting the instability issues by avoiding the need to heat too high.

If we wanted to go to extra effort to achieve a stable fuel we could distil off all feedstock up to a temperature of 350C, with or without a vacuum. Then we could drain all condensers / holding tanks and segregate the first batch of fuel. Then raise the temperature to cracking levels and expect there to be some stability issues with the second batch of fuel, which may be overcome with additives afterwards. Keeping in mind that a small amount of instable fuel will affect good fuel if mixed in, so the condensers / holding tanks would need to be well drained before the next low temperature batch. Or we could use a catalyst and perhaps avoid the instability issues altogether.

Does anyone know what vacuum we could expect to achieve using affordable equipment? and how?

Nomograph - Printer-friendly Page - [www.rhodium.ws]

Thoughts anyone?
Col

[Col]

Sizing a retort

I acquired a formula for determining how many kW need to be applied to a tank of liquid to get to a certain temperature in one hour.

L x 2.2 x temperature rise required / 3600 = kW required to heat in 1 hour.

L is volume of fluid to be heated (in litres)
2.2 is the constant for our choice of liquid - oil. The fella I was speaking to did not have a range of values for different types of oil, just one value for all oils. This constant is related to the viscosity of the liquid, though I could not figure out how, so can't tweak it for our exact application. I suppose he would also have a generic value for plastic too, as the company makes heater bands, but I didn't think to ask him for it.

So, for example, if you have 10L of oil you want to heat from ambient temperature (say 20C) to evaporating temperature in one hour you would need to apply this many kW to the retort...

10L x 2.2 x (425C-20C) / 3600 = 2.475 kW

Apparently this formula works for heating a volume of liquid with a viscosity rating of 2.2(units of measurement?). But I do not know if the rules change once you hit evaporation temperature and the liquid becomes a vapour. Nor do I know at what point the liquid would start to change phase and how long it would take to complete that process. Since reflux efficiencies, the available surface area for evaporation, insulation effectiveness etc are potentially limiting factors the actual time taken to complete evaporation would be subject to change between systems.

How does this information correlate with your practical work anyone? I recall some people were getting their 19-20L retorts up to 400C in 1-2 hours using a 2kW heater. This seems to roughly agree with the formula but the time frame is too vague.
BBD - you were getting your 19-20L retort up to temperature in 2 hours, with no condensate in the first hour while the temperature climbed, then an average of 1L/hr after that for 10 hours. Did that mean you had 10L of WMO in your 20L retort and you ran the retort dry in 11hrs total? You also had extra heating on the walls right. Do you know how much of the time those wall heaters were actually heating? I expect the base heater was on the whole time and the wall heaters were regulated via TC. I am interested to know if the wall heaters are on full duty or not.
If your wall heaters were only on part duty then this formula seems to agree with your results for the first hour, but then is blown out of the water by the next 10 hours. You were pouring 2kW into the 10L of WMO every hour, even after it reached the target temperature. And it gets worse - at the half way point it was 2kW for 5L, then at the end it was 2kW heating just 1L. This does, however, agree with what IMBD said about the last 5% of the process taking a disproportionate amount of heat to get the retort dry, which is one reason why he was content to leave the last portion of the feedstock as a sludge rather than dry it out to ash.
So it seems the formula agrees with practical results while heating liquid, but not while evaporating liquid to vapour. And we need to remember the diminishing returns toward the end of a batch. For those considering a continuous system, if you top up the retort continuously without letting the retort run dry you will eventually have a retort full of the heavy fraction and need to apply a lot of heat over a long time to evaporate it. The longer the time a molecule spends at high temperatures the greater the chance of stability issues.
Col