How to turn plastic waste into diesel fuel cheaply

[Excalibur]

Thanks.
The weight of your fuel is very light, nearly as light as petrol. Good usable diesel would be around 820 ~ 850 grams per liter.
I await more photos and information on the fractionation column from you.
grazie

Rendered translation from Italian:
good point excalibur, that's what I thought. as you will see from the photos I'm editing the wrong place for the fractionation column in the head with it to create the reflux and then insulate. as regards the empty keep it always lit to avoid clogging, the wax will not find it anywhere, the weight of the fuel is 1500 grams per 2 liters. insulation resembles excalibur but with wool instead of vermiculite

I try to upload photos

[piccolo chimico]

non riesco ad inviare le foto della colonna e le modifiche fatte.ci proverņ domani a caricare i fail

[piccolo chimico]

excalibur se mi mandi una tua mail personale proverņ a mandarle.grazie

[piccolo chimico]

excalibur ti ho inviato le mie immagini sulla tua posta.guarda un po.ciao

[fox32]

piccolochimico, could ypu please use english language, it is not native to us too, but this way we can understand ourselves. Odlly enough, i can understand more than 50% of what are you saying, and i never studied spanish. Good luck!

[Excalibur]

piccolo chimico

Good on you for building something so innovative. I have very little experience with vacuum distillation however because you are getting fuel weighing 750gr per liter, the plastic must be cracking. The dark color of your fuel suggests boil-over. Because vacuum will reduce boiling point, perhaps try reducing the reactor target temperature.
BB might be able to throw some light onto the situation as his pyrolysis unit has run under vacuum since he started.

[Beyond Biodiesel]

Thanks, Excalibur, for referring to me on this. Regardless of whether a fractionation/cracking unit is operated at ambient, or increased pressure or reduced pressure. If, your samples are coming out dark, then it is most likely the presence of free-carbon due to boil-over in your retort. So, in this case, then one would want to work on improving your refluxing system.

Italian

Grazie, Excalibur, per riferirsi a me su questo. Indipendentemente dal fatto che una unitą di frazionamento / cracking viene azionato a temperatura ambiente, o aumentata pressione o pressione ridotta. Se i campioni stanno venendo fuori buio, allora č pił probabile la presenza di senza emissioni di carbonio a causa di boil-over nel tuo storta. Quindi, in questo caso, allora si potrebbe desiderare di lavorare per migliorare il sistema di riflusso.

[piccolo chimico]

ciao BB il sistema di reflusso era sicuramente errato o meglio inesistente.come avete visto nella foto la colonna era spostata di almeno 30 centimetri dal reattore e non coibentata,quindi la condensazione veniva a crearsi nel primo stadio della colonna in basso .ora sto portando la colonna al centro del reattore e coibentando tutto,1' stadio in basso farą da reflusso, gli altri frazionamento. a malincuore proverņ ad eliminare il vuoto.

[Col]

Reflux fouling

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. 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

[Excalibur]

hello BB system reflux was definitely wrong, or rather non-existent. as you saw in the photo the column was moved at least 30 cm from the reactor and not insulated, so the condensation was to create in the first stage of the column at the bottom. I am now bringing the column in the center of the reactor and all insulated, 1 'stage will lower reflux, the other division. reluctantly try to eliminate the gap.

Sounds good. Temperature thermocouple probes at each of the fractionation column levels would be very useful for tuning purposes.

[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

[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

[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 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

[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