How to turn plastic waste into diesel fuel cheaply

[Beyond Biodiesel]

This idea I suggested some time back has whiskers on it - if the oil feed malfunctioned/stopped for any reason (bulk supply ran out, feed pump to header tank faulted, float level jammed) and the retort kept going the oil level would drop until there was no longer an oil/liquid seal and air would enter the retort - KABOOM!

Good to work out these issues ahead of time.

On Ebay I picked up a copy of The Petroleum Handbook compiled by Royal Dutch Shell, 3rd edition 1948. I paid $1 and with shipping another $28. The book is a bit battered but perfectly legible.

Good idea, Excalibur. There was a copy in the lab at Chevron. I recall spending quite a bit of time with the book. I had thought of buying a copy, but never got around to it until now. I ordered a copy.

References are made to rpm but it doesn't seem to say that the tube is rotated. I assume the rpm references are for the cylinder rotation as some people are doing for tyre pyrolysis. What is the benefit of this method for a continuous system? I guess it's one way to spread the feedstock over the heating walls and keep the feedstock mixed. Any other benefits?

If you are talking about thin film, or wiped film distillation, then the heated surface is rotated. I think that is a bit complicated for DIY.

I'm planning is to use a needle valve instead of ball valve for improved flow control of feed. A ball valve is on or off with little adjustability in between.

I am rethinking the needle valve idea for regulating continuous WMO feed, because WMO is so dirty, the valve could plug up. So, a metering pump is what I am looking at now.

One surprise happened that I'm attributing to a low oil level in the retort was that when feed was applied, it immediately flash-boiled. This resulted in dark red output with particles, presumably carbon.

Flash evaporation is what I am thinking of as well. Once the retort is hot, then a pulsed feed of a very small amount to match max output might be best.

Hi BB,Sorry been off-line for a few day's. when i say the length is 850mm[85 cm] and the radius of the retort is 333mm[30,3cm].Sorry we are metric system here,
thks

I am familiar with the metric system. Your original numbers still add up.

Product from flash boiling was mixed in with the other 180 liters or so but all looked well enough. The feedstock hitting the hot zone may have cracked the oil to some degree but the important thing is the free carbon wasn't bonded onto the oil any more.

It sounds like flash evaporation is just the ticket.

Yes, parts of that book are right up our alley. I was "like a dog with a bone" when I first read it.

I expect everyone who wants to do DIY pyrolysis will want a copy of the Petroleum Handbook.

[VAST]

Hi Col

Thanks for the info, appreciate it.

When I was thinking about the level of the feedstock and size of the retord, I was thinking that your feedstock should be in small volumes for easy gasification, the continues feedstock should be kept at a temperature just below the temp where gasification starts to reduce heating and cooling of feedstock, with a fluctuation of temperature between 400 degrees and 420 degrees in your retord.

I think the continues feed system should rather be a drip system where feedstock rate is controlled by the temperatures reached in the retord so that your flow can be regulated in this manner.

I`m more inclined to the instant flash than to a steady process where you take up the degrees in small increments. Of course this is all speculation on my part as I don`t have any practical experience. I must make my own deductions based on other peoples experience that they are sharing freely until such time as I have my unit up and running and I can do some experimentation on my own.

I keep thinking, small retord for quick heating and a 10th of the capacity of the feedstock that you normally can load in the retord, maybe even less depending on what you can verify is happening with the feedstock.

Once you deduce the correct correlation between feedstock levels and gasification you can scale it up for the amount of fuel you want to produce. The principals should remain the same or am I incorrect in assuming that?

[Amin77]

Hello all.
I don't post much lately because I really have nothing to add at this time and all the info you need is already shared, just read all the posts though. We will start to work on this again in about a month or so, then we will have new info.

rooneyassoc777, I shredd my plastics myself using a shredder, I posted pictures of that machine earlier, but shredding is not really needed, it just makes the process more efficient as you can stuff more of it in the reactor. It will still work good if you have bigger pieces. A vertical band saw is a great tool to cut plastics into smaller bits, before the shredder we used that and cut all the plastic boxes and truck mudguards into a matchbox sized pieces. Worked well

HELLO, CAN YOU SEND YOUR SKYPE OR MAIL, CAN WE TALKING?

[Col]

Float level v base plate temperature monitoring

Brainstorming a couple of months ago, we came up with a DIY idea for a float level device. Get a pneumatic air cylinder with a magnet type piston in the length of stroke equivalent to the max depth required for the level...

Great idea. Sounds promising. I am leaning more toward a very shallow depth of oil now and think a float level will be less useful for me.
I am considering putting temperature probes into the base of the retort at the centre and outer edge. The probes would be sandwiched between two base plates, one plate welded in as the base of the retort and another bolted hard under that one. The lower plate would have 2 x 6mm recessed grooves allowing for insertion of the temperature probes. Then regulate feed by base plate temperature. A shallow pot and short distance to the packing could make temperature regulation in the reflux difficult. I guess we'll see.

[Col]

Flash evap

Hi Col

Thanks for the info, appreciate it.

When I was thinking about the level of the feedstock and size of the retord, I was thinking that your feedstock should be in small volumes for easy gasification, the continues feedstock should be kept at a temperature just below the temp where gasification starts to reduce heating and cooling of feedstock, with a fluctuation of temperature between 400 degrees and 420 degrees in your retord.

I think the continues feed system should rather be a drip system where feedstock rate is controlled by the temperatures reached in the retord so that your flow can be regulated in this manner.

I`m more inclined to the instant flash than to a steady process where you take up the degrees in small increments. Of course this is all speculation on my part as I don`t have any practical experience. I must make my own deductions based on other peoples experience that they are sharing freely until such time as I have my unit up and running and I can do some experimentation on my own.

I keep thinking, small retord for quick heating and a 10th of the capacity of the feedstock that you normally can load in the retord, maybe even less depending on what you can verify is happening with the feedstock.

Once you deduce the correct correlation between feedstock levels and gasification you can scale it up for the amount of fuel you want to produce. The principals should remain the same or am I incorrect in assuming that?

I think the principles will remain the same, methods of heat management may change.
I like where this train of thought is going - we can maintain a good vapour flow rate without a large pot of boiling oil. It seems like a safer method to me and we shouldn't get any boil over. Heating the feedstock to 200C will mean less heat absorbed from the retort floor so if the reflux and condensers can handle it the flow rate can be increased. And regulating the flow rate to match a steady combustion flame sounds like the more reliable way to go, don't have to worry about keeping the burner tuned for varying fuel rates etc. so flue emissions should be able to be better managed which will make it easier to operate at work. No float level means one or two less moving parts in those extremely harsh and fouling conditions too.

One catch I think could be the free carbon particles Excalibur mentioned. They may build up on the reflux packing and reduce efficiency / effectiveness. I guess if you're using lathe turnings there's no shortage of supply! One of the YouTube videos I saw using flash evaporation showed grainy tar-like matter settling out of his fuel after condensation and collection. I am sure he is not using a reflux or any separation of fractions except by letting vapours boil off to atmosphere as the fuel drips from the condenser to the can.

I am getting (more) excited!

Col

[Col]

Method of sealing stirrer shaft

Thank you beyond biodiesel, I'm hoping the stirrer will somewhat compensate and at least distribute the heat uniformly internally.

Hi AAS.
How have you been progressing? What type of seal did you use on the stirrer shaft, and how did it perform?
Thanks, Col

[Col]

Reflux design with flash evaporating

Hi guys - do you have any thoughts on how the ideal reflux dimensions might change when applied in a flash evaporation system? I am rethinking my retort design. Instead of a deep pot I expect I will only need a shallow pot. My existing reflux section is 800mm diameter x 250mm tall (not 300 as I previously thought). I am guessing I'll just cut another section to match and use that as the retort. That clearly does not match the 1:4 ratio discussed earlier. I can't see the dimensions being a problem so long as I can keep the temperatures right. Your thoughts?
I am intending to use a flat base and install a wiper to 1) 'agitate' the oil for maximum vapour extraction and 2) push the carbon/ash build up out to the edges and away from the main heating plate, which will help maintain efficiencies. Though the wiper can be added later. Anyone know what options there are for a seal for a drive shaft in a retort?
Col

[Excalibur]

Hi guys - do you have any thoughts on how the ideal reflux dimensions might change when applied in a flash evaporation system? I am rethinking my retort design. Instead of a deep pot I expect I will only need a shallow pot. My existing reflux section is 800mm diameter x 250mm tall (not 300 as I previously thought). I am guessing I'll just cut another section to match and use that as the retort. That clearly does not match the 1:4 ratio discussed earlier. I can't see the dimensions being a problem so long as I can keep the temperatures right. Your thoughts?
Col

Col, a flash boiler won't play by the normal rules of controlled distillation. To drop oil into a very hot, shallow retort in this way may well have it barging its' way downstream, ignoring any reflux. The effect is a very, very lively one. I hope you can tame and master it.

When the book turns up, read chapter 10 Thermal Cracking. What this will explain is that cracking oil will result in:
1/. some oil that is lighter than the original,
2/.some that is heavier than original
3/.and some that is the same weight.
In controlled distillation, the lighter fraction is then boiled off, leaving the heavier which is again cracked., and the process repeats.

I can't see the dimensions being a problem so long as I can keep the temperatures right. Your thoughts?

Temperature is the key thing. Consider it like a balance. Dimensions are what can be tweaked to encourage the part to run at the desired temperature.

[AAS]

Hi AAS.
How have you been progressing? What type of seal did you use on the stirrer shaft, and how did it perform?
Thanks, Col

Hi There
Consistently obtaining about 500 Litres of a mixed fuel with average density of about 0.87. Mixing nicely with a 50% mix of conventional diesel.

I manage about 450kg's of shredded plastic and then add about 200L of used motor oil into the batch to obtain maximum amount of initial raw material.

Have enough product to proceed with cleaning the product. Centrifuge followed with a final filter and slow testing in a diesel vehicle.(next month or two)

This will be followed by stability testing with BHT.

Hence still very much in development stage, but definitely getting there!

[AAS]

Rope graphite gasket.

[AAS]

Hi Chris

There is nothing special about my pilot plant, just an upscaled version of the original concept.
If you want to upscale, I would not advice a continuous setup, bigger reactor = such a bigger BOOM if things go wrong. Keep it simple with a batch reaction. We are all DIY guys here and safety is important.

I invested allot of time on my plant and will give advice freely, but I will not give my "blue prints" that is part of the fun.

What I can say is, if you want to go bigger, stainless steel is king and a minimum of 10mm thickness everywhere! mechanical seals of reactor lid and I use additional graphite rope gasket.

Regards

AJ

[AAS]

Rope graphite gasket.

I find these graphite gaskets to be invaluable.

[Beyond Biodiesel]

In response to resent comments regarding continuous feed flash evaporation, the retort volume would function as the reflux zone. The retort size would need to be large enough to accommodate all of the coke accumulation until a scheduled cleaning cycle. So, my retort is 5gallons (20L) I observe only a thin film of black coke on each 5-gallon (20L) run. So I reason that I could use it as a flash evaporator to distill a few hundred gallons (x4L) of WMO before a cleaning cycle.

[Col]

Thank you Excalibur, AJ and BBD

Congratulations on great progress AJ!

If you want to upscale, I would not advice a continuous setup, bigger reactor = such a bigger BOOM if things go wrong. Keep it simple with a batch reaction. We are all DIY guys here and safety is important.

A continuous set up allows for a smaller reactor. Instead of boiling say 100L in an 8 hour batch run you can drip 100L onto a hot plate at 1.67L per minute. Asad said he has his oil go from feed stock to vapour within a few minutes so in this example that represents just 5L in the retort at any one time. Surely this is safer than a 100L retort? Pfaulder reckons they get their feedstock evaporated within seconds.
Downstream the system is the same as a batch system so no safety differences there. Is it upstream that you are concerned about? Having a bulk tank feeding to a hot system? Or is it the possibility of air entering a continuous feed system? I'd like to address any potential issue before fabrication.
Col

[Excalibur]

I'd bet there'd be some good set ups that could be engineered to make the flash evaporation concept work to good effect. Balanced matching of feed to heat applied might be something to look at. If my experiences of flash-boil-over events are anything to go by, then the carbon is going to come out with the product. I reason that if the feedstock oil is frothing in typical boil over fashion then a reflux will be completely ineffective.

A thought occurred as to a possible set up. Don't fit a reflux but have the outgoing product drop directly into a vessel which is heated to 300*C-350*C.
This vessel would then become the distiller so once any diesel has been boiling out, the remainder can be dropped back into the retort for re-cracking. This idea should work because the retort-outgoing-product is a mixture of cracked hydrocarbons, some of which are now in the diesel range. Heating to the aforementioned temperature will evap them.

If it was me, I'd be making a model to prove the concept. I think that making from 4" exhaust tube would be reasonably easy. Run numerous TC probes to monitor temps and use LPG heat for convenience. Make changes to dimensions, etc and retest. The object of spending the time at this stage is to get a good result that can then be scaled up.