How to turn plastic waste into diesel fuel cheaply

[AAS]

Rope graphite gasket.

[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!

[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.

[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

[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]

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]

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.

[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?

[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?

[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.

[Excalibur]

Hi folks,How is this idea?
My retort is 850mmlengthx333mmwidth radius.=296metres.
Proposed retort to be placed directly on top of retort is 1meter x 12mm width radius =45 meters.
How does that sound keeping in mind that 1/4 of 296 =74meters.
Another point is that the retort temp in my case is always higher than my reflux temp.Temp is measured in retort open area and reflux at the top of the reflux

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

There are still some errors in your earlier post with dimensions, etc
Please review and correct these.
Is the reflux radius 12cm not 12mm??
Is the retort 296 liters or .296cubic meters (not 296 metres)??

Edit: Ok so I think I worked out what you are saying. The proposed reflux is maybe too small being only 45 liters when the 1:4 recommendation is 74 liters. If it's what you have and especially if it's already made, I'd go with it. Consider mounting it a bit further away with a short length of pipe to compensate for the lesser volume.

[Excalibur]

I don't think I would want a float filled with air inside the retort come to think of it. If not air, then what? A large, disc-like float might be good, it would 'absorb' a lot of the violence inside the retort and give a more steady read, but the bigger the float is the more it impinges on the surface area of the oil which we need for evaporation.
If we had a pipe off to the side of the retort (to get away from the splashing etc) with a steel ball floating in it, and made the pipe of borosilicate or some other non-metallic material, we could use the floating steel ball to actuate a series of magnetic relays which would then tell us the oil level - like this...

The level readings from all three could be assisted by putting baffles made from perforated sheet around the level sensor. You could also program the controls for the feed pump to wait for the sensor to stabilise over a period of a few seconds before actuating the pump, just to be sure.

Apart from the colour and sediment, what was the quality of the product produced by flash-boiling? Still ok?

How about an inert gas, perhaps argon or nitrogen for the float. Some study needed on this.

Sensors for the level would be great for automatic feed. It could also be connected to an alarm system.
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. Mount the cylinder vertical so the spear protrudes into the retort with float attached to its' end. Ensure the spear is free to move and the cylinder to retort has a perfect seal. Attach proximity sensors to the cylinder to sense the magnetic piston position. Remove any seal on the cylinders' piston and plug the air in/outlets.

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.

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

[rozier56]

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

[Col]

Petroleum handbook

...The Petroleum Handbook compiled by Royal Dutch Shell, 3rd edition 1948. ...I highly recommend the book

Thanks, just bought one!

[Col]

steady float level

The level readings from all three could be assisted by putting baffles made from perforated sheet around the level sensor.

Actually, you could just put a sheet wall around the level sensor so long as it was open at the bottom and top to allow the oil level to rise and fall. The smaller the allocated enclosure the less turbulence.