How to turn plastic waste into diesel fuel cheaply

[rozier56]

wax problem

Hi folks,New problem for me, but i believe others have had this happen in past.
Brand new system built same as before but this time my heating source was a new duel fired diesel heater.Old system was on lpg gas, but bought new system to improve production time etc.The diesel heater has a capacity of producing 69Kw/hr..
When i fired up the system i reached 200*C IN 15min, all looked good, then started producing wax product that carried over to my collection tank.Stopped plant.
In the past with lpg this never happened.I think this is because i had a too fast increase in temp and caused blow through?
Only other change i made was to the distillation column, where i went from the plate system of baffel's which gave me a wet -out in certain temp range to a composite of fillings of metal internal.i.e simple distillation.
Would appreciate your feed back.

[Excalibur]

Hi folks,New problem for me, but i believe others have had this happen in past.
Brand new system built same as before but this time my heating source was a new duel fired diesel heater.Old system was on lpg gas, but bought new system to improve production time etc.The diesel heater has a capacity of producing 69Kw/hr..
When i fired up the system i reached 200*C IN 15min, all looked good, then started producing wax product that carried over to my collection tank.Stopped plant.
In the past with lpg this never happened.I think this is because i had a too fast increase in temp and caused blow through?
Only other change i made was to the distillation column, where i went from the plate system of baffel's which gave me a wet -out in certain temp range to a composite of fillings of metal internal.i.e simple distillation.
Would appreciate your feed back.

rozier56, there is not enough information and no pictures but some thoughts as a preliminary diagnosis..
The wax is uncracked plastic so some possible causes are.
Boil-over. Perhaps too much volume of heat pushes the product through all to quickly and forcefully.
Reflux problem. Perhaps the increase in heat is causing the reflux to overheat. Too hot reflux temperature will cause product to escape without any cracking.

Where in the reactor is the temperature probe? Top, side, bottom, etc?
What temperature did the reflux reach?
Is there a temperature probe monitoring the burner flame?

Please inspect your pipework, condensers etc for wax & plastic blockage before attempting to re-run.

It occurred to me after my last run that the temperatures, setting, size of parts etc are all working in a kind of harmony so changing components can have unexpected effects. In my case, I'd added insulation to the retort and I found I had to use less heat.

kedigen. Nice work. Am really wishing you well and good success.

[rozier56]

Hi Excal,Thanks for your input,i have attached a picture for your info and will expand further if it works.Ok, got some pics to work.
Plant retort is 240kg.
Reflux is 42lt capacity.This is were i measured 200*c when the problem started.
Condenser internal pipeware 1inch.
Temp measurement is on top of the reflux column and on the diesel chamber.
Retort has 10cm vermiculite insulation
Reflux has 8cm vermiculite insulation.
Low density plastic used as raw material, i.e irrigation pipe.
I am going to learn how to reduce the burner output to get a better temp control.

[Excalibur]

I suggest a thermocouple probe for the retort that extends into the liquid. The signal from this can be made to start and stop the burner and maintain the correct temperature range. I'm about to fit a new mineral insualted thermocouple for my retort with controller for my burner shortly and will be updating this info soon.

For the burner, a smaller nozzle to put the heat output into a better range may be required. See this Delavan nozzle PDF for some good information.

[Beyond Biodiesel]

my system details

Impressive machine kedigen. I hope it works out well for you. It looks like you will be heating it with liquid or gaseous fuels?

[rozier56]

Excalibur, thks for your response, i had a lesson on control of my duel burner and found out it was set at max output{65Kw/hr}. far too hot,reset to 40Kw great temp control.Great info on your blog site,have a few questions.
What is the volume of your retort?
At what reflux temp do you get best diesel production?
Are you happy with the ungrounded K-type thermocouple?
If one produces waxing material is this too high temp or too low temp?
Most info shows best diesel production at 280*c? in the distillation column.
My raw material is ldp plastic.Thanks.
Anybody can please respond to these queries.

[Excalibur]

Excalibur, thks for your response, i had a lesson on control of my duel burner and found out it was set at max output{65Kw/hr}. far too hot,reset to 40Kw great temp control.Great info on your blog site,have a few questions.
What is the volume of your retort?
At what reflux temp do you get best diesel production?
Are you happy with the ungrounded K-type thermocouple?
If one produces waxing material is this too high temp or too low temp?
Most info shows best diesel production at 280*c? in the distillation column.
My raw material is ldp plastic.Thanks.
Anybody can please respond to these queries.

Retort is 47 liters.
Reflux temperature target is 350°C on wmo feedstock. This gives a specific gravity of .84 ~ .85 SG. I haven't tried plastics in this retort yet but the reflux figure would be reduced if waxing occurs.
Ungrounded thermocouples are essential for some types of electronic equipment. Feedback voltage spikes on the earth/ground cause problems for sensitive readings and thermocouple readings are already incredibly minute that ANY stray voltage will upset them. My large red LCD's and the Arduino thermocouple breakout board both require non-grounded. The cheap Chinese handheld meters are Ok with grounded presumably because their battery is not itself grounded. K-type is the way to go for us DIY diesel makers. Be sure to check the maximum degrees a k-type TC can read. I think the rule is that thinner TC wires can only read up to a certain temperature figure.
Typically, fuel waxing will be too high temperature in the reflux. This assumes that the retort is not in any kind of boil-over mode with it's temperature carefully controlled somewhere in the region of 380°C ~ 425°C.
When Jetijs had waxing problems he solved it by cooling the reflux to 150°C
See post 680
I recommended k type TC for retort, reflux and burner, otherwise you are working blind.
I just today ordered a new mineral insulated k-type TC and a PID controller

[rozier56]

Do you think Jet's mention of "refluctor" actually reasons as our "reflux zone"?
My reflux is 300mm diameter at the base and sits directly on top of my retort, their is no "v" cone shape on the base as he mentioned!
You mentioned that your reflux is measured approx 380*c with WMO.for good results.I would have thought that melted plastic reverts back to hydrocarbons similar to waste motor oil,not exactly same,but still hydrocarbons.Therefore your higher temp value at reflux interests me.My next run tomorrow will be a mixture of LDP AND USED MOTOR OIL.This way also allows me to get more product in my retort.
Great info on K-type thermocouple, i currently use the same,not sure if grounded or not.Those PID control items are so cheap on that site compared to South Africa.i.e four times cheaper.
THKS.

[Excalibur]

Do you think Jet's mention of "refluctor" actually reasons as our "reflux zone"?
.

Yes

My reflux is 300mm diameter at the base and sits directly on top of my retort, their is no "v" cone shape on the base as he mentioned!
.

Don't worry about the v shape. As long as any condensed hydrocarbons are able to run back freely to the retort, all will be well.

You mentioned that your reflux is measured approx 380*c with WMO.for good results.I would have thought that melted plastic reverts back to hydrocarbons similar to waste motor oil,not exactly same,but still hydrocarbons.Therefore your higher temp value at reflux interests me..

Note, I mention 350°C as my reflux target. At the 380°C, there would be almost no refluxing going on, in other words you'd be getting out product at much the same weight you were putting in. The temperature is really a balance of a number of variables so each operator needs to be ready to adjust it to suit their particular conditions. Perhaps the most important criteria deciding the reflux target is the weight of product being produced.
Product produced too heavy: remedy = lower the reflux temperature.
Product produced too light: remedy = raise the reflux temperature.

My next run tomorrow will be a mixture of LDP AND USED MOTOR OIL.This way also allows me to get more product in my retort.

Good idea. Fill to about 3/4 maximum for safety.

Great info on K-type thermocouple, i currently use the same,not sure if grounded or not.Those PID control items are so cheap on that site compared to South Africa.i.e four times cheaper.
THKS.

The k-type is industrial quality 1.5m long so it can reach near the bottom of the retort. The cheaper k-type with fiberglass insulation would not last as the insulation deteriorates.
The PID controller is not the cheapest either. Others are there if you want to take the risk. I look carefully at a sellers rating and also what Google can tell me about the product, in this case the Sestos brand had good reports.

[dedooo]

Hello all, I want to ask this Can I put food oils used in the pyrolysis retort? And What do I get? Thank you

[rozier56]

Excalibur,looking at you web site i seem to notice you have a long pipe between your reflux area and your condenser?Also i assume the condenser is slightly pointed down?
Reason for the above questions is because we ran the wmo/plastic run and got good results for diesel at temp 289-350*c.We made wax when we ran higher temp.The higher temp produced good liquid product when extracted but waxed on cooling to room temp.Produced good quality rate at higher temp not at lower temps 280-350*c.
Do you reflux any of your product after condenser back to retort during a run?
If that pipe i mentioned above does exist then that will act as a reflux return.trying to figure out your production rates?
Derek.

[Beyond Biodiesel]

Hello all, I want to ask this Can I put food oils used in the pyrolysis retort? And What do I get? Thank you

There are a number of ways to convert vegetable oils to diesel fuel, which are a lot simpler than distilling and cracking them. Also, cracked vegetable oils tend to produce profoundly toxic byproducts, so it is generally frowned upon.

[Excalibur]

Excalibur,looking at you web site i seem to notice you have a long pipe between your reflux area and your condenser?Also i assume the condenser is slightly pointed down?
Reason for the above questions is because we ran the wmo/plastic run and got good results for diesel at temp 289-350*c.We made wax when we ran higher temp.The higher temp produced good liquid product when extracted but waxed on cooling to room temp.Produced good quality rate at higher temp not at lower temps 280-350*c.
Do you reflux any of your product after condenser back to retort during a run?
If that pipe i mentioned above does exist then that will act as a reflux return.trying to figure out your production rates?
Derek.

Yes, the long pipe is several meters long and runs downhill. The condenser also runs downhill. There is a smaller pipe which is coolant for the condenser.
If you are getting wax, then uncracked hydrocarbon is getting past the reflux. You don't say whether it's retort or reflux temperature that you are quoting but I believe it's the latter? The fact that wax is coming points to either the retort and/or the reflux being too high in temperature.
When both retort and reflux are in harmony for temperature balance, hydrocarbons will automatically recycle until they fail to condense in the reflux and subsequently are allowed to escape downstream.
I do not need to return any product for re-cracking because once it exits my reflux it's already no.2 diesel by weight. If yours is not, most likely it's a temperature problem.
I suggest a thermocouple for the retort (in the liquid) and another for the reflux (near the exit). Start heating and hold retort at about 400°C. Then observe the reflux. If it's too high, remove some insulation or apply some other method of cooling.

[wheels]

Excalibur, thks for your response, i had a lesson on control of my duel burner and found out it was set at max output{65Kw/hr}. far too hot,reset to 40Kw great temp control.Great info on your blog site,have a few questions.
What is the volume of your retort?
At what reflux temp do you get best diesel production?
Are you happy with the ungrounded K-type thermocouple?
If one produces waxing material is this too high temp or too low temp?
Most info shows best diesel production at 280*c? in the distillation column.
My raw material is ldp plastic.Thanks.
Anybody can please respond to these queries.

260-280 degC is the condensing point of fractions that give a specific weight equal to Diesel. That does not mean you should operate the Reactor at 280degC. You will need a temperature in the range of 400-500, 460 being optimum. Then you need a catalyst and reflux vessel with a temperature of either that 260-280 to capture the Diesel fuel, or 350-400degC(optimum temp if you are using a Catalyst), but will need further distilling. Heavy fractions, which include the Paraffin (wax) are in the temperatures of 300deg and upwards. These need to be dropped back to the Reactor vessel to be cracked further and eventually they will pass the 350degC reflux/cat and flow on through. You need another distilling vessel at a temp of around 160deg to remove the very light fractions from your Diesel. It depends on how much of the Benzene and lighter fractions you want in your Diesel.
Please note that all the temperatures I have listed above, are approximate as each and every set up is going to differ for people. That is where a lot of practice and patience will come in to see what you produce.

[Beyond Biodiesel]

I just today ordered a new mineral insulated k-type TC and a PID controller

It is hard to tell from the photo, but that TC does not leak like it is sheathed. If it is not sheathed, then how are you going to seal it so that it does not leak. or are you planning on placing this TC outside of your pyrolysis unit?