How to turn plastic waste into diesel fuel cheaply

[Excalibur]

Col, it's great that you are taking the time to think the system through. The answers are not clear cut. Much depends on size, shape, design etc.
However some points come to mind. The bigger the retort vessel, the more the need will be to cool the downstream flow. With vapor will travel heat so the more heat generated means the downstream equipment needs to be sufficient to handle the volume.

My mk6 retort needs an insulated reflux and a cooled diesel condenser trap.

I believe the 500*C target will be too high. Be wary of boil-over conditions. I liken it to a pot of milk boiling over on a stove. The feedstock will be cracking at that temp but it won't be distillation. I've seen boil-over in my sight glass before. It looks a very dark red and kind of "lumpy". Avoid.

Re, being left with ash rather than tar. The last part of the process may take more energy than will be economic. It might be more prudent to snip the run early rather than waste fuel/heat for little return.

The reflux temperature will determine what weight of fuel that gets trapped in the first condenser. You said 380*C, so try it and see. If the diesel is too heavy then reduce the figure, if too light then raise it. For comparison, my last run I targeted 300*C and the diesel was slightly light weight so I'm aiming for 320*C next time. The way I see it is, the highest temperature that gets the correct result is best as this uses less energy to obtain.

On my earlier prototypes, I discovered that my condensers were woefully inadequate to deal with the vapor stream heat. With a big retort there's lots of heat and the flow of vapor is relentless.

So,,, some opinion to ponder and puzzle over. In any case make a start. Don't expect everything to be perfection first time. It's too complex. Consider it as "work in progress".
Hope this helps.

[Col]

Are both heating and cooling required?

I try to completely cover the entire retort with heat. Any area of the retort that is not covered with heat is going to be a cold zone where refluxing will take place and prevent movement of vapors down stream to the condensers.

I have about 5 condensers. The first one is heated to 300c, the 2nd one is heated to 200c, the 3rd is heated to 100c, 4th is ambient temperature, 5th is 0c.

Every heated trap is also very well insulated, and I do not turn the heaters on the traps until the retort is done evaporating the sample. This allows the traps to be heated by the vapor-stream, so that my heaters only have to work a little to boost the temperature of the trap and hold it at its control point, and only as long as needed to evaporate any light fractions, which go to the next trap and heat it up.

Thanks Excalibur and BB. Sounds like you have great efficiency and tight control over the heating of your system BB.

Something I have been puzzled by is whether (in a continuous drip feed system with very good insulation) I will need to regulate the temperature of the reflux chamber and condensers # 1 or # 2 DOWNWARD. Much has been said of heating and insulating these chambers, and varying the length of pipes between them to manage temperature drops. So I know I will need to heat and insulate these chambers, but do I need to be able to COOL them in a continuous system??

If the vapours are leaving the retort at 500C (I just want to be left with dry ash rather than tar at the end of a cycle) should I build into my system the ability to heat AND cool the reflux zone to strictly keep it at 380C? ie. would a constant flow of vapours from a 500C retort heat the reflux zone above 380C, so I need to cool it a bit? And would a constant flow of 380C vapours from the refluxing zone heat the first condensing chamber above 180C, so I need to cool it a bit? I intend to hold the retort at 500C, the reflux at 380C and the first condenser at 180C, then cool the remainder of the vapours after that. So I catch all vapours between 380C and 180C to be used for diesel.

I recognise the answer to this question depends on how 'closed' my system is. But those of you who have experience with the practical limitations of your insulation will have an idea of whether the heat losses through your insulation are enough to pull the temperature down enough between chambers.

I recall way back there was talk of needing to pull insulation off the system to stop it getting too hot. I don't remember if this was because they couldn't regulate their heat source properly or because the vapours carried too much heat to the next chamber?

Using a hot plate and heat bands, will it be enough to just regulate the chamber temperature via thermostat controlled heaters? or will I need to leave some of the chamber walls exposed and cool them with a fan sometimes? BB's experience tells me that in a batch system I can rely on heating only and not need to cool anything. But in a continuous system there will be no heat sink / cold chamber for the vapours to transfer their heat into as the system chambers will be kept hot continuously.

I looked at strict temperature regulation using thermic oil but I would need to pressurise the oil to 400psi to achieve a temperature of 430C. I'm not really interested in hot oil at that pressure.

Thanks
Col

[Beyond Biodiesel]

Hi BB
Do you mean you have a 2kW hot plate under your retort? or do your hot plate, band heaters and line wrap heater all add up to 2kW?

I have 4 heaters on my retort. They are capable of delivering about 2KW each; however, I use variacs to regulate the voltage down to 2KW total to meet my solar gain.

All those heaters just listed are for your retort and reflux right?

Correct. I try to completely cover the entire retort with heat. Any area of the retort that is not covered with heat is going to be a cold zone where refluxing will take place and prevent movement of vapors down stream to the condensers.

I recall your retort and reflux are one chamber.

Correct. I just fill my retort about 3/4 full and I have metal screen above that for reflux area.

So no heaters are used on the condensers? just insulation?

Incorrect. I have about 5 condensers. The first one is heated to 300c, the 2nd one is heated to 200c, the 3rd is heated to 100c, 4th is ambient temperature, 5th is 0c.

You mentioned you are probably getting about 2L/hr during peak distillation / cracking. So as far as sizing our units and heat / power supply it looks like each 1L of WMO will take about 1kW to vapourise / crack it in about 1 hour once the retort is up to temperature.

As I posted up thread it is only about 100watts/lit to operate my entire WMO distillation system. Part of my success in doing so much with so little is my retort has 4" (10cm) of insulation all around it, and I have spent years developing insulation practices for these temperatures.

Every heated trap is also very well insulated, and I do not turn the heaters on the traps until the retort is done evaporating the sample. This allows the traps to be heated by the vapor-stream, so that my heaters only have to work a little to boost the temperature of the trap and hold it at its control point, and only as long as needed to evaporate any light fractions, which go to the next trap and heat it up.

Excalibur - how much fuel does your turk burner consume per batch / continuous cycle? How many litres are produced per batch / shift? Interested to know the efficiency of an oil burner v electricity. The liquid fuel will no doubt be a lot cheaper / free but I'm in the suburbs cut up into 800m2 blocks and don't think I could get away with any kind of oil burner so close to neighbours.

Thanks.
Col

I am very impressed with Excalibur's work and success. There are a number of advantages in using gas, liquid or solid fuels, such as dollar per watt; however, one is not going to get the control needed to safely and efficiently crack and fractionate hydrocarbons with flames, than one is going to have with electricity.

Also, having a flame anywhere near a cracking and fractionation system poses a serious fire and explosion hazard. So, I choose not to use fuels, but electricity for heating my retort and condenser traps.

[Excalibur]

Hi BB
Do you mean you have a 2kW hot plate under your retort? or do your hot plate, band heaters and line wrap heater all add up to 2kW? All those heaters just listed are for your retort and reflux right? I recall your retort and reflux are one chamber. So no heaters are used on the condensers? just insulation?

You mentioned you are probably getting about 2L/hr during peak distillation / cracking. So as far as sizing our units and heat / power supply it looks like each 1L of WMO will take about 1kW to vapourise / crack it in about 1 hour once the retort is up to temperature.

Excalibur - how much fuel does your turk burner consume per batch / continuous cycle? How many litres are produced per batch / shift? Interested to know the efficiency of an oil burner v electricity. The liquid fuel will no doubt be a lot cheaper / free but I'm in the suburbs cut up into 800m2 blocks and don't think I could get away with any kind of oil burner so close to neighbours.

Thanks.
Col

Sorry, I wish I'd made better effort to count the liters for the recent 130L run. I'd be totally guessing at 15 - 20 liters however the figure itself is distorted due to the addition of the non condensable retort gases being burned as fuel. The fuel/oil/diesel burned was free and I made no attempt to economize at this early development stage.
I have latest pics up of my Turk burner head on DIYDiesel blog under appropriate sections/pages.

[Col]

1kW per 1L per 1hr?

How much volume are you dumping 2KW into? I am using about 2KW for 20L. I could put more heaters on, but I do not have the power. So I use a lot of insulation to do more with less.

Hi BB
Do you mean you have a 2kW hot plate under your retort? or do your hot plate, band heaters and line wrap heater all add up to 2kW? All those heaters just listed are for your retort and reflux right? I recall your retort and reflux are one chamber. So no heaters are used on the condensers? just insulation?

You mentioned you are probably getting about 2L/hr during peak distillation / cracking. So as far as sizing our units and heat / power supply it looks like each 1L of WMO will take about 1kW to vapourise / crack it in about 1 hour once the retort is up to temperature.

Excalibur - how much fuel does your turk burner consume per batch / continuous cycle? How many litres are produced per batch / shift? Interested to know the efficiency of an oil burner v electricity. The liquid fuel will no doubt be a lot cheaper / free but I'm in the suburbs cut up into 800m2 blocks and don't think I could get away with any kind of oil burner so close to neighbours.

Thanks.
Col

[octavio]

Thanks for your previous replay, I hav

tankyou very much for your tips I really apreciate it¡

[octavio]

Nice design, thanks for posting and welcome.

1) Optimum Cracker/retort temperature range
I just completed a run of WMO and found I was getting good results up to 405*C. I didn't experiment with any higher temps on this run with this retort. I would say aim at the 400*C mark and tweak from there. Too much temperature will risk boil over while too low is slow. Note also that my retort is tall and skinny so that amongst other things will create variables. Feedstock will have a bearing on the target temps too, for example my current lot has some white spirits mixed in so this boils off early.

2) Optimum Reflux temperature range
Ok, I was aiming at 300*C and in doing so I made winter diesel of .83 SG. In other words it was a little on the light side. I'll be aiming at slightly higher temp next time perhaps 320*C. It's early days but I'm going to remove the reflux swarf packing and improve the insulation. There was no catalyst.

3) Optimum 1st condenser temperature range to fraction off anything lighter then Diesel
This was talked about only a few weeks ago. I was aiming at 80 -100*C but my set up was struggling to reach the mark. Still the diesel was OK so I'm not sure what to recommend. You could choose a relatively low temp and simply expose the diesel to that temp for a longer duration, which would achieve the same result.

Hope this helps...

Thanks for your previous replay, I hav

[Beyond Biodiesel]

Thanks Beyond,seems very low,is that with wmo?

Yes, I am just distilling WMO at this time, and my goal is far less than Excalibur's. I am only interested in 5 gallons (20L)/day to meet my fuel demands.

i am cracking ldpe and concerned about the low production rate.one more question is what Kw/energy is required to achieve the desired cracking point. i am burning a 50kw/gas burner to achieve the 400*c plus, how does tha t compare with others out there?

You are using about 20 times more power than I am using, but I do not know what volume/mass you are working with. For perspective 5 gallons (20L) of oil weighs about 35 pounds (16KG). This means power per unit volume is 1KW/2.5gal (10L); or 1KW/17.5lbs (8KG); or 100w/L; or 125w/KG.

[Excalibur]

Hi Guy's, Has Any Body Out There Got An Idea Of What Production Rate Can Or Should Be Achieved,assuming You Have The Correct Cracking Temp Of 4oo*c.in The Retort. I.e.ltrs/hr.
Thanks.

During my last run I got 10 liters per hour average. I'm currently revising the set up, aiming for 20 liters+ per hour average. Currently I'm cracking waste oil, mostly hydraulic and gear oils. My retort is 47 liter capacity though I aim to constantly fill to about 3/4 level. I have no idea on the KW of heat but I use homemade diesel plus retort generated gases for the flame.

My stock of diesel for my van has all been used so I'm working long hours to take the next steps to re-run the turk-retort as soon as possible. My upgrades will be revised efficiency diesel/oil burner head, preheating for the turk and retort feeds, new pump on feedstock, insulation on reflux and diesel reservoir. I will open up my retort for it's first ever clean out so I'll be making up special tools to reach the 1.5 meter deep vessel bottom. At this stage I'm planning on initially filling with PE/WMO to the 3/4 mark.

Pics and details will be up on my DIYdiesel blog over coming days as time permits. Also more Youtube, hopefully one of the turk burner head as well.

HTH

[ladanivaca]

mixed plastics and OMM

can be mixed in the plastic and pyrolysis process in the same deposit OMM

thanks

[rozier56]

Thanks Beyond,seems very low,is that with wmo? i am cracking ldpe and concerned about the low production rate.one more question is what Kw/energy is required to achieve the desired cracking point. i am burning a 50kw/gas burner to achieve the 400*c plus, how does tha t compare with others out there?

[Beyond Biodiesel]

I did't knew you use batteries. Do you think it will be possible to use direct solar energy via the pv panels to heat the retort in a bright sunny day without the use battery stack ?

Theoretically, if you have the gain, then you could directly dump the watts into resistance heaters. You could even dump the DC right into your heaters without a charge controller or inverter in the way.

However, most resistance heaters are designed for 110 or 220 V. You could solve the voltage problem by wiring your solar panels in series to get the desired voltage.

btw link is not working...

Yes, the forum is down while it is being moved to another server. It hopefully will be back up in a few days.

BB,my retort is 19 ltr. 2kw.
it takes roughly 1 hr to get to 400°C
and i am measuring the retort temparature(thermowell)
,not the heater temp.

I am impressed.

Hi Guy's, Has Any Body Out There Got An Idea Of What Production Rate Can Or Should Be Achieved,assuming You Have The Correct Cracking Temp Of 4oo*c.in The Retort. I.e.ltrs/hr.
Thanks.

I get roughly 1L/hr from start to finish, but nothing for the first hour while the temperature rises. So, the rate is probably 2L/hr during the peak cracking/distillation period.

[rozier56]

rozier56

Hi Guy's, Has Any Body Out There Got An Idea Of What Production Rate Can Or Should Be Achieved,assuming You Have The Correct Cracking Temp Of 4oo*c.in The Retort. I.e.ltrs/hr.
Thanks.

[octavio]

tanks for the tip

[ashiki]

BB,my retort is 19 ltr. 2kw.
it takes roughly 1 hr to get to 400°C
and i am measuring the retort temparature(thermowell)
,not the heater temp.