How to turn plastic waste into diesel fuel cheaply

[Excalibur]

with the chemical mixture, is there a formula similar to diesel fuel?

Diesel does not have a specific formula because it is not a single compound. Instead, diesel is made of a mix of saturated hydrocarbons and aromatic hydrocarbons.
Diesel is about 75% saturated hydrocarbon and 25% aromatic hydrocarbon. The average chemical formula for common diesel is C12H23, ranging approximately from C10H20 to C15H28.
Hope this helps else rephrase or elaborate the question.

[rozier56]

rozier56

Hi FOLKS,
Are you guys still out there?
No query's or responses for a long period.

[Excalibur]

I'm still here..
Waiting for diesel prices to go astronomical again. It's the calm before the storm.

Ha! I've always wanted to use this smilie

[rozier56]

rozier56

Hi Excalibur,are you available on skype?
My SKYPE is derek.cornish2.

[rozier56]

rozier56

Excalibur,
Do you control your burner switching on/off from your retort temp controller,or from your distillation control?
Is your retort temp probe measuring liquid content or the gas above the liquid?
Thks.

[Excalibur]

Excalibur,
Do you control your burner switching on/off from your retort temp controller,or from your distillation control?
Is your retort temp probe measuring liquid content or the gas above the liquid?
Thks.

The burner switches according to retort temperature. The burner does not switch off completely, it toggles between power mode and idle mode in response to settings of the controller. Both power mode and idle mode set points are individually adjustable with a screw stop on the burner itself.
Retort probe measures the liquid temperature. There is an additional probe at the top of retort in the flange but it only monitors temperature on a display for the operators' information.

[rozier56]

rozier56

I have a machine burning waste plastic shreds.When we reach temp of 285*c we produce product of 0.78 on hydrometer.
We increase temp by 1*c and it starts to wax when cooled too 20*c.
Just cant get to the 0.80 on hydrometer to clear as diesel.
Any idea's?

[Excalibur]

Is the 285°C temperature recorded at the reflux tower? If yes, then what is the simultaneous retort temperature?

How many KW is the burner? or liters per hour?

[wheels]

I have a machine burning waste plastic shreds.When we reach temp of 285*c we produce product of 0.78 on hydrometer.
We increase temp by 1*c and it starts to wax when cooled too 20*c.
Just cant get to the 0.80 on hydrometer to clear as diesel.
Any idea's?

What temperature are you testing the Fuel at?
I am not sure why you want to test SG. It tells you very little, if anything at all. But SG of Fuel and Oils is measured at a Temperature of 60degF/15.6degC. What will probably be more important to you is the Viscosity.
What Plastic stock are you using? That is more important re what range of Hydrocarbons are produced. Also making the Retort hotter is going to produce lighter weight fractions, thus the SG is going to be lighter, not heavier. You probably want to decrease the temperature and see what you get, rather than increase it.
What size is your reflux vessel and are you using any form or Catalyst? You need to play with both those area's. If the heavy chains stay too long in the reflux, or cycle too much, they may break down too much.

[rozier56]

rozier56

The retort temp's sit at 325*C to 330*c.
The plastic is ldpe and hdpe pellets and shredded.
We test samples from beginning of production for flammability as we work. paraffin and petrol produced will flame when ignited. Diesel wont burn, so when we achieve this we check hydrometer at 20*c sample and waxing.
My retort size is 310 lt and the reflux 96 lt.
The burner is a 28 kW/HR. This burner is auto controlled to switch on and off at desired temp, either at retort or reflux settings.
It takes me 2,5 hrs to reach desired temps, ie,280*c in reflux column measured at top of column.

[Excalibur]

The retort temperature is extraordinarily low. That's below the temperature at which cracking even begins, 350°C.
The vessel sizes seem reasonable though important is the temperature each vessel can maintain.
I disagree with Wheels with the the view that hotter reflux make lighter product. I believe cooler refux make lighter product because more vapor is able to condense at cooler temperatures, therefore more condensate runs back to the retort. Lighter fractions that resist the condensing effect of the reflux, move downstream and condense as product in the downstream condensers.

Rozier, does the burner use about 2 - 3 liters per hour?
I'd expect very little flow at retort temperatures of 325°C - 330°C, Such flow would be very light fraction and crystal clear.
Are you sure your KW and temperature figures are correct?

[rozier56]

rozier56

The burner is a FBR burner.When i use the 0.50 nozzle the flow rate is 1,8 kg/h,which is 18-22kW /HR.
When we use the 0.75 nozzle the rate is 2.8 kg/h which is 30-33kW /HR.
When i use the 0.75 nozzle my retort heats too quickly and we end up with boil over and make wax.
We have tried the 0.5 nozzle and although the heat up is slow, when we get too retort 390*c and reflux at 322*c we have product that varies between 0.78 and 0.79 on hydro at 20*c.
As we hit the 400*C in retort and 350*c in reflux we get 0.81 at 20*c on hydro.
A 5*C increase in retort will start to give us wax.

[wheels]

The retort temp's sit at 325*C to 330*c.
The plastic is ldpe and hdpe pellets and shredded.
We test samples from beginning of production for flammability as we work. paraffin and petrol produced will flame when ignited. Diesel wont burn, so when we achieve this we check hydrometer at 20*c sample and waxing.
My retort size is 310 lt and the reflux 96 lt.
The burner is a 28 kW/HR. This burner is auto controlled to switch on and off at desired temp, either at retort or reflux settings.
It takes me 2,5 hrs to reach desired temps, ie,280*c in reflux column measured at top of column.

The issues with all this are many and varied. This is the problem when ones cross the boundary from a small scale amateur operation to a larger commercial operation, but still using amateur methods. You simply cannot upscale these plants and expect the same results. So many parameters change.
First important question here.....does your retort rotate or do you have any means of stirring the material within the Retort ?
A couple of important points.
28Kw is far from enough heat for 310ltr vessel. You want close to 10 times that.
Plastic is an insulator of Heat. So you need to get that heat right through the Plastic evenly. That is not possible unless the Plastic is stirred or the retort rotated. Otherwise you get plastics overheated where they are closer to the Hot wall of the vessel and not hot enough further on in. The plastics that are heated on the outside then become an even greater insulator to the unmelted on the inside of the mix.
Different plastics naturally produce different weights of Hydrocarbons chains. PE in particular produces Wax. Different plastics also require different heat input. But there are also multitudes of variables that result in what the output stream comprises of. Some commercial operations work with temps as low as 300degC. But some work with Temperatures as high as 900degC. So actual temperature is meaningless unless Time is factored in. Time being the amount of time a Hydrocarbon chain remains within the retort and thus the heat source.
Reflux is purely to re crack long chains that made it out of the Retort. But of long chains do not exist, then re cracking shorter chains is not needed. Heat/time result in the chains braking to ever smaller. More heat and/or longer time the chains are exposed to the heat results in lighter fractions produced.
Commercial plants do not try to produce fuel within the retort itself. They produce a range of Hydrocarbons and then that output is sent to another part of the plant to be cracked into the various fuel outputs they want.
That is all just a brief outline of the complexity of doing this commercially. There is much much more to it than just this even.

[wheels]

The burner is a FBR burner.When i use the 0.50 nozzle the flow rate is 1,8 kg/h,which is 18-22kW /HR.
When we use the 0.75 nozzle the rate is 2.8 kg/h which is 30-33kW /HR.
When i use the 0.75 nozzle my retort heats too quickly and we end up with boil over and make wax.
We have tried the 0.5 nozzle and although the heat up is slow, when we get too retort 390*c and reflux at 322*c we have product that varies between 0.78 and 0.79 on hydro at 20*c.
As we hit the 400*C in retort and 350*c in reflux we get 0.81 at 20*c on hydro.
A 5*C increase in retort will start to give us wax.

You can't be heating evenly. On my first trial plant, I used 2Kw of electric heat for just a few ltrs of Plastic. On my next rest plant, I used 40Kw on 50ltrs of Plastic. The output pipes are 60mm. I struggle to get enough heat even with that. But due to the fact that I need to heat the plastic quickly and get it through the system quickly.
Too much cracking due to excessive time can cause wax.
PE naturally produces Wax.

[Excalibur]

The burner is a FBR burner.When i use the 0.50 nozzle the flow rate is 1,8 kg/h,which is 18-22kW /HR.
When we use the 0.75 nozzle the rate is 2.8 kg/h which is 30-33kW /HR.
When i use the 0.75 nozzle my retort heats too quickly and we end up with boil over and make wax.
We have tried the 0.5 nozzle and although the heat up is slow, when we get too retort 390*c and reflux at 322*c we have product that varies between 0.78 and 0.79 on hydro at 20*c.
As we hit the 400*C in retort and 350*c in reflux we get 0.81 at 20*c on hydro.
A 5*C increase in retort will start to give us wax.

I would try reducing the burner heat when your retort goes above 400°C. If that works then it's likely the retort was becoming too lively, frothing up and overwhelming the reflux. Froth is not vapor. It's "bubbles and liquid" .The reflux won't cope and will lose its' ability to separate heavy fractions from light.