How to turn plastic waste into diesel fuel cheaply

[imakebiodiesel]

If you are firing your retort for the first time, quarter fill it with water and boil the water. Check every weld and joint for leaks by smearing liquid soap over them. Seal any leaks before progressing.
For your first proper "burn" only half fill your retort. Add a quantity of kerosene which will boil and purge any air out of the system. It will also wash out your condenser. Take at least an hour to bring the retort up to temperature. Dont leave the reactor unattended during this time. Keep an eye on the bubbler and pressure gauge if you have one. If you are cracking plastics the process begins at 375 degrees C. Initially the flow of vapour will be very fast so keep the temperature below 385C for the first hour and then let it rise slowly to 410. Dont go above 420C, it serves no purpose and wastes energy.

[imakebiodiesel]

In a previous post I mentioned Specific gravity as a simple test for fuels. I would like to expand on that. First if you are using a hydrometer you must carry out the test at the temperature at which the hydrometer was calibrated, usually 20 degrees C.
The specific gravity will give you an indication of the main constituent of your fuel. So if your fuel measures .70 that does not mean it is entirely Octane. It means that the central alkane in your fuel is octane with equal amounts of alkanes above and below octane.
Here are some fuels and their specific gravities.
Pentane C5H12............0.63
Octane C8H18.............0.70
Decane C10H22...........0.73
Dodecane C12H26........0.755
Pentadecane c15H32....0.77
Our fuels will also contain Alkenes but their specific gravities are very close to their alkane counterparts.

You may have noticed that our fuels are much lighter than commercial petrol/gasoline, SG 0.74, kerosene SG 0.80 and diesel SG 0.84. This is because commercial fuels contain significant amounts of aromatics (cyclic hydrocarbons) which have completely different specific gravities. eg cyclooctane C8H16 has a SG of 0.84 compared to Octane C8H18 SG 0.70.

[jonathan]

reactor heating

right know l am working on retort when finished l post pictures l am confuse on reflux l want to heat the reflux with filament ? if yes what is the better tempreture to take all the fuels thanks

[sayshap]

If you are firing your retort for the first time, quarter fill it with water and boil the water. Check every weld and joint for leaks by smearing liquid soap over them. Seal any leaks before progressing.
For your first proper "burn" only half fill your retort. Add a quantity of kerosene which will boil and purge any air out of the system. It will also wash out your condenser. Take at least an hour to bring the retort up to temperature. Dont leave the reactor unattended during this time. Keep an eye on the bubbler and pressure gauge if you have one. If you are cracking plastics the process begins at 375 degrees C. Initially the flow of vapour will be very fast so keep the temperature below 385C for the first hour and then let it rise slowly to 410. Dont go above 420C, it serves no purpose and wastes energy.

How do you instal the temperature measuring equipment?
Do you dip inside the molten plastic or suspend in the path of the gases?

[jonathan]

retort

l am making 50 litres geyzer for retort l am going to make reflux on the retort l dont understand what l want to make in it and then 3 condensers to bubbler and put gas to a burner

[Excalibur]

How do you instal the temperature measuring equipment?
Do you dip inside the molten plastic or suspend in the path of the gases?

I use this kind of thing that I made from a BSP blanking plug and a length of steel tube. The near end of the tube is welded shut and where it fits the plug, it's brazed. That's the thermocouple alongside. Another one I made is 600mm long which reaches down into the feedstock.

[imakebiodiesel]

Nicely done Excalibur. That looks like a probe that will survive the harsh conditions inside a retort. I bought some on ebay that are similar made from stainless steel.
My probe protrudes into the top of the retort so I am measuring the vapour temperature just before it leaves the retort.
The reflux column must be packed with material which offers a large surface area to the vapours but will not block up. Rings cut from stainless steel pipe,
Stainless steel wool (pot scrubs) blocks of catalytic material all make good reflux fillings.
Control the temperature at the top of the column to get the fuel mixture you want. 350C for diesel, kerosene and petrol. 260C for kerosene and petrol, 176C for petrol only.

[jonathan]

reactor heating

thanks lmakebiodiesel l understand well know l hope l do it thanks l was going to do it like this on the picture what u thing?

[imakebiodiesel]

Your design looks good but the pipe that exits the top of the reflux should slope downwards to the first condenser. That way any condensing liquid will flow quickly into the first condenser rather than fill up the pipe and cause a blockage.
If your oil burner is the type to cycle on and off then you must not direct the uncondensable gases into the furnace. The burner would cycle off for a while, the gases would fill up the furnace and when the burner came back on ...kaboom!

[Marso Green]

Your design looks good but the pipe that exits the top of the reflux should slope downwards to the first condenser. That way any condensing liquid will flow quickly into the first condenser rather than fill up the pipe and cause a blockage.
If your oil burner is the type to cycle on and off then you must not direct the uncondensable gases into the furnace. The burner would cycle off for a while, the gases would fill up the furnace and when the burner came back on ...kaboom!

I could be wrong, but I'm proposing that the pipe out of the reflux should sloped upwards. Isn't it more precise for liquids to roll back into the reflux column rather than risk heavier fractions going where you don't want them?

Also, regarding the return line of uncondensable gases, wouldn't a pilot light solve/minimize the potential risk?

I also see a line going from first condenser to boiler. I think it opens up a risk of sending fractions that are too heavy for the boiler, plus potential clogging of pipe. I think this should only be done after testing the system extensively and ensuring the risk is very low.

Just an opinion though. I defer to the experts

Marso Green

[Excalibur]

I also see a line going from first condenser to boiler. I think it opens up a risk of sending fractions that are too heavy for the boiler, plus potential clogging of pipe. I think this should only be done after testing the system extensively and ensuring the risk is very low.

Isn't that line used to supply noncondensable gases for heating the first condenser if required? Please correct me if I'm wrong.

[Marso Green]

Isn't that line used to supply noncondensable gases for heating the first condenser if required? Please correct me if I'm wrong.

It seems to go to the main reactor, but I could be wrong. The diagram can be interpreted in more than one way. But whether the line carries noncondensable gases to first condenser or reactor is independent of the issue of connectivity between first condenser and reactor. Perhaps someone can explain exactly what it's supposed to do, and I believe that counting on the condensate from first reactor to fuel the reactor is high risk without insurance that it is the correct fraction for the burner used

[jonathan]

reactor design

thanks for every one l makebiodiesel thats not my design l post that design to see if it was good ok thanks for help l make that pipe downward. is there any size for reflux my retort is 50 litres geyzer l was going to mae the reflux column about 3 inch wide and 12 inch long is that good? thanks

[jonathan]

gas outlet

ok that gas that come from bubble goes to heat first condenser and goes to heat retort thats not my design l want to try it l dont thing there is anough gas to fire 2 burners

[imakebiodiesel]

The idea behind the reflux column is that any vapour that can make it to the top is fully cracked so the downward exit pipe ensures it does not flow back into the retort.
Sizing a reflux column is a bit of a black art. Your dimensions sound about right, tall and narrow is generally better than short and fat.
You are right about the amount of gas, it will not be sufficient to heat the first condenser and the retort. The design shows two valves that would allow you to control how much gas went to the condenser to get the right temperature and any excess would be diverted to the furnace.
A pilot flame or something similar would solve the problem of gas building up in the furnace.