The process is really simple, it is similar to how alcohol is made. If
you heat plastic waste in non oxygen environment, it will melt, but will
not burn. After it has melted, it will start to boil and evaporate, you
just need to put those vapors through a cooling pipe and when cooled
the vapors will condense to a liquid and some of the vapors with shorter
hydrocarbon lengths will remain as a gas. The exit of the cooling pipe
is then going through a bubbler containing water to capture the last
liquid forms of fuel and leave only gas that is then burned. If the
cooling of the cooling tube is sufficient, there will be no fuel in the
bubbler, but if not, the water will capture all the remaining fuel that
will float above the water and can be poured off the water. On the
bottom of the cooling tube is a steel reservoir that collects all the
liquid and it has a release valve on the bottom so that the liquid fuel
can be poured out.
This device works on electricity (3 phase), it has six nichrome coils as
heating elements and consumes a total of 6kW (1kW each coil). The coils
are turned on and off by three solid state relays, one for each phase,
the relays are controlled by a digital thermostat with a temperature
sensor just a bit below the lid, so that the vapor temperature can be
monitored. You need to heat the plastic slowly to about 350 degrees and
just wait till it does the magic. Our device has a capacity of 50 liters
and can hold about 30 kg of shredded plastic. The process takes about 4
hours, but it can be shortened considerably by tweaking the design a
bit. As I said, this makes a liquid fuel that can be used as multifuel,
that means it can be used on diesel engines and also on gasoline
engines, but we still need to test it will work on gasoline. It works
for diesel engines just fine, that has already been tested. There is a
difference in what plastic you use, if you use polyethylene (plastic
cans, plastic foil, and all kind of flexible non break plastics) you
will get out liquid fuel that will solidify as it cools into paraffin,
it is still good for diesel engines as long as you use a heated fuel
tank, because it needs to be heated just about at 30 degrees celsius to
be liquid and transparent. If you don't want that, you can put
the
paraffin through the device for one more time and you will chop those
hydrocarbons even smaller and half of the paraffin will turn to liquid
fuel and other half will remain a paraffin, but much denser and will
melt at higher temperatures, this is the stuff you can make candles out
of and it does not smell at all when burned, maybe a bit like candles.
But if you use polypropylene (computer monitor cases, printer cases,
other plastics that break easily), you get out only liquid fuel, no
paraffin at all. All you need is just filter the fuel out of solids and
you good to go and put it in your gas tank. We have made the analysis
and it is almost the perfect diesel fraction. It has no acids or
alkalines in it, like fuel from tires does. The unit in the pictures can
convert about 60 kg of plastic into 60 liters of fuel in one day. Other
methods of heating the reactor can be employed, electricity is just
easier to work with and control. Some Japanese companies manufacture
such devices, but their prices for this size unit is more than 100 000$,
our home made device cost us 900$ max. We use aluminum oxide bricks to
insulate the heat, they are light as foam and can be easily cut in any
shape, but any kind of insulator can be used. The bricks make the
highest costs for this device. It can also be made using liquid fuel
burners to heat the reactor, this will enable to make the device self
sustainable by using about 10-15% of the produced fuel along with the
produced gas. A small farm can use a device this size and make fuel for
itself by converting plastic waste to fuel, farms have very much plastic
waste and it is a big problem, at least in my country. Our next goal is
to make the same thing possible using biomass, every farm could then
use old leafs, wet grass, saw dust and all kind of biomass and gasify it
into tar like substance that can then be put through the pyrolysis
device and turned into biodiesel.
These are samples from polyethylene, in the first run out comes mostly
paraffin like liquid that solidifies at temperatures below 20 degrees
celsius, the other clear sample is from the same paraffin that is gone
through the process one more time.
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