HOW WE TURN PLASTIC INTO OIL
The Origin of Petroleum
The Processing Quantity
The Oil Quality
HOW WE TURN
PLASTIC INTO OIL
In order to understand the process of pyrolysis (ancient Greek pyr = fire, lysis = dissolution), it is necessary to understand how crude oil is formed. The starting material is remnants of animal and plant plankton that sank to the seafloor millions of years ago. Because there is no oxygen down there, it was not decomposed.
Thus, it remained as sludge on the seabed, which became up to 100m high in certain places. Later, sand and gravel, as well as other sediments, settled over this layer and solidified.
Over millions of years, in this isolated and airtight space, under high pressure and at temperatures of approx. 80 to 150°C, a chemical decomposition of the digested sludge took place, from which crude oil and natural gas developed.
In a pyrolysis reactor, the conditions of the formation of crude oil and natural gas are simulated, but with different physical conditions (temperature, pressure and time).
The temperatures are between 400 and 500°C. In order to prevent combustion, the process takes place under the exclusion of oxygen.
Under these conditions and during a processing time of approx. one to two hours, large hydrocarbon molecules are split into small hydrocarbon molecules.
Under normal conditions, the small hydrocarbon molecules are liquid – they form the crude oil. The liquefaction takes place during condensation, where the high temperatures are reduced back to normal conditions.
In pyrolysis, we work with Naga Earth (visit homepage), who helps us to test the prototypes in terms of handling and security before they are implemented in the communities.
The reactors themselves should allow a daily processing volume of approx. 50 to 100kg. In comparison, conventional systems can process up to 150kg per hour. We just want to process the amount of plastic that the community produces every day. This will also reduce the energy consumption for pyrolysis to the necessary minimum. We have to consider that the pyrolysis process has a negative energy balance.
Even if plastic can be regenerated up to 70 percent (i.e. up to 70kg oil can be produced from 100kg plastic), the process requires more energy than the regenerated crude oil contains. This is a common problem many big plants are facing today.
Here, too, we work with external partners to test sustainable approaches to generate the necessary energy. For heat generation, we plan a mix of waste that is not polluted with pollutants (paper, cardboard, wood, etc.), dried organic material and charcoal.
As simple as the process sounds, it is complicated in practice. The plastic does not consist of crude oil alone, but also contains many other chemical additives that give the plastic the desired properties such as resistance, hardness, etc.
In the pyrolysis process, these molecules also enter the gaseous phase and, after condensation, the liquid phase.
The resulting oil therefore also contains these additives, which can become air pollutants during subsequent combustion. This means that these substances must be eliminated or neutralized before they can be used again.
The aim is to maintain a similar oil quality to crude oil so that it can be integrated into the local market and thus contribute to the self-financing of the Community Programme.