- Pyrolysis is the thermal degradation of a substance in the absence of oxygen.
- This process requires an external heat source to maintain the temperature required.
- Typically, lower temperatures of between 300C to 850C are used for the pyrolysis of materials.
- In general pyrolysis processes tend to prefer consistent feedstocks.
- Feedstock preparation may be required to provide consistency and avoid certain inorganic materials in the process, such as metals, glass and inert materials such as rubble.
- The products produced from pyrolyzing materials are a solid residue and a synthesis gas.
- The solid residue can be converted into carbon.
- The syngas is a mixture of gases (combustible constituents include carbon monoxide, hydrogen, methane, and a broad range of other VOCs).
- A proportion of these can be condensed to produce oils, waxes, and tars.
Applications for the pyrolysis oil
- Raw material for oil refinery & plastic production
- Low speed diesel engines (marine application)
- Industrial furnaces, kilns, driers, boilers
- Fuel for power plants
- Gasification can be considered a process between pyrolysis and incineration in that it involves the partial oxidation of a substance.
- The temperatures employed are typically above 650°C.
- The process is largely exothermic, but some heat may be required to initialise and sustain the gasification process.
- The main product is a syngas, which contains carbon monoxide, hydrogen and methane.
- typically the feedstock would require some mechanical preparation and separation of glass, metals, and inert materials prior to processing the remaining waste. Plastic waste although with some contamination is considered a practical waste for such technology.
- It can also be produced by plasma at high temperatures, using steam and little oxygen to break down the complex carbon molecules and generate the syngas.
- Other gasification processes uses plasma to clean the syngas.
Applications for the syngas
- Syngas can be used to generate electricity over IC engines, turbines, boiler, or for other thermal uses.
- Syngas can be converted to oils to use in the petrochemical or into diesel.
- The syngas can also be converted into hydrogen which currently is in huge demand in particular if CO2 is neutral or highly reduced.