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Pyrolysis oil is a primary product of fast pyrolysis, in the process up to 75 wt% pyrolysis oil is produced. It is typically a liquid, almost black through dark red brown. The density of the liquid is about 1,200 kg/m3, which is higher than of fuel oil. The viscosity of the oil depends on the water content and the original feedstock.
The pyrolysis oils contain fully dissolved water, typically 15-30 wt%. The presence of water causes a decrease in viscosity of the oil, which facilitates transport, pumping, and atomisation. It improves the stability, it lowers the combustion temperature and, as a consequence, it lowers the (thermal) NOx emission in combustion-processes.
At high water contents (> 25 wt%) pyrolysis oil is sensitive to phase separation. It can be prevented by continuous stirring of the oil during storage or by water evaporation. There is no phase separation for woody material.
Pyrolysis Oil Properties (Wood Derived)
| composition | C2H5O2 |
| density | 1,150–1,250 kg/m3 |
| higher heating value | 17–20 GJ/m3 |
| water content | 15–30 wt% |
| pH | ~ 3 |
| viscosity | 25–1000 cP |
| ash | < 0,1 % |
Applications of Pyrolysis Oil
