Pyrolysis oil evaporation including liquid phase polymerization reaction

Pyrolysis oil evaporation including liquid phase polymerization reaction

Sital, Chantal (TU Delft Mechanical, Maritime and Materials Engineering)

Roekaerts, Dirk (mentor)
de Jong, Wiebren (graduation committee)
Infante Ferreira, Carlos (graduation committee)

Delft University of Technology

2018-11-01

Pyrolysis oil (BPO), derived from biomass via the fast pyrolysis process is a potential substitute for petroleum fuels. Due to its distinct physical and chemical properties (highly oxygenated, chemically reactive), the possible range of stable and clean operation in combustion devices is smaller than for petroleum fuel and to enable use of pyrolysis oil in a wider range of applications more insight in pyrolysis heating an evaporation behaviour is required. A surrogate oil of 6 discrete components (water, acetic acid, hydroxypropanone, phenol, eugenol and levoglucosan) is formulated to represent certain aspects of the real pyrolysis oil for computational means. A liquid phase thermal polymerization reaction is formulated to investigate the eect this reaction on the evaporation process. In this reaction, levoglucosan undergoes a dimerization reaction to form a solid dimer. For the evaporation, the Rapid Mixing Model (RMM) is applied, which (mainly) assumes innitely fast liquid phase thermal conductivity. The RMM is adapted for the multicomponent case and the evaporation process is numerically solved for a single stagnant droplet with initial diameter of 100 m in still air (T1 = 800K, p1 = 1 atm). Results of both the model without and with polymerization reaction show continuous variations of the mass fractions of individual components and (pure species) thermophysical properties. At the early stage of evaporation most of the vapor contains the lighter components, i.e. water, acetic and hydroxypropanone. At the end of the vaporization process, only levoglucosan is left in the drop. Furthermore, the results show that the multicomponent fuel does not match the d2 law; there is a high evaporation rate during early evaporation process, while a slower evaporation rate is observed in the further process. Validation with literature experimental data of a real BPO shows a disagreement in trend between model and experiment, with experiment showing a more rapid decrease of diameter over time. However, a better agreement with an experiment on a two-component fuel is observed. To improve the qualitative and quantitative predictions of evaporation rate, a model including gradients inside the droplet and representing the eects of internal bubbling would be required. The model including the polymerization reaction predicts that the eect of the proposed reaction of levoglucosan is very small, with only 0.4% lower evaporated mass of levoglucosan.

Biomass pyrolysis oil
Surrogate oil
Rapid mixing evaporation model
Thermal polymerization

http://resolver.tudelft.nl/uuid:0f355e41-1dab-4369-b83e-f4f5e7379a6c

Student theses

master thesis

© 2018 Chantal Sital