Investigation of the torrefaction process during pyrolysis conditions, before and after the process

Torrefaction is a promising pretreatment technology of biomass that has gained attention nowadays. Torrefaction has the potential of attaining a major impact on the commodification of biomass. Its considered added value is the production of a more coal-alike solid biofuel with higher energy density and better physical and combustion properties and which consumes substantially less energy when pelletized than fresh biomass. Additionally, the solid fuel has a significant lower moisture content than fresh biomass, it is hydrophobic and more homogeneous. However, torrefaction adds value in the logistics chain as well; torrefied and pelletized biomass is considered safer for transportation than conventional pellets, whereas cost savings are also expected due to densification of energy. Therefore, in The Netherlands there are already a couple of torrefaction plants operating on the near-commercial market level.

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TU Delft is collaborating in two projects; a European project called “Brisk”, in which other universities and research centers are involved, and a national TKI project called “Invent”, in which ECNTwente University and Dutch torrefaction industries are involved. The “Brisk” project is investigating the improvement of gasification practices and biomass characterization. Whereas, the “Invent” project is focused on investigation and improvement of torrefaction technologies. TU Delft will receive torrefied and raw biomass which will be used for characterization tests using the university’s reactors under slow pyrolysis, fast pyrolysis and combustion conditions in the university’s reactors. The tests will focus on gas species (such as CO, CO2H2OHNCONH3, and CH4) and tars produced during the conversion of biomass.

In this MSc. graduation project the aim is to investigate the effect of torrefaction of woody biomass under pyrolysis conditions in a Heated Grid reactor and a TGA. Both connected to an FTIR regarding gaseous species analysis. Main research questions are:

  • What is the effect of heating rate on the mass loss, gas species and tars composition during flash and slow pyrolysis prior and post torrefaction conditions of woody biomass?
  • What is the effect of end temperature on the mass loss, gas species and tars composition during flash and slow pyrolysis prior and post torrefaction conditions of woody biomass?
  • What is the effect of the residence time on the mass loss, gas species and tars composition during flash and slow pyrolysis prior and post torrefaction conditions of woody biomass?

The MSc. Graduation topic will include modelling of the pyrolysis using a Distribution Activation Energy Model and the Reaction Rate Constant method. Furthermore, the porosity of the produced solid residues will be analysed by an external partner and/or the solid residue will be characterised under combustion conditions in the department.

Laboratory work will be needed to answer the above research questions and Kinetics05, a software package available within the group,will be used for the modelling part. The final deliverable will be a report that you have to present your work in the group.