(390e) A Novel Fluidized Bed Model for Fast Pyrolysis Applications

Biomass fast pyrolysis has been
identified as a viable method to produce bio-oil, a renewable alternative to
petroleum-derived fuels and feedstocks. Fluidized bed reactors are ideal for pyrolysis
due to their precise temperature control and high solid-solid heat transfer
rates, and recent developments in autothermal operation have overcome the
limitations inherent in supplying externally generated heat to the reactor
itself. While many fluidized bed reactor models have been developed that
accurately depict fluid-phase or heterogeneous reactions, they do not capture
the intricacies of solid-phase reactions where heat transfer is the limiting
factor.

This work presents a
novel approach to the modeling of a fluidized bed reactor, focusing on the
experience of the particles being pyrolyzed, which make up a minority of the
bed mass. Due to the decoupling of solid- and vapor-phase reactions, this
subset of particles can be modeled as a series of open control volumes surrounded
by a uniform temperature heat source. The phenomena of heat transfer, chemical
reaction, density loss, and elutriation are all captured in a format applicable
within commercially available process simulators. The addition of partial oxidation
reactions allows the reactor model to operate autothermally,
with results supporting experimental findings on the performance enhancement
derived from autothermal operation.