Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemical and Biochemical Engineering

Supervisor

Dr. Cedric L. Briens

Abstract

This PhD research addresses the challenge of feeding biomass residues into fluidized bed reactors for pyrolysis, through the development of a novel intermittent solid slug feeder, both for laboratory-scale and large-scale reactors. The new feeder can successfully handle biomass residues that are either too cohesive or thermally sensitive for traditional feeders.

To optimize the novel feeder performance, a model for the pulsating solids flow was developed from experimental data collected with ideal slugs, as well as real biomass flow. The model was validated using both a laboratory-scale (< 10 kg/hr) and large-scale feeder (> 250 kg/hr). Several important variables were identified. They include the material flow properties, the pulse gas pressure and volume, and the feeding tube length and material. The goals of this study were to (a) characterize the fundamental dynamic behavior of the biomass slugs in the feeder, (b) maximize the solid-to-gas feeding ratio, and thus minimize energy consumption and cost, (c) minimize the accumulation of “straggler” biomass material in the feeding tube between pulses, and thus prevent biomass heating in the feeding tube, which can induce plugging, and (d) develop and validate a predictive model for the slug velocity at any location in the feeding tube, which can be applied to feeder design for any biomass feedstock.

An advantage of the new large-scale feeder technology is that it can handle larger biomass particles than traditional feeder technologies. An issue with large particles is that they require relatively long drying, which must be optimized. A model was therefore developed for drying, which takes shrinkage, and internal and external mass transfer limitations into account.

The thesis is supplemented with additional work based on the application of the novel feeder for pyrolysis studies with various biomass residues. The feeder technology made it possible to perform the first ever pyrolysis studies, in industrially-relevant equipment, on pure meat and bone meal residue, and on unmodified and undiluted Kraft lignin. Appendices include a business case-study of the implementation of the technologies developed in this thesis on large-scale pyrolysis and an additional pyrolysis study on tucumã seeds, which utilized the novel feeder.


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