Dissertation/Thesis Abstract

Heat Transfer Analysis in a Paddle Reactor for Biomass Fast Pyrolyis
by Ullal, Ankith, M.S., Michigan Technological University, 2017, 56; 10266966
Abstract (Summary)

Heat transfer analysis was performed on a novel auger reactor for biomass fast pyrolysis. As part of this analysis, correlations for specific heat capacity and heat transfer coefficients for biomass (sawdust) and sand (used as heat transfer medium) were developed. For sand, the heat transfer coefficient followed a power law distribution with reactor fill level and temperature. For raw biomass, the heat transfer coefficient also showed similar dependence on fill level, but was independent of temperature up to 300°C. These correlations were used in a one dimensional heat transfer model developed to calculate the heating time and heating rate of biomass in the presence of a heat transfer medium (HTM). A heating time of 3 seconds was obtained to raise the temperature of biomass from 298 K to 753 K. Instantaneous heating rates up to 530 K/s were obtained, thus ensuring fast pyrolysis. Further, to study the effect of heating rates on liquid product yields, a previously validated torrefaction-pyrolysis model was used to calculate the liquid yields for torrefied pine forest residues at various heating rates. A threshold heating rate value of 12 K/s was obtained from the model, above which the final product distribution was not affected. The model predicted liquid yield was 54%, in comparison to the experimental yield of 53%, for torrefied pine forest residues without HTM. The steady state experimental heating rate of 36 K/s was observed, which was above the 12 K/s threshold value thus ensuring fast pyrolysis. The results obtained in this paper will be used as a basis for scaling up the reactor configuration to carry out fast pyrolysis without HTM.

Indexing (document details)
Advisor: Bar-Ziv, Ezra, Klinger, Jordan
Commitee: Naber, Jeffrey D., Shonnard, David, Westover, Tyler L.
School: Michigan Technological University
Department: Mechanical Engineering
School Location: United States -- Michigan
Source: MAI 56/04M(E), Masters Abstracts International
Subjects: Alternative Energy, Mechanical engineering
Keywords: Auger, Biomass, Fast pyrolysis, Heating rate, Paddle mixer
Publication Number: 10266966
ISBN: 978-1-369-82227-4
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