DOI

10.17077/etd.8n2a-6nhz

Document Type

Dissertation

Date of Degree

Spring 2019

Access Restrictions

Access restricted until 07/29/2020

Degree Name

PhD (Doctor of Philosophy)

Degree In

Mechanical Engineering

First Advisor

Ratner, Albert

First Committee Member

Udaykumar, H.S.

Second Committee Member

Buchholz, James

Third Committee Member

LeFevre, Gregory H.

Fourth Committee Member

Harwood, Casey

Abstract

Gasification is a process that converts organic carbonaceous materials at high temperatures into a fuel gas primarily containing carbon monoxide (CO), hydrogen (H2), methane (CH4), and carbon dioxide (CO2). Gasification has three main byproducts: syngas, heat, and char. This thesis explores the characteristics of biochar created from the downdraft gasification of corn, soybeans, wood pellets, and refuse derived fuel (RDF). The goal of this thesis is to better understand how gasification influences the biochar and syngas byproducts so as to help model simulations and to understand how better-quality syngas and biochar can be produced through this process. Ultimate and proximate analysis, BET surface area analyses, and SEM X-ray analysis were obtained on the biochar. It was found that wood biochar was the most porous char with a high carbon content, while RDF char had the lowest porosity with the lowest carbon content. Three of the four biochars, excluding RDF, had a significant phosphorus content, while the RDF biochar had a high concentration of aluminum. X-ray analysis of the biochar shows mineral localization on the char surface and how that relates to local porosity. The syngas content from different biomasses was also tested. It was found that, in agreement with previous studies, biomass with high amounts of cellulose led to high amounts of CO, while fuel with high lignin content led to high amounts of hydrogen. To better understand equilibrium chemistry gasification, examination of syngas, char, and tar content from the gasification of miscanthus briquettes in a double stage downdraft gasifier was carried out. The results show that the optimum equivalence ratio at which miscanthus briquettes can be gasified is 0.35, with peak CO and H2 content at 20.29% CO and 18.68% H2, respectively; with a resulting syngas heating value of 5.5 MJ/Nm3. The process yields significantly higher energy content syngas and higher porosity biochar, indicating that the more uniform process created in the equilibrium environment yields significant product improvements.

Pages

xiii, 141 pages

Bibliography

Includes bibliographical references (pages 136-141).

Copyright

Copyright © 2019 Tejasvi Sharma

Available for download on Wednesday, July 29, 2020

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