Chemical and Biological Engineering ETDs

Publication Date

2-24-1977

Abstract

This study focuses on one aspect of coal gasification; that is, devolatilization of large single coal particles. Devolatilization is an important and key economic step in the overall gasification process. From a commercial standpoint for New Mexico, there are two processes in the field of coal gasification of importance: the Lurgi synthetic natural gas process and in-situ gasification. Since both the Lurgi and in-situ processes treat rather large particles of coal, the findings in this study might be used by industry to improve the design and operation of these processes. The work presented is a study and comparison of the reactivity and devolatilization kinetics for large single particles of New Mexican and South African subbituminous coal. This study was unique in that rather large (one-inch diameter) single particles of coal were investigated under controlled conditions. A custom­designed, single particle reactor and computerized on-line control and monitoring system were developed and used to investigate the devolatilization behavior of New Mexican and South African subbituminous coal. A real-time mass spectrometer was implemented and developed to continuously monitor compositions of the individual volatile species in the product gas. Experimental data were collected and mathematical models were developed and tested. Particle temperature and weight loss histories were measured and two types of heat transfer and kinetic models were tested and compared to the experimental data. Using the combined heat transfer and kinetic models, activation energies and frequency factors were determined for New Mexican and South African subbituminous coal. The experimentally determined devolatilization rate of the New Mexican coal was significantly greater than the South African coal. Therefore it was assumed that the New Mexican coal was more reactive. This assumption was further substantiated by examining specially prepared cross sectioned samples of the devolatilized coal. The New Mexico coal was found to exhibit more internal fracturing upon heating than the South African coal, thus exposing more internal surface area and resulting in a greater reactivity.

Sponsors

The New Mexico Board of Educational Finance

Document Type

Thesis

Language

English

Degree Name

Chemical Engineering

Level of Degree

Masters

Department Name

Chemical and Biological Engineering

First Committee Member (Chair)

H. Eric Nuttall Jr.

Second Committee Member

Chen-Yen Cheng

Third Committee Member

Kenneth Edward Cox

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