Production and Characterization of Coal-Biomass Briquettes

Abstract

Roll press briquetting of coal-biomass mixtures presents a significant opportunity to address feedstock challenges associated with co-utilization of coal and biomass in existing coal-fired facilities. However, several technical and economic barriers require further investigation prior to industrial utilization of coal-biomass briquettes. The scientific contributions presented in this dissertation are intended to address the most critical technical challenges pertaining to coal-biomass briquette feedstocks. As with any product of an agglomeration process, the primary technical challenge regarding coal-biomass briquettes is achieving and maintaining a high level of quality from production to utilization. Several laboratory-scale research investigations were conducted to address this challenge. The first study was conducted to identify, develop and refine methods to characterize the most important physical properties indicative of coal-biomass briquette quality. The outcome of this work is a set of recommendations for novel and refined methods to characterize important coal-biomass briquette properties. The second study was conducted to develop a novel method to identify the optimum water content of coal-biomass blends prior to briquette production. As a result of this study, the Briquette Proctor Test was developed to minimize the time and materials required to identify the optimum water content that corresponds to maximum quality of coal-biomass briquettes. The third study was conducted to evaluate the influence of feedstock variables, additive variables, and roll press operating parameters in the production of coal-biomass briquettes from various coal and biomass types. From this study, the influence of each parameter on the quality of briquettes was determined and optimum conditions were identified for a variety of coal-biomass mixtures. The fourth and final study was conducted to develop and evaluate methods to improve the water resistance of coal-biomass briquettes using wood-derived chemicals. Using these chemicals, the novel coating method developed in this study significantly improved the water resistance and weathered durability of coal-biomass briquettes.