Date on Master's Thesis/Doctoral Dissertation

5-2014

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Industrial Engineering

Degree Program

Industrial Engineering, PhD

Committee Chair

Biles, William E.

Author's Keywords

NOx prediction; Effective volatiles; Low-NOx systems; NOx emissions; Combustion optimization; Pulverized coal combustion

Subject

Nitrogen dioxide; Coal-fired power plants--Environmental aspects

Abstract

The purpose of this research work was to develop a transferable mathematically simple model which gives the possibility to make fast and easy predictions regarding the NOx emission behavior of a broad–spectrum of coals within a certain combustion environment. In this context, this thesis is a further step of a common ongoing investigation focused on predicting NOx emissions from self–sustaining, pulverized coal combustion in dry bottom firing systems. A comprehensive literature research focused on already published NOx prediction approaches from scientific publications based on fundamental quantitative relationships or empirical algorithms and statistical relationships was also carried out in this context. This research concentrated on three specific areas which were found to constitute a major gap in the knowledge of NOx formation in industrial full–scale applications: the fuel properties; the dependence of furnace geometry factors; and the specific operating conditions. The developed model shows a strong statistical significance with a coefficient of determination of 0.9876 and a standard error of 28 mg / m³ STPdry at 6 % O2 based on 142 observations coming from 28 utility boilers. Direct comparisons between model history and observations reported by other researchers have also shown very good conformities. For that background, this thesis form a good basis for identifying individual factors which contributes to system related NOx emissions in order to investigate how variations in the process parameters affect the emission level. Perhaps, as contribution to the understanding of NOx formation during coal combustion what is still an imperfectly understood phenomenon, or as basis for possible process optimization which might find application on pulverized coal–fired boilers to make the world a little bit more green.

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