Co-axial turbulent diffusion flames with directed oxygen injection

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Publication Type dissertation
School or College College of Engineering
Department Chemical Engineering
Author Rezaei, Dadmehr
Title Co-axial turbulent diffusion flames with directed oxygen injection
Date 2013-05
Description Oxy-coal combustion technology has been suggested as the most promising strategy for retrofitting conventional coal power plants to generate electric power while capturing carbon dioxide. The current research addresses three issues in oxy-coal combustion, namely: 1- What is the effect of coal composition on the stability of co-axial turbulent diffusion oxy-flames? 2- What are the stability criteria for turbulent diffusion oxy-coal flames in an advanced triple concentric co-axial burner allowing directed streams of pure oxygen to be introduced into the combustion mix? 3- How does minimization of CO2 diluent affect radiant heat flux in the combustion chamber? It is hoped that data produced in this investigation can be used for validation of advanced simulations of the appropriate configurations considered. In order to address Issue #1 listed above, the consequences of differences in coal composition on flame stability for two types of coal in oxy-combustion were explored: Utah Skyline Bituminous and Illinois #6 Bituminous. Differences in flame stand-off distances at equivalent experimental input conditions were interpreted through differences in the structure of the two coals as well as differences in their pyrolysis behavior, as determined by fundamental solid state 13C NMR and Thermal Gravimetric Analysis (TGA), respectively. In addressing Issue #2, the consequences of segregating all the input oxygen into one stream composed of 100% oxygen were determined using the co-axial burners with different oxygen stream configurations. Flame stability, heat flux, and NOx formation measurements were taken to evaluate the differences. Flame stability was quantified through flame probability density functions (PDF) of the stand-off distance (determined using photo-imaging techniques). The PDFs obtained from these simplified prototype configurations led to physical insight into coal flame attachment mechanisms and the significant effects of fine coal particles and their radial transportation by large eddies on flame stability. Finally, in addressing Issue #3, impacts of reducing the amount of injected diluent CO2 (mimicking the minimization of the recycle ratio) on the radiation heat flux were explored. Radiant heat flux, gas temperature, and wall temperature measurements were taken, and a simple radiation model was developed to correlate the average gas temperature and radian heat flux. This study provided a better understanding of the radiation mechanism and the significant effects of soot radiation on the total heat transfer in the next generation of oxy-coal combustion.
Type Text
Publisher University of Utah
Subject Coal composition; Co-axial turbulent diffusion flames, Flame stability; Oxy-coal combustion; Pure oxygen injection; Reduction of recycled flue gas (RFG) ratio
Dissertation Institution University of Utah
Dissertation Name Doctor of Philosophy
Language eng
Rights Management Copyright © Dadmehr Rezaei 2013
Format Medium application/pdf
Format Extent 3,094,903 Bytes
Identifier etd3/id/3466
ARK ark:/87278/s6k96gs8
Setname ir_etd
Date Created 2015-05-12
Date Modified 2018-01-22
ID 197020
Reference URL