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You searched for subject:(Char oxidation). Showing records 1 – 3 of 3 total matches.

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Brigham Young University

1. Mathias, James A. High-Pressure Oxidation Rates for Large Coal and Char Particles.

Degree: MS, 1996, Brigham Young University

The main objective of this study was to investigate the factors that influence the oxidation rate of large (five to eight millimeters in diameter) coal and char particles. To accomplish this, experiments were performed in which the gas temperature, gas velocity, particle size, partial pressure of oxygen, and total pressure were varied. The experiments were performed with the cantilever balance attachment and the high pressure controlled profile reactor. Approximately 90 combustion experiments were performed with Pittsburgh, Utah Blind Canyon, and Wyodak-Anderson coal. These experiments were performed at atmospheric pressure with air and varied gas temperature, gas velocity, and particle size. Following the experiments performed with coal, approximately 70 experiments were performed with char made from Pittsburgh coal. These experiments varied all the environmental conditions mentioned above as well as partial pressure of oxygen and total pressure. After the experiments were completed, the data were analyzed and the following conclusions were made. An increase in the partial pressure of oxygen dramatically increased the oxidation rate when the total pressure remained constant. The oxidation rate was only slightly affected when the partial pressure of oxygen was raised by increasing the total pressure. The oxidation rate dramatically decreased when the partial pressure of oxygen was held constant and the total pressure was raised. The oxidation rate noticeably increased when the initial mass of the particle was decreased. The gas temperature and gas velocity did not affect the oxidation rate greatly for the experiments performed with coal. The oxidation rate increased for the experiments performed with char at the high gas temperature and high gas velocity conditions.

Subjects/Keywords: high-pressure oxidation; coal particles; char particles; combustion experiments; Mechanical Engineering

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APA (6th Edition):

Mathias, J. A. (1996). High-Pressure Oxidation Rates for Large Coal and Char Particles. (Masters Thesis). Brigham Young University. Retrieved from https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=9539&context=etd

Chicago Manual of Style (16th Edition):

Mathias, James A. “High-Pressure Oxidation Rates for Large Coal and Char Particles.” 1996. Masters Thesis, Brigham Young University. Accessed April 14, 2021. https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=9539&context=etd.

MLA Handbook (7th Edition):

Mathias, James A. “High-Pressure Oxidation Rates for Large Coal and Char Particles.” 1996. Web. 14 Apr 2021.

Vancouver:

Mathias JA. High-Pressure Oxidation Rates for Large Coal and Char Particles. [Internet] [Masters thesis]. Brigham Young University; 1996. [cited 2021 Apr 14]. Available from: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=9539&context=etd.

Council of Science Editors:

Mathias JA. High-Pressure Oxidation Rates for Large Coal and Char Particles. [Masters Thesis]. Brigham Young University; 1996. Available from: https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=9539&context=etd

2. Lo, Chen Chia. Characteristics of smoldering combustion of sawdust.

Degree: MSin Engineering, Mechanical Engineering, 2013, University of Texas – Austin

This report is a study on the smoldering combustion of natural sawdust from untreated woods. The objective was to develop and test an experimental technique to study the fundamental behavior of sawdust smolder. The experimental setup was an annulus cookstove packed with sawdust between the inner and outer radii creating a central hollow core. The sawdust was ignited by a heating coil wrapped around the inner radius. Thermocouples were embedded in the sawdust bed fanning out in the radial direction, and temperature was recorded throughout the smolder process. Consistent with the literature, the experimental results indicate that wood smolder consists of three pathways, 1) sawdust to char, 2) sawdust to volatiles, and 3) char to ash. Pathways 1 and 3 can be clearly characterized by the temperature profile of the smolder; however, pathway 2 often involves flaming of the sawdust and is beyond the scope of this study. Pathway 1, sawdust to char, is an endothermic reaction that results in a clearly defined char front that propagates across the sawdust bed in the radial direction. As smolder proceeds, the char continues to oxidize and breaks down into non-volatile products such as water vapor and carbon dioxide (CO₂) in further exothermic reactions. Pathway 2, char to ash, is an exothermic reaction that can lead to glowing combustion when exposed to sufficient amounts of oxygen and results in spikes in temperature. In contrast to the clearly defined char front, the ashing zone traces cracks in the sawdust where air can penetrate through, and has no discernible front. Section 1 discusses the motivation behind the study of sawdust cookstoves in third world countries, in particular Ghana, to replace wood with sawdust as a cheap alternative for household fuel. Section 2 details the experimental setup of the cookstove rig and the methodology of the experiments conducted. Section 3 reports the results of the experiments and analyzes the temperature profiles in relation to the three types of chemical reactions as noted above. Section 4 concludes with a summary of the results and discusses efforts in measuring emissions from the smolder and future work to be done. Advisors/Committee Members: Ellzey, Janet L. (advisor).

Subjects/Keywords: Sawdust; Smolder; Smoldering combustion; Biomass; Ghana; Cookstove; Char oxidation; Ash

…irregular disintegration of the char body in the oxidation process. On the other hand, the two… …completely dominated by the exothermic char oxidation pathway to form combustion products such as… …char oxidation, the enhanced air ventilation incurs significant heat loss through convection… …oxidation of char to produce combustion products such as water vapor, CO2, N2, ash and more… …3-8: Webcam captures comparing char to ash fronts ...............................18 Figure… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Lo, C. C. (2013). Characteristics of smoldering combustion of sawdust. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/22661

Chicago Manual of Style (16th Edition):

Lo, Chen Chia. “Characteristics of smoldering combustion of sawdust.” 2013. Masters Thesis, University of Texas – Austin. Accessed April 14, 2021. http://hdl.handle.net/2152/22661.

MLA Handbook (7th Edition):

Lo, Chen Chia. “Characteristics of smoldering combustion of sawdust.” 2013. Web. 14 Apr 2021.

Vancouver:

Lo CC. Characteristics of smoldering combustion of sawdust. [Internet] [Masters thesis]. University of Texas – Austin; 2013. [cited 2021 Apr 14]. Available from: http://hdl.handle.net/2152/22661.

Council of Science Editors:

Lo CC. Characteristics of smoldering combustion of sawdust. [Masters Thesis]. University of Texas – Austin; 2013. Available from: http://hdl.handle.net/2152/22661

3. Raymond, Christopher J. Investigation of Spontaneous Combustion Inhibition of Coal Fires Utilizing Differential Scanning Calorimetry and Thermogravimetric Analysis.

Degree: MSCB, Chemistry, 2015, Kennesaw State University

Self-oxidation of coals can result in spontaneous combustion events at any time during mining, transporting, or processing, causing environmental, economical, and safety concerns. The total global primary coal production as of 2012 was 8.7 billion tons. Of that, 1.1 billion tons of coal was mined in the US, which accounts for 41% of the domestic electricity production. Spontaneous coal combustion, although dependent on coal rank, is a naturally occurring phenomenon that often causes damage to industrial and commercial facilities and freight, reduces the caloric value of coal, can release noxious gases and particulate matter, and increases CO2 pollution levels locally and globally. Through the self-oxidation process, as heat accumulates, the internal temperature of the coal continues to rise over time and if left unaltered will lead to spontaneous coal fires. Thus there is a definite need for means to suppress this process. In this study, we investigated methods of spontaneous coal combustion inhibition. During experimentation, coal was ground into a fine dust (500 microns in diameter) and treated with inorganic phosphate and sulfonate salts combined with anionic and non-ionic surfactant blends. Each ingredient was applied to the surface of unreacted coal in combination, systematically varying the concentrations of each component, to reach a cost-effective and efficient formulation. Multiple approaches including thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to analyze these effects. Results showed these novel formulations can reduce spontaneous combustion potential, making coal more thermally stable. Mechanisms by which these formulations inhibit coal spontaneous combustion are proposed. Advisors/Committee Members: Dr. Christopher Dockery, Dr. Mark Mitchell, Dr. Michael Van Dyke.

Subjects/Keywords: spontaneous coal combustion; fire inhibitor; thermal stability analysis; phosphate; sulfonate; surfactant; self oxidation; char; thermogravimetric; differential scanning; calorimeter; TGA; DSC; Chemistry

Oxidation Figure 4. SEM Surface Image of PRB Coal Figure 5. Flammability Test of Untreated and… …on a sub-bituminous coal bed. Through coal processing, the self-oxidation of coal… …phenomenon, we must understand how spontaneous heating occurs. 6 CHAPTER 2. COAL OXIDATION AND… …self-oxidation of coal is a thermodynamically spontaneous reaction, which means that it does… …susceptibility of the coal to undergo oxidation and thermal decomposition at low temperatures (20… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Raymond, C. J. (2015). Investigation of Spontaneous Combustion Inhibition of Coal Fires Utilizing Differential Scanning Calorimetry and Thermogravimetric Analysis. (Thesis). Kennesaw State University. Retrieved from https://digitalcommons.kennesaw.edu/mscs_etd/2

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Raymond, Christopher J. “Investigation of Spontaneous Combustion Inhibition of Coal Fires Utilizing Differential Scanning Calorimetry and Thermogravimetric Analysis.” 2015. Thesis, Kennesaw State University. Accessed April 14, 2021. https://digitalcommons.kennesaw.edu/mscs_etd/2.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Raymond, Christopher J. “Investigation of Spontaneous Combustion Inhibition of Coal Fires Utilizing Differential Scanning Calorimetry and Thermogravimetric Analysis.” 2015. Web. 14 Apr 2021.

Vancouver:

Raymond CJ. Investigation of Spontaneous Combustion Inhibition of Coal Fires Utilizing Differential Scanning Calorimetry and Thermogravimetric Analysis. [Internet] [Thesis]. Kennesaw State University; 2015. [cited 2021 Apr 14]. Available from: https://digitalcommons.kennesaw.edu/mscs_etd/2.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Raymond CJ. Investigation of Spontaneous Combustion Inhibition of Coal Fires Utilizing Differential Scanning Calorimetry and Thermogravimetric Analysis. [Thesis]. Kennesaw State University; 2015. Available from: https://digitalcommons.kennesaw.edu/mscs_etd/2

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.