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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Evaluation of column flotation circuits for fine coal cleaning /

Looney, John H., January 1994 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 158-163). Also available via the Internet.
12

Design, fabrication, and testing of a pulverized fuel combustion facility

Nelson, Lawrence Patrick. January 1979 (has links)
Call number: LD2668 .T4 1979 N44 / Master of Science
13

Alkali metal partitioning in a pulverized coal combustion environment.

Gallagher, Neal Benjamin. January 1992 (has links)
Fouling, slagging, corrosion, and emission of submicron particulate from pulverized coal combustors have been linked to vapor alkali. Size segregated fly ash samples extracted from a 17 kW down-fired pulverized coal combustor showed strong evidence of alkali vaporization. The fraction of sodium in sizes smaller than 0.65 μm (f(8A)) showed a correlation with acid soluble sodium divided by total silicates in the parent coal. Addition of silicates to coal reduced f(8A) for sodium. Potassium existing primarily in the mineral matter, did not show a similar correlation, but f(8A) for potassium did correlate with f(8A) for sodium. Bench scale experiments indicated potassium does not vaporize in the presence of Na or Cl alone, but requires both, and was only released when sodium was captured. Additional of sodium acetate to coal increased f(8A) for potassium. Equilibrium calculations, experiment, and modelling of sodium capture by silicates during pulverized coal combustion identified several important mechanisms governing alkali behavior. The mode of occurrence of alkali in the parent coal dictates its ability to vaporize, its release kinetics, and its sate as it diffuses to the char surface. Other species such as chlorine, sulfur, moisture, and other metals influence alkali stability in the vapor, its reactivity, and its condensation characteristics. Char oxidation can influence alkali vaporization, and capture by affecting included silicate surface area. Sodium reaction with silicates captures from 70 to over 95% of total sodium for typical coals. Silicate additive appears to be a viable technique for reducing the fraction of alkali in the vapor during combustion.
14

Formation of inorganic submicron particles under simulated pulverized coal combustion conditions

Neville, Matthew January 1982 (has links)
Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 246-250. / by Matthew Neville. / Sc.D.
15

Devolatilization of pulverized coal at high temperatures.

Kobayashi, Hisashi January 1976 (has links)
Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Microfiche copy available in Archives and Engineering. / Vita. / Bibliography: leaves 414-423. / Ph.D.
16

The behavior of ash in pulverized coal under simulated combustion conditions

Padia, Ashok Kumar Sanwarmal January 1976 (has links)
Thesis. 1976. Sc.D.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 321-328. / by Ashok S. Padia. / Sc.D.
17

THE EFFECT OF COAL TYPE, RESIDENCE TIME AND COMBUSTION CONFIGURATION ON THE SUBMICRON AEROSOL COMPOSITION AND SIZE DISTRIBUTION FROM PULVERIZED COAL COMBUSTION (STAGED, FLYASH, SPECIES ENRICHMENT).

LINAK, WILLIAM PATRICK. January 1985 (has links)
Pulverized samples of Utah bituminous, Beulah (North Dakota) low Na lignite, Beulah high Na lignite and Texas (San Miguel) lignite coals were burned at a rate of 2.5 kg/hr in a laboratory furnace under various (overall fuel lean) combustion conditions. Particle size distributions (PSD) and size segregated particle filter samples were taken at various positions within the convection section. Temperature and gas concentrations were measured throughout. The evolution of the submicron PSD within the convection section for the four coals was similar, although the location of the initial particle mode at the convection section inlet varied with coal type. While staged (.8/1.2) combustion of the Utah bituminous coal had a variable effect on the volume of submicron aerosol produced, staged combustion of two of the three lignites (Beulah low Na and Texas) caused a definite increase in the submicron aerosol volume. Vapor enhancement due to a localized reducing atmosphere, which would effect coals of higher ash volatility or higher inherent ash content, is thought to explain this behavior. Depressed combustion temperatures associated with the high moisture content of the Beulah high Na lignite are thought to offset the effects of staging. Increased combustion temperatures (through oxygen enrichment) caused staged volume increases for the Beulah high Na lignite. Combustion temperatures are a controlling factor even at more extreme staging conditions. Chemical analysis of the size segregated particle samples show the trace elements, As, Pb, Zn and the major elements, Na and K to be enriched in the submicron aerosol. Auger depth profiles show these small particles to be comprised of a core enriched in Fe, Si, Ca and Mg and surface layers enriched in Na and K. These results point to a mechanism of homogeneous nucleation of low vapor pressure species followed by successive layering of progressively more volatile species. Volatile species are enriched in the submicron aerosol due to the large surface areas provided. Modeling efforts show that while coagulation may be the dominant mechanism to describe the aerosol evolving within the convection section, it cannot be used solely to predict the PSD. Another mechanism, presumably surface area dependent growth (condensation) must be included.
18

Gasification of coal char in oxygen and carbon dioxide at high temperatures.

Mandel, Gerald January 1977 (has links)
Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography : leaves 146-149. / M.S.
19

Fate of fuel nitrogen during pulverized coal combustion.

Song, Yih-Hong January 1978 (has links)
Thesis. 1978. Sc.D.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: leaves 307-314. / Sc.D.
20

Ash vaporization under simulated pulverized coal combustion conditions

Quann, Richard J January 1982 (has links)
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Bibliography: leaves 429-434. / by Richard John Quann. / Sc.D.

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