A fundamental study of char oxidation kinetics using model materials

Thesis/Dissertation · Fri Jan 01 00:00:00 EST 1988

OSTI ID:7273458

Levendis, Y A

A fundamental study concerning the reactivity of carbon to oxygen, under conditions pertinent to the combustion of pulverized fuel particles, was conducted. Model, man-made materials have been synthesized and produced to aid in understanding the events that occur during pyrolysis and oxidation of chars. The benefit of employing synthetic materials, along with natural fuels, was that they allowed control of the purity and composition of the chars, as well as enabled production of particles of specific physical properties relevant to modeling combustion processes. Monodisperse, spherical, glassy carbon particles, of various sizes, were manufactured from spraying and thermally treating a carbon-yielding, highly crosslinked polymer. Various pore-forming agents were introduced and copolymerized, aiming to alter the pore structure, density and pore size distribution of the materials. Characterization of the chars, at various stages of pyrolysis and partial oxidation, employed widely varying techniques such as mercury intrusion, gas sorption, helium pycnometry, wide and small-angle scattering and nuclear magnetic resonance. Upon characterization, the influence of the physical factors on the combustion behavior was accounted for and the intrinsic reaction rates of the chars were correlated with their chemical nature. The mechanisms of pore coarsening, opening of pore restrictions and development of a large accessible pore surface area in the interior of the particles, in conjunction to the kinetics of structural ordering and graphitization, have been shown to influence critically the reactivity of chars. Furthermore, experiments with calcium treated chars revealed that the catalytic effect of mineral matter on enhancing the combustion rate is very important.

• Research Organization: California Inst. of Tech., Pasadena, CA (USA)
• OSTI ID: 7273458
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CARBON
COMBUSTION KINETICS
CHARS
OXIDATION
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
DENSITY
HELIUM
MEASURING METHODS
MERCURY
MICROSTRUCTURE
MINERALS
MORPHOLOGICAL CHANGES
NUCLEAR MAGNETIC RESONANCE
OXYGEN
PARTICLE SIZE
PHYSICAL PROPERTIES
POLYMERS
POROSIMETERS
POROSITY
PULVERIZED FUELS
PYCNOMETERS
PYROLYSIS
SCATTERING
SORPTION
SURFACE AREA
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
DECOMPOSITION
DENSIMETERS
ELEMENTS
FLUIDS
GASES
KINETICS
MAGNETIC RESONANCE
MEASURING INSTRUMENTS
METALS
NONMETALS
PYROLYSIS PRODUCTS
RARE GASES
REACTION KINETICS
RESONANCE
SIZE
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES
014000* - Coal
Lignite
& Peat- Combustion