Effects of pressure on rapid pyrolysis and resultant char structure of a caking coal

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:6131087

Lee, C W

An Illinois No. 6 coal was pyrolyzed in both high-pressure and atmospheric-pressure entrained-flow reactors ({approximately}10{sup 4} K/s) at 1189 K, and 0, 100, 309, 530 psig N{sub 2}, with residence times up to 1.7 s. The pyrolysis products were characterized extensively to examine the effects of pressure on physical and chemical structural changes of the coal during pyrolysis. Chars generated at 309 psig are more aromatic than those produced at 100 psig, as indicated by the diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy results and by their higher C/H ratios. Except at 1.7 s, tars generated at higher pressures are more aromatic as indicated by the Fourier-transform infrared (FTIR) spectroscopy measurements and by their higher C/H ratios. The change in composition of the gaseous pyrolysis products, measured by GC, suggests that more secondary reactions of the volatiles were occurring at 309 psig than at 100 psig, except at 1.7 s when most volatiles have left the particles. Scanning electron microscopy shows that chars generated at different pressures have significantly different surface morphologies. This coal swelled most strongly when pyrolyzed at 100 psig than at other pressures. The observed swelling behavior was caused by the completing combined effects of an improvement in fluidity and resistance to swelling by the applied pressure. This hypothesis is supported by a high-pressure microdilatometry study. The apparent first-order rate constants for devolatilization and for swelling of this coal were calculated. The changes in internal structure of this thermoplastic coal during pyrolysis, determined by CO{sub 2} and N{sub 2} surface areas, and by He density, resulted primarily from the realignment of the carbon layers. Chars generated at 100 psig are the most reactive compared to those generated at other pressures, as shown by thermogravimetric analysis results.

• Research Organization: Pennsylvania State Univ., Middletown, PA (USA)
• OSTI ID: 6131087
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
BITUMINOUS COAL
PYROLYSIS
CHARS
MICROSTRUCTURE
ACTIVATION ENERGY
AROMATICS
ATMOSPHERIC PRESSURE
CARBON DIOXIDE
CHEMICAL PROPERTIES
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
COAL GAS
COAL TAR
DENSITY
DEVOLATILIZATION
FOURIER TRANSFORMATION
GAS CHROMATOGRAPHY
HELIUM
INFRARED SPECTRA
LIGNITE
MASS TRANSFER
MORPHOLOGICAL CHANGES
NITROGEN
PARTICLE SIZE
PHYSICAL PROPERTIES
PRESSURE DEPENDENCE
SCANNING ELECTRON MICROSCOPY
SHAPE
SPECTROSCOPY
SUBBITUMINOUS COAL
SURFACE AREA
SURFACE PROPERTIES
SWELLING
TEMPERATURE DEPENDENCE
THERMAL GRAVIMETRIC ANALYSIS
TIME DEPENDENCE
VOLATILE MATTER
BLACK COAL
BROWN COAL
CARBON COMPOUNDS
CARBON OXIDES
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CHROMATOGRAPHY
COAL
CRYSTAL STRUCTURE
DECOMPOSITION
ELECTRON MICROSCOPY
ELEMENTS
ENERGY
ENERGY SOURCES
FLUIDS
FOSSIL FUELS
FUELS
GASES
GRAVIMETRIC ANALYSIS
INTEGRAL TRANSFORMATIONS
KINETICS
MATERIALS
MATTER
MICROSCOPY
NONMETALS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PYROLYSIS PRODUCTS
QUANTITATIVE CHEMICAL ANALYSIS
RARE GASES
REACTION KINETICS
SEPARATION PROCESSES
SIZE
SPECTRA
TAR
THERMAL ANALYSIS
THERMOCHEMICAL PROCESSES
TRANSFORMATIONS
YIELDS
010409* - Coal
Lignite
& Peat- Pyrolysis & Carbonization- (1987-)
010600 - Coal
Lignite
& Peat- Properties & Composition