Domains of flammability and thermal ignitability for pulverized coals and other dusts: particle size dependences and microscopic residue analyses

Conference · Fri Jan 01 00:00:00 EST 1982 · Symp. (Int.) Combust., (Proc.); (United States)

OSTI ID:5756951

Hertzberg, M; Cashdollar, K L; Ng, D L; Conti, R S

The particle size dependence for the lean limits of flammability in air of Pocahontas coal dust, Pittsburgh coal dust, and polyethylene powder were measured. In all cases, the lean limits measured in an 8-liter chamber became insensitive to particle size below some characteristic diameter. Above those characteristic diameters, the lean limit concentrations increased significantly with increasing particle size until a critical size was reached, above which the dust was nonflammable for any concentration at ambient temperature and pressure. Both the characteristic diameter and the coarse size limit of flammability (critical diameter) increased monotonically with increasing dust volatility and increasing oxygen content of the dispersing gas. The minimum autoignition temperatures (AIT's) display behavior similar to that of the lean limit concentrations, except that heating of the mixture to the elevated temperature required for such thermal ignitability studies markedly increases its flammability range. At those elevated initial temperatures, the characteristic sizes are shifted to larger diameters and no critical sizes were observed for some of the AIT mesurements even at the coarsest sizes studied. Also presented are scanning electron microscope (SEM) data revealed the structural changes from dust explosions. A theory is presented which isolates the important physical processes in their simplest form.

• Research Organization: Pittsburgh Research Center, Pennsylvania
• OSTI ID: 5756951
• Report Number(s): CONF-820801-
• Journal Information: Symp. (Int.) Combust., (Proc.); (United States), Conference: 19. international symposium on combustion, Haifa, Israel, 8 Aug 1982
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
COAL
FLAMMABILITY
DUSTS
EXPLOSIONS
IGNITION
MICROSTRUCTURE
PARTICLE SIZE
SCANNING ELECTRON MICROSCOPY
CARBONACEOUS MATERIALS
COMBUSTION PROPERTIES
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
ENERGY SOURCES
FOSSIL FUELS
FUELS
MATERIALS
MICROSCOPY
SIZE
014000* - Coal
Lignite
& Peat- Combustion
016000 - Coal
Lignite
& Peat- Health & Safety