Biosludge incineration in FBCs: Behavior of ash particles

Conference · Sun Jan 01 04:00:00 EST 1995 · Combustion and Flame; (United States)

OSTI ID:6548846

Rink, K K; Lighty, J S ^[1]; Kozinski, J A ^[2]

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1. Univ. of Utah, Salt Lake City, UT (United States)
2. McGill Univ., Montreal, Quebec (Canada). Dept. of Mining and Metallurgical Engineering

The evolution of ash morphology and metals behavior during incineration of a biosludge and silica sand in a 300-kW fluidized bed facility have been studied. The reactor was operated in the bubbling mode. Analyses of ash particles were performed using a computer-controlled electron probe microanalyzer equipped with four wavelength-dispersive spectrometers. The paper presents data on ash particle structure formation, size/numbers density distribution and migration/distribution of metals inside a supermicron fly ash particle. A mechanistic model of the fly ash evolution process is proposed. The major trends in the suggested mechanism are (1) the massive formation of porous particles in the splash zone, (2) their extensive fragmentation/disintegration along the incineration pathway resulting in the particle size reduction and number density increase, (3) the presence of a phase transition in locally high-temperature regions (1,650 K), and (4) the formation of smooth-surfaced compact-structured glassy fly ash submicron and supermicron spheres. A physical model of a compact/glassy supermicron fly ash particle is also developed. Light metal elements (Si, Al, Ca, K, Na) create a multilayer external shell encapsulating heavy metals (Cd, Cu, Ni, Pb) distributed in discrete pockets toward the core of the particle. The shell does not constitute any definite boundary between these two characteristic regions since no dependence is found between particle size and shell thickness. These data illustrate that heavy trace metals are partitioned inside a biosludge-originated supermicron fly ash particle rather than on the surface, an assumption previously accepted on the basis of fly ash data obtained during coal combustion.

• OSTI ID: 6548846
• Report Number(s): CONF-940711--
• Conference Information: Journal Name: Combustion and Flame; (United States) Journal Volume: 100:1-2
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
092000* -- Biomass Fuels-- Combustion-- (1990-)
098000 -- Biomass Fuels-- Waste Management-- (1990-)
AEROSOL WASTES
ALKALI METALS
ALKALINE EARTH METALS
ALUMINIUM
ASHES
CADMIUM
CALCIUM
CHEMICAL COMPOSITION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMBUSTION
COMBUSTION KINETICS
COMBUSTION PRODUCTS
COPPER
ELEMENTS
ENCAPSULATION
FLUIDIZED-BED COMBUSTION
FLY ASH
KINETICS
LEAD
MASS TRANSFER
MATHEMATICAL MODELS
METALS
MORPHOLOGY
NICKEL
OXIDATION
POTASSIUM
REACTION KINETICS
RESIDUES
SEMIMETALS
SILICON
SLUDGES
SODIUM
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
WASTES