Fundamental studies of the mechanisms of slag deposit formation

Technical Report · Wed Oct 01 04:00:00 EDT 1986

OSTI ID:5125356

Austin, L G; Benson, S; Rabinovich, A; Tangsathitkulchai, M; Schobert, H H

New feed systems were developed for improved feeding of pulverized coals to the drop tube furnace. Strengths were measured for deposits produced in the drop tube furnace from combustion of thirteen low-rank coals, as well as from some ion-exchanged coals and specific gravity fractions. For lignite deposits a maximum deposit strength thought due to the effects of sodium occurs for lignite having 8.8% equivalent sodium oxide in the ash. SEM-EDS analyses were used to examine the microstructure of deposits and to determine the morphological and compositional changes that occur from the base of the deposit to the top. The formation of crystalline species appears to be an indication of the degree of interaction between ash-forming species within the ash deposits. Some of the strongest deposits contained abundant crystalline phases such as pyroxene and melilite. In these deposits sodium concentrates in the glass phase. Sodium would be expected to reduce the viscosity of the liquid phase, resulting in increased deposit strength through viscous sintering. A logarithmic increase of strength with increasing substrate temperature was the typical behavior of slag drops adhering to oxidized steel. An alonized T-11 steel surface was superior, for resisting formation of a strongly adhering initial layer of slag, to 304 stainless steel, which was, in turn, superior to T-11 steel. The high adhesion strength of the molten ash drop to the oxide layer on oxidized steel is due to chemical compatibility between the oxide layer and ash and not a result of mechanical anchoring to the microporosity of the surface. Software was developed to use the computer-controlled SEM-fluorescence particle-particle analyzer as an automated particle analyzer. 17 refs., 22 figs., 11 tabs.

• Research Organization: Pennsylvania State Univ., University Park (USA). Coll. of Earth and Mineral Sciences
• DOE Contract Number: FG22-84PC70770
• OSTI ID: 5125356
• Report Number(s): DOE/PC/70770-T7; ON: DE87001925
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
014000* -- Coal
Lignite
& Peat-- Combustion
AEROSOL WASTES
ALLOYS
ASHES
BROWN COAL
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COAL
COMBUSTION
COMBUSTORS
CRYSTAL STRUCTURE
DATA
DEPOSITION
DEPOSITS
ELECTRON MICROSCOPY
ENERGY SOURCES
EXPERIMENTAL DATA
FABRICATION
FLY ASH
FOSSIL FUELS
FUEL FEEDING SYSTEMS
FUEL SYSTEMS
FUELS
FURNACES
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
LIGNITE
MATERIALS
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
NUMERICAL DATA
OXIDATION
PULVERIZED FUELS
RESEARCH PROGRAMS
RESIDUES
SCANNING ELECTRON MICROSCOPY
SINTERING
SLAGS
STEELS
SUBBITUMINOUS COAL
TEST FACILITIES
THERMOCHEMICAL PROCESSES
VERY HIGH TEMPERATURE
VISCOSITY
WASTES