Analysis and modeling of in-bed tube erosion in a gaseous fluidized bed
Erosion by impingement of bed materials (ash, coal, and sorbents) on in-bed components has caused serious problems to many fluidized bed combustion (FBC) systems in the past few decades. The author conducted an experimental study, supplemented with theoretical analysis, in which erosion-prone tubes were placed inside a fluidized bed of uniformly sized glass beads to accelerate the mass removal process of the in-bed tubes. Effects of tube-to-distributor clearance, superficial velocity, tube orientation and location, tube circumferential angle, tube bundle height and configuration, and particle size on tube erosion were investigated, identified and discussed. It was found that tube erosion occurred only at a threshold fluidizing velocity (26 cm/s), close to the minimum fluidizing velocity (19 cm/s), and increased almost linearly with increasing superficial velocity. The average specific erosion rate of a tube bundle was about one order of magnitude lower than that of a single tube under the same test conditions. The erosion of a staggered bundle was found larger by 45% than that of an in-line bundle having identical tube pitches. Mathematical modeling of gas-particle flow in the fluidized bed with an in-bed tube was pursued to explore the particle motion and its effect on tube erosion. An erosion model was developed to describe and analyze the phenomenon of in-bed tube erosion. A series of improved electrostatic impact probes, based on the triboelectric effect of moving particles, were developed and used as a primary standard for measuring the particle-surface collision frequency in the fluidized bed. Design guidelines were proposed for fluidized bed systems for planning counter measures against in-bed tube erosion.
- Research Organization:
- Catholic Univ. of America, Washington, DC (USA)
- OSTI ID:
- 7034709
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
014000* -- Coal
Lignite
& Peat-- Combustion
ADSORBENTS
ASHES
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COAL
COMBUSTION
COMBUSTORS
CORROSIVE EFFECTS
DESIGN
ENERGY SOURCES
EROSION
FLUIDIZATION
FLUIDIZED-BED COMBUSTION
FLUIDIZED-BED COMBUSTORS
FOSSIL FUELS
FUELS
MATERIALS
MATHEMATICAL MODELS
ORIENTATION
OXIDATION
PARTICLE SIZE
RECOMMENDATIONS
RESIDUES
SIZE
THERMOCHEMICAL PROCESSES
TUBES
VELOCITY