Sulfur control and bed-material agglomeration experience in low-rank-coal AFBC testing

Conference · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6737842

Goblirsch, G M; Benson, S A; Hajicek, D R; Cooper, J L

The alkaline components of lignite and subbituminous coal ash aid in the retention of sulfur. Several low-rank coals do not require addition of limestone or other sorbents to meet NSPS standards for SO/sub 2/ emissions from AFBC systems. The optimum AFBC temperature for sulfur retention by the inherent alkaline ash for low-rank coals is lower than with comparable bituminous-coals using limestone. Sodium is a better sulfur sorbent at AFBC conditions than is calcium. Its effectiveness is dependent on the form in which it occurs in the coal. Agglomeration of ash and/or bed materials can occur at AFBC conditions when firing high-sodium low-rank coals. Agglomeration can manifest itself in particle growth, clusters of bed grains, deposits on stationary surfaces, and massive solidication. The amount and rate of agglomeration appear to be functions of the amount and form of the sodium, the availability of other ash components (e.g., silica), the selection of initial bed material, and the operating temperature. For limestone-based systems, agglomeration occurs by a sequence of calcination-sulfation-adhesion of small particles, growth of particles by layered adhesion, and fusing-growth of crystals. Agglomeration results in decreased heat transfer coefficient, lower combustion efficiency, and lower sulfur capture. Possible ways to minimize agglomeration include bed flushing, lower operating temperatures, higher gas velocities, operation without recycle, alteration of the coal ash composition, and the addition of alkali suppressants.

• Research Organization: Department of Energy, Grand Forks, ND (USA). Grand Forks Energy Technology Center; Combustion Power Co., Inc., Menlo Park, CA (USA)
• OSTI ID: 6737842
• Report Number(s): DOE/FC-1005; CONF-821064-2; ON: DE83001867
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
014000* -- Coal
Lignite
& Peat-- Combustion
AGGLOMERATION
AIR POLLUTION ABATEMENT
ALKALI METALS
ALKALINE EARTH METALS
ASHES
BROWN COAL
CALCIUM
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
COAL
COAL RANK
COMBUSTION
ELEMENTS
ENERGY SOURCES
FLUIDIZED-BED COMBUSTION
FOSSIL FUELS
FUELS
LIGNITE
MATERIALS
METALS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
POLLUTION ABATEMENT
RESIDUES
SODIUM
SUBBITUMINOUS COAL
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
THERMOCHEMICAL PROCESSES