Particle entrainment and nitric oxide reduction in the freeboard of a fluidized coal combustor. [Freeboard reactions]

Conference · Fri Jan 01 04:00:00 EST 1982 · Prepr. Pap. - Am. Chem. Soc., Div. Fuel Chem.; (United States)

OSTI ID:7050980

Walsh, P M; Chaung, T Z; Dutta, A; Beer, J M; Sarofim, A F

Economic design of fluidized bed combustors requires a combination of fluidizing velocities and particle sizes which result in the unavoidable carry over of bed solids, coal char particles and unburned gaseous combustion products into the free-board. Depending upon the design parameters, the last 5 to 10% of the combustibles will burn, and also significant reduction of SO/sub 2/ and NO/sub x/ will take place, in the freeboard of the fluidized combustor - between the top of the bed and the first row of the convective tube bank. A mechanistic model for particle entrainment into the freeboard has been developed and used in conjunction with a chemical kinetic description of the NO-char reaction for prediction of the reduction of NO along the height of the freeboard in fluidized coal combustion. Bed conditions, including the mass fraction of char in the bed, are input to the model. Predicted NO profiles showed good agreement with experimental data obtained while burning bituminous and subbituminous coals under a variety of operating conditions. The steep reduction in NO observed in the splash zone immediately above the bed in some cases could not be adequately explained by the present model. This result points to the importance of the reactions in the splash zone, where it is thought that NO reducing reactions other than the NO-char reaction will have to be taken into account for satisfactory prediction of the NO profile under all conditions. The model is now in a form in which it can be integrated into system models for predicting NO emissions as a function of operating conditions.

• Research Organization: Massachusetts Inst. of Technology, Cambridge
• DOE Contract Number: FG22-80PC30215
• OSTI ID: 7050980
• Report Number(s): CONF-820304-Vol.2
• Conference Information: Journal Name: Prepr. Pap. - Am. Chem. Soc., Div. Fuel Chem.; (United States) Journal Volume: 27:1
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010800 -- Coal
Lignite
& Peat-- Waste Management
014000* -- Coal
Lignite
& Peat-- Combustion
20 FOSSIL-FUELED POWER PLANTS
200202 -- Fossil-Fueled Power Plants-- Waste Management-- Noxious Gas & Particulate Emissions
AEROSOL WASTES
AIR POLLUTION ABATEMENT
ASHES
BUBBLES
CARBON
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL REACTIONS
COAL
COMBUSTION
COMBUSTORS
DATA
DESIGN
ECONOMICS
ELEMENTS
ELUTRIATION
ENERGY SOURCES
EXPERIMENTAL DATA
FLUIDIZATION
FLUIDIZED-BED COMBUSTION
FLUIDIZED-BED COMBUSTORS
FLY ASH
FOSSIL FUELS
FUELS
INFORMATION
MATERIALS
MATHEMATICAL MODELS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PARTICLE SIZE
POLLUTION ABATEMENT
RECYCLING
RESIDUES
SEPARATION PROCESSES
SIZE
THERMOCHEMICAL PROCESSES
VELOCITY
WASTES