Heat transfer and combustion in a two-bed fluidized combustor

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6131870

Foley, J E

Fluidized bed combustion has grown with the prospect that it can burn coal and low grade fuels in an environmentally acceptable manner. Among the technical problems that exist, however, is the inherent inability to produce large variations in heat transfer rate from the fluidized bed. The objective of this research was to investigate a new concept in fluidized bed design that improves load turndown capability. Load turndown ratio is defined as the ratio of maximum to minimum fuel firing rates. The design consisted of two fluidized beds: one central and one annular bed. The central bed served as the combustion bed. The annular bed was fluidized separately from the combustion bed and its level of fluidization determined the overall heat transfer rate from the combustion bed to a surrounding water jacket. A computational model consisting of energy and mass balances and a simple combustion kinetics model for the two-bed combustor were developed to predict the detailed performance of the combustor and to assist in the design of the unit. Combustion tests were performed in an optimally-designed combustor. Three coal-based fuel forms were used: crushed coal, coal-limestone briquettes, and coal-water-limestone mixture (CWLM). A load turndown ratio of 12.3 was obtained while burning crushed coal. Slightly lower turndowns were obtained for briquettes and CWLM. Sulfur dioxide emission reductions ranging from 42% to 93% were observed for a fuel calcium-to-sulfur molar ratio of 2.0. For most tests, emissions of NO{sub x} and SO{sub 2} met EPA New Source Performance Standards. Computer model predictions were in reasonable agreement with experimental observations.

• Research Organization: Iowa State Univ. of Science and Technology, Ames, IA (USA)
• OSTI ID: 6131870
• 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
BRIQUETS
CARBONACEOUS MATERIALS
CARBONATE ROCKS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COAL
COMBUSTION
COMBUSTION CONTROL
COMBUSTION KINETICS
COMBUSTORS
CONTROL
DESIGN
DESULFURIZATION
DISPERSIONS
EMISSION
ENERGY BALANCE
ENERGY SOURCES
ENERGY TRANSFER
FLUIDIZATION
FLUIDIZED BEDS
FLUIDIZED-BED COMBUSTION
FLUIDIZED-BED COMBUSTORS
FOSSIL FUELS
FUEL SLURRIES
FUELS
HEAT TRANSFER
HYDROGEN COMPOUNDS
KINETICS
LIMESTONE
LOAD MANAGEMENT
MANAGEMENT
MASS BALANCE
MATERIALS
MATHEMATICAL MODELS
MIXTURES
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PERFORMANCE
PULVERIZED FUELS
REACTION KINETICS
ROCKS
SEDIMENTARY ROCKS
SLURRIES
SOLID FUELS
SORBENT INJECTION PROCESSES
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
SUSPENSIONS
THERMOCHEMICAL PROCESSES
WATER