NO{sub x} reduction in pressurized fluidized-bed combustion
- Lawrence Livermore National Lab., CA (United States)
- Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Energy Conversion
Batch combustion experiments were performed in a small bubbling fluidized-bed reactor with the objective of establishing the cause of reduced NO{sub x} emissions from pressurized fluidized bed combustion (PFBC). All variables except for pressure were kept constant in the experiments: fuel batch size, for example, was the same in experiments performed at three pressure levels (0.2, 1 and 2 MPa). Two different types of experiments were conducted: one using air diluted with nitrogen (4.5% O{sub 2}) for the purpose of determining the conversion of fuel N to NO{sub x}, and the other with NO-doped diluted air (800 ppM NO, 4.5% O{sub 2}) for the purpose of determining the reduction of bulk-gas NO{sub x} by the burning fuel. A large excess of combustion air was used in all experiments so as to keep the bulk-gas composition relatively unchanged by combustion products. Six different fuels were studied: a bituminous coal, coke prepared from the same coal, three specialty cokes (one of which contained 10 wt % N) and graphite (0%N). The straight-air combustion experiments showed that the conversion of fuel-N to NO{sub x} dropped with increasing pressure (at constant fuel concentration in the bed). The NO-doped combustion experiments showed significantly increased NO{sub x} reduction with increased pressure. This effect was particularly strong between 0.2 and 1 MPa, and was found to continue between 1 and 2 MPa for some of the fuels but too saturate for others. These results imply that an important phenomenon for low PFBC NO{sub x} emission is the reaction of NO{sub x} with reducing N-containing species at the burning fuel surfaces. A simple kinetic model involving parallel paths for the fuel-N is suggested as an interpretation of the results. The NO-doped experiments showed increased N{sub 2}O formation relative to the straight-air experiments implying that N{sub 2}O was a byproduct of the NO{sub x} reduction reaction where N{sub 2} was the main product.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 10164256
- Report Number(s):
- UCRL-JC-112051; CONF-9205350-1; ON: DE93015032
- Resource Relation:
- Conference: 12. international conference on fluidized-bed combustion,San Diego, CA (United States),8-13 May 1992; Other Information: PBD: 5 Nov 1992
- Country of Publication:
- United States
- Language:
- English
Similar Records
Kinetic combustion experiments in a pressurized fluidized bed
Combustion of gasification residues in a pressurized fluidized-bed
Related Subjects
20 FOSSIL-FUELED POWER PLANTS
COAL
FLUIDIZED-BED COMBUSTION
NITROGEN OXIDES
AIR POLLUTION ABATEMENT
PRESSURIZATION
BITUMINOUS COAL
COKE
GRAPHITE
FUEL-AIR RATIO
PRESSURE DEPENDENCE
NITRIC OXIDE
NITROUS OXIDE
AIR
NITROGEN
014000
200202
COMBUSTION
NOXIOUS GAS AND PARTICULATE EMISSIONS