Low N{sub 2}O, NO and SO{sub 2} emissions from circulating fluidized bed boilers

Book · Sun Dec 31 04:00:00 EST 1995

OSTI ID:287966

Lyngfelt, A; Amand, L E; Leckner, B ^[1]

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1. Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Energy Conversion

A new method, reversed staging, for decreasing N{sub 2}O without increasing the emission of the other pollutants, NO{sub x}and SO{sub 2}, was investigated in the 12 MW circulating fluidized bed boiler at Chalmers University of Technology. It was possible to reduce the emission of N{sub 2}O to one fourth (25 ppm), NO to half (about 40 ppm) compared to normal staging and normal temperature, without significantly affecting the sulfur capture efficiency (about 90%). Air staging, which is normally used in circulating fluidized bed boilers means that only a part of the combustion air, primary air, is added to the bottom zone, resulting in a lower oxygen concentration in the bottom part, while the secondary air results in more oxidizing conditions in the upper part of the combustion chamber and the cyclone. The principal idea of reversed staging is to reverse the conditions in top and bottom, i.e. to decrease the oxygen concentration in the upper part and to increase it in the bottom part. Such a reversal is accomplished by adding air in the bottom corresponding to an air ratio of approximately unity. No secondary air is added to the combustion chamber which means that the oxygen concentration will be low in the upper part of the combustion chamber and the cyclone. Air for final combustion is added in the cyclone outlet.

• OSTI ID: 287966
• Report Number(s): CONF-950522--; ISBN 0-7918-1305-3
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
AIR POLLUTION
BITUMINOUS COAL
CHEMICAL REACTION YIELD
CIRCULATING SYSTEMS
EMISSION
EXPERIMENTAL DATA
FLUIDIZED BED BOILERS
FLUIDIZED-BED COMBUSTION
FUEL-AIR RATIO
NITRIC OXIDE
NITROUS OXIDE
SORBENT INJECTION PROCESSES
STAGED COMBUSTION
SULFUR DIOXIDE