Low N2O, NO and SO2 emissions from circulating fluidized bed boilers
Other conference contribution, 1995

A new method, reversed staging, for decreasing N2O without increasing the emission of the other pollutants, NOx and SO2, was investigated in the 12 MW circulating fluidized bed boiler at Chalmers University of Technology. It was possible to reduce the emission of N2O to one fourth (25 ppm), NO to half (about 40 ppm) compared to normal staging and normal temperature, without significantly affecting the sulphur 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.

NO and N2O

nitric oxides

Fluidised bed combustion

nitrious oxide


Anders Lyngfelt

Chalmers, Department of Energy Technology

Lars-Erik Åmand

Chalmers, Department of Energy Technology

Bo G Leckner

Chalmers, Department of Energy Technology

Proc. Int. Conf. Fluid. Bed Combustion

0197-453X (ISSN)

Vol. 13 1049-1057
07918-1305-3 (ISBN)

Driving Forces

Sustainable development

Subject Categories

Energy Engineering

Chemical Engineering

Other Environmental Engineering

Areas of Advance



Chalmers Power Central



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