Nitrogen containing additives for simultaneous reduction of KCL and NOx during biomass combustion in a CFB boiler
Paper i proceeding, 2008

High levels of alkali chlorides in the flue gas can cause enhanced deposit formation and superheater corrosion during combustion of biofuels. These alkali chlorides mainly originate from potassium chloride (KCl). A challenge during combustion of biofuels is to simultaneously reduce NOx and KCl. The ChlorOut concept has been developed by Vattenfall to minimise deposit formation and corrosion. It consists of IACM, an instrument for on-line measurements of gaseous alkali chlorides, and a sulphate-containing additive that converts alkali chlorides to less corrosive alkali sulphates. The sulphate-containing additive is often ammonium sulphate, (NH4)2SO4, and, therefore, a significant NOx reduction is also achieved. This paper presents the results from a comparison of the conventional SNCR additives (ammonia or urea) and (NH4)2SO4 for reduction of NOx and/or KCl during combustion in a CFB boiler. The fuel consisted of either a mixture of wood chips and wood pellets with added PVC or with straw pellets. Of special interest was the influence of sulphation of KCl in parallel to the reduction of NO and if these processes interact. The results show that there are rather small differences in performance concerning NOx reduction between the additives.

Fluidized bed Combustion

Reduction of KCl and NOx

Nitrogen containing additives


Håkan Kassman

Chalmers, Energi och miljö

Magnus Holmgren


Elin Edvardsson

Chalmers, Energi och miljö

Lars-Erik Åmand

Chalmers, Energi och miljö

Johannes Öhlin

Chalmers, Energi och miljö

9th International Conference on Circulating Fluidized Beds, CFB 2008, in Conjunction with the 4th International VGB Workshop on Operating Experience with Fluidized Bed Firing Systems; Hamburg; Germany; 13 May 2008 through 16 May 2008

Paper 14_13-
978-393040057-7 (ISBN)


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