The ChlorOut concept ― A method to reduce alkali-related problems during combustion

Combustion of biomass with a high content of alkali and chlorine (Cl) can result in operational problems including deposit formation and su- perheater corrosion. The strategies applied to reduce such problems include co-combustion and the use of additives. Ammonium sulphate is a part of the ChlorOut concept which is applied in a range of commercial boilers. This concept is based on dosing of sulphate-containing ad- ditives to the flue gases and a unique measure- ment device for on-line measurement of gaseous alkali chlorides called LACM (in-situ alkali chlo- ride monitor). The focus of the present paper is on evaluation of long-term experiences from two full-scale boilers. The operational problems with deposit formation and superheater corro- sion decreased in these boilers after installing the ChlorOut concept.