Combating corrosion, deposit formation and emissions in biomass and waste fired boilers.

The ChlorOut® additive

The additive is injected into the flue gas upstream of the superheaters. This causes a rapid and effective conversion of the alkali chlorides in the flue gas to sulphates, which are less harmful from a corrosion and deposit point of view.

If ammonium sulphate is used as additive, a simultaneous reduction of the NOx content in the flue gases is also provided (SNCR reaction).

Corrosion ring - Before and after.
Test campaign in 100 MWth CHP plant: (Left) Deposits and corrosion products formed on test rings after four weeks exposure during combustion of a mixture of biomass and plastic waste. (Right) The appearance after ChlorOut injection with the same fuel mix during the same time period.

Main reactions

1. (NH4)2SO4→ 2NH3(g) + SO3(g) + H2O
The injected ammonium sulphate is dissociated into NH3 and SO3.

2. SO3 + H2O + 2KCl(g) → 2HCl(g) + K2SO4(s)
SO3 reacts with alkali chlorides and converts them into alkali sulphates and HCl.

SNCR reaction

3. 4NH3(g) + 4NO (g) + O2(g) →4N2(g) + 6H2O
The ammonia produced by reaction 1 reacts with the flue gas NO.

When NOx reduction is the primary driver for installation of ChlorOut, the technology is referred to as CleaNOx®.

ChlorOut test using ammonium sulphate (AS).

ChlorOut test using ammonium sulphate (AS): KCl and NO in the flue gas during combustion with wood and straw pellets. I. No injection, II. Injection of AS, III. Injection of increased amount of AS.

Test campaign in 100 MWth CHP plant.

Test campaign in 100 MWth CHP plant: KCl in flue gas and S, Cl in deposits collected on test rings. Reference case (Ref) and case with ammonium sulphate (AS).