Alloy degradation in a co-firing biomass CFB vortex finder application at 880 degrees C

• Mechanisms of alloy degradation in a fireside N-S-O-C-H-Cl-Na-K atmosphere at 880 degrees C were elucidated using SEM-EDS, chemical equilibrium calculations, and XRD. Alloys 310S, 800H/HT, and 600 were studied after 0, 8000, and 16,000 h exposure in a boiler co-firing biomass waste. For 310S and 800H/HT it was shown that nitrogen formed internal Cr nitrides lowering the Cr activity and inhibiting internal alloy Cr permeation, and that NaCl and Na2SO4 reacted with Cr oxide to form chromate and to accelerate the S and the Cl pickup. Alloy 600 showed no nitride or major chromate formation.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik -- Korrosionsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering -- Corrosion Engineering (hsv//eng)

Nyckelord

Na

K

Cl

O-2

CO

CO2

HCl

SO2

NH3

N-2

Nitride

Carbide

Sulfide

Oxide

Chloride

Volatilization

Vortex finder

CFB boiler

High-temperature corrosion

Alloy 310S

Alloy 800H/HT

Alloy 600

Co-combustion

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