Interactions of PbCl2 with alkali salts in ash deposits and effects on boiler corrosion

A1 Originalartikel i en vetenskaplig tidskrift (referentgranskad)


Interna författare/redaktörer


Publikationens författare: Jonne Niemi, Hanna Kinnunen, Daniel Lindberg, Sonja Enestam
Publiceringsår: 2018
Tidskrift: Energy and Fuels
Volym: 32
Nummer: 8
Artikelns första sida, sidnummer: 8519
Artikelns sista sida, sidnummer: 8529
eISSN: 1520-5029


Abstrakt

A novel temperature gradient laboratory-scale corrosion test method was used to study PbCl2 migration, interactions with SiO2, NaCl, Na2SO4, KCl, K2SO4 or NaCl-KCl (50:50 wt-%), and corrosion of carbon steel in waste-fired boilers. Two different steel temperatures (200 °C and 400 °C) were tested. The temperature in the furnace above the deposits was 700-800 °C. Exposure times of 4 and 24h were used. The deposit cross-sections were analyzed using SEM/EDXA. The results show that PbCl2 vaporized and condensed in the adjacent deposits. PbCl2 did not interact with SiO2 but caused severe corrosion. Deposits containing Na2SO4, K2SO4 and/or KCl reacted with the PbCl2, forming various new compounds (Na3Pb2(SO4)3Cl, K3Pb2(SO4)3Cl and/or K2PbCl4). In addition, melt formation was observed with all alkali salt deposits. Visibly more Pb was found in deposits where reactions between PbCl2 and alkali salts were possible, i.e. Pb was observed to be bound to the reaction products. No measurable corrosion was observed with steel temperature at 200 °C, while steel temperature of 400 °C resulted in catastrophic corrosion. PbCl2 in contact with the steel surface lead to faster corrosion than K2PbCl4.


Nyckelord

boiler deposits, Corrosion, high-temperature corrosion, Superheater corrosion, Temperature gradient

Senast uppdaterad 2019-23-09 vid 04:45