Corrosion Behavior of Selected Alloys in Kraft Recovery Boiler Superheater Environments

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This research aims to develop a fundamental understanding of the synergistic effect between molten salt and hot gaseous environments on corrosion mechanisms in kraft recovery boiler superheater tubes.

Product Number: 51317--9159-SG

ISBN: 9159 2017 CP

Author: Kasey Hanson

Publication Date: 2017

Industry: Process Industries

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Energy demands of the modern pulp and paper mill are satisfied in part from turbine engines powered by heating steam within superheater tubes located in the upper furnace of kraft recovery boilers. Thus in order to improve the energy generation efficiency of the steam turbines raising the operating temperatures of recovery boilers is one solution to achieve higher steam temperatures. However elevating the recovery boiler operating temperature results in increased fireside corrosion of superheater tubes which are exposed to molten salts and gaseous environments. Furthermore corrosion rates drastically increase upon exceeding the first melting temperature of superheater tube deposits. This research aims to develop a fundamental understanding of the synergistic effect between molten salt and hot gaseous environments on corrosion mechanisms in kraft recovery boiler superheater tubes. Tests were done under simulated superheater gaseous conditions on bare alloy samples as well as on samples covered with simulated superheater deposits. Although effects differ among thedifferent alloys tested the corrosion results have shown a synergistic effect ofdeposits/gas interactions at the metal surface.

Key words: tubes, suprheater, boilers, mass change, kraft recovery