Effect of Manganese on the Corrosion Behavior of Selected Alloys in Kraft Recovery Boiler Superheater Environments

ABSTRACT 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. [...]in order to improve the energy generation efficiency of the steam turbines, raising th...

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Bibliographic Details
Published inNACE International Corrosion Conference Proceedings pp. 1 - 16
Main Authors Hanson, Kasey, Singh, Preet M
Format Conference Proceeding
LanguageEnglish
Published Houston NACE International 01.01.2018
Subjects
Boiler furnaces
Boiler tubes
Boilers
Chlorine
Corrosion effects
Corrosion rate
Corrosion resistance
Corrosion resistant alloys
Discount coupons
Gas flow
High temperature
Manganese
Operating temperature
Oxidation
Potassium
Pulp & paper mills
Pulping
Recovery
Sodium carbonate
Sodium sulfate
Sodium sulfide
Stainless steel
Steam turbines
Steel alloys
Turbine engines
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Summary:ABSTRACT 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. [...]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. Previous work has shown a relation between increased levels of manganese present in the alloy composition with reduced corrosion rates of alloys coated in simulated superheater recovery boiler salt in the presence of steam. [...]in oxidizing environments this correlation is not observed. INTRODUCTION Operating temperatures of the superheater tubes in recovery boilers generally range from 480-490°C with some boilers operating above 500°C.1 Pulping chemicals combined with remnant wood components leftover from the fiber removal process is sprayed into the recovery boiler. Na2SO4, Na2CO3, NaCl and Na2S.6 Superheater deposits generally have melting temperatures above recovery boiler operating temperatures, however the presence of chlorine, and to a less extent potassium, drastically reduce the FMT of these deposits to within desirable recovery boiler operating temperature ranges.6 Interest in alloys with higher levels of Mn have been of interest in steam containing environments for recovery boilers due to some observed improved corrosion resistance.7 The exact cause of this is still unknown and will be investigated.