Title:
Recovery boiler superheater corrosion - solubility of metal oxides in molten salt

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dc.contributor.advisor Singh, Preet M.
dc.contributor.author Meyer, Joseph Freeman en_US
dc.contributor.committeeMember Gokhale, Arun
dc.contributor.committeeMember Keiser, James
dc.contributor.department Materials Science and Engineering en_US
dc.date.accessioned 2013-06-15T02:59:32Z
dc.date.available 2013-06-15T02:59:32Z
dc.date.issued 2013-04-15 en_US
dc.description.abstract The recovery boiler in a pulp and paper mill plays a dual role of recovering pulping chemicals and generating steam for either chemical processes or producing electricity. The efficiency of producing steam in the recovery boiler is limited by the first melting temperature of ash deposits that accumulate on the superheater tubes. Above the first melting temperature, the molten salt reacts with the protective oxide film that develops and dissolves it. The most protective oxide is determined by evaluating how little it dissolves and how its solubility changes in the molten salt. Solubility tests were done on several protective oxides in a known salt composition from a recovery boiler that burns hardwood derived fuel. ICP-OES was used to measure concentration of dissolved metal in the exposure tests while EDS and XRD were used to verify chemical compositions in exposure tests. NiO was found to be the least soluble oxide while Cr₂O₃ and Al₂O₃ had similar solubility with Fe₂O₃ being less soluble than Cr₂O₃ but more soluble than NiO. Exposure tests with pure metals and selected alloys indicated that even though Fe₂O₃ has little solubility, it is not a protective oxide and causes severe corrosion in stainless steels. The change in performance of iron based alloys was due to the development of a negative solubility gradient for Fe₂O₃ where Fe₂O₃ precipitated out of solution and created a continuous leaching of oxide. Manganese was found to be beneficial in stainless steels but its role is still unknown. Nickel based alloys were found to be least corroded due to nickel's low solubility and because it did not form a negative solubility gradient. en_US
dc.description.degree MS en_US
dc.identifier.uri http://hdl.handle.net/1853/47742
dc.publisher Georgia Institute of Technology en_US
dc.subject SEM en_US
dc.subject Pulp and paper en_US
dc.subject ICP en_US
dc.subject XRD en_US
dc.subject EDS en_US
dc.subject Recovery boiler en_US
dc.subject Corrosion en_US
dc.subject Molten salt corrosion en_US
dc.subject.lcsh Biomass stoves
dc.subject.lcsh Corrosion and anti-corrosives
dc.subject.lcsh Boilers Corrosion
dc.title Recovery boiler superheater corrosion - solubility of metal oxides in molten salt en_US
dc.type Text
dc.type.genre Thesis
dspace.entity.type Publication
local.contributor.advisor Singh, Preet M.
local.contributor.corporatename School of Materials Science and Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication 436052a4-5726-4887-bdbf-e726647a6d26
relation.isOrgUnitOfPublication 21b5a45b-0b8a-4b69-a36b-6556f8426a35
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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