In situ analysis of ash deposits from black liquor combustion

P Bernath, S A Sinquefield, L L Baxter, G Sclippa, C M Rohlfing, M Barfield

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Aerosols formed during combustion of black liquor cause a significant fire-side fouling problem in pulp mill recovery boilers. (Black liquor is a recycled by-product formed during the pulping of wood in the paper-making industry). The ash deposits reduce heat transfer effectiveness, plug gas passages, and contribute to corrosion. Both vapors and condensation aerosols lead to the formation of such deposits. The high ash content of the fuel and the low dew point of the condensate salts lead to a high aerosol and vapor concentration in most boilers. In situ measurements of the chemical composition of these deposits is an important step in gaining a fundamental understanding of the deposition process. Infrared emission spectroscopy is used to characterize the composition of thin film deposits resulting from the combustion of black Liquor and the deposition of submicron aerosols and vapors. New reference spectra of Na2SO4, K2SO4, Na2CO3 and K2CO3 pure component films were recorded and compared with the spectra of the black liquor deposit. All of the black liquor emission bands were identified using our new reference spectra as well as literature data and ab initio calculations. The ab initio calculations predict the locations and intensities of infrared bands for the alkali-containing vapors of interest. (C) 1998 Elsevier Science B.V. All rights reserved.

Original languageEnglish
Pages (from-to)95-103
Number of pages9
JournalVibrational Spectroscopy
Issue number2
Publication statusPublished - May 1998


  • black liquor
  • ash deposits
  • in situ analysis
  • IR

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