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Article

Solids Content of Black Liquor Measured by Online Time-Domain NMR

1
FiberLaboratory, South-Eastern Finland University of Applied Sciences, Vipusenkatu 10, FI-57200 Savonlinna, Finland
2
Valmet Automation Inc., Kehräämöntie 3, FI-87400 Kajaani, Finland
*
Author to whom correspondence should be addressed.
Appl. Sci. 2019, 9(10), 2169; https://doi.org/10.3390/app9102169
Received: 14 April 2019 / Revised: 14 May 2019 / Accepted: 22 May 2019 / Published: 27 May 2019
(This article belongs to the Special Issue Applications of Low Field Magnetic Resonance)
Black liquor, a valuable by-product of the pulp production process, is used for the recovery of chemicals and serves as an energy source for the pulp mill. Before entering the recovery unit, black liquor runs through several stages of evaporation, wherein the solids content (SC) can be used to control the evaporation effectiveness. In the current study, the time-domain nuclear magnetic resonance (TD-NMR) technique was applied to determine the SC of black liquor. The TD-NMR system was modified for flowing samples, so that the black liquor could be pumped through the system, followed by the measurement of the spin-spin relaxation rate, R2. A temperature correction was also applied to reduce deviations in the R2 caused by the sample temperature. The SC was calculated based on a linear model between the R2 and the SC values determined gravimetrically, where good agreement was shown. The online TD-NMR system was tested at a pulp mill for the SC estimation of weak black liquor over seven days without any fouling, which demonstrated the feasibility of the method in a harsh industrial environment. Therefore, the potential of the TD-NMR technology as a technique for controlling the black liquor evaporation process was demonstrated. View Full-Text
Keywords: black liquor; solids content; time-domain NMR; low-field NMR; NMR relaxation; online; 1H spin-spin relaxation rate black liquor; solids content; time-domain NMR; low-field NMR; NMR relaxation; online; 1H spin-spin relaxation rate
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MDPI and ACS Style

Nikolskaya, E.; Janhunen, P.; Haapalainen, M.; Hiltunen, Y. Solids Content of Black Liquor Measured by Online Time-Domain NMR. Appl. Sci. 2019, 9, 2169. https://doi.org/10.3390/app9102169

AMA Style

Nikolskaya E, Janhunen P, Haapalainen M, Hiltunen Y. Solids Content of Black Liquor Measured by Online Time-Domain NMR. Applied Sciences. 2019; 9(10):2169. https://doi.org/10.3390/app9102169

Chicago/Turabian Style

Nikolskaya, Ekaterina, Petri Janhunen, Mikko Haapalainen, and Yrjö Hiltunen. 2019. "Solids Content of Black Liquor Measured by Online Time-Domain NMR" Applied Sciences 9, no. 10: 2169. https://doi.org/10.3390/app9102169

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