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On-Line Determination of Green-Liquor Reduction Efficiency and Total Titratable Alkali Using Fourier-Transform-NIR Spectrometry

Dtermination en ligne de l’efficacit de la rduction de la liqueur noire et de l’alcali titrable total l’aide de la spectromtrie infrarouge transforme de Fourier

Dtermination en ligne de l’efficacit de la rduction de la liqueur noire et de l’alcali titrable total l’aide de la spectromtrie infrarouge transforme de Fourier

Abstract: In this paper, we describe the use of Fourier-transform Near-Infrared spectrometry (FT-NIR) for on-line measurement of green liquor compositions, such as TTA, EA, carbonate, sulphide, sulphate, thiosulphate, and reduction efficiency (RE) in raw green liquor. The technical feasibility of using this analyzer as an on-line monitoring system for dissolving tank TTA control as well as for reduction efficiency monitoring has been demonstrated during normal mill operation as well as for simulated upset conditions. FT-NIR data for TTA has tracked well with dissolver density values. In addition, FT-NIR reduction-efficiency data has been correlated to changes in black-liquor solids content, primary air flow and black-liquor firing rate. Online TTA control could help stabilize TTA which will stabilize recaust operations. The ability to monitor reduction efficiency online will provide operators with better understanding of boiler conditions that lead to “poor” conditions with high TRS and dead-load.

Paper presented at the 2007 International Chemical Recovery Conference in Quebec, Que., May 29 -June 1, 2007.

Keywords: GREEN LIQUOR, FT-NIR, TTA, REDUCTION EFFICIENCY, SULPHATE, THIOSULPHATE, ONLINE MONITORING, TTA CONTROL, SMELT DISSOLVING TANK, RECOVERY BOILER OPTIMIZATION, LIQUOR COMPOSITIONS

Full manuscript available at www.paptac.ca.