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AssigneePulp and Paper Research Institute of Canada
InventorDenys F. Leclerc
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A rapid method is provided for the on-line determination of sodium sulfide concentration and/or percent sulfidity in green liquors or smelt solutions used for the production of either kraft or sulfite pulp. The method eliminates manual sampling, and the need for frequent equipment maintenance. The method includes the steps of withdrawing samples of a smelt solution or green liquor from the kraft or sulfite manufacturing process, subjecting the samples to near-infrared spectrophotometry over a predetermined range of wave numbers so as to produce absorbance measurements relative to a reference spectrum of either water or a caustic soda-sodium carbonate solution, determining the absorbance shown by different combinations of sodium sulfide, sodium hydroxide, sodium carbonate and sodium chloride concentrations, correlating by multivariate calibration the relationships between the absorbance measurements of unknown samples and the absorbance shown by different combinations of sodium sulfide, sodium hydroxide, sodium carbonate and sodium chloride so that the amount of sodium sulfide and/or the percent sulfidity can be accurately determined for any levels of TTA or chloride present in the liquor.
A method for determining a sulfur concentration parameter of sulfide-containing aqueous pulp green liquor comprising:
A method according to 1 wherein the background spectrum is a water sulfidity.
A method for determining the concentration of sodium sulfide in green liquors and smelt solutions derived from the preparation of kraft or sulfite pulp wherein smelt is produced in a recovery furnace and fed to a smelt dissolving tank so as to form green liquor, which comprises the steps of:
In a cellulosic pulp manufacturing installation having a green liquor preparation unit including a recovery furnace for chemicals derived from a pulp manufacture process, a green liquor generation tank and a smelt flow line for flow of a smelt of inorganic chemicals from said recovery furnace to said tank, the improvement comprising a sensing apparatus for determining a sulfur concentration parameter of said green liquor, said apparatus comprising a fiber optic sensor operatively connected to a source of near infrared radiation over the range of wave numbers from 4000 to 14000 cm.sup.-1 a sample flow line from said tank, a sensing zone in said sample flow line for receiving near infrared radiation from said sensor, a spectrophotometer for recording absorbance spectra from said sensing zone, and comparator means for comparing the absorbance spectra from said sensing zone with a calibration of absorbance spectra for known concentration parameters and providing an evaluation of the concentration parameter of the sample.
Dependencies are inferred from the claim text.