Scale deposit inhibitor for kraft digesters and method for controlling scale deposition in kraft digesters
AssigneeHakuto Co., Ltd.
InventorsAkira Togo, Takanori Shibata
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Abstract
A scale deposit inhibitor and a method for continuously controlling scale deposition applicable to a digester and its peripheral equipment used in kraft pulp manufacture are disclosed, the scale deposit inhibitor comprising a maleic acid-acrylic acid-hypophosphorous acid terpolymer having a maleic acid unit to acrylic acid unit molar ratio of 1:4 to 4:1, a hypophosphorous acid unit content of 1 to 12 mol %, and a weight average molecular weight of 500 to 10000. The scale deposit inhibitor is added to a cooking liquor in a concentration of 0.01 to 10 ppm per ppm of a calcium ion in the cooking liquor.
Claims4
A scale deposit inhibitor for a digester used in kraft pulp manufacture, which comprises a terpolymer comprising a maleic acid unit, an acrylic acid unit, and a hypophosphorous acid unit having a maleic acid unit to acrylic acid unit molar ratio of from 1:4 to 4:1, a hypophosphorous acid unit content of from 1 to 12 mol %, and a weight average molecular weight of from 500 to 10000.
A method for controlling scale deposition in a digester used in kraft pulp manufacture, which comprises adding a scale deposit inhibitor comprising a terpolymer comprising a maleic acid unit, an acrylic acid unit, and a hypophosphorous acid unit having a maleic acid unit to acrylic acid unit molar ratio of from 1:4 to 4:1, a hypophosphorous acid unit content of from 1 to 12 mol %, and a weight average molecular weight of from 500 to 10000 to a cooking liquor in a digester to a concentration of from 0.01 to 10 ppm per ppm of a calcium ion present in said cooking liquor.
Dependencies are inferred from the claim text.