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Patent
Kurita Water Industries Ltd. and Nippon Synthetic Chemical Industry Co. | Date: 2017-01-18

Provided is a method for producing paper and a pitch removal agent that can remove pitch efficiently. A pitch removal agent having an average polymerization degree of 300 to 2500, a saponification index of 70 to 88 mol % and satisfying, when the absorbance at a wavelength of 490 nm is designated as y (Abs) and the saponification index as x (mol %), the Numerical Formula (A) below is added to a pulp slurry during production of paper using waste paper in the step of deinking the waste paper by floatation and/or a step earlier:


Patent
Kurita Water Industries Ltd. | Date: 2017-01-25

A method for treating a circulating water in a wet paint booth, the method comprising adding a treatment agent comprising an aqueous solution comprising a tannin and an alkali metal hydroxide and/or an alkali metal carbonate to the circulating water in any of passages for the circulating water in the wet paint booth, wherein the passages include for supplying the circulating water from a water tank to a paint booth, for collecting an uncoated paint in the circulating water, and for returning the circulating water to the water tank; to detackify the uncoated paint collected in the circulating water.


Patent
Kurita Water Industries Ltd. | Date: 2017-01-04

Provided are a device for controlling chemical injection into a boiler and a chemical injection method, which can control an injection amount such that a chemical concentration is obtained as per a target even in a boiler feed-water facility where a flow rate of feed-water varies to a large extent in a short period. A device for controlling the injection of a chemical into a boiler controlles an amount discharged by a chemical injection pump 37 in proportion to a flow rate measured by a flowmeter 40. An average chemical concentration in a feed-water is calculated from an amount of feed-water per predetermined period obtained by the flowmeter 40 and a reduction in the amount of chemical in a tank 36 per predetermined period obtained by a sensor 39. The chemical injection pump 37 is controlled on the basis of the calculated average chemical concentration and a preset target chemical concentration of the feed-water so that the average chemical concentration is within the target chemical concentration range.


Patent
Kurita Water Industries Ltd. | Date: 2016-02-03

Provided are a method and an agent for treating water in a cooling water system equipped with an iron-made facility, both of which can prevent the corrosion of iron and can also prevent the formation of calcium-containing scales effectively. A method for treating water in a cooling water system equipped with an iron-made facility, which comprises adding a combination of tungstic acid and/or a tungstate, and polyacrylic acid and/or a copolymer to the cooling water system, wherein the copolymer is produced by copolymerizing acrylic acid with a monomer having a sulfonic acid group, and the content of acrylic acid in the copolymer is 97% or more.


Patent
Kurita Water Industries Ltd. | Date: 2016-07-11

In measuring a dissolved substance, a concentration of a specific dissolved substance in a sample water is measured using a measuring water W1 developing a specific color within a specific pH range by adding each of two reagents to a sample water W0, and an acid-base indicator S developing different colors other than the specific color is selected in a first pH range including the specific pH range and a second pH range deviating from the first pH range. Next, a reagent is prepared by adding the acid-base indicator to one reagent wherein a pH value of a reagent added water where the two kinds of reagents are separately added to the sample water is within the second pH range. Next, absorbance values are calculated by three region component lights which are a transmitted light in the measuring water wherein the prepared reagent is added.


In an electrodeposition treatment of an iron-group metal ion-containing liquid, without being influenced by the properties of the iron-group metal ion-containing liquid, iron-group metal ions are efficiently removed from the liquid by precipitation. An anode chamber 2A provided with an anode 2 and a cathode chamber 3A provided with a cathode 3 are separated from each other by a cation exchange membrane 5, an iron-group metal ion-containing liquid is charged into the anode chamber 2A, a cathode liquid is charged into the cathode chamber 3A, and by applying the voltage between the anode 2 and the cathode 3, iron-group metal ions in the liquid in the anode chamber 2A are moved into the liquid in the cathode chamber 3A through the cation exchange membrane 5, so that an iron-group metal is precipitated on the cathode 3.


Patent
Kurita Water Industries Ltd. | Date: 2016-05-18

An efficient slime control method in a white water circulation line in a paper making process is provided. The present slime control method in a white water circulation line in a paper making process including the steps of: aerating with an oxygen-containing gas either one or both of a white water circulation line and the water feeding line for feeding water into the white water circulation line; and adding a slime control agent to at least one line of the white water circulation line and the water feeding line aerated with the oxygen-containing gas in the aerating step. Preferably, the step of measuring at least one selected from the group of measurement items consisting of the oxidation reduction potential, the sulfite ion concentration and the amount of dissolved oxygen in the white water circulation line is further included. Based on the measurement result obtained in the measurement step, the aeration rate in the aerating step and/or the amount of the slime control agent added in the adding step of the slime control agent may be regulated.


In a cooling water system having been subjected to an antimicrobial treatment using chlorosulfamic acid or a salt thereof, algae growing therein are effectively killed and removed. An antimicrobial and algicidal method for a cooling water system characterized in that in a cooling water system subjected to an antimicrobial treatment using a chlorosulfamic acid and/or a chlorosulfamic acid salt, when algae are generated, an isothiazolone-based compound is further added to the cooling water system. The chlorosulfamic acid and/or a salt thereof are added to the cooling water system in such a manner as to give a residual chlorine concentration of 0.5 mg-Cl_(2)/L or higher.


Patent
Kurita Water Industries Ltd. | Date: 2016-02-10

Provided is a method for removing a scale in a steam generation facility, whereby it becomes possible to remove a scale deposited on the inside of a boiler vessel during the operation of a boiler without causing corrosion of the boiler. A method for removing a scale in a steam generation facility is disclosed, wherein in the steam generation facility, a pH of boiler water is adjusted to 11.3 or more, and a polyacrylic acid having a weight average molecular weight that is 0.50 to 2.00 times a reference weight average molecular weight as calculated from the following calculation formula (1), or a salt thereof, is added in accordance with the pH value of the boiler water during the operation of a boiler, thereby removing a scale deposited on the inside of a boiler vessel:


Patent
Kurita Water Industries Ltd. | Date: 2016-12-21

Provided are a method for removing scale and a scale remover that can efficiently remove scale deposited inside a boiler can or the like in an addition amount of chemicals permissible in terms of cost without corroding a boiler, particularly can efficiently remove scale deposited inside a boiler can even in a facility operated with feed water containing high-concentration iron. A method for removing scale deposited in a system of a steam generating facility, wherein polyacrylic acid having a weight-average molecular weight of more than 20,000 and 170,000 or less and/or a salt thereof is added to feed water of the steam generating facility. When the feed water contains iron, polymethacrylic acid having a weight-average molecular weight of more than 1,000 and 100,000 or less and/or a salt thereof is further added in combination.

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