JP7328001B2 - How to dilute and add chemicals - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for diluting and adding chemicals in a paper manufacturing process. In the paper manufacturing process, especially the papermaking process, when chemicals are added to the process water system, it enables rapid and uniform mixing and dispersion in the water system, and the dilution of chemicals that enables good paper product properties and a reduction in the amount of chemicals added. Addition method is provided.

Many process water systems, such as the circulating water system in paper manufacturing and the water system that flows into the circulating water system, contain large amounts of organic substances such as starch, sizing agents, latex, dispersants, dyes, and casein in addition to cellulose fibers, and the water temperature is stable. Since the temperature is close to normal temperature, it is an environment where microorganisms such as bacteria and fungi can easily grow. Therefore, slime derived from such microorganisms is likely to grow in water such as a circulating water system or on the surfaces of pipes and equipment.
When this slime is mixed into the product, it lowers the product quality and production efficiency and causes offensive odors. Therefore, slime inhibitors are used in the circulating water system and in the process water system that flows into the circulating water system.
In addition, calcium ions and barium ions derived from the raw pulp are eluted into white water and the like of the circulating water system, and in particular, a large amount of calcium ions derived from the inorganic filler is eluted from the recovered waste paper pulp.
Aluminum sulfate used in the papermaking process, sulfate ions derived from sulfuric acid for pH adjustment, sodium silicate contained as a stabilizer for hydrogen peroxide used in bleaching, silica ions eluted from raw material pulp, etc. The calcium ions and barium ions combine to form scales of calcium sulfate, barium sulfate, calcium silicate, and the like, which are extremely sparingly soluble in water.
Scale adheres to paper manufacturing process equipment such as raw material machine chests, tanks, seed boxes, inlets, pipes, pumps, screens, etc., and causes performance deterioration. Furthermore, the scale adhering to the wall surface of the equipment comes off and moves to the product, resulting in paper cuts and spots on the paper product, which impairs the quality, resulting in a great loss in paper productivity. Therefore, scale inhibitors are used in the water system of the paper manufacturing process.
For the above reasons, the water used in the paper manufacturing process contains anti-slime agents, anti-scaling agents, anti-foaming agents, anti-fouling agents that prevent soiling of inorganic and organic compounds caused by raw materials and additives in the manufacturing process, and Various chemicals are used, such as rust inhibitors to prevent metal rust in pipes and equipment, and deodorants to prevent odors generated in the paper manufacturing process.

Conventionally, as a general mixing device for additive chemicals, an underwater agitator that rotates blades in reservoir water to which chemicals are added is mainly used. As another mixing device, a pipe type agitating device such as a static mixer in which a fluid is passed through a pipe in which helical elements are alternately arranged is used (Patent Documents 1, 2 and 3).

Due to the speeding up of paper manufacturing in recent years, especially in the papermaking process, it is required to add chemicals to a large amount of circulating water system or to the water system flowing into the circulating water system, and to dilute and mix the chemicals efficiently and uniformly in a short time.
However, the conventionally used chemical liquid mixing apparatus described above is insufficient for uniform mixing in a short period of time, and an excessive amount of chemical agent has to be added in order to obtain the desired chemical effect. As a result, there have been problems such as deterioration of paper product properties due to residual chemicals and an increase in chemical costs.

As a mixing technique used in fields other than paper manufacturing, Patent Document 4 discloses a method of mixing powder and liquid using jet injection, and Patent Document 5 discloses a chemical mixing device using a jet pump. ing.
However, any of these prior arts are used to prepare a uniform chemical solution in the pre-process to be supplied to the process water system, and do not disclose use for diluting and adding the chemical solution to the process water system in paper manufacturing.

JP 2004-148172 A JP-A-9-241987 JP 2006-255552 A JP-A-9-313909 JP-A-3-229691

The present invention is a method for diluting and adding chemicals to solve the above-mentioned problems of the prior art in the water system of the paper manufacturing process, and particularly in the papermaking process, when adding chemicals to the process water system, rapid and uniform mixing is achieved in the water system. It is an object of the present invention to provide a method for diluting and adding a chemical solution that enables dispersion, good paper product properties, and a reduction in the amount of chemical solution to be added.

In order to solve the above problems, the present invention
(1)
A paper manufacturing process comprising one or more water reservoirs for retaining the circulating water of a circulating water system or the influent water of an influent water flowing into the circulating water system,
A method for diluting and adding a chemical liquid using an underwater agitating device installed in at least one portion of the water reservoir of the water reservoir,
The underwater stirring device
a hollow tube having a suction hole at least in its wall surface;
a pressurized liquid supply pipe that adds a chemical solution to the process water containing the circulating water or the influent water and pressurizes it to produce a pressurized aqueous liquid;
a jet nozzle for injecting the pressurized aqueous liquid into the hollow tube as jet water;
comprising a diluent liquid discharge unit connected to the hollow tube,
By injecting the jet stream water, a negative pressure is generated in the hollow tube, and the stored water is sucked into the hollow tube as suction stored water from the suction hole, and the jet stream water and the suctioned stored water are mixed. A method for diluting and adding a chemical solution, wherein the diluted chemical solution is discharged from the diluted chemical solution discharge part into the pooled water of the water storage part in which the underwater stirring device is installed.
(2)
After supplying a predetermined amount of the chemical solution to the process water, the stored water containing the diluted chemical solution in the water reservoir is supplied as the process water to the pressurized liquid supply pipe, and the jet nozzle flows the jet water. is continued for a predetermined time,
The method for diluting and adding a chemical solution according to (1), wherein the chemical solution is dispersed by passing the stored water through the underwater stirring device and circulating it in the water reservoir.
(3)
The chemical solution according to (1) or (2), wherein the chemical solution is a liquid containing at least one of a slime control agent, a scale inhibitor, an antirust agent, an antifoaming agent, and a deodorant. Dilution addition method.
configuration.

According to the method of diluting and adding a chemical solution of the present invention, when adding the chemical solution to at least one of the circulating water system and the water system flowing into the circulating water system in the paper manufacturing process, it is possible to quickly and uniformly disperse the mixed chemical solution of the chemical solution and the water system. As a result, uneven distribution of the chemical solution is prevented, the chemical effect in the chemical solution is exhibited to a high degree, uniform and good paper product properties are obtained, wasteful excessive addition of the chemical solution is suppressed, and the use of chemical solution can be reduced.
Furthermore, by the method of diluting and adding chemicals of the present invention, the effect of stirring the water reservoir in the paper manufacturing process improves the efficiency of the chemical effect and prevents the stagnation of substances that cause odors, thereby reducing odors generated in the process. It also has the effect of preventing product odor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a model diagram of an example of a papermaking process in which the method of diluting and adding a chemical solution according to the present invention is implemented; 1 is a model diagram of an example of an underwater stirring device used in the method for diluting and adding a chemical solution according to the present invention. FIG.

The present invention will be described below with reference to FIG. FIG. 1 shows an example of using the method of diluting and adding chemicals according to the present invention in the papermaking process.

The method for diluting and adding a chemical solution according to the present invention is applied to a paper manufacturing process, particularly a papermaking process, in a paper mill.

In the present invention, the "papermaking process" means a process including a raw material adjustment system A1, a white water circulation system A2, and a white water recovery system A3, for example, as shown as papermaking process A in FIG. It is the entire water circulation process including the recovery and reuse system of the aqueous solution (mainly white water) discharged to the water system, and the water system flowing into these processes is also included.
The term "white water" as used herein means process water containing fine fibers derived from the raw pulp used in normal papermaking and other chemicals for papermaking.

The paper manufacturing process and water circulation are outlined below. First, a raw material for papermaking is adjusted in a raw material adjustment system A1 having a raw material adjustment tank 1 and a machine chest 2 in a papermaking process A.
That is, a raw material containing pulp and water (not shown) are supplied to the raw material adjusting tank 1, and further water supplied from the recovered water tank 12 by the pump 13 is added to adjust the pulp slurry.
The adjusted pulp slurry is supplied to the machine chest 2, and various papermaking chemicals such as a viscosity modifier and a paper strength agent are added. After that, the pulp slurry is supplied to the white water circulation system A2 by the pump 3, mixed with the white water from the white water silo 5, and supplied to the inlet 6 as stock.
The paper stock supplied from the inlet 6 to the wire 7a of the wire part 7 is dewatered into a sheet shape, sent to the paper manufacturing process after the press part 8, and becomes a paper product.
On the other hand, the water remaining in the wire part 7 is stored as white water in the white water silo 5 and is supplied again to the inlet 6 by the pump 4 to form the white water circulation system A2.

A part of the white water stored in the white water silo 5 is supplied from the white water silo 5 to the seal pit 9 of the white water recovery system A3. The white water supplied to the seal pit 9 is sent to the solid-liquid separator 11 by the pump 10 and subjected to solid-liquid separation.
Water of the components subjected to solid-liquid separation is stored in the recovered water tank 12, and then part of it is supplied to the raw material adjustment tank 1 of the raw material adjustment system A1 by the pump 13 and used to adjust the concentration of the pulp slurry. be done.
Another part of the water is used as shower water for keeping the wire 7a of the wire part 7 and the felt of the press part 8 clean through a pipe (not shown). The water generated in the solid-liquid separation treatment is reused as various types of water in the papermaking process A in this manner.
The white water recovery system A3 constitutes the water circulation system of the papermaking process A together with the raw material adjustment system A1 and the white water circulation system A2, and water circulates in this water circulation system.
A part of the water in the recovered water tank 12 is discharged outside the system for concentration adjustment and sent to a waste water treatment facility (not shown).

In the papermaking process A of FIG. 1, the machine chest 2, the white water silo 5, the seal pit 9, the recovered water tank 12, and the cushion tank 14 are examples of water storage units in which the underwater agitator S of the present invention is installed.
However, the water storage part in the present invention is not limited to the locations of these circulating water systems, but is present in other circulating water systems in the papermaking process, these circulating water systems, or other water systems flowing into other circulating water systems, and retains water. All such water reservoirs are included in the present invention.

In the present invention, examples of the water that flows into the circulating water system in the paper manufacturing process such as the papermaking process include tap water, industrial water, and treated water from wastewater treatment facilities, but are not limited to these.

In the method for diluting and adding a chemical solution of the present invention, the white water circulation system A2, the white water recovery system A3, or the raw material adjustment system A1 (hereinafter collectively referred to as "circulating water system"), and these water systems The diluted chemical solution is added to the water system of the water reservoirs present in the inflowing water system (for example, the cushion tank 14, the water line 15) by the underwater agitator S provided in the water reservoirs of those water reservoirs.
Although the water storage part is not particularly limited, it is intended for a place where water temporarily stays, such as a water tank existing in the water system.

In the underwater agitator S of the present invention, as illustrated in FIG. At least some water (circulating water or/and influent water 25a) is supplied as process water 25, and preferably stored water 27a of a water reservoir 27 in which a submersible agitator S is installed is supplied as process water 25. be done. On the other hand, the chemical solution 22b is supplied to the process water 25 from the chemical solution supply port 22c of the chemical solution supply pipe 22a.
The vicinity of the end of the hollow tube 20 on the side where the jet nozzle 21 is installed is enlarged in diameter, and a negative pressure 20a is generated by jetting the jet stream water 21a of the process water 25 containing the chemical solution 22b.
Due to the negative pressure 20a, the stored water 27a, which is the circulating water of the water storing part 27, or the inflowing water (not shown) flowing into the circulating water system is smoothly sucked from the suction hole 24 in the vicinity of the jet nozzle 21, and the chemical solution 20b is drawn. The jet water flow 21a of the process water 25 containing The diluted chemical liquid 23a is discharged into the water of the water storage section from the diluted chemical liquid discharging section 23 which is in the water storage section.
As a result, the chemical solution 22b is added to at least one of the circulating water system and the water system flowing into the circulating water system.
Addition of the chemical liquid 22b to the pressurized liquid supply pipe 22, supply of the pressurized liquid to the jet nozzle 21, and injection to the hollow tube 20 can be continuous or intermittent, but the addition condition of the chemical liquid 22b is continuous depending on the type. Addition or intermittent addition is preferably selected.
After a predetermined amount of the chemical solution 22b is discharged and added to the process water 25, which is preferably the circulating water and/or the influent water 25a, the supply of the chemical solution 22b to the pressurized liquid supply pipe 22 is stopped, and the chemical solution 22b is discharged. As a stirring and dispersing cycle, stored water 27a containing circulating water and/or inflow water 25a containing diluted chemical solution 23a in water storing section 27 is supplied as process water 25 to pressurized liquid supply pipe 22 of underwater stirring device S. , supplying the liquid from the pressurized liquid supply pipe 22 to the jet nozzle 21, injecting it into the hollow pipe 20, and discharging it into the stored water 27a in the water reservoir is repeated for a predetermined period of time.
That is, by passing the stored water 27a containing the diluted chemical solution 23a through the underwater agitator S and continuing the flow of the jet stream water 21a by the jet nozzle 21 for a predetermined time, the water in the water reservoir 27 where the underwater agitator S is set , the stored water 27a can be circulated, and the aforementioned stirring and dispersing cycle of the chemical solution 22b is automatically executed.
As a result, uniform dispersion of the chemical liquid in the water system in the water reservoir is achieved. In this case, the hollow tube 20 is provided with at least one suction hole 24 on the wall surface near the jet nozzle 21 to suck and store water 24a containing circulating water or inflow water containing diluted chemical solution 23a in the water reservoir. This is preferable for uniform distribution of the liquid medicine (medicine) because the supply to the tube 20 is accelerated.

The jet nozzle 21 used in the present invention is fixed to the end wall of the hollow tube 20 while penetrating the end of the hollow tube 20. The jet nozzle 21 is opened in the longitudinal direction of the hollow tube 20 to allow a pressure feed pump or the like to flow into a hose or pipe. The pressurized aqueous liquid 26 containing the chemical solution sent by such means can be jet-sprayed in the longitudinal direction, which is the direction of the diluted chemical solution discharge part 23 at the other end of the hollow tube 20, as the jet water stream 21a. ing.
The injection amount of the jet water stream 21a can be controlled and adjusted by adjusting the amount of pressurized water by a pumping pump, the amount of opening and closing of the injection nozzle, and the like. Although the shape of the hollow tube of the present invention is shown to be cylindrical in FIG. 2, a rectangular parallelepiped shape can also be used, and the shape is not limited.

The underwater agitator of the present invention has the advantage that it can be installed in an existing water reservoir such as a papermaking system without extensive modification. As the underwater agitating device, it is preferable to use a horizontal injection type or a downward injection type.
The use of an upward jet type underwater agitating device is not preferable in the case where the water flow ruffles the air-liquid interface, increasing the risk of entraining air as air bubbles in the water, which adversely affects paper properties.

In the present invention, an underwater agitating device is installed in at least one of a circulating water system composed of a raw material adjustment system, a white water circulating system, and a white water recovery system, and a water reservoir existing in a water system flowing into the circulating water system, Dilute and add the chemical solution.
Examples of the chemical solution include slime inhibitors, scale inhibitors, antifouling agents, rust inhibitors, antifoaming agents, deodorants, and the like listed below, but are not particularly limited, and known chemical solutions related to paper manufacturing are used. be done.

Examples of anti-slime agents include sodium hypochlorite, combined chlorine compounds obtained from ammonium salts and hypochlorite, methylenebisthiocyanate, 2,2-dibromo-3-nitrilopropionamide, 2,2- dibromo-2-nitroethanol, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one and the like.

Examples of scale inhibitors include polymers having carboxyl groups obtained by polymerizing maleic acid, acrylic acid, itaconic acid, etc., monomers having carboxyl groups and vinylsulfonic acid, allylsulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid. and copolymers with nonionic vinyl monomers such as acrylamide, inorganic polyphosphates such as sodium hexametaphosphate and sodium tripolyphosphate, and phosphonic acids such as hydroxyethylidene diphosphonic acid and phosphonobutanetricarboxylic acid. mentioned.

Examples of antifouling agents include organic acids such as citric acid, malic acid, and tartaric acid that prevent inorganic fouling; inorganic acids such as hydrochloric acid, sulfuric acid, and sulfamic acid; Oxyalkylene ether solvents, alkyl polyoxyethylene phosphate ester surfactants, mixtures thereof, and the like are included.

Examples of rust inhibitors include nitrites, molybdates, chromates, phosphonates, polymerized phosphates, orthophosphates, zinc salts, triazole compounds, amines, and various surfactants, polymers.

Examples of antifoaming agents mainly used include self-emulsifying types and emulsion types. Examples of emulsion types include polyoxyalkylenepolyalkylsiloxanes, polydimethylsiloxanes, higher alcohols, fatty acid esters, and the like.

Examples of deodorants include chlorite-based deodorants, polyphenol-based deodorants, amphoteric surfactants, citric acid, graft polymer-based deodorants, betaine compound-based deodorants, plant essential oils and synthetic fragrances. aromatic agents such as lavender essential oil, cedarwood essential oil, petitgrain essential oil, rosemary essential oil, rose ketones, ionones, allyl amyl glycolate, tripral, lyrial, citral, linalool, geraniol, acetylcedrene, methylnaphthyl ketone, and citral diethyl acetal, orange oil, α-pinene, d-limonene, β-caryophyllene, dihydromyrcenol, p-tert-butylcyclohexyl acetate, linalyl acetate, geranyl acetate, citronellyl acetate, galaxolide, and methyl atralate. mentioned.

Although the preferred embodiments of the present invention have been described above, the chemical dilution addition method of the present invention is not limited to the configuration of the above embodiments. In addition, the method of diluting and adding the chemical solution of the present invention can be appropriately modified according to conventionally known knowledge. Even with such modification, as long as it has the configuration of the chemical dilution addition method of the present invention, it is of course included in the scope of the present invention.

Examples of the present invention are shown below, but the present invention is not limited to these examples.

<Example 1>
An underwater agitator having a jet nozzle as shown in FIG. 2 is installed in a white water silo (capacity 50 m ³ ) and a recovered water tank (capacity 50 m ³ ) of a paper machine in a paper mill, and white water silo and recovered water are installed. A 0.2% by mass monochloramine aqueous solution obtained from a sodium hypochlorite solution and an ammonium chloride solution is used as a slime-preventing chemical solution from the chemical solution supply port to the pressurized liquid supply pipe in front of the jet nozzle while supplying the water stored in the tank. was added and supplied.
Using an underwater agitator (jet nozzle diameter 10 cm, jet nozzle discharge rate 60 L/min, discharge rate from the underwater agitator 180 L/min) so that the target addition concentration in the circulating water system is 10 mg/L as the combined residual chlorine concentration. The same amount of the slime-preventing chemical solution was continuously added to the white water silo and the recovered water tank.
The chemical added water in the white water silo and the recovered water tank was mixed with the above underwater agitator under the conditions of a jet nozzle discharge rate of 60 L/min and a discharge rate of 180 L/min from the submersible agitator, regardless of the presence or absence of chemical liquid supply from the pressurized liquid supply pipe. First, the water stored in the white water silo and the recovered water tank was supplied and continuously operated to circulate, while the diluted chemical-containing white water silo water and the recovered water tank water were supplied to the circulation water system.
15 minutes after supplying the diluted chemical solution, the number of bacteria in the solution was measured as follows using the test solution sampled from the white water silo and the recovered water tank. After allowing to stand for 30 seconds, the supernatant of the test solution was collected, and the general bacterial count was measured according to JIS K0101 (1998) 63.2.
Table 1 shows the results. The measured numbers of bacteria in the white water silo before the supply of the diluted chemical and the water in the recovery water tank to which the chemical was not added were 1.8×10 ⁸ /mL and 2.0× ^{10 8} /mL, respectively. there were.

<Example 2>
In the same white water silo and recovered water tank as in Example 1 of the paper machine in the same paper mill as in Example 1, a submersible stirring device having a jet nozzle as shown in FIG. An actual machine test was conducted in which water containing 10% by mass of sodium polyacrylate (weight average molecular weight: 8000) was supplied as a scale-preventing chemical solution from the chemical solution supply port to the pressurized liquid supply pipe in front of the jet nozzle while supplying water.
White water silo and white water silo by underwater stirring device (jet nozzle diameter 10 cm, jet nozzle discharge rate 60 L / min, discharge rate from underwater stirring device 180 L / min) so that the target addition concentration in the circulating water system maintains 5 mg / L as an active ingredient The same amount was continuously added to the recovered water tank.
Regardless of the presence or absence of chemical liquid supply to the pressurized liquid supply pipe, the above underwater agitator supplies the water stored in the white water silo and the recovered water tank, and the jet nozzle discharge rate is 60 L/min, and the discharge rate from the underwater agitator is 180 L/min. White water silo water containing diluted chemicals and recovered water tank water were supplied to the circulating water system while operating continuously under the conditions of 1 minute.
In order to confirm the effect, the inside of the inlet was inspected during regular maintenance.
Table 2 shows the results. The evaluation was carried out by visual inspection of the inlet, and was performed according to four grades of ⊚: no scale, ∘: fine scale seen, Δ: scale seen, and ×: scale clearly seen.

<Example 3>
In the paper machine in the same paper mill as in Example 1, in the same white water silo and recovered water tank as in Example 1, an underwater agitating device having a jet nozzle as shown in FIG. 2 was installed, and the white water silo and recovered water While supplying the water stored in the tank, a 0.2% by mass monochloramine aqueous solution obtained from a sodium hypochlorite solution and an ammonium chloride solution is supplied from the chemical supply port to the pressurized liquid supply pipe in front of the jet nozzle as a slime prevention chemical. An actual equipment test was conducted.
Using an underwater agitator (jet nozzle diameter 4 cm, jet nozzle discharge rate 60 L/min, discharge rate from the underwater agitator 180 L/min) so that the target addition concentration in the circulating water system is 10 mg / L as the combined residual chlorine concentration. Equal amounts of the slime-preventing chemicals were added to the white water silo and the recovered water tank.
While the chemical solution supply to the pressurized liquid supply pipe was stopped, the underwater agitator was stopped, and the white water silo water containing the diluted chemical solution and the recovered water tank water were supplied to the circulating water system.
15 minutes after supplying the diluted chemical solution, the number of bacteria in the solution was measured as follows using the test solution sampled from the white water silo and the recovered water tank. After allowing to stand for 30 seconds, the supernatant of the test solution was collected, and the general bacterial count was measured according to JIS K0101 (1998) 63.2.
Table 1 shows the results. The measured numbers of bacteria in the white water silo before the supply of the diluted chemical and the water in the recovery water tank to which the chemical was not added were 1.9×10 ⁸ /mL and 2.0× ^{10 8} /mL, respectively. there were.

<Example 4>
In the same recovered water tank as in Example 1 of the paper machine in the same paper mill as in Example 1, an underwater agitating device having a jet nozzle as shown in FIG. An actual machine test was conducted in which water containing 10% by mass of polysodium acrylate (weight average molecular weight: 8000) was supplied as a scale-preventing chemical solution from the chemical solution supply port to the pressurized liquid supply pipe on the front side.
To the recovered water tank with an underwater agitator (jet nozzle diameter 10 cm, jet nozzle discharge rate 60 L / min, discharge rate from the underwater agitator 180 L / min) so that the target addition concentration in the circulating water system is 5 mg / L as an active ingredient. added continuously.
The underwater agitator supplies the water stored in the recovered water tank under the conditions of a jet nozzle discharge rate of 60 L/min and a discharge rate of 180 L/min from the underwater agitator regardless of the presence or absence of chemical liquid supply to the pressurized liquid supply pipe. While operating continuously, the recovered water tank water containing the diluted chemical solution was supplied to the circulating water system.
In order to confirm the effect, the inside of the inlet was inspected during regular maintenance.
Table 2 shows the results.

<Comparative Example 1>
A propeller blade type stirring device was installed and operated (blade diameter / silo diameter = 0.2, rotation speed 100 rpm), a 0.2% by mass monochloramine aqueous solution obtained from a sodium hypochlorite solution and an ammonium chloride solution as a slime-preventing chemical solution is added to the circulating water system so that the target concentration is 10 mg / L as the effective total chlorine concentration. The water containing the dilute chemical solution was supplied to the circulating water system while continuously operating the impeller stirrer.
15 minutes after supplying the diluted chemical-containing water from the white water silo and the recovered water tank to the circulating water system, using the test liquid collected from the white water silo and the recovered water tank, measure the number of bacteria in the liquid as follows. did. After allowing to stand for 30 seconds, the supernatant of the test solution was collected, and the general bacterial count was measured according to JIS K0101 (1998) 63.2.
Table 1 shows the results. The measured numbers of bacteria in the white water silo before the supply of the diluted chemical and the water in the recovered water tank to which the chemical was not added were 1.8×10 ⁸ /mL and 2.3× ^{10 8} /mL, respectively. there were.

<Comparative Example 2>
A propeller blade type stirring device was installed at the bottom of the same recovered water tank as in Example 1 of the paper machine in the same paper mill as in Example 1, and operated (blade diameter / tank diameter = 0.2, rotation speed 100 rpm). Water containing 10% by mass of sodium polyacrylate (mass average molecular weight: 8000) was continuously added as a scale-preventing chemical so that the target addition concentration in the circulating water system was 5 mg/L as the active ingredient, and the blade-type agitator was operated. The water containing the diluted chemical solution was supplied to the circulating water system while the water was being heated.
In order to confirm the effect, the inside of the inlet was inspected during regular maintenance.
Table 2 shows the results.

From the comparison of the slime inhibitor tests of Example 1, Example 3 and Comparative Example 1 in the data of Table 1, and the scale inhibitor test of Example 2, Example 4 and Comparative Example 2 in the data of Table 2, It can be seen that Examples 1 to 4 of the present invention are superior to Comparative Examples 1 and 2 in terms of drug effect, and that Examples 1 and 2 are particularly superior.

A Papermaking process A1 Raw material adjustment system A2 White water circulation system A3 White water recovery system S Underwater stirring device 1 Raw material adjustment tank 2 Machine chest 3 Pump 4 Pump 5 White water silo 6 Inlet 7 Wire part 7a Wire 8 Press part 9 Seal pit 10 Pump 11 Solid Liquid separator 12 Recovered water tank 13 Pump 14 Cushion tank 15 Water line 16 Pump 20 Hollow pipe 20a Negative pressure 21 Jet nozzle 21a Jet water stream 22 Pressurized liquid supply pipe 22a Chemical solution supply pipe 22b Chemical solution 22c Chemical solution supply port 23 Diluted chemical solution Discharge portion 23a Diluted chemical liquid 24 Suction hole 24a Suctioned and stored water 25 Process water 25a Circulating water and/or inflow water 26 Pressurized aqueous liquid 27 Water storage portion 27a Storage water

Claims (3)

A paper manufacturing process comprising one or more water reservoirs for retaining the circulating water of a circulating water system or the influent water of an influent water flowing into the circulating water system,
A method for diluting and adding a chemical liquid using an underwater agitating device installed in at least one portion of the water reservoir of the water reservoir,
The underwater stirring device
a hollow tube having a suction hole at least in its wall surface;
a pressurized liquid supply pipe that adds a chemical solution to the process water containing the circulating water or the influent water and pressurizes it to produce a pressurized aqueous liquid;
a jet nozzle for injecting the pressurized aqueous liquid into the hollow tube as jet water;
comprising a diluent liquid discharge part connected to the hollow tube,
By injecting the jet stream water, a negative pressure is generated in the hollow tube, and the stored water is sucked into the hollow tube as suction stored water from the suction hole, and the jet stream water and the suctioned stored water are mixed. A method for diluting and adding a chemical solution, wherein the diluted chemical solution is discharged from the diluted chemical solution discharge part into the pooled water of the water storage part in which the underwater stirring device is installed. After supplying a predetermined amount of the chemical solution to the process water, the stored water containing the diluted chemical solution in the water reservoir is supplied as the process water to the pressurized liquid supply pipe, and the jet nozzle flows the jet water. is continued for a predetermined time,
2. The method for diluting and adding a chemical solution according to claim 1, wherein the chemical solution is dispersed by passing the stored water through the underwater agitator and circulating it in the water reservoir. 3. The chemical solution according to claim 1 or 2, wherein the chemical solution is a liquid containing at least one of a slime control agent, a scale inhibitor, an antirust agent, an antifoaming agent, and a deodorant. Dilution addition method.

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