JP7064267B2 - How to add chemicals - Google Patents

Description

The present invention relates to a method for adding a bactericidal chemical solution to a circulating water system or a water system flowing into the circulating water system in a papermaking process, and particularly relates to an addition method in which the amount of the chemical solution added is small even in a chemical solution that easily generates gas.

If slime is generated in the circulating water system or added water system due to bacteria in the paper making process, the quality of paper pieces and paper products during manufacturing will deteriorate. It is intermittently added to the water system to prevent slime (Patent Document 1).

However, bound halogen compounds such as monochloramine are unstable substances and decompose within a few hours after preparation. Therefore, bound halogen compounds are generated in a paper mill and immediately added to water-based water in the papermaking process. do.

The chemical solution addition device used at this time is usually a hypohalite line equipped with a liquid feed pump for feeding a hypophosphite aqueous solution, and a compound selected from ammonium salts, amines, amides, and imides. It has a nitrogen-containing basics line equipped with a liquid feed pump that feeds the aqueous solution of It has a process, and is usually equipped with a control mechanism that adjusts the discharge amount and discharge time per unit time of those liquid feed pumps and the amount of diluted water, and a control mechanism that stops the liquid feed when an abnormality occurs. There is.

The chemical solution tank of the hypohydrogenate aqueous solution or the nitrogen-containing base aqueous solution is connected to the liquid feed pump in the chemical solution addition device by a hose, a pipe, etc. A specific amount of the chemical solution is injected into the pipe through which the diluted water flows to generate a bound halogen compound and supply it to the circulating water to be added or the aqueous system flowing into the circulating water.

Bubbles due to the gas generated by the decomposition of hypohalite are generated in these chemicals, especially the hypohalite aqueous solution, with the passage of time, and the hypohalite aqueous solution containing bubbles generates a liquid feed pump. The amount of hypohalite discharged from hypohalite per unit time decreases, the amount required for the synthesis of a predetermined bound halogen compound is no longer sent, and the ratio of hypohalite to nitrogen-containing bases changes. Therefore, the type and amount of bound halogen compound produced will change. Furthermore, the gas lock of the liquid feed pump, that is, the inability to feed the liquid due to the stop of the pump will be caused.

Therefore, gas lock measures are installed on the upstream side of the liquid feed pump to install a gas chamber open to the atmosphere to remove air bubbles generated on the upstream side of the liquid feed pump in the chemical liquid addition device, which normally tends to generate air bubbles. Is taken.

However, it is not possible to remove the air bubbles generated in the piping from the gas chamber to the suction port of the liquid feed pump, and the air bubbles in this piping part require regular manual removal work, so improvement is required. Was there.

In order to solve such a problem, Patent Document 2 proposes a technique of feeding a fluid in which gas is likely to be generated by increasing the amount of liquid to be fed when the pump is started or when the discharge pressure is lowered. There is. However, such a method cannot be used for feeding a hypohalite aqueous solution, which requires a quantitative feeding.

Further, Patent Document 3 proposes a technique in which a flow detector and a bubble bleeding solenoid valve are provided in a liquid feed pipe, a liquid flow stop is detected, the bubble bleeding solenoid valve is opened, and air is bleeding. ing. However, with this technique, not only air bubbles but also a small amount of chemical solution is lost, and it is necessary to treat the chemical solution mixed in the wastewater.

In Patent Document 4, a pump detection means that detects a driving state of a pump body and a discharge state of a fluid and outputs a signal, and a pump detection means installed in a piping system on the discharge port side of the pump head of the pump body and detecting a fluid flow. It is equipped with a flow checker (flow meter) that outputs a signal, and an air bleeding solenoid valve installed in the piping system between the upstream side of this flow checker and the downstream side of the discharge port of the pump head, and detects the pump. A technique for automatically opening and closing the air bleeding solenoid valve by comparing the output signal by the means and the output signal by the flow checker is described. However, as in Patent Document 2, a small amount of chemical solution is lost when the air is bleeding.

Further, in Patent Document 5, an air detecting means for detecting air in a chemical solution flowing through a chemical solution supply line and a liquid feeding mode by the chemical solution supply means when the air detecting means detects air in the chemical solution are supplied. A technique is described in which a control means for operating a chemical liquid supply means by setting an air discharge operation mode for discharging air from a line is provided. However, as in Patent Documents 2 and 4, in the air discharge operation mode, the chemical solution is lost and wastewater treatment is required, and the hypohalite cannot be used for hypohalites that require continuous quantitative delivery.

Republished 2014/030751 Gazette Patent Publication No. 2012-207571 Publication of Patent No. 2001-207972 Patent Publication No. H05-60061 Patent Publication No. 2011-173039

The present invention solves the above-mentioned problems of the prior art, that is, a method for adding a slime-preventing chemical solution to a circulating water system in a papermaking process, in which stable operation of the pump is maintained and added even with a chemical solution that easily generates gas. An object of the present invention is to provide an addition method with a small amount of fluctuation.

In order to solve the above problems, the present invention
(1)
A method of adding a chemical solution to a circulating water system in the papermaking process.
With the first drug solution delivery pump for feeding the first drug solution containing the hypohalogenate compound to the circulating water system or the diluted water line that supplies the diluted water to the water system flowing into the circulating water system, and the hypohalogenate compound. It is equipped with a second drug solution delivery pump that feeds a second drug solution containing a bound halogen-generating compound that produces a bound halogen compound by reacting.
A method for adding a chemical solution, which comprises increasing the discharge amount per unit time of at least the first chemical solution delivery pump from the initial value at each operation for a certain period of time and maintaining the discharge amount for a predetermined time.
(2)
2. Addition method.
(3)
It is characterized in that at least the discharge amount per unit time of the first chemical liquid feed pump is increased from the initial value at each operation for a certain period of time and maintained for 20 seconds or more and 3 minutes or less (1) or (. The method for adding a chemical solution according to 2).
(4)
It is characterized in that the discharge amount per unit time of the first chemical liquid feed pump and the second chemical liquid feed pump is increased from the initial value at almost the same time at each operation for a certain period of time and maintained for a predetermined time (1). ) To (3). The method for adding the chemical solution.
(5)
A method of adding a chemical solution to a circulating water system in the papermaking process.
With the first drug solution delivery pump for feeding the first drug solution containing the hypohalogenate compound to the circulating water system or the diluted water line that supplies the diluted water to the water system flowing into the circulating water system, and the hypohalogenate compound. It is equipped with a second drug solution delivery pump that feeds a second drug solution containing a bound halogen-generating compound that produces a bound halogen compound by reacting.
In at least one of the first chemical delivery pump and the second chemical delivery pump,
When the measured value of the discharge amount per unit time is lower than the predetermined value determined in advance from the initial operation value, at least the reduced discharge amount per unit time of the liquid feed pump is increased from the initial operation value and specified. Keep time or
Alternatively, when the pH of the water system in the diluted water line after the first and second chemicals are added drops below a predetermined value, at least the discharge amount per unit time of the first chemical feed pump is increased. A method for adding a chemical solution, which comprises increasing the value from the initial value of operation and maintaining the value for a predetermined time.
(6)
When the measured value of the discharge amount per unit time of at least one of the first chemical liquid feed pump and the second chemical liquid feed pump is 10% or more lower than the initial operation value, at least the unit of the reduced liquid feed pump. Whether to increase the discharge rate per hour from the initial value of operation and maintain it for a predetermined time
Alternatively, when the pH of the water system in the diluted water line after the first and second chemicals are added drops by 0.3 or more from the initial operating value, at least the discharge amount per unit time of the first chemical feed pump. The method for adding a chemical solution according to (5), wherein the amount is increased from the initial value of operation and maintained for a predetermined time.
(7)
In at least one of the first chemical delivery pump and the second chemical delivery pump,
When the measured value of the discharge flow meter drops by a predetermined value or more that is predetermined from the initial operating value, at least the reduced discharge amount per unit time of the liquid feed pump is increased by 20% or more from the initial operating value and specified. Keep time or
When the pH of the water system in the diluted water line after the first and second chemicals are added drops by a predetermined value or more from the initial value, at least the discharge per unit time of the first chemical feed pump The method for adding a chemical solution according to (5) or (6), wherein the amount is increased by 20% or more from the initial value of operation and maintained for a predetermined time.
(8)
In at least one of the first chemical delivery pump and the second chemical delivery pump,
When at least one of the measured values of the discharge flow meter is lower than the initial operation value by a predetermined value or more.
Or, when the pH of the aqueous system in the diluted water line after the addition of the first chemical solution and the second chemical solution is lower than the initial value by a predetermined value or more.
Any of (5) to (7), wherein the discharge amount per unit time of the first chemical liquid feed pump and the second chemical liquid feed pump is increased from the initial value at the same time and maintained for a predetermined time. Method of adding chemical solution described in Crab.
(9)
In at least one of the first chemical delivery pump and the second chemical delivery pump,
When the measured value of the discharge flow meter drops by a predetermined value or more that is predetermined from the initial operating value, at least the discharged amount per unit time of the reduced liquid feed pump is increased from the initial operating value for 20 seconds or more. Keep within minutes or
Alternatively, when the pH of the water system in the diluted water line after the first and second chemicals are added drops by a predetermined value or more from the initial operating initial value, at least the unit of the first chemical feed pump. The method for adding a chemical solution according to any one of (5) to (8), wherein the discharge amount per hour is increased from the initial value of operation and maintained within 20 seconds or more and 3 minutes or less.
(10)
The method for adding a drug solution according to any one of (1) to (9), wherein at least one of the first drug solution feed pump and the second drug solution feed pump is a pulsation-free metering pump.
(11)
The hypohaloic acid compound is
It is characterized by being one or more selected from sodium hypochlorite, calcium hypochlorite, potassium hypochlorite, sodium hypobromous acid and potassium hypobromous acid (1). ) To (10). The method for adding the chemical solution.
(12)
The bonded halogen-producing compound is
It is characterized by being one or more selected from ammonium chloride, ammonium sulfate, ammonium bromide, ammonia, sulfamic acid or a salt thereof, urea, a hydantoin compound, glycine, threonine, lysine, glutamate and taurine. The method for adding a chemical solution according to any one of (1) to (11).

By the method of adding the anti-slime chemical solution in the papermaking process of the present invention, the formation of the bound halogen compound caused by the decrease in the amount of the chemical solution discharged from the pump per unit time due to the bubbles generated in the chemical solution used for producing the bound halogen compound. It is possible to effectively prevent a decrease in the amount, a change in the type of bound halogen compound produced, and air lock of the pump, and stable production of the targeted bound halogen compound and a liquid feed pump without wasting the chemical solution. Stable operation is possible.

It is a model figure which shows the chemical liquid addition apparatus used in the chemical solution addition method of this invention. It is the discharge amount data of the fresh water, the first chemical liquid and the second chemical liquid delivery pump in Example 1 of this invention. It is the time-dependent data of the pH value after the merge of fresh water, the first chemical solution and the second chemical solution in Example 1 of this invention.

Hereinafter, an example of the present invention will be described with reference to FIG.
<Chemical solution addition device>
FIG. 1 is a model diagram showing an example of the chemical solution adding device of the present invention, and the first chemical solution M1 of the chemical solution adding device is an aqueous solution of a hypohalogenate compound. The second chemical solution M2 is a bound halogen-producing compound that produces a bound halogen compound by reacting with the hypohalogenate compound.

The first chemical solution pump 8 is connected to the first chemical solution delivery pipe connected to the first chemical solution tank 2 in which the first chemical solution M1 is housed, but the chemical resistance to the first chemical solution M1 is improved. It is necessary to have a pump that has excellent quantification and can control the start / stop of liquid feeding and the liquid feeding speed by a device control means (not shown). Further, as a type of pump, for example, a diagram pump can be mentioned, but any pump may be used as long as it satisfies the above requirements.
Here, by using a pump with less pulsation during liquid feeding, for example, a pulsation-free metering pump, the addition ratio of the first chemical solution M1 and the second chemical solution M2 is less likely to fluctuate, and a stable target bound halogen compound can be obtained. It is preferable because it can be used. However, in general, there is a problem that bubbles generated in the chemical solution are easily stabilized because the amount of the chemical solution discharged is reduced and the stroke cycle is lengthened in order to reduce the pulsation.
The method of adding the chemical solution of the present invention solves this problem. In this example, a diagram pump is used as the first chemical liquid feeding pump 8 and the second chemical liquid feeding pump 9 described later.

The first chemical solution M1 is sodium hypochlorite, calcium hypochlorite, potassium hypochlorite, sodium hypobromous acid and hypobromous acid, which are hypochlorous acid compounds used as the first chemical solution of the present invention. One or more selected from potassium bromine and the like is used.

In the diluted water water supply pipe 1, in addition to the first chemical liquid supply pipe, the second chemical liquid supply pipe connected to the second chemical liquid tank 3 in which the second chemical liquid M2 is housed is connected to the second chemical liquid supply pipe via the second chemical liquid confluence portion 14. It is connected. A second chemical liquid feeding pump 9, a flow meter, and a check valve are connected to the second chemical liquid feeding pipe in the order of the liquid feeding direction of the second chemical liquid M2. In this example, the second chemical liquid merging portion 14 is provided on the downstream side in the diluted water flow direction of the first chemical liquid merging portion 13, but even if it is provided on the upstream side in the same direction of the first chemical liquid merging portion 13. good.

The second chemical solution M2 is a water-soluble inorganic ammonium salt such as ammonium chloride, ammonium sulfate, or ammonium bromide, which is a bound halogen-producing compound used as the second chemical solution of the present invention, ammonia, sulfamic acid or a salt thereof, urea, and the like. One or more selected from hydridein compounds, glycine, threonine, lysine, glutamic acid, taurine, etc. are used, but inorganic ammonium salts such as ammonium chloride, ammonium sulfate, ammonium bromide, etc. are used due to cost, workability, etc. It is preferably used.

As a preferable example of installing a mixing chamber in the diluted water supply pipe 1, the diluted water supply pump 7, the diluted water flow meter, the first chemical solution merging section 13, the mixing chamber 4, and the second chemical solution merging in the order of the diluted water flow direction. Part 14, the mixing chamber 5, and the pH meter 6 are connected, and the tip of the pH meter 6 installed after the first chemical solution M1 and the second chemical solution M2 are merged and mixed with the diluted water in the flow direction downstream of the diluted water. Therefore, the diluted water containing the bound halogen compound produced by this chemical solution adding device is added to the aqueous system to which the bound halogen compound is added.

In the mixing chamber 4 and the mixing chamber 5, preferably, the reaction between the component of the first chemical solution M1 and the component of the second chemical solution M2 is promoted by promoting the mixing of the diluted water and the chemical solution added to the diluted water. A device for efficiently producing the desired bound halogen compound is preferably used. In this example, a static mixer is installed, and the bound halogen compound is stably produced even though it is non-powered.

The ratio of the addition amount of the second drug solution to the first drug solution of the present invention is preferably a product when the substituted halogen per molecule of the bound halogen compound is 1, for example, monochloroamine from the viewpoint of toxicity, irritation, stability and the like. , The molar equivalent is generally 0.8 to 2.0, but more preferably 1.0 to 1.5.
The preferable range of the added molar ratio of the first chemical solution and the second chemical solution at the time of producing the bound halogen compound is set by the discharge amount per unit time of the first chemical solution feed pump and the second chemical solution feed pump during normal operation. In addition to the case where the pump operation has elapsed for a certain period of time, the discharge flow rate of the pump drops by a predetermined value or more from the initial value, or the pH of the diluted water system after the addition of the first chemical solution and the second chemical solution drops by a predetermined value or more. Even when the discharge amount per unit time of both pumps is increased substantially at the same time, it is preferable to keep it within the range of this molar ratio.

When the pH detected by the pH meter 6 after mixing the first chemical solution and the second chemical solution is lower than the initial value by a predetermined value or more, it is generally 0.3 or more, preferably 0.2 or more. In this case, at least the discharge amount per unit time of the first chemical solution feed pump 8 is increased by a device control means (not shown) and maintained for a predetermined time, preferably 20% or more, more preferably 30% or more from the initial value. As a result, the gas contained in the chemical solution can be forcibly removed.
More preferably, the discharge amount per unit time of the second chemical liquid feed pump 9 is also increased by a predetermined time from the initial value almost at the same time as the first chemical liquid feed pump 8, particularly 20% or more, more preferably 30% or more. This will forcibly remove the gas contained in the chemical solution, further suppress the fluctuation in the pH of the diluted water after mixing the two chemical solutions, and stabilize the ratio of the target bound halogen product to a high level.
Here, when the discharge amount per unit time is increased and maintained for a predetermined time, the upper limit of the predetermined time is usually 5 minutes, preferably 3 minutes, and the lower limit is 10 seconds, preferably 20 seconds.
If the stroke amount or the rotation speed is increased for too long, the amount of the bonded halogen compound produced in a unit time increases for a long time, so that the amount added to the diluted water increases significantly, resulting in an increase in cost. Further, when the discharge amount of the chemical solution increases, the uniform mixing of the two chemical solutions decreases and the production ratio of the target bound halogen compound decreases, so that it is not preferable that the time for increasing the discharge amount becomes too long.
On the contrary, if the time for increasing the discharge amount is too short, the discharge of the chemical solution containing air bubbles becomes insufficient, and it is necessary to take measures to increase the stroke amount or the rotation speed again in a short time.

The first chemical liquid feeding pump 8 and the second chemical liquid feeding pump 9 used in the present invention control the discharge amount of the first chemical liquid M1 and the second chemical liquid M2 per unit time by the stroke amount or the rotation speed.
Here, if the discharge amount is low, gas lock is likely to occur. On the other hand, if it is too high, the gas lock prevention effect is hardly improved, the price of the chemical liquid feeding pump becomes high, and the equipment cost of the chemical liquid feeding device rises.
In order to sufficiently exert the gas lock prevention effect of the present invention, it is preferable to keep the inner diameter of the section of the first chemical liquid feeding pipe constant. The discharge amount in the present invention means the discharge amount of the liquid per unit time.

As described above, this chemical solution adding device includes a device control device (not shown) for controlling the chemical solution adding device of FIG. 1. The device control means is from a device necessary for controlling this chemical addition device, such as a CPU, a RAM and ROM for holding programs and various data (a storage device such as a rewritable flash memory may be used), a timekeeping timer, and an interface. It is configured.

In addition to this device control means, the device control means includes LEDs, buttons, keyboards, etc. necessary for inputting and rewriting data necessary for device control, and a warning when an abnormality occurs in the pH meter 6. It is equipped with a buzzer, lamp, communication means, etc.

Next, another example of the present invention will be described with reference to FIG.

Instead of the measurement with the pH meter 6 in FIG. 1, the measurement of at least one of the first chemical liquid and the second chemical liquid discharge flow meter 10 and 11 provided in the first chemical liquid feed pump 8 and the second chemical liquid feed pump 9 When the measured value of the meter is lower than the initial value by a predetermined value or more, generally 20% or more, preferably 10% or more, at least the reduced discharge amount per unit time of the pump. By increasing, preferably 20% or more, more preferably 30% or more, the discharge amount per unit time of the first and second chemical liquid feeding pumps 8 and 9 is increased from the initial value at almost the same time, and for a predetermined time. It is desirable to maintain, preferably 20% or more, more preferably 30% or more.
Here, when the stroke amount or the number of revolutions is increased and maintained for a predetermined time, the upper limit of the predetermined time is usually 5 minutes, preferably 3 minutes, and the lower limit is 10 seconds, preferably 20 seconds.
If the time to increase the discharge amount per unit time is too long, the amount of bound halogen compound produced in the unit time increases, so the amount added to the diluted water increases excessively, or the first and second chemical solutions are mixed. Is not preferable because the production ratio of the target bonded halogen compound is lowered due to insufficient production. On the contrary, if the predetermined time is too short, the discharge of the first and second chemical solutions containing bubbles becomes insufficient.
The discharge flow meter used in the chemical solution addition method of the present invention is not particularly limited, but discharges per unit time of the liquid feed pump when the flow rate per unit time drops by a predetermined value or more predetermined from the initial value of operation. The discharge flow meter used in the method of increasing the amount from the initial value of operation can be used as long as the measured value decreases if the liquid to be measured contains air bubbles, and a mass flow meter is preferable, particularly Koriori. A type flow meter is preferred.

Examples of the present invention are shown below, but the present invention is not limited to this embodiment.

<Pre-water process>
In the example of FIG. 1, the chemical solution addition device intermittently generates a bound halogen compound and adds it to the water system to be added, for example, the water in the papermaking process of a papermaking factory. Diluted water is constantly supplied to 1. In this pre-watering step, the first chemical liquid feed pump 8 and the second chemical liquid feed pump 9 are stopped.

During the pre-watering process, when the value of the timing timer of the device control device approaches the timing for performing the drug injection step, the device control means starts the chemical solution addition step. A 12% by mass aqueous solution of hypochlorite sodium was used as the first chemical solution M1, and a 12% by mass aqueous solution of ammonium chloride was used as the second chemical solution M2.

<Chemical solution addition process>
When the value of the timing timer reaches the timing of starting the chemical solution addition process, the apparatus control means operates the first chemical solution delivery pump 8 and the second chemical solution delivery pump 9 to start the chemical solution addition step.

As a result, the first chemical solution M1 and the second chemical solution M2 are sent to the diluted water supply pipe 1 and join the diluted water.

In this chemical addition step, the above-mentioned device control means is a first chemical liquid feeding pump under predetermined liquid feeding conditions so that a target-bonded halogen compound (for example, monochloroamine) having a predetermined concentration is produced in the diluted water. 8 and the second chemical solution feeding pump 9 are operated to send the first chemical solution M1 and the second chemical solution M2 to the diluted water supply pipe 1.

The diluted water in the diluted water supply pipe 1 is mixed with the first chemical solution M1 supplied from the first chemical solution merging portion in the mixing chamber 4, and further, the second chemical solution M2 supplied from the second chemical solution merging section and the mixing chamber 5 are mixed. It is mixed within and added to the water system to be supplied together with the bound halogen compound (for example, monochloramine) produced by the components of these chemicals.

(Example 1)
In the example using the chemical solution addition device shown in FIG. 1, the discharge flowmeters (FD-SF manufactured by Keyence) of the first chemical solution feed pump 8 (FXD1 manufactured by Takumina) and the second chemical solution feed pump 9 (BPL manufactured by Takumina) are used. ) The discharge amount measured by 10 and 11 is increased once every 30 minutes, and at the same time, from the initial values of 0.76 L / min and 0.41 L / min to 1.24 L / min and 0.78 L / min, respectively. After maintaining for 1 minute and 30 seconds, the process of operating the first chemical feed pump 8 and the second chemical feed pump 9 again at the initial discharge rate is completed by adding the predetermined amount of the chemical solution scheduled by the device control means. Repeated until.
FIG. 2 shows time-dependent data on the amount of fresh water added, sodium hypochlorite which is the first chemical solution M1, and ammonium chloride which is the second chemical solution M2, and FIG. 3 shows diluted water after adding the first chemical solution and the second chemical solution. The time-dependent data of the pH value is shown.

(Example 2)
In the same example of using the same chemical solution addition device as in Example 1 and using the same first chemical solution feed pump 8 and second chemical solution feed pump 9, after adding the first chemical solution and the second chemical solution measured by the pH meter 6. The pH of the diluted water dropped from 9.2 immediately after operating the first chemical feed pump 8 and the second chemical feed pump 9 to 8.8 40 minutes later, so that the first chemical feed pump 8 was used. The discharge amounts measured by the discharge flow meters (FD-SF manufactured by Keyence Co., Ltd.) 10 and 11 of the second chemical liquid feed pump 9 are the initial values of 0.76 L / min, 0.41 L / min to 1.24 L / min, and 0, respectively. It was increased to .78 L / min and maintained for 1 minute and 30 seconds. After that, the first chemical liquid feed pump 8 and the second chemical liquid feed pump 9 were operated again at the initial discharge amount.
As described above, when the pH of the diluted water dropped to 8.8, the step of increasing the discharge amount of each pump for 1 minute and 30 seconds was repeated until the predetermined amount of the chemical solution planned by the apparatus control means was added.

(Example 3)
In the example of the chemical solution addition device of FIG. 1 using the same first chemical solution feed pump 8 and second chemical solution feed pump 9 as in Example 1, instead of the measurement of the pH meter 6 of Example 1 and Example 2. The discharge amount measured by the first chemical solution and the second chemical solution discharge flowmeters 10 and 11 (here, FD-SF manufactured by Keyence Co., Ltd.) is measured, and the first chemical solution delivery pump 8 and the second chemical solution delivery pump are used. The operation was started at 0.76 L / min and 0.41 L / min, respectively, and after 35 minutes, the discharge rate of the first liquid feed pump decreased by 20% to 0.61 L / min, so the first chemical feed was fed. The discharge amounts of the liquid pump 8 and the second chemical liquid feed pump 9 were increased from the initial values of 0.76 L / min and 0.41 L / min to 1.24 L / min and 0.78 L / min, respectively, and maintained for 2 minutes. After that, the first chemical liquid feed pump 8 and the second chemical liquid feed pump 9 were operated again at the initial discharge amount.
When the discharge amount of any of the first and second chemical liquid delivery pumps 8 and 9 decreases by 20%, the step of increasing the pump discharge amount for 2 minutes is continued until the addition of the predetermined amount of chemical liquid scheduled by the device control means is completed. Repeated.

(Examples 4 to 6)
Example 4 in the same manner except that a pulsation-free metering pump (BPL manufactured by TACMINA Corporation) was used in place of the first drug solution feed pump 8 and the second drug solution feed pump 9 used in Examples 1 to 3. Example 6 was carried out from.

<After water process>
When the value of the above-mentioned timing timer reaches the timing of stopping the chemical solution addition process, the device control means stops the first chemical solution delivery pump 8 and the second chemical solution delivery pump 9 until the timing of starting the next chemical solution addition process. stand by. After this, in the water step, the chemical solution remaining in the diluted water supply pipe 1 is removed by the continuously supplied diluted water.

As described above, as a result of operating the paper manufacturing process for 24 hours in the example of the present invention, in Examples 1 and 2 of the present invention, the first chemical liquid feed pump 8 and the second chemical liquid feed pump 9 are stopped by the air lock. It did not occur, and there were no problems caused by slime in the papermaking process, and it operated smoothly.

(Comparative Example 1)
As Comparative Example 1, in the apparatus of FIG. 1, the chemical solution addition device is continuously operated by using the first chemical solution delivery pump 8 and the second chemical solution delivery pump 9 of the first chemical solution and the second chemical solution as in Example 1. As a result, the pH of the diluted water after adding the first and second chemicals dropped from the initial value of 9.3 to 8.3 after 1 hour of operation, and the pH of the diluted water after 1 hour and 30 minutes of operation. When the pH dropped to 8.0, an air lock occurred and the first chemical feed pump 8 stopped.

(Comparative Example 2)
As Comparative Example 2, a pulsation-free metering pump (BPL manufactured by Takumina Co., Ltd.) was used as the first drug solution feed pump 8 and the second drug solution feed pump 9 of the same first and second chemicals as in Example 4 in the apparatus of FIG. When the chemical solution addition device was continuously operated using the solution, the pH of the diluted water after adding the first chemical solution and the second chemical solution dropped from the initial value of 9.3 to 8.3 after 50 minutes of operation, and further. After 1 hour and 10 minutes of operation, when the pH of the diluted water dropped to 8.1, an air lock occurred and the first chemical feed pump 8 stopped.

In Comparative Example 1 and Comparative Example 2, the discharge amount of the first chemical solution per unit time decreased with time from the result of the change in the discharge amount of the first chemical solution feed pump 8 and the second chemical solution feed pump 9 with time. On the other hand, since the discharge amount of the second chemical solution per unit time has remained almost constant, the amount ratio of the first and second chemical solutions at the time of mixing has changed. From the fact that the pH value of the diluted water after mixing with the second chemical solution changes, it is inferred that the production ratio of the target bound halogen compound decreases and the composition of the produced compound changes over time.

(Comparative Example 3)
As Comparative Example 3, the chemical solution addition device is continuously operated by using the first chemical solution feed pump 8 and the second chemical solution feed pump 9 of the first chemical solution and the second chemical solution as in Example 3 in the apparatus of FIG. rice field. When the discharge amounts of the first chemical liquid feed pump 8 and the second chemical liquid feed pump 9 after starting the addition of the first chemical liquid and the second chemical liquid were measured, one hour later, the unit time of the first liquid feed pump was measured. The discharge amount was 30% lower than the initial value, and air lock occurred in the first chemical liquid feed pump 8 after 1 hour and 40 minutes of operation. It is presumed that the production ratio of the target bonded halogen compound decreases and the type of the produced compound changes with time.

As described above, the good operation is continued according to Examples 1 to 6 of the present invention, whereas the bound halogen compound produced by Comparative Example 1 to Comparative Example 3 is the production of the initially targeted compound. It is inferred that the ratio has decreased and the type of produced compound has changed. Furthermore, it can be seen that the operation is likely to be interrupted by the airlock of the pump.

1 Diluted water feed pipe 2 1st chemical tank 3 2nd chemical tank 4 Mixing chamber 5 Mixing chamber 6 pH meter 7 Diluted water feed pump 8 1st chemical feed pump 9 2nd chemical feed pump 10 1st chemical discharge flow meter 11 Second chemical discharge flow meter 12 Diluted water flow meter 13 First chemical merging section 14 Second chemical merging section

Claims (9)

A method of adding a chemical solution to a circulating water system in the papermaking process.
With the first chemical solution delivery pump for feeding the first chemical solution containing the hypohalous acid compound to the circulating water system or the diluted water line for supplying the diluted water to the water system flowing into the circulating water system, and the hypohalous acid compound. From among ammonium chloride, ammonium sulfate, ammonium bromide, ammonia, sulfamic acid or a salt thereof, urea, hydantin compound, glycine, threonine, lysine, glutamic acid and taurine as the bound halogen producing compound which produces the bound halogen compound by reaction. It is equipped with a secondary chemical delivery pump that delivers a secondary chemical containing one or more selected compounds.
A chemical solution characterized in that the discharge amount per unit time of the first chemical solution delivery pump and the second chemical solution delivery pump is increased from the initial value at almost the same time at each operation for a certain period of time and maintained for a predetermined time . Addition method. A method of adding a chemical solution to a circulating water system in the papermaking process.
With the first chemical solution delivery pump for feeding the first chemical solution containing the hypohalous acid compound to the circulating water system or the diluted water line for supplying the diluted water to the water system flowing into the circulating water system, and the hypohalous acid compound. From among ammonium chloride, ammonium sulfate, ammonium bromide, ammonia, sulfamic acid or a salt thereof, urea, hydantin compound, glycine, threonine, lysine, glutamic acid and taurine as the bound halogen producing compound which produces the bound halogen compound by reaction. It is equipped with a secondary chemical delivery pump that delivers a secondary chemical containing one or more selected compounds.
In at least one of the first chemical delivery pump and the second chemical delivery pump,
When the measured value of the discharge amount per unit time is lower than the predetermined value determined in advance from the initial operation value, at least the reduced discharge amount per unit time of the liquid feed pump is increased from the initial operation value and specified. Keep time or
Alternatively, when the pH of the water system in the diluted water line after the first and second chemicals are added drops below a predetermined value, at least the discharge amount per unit time of the first chemical feed pump is increased. A method for adding a chemical solution, which comprises increasing the value from the initial value of operation and maintaining the value for a predetermined time. When the measured value of the discharge amount per unit time of at least one of the first chemical liquid feed pump and the second chemical liquid feed pump is 10% or more lower than the initial operation value, at least the unit of the reduced liquid feed pump. Whether to increase the discharge rate per hour from the initial value of operation and maintain it for a predetermined time
Alternatively, when the pH of the water system in the diluted water line after the first and second chemicals are added drops by 0.3 or more from the initial operating value, at least the discharge amount per unit time of the first chemical feed pump. The method for adding a chemical solution according to claim 2 , wherein the amount is increased from the initial value of operation and maintained for a predetermined time. In at least one of the first chemical delivery pump and the second chemical delivery pump,
When the measured value of the discharge flow meter drops by a predetermined value or more that is predetermined from the initial operating value, at least the reduced discharge amount per unit time of the liquid feed pump is increased by 20% or more from the initial operating value and specified. Keep time or
When the pH of the water system in the diluted water line after the first and second chemicals are added drops by a predetermined value or more from the initial value, at least the discharge per unit time of the first chemical feed pump The method for adding a chemical solution according to claim 2 or 3 , wherein the amount is increased by 20% or more from the initial value of operation and maintained for a predetermined time. In at least one of the first chemical delivery pump and the second chemical delivery pump,
When at least one of the measured values of the discharge flow meter is lower than the initial operation value by a predetermined value or more.
Or, when the pH of the aqueous system in the diluted water line after the addition of the first chemical solution and the second chemical solution is lower than the initial value by a predetermined value or more.
Any of claims 2 to 4 , wherein the discharge amount per unit time of the first chemical liquid feed pump and the second chemical liquid feed pump is increased from the initial value at the same time and maintained for a predetermined time. The method for adding a chemical solution according to item 1. In at least one of the first chemical delivery pump and the second chemical delivery pump,
When the measured value of the discharge flow meter drops by a predetermined value or more that is predetermined from the initial operating value, at least the discharged amount per unit time of the reduced liquid feed pump is increased from the initial operating value for 20 seconds or more. Keep within minutes or
Alternatively, when the pH of the water system in the diluted water line after the first and second chemicals are added drops by a predetermined value or more from the initial operating initial value, at least the unit of the first chemical feed pump. The method for adding a chemical solution according to any one of claims 2 to 5 , wherein the discharge amount per hour is increased from the initial value of operation and maintained within 20 seconds or more and 3 minutes or less. The method for adding a chemical solution according to any one of claims 1 to 6 , wherein at least one of the first chemical solution feeding pump and the second chemical solution feeding pump is a pulsation-free metering pump. The hypohaloic acid compound is
Claimed to be one or more selected from sodium hypochlorite, calcium hypochlorite, potassium hypochlorite, sodium hypobromite and potassium hypobromite. The method for adding a chemical solution according to any one of claims 1 to 7 . The method for adding a chemical solution according to any one of claims 1 to 8, wherein the bound halogen compound is monochrome lamin.

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