pH measuring device

Abstract

To provide a pH measurement device which can stably perform pH measurement by one pH measurement device.SOLUTION: A pH measurement device 1 comprises: a pH meter 10; and a cylindrical vertical container 20 into which a rod-shaped electrode 11 is inserted from a top portion, and performs pH measurement while consecutively introducing an aqueous solution of the measurement target whose pressure is boosted by a pump 2 from an inlet nozzle 21 and simultaneously overflowing from an outlet nozzle 22. The outlet nozzle 22 has a position L1 of a lowermost part of the container side opening higher than a center part L2 in a vertical direction of the vertical container 20 and higher than a position L3 of an uppermost part of the container side opening of the inlet nozzle 21. A bottom part of the vertical container 20 is provided with a drain nozzle 23 and a discharge valve 24 connected thereto.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pH measuring device. [Background technology]

[0002] In water quality management of treated water and industrial wastewater from various production plants, process control is performed to adjust the amount of chemicals added based on the pH measurement results of the aqueous solution to be treated. Stable control requires accurate measurement of the pH value using a highly reliable pH measuring device. Furthermore, accurate measurement of the pH value of the aqueous solution after treatment using a highly reliable pH measuring device is also necessary to confirm that the treatment has been carried out appropriately. However, over a long period of use, pH measuring devices can become unable to accurately measure the pH due to scale buildup on the pH electrode or blockage of the sampling pipe (hereinafter sometimes referred to as the supply pipe) that delivers the aqueous solution to the pH measuring device caused by impurities in the aqueous solution to be treated.

[0003] Therefore, pH measuring devices and their sampling piping are regularly cleaned.For example, Patent Document 1 discloses a technique in which a pair of pots, each equipped with a pH meter, are arranged in parallel on an external circulation line for sampling provided in a coprecipitation tank that receives waste liquid to be measured for pH, and an inlet control valve is provided on this external circulation line, and each pot is also provided with an inlet control valve and an outlet control valve, and a cleaning liquid line is connected immediately downstream of these control valves, thereby switching the flow of waste liquid to the pair of pots and cleaning each pot individually or cleaning the sampling piping as a whole. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Unexamined Japanese Patent Publication No. 2016-223775 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology of Patent Document 1 requires the installation of multiple pH measurement devices each equipped with a pH meter, and in order to ensure stable pH measurement even when switching between these multiple pH measurement devices during operation, it is necessary to perform maintenance, disassembly, and cleaning of these multiple pH measurement devices in the same manner, which requires a great deal of cost and effort. The present invention has been made in view of the above circumstances, and aims to provide a pH measurement device that can perform stable pH measurement using a single pH measurement device. [Means for solving the problem]

[0006] In order to achieve the above object, the pH measuring device according to the present invention comprises: a pH meter; The upper opening is provided with a flanged lid or a cap-like member that is directly screwed in. From the top The rod electrode of the pH meter The solution to be measured is pressurized by a pump and is continuously introduced through the inlet nozzle. The introduced aqueous solution was Outlet nozzle only The pH measuring device measures pH while overflowing from a vertical container, and is characterized in that the bottom of the outlet nozzle's container-side opening is higher than the center of the vertical container and higher than the top of the inlet nozzle's container-side opening, and a drain nozzle and a discharge valve connected to the drain nozzle are provided at the bottom of the vertical container. [Effects of the Invention]

[0007] According to the present invention, stable pH measurement can be performed using a single pH measurement device. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a longitudinal sectional view of a pH measuring device according to an embodiment of the present invention. [Figure 2] 2 is a plan view schematically showing the nozzle mounting position of the upright container of the pH measuring device of FIG. 1. FIG. [Figure 3]FIG. 1 is a flow diagram of the pH measurement equipment constructed in the example (a) of the present invention and the comparative example (b). [Figure 4] FIG. 2 is a longitudinal sectional view of a pH measuring device used in a comparative example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A pH measuring device according to an embodiment of the present invention will be described in detail below with reference to the drawings. As shown in Fig. 1, the pH measuring device 1 according to an embodiment of the present invention comprises a pH meter 10, preferably using a glass electrode method, and a substantially cylindrical, upright container 20 into which a rod-shaped pH electrode 11 is inserted from a connection at the top. The vertical container 20 has an inlet nozzle 21 at its straight body through which an aqueous solution to be measured for pH, pressurized by a pump (not shown), is continuously introduced, and an outlet nozzle 22 through which the aqueous solution is overflowed and discharged after pH measurement. Furthermore, the vertical container 20 has a drain nozzle 23 at its bottom, to which a discharge valve 24 is connected.

[0010] The bottom of the upright container 20 is preferably in a generally inverted cone shape so that wastewater after cleaning can be easily discharged from the drain nozzle 23. The structure of the top of the upright container 20 into which the rod-shaped pH electrode 11 is inserted is not particularly limited, and a preferred structure is, for example, as shown in Figure 1, in which a cap-shaped member 26 is screwed onto a central nozzle portion that protrudes outward from a lid portion 25 that is flange-joined to the upper flange of the upright container 20, and the pH electrode 11 is inserted into a through-hole provided in the center of this cap-shaped member 26. Alternatively, the cap-shaped member may be screwed directly onto the upper opening of the upright container 20 and fixed.

[0011] In the pH measuring device 1 according to the embodiment of the present invention, the position L1 of the bottom of the container-side opening of the outlet nozzle 22 is higher than the vertical center L2 of the straight body of the upright container 20, and is also higher than the position L3 of the top of the container-side opening of the inlet nozzle 21. This structure allows the pH measuring device 1 to be cleaned while maintaining the state in which a sample of aqueous solution to be measured, such as wastewater, extracted from a process piping or the like for measurement by the pH measuring device 1, is pressurized by a pump and continuously supplied to the pH measuring device 1, i.e., without stopping the operation of the pump.

[0012] Specifically, if the aqueous solution to be measured, such as seawater, contains algae or other deposits that tend to adhere to the inside of the upright container 20, or if substances contained in the aqueous solution to be measured tend to precipitate in the form of scale or other deposits depending on the measurement conditions, the pH electrode 11 can be removed from the upright container 20 by removing the flange or cap at the top end of the upright container 20, and the aqueous solution to be measured is continuously introduced into the upright container 20 through the inlet nozzle 21. At the same time, the aqueous solution flowing in from the inlet nozzle 21 is allowed to overflow from the outlet nozzle 22, and the interior of the upright container 20 is cleaned with a cleaning tool such as a brush. This makes it easy to clean the algae and other deposits and scale that have adhered to the inner walls of the upright container 20.

[0013] After the above cleaning has been performed, by opening the drain valve 24 at the end of the drain nozzle 23 provided at the bottom, the above-mentioned algae, scale, and other deposits can be almost completely discharged from the drain nozzle 23. In this way, in order to properly discharge the deposits and the like from the drain nozzle 23 at the bottom of the upright vessel 20 and prevent the deposits from overflowing from the outlet nozzle 22 together with the aqueous solution, when discharging the wastewater after cleaning from the drain nozzle 23, it is preferable to design the capacity of the pump and the size and length of the piping so that the discharge amount per unit time is greater than the supply amount per unit time of the aqueous solution introduced into the upright vessel 20 by the pump.

[0014] As described above, since there is no need to stop the pump when cleaning the pH measuring device 1, cleaning can be nearly completed by cleaning the inside of the upright container 20 only once, and the operator does not need to make at least two trips to the pump's control panel, which is generally located far from the installation position of the pH measuring device 1, to stop and restart the pump. In addition, if the pump is stopped when cleaning the pH measuring device 1, the next time the pump is restarted, the aqueous solution remaining in a full state in the supply piping system in which the pump is installed will begin to flow all at once when the pump is restarted, and the physical force of this sudden flow will cause algae, scale, and the like adhering to the supply piping system to peel off and flow into the cleaned upright container 20, which would require cleaning the inside of the upright container 20 again about once or twice; however, if the pump operation is not stopped, this second cleaning will also be unnecessary.

[0015] When the aqueous solution to be measured is seawater, algae tend to adhere more significantly to the inside of the piping than freshwater, and therefore when the pump is stopped and cleaned as described above, and then restarted after cleaning, more algae tend to come off and flow into the upright container 20. Therefore, the pH measuring device 1 of the embodiment of the present invention is more effective when the aqueous solution to be measured is seawater than when it is freshwater. Furthermore, by using the pH measuring device 1 of the embodiment of the present invention, the number of times the interior of the upright container 20 needs to be cleaned can be reduced as described above, and therefore the continuous measurement time during which pH can be stably measured can be increased even though only one pH measuring device 1 is used.

[0016] In the pH measuring device 1 according to the embodiment of the present invention, the vertical distance L between the bottom position L1 of the container-side opening of the outlet nozzle 22 of the upright container 20 and the top position L3 of the container-side opening of the inlet nozzle 21 is preferably equal to or greater than the radius (D / 2) of the container-side opening of the inlet nozzle 21, and more preferably equal to or greater than half (H / 2) of the height H of the straight body of the upright container 20. By determining the vertical positional relationship between the outlet nozzle 22 and the inlet nozzle 21 as described above, the aqueous solution to be measured is less likely to short-pass or stagnate excessively inside the upright container 20, thereby enabling more accurate pH measurement and suppressing the adhesion of algae and the like inside the upright container 20.

[0017] Furthermore, in the pH measuring device 1 according to the embodiment of the present invention, it is preferable that the outlet nozzle 22 is provided as close to the upper end as possible of the straight body of the upright container 20. By providing the outlet nozzle 22 at the upper end of the upright container 20 in this manner, the aqueous solution to be measured that is introduced into the upright container 20 from the inlet nozzle 21 can flow smoothly inside the upright container 20, resulting in more accurate pH measurement and also making it possible to prevent algae from adhering to the inner wall surface above the outlet nozzle 22.

[0018] Furthermore, in the pH measuring device 1 according to the embodiment of the present invention, the type of discharge valve 24 attached to the drain nozzle 23 is preferably a butterfly valve or a ball valve, and more preferably a butterfly valve. These types of valves allow the inner diameter of the opening when the movable parts, such as the disk or ball, are fully open to be approximately equal to the inner diameter of the drain nozzle 23, so that any detached deposits remaining in the upright container 20 can be easily discharged without being obstructed by the movable parts of the valve. In particular, butterfly valves have a smaller liquid-contacting area inside the valve than other types of valves, minimizing the possibility of algae and the like adhering to the inside of the valve.

[0019] The material of the liquid-contacting parts of the pH measuring device 1 according to the embodiment of the present invention is not particularly limited as long as it is not easily corroded by the aqueous solution to be measured, and suitable materials include resins such as polyvinyl chloride (PVC) and polypropylene (PP), and corrosion-resistant metals such as SUS316. In particular, polyvinyl chloride is more preferably used as the material for the discharge valve 24. This is because polyvinyl chloride has excellent corrosion resistance, does not rust, and has low frictional resistance on the inner surface, allowing detached deposits to be easily discharged, thereby preventing the formation of scale and the adhesion of algae, etc.

[0020] In the pH measuring device 1 according to the embodiment of the present invention, when viewed from directly above as shown in FIG. 2, the angle of the attachment position of the inlet nozzle 21 is set to 0°, and the angle of the attachment position of the outlet nozzle 22 is preferably within the range of 135° to 225°. By specifying the nozzle attachment position (nozzle orientation) as described above, the flow of the aqueous solution inside the upright container 20 can be made to be generally linear. This makes it possible to prevent algae, scale, and the like from adhering to the inner wall surface of the upright container 20. In other words, if the flow inside the upright container 20 is generally curved, the flow will locally slow down or stagnate at the innermost periphery, which is undesirable because it makes it more likely that algae, scale, and the like will adhere to the inner wall surface in contact with this area. [Example]

[0021] [Example] The pH measurement equipment shown in Figure 3(a) was constructed using a pH measurement device 1 with the structure shown in Figure 1, and samples continuously extracted from factory wastewater containing seawater used as cooling water via a sampling pipe were introduced into the pH measurement device 1 at a flow rate of 30 to 60 liters per minute, and pH measurements were performed. The pH measurement device 1 used had the structure shown in Figure 1, the pump 2 was a pump (model: YD-16GS-S) manufactured by World Chemical Co., Ltd., and the discharge valve 24 was a butterfly valve with an inner diameter of 16 mm.

[0022] The height H of the straight body of the upright container 20 was 170 mm, the inner diameter of the inlet nozzle 21 was 16 mm, and the inner diameter of the outlet nozzle 22 was 26 mm. The position L1 of the bottom of the container-side opening of the outlet nozzle 22 was higher than the center L2 of the up-down direction of the straight body of the upright container 20 and higher than the position L3 of the top of the container-side opening of the inlet nozzle 21. In addition, the vertical distance between the position L1 of the bottom of the container-side opening of the outlet nozzle 22 and the position L3 of the top of the container-side opening of the inlet nozzle 21 was set to 30 mm, so that the radius of the container-side opening of the inlet nozzle 21 was 8 mm or more.

[0023] pH measurements were performed using this pH measuring device 1 for a period of three months, during which time cleaning was performed once every two days. During this cleaning, the operation of the pump 2 was not stopped, and while continuously introducing wastewater into the vertical container 20 from the inlet nozzle 21 and simultaneously discharging it by overflow from the outlet nozzle 22, the pH electrode 11 was removed from the vertical container 20, and algae and other deposits adhering to the inside of the vertical container 20 were cleaned with a brush. As a result, the cleaning time was reduced to approximately two minutes per cleaning.

[0024] [Comparative Example] The pH of industrial wastewater was measured in the same manner as in the above-described example, except that the pH measurement equipment shown in Fig. 3(b) was constructed using a pH measurement device 101 having the structure shown in Fig. 4. Unlike the above-described example in which the inlet nozzle 21 is provided on the side of the upright container 20, the pH measurement device 101 of this comparative example has an inlet nozzle 121 provided on the bottom of the upright container 120, which made it necessary to stop operation of the pump 2 when cleaning the pH measurement device 101.

[0025] Furthermore, in order to drain the liquid remaining in the upright container 120 after cleaning, it was necessary to disconnect the supply pipe connected to the inlet nozzle 121 at the bottom. Furthermore, after cleaning the interior of the upright container 120 with a brush, when the supply pipe was reconnected and the pump 2 was restarted, algae and other deposits that had presumably been attached to the inside of the supply pipe flowed into the upright container 120 from the inlet nozzle 121 at the bottom of the upright container 120. This required further cleaning with a brush, and the time required to almost completely remove the detached algae and other deposits was longer than in the Example. Specifically, as mentioned above, the cleaning time per cycle was approximately 2 minutes in the Example, while it took approximately 4 minutes in the Comparative Example. Furthermore, re-cleaning was required every time, resulting in a maximum of approximately 12 minutes per cycle. Furthermore, a third re-cleaning was required approximately once every three cycles, and each re-cleaning required approximately 15 minutes. [Explanation of symbols]

[0026] 1, 101 pH measuring device 10 pH meter 11 pH electrode 20, 120 vertical container 21, 121 Inlet nozzle 22, 122 outlet nozzle 23 Drain nozzle 24 Exhaust valve 25, 125 Lid 26, 126 Cap-shaped member

Claims

1. A pH measurement device comprising a pH meter and a cylindrical, vertical container with a structure in which a rod-shaped electrode of the pH meter is inserted into the top of the container and a flanged lid or a directly screwed cap-shaped member is provided at the upper opening, and the pH of the aqueous solution to be measured is measured while continuously introducing the aqueous solution to be measured, which has been pressurized by a pump, through an inlet nozzle and simultaneously allowing the introduced aqueous solution to overflow through only one outlet nozzle, wherein the lowest position of the container-side opening of the outlet nozzle is higher than the center of the vertical container and higher than the highest position of the container-side opening of the inlet nozzle, and the vertical container is provided with a drain nozzle and a discharge valve connected to the drain nozzle at the bottom.

2. 2. The pH measuring device according to claim 1, wherein the distance between the bottom of the outlet nozzle and the top of the inlet nozzle in the vertical direction is equal to or greater than the radius of the container-side opening of the inlet nozzle.

3. 3. The pH measuring device according to claim 1, wherein the outlet nozzle is provided at an upper end of the vertical container.

4. 4. The pH measuring device according to claim 1, wherein the discharge valve is a butterfly valve.

5. A method for cleaning a pH measuring device comprising a pH meter and a cylindrical, upright container having a flanged lid or a directly screwed cap-like member at its upper opening and into which a rod electrode of the pH meter is inserted from the top, the method comprising the steps of: continuously introducing an aqueous solution to be measured that has been pressurized by a pump through an inlet nozzle; simultaneously allowing the introduced aqueous solution to overflow from only one outlet nozzle whose bottom is higher than the center of the vertical container and higher than the top of the inlet nozzle; removing the rod electrode and cleaning the inside of the container; and, after the cleaning, opening a valve provided at a drain nozzle at the bottom of the container while continuing to introduce the aqueous solution to be measured through the inlet nozzle to discharge the cleaning wastewater.

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