DILUTION EQUIPMENT FOR WATER QUALITY MEASUREMENT AND DILUTION METHODS

Abstract

The dilution device used for water quality measurement prepares water samples by diluting the crude solution with diluent water. The device includes: a container 10; a crude solution supply unit to provide crude solution to the container; a diluent water supply unit to provide diluent water to the container 10; a circulation unit to circulate water in the container; a drainage unit to allow water in the container to drain out; and a pressure sensor 9 to detect the water level in the container. The drainage unit includes a pump 14, and water is allowed to drain out of the container 10 by gravity when the pump 14 stops.

Description

Dilution device and dilution method for water quality measurement

[0001] The present invention relates to a dilution device for measuring water quality, and more particularly to a dilution device for measuring water quality by diluting a stock solution. The present invention also relates to a dilution method using the dilution device for measuring water quality.

[0002] A batch-type automatic continuous residual chlorine concentration measuring device is known as a technology for automatically measuring the residual chlorine concentration in water. This device measures the residual chlorine concentration in water by absorptiometry using N,N-diethyl-1,4-phenylenediamine reagent (DPD reagent). The residual chlorine concentration that can be measured by this device is 8 mg / L or less. Therefore, this device is not suitable for measuring high concentrations above 8 mg / L.

[0003] Patent Document 1 describes a water quality measurement dilution device capable of quantifying high concentrations of residual chlorine, which includes a dilution device that prepares sample water containing raw water and dilution water, and a residual chlorine concentration measuring device that measures the residual chlorine concentration of the sample water, wherein the dilution device is equipped with a container that contains the sample water, a first liquid level detection unit that detects a first liquid level in the container, a second liquid level detection unit that detects a second liquid level in the container, a raw water injection unit that injects the raw water into the container until the first liquid level detection unit detects the first liquid level, and a dilution water injection unit that injects the dilution water into the container and dilutes the raw water until the second liquid level detection unit detects the second liquid level.

[0004] In the dilution device for water quality measurement described in Patent Document 1, the dilution device dilutes raw water and, if necessary, re-dilutes the raw water to prepare sample water, which is then transferred to a residual chlorine concentration measuring device via a sample water storage section, where the residual chlorine concentration is measured. In this water quality measuring device, the raw water is diluted once or twice or more times. By diluting the raw water twice or more times, high-concentration raw water can be sufficiently diluted.

[0005] JP 2023-87160 A

[0006] In the dilution device for measuring water quality described in Patent Document 1, when a capacitance sensor or optical sensor is used as the liquid level detection unit, errors in liquid level detection can occur due to dirt on the dilution container or water droplets running down the walls of the dilution container, resulting in fluctuations in the dilution concentration.

[0007] Patent Document 1 also describes the use of a pressure-type liquid level sensor to detect the water level. However, in Patent Document 1, when measuring raw water, raw water in the raw water tank is poured into the container from above until the liquid level detector detects the liquid level.

[0008] When raw water is supplied from above, the liquid level inside the container fluctuates as the raw water falls inside the container. This fluctuation in the liquid level causes fluctuations in pressure, which leads to errors in the detected water level even when a pressure-type liquid level sensor is used as in Patent Document 1.

[0009] An object of the present invention is to provide a dilution device and a dilution method for water quality measurement that can control the dilution ratio with high precision.

[0010] The dilution device for water quality measurement of the present invention is a dilution device for water quality measurement for preparing sample water by diluting a stock solution with dilution water, and is a dilution device for water quality measurement having a container, a stock solution supply unit for supplying the stock solution to the container, a dilution water supply unit for supplying dilution water to the container, a circulation unit for circulating the liquid in the container, an outflow unit for discharging the liquid in the container, and a pressure sensor for detecting the water level in the container, and the outflow unit is equipped with a pump, and when the pump is stopped, gravity causes the liquid to flow out of the container.

[0011] In one aspect of the present invention, the circulation unit circulates and feeds water by the pump of the outflow unit.

[0012] The dilution method of the present invention is a dilution method for preparing sample water by diluting a stock solution with dilution water using the water quality measurement dilution device of the present invention, and includes a stock solution introduction step of introducing a first specified amount of stock solution into the container, a dilution water introduction step of introducing a second specified amount of dilution water into the container, a stirring step of circulating and stirring the liquid in the container, and a removal step of removing the diluted liquid from the container.The stock solution introduction step includes a step of introducing a stock solution in an amount greater than the first specified amount into the container, a pump discharge step of operating the pump to discharge a portion of the excess from the container, and then a gravity discharge step of stopping the pump and allowing the stock solution in the container to flow out by gravity so that the amount of stock solution in the container detected by the pressure sensor becomes the first specified amount.

[0013] In one aspect of the dilution method of the present invention, after the raw liquid introducing step is performed, the residual liquid in the circulation section is discharged to the outside of the dilution apparatus for water quality measurement, and then the dilution water introducing step is performed.

[0014] In one aspect of the dilution method of the present invention, after the concentrate introduction step, dilution water introduction step, and stirring step are performed, a drainage step is performed in which the liquid volume in the container is drained to the first specified volume, and then dilution water is introduced into the container to perform a second dilution step.

[0015] In one aspect of the dilution method of the present invention, after the draining step, residual water is discharged from the circulation section before the dilution water is introduced.

[0016] According to the dilution device and dilution method for water quality measurement of the present invention, when a specified amount of stock solution and dilution water are mixed in a container to prepare diluted sample water, the amount of liquid in the container is detected by a pressure sensor. In the dilution method of the present invention, after introducing an excess of stock solution into the container compared to the specified amount, most of the excess is first discharged by a pump, and then the remaining excess is drained by gravity, leaving the specified amount of stock solution in the container.

[0017] When the excess liquid is drained by gravity in this way, the liquid level in the container does not fluctuate due to pump vibration, and the water level can be detected accurately by the pressure sensor, so the specified amount of concentrate can be stored in the container with high precision, and the concentrate can be diluted at a highly accurate dilution ratio.

[0018] Furthermore, by discharging most of the excess with a pump, the discharging time is shortened compared to when the entire excess is discharged by gravity.

[0019] Fig. 1 is a configuration diagram of a dilution device for water quality measurement according to an embodiment. Fig. 2 is an explanatory diagram of a water quality measurement process in the dilution device for water quality measurement of Fig. 1. Fig. 3 is an explanatory diagram of a water quality measurement process in the dilution device for water quality measurement of Fig. 1. Fig. 4 is an explanatory diagram of a water quality measurement process in the dilution device for water quality measurement of Fig. 1. Fig. 5 is an explanatory diagram of a water quality measurement process in the dilution device for water quality measurement of Fig. 1.

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a diagram showing the configuration of a dilution device for measuring water quality according to an embodiment of the present invention.

[0021] A stock solution supply unit consisting of a pipe 1, an electromagnetic valve 2, and a pipe 3 is connected to the top of the container 10 so as to supply stock solution into the container 10. Also, a dilution water supply unit consisting of a pipe 4, an electromagnetic valve 5, and a pipe 6 is connected to the top of the container 10 so as to supply dilution water into the container 10.

[0022] A communication port (not shown) that connects the inside of the container 10 to the atmosphere is provided at the top of the container 10. When liquid is supplied to or discharged from the container 10, air enters or leaves the container 10 through the communication port.

[0023] A pressure sensor 9 for detecting the water level in the container 10 is provided at the lower part of the container 10 (the bottom in this embodiment).

[0024] In order to discharge or circulate the liquid in the container 10, an outflow section consisting of a pipe 11, an electromagnetic valve 12, a pipe 13, a pump 14 and a pipe 15 is connected to the bottom of the container 10.

[0025] The pump 14 is configured to send water from the pipe 13 to the pipe 15 when in operation, and to connect the pipes 13 and 15 to each other (allow water to flow) when stopped.

[0026] The end of pipe 15 branches into pipes 16, 20, and 23. Pipe 16 serves to form a circulation section, and is connected to the top of container 10 via solenoid valve 17 and pipe 18, returning the liquid in container 10 to the top and circulating it.

[0027] The pipe 20 is connected to a pipe 22 via an electromagnetic valve 21, and these constitute an extraction section for extracting the diluted sample water for analysis.

[0028] The pipe 23 is connected to a pipe 25 via an electromagnetic valve 24, and these constitute a discharge section for discharging the liquid in the container 10 and each pipe to the outside of the system.

[0029] Each step for preparing diluted sample water using the dilution device for water quality measurement configured as above will be described below.

[0030] [Initial Drainage Step] First, the residual liquid remaining in the water quality measurement dilution apparatus from the previous dilution operation is drained. To drain the residual liquid, solenoid valves 12 and 24 are opened, the other solenoid valves are closed, and pump 14 is operated (hereinafter sometimes referred to as ON). As a result, the residual liquid in container 10 and between pipes 11 to 15 is drained through pipes 23 and 25.

[0031] Next, the pump 14 is stopped (hereinafter sometimes referred to as OFF), the solenoid valves 17 and 24 are opened, and the other solenoid valves are closed, and the remaining liquid between the pipes 18 to 16 is discharged through the pipes 23 and 25.

[0032] [Stock solution introduction step] To prepare sample water by diluting the stock solution with dilution water at a specified ratio, first, the stock solution is stored in the container 10 to a water level H1. Hereinafter, the amount of liquid at the water level H1 may be referred to as the first specified amount.

[0033] In this case, solenoid valve 2 is opened, the other solenoid valves are closed, and pump 14 is turned OFF. Solenoid valve 2 is opened for a predetermined time so that the water level in container 10 is higher than H1, and the stock solution is introduced. Next, solenoid valves 12 and 24 are opened, the other solenoid valves are closed, pump 14 is turned ON, and after the water level in container 10 has dropped to near H1, pump 14 is turned OFF. At this time, solenoid valves 12 and 24 are left open. This causes the liquid to flow out of container 10 due to gravity. In this case, because pump 14 is turned OFF, container 10 does not vibrate, and the liquid level in container 10 does not sway.

[0034] When the water level detected by the pressure sensor 9 reaches H1, the solenoid valve 12 is closed, so that the concentrate is stored in the container 10 precisely at the water level H1 (FIG. 2).

[0035] As described above, pump 14 is turned on to perform pumping until the water level approaches H1, and then pump 14 is turned off to perform gravity discharge, which allows the liquid to flow out of container 10 by gravity. In this way, liquid is discharged from container 10 by pump 14 until the water level approaches H1, which speeds up drainage. Furthermore, during gravity discharge, there is no fluctuation of the liquid level in container 10 due to vibrations propagated from pump 14, and the pressure sensor 9 detects the water level with high accuracy.

[0036] The outflow rate during gravity outflow is slower than that during pump discharge when the pump 14 is turned on, and the drop in the water level in the container 10 is slow. Therefore, the solenoid valve 12 can be reliably closed when the water level in the container 10 drops to H1.

[0037] [Removal of Liquid from Circulation Pipe] After the above-mentioned raw liquid introduction step, solenoid valves 17 and 24 are opened, the other solenoid valves are closed, pump 14 is turned off, and the liquid between pipes 18 to 16 is discharged through pipes 23 and 25.

[0038] [Dilution Step] Then, solenoid valve 5 is opened, the other solenoid valves are closed, pump 14 is turned OFF, and dilution water is introduced into container 10 up to water level H2 (FIG. 3). Next, solenoid valves 12 and 17 are opened, the other solenoid valves are closed, pump 14 is turned ON, and the liquid in container 10 is circulated and stirred through pipes 11, 13, 15, 16, and 18 (FIG. 4).

[0039] If the volume of the stock solution introduced into container 10 is V1 and the volume of the dilution water introduced into container 10 (second specified amount) is V2, sample water (hereinafter sometimes referred to as the first diluted sample water) obtained by diluting the stock solution by a factor of (V2 + V1) / V1 is prepared by the above-mentioned first dilution step (first dilution step).

[0040] If the first diluted sample water is a 10-fold dilution of the original solution, a second diluted sample water that is 100-fold diluted is prepared by performing a similar second 10-fold dilution process (second dilution process), and a third diluted sample water that is 1000-fold diluted is prepared by performing a similar third 10-fold dilution process (third dilution process) on the second diluted sample water.

[0041] In addition, to perform the second, third or more dilution steps (hereinafter referred to as the nth dilution step), a discharge step is performed in which the (n-1)th diluted sample water prepared in the (n-1)th dilution step in the container 10 is discharged to the water level H1 by pumping and gravity discharge.

[0042] In this discharge process, too, initially, solenoid valves 12 and 24 are opened, the other solenoid valves are closed, and pump 14 is turned on to perform pump discharge, and when the water level approaches H1, solenoid valves 12 and 24 are left open and pump 14 is turned off to perform gravity discharge, in which the liquid in pump container 10 is discharged by gravity. In this gravity discharge, the liquid level in container 10 does not fluctuate, so the residual water volume can be accurately determined to be at water level H1.

[0043] After the water level of the (n-1)th diluted water sample in the container 10 is lowered to H1 as described above, the solenoid valves 17 and 24 are opened, the other solenoid valves are closed, the pump 14 is turned off, and the (n-1)th diluted water sample remaining between the pipes 18 and 16 is discharged via the pipes 23 and 25. Thereafter, dilution water is introduced into the container 10 up to the water level H2, and circulating and stirring is performed to produce the nth diluted water sample.

[0044] [Extraction Process] After the dilution process, to extract the diluted water sample from the container 10, the solenoid valves 12 and 21 are opened, the other solenoid valves are closed, the pump 14 is turned on, and the diluted water sample is extracted through the pipes 11, 13, 15, 20, and 22 (Figure 5).

[0045] <Concentrate solution, dilution water> The present invention is suitable as a dilution device for measuring the residual chlorine concentration in a concentrate solution, and examples of such concentrate solutions include, but are not limited to, CIP cleaning solutions used in beverage and food manufacturing plants, food sterilizing solutions, cooking utensil sterilizing solutions, etc. However, the water quality measurement dilution device of the present invention can also be used as a dilution device for measuring components other than residual chlorine.

[0046] The dilution water may be tap water treated with activated carbon, pure water, ultrapure water, or the like, but is not limited to these.

[0047] <Container> A cylindrical container is suitable, but a rectangular tube shape is also acceptable. In the case of a cylindrical container, the height of the container is preferably 3 to 30 times, and more preferably 5 to 10 times, the diameter of the bottom surface.

[0048] <Pressure Sensor> The pressure sensor is not particularly limited as long as it can detect the water level in the container 10, and various commercially available products can be used.

[0049] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese Patent Application No. 2023-191016, filed on November 8, 2023, and is incorporated by reference in its entirety.

[0050] 2, 5, 12, 17, 21, 24 Solenoid valve 9 Pressure sensor 10 Container 14 Pump

Claims

1. A dilution device for water quality measurement for preparing sample water by diluting an original solution with dilution water, the dilution device having: a container; an original solution supply section for supplying original solution to the container; a dilution water supply section for supplying dilution water to the container; a circulation section for circulating the liquid in the container; an outflow section for draining the liquid in the container; and a pressure sensor for detecting the water level in the container, wherein the outflow section is equipped with a pump, and the dilution device for water quality measurement is capable of draining the liquid from the container by gravity when the pump is stopped.

2. A dilution device for measuring water quality according to claim 1, wherein the circulation section circulates and supplies water by means of the pump at the outlet section.

3. A dilution method for preparing sample water by diluting an original solution with dilution water using the water quality measurement dilution device of claim 1 or 2, comprising: an original solution introducing step of introducing a first specified amount of original solution into the container; a dilution water introducing step of introducing a second specified amount of dilution water into the container; a stirring step of circulating and stirring the liquid in the container; and a removal step of removing the diluted liquid from the container, wherein the original solution introducing step comprises: a step of introducing an amount of original solution in excess of the first specified amount into the container; a pump discharge step of operating the pump to discharge a portion of the excess from the container; and a gravity discharge step of stopping the pump and allowing the original solution in the container to flow out by gravity so that the amount of original solution in the container detected by the pressure sensor becomes the first specified amount.

4. The dilution method according to claim 3, wherein after the step of introducing the concentrate is performed, the residual liquid in the circulation section is discharged outside the dilution apparatus for water quality measurement, and then the step of introducing water for dilution is performed.

5. The dilution method according to claim 4, further comprising the steps of: after the step of introducing the concentrate solution, the step of introducing the dilution water and the step of stirring, a step of draining the liquid so that the amount of liquid in the container becomes the first specified amount; and then introducing the dilution water into the container to carry out a second dilution step.

6. The dilution method according to claim 5, further comprising the step of draining residual water from said circulation section after said draining step and before introducing said dilution water.

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