JP4186849B2 - Dissolved gas concentration measuring device - Google Patents

Description

  The present invention relates to a dissolved gas concentration measuring device for measuring the concentration of dissolved gas such as treated water in a deoxygenation device, particularly the dissolved oxygen concentration.

  In recent years, deoxygenation devices that remove dissolved oxygen in water have become widespread in boiler facilities used as heat sources in factories, cleaning facilities using pure water in the manufacture of electronic components, or in residential facilities such as buildings and condominiums. This deoxygenation device is used to prevent, for example, boiler water pipes and condensate pipes from being corroded and damaged in boiler facilities, and is a safe water treatment technique that replaces deoxygenation by chemicals. Moreover, in the cleaning equipment using pure water, it is used to prevent the electronic parts from being oxidized during the cleaning and degrading the quality.

  By the way, in order to confirm that the performance of the deoxygenation apparatus is exhibited normally and treated water from which dissolved oxygen is sufficiently removed is obtained, the dissolved oxygen concentration of the treated water can be measured periodically. It is essential. In particular, in boiler facilities and cleaning facilities using pure water, a high level of water quality control is required, so automatic and continuous measurement of dissolved oxygen concentration is desired.

  The measurement of the dissolved oxygen concentration is generally performed by a chemical method or an electrochemical method described in Non-Patent Document 1. Among these, the chemical method is not suitable for automation of measurement because the operation is precise and complicated, for example, it is necessary to prevent the dissolution of air into the sample water and the oxidative deterioration of the reagent. On the other hand, electrochemical methods typified by a diaphragm type dissolved oxygen concentration meter require periodic maintenance for maintaining accuracy, such as replacement of a diaphragm and an internal solution, and therefore, continuous measurement is difficult.

  Further, Patent Document 1 describes a dissolved gas concentration measurement device that has a low-cost configuration as compared with a conventional dissolved oxygen concentration meter and that is easily equipped with a deoxygenation device. This measuring apparatus extracts sample water into a container by an extraction means, depressurizes the sample water in the container with a decompression means to reduce the solubility of dissolved gas, and detects the generated gas with an electrode, thereby The dissolved gas concentration is determined by determining the difference in the amount of production. In such an apparatus, since the measurement operation and configuration are simple, it is possible to automatically and continuously measure the dissolved oxygen concentration. However, the configuration described in Patent Document 1 has a problem that sufficient reliability cannot be obtained in the measurement result for the following reason.

  First, when the sample water is closer to pure water, the difference in electrical resistance between the sample water and the gas is small, so that it is difficult to determine the difference in the amount of gas generated by the detection method using electrodes. In particular, pure water for cleaning used in cleaning equipment using pure water in the production of electronic components tends to be highly purified, and it is necessary to cope with such dissolved oxygen concentration measurement. Second, when there is a factor that changes the capacity of the decompression means, the degree of decompression of the sample water changes, which affects the amount of gas generated. For example, when a water-sealed vacuum pump is used as the decompression means, the ultimate vacuum changes depending on the temperature of the sealed water, so this state can occur. Third, when the temperature of the sample water changes, the saturated vapor pressure of the sample water also changes, and the water vapor affects the amount of gas generated. For example, if the saturated vapor pressure of the sample water is close to the vacuum level of the decompression means, more water vapor will be contained in the gas, so the exact dissolved gas concentration must be determined without considering the vapor content. I can't.

Japan Water Works Association “Water Supply Test (2001)” pages 137-148 JP 7-49295 A

  The problem to be solved by the present invention is to realize automatic and continuous measurement of dissolved gas concentration. Moreover, it is to ensure the reliability of the measurement result of the dissolved gas concentration.

The present invention has been made to solve the above-mentioned problems. The invention according to claim 1 is directed to a container for collecting sample water, a decompression means for decompressing the sample water in the container, and the decompression means. It consists of a photoelectric sensor that detects the gas generated by decompression and the other liquid phase as a change in light, outputs a detection state within a predetermined measurement time as a signal, and a detection means that detects the temperature of the sample water, The photoelectric sensor and the detection means are each connected to a determination means via a signal line, and the determination means obtains the ultimate pressure of the decompression means based on the temperature detection value of the sample water of the detection means, Based on the signal from the photoelectric sensor, a gas generation rate is obtained, and the determination means further dissolves the sample water based on the gas generation rate, the temperature detection value of the sample water, and the ultimate pressure. Determine the concentration It is characterized in that.

Further, the invention according to claim 2 is a method for optically analyzing a container for collecting sample water, a decompression means for decompressing the sample water in the container, a gas generated by the decompression of the decompression means, and the other liquid phase. A photoelectric sensor that detects a change in the detection time and outputs a detection state within a predetermined measurement time as a signal, a first detection means that detects an ultimate pressure of the decompression means, and a second detection means that detects the temperature of the sample water The photoelectric sensor, the first detection unit, and the second detection unit are connected to a determination unit via signal lines, respectively, and the determination unit determines a gas generation rate based on a signal from the photoelectric sensor. And the determination means further includes a gas generation rate determined based on a signal from the photoelectric sensor, an ultimate pressure of the decompression means based on a signal from the first detection means, and a second detection means. Based on the signal of It is characterized by determining the dissolved gas concentration of the sample water based on the temperature detection value of the sample water.

Furthermore, the invention described in claim 3 is a container for collecting sample water, depressurizing means for depressurizing the sample water in the container, gas generated by depressurization of the depressurizing means, and other liquid phases. A photoelectric sensor that detects a change in the detection time and outputs a detection state within a predetermined measurement time as a signal, a first detection means that detects an ultimate pressure of the decompression means, and a second detection means that detects the temperature of the sample water A flow rate detection means for detecting the amount of sample water flowing into the container per time, and the photoelectric sensor, the first detection means, the second detection means, and the flow rate detection means are respectively connected via signal lines. The determination means obtains a gas generation rate based on the signal from the photoelectric sensor and the signal from the flow rate detection means, and the determination means further determines the signal from the photoelectric sensor and the Detecting the temperature of the sample water based on the gas generation rate obtained based on the signal from the quantity detection means, the ultimate pressure of the decompression means based on the signal from the first detection means, and the signal from the second detection means The dissolved gas concentration of the sample water is determined based on the value .

  According to the present invention, the sample water collected in the container is decompressed by the decompression means, and the generated gas is detected by the photoelectric sensor, so that automatic and continuous measurement can be realized. . In particular, since the photoelectric sensor is used for detecting the gas, even when the sample water is closer to pure water, the generated gas and the other liquid phase can be accurately distinguished. Moreover, since the dissolved gas concentration is determined based on the signal from the photoelectric sensor, the ultimate pressure of the decompression means, and the temperature of the sample water, the reliability of the measurement result can be ensured.

  Next, an embodiment of the present invention will be described. The present invention is applied to measurement of the dissolved oxygen concentration of raw water and treated water in a water treatment facility equipped with a deoxygenation device.

  The dissolved gas concentration measuring device of the present invention includes a depressurizing means for depressurizing sample water collected from raw water or treated water to be measured into a container, and a photoelectric detector for detecting gas generated from the sample water by depressurization. And a sensor.

  The container is provided with an inlet and an outlet for sample water, and in the present invention, a cylindrical shape such as a pipe or a tube is also included. An orifice is connected to the inlet or is provided integrally therewith. This orifice is for limiting the amount of sample water flowing into the container to increase the degree of pressure reduction of the sample water to the same level as or the same as the ultimate pressure of the pressure reducing means.

  The outlet is connected to the decompression means by a decompression line. When this decompression line is filled with sample water during decompression operation, the ultimate pressure may decrease. Therefore, if a buffer unit such as a downcomer or a trap is provided, the ultimate pressure is stabilized.

  As the pressure reducing means, for example, a water ring vacuum pump, a positive displacement vacuum pump, an ejector or the like can be used. In particular, since the sample water flows into the suction side of the decompression means, it is preferable to use a water ring vacuum pump. Further, the decompression means can be shared with decompression means provided in the deoxygenation device, for example, a water-sealed vacuum pump.

  In the above-described configuration, the sample water can be collected by connecting the orifice with a pipe through which raw water or treated water flows, or by directly immersing in raw water or treated water stored in a tank or the like.

  The photoelectric sensor has a light projecting body such as a light emitting diode and a light receiving body such as a photodiode and a phototransistor, and outputs an electrical signal such as an ON signal or an OFF signal in response to a change in incident light to the light receiving body It is possible. In addition, it is preferable to use an optical fiber sensor that transmits and receives light to and from a detection position via an optical fiber because the gas detection position can be variously set with respect to the container.

  By the way, the said optical fiber sensor of the system which fixes the detector with which the optical fiber for light projection / reception was connected to the outer side of transparent pipes, such as glass and resin, is known. In this method, when there is no water, the emitted light is reflected by the inner surface of the transparent pipe and returns to the photoreceptor, but when water is present, most of the emitted light diffuses into the water and does not return to the photoreceptor. The difference in rate is used to distinguish between gas and water.

  When this type of sensor is used, the container is first formed in a cylindrical shape, and the entire container or a portion to which the detector is fixed is formed of a transparent or translucent material. Next, the outflow port is provided above the inflow port so that the gas generated by the decompression is sequentially discharged along with the sample water flowing in the container. And the said detector is fixed to the outer side of this container. That is, the gas passing through the position of the detector is detected.

  As the optical fiber sensor, there is known a system in which a detection rod in which a light projecting / receiving optical fiber is covered with a transparent or translucent material such as a fluororesin is disposed in a liquid storage tank. In this method, when there is no water, the emitted light is reflected inside the tip of the detection rod and returns to the photoreceptor, but when there is water, most of the emitted light diffuses into the water and does not return to the photoreceptor. The difference in rate is used to distinguish between gas and water.

  When this type of sensor is used, the tip of the detection rod is fixed at a position that secures a predetermined volume in the container. The inflow port and the outflow port are positioned below the container so that the gas generated by decompression is stored in the upper part of the container and the liquid phase of the sample water is discharged. . That is, a predetermined volume of gas defined at the tip position of the detection rod is detected.

  The dissolved gas concentration measuring apparatus according to the present invention further includes a detecting means for detecting the ultimate pressure of the pressure reducing means and the temperature of the sample water.

  As the detection means, for example, a temperature sensor is applicable. When a water-sealed vacuum pump is used as the pressure reducing means, the ultimate pressure has a correlation with the temperature of the sealed water. Therefore, when the temperature change of the sealed water is detected by a temperature sensor, a change in the ultimate pressure is required. Moreover, when it is set as the structure which heat-exchanges sample water with sealing water simultaneously, if the temperature change of sealing water is detected with a temperature sensor, the temperature change of sample water will be calculated | required. That is, the ultimate pressure of the decompression means and the temperature of the sample water can be detected by one detection means.

  Further, the detection means may include a first detection means for detecting the ultimate pressure of the decompression means and a second detection means for detecting the temperature of the sample water.

  Various negative pressure sensors and vacuum sensors can be used for the first detection means. If these sensors are attached to the decompression line or the buffer unit provided in the decompression line, a change in ultimate pressure can be detected. Further, when a water ring vacuum pump is used for the pressure reducing means, a temperature sensor can be used for the first detecting means to detect the temperature of the sealed water and obtain a change in the ultimate pressure.

  Various temperature sensors using a thermocouple, a resistance temperature detector, or the like can be used for the second detection means. This second detection means is attached to the container, for example, in order to detect the temperature of the sample water.

  The photoelectric sensor and the detection unit are electrically connected to the determination unit, and each signal is input to the determination unit. This determination means is composed of a memory for storing a program for determining the dissolved gas concentration, various data, and an arithmetic circuit.

  Hereinafter, the operation of the dissolved gas concentration measuring apparatus of the present invention will be described. First, the case where the detector of the optical fiber sensor (one form of photoelectric sensor) is fixed to the outside of the cylindrical container will be described. In this configuration, as described above, the whole of the container or the portion to which the detector of the optical fiber sensor is fixed is formed of a transparent or semi-transparent material, and the sample water outlet is connected to the inlet. Is also provided in an upward position.

  When the decompression means is operated, the inside of the container becomes negative pressure, and the sample water is sucked into the container through the orifice and flows toward the outlet. After passing through the orifice, the sample water is depressurized to the same or approximately the ultimate pressure of the depressurizing means, so that an amount of gas corresponding to the dissolved amount of gas is generated on the secondary side of the orifice. . The generated gas is in a bubble state in water and forms a liquid phase and a gas-liquid two-phase flow and flows in the container. In this decompression process, the ultimate pressure of the decompression means and the temperature of the sample water are detected by the detection means.

A gas and a liquid phase in a gas-liquid two-phase flow flowing in the container are identified by the photoelectric sensor at the position of the detector. The photoelectric sensor outputs a signal corresponding to the passage of bubbles (for example, an on signal) and a signal corresponding to the passage of a liquid phase (for example, an off signal). In order to accurately identify the bubbles and the liquid phase, the gas-liquid two-phase flow is preferably a flow in which the cross section in the flow direction of the sample water is filled with bubbles in the container, that is, a slag flow. In order to form a slag flow, it is necessary to control the flow velocity of bubbles and the flow velocity of the liquid phase, and the orifice diameter and the cross-sectional area of the container in the flow direction of the sample water are set in a predetermined range in advance. Keep it. In order to prevent the sample water from boiling, it is preferable to adjust the ultimate pressure of the decompression means higher than the saturated vapor pressure of the sample water.

  The signal output from the photoelectric sensor is sent to the determination means, and the input time of the signal corresponding to the passage of the bubble is integrated for a predetermined measurement time. Next, the determination means obtains the gas generation rate from the ratio between the accumulated time and the measurement time. In this series of processes, when the sample water having a low dissolved gas concentration is to be measured, the gas generation rate can be accurately obtained by setting the measurement time to be long.

  In addition, the gas generation rate at a predetermined dissolved gas concentration is stored in advance in the determination means together with data regarding changes in the ultimate pressure of the decompression means and data regarding changes in the temperature of the sample water. The dissolved gas concentration of the sample water is determined based on the obtained gas generation rate, the ultimate pressure of the decompression means, and the temperature of the sample water. Incidentally, when the dissolved gas of the sample water is air, the dissolved oxygen concentration can be obtained by multiplying the determined dissolved gas concentration by the oxygen existing ratio in the air.

  Next, a sample water inlet and outlet are provided below the container, and the tip of the detection rod of the optical fiber sensor (one form of photoelectric sensor) is fixed at a position that secures a predetermined volume in the container. The case will be described.

  First, the container is filled with water in advance, and then the decompression means is operated. Then, the decompression line becomes negative pressure, and the sample water is sucked into the container through the orifice and flows toward the outlet. After passing through the orifice, the sample water is depressurized to the same or approximately the ultimate pressure of the depressurizing means, so that an amount of gas corresponding to the dissolved amount of gas is generated on the secondary side of the orifice. . The generated gas is in a bubble state in water, rises in the container by buoyancy, and is stored in the upper part of the container. In this decompression process, the ultimate pressure of the decompression means and the temperature of the sample water are detected by the detection means.

  The gas storage state in the container is identified by the photoelectric sensor at the tip of the detection rod. This photoelectric sensor outputs a signal (for example, an off signal) corresponding to a state where a predetermined volume of gas is not stored and a signal (for example, an on signal) corresponding to a state where a predetermined volume of gas is stored. Is done.

  The signal output from the photoelectric sensor is sent to the determination means. In this determination means, the time from when depressurization is started until a signal corresponding to the state where a predetermined volume of gas is stored is integrated. Next, the gas generation rate is determined from the ratio between the predetermined volume in the container and the accumulated time, and the gas generation rate is determined from the ratio between the gas generation rate and the flow rate of sample water into the container. . The flow rate of the sample water into the container is measured, for example, with a flow meter provided on the primary side of the orifice. In this series of processes, when sample water with a low dissolved gas concentration is to be measured, if the predetermined volume in the container defined by the tip position of the detection rod is set small, the gas generation rate is obtained. Can be shortened.

  In addition, the gas generation rate at a predetermined dissolved gas concentration is stored in advance in the determination means together with data regarding changes in the ultimate pressure of the decompression means and data regarding changes in the temperature of the sample water. The dissolved gas concentration of the sample water is determined based on the obtained gas generation rate, the ultimate pressure of the decompression means, and the temperature of the sample water. Incidentally, when the dissolved gas of the sample water is air, the dissolved oxygen concentration can be obtained by multiplying the determined dissolved gas concentration by the oxygen existing ratio in the air.

As described above, in this embodiment, since the measurement operation from collection of sample water to obtaining the determination value of dissolved gas concentration can be easily performed, automatic and continuous measurement can be realized. Can do. In particular, since a photoelectric sensor is used for gas detection, there is no problem in gas detection even when the sample water is closer to pure water, and the application range of the sample water can be expanded. Further, since the dissolved oxygen concentration is determined based on the signal from the photoelectric sensor, the pressure at which the sample water is decompressed, and the temperature of the sample water, the reliability of the measurement result can be improved.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. First, the first embodiment will be described with reference to FIG. This 1st Example is an example applied to the dissolved oxygen concentration measurement of the treated water in a deoxygenation apparatus.

  In FIG. 1, a deoxygenation apparatus 1 mainly includes a deaeration membrane module 2 in which a porous hollow fiber membrane is accommodated in a housing, a decompression means 3, a sealed water tank 4, and a heat exchanger 5. Yes. Here, the decompression means 3 is a water ring vacuum pump.

  The primary side of the deaeration membrane module 2 is connected to the raw water line 6, and the secondary side is connected to the treated water line 7. The treated water line 7 is provided with the heat exchanger 5. The deaeration side of the deaeration membrane module 2 is connected to the intake side of the decompression means 3 by a vacuum line 8.

  The sealed water tank 4 is connected to the water supply side of the decompression means 3 by a sealed water line 9. The sealed water line 9 passes through the heat exchanger 5 and is provided with a sealed water flow rate adjusting orifice 10. The sealed water tank 4 is connected to the exhaust side of the decompression means 3 through an exhaust line 11. Furthermore, the sealed water tank 4 is connected to the raw water line 6 and the refill water line 12, and an overflow line 14 is connected thereto. The makeup water line 12 is provided with a makeup water flow rate adjusting orifice 13.

  Here, the operation of the deoxygenation apparatus 1 will be described. In a state where raw water such as tap water, ground water, industrial water or pure water is supplied to the degassing membrane module 2 through the raw water line 6, the decompression means 3 is operated. Then, the vacuum line 8 becomes a vacuum, and the dissolved oxygen in the raw water is degassed to the vacuum line 8 side through the porous hollow fiber membrane, and is sequentially discharged from the exhaust line 11. The deaerated treated water flows through the treated water line 7 and is sent to a treated water tank (not shown).

  For the sealing water of the decompression means 3, a part of raw water is used. The raw water branched off from the raw water line 6 flows through the refill water line 12 while the flow rate is adjusted by the refill water flow rate adjusting orifice 13, and is stored in the sealed water tank 4 as sealed water. During operation of the pressure reducing means 3, the sealed water stored in the sealed water tank 4 flows through the sealed water line 9 while being adjusted in flow rate by the sealed water flow rate adjusting orifice 10, and is drawn into the pressure reducing means 3. Then, the sealed water is discharged from the exhaust line 11 together with the water brought in from the vacuum line 8 by the decompression means 3 and is returned to the sealed water tank 4.

  The sealed water flowing through the sealed water line 9 is heat-exchanged with the treated water in the heat exchanger 5. This is because in the pressure reducing means 3, the temperature of the sealed water rises and the saturated vapor pressure increases, and the ultimate pressure is reduced as the exhaust speed decreases. In the sealed water tank 4, the newly refilled raw water and the sealed water corresponding to the amount of water brought in from the vacuum line 8 are discarded from the overflow line 14 to the outside of the system.

  Next, the dissolved gas concentration measuring device 20 will be described. The dissolved gas concentration measuring device 20 mainly includes a container 21, a photoelectric sensor 22, and a detection means 23. Here, the detection means 23 is a temperature sensor.

  The container 21 has a cylindrical shape made of a transparent material, and is arranged so that the axial direction is substantially vertical. A sample water flow rate adjusting orifice 24 is connected to the lower end side of the container 21. The sample water flow rate adjusting orifice 24 is connected to the treated water line 7 and the sampling line 25. The collection line 25 passes through the sealed water tank 4. On the other hand, the upper end side of the container 21 is connected to the vacuum line 8 and the decompression line 26. That is, the inside of the container 21 can be decompressed by the decompression means 3. The decompression line 26 is provided with a downcomer 27.

  The photoelectric sensor 22 includes a light projecting body 28 and a light receiving body 29. One end of a light projecting optical fiber 30 is connected to the light projecting body 28, and one end of a light receiving optical fiber 31 is connected to the light receiving body 29. The other end of each of the optical fibers 30 and 31 is connected to a detector 32 disposed outside the container 21.

  The detection means 23 is provided in the sealed water tank 4 and can detect the temperature of the stored sealed water. The photoelectric sensor 22 and the detection unit 23 are connected to the determination unit 33 through a signal line.

  Here, the effect | action of the dissolved gas density | concentration measurement in the structure of said 1st Example is demonstrated. When the decompression means 3 is operated to degas the raw water, the inside of the container 21 and the decompression line 26 become negative pressure. Then, a part of the treated water flowing through the treated water line 7 is collected as sample water, and flows through the collection line 25, the container 21, and the decompression line 26. At the same time, the sample water is depressurized on the secondary side of the sample water flow rate adjusting orifice 24 to the same pressure as the ultimate pressure of the depressurization means 3 or to the same level, and the solubility of the dissolved gas is lowered to show a bubble state, It becomes a gas-liquid two-phase flow.

  In the process of depressurizing the sample water, the sample water is sucked into the intake side of the depressurization means 3, but the downcomer 27 acts as a buffer to stabilize the ultimate pressure of the depressurization means 3. Further, when the sample water flowing through the sampling line 25 passes through the sealed water tank 4, the sample water is heat-exchanged to the same temperature as the sealed water or to a similar temperature.

  In the process of reducing the sample water, the light emitted from the light projecting body 28 of the photoelectric sensor 22 is guided to the detector 32 through the light projecting optical fiber 30 and flows through the container 21. Fired. When the bubble passes through the position of the detector 32, the emitted light is reflected by the inner peripheral surface of the container 21 and is incident on the detector 32. The incident light is detected by the light receiving member 29 through the light receiving optical fiber 31. The photoelectric sensor 22 outputs an ON signal to the determination unit 33 when the light is detected by the light receiver 29. On the other hand, when the liquid phase passes through the position of the detector 32, the emitted light is diffused into the water in the container 21 and is not incident on the detector 32. The photoelectric sensor 22 outputs an off signal to the determination means 33 when the light receiver 29 does not detect light.

  Further, in the process of depressurizing the sample water, the temperature of the sealed water is detected by the detection means 23, and the detected value is output to the determination means 33. As described above, since the sample water is heat-exchanged to the same temperature as or the same as the sealed water, the determination unit 33 treats the temperature of the sealed water as the temperature of the sample water. Further, since the ultimate pressure of the decompression means 3 has a correlation with the temperature of the sealed water, the determination means 33 performs processing so as to obtain the ultimate pressure from the temperature of the sealed water based on data stored in advance.

In the determination means 33, the state in which the ON signal from the photoelectric sensor 22 is input is integrated for a predetermined measurement time (for example, about 10 seconds to 1 hour). And a gas production rate is calculated | required from the ratio of measurement time and the integration time of the input state of an ON signal. The determination unit 33 stores in advance the gas generation rate at a predetermined dissolved oxygen concentration together with data on the temperature change of the sample water and data on the ultimate pressure change of the decompression unit 3. The dissolved oxygen concentration of the sample water refers to these data, the gas generation rate, the temperature of the sample water obtained from the temperature of the above-mentioned seal water, and the ultimate pressure obtained from the temperature of the above-mentioned seal water It is determined based on. The determined dissolved oxygen concentration is sent to a control device (not shown) of the deoxygenation device 1 and used for information for determining an alarm.

  Next, a second embodiment will be described with reference to FIG. This 2nd Example is an example applied to the dissolved oxygen concentration measurement of the treated water in a deoxygenation apparatus like the 1st Example. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Now, the dissolved gas concentration measuring apparatus 20 in the second embodiment mainly includes a container 21, a photoelectric sensor 22, a first detection means 40, and a second detection means 41. Here, the first detection means 40 is a vacuum sensor, and the second detection means 41 is a temperature sensor.

  A sample water flow rate adjusting orifice 24 is connected to the bottom of the container 21, and the sample water flow rate adjusting orifice 24 is connected to the treated water line 7 and the sampling line 25. The bottom of the container 21 is connected to the vacuum line 8 and the decompression line 26. That is, the inside of the container 21 is configured to be depressurized using the depressurizing means 3. Furthermore, the upper part of the container 21 is connected to the vacuum line 8 and a drain line 42, and a drain valve 43 is provided in the drain line 42.

  In the photoelectric sensor 22, one end of a light projecting optical fiber 30 is connected to the light projecting body 28, and one end of a light receiving optical fiber 31 is connected to the light receiving body 29. The other end of each of the optical fibers 30 and 31 forms a detection rod 44 covered with a fluororesin, and this detection rod 44 is inserted into the container 21. Here, the tip end of the detection rod 44 is fixed at a position for securing a predetermined volume in the container 21.

  The decompression line 26 is provided with the first detection means 40, and the container 21 is provided with the second detection means 41. Furthermore, the sampling line 25 is provided with a flow rate detecting means 45. The photoelectric sensor 22, the first detection unit 40, the second detection unit 41, and the flow rate detection unit 45 are connected to the determination unit 33 through a signal line.

  Here, the effect | action of the dissolved gas density | concentration measurement in the structure of said 2nd Example is demonstrated. First, the drain valve 43 is opened at a timing when the decompression means 3 is not operating. Then, the treated water remaining in the treated water line 7 flows into the container 21 through the sampling line 25 due to water pressure. If bubbles remain in the container 21, the bubbles are discharged from the drain line 42. Then, the drain valve 43 is closed after a predetermined time when the inside of the container 21 is full.

  Next, when the decompression means 3 is operated to degas the raw water, the inside of the container 21 and the decompression line 26 become negative pressure. Then, a part of the treated water flowing through the treated water line 7 is collected as sample water, and flows through the collection line 25, the container 21, and the decompression line 26. At the same time, the sample water is depressurized on the secondary side of the sample water flow rate adjusting orifice 24 to the same pressure as the ultimate pressure of the depressurizing means 3 or to the same level, so that the solubility of the dissolved gas decreases and bubbles are generated. To do. Since the generated bubbles are stored in the upper part of the container 21 by buoyancy, the water level in the container 21 descends with time.

In the process of depressurizing the sample water, the light emitted from the light projecting body 28 of the photoelectric sensor 22 is guided to the detection rod 44 through the light projecting optical fiber 30 and is emitted into the container 21. When the tip of the detection rod 44 is in the water, the emitted light diffuses into the water, and no light is detected by the photoreceptor 29. In this state, the photoelectric sensor 22 outputs an off signal to the determination unit 33. On the other hand, when a predetermined amount of gas is stored in the container 21 and the water surface is lower than the tip of the detection rod 44, the emitted light is reflected inside the tip of the detection rod 44, and this reflection The detected light is detected by the light receiving body 29 through the light receiving optical fiber 31. In this state, the photoelectric sensor 22 outputs an ON signal to the determination unit 33.

  Further, in the depressurization process of the sample water, the ultimate pressure of the depressurization means 3, the temperature of the sample water, and the inflow amount of the sample water per time into the container 21 are respectively the first detection means 40, Detection is performed by the second detection unit 41 and the flow rate detection unit 45, and each detection value is output to the determination unit 33.

  The determination means 33 measures the time from the start of decompression until the ON signal is input from the photoelectric sensor 22, that is, the time until a predetermined volume of gas is stored. Then, the amount of gas generated per hour is calculated from the value of the capacity of the gas storage unit stored in advance in the determination means 33 and the time measured. Next, the gas production rate is obtained from the ratio between the amount of sample water flowing into the container 21 per hour and the amount of gas produced per hour. In addition, the determination unit 33 stores in advance the gas generation rate at a predetermined dissolved oxygen concentration together with data on the temperature change of the sample water and data on the ultimate pressure change of the decompression unit 3. The dissolved oxygen concentration of the sample water is determined based on the gas generation rate, the temperature of the sample water, and the ultimate pressure with reference to these data. The determined dissolved oxygen concentration is sent to a control device (not shown) of the deoxygenation device 1 and used for information for determining an alarm.

It is explanatory drawing of the 1st Example of this invention. It is explanatory drawing of the 2nd Example of this invention.

Explanation of symbols

3 Depressurization means 21 Container 22 Photoelectric sensor 23 Detection means
33 determination means 40 first detection means 41 second detection means
45 Flow rate detection means

Claims (3)

A container 21 for collecting sample water, a decompression means 3 for decompressing the sample water in the container 21, a gas generated by the decompression of the decompression means 3 and other liquid phases are detected as changes in light, And a detection means 23 for detecting the temperature of the sample water. Each of the photoelectric sensor 22 and the detection means 23 is determined via a signal line. The determination means 33 obtains the ultimate pressure of the decompression means 3 based on the temperature detection value of the sample water of the detection means 23, and generates gas based on the signal from the photoelectric sensor 22. obtains the rate, further wherein the determination means 33, and the gas production rate, and the temperature detection value of the water sample on the basis of said ultimate pressure, and wherein the determining the dissolved gas concentration of the sample water dissolved Body concentration measurement device. A container 21 for collecting sample water, a decompression means 3 for decompressing the sample water in the container 21, a gas generated by the decompression of the decompression means 3 and other liquid phases are detected as changes in light, Comprising a photoelectric sensor 22 that outputs a detection state within the measurement time as a signal, a first detection means 40 for detecting the ultimate pressure of the decompression means 3, and a second detection means 41 for detecting the temperature of the sample water, The photoelectric sensor 22, the first detection means 40, and the second detection means 41 are connected to a determination means 33 through signal lines, respectively, and the determination means 33 is based on a signal from the photoelectric sensor 22. The gas generation rate is obtained, and the determination unit 33 further determines the gas generation rate obtained based on the signal from the photoelectric sensor 22 and the ultimate pressure of the decompression unit 3 based on the signal from the first detection unit 40. The second is based on a signal from the detection means 41 based on the temperature detection value of the water sample dissolved gas concentration measuring apparatus characterized by determining the dissolved gas concentration of the sample water. A container 21 for collecting sample water, a decompression means 3 for decompressing the sample water in the container 21, a gas generated by the decompression of the decompression means 3 and other liquid phases are detected as changes in light, The photoelectric sensor 22 that outputs the detection state within the measurement time as a signal, the first detection means 40 that detects the ultimate pressure of the decompression means 3, the second detection means 41 that detects the temperature of the sample water, and the sample water Flow rate detecting means 45 for detecting the amount of inflow into the container 21 per time, and the photoelectric sensor 22, the first detecting means 40, the second detecting means 41 and the flow rate detecting means 45 are respectively signaled. The determination means 33 is connected via a line, and the determination means 33 is connected to the photoelectric
Based on the signal from the sensor 22 and the signal from the flow rate detection means 45, the gas generation rate is obtained, and the determination means 33 is further based on the signal from the photoelectric sensor 22 and the signal from the flow rate detection means 45. Based on the obtained gas generation rate, the ultimate pressure of the decompression means 3 based on the signal from the first detection means 40, and the temperature detection value of the sample water based on the signal from the second detection means 41, A dissolved gas concentration measuring apparatus for determining a dissolved gas concentration of sample water .

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