JP2008111721A - Method and instrument for continuously measuring concentration of total organic carbon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous TOC concentration measuring instrument capable of always holding the concentration of TOC to a highly precise measuring state even during continuous use over a long time by stably keeping the passing flow rate of the measuring state constant even with respect to a small flow rate of a high-viscosity and high-temperature sample liquid while simplifying constitution to achieve the cost reduction of the whole of the measuring instrument. <P>SOLUTION: The continuous TOC concentration measuring instrument is constituted by incorporating a flow rate measuring part 5, which is constituted so that air is sucked in the measuring flow 7 of the sample liquid to be measured by the reversal of a tubing pump 6 and a present flow rate is measured from the time required in the flow of the sample liquid, which flows in a forward direction by the return to forward rotation thereafter, between two photosensors 14a and 14b, and a feedback-type flow rate control system 8 for automatically correcting the flow rate of the sample liquid on the basis of the measured flow rate. The measurement of the flow rate and the automatic correction operation of the flow rate are performed during continuous measurement periodically and automatically. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is suitable for water quality management such as the purity of pure water and pharmaceutical water used for semiconductor cleaning, for example, and is included in liquids used in various semiconductor manufacturing processes and pharmaceutical process processes. The present invention relates to a continuous TOC concentration measuring method and apparatus for continuously measuring the concentration of total organic carbon (hereinafter referred to as TOC) in organic components.

  As a continuous TOC concentration measuring apparatus of this type, as shown in the schematic flow chart of FIG. 7, a suction pump (not shown in FIG. 7) for sucking a sample liquid to be measured, and a suction by this pump are conventionally used. A reaction tube 21 having a quartz cell structure into which the sample solution is introduced, and a low-pressure UV lamp 22 that irradiates the sample solution flowing through the reaction tube 21 with ultraviolet rays (hereinafter referred to as UV) to oxidize organic components. A UV oxidation-conductivity detection type TOC concentration measurement unit 20 provided with two conductivity sensors 23, 23 installed before and after the reaction tube 21 to detect the conductivity of the sample solution before and after UV irradiation; A regulator 24 installed to keep the sample solution pressure substantially constant on the inlet side of the sample solution to the TOC concentration measuring unit 20, and a regulator 24 attached to the sending side of the TOC concentration measuring unit 20 4 linkage to the sample liquid flow rate a continuous TOC concentration measuring device composed of the orifice 25. such as flow meters 25a supplied needle valve kept constant is known (for example, see Patent Document 1). In FIG. 7, reference numeral 26 denotes a bypass passage branched and connected to the delivery side of the regulator 24, and a specific resistance meter 27 is interposed in the bypass passage 26.

  By the way, in the above-mentioned continuous TOC concentration measurement device of the UV oxidation-conductivity detection method, the flow rate and flow rate of the sample liquid passing through the TOC concentration measurement unit has a great influence on the UV oxidation efficiency, and thus the measurement accuracy. In order to stabilize the measurement value in the case of continuous measurement over a long period of time, the flow rate of the sample liquid passing through the measurement unit is measured, and the flow rate of the sample liquid passing through the measurement unit is previously determined based on the measurement flow rate. It is very important to maintain and maintain a constant flow rate that has been set, and in order to achieve this important matter, the conventional device shown in Patent Document 1 and the like displays the flow meter attached to the device as a measurer. Etc. are regularly read, and a method of manually adjusting the orifice opening of the needle valve or the like to correct the flow rate has been adopted.

JP 2004-177164 A

  However, in the conventional continuous TOC concentration measuring apparatus as proposed in Patent Document 1 above, the regulator does not operate normally unless the source pressure of the sample liquid is higher than, for example, 0.05 MPa. Since the stable pressure regulation function is not demonstrated, the flow rate of the sample liquid cannot be kept constant and the flow rate fluctuation is severe. Therefore, 5-10 ml / min. In the low flow rate range, the flow rate to be measured is unstable, and in some cases the flow rate may be stopped (zero). Therefore, the accuracy of the flow rate measurement itself is low, and as a result, the flow rate correction accuracy based on the measured flow rate is also low. Even if the flow rate is managed at a high frequency, there is a problem that the measurement accuracy of the intended TOC concentration varies greatly.

  In addition, a so-called turbine blade type flow meter configured to rotate a rotor of various shapes in a casing may be used as one suitable for flow measurement of a fluid (sample liquid) in a minute flow rate or a low flow rate range. This turbine wing type flow meter is not only complicated and expensive, but it is also sensitive to temperature and viscosity, and is used for measuring TOC concentration for a wide range of liquids such as high viscosity liquid and high temperature liquid. Not suitable for.

  The present invention has been made in view of the above-described circumstances, and its purpose is to simplify the configuration and reduce the cost of the entire apparatus. Even if it is a sample liquid, it is possible to measure the flow rate with high precision, and to maintain and manage the flow rate of the measurement part during long-term continuous measurement reliably and stably, so that the desired TOC concentration is always maintained. An object of the present invention is to provide a continuous TOC concentration measurement method and apparatus capable of maintaining a precise measurement state.

  In order to achieve the above object, a continuous TOC concentration measuring method according to the present invention includes a suction pump for sucking a sample liquid to be measured, and irradiating the sample liquid sucked by the pump with ultraviolet rays to the sample liquid. A measurement unit that oxidizes an organic component contained therein and measures a TOC concentration in the organic component based on a difference in conductivity of the sample solution before and after the ultraviolet irradiation, and a reduced pressure that maintains the pressure of the sample solution at a positive pressure And a continuous flow of the sample liquid at a set flow rate in a measurement flow formed by a mechanism to continuously measure the TOC concentration in the sample liquid, wherein the suction pump The suction pump is returned to the normal rotation to cause the sample liquid to flow in the forward direction, and the flow rate is determined from the time required for the flow of the sample liquid in a certain distance in the forward direction. Flow to measure And a flow rate control step of automatically correcting the passage flow rate of the sample liquid to the measurement unit to the set flow rate by adjusting the rotation speed of the suction pump based on the measured flow rate in the flow rate measurement step. (Claim 1).

  In order to achieve the same object as described above, the continuous TOC concentration measuring device according to the present invention irradiates the sample liquid sucked by the pump with ultraviolet light for sucking the sample liquid to be measured, and ultraviolet light. A measurement unit that oxidizes an organic component contained in the sample solution and measures a TOC concentration in the organic component based on a difference in conductivity of the sample solution before and after the ultraviolet irradiation, and a positive pressure of the sample solution A measurement flow is formed from the decompression mechanism that maintains the flow rate, and the sample liquid at a set flow rate is continuously flowed into the measurement flow, thereby continuously measuring the total organic carbon concentration in the sample liquid. A continuous TOC concentration measuring apparatus, wherein the suction pump is reversed in the measurement flow to suck air into the measurement flow, and then the suction pump is returned to the normal rotation again to flow the sample liquid in the forward direction. The flow rate measuring means for measuring the flow rate from the time required for the flow of the sample liquid in a forward direction in the forward direction, and the rotation speed of the suction pump is adjusted based on the measured flow rate by the flow rate measuring means, It is characterized by incorporating flow rate control means for automatically correcting the flow rate of the sample solution to the measurement unit to the set flow rate. (Claim 5)

  According to the first and fifth aspects of the present invention having the above-described characteristic configuration, the sample liquid is continuously flowed in the forward direction in the measurement flow, and the sample liquid having a set flow rate is supplied to the TOC concentration measurement unit. By allowing the TOC concentration in the sample liquid to pass continuously, the suction pump is reversed at any time during the continuous measurement, for example, when the flow rate by the suction pump decreases or fluctuates, It is possible to measure the current flow rate in the measurement flow without using an expensive flow meter and without extra effort, simply by introducing a simple pump rotation direction switching means that rotates forward again. By the flow rate correction based on the measured flow rate, the flow rate of the measurement flow can be automatically and accurately maintained at the initial set flow rate. In particular, by adopting the above-described pump rotation direction switching means and the flow rate measuring means for measuring the flow rate from the time required for the flow of the sample liquid over a certain distance, 5 to 10 ml / min. Even if the sample liquid is set to a small flow rate range, high viscosity liquid or high temperature liquid, it is within a narrow tolerance range (± 3%, refer to the experimental results described later). Therefore, the flow rate of the sample liquid in the TOC concentration measurement unit can be stabilized. Therefore, although it is simple and low-cost without using a special flow meter, there is an effect that an intended TOC concentration measurement can always be kept in a precise state in continuous measurement over a long period of time.

  In the present invention, a variable flow rate tubing pump is used as the suction pump, and a single capillary is used as the pressure reducing mechanism (Claims 2 and 6). , Particle particles, etc.) and fluctuations in flow rate due to the influence of bubbles can be suppressed, and a small flow rate of sample liquid can be passed stably through the TOC concentration measurement unit. In addition, the accuracy of continuous measurement of the TOC concentration can be further improved.

  Further, in the present invention, the flow rate measurement step and the flow rate control step are automatically and periodically performed at predetermined time intervals in the continuous measurement step, that is, the flow rate measurement unit and the flow rate control unit are It is desirable to be programmed to operate periodically at predetermined time intervals during continuous measurement (claims 3 and 7). In this case, there is no need for the operator to read the flow meter for flow rate management and manually correct the flow rate accordingly, and even if it is forgotten, the predetermined measure during continuous measurement is not required. Since the flow rate measurement and flow rate correction are automatically and periodically performed at the time intervals of, high-precision TOC concentration measurement can be reliably maintained even when continuous measurement is performed over a long period of time without maintenance.

  Furthermore, in the present invention, for the flow rate measurement in the flow meter side step, a spherical measuring tube connected to the measurement flow, two photosensors provided at the entrance and exit of the measuring tube, and a sample by the two photosensors By using a flow rate measuring means comprising an input time difference of the liquid detection signal and a calculation unit for calculating the flow rate of the sample liquid from the spherical measuring tube volume (claims 4 and 8), the flow rate measurement accuracy is further improved. be able to. That is, reproducibility of accurate flow rate measurement can be ensured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a continuous TOC concentration measuring apparatus used in a continuous TOC concentration measuring method according to the present invention. This continuous TOC concentration measuring apparatus 1 has a sample liquid supply port portion 2a for supplying a sample liquid A to be measured from the bottom and a discharge port portion 2b for discharging the sample liquid A to an overflow state. An overflow tank 2 for storing the sample liquid, a suction pump 3 for sucking the sample liquid A from the overflow tank 2, and UV irradiation of the sample liquid A sucked by the suction pump 3 to irradiate the organic matter contained in the sample liquid. A measurement unit 4 that measures the TOC concentration in the organic component based on a difference in conductivity of the sample solution before and after the UV irradiation, a flow rate measurement unit 5 that measures the flow rate of the sample solution A, and the sample A sampling measurement flow 7 is formed from the decompression mechanism 6 that maintains the pressure of the liquid A at a positive pressure, and the sample liquid A is continuously flowed into the sampling measurement flow 7, whereby T in the sample liquid A And it is configured so that the C concentration measured continuously. In FIG. 1, reference numeral 9 denotes a three-way valve for introducing a calibration solution into the sampling measurement flow 7 in order to calibrate the device 1 before using the continuous TOC concentration measuring device 1.

  As shown in FIG. 2, the TOC concentration measuring unit 4 applies UV to a spiral quartz tube or a reaction tube 4A having a quartz cell structure with a cell length of 1 to 3 mm and a sample liquid A flowing through the reaction tube 4A. A low-pressure UV lamp 4B of about 3 to 15 W to be irradiated and two conductivity sensors 4C and 4C which are respectively installed before and after the reaction tube 4A and detect the conductivity of the sample solution before and after the UV irradiation, By calculating the difference in conductivity before and after UV irradiation detected by the conductivity sensors 4C and 4C, the TOC concentration in the organic component oxidized by UV irradiation is measured.

  As the suction pump 3, the maximum discharge pressure capacity is 0.3 to 0.4 MPa, and the use discharge pressure is set in the range of 0.03 to 0.08 MPa, which is about 1/10 to 1/20 of the maximum discharge capacity. A variable flow rate tubing pump is used. Between the tubing pump 3 and the flow rate measuring unit 5, the flow rate of the sampling measurement flow 7 is automatically corrected to the initial set flow rate based on the measured flow rate by the flow rate measuring unit 5 having a specific configuration as described later. As shown, a feedback flow rate control system 8 including a controller (CPU, hereinafter referred to as CPU) 8A that automatically adjusts the roller rotation speed of the tubing pump 3 is provided.

  As the decompression mechanism 6 for maintaining the pressure of the sample liquid A in the sampling measurement flow 7 at a positive pressure, it is one of gradually decompression type decompression mechanism parts, and a single capillary as a throttling mechanism is used. The single capillary 6 has a flow rate of 5 to 10 ml / min. In the set use range (0.03 to 0.08 MPa) of the discharge pressure of the tubing pump 3 described above. In the sampling measurement flow 7, a condition that air bubbles are not generated and a sufficient pressure to smoothly pass and discharge without adhering air bubbles and minute foreign matters can be maintained, and such a pressure is set. In order to satisfy both the length defined by Hagen-Poiseuille's law, specifically the fourth power of the inner diameter ratio, that is, the length of 16 times the inner diameter, the inner diameter is 0.5 mm. / The outer diameter is 1.5 mm and the length is about 100 to 10,000 mm, preferably the inner diameter is 0.5 mm / the outer diameter is 1.5 mm and the length is set to a size of 500 to 1000 mm. Incidentally, when a single capillary having an inner diameter of 1.0 mm is used, the length becomes 800 to 10000 mm. Even when the capillary is used in a straight line, it is bundled in a space several times in the space in the apparatus. Even when stored, there is a problem that a large space is required and the material cost is increased.

  The flow rate measuring unit 5 is configured as follows. That is, an air suction trap 12 is connected to a sampling measurement flow 7 downstream of the TOC concentration measuring unit 4 through a three-way switching valve 10 and an air pipe 11, and the three-way switching valve 10 and the TOC concentration measurement. A glass bulb measuring tube 13 is connected in series to the portion 7 of the sampling measurement flow 7 between the photosensors 14a and 14b at the inlet / outlet portion of the glass bulb measuring tube 13, that is, the upstream portion and the downstream portion, respectively. It is attached. In the flow rate measuring unit 5, the glass bulb measuring tube 13 is moved forward (in the direction of the arrow x in FIG. 1) in accordance with the switching operation of the three-way switching valve 10 and the forward / reverse switching operation of the tubing pump 3 as described later. ) Are sequentially detected by the two photosensors 14a and 14b, and the two sample liquid level detection signals Sa and Sb are input to the CPU 8A serving as a calculation unit, whereby the glass bulb The input time difference between the volume (known) of the measuring tube 13 and the sample liquid level detection signals Sa and Sb, that is, the two photosensors 14a and 14b to which the sample liquid is attached at a predetermined distance in the forward direction x. The flow rate of the sample solution is calculated and measured from the time required to flow.

  The flow rate measuring unit 5 and the feedback flow rate control system 8 are configured in a signal system as shown in FIG. 3 with the CPU 8A as a center. That is, the three-way switching valve 10 is switched between a first state in which the air suction trap 12 is connected to the glass bulb measuring tube 13 and a second state in which the connection between the two and 13 is cut off by a switching signal S1 transmitted from the CPU 8A. It is configured to be switched. The driving stepping motor (not shown) for driving the tubing pump 3 is switched between the normal rotation state and the reverse rotation state by the normal rotation / reverse rotation command signal S2 transmitted from the CPU 8A, and the flow rate measuring unit 5 The number of rotations of the roller is controlled by a pulse signal S3 transmitted from the CPU 8A based on the measured flow rate at, and the sample solution flow rate passing through the TOC concentration measuring unit 4 is automatically corrected to the initial set flow rate. Yes.

  The flow rate measurement unit 5 and the feedback flow rate control system 8 automatically and periodically perform sequential operations such as flow rate measurement and flow rate correction based on the measurement result at predetermined time intervals during normal continuous TOC concentration measurement. Has been programmed to be done. The programmed time interval is suitably about once every 2 to 4 weeks within a period in which the flow rate of the tubing pump 3 decreases or fluctuates.

Next, the operation of the continuous TOC concentration measuring apparatus 1 will be described.
Normally, as shown in FIG. 4A, the three-way switching valve 10 is switched to the second state described above, and the tubing pump 3 is kept in the forward rotation state, and the tubing pump 3 overflows. When the sample solution A sucked from the tank 2 flows through the sampling measurement flow 7 in the forward direction x at a set flow rate and passes through the TOC concentration measuring unit 4, the TOC concentration in the sample solution A is continuously measured.

  When the measurement in the normal measurement state has elapsed for a predetermined time, the switching signal S1 from the CPU 8A switches the three-way switching valve 10 to the first state described above as shown in FIG. In response to the reverse rotation command signal S2, the tubing pump 3 reverses and the air is sucked into the glass bulb measuring tube 13 in the flow rate measuring unit 5 through the air suction trap 12 and the pipe 11, and together with the sucked air in the sampling measurement flow 7 The sample liquid flows in the reverse direction y.

  The state shown in FIG. 4B is maintained until the front end surface of the sample liquid flowing in the reverse direction y is detected by the upstream photosensor 4a, and the front end surface of the sample liquid is the upstream photosensor. When the detection signal Sa is detected by 4a and input to the CPU 8A, the three-way switching valve 10 is switched to the first state as shown in FIG. 4C by the switching signal S1 from the CPU 8A. The tubing pump 3 returns to normal rotation by the normal rotation command signal S2 from the CPU 8A, and the sample liquid starts to flow in the forward direction x again.

  Subsequently, when the downstream photosensor 4b detects the front end surface of the sample liquid flowing in the forward direction x and the detection signal Sb is input to the CPU 8A, the volume (known) of the glass bulb measuring tube 13 and the above-mentioned The flow rate is calculated from the difference in input time between the sample liquid detection signals Sa and Sb, that is, the time required for the sample liquid to flow in the forward direction x between the two photosensors 14a and 14b attached at a certain distance. The current sample solution flow rate in the sampling measurement flow 7 is measured.

  Then, the CPU 8A compares the current flow rate measured by the flow rate measurement unit 5 with the initial set flow rate, and the rotation speed of the stepping motor is controlled by the pulse signal S3 transmitted from the CPU 8A based on the flow rate difference. The roller rotation speed of the tubing pump 3 is adjusted, and the sample solution flow rate passing through the TOC concentration measurement unit 4 is automatically corrected to the initial set flow rate.

  After the flow rate measurement and the automatic flow rate correction control based on the measured flow rate are completed, the normal TOC concentration continuous measurement state as shown in FIG. When the measurement has elapsed for a predetermined time, the same flow rate measurement and automatic flow rate correction control as described above are performed again.

  As described above, a simple pump rotation direction switching means for continuously measuring the TOC concentration in the sample solution and rotating the tubing pump 3 in the reverse direction at every predetermined time interval during the continuous measurement and introducing the forward rotation again is introduced. Therefore, the flow rate of the sampling measurement flow 7 is measured by measuring the current flow rate in the sampling measurement flow 7 without using an expensive flow meter and without requiring extra labor, and by correcting the flow rate based on the measurement flow rate. It is possible to maintain the initial set flow rate automatically and accurately. As a result, the flow rate of the sample solution in the TOC concentration measuring unit 4 can be always stabilized, and the desired TOC concentration measurement can always be kept in a precise state in continuous measurement over a long period of time.

  In particular, by adopting flow rate measuring means for measuring the flow rate from the pump rotation direction switching means and the time required for flow of the sample liquid over a certain distance, even if it is 5 to 10 ml / min. Even if the sample liquid is set to a small flow rate range, or even if the sample liquid is high viscosity or high temperature, the flow rate can be measured with high accuracy within the narrow tolerance range. The flow rate of the sample liquid in the TOC concentration measurement unit can be stabilized, and the measurement accuracy of the TOC concentration can be kept very high.

  Further, as in the present embodiment, by using the variable flow rate tubing pump 3 as a suction pump and the single capillary 6 as a pressure reducing mechanism, bubbles and minute foreign matters are mixed even under low pressure conditions. Even if it is, it is possible to pass a small amount of sample liquid stably through the TOC concentration measuring unit while suppressing fluctuations in the flow rate, while reducing the frequency of the above-described flow rate measurement and the flow rate correction based thereon. Further, the continuous measurement accuracy of the TOC concentration can be further improved.

  Incidentally, in order to confirm the measurement accuracy by the flow rate measuring unit 5 using the glass bulb measuring tube 13 and the two photosensors 14a and 14b, the present inventors set an initial flow rate of 7.5 ml / min. Under these conditions, the flow measurement test was performed about 80 times, and the test results as shown in FIG. 5 were obtained.

From the results shown in FIG. The variation rate of the measured value at, that is, (maximum value−minimum value) / average value × 100,
7.58-7.45 = 0.13
0.13 / 7.52 × 100 = 1.73 (%)
5-10 ml / min. It was confirmed that even if the sample liquid was set to a small flow rate range, it was possible to measure the flow rate with a high degree of accuracy within the narrow allowable error range (± 3%).

  Further, a test for automatically correcting the sample liquid flow rate in the sampling measurement flow 7 based on the above flow rate measurement result is repeated almost periodically, and as a result, continuous data with pump flow rate correction as shown in FIG. Got.

  As a result, the change in flow rate is about −3% in 2 weeks. Therefore, if flow measurement and flow rate correction are performed about every 2 weeks, the change in flow rate is very little even in continuous use over a long period of time. It was found that the desired TOC concentration measurement accuracy can always be kept high.

  In the above-described embodiment, the continuous sampling measurement flow has been described. However, the same effect can be obtained even when applied to the batch sampling measurement flow.

  In addition, the use of a tubing pump is optimal as the suction pump, but the invention is not limited to this, and any pump can be used as long as it can switch between forward and reverse rotations and has a variable flow rate. However, the present invention is not limited to this, and an orifice such as a needle valve may be used.

It is a schematic block diagram of the continuous TOC concentration measuring apparatus used for the continuous TOC concentration measuring method which concerns on this invention. It is an enlarged block diagram of a TOC density | concentration measurement part. It is a schematic signal system diagram of a flow measurement part and a feedback type flow control system. (A)-(C) are operation | movement explanatory drawings. It is a graph which shows a flow measurement test. It is a graph which shows the result of the automatic correction | amendment test of a sample liquid flow rate. It is a schematic flowchart of the conventional TOC concentration measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Continuous TOC concentration measuring device 2 Overflow tank 3 Tubing pump 4 TOC concentration measuring part 4A Reaction tube 4B Low pressure UV lamp 4C Conductivity sensor 5 Flow meter side part 6 Single capillary 7 Sampling measurement flow 8 Feedback type flow control system (flow rate) Control means)
8A CPU
13 Glass bulb measuring tube 14a, 14b Photosensor A Sample solution

Claims (8)

A suction pump that sucks the sample liquid to be measured, and the sample liquid sucked by this pump is irradiated with ultraviolet rays to oxidize organic components contained in the sample liquid, and the conductivity of the sample liquid before and after the ultraviolet irradiation is measured. The sample liquid at a set flow rate is continuously connected to a measurement flow formed by a measurement unit that measures the total organic carbon concentration in the organic component based on the difference and a pressure reducing mechanism that maintains the pressure of the sample liquid at a positive pressure. Is a method of continuously measuring the total organic carbon concentration in the sample liquid by flowing it,
During the continuous measurement process, after the suction pump is reversed and air is sucked into the measurement flow, the suction pump is returned to the normal rotation to cause the sample liquid to flow in the forward direction, and the constant distance of the sample liquid in the forward direction. The flow rate measuring step for measuring the flow rate from the time required for the flow between and the flow rate of the sample liquid to the measurement unit by adjusting the number of rotations of the suction pump based on the measured flow rate in the flow rate measuring step A continuous total organic carbon concentration measuring method characterized by performing a flow rate control step of automatically correcting the flow rate.   The continuous total organic carbon concentration measuring method according to claim 1, wherein a variable flow rate type tubing pump is used as the suction pump, and a single capillary is used as the pressure reducing mechanism.   3. The continuous total organic carbon concentration measuring method according to claim 1, wherein the flow rate measurement step and the flow rate control step are automatically and periodically performed at predetermined time intervals in the continuous measurement step.   For the flow rate measurement in the flow rate measurement step, a spherical metering tube connected to the measurement flow, two photosensors provided at the entrance and exit of the metering tube, a difference in input time between sample liquid detection signals by the two photosensors, and The continuous total organic carbon concentration measuring method according to any one of claims 1 to 3, wherein a flow meter side means comprising a calculation unit for calculating the flow rate of the sample liquid from the spherical measuring tube volume is used. A suction pump that sucks the sample liquid to be measured, and the sample liquid sucked by this pump is irradiated with ultraviolet rays to oxidize organic components contained in the sample liquid, and the conductivity of the sample liquid before and after the ultraviolet irradiation is measured. A measurement flow is formed from a measurement unit that measures the total organic carbon concentration in the organic component based on the difference, and a decompression mechanism that maintains the pressure of the sample liquid at a positive pressure, and the sample at a set flow rate is formed in this measurement flow A continuous total organic carbon concentration measuring device configured to continuously measure the total organic carbon concentration in the sample liquid by continuously flowing the liquid,
The suction pump is reversed in the measurement flow and air is sucked into the measurement flow, and then the suction pump is returned to the normal rotation again to cause the sample liquid to flow in the forward direction. The flow rate measuring means for measuring the flow rate from the time required for the flow between distances, and the setting of the flow rate of the sample liquid to the measurement unit by adjusting the rotation speed of the suction pump based on the measured flow rate by the flow rate measuring means A continuous type total organic carbon concentration measuring device incorporating flow rate control means for automatically correcting the flow rate.   6. The continuous total organic carbon concentration measuring apparatus according to claim 5, wherein a variable flow rate tubing pump is used as the suction pump, and a single capillary is used as the decompression mechanism.   The continuous total organic carbon concentration measuring apparatus according to claim 5 or 6, wherein the flow rate measuring means and the flow rate control means are programmed so as to operate periodically at predetermined time intervals during continuous measurement.   The flow rate measuring means includes a spherical measuring tube connected to the measurement flow, two photosensors provided at the inlet / outlet of the measuring tube, a difference in input time between sample liquid detection signals by the two photosensors, and the spherical measuring tube. The continuous total organic carbon concentration measuring apparatus according to any one of claims 5 to 7, comprising a calculation unit that calculates the flow rate of the sample liquid from the volume.

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