Water quality analysis device and power generation plant

Abstract

To provide a water quality analysis device and a power generation plant capable of measuring, in real time and continuously with high accuracy, the concentration of particles contained in sample water that includes fine particles having a particle size of 2 μm or less.SOLUTION: A water quality analysis device comprises: a measurement unit that optically measures the particle size and number of particles contained in sample water; and a calculation unit that calculates the concentration of particles contained in the sample water on the basis of the measured particle size and number of particles, and continuously and in real time calculates a corrected value of the concentration of particles contained in the sample water by correcting the calculated concentration of particles using a calibration curve. The calibration curve is prepared in advance on the basis of a correspondence between (A) a concentration of particles contained in the sample water, calculated on the basis of the particle size and number of particles obtained by measuring the sample water by the measurement unit, and (B) a concentration of particles contained in the sample water, calculated on the basis of the weight of collected particles after filtering the sample water being the analysis target and collecting the particles contained in the sample water.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water quality analyzer for analyzing the quality of water supplied to a boiler in a power plant such as a thermal power plant, and to a power plant having the same. [Background technology]

[0002] In power plants such as thermal power plants, water is supplied to a boiler, where it is converted into steam, which drives a turbine and generates electricity. The steam that drives the turbine is then cooled in a condenser, returning it to water, which is then fed back to the boiler. The water supplied to the turbine circulates through the power plant. However, because boilers and other equipment are made of metals such as steel and copper alloys, corrosion products from these metals can form and adhere to the boiler's heat transfer surfaces as scale, potentially reducing the boiler's thermal efficiency and increasing the tube wall temperature. To mitigate this risk, the amount of particles, such as corrosion products, contained in the water must be analyzed and understood as part of the water quality management system for the boiler.

[0003] From this perspective, at power plants such as thermal power plants, total iron concentration (iron particles, iron colloids, and iron ions) is measured and analyzed as a water quality control indicator during start-up and steady-state operation. However, because the total iron concentration during steady-state operation is low, there has been a demand for a device that can appropriately measure total iron concentration even when it is low. In response to this, in Patent Document 1, the applicant proposes a technology for calculating the total iron concentration with high precision, which uses a particle sensor to detect the particle size and number of particles contained in sample water collected from the plant's system water, calculates the number of particles for each particle size category, calculates the total volume of particles for each particle size category from the number of particles for each particle size category, multiplies the calculated total volume by the specific gravity of iron, and sums the total for all particle categories. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5534329 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, the water quality analyzer described in Patent Document 1 was able to calculate the total iron concentration in real time, continuously, and with high accuracy. However, the method described in Patent Document 1 had a problem in that the lower limit of the particle size of measurable iron particles was about 2 μm. However, during steady-state operation of a power plant such as a thermal power plant, the majority of the particles contained in the water supplied to the boiler or the water flowing through the boiler may be fine particles with a particle size of 2 μm or less. This meant that the concentration of particles contained in such sample water could not be measured in real time, continuously, and with high accuracy.

[0006] The present invention aims to provide a water quality analyzer and a power generation plant that can measure the particle concentration in sample water containing fine particles with a particle size of 2 μm or less in real time, continuously, and with high accuracy. [Means for solving the problem]

[0007] The water quality analysis device of the present invention has a measurement unit that continuously takes in sample water from the outside and continuously optically measures the particle size and number of particles contained in the sample water, and an arithmetic unit that calculates the concentration of particles contained in the sample water based on the particle size and number of the particles measured by the measurement unit, and continuously calculates a corrected value for the concentration of particles contained in the sample water by correcting the calculated particle concentration using a calibration curve.The calibration curve is a calibration curve created based on the correspondence between the concentration of particles (A) contained in the sample water to be analyzed, which is calculated in advance by measuring the sample water to be analyzed with the measurement unit and based on the particle size and number of particles measured by the measurement unit, and the concentration of particles (B) contained in the sample water, which is calculated in advance by filtering the sample water to be analyzed, collecting the particles contained in the sample water, and calculating it in advance based on the weight of the collected particles. The water quality analyzer may further include a flow pump that is capable of adjusting the flow rate of the sample water, and the flow pump may be a diaphragm pump. The water quality analyzer may be configured to include a relief valve that automatically opens when the water pressure of the sample water flowing inside the device exceeds a certain pressure. In the above-mentioned water quality analysis device, the measuring unit can be configured to measure the concentration of particles by irradiating light from a light source onto the sample water and receiving scattered light scattered by particles contained in the sample water. In the water quality analyzer, the concentration (B) can be calculated based on the weight of particles collected by passing sample water to be analyzed through a filter material over a number of days. A power plant according to the present invention includes a boiler and the water quality analyzer described above, which takes in a portion of water supplied to the boiler as sample water and measures the concentration of particles contained in the sample water. The power generation plant may further include a pump or a heater, and may be configured to take in a portion of the water supplied from the pump or the heater to the boiler as sample water and measure the concentration of particles contained in the sample water. [Effects of the Invention]

[0008] According to the present invention, by using a calibration curve created based on the correlation between the results of optically measuring the concentration of particles contained in sample water for calibration and the results of filtering the sample water for calibration to collect particles and measuring the weight of the collected particles, it is possible to measure the concentration of particles contained in sample water containing fine particles with a diameter of 2 μm or less in real time and continuously with high accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a case where a water quality analysis device according to an embodiment of the present invention is applied to a water circulation system of a power plant. [Figure 2]1 is a configuration diagram showing a water quality analysis device according to an embodiment of the present invention. [Figure 3] 1 is a graph showing an example of a calibration curve in the present embodiment. [Figure 4] This figure shows the relationship between the particle concentration (B: analytical value) contained in sample water measured using the suspended solids measurement method specified in JIS B 8224 and the particle concentration (C: corrected measurement value) contained in sample water corrected using a calibration curve. [Figure 5] FIG. 10 is a diagram showing the relationship between the concentration of particles contained in sample water before correction (A: measured value) and the output of the generator. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of a water quality analyzer according to the present invention will be described with reference to the drawings. The water quality analyzer according to the present invention is an apparatus for continuously measuring the concentration of particles contained in water or an aqueous solution to be analyzed in real time, and is characterized in that it can measure the particle concentration of the analysis target with high accuracy, even when the analysis target contains microparticles with a particle size of 2 μm or less. In the present invention, "real time" may include a delay of several seconds to several tens of seconds between the actual measurement time and the output time of the measurement result.

[0011] The following description will be given by way of example of a situation in which a water quality analysis device according to the present invention is applied to a water circulation system of a power plant 1, such as a thermal power plant. FIG. 1 is a schematic diagram of a case in which a water quality analysis device 10 according to this embodiment is applied to the water circulation system of the power plant 1, with solid lines indicating the flow of water and dashed lines indicating the flow of steam. As shown in FIG. 1, the power plant 1 has a boiler 20, a condenser 30, a condensate pump 40, a low-pressure heater 50, a feedwater pump 60, and a high-pressure heater 70. A portion of the water flowing from the high-pressure heater 70 to the boiler 20 is introduced into the water quality analysis device 10, where the quality of the water is analyzed.

[0012] More specifically, in the water circulation system of the power plant 1 according to this embodiment, a portion of the water heated to a high pressure and temperature by the high-pressure heater 70 is diverted and introduced into the water quality analyzer 10 via the diversion channel 90. The water quality analyzer 10 then measures the amount of corrosion products contained in the introduced water (hereinafter referred to as sample water). Note that the water that is not introduced into the water quality analyzer 10 flows from the high-pressure heater 70 to the boiler 20, where it is converted into steam. After rotating the turbine 80, the steam is converted back into water by the condenser 30, and the water passes through the condensate pump 40, the low-pressure heater 50, the feedwater pump 60, and the high-pressure heater 70. A portion of the water is measured by the water quality analyzer 10, while the remainder is converted into steam in the boiler 20 and reused to rotate the turbine 80.

[0013] Here, equipment such as a boiler 20 in a power plant 1, such as a thermal power plant, is generally made of metals such as steel and copper alloys, and corrosion products derived from these metals may be generated. When such corrosion products are carried to the heat transfer surfaces in the boiler 20 by the water circulating through the water circulation system of the power plant 1, they adhere to the boiler's heat transfer surfaces as scale, which may reduce the boiler's thermal efficiency or increase the tube wall temperature. Therefore, it is important to understand the amount (concentration) of corrosion products contained in the water supplied to the boiler 20 in the water circulation system of the power plant 1. However, particularly during steady-state operation of the power plant 1, such corrosion products are distributed in low concentrations as fine particles with a particle size of 2 μm or less, making them difficult to measure using conventional water quality analyzers.

[0014] The water quality analysis device 10 of this embodiment has the configuration described below, and can measure the concentration of these particles continuously and accurately in real time even when the sample water contains a low concentration of microparticles with a diameter of 2 μm or less, making it suitable for analyzing the water quality of water during steady-state operation of the power plant 1.

[0015] A water quality analysis device 10 according to this embodiment will be described with reference to Fig. 2. Fig. 2 is a configuration diagram showing the water quality analysis device 10 according to this embodiment. As shown in Fig. 2, the water quality analysis device 10 according to this embodiment has a valve 11, a flow pump 12, a relief valve 13, a flow meter 14, a control device 15, and a particle measuring device 16. Sample water to be analyzed continuously passes through the water quality analysis device 10, and the water quality analysis device 10 measures the concentration of particles contained in the sample water passing through the inside at regular time intervals.

[0016] Valve 11 is connected to a water distribution channel 90 that distributes water from outside the water quality analysis device 10, and collects sample water from outside the water quality analysis device 10. Valve 11 is, for example, a three-way valve, and is also connected to a flow path for introducing pure water, so that pure water can be introduced into the water quality analysis device 10 instead of introducing sample water into the water quality analysis device 10. The pure water is used for cleaning the particle measuring device 16, etc.

[0017] Flow pump 12 controls the flow rate of water flowing through water quality analysis device 10 under the control of control device 15. In particular, this embodiment is characterized by primarily measuring microparticles with a particle size of 2 μm or less. However, when measuring such microparticles, there is a problem that air bubbles contained in the sample water can affect the measurement as noise. For this reason, it is preferable to use a diaphragm pump as flow pump 12, which is less likely to generate air bubbles in the sample water flowing through water quality analysis device 10.

[0018] For example, a head cell can be used as a mechanism for introducing sample water into the water quality analysis device 10 at a constant flow rate. However, because a head cell is designed to expose the sample water to the atmosphere, there is a risk of air bubbles being introduced from the atmosphere. In contrast, a diaphragm pump is designed not to expose the sample water to the atmosphere, thereby effectively preventing the risk of air bubbles being introduced from the atmosphere. In this embodiment, to prevent the interior of the water quality analysis device 10 from being under negative pressure and drawing in outside air, the interior of the water quality analysis device 10 downstream of the diaphragm pump is pressurized by the diaphragm pump. Furthermore, because air bubbles are likely to be generated by negative pressure at the sample water intake section of the diaphragm pump, the pressure of the sample water is also pressurized upstream of the diaphragm pump, including the branch channel 90. If the pressure of the sample water in the branch channel 90 becomes excessively high, there is a risk of the piping becoming disconnected or the flow rate becoming too high. However, in this embodiment, when the pressure inside the water quality analysis device 10 (particularly on the upstream side of the diaphragm pump) becomes excessively high, the relief valve 13 automatically opens, thereby reducing the internal pressure. Furthermore, the diaphragm pump also has the function of controlling the flow rate of sample water introduced into the water quality analysis device 10 by controlling the operating speed of the pump shaft.

[0019] As described above, when the water pressure of the sample water flowing through the water quality analysis apparatus 10 reaches a certain pressure or more, the relief valve 13 automatically opens and discharges the sample water outside the system of the water quality analysis apparatus 10. This prevents the water pressure of the sample water flowing through the water quality analysis apparatus 10 from reaching a certain pressure or more. Furthermore, although the relief valve 13 is connected to a flow path for discharging the sample water to the outside when the sample water is pressurized, when the inside of the water quality analysis apparatus 10 is in a negative pressure state, the relief valve 13 functions as a check valve to prevent air from flowing back into the water quality analysis apparatus 10 from the flow path, thereby effectively preventing air from mixing with the sample water and causing bubbles to form in the sample water.

[0020] The flow meter 14 measures the flow rate of the sample water passing through the water quality analysis device 10 and transmits the measured flow rate value to the control device 15. Based on the flow rate value received from the flow meter 14, the control device 15 controls the operation of the flow pump 12 to maintain a constant flow rate within the water quality analysis device 10. For example, in this embodiment, the control device 15 controls the flow pump 12 so that the flow rate of the sample water flowing through the water quality analysis device 10 is 80 mL±5 mL / min, more preferably 80 mL±1 mL / min. The flow meter 14 is not particularly limited as long as it can appropriately measure the flow rate. Digital flow measuring devices such as differential pressure micro flow regulators and volumetric micro flow meters, and flow meters combining a float meter with image processing can also be used. However, in this embodiment, an ultrasonic flow meter is used. Ultrasonic flow meters are preferred as the flow meter 14 in this embodiment because they can be easily attached to the outside of piping, have little effect on the fluid, can be used with small diameters, are relatively inexpensive, and have high measurement accuracy.

[0021] The particle measuring instrument 16 is, for example, a particle counter, and optically measures the particle size and number of particles contained in the sample water. The particle measuring method is not particularly limited as long as it is an optical method, and measurement by a light shading method or a light scattering method is possible, for example. Note that the particle measuring instrument 16 according to this embodiment measures the particle size and number of particles contained in the sample water using a light scattering method (details of the measurement method using the light scattering method will be described later). A measurement method using the light scattering method can measure particles with smaller particle sizes than a measurement method using the light shading method, and is therefore suitable for measuring microparticles of 2 μm or less, as in this embodiment.

[0022] Specifically, the particle measuring instrument 16 has a light source, a cell, and an optical sensor, and is configured so that sample water introduced into the water quality analysis device 10 passes through the cell. The particle measuring instrument 16 detects the particle size and number of particles contained in the sample water that has passed through the cell by irradiating light from the light source onto the cell and receiving the scattered light by particles contained in the sample water that passes through the cell with the optical sensor. Specifically, when the optical sensor receives the scattered light that is scattered when the light irradiated from the light source collides with particles, it outputs an electrical signal corresponding to the scattered light. Each peak of the waveform of the electrical signal generated by the scattered light corresponds to a particle, and the number of peaks indicates the number of particles. Furthermore, since the larger the particle size of the particle, the greater the intensity of the electrical signal, so the particle measuring instrument 16 can also detect the particle size of each particle based on the intensity (intensity of each peak) of the electrical signal corresponding to the detected scattered light.

[0023] Furthermore, particle counter 16 has multiple channels according to particle size, and can divide each detected particle into particle size ranges (for example, 15 particle size ranges) based on the particle size of each particle, and calculate the number of particles in each range. Particle counter 16 then outputs the calculated number of particles for each range to control device 15. This allows control device 15 to calculate the weight of the particles based on the number of particles for each range and the average particle size in each range, and can calculate the concentration from the calculated particle weight and the volume of the sample water.

[0024] The control device 15 controls the operation of the flow pump 12. Specifically, the control device 15 controls the operation of the flow pump 12 based on the flow rate value measured by the flow meter 14, and controls the flow rate of the sample water flowing inside the water quality analysis device 10 so that the measurement of the sample water is performed at a constant flow rate.

[0025] The control device 15 also acquires from the particle measuring device 16 the particle size and number of particles contained in the sample water detected by the particle measuring device 16, and calculates the concentration of particles contained in the sample water based on the acquired particle size and number. Specifically, the control device 15 calculates the total volume of particles in each section when the particles are approximated as spheres from the number of particles and particle size in each section. Furthermore, the control device 15 multiplies the total volume of particles calculated for each section by the particle specific gravity to calculate the total weight of particles for each section, and then sums up the total weights of particles for each section to calculate the total weight of all detected particles. In this embodiment, the control device 15 can calculate the concentration (μg / L) of particles contained in the sample water by dividing the total weight of particles detected in the sample water by the volume of the sample water. An example of a calculation formula for the concentration of suspended solids based on this relationship is shown below. For example, the control device 15 can calculate the concentration of suspended solids using specific coefficients (particle size average coefficient βi and total concentration conversion coefficient α) as shown in the following formula. In the following formula, r i is the average particle size in each section i, and N i is the number of particles in each section i, and W mix is the particle density of the suspended matter, Q is the average flow rate, α is the total concentration conversion coefficient, β i is the conversion coefficient for each division i. Note that coefficients α and β i can be obtained in advance by experiment or the like.

number

[0026] In the above formula, the particle density W of the suspended matter mix can be set appropriately depending on the location where the water quality analysis device 10 is applied and the object to be measured. For example, in this embodiment, the water quality analysis device 10 is described as an example of analyzing the water quality of water circulating in a power plant 1 such as a thermal power plant. mixFor example, if the measurement target is mainly suspended solids in which iron and copper are mixed at a ratio of 8:2, the particle specific gravity W of the suspended solids can be calculated by using the specific gravity W of the suspended solids, which is the main component of corrosion products generated in the boiler 20 of the power plant 1. mix It can also be used as.

[0027] Furthermore, the control device 15 corrects the particle concentration in the sample water calculated based on the measurement results of the particle counter 16 using a calibration curve and outputs the corrected particle concentration. Specifically, the control device 15 stores a calibration curve in a memory unit (not shown) for correcting the particle concentration calculated based on the measurement results of the particle counter 16 (hereinafter also referred to as the particle concentration in the sample water measured using a light scattering method). FIG. 3 is a graph showing an example of the calibration curve in this embodiment. The calibration curve used in this embodiment is determined based on the correspondence between the particle concentration (A) in the sample water before correction, which is optically measured using a light scattering method, and the particle concentration (B) in the sample water, which is calculated based on the weight of the particles collected by passing the sample water through a filter (filtering material) for several days, based on the measurement method for suspended solids specified in JIS B 8224 (details will be described later).

[0028] In the graph shown in Fig. 3, the horizontal axis represents the particle concentration (A: measured value) (μg / L) contained in sample water optically measured using a light scattering method, and the vertical axis represents the particle concentration (B: analyzed value) (μg / L) contained in sample water previously measured using the suspended solids measurement method specified in JIS B 8224. In the example shown in Fig. 3, when calculating the particle concentration (A), the particle size and number of particles contained in sample water obtained by diverting a portion of the water actually supplied to boiler 20 of power plant 1 multiple times over several days were optically measured using a light scattering method with particle measuring instrument 16, the particle concentration in the sample water was calculated over time based on the measured particle size and number, and the average particle concentration over several days was obtained as the measured value (the value on the horizontal axis of the calibration curve, concentration (A)). Furthermore, during the same period as when the particle concentration (A) was calculated, sample water obtained by dividing a portion of the water actually supplied to the boiler 20 of the power plant 1 was passed through a filter, particles contained in the sample water were collected by the filter, and the weight of the collected particles (the difference in the change in weight including the filter) was calculated. The concentration (μg / L), which is the ratio of the weight of particles to the amount of sample water passed over several days, was calculated as the analytical value (the value on the vertical axis of the calibration curve, concentration (B)). A relationship line between concentration (A) and concentration (B) was then created to serve as the calibration curve according to this embodiment. The calculated calibration curve was stored in advance in the memory of the control device 15. In this embodiment, when measuring the concentration of particles contained in sample water using the JIS B 8224 method for measuring suspended solids, the sample water is passed through a filter material for several days. This is because the concentration of particles contained in the water supplied to the boiler 20 in the power plant 1 is generally low, and when the water is passed through for a short period of time, the amount of particles captured is small, and if the concentration is calculated based on the weight of a small amount of particles, the calculated concentration is likely to vary.In particular, JIS B 8224 specifies that the amount of suspended solids collected by the filter must be 2 mg or more in the measurement of suspended solids concentration, and if the concentration of suspended solids in the sample water is 0.5 μg / L, for example, 4000 L or more of the sample water must be filtered. In this case, if the flow rate of the water quality analyzer 10 is 200 ml / min, for example, the sample water must be passed through for approximately 7 days. In this way, by increasing the amount of suspended solids to be measured and the amount of sample water, it is possible to reduce variation in concentration and obtain a highly accurate calibration curve.

[0029] Here, we will explain the details of the measurement method for suspended solids specified in JIS B 8224. In this measurement method, suspended solids refer to the material remaining on the filter media when a sample is filtered. The weight of suspended solids in a sample is measured by drying the suspended solids remaining on the filter media at 105-110°C and measuring their weight. Specifically, an organic filter membrane with a pore size of 0.45 μm and a diameter of 47 mm is used as the filter media. The filter media is placed on a watch glass and heated at 105-110°C for approximately 1 hour. After cooling in a desiccator, the mass (X) of the filter media alone is measured. Next, the filter media is attached to a filter, and an appropriate amount of sample water is poured into the filter so that the amount of suspended solids after heating is 2 mg or more. The filter media is then subjected to suction filtration. Any material adhering to the sample container and filter tube walls is washed off onto the filter media with water, combined with the residual material on the filter media, and washed several times with water. The residue, along with the filter material, is carefully removed from the filter using tweezers or similar, transferred to a watch glass, and heated at 105-110°C for 2 hours. After cooling in a desiccator, the mass (Y) of the filter material and suspended solids is measured. The ratio of the weight of the suspended solids to the volume of sample water (the above mass (Y) - the above mass (X)) is then calculated as the particle concentration (μg / L) and plotted on a graph.

[0030] The control device 15 uses the stored calibration curve to correct the concentration of particles contained in the sample water optically measured and obtained from the particle measuring device 16. For example, in the example shown in Fig. 3, a calibration curve represented by a linear function is obtained, so that a correction value for the concentration of particles contained in the sample water can be calculated by multiplying the particle concentration obtained from the particle measuring device 16 by a coefficient corresponding to the slope of this linear function and adding a value corresponding to the intercept of the linear function to the concentration multiplied by the coefficient.

[0031] The control device 15 may also be configured to include an output device for outputting the corrected particle concentration of the sample water. For example, the control device 15 may have a display and display the corrected particle concentration of the sample water. In particular, in this embodiment, the control device 15 can calculate the corrected particle concentration (C) of the sample water simply by acquiring the particle concentration in the sample water optically measured by the particle counter 16 at any time and correcting it using a calibration curve. This allows the control device 15 to continuously display the corrected particle concentration of the sample water on the display. This allows the operator to monitor the water quality (particle concentration (C) in the water) of the water supplied to the boiler 20 of the power plant 1 in real time. The control device 15 may also be configured to connect to a printer or server wirelessly or wired, rather than just a display, to print the corrected particle concentration data of the sample water on the printer or send it to the server. When sending data to the server, the operator can access the server using their own information terminal (computer, smartphone, tablet, etc.) and obtain the output results from the server.

[0032] Furthermore, the control device 15 can be configured to control the flow pump 12 to maintain a constant flow rate, and measure the weight of particles contained in the water flowing over a fixed time period (e.g., one-minute intervals) to measure the weight of particles contained in the sample water for each fixed time period (e.g., one-minute intervals) as the particle concentration (μg / min) of the sample water. The control device 15 can also be configured to have a function of integrating the calculated particle concentration in the sample water in order to manage the amount of suspended solids flowing into the boiler 20. In this case, the control device 15 can be configured to output an alarm from an output unit provided in the control device 15 when the integrated value exceeds a reference value.

[0033] In addition, the water quality analysis device 10 of this embodiment has a particle measuring device 16 and a control device 15, so it can detect the concentration of particles contained in sample water with high accuracy, even if the sample water contains fine particles with a particle size of 2 μm or less.However, the particle size that can be measured by the water quality analysis device 10 of this embodiment is not limited to 2 μm or less, and it can also measure particles in the range of 0.5 to 20 μm or 0.1 to 100 μm, for example. [Example]

[0034] (Regarding the reliability of the calibration curve) First, the reliability of the calibration curve shown in Figure 3 was verified. Specifically, particles in a new sample water were measured using the particle measuring instrument 16, and the particle concentration (A) contained in the sample water was calculated based on the measurement results. The calculated concentration (A) was corrected using the calibration curve shown in Figure 3 to calculate the corrected concentration value (C). In addition, based on the measurement method for suspended solids specified in JIS B 8224, new sample water was passed through a filter (filtering material) for several days to collect particles, and the particle concentration (B) contained in the sample water was calculated based on the weight of the collected particles, and the correlation was determined. Here, Fig. 4 is a graph showing the correspondence between the corrected value (the corrected measurement value shown on the horizontal axis of Fig. 4, hereinafter also referred to as concentration (C)) obtained by correcting the particle concentration (A) contained in sample water optically measured using particle measuring instrument 16 shown in Fig. 3 using a calibration curve, and the particle concentration (the analytical value shown on the vertical axis of Fig. 4, concentration (B)) contained in sample water calculated based on the weight of the particles collected by passing the sample water through a filter (filter material) for several days, based on the measurement method for suspended solids specified in JIS B 8224. In Fig. 4, an approximate formula is calculated from the plot showing the correspondence relationship between concentration (B) and concentration (C), and the calculated approximate formula is displayed on the graph. As shown in Figure 4, the calculated approximation equation is a straight line with a slope of approximately "1", and it was found that the corrected measurement value (concentration (C)) obtained by correcting the particle concentration (A) contained in the sample water optically measured using the particle measuring instrument 16 detected in the example shown in Figure 3 using the calibration curve almost matches the analytical value (concentration (B)) calculated based on the measurement method for suspended solids specified in JIS B 8224. From this, it was confirmed that the particle concentration (C) corrected using the calibration curve almost matches the particle concentration (B) calculated based on the measurement method for suspended solids specified in JIS B 8224, and the reliability of the calibration curve shown in Figure 3 is high.

[0035] (Regarding the reliability of particle counter measurements) Furthermore, the reliability of the measurements of the particle counter 16 was also verified. It is generally known that as the output of the generator increases, the particle concentration in the sample water also tends to increase. Therefore, we verified whether there is a correlation between the generator output and the particle concentration in the sample water calculated by the particle counter 16. Figure 5 is a graph showing the relationship between the uncorrected particle concentration (A) in the sample water detected by the particle counter 16 and the generator output. In the example shown in Figure 5, it is shown that as the generator output increases, the particle concentration in the sample water increases, and as the generator output decreases, the particle concentration in the sample water decreases, confirming that the measurements of the particle counter 16 are also highly reliable.

[0036] 4 and 5, it was found that the particle concentration detected by the particle measuring instrument 16 is highly reliable, and that the corrected value obtained by correcting the particle concentration detected by the particle measuring instrument 16 using the calibration curve is also highly reliable. Therefore, it was found that the water quality analyzer 10 according to this embodiment can measure the particle concentration contained in sample water with high accuracy.

[0037] As described above, the water quality analyzer 10 according to this embodiment includes a particle measuring device 16 that optically measures the particle size and number of particles contained in sample water, and a control device 15 that calculates the particle concentration (A) contained in the sample water based on the particle size and number optically measured using the particle measuring device 16, and corrects the calculated particle concentration (A) using a pre-stored calibration curve. In particular, the calibration curve according to this embodiment is a calibration curve created based on the particle concentration (A) contained in the sample water optically measured using the particle measuring device 16 and the correspondence relationship between the particle concentration (A) contained in the sample water measured optically using the particle measuring device 16 and the measurement method for suspended solids specified in JIS B 8224, i.e., filtering the sample water with a filter material to collect particles contained in the sample water, determining the weight of the collected particles, and the particle concentration (B) calculated from the weight of the collected particles and the amount of sample water passed through the filter material. By using such a calibration curve to correct the particle concentration (A) of optically measured sample water, the particle concentration can be determined with high accuracy in real time and continuously, even when the particle concentration in the sample water is low and the particle size is small, between 0.5 μm and 2 μm. That is, as a conventional method for measuring particles (iron particles) in sample water in real time and continuously, a device has been provided, as disclosed in Patent Document 1, that measures the particle concentration in sample water based on the number and particle size measured by a particle counter and the iron density. However, such a device has the problem of being unable to measure the particle concentration in sample water containing small particles with a particle size of 2 μm or less with high accuracy. Furthermore, the measurement method for suspended solids specified in JIS B 8224 can measure the concentration of sample water containing small particles with a particle size of 0.5 μm to 2 μm with high accuracy, but requires filtering the sample water to collect the particles, which makes it impossible to measure the particle concentration in sample water in real time and continuously.In contrast, the water quality analysis device 10 of this embodiment uses a calibration curve created based on the correspondence between the results of optically measuring the particle concentration in sample water and the particle concentration in sample water determined using the suspended matter measurement method specified in JIS B 8224.This makes it possible to continuously calculate in real time a particle concentration that is close to the particle concentration measured using the suspended matter measurement method specified in JIS B 8224 based on the particle size and number detected by the particle measuring instrument 16.Therefore, even if the sample water contains a low concentration of mainly fine particles with a particle size of 2 μm or less, the particle concentration in the sample water can be determined in real time and continuously with high accuracy.

[0038] Furthermore, when measuring minute particles with particle sizes of 0.5 μm to 2 μm, it has been found that air bubbles contained in the sample water become noise, making it difficult to measure the particle concentration in the sample water with high accuracy. Therefore, in the water quality analysis device 10 according to this embodiment, a diaphragm pump is used as the flow pump 12 to maintain a constant flow rate of the sample water flowing into the water quality analysis device 10. Furthermore, this embodiment includes a relief valve 13. When the water pressure inside the water quality analysis device 10 exceeds a certain pressure, the relief valve 13 discharges the sample water from inside the water quality analysis device 10 to the outside, thereby preventing the water pressure inside the water quality analysis device 10 from exceeding the certain pressure. Furthermore, the relief valve 13 functions as a check valve to prevent air from entering from the outside, even when the water pressure inside the water quality analysis device 10 becomes negative, thereby effectively preventing air from mixing into the sample water flowing inside the water quality analysis device 10 and generating bubbles. In this way, in the water quality analysis device 10 of this embodiment, the water pressure inside the water quality analysis device 10 is maintained at a constant pressure (or a pressure greater than the constant pressure), thereby effectively preventing the generation of bubbles in the sample water, and even when measuring microparticles with a particle size of 0.5 to 2 μm or less, the influence of noise caused by bubbles is reduced, making it possible to measure the concentration of particles contained in the sample water with high accuracy.

[0039] Although the preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above-described embodiments. Various modifications and improvements can be made to the above-described embodiments, and such modifications and improvements are also included in the technical scope of the present invention.

[0040] In the above-described embodiment, the particle measuring instrument 16 transmits data on the particle size and number of particles contained in the sample water to the control device 15, and the control device 15 calculates the concentration of particles contained in the sample water based on the particle size and number of particles measured by the particle measuring instrument 16. However, the present invention is not limited to this configuration, and the particle measuring instrument 16 may also calculate the concentration (B) of particles contained in the sample water and transmit the calculated particle concentration (B) to the control device 15. The particle measuring instrument 16 may also store a calibration curve, correct the concentration (B) of particles contained in the sample water, and transmit the corrected particle concentration (C) to the control device 15. [Explanation of symbols]

[0041] 1...Power plant 10...Water quality analyzer 11...Valve 12...Flow pump 13...Relief valve 14...Flow meter 15...Control device 16...Particle counter 20...Boiler 30...Condenser 40...Condensate pump 50...Low pressure heater 60...Water supply pump 70...High pressure heater 80...Turbine 90…Diversion waterway

Claims

1. a measuring unit that continuously takes in sample water from the outside and optically measures the particle size and number of particles contained in the sample water; a calculation unit that calculates the concentration of particles contained in the sample water based on the particle diameters and number of the particles measured by the measurement unit, and corrects the calculated particle concentration using a calibration curve, thereby continuously calculating a corrected value of the concentration of particles contained in the sample water; The calibration curve is a calibration curve created based on the correspondence between the concentration (A) of particles contained in the sample water to be analyzed, which is calculated in advance by measuring the sample water with the measuring unit and based on the particle size and number of particles measured with the measuring unit, and the concentration (B) of particles contained in the sample water, which is calculated in advance by filtering the sample water to be analyzed, collecting the particles contained in the sample water, and based on the weight of the collected particles.

2. a flow pump capable of adjusting the flow rate of the sample water; The water quality analyzer of claim 1 , wherein the flow pump is a diaphragm pump.

3. 2. The water quality analyzer according to claim 1, further comprising a relief valve that automatically opens when the water pressure of the sample water flowing inside the analyzer exceeds a certain pressure.

4. The water quality analysis device according to claim 1 , wherein the measurement unit measures the concentration of particles by irradiating light from a light source onto the sample water and receiving scattered light scattered by particles contained in the sample water.

5. 2. The water quality analyzer according to claim 1, wherein the concentration (B) is calculated based on the weight of particles collected by passing sample water to be analyzed through a filter material over a number of days.

6. Boiler and 6. A power plant comprising: the water quality analyzer according to claim 1, which takes in a portion of the water supplied to the boiler as sample water and measures the concentration of particles contained in the sample water.

7. Further comprising a pump or a heater; The power plant according to claim 6 , wherein a part of the water supplied from the pump or the heater to the boiler is taken as sample water, and the concentration of particles contained in the sample water is measured.

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