Plant water quality control device, plant, and plant water quality control method

Abstract

To provide a water quality management device of a plant, a plant, and a water quality management method of a plant which can effectively suppress occurrence of scale and corrosion in the plant.SOLUTION: The water quality management device of the plant comprises: a measuring unit for measuring a state quantity indicating a state of cooling water of the plant; and a concentration estimation unit for estimating a concentration of a solute or an ion in the cooling water based on the measured state quantity using a prediction formula that expresses a relation between the concentration of the solute or the ion in the cooling water and the state quantity.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a water quality control device for a plant, a plant, and a water quality control method for a plant. [Background technology]

[0002] In a plant, the quality of plant water such as cooling water can cause problems such as adhesion of scale to equipment and corrosion of the equipment. Therefore, it is required to appropriately suppress the occurrence of scale and corrosion in the plant.

[0003] Patent Document 1 discloses a scale monitoring method for monitoring the occurrence of scale in a water system of a plant, etc. This method utilizes the fact that when scale adheres to an electrode, the effective electrode area decreases and electrical conductivity drops, and evaluates the amount of scale adhered to the surface of an electrode immersed in the water system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5928096 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in order to effectively suppress the generation of scale and corrosion, it is necessary to properly grasp the risk of the generation of scale and corrosion. However, the method of Patent Document 1 evaluates the amount of scale adhesion, but does not evaluate the risk of scale generation in advance. For this reason, it is difficult to avoid the generation of scale using the method of Patent Document 1.

[0006] In view of the above circumstances, at least one embodiment of the present invention aims to provide a water quality control device for a plant, a plant, and a water quality control method for a plant that can effectively suppress the occurrence of scale and corrosion in the plant. [Means for solving the problem]

[0007] A water quality control device for a plant according to at least one embodiment of the present invention includes: A measuring unit for measuring a state quantity indicating a state of the cooling water of the plant; a concentration estimation unit configured to estimate a concentration of the solute or the ion in the cooling water based on the measured state quantity by using a prediction equation expressing a relationship between the concentration of the solute or the ion in the cooling water and the state quantity; Equipped with.

[0008] Moreover, the plant according to at least one embodiment of the present invention comprises: A heat exchanger; a cooling water circulation line configured to circulate the cooling water supplied to the heat exchanger; The water quality control device described above is configured to control the quality of the cooling water; Equipped with.

[0009] Further, a method for managing water quality in a plant according to at least one embodiment of the present invention includes: Measuring a state quantity indicative of a state of cooling water in a plant; A step of estimating a concentration of the solute or the ion in the cooling water based on the measured state quantity using a prediction equation expressing a relationship between the concentration of the solute or the ion in the cooling water and the state quantity; Equipped with. Effect of the Invention

[0010] According to at least one embodiment of the present invention, there are provided a water quality control device for a plant, a plant, and a water quality control method for a plant, which are capable of effectively suppressing the occurrence of scale and corrosion in the plant. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram of a plant according to an embodiment. FIG. [Diagram 2] 1 is a schematic configuration diagram of a water quality control device according to an embodiment. [Diagram 3] 1 is a flowchart of a water quality management method according to an embodiment. [Figure 4] 1 is a flowchart of a water quality management method according to an embodiment. [Diagram 5] 1 is a flowchart of a water quality management method according to an embodiment. [Figure 6] 1 is a flowchart of a water quality management method according to an embodiment. [Figure 7] FIG. 11 is a diagram for explaining correction of a prediction formula according to an embodiment. [Figure 8] FIG. 11 is a diagram for explaining correction of a prediction formula according to an embodiment. [Figure 9] FIG. 11 is a diagram for explaining correction of a prediction formula according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0013] (Plant configuration) Fig. 1 is a schematic diagram of an example of a plant to which a water quality management device according to some embodiments is applied. The plant 100 shown in Fig. 1 includes a boiler 14 for generating steam, a turbine 16 to which the steam from the boiler 14 is supplied, and a condenser 18 to which the steam from the turbine 16 is guided.

[0014] The boiler 14 is supplied with water (condensed water) from the condenser 18 via a water supply line 12 provided between the boiler 14 and the condenser 18. A water supply pump 13 for pumping the water is provided in the water supply line 12. The boiler 14 is configured to heat the water supplied from the water supply line 12 to generate steam.

[0015] The turbine 16 is configured to be driven by steam from the boiler 14. The rotor of the turbine 16 may be connected to an electric generator 17. That is, the turbine 16 may be driven by the steam to drive the electric generator.

[0016] The condenser 18 is configured to cool and condense the steam that has completed work in the turbine 16. The condenser 18 includes a heat exchanger configured to cool the steam by heat exchange with cooling water.

[0017] The plant 100 further includes a cooling water circulation line 22 through which the cooling water supplied to the condenser 18 (heat exchanger) circulates, a cooling tower 20 provided on the cooling water circulation line 22, and a water quality control device 50 for controlling the quality of the cooling water. A cooling water pump 24 for pumping the cooling water is provided on the cooling water circulation line 22.

[0018] The cooling water used to cool the steam in the condenser 18 (heat exchanger) is guided to the cooling tower 20 via a cooling water circulation line 22. The cooling tower 20 is configured to cool the cooling water, whose temperature has been raised by heat exchange with the steam in the condenser 18, by air, for example. The cooling water cooled in the cooling tower 20 is supplied again to the condenser 18 via the cooling water circulation line 22.

[0019] A drain line 26 for discharging a portion of the cooling water flowing through the cooling water circulation line 22 is connected to the cooling water circulation line 22. The drain line 26 is provided with a drain valve 28 for adjusting the amount of water discharged through the drain line 26.

[0020] Further, a make-up water line 30 is connected to the cooling water circulation line 22 for supplying make-up water from a make-up water source to the cooling water in the cooling water circulation line 22. A make-up water pump 32 is provided in the make-up water line 30 for pumping the make-up water to the cooling water circulation line 22. The make-up water may include river water or industrial water. In the exemplary embodiment shown in FIG. 1, the make-up water line 30 is connected to the cooling tower 20, and the make-up water from the make-up water line 30 is added to the cooling water in the cooling tower 20.

[0021] The plant 100 shown in FIG. 1 further includes a chemical supply section 34 (a first chemical supply section 34A and a second chemical supply section 34B) for supplying a water quality improving agent to the cooling water in the cooling water circulation line 22 to improve the water quality of the cooling water.

[0022] Each of the chemical supply units 34 (34A, 34B) includes a chemical tank 35 (35A, 35B) for storing a water quality improvement agent, a chemical supply line 36 (36A, 36B) provided between the chemical tank 35 and the cooling water circulation line 22, and a chemical supply pump 38 (38A, 38B) provided in the chemical supply line 36. The water quality improvement agent stored in the chemical tank 35 is supplied to the cooling water flowing through the cooling water circulation line 22 via the chemical supply line 36 and the chemical supply pump 38. In the exemplary embodiment shown in FIG. 1, the chemical supply line 36 is connected to the cooling tower 20, and the water quality improvement agent from the chemical tank 35 is added to the cooling water in the cooling tower 20.

[0023] In some embodiments, the first chemical supply unit 34A is configured to supply a scale inhibitor as a water quality improving agent to the cooling water in the cooling water circulation line 22. Examples of the scale inhibitor include an acid (such as hydrochloric acid or nitric acid) or a chelating agent (such as ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid (NTA)).

[0024] In some embodiments, the second chemical supply unit 34B is configured to supply a corrosion inhibitor as a water quality improving agent to the cooling water in the cooling water circulation line 22. Examples of the corrosion inhibitor include polyphosphoric acid, phosphates, phosphonates, zinc salts, mercaptobenzothiazole, tolyltriazole, surfactants, amines, nitrites, molybdates, chromates, and the like.

[0025] When a part of the cooling water flowing through the cooling water circulation line 22 evaporates in the cooling tower 20, the concentration of solutes or ions that may cause scale or corrosion in the cooling water increases, and the risk of scale or corrosion occurring in the heat exchanger or piping increases. In this case, a part of the cooling water in the cooling water circulation line 22 can be discharged through the drainage line 26, and makeup water having a relatively low concentration of the solutes or ions can be replenished to the cooling water in the cooling water circulation line 22 through the makeup water line 30. Alternatively, in the above case, a water quality improving agent (such as a scale inhibitor or a corrosion inhibitor) from the chemical supply unit 34 can be supplied to the cooling water in the cooling water circulation line 22. In this way, the occurrence of scale or corrosion in the heat exchanger or piping can be suppressed.

[0026] (Configuration of water quality control device) Fig. 2 is a schematic configuration diagram of a water quality control device 50 according to one embodiment. As shown in Fig. 1 and Fig. 2, the water quality control device 50 includes a measurement unit 60 and a processing unit 70 for receiving and processing a signal from the measurement unit 60.

[0027] The measuring unit 60 is configured to measure a state quantity indicating a state of the cooling water of the plant 100. The state quantity includes at least one of the electrical conductivity of the cooling water, the temperature of the cooling water, and the pH of the cooling water. A signal indicating the measurement value in the measuring unit 60 is sent to the processing unit 70.

[0028] In the exemplary embodiment shown in Figures 1 and 2, the measurement unit 60 includes an electrical conductivity sensor 62 for measuring the electrical conductivity of the cooling water in the cooling water circulation line 22, a temperature sensor 64 for measuring the temperature of the above-mentioned cooling water, and a pH sensor 66 for measuring the pH of the above-mentioned cooling water.

[0029] As shown in FIG. 2, the processing unit 70 according to one embodiment includes a prediction equation acquisition unit 72, a concentration estimation unit 74, a determination unit 76, a water quality improvement unit 78, and a prediction equation correction unit 80.

[0030] The prediction formula acquisition unit 72 is configured to acquire a prediction formula expressing the relationship between the concentration of a solute or ion in the cooling water and the state quantity of the cooling water, for example, by reading it from the storage unit 82. Note that the storage unit 82 may include a storage device or auxiliary storage device of a computer constituting the processing unit 70, or may include a storage device or auxiliary storage device of a device other than the computer (such as a computer provided in a remote location).

[0031] The concentration estimation unit 74 is configured to estimate the solute or ion concentration in the cooling water using the prediction equation acquired by the prediction equation acquisition unit 72 based on the measured values ​​of the state quantities by the measurement unit 60.

[0032] The determination unit 76 is configured to determine whether or not improvement of the water quality of the cooling water is necessary, based on an index based on the concentration of the solute or ion estimated by the concentration estimation unit 74. This index is an index that indicates the water quality of the cooling water (for example, the risk of scale or corrosion due to the cooling water, etc.).

[0033] The water quality improvement unit 78 is configured to discharge the cooling water from the plant 100, add makeup water to the cooling water, or supply a water quality improvement agent to the cooling water when the judgment unit 76 judges that improvement of the water quality of the cooling water is necessary.

[0034] The prediction equation correction unit 80 is configured to correct the above-mentioned prediction equation based on the measured values ​​of the concentrations of solutes or ions in the cooling water or make-up water.

[0035] The processing unit 70 includes a computer equipped with a processor (such as a CPU), a storage device (memory device; such as a RAM), an auxiliary storage unit, an interface, and the like. The processing unit 70 receives signals from the measurement unit 60 described above via the interface. The processor is configured to process the signals thus received. The processor is also configured to process a program loaded into the storage device. This realizes the functions of each of the functional units described above (such as the concentration estimation unit 74).

[0036] The processing contents in the processing unit 70 are implemented as programs executed by the processor. The programs may be stored in an auxiliary storage unit. When the programs are executed, these programs are deployed in the storage device. The processor reads the programs from the storage device and executes the instructions contained in the programs.

[0037] (Water quality management flow) Below, a method for managing the water quality of the plant 100 according to some embodiments will be described. Below, a case where the water quality management of the plant 100 is performed using the above-mentioned water quality management device 50 will be described, but in some embodiments, the water quality management of the plant 100 may be performed using other devices. Also, some or all of the procedures described below may be performed manually.

[0038] Figures 3 to 6 are flowcharts of a water quality management method according to one embodiment. First, a common flow of each embodiment will be described with reference to Figure 3, and then each embodiment will be described in detail with reference to Figures 4 to 6.

[0039] As shown in FIG. 3, in some embodiments, first, the measurement unit 60 measures a state quantity indicating the state of the cooling water in the plant 100 (such as the electrical conductivity, temperature, or pH of the cooling water) (S2).

[0040] Next, the concentration estimation unit 74 estimates the solute or ion concentration in the cooling water using a prediction formula based on the measured values ​​of the state quantities in step S2 (S4). In step S4, the concentration of a solute or ion related to the water quality of the cooling water, for example, the concentration of a solute or ion related to the occurrence of scale or corrosion due to the cooling water, is calculated. An example of a solute or ion related to the occurrence of scale or corrosion due to the cooling water is calcium ion (Ca 2+ ), carbonate ion (CO 3 2- ), or water-soluble silica (SiO 2 ) are mentioned.

[0041] The prediction formula is based on the above solutes or ions (Ca 2+ , CO 3 2- or SiO 2 The prediction formula is a relational expression that expresses the relationship between the concentration of the component (e.g., component concentration, temperature, pH, etc.) and the state quantity of the cooling water (e.g., electrical conductivity, temperature, or pH of the cooling water). The prediction formula is obtained by analyzing the cooling water in advance before performing step S4.

[0042] For example, the concentration of calcium ions in cooling water [Ca 2+ The calcium ion concentration can be estimated by applying the measured electrical conductivity to a first prediction formula (the following formula (A)) that expresses the relationship between the calcium ion concentration and the electrical conductivity μ of the cooling water. 1 is a coefficient determined by analysis of the cooling water. [Ca 2+ ]=k 1 ×μ …(A) The electrical conductivity of the cooling water varies depending on the calcium ion concentration. In addition, when the ion ratio in the cooling water is almost constant, it is considered that the calcium ion concentration and the electrical conductivity are in a proportional relationship. For this reason, the above first prediction formula is valid.

[0043] Coefficient k in the first prediction formula 1 can be determined, for example, by regression analysis based on the results of actually measuring the calcium ion concentration and electrical conductivity of the cooling water.

[0044] For example, the concentration of carbonate ions in cooling water [CO 3 2- The carbonate ion concentration can be estimated by applying the measured temperature and pH to a second prediction formula (the following formula (B)) that expresses the relationship between the carbonate ion concentration and the temperature T (℃) and pH of the cooling water. 2 is the second dissociation constant of carbonic acid, m 1 ~m 3 is a coefficient determined by analysis of the cooling water. [CO 3 2- ]=K 2 ×(m 1 ×10 (pH-14) )-m 2 ×T+m 3 / 10 (-pH) …(B)

[0045] The second dissociation constant of carbonic acid, K 2 is the equilibrium constant of the ionization reaction represented by the following equation (C), and can be expressed by the following equation (D). HCO 3- ⇔H + +CO 3 2- …(C) K 2 =([H + ]×[CO 3 2- ]) / [HCO 3- ] …(D) Second dissociation constant K 2 is a constant that depends on temperature.

[0046] Coefficient m in the second prediction formula 1 ~m 3 can be determined, for example, by multiple regression analysis based on the results of actually measuring the carbonate ion concentration, temperature, and pH of the cooling water.

[0047] For example, the concentration of water-soluble silica in cooling water [SiO 2can be estimated by applying the measured electrical conductivity and temperature to a third prediction formula (the following formula (E)) which expresses the relationship between the water-soluble silica concentration and the electrical conductivity μ and temperature T (°C) of the cooling water. In the following formula (E), n 1 ~n 3 is a coefficient determined by analysis of the cooling water. [SiO 2 ]=n 1 ×μ+n 2 ×Tn 3 …(E)

[0048] Coefficient n in the third prediction formula 1 ~n 3 can be determined, for example, by multiple regression analysis based on the results of actually measuring the water-soluble silica concentration, electrical conductivity, and temperature of the cooling water.

[0049] Next, an index indicating the quality of the cooling water (e.g., the risk of scale or corrosion due to the cooling water, etc.) is obtained based on the concentration of the solute or ion estimated in step S4 (S6). This index may be a value calculated based on the concentration of the solute or ion estimated in step S4, or may be the concentration of the solute or ion estimated in step S4 itself.

[0050] Next, the determination unit 76 determines whether or not the quality of the cooling water needs to be improved based on the index acquired in step S6 (S8). In some embodiments, in step S8, the determination may be made based on a comparison between the index and a threshold value.

[0051] In some embodiments, in step S8, it may be determined based on the above-mentioned index whether or not there is an increased risk of scale formation in the plant 100 (whether or not scale has formed or is likely to form). Alternatively, in some embodiments, it may be determined based on the above-mentioned index whether or not there is an increased risk of corrosion formation in the plant 100 (whether or not corrosion has formed or is likely to form).

[0052] Next, if it is determined in step S8 that the quality of the cooling water needs to be improved (Yes in step S8), one or both of steps S10 and S12 described below are performed.

[0053] In step S10, the water quality improvement unit 78 discharges (blows) the cooling water from the plant 100 and adds make-up water to the cooling water (S10). The water quality improvement unit 78 is configured to adjust the opening of the drain valve 28 so as to discharge an appropriate amount of cooling water. The water quality improvement unit 78 is also configured to adjust the discharge amount of the make-up water pump 32 so as to add an appropriate amount of make-up water. The above-mentioned amount of cooling water discharged or the make-up amount of make-up water may be determined based on the index obtained in step S6.

[0054] In step S12, the water quality improvement unit 78 supplies a water quality improvement agent (such as a scale inhibitor or a corrosion inhibitor) to the cooling water (S12). The water quality improvement unit 78 is configured to adjust the discharge rate of the chemical supply pump 38 (38A or 38B) so as to supply an appropriate amount of the water quality improvement agent. The supply amount of the water quality improvement agent may be determined based on the index obtained in step S6.

[0055] If it is determined in step S8 that improvement of the quality of the cooling water is not required (No in step S8), this flow ends.

[0056] According to the above-described embodiment, in step S4, the concentration of solutes or ions that may cause scale or corrosion can be estimated based on the measured state quantities and the prediction formula. Therefore, based on the estimated solute or ion concentrations, water quality can be quickly evaluated (evaluation of the risk of scale or corrosion occurrence, etc.). For example, the above-described water quality evaluation can be performed in real time by measuring the state quantities and estimating the solute or ion concentrations at short specified intervals. This enables detailed water quality management, and effectively suppresses the occurrence of scale and corrosion in the plant 100. For example, excessive replacement of cooling water (blowdown and replenishment of makeup water) and excessive addition of water quality improvers can be suppressed.

[0057] In the above embodiment, an index indicating the quality of the cooling water, which can be obtained based on the estimated concentration of solutes or ions, is obtained (step S6), and in step S8, it is possible to appropriately determine whether or not the quality of the cooling water needs to be improved based on this index. Therefore, based on the result of this determination, the quality of the cooling water can be appropriately improved in steps S10 to S12.

[0058] In the above embodiment, when it is determined that the quality of the cooling water needs to be improved (Yes in step S8), the cooling water is discharged from the plant, makeup water is added to the cooling water, or a water quality improver is supplied to the cooling water in steps S10 to S12. This appropriately improves the quality of the cooling water, and effectively suppresses the occurrence of scale and corrosion in the plant 100.

[0059] Furthermore, in the above-described embodiment, when it is determined that the quality of the cooling water needs to be improved (Yes in step S8), the amount of cooling water discharged from plant 100, the amount of makeup water replenished to the cooling water, or the amount of water quality improver supplied to the cooling water can be determined based on the above-described index. By adding makeup water to the cooling water or supplying a water quality improver to the cooling water according to the thus determined discharge, replenishment, or supply amount, the quality of the cooling water can be appropriately improved and the occurrence of scale and corrosion in plant 100 can be effectively suppressed.

[0060] Next, an embodiment according to the flowchart of FIG. 4 will be described.

[0061] In the embodiment shown in FIG. 4, in step S2, the measuring unit 60 measures the electrical conductivity, temperature, and pH of the cooling water as state quantities indicating the state of the cooling water of the plant 100.

[0062] Next, in step S4, the calcium ion concentration [Ca 2+] is estimated, and the carbonate ion concentration in the cooling water [CO 3 2- ] is estimated.

[0063] Next, in step S6, the calcium ion concentration [Ca 2+ ] and carbonate ion concentration [CO 3 2- ] and the product ([Ca 2+ ]×[CO 3 2- This product is calculated using the formula: 3 ) is an index showing the risk of scale formation.

[0064] In step S8, the index obtained in step S6 (the above product ([Ca 2+ ]×[CO 3 2- ])) and the solubility product K of calcium carbonate sp The solubility product of calcium carbonate, K sp The solubility product K, which is compared with the index in step S8, changes with temperature. sp may be the solubility product at the temperature measured in step S2.

[0065] In step S8, the above-mentioned product is converted into the above-mentioned solubility product K sp If it is greater than or equal to (i.e., ([Ca 2+ ]×[CO 3 2- ]≧K sp If the relationship is satisfied (Yes in S8), it is determined that the risk of scale generation is high and that improvement of the water quality is necessary. In this case, the water quality of the cooling water is improved by the procedure of step S10 and / or step S12 described above. In step S12, the water quality improvement unit 78 supplies the scale inhibitor stored in the chemical tank 35A of the first chemical supply unit 34A to the cooling water.

[0066] If it is determined in step S8 that improvement of the quality of the cooling water is not required (No in step S8), this flow ends.

[0067] In the above-described embodiment, the first prediction formula is used to estimate the calcium ion concentration in the cooling water based on the measured value of electrical conductivity, so that the risk of occurrence of scale whose main component is calcium carbonate can be appropriately evaluated based on the estimated calcium ion concentration.

[0068] In addition, in the above-described embodiment, the second prediction formula is used to estimate the carbonate ion concentration in the cooling water based on the measured values ​​of temperature and pH, so that the risk of occurrence of scale whose main component is calcium carbonate can be appropriately evaluated based on the estimated carbonate ion concentration.

[0069] In the above embodiment, the product of the calcium ion concentration estimated using the first prediction formula and the carbonate ion concentration estimated using the second prediction formula and the solubility product K sp Based on the comparison, it is possible to appropriately determine whether or not improvement of the quality of the cooling water is required. Therefore, it is possible to effectively suppress the generation of scale in the plant 100.

[0070] Next, an embodiment according to the flowchart of FIG. 5 will be described.

[0071] In the embodiment shown in FIG. 5, in step S2, the measuring unit 60 measures the electrical conductivity and the temperature of the cooling water as state quantities indicating the state of the cooling water of the plant 100.

[0072] Next, in step S4, the concentration of water-soluble silica in the cooling water is estimated using the third prediction equation (the above equation (E)) based on the measured values ​​of the state quantities in step S2.

[0073] Next, in step S6, the water-soluble silica concentration [SiO 2The water-soluble silica concentration is an index showing the risk of the formation of scale, the main component of which is silica.

[0074] In step S8, the indicator obtained in step S6 (the water-soluble silica concentration [SiO 2 ]) is compared with the saturation solubility of water-soluble silica. The saturation solubility of water-soluble silica varies depending on temperature. The saturation solubility compared with the indicator in step S8 may be the saturation solubility at the temperature measured in step S2.

[0075] In step S8, if the index (estimated water-soluble silica concentration) is equal to or greater than the saturation solubility (Yes in S8), it is determined that the risk of scale generation is high and that water quality needs to be improved. In this case, the water quality of the cooling water is improved by the procedure of step S10 and / or step S12. In step S12, the water quality improvement unit 78 supplies the scale inhibitor stored in the chemical tank 35A of the first chemical supply unit 34A to the cooling water.

[0076] If it is determined in step S8 that improvement of the quality of the cooling water is not required (No in step S8), this flow ends.

[0077] In the above-described embodiment, the third prediction formula is used to estimate the water-soluble silica concentration in the cooling water based on the measured values ​​of electrical conductivity and temperature, so that the risk of occurrence of scale containing silica as its main component can be appropriately evaluated based on the estimated water-soluble silica concentration.

[0078] In addition, in the above embodiment, the necessity of improving the water quality of the cooling water can be appropriately determined based on a comparison between the water-soluble silica concentration estimated using the third prediction formula and the saturation solubility of water-soluble silica, and therefore, the generation of scale in the plant 100 can be effectively suppressed.

[0079] Next, an embodiment according to the flowchart of FIG. 6 will be described.

[0080] In the embodiment shown in FIG. 6, in step S2, the measuring unit 60 measures the electrical conductivity, temperature, and pH of the cooling water as state quantities indicating the state of the cooling water of the plant 100.

[0081] Next, in step S4, the carbonate ion concentration [CO 3 2- ] is estimated.

[0082] Next, in step S6, the Langelier Saturation Index (LSI) is calculated as an index showing the water quality of the cooling water. The Langelier Saturation Index is calculated by using the electrical conductivity μ, temperature T (°C), and pH of the cooling water obtained in step S2, and the calcium ion concentration [Ca 2+ More specifically, the Langelier index LSI is calculated using the M alkalinity [Alk] calculated by the following formula (F) based on the temperature T and pH obtained in step S2, and the electrical conductivity μ obtained in step S2, the temperature T, and the calcium ion concentration [Ca 2+ ] is used to calculate according to the following formula (G).

[0083] [Alk]=p 1 ×[OH - ]-p 2 ×T+p 3 …(F)

number

[0084] In the above formula, [OH - ] (hydroxide ion concentration in the cooling water) is calculated based on the pH measured in step S2 according to the following formula (H). [OH - ]=10 (-pOH) =10 (pH-14) …(H) The coefficient p in the above formula (F) 1 ~p 3can be determined, for example, by regression analysis based on the results of actual measurements of the M alkalinity, pH, and temperature of the cooling water. In the above formula (G), pH s represents the pH at equilibrium. The Langelier index calculated in this way is the ratio of calcium carbonate (CaCO 3 ) is an index showing the risk of scale formation and / or corrosion.

[0085] In this embodiment, step S8 includes one or both of the following steps S8a or S8b.

[0086] In step S8a, the Langelier index obtained in step S6 is compared with a threshold A1, which may be 0.1, 0.3, or 1.

[0087] In step S8a, if the Langelier index LSI is equal to or greater than the threshold value A1 (i.e., if the relationship LSI≧A1 is satisfied; Yes in S8a), it is determined that the risk of scale formation is increased and that improvement of the water quality is necessary. In this case, the quality of the cooling water is improved by the procedure of steps S10a and / or S12a corresponding to the above-mentioned step S10 and / or step S12. In step S12a, the water quality improvement unit 78 supplies the scale inhibitor stored in the chemical tank 35A of the first chemical supply unit 34A to the cooling water.

[0088] In step S8b, the Langelier index obtained in step S6 is compared with a threshold A2, which may be −0.1, −0.3, or −1.

[0089] In step S8b, if the Langelier index LSI is equal to or less than the threshold value A2 (i.e., if the relationship LSI≦A2 is satisfied; Yes in S8b), it is determined that the risk of corrosion occurrence is high and improvement of the water quality is necessary. In this case, the quality of the cooling water is improved by the procedure of steps S10b and / or S12b corresponding to the above-mentioned step S10 and / or step S12. In step S12b, the corrosion inhibitor stored in the chemical tank 35B of the second chemical supply unit 34B is supplied to the cooling water by the water quality improvement unit 78.

[0090] If it is determined in both steps S8a and S8b that improvement of the quality of the cooling water is not required (No in steps S8a and S8b), this flow ends.

[0091] In the above embodiment, the Langelier index is calculated based on the measured electrical conductivity, temperature, and pH, and the carbonate ion concentration estimated using the second prediction formula, so that the necessity of improving the water quality of the cooling water can be appropriately determined based on a comparison between the Langelier index and a threshold value. Therefore, the generation of scale and / or corrosion in the plant 100 can be effectively suppressed.

[0092] In some embodiments, the embodiments shown in the above-mentioned Figs. 4 to 6 may be combined. That is, in step S8, the calcium ion concentration [Ca 2+ ] and carbonate ion concentration [CO 3 2- ] and the product ([Ca 2+ ]×[CO 3 2- ]), silica concentration [SiO 2 Whether or not the quality of the cooling water needs to be improved may be determined based on two or more of the following: the temperature difference (Tc) of the cooling water and the Langelier index (LSI). In this way, by using a plurality of criteria, it may be possible to more appropriately determine whether or not the quality of the cooling water needs to be improved. Therefore, it is possible to effectively suppress the generation of scale and / or corrosion in the plant 100.

[0093] In some embodiments, the prediction equations (for example, the above-mentioned first to third prediction equations) may be corrected based on the measured values ​​of the concentrations of solutes or ions in the cooling water or make-up water by the prediction equation correction unit 80. Note that the prediction equation correction unit 80 may be configured to obtain the prediction equation before correction from the storage unit 82 (see FIG. 2), correct it, and store the corrected prediction equation in the storage unit 82.

[0094] The prediction equation correction unit 80 may correct the prediction equation, for example, by multiple regression analysis, based on the measured values ​​of the concentration of solutes or ions in the cooling water or make-up water, and the measured values ​​of state quantities (electrical conductivity, temperature, pH, etc.) that indicate the state of the cooling water or make-up water.

[0095] In some embodiments, the prediction equation correction unit 80 is configured to correct the prediction equation based on a measured value of the concentration of a solute or ion in the cooling water. The measured value may be obtained by measuring the concentration of a solute or ion in the cooling water collected from the plant 100.

[0096] 7 is a diagram for explaining the correction of the prediction formula according to one embodiment. The quality of the cooling water of the plant 100 may vary depending on the operating conditions of the plant 100. For this reason, a deviation may occur over time between the predicted value based on the prediction formula and the actual value measured by an operator's manual analysis regarding the concentration of solutes or ions in the cooling water.

[0097] 7, plot 201a shows the relationship between the predicted value and the actual measurement value at a certain time point in month N, and plot 202b shows the relationship between the predicted value and the actual measurement value at a certain time point in (N+1). Also, line 101 (dashed line) is a line that shows the relationship between the predicted value based on the prediction formula and the actual measurement value at the time point in month N.

[0098] 7, the predicted value in month N shown by plot 201a is located near line 101 which shows the relationship between the prediction formula and the actual measured value. Therefore, the concentration of the solute or ion in the cooling water can be appropriately estimated based on the prediction formula.

[0099] 7, the predicted value in month (N+1) shown by plot 202a is far from line 101, which indicates the relationship between the prediction formula and the actual measured value. For this reason, if the prediction formula used in month N is used, the solute or ion concentration of the cooling water in month (N+1) cannot be appropriately estimated (see line 101).

[0100] Therefore, the prediction formula is corrected based on the measured values ​​of the concentration of solutes or ions in the cooling water in month (N+1). Line 102 (solid line) in FIG. 7 is a line showing the relationship between the predicted values ​​based on the prediction formula corrected using the measurement data in month (N+1) and the actual measured values. The predicted values ​​in month (N+1) shown in plot 202a are located near line 102 showing the relationship between the corrected prediction formula and the actual measured values. In this way, by using the prediction formula corrected based on the measured values ​​of the concentration of solutes or ions in the cooling water, the concentration of solutes or ions in the cooling water can be appropriately estimated taking into account the fluctuation in the water quality of the cooling water over time.

[0101] That is, in the above-described embodiment, the above-described prediction formulas (for example, the above-described first to third prediction formulas) are modified based on the measured values ​​of the concentration of solutes or ions in the cooling water, and by using the modified prediction formulas, the concentration of solutes or ions in the cooling water can be more accurately estimated.

[0102] In one embodiment, the cooling water of the plant 100 may be sampled periodically (for example, monthly) to measure the concentration of the solute or ion, and the prediction equation may be modified based on the measurement results.

[0103] In some embodiments, the prediction equation correction unit 80 is configured to correct the prediction equation based on a measured value of the concentration of a solute or ion in the make-up water. The measured value may be obtained by measuring the concentration of a solute or ion in the make-up water collected from a make-up water source or the like.

[0104] 8 is a diagram for explaining the correction of the prediction formula according to one embodiment. The quality of makeup water supplied to the cooling water of the plant 100 may vary depending on the properties of the makeup water source. For example, when river water is used as makeup water, the quality of the makeup water may vary depending on the season. For this reason, a deviation may occur over time between the predicted value based on the prediction formula and the actual measured value for the concentration of solutes or ions in the cooling water.

[0105] 8, for example, plot 201a shows the relationship between the predicted value and the actual measurement value at a certain time in month N, and plot 202a shows the relationship between the predicted value and the actual measurement value at a certain time in (N+1). Plot 201b shows the relationship between the predicted value and the actual measurement value (make-up water) at a certain time in month N, and plot 202b shows the relationship between the predicted value and the actual measurement value (make-up water) at a certain time in (N+1). Line 101 (dashed line) is a line that shows the relationship between the predicted value based on the prediction formula and the actual measurement value at month N.

[0106] 8, the predicted value in month N shown by plot 201a is located near line 101 which shows the relationship between the prediction formula and the actual measured value. Therefore, the concentration of the solute or ion in the cooling water can be appropriately estimated based on the prediction formula.

[0107] 8, the predicted value in month (N+1) shown by plot 202a is far from line 101, which indicates the relationship between the prediction formula and the actual measured value. For this reason, if the prediction formula used in month N is used, the solute or ion concentration of the cooling water in month (N+1) cannot be appropriately estimated (see line 101).

[0108] Therefore, the prediction formula is corrected based on the measured values ​​of the concentration of the solute or ion in the cooling water in month (N+1) and the measured values ​​of the solute or ion in the make-up water. A straight line 102 (solid line) in FIG. 8 is a straight line showing the relationship between the predicted value based on the prediction formula corrected using the measurement data (cooling water and make-up water) in month (N+1) and the actual measurement value. The predicted value in month (N+1) shown in plot 202a is located near the straight line 102 showing the relationship between the corrected prediction formula and the actual measurement value. In this way, by using the prediction formula corrected based on the measured values ​​of the relatively high concentration region of the solute or ion in the cooling water and the measured values ​​of the relatively low concentration region of the solute or ion in the make-up water, the concentration of the solute or ion in the cooling water can be appropriately estimated in consideration of the change in the water quality of the cooling water and the make-up water over time.

[0109] That is, in the above-described embodiment, the above-described prediction formulas (e.g., the first to third prediction formulas) are modified based on the measured values ​​of the concentration of the solute or ion in the make-up water, so that the concentration of the solute or ion in the cooling water can be more accurately estimated by using the modified prediction formulas.

[0110] In one embodiment, a prediction formula to be used at the present time may be created by weighting a prediction formula based on actual measurement data (solute or ion concentration, and state quantity) of the cooling water at a first time point in the past with a prediction formula based on actual measurement data (solute or ion concentration, and state quantity) of the make-up water at a second time point in the past. The above-mentioned first time point and second time point may be the same time point.

[0111] 9 is a diagram for explaining the correction of the prediction formula according to one embodiment. Here, as an example, it is assumed that the current date is July 17th and the past dates (first and second past time points) are July 1st. In FIG. 9, a line 103 (solid line) is a line showing the relationship between the predicted value based on the prediction formula based on the actual measurement data (indicated by P1) of the cooling water as of July 1st (past) and the actual measurement value, and a line 104 (dashed line) is a line showing the relationship between the predicted value based on the prediction formula based on the actual measurement data (indicated by P2) of the make-up water as of July 1st (past) and the actual measurement value.

[0112] Between July 1st and July 17th, the quality of the plant cooling water changes due to evaporation of cooling water from the plant 100, discharge of cooling water from the plant 100, and replenishment of makeup water. Therefore, for example, based on the amount of evaporation of cooling water from the plant 100, the amount of discharge of cooling water from the plant 100, and / or the amount of makeup water replenishment, a prediction formula (see line 103) based on the actual measurement data of cooling water as of July 1st (past) and a prediction formula (see line 104) based on the actual measurement data of makeup water as of July 1st (past) are weighted to create a prediction formula (line 105; shown by a dashed line) to be used as of July 17th (present) (i.e., the prediction formula is modified). Using the prediction formula created in this way, a predicted value as of July 17th (present) can be more appropriately obtained. For example, a predicted value E1 of the solute or ion concentration of the cooling water as of July 17th is close to an actual value B1 of the solute or ion concentration of the cooling water.

[0113] That is, in the above-described embodiment, the above-described prediction formulas (e.g., the first to third prediction formulas) are modified based on the measured values ​​of the concentration of the solute or ion in the make-up water, so that the concentration of the solute or ion in the cooling water can be more accurately estimated by using the modified prediction formulas.

[0114] The contents described in each of the above embodiments can be understood, for example, as follows.

[0115] (1) A water quality control device (50) of a plant (100) according to at least one embodiment of the present invention comprises: a measuring unit (60) for measuring a state quantity indicating a state of cooling water of the plant; a concentration estimation unit (74) configured to estimate a concentration of the solute or the ion in the cooling water based on the measured state quantity by using a prediction equation expressing a relationship between the concentration of the solute or the ion in the cooling water and the state quantity; Equipped with.

[0116] According to the above configuration (1), the concentration of solutes or ions that may be a cause of scale or corrosion can be estimated based on the measured state quantities and the prediction equation. Therefore, the water quality can be quickly evaluated (evaluated for the risk of scale or corrosion occurrence, etc.) based on the estimated solute or ion concentration. For example, the above-mentioned water quality evaluation can be performed in real time by measuring the state quantities and estimating the solute or ion concentration at short specified intervals. This makes it possible to effectively suppress the occurrence of scale and corrosion in the plant.

[0117] (2) In some embodiments, in the configuration of (1) above, The water quality control device includes: The apparatus further includes a determination unit (76) configured to determine whether or not improvement of the quality of the cooling water is required, based on an index indicating the quality of the cooling water, which is based on the estimated concentration.

[0118] According to the above configuration (2), it is possible to appropriately determine whether or not the quality of the cooling water needs to be improved based on an index indicating the quality of the cooling water that can be obtained based on the estimated concentration of solutes or ions. Therefore, the quality of the cooling water can be appropriately improved based on the result of this determination. This makes it possible to effectively suppress the occurrence of scale and corrosion in the plant.

[0119] In this specification, improving the quality of cooling water means bringing the cooling water into a state in which the risk of the occurrence of scale, corrosion, etc. in the cooling water is reduced.

[0120] (3) In some embodiments, in the configuration of (2) above, The water quality control device includes: The plant is provided with a water quality improvement unit (78) for discharging the cooling water from the plant, adding makeup water to the cooling water, or supplying a water quality improver to the cooling water when the determination unit determines that improvement of the water quality of the cooling water is necessary.

[0121] According to the above configuration (3), when it is determined that the quality of the cooling water needs to be improved, the cooling water can be discharged from the plant, makeup water can be added to the cooling water, or a water quality improver can be supplied to the cooling water. This makes it possible to appropriately improve the quality of the cooling water and effectively suppress the occurrence of scale and corrosion in the plant.

[0122] (4) In some embodiments, in the configuration of (3) above, The water quality improvement unit is configured to determine, when the judgment unit judges that improvement of the water quality of the cooling water is necessary, based on the index, the amount of the cooling water to be discharged from the plant, the amount of make-up water to be replenished to the cooling water, or the amount of water quality improvement agent to be supplied to the cooling water.

[0123] According to the above configuration (4), when it is determined that the quality of the cooling water needs to be improved, the amount of cooling water discharged from the plant, the amount of make-up water replenished to the cooling water, or the amount of water quality improver supplied to the cooling water can be determined based on the above-mentioned index. By adding make-up water to the cooling water or supplying the water quality improver to the cooling water according to the discharge amount, make-up amount, or supply amount determined in this manner, the quality of the cooling water can be appropriately improved and the occurrence of scale and corrosion in the plant can be effectively suppressed.

[0124] (5) In some embodiments, in any one of the configurations (1) to (4) above, The state quantity includes the electrical conductivity of the cooling water.

[0125] According to the above configuration (5), the electrical conductivity is measured as a state quantity of the cooling water, so that the concentration of solutes or ions correlated with the electrical conductivity can be appropriately estimated based on the measured value of the electrical conductivity.

[0126] (6) In some embodiments, in the configuration of (5) above, The concentration estimation unit is configured to estimate the calcium ion concentration in the cooling water based on the measured electrical conductivity using a first prediction equation that expresses at least the relationship between the calcium ion concentration in the cooling water and the electrical conductivity.

[0127] According to the above configuration (6), the calcium ion concentration in the cooling water is estimated based on the measured value of the electrical conductivity using the first prediction formula, so that the risk of occurrence of scale containing calcium carbonate as a main component can be appropriately evaluated based on the estimated calcium ion concentration, and thus occurrence of scale in the plant can be effectively suppressed.

[0128] (7) In some embodiments, in any one of the configurations (1) to (6) above, The state quantities include a temperature and a pH of the cooling water, The concentration estimation unit is configured to estimate the carbonate ion concentration in the cooling water based on the measured temperature and the measured pH using a second prediction equation that expresses at least the relationship between the carbonate ion concentration in the cooling water and the temperature and the pH.

[0129] According to the above configuration (7), the carbonate ion concentration in the cooling water is estimated based on the measured values ​​of temperature and pH using the second prediction formula, so that the risk of occurrence of scale containing calcium carbonate as a main component can be appropriately evaluated based on the estimated carbonate ion concentration. Therefore, occurrence of scale in the plant can be effectively suppressed.

[0130] (8) In some embodiments, in the configuration of (6) above, The state quantities include a temperature and a pH of the cooling water, the concentration estimation unit is configured to estimate the carbonate ion concentration in the cooling water based on the measured temperature and the measured pH by using a second prediction equation that expresses at least a relationship between the carbonate ion concentration in the cooling water and the temperature and the pH, The water quality control device includes: The method further includes a determination unit (78) configured to determine whether or not improvement of the quality of the cooling water is required based on a comparison of the product of the estimated calcium ion concentration and the estimated carbonate ion concentration with the solubility product of calcium carbonate.

[0131] The product of the calcium ion concentration and the carbonate ion concentration in the cooling water is an index showing the risk of occurrence of scale whose main component is calcium carbonate. In this regard, according to the configuration of (8) above, it is possible to appropriately determine whether or not the water quality of the cooling water needs to be improved based on a comparison between the product of the calcium ion concentration estimated using the first prediction formula and the carbonate ion concentration estimated using the second prediction formula, and the solubility product of calcium carbonate. Therefore, it is possible to effectively suppress occurrence of scale in the plant.

[0132] (9) In some embodiments, in any of the configurations (1) to (8) above, the state quantity includes an electrical conductivity and a temperature of the cooling water, The concentration estimation unit is configured to estimate the concentration of water-soluble silica in the cooling water based on the measured electrical conductivity and temperature using a third prediction equation that expresses at least the relationship between the water-soluble silica concentration in the cooling water and the electrical conductivity and the temperature.

[0133] According to the above configuration (9), the water-soluble silica concentration in the cooling water is estimated based on the measured values ​​of the electrical conductivity and temperature using the third prediction formula, so that the risk of generation of scale containing silica as a main component can be appropriately evaluated based on the estimated water-soluble silica concentration. Therefore, the generation of scale in the plant can be effectively suppressed.

[0134] (10) In some embodiments, in the configuration of (9), The water quality control device includes: The system further includes a determination unit (78) configured to determine whether or not improvement of the quality of the cooling water is required based on a comparison between the estimated water-soluble silica concentration and the saturation solubility of water-soluble silica.

[0135] The concentration of water-soluble silica in cooling water is an index showing the risk of occurrence of scale whose main component is silica. In this regard, according to the configuration of (10) above, it is possible to appropriately determine whether or not the water quality of the cooling water needs to be improved based on a comparison between the water-soluble silica concentration estimated using the third prediction formula and the saturation solubility of water-soluble silica. Therefore, it is possible to effectively suppress the occurrence of scale in the plant.

[0136] (11) In some embodiments, in any one of the configurations (1) to (10) above, The state quantities include the electrical conductivity, temperature, and pH of the cooling water, the concentration estimation unit is configured to estimate the carbonate ion concentration in the cooling water based on the measured temperature and pH by using a second prediction equation expressing a relationship between the carbonate ion concentration in the cooling water and the temperature and the pH; The water quality control device includes: The method further includes a determination unit (78) configured to determine whether or not improvement of the water quality of the cooling water is required based on a comparison between the Langelier index as the index calculated based on the measured electrical conductivity, the measured temperature, the measured pH, and the estimated carbonate ion concentration and a threshold value.

[0137] The Langelier index is an index that indicates the risk of occurrence of scale and / or corrosion whose main component is calcium carbonate. In this regard, according to the configuration of (11) above, the Langelier index is calculated based on the measured electrical conductivity, temperature, and pH, and the carbonate ion concentration estimated using the second prediction formula, so that it is possible to appropriately determine whether or not improvement of the water quality of the cooling water is necessary based on a comparison between the Langelier index and a threshold value. Therefore, it is possible to effectively suppress occurrence of scale and / or corrosion in the plant.

[0138] (12) In some embodiments, in any one of the configurations (1) to (11) above, The water quality control device includes: The cooling water further includes a prediction equation correcting unit (80) configured to correct the prediction equation based on a measured value of the concentration of the solute or the ion in the cooling water.

[0139] The quality of the cooling water in a plant may vary depending on the operating conditions of the plant, etc. In this regard, according to the configuration of (12) above, the prediction formula (for example, any of the first to third prediction formulas) is corrected based on the measured value of the concentration of the solute or ion in the cooling water, so that the concentration of the solute or ion in the cooling water can be more accurately estimated by using the corrected prediction formula.

[0140] (13) In some embodiments, in any one of the configurations (1) to (12) above, The water quality control device includes: The system further includes a prediction equation correcting unit (80) configured to correct the prediction equation based on a measured value of the concentration of the solute or the ion in make-up water that is made to replenish the cooling water.

[0141] The quality of makeup water supplied to the cooling water of a plant may vary depending on the properties of the makeup water source. For example, when river water is used as makeup water, the quality of the makeup water may vary depending on the season. In this regard, according to the configuration of (13), the prediction formula (e.g., any one of the first to third prediction formulas) is corrected based on the measured value of the concentration of the solute or ion in the makeup water, so that the concentration of the solute or ion in the cooling water can be more accurately estimated by using the corrected prediction formula.

[0142] (14) At least one embodiment of the plant (100) of the present invention comprises: a heat exchanger (e.g., the condenser 18 described above); a cooling water circulation line (22) configured to circulate the cooling water supplied to the heat exchanger; A water quality control device (50) according to any one of (1) to (13) above configured to control the quality of the cooling water; Equipped with.

[0143] According to the above configuration (14), the concentration of solutes or ions that may be a cause of scale or corrosion can be estimated based on the measured state quantities and the prediction equation. Therefore, based on the estimated solute or ion concentrations, water quality can be quickly evaluated (evaluated for the risk of scale or corrosion occurrence, etc.). For example, by measuring the state quantities and estimating the solute or ion concentrations at short specified intervals, the above-mentioned water quality evaluation can be performed in real time. This makes it possible to effectively suppress the occurrence of scale or corrosion in the plant.

[0144] (15) At least one embodiment of the water quality control method for a plant according to the present invention comprises the steps of: A step (S2) of measuring a state quantity indicating a state of cooling water of the plant; A step (S4) of estimating the concentration of the solute or the ion in the cooling water based on the measured state quantity using a prediction equation expressing a relationship between the concentration of the solute or the ion in the cooling water and the state quantity; Equipped with.

[0145] According to the method of (15) above, the concentration of solutes or ions that may be a cause of scale or corrosion can be estimated based on the measured state quantities and the prediction equation. Therefore, based on the estimated solute or ion concentrations, water quality can be quickly evaluated (evaluated for the risk of scale or corrosion occurrence, etc.). For example, by measuring the state quantities and estimating the solute or ion concentrations at short specified intervals, the above-mentioned water quality evaluation can be performed in real time. This makes it possible to effectively suppress the occurrence of scale or corrosion in the plant.

[0146] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0147] In this specification, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," do not only strictly represent such a configuration, but also represent a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained. In addition, in this specification, the expressions "comprise," "include," or "have" a certain element are not exclusive expressions that exclude the presence of other elements. [Explanation of symbols]

[0148] 12 Water supply line 13 Water Pump 14 Boiler 16 Turbine 17. Generator 18 Condenser 20 Cooling Tower 22 Cooling water circulation line 24 Cooling water pump 26 Drain line 28 Drain valve 30 Make-up water line 32 Make-up water pump 34 Drug Supply Department 34A 1st Drug Supply Department 34B 2nd Drug Supply Department 35, 35A, 35B Chemical tank 36, 36A, 36B Drug supply line 38, 38A, 38B Drug supply pump 50 Water quality control equipment 60 Measurement section 62 Electrical conductivity sensor 64 Temperature Sensor 66 pH Sensor 70 Processing section 72 Prediction formula acquisition section 74 Concentration estimation section 76 Judgment section 78 Water Quality Improvement Department 80 Prediction formula correction section 82 Memory section 100 Plants

Claims

1. A measuring unit for measuring a state quantity indicating a state of the cooling water of the plant; a concentration estimation unit configured to estimate a concentration of the solute or the ion in the cooling water based on the measured state quantity by using a prediction equation expressing a relationship between the concentration of the solute or the ion in the cooling water and the state quantity; a prediction equation correction unit configured to correct the prediction equation used for estimating the concentration of the solute or the ion in the cooling water at a past time based on an actual measurement value of the concentration of the solute or the ion in the cooling water at a current time, and obtain the prediction equation for estimating the concentration of the solute or the ion in the cooling water at a current time; Equipped with The state quantity includes at least one of the electrical conductivity of the cooling water, the temperature of the cooling water, or the pH of the cooling water. Plant water quality control equipment.

2. A measuring unit for measuring a state quantity indicating a state of the cooling water of the plant; a concentration estimation unit configured to estimate a concentration of the solute or the ion in the cooling water based on the measured state quantity by using a prediction equation expressing a relationship between the concentration of the solute or the ion in the cooling water and the state quantity; a prediction equation correcting unit configured to correct the prediction equation based on an actual measurement value of a concentration of the solute or the ion in make-up water that is made to be supplied to the cooling water; Equipped with The state quantity includes at least one of the electrical conductivity of the cooling water, the temperature of the cooling water, or the pH of the cooling water. Plant water quality control equipment.

3. and a determination unit configured to determine whether or not the quality of the cooling water needs to be improved based on an index indicating the quality of the cooling water based on the estimated concentration. The water quality control device for a plant according to claim 1 or 2.

4. and a water quality improvement unit for discharging the cooling water from the plant, adding makeup water to the cooling water, or supplying a water quality improver to the cooling water when the determination unit determines that improvement of the water quality of the cooling water is necessary. The water quality control device for a plant according to claim 3.

5. The water quality improvement unit is configured to determine, when the determination unit determines that improvement of the quality of the cooling water is necessary, an amount of the cooling water to be discharged from the plant, an amount of makeup water to be replenished to the cooling water, or an amount of a water quality improvement agent to be supplied to the cooling water, based on the index. The water quality control device for a plant according to claim 4.

6. The state quantity includes the electrical conductivity of the cooling water. The water quality control device for a plant according to any one of claims 1 to 5.

7. The concentration estimation unit is configured to estimate the calcium ion concentration in the cooling water based on the measured electrical conductivity by using a first prediction equation that expresses at least a relationship between the calcium ion concentration in the cooling water and the electrical conductivity. The water quality control device for a plant according to claim 6.

8. The state quantity includes a temperature and a pH of the cooling water, The concentration estimation unit is configured to estimate the carbonate ion concentration in the cooling water based on the measured temperature and the measured pH by using a second prediction equation that expresses at least a relationship between the carbonate ion concentration in the cooling water and the temperature and the pH. The water quality control device for a plant according to any one of claims 1 to 7.

9. The state quantity includes a temperature and a pH of the cooling water, the concentration estimation unit is configured to estimate the carbonate ion concentration in the cooling water based on the measured temperature and the measured pH by using a second prediction equation that expresses at least a relationship between the carbonate ion concentration in the cooling water and the temperature and the pH, and a determination unit configured to determine whether or not improvement of the quality of the cooling water is required based on a comparison between the product of the estimated calcium ion concentration and the estimated carbonate ion concentration and the solubility product of calcium carbonate. The water quality control device for a plant according to claim 7.

10. the state quantity includes an electrical conductivity and a temperature of the cooling water, The concentration estimation unit is configured to estimate the concentration of water-soluble silica in the cooling water based on the measured electrical conductivity and temperature by using a third prediction formula that expresses at least a relationship between the water-soluble silica concentration in the cooling water and the electrical conductivity and the temperature. The water quality control device for a plant according to any one of claims 1 to 9.

11. A determination unit is provided that is configured to determine whether or not the quality of the cooling water needs to be improved based on a comparison between the estimated water-soluble silica concentration and the saturated solubility of water-soluble silica. The water quality control device for a plant according to claim 10.

12. The state quantities include an electrical conductivity, a temperature, and a pH of the cooling water, the concentration estimation unit is configured to estimate the carbonate ion concentration in the cooling water based on the measured temperature and pH by using a second prediction equation expressing a relationship between the carbonate ion concentration in the cooling water and the temperature and the pH, The determination unit is configured to determine whether or not improvement of the water quality of the cooling water is necessary based on a comparison between a Langelier index as the index calculated based on the measured electrical conductivity, the measured temperature, the measured pH, and the estimated carbonate ion concentration and a threshold value. The water quality control device for a plant according to claim 3.

13. The prediction formula correction unit is configured to obtain the prediction formula for estimating the concentration of the solute or the ion in the cooling water at a current time by weighting the prediction formula based on the actual measured value of the concentration of the solute or the ion in the cooling water at a first time point in the past and the prediction formula based on the actual measured value of the concentration of the solute or the ion in the make-up water at a second time point in the past. The water quality control device for a plant according to claim 2.

14. A heat exchanger; a cooling water circulation line configured to circulate the cooling water supplied to the heat exchanger; The water quality control device according to any one of claims 1 to 13, configured to control the quality of the cooling water; The plant is provided with:

15. Measuring a state quantity indicative of a state of cooling water in a plant; A step of estimating a concentration of the solute or the ion in the cooling water based on the measured state quantity using a prediction equation expressing a relationship between the concentration of the solute or the ion in the cooling water and the state quantity; a step of correcting the prediction equation used for estimating the concentration of the solute or the ion in the cooling water at a past time based on a current actual measurement value of the concentration of the solute or the ion in the cooling water, thereby obtaining the prediction equation for estimating the concentration of the solute or the ion in the cooling water at a current time; Equipped with The state quantity includes at least one of the electrical conductivity of the cooling water, the temperature of the cooling water, or the pH of the cooling water. Plant water quality control methods.

16. Measuring a state quantity indicative of a state of cooling water in a plant; A step of estimating a concentration of the solute or the ion in the cooling water based on the measured state quantity using a prediction equation expressing a relationship between the concentration of the solute or the ion in the cooling water and the state quantity; correcting the prediction formula based on an actual measurement value of a concentration of the solute or the ion in makeup water that is replenished to the cooling water; Equipped with The state quantity includes at least one of the electrical conductivity of the cooling water, the temperature of the cooling water, or the pH of the cooling water. Plant water quality control methods.

Images