JP4388487B2 - Chemical injection control device, chemical injection control method, and plant using this control device - Google Patents

Description

  The present invention relates to a control device, a control method, and an operation method of the plant for controlling the amount of chemicals to be introduced into a fluid flowing inside a plant such as a nuclear power generation secondary system, thermal power generation, and a combined turbine plant.

  In plants such as nuclear power generation secondary systems (condensation systems), thermal power generation, and combined turbine plants, chemicals are added to adjust the pH of water flowing through the plant to prevent corrosion of piping. Yes.

  FIG. 1 shows a schematic layout of the secondary system. The plant PT shown in FIG. 1 generates power by rotating a turbine with steam generated by a steam generator SG, and includes a steam generator SG, a high-pressure turbine 1, and a moisture separation heater 2 (MSR). The low pressure turbine 3, the condenser 4, the demineralizer 5, the low pressure heater 6, the deaerator 7, and the high pressure heater 8 are included. These devices are connected using piping in the order shown above. A bypass path 9 is provided which is arranged in parallel with the desalting apparatus 5 and through which the circulating water bypasses the desalting apparatus 5. An isolation valve 10 and a bypass valve 11 are also provided upstream of the desalting apparatus 5 and the bypass passage 9.

  Water circulating in the plant PT (hereinafter referred to as circulating water) is circulated in the plant PT by being pumped by a circulation pump (not shown). In the plant PT, the circulating water inside the plant PT is heated inside the steam generator SG to become steam. The steam (main steam) generated by the steam generator SG is sent to the high-pressure turbine 1. The main steam drives the high-pressure turbine 1 and the pressure also decreases. Most of the steam that has driven the high-pressure turbine 1 is sent to the moisture separation heater 2. A part of the steam is sent as high-pressure bleed air to a high-pressure heater 8 described later, and heats the water flowing inside. Thereafter, the high-pressure extraction sent to the high-pressure heater 8 is condensed and sent to the deaerator 7 as high-pressure drain water HP-d.

  Excess moisture is separated from the main steam by the moisture separation heater 2 and sent to the low-pressure turbine 3. The water separated by the moisture separator / heater 2 is condensed and sent as MS drain water MS-d to a deaerator tank 71 disposed downstream of the deaerator 7. The main steam discharged from the moisture separator / heater 2 is sent to the low-pressure turbine 3 to drive the low-pressure turbine 3. Most of the steam that has driven the low-pressure turbine 3 flows into the condenser 4. A part of the steam is sent as low-pressure extraction to a low-pressure heater 6 described later, and heats the water flowing inside. Thereafter, the low-pressure bleed air that has flowed through the low-pressure heater 6 is condensed into water and mixed with water flowing into the low-pressure heater 6 as low-pressure drain water LP-d.

  The condenser 4 causes external cold water (seawater here) to flow in an internal pipe (not shown) and passes the heat of the steam to the seawater, thereby condensing the steam into circulating water. The condensed circulating water is sent to the demineralizer 5 or the bypass 9. The desalinator 5 is not limited to this, but is an ion exchange resin, and can remove impurities such as ion components absorbed by water circulating in the plant.

  The water flowing out from the desalinator 5 or the bypass 9 flows into the low pressure heater 6. As described above, the low pressure extraction air flows into the low pressure heater 6 from the low pressure turbine 6. The low pressure heater 6 heats the circulating water by passing the heat of the low pressure extraction air to the circulating water. The circulating water heated by the low-pressure heater 6 is sent to the deaerator 7 and degassed. And it collect | recovers in the deaerator tank 71 provided downstream of the deaerator 7, and is mixed with MS drain water MS-d sent from MSR2. By heating the circulating water with the low-pressure heater 6, it is possible to reduce the amount of heat applied to the circulating water when degassing with the deaerator 7, thereby reducing the consumed energy accordingly.

  The mixed circulating water flows into the high-pressure heater 8. As described above, high-pressure extraction air flows into the high-pressure heater 8 from the high-pressure turbine 1. The high pressure heater 8 heats the circulating water by passing the heat of the high pressure extraction air to the circulating water. The water heated by the high-pressure heater 8 flows into the steam generator SG and becomes steam again by the steam generator SG. By heating the circulating water with the high-pressure heater 8, the amount of heating in the steam generator SG can be reduced, and the energy consumption can be reduced.

  The steam generator SG is connected to a blow-down pipe 14 for sending a part of the accumulated circulating water to the desalinator 5. The blowdown pipe 14 is connected between the desalting apparatus 5 and the isolation valve 10 provided upstream. As a result, blowdown water always flows into the desalinator 5 to remove impurities. In this way, a part of the water of the steam generator SG is sent to the desalinator 5 to remove impurities, so that the quality of the circulating water in the plant PT is kept substantially constant.

  When the water circulating through the plant PT passes through the desalting apparatus 5, the chemical components that are adjusting the pH together with the impurities contained in the water are also removed. Moreover, even when circulating water is made to flow through the bypass 9, the pH is lowered by absorbing carbon dioxide, oxygen, and the like in the system while circulating through the plant PT. Therefore, a chemical charging pump device 51 for charging chemicals is disposed downstream of the desalting apparatus 5.

  The amount of chemical input to the circulating water by the chemical injection pump device 51 is the chemical concentration of the circulating water detected by the chemical concentration detection means 13 (here, conductivity meter) arranged upstream of the steam generator SG of the plant PT. Based on the flow rate detected by the flow meter 12 provided downstream of the low-pressure heater 6, feedback control is performed to set a chemical concentration set value at which the pH of the circulating water becomes a set value and to determine the chemical input amount. It has been broken.

  When the plant PT is operating stably, it flows through the bypass 9. Moreover, the blowdown water flowing through the blowdown pipe 14 from the evaporator SG passes through the desalting apparatus 5 and impurities and chemicals are removed, so that the nature of the water inside the plant PT is kept substantially constant. When impurities in the circulating water increase, the whole or part of the circulating water flowing out of the condenser 4 flows into the demineralizer 5 to remove the impurities.

On the other hand, when the plant PT is started and stopped, an unexpected water quality disturbance such as a seawater leak is likely to occur. In preparation for the occurrence of unexpected water quality disturbances, the plant PT passes the entire amount of circulating water through the desalinator 5 at the start-up. As a result, the pH of the circulating water is lowered compared to that during normal operation, that is, the chemical concentration of the circulating water is lowered. Adjust to start operation. When the circulating water flows stably, the circulating water is passed through the bypass passage 9 to increase the chemical concentration. After the circulating water concentration reaches a predetermined set value, the operation is switched to normal operation. When stopping, adjust the circulating water concentration to a lower level and stop in a stable state.
JP 2001-137834 A JP-A-10-26307

  Usually, in the steam generator SG, the pH of the inflowing water is low, so that problems such as corrosion are likely to occur. Therefore, the chemical concentration detection means 13 detects the concentration of the chemical dissolved in the water flowing into the steam generator SG. In order to do so, it is arranged immediately before the steam generator SG. On the other hand, the chemical injection point for introducing chemicals into the water circulating through the plant PT is provided downstream of the desalinator 5 where the concentration of the chemical dissolved in water is the lowest. It takes a certain amount of time for the water flowing through the chemical injection point to reach the place where the chemical concentration detection means 13 is located.

  Consider a case in which the chemical concentration set value of the circulating water is kept constant and the state is switched from the state where the circulating water flows into the bypass passage 9 to the state where it flows into the desalinator 5. The circulating water that has flowed out of the desalting apparatus 5 has the chemicals removed by the desalting apparatus 5, and the chemical concentration is reduced. However, after the switching, the chemical concentration detected by the chemical concentration detection means 13 flows through the bypass 9 until the circulating water whose chemical concentration has decreased reaches the place where the chemical concentration detection means 13 is located from the chemical injection point. This is the concentration of circulating water when Since the feedback control of the chemical injection is performed based on the concentration, the amount of the chemical input is small (the same amount as when the fluid flows through the bypass passage 9) even though the concentration at the chemical injection point is lowered. Circulating water having a lower concentration than the chemical concentration set value flows through the plant PT.

  Similarly, when switching from the state flowing into the desalting apparatus 5 to the state flowing into the bypass 9, the chemical is not removed. The chemical concentration of the circulating water detected by the chemical concentration detection means 13 is close to the chemical concentration setting value until the circulating water with high chemical concentration reaches the place where the chemical concentration detection means 13 is arranged from the chemical injection point. At the chemical injection point, the chemical input amount when the circulating water has flowed into the desalting apparatus 5 is continuously input. When the amount of chemical input when the chemical is removed by the desalinator 5 is added to the circulating water that has flowed into the bypass 9 and the chemical concentration has not decreased, the circulating water is higher than the chemical concentration setting value. Concentration will continue and more chemicals will be added.

  At this time, when the chemical concentration is lower than the set value, the pipe interior is easily corroded by the water flowing through the pipe, and the corrosion proceeds by operating the plant for a long time. Further, when the chemical concentration becomes higher than the set value, the problem of corrosion does not occur, but more chemical than necessary is input, which affects plant materials and increases the running cost.

  Furthermore, as at the time of start-up, the circulating water is first introduced into the demineralizer 5 and the pH of the circulating water (chemical concentration setting value) is set low, and the pH (chemical concentration) is maintained in a stable flow of the circulating water. When increasing the setting value), it takes a very long time for the pH (chemical concentration setting value) to increase. For example, when the pH of circulating water at startup is 9.2 and the pH at stable operation is 10, assuming that the chemical to be added is ammonia, the ammonia concentration at pH 9.2 is 0.5 ppm, and pH 10 In this case, the ammonia concentration becomes 10 ppm, and it takes a long time to increase the concentration. During this time, it takes time for the plant PT to shift to stable operation.

  On the other hand, when the circulating water that has been flowing to the bypass passage 9 as in the stop is caused to flow to the desalinator 5 and then the pH of the circulating water is lowered to operate, the circulating water flows into the desalinator 5. Immediately after switching to do so, the chemical concentration detected by the chemical concentration detection means 13 is higher than the chemical concentration set value, so that the amount of chemical injection is stopped. However, the concentration of the circulating water flowing out from the desalinator 5 is very low, and the circulating water having a low concentration passes through the plant PT until the circulating water having the low concentration is detected by the chemical concentration detection means 13. To flow.

  In view of such a problem, the present invention introduces an optimal amount of chemicals into the liquid circulating inside the plant in a plant that circulates the liquid inside, and the properties of the liquid are within a certain condition in a short time. The purpose is to fit.

In order to achieve the above object, the present invention provides a plant having a demineralizer that removes impurities in the liquid circulating inside the plant, and a bypass that allows the circulating liquid to flow around the demineralizer. A chemical injection control device that controls chemical injection, a flow rate detection unit that detects a flow rate of a circulating liquid flowing inside the plant, and a concentration detection unit that detects a concentration of a chemical dissolved in the circulating liquid flowing inside the plant, An isolation valve that prevents the circulating liquid from flowing into the demineralizer, a bypass valve that prevents the circulating liquid from flowing into the bypass path, a large pump and a small pump, and the circulating liquid of the medicine feeding section to the disposed upstream of the downstream side and the density detection unit of the desalter and the bypass passage to introduce chemicals into the circulation liquid in the path, of the input of the drug A chemical input control unit for controlling the desiccant in which the circulating liquid is allowed to flow into the desalinator to perform desalting treatment of the circulating liquid, and the circulating liquid is bypassed. The chemical input control unit is operated by switching to a bypass state in which the circulating liquid is not desalted, and the isolation valve is opened, the bypass valve is closed, and the circulating liquid is desalted. The flow rate detected by the flow rate detector and the concentration detected by the concentration detector when either the desalting state flowing in the apparatus or the bypass state in which the isolation valve is closed and the bypass valve is open more the large pump to normal chemical input amount determining method of determining drug dosages based on a normal operation mode for operating the miniature pump, from the bypass state or the bypass state from the desalting conditions When switching the serial to desalination state until a predetermined condition is satisfied, regardless of the concentration detected by the concentration detector, chemical dosages based on the flow rate detected by the preset value and the flow detector more the large pump in a special chemical input amount determining method of determining, and having a special operation mode for operating the miniature pump.

  According to this configuration, when switching from the desalted state to the bypass state or from the bypass state to the desalted state, fluctuations such as the chemical concentration of the liquid circulating in the plant becoming thin or thick are unlikely to occur. Therefore, it is possible to operate the plant stably. Moreover, since the chemical concentration of the circulating liquid does not become too low, it is possible to prevent a problem that occurs when the circulating liquid having a low chemical concentration flows. Here, the desalted state is a state in which the isolation valve is opened and the bypass valve is closed, and the circulating liquid flows in the desalting apparatus to perform desalting treatment of the circulating water. Further, the bypass state is a state in which the isolation valve is closed and the bypass valve is opened so that the circulating liquid does not flow through the desalting apparatus and the desalting treatment of the circulating water is not performed.

The chemical charging unit having the above-described configuration includes the large pump and the small pump including a piston pump whose rotation speed and stroke can be adjusted , and the normal chemical charging amount determination method is configured to set the stroke of the piston pump to the flow rate or concentration. Based on either one, the number of rotations is determined based on the other one, and when the concentration of the circulating liquid is not changed before and after switching to the special operation mode, the special chemical input amount is determined. The method corrects the value determined based on the concentration of the stroke and the number of rotations to a value given in advance according to the state after switching, and determines the amount of medicine input based on the corrected value. May be.

  Further, the chemical charging section having the above-described configuration has two types of constant operation pumps, large and small, according to the amount of chemical input, and a spare pump that operates when the continuous operation pump is stopped. In the determination method, when switching from the desalted state to the bypass state, when the chemical concentration of the circulating liquid is higher than that in the desalted state, the maximum values of the capacities of the always-on pump and the spare pump are set to the chemicals. You may have what is used as input amount.

  According to this configuration, since all the pumps provided are fully operated and the chemicals are charged, it is possible to quickly increase the chemical concentration of the circulating liquid.

  In the above configuration, the predetermined condition of the special operation mode may be that an elapsed time from the switching time reaches a predetermined time, and the concentration detected by the concentration detection unit reaches a predetermined concentration. There may be.

In order to achieve the above object, the present invention provides a demineralizer that removes impurities in the liquid circulating inside the plant, a bypass passage that allows the circulating liquid to flow around the demineralizer, and the inside of the plant. A flow rate detection unit that detects the flow rate of the circulating liquid that flows, a concentration detection unit that detects the concentration of the chemical dissolved in the circulating liquid flowing inside the plant , and an isolation that prevents the circulating liquid from flowing into the desalinator A valve, a bypass valve that prevents the circulating liquid from flowing into the bypass path, a large pump and a small pump, and the downstream of the desalinator and the bypass path and the concentration in the path of the circulating liquid drug input control side to control the chemical supply to plant with a chemical-on control device, a and a medicine supplying portion which is disposed upstream of the detector to introduce the drug into the circulation liquid The flow rate detecting step for detecting the flow rate of the circulating liquid flowing inside the plant, the concentration detecting step for detecting the concentration of the chemical dissolved in the circulating liquid flowing inside the plant, and the circulating liquid from the chemical charging unit. A chemical charging step of charging the chemical into the desalted state in which the isolation valve is opened and the bypass valve is closed and the circulating liquid flows through the desalting apparatus, or the isolation valve is closed and the bypass is closed. when either the bypass state the valve is open, and more usually chemical input amount determining method of determining drug dosages based on the concentration detected by the flow rate detecting the flow rate detected by step concentration detection step the large pump, a normal operation mode for operating the miniature pump, when switching from said the bypass state or the bypass state from the desalting state to the desalting condition, a predetermined condition Plus up, regardless of the concentration detected by the concentration detection means, more the special chemical input amount determining method of determining drug dosages based on the flow rate detected by the value and the flow rate detection unit that is set in advance A large pump and a special operation mode for operating the small pump .

  According to this configuration, when switching from the desalted state to the bypass state or from the bypass state to the desalted state, fluctuations such as the chemical concentration of the liquid circulating in the plant becoming thin or thick are unlikely to occur. Therefore, it is possible to operate the plant stably. Moreover, since the chemical concentration of the circulating liquid does not become too low, it is possible to prevent a problem that occurs when the circulating liquid having a low chemical concentration flows.

The chemical charging unit having the above-described configuration includes the large pump and the small pump including a piston pump whose rotation speed and stroke can be adjusted , and the normal chemical charging amount determination method determines the stroke of the piston pump as the flow rate or concentration. When the rotational speed is determined by the remaining one and the concentration of the circulating liquid is not changed before and after switching to the special operation mode, the special chemical input amount determining method is the stroke And the value determined based on the concentration of the number of rotations is corrected to a value given in advance in accordance with the state after switching, and the amount of medicine input is determined based on the correction value. Also good.

  Further, the chemical charging section having the above-described configuration has two types of constant operation pumps, large and small, according to the amount of chemical input, and a spare pump that operates when the continuous operation pump is stopped. In the determination method, when switching from the desalted state to the bypass state, the chemical concentration of the circulating liquid is higher than that in the desalted state, the maximum values of the capacities of the always-on pump and the reserve pump are set to the amount of chemical input. It may be what has.

  According to this configuration, since all the pumps provided are fully operated and the chemicals are charged, it is possible to quickly increase the chemical concentration of the circulating liquid.

  In the above configuration, the predetermined condition of the special operation mode may be that an elapsed time from the switching time reaches a predetermined time, and that the concentration detected by the concentration detector reaches a predetermined concentration. May be.

In order to achieve the above object, the present invention provides a desalination apparatus for removing impurities in a liquid circulating inside, a bypass passage for allowing the circulating liquid to flow around the desalination apparatus, and a flow inside the plant. A flow rate detecting unit for detecting the flow rate of the circulating liquid, a concentration detecting unit for detecting the concentration of the chemical dissolved in the circulating liquid flowing inside the plant, and an isolation valve for preventing the circulating liquid from flowing into the desalinator. And a bypass valve for preventing the circulating liquid from flowing into the bypass passage, a large pump and a small pump, and the concentration detection in the circulating fluid path downstream of the desalinator and the bypass path A plant that is disposed upstream of a unit and that has a chemical input unit that supplies chemicals to the circulating liquid, and a chemical input control unit that controls the input of the chemicals, A desalted state in which the circulating liquid is allowed to flow into the desalting apparatus and the circulating liquid is desalted; and a bypass state in which the circulating liquid is allowed to flow into the bypass passage and the circulating liquid is not desalted. The chemical injection control unit opens the isolation valve and closes the bypass valve so that the circulating liquid flows in the desalting apparatus or the isolation valve closes and the bypass is closed. when the bypass state of any valve is open, more the normal chemical input amount determining method of determining drug dosages based on concentration detected from the flow rate detected from the flow detector the concentration detection unit large pumps, a normal operation mode for operating the miniature pump, when the from desalting state switched to the desalination state from the bypass state or the bypass state until a predetermined condition is satisfied, the concentration Regardless of the concentration detected by the detecting means, more the large pump in a special chemical input amount determining method of determining drug dosages based on the flow rate detected by the value and the flow rate detection unit that is set in advance, the small And a special operation mode for operating the pump .

  According to this configuration, when switching from the desalted state to the bypass state or from the bypass state to the desalted state, fluctuations such as the chemical concentration of the liquid circulating in the plant becoming thin or thick are unlikely to occur. Therefore, it is possible to operate the plant stably. Moreover, since the chemical concentration of the circulating liquid does not become too low, it is possible to prevent a problem that occurs when the circulating liquid having a low chemical concentration flows.

The chemical charging unit having the above-described configuration includes the large pump and the small pump including a piston pump whose rotation speed and stroke can be adjusted , and the normal chemical charging amount determination method is configured to set the stroke of the piston pump to the flow rate or concentration. When determining one of them and the number of rotations based on the remaining one and not changing the concentration of the circulating liquid before and after switching to the special operation mode, the special chemical input amount determination method includes the stroke and The chemical input amount may be determined based on a value determined in advance based on the concentration in the number of rotations based on a value given in advance in accordance with the state after switching.

  Further, the chemical charging section having the above-described configuration has two types of constant operation pumps, large and small, according to the amount of chemical input, and a spare pump that operates when the continuous operation pump is stopped. In the determination method, when switching from the desalted state to the bypass state, the chemical concentration of the circulating liquid is higher than that in the desalted state, the maximum values of the capacities of the always-on pump and the reserve pump are set to the amount of chemical input. The thing which has what is said can be illustrated.

  According to this configuration, since all the pumps provided are fully operated and the chemicals are charged, it is possible to quickly increase the chemical concentration of the circulating liquid.

  In the above configuration, the predetermined condition of the special operation mode may be that an elapsed time from the switching time reaches a predetermined time, and that the concentration detected by the concentration detector reaches a predetermined concentration. May be.

  According to the present invention, in a plant that circulates liquid inside, an optimal amount of chemicals can be introduced into the liquid that circulates inside the plant, and the properties of the liquid can be kept within certain conditions in a short time. .

  The best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a schematic perspective view of an example of a plant using the chemical injection control method according to the present invention. The plant shown in FIG. 1 is a secondary system of nuclear power generation equipment.

  The plant PT shown in FIG. 1 generates power by rotating a turbine with steam generated by a steam generator SG, and includes a steam generator SG, a high-pressure turbine 1, and a moisture separation heater 2 (MSR). The low pressure turbine 3, the condenser 4, the demineralizer 5, the low pressure heater 6, the deaerator 7, and the high pressure heater 8 are included. These devices are connected using piping in the order shown above.

  Water circulating in the plant PT (hereinafter referred to as circulating water) is circulated in the plant PT by being pumped by a circulation pump (not shown). A bypass path 9 is provided which is arranged in parallel with the desalting apparatus 5 and through which the circulating water bypasses the desalting apparatus 5. An isolation valve 10 is provided upstream of the desalting apparatus 5, and a bypass valve 11 is also provided in the bypass passage 9.

  In the secondary system of nuclear power generation, chemicals are poured into the water flowing in the piping in order to prevent corrosion of the piping. The chemical is not limited thereto, but ammonia (NH3), hydrazine (N2H4), ethanolamine, and the like are used here. By adding a predetermined amount of chemicals to the circulating water circulating in the secondary system, the pH of the flowing water can be raised. By raising the pH, corrosion of piping and equipment can be prevented, and stress corrosion cracking can also be prevented.

  In the present embodiment, a chemical charging pump device 51 for supplying the above-described chemicals is provided on the downstream side of the desalting device 5 and the bypass passage 9, and the circulating water that has passed through the desalting device 5 and the bypass passage 9 is provided. Chemicals. The chemical charging pump device 51 has a small pump 511 used when the circulating water flows into the bypass passage 9 and a large pump 512 used when the circulating water flows into the demineralizer 5. is doing. The small pump 511 and the large pump 512 used in the chemical charging pump device 51 are not limited thereto, but are piston pumps here.

  A flow meter 12 for detecting the flow rate of circulating water is detected between the low-pressure heater 6 and the deaerator 7, and a chemical concentration (pH) of water flowing into the steam generator SG is detected upstream of the steam generator SG. Concentration detection means 13 (here, the concentration of the chemical is detected by detecting the conductivity of the circulating water) is arranged. As described above, the chemical injection pump device 51 uses the piston pump, and the pump discharge amount is determined by the stroke and the rotational speed of the piston.

  The plant PT includes a chemical charging control device C1, and the chemical charging control device C1 includes a chemical charging pump device 51, an isolation valve 10, a bypass valve 11, a flow meter 12, a concentration detection means 13, and a control device Cont. . In this embodiment, the control device Cont determines the rotation speed based on the flow rate measured by the flow meter 12 and the stroke based on the concentration detected by the concentration detection means 13.

  In the plant PT, the circulating water inside the plant PT is heated inside the steam generator SG to become steam. The steam (main steam) generated by the steam generator SG is sent to the high-pressure turbine 1. The main steam drives the high-pressure turbine 1 and the pressure also decreases. Most of the steam that has driven the high-pressure turbine 1 is sent to the moisture separation heater 2. A part of the steam is sent as high-pressure bleed air to a high-pressure heater 8 described later, and heats the water flowing inside. Thereafter, the high-pressure extraction sent to the high-pressure heater 8 is condensed and sent to the deaerator 7 as high-pressure drain water HP-d.

  Excess moisture is separated from the main steam by the moisture separation heater 2 and sent to the low-pressure turbine 3. The water separated by the moisture separator / heater 2 is condensed and sent as MS drain water MS-d to a deaerator tank 71 disposed downstream of the deaerator 7. The main steam discharged from the moisture separator / heater 2 is sent to the low-pressure turbine 3 to drive the low-pressure turbine 3. Most of the steam that has driven the low-pressure turbine 3 flows into the condenser 4. A part of the steam is sent as low-pressure extraction to a low-pressure heater 6 described later, and heats the water flowing inside. Thereafter, the low-pressure bleed air that has flowed through the low-pressure heater 6 is condensed into water and mixed with water flowing into the low-pressure heater 6 as low-pressure drain water LP-d.

  The condenser 4 causes external cold water (here, seawater) to flow in an internal pipe (not shown) and passes the heat of the steam to the seawater, thereby condensing the steam into circulating water. The condensed circulating water is sent to the desalinator 5. The desalinator 5 is not limited to this, but is an ion exchange resin, and can remove impurities such as ion components absorbed by water circulating in the plant.

  The water flowing out from the desalinator 5 or the bypass 9 flows into the low pressure heater 6. As described above, the low pressure extraction air flows into the low pressure heater 6 from the low pressure turbine 6. The low pressure heater 6 heats the circulating water by passing the heat of the low pressure extraction air to the circulating water. The circulating water heated by the low-pressure heater 6 is sent to the deaerator 7 and degassed. And it collect | recovers in the deaerator tank 71 provided downstream of the deaerator 7, and is mixed with MS drain water MS-d sent from MSR2. Heating the circulating water with the low-pressure heater 6 can reduce the amount of heat applied to the circulating water when degassing with the deaerator 7, thereby reducing energy consumption accordingly.

  The mixed circulating water flows into the high-pressure heater 8. As described above, high-pressure extraction air flows into the high-pressure heater 8 from the high-pressure turbine 1. The high pressure heater 8 heats the circulating water by passing the heat of the high pressure extraction air to the circulating water. The water heated by the high-pressure heater 8 flows into the steam generator SG and becomes steam again by the steam generator SG. By heating the circulating water with the high-pressure heater 8, the amount of heating in the steam generator SG can be reduced, and the energy consumption can be reduced.

  The steam generator SG is connected to a blow-down pipe 14 for sending a part of the accumulated circulating water to the desalinator 5. The blowdown pipe 14 is connected between the desalting apparatus 5 and the isolation valve 10 provided upstream. Thereby, even when the isolation valve 10 is closed and the circulating water passes through the bypass 9, the blow-down water flows into the desalinator 5 and impurities are removed. In this way, a part of the water of the steam generator SG is sent to the desalinator 5 to remove impurities, so that the quality of the circulating water in the plant PT is kept substantially constant.

  The chemical injection of the chemical injection pump device 51 has an operation mode different from the normal operation mode and the transient operation mode. The normal operation mode is adopted when the circulating water is constantly flowing into the desalinator 5 or the bypass 9 and the concentration of the chemical dissolved in the circulating water is stable and does not change greatly from the specified value. The In the normal operation mode, the rotational speed and stroke of the small pump 511 or the large pump 512 are determined based on the flow rate measured by the flow meter 12 and the concentration detected by the concentration detection means 13 (feedback control).

  FIG. 2 shows a flowchart of the chemical injection in the normal operation mode. The flow rate of the circulating water is detected by the flow meter 12 (step S1), and the chemical concentration of the circulating water is detected by the chemical concentration detection means 13 (step S2). Then, it is detected whether the isolation valve 10 is open (step S3). When the isolation valve 10 is open (in the case of YES in step S3), the control device Cont recognizes that the circulating water flows into the desalting device 5 and the amount of chemical injected into the outlet of the desalting device 5 is large. A large pump 512 that can be charged with chemicals is employed (step S4). The control device Cont determines the rotational speed of the large pump 512 based on the flow rate detected by the flow meter 12 in step S1 (step S5), and the large pump based on the chemical concentration detected by the concentration detecting means 13 in step S2. The stroke of 512 is determined (step S6). The large pump 512 is driven in accordance with the rotational speed determined in step S5 and the stroke determined in step S6 (step S7), and the process returns to step S1.

  When the isolation valve 10 is closed (in the case of NO in step S3), if the control device Cont has circulating water flowing into the bypass passage 9 and the amount of chemical injected into the bypass passage 9 outlet (desalination device 5 outlet) is small Recognizing and adopting the small pump 511 with less chemical input (step S8). The control device Cont determines the rotational speed of the small pump 511 based on the flow rate detected by the flow meter 12 in step S1 (step S9), and the small pump based on the chemical concentration detected by the concentration detecting means 13 in step S2. The stroke of 511 is determined (step S10). The small pump 511 is driven according to the rotational speed determined in step S9 and the stroke determined in step S10 (step S11), and the process returns to step S1.

  As described above, the chemical concentration of the circulating water in the normal operation mode can be controlled to be constant by controlling the chemical charging pump device 51. Moreover, immediately after switching so that the circulating water flows into the demineralizer 5 from the state where the circulating water flows into the bypass channel 9, or immediately after the circulating water flows into the bypass channel 9, the circulating water flows into the desalinator 5. In the case where the chemical concentration of the circulating water changes more than the specified value immediately after switching as described above, the transient operation mode is adopted. The transient operation mode is further subdivided as shown below.

(First transient operation mode)
In the first transient operation mode, switching is performed so that the circulating water flowing in the bypass 9 flows into the desalinator 5 so that the chemical concentration of the circulating water does not change before and after switching. FIG. 3 shows a flowchart of operation in the first transient operation mode. When the isolation valve 10 is closed and the bypass valve 11 is open, the control device Cont opens the isolation valve 10 and closes the bypass valve 11 (step SA1). Since the chemical concentration of the circulating water decreases when the circulating water starts to flow into the desalinator 5, the controller Cont switches from the small pump 511 to the large pump 512 (step SA2). The flow rate of the circulating water is detected by the flow meter 12 (step SA3), and the chemical concentration of the circulating water is detected by the chemical concentration detection means 13 (step SA4).

  At this time, a stroke set in advance is set regardless of the concentration detected by the chemical concentration detection means 13 (step SA5), and the rotational speed (step SA6) is based on the flow rate detected by the flow meter 12 in step SA3. ). The large pump 512 is operated based on the stroke set in step SA5 and the rotation speed set in step SA6 (step SA7). It is determined whether the time t after switching the isolation valve 10 and the bypass valve 11 in step SA1 is longer than the predetermined time T (step SA8). If the time t is shorter than the predetermined time T (NO in step SA8), the process returns to step SA8. When the time t is longer than the predetermined time T (in the case of YES at step SA8), the first transient operation mode is terminated and switched to the normal operation mode shown in FIG.

  Here, the stroke determined in step SA5 is not limited thereto, but is determined based on the stroke in the normal operation mode in which the circulating water flows into the desalinator 5, and is used in step SA8. The predetermined time T is determined based on the time until the circulating water reaches the installation portion of the chemical concentration detection means 13 from the desalting apparatus 5. Thus, after switching from the state in which circulating water flows into the bypass channel 9 to the state in which the circulating water flows into the desalinator 5, the circulating water that has flowed out of the desalinator 5 reaches the installation location of the chemical concentration detection means 13. During this period, the chemical is forcibly introduced, so that circulating water having a low chemical concentration can be prevented from flowing in the system.

(Second transient operation mode)
In the second transient operation mode, the circulating water flowing through the desalinator 5 is switched so as to flow into the bypass passage 9 so that the chemical concentration of the circulating water does not change before and after switching. FIG. 4 shows a flowchart of operation in the second transient operation mode. When the isolation valve 10 is open and the bypass valve 11 is closed, the control device Cont performs an operation of closing the isolation valve 10 and opening the bypass valve 11 (step SB1). When the circulating water does not flow into the desalting apparatus 5, the chemical of the circulating water is not removed and the concentration fluctuation becomes small. Therefore, the controller Cont switches from the large pump 512 to the small pump 511 (step SB2). The flow meter 12 detects the flow rate of the circulating water (step SB3), and the chemical concentration detection means 13 detects the chemical concentration of the circulating water (step SB4).

  At this time, a stroke set in advance is set regardless of the concentration detected by the chemical concentration detection means 13 (step SB5), and the rotation speed (step SB6) is based on the flow rate detected by the flow meter 12 in step SB3. ). The small pump 511 is operated based on the stroke set in step SB5 and the rotation speed set in step SB6 (step SB7). It is determined whether the time t after switching the isolation valve 10 and the bypass valve 11 in step SB1 is longer than the predetermined time T (step SB8). If the time t is shorter than the predetermined time T (NO in step SB8), the process returns to step SB8. When the time t is longer than the predetermined time T (in the case of YES at step SB8), the second transient operation mode is terminated and switched to the normal operation mode shown in FIG.

  Here, the stroke determined in step SB5 is not limited thereto, but is determined based on the stroke in the normal operation mode in which the circulating water flows into the bypass 9 and is used in step SB8. The predetermined time T is determined based on the time until the circulating water reaches the installation part of the chemical concentration detection means 13 from the outlet of the bypass 9. Thus, after switching from the state in which circulating water flows into the desalination apparatus 5 to the state in which it flows into the bypass 9, the circulating water that has flowed out of the bypass 9 reaches the place where the chemical concentration detection means 13 is installed. During this time, the amount of chemicals to be charged is forcibly restricted, so that circulating water having a chemical concentration higher than necessary can be prevented from flowing through the system, and wasteful chemical input can be prevented.

(Third transient operation mode)
In the third transient operation mode, the circulating water flowing through the desalinator 5 is switched so as to flow into the bypass passage 9, and the chemical concentration of the circulating water is operated to be higher after switching than before switching. It is. FIG. 5 shows a flowchart of the operation in the third transient operation mode. When the isolation valve 10 is open and the bypass valve 11 is closed, the control device Cont performs an operation of closing the isolation valve 10 and opening the bypass valve 11 (step SC1). In the third transient operation mode, the controller Cont uses both the small pump 511 and the large pump 512 in order to increase the chemical concentration of the circulating water (step SC2). In addition, although not shown, a spare small pump and a large pump provided for when trouble occurs are also used (step SC3).

  The controller Cont determines the maximum stroke and rotation speed of each pump (step SC4). Each pump is driven (step SC5). The controller Cont detects the chemical concentration of the circulating water by the chemical concentration detection means 13 (step SC6). It is compared whether or not the chemical concentration n detected by the chemical concentration detection means 13 is larger than the predetermined concentration N (step SC7). If the chemical concentration n is smaller than the predetermined concentration N (NO in step SC7), the process returns to step SC6 to detect the concentration. When the chemical concentration n is equal to or exceeds the predetermined concentration N (YES in step SC7), the third transient operation mode is terminated and the normal operation mode is switched.

  Here, the third transient operation mode is an operation mode for changing the chemical concentration of the circulating water from a low state to a high state. For example, from the low concentration state of the circulating water at the start of the plant PT, The thing which makes circulating water high concentration like this can be mentioned. The predetermined concentration N used in step SC7 is determined based on the time until the circulating water reaches the installation portion of the chemical concentration detection means 13 from the outlet of the bypass passage 9 and the increasing degree of the chemical concentration of the circulating water. Thus, after switching from the state in which circulating water flows into the demineralizer 5 to the state in which it flows into the bypass 9, until the concentration of the chemical concentration detection means 13 reaches a high concentration, the chemical injection pump device 51. Since the amount of chemical input is increased at the maximum capacity, the time required for the circulating water chemical concentration to reach a predetermined concentration can be shortened, and the operating rate of the plant PT can be increased accordingly.

  In the above-described embodiment, the secondary system of the nuclear power plant is described as an example. However, the present invention is not limited to this, and water is circulated in pipes of thermal power generation, combined turbine plant, etc., and chemicals are supplied to the internal circulating water. It can be widely used in the plant to be charged. In the above-described embodiment, the stroke is determined based on the density based on the flow rate, but the present invention is not limited to this. The rotational speed is determined based on the density detected by the density detecting means 13. The stroke may be determined based on the flow rate measured by the flow meter 12.

1 is a schematic layout diagram of an example of a plant that uses a chemical input amount calculation method according to the present invention. It is a flowchart of chemical | medical agent injection | pouring at the time of normal operation mode. It is a flowchart of the driving | operation in the 1st transient operation mode. It is a flowchart of the driving | operation in the 2nd transient operation mode. It is a flowchart of the driving | operation in the 3rd transient operation mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High pressure turbine 2 Moisture separation heater 3 Low pressure turbine 4 Condenser 5 Desalination device 51 Chemical injection pump device 511 Small pump 512 Large pump 6 Low pressure heater 7 Deaerator 71 Deaerator tank 8 High pressure heater 9 Bypass path 10 Isolation valve 11 Bypass valve 12 Flow meter 13 Concentration detection means 14 Blow-down piping SG Steam generator

Claims (15)

A chemical injection control device for controlling chemical injection into a plant, comprising: a desalination device that removes impurities in the liquid circulating inside the plant; and a bypass that allows the circulating liquid to flow around the desalination device. And
A flow rate detection unit for detecting the flow rate of the circulating liquid flowing inside the plant;
A concentration detector for detecting the concentration of the chemical dissolved in the circulating liquid flowing inside the plant;
An isolation valve for preventing the circulating liquid from flowing into the demineralizer;
A bypass valve for preventing the circulating liquid from flowing into the bypass passage;
A large-sized pump and a small-sized pump, a chemical charging unit disposed in the circulating liquid path on the downstream side of the desalting apparatus and the bypass path and upstream of the concentration detection unit ;
A chemical injection control unit for controlling the chemical injection,
The plant causes the circulating liquid to flow into the demineralizer, a desalting state in which the circulating liquid is desalted, and the circulating liquid to flow into the bypass path to perform the desalting process of the circulating liquid. There is no operation to switch between the bypass state and
The chemical input control unit has either the desalting state in which the isolation valve is opened and the bypass valve is closed and the circulating liquid flows in the desalination apparatus, or the bypass state in which the isolation valve is closed and the bypass valve is open. Kano time, operating more the large pump, the miniature pump to the normal chemical input amount determining method of determining drug dosages based on concentration detected from the flow rate detected from the flow detector the concentration detection unit Normal operation mode,
When switching from the desalted state to the bypass state or from the bypass state to the desalted state , a preset value and flow rate are satisfied regardless of the concentration detected by the concentration detecting means until a predetermined condition is satisfied. more the large pump in a special chemical input amount determining method of determining drug dosages based on the flow rate detected by the detection unit, medicine input control apparatus characterized by having a special operation mode for operating the miniature pump. The chemical charging unit includes the large pump and the small pump including a piston pump whose rotation speed and stroke can be adjusted , and the normal chemical charging amount determination method uses either the flow rate or the concentration of the stroke of the piston pump. Based on one, the rotational speed is determined based on the remaining one, and when the concentration of the circulating liquid is not changed before and after switching to the special operation mode, the special chemical input amount determination method is The value determined based on the concentration of the stroke and the number of rotations is corrected to a value given in advance in accordance with the state after switching, and the chemical input amount is determined based on the correction value. The chemical injection control device according to claim 1, wherein The chemical charging section has two types of constant operation pumps, large and small, according to the amount of chemical input,
A spare pump that operates when the normally operating pump is stopped,
In the method for determining the amount of the special chemical input, when the chemical concentration of the circulating liquid is higher than that in the desalted state when switching from the desalted state to the bypass state, the maximum capacity of the always-on pump and the spare pump is maximized. 3. The chemical injection control device according to claim 1, wherein the chemical injection control device has a value as a chemical input amount. The chemical injection control device according to claim 1, 2 or 3, wherein the predetermined condition of the special operation mode is that an elapsed time from the switching time reaches a predetermined time. The chemical injection control device according to any one of claims 1 to 4, wherein the predetermined condition of the special operation mode is that the concentration detected by the concentration detector reaches a predetermined concentration. . A demineralizer that removes liquid impurities circulating inside the plant;
A bypass for allowing the circulating liquid to flow around the demineralizer;
A flow rate detecting unit for detecting a flow rate of the circulating liquid flowing inside the plant, a concentration detecting unit for detecting a concentration of a chemical dissolved in the circulating liquid flowing inside the plant, and the circulating liquid flowing into the demineralizer. An isolation valve for preventing the circulating fluid, a bypass valve for preventing the circulating liquid from flowing into the bypass passage, a large pump and a small pump, and the downstream of the demineralizer and the bypass passage in the circulating fluid path A chemical input control device for controlling chemical input to a plant , comprising a chemical input control device having a chemical input unit disposed on the side and upstream of the concentration detection unit and configured to supply a chemical to the circulating liquid,
A flow rate detection step for detecting the flow rate of the circulating liquid flowing inside the plant;
A concentration detection step for detecting the concentration of the chemical dissolved in the circulating liquid flowing inside the plant;
A chemical charging step of charging chemical into the circulating liquid from the chemical charging unit,
When the isolation valve is open and the bypass valve is closed, the flow rate detection is performed in either a desalting state in which the circulating liquid flows in the desalination apparatus or a bypass state in which the isolation valve is closed and the bypass valve is open. a normal operation mode for operating more the large pump, the miniature pump to the normal chemical input amount determining method of determining drug dosages based on the concentration detected by the flow rate and the concentration detecting step detected by the step,
When switching from the desalted state to the bypass state or from the bypass state to the desalted state , a preset value and flow rate are satisfied regardless of the concentration detected by the concentration detecting means until a predetermined condition is satisfied. drug input control method characterized by having the basis of the flow rate detected by the detector more the large pumps special chemicals input amount determining method of determining the chemical dosages, the special operation mode for operating the miniature pump. The chemical charging unit includes the large pump and the small pump including a piston pump whose rotation speed and stroke can be adjusted , and the normal chemical charging amount determination method uses either the flow rate or the concentration of the stroke of the piston pump. When determining one and the number of revolutions based on the other one and not changing the concentration of the circulating liquid before and after switching to the special operation mode, the method for determining the amount of the special chemical is determined by the stroke and the number of revolutions. 7. The method according to claim 6, further comprising: determining a chemical input amount based on a value determined in advance based on a concentration, based on a value given in advance in accordance with a state after switching. Chemical input control method. The chemical charging section has two types of constant operation pumps, large and small, according to the amount of chemical input,
A spare pump that operates when the normally operating pump is stopped,
In the method for determining the amount of the special chemical input, when the chemical concentration of the circulating liquid is higher than that in the desalted state when switching from the desalted state to the bypass state, the maximum capacity of the always-on pump and the spare pump is maximized. 8. The chemical injection control method according to claim 6 or 7, wherein the value is a chemical input amount.   9. The chemical injection control method according to claim 6, 7 or 8, wherein the predetermined condition of the special operation mode is that an elapsed time from the switching time reaches a predetermined time.   The chemical injection control method according to any one of claims 6 to 9, wherein the predetermined condition of the special operation mode is that the concentration detected by the concentration detector reaches a predetermined concentration. . A desalination device that removes impurities in the liquid circulating inside,
A bypass for allowing the circulating liquid to flow around the demineralizer;
A flow rate detection unit for detecting the flow rate of the circulating liquid flowing inside the plant;
A concentration detector for detecting the concentration of the chemical dissolved in the circulating liquid flowing inside the plant;
An isolation valve for preventing the circulating liquid from flowing into the demineralizer;
A bypass valve for preventing the circulating liquid from flowing into the bypass passage;
A large-sized pump and a small-sized pump, a chemical charging unit disposed in the circulating liquid path on the downstream side of the desalting apparatus and the bypass path and upstream of the concentration detection unit ;
A plant having a chemical charging control unit for controlling the charging of the chemical, the plant flowing the circulating liquid into the desalting apparatus, and a desalting state for performing a desalting treatment of the circulating liquid; The circulating liquid is allowed to flow into the bypass passage, and is operated by switching to a bypass state where the circulating liquid is not desalted.
The chemical input control unit has either the desalting state in which the isolation valve is opened and the bypass valve is closed and the circulating liquid flows in the desalination apparatus, or the bypass state in which the isolation valve is closed and the bypass valve is open. Kano time, operating more the large pump, the miniature pump to the normal chemical input amount determining method of determining drug dosages based on concentration detected from the flow rate detected from the flow detector the concentration detection unit Normal operation mode,
When switching from the desalted state to the bypass state or from the bypass state to the desalted state , a preset value and flow rate are satisfied regardless of the concentration detected by the concentration detecting means until a predetermined condition is satisfied. more the large pump in a special chemical input amount determining method of determining drug dosages based on the flow rate detected by the detection unit, plant characterized by having a special operation mode for operating the miniature pump. The chemical charging unit includes the large pump and the small pump including a piston pump whose rotation speed and stroke can be adjusted , and the normal chemical charging amount determination method uses either the flow rate or the concentration of the stroke of the piston pump. Based on the one and the number of rotations is determined based on the other one, and when the concentration of the circulating liquid is not changed before and after switching to the special operation mode, the special chemical input amount determination method is The value determined based on the concentration of the stroke and the number of rotations is corrected to a value given in advance in accordance with the state after switching, and the chemical input amount is determined based on the correction value. The plant according to claim 11, characterized in that The said chemical | medical agent injection | throwing-in means are two types of normal operation pumps large and small according to chemical | medical agent input amount,
A spare pump that operates when the normally operating pump is stopped,
In the method for determining the amount of the special chemical input, when the chemical concentration of the circulating liquid is higher than that in the desalted state when switching from the desalted state to the bypass state, the maximum capacity of the always-on pump and the spare pump is maximized. The plant according to claim 11 or 12, wherein the plant has a value as a chemical input amount.   14. The plant according to claim 11, wherein the predetermined condition of the special operation mode is that an elapsed time from the switching time reaches a predetermined time.   The plant according to any one of claims 11 to 14, wherein the predetermined condition of the special operation mode is that the concentration detected by the concentration detector reaches a predetermined concentration.

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