Blow-by water neutralizing device

Abstract

To provide a blow water neutralizing device having a simplified structure.SOLUTION: In the blowdown water neutralizing device, the water temperature sensor is provided on the suction side of the transfer pump in the transfer flow path. The inverter adjusts an operating frequency of the transfer pump. When the blow water is transferred from the storage tank to the neutralization tank through the transfer flow path, the control unit sets an operation frequency at which cavitation does not occur in the blow water to the inverter based on a detection result of the water temperature sensor.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a blow water neutralizer, and more particularly to a blow water neutralizer that neutralizes blow water using exhaust gas from a boiler. [Background technology]

[0002] The boiler water inside a boiler, which heats water to generate steam, becomes strongly alkaline due to impurities contained in the water it is fed into. Before this boiler water can be discharged outside the factory, it must be neutralized to meet specified wastewater standards. A conventional neutralization process is known in which exhaust gas is mixed with boiler water (hereinafter referred to as "blow water") discharged from a boiler to neutralize the exhaust gas. The blow water neutralization device for performing the neutralization process includes a tank for storing the blow water and an exhaust gas mixing device (including, for example, a circulation flow path, a pump, and an ejector) for circulating the blow water and mixing the exhaust gas into the blow water (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-251685 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-187738 Summary of the Invention [Problem to be solved by the invention]

[0004] Blow water is generally at a high temperature (e.g., 95°C), and if it is immediately neutralized after being supplied to the blow water tank, cavitation will occur in the pump. Cavitation is a phenomenon in which bubbles are generated by dissolved gas or boiling when the pressure in a liquid flow drops below the saturated vapor pressure. In this phenomenon, bubbles are generated and disappear in an instant, generating strong pressure waves that cause noise and vibration. As a result, the pump's water delivery capacity (pressure and flow rate) decreases.

[0005] Generally, to prevent cavitation in a blow-water neutralization device, two things are necessary: ​​lowering the blow-water temperature and ensuring a specified water level in the tank. Furthermore, when it is required to constantly receive blow water and perform neutralization, two tanks are provided and neutralization is performed alternately in the two tanks to maintain a high water level in the tanks to prevent cavitation (see, for example, Patent Document 2). That is, in the first state, the blow water in the second tank is neutralized while the first tank is storing blow water. In the second state, the blow water in the first tank is neutralized while the second tank is storing blow water. In the above-described device, both of the two tanks need to be switched between the first state and the second state, which increases the number of switching valves and further complicates the piping and tanks.

[0006] An object of the present invention is to provide a blow-underwater neutralization device having a simplified structure. [Means for solving the problem]

[0007] (1) A blow water neutralization device is a device for neutralizing blow water using exhaust gas from a boiler, and comprises: a storage tank in which the blow water is stored; a neutralization tank used to neutralize the blow water; an exhaust gas supply device that supplies the exhaust gas to the blow water in the neutralization tank; a transfer flow path connecting the storage tank and the neutralization tank; a transfer pump provided in the transfer flow path and transferring the blow water from the storage tank to the neutralization tank; a water temperature sensor provided on the suction side of the transfer pump in the transfer flow path; an inverter that adjusts the operating frequency of the transfer pump; and a control unit that sets an operating frequency in the inverter based on the detection result of the water temperature sensor when the blow water is being transferred from the storage tank to the neutralization tank through the transfer flow path so that cavitation does not occur in the blow water flowing through the transfer flow path.

[0008] (1) When the temperature of the blow water is, for example, 97°C, if the operating frequency of the transfer pump is 50 Hz and cavitation is likely to occur in the transfer pump, the blow water neutralization device can prevent cavitation by lowering the operating frequency of the pump to, for example, 30 Hz.

[0009] (2) The blow water neutralization device further includes a water level detection means for detecting the water level of the blow water in the storage tank, and the control unit controls the inverter based on the detection results of the water temperature sensor and the detection results of the water level detection means.

[0010] In the blow water neutralization device (2), the "predetermined value of the blow water temperature" that serves as the standard for comparing the operating frequency can be accurately determined by taking into account the water level of the blow water in the storage tank. For example, if the water level is high, the "predetermined value" will be high, and if the water level is low, the "predetermined value" will be low.

[0011] (3) In the blow water neutralization device, the water level detection means includes a water level sensor that detects the water level of the blow water in the storage tank.

[0012] (3) The blow water neutralization device has a simple structure that can detect the water level of the blow water in the storage tank.

[0013] (4) In the blow water neutralization device, the water level detection means includes a water level calculation unit that calculates the water level of the blow water in the storage tank based on the elapsed time from the start of transfer of the blow water and the flow rate of the transfer pump.

[0014] (4) The blow water neutralization device can detect the blow water level in the storage tank without using a sensor.

[0015] (5) The blow-down neutralization device further includes a sensor provided on the discharge side of the transfer pump in the transfer flow path for detecting the pressure or flow rate of the transfer pump, and an alarm means for issuing an alarm when the pressure or flow rate of the transfer pump is lower than a reference value corresponding to the operating frequency.

[0016] (5) The blow-underwater neutralization device allows for early detection of the occurrence of cavitation. [Effects of the Invention]

[0017] According to the present invention, a blow-type submersion device having a simplified structure can be obtained. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram of a blow-type submersion device according to a first embodiment of the present invention, showing a storage process. [Figure 2] FIG. 2 is a block diagram showing the control configuration of the blow underwater neutralization device. [Figure 3] FIG. 1 is a schematic diagram of a blow-water neutralization device showing the transfer process. [Figure 4] Schematic diagram of a blown hydroneutralizer showing the neutralization and cooling steps. [Figure 5] FIG. 1 is a schematic diagram of a blow-on hydroneutralizer showing the discharge process. [Figure 6] FIG. 10 is a block diagram showing the control configuration of the blow underwater neutralization device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] 1. First embodiment (1) Outline of the blow-underwater neutralization device The blow-type submersion device 1 according to the first embodiment will be described with reference to Figure 1. In each figure, the white triangular portion of each valve indicates the valve body in the open state, and the black triangular portion of each valve indicates the valve body in the closed state.

[0020] The blow water neutralization device 1 is a device that neutralizes alkaline blow water 14 from a steam boiler (not shown) with carbon dioxide gas contained in the boiler exhaust gas 15, cools it, and discharges it as treated water that complies with wastewater standards.

[0021] The blow-water neutralization device 1 mainly includes a storage tank 3, a neutralization tank 4, an exhaust gas supply device 5, a transfer flow path 6, a transfer pump 7, a water temperature sensor 8, an inverter 9, and a control unit 41 (Figure 2).

[0022] The blow-underwater neutralization device 1 further includes a pressure sensor 10 (sensor) and an alarm device 51 (FIG. 2).

[0023] The blow-water neutralization device 1 further includes a pH sensor 11, a first water level sensor 17, and a second water level sensor . (2) Detailed configuration of the blow-underwater neutralization device (2-1) Storage tank Blow water 14 is stored in the storage tank 3. Specifically, the blow water 14 is supplied from the steam boiler to the storage tank 3 via a water supply passage 33. A water supply valve 34 is provided in the water supply passage 33. A first discharge flow path 35 for discharging the blow water 14 is connected to the bottom of the storage tank 3.

[0024] (2-2) Neutralization tank The neutralization tank 4 is used to neutralize the blown water 14. A second discharge flow path 36 that discharges the blown water 14 is connected to the bottom of the neutralization tank 4. The first discharge flow path 35 and the second discharge flow path 36 are connected to the transfer flow path 6 via a first three-way valve 37. The first three-way valve 37 is an automatic valve that can switch the supply source of the blown water 14 supplied to the transfer flow path 6 between the storage tank 3 and the neutralization tank 4. In other words, the blown water 14 in the storage tank 3 and the blown water 14 in the neutralization tank 4 are alternatively supplied to the transfer flow path 6. Note that although the neutralization tank 4 is provided adjacent to the storage tank 3 in FIG. 1 , it may be located away from the storage tank 3.

[0025] (2-3) Exhaust gas supply device The flue gas supply device 5 is a device that supplies boiler flue gas 15 to blow water 14 in the neutralization tank 4. The flue gas supply device 5 has a boiler flue gas supply passage 12 and an ejector 13. The ejector 13 has a blow water supply port 27, a boiler flue gas suction port 28 to which the boiler flue gas supply passage 12 is connected, and a discharge port 29 connected to the neutralization tank 4. The ejector 13 takes in blow water 14 through the blow water supply port 27, and also sucks boiler flue gas 15 through the boiler flue gas suction port 28 and mixes it with the blow water 14. The blow water 14 mixed with the boiler flue gas 15 is discharged from the discharge port 29 of the ejector 13 and supplied to the neutralization tank 4. The boiler flue gas 15 is supplied to the ejector 13 or its supply is stopped by opening and closing a boiler flue gas supply valve 19 and an air valve 20 provided in the boiler flue gas supply passage 12.

[0026] (2-4) Transfer channel The transfer flow path 6 connects the storage tank 3 and the neutralization tank 4. The transfer flow path 6 is a flow path through which the blown water 14 in the storage tank 3 is transferred to the neutralization tank 4 in the transfer step, and is a flow path through which the blown water 14 in the neutralization tank 4 is circulated and neutralized and cooled in the neutralization and cooling step.

[0027] (2-5) Transfer pump The transfer pump 7 is provided in the transfer flow path 6. In the transfer step, the transfer pump 7 transfers the blown water 14 in the storage tank 3 to the neutralization tank 4. In the neutralization and cooling step, the transfer pump 7 circulates the blown water 14 in the neutralization tank 4.

[0028] (2-6) Inverter The inverter 9 adjusts the operating frequency of the transfer pump 7. Specifically, the inverter 9 controls the rotation speed of the motor by adjusting the frequency of the power supplied to the motor of the transfer pump 7. This changes the flow rate of the blown water 14.

[0029] (2-7) Water temperature sensor The water temperature sensor 8 is provided on the suction side of the transfer pump 7 in the transfer flow path 6. The water temperature sensor 8 detects the temperature of the blow water 14 flowing through the transfer flow path 6. The water temperature sensor 8 is specifically a thermocouple.

[0030] (2-8) Cooling device The cooling device 16 is provided in the transfer flow path 6. Specifically, the cooling device 16 is disposed downstream of the transfer pump 7. The cooling device 16 is a heat exchanger.

[0031] The cooling device 16 has a cooling water inlet 21 into which cooling water 38 flows, and a cooling water outlet 22 from which the heat-exchanged cooling water 38 is discharged. A cooling water supply passage 23 is connected to the cooling water inlet 21, and a cooling water supply valve 24 is provided in the cooling water supply passage 23. A cooling water discharge passage 25 is connected to the cooling water outlet 22, and a cooling water discharge valve 26 is provided in the cooling water discharge passage 25.

[0032] (2-9) pH sensor The pH sensor 11 is provided in the transfer flow path 6. Specifically, the pH sensor 11 is disposed upstream of the transfer pump 7. The pH sensor 11 detects the pH of the blow water 14 flowing through the transfer flow path 6.

[0033] (2-10) First water level sensor The first water level sensor 17 (water level detection means) detects the water level of the blow water 14 in the storage tank 3. The first water level sensor 17 may be an electrode-type water level sensor having multiple electrodes, or may be a pressure-type or capacitance-type sensor capable of detecting the water level in real time. (2-11) Second water level sensor The second water level sensor 18 detects the water level of the blow-down water 14 in the neutralization tank 4. The first water level sensor 17 may be an electrode-type water level sensor having multiple electrodes, or may be a pressure-type or capacitance-type sensor capable of detecting the water level in real time.

[0034] (2-12) Pressure sensor The pressure sensor 10 is provided on the discharge side of the transfer pump 7 in the transfer flow path 6, and detects the pressure of the transfer pump 7. The pressure sensor 10 is, for example, a pressure switch. A signal from the pressure sensor 10 is input to the control unit 41.

[0035] (2-13)Alarm device The alarm device 51 issues an alarm when the pressure or flow rate of the transfer pump 7 is lower than a reference value corresponding to the operating frequency. In this case, the occurrence of cavitation can be detected early. The type of alarm can be, for example, the output of text data, audio data, or image data.

[0036] (2-14) Discharge flow path and discharge valve The blow water neutralization device 1 further has a discharge flow path 42 and a second three-way valve 43. The discharge flow path 42 is a flow path for discharging the blow water 14 from the transfer flow path 6. The discharge flow path 42 is connected downstream of the transfer pump 7. The second three-way valve 43 is disposed at the connection between the transfer flow paths 6 and 42. The second three-way valve 43 is an automatic valve that can switch the supply destination of the blow water 14 flowing through the transfer flow path 6 between the cooling device 16 side and the discharge flow path 42 side. The second three-way valve 43 allows the blow water 14 from the transfer pump 7 to flow selectively to either the cooling device 16 side or the discharge flow path 42 side. (3) Control configuration The control configuration of the blow underwater neutralization device 1 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the control configuration of the blow underwater neutralization device 1. The blow underwater neutralization device 1 has a control unit 41.

[0037] The control unit 41 is a computer system having a processor (e.g., a CPU), a storage device (e.g., a ROM, a RAM, a HDD, an SSD, etc.), and various interfaces (e.g., an A / D converter, a D / A converter, a communication interface, etc.) The control unit 41 performs various control operations by executing programs stored in the storage device (corresponding to part or all of the storage area of ​​the storage device).

[0038] As shown in FIG. 2, the control unit 41 is capable of transmitting control signals to the inverter 9 and the alarm device 51. The control unit 41 can also send control signals to the transfer pump 7, the boiler exhaust gas supply valve 19, the air valve 20, the water supply valve 34, the first three-way valve 37, the second three-way valve 43, and other devices.

[0039] As shown in FIG. 2, the control unit 41 is capable of receiving detection signals from the water temperature sensor 8, the first water level sensor 17, the second water level sensor 18, and the pressure sensor 10.

[0040] (4) Process 1 to 5, several steps of the blow-underwater neutralization device 1 will be described. (4-1) Storage process The storage process will be explained using FIG. When the water supply valve 34 is opened, the blow water 14 from the steam boiler is stored in the storage tank 3 via the water supply passage 33. When the stored blow water 14 reaches a predetermined water level, the process proceeds to the transfer process.

[0041] (4-2) Transfer process The transfer process will be described with reference to FIG.

[0042] The first discharge flow path 35 and the transfer flow path 6 are connected by the first three-way valve 37, and the transfer pump 7 is driven. As a result, the blown water 14 in the storage tank 3 is transferred to the neutralization tank 4 via the transfer flow path 6.

[0043] In this way, the method of transferring blown water 14 from the storage tank 3 to the neutralization tank 4 is adopted, which simplifies the device structure, reduces the number of valves used, reduces the number of drainage pumps, reduces the number of piping components, and reduces the number of piping assembly steps.

[0044] The control unit 41 calculates a drive frequency for driving the transfer pump 7, and outputs to the inverter 9 a current value signal corresponding to the calculated value of the drive frequency.

[0045] Furthermore, while the blow water 14 is being transferred from the storage tank 3 to the neutralization tank 4 through the transfer flow path 6, the control unit 41 sets the inverter 9 to an operating frequency based on the detection result of the water temperature sensor 8 so as to prevent cavitation from occurring in the blow water 14 flowing through the transfer flow path 6. The level of the blow water 14 in the storage tank 3 drops during transfer. Even in this state, new, high-temperature blow water 14 is introduced into the storage tank 3, resulting in the transfer of high-temperature blow water 14. In this case, the dual effects of the lowered water level and the high temperature of the blow water 14 in the storage tank 3 can potentially cause cavitation. However, in this embodiment, a water temperature sensor 8 is provided on the primary side of the transfer pump 7, and an inverter 9 is provided to adjust the operating frequency of the transfer pump 7. The pump operating frequency (normally 50 Hz) is controlled in multiple stages based on the detected water temperature. When the temperature of the blow water 14 is, for example, 97°C, cavitation is likely to occur in the transfer pump 7. However, cavitation can be prevented by lowering the operating frequency of the transfer pump 7 to, for example, 30 Hz.

[0046] The control unit 41 may control the inverter 9 taking into consideration the water level of the blow water 14 in the storage tank 3, which is the detection result of the first water level sensor 17, in addition to the detection result of the water temperature sensor 8. In this case, it is possible to accurately determine the "upper limit temperature at which cavitation of the blow water 14 does not occur," which serves as a standard for comparing the operating frequency. For example, if the water level of the blow water 14 is high, the "predetermined value" will be high, and if the water level of the blow water 14 is low, the "predetermined value" will be low. For example, if the treatment capacity of the storage tank 3 is approximately 130 L, the blow water 14 can handle temperatures up to 93°C when the water level H of the blow water 14 is 1200 mm, but can only handle temperatures up to 90°C when the water level H of the blow water 14 is 500 mm.

[0047] (4-3) Neutralization / cooling process The neutralization and cooling process will be explained using FIG.

[0048] The second discharge flow path 36 and the transfer flow path 6 are connected by the first three-way valve 37, so that the blow water 14 in the neutralization tank 4 circulates through the second discharge flow path 36 and the transfer flow path 6. The blow water 14 is then cooled by the cooling device 16 and neutralized by the boiler exhaust gas 15 sucked in by the ejector 13.

[0049] In the blow water neutralization device 1, the cooling by the cooling device 16 is controlled by the control unit 41 based on the water temperature of the blow water 14 detected by the water temperature sensor 8. In addition, the neutralization by the ejector 13 is controlled by the control unit 41 based on the pH of the blow water 14 detected by the pH sensor 11.

[0050] The control unit 41 controls the alarm device 51 to issue an alarm when the detected value of the pressure sensor 10 is lower than a reference value corresponding to the operating frequency set in the inverter 9. This makes it possible to detect the occurrence of cavitation at an early stage.

[0051] The blow water neutralization device 1 is configured to detect the water pressure of the blow water 14 flowing into the ejector 13 using a pressure sensor 10. For example, if the transfer pump 7 breaks down or the transfer flow path 6 becomes clogged, the water pressure of the blow water 14 flowing into the ejector 13 drops, and sufficient negative pressure cannot be obtained at the boiler flue gas suction port 28. This reduces the amount of boiler flue gas intake, making it impossible to achieve the desired neutralization capacity. Therefore, in this configuration, when the water pressure of the blow water 14 falls below a predetermined value, the control unit 41 issues an alarm to the outside, for example, using an alarm device 51, to notify the user of the abnormality. As a result, maintenance of the transfer pump 7, the transfer flow path 6, and other components can be performed promptly, preventing a decrease in the amount of boiler flue gas 15 intake.

[0052] The cooling of the blow water 14 will now be described in detail. When the temperature of the blow water 14 detected by the water temperature sensor 8 exceeds a predetermined value defined by the discharge standard, the control unit 41 opens the cooling water supply valve 24. As a result, cooling water 38 is supplied from the cooling water inlet 21 to the outside of the internal flow path via the cooling water supply flow path 23. The blow water 14 is introduced into the internal flow path of the cooling device 16. In this state, the cooling water 38 removes heat from the blow water 14 and is discharged from the cooling water outlet 22 to the cooling water discharge flow path 25. The cooled blow water 14 is discharged from the cooling device 16 to the transfer flow path 6. On the other hand, when the temperature of the blow-off water 14 detected by the water temperature sensor 8 falls below a predetermined value defined by the drainage standard, the control unit 41 closes the cooling water supply valve 24. As a result, the supply of cooling water to the cooling device 16 is cut off, and the cooling of the blow-off water 14 is stopped.

[0053] The neutralization of the blow water 14 will now be described in detail. When the pH of the blow water 14 detected by the pH sensor 11 exceeds a predetermined value specified by the wastewater standards, the blow water 14 is neutralized by the action of the ejector 13 with the boiler flue gas 15 supplied from the boiler flue gas supply passage 12. Specifically, the control unit 41 opens the boiler flue gas supply valve 19 and closes the air valve 20. As a result, the ejector 13 takes in the blow water 14 from the blow water supply port 27 and sucks the boiler flue gas 15 supplied from the boiler flue gas supply passage 12 through the boiler flue gas suction port 28, mixing the blow water 14 with the boiler flue gas 15. This allows the blow water 14 and the boiler flue gas 15 to come into efficient contact with each other, and further agitates the blow water 14 due to the turbulence effect generated in the ejector 13, thereby dissolving the boiler flue gas 15 in the blow water 14 and neutralizing it. Then, the blown water 14 is discharged from the discharge port 29 and returned to the neutralization tank 4.

[0054] On the other hand, when the pH of the blow water 14 detected by the pH sensor 11 falls below a predetermined value set forth in the wastewater standards, the control unit 41 closes the boiler exhaust gas supply valve 19 and opens the air valve 20. As a result, outside air is drawn into the ejector 13, and the neutralization of the blow water 14 is stopped. In this way, drawing in outside air when the boiler exhaust gas 15 is not being supplied suppresses vibrations caused by pressure fluctuations that occur inside the ejector 13.

[0055] As described above, while the blown water 14 in the neutralization tank 4 circulates through the transfer flow path 6, cooling control and neutralization control are performed separately until the water temperature and pH meet the wastewater standards.

[0056] (4-4) Drainage process The drainage process will be described with reference to FIG.

[0057] When the values ​​detected by the water temperature sensor 8 and the pH sensor 11 reach the water temperature and pH values ​​that comply with the wastewater standards, respectively, the second three-way valve 43 is opened. As a result, the blown water 14 is discharged outside the system via the discharge flow path 42.

[0058] (4-5) New storage process During the neutralization and treatment process, blow water 14 can be stored in the storage tank 3. In other words, even if new blow water 14 is discharged from the steam boiler while the blow water 14 is being treated, neutralization efficiency and cooling efficiency can be maintained.

[0059] 2. Second embodiment In the first embodiment, the water level detection means was a water level sensor, but other configurations may also be used. Such an example will be described as the second embodiment using Fig. 6. Fig. 6 is a block diagram showing the control configuration of the blow-water neutralization device according to the second embodiment. The basic configuration and basic operation of the second embodiment are the same as those of the first embodiment, so the following description will focus on the differences.

[0060] The blow water neutralization device has a flow rate sensor 52. The flow rate sensor 52 is provided in the phase-shifting flow path and detects the flow rate of the blow water flowing through the transfer flow path. The control unit 41 has a water level calculation unit 53. The water level calculation unit 53 calculates the water level of the blow water 14 in the storage tank 3 based on the time elapsed since the start of transfer of the blow water 14 and the flow rate of the transfer pump 7 detected by the flow rate sensor 52. In this embodiment, the water level of the blow water 14 in the storage tank 3 can be determined without using a sensor.

[0061] 3. Other Embodiments Although several embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the invention. In particular, several embodiments and modifications described in this specification can be arbitrarily combined as necessary.

[0062] The water temperature sensor 8 may be provided on the suction side (primary side) of the transfer pump 7, and may be provided in the storage tank 3 to detect the temperature of the blown water 14 in the storage tank 3, for example.

[0063] In order to detect abnormalities such as a breakdown of the transfer pump 7 or clogging of the transfer flow path 6, a flow meter (sensor) may be used instead of the pressure sensor 10.

[0064] The control unit 41 may control the inverter 9 based only on the detection result of the water temperature sensor 8.

[0065] 4. Contributing to the United Nations-led Sustainable Development Goals (SDGs) This disclosure includes matters that contribute to achieving Goal 6 of the Sustainable Development Goals (SDGs), "Clean water and sanitation," and Goal 13, "Climate action." [Explanation of symbols]

[0066] 1: Blow underwater neutralization device 3: Reservoir 4: Neutralization tank 5: Exhaust gas supply device 6: Transfer channel 7: Transfer pump 8: Water temperature sensor 9: Inverter 10: Pressure sensor (sensor) 11: pH sensor 14: Blow water 15: Boiler exhaust gas 17: First water level sensor 31: Water temperature sensor 51:Alarm device 52:Water level calculation part

Claims

1. 1. An apparatus for neutralizing blow water using exhaust gas from a boiler, comprising: a storage tank in which the blow water is stored; a neutralization tank used to neutralize the blow water; an exhaust gas supply device for supplying the exhaust gas to the blow water in the neutralization tank; a transfer flow path connecting the storage tank and the neutralization tank; a transfer pump provided in the transfer flow path to transfer the blown water from the storage tank to the neutralization tank; a water temperature sensor provided on the suction side of the transfer pump in the transfer flow path; an inverter for adjusting the operation frequency of the transfer pump; a control unit that sets, on the basis of a detection result of the water temperature sensor, an operating frequency of the inverter such that cavitation does not occur in the blown water flowing through the transfer flow path while the blown water is being transferred from the storage tank to the neutralization tank through the transfer flow path; Equipped with Blow underwater neutralization device.

2. further comprising a water level detection means for detecting the water level of the blow water in the storage tank; 2. The blow-underwater neutralization device according to claim 1, wherein the control unit controls the inverter based on the detection results of the water temperature sensor and the detection results of the water level detection means.

3. 3. The blow water neutralization device according to claim 2, wherein the water level detection means includes a water level sensor that detects the water level of the blow water in the reservoir tank.

4. 3. The blow water neutralization device according to claim 2, wherein the water level detection means includes a water level calculation unit that calculates the water level of the blow water in the storage tank based on the elapsed time from the start of transfer of the blow water and the flow rate of the transfer pump.

5. a sensor provided on a discharge side of the transfer pump in the transfer flow path to detect a pressure or a flow rate of the transfer pump; The blow-underwater neutralization device according to any one of claims 1 to 4, further comprising an alarm means for issuing an alarm when the pressure or flow rate of the transfer pump is lower than a reference value corresponding to the operating frequency.

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