Vacuum station and vacuum pump sealing water treatment method

Abstract

To provide a vacuum station that can suppress deterioration of sealed water in a vacuum pump.SOLUTION: A vacuum station comprises: a tank that stores a liquid entrained with gas; a water-sealing type vacuum pump that sucks the gas from the tank; a sealed water tank that separates sealed water used in the vacuum pump and the gas discharged from the vacuum pump and stores the separated sealed water; a sealed water pump that supplies the sealed water from the sealed water tank to the vacuum pump; a fresh water supply device that supplies fresh water (tap water) neutralizing solution to the sealed water tank; a measuring device that measures pH of the sealed water stored in the sealed water tank; and a control unit. The control unit controls supply / stop of the fresh water (tap water) from the fresh water supply device based on a measured value of pH of the sealed water.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vacuum station in a vacuum sewer system.

Background Art

[0002] A vacuum sewer system is a system that collects liquids including domestic wastewater generated in households (hereinafter referred to as "sewage") to a vacuum station via a vacuum valve unit and a vacuum sewer pipe. The vacuum station includes a water-sealed vacuum pump that generates a vacuum serving as the driving force for collecting sewage, a water collection tank that temporarily stores the collected sewage, etc., and conveys the sewage stored in the water collection tank to a sewage treatment plant or the like.

[0003] The vacuum pump creates a negative pressure in the water collection tank by sucking the gas (hereinafter referred to as "exhaust gas") that conveys the sewage together from the water collection tank. Further, the exhaust gas sucked by the vacuum pump is transferred together with the circulating water (sealing water) to a separator-cum-sealing water tank (hereinafter referred to as "sealing water tank") arranged on the downstream side, and the exhaust gas and the sealing water are separated into gas and liquid. The sealing water is circulated between the vacuum pump and the sealing water tank by a sealing water pump arranged between the vacuum pump and the sealing water tank.

[0004] In the vacuum station described in Patent Document 1, an invention is disclosed in which an odor component removing device is provided on the upstream side of the vacuum pump to remove the odor components (including corrosive components) contained in the sewage, thereby suppressing the deterioration of the sealing water of the vacuum pump and the corrosion of the pump body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, the water seal tank installed in the vacuum station has the functions of a gas-liquid separation tank, a water seal storage tank, and a water seal cooling function. The water seal separated in the water seal tank is circulated and supplied to the vacuum pump by the water seal pump. However, if the water seal is continuously circulated and supplied, it will be mixed with air that comes into contact with the wastewater discharged from the vacuum pump, causing the water seal to become acidic and the water quality to deteriorate. If water seal with deteriorated quality is supplied to the vacuum pump, the vacuum pump may corrode, potentially shortening its lifespan.

[0007] Traditionally, to improve the quality of the water seal, maintenance was performed periodically by opening the drain valve of the water seal tank, draining the water seal, and supplying tap water to replace a portion of it. However, since the quality and concentration of the water seal in the tank were not monitored, it was unclear how effective this partial replacement of the water seal was. Furthermore, the need to replace the water seal periodically for maintenance was not only time-consuming but also resulted in increased water usage. [Means for solving the problem]

[0008] The vacuum station of the present invention has been made in view of the above problems and has a configuration comprising: a tank for storing a liquid transported together with a gas; a water-sealed vacuum pump for sucking the gas from the tank; a seal water tank for separating the seal water used in the vacuum pump from the gas discharged from the vacuum pump and for storing the separated seal water; a seal water pump for supplying seal water from the seal water tank to the vacuum pump; a neutralizing liquid supply device for supplying neutralizing liquid to the seal water tank; a measuring instrument for measuring the characteristic value of the seal water stored in the seal water tank; and a control unit for controlling the supply / stop of neutralizing liquid from the neutralizing liquid supply device based on the characteristic value of the seal water.

[0009] The vacuum station is equipped with a flow control valve positioned between the neutralizing liquid supply device and the water seal tank, and the control unit is configured to adjust the amount of neutralizing liquid supplied from the neutralizing liquid supply device based on characteristic values.

[0010] The measuring instrument is preferably placed inside the water seal tank or in the piping between the water seal tank and the vacuum pump. Furthermore, the characteristic value is preferably pH or hydrogen sulfide concentration, and the neutralizing solution is preferably tap water.

[0011] It is preferable that the tanks, vacuum pumps, sealing water tanks, and neutralizing liquid supply equipment that make up the vacuum station be housed together within a building. [Effects of the Invention]

[0012] According to the present invention, the characteristic values ​​of the sealing water stored in the sealing water tank are measured, and the supply / stop of the neutralizing liquid from the neutralizing liquid supply device is controlled based on these characteristic values. This effectively suppresses the deterioration of the sealing water, thereby suppressing corrosion of the vacuum pump and deterioration of the paint on the inside of the pump, and thus extending the lifespan of the vacuum pump. Furthermore, by reducing the number of times the sealing water stored in the sealing water tank is replaced, the amount of water used at the vacuum station can be reduced. [Brief explanation of the drawing]

[0013] [Figure 1] This diagram shows the overall configuration of the vacuum station. [Figure 2] This figure shows an example of controlling a water-sealed vacuum pump based on the pressure in the water collection tank. [Figure 3] This figure shows an example of controlling a water-sealed vacuum pump and a pressure pump based on the water level in a water collection tank. [Figure 4] This figure shows an example of the control of a cooling device, a cooling water pump, and a water seal tank drain valve based on the water temperature of the water seal tank. [Figure 5] This figure shows an example of controlling the water seal tank drain valve based on the pH of the water seal tank. [Figure 6] This figure shows an example of the control of a cooling water pump, a water seal tank drain valve, and a water seal pump based on the water level in the water seal tank. [Figure 7] This figure shows an example of controlling a drain pump and a seal tank drain valve based on the water level in a drain pit. [Modes for carrying out the invention]

[0014] A vacuum station according to one embodiment of the present invention will be described below with reference to the drawings. In the following embodiments, a vacuum station will be used as an example, but the present invention is not limited thereto, and can also be applied to facilities that circulate and transport liquid stored in a water-sealing tank using a water-sealed vacuum pump, for example.

[0015] Figure 1 shows the overall configuration of the vacuum station. In this embodiment, a simple configuration with one water-sealed vacuum pump and one pressure pump is used as an example, but multiple units may be provided.

[0016] In Figure 1, the vacuum station 10 includes a water collection tank 11, a pressure pump 12, a water-sealed vacuum pump (vacuum pump) 13, a separator / water sealing tank (water sealing tank) 14, a water sealing pump 15, an exhaust silencer 16, a mist separator 17, a cooling water pump 18, a cooling device 19, a drainage pit 20, a control unit 21, and an alarm 22. The vacuum station 10 is a standalone type in which each device, such as the water collection tank 11, the vacuum pump 13, and the water sealing tank 14, is housed in an independent building. However, the present invention is not limited to standalone types and can also be applied to vacuum stations such as road-buried types in which the water collection tank is buried underground, such as in a manhole, and the vacuum pump is installed above ground.

[0017] The water collection tank 11 is a container that collects sewage such as domestic wastewater temporarily stored in a vacuum valve unit, etc., and the exhaust gas that is transported along with this sewage. The water collection tank 11 stores the sewage that has been transported along with the exhaust gas. One end of the sewage inlet pipe 31, which transports sewage and exhaust gas temporarily stored in a private manhole, etc., along with the sewage via a vacuum pipeline, is connected to the top of the water collection tank 11.

[0018] The water collection tank 11 is provided with a sewage level measuring device 32 and a pressure measuring device 33. The sewage level measuring device 32 is a measuring device that measures the level of sewage stored in the water collection tank 11, and can be, for example, an electrode type water level gauge. Information on the level of sewage detected by the sewage level measuring device 32 is output to the control unit 21. The pressure measuring device 33 is a measuring device that measures the pressure (the pressure on the suction side of the vacuum pump 13) in the water collection tank 11. Information on the pressure detected by the pressure measuring device 33 is output to the control unit 21.

[0019] The pressure pump 12 is a pump that pumps the sewage stored in the water collection tank 11 to the sewer main or the sewage treatment plant through a pressure pipe 34 provided with a check valve 35. The check valve 35 is a valve that allows sewage to flow only in the direction from the water collection tank 11 to the sewer main or the sewage treatment plant. The drain discharged from the pressure pump 12 is conveyed to the drainage pit 20 through a drainage groove.

[0020] An exhaust pipe 36 for sending exhaust gas to an exhaust tower is connected to the water collection tank 11 from its ceiling through a vacuum pump 13, a water seal tank 14, etc. The exhaust pipe 36 constitutes a conveyance path for conveying exhaust gas from the water collection tank 11 to the vacuum pump 13.

[0021] The vacuum pump 13 is, for example, composed of a cylindrical casing and an impeller, and the impeller is attached at a position eccentric to the casing. The water seal pump 15 is connected to the water seal tank 14 and the vacuum pump 13 through a water seal pipe 37, supplies the water seal stored in the water seal tank 14 to the vacuum pump 13, and thereby water seal enters the casing of the vacuum pump 13. As a result, the impeller of the vacuum pump 13 rotates, and the heavy water seal becomes a concentric ring shape along the inner wall of the casing by centrifugal force. The volume of the space surrounded by the inner wall of this water seal ring and the blades of the impeller is changed, and the suction, compression, and exhaust actions are continuously performed through the suction / exhaust ports provided on the side wall or the inner wall of the impeller.

[0022] As a result, the vacuum pump 13 draws exhaust gas from the gas phase inside the water collection tank 11, creating negative pressure inside the water collection tank 11. Consequently, the sewage stored in the private manhole, etc., is transported along with the exhaust gas through the sewage inlet pipe 31 and stored in the water collection tank 11. The vacuum pump 13 discharges sealing water along with the exhaust gas from the water collection tank 11. The exhaust gas and sealing water discharged from the water-sealed vacuum pump 13 are mixed in the exhaust pipe 36 and transported to the sealing water tank 14. The drain water discharged from the vacuum pump 13 is transported to the drain pit 20 via the drain channel.

[0023] A check valve 38 is provided in the exhaust pipe 36 upstream of the vacuum pump 13, which ensures that exhaust is transported only in the direction that the vacuum pump 13 draws exhaust from the water collection tank 11. In addition, maintenance valves can be provided in the exhaust pipes 36 on both the upstream and downstream sides of the vacuum pump, as well as in the water sealing pipe 37 that transports water sealing from the water sealing tank 14 to the vacuum pump 13.

[0024] The sealing water tank 14 is a container that separates the exhaust gas and sealing water discharged from the vacuum pump 13 and stores the separated sealing water. The exhaust gas and sealing water discharged from the vacuum pump 13 are separated by the sealing water tank 14, and the exhaust gas from which the sealing water has been separated is transported to the exhaust tower via the exhaust silencer 16 and mist separator 17.

[0025] The water seal tank 14 is equipped with a water seal level meter 41, a water seal temperature meter 42, and a water seal pH meter 43. The water seal level meter 41 is, for example, an electrode-type water level meter that measures the water level of the water seal in the water seal tank 14 and outputs the water level information to the control unit 21. The water seal temperature meter 42 is a meter that measures the temperature of the water seal stored in the water seal tank 42, and the detected water temperature value is output to the control unit 21.

[0026] The seal water pH meter 43 is a measuring instrument that measures the pH (characteristic value) of the seal water stored in the seal water tank 14, for example, by measuring the potential difference between a glass electrode and a reference electrode. The measured pH information of the seal water is output to the control unit 21.

[0027] A drain pipe 44 is connected to the water seal tank 14 to drain the water seal stored inside to the drain pit 20. The drain pipe 44 is equipped with a water seal tank drain valve 45, which is a valve that opens and closes the drain pipe 44 and opens when draining the water seal stored in the water seal tank 14 to the drain pit 20.

[0028] A clean water pipe 46 is connected to the water seal tank 14, and a clean water pipe valve 47 is provided on the clean water pipe 46. The clean water pipe valve 47 is a valve that opens and closes the clean water pipe 46, and it opens when clean water (tap water) as a neutralizing solution is injected into the water seal tank 14.

[0029] A cooling pipe 48 is connected to the water seal tank 14, which circulates the water seal stored inside via a cooling pump 18 and a cooling device 19. The water seal pump 18 transports the water seal stored in the water seal tank 14 to the cooling device 19 and also supplies the water seal cooled by the cooling device 19 back to the water seal tank 14. The cooling device 19 is composed of, for example, a cooling tower, which cools the water seal transported by the water seal pump 18. The wastewater discharged from the cooling device 19 is transported to the drain pit 20 via a drain channel.

[0030] The drainage pit 20 is a container for storing wastewater generated at the vacuum station 10, and stores wastewater generated by the pressure pump 12, vacuum pump 13, seal water tank 14, cooling device 19, etc. The drainage pit 20 is equipped with a drainage water level measuring instrument 50. The drainage water level measuring instrument 50 is, for example, an electrode-type water level meter, and measures the water level of the wastewater stored in the drainage pit 20. The information on the water level of the wastewater detected by the drainage water level measuring instrument 50 is output to the control unit 20. The drainage pit 20 is also equipped with a drainage pipe and a drainage pump (not shown), and when the water level in the drainage pit 20 reaches a certain value, the wastewater is released to the outside.

[0031] The control unit 21 is, for example, a general-purpose computer device, and has a control program installed that comprehensively controls the operation of each device constituting the vacuum station 10. The control unit 21 receives information such as the water level in the water collection tank 11 measured by the sewage water level meter 32, the pressure inside the water collection tank 11 measured by the pressure meter 33, the water level inside the water seal tank 14 measured by the water seal water level meter 41, the water temperature and pH inside the water seal tank measured by the water seal water temperature meter 42 and the water seal water pH meter 43, and the water level in the drainage pit 20 measured by the drainage water level meter 50. Based on these input values, the control unit controls the operation of the pressure pump 12, vacuum pump 13, water seal tank drain valve 45, water seal pump 15, cooling water pump 18, cooling device 19, and various valves.

[0032] Furthermore, an alarm device 22 is connected to the control unit 21, and when predetermined conditions (water level, temperature, pH, etc.) are met with respect to the water collection tank 11, the water seal tank 14, and the drainage pit 20, the alarm device 22 is activated to generate an alarm.

[0033] The following describes a specific control example of the control unit 21. Figure 2 is a diagram showing an example of controlling the operation of the vacuum pump 12 based on the detected pressure value on the suction side of the vacuum pump 13. As shown in Figure 2, the control unit 21 stops the operation (rotation) of the vacuum pump 13 when the pressure value measured by the pressure measuring instrument 33 falls below a first threshold (for example, -70kPa). The control unit 21 also starts operating the vacuum pump 13 when the pressure value measured by the pressure measuring instrument 33 rises above a second threshold (for example, -65kPa) which is set higher than the first threshold.

[0034] When the pressure value measured by the pressure gauge 33 exceeds a third threshold (e.g., -50kPa) which is set higher than the second threshold, the control unit 21 activates the alarm 22 to issue an alarm indicating a decrease in vacuum and starts the vacuum pump 13. On the other hand, if the pressure value measured by the pressure gauge 33 is higher than the second threshold and lower than a fourth threshold (e.g., -60kPa) which is lower than the third threshold while the alarm indicating a decrease in vacuum is being issued, the control unit 22 resets the alarm. Through this control, the water collection tank 12 is controlled to an appropriate negative pressure.

[0035] Figure 3 shows an example of controlling the operation of the vacuum pump 13 and the pressure pump 12 based on the detected sewage water level in the collection tank 11. When the water level measured by the sewage water level meter 32 falls below a first threshold (LLWL), the control unit 21 issues an alarm indicating that the sewage water level has dropped and stops the operation of the pressure pump 11. Furthermore, when the alarm indicating that the sewage water level has dropped is issued, and the water level measured by the sewage water level meter 32 rises above a second threshold (LWL) which is set higher than the first threshold, the control unit 21 resets the alarm.

[0036] The control unit 21 operates the pressure pump 11 when the water level measured by the sewage water level meter 32 rises above a third threshold (HWL) which is set higher than the second threshold. On the other hand, the control unit 21 stops operating the pressure pump 11 when the water level measured by the sewage water level meter 32 falls below the second threshold (LWL).

[0037] The control unit 21 issues an alarm indicating that the sewer water level has risen and operates the pressure pump 11 (or it may operate a backup pressure pump) when the water level measured by the sewer water level meter 32 rises above a fourth threshold (HHWL) which is set higher than the third threshold. The control unit 21 resets the alarm when the water level measured by the sewer water level meter 32 falls below the third threshold (HWL) while the alarm indicating that the sewer water level has risen is being issued.

[0038] When the water level measured by the sewage level gauge 32 rises above a fifth threshold (VHWL) which is set higher than the fourth threshold, the control unit 21 issues an alarm indicating that the sewage level has risen further and stops the operation of the vacuum pump 13. On the other hand, when the water level measured by the sewage level gauge 32 falls below the fourth threshold (HHWL) while the alarm indicating that the sewage level has risen further has been issued, the control unit 21 resets the alarm and resumes the operation of the vacuum pump 13. Through this control, the sewage stored in the collection tank 11 is properly pumped.

[0039] Figure 4 shows an example of controlling the operation / stop of the cooling device 19, the operation / stop of the cooling water pump 18, and the opening / closing of the seal water tank drain valve 45 based on the detected water temperature of the seal water in the seal water tank 14. The control unit 21 issues an alarm indicating that the seal water temperature has risen when the water temperature measured by the seal water temperature measuring instrument 42 rises above a first threshold (VH). On the other hand, if the alarm indicating that the seal water temperature has risen has been issued, the control unit 21 resets the alarm when the water temperature measured by the seal water temperature measuring instrument 42 falls below a second threshold (HH) which is set lower than the first threshold (VH).

[0040] The control unit 21 opens the water seal tank drain valve 45 when the water temperature measured by the water seal temperature sensor 42 exceeds a second threshold (VH). On the other hand, the control unit 21 closes the water seal tank drain valve 45 when the water temperature measured by the water seal temperature sensor 42 falls below a third threshold (H), which is set lower than the second threshold.

[0041] The control unit 21 operates the cooling device 19 and the cooling water pump 18 when the water temperature measured by the seal water temperature sensor 42 rises above a third threshold (H). On the other hand, the control unit 21 stops the operation of the cooling device 19 and the cooling water pump 81 when the water temperature measured by the seal water temperature sensor 42 falls below a fourth threshold (L), which is set lower than the third threshold (H). Through this control, the seal water in the seal water tank 14 is controlled to an appropriate temperature.

[0042] Figure 5 shows an example of controlling the opening / closing of the clean water valve 47 based on the detected pH value of the water seal in the water seal tank 14. In Figure 5, the control unit 21 issues an alarm indicating that the pH of the water seal has decreased (the acidity of the water seal has increased) when the pH value measured by the water seal pH meter 43 falls below a first threshold (LL). The control unit 21 also stops the alarm when the pH value measured by the water seal pH meter 43 rises above a second threshold (L), which is set higher than the first threshold (LL).

[0043] Furthermore, the control unit 21 controls the fresh water valve 47 to open when the pH value measured by the seal water pH meter 43 falls below a second threshold (L). As a result, fresh water (tap water) flows into the seal water tank 14 via the fresh water pipe 46, and the pH inside the seal water tank increases. The control unit controls the fresh water valve 47 to close when the measured pH value rises above a third threshold (H), which is set higher than the second threshold (L). As a result, the supply of fresh water (tap water) to the seal water tank 14 is stopped, and the increase in the pH of the seal water is suppressed.

[0044] The water seal in the water seal tank 14 is circulated and diffused with the exhaust gas sucked in by the vacuum pump 13, causing it to become acidic and degrade in water quality. When this degraded water seal is supplied to the vacuum pump 13, it can corrode the components inside the vacuum pump 13 or cause the paint to deteriorate. In this embodiment of the vacuum station, the supply of clean water (tap water) can be controlled according to the measured pH of the water seal in the water seal tank 14, preventing the pH of the water seal from dropping excessively. This suppresses corrosion of the vacuum pump 13. Furthermore, by reducing the frequency of water seal replacement maintenance, the amount of water used in the vacuum station can be reduced.

[0045] In this embodiment, the pH thresholds can be set as follows: the first threshold (LL) is 5.7, the second threshold (L) is 5.8, and the third threshold (H) is 5.9. However, these thresholds can be changed as appropriate.

[0046] Figure 6 shows an example of controlling the operation / stopping of the cooling water pump 18, the opening / closing of the water seal tank drain valve 45, and the operation / stopping of the water seal pump 15 based on the detected water level of the water seal in the water seal tank 14.

[0047] In Figure 6, the control unit 21 issues an alarm indicating that the water level of the seal water has risen when the water level measured by the seal water level meter 41 rises above the first threshold (HWL). On the other hand, the control unit 21 issues an alarm indicating that the water level of the seal water has fallen below the second threshold (LWL), which is set lower than the first threshold (HWL), when the water level measured by the seal water level meter 41 falls below the second threshold (LWL), which is set lower than the first threshold (HWL). At the same time, it stops the operation of the seal water pump 15 and the cooling water pump 18, and also closes the seal water tank drain valve 45. Through this control, the water level of the seal water in the seal water tank 14 is controlled to an appropriate level.

[0048] Figure 7 shows an example of controlling the opening / closing of the water seal tank drain valve 45 based on the detected water level of the drainage in the drainage pit 20. When the water level measured by the drainage water level meter 50 rises above a first threshold (HHWL), the control unit 21 issues an alarm indicating that the drainage water level has risen and closes the water seal tank drain valve 45. On the other hand, when the alarm indicating that the drainage water level has risen has been issued, the control unit 21 resets the alarm when the water level measured by the drainage water level meter 50 falls below a second threshold (HWL) which is set lower than the first threshold (HHWL).

[0049] Furthermore, when the water level measured by the drain water level gauge 50 rises above the second threshold (HWL), the control unit 21 drives the drain pump installed in the drain pit 20 to remove the wastewater in the drain pit 20. Also, when the water level measured by the drain water level gauge 50 falls below the third threshold (LWL), which is lower than the second threshold (HWL), the control unit 21 stops the drain pump. Through this control, the wastewater in the drain pit 20 is controlled to an appropriate level.

[0050] In the vacuum station according to this embodiment, the supply of clean water (tap water) to the water seal tank is controlled according to the pH measurement value, but the present invention is not limited to this and may be combined with the opening and closing control of the water seal tank drain valve 45.

[0051] Alternatively, a flow rate change valve may be installed in the clean water pipe 46 that supplies clean water (tap water), and the amount of clean water (tap water) supplied to the water seal tank 14 may be controlled in stages according to the pH measurement. This makes it possible to increase the supply of clean water (tap water) when the pH measurement is excessively low, and decrease the supply of clean water (tap water) when the pH is slightly low.

[0052] In this embodiment, the vacuum station measures the pH of the seal water in the seal water tank 14, but the present invention is not limited to this, and may be configured to measure the pH of the seal water in other locations (for example, the seal water pipe 37 connecting the seal water pump 15 and the seal water tank 14).

[0053] In the vacuum station according to this embodiment, the characteristic value of the sealing water is the measured pH value in the sealing water tank 14, but the present invention is not limited to this, and for example, the water supply may be controlled according to the measured value of the hydrogen sulfide concentration in the sealing water tank.

[0054] The embodiments described above are intended to enable persons with ordinary skill in the art to implement the present invention. Various modifications of the above embodiments can be made naturally by those skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments as well. The present invention is not limited to the embodiments described and should be interpreted in the broadest sense according to the technical idea defined by the claims. [Explanation of Symbols]

[0055] 10 Vacuum Station 11 water collection tanks 12 Pressure pump 13. Water-sealed vacuum pump 14 Separator and water seal tank 15. Water sealing pump 20 Drainage pit 21 Control Unit 22 Alarm 43. Water seal pH meter 45. Water seal tank discharge valve 47 Clean water pipe valve

Claims

1. A tank for storing the liquid transported along with the gas, A water-sealed vacuum pump for drawing the gas from the tank, A sealing water tank separates the sealing water used in the vacuum pump from the gas discharged from the vacuum pump, and stores the separated sealing water. A sealing water pump that supplies sealing water from the sealing water tank to the vacuum pump, A neutralizing liquid supply device that supplies a neutralizing liquid to the aforementioned water seal tank, A measuring instrument for measuring the characteristic values ​​of the seal water stored in the seal water tank, A control unit controls the supply / stopping of the neutralizing liquid from the neutralizing liquid supply device based on the characteristic values ​​of the sealing water, Equipped with, The aforementioned characteristic value is pH or hydrogen sulfide concentration. The control unit issues an alarm when the characteristic value falls below a first threshold, and stops the alarm when the characteristic value rises above a second threshold that is higher than the first threshold, in this vacuum station.

2. The vacuum station according to claim 1, wherein the control unit starts supplying neutralizing liquid from the neutralizing liquid supply device when the characteristic value falls below a second threshold, and stops supplying neutralizing liquid when the characteristic value becomes higher than a third threshold which is higher than the second threshold.

3. A tank for storing a liquid transported together with a gas, A water-sealed vacuum pump for drawing the gas from the tank, A sealing water tank separates the sealing water used in the vacuum pump from the gas discharged from the vacuum pump, and stores the separated sealing water. A sealing water pump that supplies sealing water from the sealing water tank to the vacuum pump, A neutralizing liquid supply device that supplies a neutralizing liquid to the aforementioned water seal tank, A measuring instrument for measuring the characteristic values ​​of the seal water stored in the seal water tank, A control unit controls the supply / stopping of the neutralizing liquid from the neutralizing liquid supply device based on the characteristic values ​​of the sealing water, Equipped with, The aforementioned characteristic value is pH or hydrogen sulfide concentration. The control unit starts supplying neutralizing liquid from the neutralizing liquid supply device when the characteristic value falls below a first threshold, and stops supplying neutralizing liquid when the characteristic value becomes higher than a second threshold which is higher than the first threshold, in a vacuum station.

4. The device includes a flow control valve positioned between the neutralizing liquid supply device and the water seal tank, The vacuum station according to claim 1, characterized in that the control unit adjusts the amount of neutralizing liquid supplied from the neutralizing liquid supply device based on the characteristic value.

5. The vacuum station according to claim 1, characterized in that the measuring instrument is arranged inside the water seal tank.

6. The vacuum station according to claim 1, characterized in that the measuring instrument is placed in the piping between the water seal tank and the vacuum pump.

7. The vacuum station according to claim 1, characterized in that the neutralizing solution is tap water.

8. The vacuum station according to claim 1, characterized in that the tank, the vacuum pump, the sealing water tank, and the neutralizing liquid supply device are all housed together in a building.

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