WO2006028031A1

WO2006028031A1 - Liquid discharging device and liquid discharging method

Info

Publication number: WO2006028031A1
Application number: PCT/JP2005/016222
Authority: WO
Inventors: Iwao Ando
Original assignee: Ucan Co., Ltd.
Priority date: 2004-09-07
Filing date: 2005-09-05
Publication date: 2006-03-16
Also published as: JPWO2006028031A1; JP4552054B2; CN100510553C; CN101014806A

Abstract

A liquid discharging device and a liquid discharging method, wherein liquid discharge control valves (13, 14) of a second tank (2) are brought into a closed state, a main valve (4) between a first tank (1) and the second tank (2) is brought into an open state, and a pressure in the second tank (2) is reduced by a pressure reducing means (8) to suckingly recover a liquid in a liquid storage tank (21) to the second tank (2) through a liquid suction pipe (22) and the first tank (1). When the liquid discharge control valves (13, 14) are opened after the main valve (4) is closed, the liquid is discharged from the second tank (2) while the first tank (1) is held in a depressurized state. Then, the liquid discharge control valves (13, 14) are closed, and after the second tank (2) is depressurized by the pressure reducing means (8), the main valve (4) is opened.

Description

Specification

Drainage device and drainage method

Technical field

[0001] The present invention relates to a drainage device and a drainage method, and is suitable for use in, for example, continuously collecting and discharging drain generated by the operation of an air conditioner such as for building air conditioning. The present invention relates to a drainage device and a drainage method.

Background art

[0002] As a drain drainage device that continuously collects and discharges drains generated by the operation of air conditioners such as for building air conditioning, the drainage that has been discharged from the air conditioner is always collected by suction while maintaining a predetermined degree of vacuum. A first tank; a second tank to which drain is supplied from the first tank; a first valve that controls the supply of drain to the second tank; and the main valve There has been proposed a drainage drainage device comprising a drainage control valve that opens and drains the drainage in the second tank when in the closed state (see Patent Documents 1 and 2).

[0003] According to the drain drainage device, since the first tank always maintains a predetermined degree of vacuum, the drain from which air-conditioner power has also been discharged is continuously sucked and collected in the first tank. Is done. The main valve is normally open, and the drain collected in the first tank is transferred to the second tank whose pressure is reduced as the pressure of the first tank is reduced. Supplied with. When a predetermined amount of drain accumulates in the second tank, the main valve is closed and communication between the inside of the first tank and the inside of the second tank is cut off. Thereafter, the drainage control valve is opened, and the drain in the second tank is discharged. The drain suction I action by the first tank continues while the main nozzle is closed.

[0004] When drainage of the second tank force is completed, the drainage control valve is closed, and then the main valve is opened, so that the interiors of the first and second tanks communicate with each other. The first tank force The supply of drain to the second tank is resumed.

[0005] According to the drain drainage device, the drain generated by the operation of the air conditioner is continuously generated. Therefore, there is an advantage that the drain can be collected safely and reliably with any air conditioner installed at any location.

[0006] By the way, it is not always possible to secure a large installation location of the drainage device.

Due to the installation space and cost, there is a great demand to make the drain drainage device as compact as possible. In some cases, it is only necessary to suck and collect the drainage of only the air conditioners on one floor that are not in all the air conditioners in the entire building. In this case, a small drainage device that does not have a strong suction force is sufficient.

[0007] When considering downsizing the drainage device, the volume of the first tank becomes a bottleneck. That is, in the conventional configuration, after the drain of the second tank force is discharged, the main valve is opened, so that the first tank and the second tank are once again communicated with each other. Inevitably, however, the vacuum degree (decompression degree) of the first tank is inevitably lowered. If the degree of decrease is excessive, it is expected that a phenomenon called so-called reaction will occur in which the drain during suction collection flows back to the air conditioner. Therefore, conventionally, in order to minimize the decrease in the degree of vacuum of the first tank when the communication between the tanks is resumed, the volume of the first tank is made sufficiently large with respect to the second tank. There was a need. Specifically, in order to surely prevent the reaction, for example, the volume of the first tank is increased by more than ten times the volume of the second tank. This was a limitation of downsizing the drain drainage device. Patent Document 1: Real Fairness 7-52496

Patent Document 2: Utility Model Registration No. 2578332

Disclosure of the invention

[0008] The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a drainage device that is advantageous in terms of cost and that can be miniaturized as much as possible without impairing performance.

The present invention is also intended to provide a drainage method using the drainage device.

[0010] In order to solve the above problems, a drainage device according to the present invention includes a sealed first tank connected to a liquid storage tank via a liquid suction pipe, and a main valve that can be opened and closed. A sealed second tank connected to the first tank, a pressure reducing means connected to the second tank, and a drainage control valve for discharging the liquid in the second tank. It is provided. [0011] The drainage device can be used as follows. When the drainage control valve is closed and the main valve is open, the pressure in the second tank is reduced by the pressure reducing means, so that the liquid in the liquid storage tank becomes the liquid suction pipe and the first tank. The second tank is sucked and collected through this tank. When a predetermined amount of liquid has accumulated in the second tank, the drain valve is opened after closing the main valve, and the liquid is also discharged by the second tank force. Even after the main valve is closed, the first tank is in a reduced pressure state, so that the liquid suction action by the liquid suction pipe continues, and the sucked liquid is collected in the first tank. The Thereafter, the drainage control valve is closed, and after the second tank is depressurized by the depressurizing means, the main valve is opened. As a result, the liquid in the first tank flows into the second tank, and the liquid suction action by the second tank is resumed. By continuing the above operation, the liquid in the liquid storage tank is continuously sucked and collected and discharged.

[0012] According to the drainage device, since the main valve is opened and the communication with the first tank is resumed after the second tank returns to the reduced pressure state, it is different from the conventional one. Thus, when the main valve is opened, the degree of decompression of the first tank does not decrease. Therefore, even if the volume of the first tank is less than the volume of the second tank, the liquid absorption action by the liquid absorption pipe does not decrease, the liquid in the liquid storage tank is surely and continuously supplied. It can be collected by suction and discharged. Therefore, the drainage device has good liquid absorption performance, can be miniaturized as much as possible, and is advantageous in terms of cost.

[0013] In principle, the drainage device can be manually operated, but is usually automatically controlled so that it can be operated unattended. That is, as a preferred embodiment, a control device that automatically controls the operation of the drainage device may be provided. In this case, after the main valve is closed by the control device, the drainage control valve is opened, the second tank force liquid is discharged, and the drainage control valve is closed. After the operation and the second tank is depressurized by the depressurizing means, the main valve is opened.

[0014] As a preferred embodiment, after the second tank is depressurized to a predetermined depressurization value by the depressurization means, the control device performs a depressurization action during the opening operation of the main valve. The pressure reducing action by the pressure reducing means can be stopped when the main valve is fully opened and the second tank reaches a predetermined pressure reducing value. In this way, communication with the first tank is started by starting the opening operation of the main valve, and even if this causes a decrease in the reduced pressure value of the second tank, this is a predetermined pressure reduction. Since the pressure reducing action by the pressure reducing means continues until it returns to the value, it is possible to suppress frequent resumption of the pressure reducing action of the pressure reducing means, and it is preferable that the quiet and smooth operation of the apparatus is guaranteed. .

As a preferred embodiment, after the second tank is depressurized to a predetermined depressurization value by the depressurizing means, the depressurization action by the depressurizing means is stopped by opening the main valve. There may be provided delay means for delaying by a predetermined time that can compensate for the decrease in the reduced pressure value of the second tank. In this way, even if the reduced pressure value of the second tank drops below the predetermined reduced pressure value due to communication with the first tank, the frequent pressure reducing action of the pressure reducing means is resumed. It is preferable that the operation of the apparatus can be suppressed and that a quiet and smooth operation of the apparatus is guaranteed.

[0016] The drainage method according to the present invention includes a sealed first tank connected to a liquid storage tank via a liquid suction pipe and a first tank connected to the first tank via an openable / closable main valve. A sealed second tank, a pressure reducing means connected to the second tank, and a drainage control valve for discharging the liquid in the second tank, the drainage control valve being When the second tank is depressurized by the depressurization means in the closed state and the main valve is open, the liquid in the liquid storage tank is removed through the liquid suction pipe and the first tank. The suction is collected in the second tank, the main valve is closed, and then the drainage control valve is opened to discharge the liquid from the second tank, and then the drainage control valve is closed to reduce the pressure reduction. After the second tank is depressurized by means, It is characterized in the Hirakuko the Nbarubu.

Brief Description of Drawings

FIG. 1 is a block diagram of a drainage device according to an embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The This embodiment is an example in which the present invention is applied as a drainage drainage device for collecting drainage generated from a plurality of air conditioners installed in an office building or the like in one place and discharging it to the outside. .

FIG. 1 is a block diagram of a drain drainage device 100 according to an embodiment of the present invention, which is connected to a suction collection main body A through a suction collection main body A and a drain collection main pipe 3. A number of terminal units B.

[0020] The suction recovery main body A is installed at a position lower than the air conditioner 20 (terminal unit B) as a liquid source, such as an underground machine room or a pipe shaft of a building such as an office building. The main body A includes a first tank 1 that is a sealed tank and a second tank 2 that is also a sealed tank. The second tank 2 is disposed at a lower position than the first tank, and is connected to the first tank 1 via an openable / closable main valve 4.

Specifically, one end (upper end) of the connection pipe 5 is connected to the lower part of the first tank 1, and the other end (lower end) of the connection pipe 5 is connected to the second tank 2. Connected to the top of the. In the middle of the connecting pipe 5, the main valve 4 having an electric valve or electromagnetic valve force is interposed. By opening and closing the main valve 4, gas-liquid tight communication between the inside of the first tank 1 and the inside of the second tank 2 can be freely performed. The opening / closing operation of the main valve 4 which is an electric valve in the example of FIG. 1 is automatically controlled by a control device 6 including a microcomputer together with other electric devices or electromagnetic devices constituting the drain drainage device 100. . The main valve 4 is normally kept open.

[0022] The second tank 2 is connected with a water-sealed vacuum pump 8 as pressure reducing means via a pressure reducing pipe 7. The operation of the vacuum pump 8 is also automatically controlled by the control device 6. In the middle of the decompression pipe 7, a vacuum maintaining valve 9, which is an electromagnetic valve force, is interposed in order to prevent air from flowing into the decompressed second tank 2. The vacuum maintaining valve 9 is kept open when the vacuum pump 8 is operated, and is closed when the vacuum pump 8 is stopped. As the vacuum maintaining valve 9, a check valve may be employed instead of the solenoid valve.

[0023] The second tank 2 sucks the liquid to be collected by the operation of the vacuum pump 8. It is a tank (vacuum drain tank) that collects and stores. The second tank 2 is provided with a pressure gauge 10 for displaying the magnitude of the tank internal pressure and a pressure switch 11 as a tank internal pressure detecting means. When the depressurization value in the second tank 2 reaches a predetermined value by the operation of the vacuum pump 8, a depressurization completion signal is sent from the pressure switch 11 to the control device 6, and the control device 6 The operation of the vacuum pump 8 is stopped. Further, when the pressure reduction value in the second tank 2 does not reach a predetermined value due to drain suction or the like, a pressure shortage signal is sent from the pressure switch 11 to the control device 6, and the control device 6, the operation of the vacuum pump 8 is resumed. Thus, the second tank 2 is always maintained at a predetermined depressurization value while the circuit of the pressure switch 11 is ON.

[0024] Normally, since the main valve 4 is in an open state, the first tank 1 is also decompressed as much as the second tank 2. For this reason, the drain is sucked and collected into the second tank 2 through the drain collection main 3 and the first tank 1.

[0025] The second tank 2 is provided with a float switch 12 as a water level detection sensor. The float switch 12 sends a full water signal to the control device 6 when the drain in the second tank 2 reaches a predetermined maximum water level. Upon receiving this full water signal, the operation of the vacuum pump 8 is stopped by the control device 6, and the main valve 4 is closed by the control device 6. As a result, the communication between the first and second tanks 1 and 2 is shut off in a gas-liquid tight manner, and the drain is discharged from the second tank 2 while the first tank 1 is kept in a reduced pressure state. It becomes possible.

[0026] Instead of the float switch 12, an electrode bar type level sensor is used as the water level detection sensor.

[0027] The suction recovery main body A includes an air release valve 13 and a drainage valve 14 as a drainage control valve for discharging the drain stored in the second tank 2. ing. These valves can be motorized valves or solenoid valves. The air release valve 13 is an electromagnetic valve in the example of FIG. 1 and is disposed in an air release pipe 15 connected to the upper part of the second tank 2. On the other hand, the drain valve 14 is an electric valve in the example of FIG. 1 and is disposed in a drain pipe 16 connected to the bottom of the second tank 2. [0028] The air release valve 13 and the drain valve 14 are automatically controlled by the control device 6 so as to open after the main valve 4 is completely closed. In this case, the main valve 4 is of a type that generates a signal (fully closed signal) when it is completely closed. Upon receiving the fully closed signal, the control device 6 causes the atmospheric release valve 13 and Make sure that the drain valve 14 is open. When the air release valve 13 and the drain valve 14 are opened, the drain in the second tank 2 is drained.

[0029] While the drain valve 14 is fully closed, the drain valve 14 emits a fully closed signal, and when the operation starts from the fully closed state toward the fully open state, the fully closed signal disappears. The The control device 6 turns off the circuit of the pressure switch 11 in response to the disappearance of the fully closed signal of the drain valve 14. For this reason, the vacuum pump 8 does not operate after the drainage nozzle 14 starts the opening operation.

[0030] When the water level in the second tank 2 drops to a predetermined minimum water level due to drainage, the control device 6 receives the drainage completion signal from the float switch 12, and the control device 6 causes the air release valve 13 and The drainage nozzle 14 is closed.

[0031] It should be noted that delay means such as a delay relay and a timer are employed to close the atmosphere release valve 13 and the drain valve 14 after receiving a drain complete signal from the float switch 12, If the tank 2 is delayed for a predetermined time necessary for emptying, it is preferable that complete drainage from the second tank 2 can be achieved.

[0032] When the drain valve 14 is completely closed, the full-close signal is generated again. Upon receiving the full-close signal, the control device 6 turns on the circuit of the pressure switch 11, and the pressure In response to an under-decompression signal from the switch 11, the control device 6 activates the vacuum pump 8. When the internal pressure of the second tank 2 returns to a predetermined depressurized value by the operation of the vacuum pump 8, the depressurization completion signal from the pressure switch 11 is received and the main device 4 Is opened and the vacuum pump 8 is stopped.

[0033] By the opening operation of the main valve 4, the second tank 2 and the first tank 1 are Thus, the drain that has been stored in the first tank 1 until then flows into the second tank 2 and the suction of the drain by the second tank 2 is collected. Is resumed.

Next, the terminal unit B will be described.

[0035] A plurality of terminal units B each having an air conditioner 20 are arranged at the ceiling of each floor or room of the building where the suction collection main body A is installed. Each terminal unit B includes a water tank 21 as a liquid storage tank disposed in the vicinity of each air conditioner 20. Each water tank 21 is installed by a method of fixing to the air conditioner 20 using a mounting bracket or a force for fixing to the lower surface of the upper floor with suspension bolts. The drain generated by the operation of each air conditioner 20 naturally flows into each of the water tanks 21 by a heavy force.

In each of the water tanks 21, suction pipes (liquid absorption pipes) 22 for sucking the stored drain in the direction of the first tank 1 are inserted. The suction pipe 22 is made of a flexible pipe such as a copper pipe or nylon tube having an outer diameter of about 6 mm, which is kept warm to prevent dew condensation on the surface, and the drain collecting pipe communicating with the first tank 1 is used. It is connected to the branch pipe 17 that branches from the main 3 to each floor of the building. Each of the suction pipes 22 is composed of a thin flexible pipe as described above, so that it is possible to easily perform piping while avoiding obstacles even in a narrow ceiling where there are many obstacles and requires skilled workers. Piping work can be done in a short time without.

[0037] Each suction pipe 22 is provided with a terminal unit valve 23, which is an electromagnetic valve for controlling the movement of drain from each water tank 21 to the drain recovery main pipe 3.

[0038] Each water tank 21 is provided with a water level detection sensor 24 for detecting the water level of the drain stored therein. When the drain in each water tank 21 reaches a predetermined maximum water level, each terminal unit valve 23 is opened by a signal from the water level detection sensor 24, and the drain in each water tank 21 reaches a predetermined minimum water level. When lowered, the terminal unit valve 23 is closed by a signal from the water level detection sensor 24.

Furthermore, an overflow detection sensor 25 that is activated when the drain in the water tank 21 reaches a limit amount is attached to an appropriate position of each water tank 21. Each overflow detection sensor 25 is interlocked with each air conditioner 20, so that the water level in the water tank 21 should be When the air temperature rises abnormally, the operation of the corresponding air conditioner 20 is stopped and an alarm is issued to the outside.

[0040] In the figure, reference numeral 26 denotes an in-tank filter for preventing dust or the like contained in the drain from being sucked into the suction pipe 22.

[0041] A strainer 27 for filtering fine dust that has passed through the in-tank filter 26 may be disposed at an appropriate location of the drain recovery main pipe 3. In the present embodiment, manual valves 28 and 29 are provided on the upstream side and the downstream side of the strainer 27, respectively, and the strainer 27 is bypassed from the upstream side of the upstream valve 28 to bypass the downstream side node. A bypass pipe 30 merging further downstream of the rev 29 is provided, and a bypass nove 31 is provided on the bypass pipe 30. Therefore, if the upstream valve 28 and the downstream valve 29 are closed and the bypass valve 31 is opened, the strainer 27 can be cleaned without stopping the drainage device 100.

It should be noted that various alternative configurations can be adopted for each terminal unit B. The description of the alternative examples is omitted because it is not related to the gist of the present invention. For example, the terminal unit valve 23 is omitted, and the type proposed by the present applicant in Japanese Patent Application No. 2004-7813 is omitted. Can also be adopted.

[0043] The drainage device 100 according to the present embodiment configured as described above operates as follows.

In each terminal unit B, the drain generated by the operation of each air conditioner 20 naturally flows down and stored in each water tank 21 disposed adjacent thereto. At this time, the terminal unit valve 23 is closed. When the water level in each water tank 21 reaches a predetermined maximum water level, the terminal unit valve 23 is opened by a signal from the water level detection sensor 24.

Here, normally, the main valve 4 is in an open state, and the first and second tanks 1 and 2 are depressurized by the depressurizing action of the vacuum pump 8. By opening the terminal unit valve 23, the drain in the water tank 21 passes through the suction pipe 22, the branch pipe 17, the drain recovery main pipe 3, the first tank 1, and the connection pipe 5. It is collected by suction in the second tank 2. The water in the water tank 21 by suction collection When the position is lowered to the predetermined minimum water level, the terminal unit valve 23 is closed by the signal of the water level detection sensor 24 force.

[0046] When the drain in the second tank 2 reaches a predetermined maximum water level due to the suction and recovery of the drain, a full water signal is sent from the float switch 12 to the control device 6, and the control device 6 Thus, the operation of the vacuum pump 8 is stopped, and the main valve 4 is closed by the control device 6. As a result, the communication between the first and second tanks 1 and 2 is blocked, and the drain can be discharged from the second tank 2 while the first tank 1 is kept in a reduced pressure state. It becomes. In response to a fully closed signal generated by the closing operation of the main valve 4, the control device 6 opens the air release valve 13 and the drain valve 14, and the drain in the second tank 2 is externally connected. Is discharged.

[0047] When the drain valve 14 is opened, the full-close signal of the drain valve 14 that has been generated disappears. The control device 6 turns off the circuit of the pressure switch 11 in response to the disappearance of the fully closed signal of the drain valve 14. For this reason, the vacuum pump 8 does not operate during the drainage of the second tank 2 force.

[0048] Even after the main valve 4 is closed, the first tank 1 is in a depressurized state, so that the drain suction and recovery action by the drain recovery main pipe 3 continues. The collected drain is temporarily stored in the first tank 1. Therefore, the first tank 1 functions as a vacuum tank that sucks the drain instead of the second tank 2 while the main valve 4 is in the closed state, and the drained and collected drain is collected by the second tank 2. Instead of tank 2, it also functions as a drain tank that stores temporarily.

[0049] When drainage from the second tank 2 is completed, in response to the drainage completion signal from the float switch 12, the control device 6 causes the atmosphere release valve 13 and the drainage valve 14 to close. It is done. In response to the drain valve full close signal generated by the closing operation of the drain valve 14, the control device 6 turns on the circuit of the pressure switch 11. At this time, since the internal pressure of the second tank is atmospheric pressure, the pressure switch 11 generates an insufficient pressure reduction signal. In response to this decompression shortage signal, the control device 6 activates the vacuum pump 8 so that the internal pressure of the second tank 2 is It can be restored to a constant decompression value. In response to the pressure reduction completion signal from the pressure switch 11, the control device 6 opens the main valve 4 and stops the vacuum pump 8.

[0050] By the opening operation of the main valve 4, the second tank 2 and the first tank 1 communicate with each other as they are, so that they are sucked and collected in the first tank 1. !, The drain flows into the second tank 2 through the connecting pipe 5 and the drain recovery by the second tank 2 is resumed.

[0051] It should be noted that, after the main valve 4 is closed, the suction of the drain into the first tank 1 proceeds, so that the degree of decompression of the first tank 1 gradually decreases. Before the main tank 4 is opened and communication with the second tank 2 is resumed before the degree of decompression of the first tank 1 decreases so as to hinder suction collection, the air conditioning is resumed. There will be no problems such as interruption of drain recovery if drain flows back to the machine 20 side.

[0052] By continuing the above operation, drains generated from the plurality of air conditioners 20 are continuously sucked and collected at one place and discharged.

According to the drain drainage device 100 configured and operated as described above, after the second tank 2 is returned to the reduced pressure state, the main valve 4 is opened and the first tank 1 is opened. Since the communication is resumed, the decompression degree of the first tank 1 does not decrease when the main valve 4 is opened. Therefore, even if the volume of the first tank 1 in which the drain suction action by the suction pipe 22 is not reduced is smaller than the volume of the second tank 2, the drain in the water tank 21 is surely and continuously maintained. Can be collected by suction and discharged. Therefore, the suction recovery main body A can be made as compact as possible, which can greatly contribute to saving installation space and cost.

[0054] Therefore, the drainage drain device 100 is suitable for installation in a place where the installation space for the suction recovery main body cannot be increased, and collects and discharges the drains of a small number of air conditioners in one place. It is particularly suitable for use in.

By the way, in the drain drainage device 100, after the drainage from the second tank 2 is completed, the decompression completion signal from the pressure switch 11 is received and the opening operation of the main valve 4 and the vacuum pump 8 are performed. If both stop at the same time, the communication with the first tank 1 When the pressure reduction value of the second tank 2 falls below a predetermined value, a pressure shortage signal is issued from the pressure switch 11, and the stopped vacuum pump 8 is restarted immediately thereafter. Resulting in. However, from the viewpoint of quiet and smooth operation of the device, it is desirable to avoid the situation where the vacuum pump 8 is restarted immediately after the operation is stopped, as much as possible.

Therefore, in order to solve this problem, in the present embodiment, after the second tank 2 is depressurized to a predetermined depressurization value by the operation of the vacuum pump 8, the opening operation of the main valve 4 is performed. During this time, the pressure reducing operation is continued, and when the main valve 4 is fully opened and the second tank reaches a predetermined pressure reducing value, the vacuum pump 8 is stopped. Specifically, for example, the main valve 4 adopts a type that generates a signal (fully opened signal) when fully opened, and the fully open signal generated by the opening operation of the main valve 4 and the pressure switch. When both the decompression completion signal from 11 is obtained, the vacuum pump 8 should be stopped by the control device 6! In this way, frequent restart of the vacuum pump 8 can be suppressed, and a quiet and smooth operation of the apparatus is guaranteed, which is preferable.

[0057] As another method for solving the above problem, a delay means such as a delay relay or a timer is employed, and after receiving a pressure reduction completion signal from the pressure switch 11, the operation of the vacuum pump 8 is stopped. It is also possible to delay by a predetermined time that can compensate for the decrease in the reduced pressure value of the second tank 2 caused by the communication with the first tank 1. Also in this case, as described above, frequent restart of the vacuum pump 8 can be suppressed, and a quiet and smooth operation of the apparatus is guaranteed.

Claims

The scope of the claims

[1] A sealed first tank (1) connected to the liquid storage tank (21) via a liquid suction pipe (22), and the first tank via a freely openable / closable main valve (4) A sealed second tank (2) connected to (1), a decompression means (8) connected to the second tank (2), and the liquid in the second tank (2) A drainage device comprising a drainage control valve (13, 14) for draining.

[2] A control device (6) for automatically controlling the operation of the drainage device (100) is provided. After the main valve (4) is closed by the control device (6), the drainage control valve (13 14) is opened and the second tank (2) force liquid is discharged, and the drainage control valve (13, 14) is closed and the second pressure reducing means (8) The drainage device according to claim 1, wherein the main valve (4) is opened after the tank (2) of the tank is depressurized.

[3] The control device (6) is configured to reduce the pressure during the opening operation of the main valve (4) after the pressure reduction means (8) reduces the pressure of the second tank (2) to a predetermined pressure reduction value. The pressure reducing action by the pressure reducing means (8) is stopped when the main valve (4) is fully opened and the second tank (2) reaches a predetermined pressure reducing value. The drainage device described

[4] After the second tank (2) is depressurized to a predetermined depressurization value by the depressurization means (8), the depressurization action by the depressurization means (8) is stopped, and the main valve (4) is opened. The drainage device according to claim 2, further comprising delay means for delaying by a predetermined time that can compensate for a decrease in the reduced pressure value of the second tank (2) caused by the operation.

[5] A sealed first tank (1) connected to the liquid storage tank (21) via the liquid suction pipe (22) and the first tank via the openable / closable main valve (4). A sealed second tank (2) connected to (1), a decompression means (8) connected to the second tank (2), and the liquid in the second tank (2) And a drainage control valve (13, 14) for discharging, the drainage control valve (13, 14) is closed and the main valve (4) is opened, and the pressure reducing means (8) By depressurizing the second tank (2), the liquid in the liquid storage tank (21) is transferred to the second tank (21) via the liquid absorption pipe (22) and the first tank (1). 2), the second main valve (4) is closed, and then the drainage control valve (13, 14) is opened. The liquid is discharged from the tank (2), and then the drainage control valve (13, 14) is closed and the second tank (2) is depressurized by the depressurizing means (8). (4) A method of draining, characterized by opening.