JP6089934B2 - Drain collection system - Google Patents

Description

  The present invention relates to a drain recovery system. More specifically, the present invention relates to a closed-type drain collection system that collects drain discharged from a load device without supplying it to the atmosphere and supplies water to a boiler.

Conventionally, a drain recovery system has been proposed in which steam generated in a boiler is supplied to load equipment, drain generated from the steam used as a heat source in the load equipment is recovered, and reused as water supply to the boiler.
As the drain recovery system, the drain generated in the load equipment is recovered in an open drain recovery tank that is open to the atmosphere and supplied to the boiler, and the sealed drain recovery with pressure resistance A closed-type drain recovery system is known in which drain is recovered in a tank at a high temperature and high pressure, and the drain is supplied to a boiler (see, for example, Patent Document 1).

JP 2006-105442 A

  In the closed drain recovery system, water can be supplied at a higher temperature than in the open drain recovery system, so that the fuel consumption of the boiler can be reduced and the operating cost of the boiler can be reduced. Moreover, since the pressure difference with a boiler can be made small by keeping the pressure inside a drain collection | recovery tank high, the motive power which drives the feed water pump used when supplying water to a boiler from a drain collection | recovery tank can be reduced.

By the way, in the drain recovery system, in order to discharge the drain from the load device to the drain recovery tank, it is necessary to keep the pressure inside the drain recovery tank smaller than the pressure inside the load device. In addition, since heat is exchanged using steam in the load equipment, the temperature of the steam in the load equipment is lower than the temperature of the steam generated in the boiler, and the pressure inside the load equipment is the pressure of the boiler. Smaller than.
For this reason, in the conventional closed-type drain recovery system, the boiler cannot be supplied with the pressure inside the drain recovery tank sufficiently increased, and the power for driving the water supply pump cannot be reduced sufficiently.

  Further, in the drain recovery system, in order to enable continuous water supply to the boiler, the drain recovery tank may include an assist tank, and after the drain is temporarily stored in the assist tank, the drain may be supplied to the boiler. In such a case, the valve disposed in each line wears when the opening / closing operation is large, so the capacity of the assist tank is increased to some extent in order to reduce the number of times the valve disposed in each line is opened and closed. It is preferable.

  However, if the diameter of the assist tank is increased in order to increase the capacity of the assist tank, the interface between the drain and steam inside the assist tank increases. Along with this, the area of the interface to maintain the saturated state of water vapor increases. For this reason, the time for increasing the pressure inside the assist tank becomes longer, and the amount of steam supplied to the assist tank increases. Therefore, the time until water supply from the assist tank to the boiler is delayed.

  Therefore, an object of the present invention is to provide a drain recovery system that can increase the capacity of the assist tank and can shorten the time required to start water supply from the assist tank to the boiler.

  The present invention is a drain recovery system that recovers drain that is generated in a boiler and agglomerates steam used in a load device and supplies the drain to the boiler, the drain generated in the load device is accommodated, A cylindrical assist tank whose height direction is arranged along the vertical direction, a drain supply line that connects the load device and the assist tank, and supplies drain generated in the load device to the assist tank; A drain supply valve that opens and closes the drain supply line, a steam supply line that connects the boiler and the assist tank and supplies steam generated in the boiler to the assist tank, and a steam supply that opens and closes the steam supply line A valve is connected to the assist tank and the boiler, and the drain accommodated in the assist tank is supplied to the boiler. A water supply line that, and a feed water pump disposed in the water supply line, the assist tank relates drain recovery system is 3 or more ratio of height to diameter.

  It is preferable that a plurality of the assist tanks are provided.

  The total capacity of the assist tank is 1000 to 4000 L, and the diameter of the assist tank is preferably 300 to 700 mm.

  According to the drain recovery system of the present invention, an object of the present invention is to provide a drain recovery system capable of increasing the capacity of an assist tank and shortening the time required to start water supply from the assist tank to the boiler.

It is a figure showing composition of a drain recovery system concerning one embodiment of the present invention. It is the schematic which shows the structure of the assist tank in this embodiment. It is explanatory drawing which shows the open / close state of each valve in the drain collection | recovery system of this embodiment.

  Hereinafter, an embodiment of a drain recovery system of the present invention will be described with reference to the drawings. The drain recovery system of the present embodiment is a closed type drain recovery system that recovers drain generated in a load device in a high-pressure and high-pressure state in a sealed tank having pressure resistance, and supplies the drain to a boiler. .

First, the overall configuration of the drain recovery system 1 of the present embodiment will be described with reference to FIG. In the following description, “line” is a general term for a flow path, a path, a pipeline, and the like.
The drain collection system 1 of this embodiment includes a boiler 10, a load device 20, an assist tank 40, an open tank 50, and a drain pump 60 as a feed water pump.

  The drain recovery system 1 includes a plurality of lines that connect these devices and through which steam or water flows, and a plurality of valves that open and close the plurality of lines. Specifically, the drain recovery system 1 includes a first steam supply line L1, a drain supply line L2, a second steam supply line L3 as a steam supply line of the present invention, a water supply line L4, and a flash as lines. A steam discharge line L5 and a makeup water supply line L6 are provided. Moreover, the drain collection | recovery system 1 is provided with the drain supply valve 71 and the steam supply valve 72 as a valve.

The boiler 10 includes a plurality of can bodies 11 that generate steam, a steam header 12 that collects steam generated by the plurality of can bodies 11, and a connecting pipe 13 that connects the plurality of can bodies 11 and the steam header 12. And comprising.
The plurality of can bodies 11 generate steam by heating the water supplied to these can bodies 11. Steam generated in the plurality of cans 11 is supplied to the steam header 12 through the connecting pipe 13.

  The load device 20 uses the steam generated in the boiler 10 as a heat source, and performs heat exchange with the object to be heated.

The assist tank 40 is disposed above the boiler 10. The assist tank 40 collects and stores drainage generated by agglomeration of a part of the steam used for heat exchange in the load device 20. The drain accommodated in the assist tank 40 is supplied to the boiler 10.
In the present embodiment, the assist tank 40 includes two tanks, a first assist tank 40A and a second assist tank 40B. Water level sensors SA and SB are attached to the first assist tank 40A and the second assist tank 40B, respectively, as water level detection units for detecting the water level of the stored drain.

  The assist tank 40 is constituted by a pressure vessel that has pressure resistance and can be sealed. More specifically, as shown in FIG. 2, the assist tank 40 is disposed inside the tank body 41, a tank body 41 as an assist tank of the present invention, a steam inlet 42 provided in the tank body 41, and the tank body 41. A plate-like member 43.

The tank body 41 is formed in a cylindrical shape, and the height direction is arranged along the vertical direction. The tank body 41 is configured such that the area of the interface between the drain and the steam inside the tank body 41 is reduced while ensuring a large capacity of the tank body 41. In order to realize this, in the present embodiment, the tank body 41 is formed in a vertically long cylindrical shape whose height is higher than the diameter, and the ratio of the height to the diameter is 3 or more.
More specifically, in the present embodiment, the total capacity of the tank body 41 is set to, for example, 1000 to 4000 L, corresponding to the large amount of vapor generated by the boiler 10. Further, in order to reduce the diameter of the tank main body 41 and reduce the area of the interface between the drain and the steam inside the tank main body 41 and to speed up the time until the water supply from the assist tank 40 to the boiler 10 is started, for example, It is set to 300 to 700 mm. Specifically, for example, the following Table 1 is obtained for the ratio of the height to the diameter of the tank body 41.

In Table 1 above, when the capacity of the tank body 41 is 1000 L, 2000 L, 3000 L, and 4000 L and the diameters are 300 mm, 500 mm, and 700 mm, the ratio of the height to the diameter of the tank body 41 is obtained.
According to Table 1 above, when the total capacity of the tank body 41 is 1000 to 4000 L and the diameter of the tank body 41 is 300 to 700 mm, the capacity of the tank body 41 is 1000 L, and When the diameter is 700 mm, the minimum value of the ratio of the height to the diameter in the tank body 41 (assist tank) is 3.71. Therefore, when the total capacity of the tank body 41 is 1000 to 4000 L and the diameter of the tank body 41 is 300 to 700 mm, the tank body 41 (assist tank) has a height ratio to the diameter of 3 or more. Preferably there is.

  In the present embodiment, the total capacity of the tank main body 41 is 1000 to 4000 L by the total capacity of the two assist tanks of the tank main body 41 of the first assist tank 40A and the tank main body 41 of the second assist tank 40B. doing. For example, the capacity of the tank body 41 may be a total capacity of 2000 L using two 1000 L assist tanks 40 or a total capacity of 4000 L using two 2000 L assist tanks 40.

  Furthermore, in the present embodiment, it is assumed that a steam with an evaporation amount of 21 t per hour is generated from the boiler 10 as a preferable capacity of the assist tank 40. Therefore, the capacity of the tank body 41 of the first assist tank 40A is assumed to be 2000L, and the capacity of the tank body 41 of the second assist tank 40B is assumed to be 2000L. Further, the diameter of the tank main body 41 is assumed to be 500 mm in order to reduce the area of the interface between the drain and the steam inside the tank main body 41. In this case, as shown in Table 1 above, the tank body 41 of the first assist tank 40A and the tank body 41 of the second assist tank 40B each have a height of 10.185 m, and the height relative to the diameter. The ratio is 20.3.

  The steam inlet 42 is provided at the center of the upper surface of the tank body 41. The steam inlet 42 is connected to the downstream end of a second steam supply line L3 described later. The steam supplied from the second steam supply line L <b> 3 is introduced into the tank main body 41 downward from the steam inlet 42.

  The plate-like member 43 is formed in a disk shape having a diameter smaller than the diameter of the tank body 41. The plate-like member 43 is disposed below the steam inlet 42 so as to spread in the horizontal direction. The plate-like member 43 functions as a rectifying plate that rectifies steam introduced from the steam inlet 42 into the tank body 41. For example, the plate member 43 is suspended by a suspension member (not shown) provided on the inner surface of the upper surface of the tank body 41 and is disposed below the steam inlet 42.

  The open tank 50 is open to the atmosphere. The open tank 50 stores makeup water supplied to the boiler 10 via the assist tank 40. In addition, flash vapor generated from drain in the assist tank 40 is introduced into the open tank 50.

  The drain pump 60 is disposed in a water supply line L4 described in detail later. The drain pump 60 boosts the drain supplied from the assist tank 40 and supplies it to the boiler 10.

The first steam supply line L <b> 1 connects the steam header 12 and the load device 20, and supplies the steam generated in the boiler 10 to the load device 20.
The drain supply line L2 connects the load device 20 and the assist tank 40, and supplies the drain generated in the load device 20 to the assist tank 40. A steam trap 81 that discharges the drain generated in the load device 20 and prevents the steam from being discharged is disposed in the drain supply line L2. Further, a check valve 82 is disposed in the drain supply line L2.

  In the present embodiment, the drain supply line L2 is branched into a drain supply line L2A for supplying drain to the first assist tank 40A and a drain supply line L2B for supplying drain to the second assist tank 40B on the downstream side. Yes. The downstream end of the drain supply line L2A is connected to the upper part of the first assist tank 40A, and the downstream end of the drain supply line L2B is connected to the upper part of the second assist tank 40B.

  The drain supply valve 71 is constituted by a motor valve and is disposed in the drain supply line L2. The drain supply valve 71 opens and closes the drain supply line L2. In the present embodiment, as the drain supply valve 71, a first drain supply valve 71A is disposed in the drain supply line L2A, and a second drain supply valve 71B is disposed in the drain supply line L2B.

  The second steam supply line L3 connects the steam header 12 and the assist tank 40 and supplies steam generated in the boiler 10 to the assist tank 40. In the present embodiment, the second steam supply line L3 includes, on the downstream side, a second steam supply line L3A that supplies steam to the first assist tank 40A and a second steam supply line that supplies steam to the second assist tank 40B. Branches to L3B. The downstream end of the second steam supply line L3A is connected to the upper part of the first assist tank 40A, and the downstream end of the second steam supply line L3B is connected to the upper part of the second assist tank 40B. Is done.

  The steam supply valve 72 is configured by a motor valve and is disposed in the second steam supply line L3. The steam supply valve 72 opens and closes the second steam supply line L3. In the present embodiment, as the steam supply valve 72, the first steam supply valve 72A is disposed in the second steam supply line L3A, and the second steam supply valve 72B is disposed in the second steam supply line L3B. Further, on the downstream side of the first steam supply valve 72A in the second steam supply line L3A and the downstream side of the second steam supply valve 72B in the second steam supply line L3B, a reverse flow that prevents the backflow of steam from the assist tank 40 is prevented. Stop valves 83A and 83B are arranged.

The water supply line L4 connects the assist tank 40 and the boiler 10 and supplies the drain accommodated in the assist tank 40 to the boiler 10. In the present embodiment, the water supply line L4 includes a water supply line L4A whose upstream end is connected to the first assist tank 40A and a water supply line L4B whose upstream end is connected to the second assist tank 40B. , And connected at the connecting portion 86. The drain pump 60 described above is disposed on the downstream side of the connecting portion 86 in the water supply line L4.
The water supply line L <b> 4 branches into the same number as the plurality of can bodies 11 on the downstream side of the connection portion 86, and ends of the branched lines are connected to the plurality of can bodies 11.

  In the present embodiment, check valves 87A and 87B for preventing the backflow of water from the boiler 10 are disposed in the water supply line L4A and the water supply line L4B, respectively.

  The makeup water supply line L <b> 6 connects the open tank 50 and the assist tank 40, and supplies makeup water stored in the open tank 50 to the assist tank 40. A makeup water supply pump 84 is disposed in the makeup water supply line L6. By driving the makeup water supply pump 84, makeup water is supplied from the open tank 50 to the assist tank 40.

  In the present embodiment, the makeup water supply line L6 includes, on the downstream side, a makeup water supply line L6A that supplies makeup water to the first assist tank 40A, and a makeup water supply line L6B that supplies drain to the second assist tank 40B. It is branched to. The downstream end of the makeup water supply line L6A is connected to the bottom of the first assist tank 40A, and the downstream end of the makeup water supply line L6B is connected to the bottom of the second assist tank 40B. .

  The flash vapor discharge line L5 connects the assist tank 40 and the open tank 50, and discharges the flash vapor generated in the assist tank 40 to the open tank 50. In the flash steam discharge line L5, an automatic opening / closing valve 88 and a pressure adjusting valve 85 are arranged in this order from the upstream side. When the pressure inside the assist tank 40 exceeds a predetermined pressure, the pressure regulating valve 85 releases the flash vapor to the open tank 50 side and reduces the pressure inside the assist tank 40.

  In the present embodiment, the flash steam discharge line L5 branches on the upstream side into a flash steam discharge line L5A for releasing steam from the first assist tank 40A and a flash steam discharge line L5B for releasing steam from the second assist tank 40B. ing. The upstream end of the flash steam discharge line L5A is connected to the upper part of the first assist tank 40A, and the upstream end of the flash steam discharge line L5B is connected to the upper part of the second assist tank 40B. .

As the pressure adjustment valve 85, a pressure adjustment valve 85A is disposed in the flash steam discharge line L5A, and a pressure adjustment valve 85B is disposed in the flash steam discharge line L5B.
The automatic opening / closing valve 88 is constituted by a motor valve and opens / closes the flash steam discharge line L5. In the present embodiment, as the automatic open / close valve 88, an automatic open / close valve 88A is disposed in the flash steam discharge line L5A, and an automatic open / close valve 88B is disposed in the flash steam discharge line L5B.

  In the drain collection system 1 of the present embodiment, the drain generated in the load device 20 is supplied to the first assist tank 40A or the second assist tank 40B via the drain supply line L2. The drain is supplied to the boiler 10 from either the first assist tank 40A or the second assist tank 40B through the water supply line L4.

  Further, the upstream end of the second steam supply line L3 was connected to the steam header 12. Thereby, since steam can be supplied to the assist tank 40 from the steam header 12 in which steam generated in the plurality of can bodies 11 is collected, changes in the pressures of the plurality of can bodies 11 when steam is used in the assist tank 40. Can be reduced.

  Furthermore, since the assist tank 40 is composed of two tanks, the first assist tank 40A and the second assist tank 40B, continuous water supply to the boiler 10 becomes possible.

Next, a specific operation of the drain recovery system 1 of the present embodiment will be described.
The drain recovery system 1 supplies the drain to the boiler 10 mainly with the first drain supply valve 71A, the second drain supply valve 71B, the first steam supply valve 72A, and the second steam supply valve 72B shown in FIG. This can be realized by opening and closing according to the following procedure.
FIG. 3 shows the first drain supply valve 71A, the second drain supply valve 71B, the first steam supply valve 72A, and the second steam supply valve 72B in each step when the boiler 10 is continuously supplied with water by the drain recovery system 1. It is a figure which shows an open / close state.

  In FIG. 3, the water level of the first assist tank 40A is in a full water state (a state where the water level is higher than the second water level described later), and the water level of the second assist tank 40B is lowered (lower than the first water level described later). In the state), a case where water supply to the boiler 10 is started will be described. In this case, as shown in FIG. 3, the valves are opened and closed in the order of the first step, the second step, the third step, and the fourth step, and these first to fourth steps are repeated. Note that the drain pump 60 is continuously driven while water is supplied to the boiler 10.

In the first step, water is supplied from the first assist tank 40A to the boiler 10, and the drain is supplied to the second assist tank 40B.
In this case, as shown in FIG. 3, first, the first steam supply valve 72A is opened and steam is supplied to the first assist tank 40A. When the pressure inside the first assist tank 40A is increased and the difference between the pressure inside the first assist tank 40A and the pressure in the boiler 10 becomes smaller than a predetermined value (for example, 0.2 MPa), the drain pump 60 With this driving force, supply of drain from the first assist tank 40A to the boiler 10 is started.

  Here, the tank body 41 in the first assist tank 40A is formed in a vertically long cylindrical shape. Further, the tank body 41 has a ratio of height to diameter of 3 or more. Thereby, the area of the interface between the drain and steam in the tank body 41 can be reduced. Therefore, since the area of the interface that should maintain the saturated state of water vapor can be reduced, the pressure inside the first assist tank 40A can be increased in a short time. Further, since the amount of steam supplied to the first assist tank 40A can be reduced, the energy saving effect can be improved.

  On the other hand, in the first step, the water level detected by the water level sensor SB is lower than the first water level, which is a water level indicating that the drain stored in the second assist tank 40B is low. When the water level detected by the water level sensor SB falls below the first water level, the second drain supply valve 71B is opened. Thereby, the drain is supplied to the second assist tank 40B.

In the second step, in a state where water is supplied from the first assist tank 40A to the boiler 10, the supply of drain to the second assist tank 40B is completed, and the second assist tank 40B enters a standby state.
In the second step, the state where the first steam supply valve 72A is opened and the first drain supply valve 71A is closed is maintained, and water supply from the first assist tank 40A to the boiler 10 is continued. And the water level of the drain accommodated in 40 A of 1st assist tanks falls.

  On the other hand, in the second step, when the water level of the second assist tank 40B is higher than the first water level and rises to the second water level that is the water level indicating the full water state of the second assist tank 40B, the water level sensor SB. Is detected to have exceeded the second water level. When the water level sensor SB detects that the second water level has been exceeded, the second drain supply valve 71B is closed. Thereby, the 2nd assist tank 40B will be in the standby state in which the preparation for the water supply to the boiler 10 was completed.

In the third step, the water level of the first assist tank 40A is lowered, and water supply from the first assist tank 40A to the boiler 10 is stopped. Further, water supply from the second assist tank 40B to the boiler 10 is started, and drain is supplied to the first assist tank 40A.
In the third step, when the water level of the first assist tank 40A is lowered to a predetermined first water level, it is detected by the water level sensor SA that the water level is below the first water level. When the water level sensor SA detects that the water level is below the first water level, the first steam supply valve 72A is closed. Then, the supply of steam to the first assist tank 40A is stopped, and the pressure inside the first assist tank 40A decreases. When the pressure difference between the pressure inside the first assist tank 40A and the boiler pressure exceeds a predetermined value (for example, 0.2 MPa), the supply of steam from the first assist tank 40A to the boiler 10 is stopped. The

  In the third step, the first drain supply valve 71A is opened after the first steam supply valve 72A is closed or at the same time as the first steam supply valve 72A is closed. Thereby, the drain is supplied to the first assist tank 40A.

  On the other hand, in the third step, when the water level sensor SA of the first assist tank 40A detects that the water level is lower than the first water level, the second steam supply valve 72B is opened. Then, steam is supplied to the second assist tank 40B, and the pressure inside the second assist tank 40B is increased. When the difference between the pressure inside the second assist tank 40B and the pressure in the boiler 10 becomes smaller than a predetermined value (for example, 0.2 MPa), the boiler from the second assist tank 40B is driven by the driving force of the drain pump 60. The supply of drain to 10 is started.

  Here, the tank body 41 in the second assist tank 40B is configured in a vertically long cylindrical shape. Further, the tank body 41 has a ratio of height to diameter of 3 or more. Thereby, the area of the interface between the drain and steam in the tank body 41 can be reduced. Therefore, since the area of the interface that should maintain the saturated state of water vapor can be reduced, the pressure inside the second assist tank 40B can be increased in a short time. Further, since the amount of steam supplied to the second assist tank 40B can be reduced, the energy saving effect can be improved.

In the fourth step, in the state where water is supplied from the second assist tank 40B to the boiler 10, the supply of drain to the first assist tank 40A is completed, and the first assist tank 40A enters a standby state.
In the fourth step, the state where the second steam supply valve 72B is opened, the second drain supply valve 71B and the second communication valve 73B are closed is maintained, and water supply from the second assist tank 40B to the boiler 10 is continued. The

  On the other hand, in the fourth step, when the water level of the first assist tank 40A rises to the second water level, it is detected by the water level sensor SA that it has exceeded the second water level. When the water level sensor SA detects that the second water level has been exceeded, the first drain supply valve 71A is closed. Thereby, 40 A of 1st assist tanks will be in the standby state in which preparation for the water supply to the boiler 10 was completed.

  While the water supply to the boiler 10 continues, the first to fourth steps are repeated.

According to the drain recovery system 1 described above, the tank body 41 has a ratio of height to diameter of 3 or more. Thereby, the capacity | capacitance of the assist tank 40 can be enlarged, reducing the area of the interface of the drain and vapor | steam inside the tank main body 41. FIG. Therefore, without providing another tank between the boiler 10 and the assist tank 40, a large-capacity drain is temporarily stored in a portion below the interface between the drain and steam inside the tank body 41. It can be a buffered part, and the drain can be accommodated in this large capacity buffered part. In addition, since the large-capacity drain is buffered inside the tank main body 41, the number of opening and closing of the valve can be reduced as compared with the case where another tank is provided between the boiler 10 and the assist tank 40.
In addition, since the area of the interface between the drain and the steam in the tank body 41 can be reduced, the area of the interface where the saturated state of water vapor should be maintained can be reduced, and the amount of steam supplied to the assist tank 40 can be reduced. Therefore, the pressure inside the assist tank 40 can be increased in a short time, and the time until the water supply from the assist tank 40 to the boiler 10 is started can be shortened. Therefore, waste of heat energy from the boiler 10 can be reduced, and the drain recovery system 1 can be operated efficiently.

  Further, the drain collection system 1 of the present embodiment includes two assist tanks 40. Thus, the capacity of the assist tank 40 can be increased using the two assist tanks 40.

  Moreover, in the drain collection system 1 of this embodiment, the total capacity | capacitance of the assist tank 40 is 1000-4000L, and the diameter of the tank main body 41 is 300-700 mm. Thereby, since the total capacity | capacitance of the assist tank 40 was 1000-4000L, even when using the boiler 10 with large vapor | steam evaporation amount, drain can be collect | recovered in large quantities. Further, since the diameter of the tank body 41 is set to 300 to 700 mm, the area of the interface between the drain and the steam inside the tank body 41 is reduced, and the time until the water supply from the assist tank 40 to the boiler 10 is started is shortened. can do.

The preferred embodiment of the drain recovery system of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be modified as appropriate.
For example, in the present embodiment, the upstream side of the second steam supply line L3 is connected to the steam header 12, but this is not a limitation. That is, the upstream side of the second steam supply line L3 may be connected to any one of the plurality of cans.

  Moreover, in this embodiment, although the drain collection system 1 was comprised including the two assist tanks 40A of the 1st assist tank 40A and the 2nd assist tank 40B, it is not restricted to this. That is, the drain recovery system may be configured by one assist tank. Further, the assist tank 40 may include three or more assist tanks.

1 Drain recovery system 10 Boiler 20 Loaded equipment 41 Tank body (assist tank)
60 Drain pump (water supply pump)
71 Drain supply valve 72 Steam supply valve L2 Drain supply line L3 Second steam supply line (steam supply line)
L4 water supply line

Claims (3)

A drain recovery system that recovers drain that is generated in a boiler and is generated by agglomeration of steam used in a load device and supplies the drain to the boiler,
A cylindrical assist tank in which the drain generated in the load device is accommodated and the height direction is arranged along the vertical direction;
A drain supply line for connecting the load device and the assist tank, and supplying drain generated in the load device to the assist tank;
A drain supply valve for opening and closing the drain supply line;
A steam supply line for connecting the boiler and the assist tank, and supplying steam generated in the boiler to the assist tank;
A steam supply valve for opening and closing the steam supply line;
A water supply line that connects the assist tank and the boiler, and supplies drain stored in the assist tank to the boiler;
A water supply pump disposed in the water supply line,
The assist tank is a drain recovery system having a ratio of height to diameter of 3 or more.   The drain collection system according to claim 1, comprising a plurality of the assist tanks. The total capacity of the assist tank is 1000 to 4000L.
The drain recovery system according to claim 1 or 2, wherein the assist tank has a diameter of 300 to 700 mm.

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