JP6182961B2 - 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 enable continuous water supply to the boiler, the drain recovery tank includes a first assist tank and a second assist tank, and alternately supplies water to the boiler from the first assist tank and the second assist tank. May be switched to Here, when water is supplied from the first assist tank to the boiler, the second assist tank may be put on standby.

However, when the second assist tank is made to stand by, the pressure inside the second assist tank is not kept high, so that the pressure difference between the pressure inside the second assist tank and the boiler is large. Therefore, even if the water supply pump is driven or the second assist tank is switched from the standby state to the water supply state, water supply from the second assist tank to the boiler starts until the internal pressure of the second assist tank increases. Not.
Therefore, even if the second assist tank in the standby state is switched to the water supply state, water supply to the boiler is not immediately executed, and a time lag occurs at the timing of starting water supply to the boiler.

  Therefore, an object of the present invention is to provide a drain recovery system that includes a first assist tank and a second assist tank, and that can reduce a time lag in timing of starting water supply from the second assist tank to the boiler.

  The present invention is a drain recovery system that recovers drain generated by agglomeration of steam generated in a boiler and used in a load device and supplies the drain to the boiler, and the drain generated in the load device is accommodated. A buffer tank, a first assist tank and a second assist tank disposed below the buffer tank, the load device and the buffer tank are connected, and drain generated in the load device is supplied to the buffer tank. A first drain supply line that connects the buffer tank and the first assist tank, and supplies the drain accommodated in the buffer tank to the first assist tank; and A first drain supply valve that opens and closes one assist tank drain supply line; the buffer tank; A second assist tank drain supply line connected to the assist tank and supplying drain accommodated in the buffer tank to the second assist tank; and a second drain supply valve opening and closing the second assist tank drain supply line; A first communication line that connects the first assist tank and the buffer tank, communicates the internal space of the first assist tank and the internal space of the buffer tank, and a first that opens and closes the first communication line. A communication valve is connected to the second assist tank and the buffer tank, and a second communication line that connects the internal space of the second assist tank and the internal space of the buffer tank is opened and closed. A second communication valve that connects the boiler and the first assist tank, and the steam generated in the boiler is A first steam supply line for supplying to the strike tank, a first steam supply valve for opening and closing the first steam supply line, the boiler and the second assist tank are connected, and the steam generated in the boiler is the second A second steam supply line that supplies the assist tank; a second steam supply valve that opens and closes the second steam supply line; the first assist tank, the second assist tank, and the boiler; A water supply line for supplying drains stored in the assist tank and the second assist tank to the boiler, a water supply pump disposed in the water supply line, and the first assist tank are provided in the first assist tank. A first water level detector for detecting the level of the drained water, and a water level of the drain provided in the second assist tank and housed in the second assist tank A first water supply level detector, a first water level detection unit, and a water level detected by the second water level detection unit, the first drain supply valve, the second drain supply valve, and the first steam. A control unit that controls the supply valve, the second steam supply valve, the first communication valve, and the second communication valve, and the control unit opens the first steam supply valve and controls the first In the state where the drain supply valve and the first communication valve are closed, the second steam supply valve is closed, and the second communication valve and the second drain supply valve are opened, the second assist tank The drain recovery system opens the second steam supply valve and closes the second drain supply valve and the second communication valve when the water level exceeds the first water level.

  Further, the control unit closes the first steam supply valve when the water level of the first assist tank falls below a second water level that is lower than the first water level, and the first communication valve and the first It is preferable to open the 1 drain supply valve.

  In addition, the control unit opens the first steam supply valve and closes the first drain supply valve and the first communication valve when the water level of the first assist tank exceeds the first water level. Is preferred.

The present invention also relates to a drain recovery system that recovers the drain that is generated in the boiler and agglomerates the steam used in the load equipment and supplies the drain to the boiler, and the drain generated in the load equipment is stored in the drain recovery system. A buffer tank, a first assist tank and a second assist tank disposed below the buffer tank, the load device and the buffer tank are connected, and the drain generated in the load device is discharged to the buffer tank. A first drain supply line for supplying to the first assist tank drain supply line, connecting the buffer tank and the first assist tank, and supplying drain accommodated in the buffer tank to the first assist tank; A first drain supply valve that opens and closes the first assist tank drain supply line; and the buffer tank; The second assist tank is connected to the second assist tank, the second assist tank drain supply line for supplying the drain accommodated in the buffer tank to the second assist tank, and the second drain for opening and closing the second assist tank drain supply line. A supply valve, a first communication line that connects the first assist tank and the buffer tank, and connects the internal space of the first assist tank and the internal space of the buffer tank; and opens and closes the first communication line A second communication line that connects the first assist valve, the second assist tank and the buffer tank, and communicates the internal space of the second assist tank and the internal space of the buffer tank, and the second communication A second communication valve for opening and closing a line, the boiler and the first assist tank are connected, and the steam generated in the boiler is A first steam supply line for supplying to one assist tank, a first steam supply valve for opening and closing the first steam supply line, the boiler and the second assist tank are connected, and the steam generated in the boiler is A second steam supply line for supplying to the second assist tank; a second steam supply valve for opening and closing the second steam supply line; a boiler-side water supply line connected to the boiler on the downstream side; and the first assist tank on the upstream side A first water supply line that is connected to the boiler side water supply line, and a second water supply line that is connected to the second assist tank and has a downstream side connected to the boiler side water supply line. A first water supply valve that opens and closes the first water supply line, a second water supply valve that opens and closes the second water supply line, and the boiler-side water supply line The first drain supply valve, the second drain supply valve, the first steam supply valve, the second steam supply valve, the first communication valve, the second communication valve, the second drain valve, A control unit that controls the first water supply valve and the second water supply valve, and the control unit supplies water to the first assist tank when the first drain supply valve and the first communication valve are closed. The first steam supply valve is controlled to be opened while the first water supply valve is controlled to be closed so that the first water supply valve is closed, and the second drain supply valve and the second communication valve are closed. A drain recovery system that controls to open the second steam supply valve in a state in which the second water supply valve is controlled to be closed so that the second assist tank is in a water supply preparation state in the state where About.

  According to the drain recovery system of the present invention, it is possible to provide a drain recovery system that includes a first assist tank and a second assist tank, and that can reduce a time lag in timing of starting water supply from the second assist tank to the boiler.

It is a figure which shows the structure of the drain collection | recovery system which concerns on 1st Embodiment of this invention. It is the schematic which shows the structure of the assist tank in 1st Embodiment. It is explanatory drawing which shows the open / close state of each valve in the drain collection | recovery system of 1st Embodiment. It is a figure which shows the structure of the drain collection | recovery system which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows the open / close state of each valve in the drain collection | recovery system of 2nd 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 first 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, a buffer tank 30, an assist tank 40, an open tank 50, and a drain pump 60 as a water supply pump.

  The drain recovery system 1 connects these devices, and controls a plurality of lines through which steam or water flows, a plurality of valves for opening and closing the plurality of lines, and operations of the plurality of valves and the like. 9 is provided. Specifically, the drain recovery system 1 includes, as lines, a first steam supply line L1, a first drain supply line L2, an assist tank drain supply line L3, an assist tank steam supply line L4, and a second steam supply. A line L5, a communication line L6, a water supply line L7, a makeup water supply line L8, and a flash steam discharge line L9 are provided. In addition, the drain recovery system 1 includes a drain supply valve 71, a steam supply valve 72, and a communication valve 73 as valves.

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 buffer tank 30 collects and stores drainage generated by agglomeration of a part of the steam used for heat exchange in the load device 20. The buffer tank 30 is constituted by a pressure vessel that has pressure resistance and can be sealed. The buffer tank 30 is disposed above the boiler 10.

  The assist tank 40 is disposed on the downstream side of the buffer tank 30. The assist tank 40 is disposed below the buffer tank 30 and above the boiler 10. The assist tank 40 stores the drain supplied from the buffer tank 30. 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. A first water level sensor SA as a first water level detection unit that detects the water level of the stored drain is attached to the first assist tank 40A. The first water level sensor SA detects the water level of the drain stored in the first assist tank 40A. The second assist tank 40B is provided with a second water level sensor SB as a second water level detection unit that detects the water level of the stored drain. The second water level sensor SB detects the water level of the drain accommodated in the second assist tank 40B.

  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 includes a tank main body 41, a steam inlet 42 provided in the tank main body 41, and a plate-like member 43 disposed inside the tank main body 41. .

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 formed in a vertically long cylindrical shape whose height is higher than the diameter.
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 an assist tank steam supply line L4 described later. The steam supplied from the assist tank steam supply line L4 is introduced into the tank body 41 from the steam inlet 42 downward.

  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 buffer tank 30 and the assist tank 40. In addition, flash vapor generated from drain in the buffer tank 30 is introduced into the open tank 50.

  The drain pump 60 is disposed in a water supply line L7 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 first drain supply line L <b> 2 connects the load device 20 and the buffer tank 30, and supplies the drain generated in the load device 20 to the buffer tank 30. A steam trap 81 that discharges the drain generated in the load device 20 and prevents the discharge of steam is disposed in the first drain supply line L2.

  The assist tank drain supply line L3 connects the buffer tank 30 and the assist tank 40, and supplies the drain accommodated in the buffer tank 30 to the assist tank 40. In the present embodiment, the upstream end of the assist tank drain supply line L <b> 3 is connected to the lower portion of the buffer tank 30. Further, downstream of the assist tank drain supply line L3 are a first assist tank drain supply line L3A that supplies drain to the first assist tank 40A and a second assist tank drain supply line that supplies drain to the second assist tank 40B. Branches to L3B. The upstream side of the portion that branches to the first assist tank drain supply line L3A and the second assist tank drain supply line L3B in the assist tank drain supply line L3 is the upstream side of the first assist tank drain supply line L3A and the second assist tank. It is constituted by a line common to the upstream side of the drain supply line L3B.

  The first assist tank drain supply line L3A connects the buffer tank 30 and the first assist tank 40A, and supplies the drain accommodated in the buffer tank 30 to the first assist tank 40A. The second assist tank drain supply line L3B connects the buffer tank 30 and the second assist tank 40B, and supplies the drain accommodated in the buffer tank 30 to the second assist tank 40B. The downstream end of the first assist tank drain supply line L3A is connected to the bottom of the first assist tank 40A, and the downstream end of the second assist tank drain supply line L3B is the second assist tank 40B. Connected to the bottom.

  The drain supply valve 71 is constituted by a motor valve and is disposed in the assist tank drain supply line L3. In the present embodiment, as the drain supply valve 71, a first drain supply valve 71A is disposed in the first assist tank drain supply line L3A, and a second drain supply valve 71B is disposed in the second assist tank drain supply line B. The first drain supply valve 71A opens and closes the first assist tank drain supply line L3A. The second drain supply valve 71B opens and closes the second assist tank drain supply line L3B. In addition, the assist tank 40 to the buffer tank 30 are provided downstream of the first drain supply valve 71A in the first assist tank drain supply line L3A and downstream of the second drain supply valve 71B in the second assist tank drain supply line L3B. Check valves 82 </ b> A and 82 </ b> B are disposed to prevent the backflow of drain into the tank.

  The assist tank steam supply line L4 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 assist tank steam supply line L4 includes, on the downstream side, the first assist tank steam supply line L4A that supplies steam to the first assist tank 40A and the second assist that supplies steam to the second assist tank 40B. Branches to the tank vapor supply line L4B. The upstream side of the portion of the assist tank steam supply line L4 that branches to the first assist tank steam supply line L4A and the second assist tank steam supply line L4B is upstream of the first assist tank steam supply line L4A and the second assist tank. It is constituted by a line common to the upstream side of the steam supply line L4B.

  The first assist tank steam supply line L4A connects the boiler 10 and the first assist tank 40A, and supplies the steam generated in the boiler 10 to the first assist tank 40A. The second assist tank steam supply line L4B connects the boiler 10 and the first assist tank 40A, and supplies steam generated in the boiler 10 to the first assist tank 40A. The downstream end of the first assist tank steam supply line L4A is connected to the upper portion of the first assist tank 40A, and the downstream end of the second assist tank steam supply line L4B is connected to the second assist tank 40B. Connected to the top of the.

  The steam supply valve 72 is configured by a motor valve, and is disposed in the assist tank steam supply line L4. In the present embodiment, as the steam supply valve 72, a first steam supply valve 72A is disposed in the first assist tank steam supply line L4A, and a second steam supply valve 72B is disposed in the second assist tank steam supply line L4B. The first steam supply valve 72A opens and closes the first assist tank steam supply line L4A. The second steam supply valve 72B opens and closes the second assist tank steam supply line L4B. Further, steam from the assist tank 40 is located downstream of the first steam supply valve 72A in the first assist tank steam supply line L4A and downstream of the second steam supply valve 72B in the second assist tank steam supply line L4B. Check valves 83A and 83B for preventing backflow are arranged.

  The second steam supply line L5 connects the steam header 12 and the buffer tank 30, and supplies the steam generated in the boiler 10 to the buffer tank 30. In the present embodiment, the upstream side of the second steam supply line L5 is connected to the upstream side of the branch portion of the assist tank steam supply line L4 between the first assist tank steam supply line L4A and the second assist tank steam supply line L4B. Has been. That is, in this embodiment, the upstream side of the assist tank steam supply line L4 and the upstream side of the second steam supply line L5 are configured by a common line. The downstream end of the second steam supply line L5 is connected to the upper portion of the buffer tank 30. A pressure regulating valve 84 for supplying steam to the buffer tank 30 at a predetermined pressure is disposed in the second steam supply line L5.

  The communication line L6 connects the assist tank 40 and the buffer tank 30 and connects the internal space of the assist tank 40 and the internal space of the buffer tank 30. In the present embodiment, the end of the communication line L6 on the buffer tank 30 side is connected to the upper portion of the buffer tank 30. The communication line L6 branches on the assist tank 40 side into a first communication line L6A connected to the upper part of the first assist tank 40A and a second communication line L6B connected to the upper part of the second assist tank 40B. doing. The upstream side of the portion of the communication line L6 that branches into the first communication line L6A and the second communication line L6B is configured by a common line with the upstream side of the first communication line L6A and the upstream side of the second communication line L6B. .

  The first communication line L6A connects the first assist tank 40A and the buffer tank 30 to communicate the internal space of the first assist tank 40A and the internal space of the buffer tank 30. The second communication line L6B connects the second assist tank 40B and the buffer tank 30, and communicates the internal space of the second assist tank 40B and the internal space of the buffer tank 30.

  The communication valve 73 is constituted by a motor valve and is disposed in the communication line L6. In the present embodiment, as the communication valve 73, the first communication valve 73A is disposed in the first communication line L6A, and the second communication valve 73B is disposed in the second communication line L6B. The first communication valve 73A opens and closes the first communication line L6A. The second communication valve 73B opens and closes the second communication line L6B. In addition, the reverse flow of steam from the buffer tank 30 to the assist tank 40 occurs on the buffer tank 30 side of the first communication valve 73A in the first communication line L6A and on the buffer tank 30 side of the second communication valve 73B in the second communication line L6B. Check valves 85A and 85B are arranged to prevent this.

  The water supply line L7 connects the assist tank 40 (the first assist tank 40A and the second assist tank 40B) and the boiler 10, and the drain accommodated in the assist tank 40 (the first assist tank 40A and the second assist tank 40B). Is supplied to the boiler 10. In the present embodiment, the water supply line L7 includes a first water supply line L7A, a second water supply line L7B, and a boiler side water supply line L7C.

The first water supply line L7A has an upstream end connected to the first assist tank 40A. The second water supply line L7B has an upstream end connected to the second assist tank 40B. The end on the downstream side of the first water supply line L7A and the end on the downstream side of the second water supply line L7B are connected and joined at the connection portion 86, and the upstream of the boiler side water supply line L7C at the connection portion 86 Connected to the end of the side. The downstream end of the boiler side water supply line L7C is connected to the boiler 10.
The boiler side water supply line L <b> 7 </ b> C branches to the same number as the plurality of can bodies 11, and ends of the branched lines are connected to the plurality of can bodies 11. The drain pump 60 mentioned above is arrange | positioned at the boiler side water supply line L7C.

  In the present embodiment, check valves 87A and 87B for preventing the backflow of water from the boiler 10 are arranged in the first water supply line L7A and the second water supply line L7B, respectively. The upstream side of the check valve 87A in the first water supply line L7A and the upstream side of the check valve 87B in the second water supply line L7B are the downstream side of the first assist tank drain supply line L3A and the second assist tank drain supply line. It is comprised by the line common with the downstream of L3B.

  The makeup water supply line L <b> 8 connects the open tank 50 and the buffer tank 30, and supplies makeup water stored in the open tank 50 to the buffer tank 30. A makeup water supply pump 88 is disposed in the makeup water supply line L8. By driving the makeup water supply pump 88, makeup water is supplied from the open tank 50 to the buffer tank 30.

  The flash vapor discharge line L9 connects the buffer tank 30 and the open tank 50, and discharges the flash vapor generated in the buffer tank 30 to the open tank 50. A pressure regulating valve 89 is disposed in the flash steam discharge line L9. When the pressure inside the buffer tank 30 exceeds a predetermined pressure, the pressure regulating valve 89 allows the flash vapor to escape to the open tank 50 side, and reduces the pressure inside the buffer tank 30.

  Based on the signal from the boiler 10, the water level detected by the first water level sensor SA, and the second water level sensor SB, the controller 9 controls the first drain supply valve 71A, the second drain supply valve 71B, and the first steam supply. Control of opening and closing of the valve 72A, the second steam supply valve 72B, the first communication valve 73A, and the second communication valve 73B is controlled. Details of control of each valve by the control unit 9 will be described later.

  In the drain collection system 1 of the present embodiment, the drain generated in the load device 20 is accommodated in the buffer tank 30 via the first drain supply line L2. The drain accommodated in the buffer tank 30 is supplied to the first assist tank 40A or the second assist tank 40B via the assist tank drain supply line L3. 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 L7.

  Here, in the present embodiment, the buffer tank 30 is disposed below the buffer tank 30, and the communication line L6 that connects the internal space of the assist tank 40 and the internal space of the buffer tank 30 is provided. Drain can be supplied from the tank 30 to the assist tank 40 without using power such as a pump.

Further, by providing the assist tank 40 with the assist tank steam supply line L4 for supplying steam, the pressure inside the assist tank 40 can be increased to substantially the same pressure as the pressure of the boiler 10. Thereby, since the water supply to the boiler 10 can be performed in a state where the power for driving the drain pump 60 is reduced, the drain recovery system 1 can be operated at low cost.
Further, since the assist tank 40 is disposed above the boiler 10, the height difference between the assist tank 40 and the boiler 10 can also be used for water supply from the assist tank 40 to the boiler 10, and the power for driving the drain pump 60 can be increased. Can be reduced.

  The assist tank 40 includes a tank main body 41 and a plate-like member 43, and the plate-like member 43 is disposed below the steam inlet 42 inside the tank main body 41. Thereby, since the steam introduced downward from the steam inlet 42 can be rectified by the plate-like member 43, the steam is uniformly distributed inside the tank body 41 without forming a biased flow inside the tank body 41. Steam can be introduced. Therefore, since the water surface of the drain accommodated in the tank body 41 is not disturbed by the introduced steam, heat exchange at the interface between the drain and the steam can be suppressed. As a result, the pressure inside the assist tank 40 can be increased in a short time. Further, since the amount of steam supplied to the assist tank 40 can be reduced, the energy saving effect can be improved.

  Further, the tank body 41 is configured in a vertically long cylindrical shape. 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 where the saturated state of water vapor should be maintained can be reduced, the pressure inside the assist tank 40 can be increased in a short time. Further, since the amount of steam supplied to the assist tank 40 can be reduced, the energy saving effect can be improved.

  Further, the upstream end portions of the assist tank steam supply line L4 and the second steam supply line L5 were connected to the steam header 12. Thereby, since the steam can be supplied to the buffer tank 30 and the assist tank 40 from the steam header 12 in which the steam generated in the plurality of cans 11 is collected, the plurality of steam tanks 30 and the assist tank 40 in the case where steam is used. The change in the pressure of each can 11 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 first embodiment will be described.
Supply of the drain to the boiler 10 in the drain recovery system 1 is mainly performed by the first drain supply valve 71A, the second drain supply valve 71B, the first steam supply valve 72A, the second steam supply valve 72B, the first communication valve 73A, And the 2nd communicating valve 73B is realizable by opening and closing in the following procedures shown in FIG.
FIG. 3 shows the first drain supply valve 71A, the second drain supply valve 71B, the first steam supply valve 72A, the second steam supply valve 72B, the first in each step when continuously supplying water to the boiler 10 by the drain recovery system 1. It is a figure which shows the open / close state of 73 A of 1st communication valves, and the 2nd communication valve 73B.

  In FIG. 3, the water level of the first assist tank 40A is full (a state where the water level is higher than the first water level described later), and the water level of the second assist tank 40B is lowered (lower than the second 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, each valve is opened and closed in the order of the 1A process, the 1B process, the 1C process and the 1D process, and the 1A process to the 1D process are repeated. Note that the drain pump 60 is continuously driven while water is supplied to the boiler 10.

In the 1A process, 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. In this state, the first drain supply valve 71A and the first communication valve 73A are closed.

  On the other hand, in the first A step, the water level detected by the second water level sensor SB is the water level indicating that the drain stored in the second assist tank 40B is low (the second assist tank 40B). The water level is lower than the first water level, which is a water level indicating a full water state. When the water level detected by the second water level sensor SB falls below the second water level, the controller 9 closes the second steam supply valve 72B and opens the second communication valve 73B and the second drain supply valve 71B. Then, by opening the second communication valve 73B, the internal space of the second assist tank 40B and the internal space of the buffer tank 30 are communicated, and the internal pressure of the second assist tank 40B and the internal space of the buffer tank 30 are communicated. The pressure is the same. Here, the buffer tank 30 is disposed above the second assist tank 40B. Accordingly, drain is supplied from the buffer tank 30 to the second assist tank 40B due to a difference in height between the buffer tank 30 and the second assist tank 40B.

  In the present embodiment, a check valve 82B is disposed in the second assist tank drain supply line L3B. Therefore, even if the second communication valve 73B and the second drain supply valve 71B are simultaneously opened, the backflow of drain from the second assist tank drain supply line L3B to the buffer tank 30 can be prevented.

In the 1B process, the supply of drain to the second assist tank 40B is completed in a state where water is supplied from the first assist tank 40A to the boiler 10, and water is supplied from the second assist tank 40B to the boiler 10. Is called. That is, water supply from the first assist tank 40A to the boiler 10 and water supply from the second assist tank 40B to the boiler 10 are performed simultaneously.
In the first B step, the first steam supply valve 72A is opened, and the first drain supply valve 71A and the first communication valve 73A are maintained in a closed state, and from the first assist tank 40A, as in the first A step. Water supply 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 1B process, when the water level of the second assist tank 40B is higher than the second water level and rises to the first water level that indicates the full water level of the second assist tank 40B, the second water level sensor It is detected that the first water level has been exceeded by SB. When it is detected by the second water level sensor SB that the first water level has been exceeded, the controller 9 opens the second steam supply valve 72B and closes the second drain supply valve 71B and the second communication valve 73B. . 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. In the first B step, water is supplied simultaneously from the first assist tank 40A and the second assist tank 40B to the boiler 10, and the water levels of the drains stored in the first assist tank 40A and the second assist tank 40B are the same level. It keeps falling while keeping the difference.

  In the first C step, the water supply from the first assist tank 40A to the boiler 10 is stopped while the water supply from the second assist tank 40B to the boiler 10 is being performed, and the buffer tank 30 is provided in the first assist tank 40A. Drain is supplied from. That is, in the 1C step, the water supply from the first assist tank 40A to the boiler 10 is stopped from the state where the water supply is simultaneously performed from the first assist tank 40A and the second assist tank 40B to the boiler 10 in the 1B step, Water is supplied to the boiler 10 only from the second assist tank 40B.

  In the first C step, the second steam supply valve 72B is opened and the second drain supply valve 71B and the second communication valve 73B are kept closed, and from the second assist tank 40B as in the first B step. Water supply to the boiler 10 is continued. And the water level of the drain accommodated in the 2nd assist tank 40B falls.

  On the other hand, in the first C step, when the water level of the first assist tank 40A is lowered to a predetermined second water level (a water level lower than the first water level), the first water level sensor SA detects that the water level has fallen below the second water level. Is done. When the first water level sensor SA detects that the water level has fallen below the second water level, the controller 9 closes the first steam supply valve 72A. Then, the supply of steam to the first assist tank 40A is stopped, and the pressure inside the first assist tank 40A decreases. Then, when the pressure difference between the pressure inside the first assist tank 40A and the pressure in the boiler 10 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. Is done.

  In the first C step, the controller 9 opens the first communication valve 73A and the first drain supply valve 71A after closing the first steam supply valve 72A or simultaneously with closing the first steam supply valve 72A. . Then, the internal space of the first assist tank 40A and the internal space of the buffer tank 30 communicate with each other, so that high-pressure steam inside the first assist tank 40A flows into the buffer tank 30, and the internal space of the first assist tank 40A. The pressure and the pressure inside the buffer tank 30 are the same. Accordingly, drain is supplied from the buffer tank 30 to the first assist tank 40A due to a difference in height between the buffer tank 30 and the first assist tank 40A.

  In the present embodiment, a check valve 82A is arranged in the first assist tank drain supply line L3A. Therefore, even if the first communication valve 73A and the first drain supply valve 71A are opened at the same time, the backflow of drain from the first assist tank drain supply line L3A to the buffer tank 30 can be prevented.

In the first D process, 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 water is supplied from the first assist tank 40A to the boiler 10. Is called. That is, water supply from the second assist tank 40B to the boiler 10 and water supply from the first assist tank 40A to the boiler 10 are performed simultaneously.
In the first step D, the second steam supply valve 72B is opened, and the second drain supply valve 71B and the second communication valve 73B are kept closed. From the second assist tank 40B, as in the step 1C. Water supply to the boiler 10 is continued. And the water level of the drain accommodated in the 2nd assist tank 40B falls.

  On the other hand, in the first step D, when the water level of the first assist tank 40A is higher than the second water level and rises to the first water level that indicates the full water level of the first assist tank 40A, the first water level sensor It is detected by SA that the first water level has been exceeded. When it is detected by the first water level sensor SA that the first water level has been exceeded, the control unit 9 opens the first steam supply valve 72A and closes the first drain supply valve 71A and the first communication valve 73A. . Then, steam is supplied to the first assist tank 40A, and the pressure inside the first assist tank 40A is increased. When 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 boiler from the first assist tank 40A is driven by the driving force of the drain pump 60. The supply of drain to 10 is started. In the first D step, water is supplied simultaneously from the first assist tank 40A and the second assist tank 40B to the boiler 10, and the water levels of the drains stored in the first assist tank 40A and the second assist tank 40B are the same level. It keeps falling while keeping the difference.

  While the water supply to the boiler 10 continues, the above-mentioned 1A process-1D process are repeated.

  According to the drain collection system 1 of 1st Embodiment demonstrated above, there exist the following effects.

(1) In the drain recovery system 1, the second water level sensor SB provided in the second assist tank 40B, the first steam supply valve 72A are opened, and the first drain supply valve 71A and the first communication valve 73A are closed. In the state where the second steam supply valve 72B is closed and the second communication valve 73B and the second drain supply valve 71B are opened, the water level of the second assist tank 40B detected by the second water level sensor SB is The control unit 9 opens the second steam supply valve 72B and closes the second drain supply valve 71B and the second communication valve 73B when the first water level is exceeded. Thereby, after water was supplied to the boiler 10 simultaneously from the first assist tank 40A and the second assist tank 40B, the drain was supplied to the boiler 10 only from the second assist tank 40B. Therefore, after the pressure inside the second assist tank 40B has increased, the drain is supplied to the boiler 10 only from the second assist tank 40B. Therefore, the time lag of the timing which starts water supply from the 2nd assist tank 40B to the boiler 10 can be reduced.

(2) When the water level of the first assist tank 40A falls below the second water level lower than the first water level, the control unit 9 closes the first steam supply valve 72A, and the first communication valve 73A and the first The drain supply valve 71A was opened. Thus, after the drain is simultaneously supplied from the first assist tank 40A and the second assist tank 40B to the boiler 10, when the water level in the first assist tank 40A falls below the second water level, the boiler from the second assist tank 40B. The drain can be supplied to the first assist tank 40 </ b> A in a state where water is supplied to 10.

(3) When the water level of the first assist tank 40A exceeds one water level, the controller 9 opens the first steam supply valve 72A and closes the first drain supply valve 71A and the first communication valve 73A. . Thereby, after water was supplied to the boiler 10 simultaneously from the first assist tank 40A and the second assist tank 40B, the drain was supplied to the boiler 10 only from the first assist tank 40A. Therefore, after the pressure inside the first assist tank 40A increases, drain is supplied to the boiler 10 only from the first assist tank 40A. Therefore, it is possible to reduce the time lag at the timing when water supply from the first assist tank 40A to the boiler 10 is started.

  Next, a drain recovery system 1A according to a second embodiment of the present invention will be described with reference to FIGS. In the description of the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  The drain recovery system 1A of the second embodiment is different from the first embodiment in that the water supply valve 74 is disposed in the water supply line L7. In 2nd Embodiment, as shown in FIG. 4, as the water supply valve 74, the 1st water supply valve 74A is arrange | positioned at the 1st water supply line L7A, and the 2nd water supply valve 74B is arrange | positioned at the 2nd water supply line L7B. The first water supply valve 74A opens and closes the first water supply line L7A. The second water supply valve 74B opens and closes the second water supply line L7B.

  Based on the signal from the boiler 10, the water level detected by the first water level sensor SA, and the second water level sensor SB, the controller 9 controls the first drain supply valve 71A, the second drain supply valve 71B, and the first steam supply. Control of opening and closing of the valve 72A, the second steam supply valve 72B, the first communication valve 73A, the second communication valve 73B, the first water supply valve 74A, and the second water supply valve 74B is performed. Details of control of each valve by the control unit 9 will be described later.

Next, a specific operation of the drain recovery system 1A of the second embodiment will be described.
Supply of the drain to the boiler 10 in the drain recovery system 1A is mainly performed by the first drain supply valve 71A, the second drain supply valve 71B, the first steam supply valve 72A, the second steam supply valve 72B, the first communication valve 73A, This can be realized by opening and closing the second communication valve 73B, the first water supply valve 74A, and the second water supply valve 74B according to the following procedure shown in FIG.
FIG. 5 shows the first drain supply valve 71A, the second drain supply valve 71B, the first steam supply valve 72A, the second steam supply valve 72B, the first in each process when the boiler 10 is continuously supplied with water by the drain recovery system 1A. It is a figure which shows the open / close state of 73 A of 1st communication valves, the 2nd communication valve 73B, the 1st water supply valve 74A, and the 2nd water supply valve 74B.

  In FIG. 5, in the state where the water level of the first assist tank 40A is full (a state where the water level is higher than the first water level) and the water level of the second assist tank 40B is lowered (a state where the water level is lower than the second water level). A case where water supply to the boiler 10 is started will be described. In this case, as shown in FIG. 5, the valves are opened and closed in the order of the 2A process, 2B process, 2C process, 2D process, 2E process, 2F process and 2G process. The second G step is repeated. Note that the drain pump 60 is continuously driven while water is supplied to the boiler 10.

In the second A step, water is supplied from the first assist tank 40A to the boiler 10, and drain is supplied to the second assist tank 40B.
In this case, as shown in FIG. 5, first, in a state where the first water supply valve 74A is opened, the first steam supply valve 72A is opened and steam is supplied to the first assist tank 40A. Then, 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 first water supply Since the valve 74A is opened, the supply of drain from the first assist tank 40A to the boiler 10 is started by the driving force of the drain pump 60. In this state, the first drain supply valve 71A and the first communication valve 73A are closed.

  On the other hand, in the second A step, the water level detected by the second water level sensor SB is lower than the second 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 second water level sensor SB falls below the second water level, the control unit 9 closes the second steam supply valve 72B and closes the second communication valve while the second water supply valve 74B is closed. 73B and the second drain supply valve 71B are opened. Then, by opening the second communication valve 73B, the internal space of the second assist tank 40B and the internal space of the buffer tank 30 are communicated, and the internal pressure of the second assist tank 40B and the internal space of the buffer tank 30 are communicated. The pressure is the same. Here, the buffer tank 30 is disposed above the second assist tank 40B. Accordingly, drain is supplied from the buffer tank 30 to the second assist tank 40B due to a difference in height between the buffer tank 30 and the second assist tank 40B.

In the second B 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 B step, the first steam supply valve 72A is opened and the first drain supply valve 71A and the first communication valve 73A are closed while the state where the first water supply valve 74A is opened is maintained. Is maintained. In this state, water supply from the first assist tank 40A to the boiler 10 is continued as in the second A step. And the water level of the drain accommodated in 40 A of 1st assist tanks falls.

  On the other hand, when the water level of the second assist tank 40B is higher than the second water level and rises to the first water level that indicates the full water level of the second assist tank 40B, the first water level is detected by the second water level sensor SB. It is detected that the value exceeds. When it is detected by the second water level sensor SB that the first water level has been exceeded, the control unit 9 maintains the state in which the second water supply valve 74B is closed, and maintains the second drain supply valve 71B and the second drain valve 71B. The communication valve 73B is closed. Thereby, the 2nd assist tank 40B will be in the standby state by which the water supply to the boiler 10 was waited.

In the second C step, steam is supplied to the inside of the second assist tank 40B in a state where water is supplied from the first assist tank 40A to the boiler 10, and water supply from the second assist tank 40B to the boiler 10 is performed. The prepared water supply is ready.
In the second C step, the first steam supply valve 72A is opened and the first drain supply valve 71A and the first communication valve 73A are closed while the state where the first water supply valve 74A is opened is maintained. Is maintained. In this state, water supply from the first assist tank 40A to the boiler 10 is continued as in the second B step. And the water level of the drain accommodated in 40 A of 1st assist tanks falls.

  On the other hand, in the second C step, the second steam supply valve 72B is opened and the steam is supplied to the second assist tank 40B in a state where the second water supply valve 74B is kept closed. Further, the state where the second drain supply valve 71B and the second communication valve 73B are closed is maintained. Thereby, the steam from the boiler 10 is supplied to the inside of the second assist tank 40B with the second water supply valve 74B closed. Moreover, since the 2nd water supply valve 74B is closed, the vapor | steam supplied to the inside of the 2nd assist tank 40B will be in the state which does not flow out downstream from the 2nd water supply valve 74B in the 2nd water supply line L7B. Thus, the second assist tank 40B is in a water supply preparation state in which the internal pressure is increased and water supply to the boiler 10 is prepared. In this water supply preparation state, the difference between the pressure inside the second assist tank 40B and the pressure of the boiler 10 is maintained in a state where it is smaller than a predetermined value (for example, 0.2 MPa).

In the 2D process, the water level of the first assist tank 40A is lowered and the 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 from the buffer tank 30 to the first assist tank 40A.
In the second D step, when the water level of the first assist tank 40A is lowered to a predetermined second water level, it is detected by the first water level sensor SA that the water level has fallen below the second water level. When the first water level sensor SA detects that the water level has fallen below the second water level, the controller 9 closes the first steam supply valve 72A. Then, the supply of steam to the first assist tank 40A is stopped, and the pressure inside the first assist tank 40A decreases. Then, when the pressure difference between the pressure inside the first assist tank 40A and the pressure in the boiler 10 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. Is done.

  In the second step D, the controller 9 opens the first communication valve 73A and the first drain supply valve 71A after closing the first steam supply valve 72A or simultaneously with closing the first steam supply valve 72A. . Then, the internal space of the first assist tank 40A and the internal space of the buffer tank 30 communicate with each other, so that high-pressure steam inside the first assist tank 40A flows into the buffer tank 30, and the internal space of the first assist tank 40A. The pressure and the pressure inside the buffer tank 30 are the same. Accordingly, drain is supplied from the buffer tank 30 to the first assist tank 40A due to a difference in height between the buffer tank 30 and the first assist tank 40A.

  In the present embodiment, a check valve 82A is arranged in the first assist tank drain supply line L3A. Therefore, even if the first communication valve 73A and the first drain supply valve 71A are opened at the same time, the backflow of drain from the first assist tank drain supply line L3A to the buffer tank 30 can be prevented.

  On the other hand, in the 2D step, when it is detected by the first water level sensor SA of the first assist tank 40A that the water level has fallen below the second water level, the control unit 9 opens the second steam supply valve 72B, The second water supply valve 74B is opened. Here, in the second C step, the second assist tank 40B is in a water supply ready state, and the difference between the pressure inside the second assist tank 40B and the pressure of the boiler 10 is from a predetermined value (for example, 0.2 MPa). Is kept small. Therefore, the supply of drain from the second assist tank 40B to the boiler 10 is started in a state where the time lag of the timing of starting water supply from the second assist tank 40B to the boiler 10 is reduced by the driving force of the drain pump 60. . In this state, the second drain supply valve 71B and the second communication valve 73B are maintained in a closed state.

  Thus, in the 2D process, the 2nd feed valve 74B was opened in the state where the pressure inside the 2nd assist tank 40B was raised. Thereby, the second water supply valve 74B is opened from a state where the difference between the pressure inside the second assist tank 40B and the pressure in the boiler 10 is smaller than a predetermined value (for example, 0.2 MPa). The time lag of the timing which starts water supply from the 2nd assist tank 40B to the boiler 10 can be reduced.

In the second E step, the supply of drain to the first assist tank 40A is completed and the first assist tank 40A is on standby while the state in which water is supplied from the second assist tank 40B to the boiler 10 is maintained. It becomes a state.
In the second E step, the second steam supply valve 72B is opened and the second drain supply valve 71B and the second communication valve 73B are closed while the state where the second water supply valve 74B is opened is maintained. Is maintained. In this state, water supply from the second assist tank 40B to the boiler 10 is continued as in the second D step. And the water level of the drain accommodated in the 2nd assist tank 40B falls.

  On the other hand, in the 2E step, when the water level of the first assist tank 40A is higher than the first water level and rises to the first water level that is the water level indicating the full water state of the first assist tank 40A, the first water level sensor It is detected by SA that the first water level has been exceeded. When it is detected by the first water level sensor SA that the first water level has been exceeded, the control unit 9 keeps the first water supply valve 74A closed and maintains the first drain supply valve 71A and the first drain valve 71A. The communication valve 73A is closed. Thereby, 40 A of 1st assist tanks will be in the standby state by which the water supply to the boiler 10 was waited.

In the second F step, steam is supplied into the first assist tank 40A in a state where water is supplied from the second assist tank 40B to the boiler 10, and water supply from the first assist tank 40A to the boiler 10 is performed. The prepared water supply is ready.
In the second F step, the second steam supply valve 72B is opened and the second drain supply valve 71B and the second communication valve 73B are closed while the state where the second water supply valve 74B is opened is maintained. Is maintained. In this state, water supply from the second assist tank 40B to the boiler 10 is continued as in the second E step. And the water level of the drain accommodated in the 2nd assist tank 40B falls.

  On the other hand, in the second F step, the first steam supply valve 72A is opened and steam is supplied to the first assist tank 40A with the first water supply valve 74A kept closed. Further, the state where the first drain supply valve 71A and the first communication valve 73A are closed is maintained. Thereby, the steam from the boiler 10 is supplied to the inside of the first assist tank 40A in a state where the first water supply valve 74A is closed. Moreover, since the first water supply valve 74A is closed, the steam supplied to the inside of the first assist tank 40A does not flow downstream from the first water supply valve 74A in the first water supply line L7A. Thus, the first assist tank 40A is in a water supply preparation state in which the internal pressure is increased and water supply to the boiler 10 is prepared. In this water supply preparation state, the difference between the pressure inside the first assist tank 40A and the pressure in the boiler 10 is maintained in a state where it is smaller than a predetermined value (for example, 0.2 MPa).

In the second G step, the water level of the second assist tank 40B is lowered, and the water supply from the second assist tank 40B to the boiler 10 is stopped. Further, water supply from the first assist tank 40A to the boiler 10 is started, and drain is supplied from the buffer tank 30 to the second assist tank 40B.
In the second G step, when the water level of the second assist tank 40B drops to a predetermined second water level, it is detected by the second water level sensor SB that the water level has fallen below the second water level. When it is detected by the second water level sensor SB that the water level has fallen below the second water level, the control unit 9 closes the second steam supply valve 72B. Then, the supply of steam to the second assist tank 40B is stopped, and the pressure inside the second assist tank 40B decreases. Then, when the pressure difference between the pressure inside the second assist tank 40B and the pressure of the boiler 10 exceeds a predetermined value (for example, 0.2 MPa), the supply of steam from the second assist tank 40B to the boiler 10 is stopped. Is done.

  In the second G step, the controller 9 opens the second communication valve 73B and the second drain supply valve 71B after closing the second steam supply valve 72B or simultaneously with closing the second steam supply valve 72B. . Then, the internal space of the second assist tank 40B and the internal space of the buffer tank 30 communicate with each other, so that the high-pressure steam inside the second assist tank 40B flows into the buffer tank 30, and the inside of the second assist tank 40B. The pressure and the pressure inside the buffer tank 30 are the same. Accordingly, drain is supplied from the buffer tank 30 to the second assist tank 40B due to a difference in height between the buffer tank 30 and the second assist tank 40B.

  In the present embodiment, a check valve 82B is disposed in the second assist tank drain supply line L3B. Therefore, even if the second communication valve 73B and the second drain supply valve 71B are simultaneously opened, the backflow of drain from the second assist tank drain supply line L3B to the buffer tank 30 can be prevented.

  On the other hand, in the second G step, when it is detected by the second water level sensor SB of the second assist tank 40B that the water level has fallen below the second water level, the control unit 9 is in a state where the first steam supply valve 72A is opened, The first water supply valve 74A is opened. Here, the first assist tank 40A is in a water supply ready state in the second F step, and the difference between the pressure inside the first assist tank 40A and the pressure of the boiler 10 is from a predetermined value (for example, 0.2 MPa). Is kept small. Therefore, the supply of drain from the first assist tank 40A to the boiler 10 is started in a state where the time lag at the timing of starting water supply from the first assist tank 40A to the boiler 10 is reduced by the driving force of the drain pump 60. . In this state, the first drain supply valve 71A and the first communication valve 73A are kept closed.

  Thus, in the 2nd G process, the 1st water supply valve 74A was opened in the state where the pressure inside the 1st assist tank 40A was raised. Thereby, the first water supply valve 74A is opened from the state where the difference between the pressure inside the first assist tank 40A and the pressure of the boiler 10 is smaller than a predetermined value (for example, 0.2 MPa). It is possible to reduce a time lag at the timing of starting water supply from the first assist tank 40A to the boiler 10.

  While the water supply to the boiler 10 continues, the 2nd A process-the 2nd G process are repeated.

According to the drain collection system 1A of the second embodiment, the following effects are obtained.
(4) The drain collection system 1A includes a first water supply valve 74A that opens and closes the first water supply line L7A and a second water supply valve 74B that opens and closes the second water supply line L7B. Thereby, before starting water supply from the 1st assist tank 40A or the 2nd assist tank 40B to the boiler 10, the 1st water supply valve 74A and the 2nd water supply are closed by closing the 1st water supply valve 74A or the 2nd water supply valve 74B. Steam can be supplied to the inside of the first assist tank 40A or the second assist tank 40B upstream of the valve 74B. Therefore, when water supply from the first assist tank 40A or the second assist tank 40B to the boiler 10 is started, the pressure inside the first assist tank 40A or the second assist tank 40B can be increased. Therefore, it is possible to reduce the time lag at the timing of starting water supply from the first assist tank 40A or the second assist tank 40B to the boiler 10.

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 assist tank steam supply line L4 and the second steam supply line L5 is connected to the steam header 12, but this is not limitative. In other words, the upstream side of the assist tank vapor supply line L4 and the second vapor supply line L5 may be connected to any one of a plurality of cans.

  Moreover, in this embodiment, although the drain collection system 1 was comprised including the 2nd steam supply line L5 and the pressure control valve 84, it is not restricted to this. That is, the drain recovery system may be configured without including the second steam supply line L5 and the pressure regulating valve 84.

DESCRIPTION OF SYMBOLS 1 Drain collection system 9 Control part 10 Boiler 20 Load apparatus 30 Buffer tank 40A 1st assist tank 40B 2nd assist tank 60 Drain pump (water supply pump)
71A 1st drain supply valve 71B 2nd drain supply valve 72A 1st steam supply valve 72B 2nd steam supply valve 73A 1st communication valve 73B 2nd communication valve 74A 1st water supply valve 74B 2nd water supply valve L2 1st drain supply line L3A First assist tank drain supply line L3B Second assist tank drain supply line L4A First assist tank steam supply line (first steam supply line)
L4B second assist tank steam supply line (second steam supply line)
L6A 1st communication line L6B 2nd communication line L7 Water supply line L7A 1st water supply line L7B 2nd water supply line L7C Boiler side water supply line SA 1st water level sensor (1st water level detection part)
SB 2nd water level sensor (2nd water level detection part)

Claims (4)

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 buffer tank in which the drain generated in the load device is stored;
A first assist tank and a second assist tank disposed below the buffer tank;
A first drain supply line for connecting the load device and the buffer tank, and supplying drain generated in the load device to the buffer tank;
A first assist tank drain supply line that connects the buffer tank and the first assist tank, and supplies the drain accommodated in the buffer tank to the first assist tank;
A first drain supply valve that opens and closes the first assist tank drain supply line;
A second assist tank drain supply line for connecting the buffer tank and the second assist tank, and supplying drain accommodated in the buffer tank to the second assist tank;
A second drain supply valve for opening and closing the second assist tank drain supply line;
A first communication line that connects the first assist tank and the buffer tank and communicates the internal space of the first assist tank and the internal space of the buffer tank;
A first communication valve for opening and closing the first communication line;
A second communication line that connects the second assist tank and the buffer tank and communicates the internal space of the second assist tank and the internal space of the buffer tank;
A second communication valve for opening and closing the second communication line;
A first steam supply line for connecting the boiler and the first assist tank, and supplying steam generated in the boiler to the first assist tank;
A first steam supply valve for opening and closing the first steam supply line;
A second steam supply line for connecting the boiler and the second assist tank, and supplying steam generated in the boiler to the second assist tank;
A second steam supply valve for opening and closing the second steam supply line;
A water supply line that connects the first assist tank and the second assist tank to the boiler, and supplies drains stored in the first assist tank and the second assist tank to the boiler;
A water supply pump disposed in the water supply line;
A first water level detection unit that is provided in the first assist tank and detects the water level of the drain accommodated in the first assist tank;
A second water level detector provided in the second assist tank for detecting the water level of the drain accommodated in the second assist tank;
Based on the water level detected by the first water level detection unit and the second water level detection unit, the first drain supply valve, the second drain supply valve, the first steam supply valve, the second steam supply valve, A control unit for controlling the first communication valve and the second communication valve,
The control unit is configured to open the first steam supply valve, close the first drain supply valve and the first communication valve, and close the second steam supply valve and the second communication valve. When the second drain supply valve is opened and the water level of the second assist tank exceeds the first water level, the second steam supply valve is opened and the second drain supply valve and the second drain supply valve are opened. A drain collection system that closes the two communication valves.   The control unit closes the first steam supply valve, the first communication valve, and the first drain when the water level of the first assist tank falls below a second water level lower than the first water level. The drain recovery system according to claim 1, wherein the supply valve is opened.   The control unit opens the first steam supply valve and closes the first drain supply valve and the first communication valve when the water level of the first assist tank exceeds the first water level. The drain recovery system described in 1. 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 buffer tank in which the drain generated in the load device is stored;
A first assist tank and a second assist tank disposed below the buffer tank;
A first drain supply line for connecting the load device and the buffer tank, and supplying drain generated in the load device to the buffer tank;
A first assist tank drain supply line that connects the buffer tank and the first assist tank, and supplies the drain accommodated in the buffer tank to the first assist tank;
A first drain supply valve that opens and closes the first assist tank drain supply line;
A second assist tank drain supply line for connecting the buffer tank and the second assist tank, and supplying drain accommodated in the buffer tank to the second assist tank;
A second drain supply valve for opening and closing the second assist tank drain supply line;
A first communication line that connects the first assist tank and the buffer tank and communicates the internal space of the first assist tank and the internal space of the buffer tank;
A first communication valve for opening and closing the first communication line;
A second communication line that connects the second assist tank and the buffer tank and communicates the internal space of the second assist tank and the internal space of the buffer tank;
A second communication valve for opening and closing the second communication line;
A first steam supply line for connecting the boiler and the first assist tank, and supplying steam generated in the boiler to the first assist tank;
A first steam supply valve for opening and closing the first steam supply line;
A second steam supply line for connecting the boiler and the second assist tank, and supplying steam generated in the boiler to the second assist tank;
A second steam supply valve for opening and closing the second steam supply line;
A boiler side water supply line connected to the boiler on the downstream side, a first water supply line connected to the first assist tank at the upstream side and connected to the boiler side water supply line on the upstream side, and an upstream side connected to the second assist tank. A water supply line having a second water supply line connected and connected downstream to the boiler side water supply line;
A first water supply valve for opening and closing the first water supply line;
A second water supply valve for opening and closing the second water supply line;
A water supply pump disposed in the boiler side water supply line;
The first drain supply valve, the second drain supply valve, the first steam supply valve, the second steam supply valve, the first communication valve, the second communication valve, the first water supply valve, and the second water supply A control unit for controlling the valve ,
The control unit controls the first water supply valve to be closed so that the first assist tank is in a water supply preparation state in a state where the first drain supply valve and the first communication valve are closed. In a state, the first steam supply valve is controlled to be opened, and in a state where the second drain supply valve and the second communication valve are closed, the second assist tank is in a water supply preparation state. A drain recovery system for controlling to open the second steam supply valve in a state in which the second water supply valve is controlled to be closed .

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