JP2014190610A - Steam generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam generator capable of stably supplying water.SOLUTION: A steam generator 1 includes a tank part 2 having an evaporation tank 21 and a water header 22, a spray nozzle 23 arranged in an inside of the evaporation tank 21, a spray water supply line L4 for supplying water in the water header 22 to the spray nozzle 23, a spray water pump 7, a make-up water line L7 for supplying make-up water to the water header 22, a make-up water pump 8, a water level detection part 27 for detecting a water level of the water header 22, and a control part 90. The control part 90 includes a first initial control part 92 which drives the make-up water pump 8 until the water level of the water header 22 reaches a first water level when the water level of the water header 22 is determined to be less than the first water level in initial water supply, continues driving of the make-up water pump 8 for first time T1 after the water level reaches the first water level, and stops driving of the make-up water pump 8 and drives the spray water pump 7 when the first time T1 is elapsed after the water level reaches the first water level.

Description

  The present invention relates to a steam generator.

  Conventionally, boilers that boil fuel and boil water are widely used as steam generators. On the other hand, in order to be able to efficiently recover the energy of exhaust heat generated in factories and the like, a highly energy efficient steam generator that can generate steam without using fuel has been proposed (for example, , See Patent Document 1). According to the steam generator described in Patent Document 1, steam can be taken out from hot water having a relatively low temperature of about 90 ° C.

  As such a steam generator capable of taking out steam from hot water having a relatively low temperature, a shell-and-tube heat exchanger including a tank and a tube disposed so as to penetrate the inside of the tank is provided. The steam generator used is also known. If a shell and tube type heat exchanger is used, for example, the jacket cooling water (about 91 ° C.) of the gas engine is circulated through the tube as a heat source, and hot water of about 82 ° C. is sprayed on the tube inside the tank. This makes it possible to generate steam at the same time as the generator is driven by the gas engine. In this case, by forming a thin liquid film on the surface of the tube, steam can be generated even if the difference between the heat source circulating in the tube and the temperature of the sprayed water is relatively small at about 9 ° C. . Of the water sprayed on the tube, the water that has not become steam is stored in the lower part of the tank.

JP 2010-164223 A

  By the way, if the tank in the steam generator becomes large, the management cost for installation delivery, performance inspection and the like becomes large. Therefore, it is conceivable that the tank is composed of a plurality of small tanks. However, in such a configuration, it is necessary to manage the water level of each of the plurality of containers, and it is difficult to stably supply water.

  Accordingly, an object of the present invention is to provide a steam generator capable of stably supplying water even when a shell-and-tube heat exchanger is configured using a small tank.

  The present invention includes a plurality of evaporation tanks in which steam is generated, and a tank having a water header that is provided below the plurality of evaporation tanks and stores water that has not evaporated inside the plurality of evaporation tanks. And a tube extending in the horizontal direction inside the evaporating tank, in which hot water serving as a heat source circulates, and disposed above the tube inside the evaporating tank, and spraying water on the tube A spray nozzle, a spray water supply line for supplying the water stored in the water header to the spray nozzle, a spray water pump provided in the spray water supply line, and supplying makeup water to the water header Detected by a makeup water line, a makeup water pump provided in the makeup water line, a water level detection unit for detecting a water level inside the water header, and the water level detection unit. And a control unit that controls the spray water pump and the makeup water pump based on the water level, wherein the control unit is detected by the water level detection unit during initial water supply of the steam generation device. An initial water level determination unit that determines whether or not the water level is equal to or higher than the first water level, and when the initial water level determination unit determines that the water level is not equal to or higher than the first water level, The makeup water pump is driven until the water level is reached, and the makeup water pump is continuously driven for a first time after the water level reaches the first water level, so that the water level reaches the first water level. And a first initial control unit that stops driving of the makeup water pump and drives the spray water pump when the first time has elapsed.

  The control unit is configured to drive the spray water pump and drive the spray water pump when the initial water level determination unit determines that the water level is equal to or higher than the first water level. The makeup water pump is driven when the water level falls below the first water level after being driven, and the makeup water pump is driven when the water level reaches the first water level while the makeup water pump is driven. It is preferable to further include a second initial control unit that performs control for stopping the second time after the determination by the initial water level determination unit is performed.

  In addition, after the control by the first initial control unit or the second initial control unit is performed, the control unit, when the water level detected by the water level detection unit is equal to or higher than the first water level When the drive of the makeup water pump is stopped and the water level detected by the water level detection unit falls below a second water level lower than the first water level in a state where the drive of the makeup water pump is stopped, the makeup water pump is turned off. A third water level that is driven by the first output and the water level detected by the water level detection unit is higher than the second water level and lower than the first water level while the makeup water pump is driven at the first output. It is preferable to drive the make-up water pump with a second output smaller than the first output.

  According to the steam generator of the present invention, water can be stably supplied even when a shell-and-tube heat exchanger is configured using a small tank.

It is a figure which shows the outline of the steam generator which concerns on embodiment of this invention. It is a perspective view which shows the tank part (evaporation tank) in the steam generator which concerns on embodiment of this invention. It is sectional drawing of the tank part in the steam generator which concerns on embodiment of this invention. It is a figure which shows the relationship between the water level of a water header in case there are few retained water of the water header at the time of initial water supply, and progress of time. It is a figure which shows the relationship between the water level of a water header and progress of time when there is much water of the water header at the time of initial stage water supply.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of a steam generator according to an embodiment of the present invention.
The steam generator 1 of the present embodiment generates steam using a relatively low-temperature heat source such as exhaust heat of jacket cooling water of a gas engine. The steam generated in the steam generator 1 is compressed and sent to, for example, an exhaust heat recovery boiler.

  The steam generator 1 includes a tank part 2, a steam outlet part 24 provided in the tank part 2, a tube 25 and a spray nozzle 23 arranged in the tank part 2, a hot water supply line L1, and a hot water discharge line. L2, steam outlet line L3, spray water supply line L4, spray water pump 7 provided in spray water supply line L4, continuous blow line L5, concentration blow line L6, makeup water line L7, and bypass line L8, the heat exchanger 3, and the control part 90 are provided. “Line” is a general term for lines capable of flowing fluid such as flow paths, paths, and pipelines.

The tank unit 2 includes a plurality of evaporation tanks 21, one water header 22, and a water level gauge 27 as a water level detection unit. Each of the plurality of evaporation tanks 21 generates steam.
The water header 22 is disposed below the plurality of evaporation tanks 21. The water header 22 stores water that has not become steam inside the evaporation tank 21.

The water level indicator 27 detects the water level stored in the water header 22. More specifically, the water level gauge 27 includes a cylindrical main body 271 and a plurality of electrode bars 272 disposed inside the main body 271. The main body 271 is disposed at the same height as the water header 22. The lower end portion of the main body 271 is connected to the lower end portion of the water header 22 via a spray water supply line L4 described later. Moreover, the upper end part of the main body 271 is connected to the vapor | steam derivation | leading-out line L3 mentioned later. Thereby, the water level inside the water level gauge 27 (main body 271) becomes equal to the water level inside the water header 22.
In the present embodiment, the water level meter 27 includes four electrode rods 272 that can detect water levels at four different heights (HH, H, L, LL).

The vapor outlet 24 is provided on each of the plurality of evaporation tanks 21. The steam deriving unit 24 derives the steam generated in the evaporation tank 21.
The tube 25 extends in the horizontal direction inside the evaporation tank 21. Inside the tube 25, hot water serving as a heat source flows.

The spray nozzle 23 is disposed above the tube 25 inside the evaporation tank 21. The spray nozzle 23 sprays water toward the tube 25.
Specific configurations of the tank unit 2, the vapor outlet unit 24, the spray nozzle 23, and the tube 25 will be described later.

  The hot water supply line L <b> 1 supplies hot water serving as a heat source to the tube 25. The upstream side of the hot water supply line L1 is connected to a gas engine or the like that supplies hot water serving as a heat source. The downstream side of the hot water supply line L <b> 1 is connected to one end of the tube 25.

  The hot water discharge line L2 circulates inside the tube 25 and discharges the hot water used as a heat source to the outside. The upstream side of the hot water discharge line L <b> 2 is connected to the other end of the tube 25.

  The steam lead line L3 leads the steam generated inside the evaporation tank 21. The upstream side of the steam outlet line L3 is connected to the steam outlet 24. The downstream side of the steam outlet line L3 is connected to an ejector, a steam compressor, etc. (not shown).

The spray water supply line L4 connects the water header 22 and the spray nozzle 23, and supplies the water stored in the water header 22 to the spray nozzle 23 as spray water. A spray water pump 7 is disposed in the spray water supply line L4.
The spray water pump 7 pumps water stored in the water header 22 to the spray nozzle 23.

  The continuous blow line L5 and the concentrated blow line L6 branch from the spray water supply line L4. The continuous blow line L5 and the concentrated blow line L6 drain a part of the water stored in the water header 22. A valve 5 and a valve 6 are arranged in the continuous blow line L5 and the concentration blow line L6, respectively.

The makeup water line L7 connects the water header 22 to a storage tank or the like that stores water. The makeup water line L7 supplies makeup water to the water header 22. A makeup water pump 8 and a check valve 9 are arranged in the makeup water line L7.
The makeup water pump 8 pressurizes water supplied from a storage tank or the like and supplies it to the inside of the water header 22. The check valve 9 blocks the flow of water to the upstream side of the make-up water line L7 and allows supply of make-up water to the water header 22 through the make-up water line L7 when a water pressure higher than a predetermined pressure is received. To do.

  The bypass line L8 branches from each of the hot water supply line L1 and the hot water discharge line L2, and connects them. A valve 4 that is a three-way valve is disposed at a branch point from the hot water supply line L1 to the bypass line L8. By switching the valve 4, the supplied hot water can be discharged via the bypass line L 8 and the hot water discharge line L 2 without flowing through the tube 25 inside the tank unit 2.

  The heat exchanger 3 performs heat exchange between the hot water flowing through the hot water discharge line L2 and the water flowing through the makeup water line L7.

  The controller 90 controls the operation of the steam generator 1. For example, the control unit 90 controls the spray water pump 7 and the makeup water pump 8 based on the water level detected by the water level gauge 27, and performs water supply control of the steam generator 1. Details of control of the steam generator 1 by the controller 90 will be described later.

Next, the structure of the tank part 2, the vapor | steam derivation | leading-out part 24, the tube 25, and the spray nozzle 23 is demonstrated, referring FIG.2 and FIG.3.
FIG. 2 is a perspective view showing the tank unit 2 of the present embodiment. FIG. 3A shows the front surface of the evaporation tank 21 by cutting the evaporation tank 21 of FIG. 2 at a surface that is perpendicular to the depth direction LD and passes through a portion where the evaporation tank 21 and the spray water supply line L4 are connected. It is sectional drawing (sectional drawing of one evaporation tank 21) observed from the direction (X direction). FIG. 3B shows that the evaporation tank 21 is cut at a center portion in the width direction WD of the evaporation tank 21 and perpendicular to the width direction WD of the evaporation tank 21, and the side surface direction (Y direction) of the evaporation tank 21 It is sectional drawing observed from.

In the present embodiment, the tank unit 2 includes four evaporation tanks 21 and one water header 22.
As shown in FIGS. 2 and 3, the evaporating tank 21 has a length (height) H1 in the height direction HD and a length (width) W1 in the width direction WD from the length (depth) D1 in the depth direction LD. Is also formed in a short rectangular parallelepiped shape. The plurality of evaporation tanks 21 are connected in the width direction WD.
The water header 22 is disposed below the central region of the evaporation tank 21 in the depth direction LD. In the present embodiment, the water header 22 is formed in a cylindrical shape extending across the width direction WD of the plurality of evaporation tanks 21.
The evaporation tank 21 and the water header 22 are connected via a plurality of pipes 26. More specifically, the upper ends of the plurality of pipes 26 are respectively connected to the lower surfaces of the plurality of evaporation tanks 21. The lower ends of the plurality of pipes 26 are connected to the upper part of the circumferential surface of the water header 22.

  The vapor outlet 24 is provided in the central region in the width direction WD of the evaporation tank 21 and in the central region in the depth direction LD of the evaporation tank 21.

  The tubes 25 extend in the depth direction LD of the evaporation tank 21, are arranged in the width direction WD of the evaporation tank 21, and are further arranged in the height direction HD of the evaporation tank 21. Further, the interval W2 between the tubes 25 arranged at the center portion in the width direction WD of the evaporation tank 21 is narrower than the interval W3 between the tubes 25 arranged at the side portions in the width direction WD of the evaporation tank 21. That is, the number of tubes 25 arranged in the central portion of the evaporation tank 21 in the width direction WD is larger than the number of tubes 25 arranged in the side portions of the evaporation tank 21 in the width direction WD.

  The tube 25 present in the lower half of the evaporation tank 21 in the height direction HD is connected to the hot water supply line L1, and the tube 25 of the tube 25 present in the upper half of the evaporation tank 21 in the height direction HD is Connected to the hot water discharge line L2. The tube 25 existing in the lower half of the evaporation tank 21 in the height direction HD and the tube 25 existing in the upper half of the evaporation tank 21 in the height direction HD are connected to the inner side of the evaporation tank 21 in the depth direction LD. The hot water supplied from the hot water supply line L1 circulates through the tube 25 present in the lower half of the evaporating tank 21 in the height direction HD and then turns back to circulate through the tube 25 present in the upper half of the evaporating tank 21 in the height direction HD. And is discharged by the hot water discharge line L2.

  A plurality of spray nozzles 23 are arranged in the center region in the width direction WD of the evaporation tank 21 with a predetermined interval in the depth direction LD of the evaporation tank 21. In the present embodiment, two spray nozzles 23 are arranged on the back side and the near side of the steam outlet 24. The spray angle of the spray nozzle 23 is wide and close to 180 °.

The steam generator 1 of this embodiment operates as follows.
First, hot water of about 90 ° C., for example, serving as a heat source from a gas engine or the like is supplied to the tube 25 through the hot water supply line L1. The hot water supplied to the tube 25 flows through the tube 25 on the lower side in the height direction HD of the tank unit 2, and then flows through the tube 25 on the upper side in the height direction HD of the evaporation tank 21.
On the other hand, spray water is sprayed from the spray nozzle 23 toward the tube 25 inside the evaporation tank 21. Further, the inside of the evaporation tank 21 is maintained at a negative pressure (for example, -0.043 MPaG). Thereby, the hot water which distribute | circulates the tube 25 is deprived of heat with spray water, falls to about 85 degreeC, and is discharged | emitted through the warm water discharge line L2.

  In addition, a thin liquid film is formed on the surface of the tube 25 through which warm water flows by spraying water at about 80 ° C. from the spray nozzle 23. Thus, in a state where the negative pressure is maintained, a thin liquid film is formed on the surface of the tube 25, so that the temperature difference between the hot water flowing through the tube 25 and the water sprayed by the spray nozzle 23 is increased. Even when it is relatively small (for example, about 9 ° C.), steam can be generated efficiently.

The steam generated inside the evaporation tank 21 is led out from the steam lead-out unit 24 and supplied to an ejector, a steam compressor, and the like through the steam lead-out line L3.
Water that has not become steam inside the evaporation tank 21 is stored in the water header 22. The water stored in the water header 22 is pumped up to the spray nozzle 23 by the spray water pump 7 through the spray water supply line L4 and sprayed onto the tube 25 again.

  The continuous blow line L5 and the concentrated blow line L6 drain the water stored in the water header 22. The continuous blow line L5 always discharges a fixed amount of water by opening the valve 5, or discharges a fixed amount of water every fixed time. The concentration blow line L6 monitors the concentration value of chloride ions etc. of the water stored in the tank unit 2, and when the value exceeds a certain standard, the valve 6 is opened and a certain amount of water is discharged. .

  When the amount of water circulating between the spray water supply line L4 and the tank unit 2 is reduced, make-up water is supplied to the water header 22 from the make-up water line L7. The water replenished by the makeup water line L7 is about 20 ° C. The water replenished by the replenishing water line L7 exchanges heat with the hot water flowing through the warm water discharge line L2 by the heat exchanger 3. The water supplied by the makeup water line L7 is heated to, for example, about 40 ° C. by exchanging heat with the warm water flowing through the warm water discharge line L2.

  In the steam generator 1 of the present embodiment described above, at the start of operation of the steam generator (at the time of initial water supply), water supply may be insufficient even if the water level of the water header 22 is high. That is, when the operation of the steam generator 1 is stopped, all the water inside the evaporation tank 21 is discharged to the water header 22, and there is a case where no water exists inside the evaporation tank 21. When the operation of the steam generator 1 is started in such a state, a part of the water sent to the evaporation tank 21 by the spray water pump 7 remains inside the evaporation tank 21 as a buffer. Therefore, even if the water level of the water header 22 is high and the amount of water is considered to be sufficient in a normal operation state, the water supply may be insufficient at the initial water supply at the start of operation.

  Therefore, in the present embodiment, the water supply control of the makeup water to the water header 22 by the control unit 90 is performed when the operation of the steam generator 1 is started and when a predetermined time elapses after the operation is started. By changing the operation state of the generator 1 during the steady operation in which the operation state is stable, the water supply control in the steam generator 1 including the plurality of evaporation tanks 21 and the water header 22 is stabilized.

  More specifically, the control unit 90 includes an initial water level determination unit 91, a first initial control unit 92, and a spray water pump drive unit as a configuration for performing water supply control at the start of operation, that is, at the time of initial water supply. 93 and a second initial control unit 94.

  When the operation of the steam generator 1 is started (that is, when the initial water supply is started when the operation switch of the steam generator 1 is changed from OFF to ON), the initial water level determination unit 91 is It is determined whether the detected water level is equal to or higher than the first water level. In the present embodiment, the initial water level determination unit 91 determines whether or not the water level detected by the water level meter 27 is equal to or higher than HH when the initial water supply of the steam generator 1 is started.

  When the initial water level determination unit 91 determines that the water level of the water header 22 is not equal to or higher than the first water level, the first initial control unit 92 turns the makeup water pump 8 on until the water level of the water header 22 reaches the first water level. Drive. In addition, the first initial control unit 92 continues to drive the makeup water pump for the first time T1 after the water level of the water header 22 reaches the first water level. Then, when the first time T1 has elapsed since the water level of the water header 22 reached the first water level, the first initial control unit 92 stops driving the makeup water pump 8 and drives the spray water pump 7. .

  In the present embodiment, the first initial control unit 92 determines that the initial water level determination unit 91 determines that the water level of the water header 22 is not equal to or higher than the first water level (HH), that is, the amount of water retained in the water header 22 is small. The makeup water pump 8 is driven at the first output (high output). The first initial control unit 92 further drives the makeup water pump 8 with the first output for a first time T1 (for example, 40 seconds) after the water level of the water header 22 reaches HH. Then, when the first time T1 elapses after the water level of the water header 22 reaches HH, the first initial control unit 92 stops driving the makeup water pump 8 and drives the spray water pump 7.

  Thereby, as shown in FIG. 4, when the water level inside the water header 22 is low (less than HH) at the start of operation, the first level is maintained even after the water level of the water header 22 rises to the first water level. During the time T1, water supply to the water header 22 is continued. Therefore, since the water level of the water header 22 at the time of initial water supply can be supplied until the water level becomes higher than the first water level, stable water supply can be performed even at the time of initial water supply where water supply is likely to be insufficient compared to the normal time.

  On the other hand, when the initial water level determination unit 91 determines that the water level of the water header 22 is equal to or higher than the first water level, the water supply control is performed by the spray water pump drive unit 93 and the second initial control unit 94.

The spray water pump drive unit 93 drives the spray water pump 7 when the initial water level determination unit 91 determines that the water level of the water header 22 is equal to or higher than the first water level.
In addition, the second initial control unit 94 drives the makeup water pump 8 when the water level of the water header 22 falls below the first water level after the spray water pump 7 is driven, and in the state where the makeup water pump is driven, When the water level of the header 22 reaches the first water level, the control for stopping the driving of the makeup water pump 8 is performed for the second time T2 after the determination by the initial water level determination unit 91 is performed.

  In the present embodiment, the spray water pump drive unit 93 drives the spray water pump 7 when the initial water level determination unit 91 determines that the water level of the water header 22 is equal to or higher than the first water level (HH). Then, the second initial control unit 94 starts the water header 22 for a second time T2 (for example, 40 seconds) after the initial water level determination unit 91 determines that the water level of the water header 22 is equal to or higher than the first water level. When the water level falls below the first water level (HH), the makeup water pump 8 is driven, and when the water level of the water header 22 reaches the first water level (HH), the makeup water pump 8 is stopped.

  Thus, as shown in FIG. 5, at the time of initial water supply, even if the water level inside the water header is high (first water level HH or higher), the predetermined time (second time T2) is reached. During this time, water supply to the water header 22 is performed based on this high water level. Therefore, water can be stably supplied even during initial water supply in which water supply is likely to be insufficient compared to normal time.

  Note that the control unit 90 determines the water level detected by the water level gauge 27 after the control by the first initial control unit 92 or the second initial control unit 94, that is, during steady operation after the initial water supply is completed. When it is above the first water level, the drive of the makeup water pump 8 is stopped. Further, when the water level detected by the water level gauge 27 falls below the second water level lower than the first water level with the driving of the makeup water pump 8 stopped, the makeup water pump 8 is driven with the first output. Then, when the makeup water pump 8 is driven at the first output and the water level detected by the water level gauge 27 reaches a third water level that is higher than the second water level and lower than the first water level, the makeup water pump 8. Are driven with a second output smaller than the first output.

  In the present embodiment, after the initial water supply is completed, the control unit 90 stops driving the makeup water pump 8 when the water level detected by the water level gauge 27 is equal to or higher than the first water level (HH). Further, when the water level of the water header 22 falls below the second water level (L) with the driving of the makeup water pump stopped, the makeup water pump 8 is driven at a high output as the first output. When the water level of the water header 22 reaches the third water level (H) while the makeup water pump 8 is driven at a high output, the makeup water pump 8 is driven at a low output that is the second output. (See FIGS. 4 and 5).

  Thereby, after the initial water supply is completed, the water level of the water header 22 can be controlled by the normal water level control, so that the steam generator 1 can be operated without excessively supplying water during the steady operation.

The preferred embodiment of the steam generator 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 first time T1 and the second time T2 are both 40 seconds, but the present invention is not limited to this. That is, the first time and the second time may be set to different times.

  Moreover, in this embodiment, although the water level detection part was comprised with the water surface meter 27 provided with the main body 271 and the several electrode stick | rod 272, it is not restricted to this. That is, the water level detection unit may be configured by a pressure sensor or the like.

DESCRIPTION OF SYMBOLS 1 Steam generator 2 Tank part 7 Spray water pump 8 Makeup water pump 21 Evaporation tank 22 Water header 23 Spray nozzle 25 Tube 27 Water level gauge (water level detection part)
90 Control Unit 91 Initial Water Level Determination Unit 92 First Initial Control Unit 93 Spray Water Pump Drive Unit 94 Second Initial Control Unit L4 Spray Water Supply Line L7 Makeup Water Line

Claims (3)

A plurality of evaporation tanks in which steam is generated, and a tank unit having a water header provided below the plurality of evaporation tanks and storing water that has not evaporated inside the plurality of evaporation tanks;
A tube that extends in the horizontal direction inside the evaporation tank and in which hot water that serves as a heat source circulates,
A spray nozzle that is disposed above the tube inside the evaporation tank and sprays water on the tube;
A spray water supply line for supplying water stored in the water header to the spray nozzle;
A spray water pump provided in the spray water supply line;
A makeup water line for supplying makeup water to the water header;
A makeup water pump provided in the makeup water line;
A water level detection unit for detecting the water level inside the water header;
A control unit that controls the spray water pump and the makeup water pump based on the water level detected by the water level detection unit, and a steam generator comprising:
The controller is
An initial water level determination unit that determines whether or not the water level detected by the water level detection unit at the time of initial water supply of the steam generator is equal to or higher than a first water level;
When the initial water level determination unit determines that the water level is not equal to or higher than the first water level, the makeup water pump is driven until the water level reaches the first water level, and the water level reaches the first water level. The supply water pump is continuously driven for a first time after the arrival, and when the first time has elapsed since the water level reached the first water level, the drive of the makeup water pump is stopped to And a first initial control unit for driving the spray water pump. The controller is
When the initial water level determination unit determines that the water level is equal to or higher than the first water level, a spray water pump drive unit that drives the spray water pump;
When the water level falls below the first water level after the spray water pump is driven, the make-up water pump is driven, and when the water level reaches the first water level while the make-up water pump is driven The steam generator according to claim 1, further comprising: a second initial control unit that performs control for stopping the driving of the makeup water pump for a second time after the determination by the initial water level determination unit is performed. After the control by the first initial control unit or the second initial control unit, the control unit is configured to supply the makeup water when the water level detected by the water level detection unit is equal to or higher than the first water level. Stop the pump,
When the water level detected by the water level detection unit falls below a second water level lower than the first water level while driving of the makeup water pump is stopped, the makeup water pump is driven with a first output,
The replenishment when the water level detected by the water level detector reaches a third water level that is higher than the second water level and lower than the first water level while the makeup water pump is driven at the first output. The steam generator according to claim 1 or 2, wherein the water pump is driven with a second output smaller than the first output.

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