JP2020165614A - Water supply control device - Google Patents

Abstract

To provide a water supply control device capable of suppressing generation of cavitation in a drain supply pump.SOLUTION: A water supply control device 200 for controlling the water supply of a boiler system 1 includes: a boiler 11; a drain tank 20 for recovering drain without opening to the atmosphere; a drain supply line L3 for supplying the drain recovered in the drain tank 20 to the boiler 11; a drain supply pump 31 for delivering drain from the drain tank 20 and a flow rate adjustment mechanism 32 capable of setting a state amount for determining the flowability of the drain which are installed in the drain supply line L3; and a flow rate detection part 33 for detecting the flow rate of the drain. It also includes a flow rate control part 220 for performing feed back control of the state amount of the flow rate adjustment mechanism 32 so that the flow rate detected by the flow rate detection part 33 becomes closer to the set flow rate target value. The flow rate control part 220 starts the feed back control after matching the state amount of the flow rate adjustment mechanism 32 with the set initial value, in the case where the flow rate target value is changed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a water supply control device.

A boiler system is used in which steam is generated by a boiler and supplied to a load device, and the drain generated by condensing the steam in the load device is collected in a drain tank and resupplied to the boiler. In order to improve the thermal efficiency in such a boiler system, for example, as described in Patent Document 1, a boiler system has been proposed in which a drain tank is in a pressurized state, and high-temperature and high-pressure drain is collected and re-supplied to the boiler device. Has been done.

The boiler system described in Patent Document 1 has a drain supply pump and a drain flow rate control valve, and supplies drains contained in a drain tank to a boiler device having a plurality of boilers, and fresh water for the boiler device. It is equipped with a new water supply line to supply. The boiler system described in Patent Document 1 gives priority to the supply of drain from the drain supply line, and supplies new water from the new water supply line when the drain supply from the drain supply line is insufficient. It is provided with a control device having two operation modes, one is a water supply mode and the other is a second water supply mode in which water is supplied only from a new water supply line.

Japanese Unexamined Patent Publication No. 2017-146074

In a boiler that controls the water level as described in Patent Document 1, the combustion amount is set according to the steam consumption of the load device, and the flow rate of the water supply may be adjusted according to the combustion amount. In this case, a flow rate sensor is provided in the drain supply line, and the opening degree of the drain flow rate control valve is feedback-controlled so that the detected value of the flow rate sensor becomes a target value determined according to the amount of combustion.

In a boiler system having such a configuration, when the second water supply mode is switched to the first water supply mode, the target value of the flow rate of the drain supplied to the boiler increases stepwise. In this case, the drain flow rate may overshoot and become temporarily excessive. When the required drain flow rate is relatively large, such as when the steam consumption of the load equipment is large, switching from the second water supply mode to the first water supply mode causes the drain flow rate to become excessively large, resulting in a drain supply pump. May cause cavitation. Once the drain supply pump causes cavitation, the flow rate of the drain decreases, so that the opening degree of the drain flow rate control valve is further increased by the feedback control, and the cavitation may not be eliminated.

Therefore, an object of the present invention is to provide a water supply control device capable of suppressing the occurrence of cavitation in the drain supply pump.

The water supply control device according to the present invention includes a boiler that generates steam and supplies it to a load device, a drain tank that collects drain generated by condensation of steam in the load device without opening it to the atmosphere, and the drain tank. A drain supply line that supplies the drain collected to the boiler, a drain supply pump that is arranged in the drain supply line and sends out the drain from the drain tank, and a drain supply pump that is arranged in the drain supply line and of the drain. A water supply control device that controls the water supply of a boiler system including a flow rate adjusting mechanism capable of setting a state amount that determines the ease of flow and a flow rate detecting unit that detects the flow rate of the drain, and is detected by the flow rate detecting unit. A flow rate control unit that feedback-controls the state amount of the flow rate adjusting mechanism so that the set flow rate approaches the set flow rate target value is provided, and the flow rate control unit provides the flow rate when the flow rate target value is changed. The feedback control is started after adjusting the state amount of the adjusting mechanism to the set initial value.

In the water supply control device according to the present invention, the flow rate control unit may determine the initial value according to the operating pressure of the boiler when the flow rate target value is changed.

In the water supply control device according to the present invention, the flow rate control unit may set the initial value according to the set combustion amount of the boiler when the flow rate target value is changed.

In the water supply control device according to the present invention, the flow rate control unit does not supply the drain to the boiler from the drain supply line, but supplies make-up water from the make-up water supply line that supplies make-up water to the boiler. When the drain is supplied from the drain supply line and the state is switched to a state in which the make-up water is not supplied from the make-up water supply line, the state amount of the flow rate adjusting mechanism is adjusted to the initial value and then the feedback control is performed. May be started.

According to the present invention, it is possible to provide a water supply control device capable of suppressing the occurrence of cavitation in the drain supply pump.

It is a figure which shows the structure of the boiler system which includes the water supply control device of 1st Embodiment of this invention. It is a figure which shows the structure of the boiler system which includes the water supply control device of 2nd Embodiment of this invention.

Hereinafter, preferred embodiments of the water supply control device of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a boiler system 1 including a water supply control device 200 according to a first embodiment of the present invention.

The boiler system 1 includes a boiler device 10, a drain tank 20, an open tank 30, a number control device 100, and a water supply control device 200 according to an embodiment of the present invention. The boiler system 1 supplies steam to a load device 40 that generates steam by the boiler device 10 and consumes the steam (condenses the steam by using thermal energy).

In addition, the boiler system 1 connects these devices and includes a plurality of lines through which steam or water flows. Specifically, the boiler system 1 includes a steam supply line L1, a drain recovery line L2, a drain supply line L3, a pressurized steam line L4, a flush steam line L5, a tank make-up water supply line L6, and a boiler make-up water supply line L7. To be equipped.

Further, the boiler system 1 includes a steam trap 21 and a check valve 22 provided in the drain recovery line L2, a drain supply pump 31 arranged in the drain supply line L3, a drain flow control valve 32, and a drain flow sensor 33. A supply pressure adjusting valve 41 provided in the pressurized steam line L4, a discharge pressure adjusting valve 51 provided in the flush steam line L5, a tank water supply pump 61 provided in the tank make-up water supply line L6, and a tank water supply amount adjusting valve 62. , A make-up water supply pump 71 provided in the boiler make-up water supply line L7 is provided.

The boiler device 10 includes a plurality of boilers 11, a steam header 12 in which steam generated by the plurality of boilers 11 is collected, and a connecting pipe 13 for connecting the boiler 11 and the steam header 12.

The plurality of boilers 11 generate steam by heating the drain supplied from the drain supply line L3 or the make-up water supplied from the boiler make-up water supply line L7. Each boiler 11 can be configured by, for example, a once-through boiler or the like. The plurality of boilers 11 operate in cooperation to generate an amount of steam substantially equal to the amount of steam consumed by the load device 40.

Each of the boilers 11 has a local control unit 15 that controls the combustion state according to an instruction from the number control device 100. The local control unit 15 instructs the water supply control device 200 of the flow rate target value, which is the amount of water supply required by each boiler 11. Specifically, the local control unit 15 instructs the water supply control device 200 to set the flow rate target value to zero and stop the water supply when the water level in the boiler 11 exceeds a predetermined upper limit, and the boiler When the water level in 11 becomes equal to or lower than a predetermined lower limit, on / off control for instructing the water supply control device 200 to set the flow rate target value to a predetermined value can be performed. In this case, the flow rate target value instructed by the local control unit 15 when the water level in the boiler 11 is equal to or lower than a predetermined lower limit is preferably set to a larger value as the combustion amount is larger. Further, the local control unit 15 instructs, for example, when the drain supply line L3 is provided with an economizer that heats the water supply by the combustion exhaust gas of the boiler 11, when the water level in the boiler 11 exceeds a predetermined upper limit. The target value may not be completely zero, but may be the minimum value that can prevent the water supply from boiling in the economizer. As a result, when the water level in the boiler 11 exceeds a predetermined upper limit, the minimum flow rate of water can be continued, and boiling of the water supply in the economizer can be prevented.

The steam header 12 stores the steam generated by the boiler 11 and supplies it to the load device 40 to suppress the pressure fluctuation of the steam. The connecting pipe 13 collects the steam generated by the boiler 11 in the steam header 12. The steam header 12 has a pressure sensor 16 that detects the pressure of the steam inside.

The drain tank 20 is composed of a pressure vessel having pressure resistance. The drain tank 20 recovers the drain generated by condensing the steam generated by the boiler 11 in the load device 40 in a high temperature and high pressure state.

The drain tank 20 is provided with a drain water level gauge 25 for detecting the water level of the drain inside. The drain water level gauge 25 can be configured to include a tubular main body and a plurality of electrode rods arranged inside the main body and detecting the water level in the main body.

The open tank 30 is open to the atmosphere. The open tank 30 stores the make-up water supplied to the boiler 11. Further, the flush steam generated from the drain in the drain tank 20 is supplied to the open tank 30.

The steam supply line L1 connects the steam header 12 and the load device 40, and supplies the steam generated by the plurality of boilers 11 to the load device 40.

The drain recovery line L2 collects the drain generated by the condensation of steam in the load device 40 in the drain tank 20 without releasing it to the atmosphere. In the drain recovery line L2, the steam trap 21 allows only the drain to pass through and prevents steam from flowing out to the drain tank 20. The check valve 22 prevents the drain from flowing back.

The drain supply line L3 supplies the drain collected in the drain tank 20 to the boiler device 10. The upstream end of the drain supply line L3 is connected to the lower part of the drain tank 20. The downstream side of the drain supply line L3 is branched into a plurality of portions so that its end is connected to each of the plurality of boilers 11.

The drain supply pump 31 is arranged on the upstream side of the branch portion in the drain supply line L3, boosts the drain supplied from the drain tank 20, and sends it to a plurality of boilers 11. The drain supply pump 31 is started and stopped by the water supply control device 200 described later.

The drain flow rate adjusting valve 32 is a flow rate adjusting mechanism capable of setting an opening degree, which is a state amount that determines the ease of flow of drain supplied to the corresponding boiler 11. Each drain flow rate control valve 32 can be configured by, for example, a motor valve or the like. Each drain flow rate control valve 32 is individually controlled by the water supply control device 200 so that an appropriate amount of drain can be supplied according to the operating state of the corresponding boiler 11, as will be described in detail later.

The drain flow rate sensor 33 is a flow rate detection unit that detects the flow rate of the drain supplied to the corresponding boiler 11. Each drain flow rate sensor 33 can be configured by any flow meter such as a mass flow rate sensor or an orifice flow rate sensor.

The pressurized steam line L4 supplies steam directly from the boiler device 10 to the drain tank 20. The supply pressure adjusting valve 41 arranged in the pressurized steam line L4 keeps the pressure of the steam supplied to the drain tank 20 at a set pressure. As a result, the pressure of the drain tank 20 is prevented from becoming lower than the set pressure.

The flash steam line L5 connects the upper space of the drain tank 20 and the open tank 30. In the flash steam line L5, when the pressure of the drain tank 20 becomes higher than the set pressure, the discharge pressure adjusting valve 51 opens and the steam in the drain tank 20 is discharged to the open tank 30. As a result, the pressure of the drain tank 20 is prevented from becoming higher than the set pressure.

The tank make-up water supply line L6 connects the open tank 30 and the drain tank 20, and supplies the water stored in the open tank 30 to the drain tank 20. The tank water supply pump 61 arranged in the tank make-up water supply line L6 boosts the water stored in the open tank 30 and sends it to a plurality of drain tanks 20. The tank water supply pump 61 is started and stopped by the water supply control device 200 so that the water level of the drain tank 20 detected by the drain water level gauge 25 can be maintained within a certain range. Further, the tank water supply amount adjusting valve 62 arranged in the tank make-up water supply line L6 limits the flow rate of the make-up water according to the pressure of the drain tank 20 and applies back pressure to the tank water supply pump 61. Specifically, when the pressure of the drain tank 20 is lower than the set pressure, the opening degree is reduced so that the flow rate of the make-up water becomes smaller, thereby preventing cavitation in the tank water supply pump 61.

The boiler make-up water supply line L7 supplies the make-up water stored in the open tank 30 to the boiler device 10. The upstream end of the boiler make-up water supply line L7 is connected to the lower part of the open tank 30. The downstream side of the boiler make-up water supply line L7 is branched into a plurality of portions so that its end is connected to each of the plurality of boilers 11. When the water supply from the drain supply line L3 is insufficient, the make-up water is supplied to the boiler device 10 through the boiler make-up water supply line L7.

A plurality of make-up water supply pumps 71 are provided on the downstream side of the boiler make-up water supply line L7 so as to correspond to each boiler 11.

The make-up water supply pump 71 boosts the make-up water supplied from the open tank 30 and sends it to the corresponding boiler 11. The make-up water supply pump 71 is speed-adjustable and can be configured by, for example, an electric pump driven by an inverter (frequency converter) 72. The output frequency of the inverter 72 is controlled by the water supply control device 200.

The number control device 100 determines the combustion state (including operation / stop and combustion amount during operation) of each boiler 11 according to the amount of steam used by the load device 40. Specifically, the number control device 100 calculates the amount of steam generated in order to keep the detected value of the pressure sensor 16 of the steam header 12 substantially constant, and determines the number of operating units and the amount of combustion of the boiler 11. To do.

The number control device 100 can be realized by introducing an appropriate program into the number control device 100, for example, a computer device having a CPU, a memory, or the like.

The water supply control device 200 can be realized by introducing an appropriate program into a computer device having, for example, a CPU, a memory, or the like. Further, the water supply control device 200 may be integrally configured with the number control device 100 and the local control unit 15.

The water supply control device 200 controls the water supply from the drain tank 20 and the open tank 30 to the boiler device 10. The water supply control device 200 includes a water supply selection unit 210 that selects either one or both of water supply by the drain supply line L3 and water supply by the boiler make-up water supply line L7, and drain to the boiler device 10 using the drain supply line L3. The drain flow rate control unit 220 for controlling the supply flow rate of the boiler and the make-up water flow rate control unit 230 for controlling the supply flow rate of the make-up water to the boiler device 10 using the boiler make-up water supply line L7 are provided. In the water supply control device 200, the water supply selection unit 210, the drain flow rate control unit 220, and the make-up water flow rate control unit 230 are functionally distinct, and even if they cannot be clearly distinguished in the physical configuration and the program configuration. Good.

The water supply selection unit 210 supplies water to the boiler 11 by selecting water supply from the drain supply line L3 and water supply from the boiler make-up water supply line L7.

When water supply from the drain supply line L3 is selected by the water supply selection unit 210, the drain flow rate control unit 220 adjusts the drain flow rate so that the flow rate detected by the drain flow rate sensor 33 approaches the set flow rate target value. The opening degree of the valve 32 is feedback controlled. Further, the drain flow rate control unit 220 presets the opening degree of each drain flow rate control valve 32 when the water supply amount instructed by the local control unit 15, and by extension, the drain flow rate target value determined by the water supply amount is changed. Feedback control is started after adjusting to the initial value.

When the drain flow rate target value is changed, the drain flow rate control unit 220 starts the feedback control after setting the opening degree of the drain flow rate control valve 32 to an opening degree that matches the initial value set according to the operating conditions. , The deviation of the detected value of the drain flow rate sensor 33 from the drain flow rate target value at the time of starting the feedback control can be reduced. The drain flow rate control unit 220 confirms the feedback of the opening degree information from the drain flow rate control valve 32, confirms that the opening degree of the drain flow rate control valve 32 is equal to the initial value, and then starts the feedback control. Alternatively, the feedback control may be started when the time required for the drain flow rate control valve 32 to operate has elapsed after the signal indicating the initial value is output to the drain flow rate control valve 32.

That is, in the boiler system 1, once cavitation occurs in the drain supply pump 31, the flow rate of the drain becomes very small, so that the opening degree of the drain flow rate adjusting valve 32 becomes larger, and the cavitation may not be eliminated. However, since the drain flow rate control unit 220 starts the feedback control after adjusting the opening degree of the drain flow rate control valve 32 to a preset initial value, the flow rate of the drain supply pump 31 overshoots at the start of the feedback control. It is possible to prevent the occurrence of cavitation due to temporary excess. As a result, the boiler system 1 can prevent the occurrence of cavitation in the drain supply pump 31 and allow each boiler 11 to operate appropriately.

The initial value of the opening degree of each drain flow rate control valve 32 may always be a constant value, but is set to a value set according to the operating pressure (steam pressure) of the corresponding boiler 11 by a predetermined method. It is preferable to do so. Specifically, it is preferable to increase the opening degree of the drain flow rate control valve 32 as the operating pressure of the boiler 11 increases. By setting the initial value of the opening degree of the drain flow rate control valve 32 according to the operating pressure of the boiler 11 acting as the back pressure on the drain supply pump 31, the overshoot of the flow rate can be suppressed more reliably. , Cavitation of the drain supply pump 31 can be prevented more reliably. The initial value of the opening degree of each drain flow rate control valve 32 may be set as a function of the operating pressure of the boiler 11, and is set by referring to the correspondence table that defines the values corresponding to the classification of the operating pressure of the boiler 11. You may.

Further, the initial value of the opening degree of each drain flow rate control valve 32 may be a value preset according to the set combustion amount of the corresponding boiler 11. Specifically, it is preferable to increase the opening degree of the drain flow rate control valve 32 as the combustion amount of the boiler 11 increases. By setting the initial value of the opening degree of the drain flow rate control valve 32 according to the set combustion amount of the boiler 11, it is possible to supply the boiler 11 with a flow rate close to a stable state from the start of feedback control. .. Therefore, even if the local control unit 15 changes the flow rate target value by normal control immediately after the start of feedback control, the flow rate due to the deviation of the actual drain flow rate from the changed drain flow rate target value becomes excessive. Overshoot can be suppressed and cavitation of the drain supply pump 31 can be prevented.

The initial value of the opening degree of each drain flow rate control valve 32 may be set according to only one of the operating pressure and the set combustion amount of the boiler 11, but it depends on both the operating pressure and the set combustion amount of the boiler 11. It is preferable to set it. In this case, the initial value of the opening degree of each drain flow rate control valve 32 may be set as a function (two-variable function) of the operating pressure of the boiler 11 and the set combustion amount, but the classification and setting of the operating pressure of the boiler 11 It may be set by referring to a two-dimensional correspondence table in which values corresponding to the amount of combustion are defined.

The drain flow rate control unit 220 supplies drain from the drain supply line L3 to the boiler 11 from the state where the drain is not supplied to the boiler 11 from the drain supply line L3 but is supplied to the boiler 11 from the boiler make-up water supply line L7. When the state is switched from the make-up water supply line L7 to the state where the make-up water is not supplied, it is preferable to set the opening degree of the drain flow rate control valve 32 to the initial value and then start the feedback control. When the drain flow rate target value of the drain supply line L3 changes in a step shape with a relatively large step, cavitation of the drain supply pump 31 is particularly likely to occur. By setting the initial value, cavitation of the drain supply pump 31 can be effectively prevented.

The make-up water flow rate control unit 230 controls the supply of make-up water from the boiler make-up water supply line L7 to each boiler 11 when the water supply from the boiler make-up water supply line L7 is selected by the water supply selection unit 210.

As described above, in the boiler system 1, the drain flow rate control unit 220 of the water supply control device 200 adjusts the opening degree of the drain flow rate control valve 32 to a preset initial value when the drain flow rate target value is changed. Since the feedback control is started from, the deviation of the detected value of the drain flow rate sensor 33 from the drain flow rate target value at the time of starting the feedback control is reduced, overshoot in the feedback control is suppressed, and the cavitation of the drain supply pump 31 is performed. Can be prevented.

Subsequently, FIG. 2 shows the configuration of the boiler system 1A including the water supply control device 200A according to the second embodiment of the present invention. The boiler system 1 includes a boiler device 10, a drain tank 20, an open tank 30, a number control device 100, and a water supply control device 200A according to an embodiment of the present invention. The boiler system 1A supplies steam to the load device 40 that generates steam by the boiler device 10 and consumes the steam. Further, the boiler system 1A includes a steam supply line L1, a drain recovery line L2, a drain supply line L3A, a pressurized steam line L4, a flush steam line L5, a tank make-up water supply line L6, and a boiler make-up water supply line L7. Further, the boiler system 1A includes a steam trap 21 and a check valve 22 provided on the drain recovery line L2, a plurality of drain supply pumps 31A and a drain flow sensor 33 arranged on the drain supply line L3A, and a pressurized steam line L4. The supply pressure adjusting valve 41 provided in the above, the discharge pressure adjusting valve 51 provided in the flush steam line L5, the tank water supply pump 61 and the tank water supply amount adjusting valve 62 provided in the tank make-up water supply line L6, and the boiler make-up water supply. A plurality of make-up water supply pumps 71 provided on the line L7 are provided. In the boiler system 1A of FIG. 2, the same components as those of the boiler system of FIG. 1 are designated by the same reference numerals, and duplicate description will be omitted.

The drain supply line L3A supplies the drain collected in the drain tank 20 to the boiler device 10. The upstream end of the drain supply line L3A is connected to the lower part of the drain tank 20. The downstream side of the drain supply line L3 is branched into a plurality of portions so that its end is connected to each of the plurality of boilers 11. The drain supply pump 31A and the drain flow rate sensor 33 are arranged on the downstream side of the branch portion of the drain supply line L3, corresponding to the respective boilers 11.

The drain supply pump 31A is speed-adjustable and can be configured by, for example, an electric pump driven by an inverter (frequency converter) 36 or the like. The output frequency of the inverter 34 in the drain supply pump 31A is a state quantity that determines the ease of drain flow. That is, the inverter 34 is a flow rate adjusting mechanism that is arranged on the drain supply line L3A and can set the output frequency, which is a state quantity that determines the ease of drain flow.

The drain flow rate control unit 220A feedback-controls the speed (output frequency of the inverter 34) of the corresponding drain supply pump 31A so that the flow rate detected by the drain flow rate sensor 33 approaches the set flow rate target value. Further, the drain flow rate control unit 220 adjusts the speed of each drain supply pump 31A to a preset initial value when the drain flow rate target value determined by the water supply amount instructed by the local control unit 15 is changed. Feedback control is started from. That is, the drain flow rate control unit 220A of the water supply control device 200A in the boiler system 1A of FIG. 2 controls the control target of the drain flow rate control valve 32 of the drain flow rate control unit 220 of the water supply control device 200 of the boiler system 1 of FIG. The speed of the drain supply pump 31A is changed from the opening degree, and the control content thereof can be the same.

In the boiler system 1A of FIG. 2, the drain flow rate control unit 220A of the water supply control device 200A adjusts the speed of the drain supply pump 31A to a preset initial value when the drain flow rate target value is changed, and then performs feedback control. Since it starts, the deviation of the detected value of the drain flow rate sensor 33 from the drain flow rate target value at the time when the feedback control is started is reduced, overshoot in the feedback control is suppressed, and cavitation of the drain supply pump 31A is prevented. Can be done.

Although the preferred embodiments of the water supply control device of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be appropriately modified.

For example, in the first embodiment and the second embodiment, the boiler systems 1 and 1A are configured to include a boiler device 10 having three boilers 11, but the water supply control device of the present invention is one or two. Alternatively, it can be applied to a boiler system including a boiler device having four or more boilers.

Further, the pressurized steam line L4, the flush steam line L5, and the tank make-up water supply line L6 in the first embodiment have arbitrary configurations and can be omitted.

In the above-described embodiment, the flow rate target value is zero or the minimum flow rate when the water level of the boiler 11 is equal to or higher than a predetermined upper limit, and a predetermined value when the water level of the boiler 11 is equal to or lower than a predetermined lower limit. Although it is set to one of the values, the flow rate target value may be continuously changed so as to keep the water level of the boiler 11 constant, for example, by feedback control based on the deviation between the set water level and the actual water level.

In the above-described embodiment, the water supply selection unit 210 selects either the drain water supply from the drain supply line L3 or the make-up water supply from the boiler make-up water supply line L7, but the water supply selection unit 210 selects the drain water. The drain water from the supply line L3 and the make-up water from the boiler make-up water supply line L7 may be supplied at the same time. In this case, the water supply selection unit 210 sets the amount of water supplied to each boiler 11 instructed by the local control unit 15 to the target value (drain flow rate target value) of the drain flow rate of the drain supply line L3 and the boiler make-up water supply line L7. It can be configured to be distributed to the target value of the make-up water flow rate (make-up water flow rate target value).

In the above-described embodiment, the boiler make-up water supply line L7 is provided with the make-up water supply pump 71 whose speed can be adjusted, but like the drain supply line L3, from the branch portion in the boiler make-up water supply line L7. A make-up water supply pump may be arranged on the upstream side and the flow rate may be controlled by a flow rate control valve.

1,1A Boiler system 10 Boiler device 11 Boiler 20 Drain tank 30 Open tank 31,31A Drain supply pump 32 Drain flow control valve (flow control mechanism)
33 Drain flow rate sensor (flow rate detector)
34 Inverter (flow control mechanism)
40 Load equipment 200, 200A Water supply control device 210 Water supply selection unit 220, 220A Drain flow rate control unit 230 Makeup water flow rate control unit L1 Steam supply line L2 Drain recovery line L3, L3A Drain supply line L7 Boiler make-up water supply line

Claims (4)

A boiler that generates steam and supplies it to load equipment,
A drain tank that collects the drain generated by the condensation of steam in the load equipment without opening it to the atmosphere.
A drain supply line that supplies the drain collected in the drain tank to the boiler, and
A drain supply pump arranged on the drain supply line and sending out the drain from the drain tank,
A flow rate adjusting mechanism that is arranged on the drain supply line and can set a state amount that determines the ease of flow of the drain.
A flow rate detection unit that detects the flow rate of the drain,
A water supply control device that controls the water supply of a boiler system equipped with
A flow rate control unit that feedback-controls the state amount of the flow rate adjustment mechanism so that the flow rate detected by the flow rate detection unit approaches the set flow rate target value is provided.
The flow rate control unit is a water supply control device that starts the feedback control after adjusting the state amount of the flow rate adjusting mechanism to a set initial value when the flow rate target value is changed. The water supply control device according to claim 1, wherein the flow rate control unit determines the initial value according to the operating pressure of the boiler when the flow rate target value is changed. The water supply control device according to claim 1 or 2, wherein the flow rate control unit determines the initial value according to the set combustion amount of the boiler when the flow rate target value is changed. The flow rate control unit does not supply the drain from the drain supply line to the boiler, but supplies the drain from the drain supply line from a state in which the make-up water is supplied from the make-up water supply line that supplies the make-up water to the boiler. The feedback control is started after adjusting the state amount of the flow rate adjusting mechanism to the initial value when the water is supplied and the state is switched to the state in which the make-up water is not supplied from the make-up water supply line. The water supply control device according to any one.

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