JP2017194178A - Steam superheating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a constitution capable of stably supplying superheated steam to a load machine while preventing temperature drop in increasing the number of steam superheating devices performing superheating, in a steam superheating system including the plurality of steam superheating devices.SOLUTION: A steam superheating system 1 includes a plurality of heaters 20 respectively connected to downstream sides of a plurality of branched steam supply lines 12, steam adjustment valves 14, drain lines 15, drainage discharge valves 17, a plurality of superheated steam lines 41 respectively connected to the plurality of heaters 20, a superheated steam collection line 42 to which the superheated steam lines 41 are connected, and a number control portion 60. The number control portion 60 includes a superheating control portion 62 starting superheating after opening the drainage discharge valve 17 disposed corresponding to the heater 20 for a first time t1 with respect to the heater 20 determined as the heater 20 to perform the superheating by a number setting portion 61.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steam superheating system.

  2. Description of the Related Art Conventionally, there is known a steam superheating system in which saturated steam generated by a steam generator such as a boiler is superheated by a steam superheater and superheated steam is supplied to load equipment. For example, Patent Document 1 discloses such a steam superheating system. Patent Document 1 discloses a configuration in which a steam superheater is controlled based on a parameter related to the dryness of steam generated by a steam generator, and the superheat degree of steam is controlled to a predetermined superheat degree.

JP 2014-55694 A

  In a steam superheating system, a plurality of steam superheaters may be arranged in parallel, and superheated steam supplied from these steam superheaters may be collected and supplied to load equipment. In such a steam superheating system, a necessary amount of superheated steam is supplied to the load equipment while performing unit control to change the number of operating steam superheaters in accordance with the required load of the load equipment. For example, if the amount of superheated steam to be supplied to the load equipment increases, increase the number of steam superheaters that perform superheating to increase the amount of superheated steam that can be supplied by the entire steam superheat system, and the superheated steam required for the load equipment. Supply quantity.

  However, in a steam superheating system in which a plurality of steam superheaters are arranged in parallel, if the number of steam superheaters that perform combustion during system operation is increased, the temperature of the superheated steam supplied to the load equipment may temporarily decrease. there were. Since the internal temperature of the steam superheater is low at the beginning of combustion, saturated steam is discharged from the steam superheater without being heated to a sufficient temperature, and the entire steam superheat system is supplied to load equipment. There was a risk that the temperature of the superheated steam would decrease.

  The present invention provides a configuration capable of stably supplying superheated steam to load equipment by preventing a temperature drop that occurs when the number of steam superheaters that perform superheating is increased in a steam superheat system including a plurality of steam superheaters. The purpose is to do.

  The present invention provides a steam supply line having a main steam supply line whose upstream side is connected to the steam generator, a plurality of branch steam supply lines branched from the main steam supply line, and a downstream side of the plurality of branch steam supply lines. A plurality of steam superheaters that are connected to each other and superheat saturated steam supplied from the branch steam supply line, a plurality of flow control valves that are respectively disposed in the plurality of branch steam supply lines, and an upstream side of the plurality of branches A plurality of drain lines connected to the downstream side of the flow rate adjusting valve in each of the steam supply lines, a plurality of drain discharge valves arranged in each of the plurality of drain lines, and an upstream side connected to the plurality of steam superheaters, respectively. A plurality of superheated steam lines through which the superheated steam superheated by the steam superheater flows and downstream of the plurality of superheated steam lines A superheated steam supply line having a superheated steam collecting line for collecting superheated steam that has been connected and circulated through the plurality of superheated steam lines, and a control unit that controls the plurality of steam superheaters, the control unit comprising: A number setting unit that sets a steam superheater that performs superheating according to a required load, and the flow rate adjusting valve that is arranged corresponding to a steam superheater that is not set as a steam superheater that performs superheating by the number setting unit. After opening the drain discharge valve arranged corresponding to the steam superheater for a first time for the steam superheater set in the steam control device that performs superheating by the valve control unit to be closed and the number setting unit, An overheating control part which starts overheating is related with a steam superheating system provided with.

  The steam superheating system preferably further includes a plurality of steam traps arranged in parallel with the drain discharge valve in each of the plurality of drain lines.

  Moreover, it is preferable that the said valve control part opens the said flow regulating valve, after the overheating is started by the said overheating control part.

  ADVANTAGE OF THE INVENTION According to this invention, in a steam superheating system provided with a some steam superheater, the temperature fall which arises when increasing the number of the steam superheaters which superheat can be prevented, and superheated steam can be stably supplied to load equipment.

It is the figure which showed roughly the steam superheating system which is one Embodiment of this invention. It is a block diagram which shows the structure of a number control part. It is a timing chart which shows roughly the opening-and-closing control of the fuel regulating valve and the steam regulating valve at the time of the start of combustion of a 1st embodiment. 6 is a timing chart schematically showing opening / closing control of a fuel adjustment valve and a steam adjustment valve at the start of combustion according to a second embodiment.

  Hereinafter, preferred embodiments of the steam superheating system of the present invention will be described with reference to the drawings. The steam superheating system 1 of the first embodiment is a system that superheats saturated steam supplied from a boiler as a steam generator and supplies it to load equipment. The “line” in the present specification is a general term for lines capable of flowing a fluid such as a flow path, a path, and a pipeline.

  As shown in FIG. 1, the steam superheating system 1 of this embodiment includes a plurality of heaters 20, a steam supply line 10, a fuel supply line 30, a superheated steam supply line 40, a superheated steam header 43, and a header pressure. The sensor 52, the header temperature sensor 53, and the number control part 60 as a control part are provided. Next, each structure of the steam superheating system 1 will be described.

  The heater 20 superheats saturated steam to generate superheated steam. In the steam superheat system 1 of the present embodiment, a plurality of heaters 20 are arranged in parallel. Each heater 20 is a gas-fired combustion burner type steam superheater, and the superheated steam superheated by these heaters 20 is collected and supplied to a load device (not shown).

  The configuration of the heater 20 will be described. The heater 20 of this embodiment includes a housing 25, a steam circulation pipe 26, a burner (not shown), and a heater control unit 21.

  The housing 25 accommodates a steam circulation pipe 26, a burner, and the like therein. The steam distribution pipe 26 is formed in a spiral shape inside the housing 25. The burner is disposed in an upper part of the housing 25 and in a region inside the steam circulation pipe 26 formed in a spiral shape. The burner is constituted by a pilot burner and a main burner. In the present embodiment, a pre-purge process for pre-purging the region (combustion chamber) inside the steam flow pipe 26, an ignition try process for igniting the pilot burner, a pilot-only process for burning only the pilot burner, and a main try process for igniting the main burner Etc., combustion is started (see FIG. 3). Saturated steam passing through the steam flow pipe 26 is superheated by combustion of the burner, and superheated steam is generated.

  The heater control unit 21 performs burner control and combustion stop for each heater 20 regarding ignition, combustion, and the like. The heater control unit 21 of each heater 20 of the present embodiment is electrically connected to the number control unit 60 described later. The heater control unit 21 starts combustion control of each heater 20 based on a signal from the number control unit 60. The steam control valve 14 is also opened and closed based on a signal from the number control unit 60.

  The steam supply line 10 is a supply path for supplying saturated steam to the heater 20. The steam supply line 10 of the present embodiment includes a main steam supply line 11 and a plurality of branch steam supply lines 12 branched from the main steam supply line 11.

  The main steam supply line 11 is connected to a boiler (not shown) as a steam generator. The main steam supply line 11 of this embodiment is connected to the boiler via a saturated steam header (not shown) in which saturated steam generated by the boiler gathers. Saturated steam gathered in the saturated steam header is sent to the branch steam supply line 12 branched into a plurality through the main steam supply line 11.

  The branch steam supply line 12 has an upstream end connected to the main steam supply line 11 and a downstream end connected to the upstream end of the steam flow pipe 26 of the heater 20. The branch steam supply line 12 is branched into a plurality according to the number of heaters 20. The saturated steam sent through the main steam supply line 11 is supplied to each heater 20 through the branch steam supply line 12.

  Further, the branch steam supply line 12 of the present embodiment is provided with a steam flow meter 13, a steam control valve 14, a drain line 15, a steam trap 16, and a drain discharge valve 17.

  The steam flow meter 13 is disposed in each of the branch steam supply lines 12 and measures the flow rate of the steam flowing through the branch steam supply lines 12. The measurement information of the steam flow meter 13 is transmitted to the number control unit 60 directly or via the heater control unit 21.

  The steam control valves 14 are respectively arranged on the downstream side of the steam flow meter 13 in the branch steam supply line 12. The steam control valve 14 is an electric flow control valve configured to be capable of adjusting the flow rate of steam flowing through the branch steam supply line 12.

  The drain line 15 is connected at its upstream end to the downstream side of the steam control valve 14 in the branch steam supply line 12. The downstream side of the drain line 15 branches into two.

  The steam trap 16 is disposed in each drain line 15. The drain is separated and recovered by the steam trap 16.

  A drain discharge valve 17 is disposed in parallel with the steam trap 16 in each drain line 15. The drain discharge valve 17 is configured by, for example, an electromagnetic valve that can be controlled to open and close.

  The fuel supply line 30 is a fuel gas supply path for supplying fuel gas to the heater 20. The fuel supply line 30 of the present embodiment includes a main fuel supply line 31 and a plurality of branch fuel supply lines 32 branched from the main fuel supply line 31.

  The main fuel supply line 31 has an upstream end connected to a fuel gas supply source (not shown). The fuel gas supplied from the fuel gas supply source is sent to the branched fuel supply line 32 branched into a plurality through the main fuel supply line 31.

  The branch fuel supply line 32 has an upstream end connected to the main fuel supply line 31 and a downstream end connected to the heater 20. A plurality of branch fuel supply lines 32 are branched according to the number of heaters 20. The fuel gas sent through the main fuel supply line 31 is supplied to each heater 20 through the branch fuel supply line 32.

  The branch fuel supply line 32 of this embodiment is provided with a fuel adjustment valve 33. The fuel adjustment valve 33 is an electric valve configured to be able to adjust the flow rate of the fuel gas flowing through the branch fuel supply line 32.

  The superheated steam supply line 40 is a supply path for supplying the superheated steam superheated by the heater 20 to the load device. The superheated steam supply line 40 of the present embodiment includes a plurality of superheated steam lines 41 and a superheated steam collecting line 42 to which the superheated steam lines 41 are connected.

  The upstream end of the superheated steam line 41 is connected to the downstream end of the steam flow pipe 26 of the heater 20. The downstream end of the superheated steam line 41 is connected to the superheated steam collecting line 42. The superheated steam superheated by the heater 20 is sent to the superheated steam collecting line 42 through the superheated steam line 41. The superheated steam line 41 is not provided with a check valve or the like, and the superheated steam can move in both directions.

  Moreover, the superheated steam temperature sensor 51 is provided in the superheated steam line 41 of this embodiment. The superheated steam temperature sensor 51 is disposed in each of the superheated steam lines 41 and measures the temperature of the superheated steam superheated by the heater 20. Measurement information of the superheated steam temperature sensor 51 is transmitted to the heater control unit 21.

  The downstream end of the superheated steam collecting line 42 is connected to the superheated steam header 43. Also, the superheated steam collecting line 42 is not provided with a check valve or the like, and the superheated steam can move in both directions.

  The superheated steam header 43 collects superheated steam superheated by each heater 20 through the superheated steam supply line 40 and supplies it to a load device (not shown).

  The header pressure sensor 52 measures the pressure inside the superheated steam header 43. The header temperature sensor 53 measures the temperature inside the superheated steam header 43. These pieces of measurement information are transmitted to the number control unit 60.

  Next, the number control unit 60 as a control unit of the steam superheating system 1 that controls the plurality of heaters 20 will be described. FIG. 2 is a block diagram showing the configuration of the number control unit 60. As shown in FIG. 2, the number control unit 60 controls the operation of the plurality of heaters 20. The number control unit 60 includes a number setting unit 61, an overheat control unit 62, and a valve control unit 63.

  The number setting unit 61 sets the heater 20 that performs overheating according to the required load. More specifically, the number setting unit 61 of the present embodiment calculates the necessary steam amount required by the load device based on the pressure inside the superheated steam header 43 acquired by the header pressure sensor 52, and this necessity The number of combustion target heaters 20 that perform combustion (overheating) is set based on the amount of steam. The number setting unit 61 monitors the measurement information of the header pressure sensor 52, and when the required steam amount is changed, the number setting unit 61 resets the number of target heaters 20 to be combusted according to the changed required steam amount. Further, the number setting unit 61 determines the heater 20 to be operated based on the set number.

The overheat control unit 62 controls the combustion state of the heater 20 set as a combustion target by the number setting unit 61. In the present embodiment, the overheat control unit 62 first sets the drain discharge valve 17 disposed corresponding to the heater 20 for the first time t <b> 1 with respect to the heater 20 set as the heater 20 to be heated by the number setting unit 61. Open (for example, 400 seconds). Then, after the first time t <b> 1 has elapsed, the overheat control unit 62 closes the drain discharge valve 17 and transmits a signal permitting combustion to the heater control unit 21.
The heater control unit 21 that has received a signal permitting combustion from the overheat control unit 62 starts combustion control of the heater 20. As described above, whether or not to perform the combustion control of each heater 20 is controlled by the overheat control unit 62.
The heater control unit 21 of the heater 20 that is subject to combustion control is controlled based on the signal related to the necessary steam amount required by the heater 20 received from the number control unit 60 and the measurement information of the steam flow meter 13. The opening degree of the regulating valve 14 is controlled, and the supply amount of superheated steam is controlled. Moreover, the opening degree of the fuel adjustment valve 33 is controlled based on the measurement information of the superheated steam temperature sensor 51 to control the temperature of the superheated steam.

  The valve control unit 63 transmits a signal for closing the steam control valve 14 to the heater control unit 21 of the heater 20 that is not to be combusted by the number setting unit 61. The heater control unit 21 that has received a signal for closing the steam control valve 14 from the valve control unit 63 closes the steam control valve 14 disposed in the branch steam supply line 12 connected to the heater 20. As a result, the flow path of the branch steam supply line 12 connected to the heater 20 that has not been set as a target for overheating is blocked, and saturated steam is supplied to the heater 20 that does not perform overheating (the heater 20 to be stopped from combustion). It will not be done.

  Next, the flow of saturated steam supplied to each heater 20 and the flow of superheated steam supplied from each heater 20 to the load device will be described. The steam control valve 14 connected to the heater 20 set as the combustion target is controlled to be in an open state, and saturated steam is supplied to the heater 20 through the branch steam supply line 12. In this state, the drain discharge valves 17 connected to all the heaters 20 are controlled to be closed. Thereby, the saturated steam supplied to the heater 20 is superheated by combustion of the burner in the process of passing through the steam circulation pipe 26 and is sent to the superheated steam line 41 as superheated steam. The superheated steam sent to the superheated steam line 41 is collected in the superheated steam collecting line 42 and supplied to the load device via the superheated steam header 43.

  On the other hand, since the steam control valve 14 is controlled to be in the closed state by the control signal from the valve control unit 63, the saturated steam is not supplied into the heater 20 in the heater 20 that is subject to combustion stop. As described above, since the superheated steam line 41 and the superheated steam collecting line 42 are configured so that the superheated steam can move in both directions, the superheated steam collecting line 42 is continuously discharged from the other heaters 20 to be combusted. A part of the superheated steam that has been flown backflows through the superheated steam line 41 connected to the heater 20 subject to combustion stop and flows into the heater 20 (steam circulation pipe 26) subject to combustion stop. In this way, by drawing the superheated steam into the heater 20 subject to combustion stop, the steam flow pipe 26 can be heated by the drawn superheated steam, and the temperature inside the heater 20 can be maintained at the saturation temperature or higher. It is possible. The drain generated by the superheated steam flowing into the heater 20 is separated and collected by the steam trap 16 of the drain line 15 via the branch steam supply line 12 connected to the heater 20.

  Further, by stopping the supply of the saturated steam to the heater 20 to be stopped for combustion, the saturated steam that is not overheated is not discharged to the superheated steam line 41, so the saturated steam that is not overheated is mixed with the superheated steam. Therefore, it is possible to reliably prevent the temperature drop of the superheated steam caused by this.

  Next, control of the fuel adjustment valve 33, the steam adjustment valve 14, and the drain discharge valve 17 in the heater 20 that is newly burned will be described. FIG. 3 is a timing chart schematically showing opening / closing control of the fuel adjustment valve 33 and the steam adjustment valve 14 at the start of combustion according to the first embodiment.

In this case, first, the overheat control unit 62 arranges the heater 20 set as the heater 20 to be overheated by the number setting unit 61 (that is, the heater 20 that has been newly burned) corresponding to the heater 20. The drain discharge valve 17 thus opened is opened for the first time t1. Then, after the first time t <b> 1 has elapsed, the overheat control unit 62 closes the drain discharge valve 17 and transmits a signal permitting combustion to the heater control unit 21.
The heater control unit 21 that has received a signal permitting combustion from the overheat control unit 62 starts combustion control. As described above, the heater 20 of the first embodiment performs combustion through the pre-purge process, the ignition try process, the pilot-only process, and the main try process. As shown in FIG. 3, the heater control unit 21 opens the fuel adjustment valve 33 when the pilot-only process is completed, and introduces fuel gas into the heater 20. Next, the main burner is ignited in the main try step, and combustion is started. The heater control unit 21 opens the steam control valve 14 after a predetermined time t2 (for example, 3 seconds) has elapsed from the start of combustion.

  Thus, in this embodiment, since the superheated steam is flowing backward in the steam circulation pipe 26 of the heater 20 that is not a combustion target as described above, the temperature drop of the heater 20 is prevented, and smooth The superheated steam can be raised to a predetermined temperature. Further, before starting combustion, by opening the drain discharge valve 17 for the first time t1, superheated steam flows (backflow) through the steam circulation pipe 26 and is discharged from the drain discharge valve 17. The inside of the steam flow pipe 26 can be further heated (for example, to a temperature equal to or higher than the saturation temperature). Further, since saturated steam is supplied to the steam circulation pipe 26 after the start of combustion, the saturated steam to be overheated by pre-purge is not cooled.

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

The steam superheating system 1 of this embodiment includes a plurality of heaters 20, a plurality of steam control valves 14 that adjust the amount of steam supplied to the plurality of heaters 20, and a downstream side of the plurality of steam control valves 14. A plurality of drain lines 15 through which the drain generated in the heater 20 is circulated, a plurality of drain discharge valves 17 disposed in the plurality of drain lines 15, and a plurality of overheats whose upstream sides are connected to the plurality of heaters 20, respectively. A steam line 41, a superheated steam collecting line 42 to which the superheated steam line 41 is connected, and a number control unit 60 are provided. Then, the number control unit 60 sets the number of setting units 61 for setting the heater 20 that performs overheating, and the steam control valve 14 arranged corresponding to the heater 20 that is not set as the heater 20 that performs overheating by the number setting unit 61. After opening the drain discharge valve 17 arranged corresponding to this heater 20 for the first time t1, the valve control unit 63 for closing the heater and the heater 20 set as the heater 20 for overheating by the number setting unit 61 are opened. An overheat control unit 62 that starts overheating.
As a result, the superheated steam discharged from the heater 20 to be combusted flows back into the superheated steam line 41 connected to the heater 20 to be combusted and is taken into the heater 20. A temperature drop inside the heater 20 that is a stop target is prevented. Therefore, even when the heater 20 is to be combusted, the temperature inside the heater 20 is maintained, so that the temperature of the saturated steam can be quickly raised to the predetermined temperature of the superheated steam. Further, before starting combustion, by opening the drain discharge valve 17 for the first time t1, superheated steam flows (backflow) through the steam circulation pipe 26 and is discharged from the drain discharge valve 17. The inside of the steam distribution pipe 26 can be further heated. Therefore, the temperature drop which arises when increasing the number of the heaters 20 which perform overheating can be prevented, and superheated steam can be stably supplied to load equipment.

  In addition, the steam superheating system 1 includes a steam trap 16 disposed in parallel to the drain discharge valve 17 in the drain line 15. Thus, when the drain discharge valve 17 is closed in the heater 20 in the combustion stopped state, the drain generated by the reverse flow of the superheated steam to the heater 20 is discharged from the steam trap 16, so that the drain is discharged from the heater 20. It is possible to reliably prevent the situation that accumulates inside. Further, in this case, even if a situation in which the drainage by the steam trap 16 is not suitably performed occurs, the drain discharge valve 17 is opened before starting the combustion, so that the heater 20 (steam circulation pipe 26) is opened. The accumulated drain can be discharged from the drain discharge valve 17 by superheated steam. Therefore, superheated steam can be supplied to load equipment more stably.

  Further, the valve control unit 63 performs control to open the steam control valve 14 after a predetermined time after the combustion (overheating) is started by the overheating control unit 62. Thereby, since saturated steam is supplied to the heater 20 after pre-purge, it is possible to reliably prevent the saturated steam before starting combustion from being cooled by pre-purge.

  Next, the steam superheating system of 2nd Embodiment is demonstrated. FIG. 4 is a timing chart schematically showing opening / closing control of the fuel adjustment valve 33, the steam adjustment valve 14, and the drain discharge valve 17 at the start of combustion according to the second embodiment. The steam superheating system of the second embodiment employs an oil-fired combustion burner type heater 20 as a steam superheater, and is different from the first embodiment in that the fuel to be supplied and the equipment related thereto are different. And different.

  In the second embodiment, combustion is started through a pre-purge process, a pre-ignition process, and an ignition try process. And as shown in FIG. 4, similarly to 1st Embodiment, the opening / closing control of the drain discharge valve 17 by the overheating control part 62 is performed before a pre purge process. When the pre-purge and pre-ignition (period from when ignition is started to when fuel is supplied) are completed, the fuel adjustment valve 33 is opened and oil as fuel is introduced into the heater 20 in the ignition try process. Burner combustion is started after fuel is introduced in the ignition try process. After a predetermined time t2 has elapsed from the start of combustion, the steam control valve 14 is controlled to be in the open state by the heater control unit 21. Thus, also in the steam superheating system of the second embodiment, the superheated steam flows (reverse flow) through the steam circulation pipe 26 by opening the drain discharge valve 17 for the first time t1 before starting the combustion. ) And discharged from the drain discharge valve 17, the temperature inside the steam flow pipe 26 can be raised. Further, the superheated steam can be smoothly raised to a predetermined temperature without cooling the saturated steam in the pre-purge process.

As mentioned above, although each preferred embodiment of the steam superheater of the present invention was described, the present invention is not limited to the above-mentioned embodiment, and can be changed suitably. For example, in the present embodiment, the overheat control unit 62 first sets the drain discharge valve 17 arranged in correspondence with the heater 20 to the first heater 20 set as the heater 20 to be heated by the number setting unit 61. The drain discharge valve 17 is closed after the time t1 is released, and a signal for permitting combustion is transmitted to the heater control unit 21. However, the present invention is not limited to this. That is, the overheat control unit transmits a signal permitting combustion to the heater control unit of the heater set as the heater that performs overheating by the number setting unit, and the heater control unit that has received this signal sets the drain discharge valve for the first time. The drain discharge valve may be closed after t1 is opened, and then combustion may be started.
Moreover, it can also be set as the structure which replaces with the heater 20 of a burner system and carries out overheating by another means, such as a halogen lamp. Further, in the above embodiment, control is performed to open the steam control valve 14 after a predetermined time t2 has elapsed from the start of combustion, but the control is changed to control to open the steam control valve 14 almost simultaneously with the start of combustion. You can also. In any case, since saturated steam is supplied after pre-purge, the saturated steam is not cooled by pre-purge. In addition, the heater control unit 21 can also be configured to function as the overheat control unit 62, the valve control unit 63, and the like.

1 Steam Overheating System 10 Steam Supply Line 11 Main Steam Supply Line 12 Branch Steam Supply Line 14 Steam Control Valve (Flow Control Valve)
15 Drain line 16 Steam trap 17 Drain discharge valve 20 Heater (steam superheater)
40 Superheated Steam Supply Line 41 Superheated Steam Line 42 Superheated Steam Assembly Line 60 Number Control Unit (Control Unit)
61 Number setting unit 62 Overheat control unit 63 Valve control unit t1 1st time

Claims (3)

A steam supply line having a main steam supply line whose upstream side is connected to the steam generator and a plurality of branch steam supply lines branched from the main steam supply line;
A plurality of steam superheaters connected to the downstream sides of the plurality of branch steam supply lines, respectively, for superheating saturated steam supplied from the branch steam supply lines;
A plurality of flow regulating valves disposed in each of the plurality of branch steam supply lines;
A plurality of drain lines connected to the downstream side of the flow rate regulating valve in each of the plurality of branch steam supply lines on the upstream side;
A plurality of drain discharge valves disposed in each of the plurality of drain lines;
A plurality of superheated steam lines each having an upstream side connected to the plurality of steam superheaters and through which superheated steam superheated by the steam superheater flows, and a downstream side of the plurality of superheated steam lines are connected to flow through the plurality of superheated steam lines A superheated steam supply line having a superheated steam collecting line where collected superheated steam is collected;
A controller that controls the plurality of steam superheaters,
The controller is
A unit setting unit for setting a steam superheater that performs superheating according to the required load;
A valve control unit for closing the flow rate adjusting valve disposed corresponding to the steam superheater that is not set in the steam superheater that performs superheat by the number setting unit;
For a steam superheater set as a steam superheater that performs superheat by the number setting unit, an overheat control unit that starts overheating after opening the drain discharge valve arranged corresponding to the steam superheater for a first time And a steam superheating system.   The steam superheating system according to claim 1, further comprising a plurality of steam traps arranged in parallel with the drain discharge valve in each of the plurality of drain lines.   2. The steam superheating system according to claim 1, wherein the valve control unit opens the flow rate adjusting valve after overheating is started by the overheating control unit.

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