JP2022123455A - Power generation plant, and control method and modification method therefor - Google Patents

Abstract

To provide a power generation plant that can realize a FCB function with a simple structure.SOLUTION: A power generation plant comprises a boiler, a high-pressure turbine 111 to be driven by steam generated by the boiler, reheaters 105 and 106 for superheating the steam discharged from the high-pressure turbine 111 again, an intermediate-pressure turbine 112 to be driven by the steam superheated again by the reheaters 105 and 106, a bypass system SB for supplying the steam generated by the boiler to the reheaters 105 and 106 by bypassing the high-pressure turbine 111, and an adjustment system SC for discharging the steam superheated again by the reheaters 105 and 106 to the outside of the system on an upstream side of the intermediate-pressure turbine 112.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a power plant and its control method and modification method.

In a power plant, when an accident occurs in the power system, a fast cutback (FCB) operation may be performed in which the power plant is not stopped and the load is rapidly lowered to the on-site load to continue operation (for example, patent documents 1).

JP-A-8-121112

In Japan, power plants often do not have FCB functionality due to the high reliability of the transmission system. However, during large-scale natural disasters, there is a risk that the power system will malfunction. In addition, efforts are being made in Japan to build national resilience so that infrastructure facilities can be quickly restored even in the event of a large-scale natural disaster, and the importance of FCB functions in power plants is also recognized.

In addition, as the introduction of renewable energy is promoted, power plants are expected to play a role in adjusting the power supply and demand balance. If the power plant has the FCB function, flexible output adjustment becomes possible.

Thus, the importance of the FCB function in power plants is increasing. However, the configuration may become complicated due to the FCB function, and simplification of the configuration is desired. If the configuration is simplified, the FCB function can be added not only to newly installed power plants but also to existing power plants by remodeling. In the case of remodeling, the remodeling cost for a 600 MW class plant, for example, is expected to be on the order of 10 billion yen, so simplification of remodeling is particularly important.

The present disclosure has been made in view of such circumstances, and an object thereof is to provide a power plant capable of realizing the FCB function with a simple configuration, a control method thereof, and a modification method thereof.

A first aspect of the present disclosure includes a boiler, a first turbine driven by steam generated by the boiler, a reheater for reheating steam discharged from the first turbine, and the reheater. a second turbine driven by the resuperheated steam; a bypass system that bypasses the first turbine and supplies the steam generated by the boiler to the reheater; and a regulation system that discharges the steam generated from the second turbine to the outside of the system on the upstream side of the second turbine.

A second aspect of the present disclosure is a boiler, a first turbine driven by steam generated by the boiler, a reheater for reheating the steam discharged from the first turbine, and the reheater. a second turbine driven by resuperheated steam, the method comprising supplying steam produced in the boiler to the reheater bypassing the first turbine; and discharging the steam re-superheated by the reheater to the outside of the system on the upstream side of the second turbine.

A third aspect of the present disclosure is a boiler, a first turbine driven by steam generated by the boiler, a reheater for reheating the steam discharged from the first turbine, and the reheater. A method for modifying a power plant comprising a second turbine driven by resuperheated steam and a turbine bypass system for supplying steam generated in the boiler to a condenser bypassing the first turbine. providing a bypass system for supplying the steam generated by the boiler to the reheater while bypassing the first turbine; and supplying the steam resuperheated by the reheater upstream of the second turbine. a step of providing a control system for discharging to the outside of the system at the side.

According to the present disclosure, it is possible to achieve the FCB function with a simple configuration.

1 is a schematic configuration diagram representing a coal-fired boiler according to a first embodiment of the present disclosure; FIG. 1 is a schematic diagram representing a heat exchanger provided in a coal-fired boiler according to a first embodiment of the present disclosure; FIG. 1 is a diagram showing a specific configuration example of a power plant for FCB according to a first embodiment of the present disclosure; FIG. It is a figure showing an example of hardware constitutions of a control device concerning a 1st embodiment of this indication. FIG. 5 is a diagram showing state changes when FCB operation is performed according to the first embodiment of the present disclosure; FIG. 4 is a diagram showing flow balance during in-house islanding operation in the power plant according to the first embodiment of the present disclosure; FIG. 4 is a diagram showing an example of modification of the power plant according to the first embodiment of the present disclosure; FIG. It is a figure which shows the structure of the power generation plant of a reference example. FIG. 10 is a diagram showing a specific configuration example of a power plant according to a second embodiment of the present disclosure; FIG. FIG. 9 is a diagram showing state changes when FCB operation is performed according to the second embodiment of the present disclosure; FIG. 7 is a diagram showing flow balance during in-house islanding operation in a power plant according to a second embodiment of the present disclosure; FIG. 5 is a diagram showing an example of modification of a power plant according to a second embodiment of the present disclosure; FIG. FIG. 5 is a diagram showing a configuration example of a power plant according to a modification of the second embodiment of the present disclosure; FIG. 5 is a diagram showing a configuration example of a power plant according to a modification of the second embodiment of the present disclosure; FIG. 5 is a diagram showing a configuration example of a power plant according to a modification of the second embodiment of the present disclosure; FIG. 10 is a diagram illustrating a required amount of spray water according to the second embodiment of the present disclosure; FIG.

[First embodiment]
A first embodiment of a power plant, its control method, and modification method according to the present disclosure will be described below with reference to the drawings.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be noted that the present invention is not limited by this embodiment, and when there are a plurality of embodiments, the present invention includes a combination of each embodiment. In the following description, "up" and "up" indicate the upper side in the vertical direction, and "down" and "lower side" indicate the lower side in the vertical direction.

FIG. 1 is a schematic diagram showing the coal-fired boiler of this embodiment.

The coal-fired boiler 10 of the present embodiment uses pulverized coal obtained by pulverizing coal (carbon-containing solid fuel) as a pulverized fuel, burns the pulverized fuel with a burner, and heats the heat generated by this combustion with water supply and steam. It is a coal-fired (pulverized coal-fired) boiler capable of generating superheated steam by

In this embodiment, a coal-fired boiler 10 has a furnace 11, a combustion device 12, and a combustion gas passage 13, as shown in FIG. The furnace 11 has a hollow rectangular shape and is installed along the vertical direction. The furnace wall 101 constituting the furnace 11 is composed of a plurality of heat transfer tubes and fins connecting them, and heat generated by combustion of the pulverized fuel is heat-exchanged with water and steam flowing inside the heat transfer tubes, It suppresses the temperature rise of the furnace wall.

The combustion device 12 is provided on the lower side of the furnace wall that constitutes the furnace 11 . In this embodiment, the combustion device 12 has a plurality of burners (eg 21, 22, 23, 24, 25) mounted on the furnace wall. For example, the burners 21, 22, 23, 24, and 25 are arranged at equal intervals along the circumferential direction of the furnace 11 as one set, and a plurality of stages (for example, five stages in FIG. 1) are arranged along the vertical direction. are placed. However, the shape of the furnace, the number of burners in one stage, the number of stages, the arrangement, etc. are not limited to this embodiment.

Burners 21 , 22 , 23 , 24 , 25 are connected to pulverizers (mills) 31 , 32 , 33 , 34 , 35 via pulverized coal supply pipes 26 , 27 , 28 , 29 , 30 . The pulverizers 31, 32, 33, 34, and 35 have, for example, a pulverizing table (not shown) rotatably supported in a pulverizer housing, and a plurality of pulverizing rollers (not shown) above the pulverizing table. is supported so as to be rotatable in conjunction with the rotation of the grinding table. When coal is put between a plurality of crushing rollers and a crushing table, it is crushed and conveyed to a classifier (not shown) in the crusher housing by a carrier gas (primary air, oxidizing gas). , pulverized fuel classified within a predetermined particle size range can be supplied to the burners 21 , 22 , 23 , 24 , 25 from the pulverized coal supply pipes 26 , 27 , 28 , 29 , 30 .

Further, the furnace 11 is provided with a wind box 36 at the mounting position of the burners 21, 22, 23, 24, 25, and one end of an air duct (airway) 37 is connected to the wind box 36. As shown in FIG. The air duct 37 is provided with a forced draft fan (FDF) 38 at the other end.

The combustion gas passage 13 is connected to the upper portion of the furnace 11 in the vertical direction, as shown in FIG. The combustion gas passage 13 is provided with superheaters 102, 103, 104, reheaters 105, 106, and an economizer 107 as heat exchangers for recovering the heat of the combustion gas. Heat is exchanged between the combustion gas and feed water or steam flowing through each heat exchanger.

As shown in FIG. 1, the combustion gas passage 13 is connected to the downstream side thereof with a flue 14 through which the combustion gas that has undergone heat exchange is discharged. An air heater (air preheater) 42 is provided between the flue 14 and the air duct 37 , and heat exchange is performed between the air flowing through the air duct 37 and the combustion gas flowing through the flue 14 . The combustion air supplied to 22, 23, 24, 25 can be heated.

Further, the flue 14 is provided with a denitrification device 43 at a position upstream of the air heater 42 . The denitrification device 43 supplies a reducing agent such as ammonia or urea water, which has a function of reducing nitrogen oxides, into the flue 14, and causes a reaction between the nitrogen oxides in the combustion gas to which the reducing agent is supplied and the reducing agent. is accelerated by the catalytic action of the denitration catalyst installed in the denitration device 43, thereby removing and reducing nitrogen oxides in the combustion gas.
The gas duct 41 connected to the flue 14 is provided with a dust collector 44 such as an electric dust collector, an induced draft fan (IDF) 45, a desulfurization device 46, etc., at a position downstream of the air heater 42. A chimney 50 is provided at the end.

On the other hand, when the plurality of pulverizers 31, 32, 33, 34, 35 are driven, the pulverized fuel produced is fed into the pulverized coal supply pipes 26, 27, 28, 29, 30 together with the carrier gas (primary air, oxidizing gas). is supplied to the burners 21, 22, 23, 24, 25 through. Also, by exchanging heat with the exhaust gas discharged from the flue 14 by the air heater 42, the heated combustion air (secondary air, oxidizing gas) is supplied from the air duct 37 through the wind box 36 to the burner 21, 22, 23, 24, 25. The burners 21, 22, 23, 24, and 25 blow into the furnace 11 a pulverized fuel mixture in which pulverized fuel and carrier gas are mixed, and also blow combustion air into the furnace 11. At this time, the pulverized fuel mixture is ignited. By doing so, a flame can be formed. A flame is generated in the lower part of the furnace 11 , and high-temperature combustion gas rises inside the furnace 11 and is discharged to the combustion gas passage 13 . Air is used as the oxidizing gas in this embodiment. It may have a higher or lower oxygen ratio than air, and can be used by optimizing the fuel flow rate.

Further, the furnace 11 is provided with an additional air port 39 above the mounting positions of the burners 21, 22, 23, 24 and 25. As shown in FIG. An end of an additional air duct 40 branched from the air duct 37 is connected to the additional air port 39 . Therefore, the combustion air (secondary air, oxidizing gas) sent by the forced draft fan 38 is supplied from the air duct 37 to the wind box 36, from which the burners 21, 22, 23, 24, 25 are supplied. , and additional air for combustion delivered by the forced draft fan 38 can be supplied to the additional air port 39 through an additional air duct 40 .

In the lower region A of the furnace 11, the pulverized fuel mixture and combustion air (secondary air, oxidizing gas) are combusted to generate flame. The inside of the furnace 11 is maintained in a reducing atmosphere by setting the amount of air supplied to be less than the theoretical amount of air with respect to the amount of pulverized coal supplied. That is, nitrogen oxides (NOx) generated by combustion of pulverized coal are reduced in the region B of the furnace 11, and then additional air for combustion (additional air) is additionally supplied from the additional air port 39, thereby reducing pulverized coal. Oxidative combustion is completed, and the amount of NOx generated by the combustion of pulverized coal is reduced.

After that, as shown in FIG. 1, the combustion gas is transferred to the second superheater 103, the third superheater 104, and the first superheater 102 (hereinafter sometimes simply referred to as superheaters) arranged in the combustion gas passage 13. ), the second reheater 106, the first reheater 105 (hereinafter sometimes simply referred to as a reheater), and the economizer 107. After that, nitrogen oxides are reduced and removed by the denitrification device 43. After the particulate matter is removed by the dust collector 44 and the sulfur oxides are removed by the desulfurization device 46, the dust is discharged from the stack 50 into the atmosphere. Note that the heat exchangers do not necessarily have to be arranged in the order described above with respect to the combustion gas flow.

Next, the superheaters 102, 103, 104, the reheaters 105, 106, and the economizer 107 provided in the combustion gas passage 13 as heat exchangers will be described in detail. FIG. 2 is a schematic diagram showing a heat exchanger provided in the coal-fired boiler 10. As shown in FIG.
It should be noted that FIG. 1 does not precisely show the position of each heat exchanger (superheaters 102, 103, 104, reheaters 105, 106, economizer 107) in the combustion gas passage 13. The arrangement order of the exchangers relative to the combustion gas flow is not limited to that shown in FIG.

As shown in FIG. 2, the power plant 1 of the present embodiment includes heat exchangers (superheaters 102, 103, 104, reheaters 105, 106, economizer 107) provided in the coal-fired boiler 10, A steam turbine 110 that is rotationally driven by the steam generated by the coal-fired boiler 10 and a generator 115 that is connected to the steam turbine 110 and that generates power by the rotation of the steam turbine 110 is provided.

A steam turbine 110 that is rotationally driven by the steam generated in the coal-fired boiler 10 includes, for example, a high-pressure turbine 111, an intermediate-pressure turbine 112, and a low-pressure turbine 113. , and then into the low pressure turbine 113 . A condenser 114 is connected to the low-pressure turbine 113, and the steam that rotationally drives the low-pressure turbine 113 is cooled by cooling water (eg, seawater) in the condenser 114 to become condensed water. Condenser 114 is connected to economizer 107 via water supply line L1. The water supply line L1 is provided with, for example, a condensate pump (CP) 121, a low-pressure water supply heater 122, a water supply pump (BFP) 123, and a high-pressure water supply heater . A part of the steam that drives the steam turbines 111, 112, and 113 is extracted to the low-pressure feed water heater 122 and the high-pressure feed water heater 124, and is supplied to the high-pressure feed water heater 124 and the low-pressure feed water heater 122 via a steam extraction line (not shown). Feedwater supplied as a heat source and supplied to the economizer 107 is heated.

For example, a case where the coal-fired boiler 10 is a once-through boiler will be described. An economizer 107 is connected to each evaporator tube of the furnace wall 101 . The feed water heated by the economizer 107 is heated by radiation from the flame in the furnace 11 when passing through the evaporating pipes forming the furnace wall 101 and is led to the steam separator 126 . The steam separated by the steam separator 126 is supplied to the superheaters 102, 103, and 104, and the drain water separated by the steam separator 126 is sent through the steam separator drain tank 127 to the drain water line L2. to the condenser 114.

In addition, when the once-through boiler is started or during low-load operation, the feed water supplied from the economizer 107 does not evaporate completely when passing through the evaporation pipes constituting the furnace wall 101, and as a result, the steam is separated. An operating state (wet operating state) in which a water level exists in the vessel 126 may occur. In this wet operation state, the drain water separated by the steam separator 126 is joined to the middle of the water supply line L1 through the circulation line L6 using the boiler circulation pump (BCP) 128, so that the economizer 107 may be circulated and supplied to the evaporation tubes forming the furnace wall 101.

When the combustion gas flows through the combustion gas passage 13 , heat is recovered from the combustion gas by the superheaters 102 , 103 , 104 , the reheaters 105 , 106 and the economizer 107 . On the other hand, the feed water supplied from the feed water pump (BFP) 123 is preheated by the economizer 107, heated to steam when passing through the evaporation pipes forming the furnace wall 101, and introduced to the steam separator 126. be killed. The steam separated by the steam separator 126 is introduced into the superheaters 102, 103, 104 and superheated by the combustion gas. The superheated steam generated by the superheaters 102, 103, 104 is supplied to the high pressure turbine 111 via the steam line L3, and drives the high pressure turbine 111 to rotate. The steam discharged from the high-pressure turbine 111 is introduced into the reheaters 105 and 106 via the steam line L4 and is heated again. The re-superheated steam is supplied to the low-pressure turbine 113 through the intermediate-pressure turbine 112 via the steam line L5, and drives the intermediate-pressure turbine 112 and the low-pressure turbine 113 to rotate. The rotating shaft of each steam turbine 111, 112, 113 rotates a generator 115 to generate power. The steam discharged from the low-pressure turbine 113 is cooled by the condenser 114 to become condensed water, and is sent to the economizer 107 again through the water supply line L1.

Further, in the combustion gas passage 13, a suit (not shown) is provided between the heat transfer tubes of each heat exchanger such as the superheaters 102, 103, 104, the reheaters 105, 106, and the economizer 107, or between the heat exchangers. A blower (ash removal device) may be arranged. The soot blower is arranged to extend in a direction substantially perpendicular to the wall surface of the combustion gas passage 13 . The soot blower is an injection device that takes the vertical direction to the wall surface of the combustion gas passage 13 as an axial direction, injects steam (gas) in a direction perpendicular to the axial direction, and can also change the injection direction. The steam injected from the soot blower toward heat exchangers such as superheaters 102, 103, 104, reheaters 105, 106, and economizer 107 adheres and accumulates on the surface of each heat transfer tube of the heat exchanger. Removes ash and suppresses deterioration of heat exchange efficiency in each heat transfer tube of the heat exchanger.

Next, the FCB function according to this embodiment will be explained.
FCB is an abbreviation for Fast Cut Back. FCB refers to rapid load throttling of the plant. In the FCB, after narrowing down the load, it shifts to in-house islanding. In the on-site islanding operation, the power plant 1 does not supply power to the power system, but only supplies power within the power plant (such as the power plant in which the power plant 1 is installed), and continues to operate. Since the operation is continued, it can be restored quickly even when it is connected to the power system again.

FIG. 3 is a diagram showing a specific configuration example of the power plant 1 regarding FCB. As shown in FIG. 3, steam generated in the furnace 11 (furnace wall 101) of the boiler 10 passes through superheaters 102, 103, 104 and is sent as main steam to the high-pressure turbine 111 through the governor valve 133. The steam that has finished work in the high-pressure turbine 111 and is discharged is sent to the reheaters 105 and 106 as low-temperature reheat steam via the check valve 135 . The steam resuperheated by the reheaters 105 and 106 is sent to the intermediate pressure turbine 112 via the governor valve 134 as high temperature reheat steam. Steam that has done work in intermediate pressure turbine 112 is channeled to low pressure turbine 113 . In this manner, the high-pressure turbine 111, the intermediate-pressure turbine 112, and the low-pressure turbine 113 are driven, and the power generator 115 generates power.

The steam that has finished work in the low pressure turbine 113 is condensed by the condenser 114 . Condensate is sent to economizer 107 by condensate pump 121 via low pressure feed water heater 122 , deaerator 131 , feed water pump 123 and high pressure feed water heater 124 . The water heated by the economizer 107 returns to the furnace 11 (furnace wall 101).

The reheaters 105 and 106 are provided with a reheater spray water system SF to which spray water is supplied. The reheater spray water system SF is provided with a valve VF (reheater attenuating spray water control valve) for adjusting the flow rate of the spray water. When the reheaters 105 and 106 have a multi-stage structure, spray water can be supplied to desuperheaters installed between the reheaters. The superheaters 102, 103, 104 are provided with a superheater spray water system SG to which spray water is supplied. The superheater spray water system SG is provided with a valve VG (superheater de-warming spray water control valve) for adjusting the flow rate of the spray water. In addition, when the superheaters 102, 103 and 104 have a multi-stage structure, spray water can be supplied to desuperheaters installed between the superheaters. The spray water supplied to the reheater spray water system SF and the superheater spray water system SG is supplied from the feed water pump 123, for example.

Further, the power plant 1 is provided with a turbine bypass system SA, a bypass system SB, a regulation system SC, a check valve 135, a ventilator system SD, and a backup system SE. The power plant 1 is also provided with a control device.

Turbine bypass system SA bypasses steam (main steam) supplied to high pressure turbine 111 to condenser 114 . Specifically, one end of the turbine bypass system SA is connected between the bypass system SB and the governor valve 133 in the main steam distribution system. The other end is connected to the condenser 114 . That is, the turbine bypass system SA bypasses the high pressure turbine 111 and sends part of the main steam to the condenser 114 . A valve VA (regulating valve) is provided in the turbine bypass system SA so that the flow rate of circulating steam can be adjusted.

Bypass system SB bypasses steam (main steam) supplied to high-pressure turbine 111 to reheaters 105 and 106 . Specifically, the bypass system SB has one end connected between the superheaters 102, 103, 104 and the turbine bypass system SA in the main steam distribution system. The other end is connected between the reheaters 105 and 106 and the check valve 135 . That is, the bypass system SB bypasses the high pressure turbine 111 and sends part of the main steam to the reheaters 105 and 106 . A valve VB (regulating valve) is provided in the bypass system SB so that the flow rate of circulating steam can be adjusted.

A regulation system (high-pressure reheat steam pressure regulation system: HRH pressure regulation system) SC discharges the steam (high-temperature reheat steam) re-superheated by the reheaters 105 and 106 to the outside of the system upstream of the intermediate-pressure turbine 112. do. That is, one end of control system SC is connected between reheaters 105 and 106 and governor valve 134 of intermediate pressure turbine 112 . The other end may be open so as to be released to the atmosphere, or may be configured to be released to the outside of the system via a device such as a silencer. The control system SC is provided with a valve VC (regulating valve), which allows the flow rate of the circulating steam to be adjusted.

A check valve (high-pressure turbine exhaust compulsory check valve) 135 is provided on the outlet side of the high-pressure turbine 111 and in a distribution system for steam (low-temperature reheat steam) flowing from the high-pressure turbine 111 to the reheaters 105 and 106. , prevents the low-temperature reheat steam from flowing back to the high-pressure turbine 111 .

A ventilator system (high-pressure turbine exhaust ventilator system) SD sends steam discharged from the high-pressure turbine 111 to a condenser 114 . A valve VD (electric gate valve) is provided in the ventilator system SD, and is automatically opened when the high-pressure turbine exhaust temperature exceeds a set value.

A backup system (high-pressure feedwater pump-driven turbine-driven steam backup system: BFP-T drive system) SE converts part of the low-temperature reheat steam sent to the reheaters 105 and 106 to a pump-driven turbine 132 that drives a feedwater pump 123. supply to A valve VE (regulating valve) is provided in the backup system SE so that the flow rate of circulating steam can be adjusted.

The control device controls the power plant 1 . Specifically, each device provided in the power plant 1 is controlled to control the operating state of the power plant 1 . In particular, the controller is equipped with FCB functionality.

FIG. 4 is a diagram showing an example of the hardware configuration of the control device according to this embodiment.
As shown in FIG. 4, the control device is a computer system (computer system), and includes, for example, a CPU 1100, a ROM (Read Only Memory) 1200 for storing programs executed by the CPU 1100, and It has a RAM (Random Access Memory) 1300 functioning as a work area, a hard disk drive (HDD) 1400 as a large-capacity storage device, and a communication unit 1500 for connecting to a network or the like. A solid state drive (SSD) may be used as the mass storage device. These units are connected via a bus 1800 .

Further, the control device may include an input section such as a keyboard and a mouse, and a display section such as a liquid crystal display device for displaying data.

Note that the storage medium for storing programs and the like executed by the CPU 1100 is not limited to the ROM 1200 . For example, other auxiliary storage devices such as magnetic disks, magneto-optical disks, and semiconductor memories may be used.

A series of processes for realizing various functions to be described later is recorded in the hard disk drive 1400 or the like in the form of a program. As a result, various functions to be described later are realized. The program is pre-installed in the ROM 1200 or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. etc. may be applied. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like.

Next, the FCB operation will be explained.
FIG. 5 shows state changes when FCB operation is performed in power plant 1 . FCB operation is controlled by a control device.

FCB operation is started at time T1. Then, the turbine load (power generation amount) is reduced from 100% to 5%, for example. Specifically, the turbine load corresponds to the on-site load (the amount of electric power consumed in the power plant where the power plant 1 is installed, for example, about 5% of the power plant 1 operating at rated load). The throttle of the governor valves 133 and 134 is performed so that Also, the boiler load (steam generation amount) is reduced from 100% to 20%, for example. Specifically, the boiler load is set so that the boiler minimum load (for example, about 20% of the boiler rated load operation) is a load that allows the boiler 10 to operate stably and continuously. Narrowing down is done. However, in the power plant 1, since it is difficult to quickly narrow down the fuel, it takes a certain amount of time until the amount of steam generated in the boiler 10 decreases to the level corresponding to the minimum load of the boiler. During this transitional period, a difference occurs between the amount of steam generated from the boiler 10 and the amount of steam supplied to the steam turbine 110, and surplus steam is generated. This surplus steam is processed in the control described later. Moreover, even after the transition to in-house single operation, the boiler load is 20% and the turbine load is 5%, so surplus steam is generated, and this surplus steam is also processed in the control described later.

When the FCB operation is started, the main steam pressure set value, which is the control target value of the main steam pressure, decreases at a constant rate (decrease rate) and is set to a predetermined pressure value. The predetermined pressure value is such a pressure that the governor valve 133 can stably control the rotation speed of the high-pressure turbine 111 even in a low flow rate state (approximately 5% of the main steam flow rate at rated load) during in-station single operation. set. Correspondingly, the control device controls the valve VA provided in the turbine bypass system SA based on the main steam pressure set value (main steam pressure control). Specifically, the control device opens the valve VA and controls the opening/closing state (opening degree) of the valve VA based on the main steam pressure set value that is set to decrease. As a result, the pressure state of the main steam changes so as to correspond to the change in the main steam pressure set value, and the pressure of the main steam can be appropriately lowered.

On the other hand, the valve VB of the bypass system SB is opened (for example, fully opened) when the FCB operation is started. Then, the opening state is maintained for a predetermined time (for example, one minute), and the opening is decreased to a predetermined value at a constant rate (closing speed) to release the main steam pressure. The degree of opening of valve VB is controlled so that the flow rate of steam flowing through bypass system SB becomes a flow rate necessary to prevent overheating of reheaters 105 and 106 .

Further, when the FCB operation is started, the high-temperature reheat steam pressure set value, which is the target value of the high-temperature reheat steam pressure, decreases at a constant rate and is set to a predetermined pressure value. The predetermined pressure value is such that the speed of the intermediate pressure turbine 112 and the low pressure turbine 113 is stably controlled by the governor valve 133 even in a low flow rate state (approximately 5% of the reheat steam flow rate at rated load) during in-station single operation. The pressure is set so that it can be controlled. Correspondingly, the controller controls the valve VC provided in the regulation system SC (high pressure reheat steam pressure control) based on the high temperature reheat steam pressure setpoint. Specifically, the control device opens the valve VC (for example, fully open) and maintains the opening for a predetermined time (for example, one minute). The open/closed state (opening degree) of the valve VC is controlled based on the high temperature reheat steam pressure set value that is set to decrease after a predetermined period of time has elapsed. As a result, the pressure state of the high-temperature reheat steam changes so as to correspond to the change in the high-temperature reheat steam pressure setting value, and the pressure of the reheat steam can be appropriately lowered.

The valve VG of the superheater spray water system SG of the superheaters 102, 103, 104 is controlled based on the temperature of the steam superheated in each superheater 102, 103, 104 (superheater temperature control). That is, the valve VG controls the amount of spray water supplied to the superheaters 102 , 103 , 104 . Specifically, the control device controls the opening degree of the valve VG so that the temperature of the steam superheated by each superheater 102, 103, 104 reaches a predetermined temperature.

The valve VF of the reheater spray water system SF of the reheaters 105, 106 is controlled based on the temperature of the steam resuperheated by the respective reheaters 105, 106 (reheater temperature control). That is, the amount of spray water supplied to the reheaters 105 and 106 is controlled by the valve VF. Specifically, the control device controls the opening degree of the valve VF so that the temperature of the steam re-superheated by each of the reheaters 105 and 106 reaches a predetermined temperature.

The valve VE of the backup system SE is opened when the FCB operation is started. Then, the degree of opening is gradually narrowed to reduce the amount of steam. That is, steam is supplied as a backup to the pump-driven turbine 132 that drives the feedwater pump 123 only immediately after the FCB, and thereafter the supply is switched to auxiliary steam. Auxiliary steam is steam that is supplied from part of the steam generated in the boiler 10 or from outside the power plant 1 and is not used for power generation in the power plant 1. For example, the steam is used for heating fuel or for a soot blower. is.

By executing the FCB operation as shown in FIG. 5, the turbine load and the boiler load are narrowed down, and the operation shifts to the in-house islanding operation. FIG. 6 is a diagram showing the flow balance during in-house islanding operation in the power plant 1 of FIG. As an example, assume a boiler load of 20% and a turbine load of 5%. Hereafter, the numerical value of the percentage indicates the flow rate ratio of the main steam or the reheat steam, with the steam flow rate at the boiler rated load being 100%.

As shown in FIG. 6, 20% steam is produced in the boiler 10 and 10% steam flows through the bypass system SB. Of the other 10% steam, 5% is supplied to the high pressure turbine 111 and 5% flows through the turbine bypass system SA. Steam supplied to the high-pressure turbine 111 is sent to the condenser 114 via the ventilator system SD, and steam flowing through the turbine bypass system SA is sent directly to the condenser 114 .

10% of the steam flowing through the bypass system SB is resuperheated by the reheaters 105 and 106 to become high-temperature reheated steam, and 5% is discharged outside the system by the control system SC. The other 5% is supplied to intermediate pressure turbine 112 . Of the 10% of the steam supplied to the reheaters 105 and 106, the amount of steam discharged from the regulation system SC is 5%, and the amount of steam supplied to the intermediate pressure turbine 112 and the low pressure turbine 113 is 5%. The amount of water supplied to the boiler 10 is balanced by replenishing the condenser 114 with the same amount of water as 5% discharged outside the system from the control system SC.

In this way, the FCB operation is switched to the on-site individual operation, and the power plant 1 is disconnected from the power grid.

Next, modification of the power plant 1 will be described.
In the above example, the configuration of the power plant 1 as shown in FIG. 3 was explained, but the existing power plant 1 without the FCB function can be modified to the power plant 1 with the FCB function as shown in FIG. is also possible.

The existing power plant 1 includes a boiler 10, a high pressure turbine (first turbine) 111, reheaters 105 and 106, an intermediate pressure turbine (second turbine) 112, and a turbine bypass system SA. and By modifying such an existing power plant 1, as shown in FIG. 7, the power plant 1 having the same configuration as in FIG. 3 is obtained. In FIG. 7, the portions to be modified are indicated by thick lines.

When remodeling, as shown in FIG. 7, a bypass system SB and a control system SC are provided. Also, as shown in FIG. 7, a check valve 135 and a ventilator system SD are provided. Also, as shown in FIG. 7, the superheater spray water system SG is modified so as to increase the amount of spray water that can be supplied to the superheaters 102, 103, and 104. FIG. Specifically, for example, the valve VG is replaced with one having a large capacity. Also, a backup system SE is provided.

Note that the order of modification is not limited in the modification described above.

By modifying in this way, the turbine bypass system SA is abolished for modification and a low-pressure turbine bypass system SM having a valve VM is installed as in the configuration of the power plant 1 of the reference example shown in FIG. Remodeling can be simplified compared to the case. Also, the low-pressure turbine bypass system SM, such as the reference example shown in FIG. 8, has a system pressure lower than that of the turbine bypass system SA and the bypass system SB. Become. For this reason, it is difficult to pass the pipes through the remodeling without affecting the existing equipment due to restrictions on the layout. On the other hand, modification as shown in FIG. 7 eliminates the need to add the low-pressure turbine bypass system SM, so that restrictions on modification can be relaxed. Further, since the bypass system SB is operated together with the turbine bypass system SA, it is possible to suppress an increase in the capacity of the bypass system SB. Thus, the modification method according to the present embodiment can effectively reduce the modification cost.

It should be noted that the configuration of the power plant 1 described above can be applied to both new construction and modification.

As described above, according to the power plant and its control method and modification method according to the present embodiment, the In the power plant 1, a bypass system SB that bypasses the steam supplied to the high-pressure turbine 111 to the reheaters 105 and 106, and a system that transfers the steam resuperheated by the reheaters 105 and 106 upstream of the intermediate-pressure turbine 112. A control system SC is provided for discharging to the outside. As a result, the steam generated in the boiler 10 can bypass the high pressure turbine 111 and be discharged to the outside of the system before being supplied to the intermediate pressure turbine 112 via the reheaters 105 and 106 . For example, in FCB operation, the turbine load needs to be throttled quickly, so the amount of steam supplied to the high pressure turbine 111 and the intermediate pressure turbine 112 can be quickly reduced. Since the steam bypassing the high-pressure turbine 111 passes through the reheaters 105 and 106, overheating of the reheaters 105 and 106 can be suppressed. Since the steam discharged from the reheaters 105 and 106 is discharged to the outside of the system, it is possible to treat surplus steam while suppressing complication of the configuration.

Further, the pressure of the reheated steam can be adjusted by controlling the valve VC provided in the control system SC based on the pressure set value of the reheated steam resuperheated by the reheaters 105 and 106. .

Further, when the FCB operation is performed, the bypass of the high-pressure turbine 111 is performed by opening the valve VA. After that, by controlling the opening/closing state of the valve VA based on the pressure setting value set to decrease, the pressure of the main steam can be adjusted to decrease.

Further, in the case of remodeling, the existing power plant 1 is provided with a bypass system SB and a regulation system SC. Therefore, the configuration required for modification can be effectively simplified, and the cost can be suppressed. In addition, restrictions on installation for modification can be relaxed. By using the bypass system SB and the regulation system SC together with the existing turbine bypass system SA, it is possible to cope with the FCB operation.

[Second embodiment]
Next, a power plant, its control method, and modification method according to a second embodiment of the present disclosure will be described.
In this embodiment, a configuration of a power plant that is different from that of the first embodiment will be described. In the following, the power plant, its control method, and modification method according to this embodiment will be mainly described with respect to the differences from the first embodiment.

In the power plant 1 according to the present embodiment, as shown in FIG. 9, an auxiliary reheater spray water system SK is provided in place of the bypass system SB and regulation system SC. The check valve 135 and the ventilator system SD can also be dispensed with. Auxiliary reheater spray water system SK is provided downstream of reheaters 105 and 106 . It is provided to keep the high-temperature reheat steam temperature below the design allowable temperature of the part through which the reheat steam flows in the power plant 1 during FCB or in-house islanding operation. The auxiliary reheater spray water system SK is provided with a valve VK. This valve VK regulates the amount of spray water supplied to the outlet side of the reheaters 105,106. The spray water of the auxiliary reheater spray water system SK is supplied from the feed water pump 123, for example.

Next, the FCB operation will be explained.
FIG. 10 shows state changes when FCB operation is performed in power plant 1 . FCB operation is controlled by a controller.

FCB operation is started at time T1. The turbine load is then throttled, for example from 100% to 5%. Also, the boiler load is reduced from 100% to 20%, for example.

When the FCB operation is started, the main steam pressure set value, which is the target value of the main steam pressure, is set to decrease at a constant rate (decrease rate) to reach a predetermined pressure value. The predetermined pressure value is set to a pressure that allows the governor valve 133 to stably control the rotation speed of the high-pressure turbine 111 in a low flow rate state (approximately 5% of the main steam flow rate at rated load) during in-station islanding. be done. Correspondingly, the controller controls the valve VA provided in the turbine bypass system SA based on the main steam pressure setpoint. Specifically, the control device opens the valve VA (for example, fully open). Then, the opening/closing state (opening degree) of the valve VA is controlled based on the main steam pressure set value that is set to maintain the opening state for a predetermined time (for example, one minute) and decrease after the predetermined time has elapsed. As a result, the pressure state of the main steam changes so as to correspond to the change in the main steam pressure set value, and the pressure of the main steam can be appropriately lowered.

The hot reheat steam pressure is not pressure regulated and drops spontaneously.

The valve VG of the superheater spray water system SG of the superheaters 102, 103, 104 is controlled based on the temperature of steam superheated in each superheater 102, 103, 104 (superheater temperature). That is, the valve VG controls the amount of spray water supplied to the superheaters 102 , 103 , 104 . Specifically, the opening degree of the valve VG is controlled so that the temperature of the steam superheated by the superheaters 102, 103, 104 reaches a predetermined temperature.

When the FCB operation starts, the valve VK of the auxiliary reheater spray water system SK is controlled based on the temperature of the steam resuperheated by the reheaters 105 and 106 (high temperature reheat steam temperature). That is, the amount of spray water supplied to the reheaters 105 and 106 is controlled by the valve VK. Specifically, the opening degree of the valve VK is controlled so that the steam temperature at the outlets of the reheaters 105 and 106 reaches a predetermined temperature. This prevents the high-temperature reheat steam temperature from rising too much.

Valve VF of reheater spray water system SF is also controlled based on the temperature of the steam resuperheated by reheaters 105 and 106 . Specifically, the opening degree of the valve VF is controlled so that the steam temperature at the outlets of the reheaters 105 and 106 reaches a predetermined temperature. In addition, since there is a possibility that the supply amount of the spray water from the reheater spray water system SF of the reheaters 105 and 106 is insufficient, by cooperating with the auxiliary reheater spray water system SK, the high temperature can be ensured more reliably. Excessive rise in reheat steam temperature can be suppressed.

The valve VE of the backup system SE is opened when the FCB operation is started. Then, the degree of opening is gradually narrowed to reduce the amount of steam supplied to the pump-driven turbine 132 that drives the feedwater pump 123 .

By executing the FCB operation as shown in FIG. 10, the turbine load and the boiler load are narrowed down, and the operation shifts to the in-house islanding operation. FIG. 11 is a diagram showing the flow balance during in-house islanding operation in the power plant 1 of FIG. As an example, assume a boiler load of 20% and a turbine load of 5%.

As shown in FIG. 11, 20% of main steam is produced in boiler 10, 5% is supplied to high pressure turbine 111, and 15% flows through turbine bypass system SA. The steam supplied to the high pressure turbine 111 is sent to the reheaters 105 and 106, and the steam flowing through the turbine bypass system SA is sent to the condenser 114. The steam resuperheated by the reheaters 105 and 106 is sent to the intermediate pressure turbine 112 .

In this way, switching from FCB operation to in-house individual operation is performed, and disconnection from the power system network is performed. As shown in FIG. 11, the flow rate of steam flowing through the reheaters 105 and 106 during in-house individual operation is about 5%, which is smaller than the first embodiment (10%). On the other hand, the boiler load is about the same as in the first embodiment (20%), and the flow rate of steam flowing through the superheaters 102, 103, 104 is about 20%. It is thought that the high-temperature reheat steam temperature rises. Therefore, the required flow rate of the spray water for the reheaters 105 and 106 increases. By providing the auxiliary reheater spray water system SK, an excessive rise in the high-temperature reheat steam temperature is suppressed.

Next, modification of the power plant 1 will be described.
In the above example, the configuration of the power plant 1 as shown in FIG. 9 was described, but the existing power plant 1 without the FCB function can be modified to the power plant 1 with the FCB function as shown in FIG. is also possible.

The existing power plant 1 is assumed to include a boiler 10, a high-pressure turbine 111, reheaters 105, 106, superheaters 102, 103, 104, and a turbine bypass system SA. By modifying the existing power plant 1 as described above, the power plant 1 having the same configuration as in FIG. 9 is obtained as shown in FIG. 12 . In FIG. 12, the portions to be modified are indicated by thick lines.

When modifying, as shown in FIG. 12, an auxiliary reheater spray water system SK is installed. Also, a backup system SE is provided.

In addition, when the superheater temperature exceeds the design temperature due to insufficient cooling spray water volume in the superheaters 102, 103, 104 during FCB and in-house single operation, remodeling is performed to increase the capacity of the superheater spray water system SG. . Specifically, for example, the valve VG is replaced with one having a large capacity.

Note that the order of modification is not limited in the modification described above.

By modifying in this way, it is possible to simplify the modification. In addition, restrictions on modification can be relaxed. Moreover, since the check valve 135 and the ventilator system SD can be eliminated, the configuration can be simplified.

It should be noted that the configuration of the power plant 1 described above can be applied to both new construction and modification.

Next, a modification of the power plant 1 according to this embodiment will be described.
In this embodiment, the case where the auxiliary reheater spray water system SK is installed on the downstream side (outlet side) of the reheaters 105 and 106 has been described. System SK may be provided on the upstream side (inlet side) of reheaters 105 and 106 . Even when the auxiliary reheater spray water system SK is provided upstream of the reheaters 105 and 106 in this manner, the auxiliary reheater spray water system SK is provided downstream of the reheaters 105 and 106. As in the case, FCB operation can be performed.

Further, the reheater spray water system SF provided for the reheaters 105 and 106 may also be used as the auxiliary reheater spray water system SK. In this case, the configuration is as shown in FIG. In such a case, the temperature of the high-temperature reheat steam tends to rise during FCB operation or the like, so it is preferable to modify the reheater spray water system SF to increase its capacity. Specifically, for example, it is preferable to modify the valve VF to increase its capacity so that the spray water can be supplied so that the temperature of the high-temperature reheat steam does not rise excessively even during FCB operation. .

Further, in the present embodiment and the above modification, the object is to suppress an excessive temperature rise of the high-temperature reheat steam to protect the reheaters 105 and 106 and the intermediate pressure turbine 112. If it is possible to withstand the temperature rise of the reheat steam, or if it is assumed that an excessive temperature rise will not occur due to further reduction of the boiler load, etc., auxiliary reheating is provided downstream or upstream of the reheaters 105 and 106. The heater spray water system SK may be omitted. In this case, the configuration is as shown in FIG. In the configuration shown in FIG. 15, the reheater spray water system SF provided for the reheaters 105 and 106 is also used as the auxiliary reheater spray water system SK. However, unlike the modified example of FIG. 14, the existing reheater spray water system SF is not modified.

FIG. 16 is a diagram for explaining whether or not the auxiliary reheater spray water system SK is required in addition to the reheater spray water system SF. The smaller the flow rate of steam flowing through the reheaters 105, 106 (reheater steam flow rate) than the flow rate of steam flowing through the superheaters 102, 103, 104 (superheater steam flow rate), the higher the reheater outlet steam temperature. , the flow rate of spray water required to set the hot reheat steam temperature to a predetermined value increases. If the required flow rate of spray water exceeds the capacity of the reheater spray water system SF (existing equipment) (reference flow rate in Fig. 16), the rise in the high-temperature reheat steam temperature cannot be suppressed, so the reheater spray In addition to the water system SF, an auxiliary reheater spray water system SK is required. In FIG. 16, the vertical axis represents the required flow rate of the spray water, and the horizontal axis represents the superheater steam flow rate-reheater steam flow rate (difference). FIG. 16 is a diagram conceptually showing an example.

As shown in FIG. 16, when the reheater steam flow rate becomes smaller than the superheater steam flow rate and the difference becomes larger, at a certain point Δ1, the required spray water flow rate becomes the capacity of the reheater spray water system SF. exceed. Therefore, the auxiliary reheater spray water system SK is unnecessary in the area on the left side of the point Δ1, and the auxiliary reheater spray water system SK is necessary in the area on the right side. In particular, when performing FCB operation, the difference between the superheater steam flow rate and the reheater steam flow rate tends to increase, so there is a high possibility that the auxiliary reheater spray water system SK will be required.

If the auxiliary reheater spray water system SK is required, based on the flow rate difference between the steam flow rate of the reheaters 105, 106 and the steam flow rate of the superheaters 102, 103, 104 when performing FCB operation , the spray water supply capacity is designed so that the temperature of the hot reheat steam can be adjusted below a predetermined value. Incidentally, as shown in FIG. 14, the capacity is similarly designed when the valve VF is modified.

On the other hand, if the boiler load during FCB can be further suppressed (for example, 10% to 15%), the difference between the superheater steam flow rate and the reheater steam flow rate becomes smaller, and the point Δ1 shown in FIG. In the case of the area, as shown in FIG. 15, the auxiliary reheater spray water system SK may be unnecessary. In this case, the reheater spray water system SF adjusts the temperature of the high-temperature reheat steam to a predetermined value or lower.

In this way, in the case of the configuration of FIG. 9 in this embodiment and in the case of the modifications of FIGS. The control mode is switched from the normal operation (when the superheater steam flow rate and the reheater steam flow rate are equal, not the FCB operation). Specifically, when the FCB operation is not performed (during normal operation), the amount of spray water supplied to the reheaters 105, 106 and the superheaters 102, 103, 104 based on a preset control law (first control mode). In the first control mode, the difference between the superheater steam flow rate and the reheater steam flow rate is small and within the range assumed in advance for normal operation. to control the amount of spray water supplied to the superheaters 102, 103, 104 based on the superheater steam temperature.

When the FCB operation is performed, the flow rate difference between the steam flow rate of the reheaters 105 and 106 and the steam flow rate of the superheaters 102, 103, and 104 becomes large, so control is performed according to this flow rate difference (second 2 control mode). Specifically, the amount of spray water supplied to the reheaters 105 and 106 is controlled so that this difference in flow rate does not cause temperature anomalies in the reheaters 105 and 106 or in the high-temperature reheat steam. For example, the amount of spray water supplied to the reheaters 105 and 106 is controlled based on the high-temperature reheat steam temperature so that a larger amount of spray water can be supplied than in the first mode.

As described above, according to the power plant and its control method and modification method according to the present embodiment, the boiler 10, the high pressure turbine 111, the reheaters 105 and 106, and the superheaters 102, 103 and 104 are In the power plant 1 provided, it becomes possible to cope with the FCB operation. That is, when the FCB operation is not performed (so-called normal operation), the amount of spray water supplied to the reheaters 105, 106 and the superheaters 102, 103, 104 is controlled based on a preset control rule ( first control mode). On the other hand, when the FCB operation is performed, an imbalance may occur such that the flow rate of steam flowing through the reheaters 105 and 106 is excessively small with respect to the flow rate of steam flowing through the superheaters 102, 103 and 104. be. Therefore, when the FCB operation is performed, the spray water supply amount is controlled in consideration of the flow rate difference between the steam flow rates of the reheaters 105 and 106 and the steam flow rates of the superheaters 102, 103, and 104 (second control mode), the high temperature reheat steam temperature can be suppressed.

Further, the auxiliary reheater spray water system SK is provided on the downstream side of the reheaters 105 and 106 so that the temperature of the reheated steam can be effectively lowered. Then, based on the flow rate difference between the steam flow rate of the reheaters 105, 106 and the steam flow rate of the superheaters 102, 103, 104 when performing FCB operation, the temperature of the steam resuperheated in the reheaters 105, 106 By designing the spray water supply capacity so that the temperature can be adjusted to a predetermined value or less, it becomes possible to more reliably suppress the high-temperature reheat steam temperature to a predetermined value or less.

Further, the existing power plant 1 is modified by installing an auxiliary reheater spray water system SK for supplying spray water to the reheaters 105 and 106 . Therefore, it is possible to effectively suppress the complication of the configuration required for remodeling, and to suppress the cost. In addition, restrictions on installation for modification can be relaxed.

The present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. In addition, it is also possible to combine each embodiment. That is, it is also possible to combine the first embodiment and the second embodiment described above.

In the above-described embodiment, the boiler of the present invention is a coal-fired boiler, but as the fuel, solid fuel such as biomass fuel, PC (petroleum coke) fuel generated during petroleum refining, and petroleum residue is used. It may be a boiler that In addition, the fuel is not limited to solid fuels, and petroleum oils such as heavy oil, light oil, and heavy oil, and liquid fuels such as factory waste liquids can also be used.Gaseous fuels (natural gas, by-product gas, etc.) ) can also be used. Furthermore, it can also be applied to a mixed firing boiler that uses a combination of these fuels.

The power plant, its control method, and modification method described in each of the embodiments described above can be grasped, for example, as follows.
A power plant (1) according to the present disclosure comprises a boiler (10), a first turbine (111) driven by steam produced in said boiler (10), and exhausted from said first turbine (111) A reheater (105, 106) for reheating steam, a second turbine (112) driven by the steam reheated by the reheater (105, 106), and a steam generated by the boiler (10) A bypass system (SB) that bypasses the first turbine (111) and supplies the steam (at least part) to the reheaters (105, 106), and the reheaters (105, 106). and a regulation system (SC) for discharging the superheated steam to the outside of the system on the upstream side of the second turbine (112). The first turbine (111) is the high-pressure turbine 111, and the second turbine (112) is the intermediate-pressure turbine 112 (or the low-pressure turbine 113).

According to the power plant (1) according to the present disclosure, a power plant comprising a boiler (10), a first turbine (111), reheaters (105, 106), and a second turbine (112) In (1), a bypass system (SB) that bypasses the steam supplied to the first turbine (111) to the reheaters (105, 106) and the steam resuperheated by the reheaters (105, 106) A control system (SC) is provided upstream of the second turbine (112) to discharge to the outside of the system. Thereby, the steam generated in the boiler (10) bypasses the first turbine (111) and is discharged outside the system before being supplied to the second turbine (112) via the reheaters (105, 106). becomes possible. For example, in fast cutback operation, the boiler and turbine loads need to be throttled abruptly, and the amount of steam supplied to the first turbine (111) and the second turbine (112) can be reduced. Since the steam bypassing the first turbine (111) passes through the reheaters (105, 106), it is possible to suppress overheating due to an excessively small flow rate of steam flowing through the reheaters (105, 106). Since the steam discharged from the reheaters (105, 106) is discharged to the outside of the system, it is possible to treat surplus steam while suppressing complication of the structure.

The power plant (1) according to the present disclosure operates the control valve (VC) provided in the control system (SC) based on the pressure set value of the steam resuperheated by the reheaters (105, 106). It is good also as providing a control device which controls. A control valve (VC) is a valve VC.

According to the power plant (1) according to the present disclosure, the control valve (VC) provided in the control system (SC) is operated based on the pressure set value of the steam resuperheated by the reheaters (105, 106). By controlling, the pressure of the resuperheated steam can be adjusted.

In the power plant (1) according to the present disclosure, when the fast cutback operation is performed, the control device opens the control valve (VC) based on the pressure set value set to decrease. , the opening/closing state of the control valve (VC) may be controlled.

According to the power plant (1) according to the present disclosure, when performing fast cutback operation, the first turbine (111) is bypassed by opening the control valve (VC). After that, by controlling the opening/closing state of the control valve (VC) based on the pressure setting value set to decrease, the pressure of the re-superheated steam can be adjusted to decrease. .

A power plant (1) according to the present disclosure includes a turbine bypass system (SA) that bypasses the first turbine (111) and supplies steam generated by the boiler (10) to a condenser (114). The control device controls a regulating valve (VA ) may be controlled.

According to the power plant (1) according to the present disclosure, controlling the regulating valve (VA) of the turbine bypass system (SA) that bypasses the steam supplied to the first turbine (111) to the condenser (114) , the pressure of the steam supplied from the boiler (10) to the first turbine (111) can be adjusted.

In the power plant (1) according to the present disclosure, when the fast cutback operation is performed, the control device opens the regulating valve (VA) to the main steam pressure set value set to decrease. Based on this, the opening/closing state of the regulating valve (VA) may be controlled.

According to the power plant (1) according to the present disclosure, when the fast cutback operation is performed, the regulating valve (VA) is opened to bypass the first turbine (111). After that, the pressure of the steam supplied to the first turbine (111) is lowered by controlling the opening/closing state of the regulating valve (VA) based on the main steam pressure set value that is set to be lowered. can be adjusted to allow

A power plant (1) according to the present disclosure includes superheaters (102, 103, 104) for superheating steam generated in the boiler (10), and the control device controls the superheaters (102, 103, 104 ), the amount of spray water supplied to the superheaters (102, 103, 104) may be controlled based on the temperature of the steam superheated by the superheater.

According to the power plant (1) according to the present disclosure, the amount of spray water supplied to the superheaters (102, 103, 104) is based on the temperature of the steam superheated by the superheaters (102, 103, 104). By controlling , the temperature of the steam superheated by the superheaters (102, 103, 104) can be adjusted.

A power plant (1) according to the present disclosure comprises a boiler (10), a first turbine (111) driven by steam produced in said boiler (10), and exhausted from said first turbine (111) A reheater (105, 106) for reheating steam, a superheater (102, 103, 104) for superheating steam produced in said boiler (10), and a spray to said reheater (105, 106) A reheater spray water system (SF, SK) that supplies water, a superheater spray water system (SG) that supplies spray water to the superheaters (102, 103, 104), and fast cutback operation is not performed. In this case, a first control mode for controlling the amount of spray water supplied to the reheaters (105, 106) and the superheaters (102, 103, 104) based on a preset control rule; When performing cutback operation, the reheaters (105, 106) are controlled according to the flow rate difference between the steam flow rate of the reheaters (105, 106) and the steam flow rate of the superheaters (102, 103, 104). ) and a second control mode for controlling the amount of spray water supplied to each of the superheaters (102, 103, 104).

According to the power plant (1) according to the present disclosure, power generation comprising a boiler (10), a first turbine (111), reheaters (105, 106), and superheaters (102, 103, 104) In plant (1), it becomes possible to respond to fast cutback operation. That is, when the fast cutback operation is not performed (so-called normal operation), the spray water supplied to the reheaters (105, 106) and the superheaters (102, 103, 104) is based on a preset control law. Control the amount of supply (first control mode). On the other hand, when fast cutback operation is performed, the flow rate of steam flowing through the reheaters (105, 106) is excessively low relative to the flow rate of steam flowing through the superheaters (102, 103, 104). An imbalance may occur. For this reason, when performing fast cutback operation, the supply amount of spray water is determined in consideration of the flow rate difference between the steam flow rate of the reheaters (105, 106) and the steam flow rate of the superheaters (102, 103, 104). By controlling (second control mode), the reheat steam temperature can be suppressed.

In the power plant (1) according to the present disclosure, the reheater spray water system (SK) is provided downstream of the reheaters (105, 106), and the The temperature of the steam reheated in the reheaters (105, 106) based on the flow rate difference between the steam flow rate of the reheaters (105, 106) and the steam flow rate of the superheaters (102, 103, 104) The supply capacity of the spray water may be designed such that the is adjustable to a predetermined value or less.

According to the power plant (1) according to the present disclosure, the reheater spray water system (SK) is provided downstream of the reheaters (105, 106) to effectively reduce the temperature of the reheated steam. can be made Then, based on the flow rate difference between the steam flow rate of the reheaters (105, 106) and the steam flow rate of the superheaters (102, 103, 104) when performing the fast cutback operation, the reheaters (105, 106) By designing the spray water supply capacity so that the temperature of the reheated steam can be adjusted to a predetermined value or less, it is possible to more reliably suppress the temperature of the reheated steam to a predetermined value or less. Become.

In the power plant (1) according to the present disclosure, the reheater spray water system (SK) is provided upstream of the reheaters (105, 106), and the The temperature of the steam reheated in the reheaters (105, 106) based on the flow rate difference between the steam flow rate of the reheaters (105, 106) and the steam flow rate of the superheaters (102, 103, 104) The supply capacity of the spray water may be designed such that the is adjustable to a predetermined value or less.

According to the power plant (1) according to the present disclosure, the reheater spray water system (SK) is provided upstream of the reheaters (105, 106) to reduce the temperature of the reheated steam. can. Then, based on the flow rate difference between the steam flow rate of the reheaters (105, 106) and the steam flow rate of the superheaters (102, 103, 104) when performing the fast cutback operation, the reheaters (105, 106) By designing the spray water supply capacity so that the temperature of the reheated steam can be adjusted to a predetermined value or less, it is possible to more reliably suppress the temperature of the reheated steam to a predetermined value or less. Become.

In the power plant (1) according to the present disclosure, the reheater spray water system (SK) is provided between the reheaters (105, 106) configured in multiple stages, and fast cutback operation is performed. reheated in the reheater (105, 106) based on the flow difference between the steam flow in the reheater (105, 106) and the steam flow in the superheater (102, 103, 104) in case The spray water supply capacity may be designed such that the temperature of the steam can be adjusted below a predetermined value.

According to the power plant (1) according to the present disclosure, the reheater spray water system (SK) is provided between the multistage reheaters (105, 106) to reduce the temperature of the reheated steam. can be made Then, based on the flow rate difference between the steam flow rate of the reheaters (105, 106) and the steam flow rate of the superheaters (102, 103, 104) when performing the fast cutback operation, the reheaters (105, 106) By designing the spray water supply capacity so that the temperature of the reheated steam can be adjusted to a predetermined value or less, it is possible to more reliably suppress the temperature of the reheated steam to a predetermined value or less. Become.

A control method according to the present disclosure includes a boiler (10), a first turbine (111) driven by steam generated by the boiler (10), and recycling steam discharged from the first turbine (111). A control method for a power plant (1) comprising a superheating reheater (105, 106) and a second turbine (112) driven by steam reheated in said reheater (105, 106). a step of bypassing the first turbine (111) and supplying the steam generated in the boiler (10) to the reheaters (105, 106); and discharging the re-superheated steam to the outside of the system on the upstream side of the second turbine (112).

A control method according to the present disclosure includes a boiler (10), a first turbine (111) driven by steam generated by the boiler (10), and recycling steam discharged from the first turbine (111). A reheater (105, 106) for superheating, a superheater (102, 103, 104) for superheating the steam produced in said boiler (10), and supplying spray water to said reheater (105, 106). and a superheater spray water system (SG) for supplying spray water to the superheaters (102, 103, 104). Supplying spray water to the reheaters (105, 106) and the superheaters (102, 103, 104) based on a preset control rule when fast cutback operation is not performed According to the flow rate difference between the steam flow rate of the reheater (105, 106) and the steam flow rate of the superheater (102, 103, 104) when performing the step of controlling the amount and fast cutback operation, and controlling the amount of spray water supplied to each of the reheaters (105, 106) and the superheaters (102, 103, 104).

A modification method according to the present disclosure includes a boiler (10), a first turbine (111) driven by steam generated by the boiler (10), and recycling the steam discharged from the first turbine (111). a superheating reheater (105, 106), a second turbine (112) driven by steam reheated in said reheater (105, 106), and steam produced in said boiler (10); and a turbine bypass system (SA) that bypasses the first turbine (111) and supplies a condenser (114), wherein providing a bypass system (SB) for bypassing the first turbine (111) and supplying the steam to the reheaters (105, 106); and providing a control system (SC) for discharging the generated steam to the outside of the system on the upstream side of the second turbine (112).

According to the modification method according to the present disclosure, the boiler (10), the first turbine (111), the reheaters (105, 106), the second turbine (112), and the turbine bypass system (SA) are provided. A bypass system (SB) for supplying the steam generated by the boiler (10) to the reheaters (105, 106) bypassing the first turbine (111) for the existing power plant (1); , and a regulation system (SC) that discharges the steam re-superheated by the reheaters (105, 106) to the outside of the system upstream of the second turbine (112). Therefore, it is possible to effectively suppress the complication of the configuration required for remodeling, and to suppress the cost. In addition, restrictions on installation for modification can be relaxed. By using the bypass system (SB) and the control system (SC) together with the existing turbine bypass system (SA), it is possible to respond to the fast cutback operation.

The modification method according to the present disclosure comprises the steps of: providing a check valve (135) provided in a flow system of steam flowing from the first turbine (111) to the reheaters (105, 106); and providing a system (SD) for supplying steam to the condenser (114) from between (111) and the check valve (135). A system (SD) is a ventilator system SD.

According to the modification method according to the present disclosure, a check valve (135) provided in a flow system of steam flowing from the first turbine (111) to the reheaters (105, 106), and the first turbine (111) By providing a system (SD) for supplying steam to the condenser (114) from between the check valves (135), it is possible to respond to fast cutback operation.

In the modification method according to the present disclosure, the power plant (1) includes superheaters (102, 103, 104) for superheating steam generated in the boiler (10), and the superheaters (102, 103, 104) a superheater spray water system (SG) for supplying spray water to the superheater, and modifying the superheater spray water system (SG) to increase the amount of spray water that can be supplied. .

According to the modification method according to the present disclosure, by modifying the superheater spray water system (SG) so as to increase the amount of spray water that can be supplied, the superheaters (102, 103, 104) can be prevented from overheating.

A modification method according to the present disclosure includes a boiler (10), a first turbine (111) driven by steam generated by the boiler (10), and recycling the steam discharged from the first turbine (111). reheaters (105, 106) for superheating; superheaters (102, 103, 104) for superheating the steam produced in the boiler (10); A second turbine (112) driven by steam and a turbine bypass system (SA) that bypasses the first turbine (111) and supplies the steam generated by the boiler (10) to a condenser (114) ), comprising the step of providing reheater spray water systems (SF, SK) for supplying spray water to said reheaters (105, 106).

According to the modification method according to the present disclosure, the boiler (10), the first turbine (111), the reheaters (105, 106), the superheaters (102, 103, 104), the turbine bypass system (SA ) is modified to install a reheater spray water system (SK) that supplies spray water to the reheaters (105, 106). Therefore, it is possible to effectively suppress the complication of the configuration required for remodeling, and to suppress the cost. In addition, restrictions on installation for modification can be relaxed. By using the reheater spray water system (SK) together with the existing turbine bypass system (SA), it is possible to respond to fast cutback operation.

1: Power plant 10: Boiler 11: Furnace 12: Combustion device 13: Combustion gas passage 14: Flue 21-25: Burner 26-30: Pulverized coal supply pipe 31-35: Pulverizer 36: Wind box 37: Air duct 38: forced draft fan 39: additional air port 40: additional air duct 41: gas duct 42: air heater 43: denitration device 44: dust collector 46: desulfurization device 50: chimney 101: furnace wall 102: first superheater 103: second 2 superheater 104 : 3rd superheater 105 : 1st reheater 106 : 2nd reheater 107 : Economizer 110 : Steam turbine 111 : High pressure turbine 112 : Intermediate pressure turbine 113 : Low pressure turbine 114 : Condenser 115 : Generator 121 : Condensate Pump 122 : Low Pressure Feed Water Heater 123 : Feed Water Pump 124 : High Pressure Feed Water Heater 126 : Steam Separator 127 : Steam Separator Drain Tank 131 : Deaerator 132 : Pump Driven Turbine 133 : Governor Valve 134 : Governor valve 135 : Check valve 1100 : CPU
1200: ROM
1300: RAM
1400: Hard disk drive 1500: Communication unit 1800: Bus L1: Water supply line L2: Drain water line L3: Steam line L4: Steam line L5: Steam line L6: Circulation line SA: Turbine bypass system SB: Bypass system SC: Control system SD : Ventilator system SE : Backup system SF : Reheater spray water system SG : Superheater spray water system SK : Auxiliary reheater spray water system SM : Low-pressure turbine bypass system

Claims (16)

a boiler;
a first turbine driven by steam produced by the boiler;
a reheater for reheating the steam discharged from the first turbine;
a second turbine driven by the steam reheated by the reheater;
a bypass system that bypasses the first turbine and supplies the steam generated by the boiler to the reheater;
a regulation system that discharges the steam resuperheated by the reheater to the outside of the system on the upstream side of the second turbine;
A power plant with a 2. The power plant according to claim 1, further comprising a control device for controlling a control valve provided in said control system based on a pressure set value of steam resuperheated by said reheater. 3. The control device according to claim 2, wherein when fast cutback operation is performed, the control valve is opened and the control valve is opened and closed based on the pressure set value set to decrease. Power plant as described. a turbine bypass system that bypasses the first turbine and supplies the steam generated by the boiler to a condenser;
4. The power plant according to claim 2 or 3, wherein the control device controls a regulating valve provided in the turbine bypass system based on a main steam pressure set value of steam supplied from the boiler to the first turbine. . 3. The control device, when performing fast cutback operation, opens the regulating valve and controls the opening/closing state of the regulating valve based on the main steam pressure set value that is set to decrease. 5. The power plant according to 4. Equipped with a superheater for superheating the steam generated by the boiler,
The power plant according to any one of claims 2 to 5, wherein the controller controls the amount of spray water supplied to the superheater based on the temperature of the steam superheated by the superheater. a boiler;
a first turbine driven by steam produced by the boiler;
a reheater for reheating the steam discharged from the first turbine;
a superheater for superheating the steam generated by the boiler;
a reheater spray water system that supplies spray water to the reheater;
a superheater spray water system for supplying spray water to the superheater;
When the fast cutback operation is not performed, a first control mode for controlling the amount of spray water supplied to the reheater and the superheater based on a preset control rule and the fast cutback operation are performed. a second control mode for controlling the supply amount of spray water supplied to each of the reheater and the superheater according to the flow rate difference between the steam flow rate of the reheater and the steam flow rate of the superheater. a control device having
A power plant with a The reheater spray water system is provided downstream of the reheater, and is based on the flow rate difference between the steam flow rate of the reheater and the steam flow rate of the superheater when fast cutback operation is performed. 8. The power plant according to claim 7, wherein the spray water supply capacity is designed so that the temperature of the steam reheated in the reheater can be adjusted to a predetermined value or less. The reheater spray water system is provided upstream of the reheater, and is based on the flow rate difference between the steam flow rate of the reheater and the steam flow rate of the superheater when fast cutback operation is performed. 8. The power plant according to claim 7, wherein the spray water supply capacity is designed so that the temperature of the steam reheated in the reheater can be adjusted to a predetermined value or less. The reheater spray water system is provided between the multi-stage reheaters, and the flow rate of the steam flow rate of the reheater and the steam flow rate of the superheater when fast cutback operation is performed. 8. The power plant according to claim 7, wherein the spray water supply capacity is designed such that the temperature of the steam reheated in the reheater can be adjusted below a predetermined value based on the difference. a boiler; a first turbine driven by the steam generated by the boiler; a reheater for reheating the steam discharged from the first turbine; and a second turbine comprising:
supplying steam produced by the boiler to the reheater, bypassing the first turbine;
a step of discharging the steam resuperheated by the reheater to the outside of the system on the upstream side of the second turbine;
A control method with a boiler, a first turbine driven by steam produced by the boiler, a reheater for reheating the steam discharged from the first turbine, and a superheater for superheating the steam produced by the boiler. , a reheater spray water system for supplying spray water to the reheater, and a superheater spray water system for supplying spray water to the superheater, comprising:
a step of controlling the amount of spray water supplied to the reheater and the superheater based on a preset control rule when fast cutback operation is not performed;
When fast cutback operation is performed, the amount of spray water supplied to each of the reheater and the superheater is adjusted according to the flow rate difference between the steam flow rate of the reheater and the steam flow rate of the superheater. a step of controlling;
A control method with a boiler; a first turbine driven by the steam generated by the boiler; a reheater for reheating the steam discharged from the first turbine; and a turbine bypass system that bypasses the first turbine and supplies steam generated in the boiler to a condenser, the method comprising:
providing a bypass system for supplying the steam generated by the boiler to the reheater, bypassing the first turbine;
providing a regulation system for discharging the steam resuperheated by the reheater to the outside of the system on the upstream side of the second turbine;
Modification method with. providing a check valve provided in a flow system for steam flowing from the first turbine to the reheater;
providing a system for supplying steam to the condenser from between the first turbine and the check valve;
14. The retrofitting method of claim 13, comprising: The power plant comprises a superheater for superheating the steam generated by the boiler, and a superheater spray water system for supplying spray water to the superheater,
15. A method of retrofitting according to claim 13 or 14, comprising the step of retrofitting the superheater spray water system to increase the supply of spray water. a boiler, a first turbine driven by steam produced by the boiler, a reheater for reheating the steam discharged from the first turbine, and a superheater for superheating the steam produced by the boiler. a power generation comprising: a second turbine driven by steam resuperheated by said reheater; and a turbine bypass system for bypassing said first turbine and supplying steam generated by said boiler to a condenser. A plant modification method comprising:
A retrofitting method comprising the step of providing a reheater spray water system for supplying spray water to the reheater.

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