GB2593002A

GB2593002A - Condenser vacuum breaker

Info

Publication number: GB2593002A
Application number: GB2011420.3A
Authority: GB
Inventors: Uegaki Natsuyo; Ikeda Haruhiko
Original assignee: Hitachi GE Nuclear Energy Ltd
Current assignee: Hitachi GE Nuclear Energy Ltd
Priority date: 2019-08-09
Filing date: 2020-07-23
Publication date: 2021-09-15
Anticipated expiration: 2040-07-23
Also published as: JP2021028491A; GB202011420D0; GB2593002B; JP7101148B2

Abstract

A condenser vacuum breaker DV comprising: a vacuum break valve 65 provided in the air intake line 64 of a condenser 62; a first pressure gauge 66 that measures the pressure inside a building, e.g. a turbine building 60 in a nuclear power plant, in which the condenser is located; and a control unit 69 that controls the operation of a vacuum break valve. The control unit closes the vacuum break valve in order to maintain the vacuum state in the condenser during a normal operation; however, when a vacuum break command is detected, the control unit opens the vacuum break valve while controlling said opening such that the building pressure is maintained at a predetermined set value. Therefore, even when a vacuum break valve is opened, a temporary decrease in the pressure within the building housing the condenser is prevented.

Description

CONDENSER VACUUM BREAKER

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a condenser vacuum breaker.

2. Description of the Related Art

In the related art, some nuclear power plants have a structure capable of performing measures to operate the condenser vacuum break with a condenser vacuum breaker provided therein. Here, the "measures to operate the condenser vacuum break" means that air inside a turbine building (outside air) is vented into a condenser to break the vacuum state in the condenser, thereby, changing the condenser's internal pressure from the vacuum to atmospheric pressure. The measures to operate the condenser vacuum break are performed by opening a vacuum break valve provided in the air intake line of the condenser and venting the outside air into the condenser. The turbine building, which is provided with a Heating, Ventilation, and Air conditioning system (HVAC), is a closed space (radiation control area).

The measures to operate the condenser vacuum break are performed, for example, during a normal shutdown operation of the plant. After turbine trios, the vacuum break valve is opened and the vacuum break operation in the condenser is started.

As an example of a technique for maintaining the vacuum level in the condenser, a vacuum adjusting mechanism (condenser vacuum break control unit) described in JP-A-2009-287489 (Patent Literature 1) is known. Patent Literature 1 describes the following matters.

That is, the vacuum adjusting mechanism is provided with a plurality of air intake valves having different diameters such that an air intake rate can be finely adjusted by the number of fully opened valves. A stop valve mechanism can transmit and shut of f the air intake rate to the condenser. Therefore, the air intake rate for adjusting the condenser to a proper vacuum is prepared in advance by the vacuum adjusting mechanism; and by opening the stop valve mechanism, a proper air intake rate is immediately transmitted to the condenser. As a result, it is possible to adjust the vacuum level in the condenser to an economic, safe, and current situation-matching condition.

However, in the related art condenser vacuum breaker used in same nuclear power plants, as described below, the pressure inside the turbine building may temporarily decrease by opening the vacuum break valve during the performance of measures to operate the condenser vacuum break.

For example, in the related art condenser vacuum breaker, during the performance of the measures to operate the condenser vacuum break, the condenser rapidly sucks the air (outside air) from the turbine building that is a closed space. Therefore, there is a problem that the pressure inside the turbine building may temporarily decrease when the amount of atmospheric air entering the turbine building from outside the turbine building and the amount of outside air sucked into the condenser from the turbine building have the following relationship, that is, "amount of outside air sucked by the condenser > amount of atmospheric air flowing into the turbine building".

Moreover, the number of condensers provided in a nuclear power plant is the same with as the number of low-pressure steam turbines. The measure to operate the condenser vacuum break in a nuclear power plant is performed by simultaneously opening all of the vacuum break valves provided in the air intake lines of each respective condenser. However, when all of the vacuum break valves are opened at the same time, the vacuum state in each of the condensers is broken simultaneously, thus, causing a phenomenon, in which the pressure inside the turbine building temporarily decreases.

In addition, the Internal pressure in the bearing box of a steam turbine rotor or a generator or the like provided in the turbine building is changed to a negative pressure, which is lower than the pressure inside the turbine building during normal operation. However, there is also a problem that the lube oil used in the bearing box may leak from the bearing box into the turbine building when the pressure inside the turbine building decreases due to the performance of measures to operate the condenser vacuum break. As a result, the internal pressure in the bearing box of the steam turbine rotor or the generator or the like will have the following relationship; "internal pressure of the bearing box > pressure inside the turbine building". The vacuum adjusting mechanism described in Patent Literature 1 can adjust the vacuum level of the condenser in order to maintain the vacuum level in the condenser, but the pressure inside the turbine building at the time of condenser vacuum break operation cannot be adjusted.

SUMMARY OF THE INVENTION

The invention is made to solve the above-mentioned problems, in which the main object is to provide a condenser vacuum breaker that prevents a temporary decrease in building pressure (a pressure inside the turbine building) even when a vacuum break valve is opened during the performance of measures to operate the condenser vacuum. break. Other objects for solving the problems will become apparent in the description of the embodiments for carrying out the invention.

In order to achieve the above-described object, the invention provides a condenser vacuum breaker including a vacuum break valve provided in the air intake line of a condenser; a first pressure measuring device configured to measure the building pressure inside a building where the condenser is provided, and a control unit configured to control the operation of a vacuum break valve. The control unit closes the vacuum break valve in order to maintain the vacuum state in the condenser during normal operation; however when a vacuum break command is detected, the control unit opens the vacuum break valve while controlling the opening so that the building pressure is maintained at a predetermined set value.

Other solutions will be described below.

According to the invention, even when the vacuum break valve is opened during the performance of the measures to operate the condenser vacuum break, a temporary decrease in the building pressure (the pressure inside the turbine building) can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a nuclear power plant including a condenser vacuum breaker according to the first embodiment.

FIG. 2 is a flowchart showing operations of the condenser vacuum breaker according to the first embodiment.

FIG. 3 is an illustrative diagram showing the operation of a control unit when an opening command signal at an initial stage is outputted to a vacuum break valve.

FIG. 4 is a graph showing a relationship beT_ween the differential pressure between a condenser pressure and a building pressure and the opening of the vacuum break valve.

FIG. 5 is a schematic diagram of a nuclear power plant including a condenser vacuum breaker according to the second embodiment.

FIG. 6 is a flowchart showing operations of the condenser vacuum breaker according to the second embodiment.

FIG. 7 is a flowchart showing the first modification in the operations of the condenser vacuum breaker according to the second embodiment.

FIG. 8 is a flowchart showing the second modification in the operations of the condenser vacuum breaker according to the second embodiment.

FIG. 9 is a flowchart showing the third modification in the operations of the condenser vacuum breaker according to the second embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments of the invention (hereinafter, referred to as "present embodiment") will be described in detail with reference to the drawings. The drawings are merely shown schematically to an extent that the invention can be fully understood. Therefore, the invention is not limited to only illustrated examples. Furthermore, in each drawing, common or similar components are designated by the same reference numerals, and duplicated description thereof will be omitted.

[First Embodiment] <Configuration of Condenser Vacuum Breaker> Hereinafter, the configuration of a condenser vacuum breaker DV according to the first embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic diagram of a nuclear power plant PL including the condenser vacuum breaker DV.

The nuclear power plant PL is a plant having a water-cooled reactor represented by either a Boiling Water Reactor (BWR) or a Pressurized Water Reactor (PWR). The present embodiment will be described based from on an assumption that the nuclear power plant PL is a boiling water nuclear power plant having a boiling water reactor.

In the example shown in FIG. 1, the isolation valves 22 and the feedwater line stop valve 32, which will be described later, are shown using a void symbol, and this symbol indicates that the isolation valves 22 and the feedwater line stop valve 32, which will be described later, are in an opened state. In contrast, a vacuum break valve 65, which will be described later, is shown using in a black-filled symbol, and this symbol indicates that the vacuum break valve 65, which will be described later is in a closed state.

As shown in FIG. 1, the nuclear power plant PL according to the first embodiment includes a reactor building 10 that houses a RPV 12 and the like, a turbine building 60 that houses a steam turbine 61 and the like, and a control room 70 provided with a control panel 71 that controls the operations of the reactor.

Inside the reactor building 10, a reactor containment vessel 13 having an airtight structure is enclosed. The reactor containment vessel 13 contains a reactor pressure vessel 12 that seals a reactor core 11 in which a fuel assembly is loaded.

Inside the turbine building 60, the steam turbine 61, a condenser 62, and the condenser vacuum breaker DV are enclosed. The steam turbine 61 has a mechanism that converts thermal energy of steam generated from the reactor pressure vessel 12 into rotational energy and transmits the rotational energy to a generator to obtain electrical energy. The condenser 62 has a mechanism that condenses steam that has driven after the steam turbine 61. The condenser vacuum breaker DV is a device that breaks the vacuum state in the condenser 62 by venting air from the turbine building 60 into the condenser 62, so as to change the pressure inside the condenser 62 from vacuum to atmospheric pressure.

The reactor pressure vessel 12 and the steam turbine 61 are connected by a steam line 21. The steam turbine 61 and the condenser 62 are connected by an exhaust line 63. The condenser 62 and the reactor pressure vessel 12 are connected by a feedwater line 31. The isolation valves 22; which restrictively starts and stops the flow in the steam line 21; is provided along the steam line 21. When the isolation valves 22 are in a closed state, the steam line 21 is separated into a line on a reactor pressure vessel 12 side and a line on a steam turbine 61 side, and the reactor pressure vessel 12 is isolated from surroundings. The feedwater line stop valve 32, which selectively connects and disconnects the feedwater line 31, is provided along the feedwater line 31. The feedwater line stop valve 32 stops the flow of cooling water returned from the condenser 62 to the reactor pressure vessel 12 when the feedwater line stop valve 32 is in a closed state.

Steam generated in the reactor core 11 is guided to the steam turbine 61 via the steam line 21, which is connected to the reactor pressure vessel 12, and drives the steam turbine 61. The steam that has driven the steam turbine 61 is recovered to the condenser 62 via the exhaust line 63, and is condensed into condensate in the condenser 62. The condensate is returned as feedwater to the reactor pressure vessel 12 via the feedwater line 31. A heater (not shown) and a pump (not shown) are provided in the path of the feedwater line 31. The condensate is heated by the heater (not shown), pressurized by the pump (not shown), and then sent as feedwater to the reactor pressure vessel 12.

During normal operation in a nuclear power plant PL, the inside of the condenser 62 is kept at a vacuum condition. An air intake line 64 for taking the air (outside air) from the turbine building 60 is connected to the condenser 62. Avacuum break valve 65, which selectively connects and disconnects the air intake line 64, is provided along the air intake line 64. During normal operation in a nuclear power plant PL, the vacuum break valve 65 is closed. When the reactor is stopped, the condenser vacuum breaker DV sends the air (the air in the turbine building 60) to the condenser 62 by opening the vacuum break valve 65, and breaks the vacuum in the condenser 62.

The condenser vacuum breaker DV Includes a vacuum break valve 65 described above, a first pressure gauge 66, a second pressure gauge 67, and a control unit 69. The first pressure gauge 66 is a measuring device that measures the internal pressure of a turbine building 60 (hereinafter referred to as "building pressure") in which the condenser 62 is provided. The second pres sure gauge 67 is a measuring device that measures the internal pressure of the condenser 62 (hereinafter referred to as "condenser pressure"). The control unit 69 is a control unit that controls the opening and closing of the vacuum break valve 65. The control unit 69 outputs an opening command signal Sgop, which conveys the instruction of controlling of the vacuum break valve 65 opening in response to a vacuum break command SG71 outputted from the control panel 71. Therefore, the control unit 69 opens the vacuum break valve 65 and starts vacuum break operation in the condenser 62.

<Operation of Condenser Vacuum Breaker> Hereinafter, the operations of the condenser vacuum breaker DV will be described with reference to FIG. 2. FIG. 2 is a flowchart showing the operations of the condenser vacuum breaker DV. The operations shown in FIG. 2 are mainly oerformed by the control unit 69.

During normal operation, in a nuclear power plant PL, the condenser 62 is in a vacuum state. The vacuum break valve 65 is fully closed to maintain the vacuum state of the condenser 62. The first pressure gauge 66 measures the buildincipressure and outputs a building pressure setpoint 966a, which indicates the measured value of the building pressure, to the control unit 69. The second pressure gauge 67 measures the condenser pressure and outputs a condenser pressure setpointP67a, which indicates the measured value of the condenser pressure, to the control unit 69.

When the nuclear power plant PL is suddenly stopped during normal operation, an operator of the control panel 71 stationed in the control room 70 operates the control panel 71 to output the vacuum break command 5G71 from the control panel 71 to the control unit 69.

As shown in FIG. 2, when the vacuum break command SG71 is outputted from the control panel 71, the control unit 69 detects the racuumbreak command SG71 (Step S110). In response to the detection, the control unit 69 sends the opening command signal SGop (see FIG. 3) to the vacuum break valve 65 to gradually open the vacuum break valve 65 while controlling the opening of the vacuum break valve 65 (Step S120).

At that time, as shown in FIG. 3, the control unit 69 controls the opening of the vacuum break valve 65 so that the building pressure (the building pressure setpoint P66a measured by the first pressure gauge 66) is maintained at a predetermined set value (a building pressure set value P66b to be described later). FIG. 3 is an illustrative diagram showing the operation of the control unit 69 when the opening command signal SGop at an initial stage is sent to the vacuum break valve 65. Here, the "initial stage" is described as a current stage after the vacuum break command 5C-71 is detected.

The opening of the vacuum break valve 65 is controlled as follows; First, at the initial stage of step 9120, as shown in FIG. 3, the control unit 69 generates the opening command signal SGop based on a differential pressure between the buildingpressure setpoint P66a, measured by the first pressure gauge 66; and the building pressure set value P66b stored in advance in a storage unit M in the control unit 69. At this time, the control unit 69 calculates a default opening for the vacuum break valve 65 corresponding to the differential pressure between the building pressure setpoint P66a and the building pressure set value P66b then sends an opening command signal Sgop, corresponding to the calculated default opening, to the vacuum break valve 65. The building pressure set value P66b can be freely set according to the operation. In the present embodiment, it is assumed that the building pressure set value 966b is set at an Internal pressure value of the turbine building 60 measured during normal operation.

When the control unit 69 sends the opening command signal SGop at the initial stage to the vacuum break valve 65, the opening of the vacuum break valve 65 is set to a default opening indicated by the opening command signal SGop as a response. As a result, the building pressure (the pressure inside the turbine building) is brought into a state of being close to the building pressure set value P66b.

After sending the opening command signal SGop at the initial stage to the vacuum break valve 65, the control unit 69 gradually opens the vacuum break valve 65 while controlling the opening of the vacuum break valve 65 based on the differential pressure between the condenser pressure and the building pressure. At this time, the control unit 69 calculates an opening for the vacuum break valve 65 corresponding to the differential pressure between the condenser pressure (the condenser pressure setpoint P67a) and the building pressure (the building pressure set value P66b), then generates an opening command signal Sgop, corresponding to the calculated opening, and sends the opening command signal SGop to the vacuum break valve 65. As a response, the opening of the vacuum break valve 65 is changed to the opening indicated by the opening command signal SGop.

Returning to FIG. 2, after Step 3120, the control unit 69 calculates a differential pressure between the condenser pressure and the building pressure based on the condenser pressure (the condenser pressure setpoint P67a) and the building pressure (the building pressure setpoint P66a) (Step 3130).

Next, the control unit 69 determines whether or not the differential pressure between the condenser pressure (the condenser pressure setpoint P67a) and the building pressure (the building pressure setpoint 966a) reaches a predetermined setpoint Ppr (see FIG. 4) (Step S140). The setpoint Ppr will be described later. In decision point at step 3140, when it is determined that the differential pressure reaches the setpoint Ppr (see FIG. 4) (in case of a "Yes"), the control unit 69 fully opens the vacuum break valve 65 (Step S150). When the vacuum break valve 65 is fully opened, breaking the vacuum state in the condenser 62 is completed.

On the other hand, when it is determined, in the decision point at Step 3140 that the differential pressure does not reach the setpoint Ppr (see FIG. 4) (in a case of "Non), the control unit 69 determines whether or not a predetermined control completion condition is satisfied (Step S160). The control completion condition can be freely set according to the operation. When it is determined in the decision point at Step 5160 that the control completion condition is not satisfied (in a case of "No"), the process returns to Step 3130.

After Step S150 or when it is determined in the decision point at Step 5160 that the control completion condition is satisfied (in a case of "Yes"), processing of a series of routine is completed.

FIG. 4 is a graph showing the relationship between the differential pressure between the condenser pressure (the condenser pressure setpoint P67a) and the building pressure (the building pressure setpoint 966a) and the opening of the vacuum break valve 65. FIG. 4 shows that the horizontal axis represents the differential pressure between the condenser pressure and the building pressure, the vertical axis represents the opening of the vacuum break valve 65, and the opening of the vacuum break valve 65 is changed according to the differential pressure. As shown in FIG. 4, in order to gradually decrease the differential pressure between the condenser pressure and the building pressure, the control unit 69 gradually increases the opening of the vacuum break valve 65 (see arrow All). Then, the control unit 69 maximizes the opening of the vacuum break valve 65, that is, fully opens the vacuum break valve 65, when the differential pressure between the condenser pressure and the building pressure reaches the predetermined setpoint Ppr (see arrow Al2). The setpoint Ppr can be set to any positive (plus) value accordirg to the operation. The setpoint Ppr is preferably a value close to zero.

<Main Characteristic of Condenser Vacuum Breaker> (1) The condenser vacuum breaker DV according to the first embodiment opens the vacuum breaker valve 65 while controlling the opening of the vacuum breaker valve 65 so that the building pressure is maintained at a predetermined set value (see Step 5120 in FIG. 2).

In such a condenser vacuum breaker DV, even when the vacuum break valve 65 is opened during the vacuum break of the condenser 62, the air in the building (the turbine building 60) can be prevented from being rapidly sucked into the condenser 62 side. Therefore, the condenser vacuum breaker DV can break the vacuum state of the condenser 62 while maintaining the building pressure (the pressure inside the turbine building) at a constant set value (the building pressure set value P66b (see FIG. 3)). Such a condenser vacuum breaker DV can prevent a temporary decrease in the building pressure (the pressure inside the turbine building). As a result, the condenser vacuum breaker DV can prevent lube oil used in a bearing box of a steam turbine 61 rotor or the generator (not shown) or the like from leaking from the bearing box into the turbine building 60.

(2) The condenser vacuum breaker DV according to the first embodiment fully opens the vacuum break valve 65 when the differential pressure between the condenser pressure and the building pressure reaches the predetermined setpoint after breaking the vacuum state in the condenser 62 is started (see Step S150 of FIG. 2).

Such a condenser vacuum breaker DV can complete the break of the vacuum state of the condenser 62 while preventing the temporary decrease in the building pressure (the pressure inside the turbine building).

As described above, according to the condenser vacuum breaker DV according to the first embodiment, even when the vacuum break valve 65 is opened during the vacuum.break in the condenser 62, the temporary decrease in the building pressure (pressure inside the turbine building) can be prevented.

[Second Embodiment] The condenser vacuum breaker DV (see FIG. 1) according to the first embodiment is configured to have one steam turbine 61 and one condenser 62. On the other hand, in the second embodiment, a condenser vacuum breaker DVa is provided with a plurality of steam turbines 61 (three steam turbines 61a, 61b, 61c in the shown example) and a plurality of condensers 62 (three condensers 62a, 62b, 62c in the shown example).

<Configuration of Condenser Vacuum Breaker> Hereinafter, the configuration of the condenser vacuum breaker DVa will be described with reference to FIG. 5. FIG. 5 is a system diagram of a nuclear power plant PLa including the condenser vacuum breaker DVa.

As shown in FIG. 5, the differences between the nuclear power plant Pla, which is in accordance with to the second embodiment, and the nuclear power plant PL, which is in accordance with the first embodiment, (see FIG. 1) are described in the following points.

(1) A plurality of steam turbines 61 (three steam turbines 61a, 61b, 61c in the shown example) and a plurality of condensers 62 (three condensers 62a, 62b, 62c in the shown example) are provided in the turbine building 60.

(2) The three steam turbines 61a, 61b, 61c are connected to their corresponding condensers 62a, 62b, 62c respectively exhaust via connection lines 63a, 63b, 63c.

(3) The three steam turbines 61a, 61b, 61c are connected to the reactor pressure vessel 12 via the steam line 21.

(4) The three condensers 62a, 62h, 62c are connected to the reactor pressure vessel 12 via the feedwater line 31.

(5) The three condensers 62a, 62b, 62c is provided with air intake lines 64a, 64b, 64c respectively, and vacuum break valves 65a, 65b, 65c are installed along the respective air intake lines 64a, 64b, 64c.

(6) The three condensers 62a, 62b, 62c are connected by a tie line 68 which is a hollow pipe. Steam or cooling water in the three condensers 62a, 62b, 62c flows between the three condensers 62a, 62b, 62c via the tie line 68. Therefore, the condenser pressures of the three condensers 62a, 62b, 62c are the same.

(7) The control unit 69 is configured to send the opening command signal SGop to each of the vacuum break valves 65a, 65b, 65c.

<Operations of Condenser Vacuum Breaker> Hereinafter, operations of the condenser vacuum breaker DVa will be described with reference to FIG. 6. FIG. 6 is a flowchart showing the operations of the condenser vacuum breaker DVa. Here, regarding the operations of the condenser vacuum breaker DVa, operations that a different from those of the condenser vacuum breaker DV according to the first embodiment will be mainly described. Therefore, regarding the same operations as the condenser vacuum breaker DV according to the first embodiment (see FIG. 2), the operations of the condenser vacuum breaker DV according to the first embodiment described above is replaced with the operations of the condenser vacuum break device DVa, and the detailed description thereof is omitted.

During normal operation in a nuclear power plant PLa, each of the condensers 62a, 62b, 62c is in the vacuum state. Each of the vacuum break valves 65a, 65b, 65c is in the closed state to maintain the vacuum state of the corresponding condensers 62a, 62b, 62c. The first pressure gauge 66 measures the building pressure and outputs a building pressure setpoint P66a indicating a measured value of the building pressure to the control unit 69. The second pressure gauge 67 measures the condenser pressure and outputs a condenser pressure setpoint P67a indicating a measured value of the condenser pressure to the control unit 69.

When the nuclear power plant PLa is suddenly stopped during normal operation, the operator of the control panel 71 stationed in the control room 70 operates the control panel 71 to output the vacuum break command SG71 from the control panel 71 to the control unit 69.

As shown in FIG. 6, when the vacuum break command SG71 is outputted from the control panel 71, the control unit 69 detects the vacuumbreak command SG71 (Step 3210). In response to the detection, the control unit 69 sends the opening command signal SGop at the initial stage to one of the vacuum break valves 65 to gradually open the vacuum break valve 65 while controlling the opening of the vacuum break valve 65 (Step 5220).

In the present embodiment, it is disclosed that the control unit 69 sends the opening command signal SGop to the vacuum break valve 65b in Step 5220. At this time, the control unit 69 controls the opening of the vacuum break valve 65b such that the building pressure (the building pressure setpoint 966a measured by the first pressure gauge 66) is maintained at a predetermined set value (the building pressure set value P66b (see FIG. 3) stored in advance in the storage unit M of the control unit 69).

At the initial stage of Step S220, the control unit 69 calculates an opening corresponding to the differential pressure between the building pressure setpoint P66a and the building pressure set value P66b as a default opening of the vacuum break valve 65b. Then, the control unit 69 generates an opening command signal SGop corresponding to the default opening and sends the opening command signal SGop to the vacuum break valve 65b. As a response, the opening of the vacuum break valve 65b is changed to an opening indicated by the opening command signal SGop at the initial stage.

After outputting the opening command signal SGop at the initial stage to the vacuum break valve 65b, the control unit 69 gradually opens the vacuum break valve 65b while controlling the opening of the vacuum break valve 65b based on the differential pressure between the condenser pressure and the building pressure. At this time, the control unit 69 calculates an opening of the vacuum break valve 65b corresponding to the differential pressure between the condenser pressure (the condenser pressure setpoint P67a) and the building pressure (the building pressure set value P66b), generates an opening command signal SGop corresponding to the calculated opening, and sends the opening command signal SGop to the vacuum break valve 65b. As a response, the opening of the vacuum break valve 65b is changed to the opening indicated by the opening command signal SGop.

After Step S220, the control unit 69 determines whether or not a predetermined time is elapsed (Step 5230). When it is determined in the decision point at Step 5230 that the predetermined time has elapsed (Ina case of "Yes") , the control unit 69 sequentially opens the remaining vacuum break valves 65 before each of the vacuum break valves 65a, 65b, 65c is fully opened (Step S240). When the vacuum break valves 65a, 65b, 65c are fully opened, breaking the vacuum state of the condensers 62a, 62b, 62c is completed.

When it is determined in the decision point at Step 3230 that the predetermined time has not elapsed (in a case of "No"), the control unit 69 determines whether or not a predetermined control completion condition is satisfied (Step 5250). When it is determined in the decision point at Step S250 that the control completion condition is not satisfied (in a case of "No"), the process returns to Step 5230.

After Step 3240 or when it is determined in the decision point at Step 3250 that the control completion condition is satisfied (in a case of "Yes"), processing of a series of routine is completed.

<First Modification of Operations ofCondenserVacuumBreaker> The condenser vacuum breaker DVa may perform the operations from FIG. 7 instead of the operations from FIG. 6. FIG. 7 is a flowchart showing the first modification of the operations of the condenser vacuum breaker DVa. Here, the difference in the operations between FIG. 7 and FIG. 6 will be mainly described.

The operations in FIG. 7 that is different from FIG. 6 is the step 3240 process that is performed instead of step 3240 process. As shown in FIG. 7, in Step 5240a, the control unit 69 simultaneously opens all the remaining vacuum break valves 65 before each of the vacuum break valves 65a, 65b, 65c is fully opened. When the vacuum break valves 65a, 65b, 65c are fully opened, breaking the vacuum state in the condensers 62a, 62b, 62c is completed.

<Second Modification of Operations of Condenser Vacuum Breaker> The condenser vacuum breaker DVa may perform the operations from FIG. 8 instead of the operations from FIG. 6. FIG. 8 is a flowchart showing the second modification of the operations of the condenser vacuum breaker DVa. Here, the difference in the operations between FIG. 8 and FIG. 6 will be mainly described.

As shown in FIG. 8, when the vacuum break command 5G71 is outputted from the control panel 71, the control unit 69 detects the vacuumbreak command SG71 (Step S310). In response to the detection, the control unit 69 sends the opening command signal SGop at the initial stage to one of the vacuum break valves 65 to gradually open the vacuum break valve 65 while controlling the opening of the vacuum break valve 65 (Step 5320).

In the modification, it is disclosed that the control unit 69 sends the opening command signal SGop to the vacuum break valve 65b in Step S320. The processing of step S320 is the same as the processing of step S220 in FIG. 6, and thus the description thereof is omitted here.

After Step S320, the control unit 69 calculates the differential pressure between the condenser pressure and the building pressure based on the condenser pressure (the condenser pressure setpoint P67a) and the building pressure (the building pressure setpoint P66a) (Step 5330).

Next, the control unit 69 determines whether or not the differential pressure between the condenser pressure (the condenser pressure setpoint P67a) and the building pressure (the building pressure setpoint P66a) reaches the predetermined setpoint Ppr (see FIG. 4) (Step 5340). When it is determined in the decision point at Step S340 that the differential pressure reaches the setpoint Ppr (see FIG. 4) (in a case of "Yes"), the control unit 69 sequentially opens the remaining vacuum break valves 65 before each of the vacuum break valves 65a, 65b, 65c is fully opened (Step S350) . When the vacuum break valves 65a, 65b, 65c are fully opened, breaking the vacuum state of the condensers 62a, 62b, 62c is completed.

When it is determined in the decision point at Step S340 that the differential pressure does not reach the setpoint Ppr (see FIG. 4) (in a case of "No"), the control unit 69 determines whether or not a predetermined control completion condition is satisfied (Step 5360). When it is determined in the decision point at Step 3360 that the control completion condition is not satisfied (in a case of "No"), the process returns to Step 5330.

After Step 5350 or when it is determined in the decision point at Step 3360 that the control completion condition is satisfied (in a case of "Yes"), processing of a series of routine is completed.

<Third Modification of Operations of Condenser Vacuum Breaker> The condenser vacuum breaker DVa may perform the operations from FIG. 9 instead of the operations from FIG. 8. FIG. 9 is a flowchart showing the third modification of the operations of the condenser vacuum breaker DVa. Here, the difference in the operations between FIG. 9 and FIG. 8 will be mainly described.

The operation in FIG. 9 that is different from FIG. 6 is the processing of Step 5350a, which is performed instead of the processing in Step 5350. As shown in FIG. 9, in Step 5350a, the control unit 69 simultaneously opens all the remaining vacuum break valves 65 before each of the vacuum break valves 65a, 65b, 65c is fully opened. When the vacuum break valves 65a, 65b, 65c are fully opened, breaking the vacuum state of the condensers 62a, 62b, 62c is completed.

Such a condenser vacuum breaker DVa having a configuration that includes a plurality of steam turbines 61 and a plurality of condensers 62 can obtain function effects same as the condenser vacuum breaker DV according to the first embodiment. That is, even when the vacuum break valve 65 is opened during vacuum break in the condenser 62, such a condenser vacuum breaker DVa can prevent the air in the building (the turbine building 60) from being rapidly sucked into the condenser 62 side. Therefore, the condenser vacuum breaker DVa can break the vacuum state of the condenser 62 while maintaining the building pressure (the turbine building pressure) at a constant set value (the building pressure set value P66b (see FIG. 3)). In such a condenser vacuum breaker DVa, the temporary decrease in the building pressure (the pressure inside the turbine building) can be prevented. As a result, the condenser vacuum breaker DVa can prevenu the lube oil used in the bearing box of the rotor of the steam turbine 61 or the generator (not shown) or the like from leaking from the bearing box into the turbine building 60.

As described above, according to the condenser vacuum breaker DVa based from the second embodiment having the configuration including the plurality of steam turbines 61 and the plurality of condensers 62, similarly to the condenser vacuum break device DV according to the first embodiment, even when the vacuum break valve 65 is opened during the vacuum break in the condenser 62, the temporary decrease in the building pressure (the pressure inside the turbine building) can be prevented.

The invention is not limited to the above-described embodiments, and includes various modifications. For example, the embodiments described above are described in detail for easy understanding of the invention, and the invention is not necessarily limited to the embodiment including all the configurations described above. Apart of the configurations of one embodiment can be replaced with a configuration of another embodiment, and the configuration of one embodiment can also be added to the configuration of another embodiment.

In addition, a part of each configuration may be added to, deleted from, or replaced with another configuration.

Claims

CLAIMS1. A condenser vacuum breaker comprising: a vacuum break valve provided in the air intake line of a condenser; a first pressure gauge configured to measure the building pressure inside a building where the condenser is provided; and a control unit configured to control the operation of a vacuum break valve, wherein the control unit closes the vacuum break valve in order to maintain the vacuum state in the condenser during normal operation, and when a vacuum break command is detected, the control unit opens the vacuum break valve while controlling an opening such that the building pressure is maintained at a predetermined set value.
2. The condenser vacuum breaker according to claim 1, further comprising: a second pressure gauge configured to measure the condenser pressure inside a condenser, wherein after the vacuum break operation in the condenser is started, the control unit fully opens the vacuum break valve when a differential pressure between the condenser pressure and the building pressure reaches a predetermined setpoint.
3. The condenser vacuum breaker according to claim 1, wherein a plurality of vacuum break valves are provided, the control unit closes all of the vacuum break valves in order to maintain the vacuum state of the condenser during the normal operation, when a vacuum break command is detected, the control unit opens one of vacuum break valves, and when a specified time is elapsed after one of the vacuum break valves is opened, the control unit sequentially opens the remaining vacuum break valves.
4. The condenser vacuum breaker according to claim 1, wherein a plurality of the vacuum break valves are provided, the control unit closes all of the vacuum break valves in order to maintain the vacuum state of the condenser during the normal operation, when a vacuum break command is detected, the control unit opens one of the vacuum break valves, and when a specified time is elapsed after one of the vacuum break valves is opened, the control unit simultaneously opens all of the remaining vacuum break valves.
5. The condenser vacuum breaker according to claim 1, wherein a plurality of the vacuum break valves are provided; and a second pressure gauge configured to measure the condenser pressure inside the condenser is further provided, the control unit closes all of the vacuum break valves in order to maintain the vacuum state of the condenser during normal operation, when a vacuum break command is detected, the control unit opens one of the vacuum break valves, and after one of the vacuum break valves is opened, the control unit sequentially opens the remaining vacuum break valves when the differential pressure between the condenser pressure and the building pressure reaches a predetermined setpoint.
6. The condenser vacuum breaker according to claim 1, wherein a plurality of vacuum break valves are provided, a second pressure gauge configured to measure a condenser pressure inside the condenser is further provided, the control unit closes all of the vacuum break valves in order to maintain the vacuum state of the condenser during the normal operation, when a vacuum break command is detected, the control unit opens one of the vacuum break valves, and after one of the vacuum break valves is opened, the control unit simultaneously opens all of the remaining vacuum break valves when the differential pressure between the condenser pressure and the building pressure reaches a predetermined setpoint.