JP2002115807A - Driving turbine operation method for boiler feedwater pump, and its operation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the difficulty with prior art that when high temperature high pressure main steam is used upon turbine extraction steam air being lost to drive a feedwater pump drive turbine, exhaust steam temperature of the feedwater pump drive turbine becomes higher than a predetermined value to result in the possibility that it exceeds allowable temperature of a condenser. SOLUTION: A feedwater pump driving turbine operation method is adapted such that steam produced in a boiler is supplied to a high pressure steam turbine, and exhaust steam from the turbine is re-heated in a re-heating unit and is then supplied to a medium pressure steam turbine, and further exhaust steam from the medium pressure steam turbine is supplied to a low pressure steam turbine. Further, exhaust steam from the low pressure steam turbine is condensed, and the condensed water is supplied to the boiler with the aid of a feedwater pump driven by the steam turbine. In the method, extracted steam of the steam turbine is supplied to the feedwater pump driving turbine as driving steam upon ordinary operation, while upon load rapidly reducing operation part of the steam turbine exhaust supplied to the re-heating unit is diverted and supplied to the feedwater pump driving turbine as driving steam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for operating a drive turbine for a boiler feed pump.

[0002]

2. Description of the Related Art A conventional method of operating a drive turbine for a boiler feedwater pump and an apparatus for operating the same will be described with reference to FIG. FIG. 9 is a diagram illustrating an example of a system configuration of the thermal power plant. In this power generation plant, steam is generated in a boiler 1, and the steam passes through main steam pipes 2 and 3, is guided to a main steam control valve 4, and flows into a high-pressure turbine 5.
The high-pressure turbine exhaust that has completed expansion work in the high-pressure turbine 5 passes through the low-temperature reheat steam pipe 6, is returned to the boiler 1 again, and is reheated by the reheater RH.

[0003] The reheated steam passes through a high-temperature reheat steam pipe 7, is guided to a reheat steam valve 8, and flows into a medium-pressure turbine 9. The intermediate pressure turbine exhaust having completed the expansion work in the intermediate pressure turbine 9 passes through the crossover pipe 10 and flows into the low pressure turbine 11. Then, the generator 12 is driven by the rotational torque generated at the time of expansion work in the high-pressure turbine 5, the medium-pressure turbine 9, and the low-pressure turbine 11.

[0004] Turbine exhaust that has completed expansion work in the low-pressure turbine 11 is condensed in a condenser 13 to be condensed at normal temperature. This condensate passes through a condensate pipe 14 and is led to a condensate pump 15 where it is pressurized. This pressurized condensed water becomes water supply, passes through a water supply pipe 16 and is guided to a low-pressure water heater 17, where heat exchange is performed with turbine bleed air (not shown).
The water passes through the water supply pipe 18 and flows into the deaerator 19.

The degassing steam obtained by diverting the bleed air from the intermediate pressure turbine 9 passes through the bleed steam pipes 20 and 21 and the check valve 22 and is guided to the deaerator 19. However, the medium pressure turbine 9
Is lost, the auxiliary steam from the auxiliary steam header 23 passes through the auxiliary steam pipe 24 and the control valve 25 and is guided to the deaerator 19.

The deaerator 19 performs heat exchange between the feed water and the steam for deaeration, and the deaerated feed water passes through a feed pipe 26 and is then driven by a boiler feed pump 2 driven by a turbine 31 described later.
7 and the pressure is increased here. The pressurized feed water passes through a feed pipe 28, is guided to a high-pressure feed water heater 29, exchanges heat with turbine bleed air (not shown), and is fed to the boiler 1 through a feed pipe 30.

On the other hand, turbine bleed air obtained from the bleed steam pipe 20 is supplied to the bleed steam pipe 3 communicating with the bleed steam pipe 20.
2. It flows into the boiler feed pump drive turbine 31 via the check valve 33 and the low pressure control valve 34. Turbine exhaust that has completed expansion work in the boiler feed pump driving turbine 31 is sent to the condenser 13 via a condenser pipe (not shown), where it is condensed and condensed and returned to the above-described feed / condensate system.

As the steam system for driving the boiler feed pump drive turbine 31, there are two other steam systems in addition to the above-described steam system using turbine bleeding used during normal operation.

The first is a high-pressure system in which main steam branched from the main steam pipe 2 is guided to a high-pressure control valve 36 by a high-pressure steam pipe 35 and flows into a drive turbine 31 for a boiler feed pump. This system can be used for load shedding or site-only operation (FC
This is used when the turbine bleed is lost due to a sudden decrease in the generator operation load such as during B: First Cut Back.

The high-pressure control valve 36 and the low-pressure control valve 34 have valve opening characteristics determined in a desired relationship. When one of the valves has a desired opening, the other valve starts to open in conjunction with the other. It is configured. This is referred to as a split range relationship between the two valves. In the case of FIG. 9, the opening degree of the low-pressure control valve 34 and the high-pressure control valve 36 is adjusted by the oil cylinder stroke of the control valve oil cylinder 39 to control the flow rate of the supply water flowing into the boiler 1.

The second is a system in which auxiliary steam from the auxiliary steam header 23 is guided to the low-pressure control valve 34 via the auxiliary steam pipe 37 and the control valve 38 and flows into the drive turbine 31 for the boiler feed pump. They are used when the temperature rises.

Here, the reason why turbine bleeding is lost during a sudden load reduction operation such as during load shedding or in-station independent operation is as follows.
In addition to narrowing down the fuel to be supplied to the boiler 1 to rapidly reduce the load, the main steam control valve 4 of the high-pressure turbine 5 and the reheat control valve 8 of the intermediate-pressure turbine 9 are rapidly closed to prevent overspeed of the steam turbine. At the same time, when the high-pressure bypass valve 40 and the low-pressure bypass valve 41 are opened, the amount of steam flowing into the intermediate-pressure turbine 9 decreases.

That is, the steam generated in the boiler 1 passes through the main steam pipe 2 and the main steam pipe 3 and is guided to the high-pressure bypass valve 40, passes through the high-pressure bypass steam pipe 42 and the low-temperature reheat steam pipe 6, and is returned again. The steam is returned to the boiler 1, is not flown into the intermediate-pressure turbine 9, passes through the high-temperature reheat steam pipe 7 and the low-pressure bypass steam pipe 43, is guided to the low-pressure bypass valve 41, and flows into the condenser 13. It is.

When the main steam flows through the high-pressure bypass pipe 42, the cooling water extracted from the water supply pump 27 is passed through the spray water pipe 44 to the control valve 45, and sprayed into the high-pressure bypass pipe 42. By reducing the temperature, the low-temperature reheat steam passing through the low-temperature reheat steam pipe 6 is cooled to a predetermined temperature.

[0015]

The above-mentioned prior art has the following problems. That is, when the load is suddenly reduced, such as during load shedding or in-house operation, the turbine bleeding is lost, so the high-temperature, high-pressure main steam is used to drive the drive turbine 31 for the boiler feed pump. There is a possibility that the exhaust gas temperature of the drive turbine 31 becomes higher than a predetermined value and exceeds the allowable temperature of the condenser 13.

When the turbine exhaust temperature becomes higher than a predetermined value, the auxiliary steam is guided from the auxiliary steam header 23 to the low-pressure regulator 34 via the auxiliary steam pipe 37 and the control valve 38, and is driven by the drive turbine for the boiler feed pump. 31 is driven. That is, it is necessary to switch and operate the drive steam system of the drive turbine 31 for the boiler feed pump.

As a result, three systems for supplying turbine bleed air, main steam, and auxiliary steam are required as drive steam systems for the drive turbine 31 for the boiler feed pump, and the system configuration and operation method are complicated. Further, the system for supplying the main steam to the drive turbine 31 for the boiler feed pump has a problem that the material cost is high due to high temperature and high pressure.

Accordingly, the present invention drives the boiler feed pump drive turbine 31 by using low-temperature reheat steam or auxiliary steam during a load reduction operation such as a load rejection operation or a stand-alone operation in a station, thereby reducing the turbine exhaust temperature to a predetermined value. It is an object of the present invention to provide an operating method of a drive turbine for a boiler feed pump and an operating device for the same, in which the system configuration and the operating method are simplified to reduce the material cost.

[0019]

In order to achieve the above object, the invention of a driving turbine operating method for a boiler feed pump according to claim 1 supplies the steam generated in the boiler to a high-pressure steam turbine to reduce the expansion work. After the exhaust gas is reheated by a reheater, it is supplied to a medium-pressure steam turbine for expansion work, and the exhaust gas of this medium-pressure steam turbine is supplied to a low-pressure steam turbine for expansion work. In the condensed water, after the condensed water is supplied, the boiler water supply pump drive turbine operation method for supplying water to the boiler by a boiler water supply pump driven by a steam turbine, during normal operation,
The steam turbine exhaust gas is supplied as drive steam to the drive turbine for the boiler feed pump, and during a rapid load reduction operation, a part of the steam turbine exhaust supplied to the reheater is diverted,
Since the boiler feed pump is supplied as drive steam to the drive turbine, the turbine exhaust temperature can be set to a predetermined temperature or less, and a system for supplying main steam to the boiler feed pump drive turbine is provided. Since it is not employed, not only can material costs required for expensive pipes and valves for high temperature and high pressure be reduced, but also an operation method that simplifies the system configuration and operation method can be provided.

Further, the invention of a drive turbine operating apparatus for a boiler feedwater pump according to claim 2 is to supply steam generated in the boiler to a high-pressure steam turbine, reheat the exhaust gas by a reheater, and then reheat the medium-pressure steam. The steam is supplied to the turbine for expansion work, the exhaust of the medium-pressure steam turbine is supplied to the low-pressure steam turbine to perform expansion work, and then condensed by the condenser. In a drive turbine operating device for a boiler feed pump configured to supply water to the boiler by a feed water pump, during normal operation, a turbine bleed system that supplies bleed air of the steam turbine to the feed water pump drive turbine as drive steam, and a rapid load reduction operation At this time, a part of the steam turbine exhaust supplied to the reheater is diverted, and the low temperature reheat is supplied as drive steam to the feedwater pump drive turbine. The system is equipped with an air system, so that the turbine exhaust temperature is reduced to a predetermined temperature or less by driving the drive turbine for the boiler feed pump using the low-temperature reheat steam when the load is suddenly reduced, such as during load shedding or in-house operation alone. In addition, since the system for supplying the main steam to the drive turbine for the boiler feed pump is not used, the material cost required for expensive high-temperature and high-pressure pipes and valves can be reduced. Instead, the system configuration can be simplified.

According to a third aspect of the present invention, a control valve is provided in the low-temperature reheat steam system, and a detector for detecting a steam pressure or a steam flow rate is provided, so that the load is rapidly reduced. During operation, a control device is provided which outputs a valve opening command value obtained by comparing a set value with a detection value of the detector.

Further, the invention of the drive turbine operating device for a boiler feed pump according to claim 4 provides a valve opening command value which is maintained in a fully closed state during a normal operation from the start of a sudden load reduction operation to a scheduled time. Provided a control device for outputting to the control valve a valve opening command value of a predetermined opening, and a valve opening command value of the opening obtained from the set value and the detected value after the scheduled time has elapsed. In this case, the responsiveness of the switching of the driving steam is improved, and the decrease in the discharge flow rate of the water supply pump 27 that occurs at the time of the switching can be reduced. Therefore, the loss of water supply and the burning of the boiler 1 can be prevented. After that, since a function of adjusting the driving steam pressure to a predetermined pressure is provided, an inlet pressure necessary for driving the feedwater pump driving turbine 31 can be secured.

According to a fifth aspect of the present invention, there is provided a drive turbine operating device for a boiler feedwater pump, wherein a steam stop valve is provided between the control valve and the low pressure control valve provided in the low temperature reheat steam system. A control device is provided that outputs a valve opening command value for closing the steam stop valve during operation and a valve opening command value for opening the steam stop valve during rapid load reduction operation. Since the reheated steam flows into the boiler feedwater pump drive turbine and is driven, the responsiveness of switching the drive steam is improved, and a decrease in the discharge flow rate of the feedwater pump 27 that occurs at the time of the switchover can be reduced. Loss of water supply and burnout can be prevented. In addition, when the driving steam pressure falls below the predetermined pressure, a function of adjusting the pressure to the predetermined pressure is provided, so that the inlet pressure required to drive the boiler feed pump driving turbine 31 can be secured. Further, the invention of a driving turbine operating method for a boiler feedwater pump according to claim 6 supplies the steam generated in the boiler to a high-pressure steam turbine, reheats the exhaust gas with a reheater, and then supplies the exhaust gas to a medium-pressure steam turbine. After the expansion work is performed, the exhaust of the medium-pressure steam turbine is supplied to the low-pressure steam turbine to perform the expansion work, and then the condensate is condensed.The condensate is used as feed water, and the turbine-driven boiler feed pump is used. In a drive turbine for a water supply pump of a power plant that is caused to flow into the boiler, a low-temperature reheat steam system for diverting a part of the exhaust gas of the high-pressure steam turbine and supplying it as drive steam to the drive turbine for the boiler water supply pump, An auxiliary steam system for supplying auxiliary steam of the auxiliary steam header as drive steam to the drive turbine for the boiler feed pump, during normal operation and during rapid load reduction operation. Drive steam is supplied from the low-temperature reheat steam system and / or the auxiliary steam system, and during normal operation and load shedding or in-house operation, the boiler feed water is supplied using the low-temperature reheat steam. When the driving steam flow rate becomes insufficient while the pump driving turbine is driven, the output of the control arithmetic unit is further increased, and the insufficient steam amount from the auxiliary steam system can be compensated.

Further, the invention of a drive turbine operating apparatus for a boiler feed pump according to claim 7 is to supply steam generated in the boiler to a high-pressure steam turbine, heat the exhaust gas by a reheater, and then heat the steam into a medium-pressure steam turbine. To the low-pressure steam turbine for expansion work, and then condensed by a condenser.The condensate is then supplied to the turbine and fed to a turbine-driven boiler. In a drive turbine operating device for a boiler feedwater pump configured to supply water to a boiler by a pump, a low-temperature reheat steam system for diverting a part of the exhaust gas of the high-pressure steam turbine and supplying it as drive steam to a drive turbine for the boiler feedwater pump. An auxiliary steam system for supplying auxiliary steam of the auxiliary steam header as drive steam to the drive turbine for the boiler feed pump, and the low-temperature reheat steam system and the auxiliary steam system. Control valves provided in both of the steam systems, and two types of valve opening command values obtained by comparing a set value and a detection value from the driving steam and having opening characteristics obtained in a predetermined relationship, A control device that outputs the control steam to the control valve of the boiler feed pump during normal operation and during load shedding or in-house independent operation, and when driving the boiler feed pump drive turbine using one of the steams. Is short, the shortage of steam from the other steam system can be compensated.

Further, according to the invention of a driving turbine operating method for a boiler feed pump according to claim 8, the steam generated in the boiler is supplied to a high-pressure steam turbine to perform expansion work, and the exhaust gas is heated by a reheater. Pressure steam turbine,
A boiler of a power plant in which the exhaust of the medium-pressure steam turbine is supplied to a low-pressure steam turbine to perform expansion work, then condensed by a condenser, and the condensate is supplied to the boiler by a turbine-driven water supply pump. In a feed turbine for a feed water pump, a turbine extraction system for supplying bleed air of the intermediate-pressure steam turbine to the drive turbine for the boiler feed pump as drive steam, and a part of the exhaust gas of the high-pressure steam turbine for diverting a part of the exhaust gas for the boiler feed pump A low-temperature reheat steam system for supplying drive steam to the drive turbine and an auxiliary steam system for supplying the steam of the auxiliary header to the drive turbine for the boiler feed pump. During normal operation, drive steam is supplied from the turbine bleed system. During a sudden load reduction operation, drive steam is supplied from the low-temperature reheat steam system and / or the auxiliary steam system. When the driving steam flow rate is insufficient during normal operation and load shedding or in-house operation alone, when driving the boiler feed pump driving turbine 31 using low-temperature reheat steam, In addition, the control signal 95 is further increased to compensate for the shortage of steam from the auxiliary steam system. When the auxiliary steam is mainly used, the low-temperature reheat steam will make up for the shortfall.

Further, the invention of a drive turbine operating device for a boiler feed pump according to claim 9 is to supply steam generated in the boiler to a high-pressure steam turbine for expansion work, and to heat the exhaust gas by a reheater. , Supply expansion work to the medium-pressure steam turbine, supply the exhaust of the medium-pressure steam turbine to the low-pressure steam turbine for expansion work, condensate in the condenser, and condensate this condensate pump In the boiler feed pump drive turbine of the power plant, in which the boiler is supplied with water by increasing the pressure in the boiler with a turbine-driven water supply pump, the bleed air of the steam turbine is supplied to the boiler feed pump drive turbine during normal operation. A turbine extraction system for supplying driving steam, and auxiliary steam from the auxiliary steam header at the time of a rapid load reduction operation. And a control valve provided in the auxiliary steam system, and a valve opening degree command obtained by comparing a detection value detected from the auxiliary steam system with a set value to the control valve. In this embodiment, the auxiliary steam can be adjusted to a predetermined pressure or flow rate and supplied as drive steam for the drive turbine for the boiler feedwater pump.

Further, the invention of a drive turbine operating device for a boiler feed pump according to claim 10 is characterized in that a steam stop valve provided at an outlet side of a control valve provided in the auxiliary steam system, and a steam stop valve provided during normal operation. A valve opening command value for fully closing the valve and holding the control valve at a predetermined opening is output.During a sudden load reduction operation, the steam stop valve is opened, and the driving steam pressure is lower than a predetermined pressure. There is provided a control device that outputs a valve opening command value obtained by comparing a set value and a detected value when the value decreases.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a thermal power plant will be described below with reference to the drawings. In each embodiment, the same reference numerals are given to the portions corresponding to the components in the drawings described above, and the duplicated description is omitted except for the main part.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
It is a figure showing an embodiment. In FIG.
Similarly, one end of the first bleed steam pipe 20 is connected to the bleed port of the intermediate-pressure turbine 9, and the other end is connected in series to the second bleed steam pipe 32 provided with a check valve 33 in the middle part, and the low-pressure control valve 34 is connected. Connect to the entrance of. The low pressure control valve 34 is provided with a control valve oil cylinder 39.
The valve opening is adjusted by the stroke of the oil cylinder.

The steam system from the turbine bleed port to the low pressure control valve 34 is called a turbine bleed system, and constitutes a drive steam system for supplying the bleed air of the medium pressure turbine 9 to the drive turbine 31 for the boiler feed pump during normal operation. Is what you do. Although the drawing shows the case where the bleed air of the medium pressure turbine is used, when the bleed air is obtained from the high pressure turbine, a bleed port may be provided in the high pressure turbine.

On the other hand, a steam pipe 4 having a control valve 47 at an intermediate portion with respect to a connection portion of the low temperature reheat steam pipe 6 with the reheater RH.
6 is connected to the inlet of the low-pressure control valve 34, and the other end is connected to the drive steam system of the drive turbine 31 for the boiler feed pump when turbine bleeding is lost. This steam system is called a low temperature reheat steam system.

Reference numeral 48 denotes a control device for adjusting the drive steam pressure of the drive turbine 31 for the boiler feed pump using the control valve 47, and a pressure detector provided on the low pressure control valve 34 side of the steam pipe 46. Actual pressure signal 5 detected at 49
0 and the pressure set value 51 are input to a deviation calculator 52 to calculate a deviation signal 53, and the deviation signal 53 is calculated by the control calculator 5.
4, the valve opening command value 5 for the control valve 47
5 is output.

Next, the operation of the present embodiment will be described. During normal operation, the bleed air of the intermediate pressure turbine 9 is guided to the low pressure control valve 34 via the first and second bleed steam pipes 20 and 32, and the steam amount is adjusted by this valve to be input to the drive turbine 31 for the boiler feed pump. Is done. Accordingly, the drive turbine 31 for the boiler feedwater pump is driven at a desired rotation speed, and by driving the feedwater pump 27, the feedwater is supplied to the boiler 1 via the high-temperature feedwater superheater 29.

On the other hand, when the turbine bleed air is lost, such as when the load is cut off or in the station alone, the set value 51 of the controller 48 is set.
A valve opening command value 55 for the control valve 47 is output based on a deviation signal 53 between the control valve 47 and the actual pressure signal 50, and the control valve 47 is opened.

Thus, the low-temperature reheat steam branched from the low-temperature reheat steam pipe 6 is guided to the low-pressure control valve 34 through the steam pipe 46 and the control valve 47, and is driven by the boiler feed pump driving turbine 3
1 to drive it. At this time, since the low-temperature reheated steam is higher than the extracted steam pressure of the intermediate-pressure turbine 9, the check valve 33 prevents the turbine 9 extracted air from flowing into the boiler feed pump drive turbine 31.

The low-temperature reheated steam described in the present embodiment refers to steam including turbine exhaust and high-pressure turbine bypass steam flowing into the reheater RH of the boiler 1, so that the low-temperature reheated steam is cooled at a low temperature. Instead of branching and supplying from the hot steam pipe 6, turbine bypass steam may be cooled to a predetermined temperature by water feed spray and branched and supplied from the high-pressure bypass steam pipe 42 on the outlet side of the high-pressure bypass valve 40. A similar effect is obtained.

As described above, according to the present embodiment, the drive turbine 31 for the boiler feed water pump is driven by using the low-temperature reheat steam when the turbine bleed air is lost such as when the load is cut off or when the station is operated alone. Therefore, the turbine exhaust temperature can be made equal to or lower than a predetermined temperature.

A steam pipe 3 for supplying the main steam shown in FIG. 9 of the prior art to the drive turbine 31 for the boiler feed pump.
5 and the high-pressure and high-pressure steam system including the high-pressure control valve 36 can be eliminated, so that not only can material costs of expensive high-temperature and high-pressure piping and valves be reduced, but also the system configuration and operation method Can be simplified.

Further, when the turbine bleed air is lost, for example, when the load is cut off or the plant is operated alone, the low-temperature reheated steam is adjusted to a predetermined pressure or flow rate to drive the boiler feed pump drive turbine 31.
This can provide the effect of supplying the steam as the driving steam for the fuel cell.

In the above description, the case where the pressure detector 49 is provided in the steam system of the steam pipe 46 has been described, but a flow rate detector may be provided instead of the pressure detector. In this case, the set value 51 is naturally a flow set value.

(Second Embodiment) FIG. 2 shows a second embodiment, in which the control logic of the control device 48 in the first embodiment is further enhanced. Since there is no particular change, the description is omitted.
In the present embodiment, the reference numeral of the control device is 48A.

The concept of the control device 48A will be described first. The control device 48A outputs a valve opening command value 55 for fully closing the control valve 47 during normal operation, and firstly opens the control valve 47 to a predetermined opening during operation when turbine bleeding is lost. A valve opening command value 55 for adjusting the driving steam pressure to a predetermined pressure by using the control valve 47 is output.

Next, an example of a control block of the control device 48A will be described in detail. The actual pressure signal 50 and the set value 51 from the pressure detector 49 are input to a deviation calculator 52 to obtain a deviation signal 53. Next, the deviation signal 53 is input to a control calculator 54 to obtain a control signal 60.

Then, the control signal 60 and the predetermined opening signal 61 are inputted to the first switch 62. This first switch 6
2 is configured to switch and output an input signal when an output 64 of the on-delay timer 63 is input, and output a predetermined opening signal 61 during a normal operation, and perform a load shedding operation or an in-house independent operation. After the detection signal 65 is generated, the control signal 61 is switched to the control signal 60 after a predetermined time period when the on-delay timer 63 operates, and the control signal 60 is output as the control signal 66.

The control signal 66 is input to the second switch 67 in the next stage. The second switch 67 is configured to also input a fully-open signal 68 in addition to the control signal 66. During normal operation, the fully-open signal 68 is output as the valve opening command value 55, so that the load can be cut off or the station can be operated alone. As soon as the detection signal 65 is input, the switching operation is performed, and the control signal 66 is changed to the valve opening command value 5.
It operates to output as 5.

In the present embodiment, in addition to the operation of the first embodiment, the control valve 4 is immediately operated when the turbine bleed air is lost, such as when the load is cut off or in the station alone.
7 is rapidly opened to a predetermined opening, and the low-temperature reheated steam flows into and drives the drive turbine 31 for the boiler feed pump.

As a result, the responsiveness of the switching of the driving steam is improved, and a decrease in the discharge flow rate of the water supply pump 27 that occurs at the time of the switching can be reduced. After that, since a function of adjusting the driving steam pressure to a predetermined pressure is provided, an inlet pressure necessary for driving the boiler feed pump driving turbine 31 can be secured.

(Third Embodiment) FIG. 3 is a diagram showing a third embodiment of the present invention. In FIG. 3, in addition to the first and second embodiments described above, a steam stop valve 70 is provided on the outlet side of the control valve 47.
And a control device 71 for controlling the steam stop valve 70.

First, the control device 71 will be described from the conceptual function. The control device 71 sets the steam stop valve 70 to “fully closed” with respect to the steam stop valve 70 and the control valve 47 during the normal operation of the drive turbine 31 for the boiler feed pump.
And a valve opening command value 73 that keeps the control valve 47 at a "predetermined opening".

During a sudden load reduction operation such as a load cut-off operation or a stand-alone operation in a station, turbine bleeding is lost. In such an operation, a valve opening command value 72 for opening the steam stop valve 70 is output, and further driving is performed. When the steam pressure falls below a predetermined pressure, the control valve 47 is used to output a valve opening command value 73 for adjusting the driving steam pressure to a predetermined pressure.

Next, the details of the control block of the control device 71 will be described. First, an element 71-1 for outputting the valve opening command value 72 to the steam stop valve 70 will be described. A third switch 74 outputs a valve opening command value 72 to the steam stop valve 70, and a "full close" signal 75
And a signal 76 of "full open", and these two input signals are converted to a signal 6 generated during load shedding or in-house isolated operation.
5 and the full open signal 76 is output as the valve opening command value 72. The steam stop valve 70 is fully opened by the valve opening command value 72.

Next, the element 7-2 for outputting the valve opening command value 79 to the control valve 47 will be described. Setting value 7
7 and the actual pressure signal 50 from the pressure detector 49 are input to a deviation calculator 78 to calculate a deviation signal 79. The deviation signal 79 is input to the control calculator 80, and the control signal 81 is output. The control signal 81 and a predetermined opening signal 82
Is input to the switch 83.

On the other hand, reference numeral 84 denotes an AND circuit, which receives both the signal 65 generated during the load shedding or the in-house isolated operation and the signal 85 output under the condition that the driving steam pressure is lower than a predetermined pressure. The output signal 86 is input to the fourth switch 83 as a switch signal in the state where the switch is in the ON state.

Next, the operation of the present embodiment will be described. During the normal operation, the input condition of the AND circuit 84 is not satisfied, so that the fourth switch 83 outputs the predetermined opening signal 8 as shown in FIG.
2 to the control valve 47,
The control valve 47 is open at a predetermined opening. On the other hand, "fully closed"
, The steam stop valve 70 is fully closed. Therefore, the low-temperature reheat steam is not introduced into the low-pressure control valve 34 during the normal operation.

When the load is interrupted or the station is operated alone, the third switch 74 is switched by the signal 65 to output a fully-opened opening command value. Thereby, the steam stop valve 70 is fully opened. On the other hand, when the bleed pressure (driving steam pressure) becomes lower than the predetermined pressure during the load shedding or the single-station operation, an output 86 is generated from the AND circuit 84 and the fourth switch 8
Change 3 Therefore, the control valve 47 outputs the control signal 81
Is opened by the valve opening degree based on the valve opening command value 73 corresponding to the above. As a result, the low-temperature reheated steam flows into the drive turbine 31 for the boiler feed pump via the control valve 47, the steam stop valve 70, and the low-pressure control valve 34, and drives it.

In the present embodiment, the first or second
In addition to the operation of the embodiment, as soon as the steam stop valve 70 is opened, the low-temperature reheated steam is supplied to the drive turbine 31 for the boiler feed pump.
Since the drive flow is performed by flowing into the steam generator, the responsiveness of the switching of the drive steam is improved, so that the decrease in the discharge flow rate of the feed water pump 27 that occurs at the time of the switching can be reduced, and the loss of water supply and the burning of the boiler 1 can be prevented.

Further, when the driving steam pressure falls below a predetermined pressure, a function of adjusting the pressure to the predetermined pressure is provided, so that an inlet pressure required for driving the boiler feed pump driving turbine 31 can be secured. (Fourth Embodiment) FIG. 4 is a view showing a fourth embodiment of the present invention. The difference from the first to third embodiments is that the space between the auxiliary steam header 23 and the steam pipe 46 is different. Are connected by an auxiliary steam pipe 37 provided with a control valve 38, and are opened and closed in a split range by a control device 90 so that the valve opening degrees of the two control valves 47 and 38 are maintained in a predetermined relationship. is there.

In both normal operation and load shedding or in-house operation, at least one of the low-temperature reheat steam from the low-temperature reheat steam pipe 6 and the auxiliary steam from the auxiliary steam header 23 is supplied. , And can be supplied to the drive turbine 31 for the boiler feed pump via the low pressure control valve 34.

The control device 90 controls the actual pressure signal 50 from the pressure detector 49 installed in the steam pipe 46 and the pressure set value 9.
1 is input to a deviation calculator 92 to obtain a deviation signal 93. The deviation signal 93 is input to a control calculator 94, and a control signal 9
5, the control signal 95 is input to the first function generator 96 and the second function generator 97, respectively, and the valve opening command value 98 for the control valve 47 and the valve opening command value for the control valve 38 are output. 99 are output.

The first function generator 72 and the second function generator 72
The function of the function generator 73 is set in advance so that the valve opening characteristics of the control valve 47 and the control valve 38 have a desired relationship. When the valve is fully opened, the other valve starts to open in conjunction with it.

For example, the function of each of the function generators 72 and 73 is such that the control valve 47 starts to be opened after the control valve 47 is fully opened or the controllability is improved, as shown by the solid line in the characteristic diagram of FIG. For this reason, the control valve 47
When the desired opening degree is reached in the fully opened state, the control valve 38 starts to be opened.

Since the present embodiment is configured as described above, it can be used during normal operation and during load shedding or in-house independent operation.
When the driving steam flow rate becomes insufficient while driving the boiler feed pump driving turbine 31 using the low-temperature reheated steam, the control signal 95 is further increased to compensate for the insufficient steam amount from the auxiliary steam system. it can. When the auxiliary steam is mainly used, the low-temperature reheat steam will make up for the shortfall.

The boiler feed pump drive turbine 3
Because the main steam is not adopted as the steam system to supply to 1,
Not only can the turbine exhaust temperature be kept below a predetermined temperature, but also material costs can be reduced because expensive high-temperature and high-pressure piping and valves are not required.

(Fifth Embodiment) FIG. 6 shows a fifth embodiment of the present invention. The drive steam system of the drive turbine 31 for the boiler feed pump is a low-temperature reheat steam system shown in FIG. And a drive steam system comprising an auxiliary steam system and the turbine bleed system of FIG.

In the present embodiment, although a control valve and a control device for controlling the control valve are not particularly shown in the drive steam system including the low-temperature reheat steam system and the auxiliary steam system, the drive turbine 31 for the boiler feed pump is usually During operation, the turbine is driven by bleeding of the intermediate-pressure turbine, and when turbine bleeding is lost, such as when a load is cut off or in-house operation is performed, the turbine is driven by at least one of low-temperature reheat steam and auxiliary steam.

In this embodiment, during load shedding or in-house operation, the turbine exhaust temperature is controlled to a predetermined value by driving the boiler feed pump drive turbine 31 using at least one of the low-temperature reheat steam and the auxiliary steam. Below the temperature.

Further, since a steam system for guiding the main steam to the drive turbine 31 for the boiler feed pump is not employed, expensive high-temperature and high-pressure piping and valves are not required, and the material cost can be reduced accordingly. It is possible.

(Sixth Embodiment) FIG. 8 shows a seventh embodiment of the present invention. As a drive steam system for a drive turbine 31 for a boiler feed pump, the bleed air of the intermediate-pressure turbine 9 is extracted by a bleed steam pipe 20. Through the bleed steam pipe 32 and the check valve 33
And a steam system for feeding the low-pressure control valve 34 from the auxiliary steam header 23 to the low-pressure control valve 34 through an auxiliary steam pipe 37 having a control valve 38. A control device 48 for adjusting the pressure or the flow rate of the driving steam is provided.

The control unit 48 inputs the actual pressure signal 50 and the set pressure value 51 from the pressure detector 49 to a deviation calculator 52 to obtain a deviation signal 53. The deviation signal 53 is further transmitted to a control calculator 54. It is configured to input and output a valve opening command value 55 for the control valve 38.

During normal operation, the bleed air of the intermediate pressure turbine 9 is guided to the low pressure control valve 34 via the bleed steam pipe 20, the bleed steam pipe 32, and the check valve 33, and flows into the drive turbine 31 for the boiler feed pump. Drive this.

When the turbine bleed air is lost, such as when the load is cut off or in the station alone, the auxiliary steam from the auxiliary header 23 passes through the auxiliary steam pipe 37 and the control valve 38 and the low pressure control valve 34
And flows into the boiler feed pump drive turbine 31 to drive it.

Also in this embodiment, by driving the boiler feed pump drive turbine 31 using the auxiliary steam during load shedding or in-house operation alone, the turbine exhaust temperature can be kept below a predetermined temperature. In the present embodiment, the auxiliary steam can be adjusted to a predetermined pressure or flow rate and supplied as drive steam for the drive turbine 31 for the boiler feed pump.

Further, since a high-pressure steam system (system comprising a steam pipe 35 and a high-pressure control valve 36) for supplying main steam to the drive turbine 31 for the boiler feed pump is not used, expensive high-temperature and high-pressure piping and valves are used. This is unnecessary, and the material cost can be reduced accordingly.

(Seventh Embodiment) FIG. 8 shows a seventh embodiment of the present invention. In addition to the above-described sixth embodiment, a steam stop valve is provided at the outlet side of the control valve 38. A control device 71 for controlling the control valve 38 and the steam stop valve 70 is provided.

The control device 71 employs the same control logic as the control device shown in FIG. 3 described above, so that only the concept is described, and the detailed configuration and operation are omitted. The control device 71 outputs a valve opening command value 72 of “fully closed” to the steam stop valve 70 during normal operation of the drive turbine 31 for the boiler feed pump, and outputs a “predetermined value” to the control valve 38. A valve opening command value 73 to be held in the "opening" command 82 is output.

During the operation in which turbine bleed air is lost due to load shedding or single-site operation, the steam stop valve 7 is used.
The control valve 38 outputs a valve opening command value 72 for opening 0, and further, when the driving steam pressure falls below a predetermined pressure, the control valve 38
, A valve opening command value 73 for adjusting the driving steam pressure to a predetermined pressure is output.

In the present embodiment, similarly to the third embodiment, during operation in which turbine bleed air is lost due to load shedding or in-station independent operation, the control valve 38 is already opened by a predetermined opening degree, so that steam As soon as the stop valve 70 is opened, the auxiliary steam flows from the auxiliary steam header 23 into the drive turbine 31 for the boiler feed pump and drives it.

Accordingly, the responsiveness of switching of the driving steam is improved, and the boiler feed pump 2 which is likely to occur at the time of switching is changed.
Since a decrease in the discharge flow rate of the boiler 7 can be reduced, loss of water supply and burnout of the boiler 1 can be prevented. In addition, when the driving steam pressure falls below the predetermined pressure, a function of adjusting the pressure to the predetermined pressure is provided, so that the inlet pressure required to drive the boiler feed pump driving turbine 31 can be secured.

[0079]

According to the present invention, when turbine bleed air is lost during a load reduction operation such as a load shedding operation or a stand-alone operation in a station, the driving turbine 31 for the boiler feed pump is used by using low-temperature reheat steam or auxiliary steam. , The turbine exhaust temperature can be reduced to a predetermined temperature or lower, the system configuration and the operation method can be simplified, and the material cost can be reduced. Can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a valve opening according to a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 7 is a configuration diagram showing a sixth embodiment of the present invention.

FIG. 8 is a configuration diagram showing a seventh embodiment of the present invention.

FIG. 9 is a configuration diagram showing a conventional power plant.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Boiler, RH ... Reheater, 2 ... Main steam pipe, 3 ... Main steam pipe, 4 ... Main steam control valve, 5 ... High pressure turbine, 6 ... Low temperature reheat steam pipe, 7 ... High temperature reheat steam pipe, 8 ... Reheat steam valve, 9 ...
Medium-pressure turbine, 10 crossover pipe, 11 low-pressure turbine, 12 generator, 13 condenser, 14 condenser pipe,
15: condensing pump, 16: water supply pipe, 17: low pressure water supply heater, 18: water supply pipe, 19: deaerator, 20: bleed steam pipe,
21: extraction steam pipe, 22: check valve, 23: auxiliary steam header, 24: extraction steam pipe, 25: control valve, 26: water supply pipe,
27: boiler feed pump, 28: feed pipe, 29: high pressure feed heater, 30: feed pipe, 31: feed pump drive turbine, 32: extraction steam pipe, 33: check valve, 34: low pressure control valve, 35 ... Steam pipe, 36 high-pressure control valve, 37 auxiliary steam pipe, 38 control valve, 39 control valve oil cylinder, 40 high-pressure bypass valve, 41 low-pressure bypass valve, 42 high-pressure bypass steam pipe, 43 low-pressure bypass Steam pipe, 44 ... Spray water pipe, 45 ... Control valve, 46 ... Steam pipe, 48, 48A ... Control device, 49 ... Pressure detector or flow rate detector, 50 ... Real pressure signal or real flow signal, 51 ... Set value, 52: deviation calculator, 53: deviation signal, 54: control calculator, 55: valve opening command value, 61: predetermined opening signal, 62: first switching device, 6
3: On-delay timer, 65: Signal to generate load interruption or in-house independent operation, 67: Second switch, 68: Fully open signal, 70: Steam stop valve, 71: Control device, 72, 73 ...
Valve opening command value, 74: third switching device, 75: fully closed signal, 7
6 ... Fully open signal, 77 ... Set value, 78 ... Deviation calculator, 80
... Control arithmetic unit, 82 ... Predetermined opening signal, 83 ... Fourth switch, 84 ... AND circuit, 90 ... Control device, 91 ... Set value, 92 ... Deviation arithmetic unit, 94 ... Control arithmetic unit, 96 ... No. 1
Function generator, 97: second function generator.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01D 17/20 F01D 17/20 EBK JA 17/24 17/24 BMR N F22B 35/00 F22B 35/00 F (72) Inventor Takao Konishi 1-1-1, Shibaura, Minato-ku, Tokyo F-term in the head office of Toshiba Corporation (reference) 3G071 AA06 AA07 AB06 BA07 BA10 CA00 DA05 FA01 FA03 FA06 HA03 HA05 JA03 3L021 AA05 CA06 DA03 DA04 FA02

Claims (10)

[Claims] 1. The steam generated in a boiler is supplied to a high-pressure steam turbine for expansion work, and the exhaust gas is reheated by a reheater and then supplied to a medium-pressure steam turbine for expansion work.
The exhaust of the medium-pressure steam turbine is supplied to a low-pressure steam turbine to perform expansion work, and then condensed by a condenser.The condensed water is supplied to the boiler by a boiler feed pump driven by the steam turbine. In the boiler feedwater pump driving turbine operating method, the steam extracted from the steam turbine is supplied as drive steam to the boiler feedwater pump drive turbine during normal operation, and the steam supplied to the reheater during the rapid load reduction operation. A method for operating a drive turbine for a boiler feedwater pump, wherein a part of the turbine exhaust is diverted and supplied as drive steam to the drive turbine for the boiler feedwater pump. 2. The steam generated by the boiler is supplied to a high-pressure steam turbine for expansion work, and the exhaust gas is reheated by a reheater and then supplied to a medium-pressure steam turbine for expansion work.
The exhaust of the medium-pressure steam turbine is supplied to a low-pressure steam turbine to perform expansion work, and then condensed by a condenser.The condensed water is supplied to the boiler by a steam turbine-driven boiler feed pump. A boiler feed pump drive turbine operating device, wherein during normal operation, a turbine bleed system that supplies bleed air of the steam turbine to the boiler feed pump drive turbine as drive steam, and supplies the reheater during a rapid load reduction operation. And a low-temperature reheat steam system for diverting a part of the steam turbine exhaust to be supplied to the boiler feed pump drive turbine as drive steam. 3. A control valve is provided in the low-temperature reheat steam system, and a detector for detecting a steam pressure or a steam flow rate is provided, and a set value is obtained by comparing a set value and a detected value of the detector during a rapid load reduction operation. The drive turbine operating device for a boiler feed pump according to claim 2, further comprising a control device that outputs the valve opening command value. 4. A valve opening command value that is kept in a fully closed state during normal operation, a valve opening command value having a predetermined opening during a period from the start of a sudden load reduction operation to a scheduled time, and a valve opening command value after a lapse of the scheduled time. 4. The drive turbine for a boiler feed pump according to claim 3, further comprising a control device that outputs a valve opening command value of the opening obtained from the set value and the detection value to the control valve. Driving device. 5. A low-pressure reheating steam system, wherein a steam stop valve is provided between the control valve and the low-pressure control valve, and a valve opening command value for closing the steam stop valve is output during a normal operation, and a load sudden reduction operation is performed. 4. The drive turbine operating device for a boiler feed pump according to claim 3, further comprising a control device for outputting a valve opening command value for opening the steam stop valve at a time. 6. The steam generated in the boiler is supplied to a high-pressure steam turbine for expansion work, and the exhaust gas is heated by a reheater and then supplied to a medium-pressure steam turbine for expansion work. A drive turbine operation for a boiler feed pump, in which exhaust gas is supplied to a low-pressure steam turbine to perform expansion work, and then condensed by a condenser, and the condensate is supplied to the boiler using a turbine-driven boiler feed pump. A method for providing a low-temperature reheat steam system for diverting a part of the exhaust gas of the high-pressure steam turbine and supplying it as drive steam to a drive turbine for a boiler feed pump, wherein auxiliary steam of an auxiliary steam header is used for the drive turbine for the boiler feed pump. Auxiliary steam system for supplying drive steam is provided for both low temperature reheat steam system and auxiliary steam system during normal operation and sudden load reduction operation. A method for operating a drive turbine for a boiler feed pump, wherein drive steam is supplied from one of the two. 7. The steam generated in the boiler is supplied to a high-pressure steam turbine for expansion work, and the exhaust gas is heated by a reheater and then supplied to a medium-pressure steam turbine for expansion work. A drive turbine operating device for a boiler feed pump that supplies exhaust gas to a low-pressure steam turbine, performs expansion work, condenses the water in a condenser, feeds the condensed water to the boiler with a turbine-driven boiler feed pump, and feeds the boiler. In the above, a low-temperature reheat steam system for diverting a part of the exhaust of the high-pressure steam turbine and supplying it as drive steam to the drive turbine for the boiler feed pump is provided, and the auxiliary steam of the auxiliary steam header is supplied to the drive turbine for the boiler feed pump. An auxiliary steam system for supplying as driving steam is provided.A control valve is provided for each of the low-temperature reheat steam system and the auxiliary steam system, and a set value and the A boiler provided with a control device for outputting to the control valves two types of valve opening command values obtained by comparing a detected value of the driving steam with a characteristic of the opening degree in a predetermined relationship. Drive turbine operating device for feedwater pump. 8. The steam generated in the boiler is supplied to a high-pressure steam turbine for expansion work, and the exhaust gas is reheated by a reheater and then supplied to a medium-pressure steam turbine for expansion work.
Boiler feed water in which the exhaust of the medium-pressure steam turbine is supplied to a low-pressure steam turbine to perform expansion work, and then condensed by a condenser, and the condensed water is supplied to the boiler by a turbine-driven boiler feed pump. In the driving turbine operating method for a pump, a turbine bleeding system that supplies bleed air of the intermediate-pressure steam turbine to the boiler feed pump driving turbine as driving steam is provided, and a part of exhaust of the high-pressure steam turbine is diverted to supply boiler water. A low-temperature reheat steam system for supplying drive steam to the pump drive turbine; and an auxiliary steam system for supplying steam for the auxiliary header to the drive turbine for the boiler feed pump. Supply steam,
A driving turbine operation method for a boiler feedwater pump, wherein driving steam is supplied from at least one of the low-temperature reheating steam system and the auxiliary steam system during a rapid load reduction operation. 9. The steam generated in the boiler is supplied to a high-pressure steam turbine for expansion work, and the exhaust gas is heated by a reheater, and then supplied to a medium-pressure steam turbine for expansion work. Boiler feed pump drive turbine, which supplies the exhaust gas to a low-pressure steam turbine to perform expansion work, condenses water in a condenser, and uses the condensed water as water supply to the boiler with a turbine-driven boiler water supply pump. In the operating device, during normal operation, a turbine bleed system for supplying bleed air of the steam turbine as drive steam to the drive turbine for the boiler feed pump is provided, and during a rapid load reduction operation, auxiliary steam from the auxiliary steam header is supplied to the boiler feed water. An auxiliary steam system for supplying drive steam to the pump drive turbine is provided, and a control valve provided for the auxiliary steam system is provided. Out detection value and set value comparison boiler feed water pump drive turbine operation apparatus characterized in that a control device for outputting a valve opening degree instruction obtained in said control valve by the. 10. A steam stop valve is provided at an outlet side of a control valve of the auxiliary steam system. During normal operation, the steam stop valve is fully closed and the control valve is held at a predetermined opening. When the steam stop valve is opened and the driving steam pressure falls below a predetermined pressure, the valve opening command value obtained by comparing the set value with the detected value is output. 10. The drive turbine operating device for a boiler feed pump according to claim 9, further comprising a control device for outputting.