JPH01187612A - Vane opening control device for circulating water pump for steam turbine exhaust cooling - Google Patents

Abstract

PURPOSE:To realize the efficient operation of a movable vane type circulating water pump by performing prescribed turbine load running by keeping an outlet/ inlet temperature difference within a limited value even in such a case that circulating water temperature rises. CONSTITUTION:In a case that the outlet/inlet temperature difference is within the limited value like the case that the circulating water temperature is below a definite value, etc., ordinary running is performed according to a pump vane opening instruction signal 105 outputted from a first relational operating means 20, i.e., the pump vane opening instruction signal 105 corresponding to steam turbine load. On the contrary, in the case that the degree of vacuum of a condenser falls and the outlet/inlet temperature difference exceeds the limited value like the case that the circulating water temperature rises like in a summer or condenser cleanness deteriorates, the opening instruction signal to which pump vane opening is added is outputted by a pump vane opening set switching means 22, and circulating water flow rate is increased. Thus, the circulating water pump comes to be operated efficiently.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a thermal power generation plant or a nuclear power generation plan 1-
The present invention relates to a circulating water pump opening degree control device for steam turbine exhaust cooling, etc., which is applied to steam turbine exhaust cooling.

(Prior art) In thermal power plants or nuclear power plants, a circulating water system using natural water such as seawater, river water, or lake water is used as a means to cool the turbine exhaust gas flowing from the steam turbine to the condenser. It is well known that it is adopted.

Conventionally, fixed W-type circulating water pumps with a fixed blade opening were used in such circulating water systems, but in recent years, from the perspective of energy conservation, pumps have been developed that can supply circulating water in an amount commensurate with the steam turbine load (output). A movable 'tA type circulating water pump has come into use. This movable vane type circulating water pump has a structure in which the opening of the pump blades is variable.The amount of circulating water corresponding to the steam turbine load is determined in advance by calculation, and during operation, the pump corresponds to the actual steam turbine load detected. The blade opening is controlled to be the same.

(Problems to be Solved by the Invention) However, the conventional flash opening control simply proportionally increases or decreases the amount of circulating water, that is, the pump blade opening, in accordance with the turbine load, which causes the following problems. be.

The temperature of natural water such as seawater, river water, lake water, etc. fluctuates depending on the season, for example! When the water temperature rises as in a field, the cooling capacity decreases, and the degree of vacuum in the condenser decreases accordingly. Note that the degree of vacuum in the condenser also decreases in the same manner as described above when dirt adheres to the inside of the condenser tube and the cleanliness of the condenser decreases.

If the condenser is operated with a reduced vacuum level, the turbine load will also drop accordingly, so if it is necessary to maintain the steam turbine load at a constant value, increase the amount of steam supplied to the steam turbine. There must be. However, when the amount of steam supplied to the steam turbine increases, the amount of heat exchange in the condenser increases, and the circulating water temperature (outlet temperature) at the condenser outlet may exceed the 11 limit value (for example, 7°C). There is a possibility that it will be driven beyond the limit.

The present invention has been made in view of these circumstances, and even when the circulating water temperature rises, it is possible to reduce the temperature difference between the inlet and outlet.
It is an object of the present invention to provide a circulating water pump blade opening control device for steam turbine exhaust cooling, which is capable of operating a predetermined turbine load while maintaining the load within limit 1a, and which can effectively operate a movable vane type circulating water pump.

[Structure of the invention]

(Means for Solving the Problems) The present invention controls the spacing of a circulating water pump used in a circulating water system for a steam turbine exhaust cold section in power generation plans 1 to 1. By inputting the detection signals of both detectors, such as a pressure sensor and a pump pressure sensor that detects the circulating water pump blade opening degree, the pump blade setting distance and pump blade value are determined based on the turbine load detection signal. a first comparison calculation means that calculates a necessary pump blade opening by comparing the actual pump i interval based on the opening detection signal and outputs a pump blade opening command signal based on the calculated value; An inlet temperature detector detects the circulating water system inlet temperature, an outlet temperature detector detects the circulating water system outlet temperature, and temperature detection signals from both temperature detectors are input to detect the temperature difference between the circulating water inlet and outlet. a second comparison calculation means for calculating the temperature difference and outputting an opening increase command signal for increasing the pump blade opening when the temperature difference exceeds a certain limit value; and the first and second comparison calculation means. Input the command signal from the means,
If the temperature difference between the inlet and outlet of the circulating water is less than the limit value, a pump blade opening command signal based on the first comparison calculation means is output, and if the temperature difference between the inlet and outlet of the circulating water exceeds the limit value, the first comparison is performed. a pump blade opening degree setting switching means that outputs a signal by switching to an additive pump blade opening command signal obtained by adding the pump blade opening degree based on the pump blade opening degree command signal outputted from the calculation means at a predetermined ratio; The present invention is characterized by comprising a φ pump blade opening adjustment device that receives a pump blade opening command signal output from the setting switching means and adjusts the blade opening of the circulating water pump.

(Function) When the temperature difference between the inlet and outlet is within the limit value, such as when the circulating water temperature is below a certain level, the pump blade opening command signal output from the first comparison calculation means, that is, the pump blade opening command signal corresponding to the steam turbine load. Normal operation is performed based on the pump blade opening command signal.

On the other hand, when the circulating water temperature rises or the condenser cleanliness decreases as in the summer, when the condenser vacuum level decreases and the inlet/outlet temperature difference exceeds the limit value, the pump 17f
An opening command signal to which the pump blade opening is added is output by the m degree setting switching means, thereby increasing the circulating water debt.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a steam turbine steam system and a turbine exhaust cooling u1 system of a thermal power plant.

A steam turbine 4 is connected to a main steam pipe 2 led out from a steam generator 1 such as a boiler via a main steam stop valve/control valve 3, and a generator 5 is connected to the steam turbine 4.

The steam turbine 4 is connected to a condenser 6, and the condenser 6 is provided with a turbine exhaust cooling system 7. The turbine exhaust cooling system 7 uses seawater as circulating water for cooling, and includes a VJ-type circulating water pump 8 for pumping up seawater, and a pump outlet valve 9.
and a circulating water pipe 11 for water supply having a condenser valve 10
It is equipped with

In addition, a circulation water pipe 3 for drainage having a condenser outlet valve 12 is provided.
This circulating water pipe 13 is guided to a water discharge channel 14.

The circulating water pump 8 is provided with a pump opening adjustment device 15 for controlling the blade opening of the pump 8 and a pump opening degree detector 16 for detecting the opening.

The circulating water pipe 11.13 is provided with a condenser inlet seawater temperature detector 17 as an inlet temperature detector and a condenser outlet temperature detector 18 as an outlet temperature detector, and the generator 5 is provided with a load detector. A container 19 is provided.

During operation, steam generated in the steam generator @ 1 is sent to the steam turbine 4 through the main steam pipe 2 through the main steam stop valve and control valve 3, and after being used for work (generator drive), it is sent to the steam turbine 4 for recovery. It is sent to water container 6.

The turbine exhaust gas sent to the condenser 6 exchanges heat with the seawater supplied by the circulating water pump 8 and becomes condensed, and the seawater whose temperature has increased is discharged into the discharge channel 14. This condensate 5
The amount of circulating water supplied to the circulating water pump 6 is determined by controlling the blade of the circulating water pump 8 by the pump m opening adjustment device M15.

FIG. 2 shows the system configuration of the circulating water pump blade opening degree 11611 device that drives the blade spacing adjustment device 15. Input signals include a turbine load detection signal 101 output from a load detector 19 provided in the generator 5, and a circulating water pump 8.
The pump blade opening detection signal 102 is output from the pump blade opening degree detector 16 provided at Output inlet seawater temperature detection signal 103
and the outlet seawater temperature detection signal 104 are used.

The turbine load detection signal 101 and the pump frequency detection signal @102 are input to the first comparison calculation means 20. In this first comparison calculation means 20, the turbine load detection signal 1
The pump blade opening set in advance according to 01 is compared with the actual pump blade opening based on the pump blade opening detection signal 102, and the currently required pump force is calculated. Pump vane II based on the value;! Degree Directive Shingetsu 105
is output.

Here, the pump product setting interval will be explained with reference to FIGS. 3 to 5. Figure 3 shows the pump characteristics for each degree of opening of the circulating water pump. Loads A, B, C, of steam turbine 4,
D The blade opening corresponding to (A<B<C<D) is a, b, c,
d, the circulation pump opening degree for each opening degree is represented by the characteristic curve shown in FIG. The degree of vacuum of each blade is the degree of vacuum of the condenser 6, which is the rated degree of vacuum (usually 722 s + 1I (IVAc
) Assuming that the temperature difference between the inlet and the outlet of the condenser is, for example, 6.8°C (the limit 1f37°C with a margin of 0°2°C), calculate the required amount of circulating water, and find it from the intersection with the system head curve mH of the circulating water system. It will be done.

FIG. 4 shows the opening degree a of the circulating water pump 8 shown in FIG.
, b, c, d, and turbine loads A, B.

It shows the relationship with C and D. The blade opening increases in stages in response to the turbine load. The correspondence relationship shown in FIG. 4 is programmed into the first comparison calculation means 20, and when the turbine load detection signal 101 is input, the corresponding pump blade opening setting is determined.

FIG. 5 shows an example of east opening setting. That is, when the turbine load is less than A (LEA), the abnormality level is a%,
b% when A or more and less than B (A≦L<8), 0% when B or more and C less than 8M (B≦L<C), and less than C or more (C≦L
<D), it becomes d%.

The first comparison calculation means 20 described above compares these threshold opening values with the actual pump blade opening based on the pump flash opening detection signal 102, and determines the required pump q opening command signal. 105 is output to the pump blade opening adjustment device 21.

In addition, the pump! [The degree command signal 105 passes through the pump blade opening degree setting switching means 22. This pump blade opening setting switching means 22 has an adding means 23 and a circuit changeover switch 24, and the circuit changeover switch 24 is connected to the second comparison calculation means 25.
controlled by

The above-mentioned inlet seawater temperature detection signal 103 and outlet seawater temperature detection signal 104 are input to the second comparison calculation means 25 . Then, the second comparison calculation means 25 calculates the temperature difference between the entrance and exit (Δt), and when the temperature difference (Δt) exceeds a certain limit value, the degree of opening of the pump blade is increased. An increase command signal 106 is output to the circuit changeover switch 24.

The circuit changeover switch 24 is a circuit that directly sends the pump blade opening command signal 105 output from the first comparison calculation means 20 to the pump blade opening adjustment device 21 when the opening increase command signal 106 is not input. composition. Further, when the opening increase command signal @106 from the second comparison calculation means 25 is input, the pump blade opening command signal 105 from the first comparison calculation means 20 is once input to the addition means 23. The added pump blade opening command signal 107 is sent to the pump blade opening adjustment device 21.
Switch the circuit to send to.

FIG. 6 shows an addition program incorporated into the addition means 23. In other words, the increase in circulation pump blade opening (%) is shown on the vertical axis.
), and the horizontal axis shows the turbine load (%).

As shown in FIG. 6, each turbine load A, B, C,
A program is provided in which the pump blade opening degree is increased by a certain percentage (X%) with respect to D, and the adding means 23
The addition pump blade opening command signal 107 is output from the pump W On
It is output to the degree adjustment device 21.

During operation, the first comparison calculation means 20 compares the turbine load detection signal 101 detected by the turbine load detector 19 and the pump noise level signal 102 detected by the pump open position detector 16. Calculation is performed to calculate the opening degree of the ring water pump that is appropriate for the steam turbine load (output). Then, the pump blade opening command signal 105 is sent to the pump blade opening adjustment device 15 via the pump blade opening V'J converter 22, and the pump blade opening is set.

In addition, the degree of vacuum in the condenser decreases, the amount of steam supplied to the steam turbine 4 increases, and the temperature difference (Δ
t) exceeds the 1lIll limit, a temperature detection signal 103 is sent to the inlet seawater detected by the condenser outlet seawater temperature detector 17, and a temperature detection signal 103 is sent to the inlet seawater detected by the condenser outlet seawater temperature detector 18.
A comparison calculation is performed by the second comparison calculation means 25 using the output seawater temperature detection signal 104, and the value of the temperature difference (Δt) between the entrance and exit of the seawater to the condenser is calculated. If Δt is greater than the limit value, the pump blade opening degree increase command value signal 106 from the second comparison calculation means 25 is used in the pump blade opening setting switching means 22 to send the addition pump via the addition means 23. The blade opening command signal 107 is sent to the pump blade opening adjustment device 21 to set the blade opening. Note that when the condenser seawater inlet/outlet temperature difference (Δt) decreases to a certain value or less than the II limit value, the signal from the second comparison calculation means 25 is no longer output, and the pump blade opening setting switching means 22 receives only the signal 105 from the first comparison calculation means 20 and does not go through the second adder, so the circulating water pump blade opening is operated at the W opening of the normal pattern. . Therefore, according to the above embodiment, even if the temperature t of the condenser seawater inlet and outlet exceeds the limit value, the circulating water pump blade opening degree increases, and the temperature difference of the circulating water below the limit value increases. be driven.

〔Effect of the invention〕

As described above, according to the present invention, during normal operation, the opening degree of the circulating water pump is set to match the steam turbine load (output), and on the other hand, when the temperature difference between the circulating water inlet and outlet of the condenser exceeds the υj limit, In this case, the opening degree of the circulating water pump is automatically increased to maintain the temperature difference below the limit 11f,i. In addition, when the vacuum space of the condenser is restored, the circulating water pump blade opening is maintained at the normal operating pattern, so that the temperature difference between the condenser seawater inlet and outlet changes due to changes in the vacuum of the condenser. Even if exceeds the limit value, a command to increase the opening of the circulating water pump blades is immediately issued, and the circulating water pump can be operated within the above limit value.

[Brief explanation of the drawing]

Fig. 1 is a schematic system diagram showing an embodiment of the present invention, Fig. 2 is a system configuration diagram of the υItll device that controls the system shown in Fig. 1, Fig. 3 is a diagram showing pump characteristics, and Fig. 4 is a diagram showing the pump characteristics. FIG. 5 is a diagram showing the relationship between the turbine load and the pump blade opening, FIG. 5 is a diagram showing an example of setting the pump flash opening, and FIG. 6 is a diagram showing an increasing state of the pump opening. 4...Steam turbine. 5... Generator, 8... Circulating water pump, 11.13... Circulating water pipe, 16... Pump blade opening detection device, 17... Inlet temperature detection device, 18
... Outlet temperature detection device, 19... Turbine load detector, 20... First comparison calculation means, 21... Pump blade opening adjustment device, 22... ■Opening setting switching device, 23
...Adder, 25...Second comparison operation means. Applicant's agent Hisashi Hatano Figure 1 Figure 2 Image 1 (m x 1 l) - Turbine load (/,) - m - Figure 4

Claims (1)

[Claims] A turbine load detector that detects the steam turbine load and a pump blade opening that detects the circulating water pump blade opening are used to control the blade opening of the circulating water pump used in the circulating water system for cooling the steam turbine exhaust of a power generation plant. By inputting the detection signals of both these detectors and comparing the set pump blade opening determined based on the turbine load detection signal with the actual pump blade opening determined based on the pump blade opening detection signal. a first comparison calculation means that calculates the required pump blade opening and outputs a pump blade opening command signal based on the calculated value; an inlet temperature detector that detects the system inlet temperature of the circulating water; An outlet temperature detector detects the temperature at the outlet of the system, and temperature detection signals from both temperature detectors are input to determine the temperature difference between the inlet and outlet of the circulating water, and when the temperature difference exceeds a certain limit value, the pump a second comparison calculation means for outputting an opening increase command signal for increasing the blade opening; and the first and second
When the temperature difference between the inlet and outlet of the circulating water is less than the limit value, the command signal from the first comparison and calculation means is output, and the difference in temperature between the inlet and the outlet of the circulating water is inputted. exceeds the limit value, the pump switches to an added pump blade opening command signal obtained by adding the pump blade opening command signal based on the pump blade opening command signal outputted from the first comparison calculation means at a predetermined ratio, and outputs the signal. A pump blade opening adjustment device that inputs a pump blade opening command signal output from the pump blade opening setting switching means and adjusts the blade opening of the circulating water pump. A circulating water pump blade opening control device for steam turbine exhaust cooling, characterized in that: