JPS6050494A - Controller for temperature of feedwater of nuclear power plant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a feed water temperature control device for a nuclear power plant that suitably adjusts the temperature of feed water supplied to a nuclear reactor.

[Technical background of the invention and its problems]

FIG. 1 is a system diagram showing the water supply and steam systems of a conventional nuclear power plant. - Main steam from the reactor 1 is led to the steam turbine 5 via the main steam control valve 3, where it performs work and is sent to the condenser 7 where it is condensed. Condensate (feed water) condensed in the condenser 7 is led to the reactor 1 via low-pressure and high-pressure feed water heaters 9 and 11. The low-pressure feedwater heater 9 is supplied with low-pressure bleed air from the low-pressure steam turbine via the check valve 13, and the high-pressure feedwater heater 11 is supplied with medium-pressure bleed air from the intermediate-pressure steam turbine via the check valve 14. is supplied. Therefore, the feed water heater 9,
11, heat exchange is performed between the feed water supplied to the reactor 1 and the bleed air, and the temperature of the feed water increases. This increase in feed water temperature can improve plant thermal efficiency in the nuclear power plant and stabilize steam generation in the reactor 1.

By the way, in order to stably generate steam within the nuclear reactor 1, it is necessary to set the feed water temperature at the inlet of the nuclear reactor 1 within the shaded area shown in FIG. In FIG. 2, the horizontal axis shows the steam generation amount (output of the steam turbine), and the vertical axis shows the feed water temperature at the outlet of the feed water heater 11. The feed water temperature on the vertical axis is expressed as a percentage based on the rated temperature of 215C when the steam generation amount is 100 cm. However, the main steam sent to the steam turbine 5 is
Additionally, since the thermal efficiency of the power plant is adjusted to be optimal, the pressure of the extracted air led from the steam turbine 5 to the feed water heaters 9 and 11 also depends on the opening degree of the main steam control valve 3. become. Therefore, when the steam turbine is under low load, the extraction pressure is low, the pressure in the feed water heaters 9 and 11 is reduced, and the feed water temperature is outside the shaded area as shown by straight line BC in FIG. There are cases where this happens.

Therefore, a conventional nuclear reactor power plant is provided with a feed water temperature control device, and the feed water temperature is adjusted so that steam generation in the nuclear reactor 1 is performed stably. When the load of the natural air turbine 5 is low, main steam is guided from the main steam pipe to the high-pressure feed water heater 11 via the adjustment valve 15 and the check valve 17, and the feed water is heated. In addition, when the steam turbine 5 is under medium load, the high pressure steam turbine first turns off and the regulating valve 19
High pressure bleed air is introduced to the high pressure feed water heater 11 via the check valve 21 and the feed water is heated. Next, Fi
At the stage when the water temperature is no longer raised sufficiently, main steam is sent to the high-pressure feed water heater 11 via the regulating valve 15.

However, in the above-mentioned feed water temperature control device, an operator of a nuclear power plant monitors the feed water temperature and controls the regulating valves 15 and 1.
9 must be opened and closed manually. Also, le 4
Since the valve regulators 15 and 19 are operated manually, the feed water temperature can be adjusted to 1 liter appropriately in response to fluctuations in plant conditions that change based on fluctuations in the load of the nuclear power plant! It becomes difficult to control.

[Target of origin]

This invention was made in consideration of the above-mentioned facts, and is a method for automatically and safely controlling the feed water temperature of 61.6 degrees from the feed water heater to the Keiko reactor. The purpose is to provide a control device.

[Summary of the invention]

The steam that has done the work is condensed in a condenser, and a feed water heater that heats the condensed felled wood and guides it to the nuclear reactor, and a bleed air pipe line that guides turbine bleed air from the steam turbine to the feed water heater are provided. a pressure switch that detects the pressure of turbine bleed air in the bleed air pipe, and a pressure switch that is installed in a pipe that leads turbine bleed air or main steam to the feedwater heater, which is different from the pressure of the turbine bleed air detected by the pressure switch. and a regulating valve that is connected to the pressure switch and whose opening and closing are controlled by signals from the pressure switch, and a feed water heater that is guided to the feed water heater by the pressure switch and the regulating valve. Steam for heating is selectively switched and supplied.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a system diagram showing the feed water/black system of a nuclear power plant to which the first embodiment of the feed water temperature control device for a nuclear power plant according to the present invention is applied. The steam is guided to the steam pipe 33 and is led to the steam turbine 37 via a main steam control valve provided in the main steam pipe 33. The main steam pumped into the steam turbine 37 drives the steam turbine 37 to perform work, and then is sent to the water collector 39 where it is cooled and condensed.

Further, a water intake device 39 on the upstream side of the main steam control valve 35 in the main steam pipe 33 is communicated with a turbine bypass pipe 41, and a turbine bypass valve 43 is provided in the turbine bypass pipe 41.

In addition, the temporary water (feed water) condensed in the canyon 39 is pressurized by the feed water cylinder 45, heated through the low pressure feed water heater 47 and the high pressure feed water heater 49 in sequence, and then heated to the reactor 31.
guided by. The low pressure feed water heater 47 and the low pressure steam turbine are connected by a low pressure bleed air pipe 51, and this low pressure bleed air IT, 5.
A check valve 53 is disposed at 51 . Therefore, the feed water is heated δ in the low pressure feed water heater 47 by the low pressure turbine bleed air supplied from the low pressure steam turbine. Further, the high pressure feed water heater 49 and the intermediate pressure steam turbine are connected through an intermediate pressure bleed pipe 55, and this intermediate pressure bleed pipe 55 is also provided with a check valve 57. Therefore, the feed water flowing out of the low pressure feed water heater 47 is heated in the high pressure feed water heater 49 by the intermediate pressure turbine bleed air supplied from the intermediate pressure steam turbine.

Here, the pressure of the turbine bleed air supplied to the low-pressure and high-pressure feedwater heaters 47, 49 and these feedwater heaters 47,
The heating side of the feed water heaters 47 and 49 is filled with turbine bleed air as heated steam, and most of the heat exchange with the feed water is through condensation of the turbine bleed air. It is done by heat. Therefore, the feed water temperature at the outlet side of the feed water heaters 47, 49 approximately matches the temperature of the turbine bleed air. Further, since the turbine extracted air is steam that is almost saturated in the feedwater heaters 47 and 49, its temperature is considered to be a function only of the internal pressure of the feedwater heaters 47 and 4.9. From the above, the feed water temperature at the outlet of the feed water heaters 47 1 and 49 is uniquely determined by the internal pressure of each of the feed water heaters 47 1 and 49 . In other words, if the internal pressure is set high, a high temperature can be obtained, and if the internal pressure is set low, a low temperature can be obtained.

Therefore, in the nuclear power plant shown in Figure 3, the feed water temperature is
It is gradually raised by a low-pressure feedwater heater 47 supplied with low-pressure turbine bleed air and a high-pressure feedwater heater 49 supplied with intermediate-pressure turbine bleed air.

Moreover, the turbine bleed air heat-exchanged within the high-pressure feedwater heater 49 is condensed to become condensed water, which is guided to the low-pressure feedwater heater 47 . This condensed water is sent to the condenser 39 together with the condensed water that undergoes heat exchange and condensation in the low-pressure feedwater heater 47 .

On the other hand, the upstream side of the main steam control valve in the main steam pipe 33 and the high-pressure feed water heater 49 are connected by a sub-main steam pipe 59. The regulating valve 61 and the check valve 63 are connected in sequence. The regulating valve 61 communicates or closes the sub-main steam pipe 59 by its opening and closing operations. This aI-! The internal pressure of the high-pressure feedwater heater 49 when the regulating valve 61 is open is expressed by the following formula: 0 (internal pressure) = (main steam pressure) - KX (main steam supplied to the feedwater heater) Quantity) 2 (1) Here, the value of K is the pressure loss coefficient when the regulating valve 61 is open. Even if the amount of main steam supplied to the feed water heater is the same when the regulating valve is opened, the internal pressure immediately after the regulating valve is opened is different due to the difference in the value of K of the disposed regulating valve. Therefore, the value of K is
Select the regulating valve so that the pressure inside the vessel at point 9 is set to the desired value (for example, from point B' in Fig. 4 to point 02, or from point 1 to point G' in Fig. 6). It is determined.

Further, a pressure switch 65 is disposed upstream of the check valve 57 in the medium pressure bleed pipe 55.
is further electrically connected to the regulating valve 61. This pressure switch 65 detects the pressure of turbine bleed air flowing inside the intermediate pressure bleed air pipe 55, and when this bleed air pressure is below the ON set value, it outputs a signal to open the regulating valve 61f.
If the value exceeds the F"F set value, a signal is output to close the regulating valve 61. These ON/Ofi"F set values are set with a certain pressure difference to prevent chattering of the signal. ON/OFF of switch 65
Operation has hysteresis. This allows the regulating valve 61 to be opened and closed without error.

In addition, the above ON/OF'F setting values are for the high pressure water heater 4.
The temperature of the feed water at outlet 9 is set to be the lower limit (points B and E, respectively) of the region (the region indicated by diagonal lines in Figure 4) in which the reactor 31 can stably generate steam.

That is, the ON/OFF setting values of the pressure switch 650 are the pressures in the medium pressure bleed pipe 55 corresponding to the internal pressure points B' and E/of the high pressure feed water heater 49 which determine the above points B and 1, respectively. Note that the feed water temperature on the vertical axis in FIG. 5 is shown in the same manner as in FIG. 2.

Next, the operation will be explained.0 When the load on the steam turbine 37 is high, the intermediate pressure bleed pipe 5
The pressure of the turbine bleed air flowing through the pressure switch 6 is also high.
Since the value is equal to or higher than the ON setting value of No. 5, the regulating valve 61 is closed. Therefore, the feed water in the high pressure feed water heater 49 is heat exchanged by the medium pressure turbine bleed air.

When the load on the steam turbine 37 decreases from this state, the pressure of the intermediate pressure turbine extracted air also decreases, and the internal pressure of the high pressure feed water heater 49 to which this intermediate pressure turbine extracted air is supplied also decreases as shown in FIG. N point E/point.

It gradually decreases to point B'. Therefore, following this decrease in the internal pressure, the temperature of the feed water at the outlet of the high-pressure feed water heater 49 also decreases from point A to point E to point B in the figure. The bleed pressure flowing through the intermediate pressure bleed pipe group is ON corresponding to the vessel internal pressure point B'.
When the set value is reached, the adjustment valve 61 is opened by an ON signal from the pressure switch 65, and main steam is introduced to the high pressure feed water heater 49. As a result, the internal pressure of the high-pressure feed water heater 49 is increased to point 02 in FIG. 4, and correspondingly, the temperature of the feed water at the outlet of the high-pressure feed water heater 49 is also increased to point C in FIG. 4.

When the load on the steam turbine 37 further decreases, the extraction pressure from the low-pressure steam turbine guided to the low-pressure feedwater heater 47 decreases, and the pressure from the low-pressure feedwater heater 47 to the high-pressure feedwater heater 49 decreases.
The temperature of the feed water flowing into the tank decreases.

Therefore, in order to increase the amount of heat exchange within the high-pressure feedwater heater 49, the amount of main steam flowing into the high-pressure feedwater heater 49 increases. With this increase in the amount of main steam flowing in, the internal pressure of the high-pressure feed water heater 49 gradually decreases from point C' in FIG. 4, as is clear from equation (1). In response to this decrease in internal pressure, the temperature of the feed water at the outlet of the high pressure feed water heater 49 also changes as shown in Figure 4C.
It gradually decreases from this point.

Further, when the load on the steam turbine 37 is low, the bleed pressure in the intermediate pressure bleed pipe 55 is lower than the OFF setting value of the pressure switch 65, and therefore the regulating valve 61 is open.
Main steam is supplied to the high pressure feed water heater 49.

When the load on the steam turbine 37 increases from this state, the internal pressure of the high-pressure feedwater heater 49 increases to point 02D/, as shown in FIG.
The temperature of the water supply at the outlet also rises to 6 points and then to point D. When the bleed pressure flowing through the intermediate pressure bleed pipe 55 reaches the OF"F setting value corresponding to the chamber pressure point D', the regulating valve 61 is closed by the OFF signal from the pressure switch 65, and the chamber pressure becomes E. ′
drop to a point. In accordance with this decrease in the internal pressure, the temperature of the feed water at the outlet of the high pressure feed water heater 49 also decreases to point E.

Thereafter, as the load on the steam turbine 37 increases, the internal pressure of the high-pressure feed water heater 49 increases from point E' to point E.
Correspondingly, the temperature of the feed water at the outlet of the high pressure feed water heater 49 is also E.
Rise from point to point A.

According to the embodiment described above, the pressure of the medium-pressure turbine bleed air guided to the feed water heater 49 is detected by the pressure switch 65, and the regulating valve 61 is opened or closed based on this detected value, so that the pressure of the medium-pressure turbine bleed air guided to the feed water heater 49 is Since the inflow of main steam is controlled, reactor 3
The temperature of the water supplied to the nuclear reactor 31 can be automatically and appropriately controlled within a range where steam is stably generated in the nuclear reactor 31.

FIG. 5 is a system diagram showing a second embodiment of the feed water temperature control device for a nuclear power plant according to the present invention. In this figure, the same parts as those in the first embodiment are given the same reference numerals and the explanation thereof will be omitted.

In addition to the sub-main steam pipe 59 as a first pipe line and the intermediate pressure bleed air pipe 55 as a third pipe line, the high pressure feed water heater 49 includes:
A high pressure bleed pipe 71 is provided as a second pipe line connected to the high pressure steam turbine. A pressure switch 73 , a regulating valve 75 , and a check valve 77 are sequentially arranged in this high-pressure bleed pipe 71 toward the high-pressure feed water heater 49 .

The regulating valve 75 is electrically connected to the pressure switch 6, and is opened and closed by the ON-OF'F signal of the pressure switch 65. High pressure feed water heater 49 when regulating valve 75 is open
The internal pressure of is determined by the following formula.

(Internal pressure) = (High pressure bleed pressure) - LX (High pressure bleed air amount flowing into the feed water heater) 2 ...... (2) Here, L is the same as K in equation (1), This is the pressure loss coefficient when the valve is open. Therefore, le! By selecting the regulating valve 75 and setting the value of L appropriately, the internal pressure of the feed water heater 49 when the regulating valve 75 is opened is adjusted to a desired value (for example, at point B' in FIG. 6). to point G').

The pressure switch 73 is electrically connected to the regulating valve 6e, and opens and closes the regulating valve 61 based on ON/OFF signals of the pressure switch 73. The pressure switch 73 detects the bleed pressure in the high pressure bleed pipe 71, and this detected value is
When the N value is below the set value, the regulating valve 61 is opened and turned OFF.
When the value exceeds the set value, the regulating valve 61 is operated to close. This O
The N-OFF setting value is a range (
The lower limit of the shaded area in Figure 6 (point F, respectively)
1 point). :) The ON/OFF setting values of the pressure switch 730 are the internal pressure points of the high-pressure feed water heater 49 that determine the above points F and ■.
This is the pressure within the commercial bleed pipe 71 corresponding to the point. This ON
- The 0 yen setting value is also set with a slight difference in pressure to prevent chattering of the signal from the pressure switch 73.

Next, the effect will be explained.

When the load on the steam turbine 37 is high, the OFF signals from the pressure switches 65 and 73 turn off the regulating valve 61°7.
5 is closed, and a medium pressure bleed pipe 55 is connected to the high pressure feed water heater 49.
Turbine bleed air can be supplied completely. At this time, the internal pressure of the high-pressure feed water heater 49 is shown at point A' in FIG. 6, and the feed water temperature at the outlet of the high-pressure feed water heater 49 is shown at point A in the figure.

As the load on the steam turbine 37 decreases, the intermediate pressure bleed pipe 5
The bleed pressure in the high-pressure feed water heater 49 decreases, and the internal pressure of the high-pressure feed water heater 49 also changes from point E to point E' to point B' in FIG. Along with this, the temperature of the feed water at the outlet of the high-pressure feed water heater 49 also decreases from point A to point E to point B in the figure. When the bleed pressure of the intermediate pressure bleed pipe 55 decreases to a pressure corresponding to point B' of the internal pressure, the pressure switch 65 detects this and the regulating valve 75 is opened. As a result, high-pressure extraction air is supplied from the high-pressure steam turbine to the high-pressure feed water heater 49,
The internal pressure rises to point G' in FIG. Therefore, the temperature of the feed water at the outlet of the high-pressure feed water heater 49 rises to six points.

After this, when the load on the steam turbine 37 further decreases,
The bleed pressure of the high pressure bleed pipe 71 also decreases, and along with this,
The internal pressure of the high-pressure feed water heater 49 is 1gG′ in the diagram
Due to this decrease in the internal pressure, the temperature of the feed water at the outlet of the high-pressure feed water heater 49 also decreases from point 6 to point FJ in the figure. High pressure bleed pipe 7
When the bleed pressure of No. 1 reaches a pressure corresponding to point F' of the internal pressure, the pressure switch 73 detects this and the regulating valve 61 is opened. - This leads the main steam to the high-pressure feed water heater 49, and the internal pressure rises to point G' in FIG. Therefore, the temperature of the feed water at the outlet of the feed water heater 49 is raised to point G.

In addition, the load on the steam turbine 37 is low, and the intermediate pressure bleed pipe 55
, when the bleed pressure of each of the high-pressure bleed air #71 is lower than the ON set value of each of the pressure switches 65 and 73, the regulating valves 61 and 75 are both opened, and the high-pressure feed water heater 49 receives main steam. Supplied. Thereafter, when the load on the steam turbine increases and the bleed pressure in the high-pressure bleed air pipe 71 reaches a pressure corresponding to the internal pressure point E' of the high-pressure feed water heater 49, an OFF signal from the pressure switch 73 is activated. Adjustment valve 6
1 is closed. 0 By this closing operation of the regulating valve 61, the internal pressure drops to 12 points, and the feed water temperature at the outlet of the high pressure feed water heater 49 also drops to 1 point.

After that, when the load on the steam turbine 37 further increases, the high pressure turbine bleed air from the high pressure bleed pipe 71
The internal pressure of the high-pressure feed water heater 49 ranges from 11 points to 07 points.

The temperature rises to point D', and along with this, the feed water temperature also rises from point 1 to point 0 to point D. When the bleed pressure in the medium pressure bleed pipe 55 reaches a pressure corresponding to the internal pressure of the high pressure feed water heater 49 at point D', the regulating valve 75 is closed by the OFF signal from the pressure switch 65, and the internal pressure reaches point E'. decreases to Due to this decrease in the internal pressure, the temperature of the feed water at the outlet of the high-pressure feed water heater 49 also drops to 8 points, and after that, only the bleed air from the medium pressure bleed air pipe 55 is supplied to the high-pressure feed water heater 49.

According to this embodiment, the bleed air pressure guided to the high pressure feed water heater 49 is detected by the full pressure switches 65 and 73,
By opening and closing the control valves 61 and 75 to selectively and automatically supply main steam or high-pressure extraction air, the temperature of the feed water can be automatically adjusted to a range where natural gas is stably generated in the reactor 31. A71J can be controlled.

Furthermore, in the case of this embodiment, when the steam turbine 37 is under medium load, the high pressure turbine bleed air is guided to the high pressure feed water heater 49 via the high pressure bleed air pipe 71.
It is possible to prevent a decrease in plant efficiency during medium load.

In the second embodiment, the pressure switch 73 is provided upstream of the regulating valve 75 in the high pressure bleed pipe 71. It may be provided on the upstream side of the valve 77 (
Third Example). In this case, the pressure switch 73 cannot detect the pressure of the high pressure bleed air until the regulating valve 75 is opened.
It is necessary for the pressure switch 73 to be opened and for the ON/OFF signal to be output from the pressure switch 73. In this embodiment as well, the same effects as in the second embodiment can be obtained.

Further, in the case of the third embodiment, the regulating valve 61. ．． 75
An AND circuit may be incorporated into the control system between the pressure switch 73 and the pressure switch 73, and an interlock circuit may be formed by this AND circuit. This fourth embodiment is shown in FIG.

Signals are input from the pressure switch 73 and the 'rA regulating valve 75 to the AND circuit 79, and in response to this input signal, the AND circuit 79 outputs a signal to the regulating valve 61. That is,
As shown in FIG. 8, the signal indicating that the regulating valve 75 is open and the ON signal from the pressure switch 73 are A N
When input to D 1fljj-path 79, this AND
A signal for opening the regulating valve 61 is output from the circuit 79. Furthermore, among the above input signals, if the signal from the pressure switch 73 is the 01i'F code, the AND circuit 7
A signal for closing the regulating valve 61 is output from 9. This embodiment also provides the same effects as the second embodiment.

〔Effect of the invention〕

As mentioned above, 5. According to the feed water temperature control device for a nuclear power plant according to the present invention, the pressure of turbine bleed air guided from the steam turbine to the feed water heater is detected by a pressure switch, and the 14 regulating valve is operated based on this detected value, Since main steam is supplied to the feed water heater at a pressure different from the pressure of the heating steam, the feed water is increased to nA.
This has the effect that the temperature of the water supplied from the reactor to the reactor can be automatically controlled to an optimum range where the reactor can stably generate air.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing the feed water and steam system of a conventional nuclear power plant, Figure 2 is a diagram showing the relationship between the output of the steam turbine and the feed water temperature at the outlet of the feed water heater, and Figure 3 is a diagram showing the present invention. Fig. 4 is a system diagram showing the feed water and steam system of a nuclear power plant to which the first embodiment of the feed water temperature control device for a nuclear power plant is applied. Diagram showing the feed water temperature at the outlet of the heater individually according to the fluctuations of the steam turbine, ``5th
The figure is a system diagram showing a second embodiment of the feed water temperature control device for a nuclear power plant according to the present invention, and Figure 6 shows the internal pressure of the feed water heater and the feed water temperature at the outlet of the feed water heater in the second embodiment. FIG. 7 is a system diagram showing the fourth embodiment of the feed water temperature control device for a nuclear power plant according to the present invention, and FIG. It is a block diagram showing an interlock circuit in an example. 31...Nuclear reactor, 37...Steam turbine, 39...
・Condenser, 49... High pressure feed water heater, 51... Low pressure bleed pipe, 5... Medium pressure bleed pipe, 59... Sub main steam pipe, 61... Regulating valve, 65...・Pressure switch, 71・
...High pressure bleed pipe, 75...Adjustment valve.゛Applicant's agent
Shida Hatano Figure 1 Figure 2 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. Steam that has done work in the steam turbine is condensed in a condenser, and a feed water heater that heats the condensed water and guides it to the nuclear reactor, and a turbine extraction air from the steam turbine. A pressure switch is provided in the bleed air pipe leading to the feed water heater and detects the pressure of the turbine bleed air in the bleed air pipe, and a pressure switch is provided that detects the pressure of the turbine bleed air in the bleed air pipe, and the pressure switch detects the pressure of the turbine bleed air or main steam that is different from the pressure of the turbine bleed air detected by the pressure switch. 61, which is provided in a conduit leading to the feed water heater, is connected to the pressure switch, and is opened/closed by a signal from the pressure switch;
A water supply temperature control device for a nuclear power plant having four regulating valves. 2. The feed water temperature control device for a nuclear power plant according to claim 1, wherein the regulating valve is provided in a pipe connecting the main steam pipe that guides main steam from the nuclear reactor to the steam turbine and the feed water heater. . 3. The regulating valve is the first valve that connects the main steam pipe and the feed water heater.
A pressure switch is provided in each of the second pipe line and the second pipe line connecting the high-pressure steam turbine and the feedwater heater, and the pressure switch is provided in the second pipe line and the second pipe line connecting the intermediate-pressure steam turbine and the feedwater heater. Claim 1, wherein each of the three pipelines is provided with a regulating valve in the first pipeline being connected to a pressure switch in the second pipeline, and a regulating valve in the second pipeline being connected to a pressure switch in the third pipeline. The feed water temperature control device for a nuclear power plant according to item 1.