JPS61143607A - Controller for reheater of nuclear power turbine 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 reheater control Vt arrangement for a nuclear turbine plant, particularly for use in a boiling water or pressurized water type atomic coupler.

[Technical background of the invention and its problems]

In a steam turbine, steam (cycle steam) that has passed through a high-pressure turbine and has increased in humidity during expansion (cycle steam) is reheated and supplied to a low-pressure turbine. For this reason, a reheater for reheating is used.

In boiling water type or pressurized wood type nuclear turbine plants, the steam supplied to the steam turbine is in a saturated state, and the steam temperature and pressure at the turbine inlet are both lower than in thermal turbines. A moisture separator 3 and a reheater are used to actively separate and remove moisture from cycle steam and reheat between the high-pressure turbine section and the low-pressure turbine section. This reheater is a large heat exchanger that uses supply steam branched from the reactor side beyond the main stop valve of the steam turbine or turbine oil steam, which is at a higher temperature and pressure than the cycle steam, as the heating steam that is the reheat source. There are multiple stages depending on the heating steam source.

The highest temperature reheat stage generally uses steam turbine inlet steam. The steam temperature at the steam turbine inlet is approximately equal to the saturation temperature of the steam pressure, and since the steam pressure there is controlled to be constant, the steam temperature is also approximately constant. On the other hand, the temperature and flow rate of cycle steam at the high pressure turbine outlet vary widely depending on the load. For example, during partial load, the temperature difference between heating steam and cycle steam becomes large, and the flow rate of cycle steam is small, so the temperature rise due to heating steam becomes large.
The amount of heat exchanged in the reheater increases and the temperature difference of the cycle steam between the inlet and outlet of the reheater increases. Therefore, the heating gradient between the inlet and the outlet of the reheater increases, and the thermal stress in the reheater increases accordingly. Furthermore, on the low-pressure turbine side, the temperature of the steam supplied from the reheater to the low-pressure turbine is high, and the rate of temperature rise in the turbine body becomes large, especially when starting up the plant, resulting in large thermal stress.

For this reason, in conventional reheater control devices, a control valve is installed on the piping that supplies heating steam to the reheater to adjust the supply amount of heating steam, and the control valve is opened at a certain rate of change. By gradually increasing the temperature of the heating steam, thermal stress caused by large temperature differences or rapid temperature changes is reduced. That is, the amount of heating steam is increased by gradually opening the control valve in accordance with the increase in trapped cycle steam,
Reducing the temperature difference between cycle steam and heating steam to keep the temperature difference of cycle steam at the inlet and outlet of the reheater at a suitable value, and also increasing the temperature in the reheat and low pressure turbine by gradually supplying the heating steam This prevents thermal stress from occurring due to temperature differences and rapid temperature rises.

However, in such a conventional reheater control device, if the rate of increase in the load of the steam turbine does not match the rate of change in the opening of the control valve, heating steam corresponding to the flow rate of cycle steam will not be supplied. , the temperature difference of the cycle steam at the inlet and outlet of the reheater becomes too large, or a sudden temperature rise cannot be avoided. This means that the operation of the steam turbine plant is dependent on the rate of change in the opening of the control valve, which is not appropriate for management purposes. A similar problem occurs when the load is lowered.

In addition, other conventional control devices measure the outlet pressure of the heating steam regulating valve and control the heating steam regulating valve by taking the difference between the pressure of the cycle steam and preventing sudden temperature changes and excessive pressure. This reduces thermal stress caused by large temperature differences. In other words, in this device, the temperature of cycle steam fluctuates greatly during load operation, so by estimating the temperature difference between cycle steam and heating steam and adjusting this, the temperature of cycle steam at the inlet of the reheater and the outlet can be adjusted. This is to reduce the temperature difference in the reheated heating steam temperature.

However, since these conventional control devices perform control based only on the pressure of the heated steam, it is not possible to accurately know the actual temperature of the cycle steam reheated in the reheater and its temperature changes. It is not possible to prevent thermal stress caused by temperature changes, and it is not possible to control the amount of heating steam according to the flow rate of cycle steam flowing from the high-pressure turbine. The problem is that it cannot be prevented.

[Purpose of the invention]

The present invention was made to solve such problems, and is a nuclear turbine plant that can prevent excessive thermal stress from occurring due to large temperature changes in the reheater and low-pressure turbine, and improve safety. An object of the present invention is to provide a reheater control device.

[Summary of the invention]

In order to achieve the above object, the present invention provides a reheater that heats the exhaust gas of a high-pressure turbine, which has been worked by saturated steam generated from a nuclear reactor as a steam source, with heated steam from the steam source on the way to the low-pressure turbine. In a reheater control device for a nuclear power turbine plant, the flow rate of steam flowing from the steam source to the high-pressure turbine is detected! Detected by the i1m detector, the heating steam pressure detector provided at a position after the control valve on the piping that leads the heating steam from the steam source to the reheater, and the flow detection limit. A limit value for the increase rate of the pressure shell constant value is calculated from the pressure setting value of the heating steam corresponding to the steam flow rate and the heating steam pressure detected by the pressure detector, and the heating steam is added to the pressure setting value. The present invention is characterized by comprising a calculation device that calculates and outputs an opening/closing signal for opening and closing the control valve so that the pressures match, and in the present invention, in a similar reheater control device for a nuclear turbine plant, a temperature detector for detecting the temperature of the cycle steam at the inlet and outlet of the heating device; and a heating steam pressure installed at a position downstream of the control valve on the piping leading the heating steam from the steam source to the reheater. A pressure setting value of the heating steam pressure according to the cycle steam temperature at the inlet of the reheater detected by the temperature detector and the temperature detector is determined, and this value is used as the temperature of the outlet cycle steam and its rate of change as well as the Performing a calculation to correct the pressure setting value based on the rate of change in the heating steam pressure, and calculating and outputting an opening/closing signal for opening and closing the control valve so that the heating steam pressure matches the corrected pressure setting value. It is characterized by being equipped with a calculation device, and both can effectively prevent the occurrence of large thermal stress in the reheater and low-pressure turbine, thereby increasing safety.

[Embodiments of the invention]

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

FIG. 1 is a block diagram showing a steam cycle of a nuclear turbine plant including a reheat IJAIIJ control device according to the present invention, in which steam generated in a steam generator 1, which is a nuclear reactor, is converted to rMIifl according to the load of the power plant. The steam is directed to a high pressure turbine 4 through two valves, a main steam stop valve 2 and a steam control valve 3. The pressure and temperature of the steam that has done work in the high-pressure turbine 4 decreases, and the moisture content in the steam also increases. It is reheated by heated steam in the reheater 6 and guided to the low pressure turbine 7. The steam that has done work in the low-pressure turbine 7 is condensed into water in a condenser 8, heated by air extracted from the turbine (not shown) in a feed water heater 9, and sent to the steam generator 1 again. A part of the steam generated from the steam generator 1 is branched on the upstream side of the main steam stop valve 2 and guided to the reheater 6 through the regulating valve 10.
It becomes heated steam.

This regulating valve 10 is connected to a valve driving device I (not shown) and has a function of adjusting the valve distance. 1
1. The flow rate of steam flowing into the high-pressure turbine 4 is detected by a steam flow rate detector 12 installed between the main steam stop valve 2 and the branch point of the pipe leading to the reheater 6, and the detection signal is input to the control device 11. has been done. Further, a pressure detector 13 for detecting the pressure of the heated steam is provided in the heated steam line leading from the regulating valve 10 to the reheater 6, and its detection signal is input to the control device 11. As a result,
A valve opening signal is generated from the steam flow rate flowing into the high-pressure turbine 4 and the heated steam pressure of the reheater 6, and is sent to the regulating valve 10 to control the amount of heated steam.

FIG. 2 is a block diagram showing the structure and operation of an embodiment of the reheater control device in FIG.
The steam flow port signal detected at step 2 is converted into a set value of heating steam pressure by a function generator 11a having the characteristics shown in FIG. 3, and is input to a comparator 11d. On the other hand, pressure detector 1
The heating steam pressure signal detected by 3 is added to the bias signal generated from the bias signal generator 11b,
The pressure is inputted to the rate of change limit value 11c to limit the rate of increase in pressure, and then inputted to the comparator 11d. The comparator 11d has a characteristic of preferentially selecting a low value signal, compares the output of the function generator 11a and the output of the rate of change limiter 11C, and outputs the low value as the heating steam pressure set value. . The heated steam pressure signal from the pressure detector 13 serves as a feedback signal for the output of the comparator 11d, and the difference between the two is input to the adjustment calculator 11e. The adjustment calculator 11e has, for example, a proportional integral function, and outputs a signal to the adjustment valve 10 so that the signal from the pressure detector 13 becomes part of the pressure set value output from the comparator 11d.

Next, the operation of this control device will be explained. Inside the reheater 6, the heated steam gives heat to the cycle steam using the heat of condensation and becomes wet steam, whose temperature becomes a saturation temperature at the pressure of the heated steam that varies depending on the opening degree of the control valve 10.

On the other hand, the flow rate of cycle steam to be heated is determined from the steam flow rate measured by the flow rate detector 12, except for the part extracted in the high-pressure turbine, but it changes greatly depending on changes in the load of the power generation plant. For example, when the load decreases, the flow rate of cycle steam also decreases, and the temperature of the heated steam flowing into the reheater 6 decreases accordingly.

In the present invention, in such a case, the pressure of the heated steam is fed back by a detection signal to lower the pressure of the heated steam. As a result, the temperature difference between the heated steam and the heated steam is reduced, and the temperature difference of the heated steam at the inlet and outlet of the reheater 6 is reduced, and the thermal stress in the reheater 6 and the low-pressure turbine is small. Become.

Further, the set value of the pressure of the heated steam detected by the pressure degree detector is limited by the rate of change limiter 11c. That is, according to the m4 diagram, which is a graph showing changes in the heating steam pressure setting value with respect to changes in the steam 111m flowing into the steam turbine, the output signal of the steam flow rate detector 12 is 14, the output signal of the function generator 11a is 16, The output signal of the rate of change limiter 11c is indicated by 15, and the rate of increase in the steam flow rate also increases, but the rate of change limiter 11C prevents the output signal from exceeding a predetermined value and the output of the rate of change limiter 5111c at point %B. It becomes lower than the output of the function generator 11a. Therefore, the heating steam pressure set value is the output signal 16 of the function generator 11a from A to B and after C, and the output signal 15 of the rate of change limiter 11C from B to C. No transient temperature differences occur between the heating steam and the cycle steam due to heat transfer delays.

FIG. 5 is a block diagram showing a steam cycle of a nuclear turbine plant including another reheater control device according to the present invention. In the following description, reference number 1 in FIG.
The parts corresponding to up to 0 are indicated by reference numbers incremented by 100, and since they have exactly the same configuration as in FIG. 1, their explanation will be omitted.

In this steam cycle, the reheat 11 is
A pressure detector 112 for detecting the pressure of the heated steam is installed in the heating steam line heading toward 06, and a temperature detector 113a for detecting the temperature of the steam to be heated before heating is connected to the high pressure turbine 104 and the moisture separator 105. Temperature detectors 113b for detecting the temperature after heating are provided on the outlet side of the reheater 106, respectively, and the detection signals generated by the above three detectors are input to the control device 111. . This control device 111 performs a predetermined calculation based on the heating steam pressure and the temperatures on the inlet side and outlet side of the reheater, sends a valve opening signal to the regulating valve 110, and the amount of heated steam is controlled.

FIG. 6 is a block diagram showing the structure and operation of one embodiment of the reheater control device in FIG.
The inlet temperature signal of the reheater 106 detected at step 3a passes through the function generator 111a and becomes the set value of the heating steam pressure. Further, the inlet temperature signal from the 1SIi degree detector 113a and the output signal of the bias signal generator 111d, which generates a bias signal representing the allowable temperature difference between the inlet and the outlet, are subtracted from the outlet temperature signal of the reheater 106; It is determined whether the temperature difference between the inlet and the outlet exceeds a permissible value.

That is, (reheater outlet temperature - reheater inlet temperature) - Allowable temperature difference Deviation from the allowable value of the temperature difference, and this value is converted into a correction amount of the pressure setting value by the gain setting device 111C. , the upper and lower limits are cut by the upper and lower limit limiter 111b, and added as a difference signal to the signal from the function generator 111a. Furthermore, the rate of change of the outlet temperature signal generated by the temperature detector 113b is determined by the differential calculator 111e, and the dead band setting device 111
Only a large rate of change value is extracted by f, and is added as a difference signal to the pressure set value signal via a gain setter 111g and an upper/lower limit limiter 111h, and acts as a correction signal.

Similarly, the heated steam pressure signal from the pressure detector 112 is added to the pressure set value signal as a difference signal through a differential calculator 111k, a dead band setter 111j, a gain setter 111m, and an upper/lower limit limiter 111n. , the pressure setpoint signal will be corrected if the rate of change is large.

With respect to the pressure set value signal corrected in this way, the pressure detection signal of the pressure detection 1112 acts as a feedback signal and is input to the adjustment calculator 111p. This regulator 111p has, for example, a proportional integral function, and the regulator valve 110 is driven by its output.

Next, the operation of this control device will be explained.

As described above, the temperature of the heated steam in the reheater 106 has a saturated humidity at that pressure, and the inlet temperature of the reheater 106 changes depending on the steam flow rate.

In the present invention, the temperature difference between the inlet side and the outlet side of the reheater 106 is detected, and the pressure setting value is corrected so that this difference is within an allowable value. Therefore, generation of large thermal stress in the reheater 106 is prevented. In particular, the temperature difference between the inlet and outlet sides of the cycle steam reheater 106, which occurs due to the large temperature difference between the heated steam and the heated steam and the small flow rate of the heated steam, lowers the heating steam pressure. effectively prevented.

Further, when the rate of change in the outlet temperature of the reheater and the heating steam pressure is large, the pressure setting value is corrected, which acts to reduce the rate of change in pressure.

As a result, thermal stress is applied to the low-pressure turbine 107 due to the large rate of change in the outlet temperature of the reheater, and thermal stress between the heating steam and cycle steam that occurs due to a delay in heat transfer due to the large rate of change in the pressure of the heated steam. Thermal stress is prevented from occurring in the heat exchange section of the reheater 106 due to the transient temperature difference.

Although details of the pressure sensor and temperature sensor are not mentioned in the above embodiments, any known type can be used as long as it can be efficiently converted into an electrical signal.

Further, the temperature detector 113a for detecting the inlet temperature in the second invention is provided between the high pressure turbine 104 and the moisture separator 105, but
It may also be provided between the

〔Effect of the invention〕

As described above, according to the present invention, the heating steam pressure of the reheater is set according to the flow rate of cycle steam, and is adjusted so that the rate of increase in heating steam pressure does not become excessive. The temperature difference and the m1fl difference of cycle steam between the inlet and outlet of the reheater do not become excessive, and the generation of thermal stress in the reheater and the low pressure turbine can be prevented and the safety of the nuclear reactor plant can be improved.

Also, other books y'ef! According to A, the heating steam pressure of the reheater is such that the temperature difference between the inlet and outlet of the cycle steam is within the permissible value, and the rate of change in the outlet temperature of the cycle steam and the rate of change in the heating steam pressure are not excessive. Since the temperature difference between the heating steam and the cycle steam is adjusted, the temperature difference between the heating steam and the cycle steam does not become excessive, and the occurrence of thermal stress in the reheater and the low pressure turbine can be prevented, thereby increasing the safety of the nuclear reactor plant.

[Brief explanation of the drawing]

Figure m1 is a block diagram showing the configuration of a nuclear turbine plant including an embodiment of the reheater v control device according to the present invention;
Fig. 2 is a block diagram showing the configuration and functions of an embodiment of the reheater @ control device, Fig. 3 is a graph showing the heating steam pressure set value characteristics of the function generator included in the control device, and Fig. 4 is FIG. 5 is a block diagram showing the configuration of a nuclear turbine plant including another reheater control device according to the present invention, and FIG. 6 is a graph showing the change characteristics of the set value of the heating steam pressure. FIG. 2 is a block diagram showing the configuration and operation. . 1.101...Steam generator, 2,102...Main steam stop valve, 3.103...Steam control valve, 4.104...
・High pressure turbine, 5,105...Moisture separator, 6.1
06...Reheater, 7.107...Low pressure turbine, 8
．． 108... Condenser, 9,109... Feed water heater,
10.110...Control valve, 11.111...Control device, 11a, 111a/II! number generator, 11b, 11
1d... Bias signal generator, 11c... Rate of change limiter, 11d... Comparator, 11e, 111p... Adjustment calculator, 111b, 111h, 111n-... Upper and lower limit limiter, 111c, 111g, 111m...gain setting device, 111e, 111-...differential calculator, 111
f. 111j... Dead band setting device. Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. Reheating of the high-pressure turbine exhaust gas, which has been worked by saturated steam generated from a nuclear reactor as a steam source, heated by heated steam from the steam source on the way to the low-pressure turbine. A reheater control device for a nuclear turbine plant that controls a reheater includes: a flow rate detector that detects a flow rate of steam flowing into the high-pressure turbine from the steam source; a heating steam pressure detector installed at a position downstream of the control valve on the piping; and a heating steam pressure set value corresponding to the steam flow rate detected by the flow rate detector and a pressure setting value of the heating steam detected by the pressure detector. a calculation device that calculates a limit value for the rate of increase of the pressure setting value from the heating steam pressure, and calculates and outputs an opening/closing signal for opening and closing the control valve so that the heating steam pressure matches the pressure setting value; A reheater control device for a nuclear turbine plant, characterized by comprising: 2. The reheater for a nuclear turbine plant according to claim 1, wherein the pressure set value is calculated by a predetermined function generator, and the limit value for the rate of increase of the pressure set value is calculated by a predetermined rate of change limiter. Control device. 3. A nuclear power plant that controls a reheater that heats the exhaust gas of a high-pressure turbine that has done work using saturated steam generated from a nuclear reactor, which is a steam source, with heated steam from the steam source on the way to a low-pressure turbine. A reheater control device for a turbine plant, comprising: a temperature detector that detects the temperature of cycle steam at the inlet and outlet of the reheater; and a control valve on a pipe that guides heated steam from the steam source to the reheater. A heating steam pressure detector installed at a later position than performs an operation to correct the pressure setting value based on the temperature of the outlet cycle steam and the rate of change thereof and the rate of change of the heating steam pressure, and performs the calculation so that the heating steam pressure matches the corrected pressure setting value. A reheater control device for a nuclear turbine plant, comprising: a calculation device that calculates and outputs an opening/closing signal for opening and closing a control valve.