JPH0146681B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for a steam turbine reheater, and particularly to a nuclear power turbine that reheats high-pressure turbine exhaust gas using a portion of the steam supplied to the turbine as a heating source. The present invention relates to a control device suitable for use in a reheater.

[Background of the invention]

An example of a conventional nuclear turbine reheater system is shown in FIG. This system consists of a nuclear reactor 1 that generates steam, a steam control valve 2 that adjusts the amount of steam flowing into the turbine to control turbine speed, turbine inlet steam pressure, and turbine output, and converts the thermal energy of the steam into rotational energy. a high-pressure turbine 3 that reheats the exhaust gas of the high-pressure turbine 3 using part of the inlet steam of the high-pressure turbine, a low-pressure turbine 5 that converts the thermal energy of the reheated steam into rotational energy, and the low-pressure A condenser 6 that condenses the exhaust gas of the turbine, a feed water heater 7 that heats up the condensate and supplies water to the reactor, a generator 9 that converts the rotational energy of the turbine into electrical energy, and a heating to the reheater 4. A heating steam control valve 8 that controls the flow rate of steam, a heating steam control device 10 that controls the opening degree of the heating steam control valve and adjusts the amount of heating steam, a reheat steam temperature detector 11, and a turbine speed and high pressure turbine inlet steam pressure. It is comprised of an output control device 12 that detects and controls the output of the turbine, and a steam control valve control device 13 that controls the steam control valve 2 based on an output control signal from the output control device 12. In this system, the turbine output is controlled by adjusting the opening of the steam control valve based on the turbine rotation speed and high-pressure turbine inlet pressure. The flow rate of steam leaving the nuclear reactor 1 is controlled by a steam control valve 2 and flows into a high pressure turbine 3. The steam that has done work in the high-pressure turbine 3 is led to a reheater 4 through a so-called low-temperature reheat pipe. After being heated by a portion of the high-pressure turbine inlet steam in the reheater 4, the reheated steam is guided to the low-pressure turbine 5 through a high-temperature reheat pipe to perform work.
Steam exiting the low pressure turbine 5 is condensed in a condenser 6. On the other hand, a part of the high-pressure turbine inlet steam passes through a heating steam pipe branched before the steam control valve 2, the flow rate is controlled by the heating steam control valve 8, and flows into the reheater 4, where it exchanges heat. Heat is recovered to the feed water heater 7. This amount of heating steam is constant above a certain load, but at partial loads there is a risk that excessive thermal stress will occur in the reheater and low pressure turbine due to the low high pressure exhaust temperature, so this should be prevented. Therefore, it is necessary to restrict the flow rate.

In FIG. 1, the reheated steam temperature is detected and the heated steam control valve 8 is controlled by the heated steam control device 10 to adjust the amount of steam. That is, the amount of heated steam is controlled by feedback of the temperature of the steam heated by the heated steam. According to this method, there is a long delay time from when the steam amount is adjusted by the heating steam control valve 8 until the temperature of the reheated steam changes, resulting in extremely poor responsiveness.

In order to improve this, as shown in Figure 2,
The pressure on the outlet side of the heated steam control valve 8 is detected by the heated steam pressure detector 14, and the detected pressure signal is inputted to the heated steam control device 10. In other words, a method of feeding back the pressure on the outlet side of the heating steam control valve 8 has also been conventionally used. In this method, the pressure target value on the outlet side of the heating steam control valve 8 is determined based on the reheating steam temperature to control the amount of heating steam.

Further, as shown in FIG. 3, the reheat steam pressure is detected by the reheat steam pressure detector 15 instead of the reheat steam temperature, and the pressure detection signal is sent to the heating steam control device 10.
A method of inputting information into the computer has also been used in the past.

In the two examples mentioned above, there is almost no delay between the pressure at the outlet side of the heating steam control valve 8, which is a local loop, and the opening degree of the heating steam control valve, and the responsiveness is good, but the responsiveness to the reheating steam temperature or pressure is poor. is not good. Therefore, the problem of poor stability of the control system still remains. Also, the reheat steam pressure or temperature varies due to variations in the steam flow rate. Therefore, it will change depending on the opening degree of the steam control valve. That is, it is an amount that varies depending on the control signal of the output control device 12. Therefore, when changing the turbine output using a control signal, there is a long delay before the heating steam control valve 8 settles and reaches a predetermined reheating steam pressure (temperature) based on the control signal, and during that time the steam temperature and steam flow change. The temperature difference between the road structures is large, and excessive thermal stress is generated in the reheater 4 and the low pressure turbine 5. Further, if the turbine output fluctuates continuously, problems such as hunting of the heating steam control valve may occur. In addition, since the pressure and temperature of reheated steam are not necessarily uniform in a certain cross section of the flow path, it is possible that the temperature or pressure is locally high (low) only in the detector area, and in this case, excessive thermal stress may also occur. This causes the occurrence of

Furthermore, as shown in FIG. 4, a method has been used in which the output of the generator 9 is fed back to the heating steam control device 10, but this method also has the same problems as the above-mentioned method.

[Purpose of the invention]

It is an object of the present invention to enable the amount of heating steam to be supplied to the reheater to be controlled by an output control signal from an output control device, thereby eliminating control delays, and allowing the amount of heating steam to flow into the reheater to be controlled by the output control signal from the output control device, thereby eliminating the control delay between the reheating steam and equipment such as the reheater and low-pressure turbine. An object of the present invention is to provide a control device for a steam turbine reheater that can minimize the temperature difference between and eliminate the occurrence of excessive thermal stress.

[Summary of the invention]

In order to achieve this object, the steam turbine reheater control device of the present invention is provided with a heating steam pressure detector that detects the heating steam pressure on the outlet side of the heating steam control valve, and an output control device in the heating steam control device. The output control signal is input and converted into a heating steam pressure request signal commensurate with the turbine output, and this signal is compared with the pressure signal from the heating steam pressure detector, and the deviation signal is used to control the heating steam control valve. It is characterized by being configured to perform opening/closing control.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 5 and 6. FIG. 5 shows a nuclear power turbine system diagram equipped with a reheater control device according to the present invention.
Components with the same reference numerals as those in the figures or FIG. 4 represent the same or equivalent components, and their explanations will be omitted.

The reheater control device according to the present invention includes a heating steam pressure detector 16 that detects the pressure on the outlet side of the heating steam control valve 8, and inputs an output control signal from the output control device 12 to the heating steam control device 10. In addition to converting the signal into a heating steam pressure request signal commensurate with the turbine output, this signal is compared with the pressure signal from the detector 16, and the opening/closing control of the heating steam control valve 8 is controlled based on the deviation signal, thereby controlling the amount of heating steam. It's starting to be controlled.

FIG. 6 shows a control block diagram of the internal logic of the heating steam control system. This heating steam control device 10 includes an output control signal receiving section 17, an output-heating steam pressure converting section 18, and a heating steam pressure signal receiving section 1.
9, a heated steam pressure comparison section 20. The output control signal from the output control device 12 is received by the output control signal receiving section 17 and becomes a turbine output signal. Next, the output-heating steam pressure converter 18 converts the signal into a heating steam pressure request signal commensurate with the turbine output using a predetermined function.

On the other hand, the pressure on the outlet side of the heated steam control valve 8 is detected by the heated steam pressure detector 16, and the pressure signal thereof is received by the heated steam pressure signal receiver 19. Then, it becomes an actual heating steam pressure signal, which is compared with the heating steam pressure request signal in the heating steam pressure comparison section 20, and the opening/closing of the heating steam control valve 8 is controlled based on the deviation signal. That is, in this method, the target value of the heating steam flow rate is set as the pressure on the outlet side of the heating steam control valve 8 by the output control signal of the turbine,
The opening degree of the heated steam control valve 8 is controlled by feeding back the pressure on the outlet side of the heated steam control valve 8.

On the other hand, as shown in FIG. 5, the output control of the turbine is performed by controlling the steam flow rate by adjusting the steam control valve 2 via the steam control valve control device 13 based on the output control signal from the output control device 12. This is done by

For example, when the output increases, the output control signal is raised to operate the steam control valve 2 in the opening direction to increase the steam flow rate, and the high-pressure turbine exhaust flow rate also increases accordingly. Therefore, when the heating steam flow rate of the reheater 4 is constant, the reheating steam temperature decreases. However, since the temperature of the low-pressure turbine inlet structure does not drop easily, the temperature difference between the steam and the structure increases and excessive thermal stress occurs.

However, in the reheater control device according to the present invention, when the output control signal is increased to increase the output, the opening degree of the heating steam control valve 8 is simultaneously increased, the heating steam flow rate is increased, and the reheating steam is increased. Minimize the temperature difference between the temperature and the structure. Therefore, there is almost no control delay that exists because the conventional control system uses feedback, and no excessive thermal stress occurs.

As described above, according to this embodiment, since the amount of heating steam is controlled by the turbine output control signal, there is almost no delay in control, and the temperature difference between the reheated steam and equipment such as the low pressure turbine and reheater is minimized. It is possible to minimize the occurrence of excessive thermal stress.

Next, an example of the internal logic of the output control device 12 and the steam control valve control device 13 is shown in FIG. The output control device 12 includes a comparator 21 that compares the actual output of the turbine with a set output, and a function generator 22 that outputs a steam control valve flow rate request signal to the steam control valve control device 13 based on the output deviation. The steam regulating valve control device 13 also includes a function generator 23 that converts a steam regulating valve flow rate request signal into a steam regulating valve opening request signal, and a comparator 24 that compares the steam regulating valve opening request signal with the actual opening. It consists of

In this example, the steam control valve flow rate request signal at position B in the figure is used as the output control signal, but instead of this, the set output at position A in the figure or the steam control valve opening at position C is used. The same effect as described above can be obtained by using a request signal.

〔Effect of the invention〕

As explained above, according to the present invention, since the amount of heated steam to the reheater is controlled by the output control signal from the output control device, there is no control delay, and the amount of heated steam to the reheater is controlled by the output control signal from the output control device. This minimizes the temperature difference between the heat sink and equipment such as low-pressure turbines and other equipment, and eliminates the occurrence of excessive thermal stress.

[Brief explanation of drawings]

Figures 1 to 4 are nuclear power turbine system diagrams showing an example of the prior art, Figures 5 to 7 show an embodiment of the present invention, and Figure 5 is equipped with a reheater control device according to the present invention. Nuclear turbine system diagram, No. 6
7 is a control block diagram showing an example of the internal logic of the heating steam control device, and FIG. 7 is a control block diagram showing an example of the internal logic of the output control device and the steam control valve control device. 1...Nuclear reactor, 2...Steam control valve, 3...High pressure turbine, 4...Reheater, 5...Low pressure turbine,
8...Heating steam control valve, 10...Heating steam control device, 12...Output control device, 13...Steam control valve control device, 16...Heating steam pressure detector, 17...
... Output control signal receiving section, 18... Output-heating steam pressure conversion section, 19... Heating steam pressure signal receiving section,
20... Heating steam pressure comparison section, 21, 24... Comparator, 22, 23... Function generator.

Claims (1)

[Claims] 1. A steam source, a high-pressure turbine that converts the thermal energy of main steam from the steam source into rotational energy, a steam control valve that adjusts the main steam flow rate, and a heating source that converts a portion of the high-pressure turbine inlet steam into rotational energy. A reheater that reheats high-pressure turbine exhaust gas, a low-pressure turbine that converts the thermal energy of the reheated steam into rotational energy, a heating steam control valve that adjusts the amount of heated steam in the reheater, and a steam control valve that controls the opening degree of the steam control valve. In a steam turbine equipped with an output control device that adjusts and controls the turbine output, and a heating steam control device that controls the opening degree of the heating steam control valve and adjusts the amount of heating steam, the heating steam pressure at the outlet side of the heating steam control valve is adjusted. A heating steam pressure detector is provided to detect the heating steam pressure, and the output control signal from the output control device is input to the heating steam control device and converted into a heating steam pressure request signal commensurate with the turbine output. Compare the pressure signal with
A control device for a steam turbine reheater, characterized in that the control device for a steam turbine reheater is configured to control the opening and closing of a heating steam control valve based on the deviation signal. 2. A control device for a steam turbine reheater according to claim 1, characterized in that a set output signal is used as the output control signal. 3. A control device for a steam turbine reheater according to claim 1, characterized in that a steam regulating valve flow rate request signal is used as the output control signal. 4. A control device for a steam turbine reheater according to claim 1, characterized in that a steam control valve opening request signal is used as the output control signal.