JPH0248880B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nuclear power turbine plant having a reheater for reheating steam from a high pressure turbine by using a portion of the steam supplied to the turbine, and more particularly to a nuclear power turbine plant having a reheater for reheating steam from a high pressure turbine by using a portion of the steam supplied to the turbine. The present invention relates to a reheater control device for a nuclear turbine plant that controls the supply of heating steam to a nuclear turbine plant.

The conventional technology disclosed in Japanese Patent Publication No. 55-38563 measures the outlet pressure of the heating steam control valve,
The difference in pressure from the turbine cycle is taken into account to control the heating steam control valve, thereby reducing thermal stress caused by rapid temperature changes.

This is because the temperature of the cycle steam in the reheater fluctuates greatly during load operation, so by taking the cycle pressure, the temperature of the cycle steam in the reheater can be represented, and the cycle steam in the reheater can be compared with the cycle steam in the reheater. The purpose is to reduce the temperature difference between heating steam.

However, in the conventional reheater control device described above, it is not possible to control the amount of heated steam commensurate with the flow rate from the high-pressure turbine, so it is difficult to prevent sudden temperature changes in the steam reheated in the reheater. The disadvantage is that it cannot be done.

An object of the present invention is to provide a reheater control device for a nuclear power turbine plant that prevents overcooling of the reheater and low-pressure turbine and the generation of excessive thermal stress due to large temperature changes.

The present invention is characterized in that a reheater control device for a nuclear turbine plant equipped with a reheater that guides heated steam from a steam source through a pipe having a control valve is provided with a detector that indicates the generator output; It consists of a calculation device that calculates the amount of heated steam supplied to the reheater based on the generator output obtained from the generator, and a valve drive device that operates the opening and closing of the control valve according to the output of the calculation device. This makes it possible to always supply the optimum amount of heating steam to the reheater.

Next, a reheater control device for a nuclear power plant, which is an embodiment of the present invention, will be described with reference to the drawings. FIG. 1 shows the steam cycle of a nuclear turbine plant. In the figure, steam generated in a steam generator 1 is guided to a high-pressure turbine 6 through a main steam stop valve 2 and a steam control valve 3. The main steam stop valve 2 and the steam control valve 3 are opened and closed by the control device 5 so as to reach a target speed based on a speed signal from a speed detector 4 of the steam turbine rotor. The steam that does work in the high-pressure turbine 6 and drives the high-pressure turbine has a lower pressure and temperature and an increased moisture content, so after separating the moisture in the moisture separator 7, the steam is recycled. It is guided to the heating device 8. The heat source of the reheater 8 uses steam generated by the steam generator 1 and branches from the upstream side of the main steam stop valve 2. The steam whose temperature has been increased by exchanging heat with the heated steam in the reheater 8 is called reheated steam, and is led to the low pressure turbine 9. High pressure turbine 6 and low pressure turbine 9 are coupled to generator 10 and drive generator 10 . The steam that has done work in the low pressure turbine 9 and generated driving power is transferred to the condenser 1
1, condenses into water, and feeds water heater 1.
Leads to 2. Heated steam after heat exchange with the reheater is also introduced into the feedwater heater 12, and heats the water from the condenser. The heated water is transferred to steam generator 1
supplied to

A heating steam control valve 14 is installed in the heating steam piping led to the reheater 8, and its opening and closing are controlled by a control device 16 and a drive device 15.

In other words, the signal L of the generator output (detector 17)
(see FIG. 2) is input to the control device 16, which is sent as a valve opening signal to the control valve drive device 15, and the amount of heated steam is controlled by opening and closing the heated steam control valve 14.

The generator output signal L is approximately equal to the turbine load and is proportional to the turbine steam flow rate. At low loads,
The turbine steam flow rate is small, so the amount of reheater heating steam may also be small. If the amount of heating steam is left unchanged when the load decreases, looking inside the reheater 8, as the load decreases, the temperature of the steam coming out of the high-pressure turbine 6, that is, the temperature of the heated side flowing into the reheater 8, will decrease. is in a downward direction, the temperature difference between the heating side steam and the heated side steam becomes large, and stress is generated inside the reheater. Therefore, when the load decreases, the opening degree of the heating steam control valve 14 is reduced to lower the outlet pressure of the valve, thereby lowering the temperature of the heating steam. Regarding thermal stress in the rotor of the low-pressure turbine 9, changes in the inlet steam temperature of the low-pressure turbine 9, that is, the reheater outlet steam temperature, pose a problem. Even if the load decreases significantly and the steam flow rate from the high-pressure turbine 6 decreases, if the heating side steam flow rate remains the same, the heated side flow rate will decrease, but the heating side flow rate will remain the same, so steam will not flow out from the high-pressure turbine. Even if the steam temperature decreases slightly, the reheater outlet steam temperature approaches the heating side steam temperature, and the temperature tends to rise, which may become a source of stress for the low-pressure turbine rotor. For these reasons, it is desirable that the amount of heating steam supplied to the reheater 8 is increased or decreased depending on the turbine load. Further, when the load is cut off, the steam control valve 3 of the turbine is suddenly closed to throttle the steam in response to a signal (not shown) for a sudden decrease in the generator load. At this time, since the turbine flow rate suddenly decreases, it is desirable to rapidly decrease the reheater heating steam so that the heating steam does not flow without steam on the heated side.This is done by detecting the generator output and Controlling the opening and closing of the control valve 14 can be achieved.

FIG. 2 is a block diagram showing the control mechanism of the reheater described above. The detected generator output signal L is converted into an opening/closing signal V for the heating steam control valve 14 by the following calculation within the controller of the heating steam control valve 14. An appropriate bias signal B is applied to the generator output signal L by a bias setter 16a. This includes the initial load after joining (about 5%), etc.
When the load is low after startup, the internal temperature of the reheater 8 and the rotor of the low-pressure turbine 9 are both low, so a large temperature difference will occur when heated steam is passed through the reheater. This is to stop the inflow of heating steam when the load is below. Next, the amount of heated steam f ₁ is determined by the function generator 16b based on the biased generator output signal. An example of the function generator 16b is shown in FIG. 3, in which the generator output signal after the bias is subtracted is proportional to the control valve flow signal. Next, based on the characteristics of the valve opening degree and valve flow rate of the heating steam control valve 14, a heating steam control valve opening degree signal V is generated from the heating steam amount signal _f1 using the function generator 16c. An example of the function generator 16c is shown in FIG. This valve opening degree signal is sent to the control valve driving device 15, and the control valve 14 is controlled to open and close to the required opening degree.

Next, a reheater control device for a nuclear turbine plant, which is another embodiment of the present invention, will be described.

In one embodiment of the present invention, in addition to the generator output, the steam pressure on the downstream side of the heating steam control valve 14 is detected to control the opening degree of the heating steam control valve 14. This embodiment is shown in FIG. To explain only the differences from FIG. 1, the steam pressure detector 18 on the downstream side of the heated steam control valve 14 detects the steam pressure P, and from this, the control device 16 calculates the heated steam flow rate to control the valve. The opening degree is corrected. FIG. 6 shows a block diagram of the control mechanism.
In the example shown in FIG _. 6, in addition to the signal shown in FIG. to calculate the actual flow rate signal f ₀ , take the deviation between this signal f ₀ and the heating steam flow rate signal f ₁ calculated by the function generator 16b, and multiply by a coefficient K to correct the flow rate. The valve opening degree of the valve 4 is corrected.

Further, the function generator 16c calculates the valve opening signal V from the actual flow rate signal _f0 , and corrects the opening of the control valve 14 by taking the deviation from the valve opening signal obtained from the heated steam flow rate signal _f1 . You can do it like this.

According to the present invention, it is possible to realize a reheater control device for a nuclear turbine plant that can prevent overcooling of the reheater and the low-pressure turbine and generation of excessive thermal stress.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a control device for a nuclear turbine plant which is an embodiment of the present invention, Fig. 2 is a block diagram showing details of the control device in Fig. 1, and Fig. 3 is a block diagram of Fig. 2. 4 is a characteristic diagram of a function generator that calculates the flow rate of heated steam shown in FIG. 4, a characteristic diagram of a function generator that calculates the control valve opening shown in the block diagram of FIG. 2, and FIG. A system diagram showing a control device of a nuclear turbine plant as an example,
FIG. 6 is a block diagram showing details of the control device of FIG. 5. DESCRIPTION OF SYMBOLS 1...Steam generator, 2...Main steam stop valve, 3...Steam control valve, 4...Speed detector, 5...Control device, 6...High pressure turbine, 7...Moisture separator, 8...Reheater, 9...
Low pressure turbine, 10... Generator, 14... Heating steam control valve, 15... Drive device, 16... Control device, 16a
...Bias setting device, 16b, 16c...Function generator, 16d...Flow rate calculator, 17...Load detector, 1
8...Pressure detector.

Claims (1)

[Scope of Claims] 1. A reheater control device for a nuclear turbine plant equipped with a reheater in which heated steam is guided from a steam source via a control valve and which heats main steam with the heated steam, comprising: an output detector that detects the generator output; a calculation device that calculates the heating steam flow rate of the reheater according to the generator output based on the signal obtained by the detector; and a calculation device that calculates the heating steam flow rate of the reheater according to the generator output; A reheater control device for a nuclear turbine plant, comprising: a valve drive device that operates the control valve; 2. A detection device for detecting the state quantity of the heated steam obtained from the reheater is provided, and the heating steam flow rate is calculated by the calculation device based on the detection signal of the detection device and the generator output signal. A reheater control device for a nuclear turbine plant according to claim 1.