JPS6128802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention provides for a power generation boiler to operate without stopping power generation equipment such as a turbine when a power generation boiler or a feed water pump in a nuclear reactor trips (stops). The present invention relates to a load runback device for a water feed pump that reduces the main steam pressure to a level corresponding to the load that can be taken by a normal water pump.

(Technical background of the invention and its problems) In recent steam power generation equipment, in order to increase power generation efficiency, equipment that performs so-called variable pressure motion that changes the load by changing the inflow steam pressure of the turbine has been proposed. At near rated load, supercritical pressure operation is performed, and at low load, the pressure is maintained at a level that allows the entire steam power generation facility to operate efficiently.

Generally, in a transformer-operated thermal power generation facility, as shown in FIG. The water is supplied to each water booster pump 5a, 5b provided in parallel, and the water booster pump 5a, 5b and each water pump 6a,
6b, and the water supply pressure is maintained at a pressure corresponding to the main steam pressure. These water supply pumps 6a, 6b
The feed water discharged is further heated by the high-pressure feed water heater 7, and this water is fed to the next boiler 8, which turns it into steam through the heat exchange action of the boiler 8.
This steam is supplied through a steam control valve 11 to a turbine 10 directly connected to a generator 9, which rotates the turbine 10 to perform work.The generator 9 connected to this turbine 10 generates electricity. The exhausted steam is then returned to the condenser 1.

In this way, the amount of steam generated by the boiler 8 is adjusted by the amount of fuel input to the boiler 3, and at the same time, the flow rate and pressure are adjusted by the steam control valve 11. ing. Therefore, the pressure obtained by adding losses due to piping and the like to this main steam pressure becomes the discharge pressure of each of the water supply pumps 6a and 6b.

Therefore, the outlet steam pressure of the boiler 8, that is, the inlet pressure of the steam control valve 11, is determined by the discharge pressure of the water supply pumps 6a, 6b. or,
The relationship between the discharge pressure of the water supply pumps 6a, 6b, the main steam pressure, and the discharge flow rate or power generation load of the water supply pumps 6a, 6b is shown in FIG.

That is, in FIG. 2, the curve c shows the inlet steam pressure of the steam control valve 11, and the curve b shows the water supply pressure curves of the water supply pumps 6a and 6b, and the water supply pressure curve b and the inlet steam pressure curve c pressure difference a
is the pressure loss in the piping, etc. from the outlet of the water supply pumps 6a, 6b to the steam control valve 11. Further, the number of revolutions of the water supply pumps 6a, 6b is represented by n.

Therefore, the plurality of water supply pumps 6a, 6b mentioned above
If one of the pumps (for example, the water supply pump 6a) experiences an abnormal trip for some reason, the operation is automatically stopped in order to protect the remaining normal water supply pump 6b. That is, it is assumed that each of the water supply pumps 6a and 6b is operating normally, that is, at point A in FIG. In this state, each water supply pump 6a, 6b
have the same capacity and load, so the flow rate for one unit is 1/2 the capacity of point B in Figure 2 above.
Moreover, since this discharge pressure is the same for both units, it becomes the discharge pressure at point C. On the other hand, the rotation speeds of the water supply pumps 6a and 6b at this time are curve no.

However, one of the water supply pumps 6a and 6b
If an abnormal trip occurs in the pump, the discharge flow rate will decrease rapidly, so the remaining one water supply pump 6b
The discharge flow rate (rotation point) before tripping must be determined.

However, although the command given to the normal water supply pump 6b is immediately given to maintain the flow rate at point RO, the normal water supply pump 6b does not operate in response to such instantaneous operation. I can't do it.

Furthermore, although this water supply pump 6b is allowed to be overloaded by a few percent of its rating, significant overload operation is not permitted, and in the event of a significant overload, this normal water supply pump 6b will be Mechanical overload occurs and operation is forced to stop.

This results in stopping the water supply to the boiler 8, which ultimately means stopping the entire power generation equipment, which has disadvantages such as having to stop the functions of the power generation equipment.

[Purpose of the invention]

In order to eliminate the above-mentioned drawbacks, the present invention provides a transformer power generation facility equipped with a plurality of feed water pumps in a power generation boiler or a nuclear reactor, in which a turbine load and pressure control circuit due to runback and a flow rate at the time of trip of the feed water pump are provided. A setting circuit is installed to control the steam control valve and each flow control valve of the water pump when one of the multiple water pumps goes abnormally high, thereby reducing the power generation that can be generated by the remaining normal water pumps. The purpose of the present invention is to provide a load runback device in the event of a water pump trip, which controls a turbine by changing the main steam pressure up to the load, and also allows continuous operation of the entire power generation facility without stopping it. It is something.

[Embodiments of the invention]

Hereinafter, the present invention will be described with reference to an illustrated embodiment.

In FIGS. 3 and 4, reference numeral 21 is a turbine output setting device, and the output setting signal from this turbine output setting device 21 is sent to an upper/lower limit setting device 22.
The output signal of the rate of change limiter 23 is sequentially applied to the upper and lower limiter 22 adjusted by the setting signal of a and the rate of change limiter 23 adjusted by the setting signal of the rate of change setter 23a. , is corrected in the adder 25 using a correction signal from the deviation corrector 24. The output signal of the rate of change limiter 23 is also input to a comparator 27, where it is compared with the output signal from the output transmitter 26 of the generator 9, and the deviation signal is sent to the regulator via the correction balancer 28. 32 and the regulator 3
The steam control valve 11 is controlled by the output signal No. 2. The correction balancer 28 includes a comparator that compares output signals with a main steam pressure setting device 29 that sets the inlet steam pressure of the steam control valve 11 and a main steam pressure transmitter 30 that detects the steam pressure at the inlet of the steam control valve 11. A deviation signal from the comparator 31 is input, and the output signal from the comparator 27 is corrected.

On the other hand, the adder 25 is connected to a water supply flow rate setting circuit. This water supply flow rate setting circuit is composed of a fuel water supply amount calculator 33, a multiplier 35 to which a signal from a temperature corrector 34 is input, a first cross limit 36, a rate of change limiter 37, and a second cross limit 38. A total water supply flow rate setting signal for the water supply pump is calculated based on the output signal from the adder 25, and is input to the comparator 39 via the changeover switch 50c. The comparator 39 also receives the total feed water flow rate signal supplied to the boiler from the feed water pump, which is compared with the setting signal output from the feed water flow rate setting device, and the deviation signal is input to the regulator 40. It is designed so that The output signals from the regulator 40 are sent to comparators 43a and 4 via automatic changeover switches 42a and 12b, respectively.
3b, and is compared with the discharge flow rate signal from each water pump in both comparators 43a, 43b, and each deviation signal is applied to the flow rate control valves 41a, 41b of the water pump via regulators 44a, 44b, Opening control is performed.

On the other hand, a load and pressure control circuit for the turbine 10 is connected between the turbine output setter 21 and the upper/lower limiter 22 by a runback including a first automatic trip switch 74a. This load and pressure control circuit includes a first function generator 45 that determines a turbine output setting signal from the water supply flow rate to the boiler 8, and a first function generator 45 that determines the inlet steam pressure setting value of the steam control valve 11 from this turbine output setting signal. This load and pressure control circuit has two function generators 46, and when the water supply pump 6a or 6b trips, the output setting signal from the output setting device 21 is sent to the first automatic trip switch 47a. At the same time, the second automatic trip switch 47b cuts off the input signal from the main steam pressure setting device 29, and transmits the signal from the first function generator 45 to the upper/lower limiter 22. The output signal of the function generator 46 is sent to the comparator 31, and the comparator 31 and the comparator 2
Both deviation signals from 7 are transmitted to a regulator 32 via a correction balancer 28, and the steam control valve 11 is controlled by a control signal output from the regulator 32.

That is, when the water supply pump 6a trips abnormally, the first and second automatic trip changeover switches 47a, 47b are switched, and the output signal from the first function generator 45 is used as the turbine output setting signal for the upper and lower limit limiters 22. On the other hand, the output signal from the second function generator 46 is applied to the comparator 31 as the main steam pressure setting signal, and the steam control valve 11 is controlled based on both setting signals.

On the other hand, a flow rate setting circuit by tripping the water supply pump 6a or 6b is connected between the comparator 39 and the changeover switch 50c that supplies and cuts off the signal from the second cross limit 38 of the water supply flow rate setting circuit. . That is, this trip-based flow rate setting circuit includes maximum flow rate setters 49a and 49b that receive the output signal of the discharge header pressure detector 48 of the water supply pump and output the maximum flow rate setting signal of each water supply pump, and the setter. a changeover switch 50 for inputting a setting signal to the comparator 39;
For example, when the water supply pump 6a trips, the changeover switch 50c cuts off the water supply flow rate setting signal from the water supply flow rate setting circuit, and at the same time, the changeover switch 50a turns on. and water supply pump 6
A setting signal from the maximum flow rate setter 49b of the water supply pump 6b is inputted to the comparator 39, and the flow rate adjustment valve 41b of the water supply pump 6b is thereby adjusted so that the water supply flow rate of the normally operating water supply pump 6b becomes the maximum flow rate.
is controlled.

In this way, the present invention provides a system for detecting problems when one or more of a number of water supply pumps makes an abnormal trip.
The main steam pressure setting signal and the output setting signal are changed in accordance with the feed water flow rate that can be delivered by the remaining normal feed water pump, so that a load drop of the turbine (variable pressure operation runback) occurs smoothly and quickly,
It is possible to operate continuously without stopping the entire transformer power generation equipment.

This will be explained with reference to the graph shown in FIG. 4 as follows.

That is, when one of the water supply pumps 6a stops, the system simultaneously shifts to variable pressure operation runback. In other words, as soon as it is detected that one of the water supply pumps 6a has tripped, the set value of the main steam pressure is lowered to a pressure level corresponding to the rotational speed NO of the remaining water supply pumps 6b, and the main steam pressure is reduced to a pressure level corresponding to the rotational speed NO of the remaining water supply pumps 6b. When the water supply pump 6b has a margin, the rotation speed of the water supply pump 6b is increased so as to supply the maximum water supply flow rate.

However, when a certain water pump trips,
At the same time, since the remaining normal water supply pump has the rotational speed of NO, the pressure changes to the discharge pressure (point C) at the intersection of NO and the discharge pressure curve b (point G), so this corresponds to The set value of the main steam pressure is changed so that the main steam pressure (point R) is reached, and the discharge flow rate of the feedwater pump is set to point N.

Therefore, when there is room in the normal rotational speed of the water supply pump, the rotational speed is increased, so the point where the drop in main steam pressure matches the main steam pressure corresponding to the increased rotational speed of the water supply pump. The main steam pressure drop and load drop stop at this matching point, allowing operation at a higher load than the load point. In other words, it corresponds to the main steam pressure corresponding to the discharge pressure of the feed water pump when the main steam pressure falls from the pressure at two points along the main steam pressure curve c and the rotation speed of the remaining feed water pump changes from NO to N+1. Then, the point L becomes the balance point and becomes the power generation load at the point O.

〔Effect of the invention〕

As explained above, in the present invention, a first function generator that calculates a turbine output setting value from the flow rate of water supplied to the boiler and outputs a turbine output setting signal, and a turbine output by the first function generator are provided. A second function generator outputs an inlet steam pressure setting signal for the steam control valve from a set value, and operates when any of the plurality of feed water pumps connected in parallel is tripped, and outputs a turbine output setting signal to output the turbine output. a first trip automatic changeover switch that switches from the setting signal from the setting device to the output signal of the first function generator; and a first trip automatic changeover switch that operates when the water pump trips and converts the main steam pressure setting signal into the setting signal from the main steam pressure setting device. The maximum flow rate setting signal for each feed water pump is set by a second trip automatic changeover switch that switches from to the output signal from the second function generator, and the feed water pressure signal from the discharge header pressure detector of each feed pump. The maximum flow rate setting device that outputs and operates when the above water supply pump trips,
A changeover switch device is provided to switch the water supply flow rate setting signal of the water supply pump from the setting signal from the water supply flow rate setting device to the output signal from the maximum flow rate setting device corresponding to the water supply pump that is not tripped. In the event of a trip, the turbine output set value and main steam pressure set value are changed according to the feed water flow rate that can be supplied by the remaining normal feed water pumps, and the turbine output, that is, the main steam pressure set value, is changed in accordance with these set values. The opening degree of the adjustment valve is controlled. Therefore, not only can the power generation equipment be continuously operated without stopping the entire power generation equipment, but also excellent effects such as improving the operating efficiency of the power generation equipment can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a variable voltage operation thermal power generation facility, FIG. 2 is a diagram showing the relationship between the discharge pressure and discharge flow rate of the water supply pump of the power generation facility in FIG. 1, and FIG. FIG. 4, a system diagram of the load runback device during a pump trip, is a diagram showing the relationship between the discharge pressure and the discharge flow rate of the water supply pump according to the present invention. 1... Condenser, 2... Condensate pump, 4... Deaerator, 6
a, 6b... Water supply pump, 7... High pressure water supply heater, 8
...Boiler, 10...Turbine, 11...Steam control valve, 21...Turbine output setting device, 22...Upper/lower limit limiter, 41a, 41b...Flow rate control valve, 45
...first function generator, 46...second function generator,
47a...first automatic trip switch, 47
b...Second trip automatic changeover switch, 48...Water pump discharge pressure detector, 49a, 49b...Maximum flow rate setting device, 50a, 50b, 50c...Switching switch.

Claims (1)

[Claims] 1 A first function generator that calculates a turbine output setting value from the flow rate of water supplied to the boiler and outputs a turbine output setting signal; a second function generator that outputs a pressure setting signal;
A first actuator that operates when any one of the plurality of water supply pumps connected in parallel is tripped, and switches the turbine output setting signal from the setting signal of the turbine output setting device to the output signal of the first function generator.
a trip automatic changeover switch, and a second trip automatic changeover switch that operates when the feedwater pump trips and switches the main steam pressure setting signal from the setting signal from the main steam pressure setting device to the output signal from the second function generator. a maximum flow rate setting device that outputs a maximum flow rate setting signal for each water pump based on the water supply pressure signal from the discharge header pressure detector of each water pump; and a changeover switch for switching the water supply flow rate setting signal to the output signal from the maximum flow rate setting device corresponding to the water supply pump that is not tripped from the setting signal from the water supply flow rate setting device, when the water supply pump trips. Load runback device.