JPH0743091B2 - Water supply flow meter selection device for water level control device - Google Patents

Description

Description: [Industrial application] The present invention selects and switches a feed water flow meter applied to a feed water control system of a pressurized water reactor or a thermal power plant, particularly a steam generator water level control device. The present invention relates to a feedwater flowmeter selection device for the.

[Prior Art] Generally, two feedwater flow meters used for a feedwater control system of a pressurized water reactor (PWR), etc. are installed, one is for standby, and the other is used for control. When the meter breaks down, the operator manually switches to the standby flow meter. Moreover, it is up to the operator to determine that the flow meter has failed.

[Problems to be Solved by the Invention] As described above, the operator determines the failure, and when the failure is determined, the operator manually switches the operation. Therefore, there is a possibility of erroneous determination or erroneous operation. There is a problem that there is.

Therefore, when the feed water flow meter of the feed water control system of the PWR plant fails, the failure can be automatically detected and another healthy water feed flow meter can be automatically selected and switched to it. It is preferable to do so.

[Means for Solving the Problems] Therefore, according to the present invention, the water level of the steam generator includes the steam flow meter provided in the steam pipe and the two feed water flow meters arranged in parallel in the water supply pipe. A steam generator water level control device for controlling one of the feedwater flowmeters, in order to select and use one of the feedwater flowmeters, a comparison is made between one output of the feedwater flowmeter and the output of the steam flowmeter. No. 1 comparator, a second comparator for making a comparison between the other output of the feed water flow meter and the output of the steam flow meter, and a third comparator for making a comparison between the outputs of the two feed water flow meters. And a first AND for receiving both outputs of the first and third comparators
A circuit and a second AND for receiving both outputs of the second and third comparators
Circuit and a third AND circuit that receives the output of the first AND circuit via a NOT circuit and receives the output of the second AND circuit, and one of the two feed water flow meters is provided. There is provided a feed water flow meter selection device for a steam generator water level control device, which is characterized in that it is selectively used.

[Operation] In the steam generator, in order to keep the water level of the steam generator constant, the steam flow rate and the feed water flow rate are the same. Utilizing this property, the steam flow rate signal is used as the reference signal of the feed water flow rate.
When a deviation occurs in the output signals of the two feed water flow meters and the third comparator outputs a signal, the output of the feed water flow meter having the larger deviation from the steam flow rate signal, which is the reference signal, is output as the first and the first. Two
Select with the comparator of, determine that the feed water flow meter is defective,
It automatically switches to the normal water supply flow meter on standby.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. In the figure, two feed water flow meters 1 and 2 are installed in parallel in a water feed pipe for measuring the feed water flow rate to a steam generator (not shown), and the steam flow meter 3 is a steam flow rate of the steam generator. Is installed in the steam pipe to measure the.

In the steam generator, since the operation is performed so as to keep the steam generator water level constant, the steam flow rate and the feed water flow rate match, and therefore, when there is no abnormality in any of the flow meters 1 to 3, The signals from these flow meters are in agreement.

The signals from the flowmeters 1 to 3 are given to the comparators 4 to 6, respectively, as shown in the figure. In the comparator 4, the signals from the feedwater flowmeter 1 and the steam flowmeter 3 are input and both signals are compared. , When the deviation between the two signals exceeds a set value, a high potential signal indicating a mismatch is output to the matching circuit, that is, the first AND circuit 7. In the comparator 5, the signals from the feed water flow meter 2 and the steam flow meter 3 are input and both signals are compared. When the deviation between the signals exceeds a set value, a coincidence circuit, that is, the second AN
It outputs a high potential signal to the D circuit 8 indicating the disagreement. The comparator 6 inputs the signals from the feedwater flow meters 1 and 2 and compares the two signals. When the deviation between the signals exceeds a set value, both the first and second AND circuits 7 and 8 are provided. And outputs a high potential signal indicating a mismatch. The output of the first AND circuit 7 is connected to a NOT circuit, that is, the NOT circuit 9, and the output of the NOT circuit 9 is connected to one input of the coincidence circuit, that is, the third AND circuit 10. The other input of the third AND circuit 10 receives the output from the second AND circuit 8.

As will be apparent later, the third AND circuit 10 outputs a low potential signal to the selection relay R and deselects the selection relay R when there is no abnormality in the feedwater flowmeters 1 and 2. Therefore, normally, the signal from the feed water flow meter 2 is selected by the selection relay R and is given to the control device (not shown) as the control signal S. The other flow meter, that is, the feed water flow meter 1, is placed in the standby state, but the third AND circuit 1
When the signal from 0 becomes a high potential, the selection relay R is excited and switched to the contact position shown in the figure, and the signal from the feed water flow meter 1 is selected.

If both flowmeters 1 and 2 have no failure, the comparator 4
~ 6 all output low potential signals, therefore NOT circuit 9
Is a high potential, the second AND circuit 8 outputs a low potential signal, the third AND circuit 10 outputs a low potential signal, and the selection relay R is not excited.

If either the feed water flow meter 1 or the feed water flow meter 2 fails and the deviation of both signals exceeds the set value and the output of the third comparator 6 becomes a high potential, if the feed water flow meter 2 fails. , Second
The output of the comparator 5 is also at a high potential, the output of the second AND circuit 8 is also at a high potential, and the high potential is applied to the third AND circuit 10. Since the NOT circuit 9 remains at the high potential, the output from the third AND circuit 10 is switched from the low potential to the high potential due to the failure of the feedwater flow meter 2. As a result, the selection relay R is excited to switch the contact position, and the signal from the feed water flow meter 1 is used as the control signal S instead of the feed water flow meter 2.

If the feedwater flow meter 1 is out of order, the output of the second comparator 5 remains at a low potential, but the first and third comparators 4 and 6 output a high potential. The circuit 7 also outputs a high potential, the NOT circuit 9 is switched to a low potential, and the third AND
The two inputs of the circuit 10 are both at a low potential, the selection relay R is kept at a low potential, and the selection relay R remains unexcited, so that the signal from the feed water flow meter 2 is controlled by the control signal S. Remains used as.

As described above, according to the present invention, when the feedwater flowmeter fails, the failure of the flowmeter is automatically determined and the normal flowmeter is automatically switched. It is possible to avoid human erroneous operation and to always send a correct signal to the water supply control system, so that it is possible to suppress plant fluctuations.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a feed water flow meter selection device of a water level control device according to an embodiment of the present invention. In the figure, 1 and 2 are feed water flow meters, 3 is a steam flow meter, and 4 is a first
, 5 is a second comparator, 6 is a third comparator, 7 is a first AND circuit, 8 is a second AND circuit, 9 is a NOT circuit, 10
Is a third AND circuit, and R is a selection relay.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Teranishi 1-1-1, Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (72) Inventor Tadashi Nakao Kazu, Hyogo-ku, Kobe-shi, Hyogo 1-1-1 Tasakicho Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (56) Reference JP-A-57-131904 (JP, A)

Claims (1)

[Claims] 1. A steam generator water level control device for controlling the water level of a steam generator, comprising: a steam flow meter provided on a steam pipe; and two feed water flow meters arranged in parallel on a water supply pipe. A first comparator for making a comparison between one output of the feed water flow meter and an output of the steam flow meter to select and use one of the flow meter, and the other of the feed water flow meter A second comparator for comparing the output of the steam flow meter with an output of the steam flow meter; a third comparator for comparing the outputs of the two feed water flow meters; and the first and third comparisons. First AND receiving both outputs of the vessel
A circuit and a second AND for receiving both outputs of the second and third comparators
Circuit and a third AND circuit that receives the output of the first AND circuit via a NOT circuit and receives the output of the second AND circuit, and one of the two feed water flow meters is provided. A supply water flow meter selection device for a steam generator water level control device, which is characterized in that it is used by being selected.