JPS63210504A - Feedwater flowmeter selector for water-level controller - 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] [Industrial Application Field] The present invention selects a feed water flowmeter that is applied to a water supply control system of a pressurized wooden nuclear reactor or a thermal power plant, especially a steam generator water level control device. The present invention relates to a water supply flow meter selection device for switching the water supply flow meter.

[Prior Art] Generally, two feedwater flowmeters are installed for use in the feedwater control system of pressurized water reactors (PWRs), etc., one for standby and the other for flow rate control, which is used for control. In the event that a meter malfunctions, an operator manually switches to the standby flowmeter.

Furthermore, the determination of whether a flow meter has failed is left to the operator.

[Problems to be Solved by the Invention] In this way, the operator determines whether there is a failure, and if it is determined to be a failure, the operator manually performs switching, so there is a possibility of misjudgment or erroneous operation. There is a problem with gender.

Therefore, when a feed water flow meter in the water supply control system of a PWR plant breaks down, the failure can be automatically detected, and the other healthy feed water flow meter can be automatically selected and switched to. It is preferable to do so.

[Means for Solving the Problems] Therefore, according to the present invention, the water level of the steam generator is adjusted by including a steam flow meter provided in a steam pipe and two water supply flow meters installed in parallel in a water supply pipe. In a steam generator water level control device for controlling a steam generator, in order to select and use one of the feedwater flowmeters, a comparison is made between the output of one of the feedwater flowmeters and the output of the steam flowmeter. a second comparator for making a comparison between the other output of the feedwater flowmeter and the output of the steam flowmeter; and a third comparator for making a comparison between the outputs of the two feedwater flowmeters. a first AN receiving both outputs of the first and third comparators.
D circuit; and a second AN receiving both outputs of the second and third comparators.
D 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 water supply flowmeters. Provided is a feedwater flowmeter selection device for a steam generator water level control device, characterized in that the feedwater flowmeter is selected and used.

[Operation] In the steam generator, in order to keep the steam generator water level constant, the steam meteor and the feed water flow rate match. Taking advantage of this property, the steam flow rate signal is used as a reference signal for the water supply flow rate.

If a deviation occurs in the output signals of the two feedwater flowmeters and the third comparator outputs a signal, the output of the feedwater flowmeter with the larger deviation from the steam flowrate signal, which is the reference signal, is used as the output signal from the first and second comparator. 2
Select with the comparator, determine that the water supply flow meter is malfunctioning, and
Automatically switches to the normal water supply flow meter that is on standby.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. In the figure, two water supply flowmeters 1 and 2 are installed in parallel in a water supply pipe to measure the flow rate of water supplied to a steam generator (not shown), and a steam flowmeter 3 is installed in parallel to the water supply pipe to measure the flow rate of water supplied to a steam generator (not shown). It is installed in the steam pipe to measure the

The steam generator is operated to keep the steam generator water level constant, so the steam flow rate and the feed water flow rate match. Therefore, if there is no abnormality in any of the flow meters 1 to 3, The signals from these flow meters are consistent.

The signals from the flowmeters 1 to 3 are given to comparators 4 to 6, respectively, as shown, and the comparator 4 inputs the signals from the water supply flowmeter 1 and the steam flowmeter 3, and calculates ,
When the deviation between the two lines exceeds the onboard value by R1, a high potential signal indicating a mismatch is sent to the coincidence circuit, that is, the first AND circuit 7.
Output to. In the comparator 5, the signals from the feed water flow meter 2 and the steam flow meter 3 are inputted and compared, and when the deviation between the two signals exceeds the set value, the negative number circuit, that is, the second AND A high potential signal indicating a mismatch is outputted to the circuit 8. The comparator 6 inputs the signals from the water supply flowmeters 1 and 2 and compares both signals, and when the deviation between the two signals exceeds a set value, both the first and second AND circuits 7 and 8 outputs a high potential signal indicating a mismatch. The output of the first AND circuit 7 is connected to a NOT circuit, that is, a NOT circuit 9.

The output of the 'F circuit 9 is connected to one input of a matching circuit, that is, a third AND circuit 10. The other input of the third AND circuit 10 receives the output from the second AND circuit 8.

As will become clear later, the third AND circuit 10 is
If there is no abnormality in either feed water flow meter 1 or 2, a low potential signal is output to selection relay R to de-energize the selection relay. The signal is selected and sent as a control signal S to a control device (not shown). Other flowmeters, namely feedwater flowmeter 1, are placed in the standby layer, while the third A
When the signal from the ND circuit 10 becomes high potential, the selection relay R is energized and switched to the illustrated contact position to select the signal from the water supply flow meter 1.

If there is no failure in both flowmeters 1 and 2, comparator 4
-6 all output low potential signals, therefore, the NOT circuit 9 outputs a high potential signal, the second AND circuit 8 outputs a low potential signal, and the third AND circuit 10 outputs a low potential signal. Selection relay R is non-energized.

If either the water supply flow meter] or the water supply flow meter 2 fails and the deviation of both signals exceeds the set value and the output of the third ratio +I [2 If there is a failure, the output of the second comparator 5 also becomes a high potential, and the second AND
The output of the circuit 8 also becomes a high potential, and the third AND circuit 10 is given a high potential. Since the NOT circuit 9 remains at a high potential, the output from the third AND circuit 10 will therefore switch from a low potential to a high potential due to a failure of the water supply flow meter 2. As a result, the selection relay R is energized and the contact position is changed by 17J, and the signal from the water supply flowmeter 1 is used as the control signal S instead of the water supply flowmeter 2.

If the water supply flow meter 1 is malfunctioning, the output of the second comparator 5 will remain at a low potential, but since the first and third comparators 4 and 6 will output a high potential, the first AND The circuit 7 also becomes a high potential output, switches the NOT circuit 9 to a low potential, and the third
The two inputs of the AND circuit 10 both have a low potential, and the selection relay R remains at a low potential, and the selection relay R remains unenergized, so the signal from the water supply flowmeter 2 controls the It remains used as signal S.

[Effects of the Invention] As described above, according to the present invention, when a water supply flowmeter malfunctions, the malfunction of the flowmeter is automatically determined and the flowmeter is automatically switched to a normal flowmeter. It is possible to avoid human erroneous operations, and since the correct signal can always be sent to the water supply control system, it has the effect of suppressing plant fluctuations.

[Brief explanation of the drawing]

The figure is a block circuit diagram showing a water supply flow meter selection device for a water level control device according to an embodiment of the present invention. In the figure, 1 and 2 are feed water flowmeters, 3 is a steam flowmeter, 4 is a first comparator, 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.

Claims (1)

[Scope of Claim] A steam generator water level control device that controls the water level of a steam generator, including a steam flow meter provided in a steam pipe and two water supply flow meters installed in parallel in a water supply pipe, comprising: a first comparator for making a comparison between the output of one of the feedwater flowmeters and the output of the steam flowmeter; and a first comparator for selecting and using one of the feedwater flowmeters; a second comparator that performs a comparison between the output of the steam flowmeter and the output of the steam flowmeter, and a third comparator that performs a comparison between the outputs of the two feedwater flowmeters; a first AN receiving both outputs of the comparator;
D circuit; and a second AN receiving both outputs of the second and third comparators.
D 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 water supply flowmeters. A feed water flow meter selection device for a steam generator water level control device, characterized in that the feed water flow meter selection device is configured to select and use the following.