JPS6214042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deaerator auxiliary steam pressure control device in a thermal or nuclear power plant.

Generally, the internal pressure of a deaerator used in a thermal power generation or nuclear power generation plant is normally controlled to a predetermined value. On the other hand, when supplying water to a boiler in a plant, it is necessary to perform a so-called clean-up, in which equipment in front of the boiler, such as the feed water heater or piping line, is cleaned in advance to supply highly purified water to the boiler. For this purpose, the temperature of the water must be maintained at an appropriate value, and therefore, as described above, it is necessary to constantly control the pressure inside the deaerator.

A conventional deaerator auxiliary steam pressure control device has a configuration shown in FIG. In FIG. 1, an auxiliary boiler 1 for startup is usually provided as a steam source for a deaerator 21, and auxiliary steam generated in this auxiliary boiler 1 is transferred to an auxiliary steam header 2 and an auxiliary steam pressure control valve ( The gas is sent to the deaerator 21 via a valve (hereinafter simply referred to as a "control valve") 3. The detector 4 detects the pressure on the auxiliary boiler 1 side (primary pressure),
The detector 6 also detects the pressure on the deaerator 21 side (secondary pressure), which is the internal pressure of the deaerator 21. Target primary pressure and secondary pressure (reference) are set in the controllers 5 and 7 connected to the detectors 4 and 6, and the outputs from the detectors 4 and 6 are compared with this reference. For example, the difference between the detector output and the reference is sent to the low value priority circuit 8 as a control signal. The low value priority circuit 8 selects the lower value of the control signals. The selected control signal is sent to an electrical signal/air signal converter (E/P) via an automatic/manual selection section 9.
The signal is sent to the converter (converter) 10, converted into an air signal, which opens and closes the control valve 3, and at the same time is fed back to the controllers 5 and 7 via isolators 11 and 12, respectively, to prevent overcontrol. Here, the automatic/manual selection section 9 is for switching between automatic control and manual control.

Now, if we consider the case where the secondary pressure has become lower than the target value, the output of the detector 6 will show a lower value than when the secondary pressure is at the target value. The controller 7 adds a value obtained by subtracting the reference from this low detector output, that is, a negative value, to a bias, and outputs the control signal to the low value priority circuit 8 .
The low value priority circuit 8 selects a control signal of the controller 7 which has a value lower than the bias value with respect to a control signal of the controller 5 which has a bias value because the primary pressure is set to the target value. select. This control signal is transmitted to the automatic/manual selection section 9.
The signal reaches the E/P converter 10 via the air signal and is converted into an air signal, which drives the control valve 3 in the direction of opening. As a result, auxiliary steam flows into the deaerator 21 side, and the secondary pressure is controlled to the target value.

Conversely, when the secondary pressure becomes higher than the target value, the output of the detector 6 shows a higher value than when the secondary pressure is at the target value. The controller 7 adds a value obtained by subtracting the reference from this high detector output, that is, a positive value, to a bias, and outputs the control signal to the low value priority circuit 8. The low value priority circuit 8 selects a controller 7 higher than this bias value.
The control signal of the controller 5, which has the same bias value as described above, is selected for the control signal of the controller 5. This control signal is converted into an air signal in the same manner as described above, and this time drives the control valve 3 in the closing direction.
This prevents the auxiliary steam from flowing into the deaerator 21 side, and the secondary pressure is controlled to the target value.
The same applies when the primary pressure changes.

However, the capacity of the auxiliary boiler 1 that sends steam to the deaerator 21 is generally limited for economic reasons.
It is normal that the necessary minimum amount is installed, and in addition to the deaerator 21, auxiliary steam is also supplied to the flue gas desulfurization equipment, ash processing heating, turbine gland, turbine warming, etc. Absolute quantity is insufficient. Therefore, the primary pressure decreases, causing a so-called hunting phenomenon. That is, as described above, as the primary pressure decreases, the low value priority circuit 8 selects the control signal of the controller 5, and the control valve 3 is driven in the closing direction, but along with this, the secondary pressure decreases. The voltage starts to decrease, and eventually the low value priority circuit 8 comes to select the control signal of the controller 7, and the control valve 3 is driven in the opening direction. At this time, it is sufficient if the capacity of the auxiliary boiler 1 is sufficient, but as described above, this is insufficient and the primary pressure begins to decrease again. The above operations are repeated, resulting in a hunting phenomenon. In such a case,
Conventionally, a method has been used in which the automatic/manual selection section 9 is switched to manual and the operator manually sets the pressure inside the deaerator 21, that is, the secondary pressure, to the lowest allowable value while adjusting the pressure. In such a situation, the automatic control device cannot be used effectively, and the operator has to put in more effort than necessary.

An object of the present invention is to provide a deaerator auxiliary steam pressure control device that improves the drawbacks of the above-mentioned prior art and automatically controls the pressure inside the deaerator even when there is a shortage of auxiliary steam, thereby reducing the burden on the operator. There is a particular thing.

The present invention adds a setting device to the conventional deaerator auxiliary steam pressure control device, which can arbitrarily set a target value of the deaerator internal pressure based on an increase or decrease in the amount of auxiliary steam used.
This aims to achieve the above objective.

An embodiment of the present invention will be described below with reference to FIGS. 2 to 4. Here, the same reference numerals are used for the same components as in the prior art described above.

FIG. 2 shows the required amount of auxiliary steam in the start-up process of this embodiment, which is one of the processes in which the absolute amount of auxiliary steam described above is insufficient. In this FIG.
, auxiliary steam volume for non-smoke desulfurization, auxiliary steam volume for ash processing heating, auxiliary steam volume for turbine gland, auxiliary steam volume for deaerator heating, auxiliary steam volume for turbine warming, auxiliary steam volume for S/AH heating. The amount of steam is added. On the other hand, auxiliary boiler 1
The maximum amount of auxiliary steam discharged from is indicated by a two-dot chain line 31, and after time C, the required amount (solid line 32) exceeds the discharge amount (two-dot chain line 31), and the absolute amount of auxiliary steam is clearly insufficient. do.

FIG. 3 shows the configuration of a deaerator auxiliary steam pressure control device according to the present invention, which is a setter 13 shown in FIG. 4 in addition to the conventional control device shown in FIG.
is connected to the controller 7.
The auxiliary boiler 1 and the deaerator 21 are connected to the auxiliary steam header 2.
This auxiliary steam header 2
A control valve 3 is inserted in the middle of the deaerator 21 to adjust the amount of auxiliary steam flowing from the auxiliary boiler 1 to the deaerator 21. A detector 4 is connected to the auxiliary steam header 2 on the auxiliary boiler 1 side of the control valve 3, and a detector 6 is connected to the auxiliary steam header 2 on the deaerator 21 side, respectively. , detects the value of the secondary pressure, and transmits it as a detection signal to the controllers 5 and 7, respectively. The detection signal is, for example, 0.1 V when the pressure is 0.1 Kg/cm ² g, and when the pressure is equal to the target value, it matches the reference described later. Detector 4
A target primary pressure value (reference) is set in the controller 5 connected to the controller 5, and this reference is compared with the detection signal from the detector 4, and the detection signal is determined as in the above embodiment. The value obtained by subtracting the reference from the reference bias signal is added to the reference bias signal, used as a control signal, and transmitted to the low value priority circuit 8. On the other hand, a controller 7 connected to the detector 6 is provided with a target secondary pressure value (reference) that can be arbitrarily set using a setting device 13, which will be described later. Compare the detection signals from the device 6,
For example, as described above, the value obtained by subtracting the reference from the detection signal is added to the reference bias signal to be used as a control signal, and is transmitted to the low value priority circuit 8. The reference bias signal here is the controller 5
and 7 have the same value. In the low value priority circuit 8, the controllers 5 and 7
Out of the control signals transmitted from
The signal is transmitted to converter 10 and fed back to controllers 5 and 7 via isolators 11 and 12. As described above, the automatic/manual selection unit 9 is for switching between automatic and manual pressure control, and in this embodiment, the automatic selection is performed. The control signal transmitted to the E/P converter 10 is converted into an air signal here, and when the control signal is transmitted from the controller 7, the control valve 3 is made to correspond to the value of the control signal. When the control signal is transmitted from the controller 5, the control valve 3 is driven in the closing direction in accordance with the value of the control signal. As mentioned above, the control signals are automatic/
After passing through the manual selection section 9, feedback is sent to the controllers 5 and 7 via the isolators 11 and 12, but this is because the primary pressure or secondary pressure is determined by the function of the control valve 3 described above. This is to quickly detect that the pressure is approaching the exponent value, to ensure that pressure control is performed well and that it does not go too far.

Next, FIG. 4 shows the configuration of the setting device 13 connected to the controller 7. In FIG. 4, the connection group 14 can take a specific configuration of "ON" or "OFF" corresponding to each time in FIG. 2. For example, between times A and B (event AB)
Each event has a different specific "ON/OFF" configuration, such as in the event CD, the two on the left are "ON" and all others are "OFF". We are beginning to respond. The logic judgment device 15 to which this contact group 14 is connected is constituted by wire logic or a sequence controller such as a microcomputer.
receives a specific contact input corresponding to a specific "ON/OFF" configuration, determines the different "ON→OFF" configuration specified by this contact input, and changes the contact group 16 to the specified "ON/OFF" configuration.・Set as “ON” or “OFF” in “OFF” configuration. This contact group 16
A constant voltage generator group 17 is connected to each of the constant voltage generators 17, which generate a designated voltage corresponding to the designated "ON/OFF" configuration as a setting signal, and set the reference installed in the controller 7 described above. . As a whole, the setting device 13 performs an operation of setting the reference of the controller 7 corresponding to each event shown in FIG. On the other hand, within each event, the target secondary pressure value is set constant, so as a result, the setting device 13
However, the reference of the controller 7 is set to the target value of the secondary pressure in each event. For example, in event AB, the target value of the secondary pressure is 0 kg/cm ² g, and the reference is also OV, and in event DE. The target value is 0.1Kg/cm ² g and the reference is 0.1V.

Next, the overall operation of the above embodiment will be explained.

In FIG. 2 or 3, at the stage of event AB and event BC, the deaerator 21 does not require auxiliary steam, so the target value of the secondary pressure is 0 kg/
cm ² g, and the controller 7 is set by the setting device 13.
reference is set to 0V. On the other hand, if the target value of the primary pressure is, for example, 10 kg/cm ² g, the reference of the controller 5 is 10V. Time A
Since the primary pressure and the secondary pressure are each equal to the target value, the detectors 4 and 6
The detection signals of will be 10V and 0V. Therefore, in the controllers 5 and 7, the value obtained by subtracting the reference from the detection signal is both 0V, which is added to a bias signal of, for example, 1V as a control signal, and is transmitted to the low value priority circuit 8, respectively. The low value priority circuit 8 tries to select the lower value of the control signals, but since this value is equal to 1V, it does not make any selection. Therefore, the control valve 3 does not operate immediately and remains closed, and auxiliary steam is not immediately supplied in event AB and event BC, and the secondary pressure is controlled to the target value.

Next, at time C, at the stage of event CD, the deaerator 21 starts operating and requires an amount of auxiliary steam. Much more than the auxiliary steam discharge amount. In this case, the secondary pressure target value should be changed to a value corresponding to the auxiliary steam amount, e.g.
If it is set to 0.35Kg/cm ² g, the hunting phenomenon described above will occur, so the value corresponding to the auxiliary steam amount obtained by subtracting the excess from the secondary pressure target value, for example, 0.25Kg/cm ² g, is set. As a result, the reference of the controller 7 is set to 0.25V. At time C, the secondary pressure is 0 kg/cm ² g, and therefore the detection signal of the detector 6 is 0V, so the value obtained by subtracting the reference from the detection signal is −0.25V. The controller 7 transmits 0.75V, which is obtained by adding this value to the bias signal 1V, to the low value priority circuit 8 as a control signal. Since the control signal of the controller 5 is 1V as described above, the low value priority circuit 8 selects the control signal of the controller 7 of 0.75V. The control valve 3 is driven in the opening direction by this control signal, and auxiliary steam is supplied from the auxiliary boiler 1 to the deaerator 21 until the target secondary pressure is reached. Throughout the event CD, the required amount of auxiliary steam does not exceed the maximum auxiliary steam discharge amount of the auxiliary boiler, and therefore the primary pressure is maintained at the target value, thereby preventing the hunting phenomenon as described above.

Furthermore, in event DE, the amount of auxiliary steam for turbine warming is added, so the maximum auxiliary discharge amount of the auxiliary boiler is again exceeded. A value corresponding to the amount of auxiliary steam obtained by subtracting the amount of auxiliary steam for turbine warming, for example, 0.2 Kg/cm ² g. Therefore, the reference of the controller 7 is 0.2V. At time D, the secondary pressure is 0.25Kg/cm ² g,
The detection signal of the detector 6 is 0.25V. The value obtained by subtracting the reference from the detection signal is 0.05V
Then, the controller 7 adds this 0.05V to the bias signal 1V and transmits the 1.05V to the low value priority circuit 8 as a control signal. On the other hand, the primary pressure is equal to the target value as described above, and the control signal of the controller 5 is equal to the bias signal of 1V. Since the low value priority circuit 8 selects the control signal of the controller 5 from among the control signals, the control valve 3 is driven in the closing direction, and the amount of auxiliary steam supplied to the deaerator 21 is reduced. Along with this, the secondary pressure begins to decrease and approaches the target value. In this event DE, as in event CD, the required amount of auxiliary steam does not exceed the maximum auxiliary steam discharge amount of the auxiliary boiler, and the hunting phenomenon described above can be prevented. The same applies to event EF. As mentioned above, pressure control is performed by keeping the supply amount and required amount of auxiliary steam in balance by reducing the amount of auxiliary steam for heating the deaerator. This is because it accounts for a large proportion of the total amount of steam required, and although the above-mentioned cleanup effect decreases slightly due to the decrease in secondary pressure, it can be compensated for by extending the time slightly. be. Moreover, when time F is reached, the amount of steam generated by the plant itself increases, so by utilizing this, the required amount of auxiliary steam decreases as shown by the dashed-dotted line 33 in FIG. Therefore, sufficient auxiliary steam can be supplied to the deaerator 21, and the secondary pressure can be controlled to the originally required target value.

In addition to the above embodiment, as shown in FIG. 5, the amount of auxiliary steam supplied from the auxiliary boiler 1 in addition to the deaerator 21 is detected, and this information is fed back to a calculation device such as a microcomputer. ,
The reference of the controller 7 may also be set. In the above embodiment, the deaerator 21
Although the required amount of auxiliary steam to be used for other purposes was determined in advance, there is some variation in reality. Therefore, as shown in FIG.
8 and 19, and this information is fed back to the arithmetic controller 20 to set the reference of the controller 7.

As described above, the present invention adds a setting device composed of a logic judgment device, a group of contacts, and a group of constant voltage generators to a conventional deaerator auxiliary steam pressure control device. This has an excellent effect in that the deaerator auxiliary steam pressure control when the primary pressure decreases, which was previously performed manually by the operator, can be performed automatically and satisfactorily.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional deaerator auxiliary steam pressure control device, FIG. 2 is a diagram showing the amount of auxiliary steam required at startup of a thermal power plant according to the present embodiment, and FIG. FIG. 4 is a detailed block diagram showing the setting device in FIG. 3, and FIG. 5 is a block diagram showing another embodiment. 7... Controller, 13... Setting device, 21... Deaerator.

Claims (1)

[Claims] 1. In a deaerator auxiliary steam pressure control device for thermal power generation or nuclear power generation, which is equipped with a deaerator and a controller for adjusting the internal pressure of this deaerator,
Deaerator auxiliary steam pressure control characterized in that the controller is additionally equipped with a setting device that can arbitrarily set the internal pressure of the deaerator to a target value based on an increase or decrease in the amount of auxiliary steam used. Device.