JPS5932703A - Controller for water level of low-pressure cleanup deaerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a water level control device for a deaerator in a thermal power plant, and more particularly to a low pressure cleanup deaerator water level control device during cleanup of the deaerator.

Technical background of the invention and its problems When starting up a thermal power plant, the deaerator is cleaned in order to improve the water quality of the water supply system. The system that performs this cleaning is called the cleanup system. Incidentally, a deaerator is used to remove gases contained in the water supply, and the gases in the water supply are usually separated and extracted by heating with bleed air. Therefore, the water level t in the deaerator is controlled to be kept constant, and a deaerator water level control device is used to control this.

The first section is a block diagram of the deaerator water level control device 11. This deaerator water level control device 11 uses an adder 12 to obtain the deviation so that the deaerator water level a becomes a preset deaerator normal water level ao, and a deaerator water level adjuster fu control gain 13. , an integral gain of 1.4 J and a gain of 15. It is necessary to calculate the deaerator water level deviation PII), and outputs the drive input No. 1 to the deaerator water level control valve. Depending on the opening degree of the deaerator water level control valve, the deaerator inlet condensate flow rate Q flows into the deaerator. Here, block 16 is the time constant of the deaerator water level control valve. Deaerator inlet condensate flow rate Q and low pressure cleanup flow tiQ that can flow into the deaerator.

The integral of the deviation from this becomes the deaerator water level a. That is, a
= , /'' (QI - Q2) d t. Here, B C17 is the time constant of the deaerator water level.

When there is no low pressure cleanup flow m1Q2, that is, when low pressure cleanup starts 1) IJ, the deaerator water level i
The ti control device 11 is in the following state.

If the deaerator water level a is below the normal water level 80, the deaerator water level a is the normal water level a. Then, open the deaerator water level control P to allow water to flow into the deaerator and increase the deaerator water level d.

Deaerator water level a is normal water level a. When this happens, a close command is output from the deaerator water level control device 11 to the deaerator water level control valve. However, normally when the deaerator water level 'A' is closed,
a −” aO is 1, and a >
It is aQ. Also, since water does not leak out from the deaerator, the deaerator water level a will not be low even if the deaerator t and water level adjustment wo P are closed. Therefore, one integrator 14 divides the integrator 14 into 4A until the integrator becomes saturated for the deaerator water level deviation generated from the high deaerator water level.

Deaerator water level a is normal water level a. In the above case, the deaerator water level control device 11 outputs a close command to the deaerator water level control valve, but since no water comes out of the deaerator, the deaerator water level control valve is fully closed. Even if the deaerator water level does not drop. Therefore, the deaerator water level deviation resulting from the deaerator water level height is integrated until the integrator 14 λ tg becomes saturated.

If the deaerator water level matches the normal water level, the integrator 14 will not become saturated. However, when water flows into the deaerator due to a flow rate leak from the deaerator water level control valve, the deaerator water level becomes high, so the deaerator water level deviation resulting from the high water level is reflected in the integrator 14. Integration will continue until the integrator is saturated.

As mentioned above, at the start of low-pressure cleanup, the deaerator-based system ('1I11 unit 71', 11's integration often integrates the glass deviation until the integrator becomes saturated).

Figure 2 shows the fluctuation characteristics of the deaerator water level and deaerator, A-unit condensate UiL meter, etc. at the start of low-pressure creep 7-up.

In order to make it easier to distinguish between dark blue and light, this figure shows the colors that influence this invention.
The one that ignores the hard differential jlHj work is shown.

Assume that the low-pressure clean-up valve starts to open at time l, I.1, its opening curve is the low-pressure clean-up valve:;
Once indicated by S1. When the low-pressure clean-up valve is opened, water mold L is discharged from the deaerator, so the deaerator water level a begins to drop. At aging t2, deaerator water level a
is the deaerator normal water level a. When the water level deviation changes from high to low, the deviation signal 012 switches from positive to negative. However, when the integrator 14 is saturated, the integral signal C13 is positive, so the drive signal for the deaerator water level control valve remains in the closing direction, and the deaerator water level control valve does not open. Therefore, water is only discharged to the deaerator by the low-pressure cleanup flow rate, and there is no inflow flow rate, so that the deaerator water level a continues to drop. At time t, the deviation signal C
When the absolute value of C12 and the integral signal C]3 match, the deaerator water level control valve starts to open. The condensate flow rate Q starts to be supplied to the deaerator, but since it is lower than the low pressure cleanup flow rate Q2, the deaerator water level remains lowered. At time t, the degassing iis'', the incoming condensate flow 'I'm Q
At time t, the deaerator water level a begins to rise at the point where I and the outflow low-pressure cleanup flow rate Q2 match.
, the deaerator water level 3 tries to change from low to high, and the deviation signal c12 switches from knee) to positive, but the integral signal c
1:3 is negative/completion, deaerator water level control valve drive No. 18l)
is 1 year and lp in the opening force direction, the deaerator inlet condensate flow rate Q1 continues to increase by 13 seconds, and the deaerator inlet condensate flow rate Q1 has already changed to the low-pressure clean amplifier flow ff1Q after time t4.
Since the water level is increasing beyond z, the deaerator water level becomes higher and higher. At time t6, when the absolute value of the integral signal C1:3 coincides with the η signal CI2, the deaerator water level control valve is switched from open to closed. In this case, since the deaerator inlet condensate flow rate Ql is higher than the low-pressure cleanup flow, 1ltQ2, the deaerator water level a increases. When it matches the low-pressure cleanup flow rate Q2, the deaerator water level a switches from increasing to decreasing.

As mentioned in 42 below, during low pressure cleanup, when opening the low pressure cleanup valve, the deaerator water level iti'
[Control device] The deaerator water level a and the deaerator artificial condensate flow rate Q vary according to the integrated deviation of the integrator 14 in step 1.
In other words, the maximum fluctuation range of the deaerator water level and the deaerator input [
, 1 The maximum value of the fluctuation range of condensate flow 7 is proportional to the initial setting opening degree of the low pressure cleanup valve.

Therefore, if the initial opening of the low pressure cleanup valve is set to the low pressure cleanup flow rate opening as in the past,
The deaerator water level and the amount of condensate ωr at the deaerator inlet fluctuate greatly. Also, if the condensate flow end at the deaerator inlet fluctuates significantly, the condensate bonder may become overloaded and trip.
Even if it does not trip, it will shock the condensate bonder. On the other hand, when the deaerator water level 3 decreases, the deaerator internal pressure is low and a large amount of auxiliary steam supplied to the deaerator is sucked in, so that a large amount of auxiliary steam can be used. Therefore, it is desirable that the deaerator water level and the condensate flow rate at the deaerator inlet are always stable.

OBJECTS OF THE INVENTION An object of the present invention is to provide a low-pressure clean-up degasser that can reduce fluctuations in deaerator water level caused by saturation of the integrator of the deaerator water level control device when starting deaerator clean-up. The objective is to obtain an air water level control device.

SUMMARY OF THE INVENTION The present invention provides input means for inputting a deaerator water level signal and a low pressure cleanup valve opening signal used to control the deaerator water level in a power generation ground, and a low pressure cleanup valve opening signal from the input means. an initial opening setting means for outputting a low pressure cleanup valve drive signal so that the low pressure cleanup valve is initially opened; A cleanup flow rate opening setting means (hereinafter referred to as opening setting means) that outputs a drive signal, and an initial opening setting means based on a deaerator water level signal and a low pressure clean amplifier start signal from the input means. a setting control switching means for outputting a low-pressure clean-up valve drive signal from the corner opening setting means; and an output means for outputting a low-pressure clean amplifier valve drive signal from the setting control switching means to the low-pressure clean-up valve single-stage device. It is characterized by consisting of.

Embodiment of the Invention An embodiment of the low pressure cleanup deaerator water level control device of the present invention will be described below. FIG. 3 is an overall system configuration diagram in which the low-pressure cleanup deaerator water level control device 18 of the present invention is applied to a deaerator cleanup system.

The cleanup system of the deaerator 19 is as follows. That is, water is sent from the condenser 20 to the condensate desalination device 422 by the condensate bonder 21, where various ions contained in the water are removed. Then, water is sent to the deaerator 19 by the condensate booster bong 23 via the deaerator water level signal valve 24 and the low pressure heater 25, where the gas in the water is separated and extracted. The water from the deaerator 19 is returned to the condenser 20 through the low-pressure clean-up valve 26, and the water quality is improved by repeating the cycle.

The low pressure clean ag blow valve 27 is a valve for draining water out of the cycle when the water quality is highly contaminated. Further, the signal S1 is the opening degree signal of the low pressure cleanup valve 26, and the signal S2 is the drive signal of the low pressure cleanup valve 26, and the signal S
3 is a drive signal for the low pressure cleanup blow valve 27, and signal S4 is an opening signal for the low pressure cleanup valve 27.

Next, the low pressure cleanup deaerator water level control device 1 of the present invention
An embodiment of 8 is shown in FIG. 4. 3 This embodiment is for controlling the low pressure clean-up valve 26. Therefore, the low pressure cleanup deaerator water level control device 18
The signals input to are those for the deaerator water level signal a and the low pressure cleanup valve opening signal S1.

The low pressure cleanup valve opening signal S1 is inputted to the initial opening setting means 29, the flow rate opening setting means 30, and the setting control switching means 31 via the input means 28. The initial opening degree setting means 29 receives the opening degree signal S1 of the low pressure cleanup valve 26.
The driving signal S2A of the low pressure cleanup valve 26 is outputted so that the initial opening degree setting command SIA becomes the initial opening degree setting command SIA. On the other hand, the flow rate opening degree setting means 30
The pivot signal S2B of the low-pressure clean-up valve 26 is output so that the opening signal S1 of No. 6 becomes the flow rate opening setting matching SLB.

'Also, the setting control switch 123i is connected to the initial opening setting means 2.
9 and the drive signal 82B from the flow rate opening degree setting means 30, one of them is selected and outputted to the low pressure cleanup valve 26 as the drive signal S2. This setting control switching means 31 is as shown in FIG. That is, based on the deaerator water level signal a obtained from the input means 28, the deaerator water level change rate α is calculated. The deaerator water level change rate α is the specified value α. The following conditions and low pressure cleanup valve opening S1 are initial opening SIA
The AND circuit 33 is configured based on the above conditions. The output of the AND circuit 33 is input to the timer circuit 34, and
After that, an output signal is generated. When the output of the timer circuit 33 is established, it becomes a drive signal 82B from the flow rate opening degree setting means 3o. On the other hand, the output of the timer circuit 33 is input to the NOT circuit 35, and becomes the drive signal S2A from the initial opening degree setting means 29 when the output of the NOTN path 35 is established. :36,37
) is an LND circuit, and 38 is a zero circuit.

Let us now begin the low pressure cleanup. In this case, since the low pressure clean assozo valve 2 (5) is fully closed, water does not flow out of the deaerator 19.

Further, as described above, the deaerator water level I is less than the normal water level, and the deaerator water level is 6; the 1j node valve 24 is fully closed δ. It is assumed that the integral 8N14 of the deaerator water level control device 11 integrates a positive deviation until it becomes saturated.

Assume that low pressure IJ assembly is started at time t1 as shown in FIG. Then, the deaerator water level a and the low pressure cleanup valve opening signal s1 are input to the input means 28. The deaerator water level a and the low pressure cleanup opening signal S1 are transmitted from the input means 28 to the setting control switching means 31, and since the low pressure cleanup valve 26 is fully closed σ,
The low pressure cleanup flow rate opening setting condition is not satisfied.

Therefore, the initial four-degree setting condition for the low pressure cleanup valve is established. Therefore, the low-pressure clean-up valve drive signal 82A of the initial opening degree setting means 29 is transmitted to the output means 32 by the setting control switching means 31, and this signal causes the low-pressure clean-up valve 2G to be switched to JtB Mt. Further, in this case, the low pressure clean amplifier valve drive signal 82B of the flowmeter opening degree setting means; 3] is cut off by the setting control switching means 31.

Next, FIG. 6 shows fluctuations in the deaerator water level a and the deaerator inlet condensate flow ii:Q+ when the low pressure cleanup valve 2G is set to the initial opening degree SIA. Curve a is the deaerator water level curve, Sl is the low pressure cleanup valve opening curve, C13
C12 is the integral signal of the deaerator water level control device 11, and C12 is the deaerator water level a and the reference water level a. The deviation No. 14, Ql, is the curve of the deaerator artificial condensate flow rate. These characteristics are changed by the initial opening setting of the low pressure cleanup valve. Since the initial setting opening degree of 81 is lower than the flow rate opening degree SIB, fluctuations in the deaerator water level a and the deaerator inlet condensate flow ff1Q+ are reduced.

The deaerator standard @ device 11 controls the deaerator water level control valve 24 to maintain the deaerator water level a at the normal water level a. Make it.

Therefore, after the deaerator water level change rate α becomes within the specified value α0 and the specified time T has elapsed, the low pressure cleanup amount opening setting condition of the setting control switching means 31 is satisfied. Therefore, the low-pressure clean-up valve of the opening setting means 30, the ringing signal 82B is transmitted to the output means 32 by the setting control switching means 31, and this signal drives the low-pressure clean-up valve 26. . In this case, the low pressure cleanup valve drive signal S2A of the initial opening setting means 29 is cut off by the setting control switching means 31.

Here, the deaerator water level change rate α of ANI) circuit 33 in FIG.
is the specified value α. The following conditions are met: and the opening degree 81 of the low pressure cleanup valve is equal to or greater than the initial opening degree SIA. This means that the integral value of the integrator of the deaerator water level control device 11 almost disappears. When the deaerator water level a changes from an increasing (decreasing) direction to a decreasing (increasing) direction, the deaerator water level change rate α temporarily decreases, so the timer circuit 34 determines whether the deaerator water level a is This is to confirm that it is definitely stable.

The control gain I'+c of the initial opening degree setting means 29 is set in accordance with the time constant of the low pressure cleanup valve 26, and is adjusted in advance so as to quickly set the low pressure cleanup valve 26 to the initial opening degree. □ Also, diversion opening setting means 3
The control gain 2C is adjusted to the low pressure cleanup valve time constant, and at the same time, the deaerator water level control follows fluctuations in the low pressure cleanup flow rate q flowing out from the deaerator of the deaerator water level control device 11. To ensure that fluctuations in the deaerator water level and deaerator condensate flow rate are within specified values,
Adjusted in advance.

The above embodiment is an application example of low pressure cleanup recirculation in which the deaerator outlet flow rate is recirculated to the condenser 20, and the low pressure cleanup valve 26 is controlled. Setting control of the low-pressure clean-up blow valve 27 for temporary low-pressure clean-up blow blowing to outside the system can also be performed in the same manner. In this case, the low pressure clean-ag blow valve 27
The opening signal S4 of this valve is input. The low pressure cleanup blow valve drive signal S3 is sent from the low pressure cleanup deaerator water level control device 18 to the low pressure cleanup blow valve 2.
Output to 7. Similarly to the above-mentioned low pressure clean amplifier recirculation, when starting the low pressure clean up blow, the low pressure clean up blow valve is initially set according to the present invention, so that the deaeration water level is stabilized and the deaerator water level control device 11 is controlled. When the 81 minute value of the integrator decreases, the low pressure cleanup blow valve 27 is set to the blow flow value opening degree. In this way, the deaerator water level and the deaerator inlet condensate flow rate are stabilized at the start of low-pressure cleanup blowing.

Effects of the Invention As described above, the present invention initializes low pressure cleanup at the start of low pressure cleanup, and when the integral value of the integrator of the deaerator water level control device decreases and the deaerator water level becomes stable. By setting the low-pressure clean-up valve to the clean-up opening degree, the deaerator water level can be stabilized, and the deaerator condensate flow rate can be stabilized.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the deaerator water level control device, Fig. 2 is a characteristic diagram of the deaerator water level in a conventional example, Fig. 3 is an overall configuration diagram to which the control device of the present invention is applied, and Fig. 4 is FIG. 5 is a block diagram showing an embodiment of the present invention, FIG. 5 is an explanatory diagram of a setting control switching means, and FIG. 6 is a characteristic diagram of the deaerator water level in the present invention. 11... Deaerator water level control device, 18... Low pressure cleanup deaerator water level control device, 2
6...Low pressure cleanup valve, 28...Input means,
29... Initial opening degree setting means; 30... Flow chamber opening degree setting means; 31... Setting control switching means; 32... Output means. (7317) Agent Patent Attorney Noriyuki Chika (and 1 other person) ~17 Figure 2

Claims (1)

[Claims] Deaerator water level signal and low pressure cleanup valve opening U used to control the deaerator water level in the Yuan'chi plant
an input means for inputting a signal; an initial 4JJ opening degree setting means for outputting a low pressure cleanup valve drive signal from the input means so that the low pressure cleanup valve opening is at an initial opening degree; and the manual means. a cleanup flow opening degree setting means for outputting a low pressure creel/up valve drive signal so that the low pressure cleanup valve opening degree from the low pressure cleanup valve opening degree becomes the low pressure cleanup θIL opening degree, and 1) 1) manual power means Based on the deaerator water level signal from the deaerator water level signal and the low pressure clean amplifier open 1f (No. 1), select either the initial opening degree setting means or the fluidity degree setting means L7 to generate the low pressure cleanup valve drive signal. A low pressure cleanup deaerator water level control device comprising: a setting 111J control switch for outputting a setting control switching means; and an output means for outputting a low pressure creel/up valve driving signal from the setting control switching means to a low pressure cleanup valve driving device.