JPS5981403A - Method and device for controlling water level in drain tank for moisture separator or reheater - 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] [Field of Application of the Invention] The present invention relates to a method and apparatus for controlling the water level of a drain tank of a moisture separator 1 or a reheater, and particularly relates to a method and apparatus for controlling the water level in a drain tank of a moisture separator 1 or a reheater. This invention relates to a drain tank water level divider 1 method and device suitable for preventing turbine lip caused by a rise in the drain tank level when the load of the steam generator and turbine of the X plant suddenly drops.

[Prior art]

First, problems with conventional moisture separator drain systems will be explained using FIG. 1, taking a general power plant as an example.

Drain dehumidified by steam in the moisture separator 1 is stored in a moisture separator drain tank 2. The water level in the drain tank 2 is exchanged by the water level transmitter 3, and the regular water level control valve 5 is controlled via the regular water level controller 4, and the drain is transferred to the regular drain line 6, so that the water level in the drain tank 2 is at a surprising level. The water is supplied via the control valve 5 and recovered to 1 ml/(J7. +: Control the emergency water level control valve 1o with 6' + tears 9■η1
Then, all the drain is discharged to the condenser 2 via the emergency drain line branched from the regular drain line 6]JX control i>i'i valve 10.

However, since the drain in the moisture absorber drain tank 2 is water, if the pressure of the steam system suddenly decreases when the steam generator and turbine (not shown) are under negative pressure, the drain tank 2 The drain inside the tank evaporates (self-evaporation) and causes the water level to rise. At this time, when the water level reaches the turbine mowing/lip level switch 30, the turbine trips to prevent water induction (water intrusion) into the turbine.

,',,'The sudden drop in the air generator and turbine was aimed at plant 1, 11, 11 and 11, but due to the rise in the water level in drain tank 2, As a result, the plant will be shut down, the supply will be stopped, and the plowing rate will be low.

Furthermore, since an increase in the water level in the drain tank 2 will cause a serious accident due to the turbine walk-in duct, the increase in the water level must be suppressed by 1.13 force.

In addition, as shown in FIG. 7, the drain of the heated steam train tank 52 is also drained by saturated drain. ``Ha, imitative pressure month...water level by 18 below'' 2! Do 1. This water level slippage makes it impossible to drain the drain through the drain pipe 53 and the tube 54 in the reheater, leading to deterioration of performance due to pressure pulsation and damage to the equipment due to water hammer.

[Purpose of the invention]

The present invention has been made in view of the above, and its purpose is to improve steam generation, and to rapidly increase turbine output.
An object of the present invention is to provide a method and device for controlling the water level of a drain tank of a water separator or reheater that can prevent turbine tripping due to a rise in the water level of the drain tank when the temperature is lower than rt.

[Summary of the invention]

A first feature of the invention is a moisture separator or moisture separator
ff: saturated A1 dehumidified by moisture distribution from hot air in Ps heater] Reactor runback where the pressure in the drain tank that stores condensate suddenly decreases, 'Fni#'fJ< (hereinafter P
Under operating conditions such as turbine load cut-off, the water level setting value of the drain tank is set in advance to reduce the water level caused by flushing of condensate in the drain tank when the pressure suddenly increases. We are at the point where we are beginning to curb the rise. The second feature is the standard water level setting signal that generates the standard water level setting signal to lower the current water level setting directly to the fixed value of J'L, the bow generator, the reactor runback, and the LI% pump trip. In other words, a configuration including a set value switching device that switches the normal water level setting signal to the specified value water level setting signal from the generation of the specified value water level setting signal in response to a start signal such as a turbine load cutoff.

The third feature is a valve opening signal generator that generates a valve opening signal that suddenly opens the emergency water level controller to a predetermined I degree, and a valve opening # signal that generates a valve opening signal according to the start signal to the above valve opening degree. The present invention is equipped with a valve opening signal switching device that switches the valve opening from the signal generator to @ and the valve opening.

[Embodiments of the invention]

The embodiments of the present invention shown in FIGS. 5 to 8 and the second
HQ will be explained in detail using Figures 4 to 4.

The state K (H) inside the drain tank according to the present invention will be explained using FIGS. 2 to 4.

Generally, the load from the rated switching or partial load operation of the generating plant, 1A, is lowered, i.e., PLl, 1. When the reactor run 'bumps' due to pump rotational speed control, skin ratio pump trip or turbine load is cut off, the reactor output changes as shown in FIG. After a 5-10 second delay, it descends rapidly.

Under these conditions, in the case of VE, the state change in the moisture separator drain tank 2 is as shown in FIG. 61 occurs, the pressure suddenly decreases with a delay of 5 to 10 seconds, and along with this sudden pressure decrease, the saturated drain in the drain tank 2 and the drain line 6.11 flashes and the tank 2
The internal water level is swollen, as in Gu 63, and the water level is normal (
NWL) When the dump water level reaches 64, the emergency water level 1 is reached as shown by curve 67 in the same figure (b).
, the circumferential valve 10 begins to open. However, if the opening operation of the control valve 10 is too slow with respect to the upper water level, the turbine trip water level 65 will be reached, and the plant will be shut down. Furthermore, it'! A curve 66 in FIG. 3 (1) indicates the opening of the regular water level control valve 5, and when the water level in the tank 2 rises by 64", it is assumed to be 100% open.

Therefore, in the present invention, the pressure inside the dray tank 2 is suddenly increased to ij. Under operating conditions of +'5, the water level set value 'lIII rjl of the drain tank 2 is lowered in advance. A diagram corresponding to FIG. 3 in that case is shown in FIG. Song #162 in Figure 4 (+1) is a change in the pressure inside tank 2, which is the same as in Figure 3 (Fl), but
As shown in FIG. 4 (1)), the output prp lower request signal 6
At the same time, the emergency water level control valve 10 was fully opened as shown in the song 67', and the set water level was lowered to 71 cm, so that the amount of drain held in the tank 2 was lower than normal. , the water level level 1 when the pressure suddenly decreases is shown in Figure g4 (a).
The water level does not rise above the normal water level 64 and can be prevented from reaching the turbine trip water level 65. In this case, it cannot be said that simply lowering the water level setting value in advance is effective. A curve 66' in the wedge 4 (I) is the opening degree of the regular water level control valve 5 in this case.

Figure 5 shows the moisture separator drain tank water level of the present invention! lrl
This is a system diagram showing one embodiment of the Ifll device, and the same parts as in Figure 1 are designated by the same number IPA 1, and the explanation will be omitted here. In FIG. 5, the emergency water level controller 9 includes a normal water level setting signal generator 21, an emergency water level setting signal generator 22 for the steam generator and the turbine under sudden loads lI, f, and the above-mentioned 1 sudden Load IS? The signal generator 22 converts the water level set value from the set value by the signal generator 21 in response to the plant output drop signal when the plant output drops.
A setting value switching device 23 is provided that allows users to learn the setting value according to the setting value. The valve opening signal generator 24 and the output drop No. 16 generate an emergency valve opening signal using the fT' opening information to fully open the emergency water level control valve 10 at the time of ↑. A valve opening signal switching device 25 is provided for switching to a fully open valve signal from the valve 24, and an emergency switching controller 29 is provided. Furthermore, the switching device interlock function shown in F is added.

Figure 6 is an explanatory diagram of switching and internal interlocks.

As shown in FIG. 6, the plant output drop 1m 28, e.g.
.

1□ in Fig. 5 by the power load unbalance relay 50, which is used to switch to in-house single load operation in the event of a problem with the pump trip (49) or the plant power transmission system, 1 charge.
9. The constant value switching device 23 and the valve opening signal switching device 25 are operated, but in this case, it is a means to temporarily bring the sickle to the normal operating water level for one day, and a timer 32, 33 is provided.
The timer 32 sets the time limit to 60 seconds,
When the timer 32 turns on after 60 seconds and 7"lE, quickly return the set value switching device 23 to its original state to output the normal water level set value from the normal water level setting generator 21. For example, if the timer 33 is set to 10 seconds and the timer 33 turns on after 10 seconds,
The valve opening signal switching device 25 is returned to its original state so as not to output the valve fully open signal from the valve opening signal generator 24.

Although FIG. 5 shows the water level device side 1 device of the moisture separator drain tank 2 of the continuous separator 1, the present invention is also applicable to the case of the drain tank of the moisture separator W heat device, and the same There is an effect. Figure 7 is a system diagram showing the implementation of the drain tank water level control device according to the present invention applied to a nuclear power plant having a moisture separation reheater, and is the same as Figures 1 and 5. The parts are indicated by the same ladle number. In Fig. 7, 1a is a moisture separation reheater, 2a is a drain tank, 40 is a reactor pressure vessel, 41 is a high pressure turbine, 42I is a low pressure turbine,
43 is the power generation (shallow), 44 is the reconnaissance device, (condenser of culvert 5, 1
2), 45 is a pump, 46 is 1≦) water heater (
(corresponds to the feed water heater 7 in Figure 5), 47 is the Heimenghuan pump;
48 is the pump punching surface 1.49 is the output detection, 50
is a trip detector, and the drain tank 2a includes water level transmitters 3, 8, a regular water level controller 4, and an emergency water level control valve 29.
The values of the water level control system according to the present invention, which consists of , the regular water level control valve 5, and the emergency water level control valve 10, have been obtained and are exactly the same as those shown in FIG. The operation will be explained below.

p which performs the output control of the reactor pressure vessel 40 in FIG. 7 ],
j A sudden decrease signal from the control device 48 of the IL water pump 7, 1. ) ], 11. I)L to monitor failure of pump 47 1. j A sudden output decrease signal from the pump trip detection device 50 or a sudden output decrease signal from the power load unbalance relay of the output detector 49 that monitors malfunctions in the power transmission system causes the switching device 23.25 to pass through the interlock path shown in FIG. is activated. 5~ from this output sudden decrease signal
After 10 seconds, the pressure in the drain tank 2 drops, but when the output sudden decrease signal is generated, the water level set value in the drain tank 2a is lowered to the set value by the emergency water level setting signal generator 22. Simultaneously with the above operation, the output of the emergency water level control valve 29 becomes a fully open signal given by the valve opening signal generator 24, and the emergency water level control valve 10 becomes fully open (in this case, it does not necessarily have to be fully open). , it may also be a signal that suddenly opens after a specified amount of 1 round.) After that, in order to prevent the water level of the drain tank 2a from dropping below the minimum water level, after about 10 seconds,
The valve full open signal from the valve opening signal generator 24 is released, and within 60 seconds, the set value of the water level changes from the set value from the emergency water level setting signal generator 22 to the normal water level setting (No. The setting value from the water level controller 21 is returned to normal water level control (P.
operation).

As mentioned above, the pressure suddenly decreases at a low water level.In this case, the water level change in the drain tank 2a becomes like the curve 63' in Fig. 4(a), and the drain The water level upper case 1 according to Furano/Yu is the turbine trip water level 65
will never reach. Approximately 6 minutes after the output sudden decrease signal appears
The Zolant output stabilizes at 0 seconds, but at this point the water level set value is set to: JrT1 normal water f ('L64), so the actual water level changes from low water II'L to dump water level 70 ( (see Figure 3).

When the actual water level reaches the normal water level 64, the normal water level regulator 4 enters the normal control σ11, and drain is discharged to the feed water heater 46 via the normal water level control valve 5. The same applies to the case of FIG.

As described above, according to the embodiment of the present invention, the steam generator (
reactor pressure vessel 40) and turbine output +'je-
It is possible to prevent a turbine trip due to an increase in the water level of the drain tank 2a of the moisture separation IIJ heater 1a at the time of l/rp-r. , not only change the water level setpoint, but also adjust for non-'lj';
Since the output at t9 is also kept the same, it has excellent responsiveness, and after a specified time, normal 1) and ■ operation starts at low water level, and after the plant (2) load stabilizes, it gradually returns to normal. It is possible to move to drain discharge. Therefore, control stability can be improved. Furthermore, it is also possible to reduce the size of the drain tank.

In addition, the valve opening signal generator 24 of the emergency μ switching controller 29
Alternatively, the valve opening degree signal switching device 25 may be deleted and the water level setting value may be simply switched to a low water level, and the same effect can be obtained. This is very effective in plants where the rate of output decline is gradual, and has the new effect of simplifying the process with control assistance.

Fig. 8 is a system diagram corresponding to Fig. 7 showing another embodiment of the present invention, and the same parts as Fig. 8 are indicated by the same ladle numbers. In Fig. 8, the reheater heating unit 52
Emergency water level control valve 1. The same emergency water level controller 29a as described above is used as the ON emergency water level controller. The operating principle of the emergency water level controller 29a is basically the same as that described in FIG. 5, and the output sudden decrease signal as the switching signal is also the same as in FIGS. 6 and 7.

The water level control system of the heated steam drain tank 52 has a stable drain output, but when the output is reduced, the heated steam line 51 and the tube 54,
Due to the internal pressure 151 of the drain tank 52, the flushing of the drain in the drain tank 52 causes the water level to rise and the drain to flow into the tube 54, causing mud pulsation and water hammer. Therefore, by letting the drain in the drain tank 52 come out at the front, the redundancy of these connections can be avoided, and stable control and reliability can be improved. Yes, there is no need for the drain tank 52 to have an oversized role.

In addition, in FIG. 8, 3a, 8a are water level transmitters, 4nr, 1:'ii5JT], /J(position adjustment M1.5a is a regular water level control valve, and 53 is a drain pipe.

〔Effect of the invention〕

As explained below, according to the present invention, it is possible to prevent the turbine lip caused by the water level of the drain tank when the steam generator and turbine output suddenly drops,
Moreover, there is an effect that control stability can be improved.

[Brief explanation of drawings]

Figure 1 shows the conventional water level control 11 of the moisture separator drain tank.
System diagram of the device, Figure 2 is a diagram showing the state of decrease in reactor output when the load suddenly drops, Figures 3 and 4 are the moisture separator drain in the conventional case according to the present invention, respectively. Changes in water level and pressure in the tank and the water level at that time +ij
A diagram showing the valve opening status, FIG. 5 is a system diagram showing an embodiment of the moisture separator drain tank water level control device of the present invention, FIG. 6 is an explanatory diagram of the switching device interlock, and FIG. A system diagram showing one embodiment of a nuclear power plant equipped with a moisture content control device of the present invention and a water level control device for a reheater drain tank, Fig. 8 corresponds to Fig. 7 showing another embodiment of the present invention. This is a system diagram. 1... Moisture separator, 1a... Moisture separation reheater, 2...
Moisture separator drain tank, 2a...Moisture separator reheater drain tank, 3, 3a, 8, 8a/Water level transmitter, 4.4
a... Regular water level controller', 5.5a... Regular water level control valve, 6... Regular drain line, 7, 46... Feed water heater, 9... Emergency water level controller, 10 ．． ], Oa・
...Emergency water level control valve, 11...Emergency drain line, 12.44...Condenser, 21...Normal water level setting tank number - Earthenware, 22...Emergency water level setting signal generation device, 23... Installation, 1 value switching device, 24... Emergency valve IW signal generator, 25... Valve opening signal switching device, 28 - Plan I / Output 1 (1000 signal, 29, 29a
...Emergency water level controller, 32.33...Timer,
40... Nuclear reactor pressure vessel, 41... High pressure turbine, 4
2...Low pressure turbine fee 1 person Patent attorney Nagasaki Usuba (and 1 other person) fl1 Figure 2 Condolence 3 [ii] (α) 40th 50th

Claims (1)

[Scope of Claims] 1. Steam that is led to the turbine of a power generation plant is separated and dehumidified (d). Moisture is separated and dehumidified using an IF heater. In a system consisting of a line that collects condensate to the feed water heater via a regular water level control valve in order to control the water level to a predetermined level 9111, and an emergency line that discharges condensate to the condenser via an emergency water level control valve, Under operating conditions such as a reactor runback in which the L1 nickel in the drain tank suddenly decreases or a turbine load is cut off while the recirculation bong trip is still in progress, the water level set value in the drain tank is lowered in advance to reduce Ai+ at the time of the sudden pressure decrease.
A method for increasing the water level of a moisture separator or reheater in a drain tank, characterized by suppressing a rise in water level due to flushing of drain in the drain tank. 2. The invention according to claim 1, wherein the water level of the drain tank is suppressed from rising when the pressure suddenly decreases by rapidly opening the emergency water level control valve at the same time as lowering the set water level of the drain tank. Drain tank water level control method for moisture separator or reheater. 3. The steam that is led to the turbine of the power generation plant is
The moisture content P! tt,
In order to control the water level of the drain tank that stores the dehumidified saturated condensate to a predetermined level, there is a line that collects the condensate to the feed water heater via the regular water level control valve, and a line that discharges the condensate to the water collector via the emergency water level control valve. A system consisting of an emergency line and a specified water level setting signal generator that generates a specified water level setting signal to lower the normal water level setting by a specified value, and a reactor runback and recirculation system. A start signal such as a pump trip or turbine load cutoff causes the normal water level setting signal to be changed from the specified water level setting signal generator to the specified value (((
9. A drain/reheat/reheat water level control device for a moisture separator or reheater, characterized by comprising a set value switching device that switches to a water level setting signal. 4. A regular water level control valve is used to control the water level of the drain tank to a predetermined water level, which stores the dehumidified saturated drain after separating the moisture from the steam that is led to the turbine of the power generation plant using a moisture separator or moisture separator. In a system consisting of 14 regular lines, a line that recovers the water to the feed water heater via the water heater, and a line that discharges to the condenser via the emergency water level control valve, the specified value for lowering the normal water level set value by the specified value switch. A predetermined water level setting signal generator that generates a water level setting signal; a valve opening signal generator that generates a valve opening signal that rapidly opens the emergency water level control valve to a predetermined opening; The circulating pump trip switch is a set value switching device that switches the normal water level setting signal to the specified value water level setting signal from the specified value water level setting signal generator in response to a start signal such as turbine load cutoff, and a valve opening signal that changes the valve opening degree signal to the specified value water level setting signal from the specified value water level setting signal generator. 1. A drain tank water level control device for a moisture separator or reheater, comprising: a valve opening signal switching device iji for switching to a quick-open valve opening signal from a valve opening signal generator. 5. The preset value switching device and the valve opening signal switching device have a means for self-returning after the load change is stabilized according to the plan.
#ii A drain tank water level control device for a moisture separator or reheater according to claim 4.