JPH04194502A - Generating plant and method and device for controlling water level - Google Patents

Abstract

PURPOSE:To prevent abnormal-fall of water level after flashing in a vessel for storage of saturated water or compressed water by a method wherein specific gravity of drain in the vessel is measured and if said measured value indicates occurrence of flashing of drain, delivery quantity of drain is increased or feed quantity is decreased and if said value indicates decrease of flashing, delivery quantity is decreased or feed quantity is increased. CONSTITUTION:When average specific gravity of drain in a drain pipe between detecting means 62, 63 has become lower than normal specific value in a flash-free state, the opening of a control valve 5 for normal use is opened in advance to nut the water level within a specified range, judging that flashing may take place in a drain tank 2 and drain in a drain pipe 61 may flow backward into the tank 2 and hence the water level therein may rise. When said specific gravity has become higher than normal value, the opening of the valve 5 is made smaller to keep the water level within a specified range, judging that flashing in the tank 2 may be crushed and the drain in the tank 2 may abruptly flow into the pipe 61 and hence the level in the tank 2 may fall down. Consequently, fluctuation of water level in the drain tank due to flashing can be restrained and said level can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power generation plant, and particularly to a method and apparatus for controlling the water level in a container such as a drain tank for storing saturated water or compressed water.

[Prior Art] As described in Japanese Patent Publication No. 62-48121, for example, a water level control device in a conventional power plant detects the water level in a drain tank and controls the drain discharge pipe according to the detected value. The installed control valve is controlled in advance (feedforward control) to prevent the water level in the tank from fluctuating due to flushing, etc.

[Problems to be Solved by the Invention] Upstream of a container such as a drain tank that stores saturated water and compressed water, there is, for example, a feed water heater, and the purpose of conventional water level control devices is to control the water level in the drain tank. The purpose is to avoid the water heater being submerged in water due to abnormal rise due to flash occurrence. Therefore, conventionally, no consideration has been given to the abnormal drop in the water level in the drain tank.

In recent years, in power plants, a drain-up system has been attached to the water supply condensate system, etc., and a drain pump has been connected to the drain piping for returning high-temperature water in the drain tank to the water supply condensate system. To protect the pump, this drain pump is usually designed to trip when the water level in the drain tank becomes lower than a set value, so a flash occurs in the drain tank and the water level rises abnormally. After that, when the flash void collapses and the water level drops abnormally, the drain pump will trip, but if such trips occur frequently, there is a problem in that the operation of the plant will be hindered.

An object of the present invention is to provide a water level control method and apparatus for preventing an abnormal drop in the water level in a container storing saturated water or compressed water after a flush, as well as a power generation plant.

[Means for Solving the Problems] The above purpose is to obtain the specific gravity of condensate in a container, and if the value of the specific gravity indicates a flush of condensate, control is performed to increase the amount of discharge or to reduce the amount of inflow. , this can be achieved by controlling the amount of discharge or increasing the amount of inflow when the flash is extinguished.

[When a co-flash occurs, the water level in the container rises abnormally, and when the flash disappears, the water level drops abnormally. However, prior to this water level change, the specific gravity of the drain, especially the drain at the outlet of the container, changes compared to the specific gravity of drain saturated water. That is, the specific gravity decreases due to flash generation, and increases due to drain flowing into the drain outlet section due to extinction. Therefore, when the drain specific gravity decreases, the amount discharged from the container is increased (reduced inflow amount) to suppress the water level rise, and when the drain specific gravity increases, the amount discharged from the container is decreased (increased inflow amount). 9 [Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a water level control system of a power plant according to an embodiment of the present invention. The pressurized feed water discharged from the feed water pump 10 passes through the feed water heater 1 and is sent to the nuclear reactor 29. The feedwater heater 1 is supplied with exhaust gas or extracted steam from the turbine 9, and this steam exchanges heat with the feedwater to heat the feedwater, condenses itself into drain, and is stored in the drain tank 2. Drain tank 2
and the feed water heater 1 are connected by a communication pipe 1a and a pressure equalization pipe 1b, and the drain generated in the feed water heater 1 is connected to the communication pipe 1.
a and efficiently fall into the tank 2. Even when the load on the turbine 9 changes and the pressure in the feedwater heater 1 changes, the pressure in the drain tank 2 can efficiently follow the pressure in the feedwater heater 1 by the pressure equalizing pipe 1b. .

The drain stored in the drain tank 2 passes through a pipe 61 and is discharged to the low-pressure feed water heater 3 in this embodiment, and a regular control valve 5 is provided in the middle of the pipe 61. ing.

The pressure inside the drain tank 2 is detected by a pressure transmitter 11,
This detected value is transmitted to the flash amount calculator 15 via the preceding signal calculator 19. The pressure difference between the pressure detection means 62 attached to the outlet of the drain tank 2 and the pressure detection means 63 attached to the inlet of the regular control valve 5 is measured by the common pipe differential pressure transmitter 13, and this measured value is transmitted to the regular water level controller 14 via the flush amount calculator 15. The water level in the drain tank 2 is detected by a regular water level transmitter 12, and this detected value is transmitted to a regular water level controller 14.

The regular water level controller 14 performs proportional and integral calculations from the output signal of the transmitter 12 and the output signal of the flush amount calculator 15, and controls the opening/closing of the regular water level control valve 5 based on the result of this calculation. 2. Perform water level control.

Figure 2 shows each computing unit 19.15 and controller 14 shown in Figure 1.
FIG. The output signal of the pressure transmitter 11 is input to the saturated water specific gravity calculator 19a of the preceding signal calculator 19, and the calculator 19a calculates the drain specific gravity corresponding to the saturated water pressure in the drain tank 2. This calculated value is output to the subtracter 15d of the flash amount calculator 15. Also,
The output signal of the pressure transmitter 11 is also input to the pressure loss calculator 19b, and the calculator 19b calculates the pressure loss from the outlet of the drain tank 2 to the regular control valve 5 as a value commensurate with the pressure of the drain tank 2. The calculation result is input to the flash amount calculator 150 subtracter 15a.

The differential pressure signal of the regular piping differential pressure i signal 13 includes drain flow loss. Therefore, the value corresponding to the flow loss, that is, the calculation result of the pressure loss calculation unit 19b, is subtracted from this differential pressure signal by the subtractor 15a, and the drain pipe 6
Only the hydrostatic head signal of 1 is transmitted to the divider 15'c. On the other hand, the signal generator 15b generates a signal corresponding to the level difference between the pressure detection means 62 and 63, and inputs the generated signal to the divider 15c. The divider 15c outputs [subtracter 15a output]/[signal generation 11
15b output] to obtain a signal corresponding to the specific gravity of the drain. The next subtractor 15d subtracts the drain specific gravity equivalent signal from the output signal of the saturated water specific gravity calculator 19a, and calculates the deviation from the standard specific gravity.

The signal generator 15e generates a signal corresponding to the pipe capacity of the drain pipe 61, and the multiplier 15f multiplies the signal corresponding to the pipe capacity by the deviation signal from the standard specific gravity. The water is inputted to the adder 14d of the regular water level controller 14 through the gain compensator 15g and the gain compensator 15h.

The output signal of the regular water level transmitter 12 of the drain tank 2 is manually input to the deviation calculator 14b of the regular water level controller 14. On the other hand, the signal transmitter i4a provided in the regular water level controller 14
generates a reference water level signal, the deviation calculator 14b calculates the deviation between the measured water level and the reference water level, and inputs this deviation signal to the proportional/integral calculator 14c. The signal calculated by the proportional/integral calculator 14c is then sent to the adder 14d.

It is added to the output signal of the gain compensator 15h, and the regular control valve 5 is controlled by the added value.

In this way, in this example, when calculating the drain specific gravity,
The average specific gravity of the drain in the piping is determined by measuring the differential pressure between the outlet of the drain tank 2 and the inlet of the control valve, and dividing the differential pressure by the water level difference between the measurement points.

With the above-described configuration, when the average specific gravity of the drain in the drain pipe between the detection means 62 and 63 is lower than the standard specific gravity without flash, a flash occurs in the drain tank 2 and the drain pipe It is determined that the drain in 61 will flow back into the drain tank 2 and the water level will rise, and the regular control valve 5 is opened in advance in order to keep the water level within a specified range.

When the average specific gravity of the drain is higher than the standard specific gravity, the flash in the drain tank 2 is crushed and the drain in the drain tank 2 suddenly flows into the drain pipe 61, causing the water level in the drain tank 2 to drop. Based on this judgment, the opening degree of the regular control valve 5 is preemptively reduced in order to keep the water level within the specified range.

Through the above control, in this embodiment, fluctuations in the water level in the drain tank due to flashes that occur when the load of one power generation plant continues to gradually decrease or when the load suddenly changes are suppressed, and the water level is stabilized. becomes possible. Therefore, it is possible to avoid problems such as submergence of the drain tank upstream device due to a rise in the water level and tripping of the drain tank downstream device due to a drop in the water level.

FIG. 3 is an internal configuration diagram of the arithmetic unit 15, 19 and the controller 14 according to an embodiment alternative to the embodiment shown in FIG. In this embodiment, the internal configuration of the controller 14 is different from that of the embodiment shown in FIG. 2, and the adder 14d is placed before the deviation calculator 14b. With such a configuration, the volume of the drain pipe and the volume of the tank can be handled as one unit, and the water level of the drain tank can be more easily controlled and the adjustment of the controller 14 can be made easier.

FIG. 4 is a block diagram of a water level control system of a power plant according to a second embodiment of the present invention. In the first embodiment shown in FIG. 1, pressure detection means 62 and 63 were attached to the drain piping, but in this embodiment, flush rate detection means 66 are attached to three locations on the drain piping, and the pressure detection means 66 is attached to the drain piping at three locations. The regular control valve 5 is controlled. According to this embodiment,
There is no need to inspect the pressure and calculate the specific gravity, and the specific gravity of the drain can be directly measured, which has the effect of simplifying the configuration of the control device.

FIG. 5 is a configuration diagram of a water level control system of a power plant according to a third embodiment of the present invention. In this embodiment, the common pipe differential pressure transmitter 13 (see Fig. 1) is deleted, and instead, the internal pressure of a vent pipe 67 connecting the inlet of the common tA115 valve 5 of the drain pipe and the gas phase portion of the drain tank 2 is changed. and the internal pressure of the vent pipe 68 for detecting the upper pressure of the drain tank 2, and the upstream side of the control valve 5 of the drain piping is regarded as a part of the drain tank 2.

According to this embodiment, the tank pressure transmitter 11 and the common pipe differential pressure transmitter 13 are not required, the device configuration is simplified, and the drain tank 2 can be controlled over a wide range from the full state to the empty state. It has the effect of becoming

FIG. 6 is a configuration diagram of a water level control system of a power plant according to a fourth embodiment of the present invention. In this embodiment, as compared to the first embodiment shown in FIG. The transmitter 13 is configured to detect the differential pressure between the two. Therefore, according to this embodiment, there is an effect that the accuracy of measuring the specific gravity of the drain is improved.

FIG. 7 is a configuration diagram of a water level control system of a power plant according to a fifth embodiment of the present invention. In this embodiment, an emergency system is provided which can also discharge the drain in the drain tank 2 to the condenser 4, and this system is also provided with the same water level control system as shown in FIG. In other words, the emergency control valve 6 provided in the drain pipe to the condenser 4, the emergency water level transmitter 22 attached to the drain tank 2, the emergency pipe differential pressure transmitter 23, and the emergency water level regulator 24 are provided.

FIG. 8 is a detailed configuration diagram of a computing unit and a controller corresponding to FIG. 2 of the embodiment shown in FIG. 7. Emergency water level controller 2
The set water level 4 is set higher than the set water level of the regular water level controller 14, and the emergency water level control valve 6 is fully open during normal operation. When the water level rises above the set water level of the emergency water level controller 24, the emergency control valve 6 is opened and backup control of the regular control valve 5 is performed.

According to this embodiment, even if the pressure in the drain tank 2 decreases and a flash occurs in the drain piping in a situation where the regular water level control valve 5 cannot be used, the emergency water is The opening degree of the position control valve 6 can be adjusted, and the water level of the drain tank can be controlled even more stably.

FIG. 9 is a configuration diagram of a water level control system of a power plant according to a sixth embodiment of the present invention. In this embodiment, compared to the fifth embodiment shown in FIG. A means for detecting the differential pressure in the drain pipe downstream of the stop valve 7 is provided, and a drain tank pressure transmitter 11 (first
The water level control is performed by inputting a load command signal from the load command signal generator 18 to the advance signal calculator 19 instead of the output signal of the load command signal generator 18 (see figure).

FIG. 10 is a detailed configuration diagram of a computing unit and a water level controller corresponding to FIG. 8 of the sixth embodiment. Although there is a new arithmetic unit 17 in the figure that is not shown in FIG. 8, its configuration is the same as the arithmetic unit 15 up to the middle, and the adder 15j of the arithmetic unit 15 adds the calculation results of the arithmetic unit 17. The structure is as follows.

According to this embodiment, it is possible to predict the occurrence of a flash in advance before the actual load changes.

Since the amount of flush generated on the outlet side of the check valve 7 can also be detected, even more stable water level control is possible.

FIG. 11 is a configuration diagram of a water level control system of a power plant according to a seventh embodiment of the present invention. Compared to the sixth embodiment shown in FIG.
and. FIG. 12 is a detailed configuration diagram of each computing unit and water level controller of the seventh embodiment. Except that a system for controlling the recirculation flow rate control valve 33 based on a value obtained by proportional and integral calculation of the deviation between the detection signal of the flow rate transmitter 31 and the signal from the reference flow rate transmitter 32a is added to the sixth embodiment. This is basically the same as the embodiment shown in FIG.

According to this embodiment, since the water level stabilization control can be performed in advance by predicting the occurrence of a double flash when the actual load changes, tripping of the drain pump 8 due to an excessive drop in the water level can be avoided.

FIG. 13 is a configuration diagram of a water level control system of a power plant according to an eighth embodiment of the present invention. In this embodiment, the water level of a deaerator water storage tank of a power generation plant is controlled. The water supply in the deaerator water storage tank 41 passes through a precipitation pipe and is pumped to the next stage by a water supply pump 10. In this embodiment, the outlet pressure of this tank 41 and the water supply tank 1
The differential pressure between the inlet pressure and the deaerator downcomer pressure is transmitted to the deaerator downcomer differential pressure transmitter 53. Using this pressure difference, the deaerator water level control valve 43 is controlled in the same manner as the water level control described above to control the supply amount of the deaerator deaeration chamber 42/\ (control is performed when flash scum occurs, that is, drain The valve closes when the specific gravity decreases, and opens when the flash disappears, that is, when the drain specific gravity increases by 1. Since the control valve on the supply side is controlled i, it is the opposite of the previous embodiment.) 5. In addition, 51 is a deaerator pressure transmitter, 521 is a deaerator water level transmitter, 54 is a deaerator water level controller, 55 is a deaerator downcomer flash amount calculator, 59 is a flash quantum m++ calculator, 41a is a communication pipe between the deaeration chamber 42 and the tank 41.

According to this embodiment, even if a flushing force occurs in the deaerator downpipe from the tank 41 to the water supply pump,
Since the control valve 43 is controlled in advance of the water positions 4F and 4L in the tank, a stable control force of 1 is possible for the water level.

Note that the present invention is not limited to the embodiments described above, and may be applied to other tanks, such as a moisture separator provided between a high pressure turbine and a low pressure turbine, a moisture separator reheater drain tank, and the like. , a container for storing drain in the lower part (this container is also called a drain tank). ) can also be applied to feed water heating meters that are integrally equipped.

[Effects of the Invention] According to the present invention, the water level in the container changes due to the occurrence and disappearance of a flash, and the water supply to the container is reduced due to a change in the specific gravity of the drain in the pipe connected to the container. Since the control valve or the control valve for discharging from the container is controlled in advance, the water level in the container can be stabilized. Therefore, devices upstream of the container are prevented from being submerged in water due to an abnormal rise in the water level inside the container, and devices downstream of the container are prevented from tripping due to an abnormal drop in the water level inside the container.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a water level control system of a power generation plant according to a first embodiment of the present invention, FIG. 2 is a detailed configuration diagram of an arithmetic unit and a water level controller of the first embodiment, and FIG. FIG. 4 is a diagram showing a configuration of a water level control system of a power plant according to a second embodiment of the present invention, and FIG. 5 is a diagram showing a modification of the embodiment shown in FIG. Configuration diagram of water level control system,
FIG. 6 is a block diagram of a water level control system in a power plant according to a fourth embodiment of the present invention, FIG. 7 is a block diagram of a water level control system in a power plant according to a fifth embodiment of the present invention, and FIG. FIG. 9 is a detailed configuration diagram of the arithmetic unit and water level controller of the fifth embodiment, FIG. 9 is a configuration diagram of the main control system of the power plant according to the sixth embodiment of the present invention, and FIG. FIG. 11 is a detailed configuration diagram of the computing unit and water level controller; FIG. 11 is a diagram of the water level control system of the power plant according to the seventh embodiment of the present invention; FIG. 12 is a detailed diagram of the computing unit and water level controller of the seventh embodiment. Detailed configuration diagram: FIG. 13 is a configuration diagram of a water level control system of a power plant according to an eighth embodiment of the present invention, and FIG. 14 is a detailed configuration diagram of a water level control system of arithmetic unit 2 of the eighth embodiment. 1... Feed water heater, 1a... Communication pipe, 1b... Pressure equalization pipe, 2... Drain tank, 3... Low pressure feed water heater,
4... Condenser, 5... Normal control valve, 6... Emergency control valve, 7... Check valve, 8... Drain pump, 9...
Turbine, 10... Water supply pump, 1.1... Drain tank pressure transmitter, 12... Regular water level transmitter, 13...
- Common use pipe differential pressure transmitter, 13a - Control valve inlet pipe differential pressure transmitter, 14... Common use water level controller, 14a... Signal generator, 14b... Deviation calculator, 14c... P+I calculator, 14d...Adder, 15...Flash amount calculator,
15a... Subtractor, 15b... Signal generator, 15c
...Divider, 15d...Subtractor, 15e...Signal generator, 15f...Multiplier, 15g...-Next lag unit, 1
5h...Gain compensator, 16...Check valve inlet side pipe differential pressure transmitter, 17...Check valve outlet side flush amount calculator, 18...Load command signal transmitter, 19. ...Advance signal calculator, 19a...Saturated water specific gravity calculator, 19b...
・Pressure loss calculator, 22・・Emergency water level transmitter, 23・
...Emergency piping differential pressure transmitter, 24...Emergency water level controller, 25...Emergency piping flush calculator, 29...
- Steam generator, 31... Flow rate transmitter, 32... Flow rate controller, 33... Recirculation flow rate control valve, 41... Deaerator water storage tank, 41a... Communication pipe, 42... ... Deaerator degassing chamber, 43... Deaerator water level control valve, 51... Deaerator pressure transmitter, 52... Deaerator water level transmitter, 53...
- Deaerator downcomer pipe differential pressure transmitter, 54... Deaerator water level control valve, 55... Deaerator downcomer pipe flush amount calculator, 59
...Flash amount prediction calculator, 61...Drain piping, 62a, 62b, 63a, 63b. 64a, 64b...pressure detection degree, 65...pump suction side pressure detection dust, 66...flush rate transmitter,
67... Drain piping vent pipe, 68... Vent pipe,
68a... Orifice.

Claims (1)

[Claims] 1. A pipe for introducing at least one of exhaust gas or extracted air from a high-pressure turbine into a low-pressure turbine, a container installed in the middle of the pipe for storing the drain of a moisture separator, and a container for storing the drain of the moisture separator. In a power generation plant equipped with a drain pipe for discharging water and a control valve provided in the middle of the drain pipe to adjust the flow rate of the drain flowing through the drain pipe, the specific gravity of the drain in the drain pipe is determined and the specific gravity of the drain is determined as the specific gravity of the drain saturated water. A power generation plant characterized by comprising a control device that controls the control valve in a valve closing direction when the increase in power increases. 2. A pipe for introducing at least one of the exhaust gas or extracted air from the high-pressure turbine into the low-pressure turbine, a container provided in the middle of the pipe for storing the drain from a moisture separator, and a drain pipe for discharging the drain from the container; In a power generation plant equipped with a control valve provided in the middle of the drain pipe to adjust the flow rate of drain flowing through the drain pipe, the specific gravity of the drain in the drain pipe is determined, and when the specific gravity of the drain increases than the specific gravity of drain saturated water, the adjustment is performed. A power generation plant comprising: a control device that controls a valve in a valve-closing direction, and controls the control valve in an opening direction when the drain specific gravity decreases from a drain saturated water specific gravity. 3. A container for storing the drain of the heated steam of the feed water heater that heats the water supplied to the steam generator that supplies steam to the steam turbine, a drain pipe for discharging the drain from the container, and a container installed in the middle of the drain pipe. and a control valve that adjusts the flow rate of drain flowing through the drain pipe,
A power generation plant characterized by comprising a control device that determines the specific gravity of the drain in the drain pipe and controls the control valve in the valve closing direction when the specific gravity of the drain increases from the specific gravity of the drain when no flash occurs. 4. A container for storing the drain of the heated steam of the feed water heater that heats the water supplied to the steam generator that supplies steam to the steam turbine, a drain pipe for discharging the drain from the container, and a container installed in the middle of the drain pipe. and a control valve that adjusts the flow rate of drain flowing through the drain pipe,
The specific gravity of the drain in the drain pipe is determined, and when the specific gravity of the drain increases from the specific gravity of the drain when no flash occurs, the control valve is controlled in the valve closing direction, and the specific gravity of the drain decreases from the specific gravity of the drain when no flash occurs. A power generation plant comprising: a control device that controls the control valve in a valve-opening direction when the control valve is opened. 5. In a power generation plant comprising a deaerator, a container for storing drain from the deaerator, a drain pipe for discharging the drain from the container, and a control valve for adjusting the fluid flow rate to the deaerator. A power generation plant comprising: a control device that determines the specific gravity of drain in the drain pipe and controls the control valve in the opening direction when the specific gravity of the drain increases from the specific gravity of the drain when no flash occurs. 6. In a power generation plant comprising a deaerator, a container for storing drain from the deaerator, a drain pipe for discharging the drain from the container, and a control valve for adjusting the fluid flow rate to the deaerator. , the specific gravity of the drain in the drain piping is determined, and when the specific gravity of the drain is greater than the specific gravity of the drain when no flash occurs, the control valve is controlled in the opening direction, and the specific gravity of the drain is greater than the specific gravity of the drain when no flash occurs. A power generation plant characterized by comprising a control device that controls the control valve in a valve closing direction when the amount decreases. 7. The power generation plant according to any one of claims 1 to 6 includes means for detecting the water level in the container and controlling the control valve so as to keep the water level within a specified range, and the control device precedes the means. A power generation plant characterized in that a control valve is controlled by 8. A water level control method in which the water level of a container for storing high-temperature, high-pressure steam drain flowing in a power plant system is adjusted within a specified range by controlling the amount of discharge from the container or the amount of inflow into the container, A water level control method, characterized in that the drain specific gravity at the outlet of the container is determined, and the discharge amount or inflow amount is controlled according to the value of the specific gravity. 9. A water level control method in which the water level of a container for storing high-temperature, high-pressure steam drain flowing in a power plant system is adjusted within a specified range by controlling the amount of discharge from the container or the amount of inflow into the container, The specific gravity of the condensate in the container is determined, and if the value of the specific gravity indicates that the condensate is flushing, control is performed to increase the discharge amount or to reduce the inflow amount, and if the value indicates that the flush has disappeared, the discharge amount is A water level control method characterized by controlling to reduce or increase the amount of inflow. 10. A water level control method according to claim 8 or 9, characterized in that control based on the drain specific gravity is performed in preference to control of the discharge amount or inflow amount based on a detected value of the water level in the container. . 11. A water level control device that adjusts the water level of a container that stores drain of high-temperature, high-pressure steam flowing in a power plant system to a specified range by controlling the amount of discharge from the container or the amount of inflow into the container, A water level control device comprising: means for determining the drain specific gravity at the outlet of the container; and means for controlling the discharge amount or inflow amount according to the value of the specific gravity. 12. A water level control device that adjusts the water level of a container that stores drain of high-temperature, high-pressure steam flowing in a power plant system to a specified range by controlling the amount of discharge from the container or the amount of inflow into the container, means for determining the specific gravity of the condensate in the container; means for controlling the discharge amount to be increased or the inflow amount to be reduced when the value of the specific gravity indicates a condensate flush; A water level control device comprising: means for controlling the discharge amount or increasing the inflow amount. 13. The water level control device according to claim 11 or 12, comprising means for detecting the water level in the container and controlling the discharge amount or inflow amount based on the detected water level.