JPH0593642A - Apparatus and method for detecting liquid level - Google Patents

Abstract

PURPOSE:To detect a liquid level highly accurately without adverse effects on a meter even if a reference plane device is not provided. CONSTITUTION:An upper small-diameter pipe 21 is provided to a detecting original valve 20 at the upper part of a feed water heater 16. The upper small- diameter pipe 21 is connected to a differential pressure detector 6 through an upper detecting pipe 22, a diaphragm 7 and a capillary tube 8. A lower small-diameter pipe 23 is provided down to a detecting original valve 20 at the lower part of the feed water heater 16. The lower small-diameter pipe 23 is connected to the differential pressure detector 6 through a lower detecting pipe 24, a diaphragm 9 and a capillary tube 10. The diameter of the upper detecting pipe 22 set so that the diameter is smaller than the diameter of the upper small-diameter detecting pipe 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detecting device and method for detecting the liquid level of various tanks in a power plant or the like.

[0002]

2. Description of the Related Art As a conventional device for detecting the liquid level in a tank or the like, there is, for example, the one described in JP-A-59-104514. This device, as shown in FIG.
Liquid in the reactor pressure vessel 1 and a reference level 3 connected to the gas phase of the reactor pressure vessel 1 via an upper detection pipe 2, a reference head 4 connected to the reference level 3 Differential pressure detector 6 for detecting the differential pressure between the lower detection pipe 5 communicating with the phase portion
And have both. The reference water head pipe 4 is connected to the differential pressure detector 6 via the diaphragm 7 and the capillary tube 8, and the lower detection pipe 5 is connected to the differential pressure detector 6 via the diaphragm 9 and the capillary tube 10. A liquid (silicon) for pressure transmission is enclosed in the capillary tubes 8 and 10, the pressure from the reference head 4 and the lower detection pipe 5 is transmitted to the diaphragms 7 and 9, and the capillary tubes 8 and 10 are It is configured to be transmitted to the differential pressure detector 6 via the.

Since the enclosed liquid (silicon) in the capillary tubes 8 and 10 has a large viscosity, the viscous resistance with the inner peripheral surfaces of the capillary tubes 8 and 10 becomes extremely high, and pressure fluctuations with high frequency can be easily attenuated. It is possible to improve the detection accuracy. Further, since the insides of the capillary tubes 8 and 10 are isolated from the reference head pipe 4 and the lower detection pipe 5 by the diaphragms 7 and 9, foreign matters (rust etc.) from the inside of the pressure vessel 1 are caught in the capillary tubes 8 and 1.
There is no mixing in 0, and the adverse effect on the differential pressure detector 6 due to mixing of foreign matter is avoided.

Further, the liquid level detection device having the above-mentioned structure is applied not only to the water level detection in the reactor pressure vessel but also to the water level detection of turbine equipment (heater water level, moisture separator drain tank, etc.). ing.

[0005]

However, in the above-mentioned conventional liquid level detecting device, when the pressure in the pressure vessel is lowered, the water in the reference surface device flushes (the water in the reference surface device is pulled into the pressure container). As a result, the water level in the reference level falls, causing an error in water level detection. Then, when the pressure in the pressure vessel further decreases, the water in the reference water head pipe also evaporates and the inside of the reference water head pipe becomes empty, and the heat is transferred from the upper detection pipe to the reference water head pipe to fill the inside of the capillary tube. The liquid may evaporate.

If the reference water head tube is emptied and the ambient temperature exceeds 250 ° C., hydrogen accumulates in the steam-side diaphragm, causing a problem that the water level cannot be detected.

Turbine equipment may be operated under vacuum conditions. In this case, the water in the reference plane is drawn toward the equipment, and the same phenomenon as described above occurs. There is an error in water level detection.

By the way, in order to prevent the measurement error due to the above-mentioned water head difference, a structure in which water does not accumulate in the upper detection pipe, that is, a structure without a reference level is sufficient.
If no reference plane is provided, high-temperature steam may flow from the process side (reactor pressure vessel or turbine equipment) and adversely affect instruments (diaphragm, differential pressure detector, etc.).

An object of the present invention is to provide a liquid level detecting device and method which can detect the liquid level with high accuracy without adversely affecting the instrument even without the reference surface level device.

[0010]

In order to achieve the above object, the present invention provides a gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside, and the inside of the container. A liquid phase pressure transmission pipe for transmitting the pressure of the liquid phase portion to the outside, and both the transmission pipes are connected, and liquid level calculation means for calculating the liquid level in the container from the difference between the gas phase pressure and the liquid phase pressure, In the liquid level detecting device including, a heat radiating means for radiating the temperature of the gas phase in the gas phase pressure transmitting pipe is provided in the middle of the gas phase pressure transmitting pipe, and the heat radiating means is connected to the container. It is placed near.

Further, the present invention is a gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside,
Liquid phase pressure transmission pipe for transmitting the pressure of the liquid phase portion in the container to the outside, and the both transmission pipes are connected, a liquid for calculating the liquid level in the container from the difference between the gas phase pressure and the liquid phase pressure In the liquid level detecting device including the position calculating means, the gas-phase pressure transmission pipe is thinned from the middle, and the thinned portion is provided near the connecting portion with the container.

Further, the present invention is a gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside,
Liquid phase pressure transmission pipe for transmitting the pressure of the liquid phase portion in the container to the outside, and the both transmission pipes are connected, a liquid for calculating the liquid level in the container from the difference between the gas phase pressure and the liquid phase pressure In a liquid level detecting device including a position calculating means, a heat radiation fin is provided on an outer peripheral surface of the gas phase pressure transmission pipe, and the heat radiation fin is arranged near a connection portion with the container.

Further, according to the present invention, a gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside,
Liquid phase pressure transmission pipe for transmitting the pressure of the liquid phase portion in the container to the outside, and the both transmission pipes are connected, a liquid for calculating the liquid level in the container from the difference between the gas phase pressure and the liquid phase pressure In the liquid level detecting device including the position calculating means, an orifice is provided in the middle of the gas-phase pressure transmission pipe, and the orifice is arranged near the connecting portion with the container.

Further, according to the present invention, a gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside,
Liquid phase pressure transmission pipe for transmitting the pressure of the liquid phase portion in the container to the outside, and the both transmission pipes are connected, a liquid for calculating the liquid level in the container from the difference between the gas phase pressure and the liquid phase pressure In the liquid level detection device including the position calculation means, the gas-phase pressure transmission pipe is thinned from the middle, and a radiation fin is provided on the outer peripheral surface of the thinned pipe, and the thinned portion and the radiation fin are provided in the container. It is placed near the connection with.

Further, the present invention is a gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside,
Liquid phase pressure transmission pipe for transmitting the pressure of the liquid phase portion in the container to the outside, and the both transmission pipes are connected, a liquid for calculating the liquid level in the container from the difference between the gas phase pressure and the liquid phase pressure In the liquid level detection device including the position calculation means, the gas-phase pressure transmission pipe is thinned from the middle, and an orifice is provided in the thinned pipe, and the thinned portion and the orifice are connected to the container. It is located near the department.

Further, according to the present invention, the pressure of the vapor phase portion and the pressure of the liquid phase portion in the container in which the liquid is stored are respectively taken in through the pressure transmission pipes, and the pressure difference between the vapor phase portion and the liquid phase portion is calculated. In the liquid level detecting method for detecting the liquid level in the container, when the pressure of the gas phase portion is taken in, the temperature of the gas phase is radiated on the upstream side of the pressure transmission pipe.

[0017]

According to each of the above structures, the temperature of the vapor phase (steam) in the vapor phase pressure transmission pipe is lowered, so that the temperature can be prevented from adversely affecting the liquid level calculating means. In particular,
By thinning the gas-phase pressure transmission pipe from the middle, the flow of steam is suppressed, the steam radiates heat sufficiently, and the temperature is completely lowered before it acts on the liquid level calculation means.
In addition, since steam can sufficiently dissipate heat by providing a radiation fin or an orifice, the steam acts on the liquid level calculation means after the temperature is completely lowered, as in the case of the upper air.

Further, since the reference level is not provided,
Even if the pressure in the container drops, no measurement error occurs, and the liquid level in the container can be detected with high accuracy.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a main system diagram for measuring the feedwater heater body drain water level in a nuclear power plant. In the figure, the steam generated in the pressure vessel 11 is the main steam line 1
After driving the turbine 13 through 2 and flowing into the condenser 14, it is condensed in the condenser 14. The condensed water condensed in the condenser 14 is pressurized by the condensate pump 15, heated in the feed water heater 16, and then returns to the pressure vessel 11.

Here, the feed water heater 16 is constructed so that the feed water to the nuclear reactor is heated by the extraction line 17 from the turbine 13. In order to ensure sufficient performance of the feed water heater 16, the body drain water level of the feed water heater 16 is maintained at a prescribed water level by a water level control device.

Feed Water Heater 16 In order to detect the body drain water level, a differential pressure detector 6 is provided above and below the feed water heater 16.
The pipe for pressure transmission connected to is attached.
The configuration for detecting the water level of the drainage heater 16 body drain will be described below.

FIG. 2 is a block diagram of a water level detecting device for measuring the water level of the body water drain of the feed water heater 1 in the power plant. Detection seats are provided on the upper and lower portions of the feed water heater 16. Piping size 20 from the upper detection seat to the detection source valve 20
It is composed of an upper small-diameter pipe 21 of A or larger. It is necessary to increase the diameter of the upper small-diameter pipe 21 to 20 A or more in order to prevent stress concentration on the small-diameter pipe 21 that fits with the detection seat and from the result of considering a failure case. In addition, it is necessary to further increase the diameter in a place where heat transfer and vibration are large. The reason for providing the detection source valve 20 is to partition the process side and the instrumentation side. With this detection source valve 20, even if an accident occurs on the process side, the influence on the instrumentation side can be prevented.

The detection source valve 20 has an upper detection pipe 22.
The upper detection pipe 22 is connected to the differential pressure detector 6 via the diaphragm 7 and the capillary tube 8. A liquid (silicon) for pressure transmission is enclosed in the capillary tube 8 and the pressure (atmospheric pressure) in the upper detection pipe 22 can be transmitted to the differential pressure detector 11.

By the way, since a gas phase (steam) exists in the upper detection pipe 22, it is considered that the differential pressure detector 6 after the diaphragm 7 is thermally affected. Therefore, in order to suppress this heat effect, the upper detection pipe 22 has a pipe configuration (for example, a pipe size of 10 A) that is thinner than the small diameter pipe 21 from the upper detection seat to the detection source valve 20, and the feed water heater 16
The flow of steam that flows in is further suppressed, and the steam temperature is radiated to facilitate the condensation of steam.

A lower small-diameter pipe 23 extends from the lower detection seat of the feed water heater 16 to the detection source valve 20.
Further, a lower detection pipe 24 is connected to the detection source valve 20,
The lower detection pipe 24 is connected to the differential pressure detector 6 via the diaphragm 9 and the capillary tube 10. A liquid (silicon) for pressure transmission is sealed in the capillary tube 10. As a result, the water heater 1
The pressure (water pressure) of the liquid phase part in 6 is the lower small diameter pipe 2
3, the lower detection pipe 24, the diaphragm 9, and the capillary tube 10 are transmitted in this order and can be transmitted to the differential pressure detector 6. The differential pressure detector 11 measures the water level based on the pressure difference between the upper and lower parts.

The lower detection pipe 24 is always in the liquid phase, and the pipe gradient from the detection source valve 20 to the diaphragm 8 side is generally downward.
Therefore, it is unlikely that heat conduction will adversely affect the instrument. Therefore, it is not necessary to give a heat dissipation effect, and it is not necessary to consider the aperture.

FIG. 3 is a graph of the temperature gradient when the upper detection pipe 22 is thinned as shown in FIG. From this graph, there is no temperature change in the upper small-diameter pipe 20 because it rises, but heat is gradually dissipated from the detection source valve 20 onward, and a sudden temperature change appears in the upper detection pipe 22. It can be seen that there is an effect of suppressing the thermal influence on the 7 and later.

FIG. 4 shows another embodiment of the present invention.
Also in this embodiment, the diameter of the upper detection pipe 22 is smaller than that of the upper small-diameter pipe 21 as in the above-described embodiments. A feature of this embodiment is that the heat radiation fins 40 are provided on the outer peripheral surface of the upper detection pipe 22 having a small diameter.
By providing such a radiation fin 40, the vapor temperature in the upper detection pipe 22 can be effectively lowered, and the vapor condensation effect can be promoted. In addition,
When the heat dissipation effect can be expected only with the heat dissipation fins 40,
The upper detection pipe 22 after the detection source valve 20 does not have to be thin.

Further, by providing the radiation fin 40, the condensation speed after the detection source valve 20 is remarkably increased, and condensed water may block the inside of the upper detection pipe 22. In order to prevent this, the radiation fin 40 is provided near the detection source valve 20.

5 to 7 show the detailed structure of the radiation fin 40. Radiating fin 40 shown in FIGS. 5 and 6
Are formed in a ring shape and are provided along the axial direction of the upper detection pipe 22. Also, the radiation fin 4 shown in FIG.
A plurality of 0A are provided along the circumferential direction of the upper detection pipe 22 having a flat plate shape.

FIG. 8 shows still another embodiment of the present invention. Also in this embodiment, the upper detection pipe 22 has a smaller diameter than the upper small-diameter pipe 21 as in the above-described two embodiments. The feature of this embodiment is that the orifice 80 is provided in the middle of the upper detection pipe 22. By providing the orifice 80 in this way, the flow of the process fluid (steam) can be restricted and the heat radiation area can be further increased as compared with the piping configuration of FIG. 2 in which the diameter of the piping is simply reduced, thereby further improving the condensation rate. It becomes possible. If the heat dissipation effect can be expected only with the orifice 80, the upper detection pipe 22 after the detection source valve 20 does not have to be thin.

Further, when the orifice 80 is provided, the condensation speed after the detection source valve 20 is remarkably increased, and condensed water may block the inside of the upper detection pipe 22. In order to prevent this, the orifice 80 is provided near the detection source valve 20.

9 and 10 show an example of the orifice 80. The orifice 80 is a special orifice provided with four holes 81 in the axial direction in consideration of blockage due to condensed water. By providing this special orifice 80, a measure for blocking is taken.

[0034]

As described above, according to the present invention,
It has the following effects.

(1) By removing the reference plane from the gas-phase pressure transmission pipe, flushing does not occur even when the pressure in the container becomes low, and the error in liquid level detection can be reduced. In addition, since there is no reference plane, water filling the reference plane is unnecessary.

(2) Since the gas-phase pressure transmission pipe is provided with a heat radiation effect, it is possible to prevent deterioration of the instrument due to thermal influence.

(3) A diaphragm type differential pressure gauge can be used by providing a heat dissipation facility in addition to a small diameter pipe, which leads to improvement in measurement accuracy and reliability.

[Brief description of drawings]

FIG. 1 is a main system diagram around a feedwater heater in a nuclear power plant.

FIG. 2 is an overall configuration diagram of a liquid level detection device according to an embodiment of the present invention.

FIG. 3 is a temperature gradient graph of an upper detection pipe according to an embodiment.

FIG. 4 is an overall configuration diagram of a liquid level detection device according to another embodiment of the present invention.

FIG. 5 is a detailed external view of a radiation fin according to another embodiment.

6 is a detailed vertical cross-sectional view of the heat dissipation fin of FIG.

FIG. 7 is a detailed external view showing another example of a radiation fin.

FIG. 8 is an overall configuration diagram of a liquid level detection device according to still another embodiment of the present invention.

FIG. 9 is a sectional view of a special orifice according to still another embodiment.

FIG. 10 is a side view of the special orifice of FIG.

FIG. 11 is an overall configuration diagram of a conventional liquid level detection device.

[Explanation of symbols]

 11 Pressure Vessel 12 Main Steam Line 13 Turbine 14 Condenser 15 Condensate Pump 16 Water Heater 17 Extraction Line 20 Source Valve 21 Upper Small Diameter Pipe 22 Upper Detection Pipe 23 Lower Small Diameter Pipe 24 Lower Detection Pipe 40, 40A Heat Radiation Fin 80 orifice

Claims (11)

[Claims] 1. A gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside, and a liquid-phase pressure transmission pipe for transmitting the pressure of a liquid-phase portion in the container to the outside. And a liquid level calculating device that is connected to the both transmission pipes and that calculates a liquid level in the container from a difference between a gas phase pressure and a liquid phase pressure. A heat radiating means for radiating the temperature of the gas phase inside is provided in the middle of the gas phase pressure transmission pipe,
A liquid level detecting device, characterized in that the heat radiating means is arranged near a connecting portion with the container. 2. A gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside, and a liquid-phase pressure transmission pipe for transmitting the pressure of a liquid-phase portion in the container to the outside. And a liquid level calculating device that is connected to the both transmission pipes and that calculates a liquid level in the container from a difference between a gas phase pressure and a liquid phase pressure. A liquid level detecting device, characterized in that the liquid is thinned from the middle and the thinned portion is provided near a connection portion with the container. 3. A gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside, and a liquid-phase pressure transmission pipe for transmitting the pressure of a liquid-phase portion in the container to the outside. And a liquid level calculating device that is connected to the both transmission pipes and that calculates a liquid level in the container from a difference between a gas phase pressure and a liquid phase pressure. A liquid level detecting device, characterized in that a heat radiation fin is provided on an outer peripheral surface of the container, and the heat radiation fin is arranged near a connecting portion with the container. 4. A gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside, and a liquid-phase pressure transmission pipe for transmitting the pressure of a liquid-phase portion in the container to the outside. And a liquid level calculating device that is connected to the both transmission pipes and that calculates a liquid level in the container from a difference between a gas phase pressure and a liquid phase pressure. 2. A liquid level detecting device, characterized in that an orifice is provided in the middle of, and the orifice is arranged near a connecting portion with the container. 5. A gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside, and a liquid-phase pressure transmission pipe for transmitting the pressure of a liquid-phase portion in the container to the outside. And a liquid level calculating device that is connected to the both transmission pipes and that calculates a liquid level in the container from a difference between a gas phase pressure and a liquid phase pressure. A liquid level detecting device, characterized in that the heat dissipation fins are provided on the outer peripheral surface of the thinned pipe, and the heat dissipation fins and the heat dissipation fins are arranged in the vicinity of a connecting portion with the container. 6. A gas-phase pressure transmission pipe for transmitting the pressure of a gas-phase portion in a container containing a liquid to the outside, and a liquid-phase pressure transmission pipe for transmitting the pressure of a liquid-phase portion in the container to the outside. And a liquid level calculating device that is connected to the both transmission pipes and that calculates a liquid level in the container from a difference between a gas phase pressure and a liquid phase pressure. A liquid level detecting device, characterized in that the nozzle is thinned from the middle, and an orifice is provided in the middle of the thinned pipe, and the thinned portion and the orifice are arranged near a connecting portion with the container. 7. The liquid level detection device according to claim 1, wherein a diaphragm is provided in the middle of the gas phase pressure transmission pipe and the liquid phase pressure transmission pipe. Position detection device. 8. The liquid level detection device according to claim 3, wherein the radiation fins are ring-shaped and are provided in plural along the axial direction of the gas-phase pressure transmission pipe. Liquid level detector. 9. The liquid level detection device according to claim 3, wherein the heat radiation fins are flat and are provided in plural along the circumferential direction of the gas phase pressure transmission pipe. Liquid level detector. 10. The liquid level detecting device according to claim 4, wherein the orifice has a plurality of holes along the axial direction. 11. The pressure of the gas phase portion and the pressure of the liquid phase portion in the container in which the liquid is stored are respectively taken in through the pressure transmission pipes, and the pressure difference between the gas phase portion and the liquid phase portion causes the inside of the container A liquid level detecting method for detecting a liquid level, characterized in that, when the pressure of the gas phase portion is taken in, the temperature of the gas phase is radiated on the upstream side of the pressure transmission pipe.