JP2002276902A - Control device for dryness or wetness of two-phase fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for dryness or wetness of two-phase fluid to enable the execution of control through measurement of dryness or wetness of fluid in the whole of piping containing layered fluid present in a mixed state is fluid piping. SOLUTION: A flow velocity sensor 10, a pressure sensor 9, a Pitot tube, and an ultraviolet transmitter receive 2 are mounted, in the order, in vapor piping 3 through which vapor 5 and drain 6 flow down. A dryness or wetness adjusting means 4 is mounted in the vapor piping 3. By detecting the dynamic pressure of the system 5 to be measured in the Pitot tube 1, dryness X1 of the vapor 5 is detected. Meanwhile, the liquid level of drain 6 is measured by the ultrasonic transmitter receiver 2, and from weight conversion, a weight of the drain 6 is determined. Further, from the dryness X1 of the vapor 5 and the weight of the drain 6, dryness or wetness of the fluid in the whole of the piping is calculated. By adjusting the dryness or wetness adjusting means 4 based on the calculated value, dryness or wetness of feed vapor can be controlled optionally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for arbitrarily controlling the dryness or wetness of a fluid as a mixture of vapor and liquid two-phase fluids such as a refrigerant and a condensate or a refrigerant gas and a refrigerant liquid. . For example, the ratio of the mass occupied by dry saturated steam to the total mass per unit volume of steam is expressed as dryness X
When the dryness is X, the wetness is represented by (1-X). In various boilers, equipment using steam power, drying equipment, and the like, for example, the operating efficiency and the drying state change depending on the moisture content in the steam, so that the dryness or wetness is measured and controlled.

[0002]

2. Description of the Related Art A conventional dryness or wetness control device is disclosed in, for example, Japanese Patent No. 2873640. It consists of a squeezing dryness meter or infrared wetness meter for measuring the dryness of steam, and a dryness and wetness control device for heating and cooling the steam. It can be arbitrarily controlled.

[0003]

In the conventional dryness controller or the squeezed dryness meter or the infrared wetness meter used in the conventional dryness control device, the dryness of the vapor in the gas phase can be measured. There was a problem that it was not possible to measure and control the dryness of the entire fluid pipe in consideration of drainage as a mixed layered condensate.

For example, in an actual steam pipe, there are many cases where a layer of a drain as a liquid phase is mixed below a layer of a vapor as a gas phase. With the above-mentioned conventional dryness meter, it is possible to measure the dryness of steam that changes based on the amount of fine water droplets contained in the steam, but it measures the dryness of the entire pipe taking into account the drain in the lower layer. And therefore cannot control the overall dryness of the piping.

[0005] Accordingly, an object of the present invention is to measure the dryness or wetness of a fluid in the entire piping including the layered liquid mixed in the fluid piping, and to control the dryness or dryness of a two-phase fluid. It is to provide a wetness control device.

[0006]

Means of the present invention taken to solve the above-mentioned problems are: a dryness or wetness measuring means for measuring the dryness or wetness of a fluid flowing down a pipe;
A device comprising a dryness or wetness adjustment means for adjusting the dryness or wetness of a fluid to control the dryness or wetness of a supplied fluid to a predetermined value, wherein the fluid is a gas-liquid two-phase fluid, In addition, the fluid dryness or wetness measuring means detects the dryness or wetness of the gaseous fluid and the gas phase fluid dryness detecting means, and detects the weight from the liquid level of the layered liquid phase fluid in the fluid piping. Liquid phase liquid level weight detecting means.

The invention according to claim 2 specifies an embodiment suitable for carrying out the invention according to claim 1, wherein the gas-phase fluid dryness detecting means detects the dynamic pressure of the gas-phase fluid. A dynamic pressure detecting means for detecting, a specific weight or specific volume calculating means for calculating a specific weight or a specific volume of the gas phase fluid from a dynamic pressure value detected by the dynamic pressure detecting means and a flow rate of the gas phase fluid; It is characterized in that the dryness or wetness of a gas-phase fluid is arithmetically controlled based on a relational expression between the specific weight or specific volume of the fluid and the dryness or wetness.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, the flow velocity of the gas-phase fluid is detected by a flow velocity detecting means, and the detected flow velocity value is supplied to the specific weight or specific volume calculating means. It is characterized by being constituted.

According to a fourth aspect of the present invention, in addition to the configuration of the second aspect, the dynamic pressure detecting means is a pitot tube or an elastically urged flap, and detects the static pressure of the gas-phase fluid flowing down. A static pressure detecting means is provided.

According to a fifth aspect of the present invention, in addition to the configuration of the second aspect, the dynamic pressure detecting means is a pitot tube, and the static pressure is also detected by the pitot tube.

The invention according to claim 6 specifies an embodiment suitable for carrying out the invention according to claim 1, wherein the liquid phase fluid level weight detecting means is provided on an outer surface at the bottom of a fluid pipe. Liquid level detection for detecting the liquid level in the fluid pipe from the attached ultrasonic transceiver and the time until the ultrasonic wave radiated upward from the ultrasonic transceiver is reflected by the liquid surface and returned. Means for calculating the unit volumes of the gas phase fluid and the liquid phase fluid in the fluid pipe from the liquid level detected by the liquid level detecting means, and calculating and calculating the weight from the unit volume of the liquid phase fluid. It is characterized by the following.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The dryness of a gas phase fluid is detected by a gas phase fluid dryness detecting means, and the unit of the liquid phase and the gas phase in the fluid pipe is measured from the liquid level detected by the liquid phase fluid level detecting means. Calculating the volume, calculating the gas weight S and the liquid weight D in the gas phase fluid from the unit volume and dryness of the gas phase, and calculating the weight D 'of the liquid phase fluid from the unit volume of the liquid phase Accordingly, the dryness or wetness of the entire fluid pipe can be measured and controlled as the dryness X = S / (S + D + D ′) of the gas-liquid two-phase fluid.

The dynamic pressure of the gaseous fluid flowing down is detected by the dynamic pressure detecting means, and from the detected dynamic pressure value and the flow velocity of the gaseous phase fluid,
The specific weight or specific volume calculation means can calculate the specific weight or specific volume by the equation of dynamic pressure value = ρV2 / 2. Here, ρ is the specific weight of the gas phase fluid, V is the flow velocity, and the specific volume: v can be obtained as the reciprocal of ρ.

For example, there is a relational expression expressed by a predetermined definition equation between the specific weight or specific volume of steam as a gas phase fluid and the dryness or wetness of steam. The dryness or wetness of the steam is calculated from the value calculated by the means and this relational expression, and the dryness or wetness of the supplied steam can be arbitrarily controlled.

When the flow rate of the gaseous phase fluid is unclear, the flow rate detecting means detects the flow rate of the gaseous phase fluid, and uses the detected flow rate value as the specific weight or specific volume calculating means. To be calculated.

When the static pressure of the gas phase fluid is unclear, the static pressure detecting means may be used in addition to the pitot tube or the elastically urged flap as the dynamic pressure detecting means. , Also easily detects the static pressure of the flowing gas phase fluid,
The dryness can be calculated and controlled. In addition, by using a pitot tube as a double tube with a static pressure tube, the pitot tube detects both the dynamic pressure as the difference between the total pressure and the static pressure and the static pressure, and calculates and controls the dryness. can do.

In the liquid phase fluid level weight detecting means, the time required for the ultrasonic wave radiated upward from the ultrasonic transmitter / receiver attached to the bottom outer surface of the fluid pipe to be reflected by the liquid surface and returned. To detect the liquid level in the fluid pipe. From the detected liquid level, the areas of the liquid phase portion and the gas phase portion are calculated, and the unit volumes of the liquid phase and the gas phase at the unit length of the fluid pipe are calculated. Further, the weight of the liquid phase fluid can be calculated from the calculated unit volume and specific volume of the liquid phase.

[0018]

EXAMPLE In this example, an example of controlling the dryness of a gas-liquid two-phase fluid of steam and drain will be described. In the present embodiment, the pitot tube 1 is used as the gas-phase fluid dryness detecting means.
And an example in which the ultrasonic transceiver 2 is used as the liquid-phase fluid level weight detection means.

In FIG. 1, upper and lower steam pipes 3 through which a mixed fluid of steam and drain as a controlled fluid flows down from left to right, adjusting means 4 for adjusting dryness or wetness,
The dryness or wetness measuring means 24 constitutes a two-phase fluid dryness or wetness control device. The lower steam pipe 3 passes through the adjusting means 4 and communicates with the steam pipe 3 which is enlarged and shown in the upper part. In the steam pipe 3, the steam 5 flows down in a layered manner at the upper part and the drain 6 flows down in a layered manner.

An end opening 7 of the pitot tube 1 serving as a dynamic pressure detecting means is disposed substantially at the center of the steam pipe 3 and communicates with the upper pressure transducer 8. The pitot tube 1 of the present embodiment uses a single tube capable of detecting the total pressure of the fluid.

A pressure sensor 9 is mounted above the end opening 7 of the pitot tube 1 as a static pressure detecting means for detecting the static pressure of the steam to be measured. The dynamic pressure of the steam can be obtained by subtracting the static pressure detected by the pressure sensor 9 from the total pressure detected by the pitot tube 1. When a pitot tube 1 is provided with a static pressure tube and is of a double tube type capable of detecting static pressure, the pressure sensor 9 does not necessarily need to be attached. Further, even when the static pressure of the steam is known, the pressure sensor 9 does not necessarily need to be attached.

At a further upstream side of the pressure sensor 9, a flow velocity sensor 10 is mounted as flow velocity detecting means for detecting a flow velocity of the steam passing through the steam pipe 3. The flow rate sensor 10
The inside is constituted by a sensor unit 10 (not shown) and a flow velocity converter 21. The flow rate sensor 10 does not necessarily need to be attached when the flow rate of the passing steam is known.

The ultrasonic transmitter / receiver 2 is mounted on the outer periphery of the bottom of the steam pipe 3.
Attach. On the other hand, on the upstream side of the flow velocity sensor 10, a supply pipe 22 and a discharge pipe 23 for the cooling fluid are connected to the upper and lower parts of the steam pipe 3, respectively.

The dryness or wetness adjusting means 4 includes a heater 11 for heating the supplied steam to increase the dryness, and a cooler 12 for supplying water droplets to the steam to reduce the dryness. It consists of.

A heater fluid supply pipe 14 and a discharge pipe 15 are connected to the heater body 13 via a valve 19 to control the supply amount of the heating fluid to appropriately heat the steam passing through the heater body 13. Thus, the dryness of steam can be arbitrarily increased.

A cooling water supply pipe 17 is connected to the cooler main body 16 via a valve 20, so that the dryness of steam can be arbitrarily reduced. A steam trap 18 is connected to a lower portion of the cooler body 16 to discharge excess cooling water in the cooler body 16 to the outside.

The valves 19 and 20, the pressure transducer 8 of the pitot tube 1, the pressure sensor 9, and the flow rate transducer 2
1 and the ultrasonic transceiver 2 are electrically connected to an arithmetic control unit (not shown).

Using the pitot tube 1 as a gas phase fluid dryness detecting means, the dryness X1 or wetness (1-X
In order to measure 1), first, the total pressure of the steam 5 is detected by the pitot tube 1, and the specific weight or ratio is determined from the dynamic pressure value as a difference between the total pressure and the static pressure and the flow velocity V of the steam 5. The volume calculating means calculates the specific weight or specific volume of the steam 5 by the equation of dynamic pressure = ρV 2/2. Note that the specific volume v is obtained as the reciprocal of the specific weight ρ.

A specific relational expression exists between the specific weight or specific volume of the steam 5 and the dryness or wetness. That is, ρ
= X1 / v〃 + (1−X1) / v ′ expression holds. Here, ρ is the specific weight of steam 5, X1 is the dryness of steam 5, v〃
Is the specific volume of saturated steam, and v 'is the specific volume of saturated water. v
〃 and v ′ can be uniquely obtained from the steam table if the static pressure of the measured steam is known. Accordingly, the static pressure in the steam pipe 3 is measured by the pressure sensor 9 and v〃 and v ′ are obtained from the specific volume of the saturated steam and the specific volume of the saturated water for each pressure in the steam table stored in advance. Can be requested.

The above equation, ρ = X1 / v〃 + (1-X1)
By determining ρ, v〃, and v ′ in / v ′, the dryness X1 of the measured steam 5 can be obtained, and similarly, the wetness (1−X1) can be obtained.

Next, an example in which the ultrasonic transceiver 2 detects the unit volumes of the steam 5 and the drain 6 will be described. The ultrasonic transceiver 2 attached to the bottom outer surface of the steam pipe 3 is connected to an arithmetic control unit (not shown). The relation between the specific volume of the saturated steam and the saturated water and the steam pressure is stored in the arithmetic control unit in advance.

The ultrasonic transmitter / receiver 2 emits ultrasonic waves upward from the bottom outer surface of the steam pipe 3 every predetermined time, and is reflected from the upper liquid surface of the drain 6 and returns from the steam pipe 3. 3, the area of the steam section 5 of the steam pipe 3 having a predetermined pipe diameter and the area of the drain section 6 are calculated from the detected liquid level, and the steam 5 in the unit length of the steam pipe 3 is calculated. And the unit volume V2 of the drain 6 are calculated.

Next, based on the calculated unit volume V1 of the steam 5 and the dryness X1, the weight S of the dry saturated steam in the steam 5 and the weight D of the fine water-drop-shaped drain contained in the steam 5 are calculated. calculate. That is, X1 = S / (S + D), and X1
Have already been determined, and similarly, S and D at known V1
S and D can be calculated from the ratio of.

Next, the calculated unit volume V2 of the drain 6
Is multiplied by the reciprocal of the specific volume of the saturated water based on the pressure of the steam pipe 3 to calculate the weight D 'of the drain 6, and the dryness X of the two-phase fluid composed of the steam 5 and the drain 6 is calculated as X = S / (S +
D + D '), the dryness of the entire fluid pipe 3 can be obtained.

Further, the overall dryness or wetness determined by the arithmetic and control unit is compared with the set value inputted, and the arithmetic and control unit sends the values to the valves 19 and 20 so that the deviation between them is set to, for example, zero. And the valves 19 and 20 are controlled to open and close, and the dryness or wetness of the supplied steam is arbitrarily controlled.

In this embodiment, an example is shown in which the pitot tube 1 is used as the dynamic pressure detecting means. In addition, a flap as a resistance plate having a predetermined area elastically urged by a spring or the like is attached, and the measurement is performed. By detecting the displacement of the flap based on the dynamic pressure of the steam, a dynamic pressure detecting means can be provided.

As the flow velocity sensor 10 in this embodiment, a conventionally known one such as an electromagnetic type, an ultrasonic type, a vortex type, a thermal type, a turbine type, or a laser Doppler type can be used.

[0038]

As described above, according to the present invention, a gas-phase fluid dryness detecting means and a liquid-phase fluid level weight detecting means are provided, and the detection value of each of the detecting means is used to determine the fluid of the entire pipe. Dryness or wetness can be measured, and therefore the dryness or wetness of the fluid throughout the piping can be controlled.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional configuration diagram of an apparatus for controlling dryness or wetness of a two-phase fluid according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pitot tube 2 Ultrasonic transceiver 3 Steam piping 4 Dryness or wetness adjustment means 11 Heater main body 14 Heating fluid supply pipe 16 Cooler main body 17 Cooling fluid supply pipe 24 Dryness or wetness measurement means

Claims (6)

[Claims] 1. A supply system comprising a dryness or wetness measurement means for measuring the dryness or wetness of a fluid flowing down a pipe, and a dryness or wetness adjustment means for adjusting the dryness or wetness of a fluid. In controlling the dryness or wetness of the fluid to a predetermined value, the fluid is a gas-liquid two-phase fluid, and
The fluid dryness or wetness measuring means detects the dryness or wetness of the gaseous fluid, and a liquid which detects the weight from the liquid level of the layered liquid phase fluid in the fluid piping. A two-phase fluid dryness or wetness controller. 2. The method according to claim 1, wherein said gas phase fluid dryness detecting means detects a dynamic pressure of the gas phase fluid, and a dynamic pressure value detected by the dynamic pressure detecting means and a flow rate of the gas phase fluid. Specific weight or specific volume calculating means for calculating the specific weight or specific volume of the fluid,
An arithmetic control unit that calculates the dryness or wetness of the gaseous fluid based on a relational expression between the specific weight or specific volume of the gaseous fluid and the dryness or wetness. 2. The apparatus for controlling dryness or wetness of a two-phase fluid according to claim 1. 3. The two-phase fluid according to claim 2, wherein the flow rate of the gas-phase fluid is detected by a flow rate detecting means, and the detected flow rate value is supplied to the specific weight or specific volume calculating means. Dryness or wetness control device. 4. The apparatus according to claim 2, wherein said dynamic pressure detecting means is a pitot tube or an elastically urged flap, and further comprises a static pressure detecting means for detecting a static pressure of a gas phase fluid. A two-phase fluid dryness or wetness control device. 5. The dryness or wetness control apparatus for a two-phase fluid according to claim 2, wherein the dynamic pressure detection means is a pitot tube, and the static pressure is also detected by the pitot tube. 6. An ultrasonic transmitter / receiver attached to a bottom outer surface of a fluid pipe, wherein an ultrasonic wave radiated upward from the ultrasonic transmitter / receiver is at a liquid level. A liquid level detecting means for detecting a liquid level in the fluid pipe from a time until it is reflected and returned, and a gas phase fluid and a liquid phase in the fluid pipe based on the liquid level detected by the liquid level detecting means. The dryness or wetness control device for a two-phase fluid according to claim 1, wherein a unit volume of the fluid is calculated, and a weight is calculated from the unit volume of the liquid phase fluid.