JP2002277449A - Measuring apparatus for degree of dryness or wetness of two phase fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring apparatus for the degree of dryness or wetness of a two phase fluid which can measure the degree of the dryness or the wetness of a fluid in the entire piping containing layered liquids mingling in the piping of the fluid. SOLUTION: Ultrasonic transmitter/receivers 2, 3 and 4 are mounted on vapor piping 1 through which flow down vapors and drains. The degree of dryness X1 of the vapor are determined by the ultrasonic transmitter/receivers 2 and 3. The liquid level of the drain 6 is measured to determine the weight of the drain 6 from the conversion to weights. Moreover, the degree of dryness or wetness of the fluid in the entire piping can be detected from the degree of dryness X1 of the vapor and the weight of the drain 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the dryness or wetness of a fluid in which a vapor and a condensed liquid or a gas-liquid two-phase fluid such as a refrigerant gas and a refrigerant liquid are mixed. For example, the ratio of the mass occupied by dry saturated steam to the total mass per unit volume of steam is referred to as dryness X. When the dryness is X, the wetness is represented by (1-X). In various boilers, equipment using steam power, and drying equipment, it is necessary to measure the dryness of steam for heat management. This is because, for example, the dry state changes depending on the moisture content in the steam.

[0002]

2. Description of the Related Art Conventional steam dryness measuring devices include:
For example, there is a so-called squeezing dryness meter that measures the dryness by using a change in enthalpy of steam. This is done by injecting wet steam through the nozzle into the measuring vessel, adiabatic expansion (equal enthalpy change) into superheated steam, and detecting the pressure upstream of the nozzle and the pressure and temperature in the measuring vessel,
The dryness is measured using a Moliere diagram, a saturated steam table or a superheated steam table.

[0003]

The conventional dryness meter described above can measure the dryness of vapor as a gas phase, but takes into account the drainage as a layered condensate mixed in the fluid piping. However, there has been a problem that the dryness of the entire fluid pipe cannot be measured.

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 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.However, the dryness of the entire pipe taking into account the lower layer drainage can be measured. It cannot be measured.

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

[0006]

According to the first aspect of the present invention,
For measuring the dryness or wetness of a gas-liquid two-phase fluid, an ultrasonic transmitter / receiver installed opposite to the pipe through which the gas-phase fluid flows, and a gas phase based on the propagation time of the ultrasonic wave passing through the gas-phase fluid A gas phase fluid dryness detecting means for detecting the dryness or wetness of the fluid; and a liquid phase fluid level detecting means for detecting the weight from the liquid level of the layered liquid phase fluid in the fluid piping. The dryness or wetness of a gas-liquid two-phase fluid is calculated by taking into account the value detected by the liquid phase liquid level weight detection means to the value detected by the phase fluid dryness detection means. It is.

The invention according to claim 2 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 of a 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.

[0008]

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 as the dryness X = S / (S + D + D ′) of the gas-liquid two-phase fluid.

In the gas-phase fluid dryness detecting means, an ultrasonic signal is transmitted from a transmitter of an ultrasonic transmitter / receiver attached to a pipe through which the gas-phase fluid flows, and received by the other receiver. The propagation time T of an ultrasonic wave passing through a fluid is represented by T = L / L, where L is the distance between the ultrasonic transceivers and C is the speed of sound in the fluid.
Since it is C, the sound velocity in the fluid can be obtained from this. Further, there is a relationship that the speed of sound in a fluid changes depending on the degree of dryness of the fluid, and the lower the degree of dryness, the higher the speed of sound. Therefore, based on the relationship between the sound speed and the dryness, the dryness or wetness of the gas phase fluid can be calculated from the calculated sound speed.

In the liquid-phase fluid level weight detecting means, the ultrasonic waves radiated upward from the transmitter of the ultrasonic transmitter / receiver attached to the bottom outer surface of the fluid pipe are reflected by the liquid surface and reflected to the receiver. The liquid level in the fluid pipe is detected from the time until it returns. The areas of the liquid phase portion and the gas phase portion are calculated from the detected liquid level, and the unit volumes of the liquid phase and the gas phase at the unit length of the fluid pipe can be calculated. Further, the weight of the liquid phase fluid can be calculated from the calculated unit volume and specific volume of the liquid phase.

[0011]

EXAMPLE In this example, an example will be described in which the dryness of a gas-liquid two-phase fluid of steam and drain is measured using ultrasonic waves. In FIG. 1, a pair of ultrasonic transmitters 2 and a receiver 3 are attached in the middle of a steam pipe 1 in which a mixed fluid of steam and drain as a fluid to be measured flows down from left to right. FIG. 1 is a plan view of a steam pipe 1 and ultrasonic transceivers 2 and 3.
Is attached to almost the center of the steam pipe 1. As shown in FIG. 2, a pair of ultrasonic transceivers 4 for detecting the liquid level of the drain are attached to the outer surface of the bottom of the steam pipe 1. In the steam pipe 1, a steam 5 flows down in a layered manner at the upper part and a drain 6 flows down at a lower part, and the steam 5 is in a so-called wet steam state in which dry saturated steam and fine water droplets are mixed.

A pressure sensor 7 for detecting the internal pressure is attached to the steam pipe 1. Ultrasonic transceiver 2,
Each of the pressure sensors 3 and 4 and the pressure sensor 7 are connected to an arithmetic control unit (not shown).

The ultrasonic transmitters and receivers 2 and 3 as the gas-phase fluid dryness detecting means calculate the sound speed in the steam 5 from the propagation time of the ultrasonic wave, and calculate the steam speed from the calculated sound speed and the pressure value from the pressure sensor 7. A dryness X1 of 5 is detected. If the pressure is known, the pressure sensor 7 is not always necessary.

There is a certain correlation between the speed of sound in the steam 5 and the dryness X1 of the steam. As the speed of sound increases, the dryness X1 increases.
Will be lower. Even at the same sound speed, the higher the steam pressure, the higher the dryness X1. Therefore, the dryness X1 of the steam 5 can be detected from the calculated sound speed and the detected pressure.

Next, an example in which the ultrasonic transceiver 4 detects the unit volumes of the steam 5 and the drain 6 will be described. The ultrasonic transmitter / receiver 4 attached to the bottom outer surface of the steam pipe 1 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 4 emits an ultrasonic wave upward from the bottom outer surface of the steam pipe 1 every predetermined time, and is reflected from the upper liquid surface of the drain 6 and returned from the steam pipe 1. 1, the area of the steam section 5 and the area of the drain section 6 of the steam pipe 1 having a predetermined pipe diameter are calculated from the detected liquid level, and the calculated area of the steam section 5 and the area of the drain section 6 are calculated. The unit volume V1 of the steam 5 and the unit volume V2 of the drain 6 in the unit length of the steam pipe 1 are calculated from the area.

Next, from the 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 droplet-shaped drain contained in the steam 5 are calculated.
That is, X1 = S / (S + D), and X1 has already been obtained. Similarly, S and D can be calculated from the ratio of S and D in the known V1.

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 in the steam pipe 1 to calculate the weight D ′ of the drain 6,
X = S / (S
+ D + D ').

[0019]

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. It is possible to measure the dryness or wetness of the fluid in the entire pipe including the layered liquid mixed in the liquid.

[Brief description of the drawings]

FIG. 1 is a plan view of an apparatus for measuring dryness or wetness of a two-phase fluid according to the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steam piping 2, 3 Ultrasonic transceiver 4 Ultrasonic transceiver 5 Steam section 6 Drain section 7 Pressure sensor

Claims (2)

[Claims] An apparatus for measuring the dryness or wetness of a gas-liquid two-phase fluid, comprising: an ultrasonic transmitter / receiver attached to a pipe through which a gas-phase fluid flows; Gas phase fluid dryness detecting means for detecting the dryness or wetness of the gaseous fluid from the propagation time, and liquid phase fluid level weight detecting means for detecting the weight from the level of the layered liquid phase fluid in the fluid piping. To calculate the dryness or wetness of a gas-liquid two-phase fluid by taking into account the value detected by the liquid-phase fluid liquid level weight detector in addition to the value detected by the gas-phase fluid dryness detector. An apparatus for measuring dryness or wetness of a two-phase fluid. 2. The liquid-phase fluid level weight detecting means includes: an ultrasonic transceiver mounted on an outer surface of a bottom of a fluid pipe; and an ultrasonic wave radiated upward from the ultrasonic transceiver 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 apparatus for measuring dryness or wetness of 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.