JP3878344B2 - Fluid dryness measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for measuring the dryness of a fluid mixed with gas and liquid such as steam and refrigerant. For example, in various boilers and devices using steam power, it is necessary to know the dryness indicating the moisture content in steam, that is, the ratio of the mass of dry saturated steam to the total mass per unit volume of the steam flow. This is because the enthalpy of the steam varies depending on the moisture content. Similarly, it is necessary to know the dryness of the refrigerant in refrigeration equipment such as a refrigerator and an air conditioner.
[0002]
[Prior art]
As a conventional fluid dryness measuring apparatus, there is a squeeze dryness meter that measures the dryness of steam by utilizing the change in the isoenthalpy of steam. This is achieved by injecting wet steam into the measurement container through the nozzle and adiabatic expansion (isenthalpy change) to form superheated steam, and detecting the pressure upstream from the nozzle and the pressure and temperature in the measurement container. The dryness is measured using a figure or a saturated steam table and a superheated steam table.
[0003]
[Problems to be solved by the invention]
The above-mentioned conventional dryness meter has a problem that only a part of wet steam can be measured because the range of measurable vapor pressure and dryness is limited. That is, when the pressure or dryness of the wet steam to be measured is low, the superheated steam state is not obtained after adiabatic expansion. Therefore, the technical problem of the present invention is to provide a fluid dryness measuring device that has a wide range of dryness that can be measured and can easily measure dryness.
[0004]
[Means for Solving the Problems]
The technical means of the present invention taken in order to solve the above technical problem includes a measurement container filled with fluid, an ultrasonic transmitter and an ultrasonic receiver attached to the measurement container, Calculation control for calculating the sound speed from the pressure detection means attached to the measurement container and the propagation time of the ultrasonic wave passing through the fluid, and calculating and outputting the dryness of the fluid from the sound speed and the pressure signal detected by the pressure detection means A fluid dryness measuring apparatus, comprising:
[0005]
DETAILED DESCRIPTION OF THE INVENTION
A fluid to be measured is filled in a measurement container, and an ultrasonic pulse is transmitted from an ultrasonic transmitter attached to the measurement container and received by an opposing ultrasonic receiver. The propagation time T of the ultrasonic wave passing through the fluid is T = L / C, where L is the distance between the ultrasonic transmitter and the ultrasonic receiver, and C is the speed of sound in the fluid. The speed of sound in the fluid can be determined. In addition, there is a relationship that the speed of sound in the fluid changes depending on the dryness of the fluid, and the lower the dryness, the higher the speed of sound. Therefore, based on the relationship between the sound speed and the dryness, the dryness of the fluid can be calculated from the calculated sound speed.
[0006]
As described above, according to the present invention, the dryness of the fluid is calculated from the propagation time of the ultrasonic wave, and therefore it is not necessary to put the fluid in a superheated steam state. Therefore, the range of dryness that can be measured is wide, and the dryness can be easily measured.
[0007]
【Example】
An embodiment showing a specific example of the above technical means will be described (see FIGS. 1 and 2). This embodiment is applied to a vapor dryness measuring apparatus. A bypass pipe 2 is provided in the middle of the steam pipe 1 through which the steam flows, and a measurement container 3 is provided in the bypass pipe 2 and an opening / closing valve 4 is interposed downstream of the measurement container 3. An ultrasonic wave transmitter 5 and an ultrasonic wave receiver 6 are attached to the measurement container 3 so as to face the ultrasonic wave transmitter 5. An oscillator 7 is connected to the ultrasonic transmitter 5, a receiver 8 is connected to the ultrasonic receiver 6, and the oscillator 7 and the receiver 8 are connected to the arithmetic controller 9. Further, the pressure detection means 10 is attached to the measurement container 3 and connected to the arithmetic controller 9.
[0008]
Next, the measurement of the vapor dryness by this apparatus will be described. First, the on-off valve 4 is opened and a part of the steam flowing through the steam pipe 1 is caused to flow into the bypass pipe 2. And after each part is fully heated, the on-off valve 4 is closed and the measurement container 3 is filled with steam. Subsequently, the arithmetic controller 9 supplies a trigger signal to the oscillator 7 to cause the oscillator 7 to oscillate, thereby supplying an oscillation output to the ultrasonic transmitter 5 to transmit an ultrasonic pulse. Is received by the ultrasonic receiver 6. The reception signal of the ultrasonic receiver 6 is supplied from the receiver 8 to the arithmetic controller 9. The detection signal of the pressure detection means 10 is supplied to the arithmetic controller 9.
[0009]
The arithmetic controller 9 calculates the speed of sound in the steam from the propagation time of the ultrasonic waves from the ultrasonic transmitter 5 to the ultrasonic transmitter / receiver 6, and the calculated sound speed and the pressure signal detected by the pressure detection means 10. Calculate the dryness of the steam from the output. Here, the speed of sound in steam and the degree of dryness of steam have a correlation as shown in FIG. 2, and there is a relationship that the degree of dryness decreases as the speed of sound increases. There is a relationship that the higher the value (P1>P2> P3), the higher the dryness. Therefore, the dryness of the steam can be calculated from the calculated sound speed and the detected pressure.
[0010]
【The invention's effect】
As described above, according to the present invention, the dryness of the fluid can be measured without making the fluid overheated by calculating the dryness of the fluid from the propagation time of the ultrasonic wave in the fluid. As a result, an excellent effect is obtained that the dryness can be easily measured.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a vapor dryness measuring apparatus according to the present invention.
FIG. 2 is a diagram showing the relationship between the speed of sound in the fluid and the degree of dryness of the fluid for each pressure used in the vapor dryness measuring apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steam piping 2 Bypass line 3 Measuring container 5 Ultrasonic transmitter 6 Ultrasonic receiver 7 Oscillator 8 Receiver 9 Arithmetic controller 10 Pressure detection means

Claims (1)

Measurement container filled with fluid, ultrasonic wave transmitter and ultrasonic wave receiver mounted relative to the measurement container, pressure detection means attached to the measurement container , and propagation time of ultrasonic wave through the fluid A fluid dryness measuring apparatus comprising: an arithmetic controller that calculates a sound velocity from the sound velocity and calculates and outputs the fluid dryness from the sound velocity and the pressure signal detected by the pressure detecting means .

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