JPS6269146A - Measuring device for wetness of vapor - Google Patents

Abstract

PURPOSE:To measure the wetness of vapor with high accuracy by dividing the light from a light source into two, leading one of them to an optical fiber for irradiating it to a detecting part, and leading the other to an photoelectric converting element. CONSTITUTION:To light sources 3, 3' and 3'', a power source is supplied successively through a controller 24 and a power source switching device 25 by a command from a signal operation processor 27, and its light is switched by an optical switch 23 which has synchronized with the switching device 25. This light is divided into two by an equal light quantity by a half mirror 50, and one of them is converted to an electric signal IO by a photodetector 51. The other is led to an optical fiber 6, becomes an incident light 5 to a wet vapor flow of a measuring space A, led to photodetectors 16, 12, as light 13 which is scattered by a water droplet in the space A and light 10 which is attenuated by the water droplet, by optical fibers 15, 11, respectively, converted to electric signals and fetched as a scattered light signal Is, and a transmission light signal Ir. These signals IO, Is and Ir are amplified 22, synchronized with a wavelength variation of the light source by the switching device 25, and the respective signals are identified and stored in a data store part of the device 27.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention is aimed at reducing moisture in steam that occurs under certain conditions as the state of the steam changes in steam turbines and various devices that utilize steam. The present invention relates to a device for measuring steam humidity.

[Background of the invention]

As shown in Japanese Patent Application Laid-Open No. 57-199943, the steam humidity measuring device greatly improves the conventional method and measures the humidity at any spot in the steam flow path instantaneously and continuously. It is now possible. This device is.

It is based on an optical method, and the condition is that the incident light source intensity is constant for scattered light from a group of water droplets in wet steam to be detected. In the method of detecting the characteristics of scattered light from a group of water droplets and the method of detecting the angular characteristics of the intensity of scattered light from a group of water droplets with respect to incident light, changes in the intensity of incident light are detected as changes in the intensity of scattered light from a group of water droplets. will be
This has a significant impact on the humidity measurement accuracy. By the way, the most common cause of changes in incident light intensity is changes in power supply voltage, and other causes include changes in characteristics due to thermal effects of electronic components. Such changes in the intensity of incident light can be adequately dealt with with the current level of technology, but it is difficult to measure vapor humidity instantly and
It cannot be measured continuously. In particular, since the wet vapor flow is a strongly unsteady flow, the reliability of the measured value of the wetness is greatly reduced when it is accompanied by a change in the intensity of the incident light. Therefore, a technical solution that can quickly respond when the incident light intensity changes is required, but this point is not examined in the cited document.

[Purpose of the invention]

An object of the present invention is to provide a device for measuring steam humidity with high accuracy. The light was irradiated into a stream of wet steam flowing in the space of the detection unit, and the amount of transmitted light and scattered light, which varied depending on the particle size distribution of water droplets in the wet steam and the total amount of water droplets, was received by an optical fiber. In contrast, in the present invention, in order to eliminate the above-mentioned drawbacks, the light from the light source is transmitted by a half mirror before entering the optical fiber to be transmitted to the detection part. Divide the amount of light into two,
One of the two divided lights is guided to an optical fiber for irradiating the detection section, and the other is guided to a light-to-electrical conversion element (first electrical signal).

Furthermore, the configuration is such that an electrical signal (second electrical signal) obtained by optical-to-electrical conversion of transmitted/scattered light from the detection section and the first electrical signal are stored in the data processing device at the same time.

The advantage of this configuration is that it is possible to detect variations in the light intensity of the light source at the same time as the measurement data, so the influence of changes in the light source light intensity can be excluded from changes in the transmitted and scattered light intensity on the detection unit. Instant and continuous measurement of wetness becomes more reliable.

[Embodiments of the invention]

Examples of the invention are detailed below.

FIG. 1 shows the practical area of this humidity measuring device, in which the tip 2 of a cylindrical detector 1 is inserted into a defined steam flow path. Inside the detector 1 and the tip 2, there is an optical fiber 6 for guiding the light irradiated into the measurement space A of the steam flow path, and a light receiver for detecting the light scattered by the water droplets in the steam. An optical fiber 11.15 is provided for leading to element 12.16. Further, the light from the light sources 3, 3', 31, etc. is guided to the half mirror 50 via the light sketch 23 and is divided into two parts, one of which enters the light receiving element 51 and the other which is provided inside the tip part 2. The optical fiber 6 guides the beam to a prism 7 for irradiating the measurement space A with a 90 degree deflection. Furthermore, prism 7
An optical fiber 1 is provided for guiding the light that has traveled straight into the measurement space via the prism 9 to the light receiving element 12. Further, a light receiving window 14 is provided so that scattered light in a direction perpendicular to the path of light irradiated into the measurement space A by the prism or the reflecting mirror 7 is guided to a light receiving element 16 by an optical fiber 15.

In FIG. 1, light sources 3.3' and 3' are shown as an example, and are substantially composed of a plurality of light emitting diodes or laser diodes, each of which generates m wavelengths different from each other. be done.

The power switch 25 is operated via the controller 24 in response to a command from the signal processing unit 27, and power is supplied to the light sources 5M in synchronization with the operation of the switch 25. The light from the light source is switched by the optical switch 23 which operates as follows. The light switched in this way is transmitted to the light path 53 located at the center of the support member 52.
A half mirror 50 provided at the side divides the light into two halves so that the amount of light is equal, and one side is converted into an electric signal Io by a light receiving element 51. The other is guided into an optical fiber 6 and becomes incident light 5 into the wet vapor stream in the measurement space A, light 13. scattered by the water droplets in the measurement space A. and an optical fiber 15 as the light 10 attenuated by the water droplets.
．． 11 to light receiving elements 16 and 12, where it is converted into an electrical signal and taken out as a scattered light signal Is and a transmitted light signal It. In this way, in the present invention, 1/2 of the amount of light from the light source is used.
Three types of information are obtained: a signal Io, a scattered light signal Is, and a transmitted light signal IT.
The operation of amplifying the data to a predetermined voltage and storing it in the data storage section in the signal processing device 27 is continued until a predetermined number of data are stored. Storage of these three types of signal data is carried out by the controller 2 according to instructions from the signal processing device 27.
4 operates the power supply switch 25 to synchronize with changing the wavelength of the light source, and also identifies and stores the three types of signals mentioned above. The details of this storage state are as shown in FIG. 2(a), where the signal processing device 27 generates the acquisition signal 61 at the time interval Δt, and the signals Is+ It and It+ are generated with a time delay of Δtp from the time of generation of this signal. It is taken in and stored. This signal acquisition is repeated for the wavelength λ1 of one type of light source the number of times n necessary for data transformation processing.6 Therefore, if the types of wavelengths of the light source are λ1 to λ, the signal processing device The number of data is as shown in Figure 2 (b), and the IS and IT signals in each acquisition include the influence of changes in the light source light intensity, but at the same time as the Is and IT signals, the light source light intensity signal Io is Since the data is taken in, data with extremely high accuracy can be obtained by averaging over time as shown below.

The average value of the signal, M=the number of types of light source wavelengths (1 to m).

After performing such signal processing, the signal processing device
Based on the following equation, which is a relational expression between the amount of incident light and the amount of scattered light, the particle size distribution of water droplets in humid steam is determined, and the degree of wetness is calculated.

Here, ■ = amount of scattered or transmitted light Io = amount of incident light I = I / time average value of Io (Is or It
) Cn = particle number concentration Q = optical path length of measurement space D = particle diameter i = refractive index of powder particles/refractive index of fluid 0 = angle between incident light and scattered light α = particle parameter (=πD/λ) λ,=wavelength of light N(D)=particle size distribution function=scattering coefficient Another example is shown in FIG. In the figure, a light emitting diode or laser diode 81 as a light source for irradiating an 8tq constant space C is equipped with its power supply device 94, and light from this light source is transmitted to a light path 72 located at the center of a support member 71. The amount of light from the light source is divided into two parts by the half mirror 73, one part is converted into an electric signal Io by the light receiving element 74, and the other part is sent to the optical fiber 85 disposed inside the main body 85. + from the irradiation window 83! Irradiate a constant space C. In the measurement space C, a plurality of light receiving windows 86, 87, 88, 89 are provided in the same plane as the irradiation light and at various angular positions with respect to the incident light on the surface of the tip 84 that is in contact with the space C. The scattered light incident on each light receiving window is guided to the light receiving elements 75, 76° 77.78 through optical fibers 90°91, 92, 93 to the light receiving windows and converted into electrical signals.
, convert to Isz+l5stISA. The IO+IS1°l5zt l5at IS4 signal converted into an electrical signal is connected to the signal processing device 27 via the voltage amplifier 22 and stored in the data storage section. Furthermore, the method of capturing each signal will be explained with reference to FIG. FIG. 4(a) shows the timing of signal acquisition. The signal processing device @27 generates the acquisition signal every Δ time, and correspondingly, after a delay time Δ14e, each angular position (OL *Scattered light signal at Dz+ Osr O+) ■si + I s x r I s 3HI
The s number and the light source signal Io are captured at the same time. This acquisition is carried out a sufficient number of times n to calculate the time average value of the signal.
The data storage format is as shown in Figure 4(b), in which n pieces of each signal are stored, and at each point in time when the signals from ISI to ISm are captured, changes in the amount of power light are recorded. However, the effect of this change can be removed by averaging as follows.

Here, (Is)s is the average value of scattered light at each angular position, and M is the number of scattered light measurement positions at different angular positions.

Therefore, in this embodiment, since there is only one light source and the wavelength of the light is constant, al! Since the angular dependence of scattered light from a group of water droplets in wet steam in I constant space C is determined by Kil+, the particle size distribution of the group of water droplets is calculated, and the wetness is determined, the basic formula for calculation is as follows. This is the same as equation (3), and the calculation process is performed using equation (3) as 118 in equation (4), with the wavelength constant being constant.

In the embodiment of the present invention, if the electronic components constituting the light emitting element as a light source and the light receiving element can withstand high temperatures, optical fibers, cooling mechanisms, etc. are unnecessary, and the light receiving window of the present invention can be used as a light receiving window. It becomes possible to arrange the light emitting elements and the light receiving elements in an array at the positions where the light emitting elements and the light receiving elements are arranged, the measuring device becomes smaller, and the number of information on the measured values can be increased, so that more accurate measurement can be realized.

〔Effect of the invention〕

According to the present invention, conventional adverse factors are accepted;
Fluctuation value that reduces measurement accuracy (light source fluctuation value)
The system is configured so that it can be used as data, and this data can be used to normalize the originally required amount of scattered light.
By averaging the time of the fluctuation process, extremely stable and highly accurate humidity measurement is possible.

[Brief explanation of drawings]

FIG. 1 is a structural sectional view of one embodiment of the present invention, and FIG. 2 is (a
) is a diagram showing the signal acquisition timing in Figure 1, and Figure 2 (
b) is a data storage configuration diagram by signal acquisition in FIG. 2(a), FIG. 3 is a structural sectional view of another embodiment of the present invention, and FIG. 4(a) is a diagram showing the signal acquisition timing in FIG. 3. Figure, 4th
FIG. 4(b) is a diagram illustrating the data storage format by signal acquisition in FIG. 4(a). 1...Detector, 6,11.15...Optical fiber, 3
゜3', 3', 81...Light source, 12.16,51
．． 74... Light receiving element, 23... Optical switch, 7,9...
・Blizz Ax g reflector, 14...light receiving window, 24...
Controller, 25... Power switch, 50.73... Optical branching device 1. Half mirror 122...Amplifier, 27...Signal processing device.

Claims (1)

[Scope of Claims] 1. A light source for irradiating light to the steam flow, an optical fiber and a prism or a reflecting mirror for transmitting the light to the irradiation window, in order to measure the wetness of the wet steam flow; a prism or a reflecting mirror that receives transmitted light from which the irradiated light has passed through the wet steam flow, the optical fiber that transmits the transmitted light to the light receiving element, and water droplets in the steam that are perpendicular to the direction of the transmitted light. the light receiving window for receiving scattered light from the light receiving window; and the optical fiber for transmitting the scattered light to the light receiving cable, and a plurality of light emitting elements having different wavelengths as the light source for the irradiation. , an apparatus comprising a switch for sequentially switching the light from the light emitting element to the optical fiber for irradiating the wet steam, an optical path to the optical fiber for transmitting the irradiated light from the light emitting element; An optical splitter or half mirror that divides the amount of light from the light source into two with the same intensity is arranged inside the interior, and one of the split lights is guided to the optical fiber for transmission, and the other part is connected to a separately installed light receiving element. The transmitted light and scattered light obtained in response to the switching of the wavelength of the irradiated light are converted into electrical signals and stored in a signal processing device while maintaining simultaneity with the electrical signals from the light receiving element that receives the transmitted light and scattered light. A steam humidity measuring device characterized by comprising: