JPH0448246A - Near infrared humidity measuring instrument - Google Patents

Abstract

PURPOSE:To accurately measure humidity without being affected by dirt by detecting the difference between the quantities of near infrared rays which are reflected by two rotary reflecting plates. CONSTITUTION:Near infrared rays having wavelength which is absorbed by water are guided to a two-unit optical fiber cable 14 through a filter lens 13 which transmits only light with wavelength emitted by a light emitting element 12 to irradiate piping 1 from the light emission surface of an optical fiber connector 2. The radiating near infrared rays are reflected by 1st and 2nd rotary reflecting plates 3 and 4 which are rotated by the flow of fluid in the piping 1 and received by a light receiving element 15 from the light reception surface of a two-unit optical fiber connector 2 through the two-unit optical fiber cable 14 alternately to generate electric signals corresponding to the quantities of received light. The electric signals are inputted to a calculation device 17 through an amplifier 16. The calculation device 17 calculates the humidity in the piping 1 from the difference between the levels of reflected light beams which are inputted alternately. Consequently, even if the light emitting and receiving surfaces are stained, the humidity can accurately be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a near-infrared humidity measuring device that measures the humidity of gas flowing through a pipe using near-infrared rays, and in particular, a near-infrared humidity measuring device that emits and receives near-infrared rays when facing inside the pipe. This invention relates to a device that prevents humidity measurement accuracy from decreasing even if dirt occurs on the opening surface of a light emitting/light receiving device.

This near-infrared humidity measuring device takes advantage of the fact that moisture has a large absorbance at a specific wavelength of infrared rays, and can measure humidity from the relationship between absorbance and humidity.

2. Description of the Related Art A conventional near-infrared humidity measuring device will be explained with reference to FIG. This is a light emitting/receiving device that has a reflector plate 32 attached to the bottom of the gas pipe 31, and a near-infrared light emitting port and a light receiving port for receiving the near-infrared light from the reflector plate 32 at the top of the tube opposite to the reflector plate 32. The device 33 is attached, and the light emitting device 3
3 irradiates the pipe 31 with near-infrared rays having a wavelength that is absorbed by moisture, the reflection plate 32 reflects the near-infrared rays, and the humidity is calculated based on the amount of near-infrared rays received by the light receiving device 33.

Problems to be Solved by the Present Invention In the above system, if the opening surface of the light emitting/light receiving device 33 facing the pipe 31 becomes dirty due to adhesion of foreign matter in the pipe, the light emitting/light receiving level decreases, There was a problem that it could not be measured.

Therefore, a technical problem of the present invention is to enable accurate humidity measurement even if the light emitting and light receiving surfaces become dirty.

Means for Solving the Problems The technical means of the present invention taken to solve the above-mentioned technical problems consists of a light emitting/light receiving device having a near-infrared light emitting port and a light receiving port attached to a gas pipe; A first rotary reflector disposed facing the light receiving aperture, a second rotary reflector disposed between the first rotary reflector and the light emitting/light receiving aperture, an opening formed in the second rotating reflector so that the light reaches the first rotating reflector directly; a member for cleaning the first and second rotating reflectors; and a first and second rotating light received by the light receiving device. and a calculation device that calculates humidity from the amount of near-infrared rays reflected from the reflector.

action The operation of the above technical means is as follows.

Near-infrared rays emitted from the light emitting device are reflected by the second rotating reflector and received by the light receiving device. Furthermore, since the second rotating plate is rotating and has an aperture, when near-infrared rays pass through the aperture, the near-infrared rays are reflected by the first rotating reflector and received by the light receiving device. .

Since the first and second rotary plates are cleaned by the cleaning member and kept in the same state, no difference in dirt occurs. Even if the light emitting and light receiving surfaces of the light emitting/receiving device become dirty with foreign matter in the piping, the light emission level will decrease due to the dirt, and the light receiving level of the amount of near infrared rays reflected from the first and second rotating reflectors will decrease. decrease by the same amount. The rate at which near-infrared rays are absorbed by moisture differs depending on the distance from the light emitting/receiving device to both rotating reflectors. Therefore, by detecting the difference in the amount of near-infrared rays reflected from the first and second rotating reflectors,
Accurate humidity measurement is possible without being affected by dirt.

Effect of the invention The present invention produces the following unique effects.

As described above, according to the present invention, humidity can be accurately measured even if dirt occurs on the light emitting and light receiving surfaces.

Embodiment An embodiment illustrating a specific example of the above technical means will be described (see FIGS. 1 and 2).

A two-wire optical fiber connector 2 that has a light emitting port that irradiates near-infrared rays with a wavelength that is absorbed by water onto the snow field of the fluid piping 1, and a light receiving port that receives near-infrared rays reflected from the reflecting plate described below.
Attach.

A first rotary reflector 3 and a second rotary reflector 4 are arranged facing the two-wire optical fiber connector 2.

The first and second rotating reflectors 3 and 4 are attached to a rotating shaft 7 whose upper and lower ends are rotatably connected to the pipe 1 via bearings 5 and 6. A rotating blade 8 is attached to a rotating shaft 7 below the first rotating reflecting plate 3 so that the rotating shaft 7 is rotated by the flow of fluid in the pipe 1. As shown in FIG. 2, the first and second rotary reflecting plates 3 and 4 are formed into approximately cross shapes with cutouts provided on the outer circumferential side of discs, so that they do not overlap with each other. This spark forms the opening of the second rotating reflector.

A mounting member 9 is attached to the pipe 1, and the first and second
Brushes 10 and 11 are attached to clean the rotating reflecting plates 3 and 4.

Near-infrared light having a wavelength that is absorbed by moisture is converted into light generated by a light-emitting element 12, which is a light-emitting device, and is guided to a two-line optical fiber 14 through a filter lens 13 that transmits only light of that wavelength. The light is irradiated onto the piping 1 from the light emitting surface of the optical fiber connector 2 . The irradiated near-infrared rays are reflected by the first and second rotating reflection plates 3 and 4 that are rotating due to the fluid flow in the pipe 1, and are alternately reflected from the light receiving surface of the two-wire optical fiber connector 2 to the two-wire optical fiber 14. The light passes through and is received by a light receiving element 15, which is a light receiving device, and an electrical signal corresponding to the amount of light received is generated. This electrical signal is input to the calculation device 17 via the amplifier 16.

The calculation device 17 calculates the humidity inside the pipe 1 from the difference in the reflected light levels that are alternately input.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a near-infrared humidity measuring device according to an embodiment of the present invention, FIG. 2 is a plan view of first and second rotating reflectors,
FIG. 3 is a schematic diagram of a conventional near-infrared humidity measuring device. 2: Two-wire optical fiber connector 3: First rotating reflector 4: Second rotating reflector 7: Rotating shaft 8: Rotating blade 9: Light emitting element 10 11: Brush 15: Light receiving element 17: Arithmetic unit

Claims (1)

[Claims] 1. A light-emitting/light-receiving device having a near-infrared light-emitting port and a light-receiving port attached to a gas pipe, a first rotating reflector placed opposite the light-emitting/light-receiving port, and a first rotating reflector and a light-emitting/light-receiving device.
a second rotary reflector disposed between the light receiving ports; an opening formed in the second rotary reflector so that near-infrared rays emitted from the light emitting device directly reach the first rotary reflector;
A near-infrared humidity measuring device comprising: a member for cleaning the second rotating reflector; and a calculating device for calculating humidity from the amount of reflected near-infrared rays from the first and second rotating reflectors received by the light receiving device.