JPH0774782B2 - Near infrared humidity measuring device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a near-infrared humidity measuring device for measuring the humidity of a gas flowing through a pipe by using near-infrared rays, and particularly emits and receives near-infrared rays facing a pipe. The present invention relates to a device for preventing humidity measurement accuracy from deteriorating even if an opening surface of a light emitting / receiving device or a reflecting plate for reflecting near infrared rays is contaminated.

This near-infrared humidity measuring device utilizes the fact that water has a large absorption at a specific wavelength of infrared rays, and can measure humidity from the relationship between the absorption and humidity.

2. Description of the Related Art A conventional near infrared humidity measuring device will be described with reference to FIG. This is a reflector 32 attached to the bottom of the gas pipe 31,
Light emission having a near-infrared emission port at the top of the tube facing the reflection plate 32 and a light reception port for receiving the near-infrared light from the reflection plate 32.
With the light receiving device 33 installed, connect the light emitting device 33 to the pipe 31
Reflector 32 irradiates near-infrared rays with a wavelength absorbed by water to
And the humidity is calculated based on the amount of near infrared light received by the light receiving device 33.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above, when the opening face of the light emitting / receiving device 33 facing the pipe 31 or the reflection plate for reflecting near infrared rays is contaminated due to foreign matter in the pipe, the light emitting / receiving level is However, there is a problem that the humidity cannot be accurately measured.

Therefore, a technical problem of the present invention is to enable accurate humidity measurement even if the light emitting / receiving device or the reflector plate is contaminated.

Means for Solving the Problems Technical means of the present invention taken to solve the above technical problems include a light emitting / receiving device having a near infrared ray emitting port and a light receiving port attached to a gas pipe, and a pipe. And a reflecting plate for reflecting near-infrared light emitted from the light emitting device attached to the blade member to the light receiving device at a position near the light emitting device and a position away from the light emitting device, and a light receiving device. The calculation device calculates the humidity from the amount of near-infrared rays reflected from the reflector received by the device.

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

The reflecting plate is rotated by the gas flow together with the blade member, and causes the near-infrared light emitted from the light emitting device to be reflected by the light receiving device alternately at a position near the light emitting device and a position far from the light emitting device. Even if foreign matter in the piping adheres to the light emitting / receiving surface of the light emitting / receiving device or the reflecting plate and is contaminated, the light emitting level decreases due to the dirt, and the light is alternately reflected from the reflecting plate at a position near the light emitting device and a position far from the light emitting device. The received light level of near-infrared rays is reduced by the same amount. The ratio of near infrared rays absorbed by water varies depending on the difference in the distance from the light emitting / receiving device to the reflector. Therefore, by detecting the difference in the amount of near-infrared rays reflected from the reflection plate at a position close to the light emitting device and a position far from the light emitting device, accurate humidity can be measured without being affected by dirt.

EFFECTS OF THE INVENTION The present invention produces the following unique effects.

As described above, according to the present invention, even if the light emitting and light receiving surfaces are contaminated, the humidity can be accurately measured. Therefore, there is no need for regular inspection and cleaning, which is convenient.

Example An example showing a concrete example of the above technical means will be described (see FIGS. 1 and 2).

A two-wire optical fiber connector 2 having a light emitting port for irradiating near infrared rays having a wavelength absorbed by water and a light receiving port for receiving reflected light of near infrared rays from a reflecting plate described below at the top of the fluid pipe 1.
Attach.

The mounting member 3 is attached to the pipe 1, and the rotary shaft 4 is attached thereto. The blade 5 is attached to the rotating shaft 4. In this embodiment, three blades 5 are attached at equal intervals. The reflectors 6 are attached to the blades 5, respectively. The blades 5 are rotated by the gas flow together with the rotary shaft 4, so that the reflectors 6 face each other alternately at a position closer to the two-wire optical fiber connector 2 and a position farther from it.

The near-infrared light having a wavelength absorbed by water is converted into light generated from the light emitting element 7 which is a light emitting device, and is guided to the two-wire optical fiber 9 through the filter lens 8 that transmits only the light having the wavelength. The pipe 1 is irradiated with light from the light emitting surface of the line optical fiber connector 2. The irradiated near-infrared rays are reflected when the reflecting plate 6 of the blade 5 which is rotating due to the gas flow in the pipe 1 faces the two-wire optical fiber connector 2 at a position close to and away from the two-wire optical fiber connector 2, and alternately the two-wire optical fibers. The light is received from the light receiving surface of the connector 2 through the two-wire optical fiber 9 to the light receiving element 10 which is a light receiving device, and an electric signal corresponding to the amount of received light is generated. This electric signal is input to the calculation device 12 via the amplifier 11. The calculation device 12 calculates the humidity in the pipe 1 from the difference in the reflected light levels that are alternately input.

Although three reflectors are provided in the above embodiment, the present invention is not limited to this, and any reflector can be used as long as it can be reflected alternately at a position near the light emitting / receiving device and at a position away from it. It may be a sheet. Similarly, the number of blades may be any number, and the number of blades and the number of reflectors need not necessarily be the same.

[Brief description of drawings]

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 sectional view taken along line II-II of FIG. 1, and FIG. 3 is a schematic configuration diagram of a conventional near-infrared humidity measuring device. Is. 2: 2-wire optical fiber connector 4: Rotating shaft 5: Blade 6: Reflector 7: Light emitting element 10: Light receiving element 12: Calculation device

Claims (1)

[Claims] 1. A light emitting / receiving device having a near infrared ray emitting port and a light receiving port attached to a gas pipe, a blade member arranged in the pipe and rotated by a gas flow, and irradiation from the light emitting device attached to the blade member. The near-infrared is composed of a reflector that reflects the near-infrared light to the light-receiving device at a position near the light-emitting device and a position away from the light-emitting device, and a calculation device that calculates the humidity from the amount of near-infrared light reflected from the light-receiving device. Infrared humidity measuring device.