JPH08122151A - Reflecting-mirror supporting device - Google Patents

Abstract

PURPOSE: To reflect laser light excellently regardless of the change in weather. CONSTITUTION: In the device, which supports a reflecting mirror for reflecting laser light for measurement, a supporting member 2 which fixes the above described reflecting mirror 1 at a specified position, a casing 5 which surrounds the supporting member 2 and the reflecting mirror 1 and has a transmitting window member 8 for transmitting the laser light on the laser optical axis, a tubular hood 9 attached to the casing 5 so as to surround the transmitting window member 8, and an air nozzle 10 which is provided in the hood 9 and forms an air curtain in the hood 9, are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflecting mirror supporting device for supporting a reflecting mirror for reflecting a laser beam when measuring a gas concentration distribution outside a vaporizer of a liquefied natural gas facility. It is a thing.

[0002]

2. Description of the Related Art Combustible gas is used as a fuel gas in various fields. For example, liquefied natural gas contains a large amount of methane gas and is used as city gas. Since leakage of flammable gas poses a disaster prevention problem, a place where LNG is handled, for example, an LNG storage base, is equipped with a system for detecting the leakage of gas and issuing an alarm or the like from the viewpoint of security.

The gas analysis measures and analyzes the amount and concentration of a gas of a specific component, and development of a non-contact gas analysis capable of performing measurement without contact with the gas is in progress. One of the non-contact gas analyzes is a light absorption method that optically measures the gas concentration.

The light absorption method is a method for measuring the concentration of, for example, methane gas in a non-contact manner according to Lambert-Beer's law by utilizing the fact that various gas molecules absorb light of wavelengths unique to each gas molecule. That is, since the transmission loss of light has different wavelength ranges depending on the type of gas, if the transmission loss of a specific wavelength range is detected, the specific gas concentration can be measured. For example, for methane gas, the wavelength is 1.6 μm, 3.3 μm,
There is characteristic absorption near 7.8 μm. This light absorption method enables measurement over a long optical path over a wide range, and because of the sharp wavelength characteristics of light it is possible to selectively measure only the target gas species in a mixed gas. Applicable to various gases simply by selecting the laser wavelength
It has excellent features such as.

[0005]

By the way, in order to monitor a wide outdoor area such as around the vaporizer of the LNG storage base by the above-mentioned gas analysis (light absorption method), the light from a light source such as an optical transmitter is used. For example, the laser light is arranged in a mesh shape in, for example, two vertical and horizontal directions by a reflecting mirror such as a moving mirror and a fixed mirror arranged in a key place, and an optical path of the laser light is formed in a plane. By measuring the gas concentration in each of these optical paths and performing arithmetic processing on these by a proportional distribution method or the like, the gas concentration distribution can be obtained planarly, and the leak location and the leak amount of LNG can be measured quickly and accurately. .

As described above, when the light from one light source is arranged in a mesh, one light path length is very long and the distance between the reflecting mirrors is large at the LNG storage base, and therefore the reflecting mirrors are slightly angled. Even if there is a deviation, the light will diverge before it reaches the next reflector. Then, while the light is reflected by the plurality of reflecting mirrors, it is completely separated from the measuring optical path, and the measurement becomes impossible. Therefore, the reflecting mirror is fixed at a predetermined position by a supporting member, the supporting member and the reflecting mirror are surrounded by a casing so as not to be affected by the outside air, and the laser light is transmitted on the laser optical axis of this casing. It is proposed to provide a transparent window member. However, when it rains, raindrops adhere to the transmissive window member and light is diffusely reflected, and the light intensity decreases. Then, the light may be attenuated while being reflected by the plurality of reflecting mirrors, and measurement may be impossible.

Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide a reflecting mirror support device capable of favorably reflecting laser light without being affected by changes in weather. It is in.

[0008]

In order to achieve the above-mentioned object, a reflecting mirror supporting device of the present invention is a device for supporting a reflecting mirror for reflecting laser light for measurement, wherein the reflecting mirror is set at a predetermined position. A supporting member to be fixed to, a casing having a transparent window member that surrounds the supporting member and the reflecting mirror and transmits laser light on the laser optical axis, and a cylindrical type that is attached to the casing and surrounds the transparent window member. The eaves and an air nozzle that is provided in the eaves and forms an air curtain in the eaves are provided.

Further, in an apparatus for supporting a reflecting mirror for reflecting laser light for measurement, a supporting member for fixing the reflecting mirror in a predetermined position, a supporting member surrounding the supporting member and the reflecting mirror, and on a laser optical axis. A casing having a transparent window member that transmits laser light to, and attached to the casing,
A cylindrical eaves surrounding the transparent window member and an air blowing unit for blowing air to the reflecting mirror and the transparent window member are provided.

Further, in a device for supporting a reflecting mirror for reflecting a laser beam for measurement, a supporting member for fixing the reflecting mirror at a predetermined position, and surrounding the supporting member and the reflecting mirror and on the laser optical axis. A casing having a transparent window member that transmits laser light, a cylindrical eaves attached to the casing and surrounding the transparent window member, and an air nozzle that is provided in the eaves and forms an air curtain in the eaves, An air blowing unit for blowing air to the reflecting mirror and the transmission window member is provided.

[0011]

Since the supporting member and the reflecting mirror are surrounded by the casing, the supporting member and the reflecting mirror are not easily affected by the outside air. Therefore, the reflecting mirror should always guide the laser beam in the intended direction without being affected by the change of weather. Is possible. Further, since the air curtain is formed in the cylindrical eave by providing the eaves and the air nozzle, raindrops are suppressed from entering even in a storm, so that the raindrops are prevented from adhering to the transmission window member. or,
Since a part of the air forming the air curtain collides with the transmission window member, water droplets attached to the transmission window member are blown off. Therefore, the laser beam can be well reflected even in the case of rain.

Further, by blowing the air onto the reflecting mirror and the transmitting window member by the air blowing means, dew condensation does not occur on the reflecting mirror and the transmitting window member, and when the dew condensation occurs, the air is reflected on the reflecting mirror and the transmitting window member. By blowing on the window member, dew condensation can be removed and light can be reflected well.

[0013]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a corner cube mirror which is a reflecting mirror. The corner cube mirror 1 reflects a laser beam and reverses the direction of the laser beam.

The corner cube mirror 1 is mounted on a fixed base 3 which is horizontally mounted on top of a support column 2 which is a support member. The support pillar 2 is formed of an iron pillar having a predetermined diameter, a cylindrical iron pipe, or the like, and is provided upright on the ground surface (or on a fixed object on the ground surface). Support pillar 2
A heat insulating material 4 is provided on the outer periphery of the. The heat insulating material 4 is, for example, a glass wool tape or sheet having a thickness of 75 mm wound around the outer circumference of the support pillar 2.
Is uniformly covered with the heat insulating material 4 so that the exchange of temperature with the outside air is blocked and deformation due to thermal expansion does not occur.

The corner cube mirror 1 and the support pillar 2 are surrounded by a casing (mirror box) 5, that is, the corner cube mirror 1 and the support pillar 2 are housed in the mirror box 5. The mirror box 5 encloses side plates extending above the mirror 1 along the support pillars 2 on the fixed object 6 (or on the ground surface) on the surface of the ground, arranged on four sides of the support pillars 2, and surrounds the top opening. It is covered with a top plate and is made of a material that prevents direct sunlight from hitting the support columns 2, the mirror 1, and the heat insulating material 4.

A circular transmission window 7 having a predetermined size is provided at the entrance and exit points of the laser light of the mirror box 5, and the transmission window 7 is made of CaF ₂ which transmits the laser light. The transparent window member 8 formed by, for example, is fitted in, and the inside of the mirror box 5 is shielded from the outside air.

The transparent window member 8 surrounding the transparent window member 8 is formed near the edge of the mirror box 5 forming the transparent window 7.
A larger diameter cylindrical eave or hood 9 for rain protection is mounted along the laser optical axis. Hood 9
Is for preventing raindrops from adhering to the transmission window member 8 when it rains.

A flat air nozzle 10 for forming an air curtain in the hood 9 is attached to the hood 9, and the flat air nozzle 10 may have any structure as long as it forms the air curtain in the hood 9.
For example, as shown in FIG. 5, a slit 11 may be provided in the circumferential direction, and air may be blown from the slit 11 to form an air curtain. Flat air nozzle 1
As shown in FIGS. 1 and 2, a first air supply pipe 13 having a first regulating valve 12 is connected to 0.

Further, air is blown to the front and rear of the transmissive window member 8 and the front of the corner cube mirror 1 to at least both surfaces of the transmissive window member 8 through which laser light is transmitted and reflected and the front surface (reflection surface) of the corner cube mirror 1. Air nozzles 14, 15 and 16 are respectively provided as air spraying means. A second air supply pipe 18 having a second adjusting valve 17 is connected to the air nozzles 14, 15, 16 and a membrane dryer 19 is provided on the upstream side of the second flow rate adjusting valve 17 of the second air supplying pipe 18. It is installed.
The membrane dryer 19 is for drying air, and is composed of a heater, an adsorbent, a filter, and the like. Dry air (dry air) through the membrane dryer 19 is used.
Are sprayed on both surfaces of the transmission window member 8 and the front surface of the corner cube mirror 1.

The second air supply pipe 18 and the first air supply pipe 13 are connected to an air supply pipe 20, and a flow rate adjusting valve 21 is provided in the air supply pipe 20. This flow rate control valve 21 (and the first and second control valves 12 and 17)
6, the opening degree is adjusted by the controller 22 as shown in FIG. The controller 22 is provided in the main body 23 of the gas concentration measuring device for measuring the distribution of the gas concentration outside the room where, for example, the vaporizer of the liquefied natural gas facility is installed. As shown in FIG. 6 and FIG. 7, the gas concentration measuring device uses a reflector such as a movable mirror unit 25 and a fixed mirror unit 26, which are provided with light from a light source 24 such as an optical transmitter, for example, a laser beam, at important points. To the monitored part 27,
Are arranged in a mesh shape in the direction to form the optical path 28 of the laser light in a plane. The gas concentration distribution in each of these optical paths 28 is measured, and the gas concentration distribution can be obtained in a planar manner by calculating these with a computer or other computer by a proportional distribution method. Can be measured quickly and accurately. The detector 39 converts the intensity of the received light of a specific wavelength into a current, and this output signal is output to a computer (not shown) via the amplifier 29.
The controller 22 has a function of obtaining the received light intensity from this output signal and adjusting the opening degree of the flow rate adjusting valve 21 and the first and second adjusting valves 12, 17 according to the received light intensity. Specifically, when the received light intensity is shown as a current value, the current value is about 100 mV when there is no raindrop attachment or dew condensation.
For example, when it becomes 50 mV or less, it is determined that raindrops are attached or dew is formed, the opening of the flow rate control valve 21 is opened, and air is supplied to the flat air nozzle 10 and dry air is supplied to the air nozzles 14, 15 and 16. Further, at the time of measurement, the flat air nozzle 10 and the air nozzles 14, 1 are always
It is also possible to supply air to 5 and 16 and increase the supply amount of air when the current value reaches a predetermined value (for example, 50 mV or less). Furthermore, when it is raining, air may be supplied to the flat air nozzle 10, and when there is a possibility that dew condensation may occur (in the next morning when it rained on the previous day in winter etc.), Air nozzle 14,15,1
You may make it supply dry air to 6.

Next, the operation of this embodiment will be described.

As shown in FIGS. 1 and 2, the mirror box 5 is provided with a transmission window 7 for incident light and emitted light, so that the corner cube mirror 1 does not interfere with its use. .

Since the corner cube mirror 1 is supported by the support pillars 2, and the support pillars 2 are covered with the heat insulating material 4 such as glass wool and are housed in the mirror box 5, the support pillars 2 are kept at the temperature of the outside air. Communication is blocked,
Even if the air temperature changes, a constant temperature can be maintained, and the local temperature rise of the support columns 2 due to direct sunlight is eliminated. As a result, deformation of the support column 2 due to thermal expansion is prevented, and the corner cube mirror 1 can always guide the laser beam in a target direction without being affected by changes in weather.

Further, since the hood 9 is attached to the mirror box 5, it becomes difficult for raindrops to adhere to the transmission window member 8. Further, since the flat air nozzle 10 is attached to the mirror box 5, by blowing air from the flat air nozzle 10 to form an air curtain, it is possible to more reliably prevent raindrops from adhering to the transmission window member 8 and to Since a part of the air forming the curtain collides with the transmission window member 8, the water droplets attached to the transmission window member 8 are blown off. For this, an air curtain was formed after spraying water droplets on the transmission window member. As a result,
The water droplets were blown off, and the received light intensity did not decrease. This prevents raindrops from entering the hood 9 even when a storm such as a typhoon prevents the raindrops from adhering to the transmissive window member 8 and even when water droplets adhere to the transmissive window member 8. Is blown away, the laser light can be satisfactorily reflected without being diffusely reflected in the case of rain.

Further, since the air nozzles 14, 15 and 16 are provided, it is possible to prevent dew condensation on the transmission window member 8 and the corner cube mirror 1. That is, by blowing dry air (dry air) through the membrane dryer 19 from the air nozzles 14, 15, 16 onto both surfaces of the transmission window member 8 and the front surface (reflection surface) of the corner cube mirror 1, the transmission window member 8 or the corner cube. Condensation on the mirror 1 is prevented. If there is condensation,
Condensation can be removed by purge air. For example, condensation was formed on the entire front surface of the mirror, and about 50 l / h of dry air was blown on the upper half of the mirror. As a result, it was found that the purged portion had dew condensation. When the dew condensation occurred on the mirror, the received light intensity decreased. Thereby, the dew condensation on the transmission window member 8 and the corner cube mirror 1 can be prevented, and even if the dew condensation occurs, the dew condensation can be removed and the laser light can be reflected well.

Therefore, the laser beam can be reflected well without being affected by weather changes, and the reliability of the gas concentration measuring device for measuring the distribution of the gas concentration outside the room where the vaporizer of the liquefied natural gas facility is installed. improves.

FIGS. 3 and 4 are views showing another embodiment, in which the reflecting mirror is a movable mirror. That is, in the movable mirror unit shown by 25 in FIG. 7, the same parts as those in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIGS. 3 and 4, the reflecting mirror is composed of two emitting mirrors 30 and a moving mirror 31, and the emitting mirror 30 is fixed above the inside of the mirror box 32 by a supporting rod 33 such as an iron rod. ing. The movable mirror 31 is attached via an air cylinder 35 to a support pillar 34 provided upright on the surface of the earth (or a fixed object on the surface of the earth), and the light from a light source such as an optical transmitter such as a laser is attached by the air cylinder 35. The light is moved to the reflection position and the non-reflection position (the position indicated by the alternate long and short dash line in FIG. 3) for reflecting the light on the emission mirror 30. The heat insulating material 36 is lined on the inner wall of the mirror box 32 so as to block the exchange of temperature with the outside air.

A transmission window 7 in which a transmission window member 8 is fitted is provided at the position of emission and incidence of laser light from the emission mirror 30 of the mirror box 32.

In the vicinity of the edge of the mirror box 32 forming the transmission window 7, a cylindrical eave having a diameter larger than that of the transmission window member 8 surrounding the transmission window member 8, that is, a hood 9 for protection from the rain is provided on the laser optical axis. Is installed along.

A flat air nozzle 10 for forming an air curtain in the hood 9 is attached to the hood 9, and a first air supply pipe 13 having a first control valve 12 is connected to the flat air nozzle 10.

Before and after the transmission window member 8 and in front of the emission mirror 30 and the movable mirror 31, both surfaces of the transmission window member 8 through which at least laser light is transmitted and reflected, and the front surfaces of the emission mirror 30 and the movable mirror 31 are covered with air. Air nozzles 14, 15, 37, 38 are provided as air spraying means for spraying. These air nozzles 14, 15, 37, 38 have
A second air supply pipe 18 having a second control valve 17 is connected, and a membrane dryer 19 is provided on the upstream side of the second flow control valve 17 of the second air supply pipe 18.

The second air supply pipe 18 and the first air supply pipe 13 are connected to an air supply pipe 20, and a flow rate adjusting valve 21 is provided in the air supply pipe 20. The opening degree of the flow rate adjusting valve 21 and the first and second adjusting valves 12 and 17 are adjusted by a controller 22.

Even with this structure, the same operational effects as those of the above-described embodiment can be obtained.

That is, since the heat insulating material 36 is lined on the inner wall of the mirror box 32, the support rod 33, the support pillar 34, and the air cylinder 35 are blocked from exchanging the temperature with the outside air, and the temperature changes. However, a constant temperature can be maintained, and local temperature rise due to direct sunlight is eliminated. Thereby, the emitting mirror 30 and the moving mirror 31 are
The laser beam can always be guided in a desired direction without being affected by changes in weather.

Moreover, since the hood 9 is attached to the mirror box 32, raindrops are less likely to adhere to the transmission window member 8. Further, since the flat air nozzle 10 is attached to the mirror box 32, by blowing air from the flat air nozzle 10 to form an air curtain, rain drops are less likely to adhere to the transmission window member 8 and at the same time, Since a part of the air forming the curtain collides with the transmission window member 8, the water droplets attached to the transmission window member 8 are blown off. This prevents raindrops from entering the hood 9 even when a storm such as a typhoon prevents the raindrops from adhering to the transmissive window member 8 and even when water droplets adhere to the transmissive window member 8. In the case of rain, the laser light can be satisfactorily reflected without irregular reflection of the light.

Further, the air nozzles 14, 15, 37, 3
8 is provided, the transmission window member 8, the exit mirror 30 and
The dew condensation on the movable mirror 31 can be prevented. That is, by blowing dry air (dry air) through the membrane dryer 19 from the air nozzles 14, 15, 37, and 38 to both surfaces of the transmission window member 8 and the front surfaces (reflection surfaces) of the emission mirror 30 and the movable mirror 31, the transmission window. Condensation on the member 8, the emission mirror 30, or the movable mirror 31 is prevented. If dew condensation has occurred, it can be removed by the purge air. This allows
The dew condensation on the transmissive window member 8, the emission mirror 30, and the movable mirror 31 can be prevented, and even if dew condensation occurs, the dew condensation can be removed and the laser light can be reflected well.

Therefore, the laser light can be reflected well without being affected by weather changes, and the reliability of the outdoor gas leak detection system in which the vaporizer of the liquefied natural gas facility is installed is improved.

[0040]

In summary, according to the present invention, the excellent effect that the laser light can be reflected well without being influenced by the change of weather is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing one embodiment of the present invention.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a perspective view showing another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing an example of an air nozzle and air blowing means of the present invention.

FIG. 6 is a configuration diagram for explaining a main body of a gas concentration measuring device.

FIG. 7 is a diagram showing an example of an optical path in the case of measuring a gas concentration two-dimensionally by a gas concentration measuring device.

[Explanation of symbols]

 1 Reflecting Mirror (Corner Cube Mirror) 2 Supporting Member (Supporting Pillar) 5 Casing (Mirror Box) 8 Transparent Window Member 9 Eaves (Hood) 10 Flat Air Nozzle

Front page continuation (72) Inventor Shigeki Mitani 3-3-22 Nakanoshima, Kita-ku, Osaka-shi, Osaka, Kansai Electric Power Co., Inc. Electric power company (72) Inventor Fumihiko Yamaguchi 3-2-16 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Toyosu General Office

Claims (3)

[Claims] 1. A device for supporting a reflecting mirror that reflects a laser beam for measurement, comprising: a supporting member for fixing the reflecting mirror at a predetermined position; and surrounding the supporting member and the reflecting mirror and on the laser optical axis. A casing having a transparent window member for transmitting the laser light, a cylindrical eaves attached to the casing and surrounding the transparent window member, and an air nozzle provided in the eaves and forming an air curtain in the eaves. A reflecting mirror support device characterized in that 2. A device for supporting a reflecting mirror that reflects a laser beam for measurement, comprising: a supporting member for fixing the reflecting mirror at a predetermined position; and surrounding the supporting member and the reflecting mirror and on the laser optical axis. A casing having a transparent window member for transmitting the laser beam, a cylindrical eaves attached to the casing and surrounding the transparent window member, and an air blowing unit for blowing air to the reflecting mirror and the transparent window member. A reflector support device characterized by the above. 3. A device for supporting a reflecting mirror that reflects a laser beam for measurement, comprising: a supporting member for fixing the reflecting mirror at a predetermined position; and surrounding the supporting member and the reflecting mirror and on the laser optical axis. A casing having a transparent window member that transmits laser light, a cylindrical eaves attached to the casing and surrounding the transparent window member, and an air nozzle that is provided in the eaves and forms an air curtain in the eaves, An apparatus for supporting a reflecting mirror, comprising: an air blowing unit for blowing air to the reflecting mirror and the transmission window member.