JPH0719985A - Gas leak monitoring device - Google Patents

Abstract

(57) [Abstract] [Purpose] A small and inexpensive gas flux and its direction can be determined by measuring the wind speed from a breeze to a strong wind and the concentration of leaked gas in the air spatially and temporally in agreement. (EN) Provided is an outdoor gas leakage monitoring device which can be detected with high accuracy and which can be easily made into an explosion-proof structure if necessary. [Structure] A plurality of partition walls radially arranged in a horizontal direction between a top plate and a bottom plate define a converging wind passage from an open outer peripheral portion to a central portion, and thus outdoor raindrops, fog, and dust are provided. It is possible to measure the wind speed from a light breeze to a strong wind in a state of being accelerated, and moreover, the wind direction can be correctly grasped. At the same time, since the concentration of the leaked substance in the air can be measured at the same position with good responsiveness, the magnitude of the gas flux can be detected with responsiveness and accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention mainly relates to combustible gas,
In various outdoor plants that may leak gas such as toxic gas, various oils, and vapors of organic solvents, by measuring the leaked gas concentration in the air, the wind direction, and the wind speed in a spatially and temporally consistent manner, Not only the local leak gas concentration but also the leak gas gas flux that is an indicator of the size of the leak (leak gas concentration x wind speed: the amount of leak gas flowing per unit time and unit area, referred to below as the gas flux) And gas leakage monitoring to obtain the direction and direction.

[0002]

2. Description of the Related Art Conventionally, wind direction and wind speed in various outdoor plants have been observed by a wind direction and anemometer for weather observation which is usually installed high on the roof of an instrument room. However, when trying to detect a leak of gas using a gas detector, it is necessary to know the local wind speed at the detection location in order to know the scale of the leak. Needs to know the wind direction. Recently, small, inexpensive sensors such as semiconductor type, thermistor type, resistance thermometer, etc. have become widespread with respect to wind direction and wind speed.Both of them measure wind direction and wind speed from heat loss from the sensor due to wind. When raindrops, fog, and dust come into contact with each other, a large error occurs, which makes it unusable for outdoor use. For this reason, conventionally, a gas detector is installed alone, and it is not possible to measure the wind direction wind speed and the leakage gas concentration at the same position, that is, the size of the gas flux, which is an index of the size of the leakage, is measured. It could not be detected, and highly accurate gas leakage monitoring could not be performed.

Further, since the conventional gas detector dislikes raindrops, fog, and dust, the raindrop cover is used to avoid rain. However, when the wind speed is low, it takes a long time to replace the wind in the raindrop cover, so that a detection response is obtained. It took a long time.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art as described above, and its main purpose is to reduce the size and cost, wind direction wind speed from a breeze to a strong wind, and air. An outdoor gas that can detect the gas flux and its direction with high responsiveness and accuracy by measuring the leaked gas concentration in the space and time in a consistent manner. To provide a leakage monitoring device.

[0005]

According to the present invention, the above-described object is to provide a top plate and a bottom plate which are vertically separated from each other and a space defined between the top plate and the bottom plate, and between the top plate and the bottom plate. A plurality of partition walls extending over and radially outward from the outer side of the radial center of the empty chamber in a radial pattern at equal angular intervals and a predetermined length, and the central portion of the empty space. It is achieved by providing a gas leakage monitoring device characterized in that it has a wind direction and wind speed sensor provided in the air conditioner and a gas sensor provided in the center of the chamber.

[0006]

A plurality of partition walls radially arranged between the top plate and the bottom plate define a converging wind passage from the open outer peripheral portion to the central portion, and various wind speed sensors and gas sensors are disposed in the central portion. By positioning it and measuring the wind direction of the wind mixed with raindrops, fog and dust, the wind speed and the leak gas concentration in the air at spatially and temporally coincident points,
The wind speed can be measured in an accelerated state, and the wind direction and leak gas concentration can be accurately grasped. In particular, by narrowing the distance between the top plate and the bottom plate toward the central portion in the radial direction, it is possible to further accelerate the wind speed. Further, by providing the annular air filter on the outer peripheral portion of the gas leakage monitoring device, even in a harsh environment, the sensitivity of the wind direction sensor and the gas sensor does not deteriorate.

Leakage monitoring of these various leaked gases has been conventionally performed by humans frequently to circulate around the equipment machine in order to prevent accidents and disasters and to manage equipment, which is useful from the viewpoint of labor saving. Is.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 shows a vertical sectional view of a first embodiment of a gas leakage monitoring apparatus to which the present invention is applied, and FIG. 2 shows a transverse sectional view thereof. This gas leakage monitoring device has a top plate 1 and a bottom plate 2 which are two circular plates facing each other and defining a substantially cylindrical empty space 3 facing each other. The top plate 1 and the bottom plate 2 are gradually recessed in a direction toward each other toward their central portions, so that the vacant chamber 3 has an outer peripheral portion 3a having a wide vertical width and an intermediate portion 3b having a narrow vertical width. , The central portion 3c having a narrow vertical width. Here, the central part diameter of the top plate 1 and the bottom plate 2 and the vertical distance between them are set to 2 cm. The inclination of the top plate 1 and the bottom plate 2 in the middle portion 3b is about 27 degrees.

Between the top plate 1 and the bottom plate 2, the intermediate portion 3 is provided.
Eight partition walls 4 extend radially from b to the outer peripheral portion 3a to the outer peripheries of the top plate 1 and the bottom plate 2 at equal angular intervals to define the vacant chamber 3 in passages 5 in eight directions. An air filter 7 for preventing raindrops, fog, and dust from entering the inside is provided in the outer peripheral portion 3a of each passage 5. Here, the approximate dimensions of the air filter 7 are the outer diameter 10
A filter having a cm, a height of 4 cm, a filter thickness of 2 cm, and a porosity of 95% made of stainless fine wire was used. Also,
The ratio obtained by dividing the area of the outer peripheral surface of the air filter 7 by the area of the mouth on the inner peripheral side of the passage 5 is 10, which is equal to the reciprocal of the wind speed ratio at those points.

On the other hand, a hot wire semiconductor type gas sensor 9 held inside a holder 8 made of a pipe having a diameter of about 20 mm is arranged above the central position of the central portion 3c in the chamber 3. A metal wire net 10 for protection is provided on the surface of the holder 8. Actually, the gas sensor 9 is a contact combustion type, a semiconductor type, a hot wire type semiconductor type, a gas heat conduction type, an AET.
Any sensor such as a formula may be used. The holder 8 is fixed to the bottom plate 2 in an airtight manner by a mounting member 11 and a packing 12.

A two-dimensional semiconductor flow sensor 14, which is held by a holder 13 made of a pipe having a diameter of about 14 mm so that only the sensing surface is exposed, is arranged below the center of the central portion 3c in the chamber 3. ing. This flow sensor 1
Reference numeral 4 is a sensor capable of measuring not only the wind speed but also the wind direction over 360 degrees, that is, two-dimensionally.

Here, it is desirable that both sensors 9 and 14 are easily attached and detached together with their holders to facilitate maintenance.

Such a gas leakage monitoring device is equipped with a mounting bracket 1
The top plate 1, the bottom plate 2, and the sensor 14 are attached to the attached member 17 by means of 5 and the packing 16 such that the top plate 1, the bottom plate 2, and the sensor 14 are horizontal, and the attached member 17 is airtight. The wirings 18 and 19 of the gas sensor 9 and the flow sensor 14 are connected to an external management device (not shown). Here, each sensor 9, 14 and each wiring 18, 19 have an intrinsically safe explosion-proof structure by a low power consumption design.

In the present embodiment, the angle is 360 degrees, that is, 2 degrees.
Although a dimensionally measurable flow sensor was used, at least two one-dimensional flow sensors having different detection directions were used, and the wind speed detected by each sensor was vector-synthesized to function as a 360-degree two-dimensional sensor. You may let me. When an omnidirectional wind speed sensor is used, the velocity of air flowing toward the center of the anemometer through the passages defined by equally spaced partition walls is measured at the inner port of each passage, and It is also possible to scan the flow velocity output signal to determine the wind direction, and measure the total flow velocity of air at the center to determine the wind velocity. The air filter 7 is not only a metal mesh,
Fibers such as glass and polymers, thin wires, nets, films, etc. stacked, fine particles fused to each other, molded by adhering, etc. Porous, capable of efficiently removing raindrops, fog and dust in the air The air filter 7 may be configured to have different porosities, materials, etc. from the outside to the inside, or may be pleated to increase the air passage area. Also, when using in a place where there is a lot of fog that is difficult to remove with a normal air filter, place a thin wire, mesh, or membrane of energizing heat generation consisting of self-regulating heat generating elements inside the air filter, and if necessary, this It is also possible to turn off the fog by heating the air containing the fog by energizing the.

When the relationship between the outside air wind speed of this gas leakage monitoring device and the wind speed measured by the above-mentioned sensor was obtained by approximate calculation, the outside air wind speeds were 30 (cm / s) and 300 (c).
m / s), 1500 (cm / s) sensor measurement wind speed is 7 (cm / s), 260 (cm / s), 1740
(Cm / s).

As described above, it is possible to accurately measure a low wind speed and to accurately measure a leak gas concentration at the same position even though a wind resistor such as an air filter is used. It was

In the above embodiment, the ratio obtained by dividing the area of the outer peripheral surface of the air filter 7 by the area of the mouth on the inner peripheral side of the passage 5 is equal to the reciprocal of the wind speed ratio at those points. 3 ~
30 and preferably 5 to 15. Although the number of partition walls 4 depends on the accuracy of the wind direction to be measured, it is usually 4 directions or more, and preferably 8 to 16 directions.
It goes without saying that one, eight, and sixteen partition walls 4 are required. At this time, when the density of the air filter is high and thin, the partition wall 4 does not extend to the outer peripheral surface of the air filter 7 and does not significantly affect the wind direction distribution even to the inner peripheral surface. On the contrary, when the density of the air filter 7 is low, the air filter 7 may be filled up to the vicinity of the inner port of the passage 5.
It is desirable to stop the position occupied by the air filter 7 at a position that does not exceed the re-scattering flow velocity of the collected raindrops, fog and dust. This re-entrainment flow velocity is wind speed of 20 m / s
It is desirable to set it to 5 m / s or less even in such a strong wind.

FIG. 3 is a perspective view showing a main part of a gas leakage monitoring apparatus according to the second embodiment of the present invention. This gas leakage monitoring device has a top plate and a bottom plate composed of two circular plates that face each other with a space above and below and define a cylindrical vacant chamber in the center, and are radiated from the outside of the vacant chamber in the center. Has eight partition walls extending outward in the radial direction to the outer circumferences of the two circular plates at equal angular intervals. The specific structure is similar to that of the first embodiment, but in this embodiment, the top plate and the bottom plate are parallel to each other and no air filter is provided. A gas sensor similar to that of the first embodiment and the mechanical wind direction and air velocity sensor shown in FIG. 3 are housed in the cylindrical vacant chamber at the center. Here, reference numeral 21 indicates a plate-shaped wind direction sensor that freely rotates in the direction of the wind, reference numeral 22 indicates a windmill-type wind speed sensor that rotates in one direction, and these rotation axes are coaxial double. Since the wind speed is accelerated in this central part, it is possible to measure even in a slight breeze. Needless to say, these mechanical wind speed sensors are supported so as not to interfere with the gas sensor.

[0020]

As is apparent from the above description, according to the gas leakage monitoring apparatus of the present invention, a plurality of partition walls radially arranged in the horizontal direction between the top plate and the bottom plate allow the center to be opened from the opened outer peripheral portion. Since the converging wind passage to the section is defined, it is possible to measure the wind speed from a light wind including strong rain drops, fog, and dust to strong wind, and also to accurately grasp the wind direction. . At the same time, the leak gas concentration in the air can be measured at the same position with good responsiveness, so that the gas flux and its direction can be detected with responsiveness and accuracy.

[Brief description of drawings]

FIG. 1 is a simplified front view of a gas leakage monitoring device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a perspective view showing a main part of a gas leakage monitoring device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Top Plate 2 Bottom Plate 3 Vacancy 3a Outer Part 3b Middle Part 3c Central Part 4 Partition 5 Passage 7 Air Filter 8 Holder 9 Hot Wire Semiconductor Gas Sensor 10 Wire Mesh 11 Mounting Bracket 12 Packing 13 Holder 14 Two-Dimensional Semiconductor Flow Sensor 15 Mounting Bracket 16 Packing 17 Attached member 18, 19 Wiring 21 Wind direction sensor 22 Wind speed sensor

Claims (1)

[Claims] 1. A top plate and a bottom plate which are vertically separated from each other, and a space defined by the top plate and the bottom plate, extending in the space between the top plate and the bottom plate, and a radial center of the space. A plurality of partition walls that extend radially outward from the outer side of the portion at equal angular intervals and a predetermined length, a wind direction wind velocity sensor provided in the center of the chamber, and the center of the chamber. And a gas sensor provided in the gas leak monitoring device.