JPH085618A - Method and apparatus for detecting gas component in water - Google Patents

Abstract

PURPOSE:To detect a gas component in the water with high sensitivity by introducing a separated gas component in the water into a gas phase, adsorbing the gas component into an adsorbent and concentrating, and then heating a tube filled with the adsorbent thereby purging the gas component. CONSTITUTION:A supply gas is fed through a gas intake port 1 into a gas supply pipe 2. The gas component in the water passes through a gas permeation membrane 8 and enters into a gas permeation part 3. It is then carried, along with the supply gas, to a concentration part 5 through a return pipe 4. The concentration part 5 comprises a tube 9 filled with an adsorbent 11, and a heating part 10 disposed closely thereto, wherein the gas component in the water in the supply gas carried through the return pipe 4 is adsorbed by the adsorbent and concentrated. Upon concentration for a predetermined time, a heating part 10 is heated and the gas component is disorbed from the adsorbent 11 and detected at a detecting part 6. Since the gas component can be detected while being concentrated, high sensitivity detection is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater gas detection method and a detection apparatus for detecting leakage of oil or gas in water.

[0002]

2. Description of the Related Art Leakage is discovered as early as possible in order to minimize human injury and environmental pollution due to leakage of crude oil and natural gas at offshore bases for mining crude oil and natural gas and offshore pipelines. There is a need to. Conventionally, leaked crude oil and natural gas have been detected on the surface of the sea using various detection methods. However, these methods have a problem that when a leak occurs in the sea, it takes time to be detected, and it takes time to take measures because the leak location cannot be specified. Therefore, it is necessary to detect a leak in water at an early stage, and if a gas component in crude oil or natural gas can be detected in water, a leak can be detected at an early stage.

Conventionally, as a method for measuring a gas component in water, Japanese Patent Application Laid-Open No. 4-95752 proposes a method for measuring a dissolved gas component in a liquid using a gas permeable membrane. This measuring method will be described with reference to FIG. Gas inlet 1 on one side
However, the gas permeable part 3 to which the detection part 6 is connected on the other side is immersed in water, and the gas component in the water that has permeated the gas permeable film 8 and diffused into the gas phase inside the gas permeable part 3 is applied to the detection part 6. The gas component in water was detected by transporting and measuring.

[0004]

In the above-mentioned conventional method for detecting a gas component in water, if the gas component concentration is below the detection limit of the detector, it cannot be detected, and the detection sensitivity is determined by the ability of the detector. There was a problem of being lost. An object of the present invention is to solve the above problems and provide a highly sensitive method for detecting a gas component in water and a detection apparatus therefor.

[0005]

The first invention of the present invention is as follows:
The gas component in the water separated into the gas phase by the gas permeable membrane is introduced into the adsorbent-filled cylinder provided at the outlet side of the pipe that transports the gas phase and concentrated into the adsorbent, and after being concentrated for a certain time, the adsorbent The method for detecting a gas component in water is characterized in that the adsorbent filling cylinder is heated by a heating unit provided in the vicinity of the filling cylinder to expel the gas component concentrated in the adsorbent, and the gas component is introduced into the detection unit and detected.

A second invention comprises a gas intake port, an air supply pipe, a gas permeation part, a return pipe, a concentration part, a detection part and a pump for sucking a gas phase, and the gas permeation part has a gas permeable membrane, The gas components inside the gas permeation part, which are transported by the air supply pipe that supplies the gas taken in from the gas intake port to the gas permeation part and the return pipe that supplies the gas from the gas permeation part to the concentration part, via the concentration part. It is a device for detecting a gas component in water, which has a structure of being introduced into a detection unit for detection.

A third aspect of the present invention is characterized in that the concentrating section is composed of an adsorbent-filled cylinder and a heating section installed near the adsorbent-filled cylinder. It is a detection device.

A fourth aspect of the present invention has a bypass from the gas permeation part directly to the detection part in parallel with the concentration flow path from the gas permeation part to the detection part via the concentrating part, and the concentration flow path is provided by a switching valve. Alternatively, the underwater according to the second invention or the third invention is characterized in that it has a control section that is switched to one of the bypass flow paths and controls the switching valve and the concentrating section according to the output value of the detection section. It is a device for detecting a gas component.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of a device for detecting a gas component in water according to the present invention.

It comprises a gas intake 1, an air supply pipe 2, a gas permeation part 3, a return pipe 4, a concentrating part 5, a detecting part 6 and a pump 7. Insufflation gas is sent from the gas intake port 1 to the insufflation pipe 2. The air supply pipe 2 is installed in water, and the gas permeable part 3 is provided at an arbitrary position thereof. A return pipe 4 extends from the outlet side of the gas permeable portion 3, and the return pipe 4 is connected to a pump 7 via a concentrating portion 5 and a detecting portion 6. A gas permeable film 8 is provided on the gas permeable portion 3. The gas component in the water passes through the gas permeable membrane 8 and enters the gas permeable part 3, and is transported to the concentrating part 5 through the return pipe 4 together with the gas to be sent. FIG. 2 is an enlarged cross-sectional view of the concentration section 5. The concentrating unit 5 is composed of an adsorbent-filled cylinder 9 and a heating unit 10 installed in the vicinity thereof. The adsorbent filling cylinder 9 is filled with the adsorbent 11, and the water gas component in the gas fed through the return pipe 4 is adsorbed by the adsorbent 11 and concentrated. The gas component adsorbed and concentrated on the adsorbent 11 by heating the heating unit 10 after concentrating for a certain period of time is adsorbent 1
Detach from 1. The desorbed gas component is introduced into the detection unit 6 and detected.

Adsorbent filling cylinder 9 (inner diameter 16 mm × length 110)
mm) was filled with adsorbent 11 (50 ml), and the gas fed from the return pipe 4 was fed at a flow rate of 1 liter / min for 5 minutes. Then, the adsorbent-filled cylinder 9 was heated to 200 ° C., and the concentration of the desorbed water gas component was measured by the hydrocarbon gas detector (detection lower limit: 2 ppm) installed in the detection unit 6. When the gas fed from the return pipe 4 was directly introduced into the hydrocarbon gas detector as in the prior art, the concentration of the gas component in the water was below the lower limit of detection and could not be measured, but according to the present invention, 10
A measured value in ppm was obtained. Calculated gas component in water is 1
It is concentrated by a factor of 00 and, according to the present invention, 0.02 pp
The lower limit of detection of m is obtained. Further, the sensitivity can be further enhanced by lengthening the time for feeding the fed gas to the concentrating section.

FIG. 3 is a constitutional view showing a second embodiment of the apparatus for detecting a gas component in water of the present invention, and shows only the constitution corresponding to the portion from the return pipe 4 to the pump 7 of the apparatus of FIG. . In the second embodiment, a control unit 12, a bypass 13, a switching valve 14, and a connection 15 between the control unit and each unit are added to the device shown in FIG.

The bypass 13 is a flow path from the gas permeable section to the detection section directly without passing through the concentrating section, and is installed in parallel with the flow path passing through the concentrating section. The control unit 12 monitors the measurement value of the detection unit 6 and controls the switching valve 14 and the concentration unit 5.

Normally, the gas supplied from the return pipe 4 is introduced directly into the detection section 6 through the bypass 13. The measurement value of the detection unit 6 is constantly monitored by the control unit 12, and if the measurement value is equal to or less than a preset value, the flow path is switched by the switching valve 14, and the gas to be fed is concentrated in the concentration unit. It is sent to 5. Then, after the air-gas concentration for a certain period of time, the water gas component concentrated in the adsorbent 11 is introduced into the detection unit 6 by heating and desorption, and the concentration is measured. Further, when the concentration of the concentrated gas is equal to or higher than the set value, the flow path is switched by the switching valve 14 and the air supply gas is sent to the bypass 13 side.

When a high-concentration water gas component is introduced into the concentrating section 5, not only an abnormal measurement occurs, but also a so-called memory phenomenon occurs in which the concentrated gas component remains in the adsorbent 11 and normal measurement cannot be performed. However, according to the apparatus of the present invention, these problems do not occur if the gas fed from the return pipe 4 is fed to the concentrating section 5 only when the gas component concentration in water is low. In addition, real-time measurement is difficult when supplying air to the concentrating unit 5, but real-time measurement can be performed when supplying air to the bypass 13 side.

[0017]

As described above, according to the method for detecting a gas component in water and the apparatus therefor according to the present invention, the gas component can be concentrated and detected, so that highly sensitive detection can be performed. Also,
Real-time measurement is also possible by switching the flow path to the concentration section or bypass.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a device for detecting a gas component in water according to the present invention.

FIG. 2 is a structural cross-sectional view showing one embodiment of the concentrating section of the detection device of the present invention.

FIG. 3 is a configuration diagram showing a second embodiment of the apparatus for detecting a gas component in water according to the present invention.

FIG. 4 is a configuration diagram for explaining a conventional technique.

[Explanation of symbols]

 1 Gas Intake Port 2 Gas Pipe 3 Gas Permeation Part 4 Return Pipe 5 Concentration Part 6 Detecting Part 7 Pump 8 Gas Permeation Membrane 9 Adsorbent Filling Tube 10 Heating Part 11 Adsorbent 12 Control Part 13 Bypass 14 Switching Valve 15 Wiring

Claims (4)

[Claims] 1. A gas component in water separated into a gas phase by a gas permeable membrane is introduced into an adsorbent-filled cylinder provided on the outlet side of a pipe for transporting the gas phase to be condensed into an adsorbent, and then kept constant. After the time-concentration, the adsorbent-filled cylinder is heated by a heating unit provided in the vicinity of the adsorbent-filled cylinder to expel the gas component concentrated in the adsorbent, and the gas component is introduced into a detection unit for detection. Method of detecting gas components in water. 2. A gas intake port, an air supply pipe, a gas permeation part, a return pipe, a concentrating part, a detection part, and a pump for sucking a gas phase, the gas permeation part having a gas permeable membrane, and the gas intake part. The gas component inside the gas permeation part transported by the air supply pipe for supplying the gas taken in from the mouth to the gas permeation part and the return pipe for supplying the gas from the gas permeation part to the concentration part is condensed. An apparatus for detecting a gas component in water, which has a structure for introducing the gas into the detection section to detect the gas component. 3. The apparatus for detecting a gas component in water according to claim 2, wherein the concentrating section includes an adsorbent-filled cylinder and a heating section installed near the adsorbent-filled cylinder. 4. A concentrating flow path from the gas permeation section to the detection section is provided in parallel with a concentrating flow path from the gas permeation section to the detection section via the concentrating section, and the concentration flow is controlled by a switching valve. 4. A control unit that is switched to either a flow path or the bypass and has a control unit that controls the switching valve and the concentrating unit according to an output value of the detection unit. Device for detecting gas components in water.