Marine gas detection device and gas detection method

Abstract

We provide laser-based gas detection technology applicable to ships. [Solution] In a corner of a garage (100) on a ship, a laser beam (LB) with a wavelength absorbed by carbon monoxide gas is irradiated, reflected by a reflector 103, the scattered light (SL) of the laser beam (LB) is received by a light receiving unit, and information regarding the detection of the target gas component is output by a control unit (13) by referring to a signal of the amount of the target gas component obtained according to the intensity signal of the received light.

Description

Technical Field

[0001] The present invention relates to a gas detection device and a gas detection method for ships.

Background Art

[0002] Conventionally, as a technique for detecting a fire by a fire alarm device, a technique of detecting a fire by irradiating and receiving laser light is known. Among them, as a technique applicable to ships, laser light irradiated from a light source device is received by a light receiving device optically opposed to the light source device across a detection area, and attenuation of the laser light due to fire or smoke in the detection area is detected, and an alarm is issued based on the detection result (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the other hand, a large force is applied to a ship during navigation, causing deflection. Therefore, when the above conventional technology is applied to a ship, the optical axis may be displaced between the light source device and the light receiving device due to the deflection, and the laser light irradiated from the light source device may not be detected by the light receiving device, making it difficult to detect a fire. Thus, there remains room for consideration of the conventional technology from the viewpoint of applying the detection technology using laser light to ships.

[0005] One aspect of the present invention aims to provide a gas detection technology using laser light applicable to ships.

Means for Solving the Problems

[0006] To solve the above problems, a ship gas detection device according to one aspect of the present invention is a ship gas detection device installed on a ship, comprising: an irradiation unit that irradiates the atmosphere of the ship with laser light of a wavelength absorbed by the gas component to be monitored; a light receiving unit that receives the laser light or reflected light irradiated from the irradiation unit onto the atmosphere; a control unit that outputs information regarding the detection of the gas component to be monitored by referring to a signal of the amount of the gas component to be monitored, which is acquired according to the signal of the intensity of the light received by the light receiving unit; and a reflection intensity change reduction unit that reduces the amount of change in the signal of the intensity of the received light due to the bending of the ship.

[0007] Furthermore, in order to solve the above problems, a gas detection method according to one aspect of the present invention is a method for detecting gas in a ship, comprising the steps of: irradiating the atmosphere of the ship from an irradiation unit with laser light of a wavelength absorbed by the gas component to be monitored; receiving the laser light or its reflected light irradiated onto the atmosphere from the irradiation unit with a light receiving unit; and in a control unit, acquiring a signal of the amount of the gas component to be monitored according to the signal of the intensity of the reflected light received by the light receiving unit, and outputting information regarding the detection of the gas component to be monitored by referring to the acquired signal of the amount of the gas component to be monitored, further comprising the step of reducing the amount of change in the signal of the intensity of the reflected light due to the bending of the ship with a reflection intensity change reduction unit. [Effects of the Invention]

[0008] According to one aspect of the present invention, a gas detection technology using laser light applicable to ships can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] This figure schematically shows a plan view of a first example to which the gas detection device according to Embodiment 1 of the present invention is applied. [Figure 2] This figure schematically shows a front view of a first example to which the gas detection device according to Embodiment 1 of the present invention is applied. [Figure 3] This figure schematically shows the configuration of a gas detection device according to Embodiment 1 of the present invention. [Figure 4] This is a block diagram showing an example of a functional configuration related to gas detection in the control unit in Embodiment 1 of the present invention. [Figure 5] This flowchart shows an example of the process flow in a gas detection method according to Embodiment 1 of the present invention. [Figure 6] This figure schematically illustrates an example of the temporal behavior of the column density detected in Embodiment 1 of the present invention. [Figure 7] This figure schematically illustrates another example of the temporal behavior of the column density detected in Embodiment 1 of the present invention. [Figure 8] This figure schematically shows a second example in which the gas detection device according to Embodiment 1 of the present invention is applied, viewed from a planar perspective. [Figure 9] This figure schematically shows a third example in which the gas detection device according to Embodiment 1 of the present invention is applied, viewed from above. [Figure 10] This figure schematically illustrates an example of the application of a gas detection device according to Embodiment 3 of the present invention. [Figure 11] Figure 10 is a schematic diagram showing a cross-section of the main part in the application example. [Figure 12] This figure shows an enlarged view of the main parts of the application example shown in Figure 10. [Modes for carrying out the invention]

[0010] [Embodiment 1] Embodiment 1 of the present invention will be described based on an application example in a ship's garage. The garage 100 is a garage on a ship such as a car carrier or ferry. The garage 100 is a closed space having a rectangular floor 101 and ceiling, and partitioned on all four sides by bulkheads 102. The longitudinal distance of the garage 100 is about 100m. Multiple automobiles 110 are accommodated in the garage 100.

[0011] The gas detection device 1 is arranged such that laser light passes around the vehicle 110, for example, above or below the vehicle body of the vehicle 110 or between vehicle bodies. In this embodiment, the gas detection device 1 is arranged on one side of the garage 100. The gas detection device 1 is arranged at a corner of the garage 100, facing the reflector 103 arranged on the other partition wall 102 with one partition wall at its back. The laser light LB is irradiated from one end side to the reflector 103 on the other end side of the garage 100 along the partition wall on one side of the garage 100 at a height close to the floor surface. Also, the gas detection device 1 is configured such that a signal from the gas detection device 1 is transmitted to the monitoring and control PC 130 in a separate room of the ship. The monitoring and control PC 130 is constantly monitored by a monitor.

[0012] [Gas Detection Device] The configuration of the gas detection device according to an embodiment of the present invention is schematically shown in FIG. 3. As shown in FIG. 3, the gas detection device 1 has an irradiation unit 11, a light receiving unit 12, and a control unit 13. Also, as described above, the gas detection device 1 has a reflector 103 arranged at a position facing it.

[0013] [Irradiation Unit] The irradiation unit 11 is a device that irradiates laser light LB of a specific wavelength. The irradiation unit 11 includes, for example, an output adjustment unit 111 and a laser diode 112.

[0014] The wavelength of the laser light LB irradiated by the irradiation unit 11 is a wavelength absorbed by the gas component to be monitored. Therefore, the wavelength of the laser light LB is determined according to the type of the "gas component to be monitored" that is the detection target.

[0015] The "gas component to be monitored" can be appropriately determined according to the use of the gas detection device 1. For example, if the use of the gas detection device 1 is to detect gas leakage, the gas component to be monitored can be the gas of the cargo on the ship or the gas used in the ship's equipment. Also, if the use of the gas detection device 1 is to monitor the state of the object to be monitored, the gas component to be monitored can be the outgas from the object to be monitored or the gas component generated along with the change (such as temperature rise, oxidation or combustion) of the object to be monitored (vaporized matter, decomposed matter or PM, etc. of the material of the object to be monitored due to heat). Examples of the "gas component to be monitored" include liquefied natural gas, ammonia gas, carbon monoxide gas, particulate matter and butane gas.

[0016] In this embodiment, the use of the gas detection device 1 is early warning of fire, the gas component to be monitored is carbon monoxide gas which is the gas generated when an object burns, and the information regarding the detection of the gas component to be monitored to be output is used as a fire warning signal. In this embodiment, the wavelength of the laser beam LB irradiated by the irradiation unit 11 is 1.6 μm.

[0017] The laser beam LB is irradiated onto the atmosphere of the ship. The "atmosphere of the ship" is the gas that exists around the ship and can be a measurement target on the ship. For example, the atmosphere of the ship can be the air around the cargo on the ship (for example, the air within a distance of 1 m from the surface of the cargo), or the air around the ship's equipment. The laser beam LB may be irradiated onto the generation location of the atmosphere, or may be irradiated onto the atmosphere at a specific position that has flowed from the generation location and is away from the generation location. In this embodiment, the laser beam LB is irradiated onto the space that is likely to be the flow path of carbon monoxide flowing from the generation location.

[0018] [Light receiving unit] The light-receiving unit 12 is a device that receives light SL from the atmosphere irradiated with laser light LB. Examples of light SL from the atmosphere include the laser light LB that has passed through the atmosphere, its reflected light, and its diffusely reflected light. The light-receiving unit 12 is a device that generates a signal corresponding to the intensity of the received light. An example of the light-receiving unit 12 is a photodiode (PD). It is preferable for the light-receiving unit 12 to receive reflected light of the laser light LB irradiated into the atmosphere from the irradiation unit 11, from the viewpoint of detecting light SL from the atmosphere with a simple configuration.

[0019] [Control Unit] The control unit 13 has the function of outputting a fire warning signal as information related to the detection of the monitored gas component by referring to the detection signal of light received by the light receiving unit 12. A block diagram of an example of the functional configuration of the control unit 13 related to gas detection is shown in Figure 4. As shown in Figure 4, for example, the control unit 13 includes a column density acquisition unit 131, a column density increase amount acquisition unit 132, a column density increase amount determination unit 133, and a warning signal output unit 134.

[0020] The column density acquisition unit 131 acquires the column density of the target gas component in accordance with the signal detected by the light receiving unit 12. When the target gas component is present in the atmosphere, the laser beam LB is partially absorbed by the target gas component in its optical path and is received by the light receiving unit 12 due to diffuse reflection, etc. Therefore, the unit of the measured value of the target gas component acquired by the gas detection device 1 is column density (concentration × distance (e.g., ppm·m)).

[0021] The column density increase acquisition unit 132 acquires the column density increase amount by referring to the column density of the monitored gas component acquired by the column density acquisition unit 131. The "column density increase amount" is the column density of the gas component. This quantity represents the degree of increase in column density over time. Examples of "column density increase" include the value of the increase in column density of the monitored gas component per unit time (i.e., the rate of change (slope) of column density), and the time integral of column density. When time is "t" and the column density increase is "Rco", the former is expressed as the ratio of the change in column density (d column density) to the increase in time (dt), as shown in equation (1) below, and the latter is expressed in equation (2) below.

[0022]

number

[0023] The column density increase determination unit 133 determines whether the column density increase exceeds the reference value by referring to the column density increase acquired by the column density increase acquisition unit 132 and its reference value. In this embodiment, the "reference value" may be a value that indicates that the column density of the monitored gas component acquired in response to the signal of the intensity of light SL from the aforementioned atmosphere received by the light receiving unit 12 has increased from the normal column density of the monitored gas component in that atmosphere. In this case, the reference value is a value greater than the normal column density increase of the monitored gas component in the aforementioned atmosphere. "Normal time" refers to times other than during combustion of the monitored object and the preceding stages such as temperature rise or incomplete combustion. The normal column density increase may be a predetermined value, a column density increase acquired by normal measurement (normal measurement value), or a calculated value obtained by computer simulation.

[0024] In this embodiment, the "reference value" can be appropriately determined based on the type of gas component to be monitored, the fire risk of the object being monitored, and the degree of early fire warning. For example, if the gas component to be monitored is a gas that is only generated during the process leading to a fire, the reference value can be set lower. Also, even if the fire risk of the object being monitored is high, the reference value can be set lower from the standpoint of fire prevention. Furthermore, even if a high level of fire alert is set, the reference value can be set lower from the standpoint of fire prevention.

[0025] Furthermore, the "reference value" can be determined appropriately in addition to the above, depending on the type of column density increase. For example, if the column density increase is the rate of change in column density, the reference value will be the increase in column density per unit time of the monitored gas component that is greater than the normal increase in column density per unit time of the monitored gas component in the aforementioned atmosphere.

[0026] The column density of the target gas component to be detected increases with its generation. Therefore, the column density of the target gas component to be detected is essentially zero or a specific positive constant value under normal conditions, starts to increase when a fire occurs, and tends to increase significantly during a fire, and can be represented by such a curve (see Figure 6). Thus, by setting the slope between the slope of the column density under normal conditions and the slope of the column density during a fire as the reference value, it becomes possible to determine a state in which the target gas component is generated more than under normal conditions but has not yet reached a fire as a state requiring fire vigilance. Setting the reference value on the normal conditions side (smaller) at the rising part of this curve is preferable from the viewpoint of enabling earlier fire vigilance. On the other hand, setting the reference value on the fire conditions side (larger) is preferable from the viewpoint of suppressing the occurrence of false alarms and improving the reliability of the alarm signal. Therefore, the reference value should be set to a value where the column density of the target gas component is greater than the increase per unit time of the column density of the target gas component under normal conditions in the aforementioned atmosphere. Using the value of the increase per unit time is preferable from the standpoint of achieving earlier fire detection or from the standpoint of suppressing false alarms of fire warning signals.

[0027] Furthermore, if the increase in column density is the time integral of the column density, the reference value will be the time integral of the column density of the monitored gas component that is greater than the time integral of the column density of the monitored gas component under normal conditions in the aforementioned atmosphere.

[0028] Even when a monitored gas component is continuously being generated, if convection occurs in the ship's atmosphere, the generated monitored gas component is more easily dispersed from its source, and the column density of the monitored gas component may change irregularly in response to increases or decreases in its generation rate (see Figure 7). However, even if the increase or decrease in column density is irregular, if the amount of monitored gas component generated in a given time increases, the column density also tends to increase. Therefore, when changes in the column density of the monitored gas component are influenced by other factors, it is possible to achieve fire alert by using the cumulative value of the column density corresponding to the amount of monitored gas component generated in a given time that could potentially lead to a fire as a reference value, and determining whether the time integral of the actual column density of the monitored gas component exceeds this reference value. Therefore, setting the reference value to a time integral of the column density of the monitored gas component that is greater than the time integral of the column density of the monitored gas component under normal conditions in the aforementioned atmosphere is preferable from the viewpoint of achieving early fire alert even when the source of the monitored gas component is influenced by external factors.

[0029] The reference value can be set as appropriate by methods such as an experimental method based on the detected column density of the gas detection device 1 when a specific amount of the monitored gas component is supplied, or a calculation method based on the distribution prediction of the monitored gas component using computer simulation.

[0030] The warning signal output unit 134 outputs a warning signal indicating a fire warning in response to the determination by the column density increase determination unit 133 that the acquired column density increase exceeds the standard value. This signal is transmitted to the user, for example, by wireless communication, or notified to the surroundings as a visual or audible alarm.

[0031] Thus, the control unit 13 is configured to output a warning signal when the column density of the monitored gas component, acquired in response to the signal of the intensity of light SL from the aforementioned atmosphere received by the light receiving unit 12, exceeds the aforementioned reference value.

[0032] [Reflector] The reflector 103 is a plate-shaped member attached to the bulkhead 102 facing the gas detection device 1 in the garage 100. The reflector 103 is a member that diffusely reflects the laser beam LB. The reflector 103 also has a sufficient area of ​​about 1 meter square. It is known that ships flex when loaded with cargo or while underway. The reflector 103 extends to at least the range of the reach of the laser beam LB, which changes due to the flexing of the ship. In this way, the reflector 103 is configured so that the laser beam LB from the opposing gas detection device 1 reaches it regardless of whether the ship flexes or not, and diffuse reflection generates light SL, which is scattered light of the laser beam LB.

[0033] The deflection of the ship is determined by known measurement techniques for measuring hull deflection. The dimensions of the reflector 103 can be appropriately determined from the beam diameter of the laser beam LB, the distance to the gas detection device 1 at the time of installation, and the amount of ship deflection at the installation site.

[0034] [others] The gas detection device 1 further includes a focusing lens 14 that focuses light SL toward the light receiving unit 12. This further enhances the detection sensitivity of the light SL. In particular, in this embodiment, since the light SL is scattered light due to diffuse reflection by the reflector 103, the configuration in which the gas detection device 1 further has a condensing lens 14 is preferable from the viewpoint of sufficiently increasing the detection sensitivity of the light SL in the light receiving unit 12.

[0035] Furthermore, in addition to the fire alarm function described above, the control unit 13 also includes various functional configurations related to the output of alarm signals, such as a function to control the irradiation of laser light LB at the irradiation unit 11.

[0036] Furthermore, the control unit 13 may also include functions other than those described above, such as reference values, in addition to the gas detection function described above. For example, the column density increase amount and the reference value referenced by the control unit 13 may be values ​​other than the rate of change of column density and the time integral of column density. For example, the column density increase amount and the reference value may be the difference from the previous measurement of column density. If the reference value corresponding to this column density increase amount is set to a value that shows a sufficiently large difference over a specific sufficiently short time interval, it becomes possible to detect that a particular gas has increased remarkably rapidly in the atmosphere.

[0037] Furthermore, the column density increase acquisition unit 132 may acquire multiple types of column density increase amounts, and the column density increase determination unit 133 may refer to a reference value corresponding to each of the multiple types of column density increase amounts and determine whether each of the multiple types of column density increase amounts is greater than or equal to at least one of the reference values. Alternatively, the column density increase determination unit 133 may be configured to output a signal to the warning signal output unit 134 indicating that a warning signal should be output when it is determined that two or more of the multiple types of column density increase amounts exceed the reference value.

[0038] In determining detected values ​​based on such standard values, setting the standard values ​​more strictly can lead to safer determinations, while setting the standard values ​​more loosely can reduce false positives. Therefore, determination based on these standard values ​​is preferable from the viewpoint of obtaining appropriate determination results.

[0039] [Gas detection method] An example of a gas detection method using the gas detection device 1 in this embodiment will be described. An example of the process flow in this gas detection method is shown in the flowchart of Figure 5.

[0040] In step S11, the control unit 13 starts irradiating with laser light LB from the irradiation unit 11. For example, the control unit 13 transmits an information signal regarding the output of the laser light LB to be irradiated to the output adjustment unit 111. The output adjustment unit 111 adjusts the wavelength of the laser light to match the gas to be detected and also performs frequency modulation according to the acquired information signal. The laser diode 112 irradiates with the desired laser light LB according to the wavelength adjustment and frequency modulation by the output adjustment unit 111.

[0041] Next, in step S12, the gas detection device 1 receives the scattered light SL (light) that has been diffusely reflected by the reflector 103 of the laser light LB through the focusing lens 14. In this way, the gas detection device 1 begins to receive the light SL.

[0042] As described above, in the gas detection method according to this embodiment, a laser beam LB with a wavelength of 1.6 μm, which is absorbed by carbon monoxide gas, the gas to be monitored, is used to irradiate the atmosphere of a specific area in the garage 100 from the irradiation unit 11. The light beam is diffusely reflected by the reflector plate 103, and the light SL from the atmosphere irradiated by the laser beam LB is received by the light receiving unit 12.

[0043] Next, in step S13, the column density acquisition unit 131 receives light S from the light receiving unit 12. In response to the detection signal of L, the column density (ppm·m) of the optical SL is acquired as a signal of the amount of the monitored gas component.

[0044] Next, in step S14, the column density increase acquisition unit 132 refers to the column density of the optical SL acquired by the column density acquisition unit 131 and acquires the column density increase amount of the optical SL, for example, the rate of change of the column density or the time integral value of the column density as described above.

[0045] Next, in step S15, the column density increase determination unit 133 refers to the column density increase amount of the optical SL obtained by the column density increase amount acquisition unit 132 and the corresponding reference value to determine whether the column density increase amount of the optical SL is greater than the reference value.

[0046] If the increase in the column density of the optical SL is greater than the reference value, in step S16, the warning signal output unit 134 outputs a warning signal as information regarding the detection of the monitored gas component.

[0047] In this gas detection method according to the present embodiment, the control unit 13 outputs a warning signal when the column density of carbon monoxide gas acquired in response to the signal detected by the light receiving unit 12 exceeds a reference value indicating an increase from the normal column density of carbon monoxide gas in the aforementioned atmosphere.

[0048] The emitted warning signal is displayed on the monitoring control PC130, which is monitored by the supervisor. The supervisor confirms that the situation warrants fire vigilance and takes preventative measures to prevent the fire.

[0049] On the other hand, if the increase in the column density of light SL is less than or equal to the reference value, the control unit 13 returns to step S11. In this way, the laser light LB is continuously irradiated into the garage 100, and the reflected light (light SL) is also continuously received, and steps S12 to S15 are repeated by the control unit 13.

[0050] In the gas detection method described above, light SL is generated by diffuse reflection of the laser beam LB by the reflector 103, and this light is received by the light receiving unit 12. As mentioned above, the reflector 103 has sufficient width, so the laser beam LB does not detach from the reflector 103 due to the bending of the ship. In addition, the reflector 103 generates scattered light of the laser beam LB. Therefore, even if the reflector 103 deviates from the gas detection device 1 due to the bending of the ship, the amount of light SL received by the light receiving unit 12 does not change, or the amount of change is very small. In this way, the reflector 103 is configured to reduce the amount of change in the signal intensity of light SL due to bending caused by the ship's navigation, and reflecting the laser beam LB with such a reflector 103 is a process in which the amount of change in the signal intensity of light SL due to bending caused by the ship's navigation is reduced by the reflector 103.

[0051] According to the gas detection method described above, it is possible to detect and warn of a fire originating from a vehicle 110 in the garage 100 at an early stage. For example, as shown in Figures 1 and 2, suppose one of the vehicles 110 housed in the garage 100 is an electric vehicle, and an abnormal reaction occurs in the lithium-ion battery installed in that electric vehicle. The heat generated by the lithium-ion battery heats the resin products or oil components of the vehicle 110, causing some of them to decompose and generate carbon monoxide gas. Although carbon monoxide is lighter than air, it flows due to the slight airflow generated by the heat generated by the lithium-ion battery, and diffuses while spreading low to the floor. Then, when it flows to the partition wall of the garage 100, it flows along the floor and the partition wall. The carbon monoxide gas 120 that diffuses and flows inside the garage 100 in this way crosses the optical path of the laser beam LB emitted by the gas detection device 1 and then flows along the optical path.

[0052] The gas detection device 1 detects carbon monoxide by column density (ppm·m). Therefore, even if the amount of carbon monoxide gas generated is small, or if the concentration of carbon monoxide gas in the garage 100 is very low, the carbon monoxide gas due to diffusion and flow will be detected by the gas detection device 1.

[0053] Figure 6 schematically shows the first example of the temporal behavior of the column density detected in the above case. As described above, when carbon monoxide generated in the garage 100 flows toward the optical path of the laser beam LB and then flows along that optical path, the opportunities for the laser beam LB to collide with carbon monoxide molecules increase. Therefore, as shown in Figure 6, the column density tends to follow a curve that clearly increases from a certain point. If the rate of change of the column density at the rise of this curve (for example, CD1 / t1 in the figure) is taken as the reference value, the generation of carbon monoxide in the garage 100 is detected in the initial stages of carbon monoxide generation.

[0054] When a warning signal is detected from the gas detection device 1, preventive measures are promptly taken to prevent the fire from spreading to other vehicles or vessels. As a result, a fire in an electric vehicle within a garage 100 where vehicles 110 are densely packed together can be prevented, and the fire may spread to other vehicles 110 or to a vessel.

[0055] In this way, the gas detection device 1 detects carbon monoxide gas, the target gas component, by column density. Therefore, it is possible to detect carbon monoxide gas in a wide area, such as the entire garage 100 that houses multiple cars 110, rather than individual cars 110, and furthermore, it is possible to detect it quickly even at low concentrations.

[0056] Furthermore, the gas detection device 1 determines the time-dependent increase in the column density of the monitored gas component and uses this to determine whether or not to output a fire warning signal. Therefore, the gas detection device 1 can detect the possibility of a fire occurring before it actually happens based on the gas detection results, and thus can be applied to early fire warning.

[0057] Furthermore, the gas detection device 1 has an irradiation unit 11 fixed in a position to irradiate the atmosphere with laser light LB, and a light receiving unit 12 fixed in a position to receive light SL, which is scattered light reflected by the reflector 103 from the laser light LB. As the gas detection device 1 has a simple configuration in which the irradiation unit 11 and the light receiving unit 12 are integrated, it is compact and therefore easy to place in a suitable location in the garage 100. Thus, the gas detection device 1 is advantageous in terms of its simplified configuration and high degree of freedom in installation.

[0058] [Differentiation] The laser beam LB of the gas detection device 1 is diffusely reflected when it is irradiated onto the reflector 103. However, if the bulkhead 102 of the garage 100 has a surface that sufficiently diffusely reflects the laser beam LB and generates scattered light SL that is substantially unaffected by the bending of the ship, then the bulkhead 102 can be used instead of the reflector 103 in a configuration that reduces the amount of change in the signal intensity of the reflected light due to bending caused by the ship's navigation.

[0059] Furthermore, although the reflector 103 is a reflective member that diffusely reflects the laser light LB, the reflective member may be a member capable of appropriately reflecting the irradiated laser light LB toward the gas detection device 1. For example, the reflective member may be a retroreflector. A retroreflector reflects the incident laser light LB in a direction parallel to and opposite to the direction of incidence. By appropriately setting the shape and dimensions of the reflective structure unit in the retroreflector, it is possible to make the reflected light of the laser light LB irradiated from the irradiation unit 11 reach the focusing lens 14. Since the retroreflector reflects the incident light in a direction parallel to the incident light regardless of the angle of incidence of the incident light, the reflected light of the laser light LB reaches the light receiving unit 12 regardless of whether or not the ship is bending. It is effective from the standpoint of allowing light to be received.

[0060] Furthermore, the increase in column density in the gas detection device 1 may be the cumulative value (time integral) of the column density over time. Another example of the temporal behavior of column density in this embodiment is schematically shown in Figure 7. For example, if the garage 100 is not a closed space, and part or all of its sides or the top is open, then air flows within the garage 100 at a certain range of wind velocities and in irregular directions. In such a case, the generated target gas component is affected by the flowing atmosphere inside the garage 100, and the opportunity for the laser beam LB of the gas detection device 1 to collide with carbon monoxide molecules also fluctuates. Therefore, as shown in Figure 7, the column density of the target gas detected by the gas detection device 1 tends to draw a curve that increases and decreases irregularly. If the value corresponding to the time integral of the column density (shaded area in the figure) at a certain time (t3 in the figure) from when the column density exceeds the normal level (t2 in the figure) is taken as the aforementioned reference value, then the generation of carbon monoxide in the garage 100 can be detected at the initial stage of generation, regardless of the flow of the atmosphere inside the garage 100.

[0061] Furthermore, as shown in Figure 8, two gas detection devices 1 may be installed in the garage 100 in a orientation where the optical paths of the laser beams LB they emit intersect each other. One device is positioned to emit the laser beam LB in the longitudinal direction of the garage 100, and the other device is positioned to emit the laser beam LB in the short direction of the garage 100. Such an arrangement of the gas detection devices 1 can increase the opportunities for detecting the target gas components and is preferable from the viewpoint of detecting the target gas components earlier compared to the application example shown in Figure 1.

[0062] Furthermore, as shown in Figure 9, four gas detection devices 1 may be installed in the garage 100 in positions and orientations that irradiate laser light LB along each of the partition walls. For example, each of the four gas detection devices 1 is located at one of the four corners of the garage 100. The first device is positioned to irradiate laser light LB along one side partition wall of the garage 100, the second device to irradiate laser light LB along one end partition wall, the third device to irradiate laser light LB along the other side partition wall of the garage 100, and the fourth device to irradiate laser light LB along the other end partition wall. Such an arrangement of gas detection devices 1 makes it possible to detect any target gas component that reaches any partition wall of the garage 100 due to the aforementioned diffusion flow along the floor surface, which is specific to the target gas component. Therefore, such an arrangement of gas detection devices 1 is preferable to the application example shown in Figure 1 in terms of detecting the target gas component earlier and more reliably.

[0063] Furthermore, the amount of change in the signal intensity of reflected light due to the deflection of the ship in the gas detection device 1 may be reduced by control. For example, the control unit 13 may further include a correction signal generation unit that, by referring to information regarding the deflection of the ship, generates a correction signal that cancels out the change in the signal intensity of the light SL received by the light receiving unit 12 due to the deflection of the ship.

[0064] Information regarding the deflection of a ship may be, for example, a set value in the ship's design, or it may be obtained from the detection signal of a measuring device such as a known laser-type optical deflection meter. Furthermore, for example, a correction signal can be determined from a correction amount of the light reception intensity of the light SL corresponding to the amount of deflection of the ship, based on a pre-acquired correlation between the amount of deflection of the ship and the change in the light reception intensity of the light SL.

[0065] The control unit 13 then further references the correction signal and outputs information (warning signal) regarding the detection of the monitored gas component. For example, the control unit 13 references the correction signal when acquiring the column density in step S13 and acquires the column density for which the correction signal was referenced. Alternatively, the control unit 13 further includes a functional configuration that corrects the reference value by referring to the correction signal, and in step S15, it references the reference value corrected according to the correction signal and checks if the reference value has not been corrected. It determines whether the increase in column density is greater than a standard value. This configuration is effective from the viewpoint of simplifying and miniaturizing the gas detection device 1.

[0066] Furthermore, the amount of change in the signal intensity of reflected light due to the deflection of the ship in the gas detection device 1 may be reduced by adjusting the optical axis of the irradiating laser beam LB. For example, the irradiation unit 11 of the gas detection device 1 further includes a fine steering mirror in its optical system for adjusting the optical axis of the irradiating laser beam LB, and the control unit 13 drives the fine steering mirror so that the laser beam LB is irradiated to a position where light SL on the reflector 103 or bulkhead 102 is received by the light receiving unit 12, according to the amount of deflection of the ship. This configuration is advantageous from the viewpoint of increasing the flexibility of the installation of the gas detection device 1, as it makes it possible to irradiate the laser beam LB according to the part that reflects the laser beam LB. In addition, in this configuration, a reflective member with high reflectivity may be applied, which is further advantageous from the viewpoint of increasing the intensity of the received light SL and improving the accuracy of gas detection.

[0067] The garage 100 described in this embodiment is an example of a location on a ship where the risk increases when an abnormality occurs in an electric vehicle stored there. Since the gas detection device 1 can detect gas leaks early, it may be placed in an explosion-proof area on the ship, and the gas detection device 1 may be configured to be explosion-proof for such use. For example, the gas detection device 1 may be configured to be used while housed in an explosion-proof casing. Alternatively, the gas detection device 1 may further have a configuration that limits the energy of the laser beam LB so as not to become an ignition source for the surrounding explosive atmosphere.

[0068] Furthermore, the gas detection device 1 may be placed not inside the garage 100, but inside the exhaust pipe from the garage 100, or inside a sampling pipe used to collect atmospheric samples at any point in the garage 100. For example, the gas detection device 1 may be positioned inside the exhaust pipe or sampling pipe to irradiate the laser beam LB along the longitudinal direction of the exhaust pipe or sampling pipe. Even in this configuration, it is possible to detect the generation of the target gas component inside the garage 100 at an early stage.

[0069] Furthermore, the garage 100 may be equipped with baffles that rise from the floor and extend diagonally to the partition wall when viewed from above, guiding the diffusion flow of the monitored gas component toward the partition wall. The presence of such baffles in the garage 100 is preferable from the viewpoint of accelerating and increasing the chances of collision between the monitored gas component and the laser beam LB.

[0070] Furthermore, the garage 100 may be equipped with a fan that blows air toward the partition wall. The placement of such a fan in the garage 100 is preferable from the viewpoint of accelerating and increasing the opportunity for collision between the monitored gas component and the laser beam LB, and further, from the viewpoint of stabilizing the aforementioned diffusion flow of the monitored gas component by the stable airflow provided by the fan.

[0071] Furthermore, a pressure gradient may be formed in the garage 100, where a specific bulkhead side has lower pressure. Such a pressure gradient is also preferable from the viewpoint of accelerating and increasing the chances of collision between the monitored gas component and the laser beam LB.

[0072] Furthermore, although the gas detection device 1 is a fixed device that is fixed and stationary at the measurement position as described above, it may also be a device in which the irradiation unit and the light receiving unit are arranged separately. For example, the gas detection device 1 may be a separated arrangement type device that includes an irradiation unit positioned to irradiate the aforementioned atmosphere with laser light LB, and a light receiving unit positioned to receive light SL that has passed through the atmosphere. In this case, from the viewpoint of simplifying the alignment of the optical axes of the irradiation unit and the light receiving unit, the irradiation unit may irradiate the atmosphere with scattered light from the laser light LB. Alternatively, one or both of the irradiation unit and the light receiving unit may be equipped with a vibration isolation mechanism for adjusting the optical axis (for example, the aforementioned F This may include (for example, a fine steering mirror).

[0073] Furthermore, the gas detection device 1 may be a rotating (swivel) device that changes the irradiation direction of the laser beam LB to a specific direction, in addition to the fixed or separately positioned devices described above. In this case, the control unit may be configured to adopt, as the reference value for the judgment for the warning signal described above, a predetermined reference value corresponding to the amount of light received which changes depending on the irradiation direction of the laser beam LB, or a reference value calculated to reflect the change in the amount of light received.

[0074] Other embodiments of the present invention will be described below. For the sake of convenience, components having the same function as those described in the above embodiments will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0075] [Embodiment 2] This embodiment is the same as Embodiment 1 described above, except that it further includes other detectors that detect the target gas component by means other than laser light irradiation and reception, and the control unit further refers to the detection signal of the other detectors when outputting information regarding the detection of the target gas component.

[0076] [Other detectors] Other detectors may be selected from known detectors other than the laser type described above, within the range of being able to detect the gas component to be monitored. The other detectors may be one or more types, and may be appropriately selected from, for example, gas sensors marketed by the applicant, depending on the type of gas component to be detected. Examples of other detectors include solid-state sensors, electrochemical sensors, and infrared sensors.

[0077] Solid-state sensors are suitable for detecting flammable gases. Examples of solid-state sensors include MEMS hot-wire semiconductor sensors, hot-wire semiconductor sensors, substrate semiconductor sensors, catalytic combustion sensors, and gas thermal conduction sensors.

[0078] Electrochemical sensors are suitable for detecting toxic gases or oxygen gases. Examples of electrochemical sensors include potentiometer-type sensors and galvanic cell-type sensors.

[0079] Infrared sensors are suitable for detecting carbon dioxide or flammable gases. Examples of infrared sensors include non-dispersive infrared sensors.

[0080] The monitored gas component flows near the floor surface by diffusion flow similar to that of carbon monoxide gas described in Embodiment 1, and in Embodiment 1, it tends to flow towards one side of the garage 100. Other detectors should be placed in appropriate locations in the garage 100 according to the behavior of the monitored gas component and the detection mechanism of the other detectors.

[0081] [Control Unit] In this embodiment, the control unit further includes a functional configuration that outputs information regarding the detection of the monitored gas component by further referring to the detection signals of other detectors. For example, in addition to the functional configuration of the control unit 13 of Embodiment 1, the control unit in this embodiment may further include a component amount acquisition unit that acquires the component amount of the monitored gas component detected in response to the detection signals of other detectors, and a component amount determination unit that determines whether the acquired component amount is greater than or equal to a reference value. In this control unit, the warning signal output unit 134 further refers to the determination result of the component amount determination unit.

[0082] Furthermore, the control unit in this embodiment may further include a functional configuration for controlling the detection of the target gas component by other detectors. Such a functional configuration for controlling other detectors may be provided by the other detectors, or it may be provided separately from the other detectors and the control unit 13. A control unit may be provided.

[0083] [Gas detection method] The gas detection method in this embodiment can be implemented in the same manner as the gas detection method in Embodiment 1 described above, except that detection signals from other detectors are further referenced when outputting information regarding the detection of the gas component to be monitored.

[0084] For example, the gas detection method in this embodiment further includes the steps of acquiring a detection signal from another detector and outputting information regarding the detection of a target gas component by referring to the said detection signal.

[0085] The step of acquiring detection signals from other detectors includes, for example, the step of activating other detectors and the step of acquiring detection signals from other detectors. The step of outputting information regarding the detection of a monitored gas component by referring to the detection signal includes, for example, the step of acquiring the amount of the component from the detection signal and the step of detecting whether the acquired amount of the component is greater than or equal to a reference value.

[0086] The gas detection method in this embodiment may include these further steps, for example, after step S16 which outputs a warning signal, and may further include a step of outputting a fire alarm if the amount of the acquired component is greater than the reference value. If the amount of the acquired component is less than the reference value, the process may return to before the above-mentioned further steps.

[0087] In the gas detection method described above, if the monitored gas component in the next step is carbon dioxide gas, it can be expected that combustion is progressing further, making it possible to detect the occurrence of a fire even more effectively.

[0088] Furthermore, in the gas detection method described above, if the target gas component to be monitored in the next step is a flammable gas, it is advantageous from the standpoint of anticipating situations where a fire is likely and a leak of flammable gas is expected, allowing for the estimation of the scale and extent of the fire, and enabling appropriate countermeasures according to the situation.

[0089] [Embodiment 3] Examples of applications of the gas detection device according to this embodiment are schematically shown in Figures 10 to 12. The gas detection device according to this embodiment is installed to detect gas leaks in a gas carrier.

[0090] As shown in Figure 10, the gas carrier 300 has a plurality of substantially spherical gas tanks 310. The lower half of each gas tank 310 is housed within the hull 320 of the gas carrier 300, while the upper half is exposed from the deck. Within the hull 320, the gas tanks 310 are supported by support parts 321. The exposed upper half of the tanks, along with the edges from the deck, is covered by a skirt 322. In this embodiment, the gas detection device 3 is positioned around the gas tanks 310, for example, at the gas tank edges 311 such as the upper or lower edges of the skirt 322, or at the lower part of the gas tanks 312 where a space is formed between the hull 320 and the gas tanks 310 within the hull 320. In gas carriers equipped with large, integrated structures on the deck, such as pressurized or semi-reflector type tanks, the gas detection device 3 may be positioned on the side of such structures.

[0091] The gas detection device 3 is configured similarly to the gas detection device 1 in Embodiment 1 described above, except that it is configured to output a warning signal by referring to the column density of the detected gas. A reflector 303, having dimensions large enough to receive the laser beam LB whose optical axis is shifted due to the deflection occurring in the gas carrier 300, is positioned in front of the gas detection device 3. The reflector 303, like the reflector 103 in Embodiment 1, diffusely reflects the laser beam LB. The light SL, which is a radiating element and scattered light, is received by the light receiving section of the gas detection device 3. Furthermore, the control unit of the gas detection device 3 has the same functional configuration as the control unit 13 described above, except that, for example, instead of the column density increase acquisition unit and the column density increase determination unit, it includes a column density determination unit that determines whether the acquired column density is greater than its reference value.

[0092] The gas detection method in this embodiment can be implemented in the same way as the gas detection method in Embodiment 1 described above, except that step S14, in which the column density pressure is acquired, is omitted, and a reference value for the column density is adopted in step S15. In other words, in this embodiment, a warning signal is output when the column density (ppm·m) of the monitored gas component exceeds the reference value. The warning signal output in this embodiment is not a fire warning as in Embodiment 1, but a leak warning signal for the monitored gas component.

[0093] The gas to be monitored by the gas detection device 3 is the gas component filled in the gas tank 310, such as liquefied natural gas, ammonia gas, or hydrogen gas.

[0094] The gas detection device 3 detects the target gas component in terms of column density (ppm·m), enabling high-precision detection of the target gas component along the optical path of the laser beam LB. Furthermore, since the reflector 303 is positioned opposite the gas detection device 3, the laser beam LB reaches the reflector 303 regardless of the deflection of the optical axis caused by the bending of the gas carrier 300, and is received by the light receiving unit as scattered light. Therefore, there is virtually no change in the detection intensity of the light SL at the light receiving unit due to the bending. Thus, by positioning the gas detection device 3 to irradiate the area where the diffusion flow of gas leaked from the gas tank 310 is predicted to occur, it is possible to detect gas leaks from the gas tank 310, enabling early response to gas leaks in the gas tank 310.

[0095] [Examples of implementation using software] The function of the gas detection device (hereinafter also simply referred to as "the device") can be realized by a program that causes a computer to function as the device, and by a program that causes a computer to function as each control block of the device (particularly each part included in the control unit 13).

[0096] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., memory) as hardware for executing the program. By executing the program using this control device and storage device, each of the functions described in the above embodiment can be realized.

[0097] The above program may be recorded on one or more computer-readable recording media, not temporary ones. These recording media may or may not be provided by the above device. In the latter case, the program may be supplied to the above device via any wired or wireless transmission medium.

[0098] Furthermore, some or all of the functions of each of the above control blocks can also be realized by logic circuits. For example, an integrated circuit in which logic circuits functioning as each of the above control blocks are formed is also included in the scope of the present invention. In addition, it is also possible to realize the functions of each of the above control blocks by, for example, a quantum computer.

[0099] Furthermore, each process described in the above embodiment is an AI (Artificial Intelligence) It may be executed by the control device described above. In this case, the AI ​​may be run on the control device described above, or on other devices (e.g., an edge computer or a cloud server).

[0100] 〔summary〕 A first aspect of the present invention is a ship-use gas detection device (1) installed on a ship, comprising: an illumination unit (11) that irradiates the atmosphere of the ship with laser light (LB) of a wavelength absorbed by the gas component to be monitored; a light receiving unit (12) that receives the laser light or reflected light irradiated from the illumination unit onto the atmosphere; a control unit (13) that outputs information regarding the detection of the gas component to be monitored by referring to a signal of the amount of the gas component to be monitored, which is acquired according to the intensity signal of the reflected light received by the light receiving unit; and a reflection intensity change reduction unit (reflector 103) that reduces the amount of change in the intensity signal of the reflected light due to the bending of the ship. According to the first aspect, a gas detection technology using laser light applicable to ships can be provided.

[0101] A second aspect of the present invention includes a reflectance intensity change reduction unit, which in the first aspect is positioned on the optical path of the laser beam from the irradiation unit, extends over a range of the laser beam's arrival position that changes due to the bending of the ship, and includes a reflecting member that reflects the arriving laser beam toward the light receiving unit. The second aspect is even more effective in reducing the influence of deviations in the optical axis of the laser beam due to the bending of the ship on the reflection of the laser beam.

[0102] A third aspect of the present invention is that, in the first or second aspect, the reflection intensity change reduction unit includes a correction signal generation unit that, by referring to information regarding the deflection of the ship, generates a correction signal that cancels out the change in the intensity signal of the reflected light received by the light receiving unit due to the deflection of the ship, and the control unit further refers to the correction signal to output information regarding the detection of the monitored gas component. The third aspect is even more effective from the viewpoint of simplifying and miniaturizing the configuration of the gas detection device.

[0103] A fourth aspect of the present invention is that, in any of the first to third aspects, the control unit outputs information regarding the detection of a monitored gas component when the amount of the monitored gas component exceeds a reference value corresponding to the monitored gas component. The fourth aspect is even more effective in terms of obtaining an appropriate judgment result based on the intensity of light received by the light receiving unit.

[0104] A fifth aspect of the present invention is that, in any of the first to fourth aspects, the information relating to the detection of the monitored gas component is a warning signal for a leak of the monitored gas component. The fifth aspect is even more effective in enabling early response to gas leaks in equipment that contains or circulates the monitored gas component.

[0105] A sixth aspect of the present invention is that, in any of the first to fourth aspects, the monitored gas component is a gas component generated when a substance burns, and the information regarding the detection of the monitored gas component is a fire warning signal. The sixth aspect is even more effective in realizing early fire warning and preventing fires.

[0106] A seventh aspect of the present invention is that, in any of the first to sixth aspects, the light receiving unit receives scattered light from the laser beam irradiated into the atmosphere from the irradiation unit. The seventh aspect is even more effective in reducing the influence of the deflection of the optical axis of the laser beam due to the bending of the ship on the light receiving unit's reception intensity.

[0107] An eighth aspect of the present invention further comprises, in any of the first to seventh aspects, another detector that detects a target gas component in the atmosphere without irradiating the atmosphere with laser light and receiving the irradiated laser light, and the control unit further refers to the detection signal of the other detector and outputs information regarding the detection of the target gas component. The eighth aspect is even more effective in terms of obtaining a more appropriate judgment result that takes into account the judgment result based on the detection value of the other detector.

[0108] The ninth aspect of the present invention is that, in any of the first to eighth aspects, the monitored gas The components are one or more gases selected from the group consisting of liquefied natural gas, ammonia gas, carbon monoxide gas, particulate matter, and butane gas. The ninth embodiment is even more effective from the standpoint of preventing disasters such as fires and from taking measures against such disasters at an early stage.

[0109] A tenth aspect of the present invention is a gas detection method for a ship, comprising the steps of: irradiating the atmosphere of the ship from an irradiation unit with laser light of a wavelength absorbed by a gas component to be monitored; receiving the laser light irradiated onto the atmosphere from the irradiation unit or its reflected light with a light receiving unit; and in a control unit, acquiring a signal of the amount of a gas component to be monitored according to the signal of the intensity of the reflected light received by the light receiving unit, and outputting information regarding the detection of a gas component to be monitored by referring to the acquired signal of the amount of a gas component to be monitored, further comprising the step of reducing the amount of change in the signal of the intensity of the reflected light due to the bending of the ship with a reflection intensity change reduction unit. According to the tenth aspect, a laser light gas detection technology applicable to ships can be provided.

[0110] This invention makes it possible to detect target gases in a ship's atmosphere, regardless of whether the ship flexes during navigation, by receiving laser light irradiated onto the atmosphere. Therefore, according to this invention, it is possible to detect various phenomena involving gas generation, such as gas leaks, deterioration of cargo, and signs of fire on a ship. This invention, which has such effects, is expected to contribute to achieving, for example, United Nations Sustainable Development Goal (SDG) 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0111] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of Symbols]

[0112] 1.3 Gas detection device 11 Irradiation area 12 Light receiving part 13 Control Unit 14. Focusing lens 100 Garage 101 beds 102 Bulkhead 103, 303 Reflector 110 Automobile 111 Output adjustment section 112 Laser Diode 120 Carbon monoxide gas (monitoring gas) 130 Monitoring and Control PC 131 Column Density Acquisition Unit 132 Column density increase acquisition unit 133 Column density increase determination unit 134 Warning signal output unit 300 gas carriers 310 gas tanks 311 Gas tank edge 312 Lower part of gas tank 320 hull 321 Support part 322 Skirt LB laser light SL (Light from the atmosphere)

Claims

1. A ship-use gas detection device installed on a ship, An irradiation unit that irradiates the atmosphere of the ship with laser light of a wavelength absorbed by the gas components to be monitored, A light receiving unit that receives the laser light or reflected light irradiated from the irradiation unit into the atmosphere, A control unit that outputs information regarding the detection of the monitored gas component by referring to a signal of the amount of the monitored gas component acquired in accordance with the signal of the intensity of light received by the light receiving unit, A reflection intensity change reduction unit that reduces the amount of change in the signal intensity of the received light due to the bending of the ship, A marine gas detection device, including...

2. The ship gas detection device according to claim 1, wherein the reflection intensity change reduction unit is arranged on the optical path of the laser light from the irradiation unit, extends over a range of the arrival position of the laser light which changes due to the bending of the ship, and includes a reflective member that reflects the arriving laser light toward the light receiving unit.

3. The reflection intensity change reduction unit includes a correction signal generation unit that generates a correction signal that cancels out the change in the light intensity signal received by the light receiving unit due to the bending of the ship, by referring to information regarding the bending of the ship. The control unit further refers to the correction signal and outputs information regarding the detection of the monitored gas component. The shipboard gas detection device according to claim 1.

4. The shipboard gas detection device according to claim 1, wherein the control unit outputs information regarding the detection of the monitored gas component when the amount of the monitored gas component exceeds a reference value corresponding to the monitored gas component.

5. The shipboard gas detection device according to claim 4, wherein the information relating to the detection of the monitored gas component is a warning signal for a leak of the monitored gas component.

6. The aforementioned monitored gas components are gas components generated when a substance burns, The information regarding the detection of the aforementioned monitored gas component serves as a fire warning signal. The ship's gas detection device according to claim 4.

7. The ship gas detection device according to claim 1, wherein the light receiving unit receives scattered light from the laser light irradiated into the atmosphere from the irradiation unit.

8. The system further includes another detector that detects the target gas component in the atmosphere without relying on the irradiation of the laser light into the atmosphere or the reception of the irradiated laser light. The control unit further references the detection signals from the other detectors and outputs information regarding the detection of the monitored gas component. The shipboard gas detection device according to claim 1.

9. The shipboard gas detection device according to claim 1, wherein the monitored gas component is one or more gases selected from the group consisting of liquefied natural gas, ammonia gas, carbon monoxide gas, particulate matter, and butane gas.

10. A method for detecting gases on a ship, A step of irradiating the atmosphere of the ship from an irradiation unit with laser light of a wavelength absorbed by the gas component to be monitored, A step of receiving the laser light or its reflected light irradiated from the irradiation unit into the atmosphere with a light receiving unit, The control unit includes the steps of acquiring a signal indicating the amount of the monitored gas component in accordance with the signal indicating the intensity of the reflected light received by the light receiving unit, and outputting information regarding the detection of the monitored gas component by referring to the acquired signal indicating the amount of the monitored gas component, A gas detection method further comprising the step of reducing the amount of change in the signal intensity of the reflected light due to the deflection of the vessel using a reflection intensity change reduction unit.

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