Detector, and detection method

Abstract

To accurately detect density of first gas from mixed gas consisting of the first gas and second gas of which molecular weights are close to each other.SOLUTION: A detector 1 comprises: a sample gas introduction port 2 to which first mixed gas consisting of first gas and second gas of which molecular weights are close to each other is introduced; a detection element 4 that has an adsorption film 4A formed on a quartz crystal resonator 4D; an adsorbent 3C that adsorbs the first gas; and an interchange mechanism 3 that includes a desorption device 3D desorbing the first gas adsorbed to the adsorbent 3C, and interchanges the second gas to third gas different in molecular weight from the first gas. The detector is configured to detect, as density of the first gas, a frequency variation amount of the quartz crystal resonator 4D of the detection element 4 varying according to a differential between an adsorption amount of the third gas adsorbed to the adsorption film 4A and an adsorption amount of second mixed gas consisting of the first gas and the third gas adsorbed to the adsorption film 4A after the second gas is interchanged to the third gas by the interchange mechanism 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to gas detectors and methods of detection. [Background technology]

[0002] There are odor sensors that measure the intensity of odor in a mixed gas containing multiple types of gases, for example, a mixed gas containing a first gas that emits an odor and a second gas that is odorless, by detecting the concentration of the first gas.

[0003] For example, Patent Document 1 discloses an identification device that detects odor components with a sensor by collecting the odor components in a collection tube, heating the collection tube with a heater to desorb the odor components from the collection tube, and then supplying a carrier gas to the collection tube. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-22694 Summary of the Invention [Problem to be solved by the invention]

[0005] In such an odor sensor, the concentration of the first gas, that is, the concentration of the odor component, is measured from the difference between the adsorption amount of the first gas and the adsorption amount of the mixed gas.

[0006] Since odor sensors are usually used in the atmosphere, nitrogen gas or air is often used as the second gas. However, if the difference in molecular weight between the first gas and the second gas is close, the difference between the amount of the first gas adsorbed by the odor sensor and the amount of the mixed gas adsorbed becomes small, which may reduce the accuracy of detecting the concentration of the first gas.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide a detector and a detection method that can detect the concentration of a first gas with higher accuracy than when the concentration of the first gas is detected using only a mixed gas of a first gas and a second gas having similar molecular weights. [Means for solving the problem]

[0008] The detector according to a first aspect comprises an inlet through which a first mixed gas composed of a first gas whose concentration is to be detected and a second gas whose molecular weight differs from that of the first gas by less than a predetermined value is introduced; a detection element having an adsorption film formed on a quartz oscillator; and an exchange mechanism disposed between the inlet and the detection element, which exchanges the second gas introduced from the inlet with a third gas that does not contain the first gas and whose molecular weight differs from that of the first gas by at least the predetermined value. The detector detects the concentration of the first gas by the amount of change in frequency of the quartz oscillator of the detection element, which changes depending on the difference between the amount of the third gas adsorbed onto the adsorption film and the amount of the second mixed gas composed of the first gas and the third gas adsorbed onto the adsorption film after the exchange mechanism has exchanged the second gas for the third gas.

[0009] A detector according to a second aspect is the detector according to the first aspect, wherein the exchange mechanism includes an adsorbent that adsorbs the first gas, and a desorption device that desorbs the first gas adsorbed by the adsorbent from the adsorbent when the third gas is introduced, thereby generating the second mixed gas.

[0010] A detector according to a third aspect is the detector according to the first or second aspect, wherein the first gas is ethylene and the adsorption film is made of a porous material.

[0011] A detector according to a fourth aspect is the detector according to the third aspect, wherein the porous material is a metal-organic framework.

[0012] A detector according to a fifth aspect is the detector according to the fourth aspect, wherein the second gas is nitrogen and the third gas is carbon dioxide.

[0013] A detection method according to a sixth aspect includes a detection device including: an inlet into which a first mixed gas composed of a first gas whose concentration is to be detected and a second gas whose molecular weight differs from that of the first gas by less than a predetermined value; a detection element having an adsorption film formed on a quartz crystal oscillator; and a mechanism provided between the inlet and the detection element, the mechanism including an adsorbent that adsorbs the first gas and a desorption device that desorbs the first gas adsorbed to the adsorbent from the adsorbent, and an exchange mechanism that exchanges the second gas contained in the first mixed gas introduced from the inlet with a third gas that does not contain the first gas and whose molecular weight differs from that of the first gas by the predetermined value or more. Therefore, after the first gas is adsorbed onto the adsorbent, the exchange mechanism is controlled so that the third gas introduced into the exchange mechanism comes into contact with the adsorption film, thereby adsorbing the third gas onto the adsorption film; the desorption device is controlled during the introduction of the third gas into the exchange mechanism to desorb the first gas from the adsorbent, thereby generating a second mixed gas composed of the first gas and the third gas, and adsorbing the second mixed gas onto the adsorption film; and the concentration of the first gas is detected from the frequency change of a quartz oscillator of the detection element, which changes depending on the difference between the adsorption amount of the third gas adsorbed onto the adsorption film and the adsorption amount of the second mixed gas adsorbed onto the adsorption film. [Effects of the Invention]

[0014] According to the present disclosure, the concentration of a first gas can be detected with higher accuracy compared to when the concentration of a first gas is detected using only a mixed gas of a first gas and a second gas having similar molecular weights. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a diagram illustrating an example of the configuration of a detector. [Figure 2] FIG. 10 is a diagram showing an example of the relationship between the change in oscillation frequency of a quartz crystal oscillator and the amount of gas adsorbed by an adsorption film. [Figure 3]FIG. 10 is a diagram showing an example of the frequency change |Δf| of the detection element according to the type of base gas contained in the sample gas containing ethylene. [Figure 4] FIG. 2 is a diagram illustrating an example of the configuration of a main part of an electrical system in the control device. [Figure 5] 10 is a flowchart showing an example of the flow of a detection process executed by the control device. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, the present embodiment will be described with reference to the drawings. The same components and processes are denoted by the same reference numerals throughout the drawings, and duplicated explanations will be omitted. The dimensional proportions in the drawings are exaggerated for the sake of explanation, and may differ from the actual proportions.

[0017] FIG. 1 is a diagram showing an example of the configuration of an odor component detector 1 according to the present disclosure. Detector 1 is a sensor that detects the concentration of an odor component from a gas mixture containing the odor component, and is also referred to as an "odor sensor." Hereinafter, the odor component whose concentration is to be detected will be referred to as the "target gas," the odorless gas present together with the target gas will be referred to as the "base gas," and the gas mixture consisting of the target gas and the base gas will be referred to as the "sample gas." Note that the term "gas" will be used to refer to gases in general rather than a specific type of gas.

[0018] The target gas is an example of a first gas in the present disclosure, the base gas is an example of a second gas in the present disclosure, and the sample gas is an example of a first mixed gas in the present disclosure.

[0019] As shown in FIG. 1, the detector 1 includes a sample gas inlet 2 , an exchange mechanism 3 , a detection element 4 , an intermediate flow path 5 , a valve 6 , an outlet 7 , a control device 8 , and an oscillation circuit 9 .

[0020] First, the outline of the configuration of the detector 1 will be described.

[0021] The sample gas inlet 2 is an inlet for introducing the sample gas into the detector 1. The sample gas inlet 2 is connected to the exchange mechanism 3, and the sample gas introduced from the sample gas inlet 2 flows into the exchange mechanism 3.

[0022] The exchange mechanism 3 has a mechanism for exchanging the base gas contained in the sample gas with another gas. The gas used to exchange the base gas is called the "exchange gas." Furthermore, the sample gas in which the base gas has been replaced with the exchange gas by the exchange mechanism 3 is called the "exchanged sample gas."

[0023] The replacement gas is an example of a third gas in the present disclosure, and the replacement sample gas is an example of a second gas mixture in the present disclosure.

[0024] The exchange mechanism 3 and the detection element 4 are connected by an intermediate flow path 5, and the intermediate flow path 5 is provided with a valve 6 for opening and closing the intermediate flow path 5.

[0025] The detection element 4 detects the concentration of the target gas contained in the exchange sample gas that flows in from the exchange mechanism 3 through the intermediate flow path 5. An outlet 7 is attached to the detection element 4, and the gas that passes through the detection element 4 is discharged from the outlet 7 to the atmosphere.

[0026] Next, the principle of gas exchange in the exchange mechanism 3 will be described in detail.

[0027] As shown in Figure 1, the exchange mechanism 3 is provided with an adsorbent 3C that adsorbs the target gas contained in the sample gas, and as the sample gas introduced from the sample gas inlet 2 passes through the adsorbent 3C, the target gas contained in the sample gas is adsorbed by the adsorbent 3C. Because the target gas is adsorbed by the adsorbent 3C, the target gas is removed from the sample gas that has passed through the adsorbent 3C, and only the base gas remains.

[0028] Meanwhile, a base gas outlet 3B is provided in the space downstream of the flow path of the exchange mechanism 3 after the sample gas has passed through the adsorbent 3C. Therefore, when the intermediate flow path 5 is closed by the valve 6, the base gas contained in the sample gas is discharged to the atmosphere from the base gas outlet 3B. After the base gas in the exchange mechanism 3 is discharged from the base gas outlet 3B, the valve 6 is opened, ensuring a gas flow path from the exchange mechanism 3 to the detection element 4. The opening and closing of the valve 6 is controlled by, for example, the control device 8.

[0029] Furthermore, an exchange gas inlet 3A is provided in a space located upstream of the flow path of the exchange mechanism 3 before the sample gas passes through the adsorbent 3C. Therefore, if the introduction of the sample gas from the sample gas inlet 2 is stopped and then the exchange gas is introduced from the exchange gas inlet 3A, the inside of the exchange mechanism 3 is filled with the exchange gas, and the exchange gas reaches the detection element 4 through the intermediate flow path 5.

[0030] On the other hand, when the inside of the exchange mechanism 3 is filled with exchange gas and the desorption device 3D is operated to desorb the target gas adsorbed on the adsorbent 3C from the adsorbent 3C, a mixed gas consisting of the target gas and the exchange gas, i.e., an exchange sample gas in which the base gas contained in the sample gas is replaced with the exchange gas, is generated, and the exchange sample gas reaches the detection element 4 through the intermediate flow path 5.

[0031] In this way, the base gas of the sample gas containing the target gas is exchanged with the exchange gas by the exchange mechanism 3.

[0032] Although the desorber 3D uses a heater that heats the adsorbent 3C to desorb the target gas from the adsorbent 3C, the desorber 3D is not limited to a heater and may be any device that can desorb the target gas from the adsorbent 3C. For ease of explanation, the heater that is an example of the desorber 3D will be referred to as the "heater 3D" by adding the same reference numeral "3D" as the desorber 3D. The on / off control of the heater 3D is performed by the control device 8 shown in FIG. 1.

[0033] Next, the principle of detection of the concentration of the target gas by the detection element 4 will be described.

[0034] As shown in Figure 1, the detection element 4 includes a quartz crystal oscillator 4D composed of electrodes 4B and a quartz crystal 4C, and an adsorption film 4A formed on the quartz crystal oscillator 4D. When gas is adsorbed onto the adsorption film 4A of the detection element 4, the oscillation frequency of the quartz crystal oscillator 4D changes depending on the amount of adsorption of the gas. The relationship between the oscillation frequency of the quartz crystal oscillator 4D and the amount of gas adsorbed onto the adsorption film 4A is expressed by the Sauerbrey equation shown in equation (1).

[0035]

number

[0036] In equation (1), Δf is the frequency change of the quartz crystal oscillator 4D, n is the odd-order harmonic, f0 is the fundamental frequency, A is the area of ​​the adsorption film 4A, and ρ q is the density of the quartz crystal 4C, μ q represents the rigidity of the quartz crystal 4C, and Δm represents the mass change of the gas adsorbed on the adsorption film 4A.

[0037] 2 is a graph showing an example of the relationship between the change in the oscillation frequency of the quartz crystal resonator 4D based on equation (1) and the amount of gas adsorbed on the adsorption film 4A. The horizontal axis of Fig. 2 represents the passage of time, and the vertical axis represents the frequency change Δf relative to the reference oscillation frequency of the quartz crystal resonator 4D.

[0038] When gas is adsorbed onto the adsorption film 4A at time t1, the mass of the adsorption film 4A increases, which increases Δm and reduces the frequency change Δf. On the other hand, when gas is desorbed from the adsorption film 4A at time t2, the mass of the adsorption film 4A decreases, which decreases Δm and increases the frequency change Δf.

[0039] Therefore, the detection element 4 notifies the control device 8 of the oscillation frequency of the quartz crystal oscillator 4D before and after the target gas is adsorbed onto the adsorption film 4A.

[0040] The control device 8 calculates the mass change Δm of the gas adsorbed on the adsorption film 4A from the frequency change Δf, which is the difference between the oscillation frequencies, to detect the concentration of the target gas. The oscillation of the quartz crystal oscillator 4D is performed by an oscillation circuit 9. The detection element 4 may have the oscillation circuit 9 built in. The detector 1 shown in FIG. 1 does not necessarily need to include the control device 8, and the control device 8 may be separate from the detector 1.

[0041] The adsorption film 4A is made of a porous material to easily adsorb the target gas. Specifically, a metal organic framework (MOF) is used for the adsorption film 4A. Specifically, UiO-66, ZIF-8, MOF-5, MOF-74, and HKUST-1 are used, and the metal elements constituting these structures are Co. 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Al 3+ , Mn 2+ , Fe 2+ , Fe 3+ , Cr 3+ , and Cr 6+ Furthermore, MOFs obtained by adding functional groups such as amino groups, carboxyl groups, and sulfo groups to the above-mentioned MOFs may also be used.

[0042] The adsorption film 4A is not limited to a metal-organic framework, and may be made of zeolite, activated carbon, mesoporous silica, a porous coordination polymer (PCP), silica gel, a covalent organic framework (COF), a clay mineral, or a porous metal.

[0043] Here, we consider an example in which the exchange mechanism 3 is removed from the detector 1, and the concentration of the target gas contained in the sample gas is detected using a detector (referred to as a "comparison detector") in which the sample gas inlet 2 is directly connected to the detection element 4. For the sake of specific explanation, the target gas contained in the sample gas is ethylene, and the base gas is nitrogen (sometimes referred to as "N2").

[0044] The molecular weight of ethylene is 28.01 g / mol, and the molecular weight of nitrogen is 28.05 g / mol, resulting in a molecular weight difference of only 0.04 g / mol between ethylene and nitrogen. Furthermore, because both ethylene and nitrogen are adsorbed to the adsorption film 4A of the detection element 4 by physical adsorption, changes in mass tend to be less transmitted to the adsorption film 4A than when adsorption is by chemical adsorption. Therefore, the difference between the amount of nitrogen adsorbed on the adsorption film 4A and the amount of sample gas adsorbed is small, and the oscillation frequency of the quartz crystal oscillator 4D in the comparison detector changes only by a value below the detection limit, which may prevent the ethylene concentration from being detected.

[0045] On the other hand, in the detector 1 shown in FIG. 1 having an exchange mechanism 3, a sample gas composed of ethylene and nitrogen is introduced through a sample gas inlet 2, and the ethylene is adsorbed by an adsorbent 3C. After that, nitrogen is discharged through a base gas outlet 3B, and an exchange gas that serves as a base gas instead of nitrogen is introduced through an exchange gas inlet 3A. For example, carbon dioxide (sometimes referred to as "CO2") is used as the exchange gas. The exchange gas is an example of the third gas in this disclosure.

[0046] By introducing carbon dioxide into the exchange mechanism 3, carbon dioxide is adsorbed onto the adsorption film 4A of the detection element 4, and then the desorption device 3D is operated, so that the exchange sample gas consisting of ethylene and carbon dioxide is adsorbed onto the adsorption film 4A of the detection element 4. The molecular weight of carbon dioxide is 44.01 [g / mol], which is 16.00 [g / mol] larger than the molecular weight of ethylene.

[0047] Therefore, the difference between the amount of carbon dioxide adsorbed in the adsorption film 4A and the amount of adsorption of the replacement sample gas becomes larger than the difference between the amount of nitrogen adsorbed and the amount of sample gas adsorbed, so the frequency change Δf of the quartz oscillator 4D becomes larger, and the concentration of ethylene can be detected.

[0048] When carbon dioxide is used as the exchange gas, it is preferable to use UiO-66, which is an example of an MOF that adsorbs carbon dioxide more easily than other porous materials, for the adsorption film 4A.

[0049] In the above example, carbon dioxide was used as the exchange gas, but in this case, the exchange gas should not contain the target gas and should have a molecular weight difference of at least a predetermined value from the target gas. Specifically, if a gas with a molecular weight difference of at least ±1 g / mol from the target gas is used as the exchange gas, the concentration of the target gas can be detected.

[0050] Figure 3 shows an example of the frequency change |Δf| of the detection element 4 depending on the type of base gas contained in a sample gas containing ethylene, which is the target gas. The horizontal axis of Figure 3 represents the molar mass [g / mol] of the base gas, and the vertical axis represents the frequency change Δf relative to the reference oscillation frequency of the detection element 4. Points P1, P2, P3, P4, and P5 in Figure 3 represent the frequency change |Δf| of the detection element 4 when nitrogen, air, oxygen, carbon dioxide, and acetone vapor are used as the base gas, respectively. The operator |Δf| represents the absolute value of the frequency change Δf.

[0051] As shown in Figure 3, when nitrogen and air, which have molecular weights less than ±1 g / mol different from ethylene, are used as base gases, the frequency change |Δf| of the detection element 4 is near 0. On the other hand, when oxygen, carbon dioxide, or acetone vapor, which have molecular weights more than ±1 g / mol different from ethylene, are used as base gases, the frequency change |Δf| of the detection element 4 is large enough to detect the ethylene concentration. Therefore, when detecting the concentration of ethylene in a sample gas using the detector 1, any of oxygen, carbon dioxide, or acetone vapor can be used as the exchange gas. Furthermore, either argon or helium can also be used as the exchange gas because their molecular weights are more than ±1 g / mol different from ethylene. However, because oxygen and acetone vapor are flammable, it is preferable to use carbon dioxide, which is more readily available and non-flammable than other gases, when detecting the concentration of ethylene in a sample gas using the detector 1. Air with a humidity level below a predetermined value (e.g., 30%) is specifically called "dry air." However, dry air is also a gas whose molecular weight differs from that of ethylene by less than ±1 g / mol, and it may be used as a base gas. Therefore, even when dry air is used as a base gas, the frequency change |Δf| of the detection element 4 will be close to 0.

[0052] The control device 8 of the detector 1 is configured using a computer 10, for example.

[0053] FIG. 4 is a diagram showing an example of the configuration of the main parts of an electrical system in the control device 8 using the computer 10. As shown in FIG.

[0054] The computer 10 includes a CPU (Central Processing Unit) 10A, which is an example of a processor that performs the functions of the control device 8, a RAM (Random Access Memory) 10B used as a temporary work area for the CPU 10A, a non-volatile memory 10C that stores a detection program that causes the computer 10 to function as the control device 8 of the detector 1, and an input / output interface (referred to as "I / O") 10D. The CPU 10A, RAM 10B, non-volatile memory 10C, and I / O 10D are each connected via a bus 10E.

[0055] The nonvolatile memory 10C is an example of a storage device that maintains stored information even when power to the nonvolatile memory 10C is cut off, and may be, for example, a semiconductor memory or a hard disk. For example, data that should not be erased every time the power to the computer 10 is turned off is stored in the nonvolatile memory 10C. The nonvolatile memory 10C does not necessarily have to be built into the computer 10, and may be a portable storage device that is detachable from the computer 10, such as a memory card. The computer 10 may also use, as the nonvolatile memory 10C, a nonvolatile memory of an external device (not shown) connected via a communication unit (not shown) connected to the I / O 10D, for example.

[0056] On the other hand, for example, a heater 3D, a detection element 4, a valve 6, and a user interface device (referred to as a "UI device") 11 are connected to the I / O 10D.

[0057] The UI device 11 is a device that receives instructions from a user by, for example, operating a button, and that has a screen that displays information such as the concentration of the detected target gas.

[0058] Therefore, the CPU 10A controls the heater 3D and the valve 6 via the I / O 10D, obtains the oscillation frequency of the quartz oscillator 4D from the detection element 4, and displays the detected concentration of the target gas on the UI device 11. The CPU 10A may be connected to the UI device 11 via a communication unit connected to the I / O 10D.

[0059] Next, a description will be given of the operation of the detector 1. Fig. 5 is a flowchart showing an example of the flow of the detection process executed by the CPU 10A of the control device 8 when, for example, the power supply of the detector 1 is turned on.

[0060] A detection program that defines the detection process is stored in advance in, for example, the nonvolatile memory 10C of the computer 10 shown in Fig. 4. The CPU 10A of the control device 8 reads the detection program stored in the nonvolatile memory 10C and executes the detection process.

[0061] The operation of the detector 1 will be described below using an example in which the concentration of ethylene is detected from a sample gas composed of ethylene and nitrogen. Carbon dioxide is used as the exchange gas, for example.

[0062] In step S10, CPU 10A performs control to close valve 6. As a result, intermediate flow path 5 is blocked.

[0063] In step S20, CPU 10A determines whether the introduction of sample gas has started from sample gas inlet 2. CPU 10A may determine that the introduction of sample gas has started, for example, when an instruction to start sample gas introduction is received from a user via UI device 11. If the instruction to start sample gas introduction has not been received, CPU 10A may repeatedly execute the determination process of step S20, for example, and wait until the instruction to start sample gas introduction is received. On the other hand, if the instruction to start sample gas introduction is received, CPU 10A proceeds to step S30.

[0064] Ethylene is adsorbed onto the adsorbent 3C as the sample gas is introduced into the exchange mechanism 3. Furthermore, since the intermediate flow path 5 is blocked by the processing of step S10, nitrogen contained in the sample gas introduced into the exchange mechanism 3 is discharged from the base gas outlet 3B.

[0065] In step S30, CPU 10A determines whether the introduction of sample gas has ended. CPU 10A may determine that the introduction of sample gas has ended, for example, when an instruction to end the introduction of sample gas is received from the user via UI device 11. If the instruction to end the introduction of sample gas has not been received, CPU 10A may repeatedly execute the determination process of step S30, for example, and wait until the instruction to end the introduction of sample gas is received. On the other hand, if the instruction to end the introduction of sample gas is received, CPU 10A proceeds to step S40.

[0066] In step S40, CPU 10A performs control to open valve 6. As a result, exchange mechanism 3 and detection element 4 are connected by intermediate flow path 5.

[0067] In step S50, the CPU 10A determines whether or not the introduction of carbon dioxide has started from the exchange-gas inlet 3A. The CPU 10A may determine that the introduction of carbon dioxide has started when, for example, an instruction to start the introduction of exchange-gas has been received from the user via the UI device 11. If the instruction to start the introduction of exchange-gas has not been received, for example, the CPU 10A repeatedly executes the determination process of step S50 and waits until the instruction to start the introduction of exchange-gas is received. On the other hand, if the instruction to start the introduction of exchange-gas has been received, the CPU 10A proceeds to step S60.

[0068] Since the intermediate flow path 5 is opened by the process of step S40, the carbon dioxide introduced into the exchange mechanism 3 reaches the detection element 4.

[0069] Therefore, in step S60, the CPU 10A obtains the oscillation frequency of the quartz crystal oscillator 4D, which changes depending on the amount of carbon dioxide adsorbed on the adsorption film 4A, from the detection element 4, and stores it in the RAM 10B.

[0070] In step S70, CPU 10A controls the heater 3D to be powered on. As a result, ethylene is desorbed from the adsorbent 3C, and a mixed gas of ethylene and carbon dioxide is generated in the exchange mechanism 3. That is, an exchanged sample gas is generated in which the base gas in the sample gas is exchanged from nitrogen to carbon dioxide.

[0071] Since the intermediate flow path 5 is in an open state, the exchange sample gas generated by the exchange mechanism 3 reaches the detection element 4 .

[0072] Therefore, in step S80, the CPU 10A obtains the oscillation frequency of the quartz crystal oscillator 4D, which changes depending on the amount of exchange sample gas adsorbed on the adsorption film 4A, from the detection element 4, and stores it in the RAM 10B.

[0073] In step S90, CPU 10A calculates the mass change Δm of the gas adsorbed on the adsorption film 4A using the Sauerbrey equation (1) from the frequency change Δf, which is expressed as the difference between the oscillation frequency acquired by the processing in step S60 and the oscillation frequency acquired by the processing in step S80, and detects the concentration of ethylene contained in the sample gas. CPU 10A displays the detected ethylene concentration, for example, on the UI device 11. This completes the detection process shown in FIG. 5.

[0074] Thus, according to the detector 1 of the present disclosure, an exchange mechanism 3 is provided between the sample gas inlet 2 and the detection element 4, and the base gas in the sample gas is exchanged for an exchange gas. Therefore, even if the molecular weight difference between the target gas and the base gas is less than ±1 [g / mol], the base gas can be exchanged for an exchange gas whose molecular weight difference with the target gas is ±1 [g / mol] or more, making it possible to detect the concentration of the target gas contained in the sample gas.

[0075] In addition to ethylene and carbon dioxide, other gas combinations with molecular weight differences of less than ±1 g / mol include methylamine (31.10 g / mol) and oxygen (32.00 g / mol), and acetaldehyde (44.05 g / mol) and carbon dioxide (44.01 g / mol). The detector 1 can also detect odor components (methylamine and acetaldehyde) in sample gases composed of these combinations.

[0076] Furthermore, it is also possible to detect the concentration of either gas from a sample gas that does not contain any odor components, such as a sample gas composed of carbon monoxide (28.01 [g / mol]) and nitrogen (28.05 [g / mol]).

[0077] In addition, it goes without saying that even for sample gases composed of a combination of a target gas and a base gas not listed above where the molecular weight difference between the two is less than ±1 [g / mol], by replacing the base gas, the detector 1 can detect the concentration of either type of gas contained in the sample gas.

[0078] When detecting the concentration of a gas other than ethylene, the exchange mechanism 3 is provided with an adsorbent 3C that adsorbs the gas whose concentration is to be detected.

[0079] In the detector 1 shown in Figure 1, an exchange gas inlet 3A is provided in the exchange mechanism 3 upstream of the adsorbent 3C with respect to the gas flow, but the exchange gas inlet 3A may also be provided downstream of the adsorbent 3C and in the flow path between the adsorbent 3C and the adsorption film 4A of the detection element 4.

[0080] Furthermore, the valve 6 does not necessarily have to be provided in the intermediate flow path 5, and the valve 6 may be provided at the connection part of either the exchange mechanism 3 or the detection element 4, which are connected to the intermediate flow path 5. In other words, either the exchange mechanism 3 or the detection element 4 may include the valve 6.

[0081] Furthermore, the detector 1 shown in Figure 1 has a sample gas inlet 2 for introducing sample gas into the exchange mechanism 3 and an exchange gas inlet 3A for introducing exchange gas into the exchange mechanism 3, but the sample gas inlet 2 and the exchange gas inlet 3A may be a common inlet, and the sample gas and exchange gas may be introduced into the exchange mechanism 3 from the same inlet.

[0082] 1 has a base gas outlet 3B for discharging the base gas contained in the sample gas and an outlet 7 for discharging the gas that has passed through the detection element 4, but the gas may be discharged from the outlet 7 without providing the base gas outlet 3B. In this case, it is not necessary to provide the valve 6 and the intermediate flow path 5, and it is sufficient to connect the exchange mechanism 3 and the detection element 4 next to each other. The control device 8 does not acquire the oscillation frequency when the sample gas is passing through the detection element 4, and it is sufficient to perform each of the processes of steps S60 to S90 shown in FIG. 5 after the exchange gas is introduced into the exchange mechanism 3.

[0083] Although the present disclosure has been described above using the embodiments, the present disclosure is not limited to the scope described in the embodiments. Various modifications or improvements can be made to the embodiments without departing from the spirit of the present disclosure, and such modifications or improvements are also included in the technical scope of the present disclosure. For example, the internal order of the detection process shown in FIG. 5 may be changed without departing from the spirit of the present disclosure.

[0084] In the embodiment, an example has been described in which the detection process in the detector 1 is realized by software, but the same process as the flowchart of the detection process shown in Fig. 5 may be implemented in, for example, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a PLD (Programmable Logic Device) and processed by hardware. In this case, the processing speed can be increased compared to when the detection process is realized by software.

[0085] In this way, the CPU 10A of the detector 1 may be replaced with a dedicated processor specialized for specific processing, such as an ASIC, FPGA, PLD, GPU (Graphics Processing Unit), or FPU (Floating Point Unit).

[0086] Furthermore, the operation of the CPU 10A of the detector 1 in the embodiment may be realized by one CPU 10A or by multiple CPUs 10A. Furthermore, the operation of the CPU 10A of the detector 1 in the embodiment may be realized by cooperation of multiple CPUs 10A located at physically separate locations.

[0087] In the above-described embodiment, the detection program read by the CPU 10A of the detector 1 is installed in the nonvolatile memory 10C, but the present invention is not limited to this. The detection program according to this embodiment can also be provided in a form recorded on a storage medium readable by the computer 10. For example, the detection program may be provided in a form recorded on an optical disc such as a CD (Compact Disc)-ROM or a DVD (Digital Versatile Disc)-ROM. The detection program may also be provided in a form recorded on a portable semiconductor memory such as a USB (Universal Serial Bus) memory or a memory card. The nonvolatile memory 10C, CD-ROM, DVD-ROM, USB, and memory card are examples of non-transitory storage media.

[0088] Furthermore, the detector 1 may download the detection program from an external device connected to a communication line. In this case, the CPU 10A of the detector 1 reads the detection program downloaded from the external device and executes the detection process.

[0089] In addition, the following supplementary notes are disclosed regarding the above-described embodiment.

[0090] (Appendix 1) an inlet into which a first mixed gas is introduced, the first mixed gas being a target of concentration detection and a second mixed gas having a molecular weight difference with the first mixed gas that is less than a predetermined value; a detection element having an adsorption film formed on a quartz crystal oscillator; an exchange mechanism provided between the inlet and the detection element, which exchanges the second gas introduced from the inlet with a third gas that does not contain the first gas and has a molecular weight difference with the first gas that is equal to or greater than the predetermined value; Equipped with The amount of change in frequency of a quartz crystal oscillator of the detection element, which changes depending on the difference between the amount of the third gas adsorbed on the adsorption film and the amount of a second mixed gas composed of the first gas and the third gas adsorbed on the adsorption film after the second gas is exchanged for the third gas by the exchange mechanism, is detected as the concentration of the first gas. Detector.

[0091] (Appendix 2) The exchange mechanism includes an adsorbent that adsorbs the first gas; a desorption device that desorbs the first gas adsorbed in the adsorbent from the adsorbent when the third gas is introduced, thereby generating the second mixed gas; 2. The detector of claim 1, comprising:

[0092] (Appendix 3) the first gas is ethylene; The adsorption membrane is made of a porous material. 10. A detector according to claim 1 or 2.

[0093] (Appendix 4) The porous material is a metal-organic framework. Detector according to appendix 3.

[0094] (Appendix 5) The second gas is any one of nitrogen, dry air, and air, and the third gas is any one of carbon dioxide, argon, helium, and oxygen. A detector according to any one of Supplementary notes 1 to 4.

[0095] (Appendix 6) an inlet into which a first mixed gas is introduced, the first mixed gas being a target of concentration detection and a second mixed gas having a molecular weight difference with the first mixed gas that is less than a predetermined value; a detection element having an adsorption film formed on a quartz crystal oscillator; an exchange mechanism provided between the inlet and the detection element, the exchange mechanism including an adsorbent that adsorbs the first gas and a desorption device that desorbs the first gas adsorbed to the adsorbent from the adsorbent, and which exchanges the second gas contained in the first mixed gas introduced from the inlet with a third gas that does not contain the first gas and has a molecular weight difference from the first gas that is equal to or greater than the predetermined value; Using a detector equipped with After the first gas mixture is adsorbed onto the adsorbent by the first gas mixture introduced from the inlet, the exchange mechanism is controlled so that the third gas introduced into the exchange mechanism comes into contact with the adsorption film, thereby adsorbing the third gas onto the adsorption film; and while the third gas is being introduced into the exchange mechanism, the desorption device is controlled to desorb the first gas from the adsorbent, thereby generating a second gas mixture composed of the first gas and the third gas, and adsorbing the second gas mixture onto the adsorption film; A computer executes a process of detecting the concentration of the first gas from a frequency change amount of a quartz oscillator of the detection element, which changes depending on a difference between an adsorption amount of the third gas adsorbed on the adsorption film and an adsorption amount of the second mixed gas adsorbed on the adsorption film. Detection method. [Explanation of symbols]

[0096] 1. Detector 2 Sample gas inlet 3 Exchange mechanism 3A Exchange gas inlet 3B Base gas outlet 3C adsorbent 3D Desorption Device (Heater) 4. Detector element 4A Adsorption membrane 4B electrode 4C crystal crystal 4D crystal oscillator 5 Intermediate flow path 6 valves 7 Outlet 8 Control Device 9 Oscillator Circuit 10. Computers 10A CPU 10B RAM 10C non-volatile memory 10D I / O 10E Bus 11 UI device Δf Frequency change amount Δm Mass change amount

Claims

1. an inlet into which a first mixed gas is introduced, the first mixed gas being a target of concentration detection and a second mixed gas having a molecular weight difference with the first mixed gas that is less than a predetermined value; a detection element having an adsorption film formed on a quartz crystal oscillator; an exchange mechanism provided between the inlet and the detection element, which exchanges the second gas introduced from the inlet with a third gas that does not contain the first gas and has a molecular weight difference with the first gas that is equal to or greater than the predetermined value; Equipped with The amount of change in frequency of a quartz crystal oscillator of the detection element, which changes depending on the difference between the amount of the third gas adsorbed on the adsorption film and the amount of a second mixed gas composed of the first gas and the third gas adsorbed on the adsorption film after the second gas is exchanged for the third gas by the exchange mechanism, is detected as the concentration of the first gas. Detector.

2. The exchange mechanism includes an adsorbent that adsorbs the first gas; a desorption device that desorbs the first gas adsorbed by the adsorbent from the adsorbent when the third gas is introduced, thereby generating the second mixed gas; The detector of claim 1 , comprising:

3. the first gas is ethylene; The adsorption membrane is made of a porous material.

3. A detector according to claim 1 or claim 2.

4. The porous material is a metal-organic framework.

4. The detector of claim 3.

5. The second gas is any one of nitrogen, dry air, and air, and the third gas is any one of carbon dioxide, argon, helium, and oxygen.

5. The detector of claim 4.

6. an inlet into which a first mixed gas is introduced, the first mixed gas being a target of concentration detection and a second mixed gas having a molecular weight difference with the first mixed gas that is less than a predetermined value; a detection element having an adsorption film formed on a quartz crystal oscillator; an exchange mechanism provided between the inlet and the detection element, the exchange mechanism including an adsorbent that adsorbs the first gas and a desorption device that desorbs the first gas adsorbed by the adsorbent from the adsorbent, and which exchanges the second gas contained in the first mixed gas introduced from the inlet with a third gas that does not contain the first gas and has a molecular weight difference from the first gas that is equal to or greater than the predetermined value; Using a detector equipped with After the first gas mixture is adsorbed onto the adsorbent by the first gas mixture introduced from the inlet, the exchange mechanism is controlled so that the third gas introduced into the exchange mechanism comes into contact with the adsorption film, thereby adsorbing the third gas onto the adsorption film; and while the third gas is being introduced into the exchange mechanism, the desorption device is controlled to desorb the first gas from the adsorbent, thereby generating a second gas mixture composed of the first gas and the third gas, and adsorbing the second gas mixture onto the adsorption film. A computer executes a process of detecting the concentration of the first gas from a frequency change amount of a quartz oscillator of the detection element, which changes depending on a difference between an adsorption amount of the third gas adsorbed on the adsorption film and an adsorption amount of the second mixed gas adsorbed on the adsorption film. Detection method.

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