Analytical apparatus, analytical method, and ozone decomposer

Abstract

A suitable reference gas is generated from the sample gas, in which components other than ozone are not excessively removed. [Solution] The analyzer 100 comprises a measuring cell 1 into which a sample gas Gs and a reference gas Gr are alternately introduced, a light source 3 that outputs measuring light L, a detection unit 5 that detects the measuring light L that has passed through the measuring cell 1, a calculation unit 91 that analyzes the ozone contained in the sample gas Gs, and an ozone decomposer 71 that generates the reference gas Gr from the sample gas Gs by heating. The ozone decomposer 71 has an introduction tube 71a into which the sample gas Gs is introduced, a heating unit 71b that heats the introduction tube 71a, and a porous first filling member 71c made of a substance that is inert to sulfur dioxide and is filled into the heated portion of the introduction tube 71a by the heating unit 71b.

Description

Technical Field

[0001] The present invention relates to an analyzer for analyzing ozone contained in a sample gas. In particular, an analyzer that analyzes ozone based on the measurement light after passing through the sample gas and the measurement light after passing through a reference gas that does not contain ozone, an analysis method that analyzes ozone based on the measurement light after passing through the sample gas and the measurement light after passing through the reference gas, and an ozone decomposer that decomposes ozone contained in the sample gas to generate a reference gas.

Background Art

[0002] Conventionally, a sample gas and a reference gas that does not contain ozone are alternately introduced into a measurement cell, and based on the intensity of the measurement light (for example, ultraviolet light) after passing through the sample gas introduced into the measurement cell and the intensity of the measurement light after passing through the reference gas introduced into the measurement cell, an analyzer for analyzing ozone (for example, calculating the concentration of ozone) contained in the sample gas is known. In this analyzer, the reference gas is generated by introducing the sample gas into an ozone decomposer and removing ozone from the sample gas (for example, see Patent Document 1).

[0003] The ozone decomposer used in the above analyzer removes ozone from the sample gas by decomposing ozone with a catalyst such as manganese dioxide.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the analytical apparatus described above, in order to accurately analyze the ozone contained in the sample gas, it is preferable that the reference gas is a gas obtained by removing only ozone from the sample gas. That is, when generating the reference gas from the sample gas, it is preferable that gas components that absorb the measurement light used for ozone analysis are not removed from the sample gas. In particular, when using ultraviolet light as the measurement light, it is preferable that sulfur dioxide (SO2) is not excessively removed from the sample gas.

[0006] However, in ozonodegraders that use metals as catalysts to decompose ozone, the catalyst and sulfur dioxide interact, potentially creating a reference gas from which sulfur dioxide has been excessively removed from the sample gas.

[0007] The object of the present invention is to generate a reference gas in which components other than ozone are not excessively removed from the sample gas, in an analytical device that analyzes ozone contained in a sample gas based on the measurement light after passing through the sample gas and the measurement light after passing through the reference gas. [Means for solving the problem]

[0008] Several embodiments for solving the problem are described below. These embodiments can be combined as needed. The analytical apparatus according to the present invention is an apparatus for analyzing ozone contained in a sample gas. The analytical apparatus comprises a measuring cell, a light source, a detection unit, a calculation unit, and an ozone decomposer. Sample gas and reference gas are alternately introduced into the measuring cell. The reference gas is a gas that does not contain ozone. The light source outputs measurement light toward the measuring cell. The detection unit detects the measurement light that has passed through the measuring cell. The calculation unit analyzes the ozone contained in the sample gas based on the measurement light detected by the detection unit after passing through the sample gas and the measurement light detected by the detection unit after passing through the reference gas. The ozone decomposer generates a reference gas by decomposing the ozone contained in the sample gas by heating.

[0009] In the analytical apparatus described above, the ozone decomposer comprises an inlet tube, a heating section, and a first packing member. The inlet tube introduces the sample gas. The heating section heats the inlet tube. The first packing member is a porous member made of a substance inert to sulfur dioxide, which is filled into the heated portion of the inlet tube by the heating section.

[0010] In the ozone decomposer of the analytical apparatus described above, since the first packing member is porous, the sample gas introduced into the inlet tube tends to accumulate in the packed portion of the first packing member. The packed portion of the first packing member is heated by the heating section, but because the sample gas accumulates in the packed portion of the first packing member (i.e., it takes time for the sample gas to pass through the first packing member), the temperature drop in the packed portion is suppressed, and the sample gas is heated for a relatively long time. In this way, the temperature drop in the packed portion of the first packing member is suppressed, and the sample gas is heated for a relatively long time, so that the ozone contained in the sample gas can be efficiently decomposed and removed by heating alone, without the use of a metal catalyst.

[0011] Furthermore, by filling the inlet tube with the first packing material, the temperature drop of the packed portion of the first packing material is suppressed, and the sample gas is heated in this packed portion for a relatively long time. As a result, ozone can be efficiently decomposed and removed even if the heating temperature of the inlet tube by the heating unit is lowered. Lowering the heating temperature of the inlet tube by the heating unit also suppresses the generation of products due to the heating of the sample gas.

[0012] Furthermore, in the above-described ozone decomposer, no metal catalyst active against sulfur dioxide is used, and the first packing material filling the inlet tube is made of a substance inert to sulfur dioxide. As a result, sulfur dioxide that absorbs measurement light is less likely to be removed from the sample gas, so the above-described ozone decomposer can produce a more suitable reference gas in which sulfur dioxide contained in the sample gas is not excessively removed.

[0013] Furthermore, "active to sulfur dioxide" means, for example, that sulfur dioxide is adsorbed onto the first packing material, and / or interacts with the first packing material, etc., to change into other substances, thereby reducing the amount of sulfur dioxide contained in the sample gas. Therefore, "inactive to sulfur dioxide" means that no adsorption and / or interaction of sulfur dioxide occurs, and the amount of sulfur dioxide contained in the sample gas does not decrease.

[0014] In the analytical apparatus described above, the first packing member may be made of a substance that is inert to hydrocarbons. This makes it more difficult to remove hydrocarbons that absorb the measurement light from the sample gas, thus enabling the production of a more suitable reference gas in which hydrocarbons contained in the sample gas are not excessively removed.

[0015] In the analytical apparatus described above, the first packing member may be made of quartz wool. This makes it easier for the sample gas to accumulate in the packed portion of the first packing member.

[0016] The ozone decomposer described above may further include a second packing member. The second packing member is packed on the outlet side of the inlet tube and is made of a substance that adsorbs products generated by heating the sample gas. This suppresses the effect of the products on the analytical instrument.

[0017] In the analytical apparatus described above, the second packing member may be made of quartz wool. This allows for more efficient adsorption of products generated by heating the sample gas.

[0018] In the analytical apparatus described above, the heating temperature of the inlet tube may be 150°C to 400°C. This allows for efficient decomposition and removal of ozone from the sample gas while suppressing excessive heating of the inlet tube.

[0019] In the analytical apparatus described above, the light source may be an LED that outputs ultraviolet light as the measurement light. Since LEDs output ultraviolet light with a relatively wide spectral width, if excessive sulfur dioxide is removed from the sample gas and a reference gas is generated, it may affect the analysis of ozone using ultraviolet light. The ozone decomposer in the analytical apparatus described above suppresses the removal of excessive sulfur dioxide from the sample gas, so even if an LED is used as the light source for the measurement light, which is ultraviolet light, ozone can be analyzed accurately.

[0020] Another analytical method according to the present invention is a method for analyzing ozone contained in a sample gas using measuring light. The analytical method comprises the following steps. ◎Step of heating the inlet tube. ◎Step of introducing the sample gas into the introduction tube. ◎A step in which the sample gas is passed through a porous first packing member made of a substance inert to sulfur dioxide, which is filled in the heated section of the inlet tube, and the ozone contained in the sample gas is decomposed by heating to generate an ozone-free reference gas. ◎A step in which measurement light is passed through a reference gas and the measurement light after passing through the reference gas is detected. ◎A step in which measurement light is passed through a sample gas and the measurement light after passing through the sample gas is detected. ◎A step of analyzing the ozone contained in the sample gas based on the measurement light detected after passing through the sample gas and the measurement light detected after passing through the reference gas.

[0021] In the above analysis method, since the first filling member is porous, the sample gas introduced into the introduction pipe is likely to stay in the filled portion of the first filling member of the introduction pipe. The filled portion of the first filling member is heated by heating the introduction pipe. However, when the sample gas stays in the filled portion of the first filling member, the temperature drop in the filled portion is suppressed, and the sample gas is heated for a relatively long time. Thus, by suppressing the temperature drop in the filled portion of the first filling member and heating the sample gas for a relatively long time, ozone contained in the sample gas can be efficiently decomposed and removed only by heating without using a metal catalyst.

[0022] Also, by filling the introduction pipe with the first filling member, the temperature drop in the filled portion of the first filling member is suppressed, and the sample gas is heated for a relatively long time in the filled portion. Therefore, even if the heating temperature of the introduction pipe is lowered, ozone can be efficiently decomposed and removed. By being able to lower the heating temperature of the introduction pipe, generation of products due to heating of the sample gas can also be suppressed.

[0023] In the case of analyzing ozone contained in a sample gas based on measurement light detected after the sample gas has passed through and measurement light detected after a reference gas containing no ozone has passed through, an ozone decomposer according to another aspect of the present invention decomposes ozone contained in the sample gas by heating to generate a reference gas. The ozone decomposer includes an introduction pipe, a heating unit, and a first filling member. The introduction pipe introduces the sample gas. The heating unit heats the introduction pipe. The first filling member is filled in the heated portion of the introduction pipe by the heating unit and is a porous member made of a substance that is inert to sulfur dioxide.

[0024] In the above ozone decomposer, since the first filling member is porous, the sample gas introduced into the introduction pipe is likely to stay in the filled portion of the first filling member. The filled portion of the first filling member is heated by the heating portion. However, when the sample gas stays in the filled portion of the first filling member, the temperature drop in the filled portion is suppressed, and the sample gas is heated for a relatively long time. Thus, since the temperature drop in the filled portion of the first filling member is suppressed and the sample gas is heated for a relatively long time, ozone contained in the sample gas can be efficiently decomposed and removed only by heating without using a metal catalyst.

[0025] Also, by filling the introduction pipe with the first filling member, the temperature drop in the filled portion of the first filling member is suppressed, and the sample gas is heated for a relatively long time in the filled portion. Therefore, even if the heating temperature of the introduction pipe by the heating portion is lowered, ozone can be efficiently decomposed and removed. Since the heating temperature of the introduction pipe by the heating portion can be lowered, generation of products due to heating of the sample gas can also be suppressed.

Advantages of the Invention

[0026] A reference gas in which components other than ozone are not excessively removed from the sample gas can be generated, so that ozone can be analyzed more accurately.

Brief Description of the Drawings

[0027] [Figure 1] A diagram showing the configuration of the analyzer. [Figure 2] A diagram showing the configuration of the ozone decomposer. ​​​​​​​​​​​​​The following describes the analytical apparatus 100 according to the first embodiment. The analytical apparatus 100 is a device that analyzes ozone (O3) contained in a measurement atmosphere such as air, which absorbs light having wavelengths in the ultraviolet region (referred to as ultraviolet light). Specifically, the analytical apparatus 100 alternately introduces a gas containing ozone (referred to as sample gas Gs) and a gas that does not contain ozone (referred to as reference gas Gr) into the measurement cell 1, and performs ozone analysis based on the intensity of the measurement light L after passing through the measurement cell 1 into which the sample gas Gs has been introduced and the intensity of the measurement light L after passing through the measurement cell 1 into which the reference gas Gr has been introduced.

[0029] Sample gas Gs may contain substances other than ozone that absorb ultraviolet light. Examples of gases that absorb ultraviolet light include hydrocarbons (volatile organic compounds, VOCs) such as sulfur dioxide (SO2) and toluene (C7H8). Furthermore, water (H2O) in sample gas Gs can cause refraction and scattering of ultraviolet light, potentially affecting the ozone analysis results. To accurately analyze ozone using ultraviolet light, it is preferable that the reference gas Gr does not contain ozone but contains the above-mentioned substances that cause absorption, refraction, and scattering of ultraviolet light in amounts similar to that of the sample gas Gs.

[0030] In the analytical instrument 100, an ozone decomposer 71 is used to remove ozone from the sample gas Gs and generate a reference gas Gr. As will be explained in detail below, the ozone decomposer 71 can efficiently decompose and remove ozone from the sample gas Gs, while removing almost none of the ultraviolet light-absorbing substances mentioned above. In other words, the ozone decomposer 71 can generate a reference gas Gr that is ozone-free but contains ultraviolet light-absorbing substances in a similar amount to the sample gas Gs. As a result, the analytical instrument 100 can accurately analyze ozone.

[0031] (2) Configuration of the analytical instrument The configuration of the analyzer 100 will be explained using Figure 1. Figure 1 is a diagram showing the configuration of the analyzer. The analyzer 100 comprises a measuring cell 1, a light source 3, a detection unit 5, an introduction unit 7, and a control unit 9. The measuring cell 1 is a component having an internal space SP. An inlet 11 connected to the internal space SP is provided at one end of the measuring cell 1, and an outlet 13 connected to the internal space SP is provided at the other end. Sample gas Gs or reference gas Gr is introduced into the internal space SP of the measuring cell 1 from the inlet 11 by the introduction unit 7. The sample gas Gs or reference gas Gr introduced into the internal space SP is discharged from the outlet 13.

[0032] The measurement cell 1 is made of a material that does not interact with ozone, such as glass. If the measurement cell 1 is made of a transparent material such as glass, a thin metal film (for example, a sputtered chromium (Cr) film) is provided on the outer surface of the measurement cell 1. This prevents the measurement light L output from the light source 3 from being reflected off the surface of the measurement cell 1 and from leaking out of the measurement cell 1.

[0033] Light source 3 is an LED (Light Emitting Diode) element positioned at one end of measurement cell 1 and outputs measurement light L toward measurement cell 1. The measurement light L has at least a light component with a wavelength absorbed by the gas to be analyzed. For example, the measurement light L contains at least a light component with a wavelength around 254 nm.

[0034] The detection unit 5 is located on the opposite side of the measurement cell 1 from where the light source 3 is positioned, and detects the measurement light L output from the light source 3 and passing through the internal space SP of the measurement cell 1. The detection unit 5 is, for example, an element capable of detecting the measurement light L, such as a silicon photodiode.

[0035] As shown in Figure 1, an optical filter 51 may be provided between the measurement cell 1 and the detection unit 5. The optical filter 51 allows only the light component of the measurement light L that is absorbed by ozone to pass through. As a result, only the light component of the wavelength absorbed by ozone can be detected by the detection unit 5, and analysis results that are not affected by other light components of the measurement light L can be calculated.

[0036] The introduction unit 7 alternately introduces the sample gas Gs and the reference gas Gr into the internal space SP of the measurement cell 1 at a predetermined interval. Specifically, the introduction unit 7 includes an ozone decomposer 71 and a three-way valve 73. The ozone decomposer 71 removes ozone from the sample gas Gs to generate the reference gas Gr.

[0037] In the analyzer 100, the ozone decomposer 71 is positioned either tilted vertically or vertically. Specifically, it is tilted so that the outlet Out (Figure 2) of the reference gas Gr is above the inlet In (Figure 2) of the sample gas Gs, or it is positioned vertically in this direction. This allows for a constant adjustment of the sedimentation of the packing material inside the ozone decomposer 71 due to gravity (i.e., the first packing member 71c and the second packing member 71d), and a constant density of the packing material. As a result, short-pass (where the sample gas Gs passes through a point with less pressure loss) caused by changes in packing density over time can be prevented, and the ozone decomposition efficiency can be maintained.

[0038] The three-way valve 73 is, for example, a three-way solenoid valve having three gas ports a, b, and c. Gas port a is connected to the inlet 11 of the measuring cell 1. Gas port b is connected to the gas line through which the sample gas Gs is introduced. Specifically, gas port b is connected to a device for collecting the sample gas Gs (e.g., a sampling probe). The sampling flow rate of the sample gas Gs can be, for example, 0.6 L / min.

[0039] Gas port c is connected to the ozone decomposer 71. The three-way valve 73 alternately switches between a state in which gas ports a and b are open for gas flow, and a state in which gas ports a and c are open for gas flow, at a predetermined interval, according to a signal from the control unit 9.

[0040] When gas inlets a and b are open for gas flow, the three-way valve 73 introduces the sample gas Gs into the internal space SP of the measurement cell 1. On the other hand, when gas inlets a and c are open for gas flow, the three-way valve 73 introduces the reference gas Gr generated by the ozone decomposer 71 into the internal space SP of the measurement cell 1. As a result of this switching, the three-way valve 73 can alternately introduce the sample gas Gs and the reference gas Gr into the internal space SP of the measurement cell 1 at a predetermined cycle.

[0041] In this way, by introducing the sample gas Gs and the reference gas Gr alternately into the internal space SP of the measurement cell 1 at a predetermined cycle, it becomes unnecessary to separately provide a detection unit for measuring the intensity of the measurement light L after it has passed through the sample gas Gs and a detection unit for measuring the intensity of the measurement light L after it has passed through the reference gas Gr. That is, a single detection unit 5 can perform both the detection of the measurement light L after it has passed through the sample gas Gs and the detection of the measurement light L after it has passed through the reference gas Gr.

[0042] In the analytical apparatus 100, the above-mentioned gas line is constructed using piping components (e.g., fittings) made of fluororesin (e.g., PTFE).

[0043] The control unit 9 is a computer system equipped with a CPU, storage devices (RAM, ROM, HDD, SSD, etc.), various interfaces, a display, and the like. The control unit 9 has an arithmetic unit 91 and a display unit 93.

[0044] The calculation unit 91 is composed of a CPU, memory device, and various interfaces that make up the control unit 9, and performs processing related to the control of the analyzer 100. Specifically, the calculation unit 91 controls the introduction unit 7 to switch between a state in which gas inlet a and gas inlet b are open (sample gas Gs is introduced into the internal space SP of the measurement cell 1) and a state in which gas inlet a and gas inlet c are open (reference gas Gr is introduced into the internal space SP) at predetermined intervals.

[0045] The calculation unit 91 analyzes the ozone contained in the sample gas Gs based on the measurement light L after it has passed through the sample gas Gs and the measurement light L after it has passed through the reference gas Gr. Specifically, the calculation unit 91 calculates the concentration of ozone contained in the sample gas Gs from the difference or ratio between the intensity of the measurement light L after it has passed through the sample gas Gs and the intensity of the measurement light L after it has passed through the reference gas Gr.

[0046] The arithmetic unit 91 may implement some or all of the above control by executing a program stored in the memory device. Alternatively, the arithmetic unit 91 may implement some or all of the above control in hardware.

[0047] The control unit 9 can notify the user of abnormalities occurring in the analyzer 100 as alarms. Specifically, these include, for example, an alarm notifying the user that the measurement light L has fallen below a predetermined threshold, a zero calibration abnormality alarm indicating that zero calibration is inadequate, a span calibration abnormality alarm indicating that span calibration is inadequate, a communication abnormality alarm indicating that communication between the control unit 9 and the outside is abnormal, a telemeter failure alarm related to a telemeter malfunction, an internal temperature abnormality alarm indicating that the temperature inside the analyzer 100 is abnormal, a cell temperature abnormality alarm indicating that the temperature of the measurement cell 1 is abnormal, an ozone decomposer temperature abnormality alarm indicating that the temperature of the ozone decomposer is abnormal, an atmospheric pressure abnormality alarm indicating that the measurement value of the atmospheric pressure sensor is abnormal, a sample pressure abnormality alarm indicating that the suction pressure for aspirating the sample gas Gs is abnormal, a sample flow rate abnormality alarm indicating that the flow rate of the sample gas Gs is abnormal, and a power supply abnormality alarm indicating that the power supply is abnormal.

[0048] In addition, the control unit 9 can notify the user of "warnings" that are not as serious as alarms but indicate that the state of the analyzer 100 is in a pre-alarm stage. For example, it can set a threshold other than the predetermined threshold for the intensity of the measurement light L, and when the intensity of the measurement light L falls below this threshold, it can notify the user of a warning that "the intensity of the measurement light L is approaching the lower limit (predetermined threshold)." Other warnings that can be notified include, for example, zero calibration warnings, span calibration warnings, battery voltage abnormality warnings related to low clock battery, and internal device temperature warnings.

[0049] Furthermore, the control unit 9 can also notify information indicating the status of the analyzer 100. Examples of information that the analyzer 100 can notify include AIC information indicating that an automatic sequence is being executed, line information indicating that a measurement line is set to something other than measurement, calibration execution information indicating that calibration has been performed, power ON information indicating that the power is ON, and maintenance information indicating that the analyzer 100 is undergoing maintenance.

[0050] The control unit 9 has various interfaces, including a network interface, a serial interface (RS-232C, USB interface, etc.), an analog input / output interface, and a contact input / output interface.

[0051] The analytical instrument 100 having the above configuration can analyze the target gas at high speed (e.g., in 120 seconds or less) with a minimum detection sensitivity (2σ) of 0.5 ppb over such a wide concentration range. Minimum detection sensitivity can be defined as the lowest concentration of the target gas that can be detected by the analytical instrument 100.

[0052] (3) Configuration of the ozone decomposer The configuration of the ozone decomposer 71 will be explained below using Figure 2. Figure 2 is a diagram showing the configuration of the ozone decomposer. The ozone decomposer 71 generates an ozone-free reference gas Gr by heating the sample gas Gs and decomposing and removing the ozone contained in the sample gas Gs. The ozone decomposer 71 has an introduction pipe 71a, a heating section 71b, and a first packing member 71c.

[0053] The inlet pipe 71a is, for example, a cylindrical member made of glass. An inlet In is provided at one end of the cylindrical inlet pipe 71a, and an outlet Out is provided at the other end. The inlet In is connected to the supply line for the sample gas Gs, and the outlet Out is connected to the gas port c of the three-way valve 73. The sample gas Gs is introduced into the internal space of the inlet pipe 71a from the inlet In, and the reference gas Gr generated from the sample gas Gs is discharged from the outlet Out.

[0054] As shown in Figure 2, the inlet pipe 71a is a straight component. This makes the ozone decomposer 71 inexpensive and compact. In addition, other components that allow for a longer flow path for the sample gas Gs can be used as the inlet pipe 71a, such as a U-shaped component or a cross-shaped component.

[0055] The heating section 71b is a heater constructed by winding a heater wire in a coil shape along the outer wall of the introduction pipe 71a. By passing an electric current through the heater wire wound around the outer wall of the introduction pipe 71a, the heating section 71b heats the introduction pipe 71a. As shown in Figure 2, the heater wire constituting the heating section 71b is wound around the central part of the introduction pipe 71a in the longitudinal direction. That is, the heating section 71b heats the central part of the introduction pipe 71a around which the heater wire is wound. The central part of the introduction pipe 71a that is heated by the heating section 71b is called the heated portion of the introduction pipe 71a. By constructing the heating section 71b by winding a heater wire around the outer wall of the introduction pipe 71a, that is, by positioning the heating section 71b outside the introduction pipe 71a, it is possible to prevent, for example, the adsorption of sulfur dioxide and other substances by the heating section 71b.

[0056] Alternatively, for example, the heating section 71b may be configured by attaching a heater to a metal block such as aluminum, and the introduction pipe 71a may be heated by inserting the introduction pipe 71a into this metal block.

[0057] The first packing member 71c is a porous member made of a material inert to ultraviolet light-absorbing substances (i.e., sulfur dioxide, hydrocarbons, and water), and is filled in the internal space of the inlet pipe 71a at the location corresponding to the heated portion of the inlet pipe 71a. The first packing member 71c is, for example, a wool-like member composed of multiple fibers. In the first packing member 71c, multiple fibers are intertwined to form numerous spaces (i.e., porous spaces), through which the sample gas Gs flows. Due to the intertwining of multiple fibers in the wool-like first packing member 71c, the sample gas Gs flows through the first packing member 71c following a complex path. In other words, the sample gas Gs tends to linger in the first packing member 71c, and it takes time for it to pass through the first packing member 71c.

[0058] In this way, the first packing member 71c is filled into the heated portion of the inlet tube 71a, and the sample gas Gs tends to remain in the first packing member 71c. That is, it takes time for the sample gas Gs to pass through the first packing member 71c, which suppresses the temperature drop in the internal space of the inlet tube 71a due to the flow of the sample gas Gs, and also heats the sample gas Gs for a relatively long time. In this way, the temperature drop in the filled portion of the first packing member 71c is suppressed, and the sample gas Gs is heated in this filled portion for a relatively long time, so that the ozone contained in the sample gas Gs can be efficiently decomposed and removed by heating alone, without the use of a metal catalyst.

[0059] By filling the inlet tube 71a with the first packing member 71c, the temperature drop of the packed portion of the first packing member 71c is suppressed, and the sample gas Gs is heated in this packed portion for a relatively long time. Therefore, even if the heating temperature of the inlet tube 71a by the heating unit 71b is low (for example, around 300°C), ozone can be efficiently decomposed and removed inside the inlet tube 71a. By being able to lower the heating temperature of the inlet tube 71a by the heating unit 71b, the generation of products due to the heating of the sample gas Gs can also be suppressed. For example, the generation of thermal decomposition products that occur when hydrocarbon-based substances contained in the sample gas Gs are heated can be suppressed.

[0060] Furthermore, the first filler member 71c is made of a material that is inert to ultraviolet light-absorbing substances (i.e., sulfur dioxide, hydrocarbon-based substances, and water). In other words, the first filler member 71c is made of a material to which the above-mentioned ultraviolet light-absorbing substances do not easily adhere and / or which does not easily interact with such substances to form other substances. Specifically, the first filler member 71c is made of, for example, quartz, glass, or ceramics. In addition, for example, a metal that has been surface-treated so that a material inert to ultraviolet light-absorbing substances is formed on its surface can also be used. Specifically, for example, the first filler member 71c can be made of a metal coated with gold, or a metal such as stainless steel or aluminum with an oxide film, a tempered glass film, and a highly durable chemical modification formed in layers.

[0061] Based on the above, suitable materials for the first filling member 71c include, for example, quartz wool made of multiple quartz fibers. Other suitable materials for the first filling member 71c include ceramic wool made of multiple ceramic fibers and wool made of surface-treated metal fibers. Furthermore, the first filling member 71c, which is made of a wool-like material made of multiple fibers, is easy to fill into the internal space of the introduction pipe 71a, remove from the internal space of the introduction pipe 71a, and replace.

[0062] Thus, in the ozone decomposer 71, no metal catalyst active against sulfur dioxide and / or hydrocarbon-based substances (i.e., substances that absorb ultraviolet light) is used, and the first packing member 71c is composed of a substance that is inert to substances that absorb ultraviolet light (sulfur dioxide, hydrocarbon-based substances, etc.). As a result, substances that absorb ultraviolet light are less likely to be removed from the sample gas Gs, and the ozone decomposer 71 can produce a more suitable reference gas Gr in which the above-mentioned substances contained in the sample gas are not excessively removed.

[0063] The ozone decomposer 71 has a second packing member 71d. The second packing member 71d is packed on the outlet side (Out) of the inlet pipe 71a and is made of a material that adsorbs products generated by heating the sample gas Gs. When the sample gas Gs is heated, some of the hydrocarbon substances contained in the sample gas Gs react to produce volatile organic compounds. If these products are present in the reference gas Gr, they may affect the analyzer 100. For example, these products may adhere to the inner wall of the measurement cell 1, contaminating the measurement cell 1 and affecting the ozone analysis results.

[0064] The second packing member 71d adsorbs the above-mentioned products generated by heating the sample gas Gs, so that the reference gas Gr is almost free of these products, thereby suppressing the adhesion of these products to the inner wall of the measurement cell 1. For example, quartz wool is suitable as such a second packing member 71d. In a comparative example, when the second packing member 71d was made of fluororesin (PTFE), it was not possible to efficiently adsorb the above-mentioned products.

[0065] The ozone decomposer 71 has an insulating member 71e. The introduction pipe 71a is fixed to the insulating member 71e by a mounting member 71f. The insulating member 71e prevents heat from the heating section 71b from being radiated to the surroundings, thereby preventing excessive heating of parts other than the ozone decomposer 71.

[0066] (4) Analysis operation of the target gas by the analyzer The analysis operation of the analyzer 100 for ozone will be explained below using Figure 3. Figure 3 is a flowchart of the analysis operation for ozone. First, the analyzer 100 is warmed up for a predetermined time (step S1). Specifically, the heating unit 71b of the ozone decomposer 71 is operated to heat the inlet tube 71a to a predetermined temperature. The higher the heating temperature, the better the decomposition efficiency of the ozone contained in the sample gas Gs, but it is preferable that the heating temperature of the inlet tube 71a be set so that the analyzer 100 is not overheated. Specifically, the heating temperature of the inlet tube 71a is preferably in the range of 150°C to 400°C, more preferably in the range of 200°C to 350°C, and even more preferably in the range of 270°C to 330°C. The heating temperature of the inlet tube 71a can be, for example, 300°C.

[0067] Subsequently, the calculation unit 91 of the control unit 9 controls the light source 3 and outputs measurement light L from the light source 3 toward the internal space SP of the measurement cell 1 (step S2).

[0068] Next, sample gas Gs and reference gas Gr are alternately introduced into the internal space SP of the measurement cell 1 at a predetermined interval. Based on the measurement light L detected by the detection unit 5 after passing through the sample gas Gs and the measurement light L detected by the detection unit 5 after passing through the reference gas Gr, the ozone contained in the sample gas Gs is analyzed. Specifically, the following steps are performed.

[0069] First, the calculation unit 91 opens the gas ports a and c of the three-way valve 73 to allow gas flow and introduces the reference gas Gr into the internal space SP of the measurement cell 1 (step S3). Specifically, by opening the gas ports a and c of the three-way valve 73 to allow gas flow, the sample gas Gs is introduced into the introduction pipe 71a which has been heated to the above temperature. The sample gas Gs introduced into the introduction pipe 71a passes through the first packing member 71c. As the sample gas Gs passes through the first packing member 71c, it is heated, and the ozone contained in the sample gas Gs is decomposed by the heating, generating an ozone-free reference gas Gr. Subsequently, the reference gas Gr generated in the introduction pipe 71a is introduced into the measurement cell 1 via the three-way valve 73.

[0070] Next, the measurement light L that has passed through the measurement cell 1 with the reference gas Gr introduced into the internal space SP is detected by the detection unit 5 (step S4). This allows information about the measurement light L after passing through the reference gas Gr (the intensity of the measurement light L) to be obtained.

[0071] After obtaining information about the measurement light L after it has passed through the reference gas Gr, the calculation unit 91 opens the gas ports a and b of the three-way valve 73 to allow gas flow and introduces the sample gas Gs into the internal space SP of the measurement cell 1 (step S5). Next, the detection unit 5 detects the measurement light L that has passed through the measurement cell 1 with the sample gas Gs introduced into the internal space SP (step S6). This allows information about the measurement light L after it has passed through the sample gas Gs to be obtained.

[0072] After obtaining information on the measurement light L after passing through the reference gas Gr, the calculation unit 91 analyzes the ozone contained in the sample gas Gs based on the information on the measurement light L after passing through the reference gas Gr obtained in step S4 and the information on the measurement light L after passing through the sample gas Gs obtained in step S6 (step S7). Specifically, the calculation unit 91 calculates the concentration of ozone contained in the sample gas Gs based on the difference or ratio between the intensity of the measurement light L after passing through the reference gas Gr and the intensity of the measurement light L after passing through the sample gas Gs.

[0073] In the analyzer 100, steps S3 to S7 described above are repeatedly performed until the ozone analysis is completed (i.e., until "Yes" is answered in step S8).

[0074] 2. Characteristics of the Embodiment The above embodiment can also be described as follows. (1) The analyzer (e.g., analyzer 100) comprises a measuring cell (e.g., measuring cell 1), a light source (e.g., light source 3), a detection unit (e.g., detection unit 5), a calculation unit (e.g., calculation unit 91), and an ozone decomposer (e.g., ozone decomposer 71). A sample gas (e.g., sample gas Gs) and a reference gas (e.g., reference gas Gr) are alternately introduced into the measuring cell. The reference gas is a gas that does not contain ozone. The light source outputs measuring light (e.g., measuring light L) toward the measuring cell. The detection unit detects the measuring light that has passed through the measuring cell. The calculation unit analyzes the ozone contained in the sample gas based on the measuring light after it has passed through the sample gas and the measuring light after it has passed through the reference gas. The ozone decomposer generates a reference gas by decomposing the ozone contained in the sample gas through heating.

[0075] In the analytical apparatus described above, the ozone decomposer includes an introduction tube (e.g., introduction tube 71a), a heating section (e.g., heating section 71b), and a first packing member (e.g., first packing member 71c). The introduction tube introduces the sample gas. The heating section heats the introduction tube. The first packing member is a porous member made of a substance inert to sulfur dioxide, which is filled into the heated portion of the introduction tube by the heating section.

[0076] In the ozone decomposer of the analytical apparatus described above, since the first packing member is porous, the sample gas introduced into the inlet tube tends to accumulate in the packed portion of the first packing member. The packed portion of the first packing member is heated by the heating section, but because the sample gas accumulates in the packed portion of the first packing member (i.e., it takes time for the sample gas to pass through the first packing member), the temperature drop in the packed portion is suppressed, and the sample gas is heated for a relatively long time. In this way, the temperature drop in the packed portion of the first packing member is suppressed, and the sample gas is heated for a relatively long time, so that the ozone contained in the sample gas can be efficiently decomposed and removed by heating alone, without the use of a metal catalyst.

[0077] Furthermore, by filling the inlet tube with the first packing material, the temperature drop of the packed portion of the first packing material is suppressed, and the sample gas is heated in this packed portion for a relatively long time. As a result, ozone can be efficiently decomposed and removed even if the heating temperature of the inlet tube by the heating unit is lowered. Lowering the heating temperature of the inlet tube by the heating unit also suppresses the generation of products due to the heating of the sample gas.

[0078] Furthermore, in the above-described ozone decomposer, no metal catalyst active against sulfur dioxide is used, and the first packing material filling the inlet tube is made of a substance inert to sulfur dioxide. As a result, sulfur dioxide that absorbs measurement light is less likely to be removed from the sample gas, so the above-described ozone decomposer can produce a more suitable reference gas in which sulfur dioxide contained in the sample gas is not excessively removed.

[0079] (2) In the analytical apparatus described in (1) above, the first packing member may be made of a substance that is inert to hydrocarbons. This makes it more difficult to remove hydrocarbons that absorb the measurement light from the sample gas, and thus a more suitable reference gas can be produced in which hydrocarbons contained in the sample gas are not excessively removed.

[0080] (3) In the analytical apparatus described in (1) or (2) above, the first packing member may be made of quartz wool. This makes it easier for the sample gas to accumulate in the packed portion of the first packing member.

[0081] (4) Any of the ozone decomposers described in (1) to (3) above may further include a second packing member (for example, a second packing member 71d). The second packing member is a member made of a substance that is packed into the outlet side of the inlet tube (for example, outlet Out) and adsorbs products generated by heating the sample gas. This suppresses the effect of such products on the analytical instrument.

[0082] (5) In the analytical apparatus described in (4) above, the second packing member may be made of quartz wool. This allows for more efficient adsorption of products generated by heating the sample gas.

[0083] (6) In any of the analytical apparatuses described in (1) to (5) above, the heating temperature of the inlet tube may be 300°C or higher. This allows ozone to be efficiently decomposed and removed from the sample gas.

[0084] (7) In any of the analytical apparatuses described in (1) to (6) above, the light source may be an LED that outputs ultraviolet light as the measurement light. Since LEDs output ultraviolet light with a relatively wide spectral width, if sulfur dioxide is excessively removed from the sample gas and a reference gas is generated, it may affect the analysis of ozone using ultraviolet light. The ozone decomposer in the above analytical apparatus suppresses the removal of excessive sulfur dioxide from the sample gas, so even if an LED is used as the light source for the measurement light, which is ultraviolet light, ozone can be analyzed accurately.

[0085] (8) The analytical method is a method of analyzing ozone contained in a sample gas using measuring light. The analytical method comprises the following steps. ◎A step of heating the inlet tube (for example, step S3). ◎The step of introducing the sample gas into the introduction tube (for example, step S3). ◎A step (for example, step S3) in which the sample gas is passed through a porous first packing member made of a substance inert to sulfur dioxide, which is filled in the heated portion of the inlet tube, and the ozone contained in the sample gas is decomposed by heating to generate an ozone-free reference gas. ◎A step in which the measurement light is passed through a reference gas and the measurement light after passing through the reference gas is detected (for example, step S4). ◎A step in which measurement light is passed through the sample gas and the measurement light after passing through the sample gas is detected (for example, steps S5 to S6). ◎A step (e.g., step S7) in which the ozone contained in the sample gas is analyzed based on the measurement light detected after passing through the sample gas and the measurement light detected after passing through the reference gas.

[0086] In the analysis method described above, since the first packing member is porous, the sample gas introduced into the inlet tube tends to accumulate in the packed portion of the first packing member in the inlet tube. The packed portion of the first packing member is heated by the heating of the inlet tube, but the accumulation of the sample gas in the packed portion of the first packing member suppresses the temperature drop in the packed portion, and the sample gas is heated for a relatively long time. In this way, the temperature drop in the packed portion of the first packing member is suppressed, and the sample gas is heated for a relatively long time, allowing ozone contained in the sample gas to be efficiently decomposed and removed by heating alone, without the use of a metal catalyst.

[0087] Furthermore, by filling the inlet tube with the first packing material, the temperature drop of the packed portion of the first packing material is suppressed, and the sample gas is heated in this packed portion for a relatively long time. As a result, ozone can be efficiently decomposed and removed even if the heating temperature of the inlet tube is lowered. Lowering the heating temperature of the inlet tube also suppresses the generation of products due to the heating of the sample gas.

[0088] (9) When analyzing ozone contained in a sample gas based on measurement light detected after passing the sample gas and measurement light detected after passing an ozone-free reference gas, the ozone decomposer generates a reference gas by decomposing the ozone contained in the sample gas by heating. The ozone decomposer comprises an introduction tube, a heating section, and a first filling member. The introduction tube introduces the sample gas. The heating section heats the introduction tube. The first filling member is a porous member made of a substance inert to sulfur dioxide, which is filled into the heated portion of the introduction tube by the heating section.

[0089] In the ozone decomposer described above, since the first packing member is porous, the sample gas introduced into the inlet tube tends to accumulate in the packed portion of the first packing member. The packed portion of the first packing member is heated by the heating section, but the accumulation of the sample gas in the packed portion of the first packing member suppresses the temperature drop in the packed portion, and the sample gas is heated for a relatively long time. In this way, the temperature drop in the packed portion of the first packing member is suppressed, and the sample gas is heated for a relatively long time, allowing the ozone contained in the sample gas to be efficiently decomposed and removed by heating alone, without the use of a metal catalyst.

[0090] Furthermore, by filling the inlet tube with the first packing material, the temperature drop of the packed portion of the first packing material is suppressed, and the sample gas is heated in this packed portion for a relatively long time. As a result, ozone can be efficiently decomposed and removed even if the heating temperature of the inlet tube by the heating unit is lowered. Lowering the heating temperature of the inlet tube by the heating unit also suppresses the generation of products due to the heating of the sample gas.

[0091] 3. Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple embodiments and modifications described herein can be arbitrarily combined as needed. (A) In the analysis operation described using the flowchart in Figure 3, the order of processing and the content of processing for each step in the flowchart in Figure 3 can be changed as appropriate without departing from the spirit of the invention.

[0092] (B) At the start of the analysis, a constant current may be input to the light source 3, and when the intensity of the measurement light L output from the light source 3 with a constant current input falls below a predetermined threshold, the current input to the light source 3 may be increased. This extends the usable time of the light source 3.

[0093] (C) The above technology can also be applied to an analytical apparatus in which a sample gas Gs is introduced into measurement cell 1, while another cell is provided into which a reference gas Gr is introduced, and the measurement light L that has passed through each cell is detected by separate detection units.

[0094] (D) In ​​addition to the components described above, the analyzer 100 may also be equipped with, for example, a filter to remove dust and other particles from the sample gas, and a component to remove moisture from the gas introduced into the internal space SP of the measurement cell 1 (such as a mist trap). [Industrial applicability]

[0095] This invention can be widely applied to analytical devices that analyze ozone based on the measurement light after passing through a sample gas and the measurement light after passing through a reference gas that does not contain ozone. [Explanation of symbols]

[0096] 100: Analyzer 1: Measurement cell 11: Entrance 13:Exit SP: Internal space 3:Light source 5: Detection unit 51: Optical filter 7: Introduction 71: Ozone decomposer 71a:Introduction pipe 71b: Heating section 71c: First filling member 71d: Second filling member 71e: Insulation material 71f: Mounting components In: entrance Out :Exit 73: Three-way valve 9: Control Unit 91: Arithmetic section 93: Display section Gr: Reference gas Gs: Sample gas L: Measuring light

Claims

1. An analytical device for analyzing ozone contained in a sample gas, A measurement cell into which the aforementioned sample gas and an ozone-free reference gas are alternately introduced, A light source that outputs measurement light toward the aforementioned measurement cell, A detection unit for detecting the measurement light that has passed through the measurement cell, A calculation unit analyzes the ozone contained in the sample gas based on the measurement light detected by the detection unit after the sample gas has passed through and the measurement light detected by the detection unit after the reference gas has passed through. An ozone decomposer that generates the reference gas by decomposing the ozone contained in the sample gas by heating, Equipped with, The aforementioned ozone decomposer is An introduction tube for introducing the aforementioned sample gas, A heating section for heating the aforementioned introduction pipe, A porous first filling member made of a substance inert to sulfur dioxide is filled into the heated portion of the introduction tube by the heating unit, An analytical device having the following features.

2. The analytical apparatus according to claim 1, wherein the first filling member is made of a substance that is inert to hydrocarbons.

3. The analytical apparatus according to claim 1 or 2, wherein the first packing member is made of quartz wool.

4. The analytical apparatus according to any one of claims 1 to 3, wherein the ozone decomposer further comprises a second filling member made of a substance that is filled on the outlet side of the introduction tube and adsorbs products generated by heating the sample gas.

5. The analytical apparatus according to claim 4, wherein the second packing member is made of quartz wool.

6. The analytical apparatus according to any one of claims 1 to 5, wherein the heating temperature of the introduction tube is 150°C to 400°C.

7. The analytical apparatus according to any one of claims 1 to 6, wherein the light source is an LED that outputs ultraviolet light as the measurement light.

8. An analytical method for analyzing ozone contained in a sample gas using measuring light, The steps include heating the inlet tube and The steps include introducing the sample gas into the introduction tube, The step of passing the sample gas through a porous first packing member made of a substance inert to sulfur dioxide, which is filled in the heating portion of the introduction tube, thereby decomposing the ozone contained in the sample gas by heating and generating an ozone-free reference gas, The steps include passing the measurement light through the reference gas and detecting the measurement light after it has passed through the reference gas, The steps include passing the measurement light through the sample gas and detecting the measurement light after it has passed through the sample gas, A step of analyzing the ozone contained in the sample gas based on the measurement light detected after passing through the sample gas and the measurement light detected after passing through the reference gas. An analytical method that includes the following features.

9. In an ozone decomposer for analyzing ozone contained in a sample gas based on measurement light detected after passing through the sample gas and measurement light detected after passing through an ozone-free reference gas, the ozone decomposer generates the reference gas by decomposing the ozone contained in the sample gas by heating, An introduction tube for introducing the aforementioned sample gas, A heating section for heating the aforementioned introduction pipe, A porous first filling member made of a substance inert to sulfur dioxide is filled into the heated portion of the introduction tube by the heating unit, An ozone decomposer equipped with this feature.

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