Total nitrogen measurement device

Abstract

The present invention comprises: a thermal decomposition unit (2) for thermally decomposing a nitrogen component in a sample so as to generate a sample gas that contains nitrogen monoxide; a reaction unit (4) which includes a reaction space (12) for reacting the nitrogen monoxide in the sample gas generated by the thermal decomposition unit (2) with an ozone gas so as to generate light, a sample gas introduction flow path (14) for introducing the sample gas into the reaction space (12), an ozone gas introduction flow path (16) for introducing the ozone gas into the reaction space (12), and window (18) for transmitting and guiding the light generated in the reaction space (12) to the outside; and an optical sensor (8) for detecting the light transmitted through the window (18). The ozone gas introduction flow path (16) of the reaction unit (4) is provided so as to form a flow of the ozone gas along the window (18) in a vicinity region (A) of the window (18) by introducing the ozone gas toward the vicinity region (A).

Description

Total Nitrogen Measuring Device

[0001] The present invention relates to a total nitrogen measuring device.

[0002] As a total nitrogen measuring device, there is a device that measures total nitrogen by the thermal decomposition / chemiluminescence method (chemiluminescence method). Such a total nitrogen measuring device thermally decomposes the nitrogen component contained in a sample to generate nitric oxide (NO), and then introduces the sample gas containing the generated nitric oxide into a reaction space to which ozone gas is supplied, and reacts the nitric oxide with ozone (O ３ ) to excite it (NO + O ３ → NO ２ ＊ + O ２ ), and the amount of nitrogen component contained in the sample is quantified by detecting, with a light sensor outside the reaction space, the intensity of the light emitted when the excited nitrogen dioxide (NO ２ ＊ ) returns to the ground state (NO ２ 0])

[0003] An object of the present invention is to improve the detection sensitivity of a total nitrogen measuring device using the above-described thermal decomposition / chemiluminescence method.

[0004] In a total nitrogen measuring device using the thermal decomposition / chemiluminescence method, the light emitted from nitric oxide in the excited sample gas in the reaction part is taken out through a window provided in the reaction part and detected by a light sensor. Considering increasing the intensity of the light detected by the light sensor to improve the detection sensitivity, it is preferable to introduce the sample gas to a position as close to the window as possible and react nitric oxide with ozone in a region close to the window. However, when the sample gas is introduced to a position close to the window, there is a problem that the sample gas contacts the window and contaminants in the sample gas adhere to the window, and the amount of light transmitted through the window decreases, resulting in a decrease in detection sensitivity.

[0005] To solve the above problems, the first total nitrogen measuring device according to the present invention comprises: a pyrolysis unit that pyrolyzes nitrogen components in a sample to produce a sample gas containing nitric oxide; a reaction unit having a reaction space for generating light by reacting the nitric oxide in the sample gas produced in the pyrolysis unit with ozone gas; a sample gas introduction channel for introducing the sample gas into the reaction space; an ozone gas introduction channel for introducing ozone gas into the reaction space; and a window for transmitting the light generated in the reaction space to the outside; and a light sensor for detecting the light transmitted through the window, wherein the ozone gas introduction channel of the reaction unit is provided to introduce ozone gas toward the vicinity of the window, thereby forming an ozone gas flow along the window in the vicinity region.

[0006] Furthermore, the intensity of light detected by the light sensor located outside the window changes depending on whether the location where nitric oxide in the sample gas is excited by ozone is close to or far from the window of the reaction section. Therefore, in order to improve detection sensitivity, it is preferable to stably react nitric oxide with ozone in a location close to the window.

[0007] Therefore, the second total nitrogen measuring device according to the present invention comprises: a pyrolysis unit that pyrolyzes nitrogen components in a sample to produce a sample gas containing nitric oxide; a reaction unit having a reaction space for generating light by reacting the nitric oxide in the sample gas produced in the pyrolysis unit with ozone gas; a sample gas introduction channel for introducing the sample gas into the reaction space; an ozone gas introduction channel for introducing ozone gas into the reaction space; and a window for transmitting the light generated in the reaction space to the outside; and a light sensor for detecting the light transmitted through the window, wherein the reaction space of the reaction unit has a side surface perpendicular to the window, the end of the sample gas introduction channel is provided on the side surface, and the reaction space of the reaction unit has an inner wall surface facing the window at a position where the distance from the end of the sample gas introduction channel is shorter than the window.

[0008] According to the first total nitrogen measuring device of the present invention, the ozone gas introduction channel in the reaction section is provided such that ozone gas is introduced toward the vicinity of the window, thereby forming an ozone gas flow along the window in the vicinity. This makes it difficult for contaminants in the sample gas to adhere to the window, and the window is less likely to be soiled by the sample gas. As a result, the detection sensitivity is improved.

[0009] According to the second total nitrogen measuring device of the present invention, the reaction space of the reaction section is provided with an inner wall surface facing the window at a position shorter than the window's distance from the sample gas introduction channel. As a result, the sample gas introduced through the sample gas introduction channel does not flow to a position far from the window. This allows nitric oxide to react stably with ozone in a location close to the window, improving detection sensitivity.

[0010] Furthermore, the configurations of the first total nitrogen measuring device and the second total nitrogen measuring device described above can be combined with each other, and combining these configurations increases the effect of improving detection sensitivity.

[0011] This is a schematic diagram showing one embodiment of a total nitrogen measuring device. This diagram shows the direction of introduction of sample gas and ozone gas into the reaction space in the same embodiment. This diagram explains the flow of sample gas and ozone gas within the reaction space in the same embodiment. This diagram shows a modified arrangement of the ozone gas introduction channel in the reaction section. This graph shows the results of verification regarding the effect of the position of the inner wall surface of the reaction space facing the window on detection sensitivity.

[0012] An embodiment of the total nitrogen measuring device according to the present invention will be described below with reference to the drawings.

[0013] The total nitrogen measuring device 1 comprises a pyrolysis unit 2, a reaction unit 4, an ozone gas source 6, a light sensor 8, and a calculation unit 10.

[0014] The pyrolysis unit 2 performs thermal decomposition of nitrogen components in the sample to produce a sample gas containing nitric oxide. The sample gas produced in the pyrolysis unit 2 is introduced into the reaction space 12 located inside the reaction unit 4.

[0015] The reaction section 4 includes a reaction space 12, a sample gas introduction channel 14, an ozone gas introduction channel 16, a window 18, and an exhaust channel 22.

[0016] The reaction space 12 is a cylindrical space located inside the reaction section 4, used to excite nitric oxide in the sample gas by reacting it with ozone gas.

[0017] The sample gas introduction channel 14 is a channel for introducing the sample gas into the reaction space 12, and the ozone gas introduction channel 16 is a channel for introducing ozone gas supplied from the ozone gas source 6 into the reaction space 12.

[0018] Window 18 forms a wall that demarcates the reaction space 12 and is a transparent window that transmits light emitted from nitric oxide excited in the reaction space 12 to the outside. Window 18 is made of, for example, quartz glass or borosilicate glass.

[0019] The discharge channel 22 is a channel for discharging gas from the reaction space 12 to the outside. In this embodiment, the end of the discharge channel 22 on the reaction space 12 side is provided on the inner wall surface 20 facing the window 18.

[0020] The light sensor 8 is positioned outside the reaction space 12, near the window 18, to receive light emitted from nitric oxide excited within the reaction space 12 and transmitted through the window 18. The light sensor 8 outputs a signal corresponding to the intensity of the light transmitted through the window 18. The signal output from the light sensor 8 is ultimately input to the calculation unit 10. The calculation unit 10 is configured to quantify the nitric oxide concentration in the sample gas based on the output signal from the light sensor 8. The calculation unit 10 is implemented by a computer circuit equipped with a CPU (Central Processing Unit) and the like.

[0021] The end 15 of the sample gas introduction channel 14 on the reaction space 12 side, and the end 17 of the ozone gas introduction channel 14 on the reaction space 12 side, are each provided on the side surface 21 of the reaction space 12 perpendicular to the window 18.

[0022] As shown in Figure 2, the sample gas introduction channel 14 and the ozone gas introduction channel 16 are provided to introduce the sample gas and ozone gas along the side surface 21 of the reaction space 12 so that the sample gas and ozone gas flow in the same direction in a swirling motion within the reaction space 12.

[0023] As shown in Figure 3, the ozone gas introduction channel 16 is provided to introduce ozone gas toward the vicinity region A of the window 18 in the reaction space 12. In this embodiment, the ozone gas introduction channel 16 is inclined with respect to the side surface 21 to introduce ozone gas into the reaction space 12 in a direction toward the window 18. By introducing ozone gas toward the vicinity region A, an ozone gas flow is formed in the vicinity region A along the window 18, making it difficult for the sample gas introduced into the reaction space 12 through the sample gas introduction channel 14 to come into contact with the window 18, thereby suppressing contamination of the window 18 with sample gas.

[0024] Furthermore, as shown in Figure 4, if structurally possible, the ozone gas introduction channel 16 may be provided perpendicular to the side surface 21 so that the ozone gas is introduced along the window 18. Even with such a structure, an ozone gas flow can be formed in the area A near the window 18, and contamination of the window 18 with sample gas is suppressed.

[0025] Returning to Figure 3, in this embodiment, the sample gas introduction channel 14 is also inclined with respect to the side surface 21, so that the sample gas is introduced into the reaction space 12 in a direction that approaches the window 18. By introducing the sample gas into the reaction space 12 in a direction that approaches the window 18, the nitric oxide in the sample gas can be reacted with ozone at a position close to the window 18 within the reaction space 12. This improves the intensity of light detected by the light sensor 8 and enhances the detection sensitivity.

[0026] In the example shown in Figure 3, the distance from the end 15 of the sample gas introduction channel 14 to the window 18 is the same as the distance from the end 17 of the ozone gas introduction channel 16 to the window 18, and the inclination angles of the sample gas introduction channel 14 and the ozone gas introduction channel 16 with respect to the side surface 21 are the same, but the present invention is not limited thereto. To facilitate the formation of a layer of ozone gas only in the area A near the window 18, the distance from the end 17 of the ozone gas introduction channel 16 to the window 18 may be shorter than the distance from the end 15 of the sample gas introduction channel 14 to the window 18, or the inclination angle of the ozone gas introduction channel 16 with respect to the side surface 21 may be greater than the inclination angle of the sample gas introduction channel 14 with respect to the side surface 21.

[0027] In a total nitrogen measuring device using the pyrolysis / chemiluminescence method, it is generally desirable to introduce the sample gas into the reaction space 12 in an ozone-rich state. Therefore, the flow rate of ozone gas introduced into the reaction space 12 is greater than the flow rate of the sample gas. For example, the flow rate of ozone gas can be set to 500 mL / min and the flow rate of sample gas to 150 mL / min. As a result, even if the sample gas is introduced from the sample gas introduction channel 14 toward the window 18, a large flow of ozone gas is formed in the region A near the window 18 in the reaction space 12, as described above, making it difficult for the sample gas to come into contact with the window 18. In this way, by forming a flow of ozone gas in the region A near the window 18, it is possible to introduce the sample gas toward the window 18 and react nitric oxide with ozone at a position close to the window 18 while suppressing contamination of the window 18 by the sample gas.

[0028] Furthermore, as shown in Figure 3, the distance L1 (for example, 1.4 mm) between the inner wall surface 20 of the reaction space 12 facing the window 18 and the center of the end 15 of the sample gas introduction channel 14 is shorter than the distance L2 (for example, 3.6 mm) between the window 18 and the center of the end 15 of the sample gas introduction channel 14. In other words, the inner wall surface 20 facing the window 18 is located closer to the end 15 of the sample gas introduction channel 14 than to the window 18, making it easier for the sample gas introduced into the reaction space 12 through the sample gas introduction channel 14 to remain closer to the window 18. As a result, the position where nitric oxide in the sample gas reacts with ozone stabilizes closer to the window 18, and the intensity of light detected by the photosensor 8 improves.

[0029] Figure 5 is a graph showing the results of a verification of the effect of the position of the inner wall surface of the reaction space facing the window on the detection sensitivity. In Figure 5, the horizontal axis represents the concentration of nitric oxide gas, and the vertical axis represents the amplification value of the output signal of the photosensor 8 by the operational amplifier. In this verification, nitric oxide gas was measured using two reaction sections: one in which the distance L1 (1.4 mm) between the inner wall surface 20 and the center of the end 15 of the sample gas introduction channel 14 was shorter than the distance L2 (3.6 mm) between the window 18 and the center of the end 15 of the sample gas introduction channel 14 (Example), and another in which the distance L1 (26.4 mm) between the inner wall surface 20 and the center of the end 15 of the sample gas introduction channel 14 was longer than the distance L2 (3.6 mm) between the window 18 and the center of the end 15 of the sample gas introduction channel 14 (Comparative Example).

[0030] From the verification in Figure 5, it can be seen that by bringing the inner wall surface 20 facing the window 18 closer to the end 15 of the sample gas introduction channel 14, the position where nitric oxide reacts with ozone stabilizes closer to the window 18, and the intensity of light detected by the light sensor 8 improves.

[0031] The embodiments described above are merely examples of embodiments of the total nitrogen measuring device according to the present invention. Embodiments of the total nitrogen measuring device according to the present invention are as follows.

[0032] In a first embodiment of the total nitrogen measuring device according to the present invention, the device comprises: a pyrolysis unit that pyrolyzes nitrogen components in a sample to produce a sample gas containing nitric oxide; a reaction unit having a reaction space for generating light by reacting the nitric oxide in the sample gas produced in the pyrolysis unit with ozone gas; a sample gas introduction channel for introducing the sample gas into the reaction space; an ozone gas introduction channel for introducing ozone gas into the reaction space; and a window for transmitting the light generated in the reaction space to the outside; and a light sensor for detecting the light transmitted through the window, wherein the ozone gas introduction channel of the reaction unit is provided to form an ozone gas flow along the window in the vicinity region by introducing ozone gas toward the vicinity region of the window.

[0033] In one specific embodiment of the first embodiment described above, the reaction space of the reaction section has a side surface perpendicular to the window, and the ozone gas introduction channel is inclined with respect to the side surface and connects to the side surface so as to introduce ozone gas in a direction approaching the window.

[0034] In one specific embodiment described above, the sample gas introduction channel may be inclined with respect to the side surface so as to introduce the sample gas in a direction toward the window.

[0035] In a second embodiment of the total nitrogen measuring device according to the present invention, the device comprises: a pyrolysis unit that pyrolyzes nitrogen components in a sample to produce a sample gas containing nitric oxide; a reaction unit having a reaction space for generating light by reacting the nitric oxide in the sample gas produced in the pyrolysis unit with ozone gas; a sample gas introduction channel for introducing the sample gas into the reaction space; an ozone gas introduction channel for introducing ozone gas into the reaction space; and a window for transmitting the light generated in the reaction space to the outside; and a light sensor for detecting the light transmitted through the window, wherein the reaction space of the reaction unit has a side surface perpendicular to the window, the end of the sample gas introduction channel is provided on the side surface, and the reaction space of the reaction unit has an inner wall surface facing the window at a position shorter than the window at the distance from the end of the sample gas introduction channel.

[0036] 1 Total nitrogen measuring device 2 Pyrolysis unit 4 Reaction unit 6 Ozone gas source 8 Optical sensor 10 Calculation unit 12 Reaction space 14 Sample gas introduction channel 15 End of sample gas introduction channel 16 Ozone gas introduction channel 17 End of ozone gas introduction channel 18 Window 20 Inner wall surface facing the window 22 Discharge channel

Claims

1. A total nitrogen measuring device comprising: a pyrolysis unit that pyrolyzes nitrogen components in a sample to produce a sample gas containing nitric oxide; a reaction unit having a reaction space for generating light by reacting the nitric oxide in the sample gas produced in the pyrolysis unit with ozone gas; a sample gas introduction channel for introducing the sample gas into the reaction space; an ozone gas introduction channel for introducing ozone gas into the reaction space; and a window for transmitting the light generated in the reaction space to the outside; and a light sensor for detecting the light transmitted through the window, wherein the ozone gas introduction channel of the reaction unit is provided to introduce ozone gas toward the vicinity of the window, thereby forming an ozone gas flow along the window in the vicinity region.

2. The total nitrogen measuring device according to claim 1, wherein the reaction space of the reaction section has a side surface perpendicular to the window, and the ozone gas introduction channel is inclined with respect to the side surface and connects to the side surface so as to introduce ozone gas in a direction approaching the window.

3. The total nitrogen measuring device according to claim 2, wherein the sample gas introduction channel is inclined with respect to the side surface so as to introduce the sample gas in a direction toward the window.

4. A total nitrogen measuring device comprising: a pyrolysis unit for pyrolyzing nitrogen components in a sample to produce a sample gas containing nitric oxide; a reaction space for reacting the nitric oxide in the sample gas produced in the pyrolysis unit with ozone gas to generate light; a sample gas introduction channel for introducing the sample gas into the reaction space; an ozone gas introduction channel for introducing ozone gas into the reaction space; and a window for transmitting the light generated in the reaction space to the outside; and a light sensor for detecting the light transmitted through the window, wherein the reaction space of the reaction unit has a side surface perpendicular to the window, the end of the sample gas introduction channel is provided on the side surface, and the reaction space of the reaction unit has an inner wall surface facing the window at a position shorter than the window at the distance from the end of the sample gas introduction channel.

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