JP2017181204A - Ozone measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ozone measurement device that can reduce an indication skip of ozone concentration in sample gas in a configuration of alternately measuring an amount of UV transmission light of the sample gas and an amount of UV transmission light of reference gas to obtain the ozone concentration in the sample gas.SOLUTION: An ozone concentration device 100, which alternately measures an amount of UV transmission light of sample gas and an amount of UV transmission light of reference gas, and sequentially computes a concentration after measuring the sample gas and a concentration after measuring the reference gas, is configured to have a control unit 4 that conducts performing of: every time the concentration after measuring the sample gas and the concentration after measuring the reference gas are computed respectively, obtaining a first index value indicative of a degree of change from previous concentrations after measuring the sample gas of an up to date concentration after measuring the sample gas, and a second index value indicative of a change of degree from previous concentrations after measuring the reference gas of an up to date concentration after measuring the reference gas; when a difference between the first and second index values is equal to or greater than a prescribed threshold, replacing a current-time computed concentration after measuring the sample gas or a current-time computed concentration after measuring the reference gas with a different value based on at least one of a previously computed concentration after measuring the sample gas or a previously computed concentration after measuring the reference gas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ozone measuring device for measuring ozone concentration in the atmosphere or the like.

  2. Description of the Related Art Conventionally, there is an ozone measuring device that measures the ozone concentration in a sample gas by absorbing ultraviolet rays by utilizing the fact that ozone absorbs ultraviolet rays. The ozone measuring device measures the ultraviolet absorbance (ultraviolet transmitted light amount) of the sample gas and the ultraviolet absorbance (ultraviolet transmitted light amount) of the reference gas from which the ozone in the sample gas has been removed, and the ozone in the sample gas is determined from these ratios. The concentration is required. In such an ozone measuring apparatus, a mercury lamp is generally used as the ultraviolet light source.

  However, the mercury lamp has a relatively low light amount stability, and the light amount may suddenly increase or decrease during lighting. Then, when the ozone concentration is obtained using the measurement data when the light quantity of the mercury lamp changes in this way, the indication value of the ozone concentration may become an unrealistic value. Here, this phenomenon is called “instruction skip”.

  To solve this problem, there is a method in which the calculation of the ozone concentration in the sample gas using the ultraviolet absorbance of the reference gas is not performed when the change rate of the ultraviolet absorbance of the reference gas exceeds a predetermined threshold ( Patent Document 1).

JP 2008-175626 A

  However, although the above-described conventional method can achieve a certain effect, there are cases where the skipping of instructions cannot be sufficiently reduced.

  That is, in the above conventional method, attention is paid only to the change in the light amount of the mercury lamp when the amount of ultraviolet light transmitted through the reference gas is measured, and the instruction skip is determined from the magnitude of the change. For this reason, if there is a change in the light amount of the mercury lamp when measuring the amount of ultraviolet light transmitted through the sample gas, it is not possible to determine the skipping. Therefore, the measurement result of the ozone concentration in the sample gas may still show an instruction skip to be reduced.

  Accordingly, an object of the present invention is to reduce the skipping of instructions that occur in the measurement result in a configuration in which the ozone concentration in the sample gas is obtained by alternately measuring the ultraviolet light transmission amount of the sample gas and the ultraviolet light transmission amount of the reference gas. It is to provide an ozone measuring device that can be used.

  The above object is achieved by the ozone measuring apparatus according to the present invention. In summary, the present invention permeates through a measurement unit in which a sample gas and a reference gas from which ozone in the sample gas is removed are alternately introduced, a light source that irradiates the measurement unit with ultraviolet light, and the measurement unit. A detector that receives light and generates an electrical signal according to the amount of light received, sample gas measurement data according to an electrical signal generated by the detector when a sample gas is introduced into the measurement unit, and the measurement A control unit that calculates ozone concentration in the sample gas based on reference gas measurement data corresponding to an electrical signal generated by the detector when a reference gas is introduced into the unit, and the control unit Calculates the concentration after measurement of the sample gas indicating the ozone concentration in the sample gas based on the current sample gas measurement data and the latest reference gas measurement data when the sample gas measurement data is acquired, and the reference Get gas measurement data In this case, after calculating the reference gas measurement concentration indicating the ozone concentration in the sample gas based on the current reference gas measurement data and the latest sample gas measurement data, the concentration after the sample gas measurement or after the reference gas measurement is calculated. Each time the concentration is calculated, a first index value indicating the degree of change of the latest concentration after measurement of the sample gas from the previous concentration after measurement of the sample gas, and that of the concentration after the measurement of the latest reference gas are calculated. A second index value indicating the degree of change from the previous concentration after measurement of the reference gas, and when the difference between the first and second index values is greater than a predetermined threshold, A process of replacing the concentration after measurement of the sample gas or the concentration after measurement of the reference gas with another value based on at least one of the concentration after measurement of the sample gas or the concentration after measurement of the reference gas previously calculated, respectively. An ozone measuring device according to symptoms.

  According to the present invention, in the configuration in which the ultraviolet light transmission amount of the sample gas and the ultraviolet light transmission amount of the reference gas are alternately measured to obtain the ozone concentration in the sample gas, it is possible to reduce the instruction skip occurring in the measurement result.

It is a block diagram of the ozone measuring device which concerns on one Example. It is explanatory drawing for demonstrating the calculation method of the ozone concentration in one Example. It is a graph for demonstrating the problem of instruction skip. It is a graph for demonstrating the typical example of instruction skip. It is a graph for demonstrating the instruction skip correction process in one Example. It is a flowchart which shows the flow of a process of the measurement data in one Example. It is a graph which shows the effect of the instruction skip correction process in one Example. It is a graph for demonstrating the other typical example of instruction skip.

  Hereinafter, the ozone measuring apparatus according to the present invention will be described in more detail with reference to the drawings.

[Example 1]
1. Overall Configuration of Ozone Measuring Device FIG. 1 is a block diagram showing the overall configuration of an ozone measuring device 100 of the present embodiment. In this embodiment, the ozone measuring device 100 is used to measure the ozone concentration in the atmosphere.

  The measuring apparatus 100 includes a sample gas introduction port 11 for introducing a sample gas (air) and an introduction tube 12 through which the sample gas introduced from the sample gas introduction port 11 flows. The introduction tube 12 is connected to a measurement cell 21 of the detection unit 2 described later, and supplies a sample gas to the measurement cell 21. A bypass pipe 13 is connected to the introduction pipe 12 so that a part thereof is shortcut, and an ozonolysis device 14 is connected in the middle of the bypass pipe 13. Valves 15 and 16 for switching the flow path of the sample gas are provided in the middle of each of the introduction pipe 12 and the bypass pipe 13. Further, a clean filter 17 is provided in the middle of the introduction pipe 12 for removing impurities of powder and granular materials from the sample gas introduced into the introduction pipe 12 from the sample gas introduction port 11. In the present embodiment, the sample gas and ozone in the sample gas are removed from the measurement cell 21 by the sample gas introduction port 11, the introduction pipe 12, the bypass pipe 13, the ozonolysis device 14, the valves 15 and 16, the clean filter 17, and the like. The gas supply unit 1 is configured to alternately introduce the reference gas.

  In addition, the measuring device 100 includes a discharge pipe 31 for discharging the gas after measurement, and a discharge port 32. The discharge pipe 31 is connected to the measurement cell 21 and the gas after passing through the measurement cell 21 is introduced. A pump 33 for flowing gas and a flow meter 34 for detecting the flow rate of the gas flowing through the discharge pipe 31 are provided in the middle of the discharge pipe 31. Further, a temperature sensor 35 for detecting the temperature of the gas flowing through the discharge pipe 31 and a pressure sensor 36 for detecting the pressure of the gas flowing through the discharge pipe 31 are provided. In the present embodiment, the discharge pipe 31, the discharge port 32, the pump 33, the flow meter 34, the temperature sensor 35, the pressure sensor 36, and the like constitute the gas discharge unit 3 that discharges the gas that has passed through the measurement cell 21.

  Moreover, the measuring apparatus 100 has the detection part 2 which detects the ozone contained in sample gas. The detection unit 2 receives a measurement cell 21 as a measurement unit into which a sample gas or the like is introduced, a mercury lamp 22 as an ultraviolet light source, and light emitted from the mercury lamp 22 and transmitted through the measurement cell 21 according to the amount of light received. It has a detector (photoelectric converter) 23 that generates an electrical signal. The detector 23 includes a photoelectric conversion element (a photodiode in this embodiment), an amplifier, an AD converter, and the like.

  Furthermore, the ozone measuring device 100 has a control unit 4 that comprehensively controls the operation of the measuring device 100 such as the pump 33, valves 15 and 16, and the detecting unit 2, and that determines the ozone concentration in the sample gas. The control unit 4 includes a CPU as a calculation control unit, a storage unit (memory) as a storage unit, and the like, and controls the operation of each unit of the ozone measuring apparatus 100 according to a program stored in the storage unit. Perform measurement data processing. The ozone measurement apparatus 100 may further include a display unit that displays the measurement result, a transmission unit that transmits the measurement result to an external device that is connected to the measurement apparatus 100 in a communicable manner, and the like.

  Measurement of the ozone concentration in the sample gas by the ozone measuring device 100 is performed as follows.

  (1) The sample gas (air) is sucked into the introduction pipe 12 from the sample gas introduction port 11 by the pump 33 at a constant flow rate, and this sample gas is introduced into the measurement cell 21 by the valves 15 and 16 without passing through the bypass pipe 13. The

  (2) The measurement cell 21 is irradiated with ultraviolet rays having a specific wavelength (254 nm in this embodiment), which is light in the ultraviolet region, from the mercury lamp 22. Thereby, ultraviolet rays according to the concentration of coexisting components that absorb ozone and other ultraviolet rays in the sample gas are absorbed by the sample gas. Ultraviolet light attenuated by passing through the measurement cell 21 into which the sample gas has been introduced is received by the detector 23. The detector 23 generates an electrical signal corresponding to the intensity of the received ultraviolet light (ultraviolet transmitted light amount), and AD-converted measurement data (herein, also referred to as “sample gas measurement data”) is a control unit. 4 The control unit 4 stores the input sample gas measurement data in the storage unit.

  (3) When the gas flow path is switched by the valves 15 and 16 and the sample gas is introduced into the bypass pipe 13, ozone in the sample gas is decomposed (removed) by the ozone decomposer 14, and ozone is removed. Reference gas not included is adjusted. This reference gas is introduced into the measurement cell 21, and the same measurement as in the case of the sample gas (2) is performed. Since the reference gas is adjusted by removing only ozone in the sample gas, in the case of measuring the reference gas, ultraviolet rays corresponding to the concentration of coexisting components other than ozone in the sample gas are absorbed. Ultraviolet light attenuated by passing through the measurement cell 21 introduced with the reference gas is received by the detector 23. The detector 23 generates an electrical signal corresponding to the intensity of the received ultraviolet light (ultraviolet transmitted light amount), and AD-converted measurement data (herein also referred to as “reference gas measurement data”) is a control unit. 4 The control unit 4 stores the input reference gas measurement data in the storage unit.

  (4) The control unit 4 uses the sample gas measurement data and the reference gas measurement data as will be described in detail later, and the sample according to the ratio of the ultraviolet transmitted light amount of the sample gas to the ultraviolet transmitted light amount of the reference gas Obtain the ozone concentration in the gas by calculation. And the control part 4 memorize | stores the measurement result of the ozone concentration in sample gas in a memory | storage part. The control unit 4 may further display the measurement result stored in the storage unit on the display unit or transmit it to an external device.

  By repeating the above operation, the ozone concentration in the sample gas is intermittently measured. As will be described in detail later, the measurement of the UV light transmission amount of the sample gas and the measurement of the UV light transmission amount of the reference gas can be switched, for example, every few seconds. Thus, the ozone concentration in the sample gas can be continuously measured.

2. Calculation of ozone concentration Next, the calculation of the ozone concentration in the ozone measuring apparatus 100 of the present embodiment will be described in more detail. In the present embodiment, the control unit 4 calculates the ozone concentration in the sample gas by the following equation (1) based on Lambert-Beer's law.

  In the above formula (1), Is is sample gas measurement data corresponding to the ultraviolet light transmission amount of the sample gas, Iz is reference gas measurement data corresponding to the ultraviolet light transmission amount of the reference gas, Kg is an absorption coefficient of ozone gas, and L is a measurement cell. 21 is the optical path length (cell length), TMs is the sample gas temperature for correction, and Ps is the pressure of the sample gas for correction.

  The calculation of the ozone concentration is performed after the measurement of the UV light transmission amount of the sample gas and the measurement of the UV light transmission amount of the reference gas while alternately introducing the sample gas and the reference gas into the measurement cell 21. When the gas introduced into the measurement cell 21 is switched from the sample gas to the reference gas or from the reference gas to the sample gas, after a purge period of 3 seconds (a period for replacing the gas in the measurement cell 21), 3 The control unit 4 acquires an average value of measurement data sampled at a predetermined time interval (for example, every 150 ms) during a measurement period of seconds. Therefore, the ozone concentration is updated every 6 seconds. As shown in FIG. 2, after the measurement of the reference gas is completed, the reference gas measurement data acquired this time and the latest sample gas measurement data (that is, acquired one time before (6 seconds before)) Using the above equation (1), the ozone concentration is calculated (here, the ozone concentration calculated at this timing is also referred to as “reference gas post-measurement concentration”). Further, after the measurement of the sample gas is completed, the above-described formula is used by using the sample gas measurement data acquired this time and the latest reference gas measurement data (that is, acquired one time before (6 seconds before)). The ozone concentration is calculated by (1) (here, the ozone concentration calculated at this timing is also referred to as “post-measurement gas concentration”).

3. If the light intensity of the mercury lamp 22 is stable, for example, when a sample gas with a constant ozone concentration (for example, air that does not contain ozone (zero gas)) is introduced into the measurement cell 21, The concentration after the measurement of the reference gas one time before, or the concentration after the measurement of the reference gas this time and the concentration after the measurement of the sample gas one time before should be almost the same.

  However, the light quantity of the mercury lamp 22 may suddenly change during lighting. FIG. 3A shows the measurement data when zero gas is introduced into the measurement cell 21, that is, the result of measuring the change in the light quantity of the mercury lamp 22. In the figure, the vertical axis represents measurement data (AD count value output from the detector 23), and the horizontal axis represents time. As indicated by an arrow in FIG. 3A, the light quantity state of the mercury lamp 22 may change suddenly, and thus the change in the amount of transmitted ultraviolet light when the light quantity of the mercury lamp 22 changes suddenly undergoes density conversion. Then, the indicated value of the ozone concentration in the sample gas becomes an unrealistic value. FIG. 3B shows the measurement result of the ozone concentration of zero gas when the skipping correction process of the present embodiment described later is not performed (the sample gas measurement concentration and the reference gas measurement concentration are plotted alternately. Ozone concentration). In the figure, the vertical axis represents time, and the horizontal axis represents ozone concentration. As shown in FIG. 3B, there is an instruction skip that suddenly increases or decreases in the instruction value of the ozone concentration that should be almost constant in this case.

  FIG. 4 is a graph showing some typical examples of instruction skipping. In the figure, the vertical axis represents ozone concentration and the horizontal axis represents time. In the figure, “♦” is a plot of the concentration after measurement of the sample gas, and “■” is a plot of the concentration after measurement of the reference gas.

  (1) in FIG. 4 shows an example of instruction skipping when the light quantity of the mercury lamp 22 changes to the plus side during the reference gas measurement period. In this case, the instruction gas jumps in the direction that the concentration after measurement of the reference gas calculated immediately increases (the difference between the UV absorbance of the previous sample gas and the UV absorbance of the current reference gas has increased in a pseudo manner) Equivalent to.) Further, in this case, the measurement period of the next sample gas is a transition period until the mercury lamp 22 returns to a stable state. .

  (2) in FIG. 4 shows an example of skipping when the light quantity of the mercury lamp 22 changes to the minus side during the purge period of the sample gas. In this case, the measurement period of the sample gas immediately after is a transitional period until the mercury lamp 22 returns to a stable state, so that the instruction jumps in a direction in which the concentration after measurement of the sample gas calculated immediately after that increases (this time) This corresponds to the fact that the difference between the ultraviolet absorbance of the sample gas and the ultraviolet absorbance of the reference gas one time before has been increased pseudo).

  (3) in FIG. 4 shows an example of skipping when the light quantity of the mercury lamp 22 changes to the plus side during the sample gas measurement period. In this case, the concentration immediately after the measurement of the sample gas calculated immediately jumps in the direction of decreasing (the difference between the UV absorbance of the current sample gas and the UV absorbance of the previous reference gas has been reduced in a pseudo manner) Equivalent to.) In this case, the next reference gas measurement period is a transitional period until the mercury lamp 22 returns to a stable state, and therefore, the next calculated reference gas concentration after the reference gas measurement is skipped. .

  Also, (4) in FIG. 4 shows an example of instruction skipping when the light quantity of the mercury lamp 22 changes to the minus side during the reference gas purge period. In this case, the measurement period of the reference gas immediately after is a transitional period until the mercury lamp 22 returns to a stable state, and thus the instruction skips in a direction in which the concentration after measurement of the reference gas calculated immediately after that decreases (once). This is equivalent to the fact that the difference between the UV absorbance of the previous sample gas and the UV absorbance of the current reference gas has become smaller.)

  In this way, depending on the timing at which the light amount state of the mercury lamp 22 suddenly changes and whether the light amount change is in the positive direction or the negative direction, different indication skips occur in the concentration after the sample gas measurement and the concentration after the reference gas measurement. Therefore, in the method of Patent Document 1 in which only the light quantity change of the mercury lamp 22 when measuring the ultraviolet light transmission quantity of the reference gas is measured and the instruction skip is discriminated from the magnitude of the change, the instruction skip is sufficiently reduced. There are things that cannot be done.

4). Instruction skip correction process In this embodiment, the control unit 4 executes the following instruction skip correction process. That is, according to the above formula (1), the ozone concentration is obtained from the ratio between the ultraviolet light transmission amount of the sample gas and the ultraviolet light transmission light amount of the reference gas, so if the light amount of the mercury lamp 22 is stable, the nearest sample The rate of change of the concentration after gas measurement from the concentration after the previous sample gas measurement is substantially the same as the rate of change from the concentration after the last reference gas measurement of the concentration after the last reference gas measurement. More specifically, it can be estimated that the rate of change between the two is within a predetermined range depending on the measurement target (such as the ozone concentration in the atmosphere or the ozone concentration generated by the ozone generator). However, when the light quantity of the mercury lamp 22 changes greatly, the change rate of the both is greatly different. Therefore, in this embodiment, the difference between the above two change rates is compared with a predetermined threshold, and it is determined that an instruction skip has occurred when the difference exceeds the predetermined threshold. Then, the concentration after measurement of the sample gas or the concentration after measurement of the reference gas that cannot be handled as an accurate value due to skipping of instructions is replaced with an alternative value so as to be closer to the actual ozone concentration.

  This will be specifically described with reference to FIG. In the figure, the vertical axis represents ozone concentration and the horizontal axis represents time. In the figure, “♦” is a plot of the concentration after measurement of the sample gas, and “■” is a plot of the concentration after measurement of the reference gas. In the figure, Cs is the concentration after measurement of the sample gas, Cz is the concentration after measurement of the reference gas, and θs is an angle indicating the rate of change of the concentration after measurement of the sample gas described later (here, also referred to as “angle after measurement of the sample gas”). ), Θz is an angle indicating a rate of change in concentration after reference gas measurement (to be described later) (also referred to as “angle after reference gas measurement”). The subscript “n” of Cs, Cz, θs, θz, etc. indicates the number of density calculation timings. In this case, attention is paid to the concentration calculation timings (1) to (7) in FIG. 5, and an instruction skip occurs in the concentration after the sample gas measurement at the timing (4) and the concentration after the reference gas measurement at the timing (5). It shall be.

At timing (1), the concentration Cz _n-2 after reference gas measurement is calculated. Next, at the timing (2), the concentration Cs _n-1 after the sample gas measurement is calculated. Next, at the timing (3), the concentration Cz _n-1 after the reference gas measurement is calculated, and the current concentration Cz _n-1 after the reference gas measurement is changed from the concentration Cz _n-2 after the previous reference gas measurement. The angle θz _n-2 after the reference gas measurement indicating the rate is obtained. Next, at the timing (4), the sample gas measurement concentration Cs _n is calculated, and the sample showing the change rate of the current sample gas measurement concentration Cs _{n from} the previous sample gas measurement concentration Cs _n−1. An angle θs _n−1 after gas measurement is obtained.

Thereafter, similarly, the ozone concentration is sequentially calculated, and an angle θ indicating the rate of change of the current ozone concentration from the previous ozone concentration is obtained. That is, at the timing (5), the reference gas measurement concentration Cz _n is calculated, and the reference gas measurement angle θz _n−1 is obtained. At timing (6), the sample gas measurement concentration Cs _{n + 1} is calculated, and the sample gas measurement angle θs _n is obtained. At timing (7), the concentration Cz _{n + 1} after the reference gas measurement is calculated, and the angle θz _n after the reference gas measurement is obtained.

Here, in the present embodiment, the angle θ (θs, θz) is obtained in atan (arc tangent) with the vertical axis representing ozone concentration and the horizontal axis representing time, as shown in FIG. More specifically, in the present embodiment, the angle θ is calculated by the following equation (2) by converting it to unit time “1” because the time on the horizontal axis is a constant period (6 seconds).
θ = | atan (current concentration−previous concentration) | (2)

In this embodiment, the ozone concentration and the angle θ are obtained at each concentration calculation timing, and then the latest sample gas measurement angle θs and the reference gas measurement angle θz are compared. In particular, in the present embodiment, the difference (absolute value) between the most recent sample gas measurement angle θs and the reference gas measurement angle θz (herein, also simply referred to as “angle difference”) is larger than a predetermined threshold θerr. It is determined whether or not. That is, it is determined whether or not the following formula (3) is satisfied.
θerr <| θz−θs | (3)

  When the angle difference is equal to or smaller than the threshold θerr, it is determined that no instruction skip occurs in the ozone concentration calculated at the current concentration calculation timing. The ozone concentration calculated this time is directly reflected in the measurement result (displayed, recorded, etc.) of the ozone concentration in the sample gas. On the other hand, if the angle difference is larger than the threshold value θerr, it is determined that an instruction skip has occurred in the ozone concentration calculated at the current concentration calculation timing. Then, the ozone concentration calculated this time is replaced based on the ozone concentration calculated at the previous concentration calculation timing (interpolation process), and is reflected in the measurement result of the ozone concentration in the sample gas. In particular, in the present embodiment, in the interpolation process, the ozone concentration calculated this time is replaced with the ozone concentration calculated last time.

In the example of FIG. 5, at the timing (4), the sample gas post-measurement angle θs _n−1 obtained this time is compared with the reference gas post-measurement angle θz _n−2 obtained one time before,
θerr <| θz _n−2 −θs _n−1 |
In other words, it is determined that the angle difference is larger than the threshold value θerr. Then, the concentration Cs _n after measurement of the sample gas calculated this time is replaced with the concentration Cs _n−1 after measurement of the sample gas calculated last time, and is reflected in the measurement result of the ozone concentration in the sample gas. When the previous ozone concentration has already been replaced with the previous ozone concentration, the ozone concentration calculated this time may be replaced with the ozone concentration after the previous replacement.

Similarly, in the example of FIG. 5, at timing (5), the reference gas measurement angle θz _n−1 obtained this time is compared with the sample gas measurement angle θs _n−1 obtained one time before. ,
θerr <| θz _n−1 −θs _n−1 |
In other words, it is determined that the angle difference is larger than the threshold value θerr. Then, the post-sample gas measurement concentration Cz _n calculated this time is replaced with the previously calculated post-sample gas measurement concentration Cz _n−1 and reflected in the measurement result of the ozone concentration in the sample gas.

  On the other hand, at timings (1), (2), (3), (6), and (7), the angular difference is determined to be equal to or less than the threshold θerr, and the sample gas measured concentration Cs calculated at each of these timings, The concentration Cz after the reference gas measurement is directly reflected in the measurement result of the ozone concentration in the sample gas.

  Note that the threshold θerr can sufficiently reduce the skipping in accordance with the measurement target (eg, the ozone concentration in the atmosphere or the ozone concentration generated by the ozone generator), the measurement data acquisition interval, and the like. Can be arbitrarily determined. As an example, in this embodiment, θerr is 3.5 degrees.

  Thus, in this embodiment, every time the control unit 4 calculates the concentration after measurement of the sample gas or the concentration after measurement of the reference gas, the control unit 4 calculates the concentration after the measurement of the latest sample gas from the concentration after the measurement of the previous sample gas. A first index value indicating the degree of change and a second index value indicating the degree of change of the latest reference gas measurement concentration from the previous reference gas measurement concentration are obtained. Then, when the difference between the first and second index values is greater than a predetermined threshold, the control unit 4 calculates the sample gas concentration calculated this time or the reference gas measured concentration previously calculated respectively. Interpolation processing is performed to replace with another value based on at least one of the post-measurement concentration or the reference gas post-measurement concentration. In particular, in the present embodiment, in the interpolation process, the concentration after the measurement of the sample gas calculated this time is replaced with another value based on the concentration after the measurement of the sample gas calculated previously, and the concentration after the measurement of the reference gas calculated this time is calculated previously. Is replaced with another value based on the measured concentration of the reference gas. In this embodiment, the first index value indicates the rate of change of the latest post-sample gas concentration from the previous post-sample gas concentration, and the second index value is the latest It shows the rate of change of the concentration after the reference gas measurement from the concentration after the previous reference gas measurement. More specifically, in this embodiment, this rate of change is obtained when the concentration after measurement of the sample gas or the concentration after measurement of the reference gas is plotted on the coordinates where the vertical axis indicates the ozone concentration in the sample gas and the horizontal axis indicates the time. The angle between the straight lines connecting adjacent concentration plots after measurement of the sample gas and the horizontal axis, or the angle connecting the straight lines connecting adjacent plots of concentration after measurement of the reference gas to the horizontal axis.

  FIG. 6 is a flowchart showing the flow of measurement data processing in the control unit 4 in this embodiment.

  The control unit 4 samples the measurement data input from the detector 23 at a predetermined time interval (for example, every 150 ms) (S1). Further, the control unit 4 monitors the start timing of the measurement period of the ultraviolet light transmission amount of the sample gas or the reference gas ultraviolet light that arrives every 6 seconds (S2), and the ultraviolet transmission light amount of the sample gas or the ultraviolet light of the reference gas. When the start timing of the transmitted light amount measurement period arrives, the average value of the measurement data sampled for 3 seconds is obtained, and the concentration after measurement of the sample gas or the concentration after measurement of the reference gas is calculated (S3, S4). Further, as described with reference to FIG. 5, the control unit 4 determines whether or not an instruction skip has occurred in the ozone concentration calculated this time at every concentration calculation timing (S5).

  When the control unit 4 determines that the instruction skip has occurred in S5, the ozone concentration calculated this time is the ozone concentration calculated twice before (that is, the ozone concentration calculated this time is after the sample gas measurement). In the case of the concentration, the concentration after the previous sample gas measurement is used, and when the ozone concentration calculated this time is the concentration after the reference gas measurement, the concentration is replaced with the concentration after the previous reference gas measurement) for subsequent processing (S6). On the other hand, if the control unit 4 determines in S5 that no instruction skip has occurred, the control unit 4 uses the ozone concentration calculated this time for subsequent processing.

  Thereafter, the control unit 4 determines the ozone concentration (including the replaced one) obtained as described above, and the ozone obtained so far and stored in the storage unit of the control unit 4 in the same manner as described above. Smoothing processing is performed using the density (S7). And the control part 4 memorize | stores the ozone concentration obtained by the smoothing process in a memory | storage part as a measurement result of the ozone concentration in final sample gas. The control unit 4 may further display the measurement result stored in the storage unit on the display unit or transmit it to an external device.

  In the present embodiment, as the interpolation processing, the concentration after the current sample gas measurement is replaced with the concentration after the previous sample gas measurement, or the concentration after the current reference gas measurement is replaced with the concentration after the previous reference gas measurement. However, the interpolation process itself is not limited to this, and any available interpolation method can be adopted. For example, replace the concentration after the previous sample gas measurement or the concentration after the reference gas measurement with an intermediate value between the previous and current sample gas concentrations, or replace the previous and previous (for example, the previous) sample gas measurement concentrations or the concentration after the reference gas measurement. Or can be replaced with the value obtained by extrapolation. In addition, the ozone concentration that replaces the ozone concentration calculated this time in the interpolation process may be a value that is closer to the actual ozone concentration based on the ozone concentration calculated earlier. Therefore, the calculated sample gas concentration can be replaced with another value based on the previously calculated reference gas measured concentration (or both the sample gas measured concentration and the reference gas measured concentration). It may also be contemplated to replace the reference gas post-measurement concentration with another value based on the previously calculated sample gas post-measurement concentration (or both the sample gas post-measurement concentration and the reference gas post-measurement concentration). However, according to the study by the present inventors, in order to obtain a measurement result closer to the actual ozone concentration, interpolation processing is performed between the concentrations after the sample gas measurement or between the concentrations after the reference gas measurement as in this embodiment. Preferably it is done.

  In this embodiment, a smoothing process for smoothing the measurement result is performed, but the ozone concentration (including the replaced one) calculated at each concentration calculation timing without performing this is used as the final sample gas. It is good also as a measurement result of ozone concentration in the inside.

5. Effect Confirmation Next, the results of examining the effect of the instruction skip correction processing of this embodiment will be described.

  The left figure of FIG. 7A shows the case of not performing the instruction skip correction process of this embodiment (similar to FIG. 3B), and the right figure of the zero gas when the instruction jump correction process of this embodiment is performed. The measurement result of ozone concentration is shown. In the figure, the vertical axis represents time, and the horizontal axis represents ozone concentration. As shown to the right figure of Fig.7 (a), when the instruction skip correction process of a present Example is performed, it turns out that the instruction skip seen by the left figure of Fig.7 (a) is reduced.

  In FIG. 7B, the mercury lamp 22 is relatively stable and the skipping correction process of the present embodiment is performed using a reference unit that does not perform the skipping correction process of the present embodiment and the arbitrary mercury lamp 22. This is a comparison of the results of long-term measurements of atmospheric ozone concentrations with a verifier. In the figure, the vertical axis represents the ozone concentration, the horizontal axis represents the time, and the ozone concentration plots an average value for one hour. As shown in FIG. 7 (b), substantially the same ozone concentration measurement result is obtained by the reference device and the verification device, and accurate measurement can be performed in the long-term measurement of the actual ozone concentration in the atmosphere. I understand.

  As described above, according to the present embodiment, not only when the amount of ultraviolet light transmitted through the reference gas is measured, but also when the amount of light of the mercury lamp 22 changes suddenly when the amount of ultraviolet light transmitted through the sample gas is measured, Instruction skipping can be determined. Therefore, according to the present embodiment, it is possible to reduce the instruction skip occurring in the measurement result of the ozone concentration in the sample gas and obtain a more accurate measurement result.

[Example 2]
Next, another embodiment of the present invention will be described. The basic configuration and operation of the ozone measuring apparatus of the present embodiment are the same as those of the first embodiment. Accordingly, elements having the same or corresponding functions or configurations as those of the first embodiment in the ozone measuring apparatus of the present embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In Example 1, in order to discriminate instruction skip, the most recent sample gas measurement angle θs and the reference gas measurement angle θz were compared at each concentration calculation timing. In many cases, the mercury lamp 22 returns to a stable state within 10 seconds after a change in the light amount of the mercury lamp 22 that causes an instruction skip occurs. In many cases, the skipping of instructions can be sufficiently reduced by the method of the first embodiment.

  However, when the change in the light amount of the mercury lamp 22 is relatively large and the change in the indication skip is relatively large, it may take several tens of seconds for the mercury lamp 22 to return to a stable state. In such a case, in the method of the first embodiment that compares the most recent sample gas measurement angle θs and the reference gas measurement angle θz, the time until the light quantity of the mercury lamp 22 stabilizes when the instruction skip occurs. It may not be possible to suppress the change in ozone concentration.

  FIG. 8 is a graph for explaining another typical example of instruction skipping. In the figure, the vertical axis represents ozone concentration and the horizontal axis represents time. In the figure, “♦” is a plot of the concentration after measurement of the sample gas, and “■” is a plot of the concentration after measurement of the reference gas. In the example shown in FIG. 8, it can be seen that it takes a relatively long time for the calculated value of the ozone concentration to be stabilized when an instruction skip occurs compared to the examples shown in FIGS. 4 and 5.

In the example of FIG. 8, there is an instruction skip in the ozone concentration calculated at the concentration calculation timings (3) to (8). Here, with regard to the concentration after the measurement of the sample gas at the timing (3), the difference between the latest angles θs _n−1 and θz _n−1 is large, so that the instruction skip occurs even by the method of the first embodiment. Can be determined. Similarly, with respect to the concentration after the measurement of the sample gas at the timing (4), the difference between the latest angles θz _n and θs _n−1 is large, so that the skipping of instructions is also generated by the method of the first embodiment. It can be judged.

However, for the concentration after the sample gas measurement at timing (5), for example, since the difference between the latest angles θs _n and θz _n is small, it is determined that an instruction skip has occurred in the method of the first embodiment. It ’s difficult. Similarly, for the concentration after measurement of the reference gas at timing (6), for example, since the difference between the latest angles θz _{n + 1} and θs _n is small, it is determined that an instruction skip has occurred in the method of the first embodiment. Difficult to do.

  Therefore, in this embodiment, the difference (absolute value) between the latest and previous angles θs is compared with the difference (absolute value) between the latest and previous angles θz. In particular, in the present embodiment, it is determined whether or not the difference (absolute value) between the difference between the angles θs and the difference between the angles θz is larger than a predetermined threshold θerr. If it is greater than the threshold value θerr, it is determined that an instruction skip has occurred in the ozone concentration calculated this time, and if it is less than the threshold value θerr, it is determined that no instruction skip has occurred in the ozone concentration calculated this time. .

  As described above, in this embodiment, the first index value indicating the degree of change in the concentration after the latest sample gas measurement from the concentration after the previous sample gas measurement is the previous sample gas of the concentration after the latest sample gas measurement. It shows the difference between the rate of change from the concentration after measurement and the rate of change from the concentration after the last sample gas measurement of the concentration after the previous sample gas measurement. Further, in the present embodiment, the second index value indicating the degree of change in the latest reference gas measurement concentration from the previous reference gas measurement concentration is the value after the previous reference gas measurement of the latest reference gas measurement concentration. It shows the difference between the change rate from the concentration and the change rate from the concentration after the last reference gas measurement of the concentration after the previous reference gas measurement. Also in the present embodiment, this rate of change is obtained as the angle θ as in the first embodiment.

In the example of FIG. 8, for example, at the timing (5), the following equation:
θerr <|| θz _n −θz _n−1 | − | θs _n −θs _n−1 ||
It is determined whether or not it is satisfied, and it is determined that there is an instruction skip in the concentration after the sample gas measurement at the timing (5). The instruction skip at timings (3), (4), (6), (7), and (8) can also be determined in the same manner as described above.

  Note that the threshold value θerr in this embodiment is also the measurement target (whether it is the ozone concentration in the atmosphere or the ozone concentration generated by the ozone generator), the measurement data acquisition interval, as in the case of the first embodiment. Depending on the above, it is possible to arbitrarily determine so that the skipping of instructions can be sufficiently reduced.

  The interpolation process when it is determined that the instruction skip has occurred can be performed in the same manner as in the first embodiment.

  As described above, in this embodiment, even when the change in the amount of light of the mercury lamp 22 is relatively large and the change in the instruction skip is relatively large, the calculated value of the ozone concentration until it becomes stable when the instruction skip occurs is eliminated. Thus, a more accurate measurement result can be obtained.

DESCRIPTION OF SYMBOLS 1 Gas supply part 2 Detection part 3 Gas discharge part 4 Control part

Claims (5)

A measurement unit in which a sample gas and a reference gas from which ozone in the sample gas has been removed are alternately introduced;
A light source for irradiating the measurement unit with ultraviolet rays;
A detector that receives light transmitted through the measurement unit and generates an electrical signal corresponding to the amount of light received;
The sample gas measurement data corresponding to the electrical signal generated by the detector when the sample gas is introduced into the measurement unit, and the electrical signal generated by the detector when the reference gas is introduced into the measurement unit A control unit that calculates the ozone concentration in the sample gas based on the reference gas measurement data according to
And the control unit includes:
When the sample gas measurement data is acquired, the post-measurement gas concentration indicating the ozone concentration in the sample gas is calculated based on the current sample gas measurement data and the most recent reference gas measurement data, and the reference gas measurement When data is acquired, based on the current reference gas measurement data and the latest sample gas measurement data, the concentration after measurement of the reference gas indicating the ozone concentration in the sample gas is calculated,
Each time the concentration after measurement of the sample gas or the concentration after measurement of the reference gas is calculated, a first index value indicating the degree of change from the concentration after measurement of the sample gas immediately before the concentration after measurement of the sample gas. And a second index value indicating a degree of change of the latest measured concentration of the reference gas from the previous measured concentration of the reference gas, and a difference between the first and second index values is obtained. If the concentration after measurement of the sample gas or the concentration after measurement of the reference gas calculated this time is larger than a predetermined threshold, the concentration after the measurement of the sample gas or the concentration after measurement of the reference gas previously calculated The ozone measuring device characterized by performing the process which substitutes to the value of.   When the difference between the first and second index values is larger than the threshold value, the control unit determines another value based on the concentration after measurement of the sample gas previously calculated as the concentration after measurement of the sample gas previously calculated. The ozone measuring device according to claim 1, wherein the ozone measuring device is replaced with or replaced with another value based on the previously calculated concentration of the reference gas previously calculated. The first index value indicates a rate of change of the latest concentration after measurement of the sample gas from the previous concentration after measurement of the sample gas,
3. The ozone measuring apparatus according to claim 1, wherein the second index value indicates a rate of change of the latest post-reference gas measurement concentration from the previous post-reference gas measurement concentration. The first index value is calculated based on the rate of change of the latest concentration after measurement of the sample gas from the previous concentration after measurement of the sample gas and the concentration after the previous measurement of the sample gas before the concentration after the previous measurement of the sample gas. Shows the difference between the rate of change and
The second index value includes a rate of change of the latest concentration after the reference gas measurement from the previous concentration after the reference gas measurement, and a concentration after the previous reference gas measurement after the previous concentration after the reference gas measurement. The ozone measuring device according to claim 1, wherein a difference between the change rate and the rate of change is indicated. The control unit is adjacent to each other when the change rate is plotted with the concentration after measurement of the sample gas or the concentration after measurement of the reference gas on the coordinates where the vertical axis indicates the ozone concentration in the sample gas and the horizontal axis indicates time. The straight line connecting the plots of the concentration after the sample gas measurement is obtained as an angle formed with the horizontal axis direction, or an angle formed between the adjacent plots of the concentration after the reference gas measurement with the horizontal axis direction. Item 5. The ozone measuring device according to item 3 or 4.

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