Analysis device, analysis method, and analysis program

Abstract

To suppress upward or downward fluctuations of a differential signal obtained by switching flow paths in an analysis device that analyzes a measurement target component contained in a sample gas.SOLUTION: An analysis device comprises: a first flow path into which a sample gas is introduced and which includes an oxidation-reduction unit for a measurement target component; a second flow path into which the sample gas is introduced and from which the measurement target component is derived; a specific component detection unit that detects a specific component which is an oxide or a reductant of the measurement target component derived from the first and second flow paths; a flow path switching unit that switches the flow path connected to the specific component detection unit; a differential signal output unit that outputs, at predetermined time intervals, a differential signal between a first detection signal of the specific component obtained when the first flow path is connected to the specific component detection unit, and a second detection signal of the specific component obtained when the second flow path is connected to the specific component detection unit; a smoothing processing unit that performs smoothing processing on the differential signal so that the rate of change becomes smaller according to the magnitude of the rate of change of the differential signal; and a measurement target component concentration calculation unit that calculates the concentration of the measurement target component on the basis of the smoothed differential signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an analysis device, an analysis method, and an analysis program. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is an analyzer that analyzes a measurement target component contained in a sample gas by switching a flow path using a switching valve.

[0003] This type of analyzer, as shown in Patent Document 1, for example, includes a sample flow path through which a sample gas flows, a reference flow path through which a reference fluid flows, an analysis unit that analyzes a component to be measured contained in the sample gas, and a switching valve that switches the flow path connected to the analysis unit between the sample flow path and the reference flow path. The sample gas and the reference fluid are alternately supplied to the analysis unit, allowing the analysis unit to detect a predetermined component contained in the sample gas and a predetermined component contained in the reference fluid, and calculate the difference in concentration between these predetermined components to calculate the concentration of the component to be measured.

[0004] In the above-described analytical device, since the sample gas and the reference fluid are alternately supplied to the analytical section, the concentrations of the predetermined component in the sample flow path and the predetermined component in the reference flow path are not detected precisely at the same time. That is, the concentration of the predetermined component delivered from one flow path is detected before or after the concentration of the predetermined component delivered from the other flow path.

[0005] As a result, due to differences in the measurement time and gas arrival speed between the sample and reference flow paths, the concentration difference between the predetermined component from the sample flow path and the predetermined component from the reference flow path may vary more significantly than the actual concentration change. In particular, when the concentrations of the predetermined component contained in the sample gas and the predetermined component contained in the reference fluid change suddenly, such as when the sample gas and / or the reference fluid rise or fall, the difference in concentration may exceed or fall below the actual concentration change during the rise or fall. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-156306 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, the present invention has been made in consideration of the above-mentioned problems, and its main objective is to suppress upward or downward fluctuations in the differential signal obtained by switching flow paths in an analytical device that analyzes the components to be measured contained in a sample gas. [Means for solving the problem]

[0008] That is, the analytical device of the present invention is an analytical device for analyzing a target component contained in a sample gas, and is characterized by comprising: a first flow path into which the sample gas is introduced and which has an oxidation-reduction section that oxidizes or reduces the target component; a second flow path into which the sample gas is introduced and which outputs the target component; a specific component detection section connected to the first flow path and the second flow path and which detects a specific component that is an oxide or a reduction product of the target component; a flow path switching section that switches the flow path connected to the specific component detection section between the first flow path and the second flow path; a differential signal output section that connects the first flow path to the specific component detection section and outputs a differential signal at predetermined intervals indicating the difference between a first detection signal of the specific component obtained by passing the sample gas through the oxidation-reduction section and a second detection signal of the specific component obtained by connecting the second flow path to the specific component detection section; a smoothing processing section that smoothes the differential signal using a filter that shapes the differential signal so that the rate of change of the differential signal becomes smaller depending on the magnitude of the rate of change of the differential signal; and a target component concentration calculation section that calculates the concentration of the target component based on the differential signal smoothed by the smoothing processing section.

[0009] With this configuration, the smoothing processing unit smoothes the differential signal using a filter that shapes the differential signal so that the rate of change decreases according to the magnitude of the rate of change when the rate of change of the differential signal is equal to or greater than a predetermined value, thereby making it possible to suppress changes in the differential signal at predetermined time intervals. Specifically, even when the concentration of the component to be measured in the sample gas changes suddenly, such as at the rise or fall of the sample, it is possible to suppress the differential signal from fluctuating above or below the actual concentration change at the rise or fall of the sample. In addition, since the smoothing processor performs the smoothing process without applying a moving average to the detected concentration, it is possible to prevent the response speed of the analyzer from slowing down depending on the number of moving average points, and as a result, it is possible to improve the response speed of the analyzer compared to when applying a moving average to the detected concentration.

[0010] A specific example of the filter is one that adjusts the second differential signal so as to suppress the absolute value of the difference between the rate of change of the first differential signal and the rate of change of the second differential signal output after the first differential signal as the absolute value of the difference becomes larger. With this configuration, the second differential signal is adjusted so that the larger the difference in absolute value between the rate of change of the first differential signal and the rate of change of the second differential signal, the more the absolute value of the difference is suppressed, thereby making it possible to suppress the change over time from the rate of change of the first differential signal to the rate of change of the second differential signal.

[0011] The filter may suppress the absolute value based on an arithmetic expression that indicates a change in the rate of change of the second differential signal relative to the rate of change of the first differential signal. With this configuration, the absolute value of the difference between the rate of change of the first differential signal and the rate of change of the second differential signal can be calculated quantitatively, so that the differential signal can be made to accurately follow changes in concentration.

[0012] The arithmetic expression may be one that calculates a weighted average of the rate of change of the first differential signal and the rate of change of the second differential signal. With this configuration, by calculating the weighted average, the effect of the rate of change of the first differential signal is reflected in the second differential signal after smoothing processing, so that it is possible to suppress changes in the rate of change of the second differential signal relative to the rate of change of the first differential signal.

[0013] It is preferable that the differential signal output section outputs the differential signal which is a digital signal, and that the filter is a digital filter.

[0014] With this configuration, the smoothing processing unit smoothes the differential signal using a digital filter, thereby reliably reducing the rate of change in the differential signal above a predetermined value, and the concentration calculation unit can more accurately calculate the concentration of the component to be measured.

[0015] The digital filter preferably uses an adaptive filter configured so that the amount of suppression of the absolute value is adjustable.

[0016] With this configuration, the smoothing processor smoothes the difference signal by using an adaptive filter, so that it is possible to shape the rate of change of various difference signals. As a result, when the rate of change of the difference signal changes suddenly, the smoothing processor can smooth the difference signal in response to the change, so that the concentration calculation unit can prevent the concentration of the measurement target component from being over or underexcited.

[0017] The device may further include a first response time adjustment unit that adjusts a first response time, which is the time it takes for the sample gas to pass through the first flow path and the first detection signal to be output, and a second response time adjustment unit that adjusts a second response time, which is the time it takes for the sample gas to pass through the second flow path and the second detection signal to be output, and the differential signal output unit may output the differential signal based on the first response time adjusted by the first response time adjustment unit and / or the second response time adjusted by the second response time adjustment unit.

[0018] With this configuration, the differential signal output unit outputs a differential signal with the response time adjusted, so the time difference when the concentrations of the two specific components are calculated is small in the differential signal, allowing the concentration calculation unit to more accurately calculate the concentration of the measurement target component from the differential signal.

[0019] It is preferable that the first response time adjustment unit and / or the second response time adjustment unit adjust the first response time and / or the second response time so that the difference between the first response time and the second response time becomes zero.

[0020] With this configuration, the response times in each flow path are the same, eliminating errors due to differences in response time when the differential signal output unit outputs a differential signal, and allowing the concentration calculation unit to calculate the concentration of the component to be measured more accurately.

[0021] Specific examples of the component to be measured and the specific component include nitrogen oxides when the component to be measured is ammonia, nitric oxide when the component to be measured is nitrogen oxides, and sulfur dioxide when the component to be measured is hydrogen sulfide.

[0022] An analytical method for analyzing a target component contained in a sample gas, the method comprising: using an analytical device comprising: a first flow path through which the sample gas is discharged and which has an oxidation-reduction section that oxidizes or reduces the target component; a second flow path through which the sample gas is discharged and from which the target component is discharged; a specific component detection section connected to the first flow path and the second flow path and which detects a specific component that is an oxide or a reduction product of the target component; and a flow path switching section that switches the flow path connected to the specific component detection section between the first flow path and the second flow path; connecting the first flow path to the specific component detection section and outputting a differential signal at predetermined time intervals that indicates the difference between a first detection signal of the specific component obtained by passing the sample gas through the oxidation-reduction section and a second detection signal of the specific component obtained by connecting the second flow path to the specific component detection section; smoothing the differential signal using a filter that shapes the differential signal so that the rate of change of the differential signal becomes smaller depending on the magnitude of the rate of change; and calculating the concentration of the target component based on the smoothed differential signal. An analytical program for analyzing a measurement target component contained in a sample gas, the program comprising: an analytical device including a first flow path through which the sample gas is discharged and which has an oxidation-reduction unit that oxidizes or reduces the measurement target component; a second flow path through which the sample gas is discharged and from which the measurement target component is discharged; a specific component detection unit connected to the first flow path and the second flow path and that detects a specific component which is an oxide or a reduction product of the measurement target component; and a flow path switching unit that switches the flow path connected to the specific component detection unit between the first flow path and the second flow path, the program comprising: connecting the first flow path to the specific component detection unit and causing the sample gas to pass through the oxidation-reduction unit; and a second detection signal of the specific component obtained by connecting the second flow path to the specific component detection unit, at predetermined time intervals; a smoothing processing unit that smoothes the differential signal using a filter that shapes the differential signal so that the rate of change of the differential signal becomes smaller depending on the magnitude of the rate of change of the differential signal; and a measurement target component concentration calculation unit that calculates the concentration of the measurement target component based on the differential signal smoothed by the smoothing processing unit.

[0023] With this configuration, it is possible to obtain the same effects as those of the above-described analyzer. [Effects of the Invention]

[0024] According to the present invention, in an analyzer that analyzes a measurement target component contained in a sample gas, it is possible to suppress upward or downward fluctuations in a differential signal obtained by switching flow paths. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic diagram showing an analysis device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing functional blocks of a calculation device according to the embodiment. [Figure 3] 6 is a graph showing a smoothing process in the same embodiment. [Figure 4]10 is a flowchart showing an analysis method in the embodiment. [Figure 5] FIG. 10 is a diagram showing a concentration calculation result in the same embodiment. [Figure 6] 10 is a graph showing a smoothing process according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] An analytical device according to one embodiment of the present invention will be described below with reference to the drawings. Note that in all of the drawings shown below, some parts may be omitted or exaggerated for clarity. Identical components will be assigned the same reference numerals, and their description will be omitted where appropriate.

[0027] <Device configuration> The analytical device 100 of this embodiment analyzes a target component contained in a sample gas by a chemical analysis method (CLA method) in which an instrumentation gas, which is a gas containing oxygen, reacts with the sample gas. Examples of the sample gas include flue gas flowing through a flue and / or exhaust gas emitted from a vehicle or a test specimen that is a part of a vehicle. In this embodiment, the analytical device 100 measures, for example, the concentration of the target component.

[0028] In this embodiment, examples of the component to be measured include ammonia, nitrogen oxides (NOx), and / or hydrogen sulfide. In this embodiment, the sample gas contains, in addition to the component to be measured, a specific component that is an oxide or reduction product of the component to be measured. Specifically, when the component to be measured is ammonia, the specific component is nitrogen oxide, which is an oxide or reduction product of ammonia, and the sample gas contains ammonia and nitrogen oxide. When the component to be measured is nitrogen oxide, the specific component is nitric oxide, which is a reduction product of nitrogen oxide, and the sample gas contains nitrogen oxide and nitric oxide. When the component to be measured is hydrogen sulfide, the specific component is sulfur dioxide, which is an oxide of hydrogen sulfide, and the sample gas contains hydrogen sulfide and sulfur dioxide.

[0029] 1, the analytical device 100 includes a first flow path L1 into which a sample gas is introduced and which oxidizes or reduces a component to be measured before discharging it, a second flow path L2 into which the sample gas is introduced and which discharging the component to be measured without oxidizing or reducing it, a specific component detection unit 3 connected to the first flow path L1 and the second flow path L2 and which detects a specific component, a flow path switching unit 4 which switches the flow path connected to the specific component detection unit 3, and a calculation device 5 which performs various calculations. Each unit will be described below.

[0030] The first flow path L1 is a flow path through which the sample gas flows toward the flow path switching unit 4. In this embodiment, the first flow path L1 leading to the flow path switching unit 4 is provided with an oxidation-reduction unit 2 that oxidizes or reduces the measurement target components. The oxidation-reduction unit 2 is, for example, an oxidation-reduction catalyst that oxidizes or reduces the measurement target components to generate a specific component. Therefore, when the sample gas passes through the oxidation-reduction unit 2, a predetermined proportion of the measurement target components is oxidized or reduced and converted into the specific component, changing the concentration of the specific component contained in the sample gas. In this embodiment, the specific component generated by oxidation or reduction in the oxidation-reduction unit 2 is the same component as the specific component led out from the second flow path L2.

[0031] Specifically, when the component to be measured is ammonia, the oxidation-reduction unit 2 is a reduction catalyst that reduces ammonia, and the oxidation-reduction unit 2 reacts ammonia with nitric oxide, thereby reducing the specific component, nitrogen oxide, in the first flow path L1. In this case, the decrease in the ammonia concentration and the decrease in the nitric oxide concentration in the first flow path L1 are approximately the same. Therefore, the concentration of ammonia in the sample gas can be calculated based on the difference between the concentration of nitrogen oxide in the first flow path L1 and the concentration of nitrogen oxide in the second flow path L2, which will be described later.

[0032] Alternatively, the redox unit 2 may be an oxidation catalyst that oxidizes ammonia, and the redox unit 2 may react ammonia with oxygen to produce nitrogen oxide, a specific component. In this case, the decrease in ammonia concentration and the increase in nitrogen oxide concentration in the first flow path L1 are approximately equal. Therefore, the ammonia concentration in the sample gas can be calculated based on the difference between the nitrogen oxide concentration in the first flow path L1 and the nitrogen oxide concentration in the second flow path L2 (described later). Before calculating the difference in nitrogen oxide concentration between the first flow path L1 and the second flow path L2, the nitrogen oxide concentration can be calculated based on the sample gas flowing through the first flow path L1, or the nitric oxide concentration can be calculated based on the sample gas flowing through the second flow path L2.

[0033] The second flow path L2 is provided in parallel with the first flow path L1, and is a flow path through which the sample gas flows toward the flow path switching unit 4. Unlike the first flow path L1, the second flow path L2 does not have an oxidation-reduction unit 2. Therefore, the concentrations of the measurement target components and the specific components contained in the sample gas do not change before and after the sample gas passes through the second flow path L2.

[0034] The specific component detector 3 is connected to the first flow path L1 and the second flow path L2 and detects a specific component that is an oxide or a reduced product of the component to be measured. Specifically, when connected to the first flow path L1, the specific component detector 3 outputs a first detection signal indicative of the specific component derived from the first flow path L1, and when connected to the second flow path L2, it outputs a second detection signal indicative of the specific component derived from the second flow path L2. Note that the specific component detector 3 may output the first detection signal and the second detection signal as digital signals or analog signals.

[0035] More specifically, in a chamber (not shown) where a specific component from the first flow path L1 and / or the second flow path L2 reacts with ozone from the instrumentation gas flow path L5 (described later), the specific component detector 3 is, for example, a photodiode that detects luminescence generated during the reaction. The first detection signal and the second detection signal are signals that indicate the luminescence intensity when the specific component reacts with ozone.

[0036] In this embodiment, the flow path in which the specific component detection unit 3 is installed is referred to as the analysis flow path L3, and the flow path in parallel with the analysis flow path L3 through which the sample gas bypasses the specific component detection unit 3 is referred to as the bypass flow path L4. A switching valve V is provided in the analysis flow path L3 upstream of the specific component detection unit 3. The switching valve V periodically switches the flow path through which the sample gas flows between the analysis flow path L3 and the bypass flow path L4. This allows the analysis device 100 of this embodiment to switch between a case in which the sample gas is introduced into the specific component detection unit 3 and a case in which the sample gas is not introduced into the specific component detection unit 3.

[0037] The flow path switching unit 4 switches the flow path connected to the analysis flow path L3, in which the specific component detection unit 3 is provided, between the first flow path L1 and the second flow path L2 at predetermined time intervals. The flow path connected downstream of the flow path switching unit 4 is connected to the analysis flow path L3 upstream of the specific component detection unit 3. Specifically, the flow path switching unit 4 alternately outputs the specific component from the first flow path L1 and the specific component from the second flow path L2 to the analysis flow path L3. The flow path switching unit 4 is, for example, a three-way switching valve that switches at a constant interval, but is not limited to this.

[0038] The analyzer 100 of this embodiment further includes an instrumentation gas flow path L5 through which an instrumentation gas containing, for example, oxygen or ozone flows. Specifically, the instrumentation gas flow path L5 may supply ozone to the specific component detection unit 3 so that the specific component detection unit 3 can detect the first detection signal and / or the second detection signal.

[0039] Specifically, the instrumentation gas flow path L5 is provided with an ozone generator 6 that converts oxygen in the instrumentation gas into ozone. As a result, the instrumentation gas passes through the ozone generator 6, and the instrumentation gas containing ozone is supplied from the instrumentation gas flow path L5 to the specific component detection unit 3.

[0040] Furthermore, the instrumentation gas flow path L5 upstream of the ozone generator 6 may be provided with a branch flow path L6 that branches off from the instrumentation gas flow path L5 and is connected to the analysis flow path L3 upstream of the specific component detection unit 3. This allows the sample gas to be diluted with oxygen in the instrumentation gas in the analysis flow path L3 upstream of the specific component detection unit 3.

[0041] The calculation device 5 constitutes a so-called computer equipped with a CPU, memory, A / D converter, D / A converter, and various input / output devices, and as shown in FIG. 2 , it performs the functions of a first detection signal receiving unit 51, a second detection signal receiving unit 52, a specific component concentration calculation unit 53, a differential signal output unit 54, a first response time adjustment unit 55, a second response time adjustment unit 56, a measurement target component concentration calculation unit 57, and a smoothing processing unit 58.

[0042] The first detection signal receiving unit 51 receives the first detection signal output from the specific component detecting unit 3 .

[0043] The second detection signal receiving unit 52 receives the second detection signal output from the specific component detecting unit 3 .

[0044] The specific component concentration calculation unit 53 calculates the concentration of the specific component based on the signal from the specific component detection unit 3. Specifically, the specific component concentration calculation unit 53 calculates a first concentration indicating the concentration of the specific component obtained by connecting to the first flow path L1 based on the first detection signal received by the first detection signal receiving unit 51. Furthermore, the specific component concentration calculation unit 53 calculates a second concentration indicating the concentration of the specific component obtained by connecting to the second flow path L2 based on the second detection signal received by the second detection signal receiving unit 52.

[0045] The differential signal output unit 54 outputs a differential signal indicating the difference between the first concentration and the second concentration at predetermined time intervals. The differential signal indicates the difference between the first concentration obtained from the time the first flow path L1 is connected to the specific component detection unit 3 until the time the second flow path L2 is switched to the specific component detection unit 3, and the second concentration obtained from the time the second flow path L2 is connected to the specific component detection unit 3 until the time the second flow path L2 is switched to the first flow path L1. Here, the differential signal output unit 54 outputs the differential signal as a digital signal, regardless of whether the first detection signal and the second detection signal are digital signals or analog signals. Note that in this embodiment, the differential signal indicates the difference in concentration of the specific component in the different flow paths, but it may also indicate the concentration of the target component obtained based on the difference in concentration of the specific component.

[0046] The first response time adjustment unit 55 adjusts the first response time, which is the time it takes for the sample gas to pass through the first flow path L1 and output a first detection signal. Specifically, the first response time adjustment unit 55 adjusts the first response time based on first flow path information, which is information indicating the state of the first flow path L1, and / or second flow path information, which is information indicating the state of the second flow path L2. Here, the first flow path information may include, for example, the piping length and piping diameter of the first flow path L1. The second flow path information may include, for example, the piping length and piping diameter of the second flow path L2.

[0047] In this embodiment, the first response time is calculated based on the difference between the time when the sample gas is introduced into the first flow path L1 and the time when the first detection signal is output, but it may also be the time from when the sample gas is introduced into the first flow path L1 to when it is introduced into the specific component detection unit 3. The first response time adjustment unit 55 may adjust the first response time so that the difference between the first response time and a second response time, which will be described later, becomes zero. Note that the adjustment of the first response time by the first response time adjustment unit 55 may be automatic or manual. When the first response time adjustment unit 55 automatically adjusts the first response time, the calculation device 5 may further include a first response time reception unit that receives the first response time.

[0048] The second response time adjusting unit 56 adjusts the second response time, which is the time it takes for the sample gas to pass through the second flow path L2 and for the second detection signal to be output. Specifically, the second response time adjusting unit 56 adjusts the second response time based on the first flow path information and / or the second flow path information.

[0049] In this embodiment, the second response time is calculated based on the difference between the time when the sample gas is introduced into the second flow path L2 and the time when the second detection signal is output, but it may also be the time from when the sample gas is introduced into the first flow path L1 to when it is introduced into the specific component detection unit 3. The second response time adjustment unit 56 may adjust the second response time so that the difference from the first response time becomes zero. Note that the adjustment of the second response time by the second response time adjustment unit 56 may be automatic or manual. When the second response time adjustment unit 56 automatically adjusts the second response time, the calculation device 5 may further include a second response time reception unit that receives the second response time.

[0050] Measured component concentration calculation unit 57 calculates the concentration of the measured component based on the differential signal output by differential signal output unit 54 or the differential signal smoothed by smoothing processing unit 58. Specifically, measured component concentration calculation unit 57 calculates the concentration of the measured component from the concentration difference of the specific component by multiplying the concentration difference of the specific component indicated by the differential signal by a predetermined conversion coefficient. Then, after smoothing processing unit 58 smoothes the differential signal, measured component concentration calculation unit 57 calculates the concentration of the measured component based on the smoothed differential signal.

[0051] When the rate of change of the differential signal is equal to or greater than a predetermined value, the smoothing processing unit 58 smoothes the differential signal using a filter that shapes the differential signal so that the rate of change decreases in accordance with the magnitude of the rate of change. Here, the rate of change of the differential signal refers to the difference between the differential signals output by the differential signal output unit 54 at predetermined time intervals, and more specifically, refers to the difference between the concentration of a specific component indicated by a first differential signal (described below) and the concentration of a specific component indicated by a second differential signal (described below). Furthermore, the smoothing processing refers to processing the second differential signal so as to suppress the absolute value of the rate of change of the second differential signal relative to the absolute value of the rate of change of the first differential signal.

[0052] The filter of this embodiment adjusts the second difference signal so as to suppress the absolute value of the difference between the rate of change of the first difference signal and the rate of change of the second difference signal output after the first difference signal as the absolute value of the difference increases, and is specifically a digital filter. More specifically, the digital filter is an adaptive filter configured to adjust the amount by which the absolute value of the difference between the rate of change of the first difference signal and the rate of change of the second difference signal is suppressed. The adaptive filter of this embodiment may be, for example, a one-euro filter, which is easy to use and inexpensive, but is not limited to this.

[0053] Specifically, the filter of this embodiment suppresses the absolute value of the difference between the rate of change of the first differential signal and the rate of change of the second differential signal based on an arithmetic expression that indicates the change in the rate of change of the second differential signal relative to the rate of change of the first differential signal. Specifically, the arithmetic expression used in the filter calculates a weighted average of the rate of change of the first differential signal and the rate of change of the second differential signal.

[0054] A method for smoothing the rate of change of the second differential signal using the filter of this embodiment will be described below with reference to Fig. 3. As a premise, the differential signal is output at predetermined times (t0, t1, t2, t3, ...), and the differential signal output at time t1 is the first differential signal, and the differential signal output at time t2 is the second differential signal.

[0055] First, when a first differential signal is output at time t1, a rate of change Δ1 of the differential signal during a period P1 from time t0 to time t1 is calculated. Then, a weighted average H1 at time t1 is calculated by multiplying the differential signal at time t0 and the first differential signal by a predetermined weighting coefficient. Based on this weighted average H1, the first differential signal is smoothed. Note that the differential signal at time t0 may be assumed to be a predetermined value, such as 0.

[0056] Next, when the second differential signal is output at time t2, a rate of change Δ2 of the second differential signal during period P2 from time t1 to time t2 is calculated. Then, the weighted average H1 at time t1 and the rate of change Δ2 of the second differential signal during period P2 are multiplied by a predetermined weighting coefficient to calculate the weighted average H2 at time t2.

[0057] A reduction coefficient A2 is calculated based on this weighted average H2. The reduction coefficient A2 is a coefficient that reduces the absolute value of the difference between the rate of change Δ1 of the differential signal in period P1 and the rate of change Δ2 of the differential signal in period P2. The reduction coefficient A2 is, for example, a number obtained by using the reciprocal of the weighted average H2.

[0058] Then, the second differential signal is smoothed using the smoothed first differential signal S'1, the second differential signal S2, and the suppression coefficient A2. Specifically, the smoothed second differential signal S'2 is calculated by the following formula:

[0059]

number

[0060] The differential signal output after time t3 is also smoothed in the same way. Specifically, when a differential signal is output after time t3, the rate of change of the second differential signal, which is the differential signal at the time of output, is calculated. Here, the first differential signal is the differential signal output immediately before the second differential signal. Next, the weighted average at the time the first differential signal is output and the rate of change of the second differential signal are multiplied by a predetermined weighting coefficient to calculate the weighted average at the time the second differential signal is output. Next, based on the weighted average at the time the second differential signal is output, the reduction coefficient at the time the second differential signal is output is calculated. Next, the second differential signal is smoothed using the smoothed first differential signal, the second differential signal, and the reduction coefficient at the time the second differential signal is output.

[0061] <Analysis method> Next, an analysis method using the analysis device 100 of this embodiment will be described.

[0062] With the first flow path L1 connected to the specific component detection unit 3, sample gas is introduced into the first flow path L1 from a flue or the like. As the sample gas passes through the first flow path L1, the components to be measured contained in the sample gas are oxidized or reduced to specific components by the oxidation-reduction unit 2 (S1).

[0063] In this state, the switching valve V opens the analysis flow path L3 and closes the bypass flow path L4. The instrumentation gas flows through the instrumentation gas flow path L5, and oxygen contained in the instrumentation gas is converted to ozone. The instrumentation gas containing ozone is then introduced into the specific component detection unit 3.

[0064] When the sample gas and instrumentation gas are introduced into the specific component detection unit 3, the specific component reacts with ozone, generating light. The specific component detection unit 3 detects this light emission and outputs it as a first detection signal (S2). The first detection signal receiving unit 51 receives the first detection signal, and the specific component concentration calculation unit 53 calculates the concentration of the specific component obtained by connecting the first flow path L1 based on the first detection signal (S3).

[0065] After a certain period of time has elapsed, the switching valve V switches the flow path from the analysis flow path L3 to the bypass flow path L4, thereby discharging the sample gas outside the system without passing through the specific component detection unit 3.

[0066] In this state, the flow path switching unit 4 switches the flow path connected to the specific component detection unit 3 from the first flow path L1 to the second flow path L2 (S4). As a result, the sample gas is introduced into the second flow path L2 from the flue or the like, and passes through the flow path switching unit 4 without being oxidized or reduced.

[0067] After a certain period of time has elapsed, the switching valve V switches the flow path that opens from the bypass flow path L4 to the analysis flow path L3, so that the sample gas is introduced from the second flow path L2 into the specific component detection unit 3 without being oxidized or reduced (S5).

[0068] When the sample gas and instrumentation gas are introduced into the specific component detection unit 3, the specific component reacts with ozone, generating light. The specific component detection unit 3 detects this light emission and outputs it as a second detection signal (S6). The second detection signal receiving unit 52 receives the second detection signal, and the specific component concentration calculation unit 53 calculates the concentration of the specific component obtained by connecting the second flow path L2 based on the second detection signal (S7).

[0069] When the first detection signal and the second detection signal are output, the first response time adjustment unit 55 and / or the second response time adjustment unit 56 adjust the first response time and / or the second response time, respectively. Here, one of the first response time adjustment unit 55 and the second response time adjustment unit 56 may adjust one of the response times so that the difference between the first response time and the second response time becomes zero.

[0070] With the first response time and / or the second response time adjusted, the differential signal output unit 54 acquires the concentrations of the specific components obtained from the first flow path L1 and the second flow path L2 from the specific component concentration calculation unit 53, and outputs a differential signal indicating the difference in concentration of the specific components (S8).

[0071] The measurement target component concentration calculation section 57 calculates the concentration of the measurement target component based on the differential signal output by the differential signal output section 54 (S9).

[0072] The smoothing processing unit 58 acquires the differential signal, and when the rate of change of the differential signal is equal to or greater than a predetermined value, smoothes the differential signal using a filter that shapes the differential signal so that the rate of change becomes smaller according to the magnitude of the rate of change (S10).

[0073] After smoothing processing unit 58 smoothes the differential signal, measurement target component concentration calculation unit 57 acquires the smoothed differential signal and calculates the measurement target component based on the differential signal. The calculated measurement target component is displayed on display unit D, such as a display.

[0074] <Example> 5 shows the concentration calculation results when the smoothing process of this embodiment is performed (this embodiment) and the conventional concentration calculation results (conventional example). Here, the specific component is nitrogen oxide, and the component to be measured is ammonia.

[0075] 5, the peak value (absolute value) of the concentration in the conventional example is about 1.0 ppm, while the peak value (absolute value) of the concentration in this example is about 0.35 ppm. Therefore, it can be seen that the present example can suppress over- and under-exposure when calculating the concentration of the measured component compared to the conventional example.

[0076] <Effects of this embodiment> According to the analytical device 100 of this embodiment, the smoothing processor 58 smoothes the differential signal using a filter that suppresses the absolute value of the difference between the rate of change of the first differential signal and the rate of change of the second differential signal as the absolute value increases, thereby suppressing changes in the differential signal at predetermined time intervals. Specifically, even when the concentration of the component to be measured in the sample gas changes suddenly, such as at the rise or fall of the signal, the differential signal can be prevented from fluctuating above or below the actual concentration change at the rise or fall of the signal. In addition, since the smoothing processing unit 58 performs smoothing processing without applying a moving average to the detected density, it is possible to prevent the response speed of the analyzer 100 from being slowed down according to the number of points of the moving average. As a result, the response speed of the analyzer 100 can be improved as compared with the case of applying a moving average to the detected density.

[0077] <Other Embodiments> Note that the present invention is not limited to the above-described embodiments.

[0078] As another aspect of the filter used by the smoothing processing unit 58, when the change rate of the differential signal is large, the differential signal output later is smoothed so that the change rate of the differential signal becomes small according to the change rate. When the change rate of the differential signal is small, the smoothing processing is performed less compared to the case where the change rate of the differential signal is large. When the change rate of the differential signal is 0, the filter used by the smoothing processing unit 58 may output the differential signal output later without smoothing it.

[0079] Specifically, as shown in FIG. 6, when the change rates A1 and A2 (where A1 < A2) of the differential signal output by the differential signal output unit 54 are given, the smoothing processing unit 58 smooths the change rate A1 of the differential signal to B1 and smooths the change rate A2 of the differential signal to B2. Here, the amount C2 by which the smoothing processing unit 58 smooths the change rate A2 of the differential signal is larger than the amount C1 by which the smoothing processing unit 58 smooths the change rate A1 of the differential signal. In FIG. 6, the change rate B1 of the smoothed differential signal is smaller than the change rate B2 of the smoothed differential signal, but the magnitude relationship is not limited to this.

[0080] More specifically, the smoothing processor 58 stores in a predetermined memory the concentration of a specific component indicated by the differential signal output at a certain time. The filter used by the smoothing processor 58 calculates a weighted average of the change rate of the differential signal. More specifically, the filter used by the smoothing processor 58 changes the proportion of the weighted average after a predetermined time has elapsed in accordance with the weighted average of the change rate of the differential signal after a predetermined time has elapsed and the change rate of the differential signal at a certain time, thereby correcting the change rate of the differential signal in accordance with the change rate of the differential signal.

[0081] In the above embodiment, the concentration of the target component is calculated once, and then the smoothing processing unit 58 smoothes the differential signal. However, this is not limiting. For example, after the differential signal output unit 54 outputs a differential signal, the smoothing processing unit 58 may smooth the differential signal, and the target component concentration calculation unit 57 may calculate the concentration of the target component based on the smoothed differential signal. Specifically, the differential signal output unit 54 outputs a differential signal based on the first detection signal and the second detection signal. The smoothing processing unit 58 then acquires the differential signal output by the differential signal output unit 54 and smooths the differential signal. Thereafter, the target component concentration calculation unit 57 may calculate the concentration of the target component based on the differential signal smoothed by the smoothing processing unit 58.

[0082] In the above embodiment, the differential signal output unit 54 outputs a differential signal with the response time difference adjusted, but it may also output a differential signal with the response time difference not adjusted. Specifically, the differential signal output unit 54 may directly acquire the first detection signal and the second detection signal from the specific component detection unit 3 and output a differential signal from the first detection signal and the second detection signal. Even in this case, it is possible to output the concentration of the component to be measured more accurately while maintaining high-speed responsiveness compared to the conventional analyzer 100.

[0083] In the above embodiment, the differential signal output unit 54 outputs a digital signal as the differential signal, but it may also output an analog signal as the differential signal. In this case, the smoothing processing unit 58 may convert the differential signal, which is an analog signal, into a digital signal and then smooth the digital differential signal, or an A / D converter provided separately from the smoothing processing unit 58 may convert the differential signal into a digital signal, and then the smoothing processing unit 58 may receive the digital differential signal.

[0084] In the above embodiment, the smoothing processing unit 58 uses an adaptive filter as a digital filter, but is not limited to this and other digital filters may be used.

[0085] In the above embodiment, the analysis device 100 includes the first response time adjustment unit 55 and the second response time adjustment unit 56, but the first response time adjustment unit 55 and the second response time adjustment unit 56 do not have to be included.

[0086] In the above embodiment, the first detection signal and the second detection signal are light intensity signals based on luminescence generated during the reaction between ozone and the specific component, but the first detection signal and the second detection signal may indicate the concentration of the specific component obtained from the first flow path L1 and the concentration of the specific component obtained from the second flow path L2, respectively. In other words, the specific component detector 3 is not limited to a configuration that detects luminescence generated during the reaction between ozone and the specific component, and may be a configuration that detects the concentration of the specific component.

[0087] In addition, the present invention can be modified in various ways without departing from the spirit of the invention. [Explanation of symbols]

[0088] 100...Analyzer L1: First flow path L2: Second flow path L3: Analysis channel L4: Bypass flow path L5 Instrumentation gas flow path 2. Redox unit 3. Specific component detection section 4. Flow path switching section 5...Arithmetic unit 51 First detection signal receiving unit 52 Second detection signal receiving section 53 ...Specific component concentration calculation section 54 Differential signal output section 55 First response time adjustment unit 56 Second response time adjustment unit 57 Measurement target component concentration calculation section 58 Smoothing processing unit 6. Ozone Generator

Claims

1. An analytical device for analyzing a measurement target component contained in a sample gas, a first flow path into which the sample gas is introduced and which has an oxidation-reduction section that oxidizes or reduces the component to be measured; a second flow path through which the sample gas is introduced and through which the measurement target component is discharged; a specific component detection unit connected to the first flow path and the second flow path, which detects a specific component that is an oxide or a reduced product of the measurement target component; a flow path switching unit that switches a flow path connected to the specific component detection unit between the first flow path and the second flow path; a differential signal output unit that connects the first flow path to the specific component detection unit and outputs, at predetermined time intervals, a differential signal that indicates the difference between a first detection signal of the specific component obtained by passing the sample gas through the oxidation-reduction unit and a second detection signal of the specific component obtained by connecting the second flow path to the specific component detection unit; a smoothing processing unit that smoothes the difference signal using a filter that shapes the difference signal so that the rate of change of the difference signal becomes smaller according to the magnitude of the rate of change of the difference signal; and a measurement target component concentration calculation unit that calculates the concentration of the measurement target component based on the differential signal smoothed by the smoothing processing unit.

2. 2. The analyzer according to claim 1, wherein the filter adjusts the second differential signal so as to suppress the absolute value of the difference between the rate of change of the first differential signal and the rate of change of the second differential signal outputted after the first differential signal as the absolute value of the difference becomes larger.

3. The analyzer according to claim 2 , wherein the filter suppresses the absolute value based on an arithmetic expression that indicates a change in the rate of change of the second differential signal relative to a change rate of the first differential signal.

4. The analyzer according to claim 3 , wherein the arithmetic expression calculates a weighted average of a rate of change of the first differential signal and a rate of change of the second differential signal.

5. the differential signal output unit outputs the differential signal, which is a digital signal; The analysis device according to claim 1 , wherein the filter is a digital filter.

6. The analyzer according to claim 5 , wherein the digital filter is an adaptive filter configured so that the amount by which the absolute value is suppressed is adjustable.

7. a first response time adjusting unit that adjusts a first response time, which is the time it takes for the sample gas to pass through the first flow path and the specific component detecting unit; a second response time adjusting unit that adjusts a second response time, which is the time it takes for the sample gas to pass through the second flow path and pass through the specific component detecting unit, 7. The analytical device according to claim 1, wherein the differential signal output unit outputs the differential signal based on the first response time adjusted by the first response time adjustment unit and / or the second response time adjusted by the second response time adjustment unit.

8. 8. The analysis device according to claim 7, wherein the first response time adjustment unit and / or the second response time adjustment unit adjusts the first response time and / or the second response time so that a difference between the first response time and the second response time becomes zero.

9. 9. The analytical device according to claim 1, wherein the specific component is nitrogen oxide when the component to be measured is ammonia, the specific component is nitric oxide when the component to be measured is nitrogen oxide, and the specific component is sulfur dioxide when the component to be measured is hydrogen sulfide.

10. An analytical method for analyzing a measurement target component contained in a sample gas, comprising: an analyzer including a first flow path through which the sample gas is discharged and which has an oxidation-reduction unit that oxidizes or reduces the component to be measured; a second flow path through which the sample gas is discharged and which discharges the component to be measured; a specific component detection unit that is discharged from the first flow path and the second flow path and detects a specific component that is an oxide or a reduction product of the component to be measured; and a flow path switching unit that switches a flow path connected to the specific component detection unit to either the first flow path or the second flow path, a differential signal output indicating the difference between a first detection signal of the specific component obtained by connecting the first flow path to the specific component detection unit and passing the sample gas through the oxidation-reduction unit and a second detection signal of the specific component obtained by connecting the second flow path to the specific component detection unit at predetermined time intervals; smoothing the differential signal using a filter that shapes the differential signal so that the rate of change of the differential signal becomes smaller according to the magnitude of the rate of change of the differential signal; and calculating the concentration of the component to be measured based on the smoothed differential signal.

11. An analysis program for analyzing a measurement target component contained in a sample gas, an analyzer including a first flow path through which the sample gas is discharged and which has an oxidation-reduction unit that oxidizes or reduces the component to be measured; a second flow path through which the sample gas is discharged and which discharges the component to be measured; a specific component detection unit that is discharged from the first flow path and the second flow path and detects a specific component that is an oxide or a reduction product of the component to be measured; and a flow path switching unit that switches a flow path connected to the specific component detection unit to either the first flow path or the second flow path, a function as a differential signal output unit that outputs, at predetermined time intervals, a differential signal indicating the difference between a first detection signal of the specific component obtained by connecting the first flow path to the specific component detection unit and passing the sample gas through the oxidation-reduction unit and a second detection signal of the specific component obtained by connecting the second flow path to the specific component detection unit; a function as a smoothing processing unit that smoothes the difference signal using a filter that shapes the difference signal so that the rate of change of the difference signal becomes smaller according to the magnitude of the rate of change of the difference signal; and a function as a measurement target component concentration calculation unit that calculates the concentration of the measurement target component based on the difference signal smoothed by the smoothing processing unit.

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