JP2008216025A - Exhaust gas measuring instrument and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas measuring instrument in which a gas chromatograph that can obtain reliability in a measuring result is incorporated, and to provide an exhaust gas measuring method. <P>SOLUTION: Since the measurement result of the gas chromatograph 2 is a measured result of exhaust gas, from which CO<SB>2</SB>or moisture is removed, in other words, the same result as where a definite amount or larger for the exhaust gas is introduced into a concentration part 11, it is necessary to correct the measured result. Then, CO<SB>2</SB>and moisture in the exhaust gas are measured, by a concentration detector 3 and a humidity detector (hygrometer) 4, and the measured result is outputted to a correction computing part 5 via signal lines 3a and 4a. Correction for adding the measuring results of the concentration detector 3 and the humidity detector (hygrometer) 4 to the measuring results of the gas chromatograph 2 is carried out in the correction computing part 5, and the correction result is displayed on a display part 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus and a method for measuring HC (hydrocarbon) concentration in automobile exhaust gas.

Various exhaustive components such as NO _X , SO _X , CO, CO ₂ , and HC are contained in the exhaust gas of automobiles.
A measuring device disclosed in Patent Document 1 is known as a device for measuring harmful components in exhaust gas of automobiles using gasoline as fuel. This measuring device collects automobile exhaust gas in a sampling bag, and transports this sampling bag to the place where the measuring device is installed to analyze the components. In particular, fuel with a low gasoline mixing ratio was burned. In some cases, the exhaust gas is likely to condense, and accurate measurement values cannot be obtained.

  As for the exhaust gas of automobiles using gasoline as fuel, the total content of HC in the exhaust gas is generally measured by a hydrogen flame ionization measuring instrument.

  On the other hand, recently, alternative fuels such as natural gas other than gasoline are being used. In the case of this alternative fuel, the ratio of the HC component in the exhaust gas is different from that of gasoline. In other words, in HC (hydrocarbon), there are alkanes composed of carbon single bonds, alkenes having carbon double bonds, alkynes having triple bonds, and aromatics based on benzene. Each system has different photochemical reactivity. Therefore, even if the total amount of HC (hydrocarbon) is the same, the influence on the environment is different.

  A gas chromatograph is used to perform qualitative and quantitative analysis of the HC component in the exhaust gas. Patent Document 2 proposes an automatic analyzer for sample gas using a gas chromatograph. In order to perform qualitative analysis and quantitative analysis of a specific chemical species in a gas chromatograph, it is necessary to concentrate the sample gas. For this reason, in Patent Document 2, before introducing the sample gas into the gas chromatograph analyzer, the sample gas is condensed by passing through a trap tube disposed in a Dewar bottle filled with liquid nitrogen, and then the trap tube is heated. The sample gas condensed is rapidly evaporated to concentrate the sample gas.

JP 2000-035388 Japanese Unexamined Patent Publication No. 07-031801

  In the measurement by the hydrogen flame ionization measuring instrument, even if the total amount of HC can be measured, it cannot be accurately measured up to the type of HC. On the other hand, in the case of a gas chromatograph, qualitative and quantitative analysis can be performed, but there is a problem of condensation. For example, in Patent Document 2, when the three-way valves 20b and 20e are closed after the sampling gas is sucked by the pump disposed in the pipe line 20H, the pressure in the sample loop 20s having a predetermined capacity is reduced. High pressure for a moment causes condensation. Condensation also occurs due to a temperature difference between the sample device including the pipe line and the three-way valve and the sample gas in the sampling bag.

The resulting condensation is difficult to eliminate with the carrier gas, and the HC component dissolves in this condensation, and accurate measurement cannot be performed.
Specifically, FIG. 8 shows the result of measuring the total content of HC in the exhaust gas of an automobile fueled with gasoline using both a flame ionization measuring instrument and a conventional gas chromatograph, and FIG. 9 shows the correlation between the two. It is a graph to show. In this measurement, the value measured with a flame ionization measuring instrument is considered to be an accurate value. There is an average difference of about 8% between the total HC content measured with a flame ionization measuring instrument and the total HC content measured with a conventional gas chromatograph, and this value is low (strict). This is a big problem for alternative fuel vehicles such as natural gas vehicles.

  In order to solve the above-mentioned problems, an exhaust gas measuring device according to the present invention includes a sampling bag for storing automobile exhaust gas, a concentrating device for concentrating exhaust gas in the sampling bag, and an exhaust gas concentrated by the concentrating device. A gas chromatograph for analyzing the above, a concentration detection device for detecting the concentration of a specific component other than HC (hydrocarbon) in the exhaust gas in the sampling bag, and a humidity for detecting moisture in the exhaust gas in the sampling bag A detection device, a correction calculation unit that corrects the analysis value in the gas chromatograph based on values detected by the concentration detection device and the humidity detection device, and a display unit that displays the value corrected by the correction calculation unit. The configuration was provided.

  Further, the exhaust gas measuring method according to the present invention concentrates the exhaust gas in the sampling bag and analyzes HC (hydrocarbon) in the exhaust gas of the automobile by a gas chromatograph, and in parallel with this analysis, The concentration and water content of specific components other than HC (hydrocarbon) in the exhaust gas were detected, the analysis value by the gas chromatograph was corrected based on this detection value, and this correction value was displayed.

The specific component other than HC (hydrocarbon) whose concentration is detected by the concentration detector refers to a component that affects the HC (hydrocarbon) concentration by gas chromatography, and is typically CO ₂ (carbon dioxide). .

According to the present invention, when the HC contained in the exhaust gas is analyzed by the gas chromatograph, the ratio of the components in the exhaust gas, such as CO ₂ (carbon dioxide) and water, which affects the HC analysis is measured. Since the measurement value of the gas chromatograph is corrected based on this measurement value, accurate HC analysis can be performed.

  FIG. 6 shows the result of measuring the total content of HC in the exhaust gas of an automobile fueled with gasoline using both the flame ionization measuring instrument and the measuring apparatus of the present invention incorporating a gas chromatograph, and FIG. 7 shows the correlation between the two. It is a graph which shows. From these graphs, according to the present invention, the difference between the hydrogen ionization measuring instrument and the measuring device of the present invention incorporating the gas chromatograph is 2.0% for low-pollution vehicles and 3.0% for ultra-low-pollution vehicles. % And −2.5%, which shows that the reliability of the measurement result is higher than the conventional one.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of an exhaust gas measuring device according to the present invention, and FIGS. 2 to 5 are diagrams showing measurement procedures using the exhaust gas measuring device.

  The exhaust gas measuring device according to the present invention includes a concentrating device 1, a gas chromatograph 2, a concentration detecting device 3, a humidity detecting device (hygrometer) 4, a correction calculation unit 5, a display unit 6 and a storage unit 7.

  The concentration device 1 includes a concentration unit 11, a separation unit 12, a sampling unit 13, a volume measuring device 14, and a switching valve 15. The switching valve 15 is connected to a He gas source 16 by a carrier gas supply pipe 16a, and is connected to a sampling bag 17 for storing the exhaust gas of an automobile by an exhaust gas supply pipe 17a. 11a and a discharge pipe 11b, a separation unit 12 of the concentrating device 1, a supply pipe 12a and a discharge pipe 12b, a sampling unit 13 of the concentrating device 1 and a supply pipe 13a, and the volume measuring device. 14 and a supply pipe 14a, and a discharge pipe 14b from the volume measuring device 14 is provided with an exhaust pump 18.

  A discharge pipe 13b from the sampling unit 13 is connected to the gas chromatograph 2, and a signal line 2a from the gas chromatograph 2 is connected to the correction calculation unit 5. The correction calculation unit 5, the display unit 6, and a storage unit. 7 is connected by signal lines 5a and 5b.

Further, the concentration detection device 3 is for detecting the concentration of a specific component other than HC in the sample gas in the sampling bag 17, for example, CO ₂ , and is connected to the correction calculation unit 5 by a signal line 3 a, The humidity detection device (hygrometer) 4 measures moisture in the sample gas and is connected to the correction calculation unit 5 through a signal line 4a.

A measurement method using the exhaust gas measuring apparatus having the above configuration will be described below.
First, the switching valve 15 is operated to replace the concentrating unit 11, the supply pipe 11a, and the discharge pipe 11b with helium gas from the He gas source 16. Other inert gases such as nitrogen gas may be used instead of helium gas.

  Next, as shown in FIG. 2, the switching valve 15 is operated to supply an exhaust gas supply pipe 17a of the sampling bag 17, a supply pipe 11a and a discharge pipe 11b of the concentrating unit 11, and a supply pipe 14a and a discharge pipe 14b of the volume measuring device 14. , The exhaust pump 18 is driven, and exhaust gas is introduced into the concentrating unit 11.

  The amount of exhaust gas introduced into the concentrating unit 11 can be controlled by measuring the amount of helium gas discharged by the volume measuring device 14.

  Here, since the concentrating unit 11 is cooled in advance to -130 ° C to -150 ° C, the exhaust gas introduced into the concentrating unit 11 is rapidly cooled and condensed.

  Next, by operating the switching valve 15, as shown in FIG. 3, the discharge pipe 11b of the concentration unit 11, the supply pipe 12a and the discharge pipe 12b of the separation unit 12, and the supply pipe 14a and the discharge pipe 14b of the volume measuring device 14 In a communicating state, the temperature of the concentration unit 11 is raised to room temperature, and the temperature of the separation unit 12 is lowered to −15 ° C. to −60 ° C.

As a result, only the HC component in the exhaust gas is collected in the separation unit 12, and CO ₂ in the exhaust gas is diffused into the atmosphere via the exhaust pipe 14b.

Next, by operating the switching valve 15, as shown in FIG. 4, the discharge pipe 12 b of the separation unit 12 and the supply pipe 13 a of the sampling unit 13 are in communication, and the temperature of the separation unit 12 is increased to 180 ° C. The temperature of the sampling unit 13 is lowered to −160 ° C. to −180 ° C. By this operation, the exhaust gas concentrated by removing CO ₂ or moisture is introduced into the sampling unit 13.

  After that, as shown in FIG. 5, the exhaust pipe 13b of the sampling unit 13 is opened and the concentrated exhaust gas is sent to the gas chromatograph 2 for qualitative and quantitative analysis of HC. For the moisture remaining in the concentrating unit 11, after the concentrated exhaust gas is sent to the gas chromatograph 2, the condensing unit 11 is operated by operating the switching valve 15 while the concentrating unit 11 is heated to 150 ° C. And the discharge pipe 14b are in communication with each other and diffused into the atmosphere. And the measurement result of the gas chromatograph 2 is output to the correction | amendment calculating part 5 via the signal wire | line 2a.

The measurement result of the gas chromatograph 2 is the measurement result of the exhaust gas from which CO ₂ , moisture and the like have been removed. In other words, since the exhaust gas is introduced into the concentrating unit 11 beyond the fixed amount, Need to be corrected.

Therefore, in the present invention, the concentration detection device 3 and the humidity detection device (hygrometer) 4 measure CO ₂ and moisture in the exhaust gas, and output the results to the correction calculation unit 5 via the signal lines 3a and 4a. . The correction calculation unit 5 performs correction by adding the measurement results of the concentration detector 3 and the humidity detector (hygrometer) 4 to the measurement results of the gas chromatograph 2. The result is displayed on the display unit 6 and stored in the storage unit 7.

Schematic configuration diagram of an exhaust gas measuring device according to the present invention Schematic configuration diagram explaining the operation from the sampling bag to the concentration unit of the concentration device Schematic configuration diagram explaining the operation from the concentration unit to the separation unit of the concentrator Schematic configuration diagram explaining the operation from the separation unit to the sampling unit of the concentrator Schematic configuration diagram explaining the operation from the sampling unit of the concentrator to the gas chromatograph The graph which shows the result of having measured the total content of HC by the measuring apparatus and hydrogen flame ionization measuring device of this invention. Graph showing the correlation of the measurement results in FIG. The graph which shows the result of having measured the total content of HC by the conventional measuring apparatus (gas chromatograph) and the flame ionization measuring instrument. Graph showing the correlation of the measurement results of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Concentrator, 2 ... Gas chromatograph, 2a ... Signal line, 3 ... Concentration detector, 3a ... Signal line, 4 ... Humidity detector (hygrometer), 4a ... Signal line, 5 ... Correction operation part, 5a, 5b Signal line, 6 Display unit, 7 Storage unit, 11 Concentration unit, 11 a Supply tube, 11 b Discharge tube, 12 Separation unit, 12 a Supply tube, 12 b Discharge tube, 13 Sampling unit, 13 a ... supply pipe, 13b ... discharge pipe, 14 ... volume measuring device, 14a ... supply pipe, 14b ... discharge pipe, 15 ... switching valve, 16 ... He gas source, 16a ... carrier gas supply pipe, 17 ... sampling bag, 17a ... Exhaust gas supply pipe, 18 ... exhaust pump.

Claims (3)

Sampling bag for storing exhaust gas of automobile, concentrating device for concentrating exhaust gas in sampling bag, gas chromatograph for analyzing exhaust gas concentrated in this concentrating device, and in exhaust gas in sampling bag A concentration detection device for detecting the concentration of a specific component other than HC (hydrocarbon), a humidity detection device for detecting moisture in the exhaust gas in the sampling bag, and a value detected by the concentration detection device and the humidity detection device An exhaust gas measuring device comprising: a correction calculation unit that corrects the analysis value in the gas chromatograph based on the above, and a display unit that displays a value corrected by the correction calculation unit. The exhaust gas measuring device according to claim 1, wherein the concentration detecting device detects a concentration of CO ₂ (carbon dioxide) in the exhaust gas. Concentrate the exhaust gas in the sampling bag and analyze HC (hydrocarbon) in the exhaust gas of the automobile by gas chromatograph, and in parallel with this analysis, other than HC (hydrocarbon) in the exhaust gas in the sampling bag An exhaust gas measuring method comprising: detecting a concentration and moisture of a specific component; correcting an analysis value by the gas chromatograph based on the detected value; and displaying the correction value.

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