JPH07107533B2 - Automotive exhaust gas analyzer - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for analyzing aldehydes and alcohols in automobile exhaust gas.

(Prior Art) Exhaust gas from an automobile contains various kinds of components and causes pollution problems, and therefore, the components are strictly regulated.

By the way, it is considered to use alcohol as a fuel for automobiles in preparation for exhaustion of petroleum resources, but a large amount of aldehydes and unburned alcohol may be discharged from the engine by using this as fuel. Therefore, a measuring device for monitoring the emission amount of these components is required. Of course, the sample gas containing only alcohols and aldehydes can be analyzed by the existing gas chromatograph, but the exhaust gas contains other kinds of components and a large amount of gas generated by alcohol combustion. There is a problem that the water content of the water interferes with the analysis.

(Object) The present invention has been made in view of such a problem, and an object of the present invention is to provide an automobile exhaust capable of highly accurately analyzing aldehydes and alcohols contained in exhaust gas. It is to provide a gas analyzer.

(Summary of the Invention) Alcohols and acetaldehyde comprising a heatable sampling gas transfer pipe, a plurality of measuring pipes, a column for separating alcohols and acetaldehyde, and a flame ionization detector for detecting components from the column An alcohol analyzer for analysis, a column for separating formaldehyde, a reduction furnace for reducing formaldehyde to convert it to methane, and a formaldehyde analyzer for detection of components from the reduction furnace, and a formaldehyde analyzer, and a flow path Switching means, wherein the flow path switching means connects the plurality of measuring pipes to the sampling gas transfer pipes in series, respectively, and a flow passage for sucking automobile exhaust gas into the respective measuring pipes, and the measuring pipes. Simultaneously independently to the alcohol analyzer and the formaldehyde analyzer A flow path to be connected is formed.

(Example) Therefore, the details of the present invention will be described below based on an illustrated example.

FIG. 1 shows an embodiment of the present invention. This apparatus is roughly divided into an alcohols and acetaldehyde analysis system (hereinafter referred to as alcohols analysis system) I and a formaldehydes analysis system II. , And each analytical system
A temperature that prevents condensation of exhaust gas, for example,
Sampling sections I a and II a kept at 130 ° C. and measuring sections I b kept at a temperature suitable for analysis, for example, about 100 ° C.,
It is divided into II b.

In this device, reference numeral 1 in the drawing is a flow path switching valve consisting of a 10-way valve arranged in the sampling unit I a, and a heating filter 2 for removing dust and soot is connected to one end of the flow path switching valve and a heater 3 Therefore, the other end of the sampling pipe 4 heated to, for example, about 130 ° C. is connected to the exhaust pipe so that the exhaust gas flows therein. This switching valve 1 includes a measuring pipe 5,
The pre-column 6, the choke column 7, the first separation column 8, the dummy column 9, and the sample injection port 10 are connected.

The pre-column 6 and the dummy column 9 use porous polymer beads as a packing material, and the first separation column 8 uses a terephthalic acid resin having polyethylene glycol coated on the surface as a packing material.

A choke column 12, a dummy column 13, and a second separation column 14 are connected to the discharge end of the first separation column 8 via a second switching valve 11 composed of a four-way valve. Second separation column
A hydrogen flame ionization detector 15 is connected to the discharge end of 14.

Next, the formaldehyde analysis system II will be described. In the figure, reference numeral 21 is a switching valve consisting of a 10-way valve, and the switching valve 1 of the alcohol analysis system I is connected to the switching valve 1 by a pipe 22 and exhaust gas flows in, Measuring pipe 23, pre-column 24,
Choke column 25, first separation column 26, dummy column
27, the sample injection port 28, and the suction pump 29 are connected.
The pre-column 24, the first separation column 26, and the dummy column 27 are filled with porous polymer beads.

The discharge end of the first separation column 26 is a switching valve composed of a 4-way valve.
A second separation column 31, a dummy column 32, and a choke column 33 are connected via 30. This second separation column
A reduction catalyst furnace 34 into which hydrogen flows is connected to the discharge end of 31, and a hydrogen flame ionization detector 35 is connected to the discharge end of the reduction catalyst furnace 34.

In this embodiment, when the switching valves 1 and 21 of both analysis systems I and II are set to the first position (solid line in the figure), the gas sampling pipe 4, the measuring pipe 5, the measuring pipe 23, and the suction pump 29 are connected to the first position. One flow path is formed. When the suction pump 29 is operated in this state, the exhaust gas from the engine flows into the measuring pipe 5 and the measuring pipe 23 through the gas sampling pipe 4, and is discharged from the discharge port of the suction pump 29 to the atmosphere. During this inflow process, the sampling pipe 4, the measuring pipes 5 and 23, and the switching valves 1 and 21 are maintained at 130 ° C. and are in a heated state, so that the inflowing exhaust gas condenses a large amount of water contained therein. Without maintaining the composition, the composition as it is discharged from the engine is maintained.

On the other hand, in each of the analysis systems I and II, the dummy column 9 (2
7), first separation column 8 (26), choke column 12 (3
3) flow path, sample injection port 10 (28), pre-column 6
(24), the flow path to the choke column 7 (25), and the flow path to the dummy column 13 (32), the second separation column 14 (31), and the hydrogen flame ionization detector 15 (35) are formed. hand,
These two flow paths are purged by the carrier gas and maintained in a clean state.

In this way, when the insides of the two measuring pipes 5 and 23 have been sufficiently replaced with the exhaust gas, the switching valves 1 and 21 are used to
Set the flow path (dotted line in the figure). As a result, the exhaust gas discharged at the same time is sampled in the two measuring pipes 5 and 23 by an amount determined by the volumes of the measuring pipes 5 and 23.

The exhaust gas sampled in the measuring tube 5 of the alcohol analysis system I is introduced into the pre-column 6 by the carrier gas flowing in through the sample injection port 10 and is separated by the porous polymer beads contained therein. The components separated by the pre-column 6 flow into the first separation column 8 and are further separated by the polyethylene glycol contained therein. Of the components separated here,
Interfering components such as carbon monoxide, methane, carbon dioxide, etc., which are initially discharged, and formaldehyde are sequentially discharged to the atmosphere through the choke column 12 via the switching valve 11. When the discharge of the interfering components is completed in this way, the switching valve 11
Is switched to the second flow path (dotted line in the figure), alcohols and aldehydes flow into the second separation column 14. When the alcohols and aldehydes have finished flowing into the second separation column 14, the switching valve 11 is switched to the original flow path (solid line in the figure). As a result, only the target component is further separated into each component by the second separation column 14, and the concentrations of methyl alcohol, ethyl alcohol and acetaldehyde are detected by the hydrogen flame ionization detector 15 (Fig. 2a).

The exhaust gas contained in the measuring tube 23 of the formaldehyde analysis system II is introduced into the pre-column 24 by the carrier gas flowing in through the sample inlet 28, and is separated by the porous polymer beads contained therein. The components separated by the pre-column 24 flow into the first separation column 26, and are further separated by the porous polymer beads contained therein. Among the components separated here, interfering components such as carbon monoxide, methane, and carbon dioxide that are initially discharged are sequentially released into the atmosphere through the choke column 33 via the switching valve 30. When the interfering components other than formaldehyde are discharged in this way, the switching valve 30 is set to the second position.
Formaldehyde flows into the second separation column 31 when the flow path is switched to (dotted line in the figure). When the formaldehyde has finished flowing into the second separation column 31, the switching valve 30 is switched to the original flow path (solid line in the figure), and the formaldehyde is supplied to the second separation column 31.
The separation column 31 further separates from the contaminants. The formaldehyde thus discharged from the second separation column 31 flows into the reduction furnace 34, is reduced by hydrogen and is converted into methane, and the concentration is detected by the hydrogen flame ionization detector 35 (second Figure b). By converting formaldehyde into methane and then detecting it with the flame ionization detector 35, it is possible to effectively use a flame ionization detector that is not sensitive to formaldehyde, and to obtain acetaldehyde,
Methyl alcohol, ethyl alcohol, and formaldehyde can be detected at similar sensitivity levels, and the apparatus can be simplified.

By the way, in the process of switching the switching valves 1 (21) and 11 (30), the choke columns 7 (25) and 12 (33) and the dummy columns 9 (27) and 13 (32) are used to connect the two channels. Since the resistances are set to be the same, the discharge conditions of the separated components do not change, and high separation accuracy is guaranteed.

When configuring each analyzer, if a known amount of sample is injected from the sample injection port with the switching valves 1 and 21 set to the second position (the flow path indicated by the dotted line in the figure), The respective samples flow into the precolumns 6 and 24 through the measuring tubes 5 and 23 by the carrier gas, and are detected by the detectors 15 and 35 through the same process as described above.

[Example] Humidified air was enclosed in a container, and methyl alcohol,
A standard sample was prepared by mixing 10 ppm each of ethyl alcohol, acetaldehyde, and formaldehyde, and the standard sample was analyzed by the above analyzer. Chromatograms with unimodal peaks of ethyl alcohol and ethyl alcohol were obtained from formaldehyde analysis system II as shown in Fig. II.

In addition, nitrogen gas is sealed in the container, methyl alcohol,
A standard sample was prepared by mixing 10 ppm each of ethyl alcohol, acetaldehyde, and formaldehyde, and the standard sample was analyzed by the above-mentioned analyzer. The analysis systems I and II showed the results shown in FIGS. It was found that a chromatogram similar to that of was obtained, which did not affect the quantitative analysis.

From these, it was found that the retention time and the peak area of each target component are not related to the oxygen concentration and water content in the base air.

Furthermore, when the relationship between the concentrations of the components and their peak areas was investigated, a calibration curve with extremely high linearity as shown in FIG. 4 could be obtained.

When the exhaust gas from the engine using alcohol as fuel was measured based on this calibration curve, it was confirmed from the alcohols analysis system I that acetaldehyde, methyl alcohol, and ethyl alcohol were separated with high accuracy as shown in FIG. Also, formaldehyde could be detected from the formaldehyde analysis system II as shown in Fig. II.

Further, when the exhaust gas from the engine using light oil as a fuel was measured, acetaldehyde, methyl alcohol, and formaldehyde in the exhaust gas could be detected as shown in FIGS.

From these facts, it was also revealed that trace amounts of alcohols and aldehydes in exhaust gas can be analyzed with high accuracy regardless of the type of fuel.

(Effect) As described above, in the present invention, a heatable sampling gas transfer pipe, a plurality of measuring pipes, a column for separating alcohols and acetaldehyde, and a hydrogen flame ionization for detecting components from the column An alcohols analyzer consisting of a detector for analyzing alcohols and acetaldehyde, a column for separating formaldehyde,
A reduction furnace that reduces formaldehyde to methane,
And a formaldehyde analyzer comprising a hydrogen flame ionization detector for detecting components from the reduction furnace, and flow path switching means, the flow path switching means connecting a plurality of measuring pipes to the sampling gas transfer pipes in series, respectively. The exhaust gas from the engine is designed to have a flow path for sucking automobile exhaust gas into each metering pipe and a flow path for independently connecting the metering pipe to the alcohol analyzer and the formaldehyde analyzer at the same time. Since the gas generated at the same time can be collected in an independent measuring pipe without causing dew condensation, the exhaust gas components including alcohols, acetaldehyde, and formaldehyde are highly reliable, especially in engines that use alcohols as fuel. Highly accurate and simultaneous analysis can be performed with a hydrogen flame ionization detector having the property.

In addition, since the analytical system is divided into two, an alcohol type and a formaldehyde type, it is possible to easily select a stationary phase suitable for the component, and to reliably separate and measure similar components. You can

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention, FIG. 2 is a timing chart showing the operation of the same apparatus, FIG. 3 is a diagram of a chromatogram showing the measurement results of a standard sample by the same apparatus, FIG. 4 is a diagram showing a result of calibration by the same apparatus, and FIGS. 5 and 6 are chromatograms showing results of measurement of vehicle exhaust gas by the same apparatus, respectively. I ... Alcohol analysis system II ... Formaldehyde analysis system Ia, IIa ... Sampling section Ib, IIb ... Measuring section 1 ... Switching valve, 3 ... Heater 4 ... Sampling pipe, 5 ... Measuring tube 6 …… Pre-column 8, 14 …… Separation column, 11 …… Switching valve 15 …… Hydrogen flame ionization detector 21 …… Switching valve, 23 …… Measuring tube 24 …… Pre-column 26, 31 …… Separating Column 30 …… Switching valve, 34 …… Reduction furnace 35 …… Hydrogen flame ionization detector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Oi 16-3 Onogawa, Yatabe-cho, Tsukuba-gun, Ibaraki Inside Institute for Pollution Resources, Institute of Industrial Technology (72) Hideo Ouchi 16-3 Onogawa, Yatabe-cho, Tsukuba-gun, Ibaraki Industry (72) Inventor Shigeo Yasui Shigeo Yasui 1-63-1, Shibasaki, Chofu-shi, Tokyo Shimadzu Corporation Tokyo Research Institute (72) Inventor Mikihiko Suzuki 1-63-1, Shibasaki, Chofu-shi, Tokyo Shimazu Co., Ltd. Hideo Kawahara, Examiner, Tokyo Research Laboratory of Manufacturing Co., Ltd. (56) References Japanese Patent Publication No. 51-2836 (JP, B2) Japanese Patent Publication No. 60-16566 (JP, B2)

Claims (1)

[Claims] 1. A sampling gas transfer pipe that can be heated, a plurality of measuring pipes, a column for separating alcohols and acetaldehyde, and a flame ionization detector for detecting components from the column, and alcohols and acetaldehyde. An alcohol analyzer for analysis, a column for separating formaldehyde, a reduction furnace for reducing formaldehyde to convert it to methane, and a formaldehyde analyzer for detection of components from the reduction furnace, and a formaldehyde analyzer, and a flow path Switching means, wherein the flow path switching means connects the plurality of measuring pipes to the sampling gas transfer pipes respectively in series to allow the vehicle exhaust gas to be sucked into the respective measuring pipes, and the measuring pipes, respectively. Independently contact the alcohol analyzer and the formaldehyde analyzer simultaneously. An automobile exhaust gas analyzer that forms a continuous flow path.