JP2003028765A - Analytical device and method of particulate matter in engine exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an analytical device and a method of particulate matter in engine exhaust gas capable of measuring highly accurately the trace PM in the engine exhaust gas. SOLUTION: The exhaust gas G flowing in an exhaust pipe 24 linked to an engine 23 is diluted by dilution air A in a dilution pipeline 25. The diluted exhaust gas is introduced into a sampling passage 29, and the particulate matter included in the diluted exhaust gas is collected by a filter 4 installed in the sampling passage 29. When analyzing the particulate matter in the engine exhaust gas for analyzing each component of SOF, a sulfate and soot in the particulate matter 3 collected by the filter, the particulate matter is collected prior to the analysis by using the filter 4 in a state where the exhaust gas is not passed in the exhaust pipe and the dilution pipeline, and each component of the SOF, the sulfate and the soot in the particulate matter is analyzed, respectively. Hereby a background value remaining in the passage of the exhaust pipe or the like is determined, and the values measured by the analysis of each component of the SOF, the sulfate and the soot when passing the exhaust gas G in the exhaust pipe 24 are corrected based on the background value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to particulate matter (particulate matter, hereinafter referred to as PM) contained in gas discharged from, for example, a diesel engine.
Analysis apparatus and method.

[0002]

2. Description of the Related Art As a method of measuring PM contained in exhaust gas of a diesel engine, high temperature exhaust gas discharged from a diesel engine is diluted with clean air, and the diluted exhaust gas is sucked in a fixed volume to capture PM with a filter. A filter weight method is generally known in which the filter is collected, weighed with a precision balance or the like, and quantitatively analyzed based on the weight difference from the filter before PM collection.

However, in the above-described filter weight method, the water adsorbed on the filter has a great influence as a measurement error, so that a constant temperature / constant humidity treatment is required to keep the water content in the filter constant before and after the collection. Also, low concentration PM
When measuring the exhaust gas of, for example, 0.1 mg of PM collected on a 200 mg filter needs to be accurately weighed, and the measurement error of the weight of the filter itself greatly affects the measurement error of the PM weight. There is such a problem.

On the other hand, as disclosed in Japanese Examined Patent Publication No. 7-58264, a method of heating the filter trapping PM stepwise in a heating furnace to oxidize PM and measure it with a gas analyzer There is.

However, most of PM is an inorganic carbon called soot (hereinafter referred to as soot) and SOF (Soluble Organic Fr).
A hydrocarbon called "action" (hereinafter referred to as SOF) and a sulfate hydrate called "sulfate" (hereinafter referred to as "SOF")
It is difficult to separate the high-boiling point SOF and reduce the sulfate in an oxidizing atmosphere by the method described in the above publication. Therefore, the SOF occupying most of the PM, It was difficult to separate the sulfate and soot individually and measure their concentration or weight.

As a solution to the above-mentioned drawbacks of the prior art, the applicant of the present application has filed a patent application for "Analysis method and apparatus for particulate matter in engine exhaust gas" on March 29, 2000. (Japanese Patent Application No. 2000-92283). The content of the invention of this patent application is that a filter that collects PM contained in engine exhaust gas is provided in a heating furnace, and first, the filter is heated at a predetermined temperature while flowing an inert gas into the heating furnace to remove PM in PM. The SOF and the sulfate are vaporized, and the vaporized SOF is oxidized to CO ₂ , while the vaporized sulfate is reduced to SO ₂ , and the CO ₂ and SO ₂
Was analyzed by gas analysis unit, then the while flowing oxygen into the heating furnace and heating the filter to oxidize the remaining soot on the filter to generate CO _2, the CO ₂ gas analyzer It is to analyze.

According to the above-described method and apparatus for analyzing particulate matter in engine exhaust gas, SOF, sulfate and soot in PM contained in engine exhaust gas can be individually and easily separated with a small amount even if they are minute amounts. SPM, sulfate, and soot, which can be measured well, and which cannot be measured by the conventional filter weight method or the method described in Japanese Patent Publication No. 7-58264 mentioned at the beginning, account for most of PM. It is possible to separately measure the concentration or weight of each, and it is also possible to accurately measure low-concentration PM.

[0008]

In the method and apparatus for analyzing particulate matter in engine exhaust gas, the exhaust gas from the engine is once discharged to the exhaust pipe,
All (or part) of it is introduced into the diluting line and diluted with clean air in the diluting line,
Part (or all) of this diluted exhaust gas is sucked into the gas sampling flow path in a fixed volume, and PM in the diluted exhaust gas is filtered by the filter provided in this gas sampling flow path.
However, a part of PM in the exhaust gas adheres to the inner wall of the exhaust pipe, the diluting pipe or the gas sampling flow passage, and is separated from the inner wall during the next analysis. It may be mixed in the exhaust gas.

The above-mentioned mixed PM causes almost no problem at a relatively high concentration measurement level, but in recent exhaust gas measurement of low emission vehicles, PM is accurately measured in a very low concentration region. Therefore, the mixed PM has a great influence on the measurement result as a so-called background.

The present invention has been made with the above matters in mind, and its object is to trace a minute amount of PM in engine exhaust gas.
P in engine exhaust gas that can measure P with high accuracy
M analyzer and method.

[0011]

In order to achieve the above object, according to the present invention, exhaust gas flowing through an exhaust pipe connected to an engine is diluted with dilution air in a dilution pipe, and the diluted exhaust gas is sampled. The particulate matter contained in the diluted exhaust gas is introduced into the flow path, and the filter provided in the gas sampling flow path collects the SOF in the particulate matter collected in the filter,
In an analyzer for particulate matter in engine exhaust gas that analyzes each component of sulfate and soot, prior to the analysis, the particulate matter of the particulate matter using a filter in a state where exhaust gas does not flow to the exhaust pipe and the dilution pipe line is used. Collect,
By analyzing each component of SOF, sulfate and soot in the particulate matter, the background value remaining in the flow path of the exhaust pipe or the like is obtained, and based on this background value, the exhaust gas is exhausted to the exhaust pipe. The analytical value of each component of SOF, sulfate and soot when flowing is corrected.

More specifically, the exhaust gas flowing through the exhaust pipe connected to the engine is diluted with the diluting air in the diluting pipe, and the diluted exhaust gas is introduced into the gas sampling passage, and the gas sampling passage is formed. The PM provided in the diluted exhaust gas is collected by the filter provided in the heating furnace, and the filter that collects the PM is provided in the heating furnace. Is heated at a predetermined temperature to vaporize SOF and sulfate in PM and oxidize the vaporized hydrocarbon to CO ₂ , while reducing the vaporized sulfate to SO ₂ and to gasify the CO ₂ and SO ₂ . After analysis by the analysis unit, the filter is heated while flowing oxygen into the heating furnace to oxidize the soot remaining on the filter to reduce CO 2.
_When the PM in the exhaust gas is analyzed by generating ₂ and analyzing this CO ₂ in the gas analysis unit, a filter is used prior to the analysis without exhaust gas flowing through the exhaust pipe and the dilution pipe. PM is collected by using a filter, and a filter that collects the PM is provided in the heating furnace. First, the filter is heated at a predetermined temperature while flowing an inert gas into the heating furnace to heat the SOF in the PM. and vaporizing sulphate, while the CO ₂ by oxidizing SOF vaporized, and SO ₂ by reducing vaporized sulfate, the CO ₂ and SO ₂ was analyzed by a gas analyzer unit, then the heating furnace The filter is heated while flowing oxygen into the soot to oxidize the soot remaining on the filter to generate CO ₂ , and the CO ₂ is analyzed by the gas analysis section to remain in the flow path of the exhaust pipe or the like. P Analyzing the determined background values, than it corrects the analysis value of the PM trapped by the filter when a current of exhaust gases in the exhaust pipe.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The details of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of the present invention. First, FIG. 1 schematically shows one configuration example of a gas analyzer 1 used in a method for analyzing PM in engine exhaust gas of the present invention (hereinafter, simply referred to as an analysis method). A heating furnace for heating a filter 4 that collects PM3 contained in engine exhaust gas (a configuration for collecting PM will be described later), which is, for example, an electric furnace, and includes a heater 5 for heating. The heating state of the heating heater 5 is controlled by a temperature adjusting mechanism (not shown), so that the temperature inside the heating furnace 2 is set to an arbitrary predetermined temperature.

Reference numeral 6 denotes a gas supply section for selectively supplying an inert gas (for example, nitrogen gas) or oxygen to the heating furnace 1, which is a flow rate control device such as a mass flow controller having functions of flow rate measurement and flow rate control. A nitrogen gas supply passage 9 and an oxygen supply passage 10 respectively provided with 7 and 8, and a connecting passage 1 to the downstream side of these supply passages 9 and 10 and the heating furnace 2.
1 is connected to each of the three-way solenoid valves 12.

Reference numeral 13 is a gas flow passage through which the gas generated in the heating furnace 2 flows, and its downstream side is branched into two mutually parallel gas flow passages 14 and 15. An oxidation / reduction processing unit 16 and a gas analysis unit 17 are provided in series in this order on the downstream side of these gas flow paths 14 and 15.

More specifically, one gas passage 14 has
A flow meter 18 such as a mass flow meter, for example, an oxidation catalyst such as CuO is provided, and an oxidation processing unit 16A and a CO ₂ analyzer 17A, which are connected to an oxygen supply path 19 for supplying oxygen, are provided in this order. Then, in the other gas flow path 15, a flow meter 20 similar to the flow meter 18,
For example, a reduction processing unit 16B provided with a reduction catalyst such as carbon and an SO ₂ analyzer 17B are provided in this order. The CO ₂ analyzer 17A and SO ₂ analyzer 17B used here are, for example, a non-dispersive infrared gas analyzer (ND).
IR gas analyzer). That is, the oxidation / reduction processing unit 1
6, the oxidation processing unit 16A and the reduction processing unit 16B are arranged in parallel with each other, and in the gas analysis unit 17, the CO ₂ analyzer 17A and SO ₂ analyzer 17B are arranged in parallel with each other. .

Although not shown, the gas flow paths 11,
13 and portions of the gas flow paths 14 and 15 up to the gas analysis unit 17 (including the oxidation treatment unit 16A and the reduction treatment unit 16B) are configured so that they can be heated and kept at a proper temperature by a heater, for example. There is. This is to prevent changes in the components contained in the gas generated in the heating furnace 2 and to ensure that the oxidation and reduction processes are performed.

Reference numeral 21 denotes an operation based on signals (flow rate signal Q, concentration signal C, etc.) from various parts of the apparatus,
An arithmetic control unit that sends a control signal to each unit of the device based on the arithmetic result, and is composed of, for example, a personal computer.

By the way, the filter 4 is made of a material having a small amount of impurities, for example, quartz. To collect PM contained in the engine exhaust gas, the filter 4 is constructed as shown in FIG. A gas sampling device 22 is used which is capable of flowing a constant flow rate of the exhaust gas from.

That is, in FIG. 2, reference numeral 23 is a diesel engine mounted in, for example, an automobile. An exhaust pipe 24 is connected to the engine 23, and a downstream end 24 a thereof is connected to a diluting pipe line (also referred to as a diluting tunnel) 25. The dilution pipe line 25 is discharged into the exhaust pipe 24,
The whole amount of the engine exhaust gas G introduced into the pipe 25 is diluted with clean air A, and the flowing gas has a constant flow rate.
And an air introduction portion 25a including a CFV (Critical Flow V) on the downstream side.
enturi) 27 and suction pump 28 are provided.

29 is a CFV 27 with respect to the dilution pipe line 25.
The sampling probe 29a is inserted and connected in the diluting pipe 25 in the gas sampling flow passage connected at a point slightly upstream of the gas G of the gas G diluted with the air A in the diluting pipe 25. A part is sampled as the sample gas S. The downstream side of the gas sampling flow path 29 has two flow paths 30, 31.
And a filter device 3 for collecting PM contained in the sample gas S into the respective flow channels 30 and 31.
2, 33 are provided, one flow path 30 is a sample gas flow path for flowing exhaust gas during PM collection, and the other flow path 31 is a bypass flow for flowing exhaust gas during PM non-collection. Each is configured on the road. The filter device 3
One of the filter devices 32 and 33 is for measurement, and the other filter device 33 is a dummy.

Reference numeral 34 is a three-way solenoid valve as a flow path switching means provided on the downstream side of the sample gas flow path 30 and the bypass flow path 31, the downstream side of which is connected to the gas flow path 35. Is provided with a suction pump, such as a roots blower pump 36, whose suction capacity can be changed by controlling the number of revolutions, and a flow meter with high measurement accuracy, such as a Venturi meter 37, in this order.

Next, an analysis method using the analysis device will be described with reference to FIGS. 3 and 4. Figure 4
Shows temporal changes in the atmosphere in the heating furnace 2 and the heating temperature of the filter 4, and the output state in each atmosphere. Reference numerals a and c are CO ₂ concentration outputs, and b is an SO ₂ concentration output.

For convenience of explanation, the measurement with the exhaust gas G flowing from the engine 23 will be described first.

Using the gas sampling device 22 shown in FIG. 2, as shown in FIG. 3B, the exhaust gas G from the engine 23 is sampled at a constant flow rate, and the PM 38 in the exhaust gas G is collected by the filter 4. To gather. At this time, the PM 39 adhering to the inner wall 25 a of the diluting pipe 25 is not covered
Apart from a, it mixes with the exhaust gas G and is also collected by the filter 4.

The heating furnace 2 in which the filter 4 which has collected the PM 3 is preheated to 1000 ° C.
Place it inside. Then, the solenoid valve 12 of the gas supply unit 6 is operated to connect the nitrogen gas supply passage 9 to the heating furnace 2, and nitrogen gas is supplied into the heating furnace 2 via the flow rate control device 7.
The flow rate of nitrogen gas at this time is measured by the flow rate control device 7, and the result is sent to the personal computer 21 as a flow rate signal Q.

In the heating furnace 2, by heating the filter 4 at 1000 ° C. in a nitrogen gas atmosphere, the SOF and the sulfate in the PM 3 collected by the filter 4 are gasified, and these are gasified together with the nitrogen gas. It flows out into the gas flow path 13.

The gas flowing out of the gas flow path 13 (containing the gasified SOF, sulfate and other generated gas) flows through the gas flow paths 14 and 15 in a bisected state. Then, the gas flowing through one of the gas flow paths 14 passes through the flowmeter 18 and the oxidation / reduction processing unit 16A
Flow into. Oxygen is supplied to the oxidation treatment unit 16A, and SOF of the gasified SOF and the sulfate is oxidized by the oxidation catalyst and oxygen, and CO
₂ and H ₂ O, and together with other gases, gas analyzer 1
It is sent to the CO ₂ analyzer 17A of No. 7 and the CO ₂ concentration is measured. In addition, the gas flowing through the other gas flow path 15 passes through the flow meter 20 and the reduction processing unit 16B of the oxidation / reduction processing unit 16
Of the gasified SOF and sulfate, the sulfate is reduced by the reduction catalyst, and SO
It becomes ₂ and is sent to the SO ₂ analyzer 17B of the gas analysis unit 17 together with other gas, and the SO ₂ concentration is measured.

Then, the gas analyzer 17 outputs CO ₂ concentration and SO ₂ concentration signals having the shapes shown by reference characters a and b in FIG.
Input to 1. Since a signal indicating the flow rate of nitrogen gas is input to the personal computer 21, this nitrogen gas flow rate and C
Based on the O ₂ concentration and the SO ₂ concentration, the weights of SOF and sulfate in the PM3 captured by the filter 4 are obtained, respectively.

Next, the solenoid valve 12 of the gas supply unit 6 is switched to connect the oxygen supply passage 10 to the heating furnace 2, and oxygen is supplied into the heating furnace 2 via the flow rate control device 8. The flow rate of oxygen at this time is measured by the flow control device 8, and the result is sent to the personal computer 21 as a flow signal.

In the heating furnace 2, under an oxygen atmosphere.
By heating the filter 4 at 1000 ° C.
The soot remaining in the filter 4 burns (oxidizes)
CO ₂And CO (which is almost trace amount) are generated,
These flow out into the gas flow path 13 together with oxygen.

The gas flowing out to the gas flow path 13 (including CO ₂ and CO generated by the combustion and other generated gas) branches into the gas flow paths 14 and 15.
The gas flowing through one of the gas flow paths 14 is the flow meter 1
8 and flows into the oxidation / reduction processing unit 16A of the oxidation / reduction processing unit 16. Since oxygen is supplied to the oxidation treatment section 16A, CO contained in the gas is oxidized to form C
It becomes O ₂ , is mixed with CO _{2 in} the gas, and is sent to the CO ₂ analyzer 17A of the gas analysis unit 17 together with other gas,
The CO ₂ concentration is measured. In addition, the gas flowing through the other gas flow path 15 passes through the flowmeter 20 and is subjected to the oxidation / reduction processing unit 16
Of the SO ₂ analyzer 17B of the gas analyzer 17 without any treatment.
Sent to and discarded without measuring the concentration.

Then, from the gas analysis section 17, as shown in FIG.
At, a signal representing the CO ₂ concentration having a shape as indicated by the symbol c is output, and this is input to the personal computer 21. Since the signal indicating the oxygen flow rate is input to the personal computer 21, the weight of the soot in the PM3 trapped by the filter 4 is obtained based on the oxygen flow rate and the CO ₂ concentration.

In this embodiment, since the exhaust gas G from the engine 23 is diluted when collecting the PM3 by the filter 4, the weight of the soot, SOF and sulfate is taken into consideration in consideration of this dilution rate. By performing calculations based on the soot and SO in the exhaust gas G,
The weights of F and sulfate can be obtained.

As described above, the PM in the exhaust gas G is
SOF, sulphate and soot can be individually weighted to obtain their weight,
The PM in the exhaust gas G also includes the PM 39 originally attached to the inner wall 25a of the diluting conduit 25.

Therefore, before carrying out the quantitative analysis (main measurement) of the exhaust gas G, as shown in FIG. 3 (A), the exhaust gas G is not passed through the exhaust pipe 24 and the diluting pipe line 25. PM39 is collected using the filter 4 of
The filter 4 that has collected M39 is subjected to analysis in the same procedure as in the main measurement.

That is, at the time of collecting the PM 39, a predetermined amount of air A is flown through the dilution pipe line 25, and the temperature of the dilution pipe line 25 is set to the same temperature as when the exhaust gas G is flowed. Perform heating and heat retention as appropriate to equalize the sampling conditions. The exhaust pipe 24 may be separated from the diluting pipe line 25.

Then, the filter 4 which has collected PM39 as described above is analyzed by the same procedure (conditions) as the procedure in the above-mentioned exhaust gas analysis using the gas analyzer 1 shown in FIG. The sulfate and soot are individually analyzed quantitatively (background measurement).
The numerical values obtained by this quantitative analysis are so-called background values of SOF, sulfate and soot.

Therefore, by subtracting the background values of the SOF, the sulfate and the soot individually from the weight measurement values of the SOF, the sulfate and the soot obtained by the quantitative analysis of the exhaust gas G, the PM38 contained in the exhaust gas G can be obtained. The true weight values of SOF, sulphate and soot can be obtained. It goes without saying that the true weight value of PM38 contained in the exhaust gas G can be obtained.

As described above, in the analysis method of the present invention, the dilution pipe 25 and the gas sampling flow path 29 are provided.
Before the main measurement in which the exhaust gas G is caused to flow, PM is collected in the filter 4 provided in the gas sampling flow path 29, the filter 4 is housed in the heating furnace 2 and analyzed by the above-described predetermined procedure. Without letting the exhaust gas G flow into the dilution pipe line 25 and the gas sampling flow path 29, PM is collected in the filter 4 provided in the gas sampling flow path 29, and the filter 4 is housed in the heating furnace 2 and described above. Since the background value is corrected by performing the background measurement for performing the analysis in the predetermined procedure described above, the SO in the PM 38 contained in the exhaust gas G of the engine 23 is reduced.
F, sulphate and soot can be individually separated and measured easily and accurately.

In the above-described embodiment, the gas flow passage 13 provided on the downstream side of the heating furnace 2 is replaced with the gas flow passages 14 and 15.
In the heating furnace 2, since the oxidation treatment section 16A and the CO ₂ analyzer 17A are provided in one gas flow path 14 and the reduction treatment section 16B and the SO ₂ analysis meter 17B are provided in the other gas flow path 15, The generated gas is halved, and the output signal obtained during gas analysis must be small. A configuration that solves this point will be described as a second embodiment with reference to FIG.

In FIG. 5, reference numeral 40 denotes a flow meter provided in the gas flow path 13 on the downstream side of the heating furnace 2, which is similar to the flow meters 18 and 20 in the first embodiment. Then, in the oxidation / reduction processing unit 16 provided on the downstream side of the flow meter 40, an oxidation / reduction catalyst containing platinum (Pt) as a main component is provided, and an oxygen supply passage 19 is connected. The gas analysis unit 17 provided on the downstream side of the oxidation / reduction processing unit 16 includes a CO ₂ analyzer 17A and an SO ₂ analyzer.
_{2 The} analyzer 17B is arranged in series.

The PM analysis method using the gas analyzer shown in FIG. 5 will be described. First, the exhaust gas G from the engine 23 is sampled at a constant flow rate using the gas sampling device 22 shown in FIG. , This exhaust gas G
The PM 38 therein is collected by the filter 4.

The filter 4 which has collected the PM 38 is placed in the heating furnace 2 whose inside is heated to 1000 ° C. in advance. Then, first, the solenoid valve 12 of the gas supply unit 6 is operated to connect the nitrogen gas supply passage 9 to the heating furnace 2, and nitrogen gas is supplied into the heating furnace 2 via the flow rate control device 7. The flow rate of the nitrogen gas at this time is determined by the flow rate control device 7
The measurement result is sent to the personal computer 21 as a flow rate signal.

In the heating furnace 2, by heating the filter 4 at 1000 ° C. in a nitrogen gas atmosphere, the SOF and the sulfate in the PM collected in the filter 4 are gasified, and these are generated. It flows out into the gas flow path 13 together with the gas and the nitrogen gas.

The gas (containing the gasified SOF and sulfate) flowing out to the gas flow path 13 flows into the oxidation / reduction processing unit 16 via the flow meter 40. Since oxygen is supplied to the oxidation / reduction processing unit 16, SOF of gasified SOF and sulfate is oxidized by the oxidation / reduction catalyst and oxygen to become CO ₂ and H ₂ O, while The sulfate is reduced to SO ₂ by the oxidation / reduction catalyst. These CO
₂ , H ₂ O and SO ₂ are in that state,
Sent to 7.

The concentration of CO _{2 in} the gas flowing into the gas analyzer 17 is first measured by the CO ₂ analyzer 17A, and then S ₂ is measured by the SO ₂ analyzer 17B.
The O ₂ concentration is measured, and the CO ₂ concentration and SO ₂ concentration signals are output from the gas analysis unit 17, which is the personal computer 21.
Entered in. Since a signal representing the flow rate of nitrogen gas is input to the personal computer 21, this nitrogen gas flow rate and CO
_{Based on the 2} concentration and the SO ₂ concentration, the weights of SOF and sulfate in the PM collected in the filter 4 are obtained, respectively.

Next, the solenoid valve 12 of the gas supply unit 6 is switched to connect the oxygen supply passage 10 to the heating furnace 2, and oxygen is supplied into the heating furnace 2 via the flow rate control device 8. The flow rate of oxygen at this time is measured by the flow control device 8, and the result is sent to the personal computer 21 as a flow signal.

In the heating furnace 2, under an oxygen atmosphere.
By heating the filter 4 at 1000 ° C.
The soot remaining in the filter 4 burns (oxidizes)
CO ₂And CO (which is almost trace amount) are generated,
These flow out into the gas flow path 13 together with oxygen.

The gas (including CO ₂ and CO generated by the combustion) flowing out to the gas flow path 13 is
It flows into the oxidation / reduction processing unit 16 via the flow meter 40. Since oxygen is supplied to the oxidation / reduction processing unit 16, CO contained in the gas is oxidized to generate CO ₂
And is sent to the CO ₂ analyzer 17A of the gas analysis unit 17 together with the CO _{2 in the} gas to measure the CO ₂ concentration,
This density signal is input to the personal computer 21. And C
The gas leaving the O ₂ analyzer 17A is sent to the SO ₂ analyzer 17B, but is discarded without measuring the concentration.

Since a signal indicating the flow rate of oxygen is input to the personal computer 21, this oxygen gas flow rate and C
Based on the O ₂ concentration, the weight of soot in the PM collected by the filter 4 can be obtained.

Also in the second embodiment, similarly to the first embodiment, the background measurement is performed prior to the main measurement, and the measurement result obtained by the background measurement is used. The measurement result in the main measurement is corrected. When collecting PM by the filter 4, exhaust gas G from the engine 23
Therefore, by performing the calculation based on the weights of the SOF, the sulfate and the soot in consideration of the dilution rate, as in the first embodiment described above,
The weights of SOF, sulfate and soot in the exhaust gas G can be obtained.

As described above, according to the second embodiment as well, the SOF, the sulfate and the soot in the PM 38 contained in the exhaust gas G of the engine 23 can be individually separated and measured easily and accurately.

Then, in the above-described second embodiment, the gas generated in the heating furnace 2 is not divided into two in the middle,
Further, in the gas analysis unit 17, the Cs arranged in series are arranged.
Since the O ₂ analyzer 17A and the SO ₂ analyzer 17B are sequentially passed, a large concentration signal of CO ₂ or SO ₂ can be obtained. In addition, there is an advantage that the entire configuration of the device is simple.

In the above embodiments, the engine 2 is used.
Although the exhaust gas G from the exhaust gas No. 3 is all diluted and then a part of the diluted exhaust gas is sampled to obtain the sample gas S, the present invention collects a part of the exhaust gas G from the engine 23 and then It can also be applied to a gas sampling apparatus of the partial sampling total amount dilution method in which all of the collected exhaust gas is diluted and all of the diluted exhaust gas is used as the sample gas S.

FIG. 6 schematically shows an example of the construction of the gas sampling apparatus of the partial sampling and total dilution type.
Reference numeral 41 is a sample probe that is inserted and connected to the exhaust pipe 24, and collects a part of the exhaust gas G flowing through the exhaust pipe 24. 42 is a diluting pipe, which is the sample probe 4
The downstream side of 1 is inserted and connected, and the upstream side thereof is connected to a dilution air introducing pipe 44 for introducing the dilution air 43. The downstream side of the diluting pipe 42 is connected to the gas sampling passage 29 so that all the exhaust gas diluted in the diluting pipe 42 flows into the gas sampling passage 29.

The present invention is not limited to the above-described embodiments, but can be modified in various ways. For example, as the heating furnace 2, a high frequency heating furnace or an infrared image furnace may be used. Then, as the inert gas supplied to the heating furnace 2, besides nitrogen gas, an appropriate gas such as argon gas may be used.

When the gasified SOF produced when the filter 4 is heated at a predetermined temperature in a nitrogen gas atmosphere is oxidized in the oxidation treatment section 16A or the oxidation / reduction treatment section 16, H ₂ O is emitted together with CO _2. However, this H ₂ O may become an interference component in the measurement of CO ₂ and SO ₂ . Therefore, the gas analyzer 15 may be removed before it is supplied to the gas analyzer 15, or the gas analyzer 17 may be removed.
CO ₂ analyzer 17A and SO ₂ analyzer 17B installed in
Alternatively, a gas analyzer having a configuration capable of compensating for the influence of interference components may be used.

Further, as the gas analyzer provided in the gas analysis section 17, a gas analyzer using a Fourier transform infrared spectrophotometer (FTIR gas analyzer) may be provided.
This FTIR gas analyzer is capable of simultaneously measuring the concentrations of CO ₂ and SO ₂ by itself,
Since NO _x, etc. can also be measured, SO contained in PM
Not only F, sulfate and soot but also the concentrations of other components can be measured all at once. Further, a mass spectrometer (mass spectrometer) may be used as the gas analyzer provided in the gas analyzer 17. Even in this mass spectrometer, CO ₂ , SO ₂ , N
It is possible to simultaneously measure O _{x and the} like. Therefore, when these FTIR gas analyzers or mass spectrometers are provided in the gas analyzer 17, the configuration of the entire device is simplified.

[0060]

As described above, according to the present invention, a very small amount of PM in engine exhaust gas can be measured with high accuracy, and SOF, sulfate, and soot in PM can be easily and accurately measured. You can In particular, S that occupies most of PM that cannot be measured by the conventional filter weight method or the method disclosed in the above-mentioned publication.
OF, sulphate, and soot can be individually separated to measure their concentration or weight, and low-concentration PM can also be accurately measured. And this invention can greatly contribute to the exhaust gas measurement of a low emission vehicle and the development of a low emission vehicle in particular.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of an apparatus for analyzing particulate matter in engine exhaust gas according to the present invention.

FIG. 2 is a diagram schematically showing an example of a gas sampling device for collecting PM on a filter.

FIG. 3 is a diagram for explaining the operation of the present invention.

FIG. 4 is a diagram for explaining the operation of the present invention.

FIG. 5 is a diagram schematically showing another example of the analyzer.

FIG. 6 is a diagram schematically showing another example of the gas sampling device.

[Explanation of symbols]

3 ... Collected PM, 4 ... Filter, 17 ... Gas analysis part, 23 ... Engine, 24 ... Exhaust pipe, 25 ... Diluting pipe, 29 ... Gas sampling passage, 42 ... Diluting pipe,
A ... Diluting air, G ... Exhaust gas.

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Claims (2)

[Claims] 1. An exhaust gas flowing through an exhaust pipe connected to an engine is diluted with dilution air in a dilution pipe line, the diluted exhaust gas is introduced into a gas sampling flow passage, and the diluted exhaust gas is provided in the gas sampling flow passage. A particulate matter contained in the diluted exhaust gas is collected by a filter, and each component of SOF, sulfate and soot in the particulate matter collected by the filter is analyzed. In the analyzer, prior to the analysis, the particulate matter is collected using a filter in a state where the exhaust gas does not flow through the exhaust pipe and the diluting pipeline, and SOF, sulfate and soot in the particulate matter are collected. By analyzing each component respectively, the background value remaining in the flow path of the exhaust pipe etc. is obtained, and based on this background value An apparatus for analyzing particulate matter in engine exhaust gas, which corrects the analytical values of SOF, sulfate, and soot components when exhaust gas is passed through the exhaust pipe. 2. An exhaust gas flowing through an exhaust pipe connected to an engine is diluted with dilution air in a dilution pipe, the diluted exhaust gas is introduced into a gas sampling passage, and the diluted exhaust gas is provided in the gas sampling passage. A particulate matter contained in the diluted exhaust gas is collected by a filter, and each component of SOF, sulfate and soot in the particulate matter collected by the filter is analyzed. In the analysis method, prior to the analysis, particulate matter is collected using a filter in a state where exhaust gas does not flow through the exhaust pipe and the dilution pipe line, and SOF, sulfate and soot in the particulate matter are collected. By analyzing each component respectively, the background value remaining in the flow path of the exhaust pipe etc. is obtained, and based on this background value A method for analyzing particulate matter in engine exhaust gas, which comprises correcting the analytical values of SOF, sulfate, and soot components when exhaust gas is passed through the exhaust pipe.