Analytical methods

Abstract

To accurately specify a generation source of exhaust particles.SOLUTION: An analysis method includes the steps of: dividing a resin filter which is provided in a flow path for circulating exhaust gas discharged from an engine and in which one or more fluorines are bonded to one carbon of a polyethylene skeleton; performing organic element analysis of one of the divided resin filters; performing metal element analysis of the other of the divided resin filters; and deriving a component configuration ratio of exhaust particles included in the exhaust gas based on results of the organic element analysis and the metal element analysis.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an analytical method. [Background technology]

[0002] Exhaust gas emitted from engines contains exhaust particles known as PM (particulate matter). Hereinafter, exhaust particles contained in exhaust gas will be referred to simply as PM. From the perspective of environmental measures, there is a desire to reduce the amount and number of exhaust particles released into the atmosphere.

[0003] In order to reduce the amount and number of exhaust particles released into the atmosphere, it is important to identify the causative substances that are the source of exhaust particles. Patent Document 1 discloses an organic soluble component amount estimation system that estimates the amount of organic soluble components contained in exhaust particles in exhaust gas emitted from a diesel engine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-20889 Summary of the Invention [Problem to be solved by the invention]

[0005] However, exhaust particles in exhaust gas emitted from engines contain both organic and inorganic substances. The organic soluble component amount estimation system described in Patent Document 1 was unable to derive the elements and component ratios of the organic and inorganic substances contained in the exhaust particles, and therefore was unable to accurately identify the source of the exhaust particles.

[0006] Therefore, an object of the present invention is to accurately identify the source of exhaust particles. [Means for solving the problem]

[0007] In order to solve the above problem, an analysis method according to one embodiment of the present invention includes: a step of dividing a resin filter provided in a flow path for circulating exhaust gas discharged from an engine, the resin filter having one or more fluorines bonded to one carbon of a polyethylene skeleton; A step of subjecting one of the divided resin filters to organic elemental analysis; A step of subjecting the other of the divided resin filters to metal element analysis; Deriving a component ratio of exhaust particles contained in the exhaust gas based on the results of the organic element analysis and the metal element analysis; A step of estimating a generation source of the exhaust particles based on a characteristic element among the component ratios of the generation source of the exhaust particles and the component composition ratio of the exhaust particles; Includes. [Effects of the Invention]

[0008] According to the present invention, the source of exhaust particles can be identified with high accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an exhaust particle analysis system according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic block diagram of the analysis device according to the embodiment. [Figure 3] FIG. 3 is a first flow diagram of the exhaust particle analysis method according to the embodiment. [Figure 4] FIG. 4 is a second flow diagram of the exhaust particle analysis method according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0011] [1. Overall configuration of exhaust particle analysis system] First, the overall configuration of an exhaust particle analysis system 100 according to one embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic diagram of the exhaust particle analysis system 100 according to one embodiment of the present invention.

[0012] As shown in FIG. 1, the exhaust particle analysis system 100 includes a vehicle 200 , a PM measurement device 300 , an organic element analyzer 400 , a metal element analyzer 500 , and an analysis device 600 .

[0013] The vehicle 200 includes an engine 210, an exhaust pipe 220, and a muffler 230. The vehicle 200 is, for example, a gasoline vehicle, a diesel vehicle, a hybrid vehicle, or a hydrogen engine vehicle.

[0014] Engine 210 is, for example, a gasoline engine, a diesel engine, or a hydrogen engine. Engine 210 drives vehicle 200 using kinetic energy obtained by burning fuel. An exhaust pipe 220 is connected to an exhaust port of engine 210 via an exhaust manifold. Exhaust gas discharged from the exhaust port of engine 210 is guided to exhaust pipe 220.

[0015] The exhaust pipe 220 forms a flow path for circulating exhaust gas emitted from the engine 210. The exhaust pipe 220 guides the exhaust gas to the outside via a muffler 230. A catalyst (not shown) is provided in the exhaust pipe 220 between the exhaust manifold and the muffler 230.

[0016] The PM measurement device 300 includes an inlet pipe 310 , a mixing pipe 320 , a heat exchanger 330 , a venturi 340 , a suction blower 350 , a branch pipe 360 ​​, and a filter 370 .

[0017] One end of the inlet pipe 310 is connected to the muffler 230 of the vehicle 200, and the other end is connected to the mixing pipe 320. The inlet pipe 310 forms a flow path through which the exhaust gas discharged from the muffler 230 flows. The inlet pipe 310 guides the exhaust gas discharged from the muffler 230 to the mixing pipe 320.

[0018] The mixing pipe 320 is provided with an air supply device 322. The air supply device 322 supplies air into the mixing pipe 320. In the mixing pipe 320, the air supplied by the air supply device 322 is mixed with the exhaust gas introduced by the introduction pipe 310. The mixing pipe 320 forms a flow path through which the mixture of air and exhaust gas flows. In the mixing pipe 320, the exhaust gas is uniformly mixed with the air and diluted.

[0019] The heat exchanger 330 is formed with a heat medium flow path (not shown) through which a heat medium flows. The heat medium is, for example, water or oil. The mixture of air and exhaust gas mixed in the mixing pipe 320 is also introduced into the heat exchanger 330. The heat exchanger 330 exchanges heat between the heat medium in the heat medium flow path and the mixture of air and exhaust gas. The heat exchanger 330 adjusts the temperature of the mixture.

[0020] The venturi 340 adjusts the pressure of the mixture by throttling the flow of the mixture, thereby increasing the flow velocity of the mixture and reducing the pressure of the mixture.

[0021] The suction blower 350 draws in the mixture through the venturi 340. The suction blower 350 adjusts the total flow rate of the mixture based on the temperature of the mixture adjusted by the heat exchanger 330 and the pressure of the mixture adjusted by the venturi 340.

[0022] One end of the branch pipe 360 ​​is connected to the mixing pipe 320, and the other end is connected to a pump. The branch pipe 360 ​​forms a flow path through which a mixture of air and exhaust gas flows. The pump draws a portion of the mixture in the mixing pipe 320 into the branch pipe 360. The filter 370 is provided in the branch pipe 360 ​​and collects exhaust particles (PM components) contained in the mixture.

[0023] In this embodiment, the filter 370 is provided in the branch pipe 360 ​​of the PM measurement device 300. However, the filter 370 only needs to be able to capture PM components contained in the exhaust gas emitted from the engine 210, and it only needs to be provided in a flow path through which the exhaust gas flows. Therefore, the filter 370 may be provided in, for example, the exhaust manifold, the exhaust pipe 220, the inlet pipe 310, the mixing pipe 320, or the like that forms a flow path through which the exhaust gas flows.

[0024] In this way, filter 370 captures exhaust particles in the exhaust gas emitted from engine 210. Filter 370 is a fluororesin-based filter. More specifically, filter 370 is a resin filter in which hydrogen bonded to carbon is substituted with fluorine. In other words, filter 370 is a resin filter in which one or more fluorines are bonded to each carbon in a polyethylene skeleton.

[0025] In this embodiment, a polytetrafluoroethylene filter (hereinafter referred to as a PTFE filter) is used as an example of a resin filter in which one or more fluorine atoms are bonded to one carbon atom in a polyethylene skeleton. PTFE filters have a lower metal content than glass filters. PTFE filters also have strong resistance to organic solvents. Furthermore, they are excellent in water repellency and particle collection.

[0026] After capturing the exhaust particles, the filter 370 is removed from the branch pipe 360 ​​and divided into two parts. In the following description, one of the two divided parts of the filter 370 is referred to as a first divided filter 370A, and the other of the two divided parts of the filter 370 is referred to as a second divided filter 370B.

[0027] The organic elemental analyzer 400 performs organic elemental analysis on the first divided filter 370A. For example, the organic elemental analysis is a CHNOS analysis, which can analyze carbon (C), hydrogen (H), nitrogen (N), oxygen (O), and sulfur (S).

[0028] The metal element analyzer 500 performs metal element analysis on the second segmented filter 370B. For example, the metal element analysis is performed by inductively coupled plasma atomic emission spectrometry (hereinafter referred to as ICP-AES analysis) and inductively coupled plasma mass spectrometry (hereinafter referred to as ICP-MS analysis).

[0029] The analysis device 600 analyzes the components of the exhaust particles based on the analysis results of the organic element analyzer 400 and the metal element analyzer 500 .

[0030] [2. Configuration of the analysis device] Next, the configuration of an analysis device 600 according to an embodiment of the present invention will be described with reference to Fig. 2. Fig. 2 is a schematic block diagram of analysis device 600 according to an embodiment of the present invention.

[0031] Analysis device 600 has one or more processors 610 and one or more memories 620 connected to processor 610. Processor 610 includes, for example, a CPU (Central Processing Unit). Memory 620 includes, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory). ROM is a storage element that stores programs used by the CPU, calculation parameters, etc. RAM is a storage element that temporarily stores data such as variables and parameters used in processing executed by the CPU.

[0032] The analysis device 600 communicates with the organic elemental analyzer 400 and the metal elemental analyzer 500 and obtains analysis results from the organic elemental analyzer 400 and the metal elemental analyzer 500 .

[0033] 2, the processor 610 has functional units that function as an acquisition unit 611, a derivation unit 612, an analysis unit 613, an identification unit 614, and an estimation unit 615. Various processes, including the processes described below, performed by the acquisition unit 611, the derivation unit 612, the analysis unit 613, the identification unit 614, and the estimation unit 615 can be executed by the processor 610. In detail, the various processes are executed by the processor 610 executing a program stored in the memory 620.

[0034] The acquisition unit 611 acquires various information used in the processing performed by the derivation unit 612, and outputs the information to the derivation unit 612. For example, the acquisition unit 611 acquires analysis results from the organic elemental analyzer 400 and the metal elemental analyzer 500.

[0035] The derivation unit 612 derives the component ratio of the exhaust particles contained in the exhaust gas based on the results of the organic element analysis and the metal element analysis. For example, the component ratio M A is M A = a / M1, where a is the quantitative value of specific organic component a in first divided filter 370A, and M1 is the total amount of PM components in first divided filter 370A. The component ratios are derived in the same manner for all organic components.

[0036] In addition, the component ratio M of the second divided filter 370B B is M B = b / M2, where b is the quantitative value of the specific metal component b in the second divided filter 370B, and M2 is the total amount of PM components in the second divided filter 370B. The component ratios are similarly derived for all metal components. The analysis device 600 calculates the component ratio M from the results of the organic element analysis and the metal element analysis. A , M B and the derived component ratio M A , M B Based on this, the composition ratio of all components in exhaust particles is derived.

[0037] The analysis unit 613 analyzes the component ratio of the causative substances that may be the source of exhaust particles. For example, the analysis unit 613 uses an analyzer (not shown) to analyze the component ratio (composition ratio) of engine oil that may be the source of exhaust particles. Here, engine oil will be described as an example of a source of exhaust particles, but there are multiple sources of exhaust particles other than engine oil. For example, sources of exhaust particles include gasoline burned in the engine 210, metal burrs formed inside the exhaust pipe 220, processing oil and cutting oil used when processing the exhaust pipe 220, sound-absorbing materials, dust, and substances derived from the environment.

[0038] The identifying unit 614 identifies a characteristic element from among the components of the generation source. Here, a characteristic element from among the components of the generation source is a component or element that does not overlap with the components of other generation sources (causing substances) and has a large component ratio. For example, the identifying unit 614 identifies molybdenum (Mo) as a characteristic element from among the component ratios of the engine oil analyzed by the analyzing unit 613. Here, it is preferable that the characteristic element from among the component ratios of the engine oil is an element that does not overlap with the characteristic elements from among the component ratios of other generation sources.

[0039] The estimation unit 615 estimates the source of the exhaust particles based on the elements identified by the identification unit 614 and the total component ratio of the exhaust particles derived by the derivation unit 612. For example, the abundance ratio of molybdenum to other components among the components of the engine oil is determined in advance. Next, the other engine oil components are derived based on the molybdenum content in the exhaust particles. If the amount of the derived engine oil components is less than the amount of the components in the exhaust particles, it is estimated that the engine oil is the source of the exhaust particles.

[0040] The functions of analysis device 600 according to this embodiment may be divided among multiple analysis devices, or multiple functions may be realized by a single analysis device. When the functions of analysis device 600 are divided among multiple analysis devices, the multiple analysis devices may be connected to each other via a communication bus.

[0041] [3. Exhaust particle analysis method] Next, an exhaust particle analysis method according to this embodiment will be described with reference to Figures 3 and 4. Figure 3 is a first flow chart of the exhaust particle analysis method according to this embodiment. Figure 4 is a second flow chart of the exhaust particle analysis method according to this embodiment.

[0042] The exhaust particle analysis method includes a flow for analyzing components of factor substances that may be sources of exhaust particles, and a flow for analyzing components of exhaust particles captured by filter 370. Below, the flow for analyzing components of factor substances that may be sources of exhaust particles will be explained using Fig. 3, and the flow for analyzing components of exhaust particles captured by filter 370 will be explained using Fig. 4.

[0043] (Causing substance analysis flow) 3, analysis device 600 analyzes the component ratio of the factorial substances that can be the source of exhaust particles (step S300). The factorial substances that can be the source of exhaust particles include engine oil, gasoline, metal burrs in exhaust pipe 220, processing oil, cutting oil, sound absorbing material, etc. Next, analysis device 600 identifies characteristic elements from the component ratio of the analyzed source (step S310).

[0044] Specifically, the analysis device 600 identifies a characteristic element for each of the causative substances that may be the source of generation. For example, the analysis device 600 identifies molybdenum (Mo) as a characteristic element of engine oil, and identifies iron (Fe) as a characteristic element of metal burrs inside the exhaust pipe 220.

[0045] At this time, the analysis device 600 determines the ratio of the characteristic element of the factor substance that can be the generation source to other elements. For example, in the case of engine oil, the ratio of the characteristic element molybdenum (Mo) to the other element calcium (Ca) is determined. One example is Mo:Ca=1:2. The ratio of the characteristic element molybdenum to the other element zinc (Zn) is also determined. One example is Mo:Zn=1:1. The analysis device 600 stores this information in a database.

[0046] (Exhaust particle analysis flow) 4, a dividing device (not shown) divides the filter 370 that has collected exhaust particles into a first divided filter 370A and a second divided filter 370B (step S320). Then, the organic element analyzer 400 performs organic element analysis on the first divided filter 370A (step S330). Furthermore, the metal element analyzer 500 performs metal element analysis on the second divided filter 370B (step S340).

[0047] Based on the results of the organic element analysis and the metal element analysis, the analysis device 600 derives the total component ratio of the exhaust particles contained in the exhaust gas (step S350). As an example, the elements (components) contained in the exhaust particles are 10 μg of molybdenum and 50 μg of calcium. Furthermore, the analysis device 600 estimates the source of the exhaust particles based on the characteristic elements identified in S310 and the component ratio of the exhaust particles derived in S350 (step S360).

[0048] Specifically, when the exhaust particles contain "molybdenum," the analysis device 600 determines whether "engine oil" is included as a generation source. For example, the analysis device 600 refers to a database and estimates, based on the ratio of characteristic elements of the causative substances that may be the generation source to other elements, that if the exhaust particles contain 10 μg of molybdenum, they also contain 20 μg of calcium.

[0049] Next, the analysis device 600 performs a subtraction process to remove engine oil components from the elements contained in the exhaust particles. If the estimated amount of engine oil components is less than the amount of components in the exhaust particles, it is estimated that engine oil is included as a source of the exhaust particles. As an example, if the elements contained in the exhaust particles are 10 μg of molybdenum and 50 μg of calcium, the analysis device 600 performs the subtraction process as follows: molybdenum: 10 μg - 10 μg = 0, calcium: 50 μg - 20 μg = 30 μg.

[0050] Then, based on the subtracted information, the analysis device 600 estimates the factorial substances that could be other generation sources. For example, if the exhaust particles contain "30 μg of calcium," the analysis device 600 determines whether metal burrs, processing oil, cutting oil, etc. in the exhaust pipe 220 are included as sources of "calcium," as described above. Finally, the analysis device 600 derives the influence of the factorial substances that could be the generation sources.

[0051] [4. Summary] As described above, according to this embodiment, the filter that collects exhaust particles is divided into two, one of the divided filters is subjected to organic element analysis, and the other filter is subjected to metal element analysis. Then, based on the results of the organic element analysis and the metal element analysis, the component ratio of the exhaust particles contained in the exhaust gas is derived.

[0052] Here, by performing organic element analysis on the filter, it is possible to analyze some components of exhaust particles such as soot (SOOT) and soluble organic fraction (SOF).In addition, by performing metal element analysis on the filter, it is possible to analyze some components of exhaust particles such as aluminum (Al), calcium (Ca), iron (Fe), silicon (Si), and zinc (Zn).

[0053] However, exhaust particles in the exhaust gas emitted from the engine 210 contain both organic and inorganic substances. Therefore, if either organic element analysis or metal element analysis is performed on a single filter, only a portion of the exhaust particle components can be analyzed from the single filter, and it is not possible to analyze all of the exhaust particle components. In other words, organic element analysis or metal element analysis can only analyze either organic or inorganic substances using a single filter. On the other hand, according to the above embodiment, it is possible to analyze exhaust particle components containing both organic and inorganic substances using the same filter. As a result, the source of exhaust particles can be identified with high accuracy.

[0054] Specifically, in this embodiment, the component ratios of the contributing substances that may be the source of exhaust particles are analyzed in advance, and characteristic elements in the component ratios are identified. Therefore, by comparing the component ratios of the contributing substances with the component ratios of the exhaust particles collected by the filter based on the analyzed elements, the source of exhaust particles can be accurately identified. However, the analysis of the component ratios of the contributing substances that may be the source of exhaust particles may be performed after the analysis of the exhaust particles collected by the filter. Furthermore, the analysis of the component ratios of the contributing substances that may be the source of exhaust particles and the identification of characteristic elements in the component ratios may be performed outside the exhaust particle analysis system 100 and stored in an external database. In this case, the analysis device 600 may acquire data on the component ratios of the contributing substances and data on characteristic elements in the component ratios from a database external to the exhaust particle analysis system 100.

[0055] Furthermore, the filter 370 of this embodiment is a PTFE filter. Because the components of exhaust particles are present in extremely small amounts, chemical analysis would be difficult if the components of the filter itself interfered. In contrast, PTFE filters have a very low metal content and are highly resistant to organic solvents. This minimizes adverse effects on organic elemental analysis and metal elemental analysis.

[0056] In this embodiment, metal elements in exhaust particles are detected by ICP-AES analysis and ICP-MS analysis. ICP-AES analysis can detect many types of metal elements. ICP-MS analysis can also improve sensitivity, although it limits the target elements compared to ICP-AES analysis. In this embodiment, most elements are analyzed with high sensitivity by ICP-MS analysis, and elements that could not be detected by ICP-MS analysis are detected by ICP-AES analysis.

[0057] In this embodiment, organic elements in exhaust particles are detected by CHNOS analysis. CHNOS analysis can detect the total amount of organic components in exhaust particles. Therefore, the proportion of organic components in the exhaust particles can be determined.

[0058] While the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention.

[0059] In the above embodiment, an example has been described in which both ICP-AES analysis and ICP-MS analysis are performed in the metal element analyzer 500. However, this is not limiting, and the metal element analyzer 500 may perform only ICP-MS analysis without performing ICP-AES analysis. Furthermore, the metal element analyzer 500 may perform only ICP-AES analysis without performing ICP-MS analysis. In this way, the metal element analyzer 500 may perform at least one of ICP-AES analysis or ICP-MS analysis.

[0060] In the above embodiment, an example has been described in which CHNOS analysis is performed in the organic elemental analyzer 400. However, the present invention is not limited to this, and the organic elemental analyzer 400 may also perform gas chromatography mass spectrometry (GC-MS analysis). [Explanation of symbols]

[0061] 100 Exhaust Particle Analysis System 200 vehicles 210 engine 220 Exhaust pipe 300 PM measuring device 370 filters 370A 1st division filter 370B Second division filter 400 Organic Elemental Analyzer 500 Metal Elemental Analyzer 600 Analysis equipment 610 processor 611 Acquisition Department 612 Derivation part 613 Analysis Department 614 Specific part 615 Estimation Department 620 memory

Claims

1. a step of dividing a resin filter provided in a flow path for circulating exhaust gas discharged from an engine, the resin filter having one or more fluorines bonded to one carbon of a polyethylene skeleton; A step of subjecting one of the divided resin filters to organic elemental analysis; A step of subjecting the other of the divided resin filters to metal element analysis; Deriving a component ratio of exhaust particles contained in the exhaust gas based on the results of the organic element analysis and the metal element analysis; A step of estimating a generation source of the exhaust particles based on a characteristic element among the component ratios of the generation source of the exhaust particles and the component composition ratio of the exhaust particles; Analytical methods including:

2. The resin filter is a PTFE filter. The analytical method according to claim 1 .

3. The metal element analysis is at least one of ICP-AES analysis or ICP-MS analysis, The analytical method according to claim 1 or 2.

4. The organic elemental analysis is a CHNOS analysis. The analytical method according to any one of claims 1 to 3.

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