JP2017215275A - Method and system for measuring amount of unburned fuel in exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a system for measuring the amount of the unburned fuel in an exhaust gas, the method and the system attaining a real-time measurement of the amount of the unburned fuel in an exhaust gas discharged from an internal-combustion engine, for example.SOLUTION: The amount of the unburned fuel in an exhaust gas is calculated from the result of mass analysis conducted at a measurement by removing the non-volatile component from an exhaust gas to be measured and introducing the volatile component alone of the exhaust gas to a mass analyzer without causing the volatile component to pass through a gas chromatography and from the result of advance analysis of analyzing a sample of a fuel which generates the exhaust gas as the measurement target in advance.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for measuring the amount of unburned fuel in exhaust gas and a measurement system for the amount of unburned fuel in exhaust gas that can be used for analysis in the exhaust gas of an internal combustion engine.

  In an internal combustion engine such as a diesel engine, unburned fuel is supplied and burned to increase the temperature of exhaust gas for improving or regenerating the exhaust gas purification device, and the amount of unburned fuel supplied is increased. It is becoming important to measure the amount of unburned fuel in the exhaust gas for the optimization of the exhaust gas and the performance evaluation of the exhaust gas purification device.

  Conventionally, the amount of unburned fuel in the exhaust gas is measured by passing a certain amount of exhaust gas through a filter and using gas chromatography (GC) and mass spectrometry (MS) for the unburned fuel collected by the filter. It is analyzed by GC / MS analysis to measure polycyclic aromatic hydrocarbons (see, for example, Patent Document 1).

  However, this measurement method uses a chromatogram consisting of the elution time (retention time) required for separation of unburned fuel and the detected amount at that time, and the component of the component that can quantify the area of the chromatogram of the measured specific ion. The amount of unburned fuel is calculated by approximation using the area, but there is a problem that real time measurement cannot be performed because the unburned fuel collected by the filter is analyzed.

JP 2009-175048 A

  The present invention has been made in view of the above, and an object of the present invention is to determine the amount of unburned fuel in exhaust gas discharged from an internal combustion engine or the like in real time using a relatively simple measurement system. The object is to provide a method for measuring the amount of fuel and a system for measuring the amount of unburned fuel in the exhaust gas.

  The method for measuring the amount of unburned fuel in the exhaust gas according to the present invention for achieving the above object is a method for measuring the amount of unburned fuel in the exhaust gas for measuring the amount of unburned fuel contained in the exhaust gas to be measured. The result of mass spectrometry analysis in advance was performed by eliminating the non-volatile components in the exhaust gas to be measured and introducing only the volatile components in the exhaust gas into the mass spectrometer without passing through the gas chromatography. It is a method characterized in that the amount of unburned fuel in the exhaust gas is calculated from the result of the preliminary analysis in which the fuel sample that generates the exhaust gas to be measured is analyzed.

  According to this method, when the amount of unburned fuel contained in the exhaust gas to be measured is analyzed using a mass spectrometer, a mass spectrometer is used without using gas chromatography, so the analytical instrument is simplified. In addition, it is possible to perform measurement during traveling in an internal combustion engine mounted on an automobile or the like.

  More specifically, in the above-described method for measuring the amount of unburned fuel in the exhaust gas, a GC / MS analysis including a gas chromatograph and a mass analyzer is performed on the fuel sample that generates the exhaust gas to be measured in the preliminary analysis. Analyzing using a meter, obtaining an intensity ratio between the ionic strength of the specific ion and the molecular ion corresponding to the fuel component in the fuel that generates the exhaust gas to be measured, and the ionic strength of the specific ion and the fuel Obtain a calibration curve that is a relationship with the mass of the component, measure the ion intensity of the molecular ion in the measurement analysis, and determine the specific ion corresponding to the molecular ion from the ion intensity of the molecular ion and the intensity ratio. And calculating the sum of the calculated ion intensities of the specific ions by multiplying the conversion factor by the conversion value obtained from the calibration curve. Calculating a mass, and the amount of unburned fuel in the exhaust gas by integrating the mass of the fuel component This was calculated.

  Alternatively, more specifically, in the above-described method for measuring the amount of unburned fuel in the exhaust gas, a sample of the fuel that generates the exhaust gas to be measured in the pre-analysis is GC / mass comprising a gas chromatography and a mass spectrometer. Analysis using an MS analyzer, the ratio of the ionic strength of the specific ion and the ionic strength of the molecular ion corresponding to the fuel component in the fuel that generates the exhaust gas to be measured, the ionic strength of the specific ion and the fuel A calibration curve, which is a relationship with the mass of the component, is obtained, and the specific ion in the total ion chromatogram showing all ions and the specific ion in the selected ion chromatogram showing only the selected ions and its ion A conversion factor is obtained by dividing the ionic strength of all specific ions consisting of the surroundings. The ionic strength of the molecular ion is measured, and the ionic strength of the specific ion corresponding to the molecular ion is calculated from the ionic strength of the molecular ion and the intensity ratio, and the calculated ionic strength of the specific ion is calculated. The mass of the fuel component is calculated by multiplying the sum by the conversion factor and the conversion value obtained from the calibration curve, and the calculated mass of the fuel component is added to obtain the amount of unburned fuel in the exhaust gas. .

  As a result, the amount of unburned fuel can be calculated from the ionic strength of molecular ions with a relatively simple algorithm, so that the amount of unburned fuel in the exhaust gas can be measured in real time.

  Further, in the above method for measuring the amount of unburned fuel in the exhaust gas, as the specific ions, the mass-to-charge ratio corresponding to the molecular weight of a linear saturated hydrocarbon having a carbon number of 15 or more and 26 or less and the mass-to-charge ratio of fragment ions Is a measurement method using linear saturated hydrocarbons contained in diesel engine fuel as specific ions when using ions of 57, 71, 85, so it can be used to measure the amount of unburned fuel in exhaust gas from diesel engines. This is a suitable method.

  Further, in the above method for measuring the amount of unburned fuel in the exhaust gas, if the exhaust gas is collided with a heated collision member or passed through a heated filter, the nonvolatile components in the exhaust gas to be measured are eliminated. The nonvolatile component in the exhaust gas can be easily eliminated with a relatively simple configuration.

  And the measurement system of the amount of unburned fuel in the exhaust gas of the present invention for achieving the above object comprises a measurement pipe, a heating collision part, and a mass spectrometer, and an exhaust gas passage through which the exhaust gas to be measured passes. The mass spectrometer is connected with the measurement pipe, the heating collision part is provided in the middle of the measurement pipe, and the particulate matter of the exhaust gas introduced into the measurement pipe inside the heating collision part A heating collision member to be collided is disposed, and the mass spectrometer is configured to include a mass analyzer and an arithmetic unit. According to this structure, it becomes a measuring system which can implement the measuring method of unburned fuel amount in said exhaust gas.

  According to the method for measuring the amount of unburned fuel in the exhaust gas and the system for measuring the amount of unburned fuel in the exhaust gas of the present invention, when analyzing the amount of unburned fuel contained in the exhaust gas to be measured using a mass spectrometer. Since the mass spectrometer is used without using gas chromatography, the analytical instrument is simplified and the amount of unburned fuel can be calculated in real time.

It is a figure which shows typically the structure of the measurement system of the amount of unburned fuel in the waste gas of embodiment which concerns on this invention. It is a figure which shows typically the structure of the mass spectrometer of FIG. It is a figure which shows the structure of the step in the measuring method of the amount of unburned fuel in the waste gas of embodiment which concerns on this invention. It is a figure which shows an example of the chromatogram obtained with a mass spectrometer. It is a figure which shows an example of the mass spectrum obtained with a mass spectrometer. It is a figure which shows the 1st example of the mass spectrum which shows the relationship of the count of the specific ion and molecular ion in a component of a fuel. It is a figure which shows the 2nd example of the mass spectrum which shows the relationship between the count of the specific ion in a component of a fuel, and molecular ion. It is a figure which shows the 3rd example of the mass spectrum which shows the relationship of the count of the specific ion and molecular ion in a component of a fuel. It is a figure which shows the calibration curve which shows the relationship between a specific ion and the amount of linear saturated hydrocarbons. It is a figure which shows an example of the chromatogram which shows the total amount (TIC) of the ion count of all the ranges to measure. It is a figure which shows an example of the chromatogram which shows the quantity (SIC) of the ion count of only the selected ion. It is a figure which shows an example of the chromatogram at the time of the analysis of the sample of a fuel. It is a figure which shows the method of the division in the elution time of a chromatogram. It is a figure which shows the relationship between the SIC peak area and TIC division area in a chromatogram. It is a figure which overlaps and shows the chromatogram of only the selected ion in the analysis of exhaust gas. It is a figure which shows the example of the mass spectrum which shows the mass fragment of the exhaust gas which shows the relationship of the count of specific ion and the count of molecular ion in the analysis of exhaust gas. It is a figure which shows typically the structure of the GC / MS analyzer used for the analysis of the sample of a fuel. It is a figure which shows the work procedure in the analysis of the sample of a fuel using a GC / MS analyzer.

  Hereinafter, a method for measuring the amount of unburned fuel in exhaust gas and a system for measuring the amount of unburned fuel in exhaust gas according to embodiments of the present invention will be described with reference to the drawings.

  First, the measurement system for the amount of unburned fuel in the exhaust gas according to the embodiment of the present invention will be described. As shown in FIG. 1, the measurement system 1 for the amount of unburned fuel in the exhaust gas includes a measurement pipe 21, a heating collision unit 22, and a mass spectrometer 30, and is an exhaust gas passage through which the exhaust gas G to be measured passes. An exhaust pipe 11 of a certain internal combustion engine (hereinafter, engine) 10 and a mass spectrometer 30 are connected by a measurement pipe 21.

  Further, a heating collision member 22 a is provided in the middle of the measurement pipe 11, and a heating collision member 22 a that collides particulate matter such as soot of the exhaust gas G introduced into the measurement pipe 21 inside the heating collision part 22. As shown in FIG. 2, the mass spectrometer 30 is configured to include a computing device 30 b including a mass analyzer (MS: mass spectrometry) 30 a and a computing unit 34. The mass analyzer 30 a includes an ionization chamber 31, a quadrupole 32, and an ion detector 33.

  As shown in FIG. 1, a probe 23 is provided in a portion inserted into the exhaust pipe 11 on the distal end side of the measurement pipe 21, and a flow rate adjusting valve 24 and a suction are provided in the middle of the measurement pipe 21. A pump 25 is provided. Further, an exhaust pipe 26 for exhausting the exhaust gas G that is no longer needed by the mass spectrometer 30 is provided. After the exhaust gas G is purified by an exhaust gas purification device (not shown) provided in the exhaust pipe 26, the atmosphere Release into.

  The heating collision unit 22 is connected to the exhaust pipe 11 by the measurement pipe 21 on the inlet side of the exhaust gas G, and connected to the mass spectrometer 30 by the measurement pipe 21 on the outlet side of the exhaust gas G. A heating collision member 22 a is disposed inside the heating collision unit 22 so as to face the outlet of the measurement pipe 21. At the time of measurement, an electric heater or the like is used at 400 ° C. to 600 ° C. (in order to prevent thermal decomposition and carbonization) so that organic substances adhering to the surface of the particulate matter colliding with the heating collision member 22a can be volatilized. It is configured so that it can be heated to the following extent.

  If this heating collision member 22a is formed in a plate shape, the structure becomes simple. Further, a gap 22 c is provided between the periphery of the heating collision member 22 a and the wall surface 22 b of the heating collision part 22. The exhaust gas G colliding with the heating collision member 22a passes through the gap 22c and flows into the measurement pipe 21 from the opening 21a provided on the side of the measurement pipe 21 connected to the back side of the heating collision member 22a. Thus, the exhaust gas G containing the volatilized component is introduced from the measurement pipe 21 into the mass analyzer 30a. On the other hand, the non-volatile particulate matter that collides with the heating collision member 22a adheres to the heating collision member 22a and is separated from the exhaust gas G.

  In addition, as the heating collision member 22a, instead of the plate material, a filter (not shown) heated to about 400 ° C. or more and 600 ° C. (to prevent thermal decomposition or carbonization) may be provided. The introduced exhaust gas G is allowed to pass through the heated filter to volatilize the organic matter adhering to the surface of the particulate matter, and capture non-volatile components such as particulate matter such as soot by the filter. And the non-volatile component are separated, and the exhaust gas G containing only the volatilized component is introduced from the measurement pipe 21 to the mass analyzer 30a.

  In the sampling of the exhaust gas G when measuring the amount of unburned fuel in the exhaust gas G, the exhaust gas G is diverted from the exhaust pipe 11 of the engine 10 and introduced into the measurement pipe 21. The exhaust gas G introduced into the measurement pipe 21 is made to collide with a heating collision plate 22a provided in the middle of the measurement pipe 21 to volatilize the organic matter adhering to the surface of the particulate matter contained in the exhaust gas G. The exhaust gas G containing the volatile component is introduced into the mass analyzer 30a.

  As shown in FIG. 2, each component in the exhaust gas G introduced into the mass analyzer 30a is ionized in an ionization chamber 31 by an electron impact method (EI ionization method). A voltage of 10 eV to 70 eV is used as the ionizing voltage. The ions It of each component ionized in the ionization chamber 31 are caused to fly by electrostatic force and pass through the quadrupole 32.

  By changing the voltage in the quadrupole 32 and changing the strength of the electric field, only specific ions Is can reach the detector 33. Thereby, the ions can be separated and selected according to the mass-to-charge ratio (m / z: m is the mass of the ion and z is the charge).

  The selected ions Is are sensitized and detected by a detector 33 with an electron multiplier or a microchannel plate, and the number of the ions Is is counted and converted into an electrical signal according to the counted number. This is sent to the calculation unit 34 of 30b. The number of counts is the ion intensity of the ions Is.

  A mass spectrum (mass spectrum) as shown in FIG. 5 can be obtained from the electrical signal converted by the detector 33. The horizontal axis represents the mass-to-charge ratio, and the vertical axis represents the detected ion intensity (count).

  In this mass spectrum, ions that have only one positive or negative charge, multivalent ions that are charged more than two, fragment ions (Fin, Fim) dissociated during the ionization process or in flight, and samples are associated with each other. Associated ions appear. Normally, a molecule contains an isotope element, and each peak appears with an inherent distribution derived from the molecule. And since a mass spectrum contains all these information, it becomes a considerably complicated spectrum.

  As shown in FIGS. 1 and 2, the method for measuring the amount of unburned fuel in the exhaust gas according to the embodiment of the present invention eliminates the non-volatile component in the exhaust gas G to be measured, and the volatile component of the G in the exhaust gas. As a result, the sample of the fuel in which the exhaust gas G to be measured is generated in advance as shown in FIG. Is a method of calculating the amount of unburned fuel in the exhaust gas G from the result of a prior analysis in which the gas is analyzed using a GC / MS analyzer 40 comprising a gas chromatography 40a and a mass analyzer 30a.

  In the method for measuring the amount of unburned fuel in the exhaust gas, as a pre-analysis, a fuel sample used in the engine 10 is analyzed with a gas chromatography (GC) 40a and mass spectrometry (MS) as shown in FIG. : Mass spectrometer) 30a is directly connected, and the sample from gas chromatography (GC) 40a is analyzed by GC / MS analyzer 40 for mass analysis.

  In this GC / MS analysis, a sample (sample) driven by a syringe (not shown) or the like is vaporized in a high-temperature vaporization chamber (not shown) and then gas chromatography (GC) using a carrier gas used as a mobile phase. ) Move from the GC injector 41 of 40a to the capillary column 42. As the carrier gas, an inert gas such as helium, nitrogen, or argon is used, and the sample is carried by the carrier gas.

  This sample is separated into each component by the principle of chromatography in a capillary column 42 in which a stationary phase for component separation is applied to the inner wall of a tube of 1 mm or less inner diameter of fused silica.

  Each component of the sample separated by this elution time (retention time: time eluted from the capillary column) and carried to the carrier gas is further sent to the mass analyzer 30a. In this mass analyzer 30a, each component contained in the sent carrier gas is ionized in a vacuum applied with a high voltage in the ionization chamber 31, and each ionized component is caused to fly in the apparatus by electrostatic force. Then, the ions are separated by the quadrupole 32 according to the mass electrification ratio by an electric / magnetic action or the like, and the ions selected by the quadrupole 32 are separated by the detector 33 by an electron multiplier or a micro. Sensitize with channel plate.

  This work flow is shown in FIG. In this work flow, in step S21 of the pre-processing step S20, the soluble part of the fuel sample to be measured is extracted with an organic solvent, and in step S22, the soluble part of the fuel sample is injected into the GC injector 41. . On the other hand, in step S23, the volatile component of the fuel sample is introduced into the GC injector 41 by thermal desorption. In step S31 of the next GC separation step S30, the mixture is separated by the capillary column 42, and in step S41 of the next detection step S40, the components eluted from the capillary column 42 are detected by the mass analyzer 30a.

  This detector 33 converts the electric signal into an electric signal. By taking the electric signal on the horizontal axis and the signal intensity obtained from the detector 33 on the vertical axis, a chromatogram as shown in FIG. 4 is obtained. It is done. In this chromatogram, substances are identified from the elution time tr indicated on the horizontal axis, and quantified from the height or area of the chromatogram called peak P (i) on the vertical axis. The chromatogram used here shows the number of detected ions.

  An example of a chromatogram obtained when analyzing this fuel sample is shown in FIG. For example, in the analysis result when JIS No. diesel oil is used as the fuel, if the horizontal axis is the elution time tr, the peak P (i) of the linear saturated hydrocarbon is regularly spaced at regular intervals with respect to the elution time tr. appear. In other words, hydrocarbons are classified into alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, etc., depending on their molecular structure, but as fuel components, there are many straight-chain saturated hydrocarbons. Since a hydrogen peak P (i) appears, this peak P (i) is used as a reference.

  Then, some (a, b) of specific ions corresponding to fuel components (for example, linear saturated hydrocarbons having 15 to 26 carbon atoms (n-alkane)) in the fuel sample are selected and set. Keep it. In this selection, it is preferable to select fragment ions and molecular ions that have a high generation ratio of mass fragment patterns obtained by electron impact method (EI ionization method) that is different for each molecule. When ions having mass-to-charge ratios of 57, 71, and 85 are used as the specific ions (fragment ions having a high generation ratio), a linear saturated hydrocarbon contained in diesel engine fuel is used as a specific ion measurement method, and Therefore, it becomes a method suitable for measuring the amount of unburned fuel in the exhaust gas of a diesel engine, and is more preferable. In the following, in order to simplify the description, two specific ions (a, b) are described, but the present invention is not limited to two.

  Furthermore, a mass spectrum of linear saturated hydrocarbons separated by gas chromatography (GC), as shown in FIGS. 6 to 8, is obtained. 6 to 8 show the relationship between the count p (j) of the three molecular ions p and the counts a (j) and b (j) of the specific ions a and b. That is, in FIGS. 6 to 8, the counts “a (n), b (n)”, “counts of specific ions a and b with respect to the counts p (n), p (m), and p (o) of the molecular ions p, respectively. a (m), b (m) "," a (o), b (o) ").

  Further, at the time of analyzing the fuel data, the counts (number of ions) ac (j) and bc (j) of the specific ions a and b and the count p (j) of the molecular ions p are detected, and these are detected. The intensity ratio, α (j) = ac (j) / pc (j), and β (j) = bc (j) / pc (j), which are ratio values, are calculated in advance. The subscript “c” next to “a”, “b”, and “p” represents the value at the time of analysis of the fuel sample.

  Thereby, the counts am (j) and bm (j) of the specific ions a and b can be estimated from the count pm (j) of the molecular ions p detected during the analysis of the exhaust gas. That is, “am (j) = α (j) × p (j)” and “bm (j) = β (j) × pm (j)”. The subscript “m” next to “a”, “b”, and “p” represents a value at the time of analysis of exhaust gas.

  Further, as shown in FIG. 9, the ionic strength (count) P (i) (= at, bt) of these specific ions (i = a, b), and these specific ions P (i) (= a, Calibration curve L (i) (= L (a) showing the relationship with the mass (straight chain saturated hydrocarbon amount) M (i) (= M (a), M (b)) of the fuel component corresponding to b) , L (b)) is prepared and prepared. Specifically, the conversion value for obtaining the mass (linear saturated hydrocarbon amount) M (i) (= M (a), M (b)) of the fuel component from the strengths at, bt of the specific ions a, b. C (i) (= C (a), C (b)) is set.

  That is, the linear saturated hydrocarbon amount M (a) corresponding to the intensity at of the specific ion a is “M (a) = C (a) × at”, and the linear saturation corresponding to the intensity bt of the specific ion b. The hydrocarbon amount M (b) can be calculated by “M (b) = C (b) × bt”. That is, “M (i) = C (i) × P (i)”.

  In addition, since the fuel contains a certain proportion of compounds having boiling points close to each straight-chain saturated hydrocarbon, a conversion coefficient k (i) for obtaining the amount of fuel including the surrounding compounds is obtained. It is preferable to keep it.

  In this connection, in the analysis using the mass analyzer 30a, the chromatograph as shown in FIG. 4 can be drawn for each selected ion, and as shown in FIG. Both TIC (Total Ion Counts) indicating the total amount of all ion counts in the range and SIC (Selected Ion Counts) indicating the amount of selected ion counts of only selected ions as shown in FIG. 11 can be expressed. .

  In this chromatogram analysis, in order to obtain the conversion coefficient k (i), as shown in FIG. 13, the chromatogram is divided on an elution time basis. This dividing point is an intermediate point ts (i) between adjacent peaks (P (i), P (i + 1)), and one section Δts (i) has two peaks (P (i−1) with respect to the elution time tr. ), P (i)) from the intermediate point ts (i-1). The intermediate point ts (i) between the next two peaks (P (i), P (i + 1)) is assumed.

  Next, as shown in FIG. 14, regarding the area from the intermediate point ts (i-1) to the intermediate point ts (i) of the target peak P (i), the total amount of all ion counts in all ranges to be measured is shown. The area of the peak portion corresponding to the peak P (i) in the SIC indicating the amount of the selected ion count of only the selected specific ion fragment is obtained as the SIC peak area Ap (i). . The SIC peak area Ap (i) is an area due to only the linear saturated hydrocarbon, and the TIC segment area At (i) is an area based on the sum of the linear saturated hydrocarbon and the surrounding compounds.

  Then, in the analysis of the fuel sample in the pre-analysis, the TIC segment area At (i) of the total amount ion chromatogram representing the total amount TIC of the ion count of all the ranges to be measured and the selection to count only the selected specific ion fragment The SIC peak area Ap (i) of the selected ion chromatogram representing the ion count SIC is calculated.

  Using these areas, the conversion factor k (i), which is the value of the ratio of the TIC segment area At (i) and the SIC peak area Ap (i), is determined for each peak P (i) of the chromatogram by “k ( i) = (TIC division area / SIC peak area) = (Act (i) / Acp (i)) ”. As a result, the TIC segment area At (i) can be estimated from the SIC segment area As (i). “Act (i) = k (i) × Acs (i)”. The area Ac when obtaining the conversion factor k (i) is obtained when the fuel sample is analyzed, and is different from the area Am when the exhaust gas is analyzed. Therefore, the area when the fuel sample is analyzed. Is Ac.

  That is, in the pre-analysis, in the mass spectrum obtained by the GC / MS analysis, ions of specific ions a and b corresponding to specific fuel components (linear saturated hydrocarbons) in the fuel that generates the exhaust gas G to be measured. Intensity ratios α (j) and β (j) between the intensity a (j) and b (j) and the ion intensity p (j) of the molecular ion p, the ion intensity P (i) of the specific ions a and b, and the fuel A calibration curve L (i) which is a relationship with the component mass M (i) is obtained. Further, preferably, the ion intensity Acs (i) of the specific ions a and b in the selected ion spectrum showing only the selected ions, and the specific ions a and b in the whole ion spectrum showing all the ions are the surroundings. A conversion coefficient k (i) obtained by dividing the ionic strength Act (i) of the specific all ions is obtained.

  Next, in the analysis performed on the exhaust gas, only mass spectrometry (MS: mass analyzer) 30a is used without using gas chromatography (GC). In this case, a mass spectrum of exhaust gas containing all the molecular ions p as shown in FIG. 16 is obtained. In this case, the specific ions a and b corresponding to the specific fuel component (linear saturated hydrocarbon) overlap, but the molecular ions p (n), p (m) and p (o) are mass charges. Since the ratio is different, they are separated. In other words, the mass spectrum is as shown in FIG.

  In the analysis of the exhaust gas, the exhaust gas G is drawn from the probe 23 attached to the exhaust pipe 11 of the engine 10 by the suction pump 25 while being adjusted to a constant flow rate by the flow rate adjusting valve 24. It leads to the measurement pipe 21 which is a sampling pipe, and further, the particulate matter of the exhaust gas G collides with the heating collision member 22a of the heating collision part 22 and adheres to the surface of the particulate matter contained in the exhaust gas G. The exhausted gas G containing the volatile components is introduced into the mass spectrometer 30 and the amount of unburned fuel in the exhaust gas G is measured.

  In measuring the amount of unburned fuel in the exhaust gas G, the count (ion intensity) pm (j) of molecular ions p (j = n, m, o) is detected from the mass spectrum of the exhaust gas as shown in FIG. To do. The ratio between the counts ac (j) and bc (j) of the specific ions a and b and the count pc (j) of the molecular ions p, which is obtained in advance analysis from the count pm (j) of the molecular ions p. Using the intensity ratios α (j) and β (j), specific ion counts am (j) and bm (j) are obtained. That is, am (j) and bm (j) are calculated by am (j) = α (j) × p (j) ”,“ bm (j) = β (j) × pm (j) ”, and the like.

  Then, the sums amt and bmt of specific ion counts am (j) and bm (j) corresponding to the respective molecular ions are obtained. amt = Σam (j), bmt = Σbm (j). FIG. 16 represents “amt = am (n) + am (m) + am (o) +...” And “bmt = bm (n) + bm (m) + bm (o) +.

  Next, with respect to P (i) which is the sum amt and bmt of the counts am (j) and bm (j) of the specific ions a and b, the calibration curve L (i) set in the prior analysis is used. Using the converted value C (i), the mass (straight chain hydrocarbon content) M (i) of the fuel component corresponding to the specific ions a and b is calculated. Specifically, “M (i) = C (i) × P (i)”, and more specifically, “M (a) = C (b) × amt”, “M (a) = C (b) × bmt ”.

  Next, from the value M (i) of only the mass (straight chain saturated hydrocarbon amount) of the fuel component corresponding to the specific peak P (i), the peripheral compound corresponding to the specific peak P (i) is also included. The mass Mf (i) of the fuel component is calculated. In this calculation, the sums amt and bmt of the counts of specific ions correspond to the SIC peak area Amp (i) of the selected ion chromatogram representing the selected ion count SIC that counts only the selected ions. From i), the conversion factor k (i) is used to calculate the TIC section area Amt (i) of the total ion chromatogram representing the total ion count TIC. Since “Amt (i) = k (i) × Amp (i)”, Mf (i) = k (i) × M (i) and peripheral compounds corresponding to the specific peak P (i) are included. The mass Mf (i) of the specific component of the obtained fuel is calculated.

  Then, the mass Mf (i) of the specific component of the fuel is integrated by the number of peaks P (i) to obtain the unburned fuel amount Mt (= ΣMf (i)) in the exhaust gas.

  That is, in the analysis at the time of measurement, the ionic strength pm (j) of the molecular ion p is measured, and the molecular ion p is calculated from the ionic strength pm (j) of the molecular ion p and the intensity ratios α (j) and β (j). And the ion intensity am (j) and bm (j) of the specific ions a and b corresponding to the sum of the calculated ion intensities am (j) and bm (j) of the specific ions a and b, amt, The fuel component mass M (i) is calculated by multiplying bmt by the converted value C (i) obtained from the calibration curve L (i), and the calculated fuel component mass M (i) is integrated. If the unburned fuel amount Mt in the exhaust gas is used, the unburned fuel amount Mt can be calculated from the ionic strength pm (j) of the molecular ion p, so that the unburned fuel amount Mt in the exhaust gas can be measured in real time.

  When the conversion coefficient k (i) is obtained, the conversion coefficient k is converted into the sums amt and bmt of the ion intensities am (j) and bm (j) of the specific ions a and b calculated in the analysis at the time of measurement. The mass M (i) of the fuel component is calculated by multiplying the conversion value C (i) obtained from (i) and the calibration curve L (i), and the calculated mass M (i) of the fuel component is integrated. Thus, the unburned fuel amount Mt in the exhaust gas is set.

  When the above analysis is displayed in steps, a step configuration as shown in FIG. 3 is obtained. That is, the measurement method S50 for the amount of unburned fuel in the exhaust gas includes the following steps. That is, the fuel sample analysis (preliminary analysis) S50A includes a first analysis step S51, an ion selection step S52, an intensity ratio calculation step S53, a calibration curve setting step S54, and a conversion coefficient calculation step S55. In the exhaust gas analysis (analysis during measurement) S50B corresponding to the process, there are a second analysis step S56, a specific ion intensity calculation step S57, a quantification step S58, and an unburned fuel amount calculation step S59.

  This first analysis step S51 is a step of analyzing a fuel sample that generates exhaust gas G to be measured using a GC / MS analyzer 40 comprising a gas chromatography 40a and a mass analyzer 30a, and an ion selection step S52. Is a step of selecting specific ions a and b from ions constituting the mass spectrum from the mass spectrum corresponding to the peak for the fuel component in the gas chromatograph 40a obtained in the first analysis step S51.

  The intensity ratio calculating step S53 is an intensity ratio α () between the ion intensities ac (j) and bc (j) of the specific ions a and b selected in the ion selecting step S52 and the ion intensity p (j) of the molecular ions p. j) and β (j) are calculated, and the calibration curve setting step S54 is a calibration curve L () indicating the relationship between the ion intensities at and bt of the specific ions a and b and the mass M (i) of the fuel component. This is a step for setting i).

  The conversion coefficient calculation step S55 includes, in the gas chromatograph obtained in the first analysis step S51, a total ion chromatogram that displays all ions and a selected ion chromatogram that displays only selected ions. The conversion coefficient k (i) is calculated from the TIC section area Act (i) that is the area of the specific ions and the SIC peak area Acp (i) that is the peak area of the specific ions a and b in the selected ion chromatogram. It is a step to do.

  On the other hand, the second analysis step S56 of the measurement time analysis is a step of analyzing the amount of unburned fuel in the exhaust gas to be measured using the mass analyzer 30a, and the specific ion intensity calculation step S57 is the second analysis step. , The ionic strength pm (j) of the molecular ion p is measured, and the ionic strength am (of the specific ions a and b is determined from the ionic strength pm (j) of the molecular ion p and the intensity ratios α (j) and β (j). j) and bm (j) are calculated.

  In the quantification step S58, the converted value C (i) obtained from the calibration curve L (i) to the sum amt, bmt of the ion intensities am (j), bm (j) of the specific ions a, b in the specific ion intensity calculation step S7. To calculate the fuel component mass M (i), or to further multiply the value obtained by multiplication by a conversion factor k (i) to calculate the fuel component mass Mf (i). In the unburned fuel amount calculating step S59, the mass M (i) or Mf (i) of the fuel component calculated in the quantifying step S58 is integrated, and this integrated value is calculated as the unburned fuel amount Mt in the exhaust gas. It is a step to do.

  According to the method for measuring the amount of unburned fuel in the exhaust gas, the ratio of specific ions to molecular ions of fuel components (for example, linear saturated hydrocarbons) in the fuel is obtained in advance, and the strength of the specific ions and the fuel A calibration curve L (i) indicating the relationship with the mass of the component is prepared, the exhaust gas G to be measured is introduced into the measurement pipe 21, introduced into the mass spectrometry (MS) of the mass spectrometer 30, and the electron Ionization of molecules by collision and detection of the ionic strength of the molecular ion with electrons loaded on the resulting molecule and detecting the relationship between the ionic strength of this molecular ion and the ionic strength of the specific ion, and the ion of the specific ion The fuel component mass is quantified based on the strength.

  Based on these, when measuring the unburned fuel in the exhaust gas, the intensity of the specific ions in the exhaust gas is multiplied by multiplying the ionic strength of the molecular ions corresponding to each fuel component by the strength ratio obtained in advance. , The mass of each fuel component is quantified, and the mass of each fuel component is integrated to calculate the amount of unburned fuel. At this time, since the fuel contains compounds with boiling points close to each fuel component at a fixed rate, the amount of unburned fuel is calculated by correcting the mass of each fuel component with a conversion factor that takes this fixed rate into account. It is preferable to do.

  Furthermore, when analyzing the exhaust gas to be measured using an MS analyzer, if the selected ion chromatogram is used instead of the total ion chromatogram, the exhaust gas can be detected in the exhaust gas in a relatively short time with high accuracy. The amount of unburned fuel contained in can be obtained.

  According to the method for measuring the amount of unburned fuel in the exhaust gas and the system for measuring the amount of unburned fuel in the exhaust gas according to the embodiment of the above configuration, the mass spectrometer is used to calculate the amount of unburned fuel contained in the exhaust gas to be measured. Therefore, since the mass spectrometer is used without using gas chromatography, the analytical instrument is simplified and the amount of unburned fuel can be calculated in real time.

  And since the quantity of the unburned fuel in the exhaust gas discharged | emitted from an internal combustion engine etc. can be measured in real time, the measurement at the time of driving | running | working in the internal combustion engine mounted in a motor vehicle etc. can be enabled.

1 Measurement system for the amount of unburned fuel in exhaust gas 10 Internal combustion engine
DESCRIPTION OF SYMBOLS 11 Exhaust pipe 21 Measurement pipe 22 Heating collision part 22a Heating collision member 30 Mass spectrometer 30a Mass analyzer 30b Arithmetic apparatus 31 Ionization chamber 32 Quadrupole 33 Ion detector 34 Arithmetic part 40 GC / MS (GC SMS) analyzer 40a Gas chromatography (GC)
41 GC injector 42 Capillary column At (i), Act (i), Amt (i) Partition area Ap (i), Acp (i), Amp (i) Peak area (peak area)
C (i) Calibration curve conversion value G Exhaust gas k (i) Conversion factor L (i) Calibration curve p (j) Molecular ion P (i), P (i + 1) Peak tr of fuel component (linear saturated hydrocarbon) Elution time (retention time)
ts (i-1), ts (i) Dividing point (midpoint of adjacent peaks)
Δts (i) Category

Claims (6)

In the method for measuring the amount of unburned fuel in the exhaust gas, which measures the amount of unburned fuel contained in the exhaust gas to be measured,
Excludes non-volatile components in the exhaust gas to be measured, introduces only the volatile components in the exhaust gas into the mass spectrometer without passing through the gas chromatography, and analyzes in advance the results of mass spectrometry analysis A method for measuring the amount of unburned fuel in exhaust gas, wherein the amount of unburned fuel in the exhaust gas is calculated from a result of a prior analysis in which a sample of fuel generating the target exhaust gas is analyzed. In the preliminary analysis, a fuel sample that generates the exhaust gas to be measured is analyzed using a GC / MS analyzer including a gas chromatography and a mass spectrometer, and the fuel component in the fuel that generates the exhaust gas to be measured is analyzed. Finding the intensity ratio between the ionic strength of the corresponding specific ion and the ionic strength of the molecular ion, and obtaining a calibration curve that is the relationship between the ionic strength of the specific ion and the mass of the fuel component,
In the measurement analysis, the ionic strength of the molecular ion is measured, and the ionic strength of the specific ion corresponding to the molecular ion is calculated from the ionic strength of the molecular ion and the strength ratio. The mass of the fuel component is calculated by multiplying the sum of the ionic strengths of the specific ions by the conversion coefficient and the conversion value obtained from the calibration curve, and the calculated mass of the fuel component is added to the exhaust gas in the exhaust gas. The method for measuring the amount of unburned fuel in exhaust gas according to claim 1, wherein the amount of unburned fuel is used. In the preliminary analysis, a fuel sample that generates the exhaust gas to be measured is analyzed using a GC / MS analyzer including a gas chromatography and a mass spectrometer, and the fuel component in the fuel that generates the exhaust gas to be measured is analyzed. Obtain a calibration ratio that is the relationship between the ionic strength of the corresponding specific ion and the ionic strength of the molecular ion, and the relationship between the ionic strength of the specific ion and the mass of the fuel component, and then select only the selected ions. With the ionic strength of the specific ion in the selected selected ion chromatogram, a conversion factor obtained by dividing the ionic strength of the specific total ion consisting of the specific ion and the surroundings in the total ion chromatogram showing all ions,
In the measurement analysis, the ion intensity of the molecular ion in the mass spectrum is measured, and the ion intensity of the specific ion corresponding to the molecular ion is calculated from the ion intensity of the molecular ion and the intensity ratio. The mass of the fuel component is calculated by multiplying the sum of the ionic strengths of the specific ions multiplied by the conversion coefficient and the conversion value obtained from the calibration curve, and the calculated mass of the fuel component is integrated. The method for measuring the amount of unburned fuel in exhaust gas according to claim 1, wherein the amount of unburned fuel in the exhaust gas is used.   4. The ion having a mass-to-charge ratio corresponding to the molecular weight of a linear saturated hydrocarbon having a carbon number of 15 or more and 26 or less and a fragment-ion mass-to-charge ratio of 57, 71, 85 is used as the specific ion. A method for measuring the amount of unburned fuel in the exhaust gas as described in 1.   The exhaust gas in the exhaust gas according to any one of claims 1 to 4, wherein the non-volatile component in the exhaust gas to be measured is eliminated by causing the exhaust gas to collide with a heated collision member or passing through a heated filter. A method for measuring the amount of unburned fuel. It has a measurement pipe, a heating collision part, and a mass spectrometer,
The exhaust gas passage through which the exhaust gas to be measured passes and the mass spectrometer are connected by the measurement pipe,
The heating collision member is provided in the middle of the measurement pipe, a heating collision member for colliding the particulate matter of the exhaust gas introduced into the measurement pipe is arranged inside the heating collision section, and the mass spectrometer A system for measuring the amount of unburned fuel in exhaust gas, characterized by comprising a mass analyzer and an arithmetic unit.

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