Gas analysis device and gas analysis method

Abstract

A gas analysis device comprising: a first flow channel in which a sample gas flows; a first analyzer for performing wet measurement of the total hydrocarbon concentration in the sample gas, the first analyzer being provided in the first flow channel; a second flow channel in which the sample gas flows; a non-methane cutter for removing a hydrocarbon component other than methane from the sample gas, the non-methane cutter being provided in the second flow channel; a second analyzer for performing dry measurement of the methane concentration in the sample gas, the second analyzer being provided downstream from the non-methane cutter in the second flow channel; and a calculation unit for calculating the concentration of the hydrocarbon component other than methane in the sample gas using the total hydrocarbon concentration from the first analyzer and a corrected methane concentration obtained by moisture correction of the methane concentration from the second analyzer.

Description

[Technical field]

[0001] The present invention relates to a gas analysis device and a gas analysis method. [Background technology]

[0002] Conventionally, the total hydrocarbons (THC) contained in exhaust gas were extracted from methane (CH 4 A gas analyzer that determines the concentration of non-methane hydrocarbons (NMHCs) excluding methane hydrocarbons (NHCs) has been developed.

[0003] This gas analyzer is configured using a detector that uses a flame ionization detector (FID), and measures the THC concentration in the exhaust gas by the detector, and also measures the methane concentration contained in the exhaust gas that has passed through a non-methane cutter (NMC) that removes hydrocarbon components other than methane from the exhaust gas by the detector. The gas analyzer then calculates the concentration of hydrocarbon components other than methane (NMHC) from the difference in the concentrations obtained by the detectors. Usually, this gas analyzer measures the THC concentration and methane concentration by so-called wet measurement, in which the temperature of the exhaust gas and its flow path is heated and then measured without dehumidification in order to prevent the adsorption of HC components to the flow path and the loss of dissolution due to water droplets remaining in the flow path (Patent Document 1).

[0004] Incidentally, the NMC used to measure methane concentration is adjusted to a high temperature of 300°C or more, and is designed to oxidize and remove hydrocarbon components other than methane through a catalytic effect. However, at such high temperatures, methane is also partially oxidized in the NMC, so a certain amount of moisture is added to the NMC to adjust the amount of methane oxidation. However, when measurements are taken under conditions in which the moisture concentration in the exhaust gas fluctuates greatly, the fluctuation in moisture concentration leads to fluctuations in the amount of methane oxidation in the NMC, which has a significant effect on the measured value of the methane concentration. For this reason, it is desirable to measure the methane concentration by so-called dry measurement, by installing a device such as a dehumidifier that keeps the moisture concentration in the exhaust gas constant upstream of the NMC.

[0005] However, as mentioned above, it is desirable to measure the THC concentration by wet measurement in order to prevent dissolution loss of HC components. Conventionally, a method for accurately calculating the NMHC concentration using the THC concentration measured by wet measurement and the methane concentration measured by dry measurement has not been established because the measurement conditions are different for each. The same is true when measuring the concentration of hydrocarbons other than methane and ethane (NMNEHC: Non-Methane Non-Ethane Hydro-Carbon) using a non-methane non-ethane cutter (NMC) that removes hydrocarbon components other than methane and ethane from exhaust gas. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2002-350304 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of these problems, and has as its main object to provide a gas analyzer that can accurately calculate the concentrations of NMHC and NMNEHC in a sample gas. [Means for solving the problem]

[0008] That is, the gas analyzing apparatus of the present invention is characterized by comprising a first flow path through which a sample gas flows, a first analyzer provided in the first flow path for wet measuring a total hydrocarbon concentration in the sample gas, a second flow path through which the sample gas flows, a non-methane cutter provided in the second flow path for removing hydrocarbon components other than methane in the sample gas, a second analyzer provided in the second flow path downstream of the non-methane cutter for dry measuring the methane concentration in the sample gas, and a calculation unit that calculates the concentration of hydrocarbon components other than methane in the sample gas using the total hydrocarbon concentration of the first analyzer and a corrected methane concentration obtained by correcting the methane concentration of the second analyzer for moisture.

[0009] With this configuration, for example, a dehumidifier or the like that keeps the moisture concentration in the sample gas constant is placed upstream of the non-methane cutter to measure the methane concentration on a dry basis, thereby reducing the variation in the amount of methane oxidation in the non-methane cutter. Then, this dry measured methane concentration value is corrected for moisture and converted into a corrected methane concentration value that assumes a wet measurement, so that the measurement conditions can be made closer to those of the wet measured THC concentration value. This makes it possible to accurately calculate the NMHC concentration while measuring the THC concentration on a wet basis and the methane concentration on a dry basis. The NMHC includes, for example, hydrocarbons with more carbon atoms than methane and those with functional groups substituted thereon, specifically, alcohols, ethers, carboxylic acids, aldehydes, benzene, esters, etc.

[0010] A specific configuration of the gas analyzer includes a heating unit provided in the first flow path for heating the temperature of the sample gas, and a moisture concentration adjusting unit for adjusting the moisture concentration in the sample gas provided upstream of the non-methane cutter in the second flow path. This heating unit preferably heats the temperature of the sample gas to a temperature equal to or higher than the dew point temperature. A specific example of the moisture concentration adjusting unit is a dehumidifier that reduces the moisture concentration in the sample gas.

[0011] The corrected methane concentration is a methane concentration that takes into account the moisture concentration removed by the dehumidifier, and specifically, it is desirable to obtain the methane concentration obtained by multiplying the methane concentration from the second analyzer by a predetermined moisture concentration correction coefficient.

[0012] When the second analyzer is calibrated using methane by passing it through the non-methane cutter, the calculation unit may calculate the concentration of hydrocarbon components other than methane in the sample gas by the following formula (A). TIFF0007638294000001.tif11158x NMHC : Concentration of hydrocarbon components other than methane in the sample gas x THC(NMC-FID) : Methane concentration of the second analyzer RF CH4(THC-FID) : Response factor of methane in the first analyzer x THC(THC-FID) : Total hydrocarbon concentration of the first analyzer RF C2H6(NMC-FID) : Response factor of ethane in the second analyzer PF C2H6(NMC-FID) : Ethane permeability of the second analyzer K: Moisture concentration correction coefficient

[0013] In addition, when the second analyzer is calibrated using methane while bypassing the non-methane cutter, the calculation unit may calculate the concentration of hydrocarbon components other than methane in the sample gas using the following formula (B). TIFF0007638294000002.tif11158x NMHC : Concentration of hydrocarbon components other than methane in the sample gas x THC(NMC-FID) : Methane concentration of the second analyzer RF CH4(THC-FID) : Response factor of methane in the first analyzer x THC(THC-FID) : Total hydrocarbon concentration of the first analyzer PF CH4(NMC-FID) : methane transmittance of the second analyzer RF C2H6(NMC-FID) : Response factor of ethane in the second analyzer PF C2H6(NMC-FID) : Ethane permeability of the second analyzer K: Moisture concentration correction coefficient

[0014] In addition, when the second analyzer is calibrated by bypassing the non-methane cutter using propane, the calculation unit may calculate the concentration of hydrocarbon components other than methane in the sample gas using the following formula (C). TIFF0007638294000003.tif11158x NMHC : Concentration of hydrocarbon components other than methane in the sample gas x THC(NMC-FID) : Methane concentration of the second analyzer x THC(THC-FID) : Total hydrocarbon concentration of the first analyzer PF CH4(NMC-FID) : methane transmittance of the second analyzer PF C2H6(NMC-FID) : Ethane permeability of the second analyzer K: Moisture concentration correction coefficient

[0015] It is desirable that the gas analyzer further comprises a third flow path through which the sample gas flows, a non-methane / non-ethane cutter provided in the third flow path for removing hydrocarbon components other than methane and ethane from the sample gas, and a third analyzer provided in the third flow path downstream of the non-methane / non-ethane cutter for dry measuring a total methane and ethane concentration of methane and ethane in the sample gas, and the calculation unit calculates the concentration of the hydrocarbon components other than methane and ethane in the sample gas using the total hydrocarbon concentration of the first analyzer and a corrected total methane and ethane concentration obtained by correcting the total methane and ethane concentration of the third analyzer for moisture correction.

[0016] Furthermore, it is preferable that the calculation unit is configured to calculate the concentration of hydrocarbon components other than methane in the sample gas by the following formula (D) when the third analyzer is calibrated using ethane by passing it through the non-methane / non-ethane cutter. TIFF0007638294000004.tif11158x NMNHC : Concentration of hydrocarbon components other than methane and ethane in the sample gas x THC(NMNEC-FID) : Total methane and ethane concentration of the third analyzer x THC(THC-FID) : Total hydrocarbon concentration of the first analyzer PF C3H8(NMNEC-FID) : Propane permeability of the third analyzer K': Moisture concentration correction coefficient

[0017] The gas analyzer of the present invention is characterized in that it comprises a first flow path through which a sample gas flows, a first analyzer provided in the first flow path and performing wet measurement of a total hydrocarbon concentration in the sample gas, a second flow path through which the sample gas flows, a non-methane / non-ethane cutter provided in the second flow path and removing hydrocarbon components other than methane and ethane from the sample gas, a second analyzer provided in the second flow path downstream of the non-methane / non-ethane cutter and performing dry measurement of a total methane and ethane concentration in the sample gas, and a calculation unit that calculates the concentration of hydrocarbon components other than methane and ethane in the sample gas using the total hydrocarbon concentration of the first analyzer and a corrected total methane and ethane concentration obtained by correcting the total methane and ethane concentration of the second analyzer for moisture correction.

[0018] With this configuration, for example, a dehumidifier that keeps the moisture concentration in the sample gas constant is placed upstream of the non-methane / non-ethane cutter to measure the methane concentration on a dry basis, thereby reducing the variation in the amount of oxidation of methane and ethane in the non-methane / non-ethane cutter. Then, the dry measured total concentration value of methane and ethane is corrected for moisture and converted to a corrected total concentration value of methane and ethane assuming a wet measurement, so that the measurement conditions of the THC concentration value measured on a wet basis can be approximated. This makes it possible to accurately calculate the NMNEHC concentration while measuring the THC concentration on a wet basis and the total concentration of methane and ethane on a dry basis. The NMNEHC includes, for example, hydrocarbons with more carbon atoms than ethane and those with substituted functional groups, specifically, alcohols, ethers, carboxylic acids, aldehydes, benzene, esters, etc.

[0019] The gas analyzer of the present invention is characterized in that it comprises a first flow path through which a sample gas flows, a first analyzer provided in the first flow path for wet measuring a total hydrocarbon concentration in the sample gas, a second flow path through which the sample gas flows, a hydrocarbon selective catalyst provided in the second flow path for removing specified hydrocarbon components in the sample gas, a second analyzer provided in the second flow path downstream of the hydrocarbon selective catalyst for dry measuring the concentration of hydrocarbon components in the sample gas, and a calculation unit that calculates the concentration of the specified hydrocarbon component in the sample gas using the total hydrocarbon concentration of the first analyzer and a corrected hydrocarbon component concentration obtained by correcting the concentration of the hydrocarbon component of the second analyzer for moisture. This gas analyzer can not only accurately measure the concentration of hydrocarbon components other than methane and ethane (NMNEHC) in a sample gas, but also the concentration of hydrocarbon components other than methane (NMHC) in a sample gas. In addition, the non-methane / non-ethane cutter and the non-methane cutter can be configured using a common hydrocarbon selective catalyst, simplifying the flow path configuration.

[0020] Furthermore, the gas analysis method of the present invention is characterized in that a first analyzer for wet measuring a total hydrocarbon concentration in the sample gas is provided in a first flow path through which a sample gas flows, a non-methane cutter for removing hydrocarbon components other than methane from the sample gas is provided in a second flow path through which the sample gas flows, and a second analyzer for dry measuring a methane concentration in the sample gas is provided downstream of the non-methane cutter in the second flow path, and the concentration of the hydrocarbon components other than methane in the sample gas is calculated using the total hydrocarbon concentration of the first analyzer and a corrected methane concentration obtained by correcting the methane concentration of the second analyzer for moisture.

[0021] Such a gas analysis method can achieve the same effects as those of the gas analyzer of the present invention described above. Effect of the Invention

[0022] According to the present invention configured as described above, it is possible to provide a gas analyzer that accurately calculates the concentration of NMHC and the concentration of NMNEHC in a sample gas. [Brief description of the drawings]

[0023] [Figure 1] 1 is a diagram illustrating a schematic configuration of a gas analyzer according to an embodiment of the present invention. [Diagram 2] FIG. 13 is a diagram illustrating a schematic configuration of a gas analyzer according to another embodiment. [Diagram 3] FIG. 13 is a diagram illustrating a schematic configuration of a gas analyzer according to another embodiment. [Figure 4] FIG. 13 is a diagram illustrating a schematic configuration of a gas analyzer according to another embodiment. [Explanation of symbols]

[0024] 100 Gas analyzer L1: First flow path 2...1st analyzer L2: Second flow path 3. Non-methane cutter (NMC) 4...Second analyzer 9...Moisture concentration adjustment section 11 Calculation section DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] A gas analyzer 100 according to one embodiment of the present invention will be described below with reference to the drawings.

[0026] <Device configuration> The gas analyzer 100 of this embodiment analyzes hydrocarbons contained in exhaust gas discharged from an internal combustion engine, for example.

[0027] Specifically, as shown in FIG. 1, this gas analysis device 100 includes a first flow path L1 through which exhaust gas, which is a sample gas, flows, a first analyzer 2 provided in the first flow path L1 and measuring the total hydrocarbon concentration (THC concentration) in the exhaust gas, a second flow path L2 provided separately from the first flow path L1 and through which exhaust gas flows, a non-methane cutter (NMC) 3 provided in the second flow path L2 and removing hydrocarbon components other than methane (NMHC) in the exhaust gas, and a second analyzer 4 provided downstream of the NMC 3 in the second flow path L2 and measuring the methane concentration in the exhaust gas.

[0028] In this embodiment, the first flow path L1 and the second flow path L2 branch off from a predetermined branch point BP of a main flow path ML that has an introduction port P1 into which exhaust gas is introduced.

[0029] A first flow rate adjustment mechanism 5 and a second flow rate adjustment mechanism 6 are provided in the first flow path L1 and the second flow path L2, respectively, in order to synchronize the response timings of the first analyzer 2 and the second analyzer 4.

[0030] The first flow control mechanism 5 is constituted, for example, by a capillary provided upstream of the first analyzer 2 in the first flow path L1, and the second flow control mechanism 6 is constituted, for example, by a capillary provided upstream of the second analyzer 4 in the second flow path L2.

[0031] The NMC3 provided in the second flow path L2 is an oxidation catalyst, and may be, for example, manganese dioxide, copper oxide, platinum, or other metals that serve as oxidation catalysts. The NMC3 is heated to 300° C. or higher. Specifically, the second flow path L2 is provided with a heating unit 7 for heating the NMC3 to the above temperature. By heating to this temperature, the NMC3 efficiently combusts and removes hydrocarbon components other than methane, and allows methane to pass through efficiently (for example, 80% or more).

[0032] Further provided here are a bypass line BL that branches off from the upstream side of the NMC3 and joins the downstream side, and a switching valve V such as a three-way valve for selectively flowing exhaust gas into the NMC3 or the bypass line BL.

[0033] The first analyzer 2 and the second analyzer 4 are flame ionization (FID) detectors that detect hydrocarbons in the exhaust gas by a hydrogen flame ionization (FID) method. 2 , or H 2 A mixture gas of H2O / He and combustion supporting air are supplied from a gas supply line (not shown). A calibration gas supply line 8 for supplying a calibration gas for calibrating the first analyzer 2 and the second analyzer 4 is connected to the first flow path L1 and the second flow path L2.

[0034] This gas analyzer 100 is configured such that the first analyzer 2 performs wet measurement of the total hydrocarbon concentration in the exhaust gas, and the second analyzer 4 performs dry measurement of the methane concentration in the exhaust gas.

[0035] Specifically, the first flow path L1 is provided with a heating unit (heating block) B that heats the flow path and the first analyzer 2 to a predetermined temperature (e.g., 191° C.). This predetermined temperature is preferably equal to or higher than a dew point temperature according to the pressure of the exhaust gas.

[0036] On the other hand, upstream of the NMC3 in the second flow path L2, a moisture concentration adjusting unit 9 that adjusts the moisture concentration in the exhaust gas is provided. This moisture concentration adjusting unit 9 is configured to change the temperature of the exhaust gas to keep the moisture concentration constant, and reduces the moisture concentration contained in the sample gas to a preset concentration. For example, this moisture concentration adjusting unit 9 uses a dehumidifier that cools the exhaust gas introduced into the NMC3 to a temperature equal to or lower than the dew point temperature to dehumidify it. For example, this dehumidifier may be an electronic cooler that uses the Peltier effect to perform cooling, or a compressor type that uses a compressor. Note that, upstream of the dehumidifier in the second flow path L2, a humidifier that makes the moisture concentration in the exhaust gas introduced into the dehumidifier higher than the saturated water vapor amount in the dehumidifier may be provided.

[0037] A moisture supply line 10 that supplies moisture to the second flow path L2 is connected between the moisture concentration adjuster 9 in the second flow path L2 and the NMC 3. A regulator (not shown) is provided in this moisture supply line 10, and is configured to be able to control the amount of moisture supplied to the second flow path L2 to a predetermined amount. Here, the moisture supply line 10 is configured to supply 1 to 2 vol % moisture to the second flow path L2.

[0038] The gas analyzer 100 is equipped with a calculation unit 11 that calculates the concentration of NMHC in the exhaust gas from the concentrations obtained by the first analyzer 2 and the second analyzer 4.

[0039] Therefore, the calculation unit 11 of this embodiment calculates the NMHC concentration in the exhaust gas using the THC concentration measured by the first analyzer 2 and the corrected methane concentration obtained by correcting the methane concentration measured by the second analyzer 4 for moisture.

[0040] Specifically, this corrected methane concentration is a methane concentration that takes into account the moisture concentration removed by the dehumidifier, and more specifically, is calculated by multiplying the methane concentration measured by the second analyzer 4 by a predetermined moisture concentration correction coefficient K.

[0041] This moisture concentration correction coefficient K is used to convert the methane concentration measured on a dry basis into a value measured on a wet basis, and is expressed by the following formula (a) or an equivalent formula: TIFF0007638294000005.tif11158

[0042] where x H2O·w is the moisture concentration in the exhaust gas before the moisture concentration adjustment upstream of the moisture concentration adjusting unit 9 in the second flow path L2, and x H2O·d is the moisture concentration in the exhaust gas after the moisture concentration adjustment downstream of the moisture concentration adjuster 9 in the second flow passage L2.

[0043] More specifically, calculation unit 11 calculates the NMHC concentration according to the calibration method of second analyzer 4 using the following formulas (1) to (3).

[0044] (A) Calibration using methane passed through NMC3 TIFF0007638294000006.tif11158(B) Calibration with NMC3 bypassed using methane TIFF0007638294000007.tif11158(C) Calibration with NMC3 bypassed using propane TIFF0007638294000008.tif11158

[0045] Where: x NMHC : Concentration of hydrocarbon components other than methane in exhaust gas x THC(THC-FID) : Total hydrocarbon concentration of first analyzer 2 x THC(NMC-FID) : Methane concentration of the second analyzer 4 RF CH4(THC-FID) : Response factor of methane in the first analyzer 2 RF C2H6(NMC-FID) : Response factor of ethane in the second analyzer 4 PF CH4(NMC-FID) : Methane transmittance of the second analyzer 4 PF C2H6(NMC-FID) : Ethane transmittance of the second analyzer 4 K: Moisture concentration correction coefficient It is.

[0046] The derivation of the above formulas (1) to (3) will be explained below.

[0047] First, the THC concentration x measured by the first analyzer 2 THC[THC-FID] is the response factor RF of methane at the first analyzer 2 CH4[THC-FID] , methane concentration in sample gas x CH4 , the concentration of hydrocarbon components other than methane in the sample gas x NMHC Using this, we obtain the following equation (4).

[0048] x THC[THC-FID] =x CH4 ×RF CH4[THC-FID] +x NMHC (4)

[0049] This equation (4) is for the first analyzer 2 (THC-FID) to measure propane C 3 H 8 It is assumed that the RF gas is calibrated using standard gases. CH4[THC-FID] is the response coefficient of methane for the first analyzer 2 calibrated with propane. The response coefficient is the sensitivity difference (ratio) of the target component to the calibration gas.

[0050] The methane concentration obtained by the second analyzer 4 (NMC-FID) has a different concentration calculation formula depending on the calibration method.

[0051] (A) Calibration using methane passed through NMC3 In this case, the methane concentration measured by the second analyzer 4 in a dry state is expressed by the following formula (5). x THC[NMC-FID] =[x CH4 +x NMHC ×RF C2H6[NMC-FID] ×PF C2H6[NMC-FID] ] / K (5)

[0052] (B) Calibration with methane bypassing NMC3 In this case, the methane concentration measured by the second analyzer 4 in a dry state is expressed by the following formula (6). x THC[NMC-FID] =[x CH4 ×PF CH4[NMC-FID] +x NMHC ×RF C2H6[NMC-FID] ×PF C2H6[NMC-FID] ] / K (6)

[0053] (C) Calibration with propane bypassing NMC3 In this case, the methane concentration measured by the second analyzer 4 in a dry state is given by the following equation (7). x THC[NMC-FID] =[x CH4 ×RF CH4[NMC-FID] ×PF CH4[NMC-FID] +x NMHC ×RF C2H6[NMC-FID] ×PF C2H6[NMC-FID] ] / K (7)

[0054] Then, using the above equation (4), which represents the THC concentration measured wet by the first analyzer 2, and the above equations (5) to (7), which represent the methane concentration measured dry by the second analyzer 4, equations (1) to (3), which are calculation equations for the NMHC concentration according to the calibration method of the second analyzer 4 described above, can be obtained.

[0055] <Effects of this embodiment> According to the gas analyzer 100 of the present embodiment, the methane concentration value measured on a dry basis is moisture-corrected and converted to a corrected methane concentration value assuming, for example, wet measurement, thereby making it possible to approximate the measurement conditions of the THC concentration value measured on a wet basis. This makes it possible to accurately calculate the NMHC concentration while measuring the THC concentration on a wet basis and the methane concentration on a dry basis.

[0056] <Other Modified Embodiments> The present invention is not limited to the above-described embodiment.

[0057] As shown in Fig. 2, the gas analyzer 100 may further include a third flow path L3 provided with a non-methane / non-ethane cutter (NMNEC) 12 for removing hydrocarbon components other than methane and ethane from the sample gas as the sample gas flows, and a third analyzer 13 provided in the third flow path L3 for dry measuring the total methane / ethane concentration of methane and ethane in the sample gas. In this case, a heating unit 14 for heating the NMNEC to a temperature of 200 to 250°C is provided in the third flow path L3. In this case, a moisture concentration adjusting unit 9 (e.g., a dehumidifier, etc.) for adjusting the moisture concentration in the sample gas is provided upstream of the NMNEC in the third flow path L3, and a moisture supply line 10 is connected between the moisture concentration adjusting unit 9 and the NMNEC in the third flow path L3.

[0058] In this case, the calculation unit 11 (not shown in FIG. 2) can calculate the concentration of hydrocarbon components other than methane and ethane (NMNEHC) in the sample gas using the THC concentration of the first analyzer 2 and the corrected methane / ethane total concentration obtained by correcting the methane / ethane total concentration of the third analyzer 13 for moisture. This moisture correction is performed in the same manner as the moisture correction of the methane concentration described above. The calculation of the concentration of hydrocarbon components other than methane and ethane (NMNEHC) by the calculation unit 11 is performed based on a predetermined calculation formula corresponding to the calibration method of the third analyzer 13, similar to the calculation of the concentration of hydrocarbon components other than methane (NMHC) described above.

[0059] Specifically, this corrected methane / ethane total concentration is the total concentration of methane and ethane taking into account the moisture concentration removed by the dehumidifier, and more specifically, is calculated by multiplying the methane / ethane total concentration measured by the third analyzer 13 by a predetermined moisture concentration correction coefficient K'.

[0060] This moisture concentration correction coefficient K' is used to convert the dry measured methane and ethane total concentration into a wet measured value, and is expressed by the following equation (b) or an equivalent equation. TIFF0007638294000009.tif11158

[0061] where x' H2O·w is the moisture concentration in the exhaust gas before the moisture concentration adjustment upstream of the moisture concentration adjusting unit 9 in the third flow path L3, and x' H2O·d is the moisture concentration in the exhaust gas after the moisture concentration adjustment downstream of the moisture concentration adjuster 9 in the third flow passage L3.

[0062] Then, calculation unit 11 calculates the NMNEHC concentration using the following formula (8). TIFF0007638294000010.tif11158

[0063] Where: x NMNEHC : Concentration of hydrocarbon components other than methane and ethane in exhaust gas x THC(THC-FID) : Total hydrocarbon concentration of first analyzer 2 x THC(NMNEC-FID) : Total methane and ethane concentration of the third analyzer 13 PF C3H8(NMNEC-FID) : Propane permeability of the third analyzer 13 K': Moisture concentration correction coefficient It is.

[0064] The derivation of the above formula (8) will be explained below. First, the THC concentration x measured by the first analyzer 2 THC[THC-FID] is the response factor RF of methane at the first analyzer 2 CH4[THC-FID] , the response factor of ethane in the first analyzer 2, RF C2H6[THC-FID] , methane concentration in sample gas x CH4 , the ethane concentration in the sample gas x C2H6 , the concentration of hydrocarbon components other than methane and ethane in the sample gas x NMNEHC Using this, we obtain the following equation (9).

[0065] x THC[THC-FID] =x CH4 ×RF CH4[THC-FID] +x C2H6 ×RF C2H6[THC-FID] +x NMNEHC (9)

[0066] This equation (9) is the first analyzer 2 (THC-FID) 3 H 8 It is assumed that the RF gas is calibrated using standard gases. CH4[THC-FID] and RF C2H6[THC-FID] are the response coefficients of methane and ethane, respectively, of the first analyzer 2 calibrated with propane. The response coefficient is the sensitivity difference (ratio) of the target component to the calibration gas. Here, propane C 3 H 8 Since the sensitivity difference of ethane to the first analyzer can be considered to be 1, the response factor RF C2H6[THC-FID] can be approximated as 1.

[0067] Next, the total concentration of methane and ethane obtained by dry measurement using the third analyzer 13 (NMNEC-FID) is expressed by the following equation (10) when calibrated by passing ethane through the NMNEC 12 as the calibration gas.

[0068] x THC[NMNEC-FID] =[x CH4 ×RF CH4[NMNEC-FID] ×PF CH4[NMNEC-FID] +x C2H6 +x NMNEHC ×RF C3H8[NMNEC-FID] ×PF C3H8[NMNEC-FID] ] / K' (10)

[0069] Where: RF CH4[NMNEC-FID] : Response factor of methane in the third analyzer 13 PF CH4[NMNEC-FID] :Methane transmission rate of the third analyzer 13 RF C3H8[NMNEC-FID] : Response factor of propane in the third analyzer 13 PF C3H8[NMNEC-FID] : Propane permeability of the third analyzer 13 Since the NMNEC12 is heated to 200-250℃, it is considered that all the methane in the sample gas is transmitted through it. CH4[NMNEC-FID] can be approximated as 1. Furthermore, since the sensitivity difference of propane with respect to ethane can be considered as 1, the response factor RF of propane in the third analyzer 13 is C3H8[NMNEC-FID]can be approximated as 1.

[0070] Then, using the above equation (9), which represents the THC concentration measured wet by the first analyzer 2, and the above equation (10), which represents the combined methane and ethane concentration measured dry by the third analyzer 13, equation (8), which is the calculation equation for the NMNEHC concentration mentioned above, can be obtained.

[0071] The calculation unit 11 can also calculate the ethane concentration in the sample gas using the corrected methane concentration from the second analyzer 4 and the corrected total methane and ethane concentration from the third analyzer 13.

[0072] Furthermore, a third flow rate adjustment mechanism 15 is provided in the third flow path L3 to synchronize the response timing of the first analyzer 2 and the second analyzer 4 with that of the third analyzer 13. The third flow rate adjustment mechanism 15 is configured by, for example, a capillary provided upstream of the third analyzer 13 in the third flow path L3.

[0073] In addition, as shown in FIG. 3, the gas analyzer 100 may be configured to introduce the sample gas into a common analyzer by merging the downstream side of the NMC3 in the second flow path L2 and the downstream side of the NMNEC in the third flow path L3. In this case, a flow path switching mechanism 16, for example, consisting of on-off valves V1 and V2, is provided to switch the flow path through which the sample gas flows between the second flow path L2 and the third flow path L3. By switching to the second flow path L2, the analyzer measures the methane concentration on a dry basis, and by switching to the third flow path L3, the analyzer measures the total concentration of methane and ethane on a dry basis. With this configuration, the number of analyzers can be reduced, which makes it possible to reduce the cost of the gas analyzer 100.

[0074] In addition, as shown in FIG. 4, the gas analyzer 100 may include a first flow path L1 through which exhaust gas, which is a sample gas, flows, a first analyzer 2 provided in the first flow path L1 and for wet measuring the total hydrocarbon concentration (THC concentration) in the exhaust gas, a second flow path L2 provided separately from the first flow path L1 and through which exhaust gas flows, a moisture concentration adjusting unit 9 (e.g., a dehumidifier) ​​provided in the second flow path L2 for adjusting the moisture concentration in the sample gas, a hydrocarbon selective catalyst 17 for removing a predetermined hydrocarbon component in the exhaust gas, an analyzer 18 provided downstream of the hydrocarbon selective catalyst 17 in the second flow path L2 for dry measuring the concentration of the hydrocarbon component in the exhaust gas, and a temperature switching mechanism 19 for switching the temperature of the hydrocarbon selective catalyst 17. The analyzer 18 is an FID detector for detecting hydrocarbons in the exhaust gas by a flame ionization (FID) method. The hydrocarbon selective catalyst 17 is a catalyst that can select a hydrocarbon component to be removed depending on the temperature, and becomes, for example, a non-methane cutter or a non-methane / non-ethane cutter depending on the temperature. The hydrocarbon selective catalyst 17 may be capable of selectively removing not only methane, or methane and ethane, but also other hydrocarbons. The temperature switching mechanism 19 is configured by a heating unit whose set temperature can be changed, as in the above embodiment.

[0075] Then, the temperature switching mechanism 19 heats the hydrocarbon selective catalyst 17 to 200 to 250°C, turning the hydrocarbon selective catalyst 17 into a non-methane / non-ethane cutter that removes hydrocarbon components other than methane and ethane from the exhaust gas. This allows the analyzer 18 to measure the methane / ethane total concentration of methane and ethane in the exhaust gas on a dry basis. Here, the calculation unit 11 of the gas analyzer 100 calculates the concentration of the hydrocarbon components other than methane and ethane in the exhaust gas from the THC concentration of the first analyzer 2 and the corrected methane / ethane total concentration obtained by correcting the methane / ethane total concentration of the analyzer 18 for moisture.

[0076] Furthermore, the temperature switching mechanism 19 heats the hydrocarbon selective catalyst 17 to 300°C or higher to serve as a non-methane cutter that removes hydrocarbon components other than methane from the exhaust gas. This allows the analyzer 18 to measure the concentration of methane in the exhaust gas on a dry basis. Here, the calculation unit 11 of the gas analyzer 100 calculates the concentration of the hydrocarbon components other than methane in the exhaust gas from the THC concentration of the first analyzer 2 and the corrected methane concentration obtained by correcting the methane concentration of the analyzer 18 for moisture.

[0077] The temperature switching by the temperature switching mechanism 19 may be configured to be manually set by a user, or may be configured to be automatically set, for example, by a predetermined measurement sequence, etc. In the above description, the analyzer is an FID detector, but any analyzer capable of measuring hydrocarbon components may be used.

[0078] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention. [Industrial Applicability]

[0079] According to the present invention, it is possible to provide a gas analyzer that accurately calculates the concentration of NMHC and the concentration of NMNEHC in a sample gas.

Claims

1. a first flow path through which the sample gas flows; a first analyzer provided in the first flow path for wet measuring a total hydrocarbon concentration in the sample gas; a second flow path through which the sample gas flows; a non-methane cutter provided in the second flow path for removing hydrocarbon components other than methane from the sample gas; a second analyzer provided in the second flow path downstream of the non-methane cutter for dry measuring a methane concentration in the sample gas; a calculation unit that calculates a concentration of hydrocarbon components other than methane in the sample gas using a total hydrocarbon concentration of the first analyzer and a corrected methane concentration obtained by correcting the methane concentration of the second analyzer for moisture.

2. The first flow path is provided with a heating unit that heats the sample gas, 2. The gas analyzer according to claim 1, further comprising a moisture concentration adjusting section arranged upstream of the non-methane cutter in the second flow passage to adjust the moisture concentration in the sample gas.

3. 3. The gas analyzer according to claim 2, wherein the moisture concentration adjusting section is a dehumidifier that reduces the moisture concentration in the sample gas.

4. 4. The gas analyzer according to claim 3, wherein the corrected methane concentration is a methane concentration that takes into account the concentration of moisture removed by the dehumidifier.

5. 5. The gas analyzer according to claim 1, wherein the corrected methane concentration is obtained by multiplying the methane concentration of the second analyzer by a predetermined moisture concentration correction coefficient.

6. When the second analyzer is calibrated using methane passing through the non-methane cutter, 6. The gas analyzer according to claim 1, wherein the calculation unit calculates the concentration of hydrocarbon components other than methane in the sample gas by the following formula (A): x ＮＭＨＣ : Concentration of hydrocarbon components other than methane in the sample gas x ＴＨＣ（ＮＭＣ－ＦＩＤ） : methane concentration of the second analyzer RF ＣＨ４（ＴＨＣ－ＦＩＤ） : Response factor of methane in the first analyzer x ＴＨＣ（ＴＨＣ－ＦＩＤ） : total hydrocarbon concentration of the first analyzer RF Ｃ２Ｈ６（ＮＭＣ－ＦＩＤ） : ethane response factor in the second analyzer P.F. Ｃ２Ｈ６（ＮＭＣ－ＦＩＤ） : Ethane permeability of the second analyzer K: Moisture concentration correction coefficient

7. When the second analyzer is calibrated using methane to bypass the non-methane cutter, 6. The gas analyzer according to claim 1, wherein the calculation unit calculates the concentration of hydrocarbon components other than methane in the sample gas by the following formula (B): x ＮＭＨＣ : Concentration of hydrocarbon components other than methane in the sample gas x ＴＨＣ（ＮＭＣ－ＦＩＤ） : methane concentration of the second analyzer RF ＣＨ４（ＴＨＣ－ＦＩＤ） : Response factor of methane in the first analyzer x ＴＨＣ（ＴＨＣ－ＦＩＤ） : total hydrocarbon concentration of the first analyzer P.F. ＣＨ４（ＮＭＣ－ＦＩＤ） : methane transmittance of the second analyzer RF Ｃ２Ｈ６（ＮＭＣ－ＦＩＤ） : ethane response factor in the second analyzer P.F. Ｃ２Ｈ６（ＮＭＣ－ＦＩＤ） : Ethane permeability of the second analyzer K: Moisture concentration correction coefficient

8. When the second analyzer is calibrated using propane to bypass the non-methane cutter, 6. The gas analyzer according to claim 1, wherein the calculation unit calculates the concentration of hydrocarbon components other than methane in the sample gas by the following formula (C): x ＮＭＨＣ : Concentration of hydrocarbon components other than methane in the sample gas x ＴＨＣ（ＮＭＣ－ＦＩＤ） : methane concentration of the second analyzer x ＴＨＣ（ＴＨＣ－ＦＩＤ） : total hydrocarbon concentration of the first analyzer P.F. ＣＨ４（ＮＭＣ－ＦＩＤ） : methane transmittance of the second analyzer P.F. Ｃ２Ｈ６（ＮＭＣ－ＦＩＤ） : Ethane permeability of the second analyzer K: Moisture concentration correction coefficient

9. a third flow path through which the sample gas flows; a non-methane / non-ethane cutter provided in the third flow path for removing hydrocarbon components other than methane and ethane from the sample gas; a third analyzer that is provided in the third flow path downstream of the non-methane / non-ethane cutter and that measures a total methane / ethane concentration of methane and ethane in the sample gas on a dry basis, 9. The gas analyzer according to claim 1, wherein the calculation unit calculates concentrations of hydrocarbon components other than methane and ethane in the sample gas, using a total hydrocarbon concentration of the first analyzer and a corrected total methane and ethane concentration obtained by correcting the total methane and ethane concentration of the third analyzer for moisture.

10. When the third analyzer is calibrated by passing ethane through the non-methane / non-ethane cutter, 10. The gas analyzer according to claim 9, wherein the calculation unit calculates the concentration of hydrocarbon components other than methane in the sample gas by the following formula (D): x ＮＭＮＨＣ : Concentration of hydrocarbon components other than methane and ethane in the sample gas x ＴＨＣ（ＮＭＮＥＣ－ＦＩＤ） :Methane and ethane total concentration of the third analyzer x ＴＨＣ（ＴＨＣ－ＦＩＤ） : total hydrocarbon concentration of the first analyzer P.F. Ｃ３Ｈ８（ＮＭＮＥＣ－ＦＩＤ） : propane permeability of the third analyzer K': Moisture concentration correction coefficient

11. a first flow path through which the sample gas flows; a first analyzer provided in the first flow path for wet measuring a total hydrocarbon concentration in the sample gas; a second flow path through which the sample gas flows; a non-methane / non-ethane cutter provided in the second flow path for removing hydrocarbon components other than methane and ethane from the sample gas; a second analyzer that is provided in the second flow path downstream of the non-methane / non-ethane cutter and that measures a total concentration of methane and ethane in the sample gas on a dry basis; a calculation unit that calculates concentrations of hydrocarbon components other than methane and ethane in the sample gas using the total hydrocarbon concentration of the first analyzer and a corrected total methane and ethane concentration obtained by correcting the total methane and ethane concentration of the second analyzer for moisture.

12. a first flow path through which the sample gas flows; a first analyzer provided in the first flow path for wet measuring a total hydrocarbon concentration in the sample gas; a second flow path through which the sample gas flows; a hydrocarbon selective catalyst provided in the second flow path for removing a predetermined hydrocarbon component in the sample gas; a second analyzer that is provided downstream of the hydrocarbon selective catalyst in the second flow path and that performs dry measurement of a concentration of a hydrocarbon component in the sample gas; a calculation unit that calculates the concentration of the specified hydrocarbon component in the sample gas using the total hydrocarbon concentration of the first analyzer and a corrected hydrocarbon component concentration obtained by correcting the concentration of the hydrocarbon component from the second analyzer for moisture.

13. a first analyzer for wet measuring a total hydrocarbon concentration in the sample gas is provided in a first flow path through which the sample gas flows; a non-methane cutter for removing hydrocarbon components other than methane from the sample gas is provided in a second flow path through which the sample gas flows; a second analyzer for dry measuring a methane concentration in the sample gas is provided downstream of the non-methane cutter in the second flow path; A gas analysis method comprising: calculating concentrations of hydrocarbon components other than methane in the sample gas using a total hydrocarbon concentration measured by the first analyzer and a corrected methane concentration obtained by correcting the methane concentration measured by the second analyzer for moisture.

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