Method for determining total volatile organic compound concentration of oil field treatment station by using gas chromatography

Abstract

The invention provides a method for measuring the concentration of total volatile organic compounds in an oil field treatment station by using gas chromatography, which belongs to the technical field of analysis and detection, and comprises the following steps: detecting the concentration of a single component by using gas chromatography to obtain the corresponding relationship between the component and the TVOCs concentration measured by Sumar tank sampling / gas chromatography-mass spectrometry; the invention relates to a method for obtaining the TVOCs concentration through simple calculation. According to the method, the characteristics of stability and economy of the gas chromatography are utilized, the TVOCs monitoring cost is reduced, the convenience of obtaining the TVOCs concentration is improved, the method can be conveniently used for daily monitoring of the TVOCs concentration of an uninterrupted and stable-emission oil field treatment station, the defects that an existing gas chromatography-mass spectrometry method is high in analysis cost and cannot be used for daily detection are overcome, and the method is suitable for popularization and application. And the conditions of gas chromatography and mass spectrometry are controlled, so that the test result has higher accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of analysis and detection, and in particular relates to a method for measuring the total volatile organic matter concentration of an oil field processing station by utilizing gas chromatography. Background Art

[0002] Volatile organic compounds (VOCs) include alkanes, olefins, aromatics, halogenated hydrocarbons, alcohols, aldehydes, ketones, etc. Total volatile organic compounds (TVOCs) refer to the sum of VOCs with a melting point below room temperature and a boiling point between 50-260°C. VOCs can have an impact on human health, and some VOCs can harm human health even at very low concentrations. Therefore, there are strict control standards for VOCs emissions at home and abroad.

[0003] At present, the commonly used pretreatment methods for VOCs include solvent desorption, low-temperature preconcentration-thermal desorption, solid phase extraction, headspace method, supercritical fluid extraction, purge-filling method, etc.; the analysis methods include gas chromatography, high performance liquid chromatography and gas chromatography-mass spectrometry, fluorescence spectrophotometry, colorimetric tube detection, etc., among which the most commonly used methods are gas chromatography and gas chromatography-mass spectrometry. The more mature ones are solid phase adsorption-thermal desorption / gas chromatography-mass spectrometry and Suma jar sampling / gas chromatography-mass spectrometry. Solid phase adsorption-thermal desorption / gas chromatography-mass spectrometry can determine 24 VOCs components in the exhaust gas of fixed pollution sources; for example, Li Xiaomin et al. published "Rapid Determination of Polycyclic Aromatic Hydrocarbons in the Air by Stirring Bar Solid Phase Adsorption-Thermal Desorption-Gas Chromatography / Mass Spectrometry" in Analytical Chemistry, Vol. 39, November 2011. They used a stirring bar coated with polydimethylsiloxane as an atmospheric passive sampler and established a stirring bar solid phase adsorption-thermal desorption-gas chromatography / mass spectrometry / mass spectrometry for rapid determination of polycyclic aromatic hydrocarbons in the air. Researchers usually use Suma tank sampling / gas chromatography-mass spectrometry to qualitatively and quantitatively detect TVOCs in exhaust gas; for example, Cui Lianxi et al. published "Suma tank sampling-gas chromatography-mass spectrometry for the determination of 99 volatile organic compounds in ambient air" in Volume 48, Issue 3, February 2020, Guangzhou Chemical Industry, using Suma tank sampling, pre-concentration with a pre-concentrator, separation with an HP-1 chromatographic column into a mass spectrometer for analysis, qualitative determination by retention time, and quantitative determination by the internal standard method, and established a method for the determination of 99 volatile organic compounds in ambient air by Suma tank sampling-gas chromatography-mass spectrometry. However, both of the above methods use gas chromatography-mass spectrometry, which is expensive and has high sample analysis costs, and are not suitable as routine detection methods for TVOCs in oilfield treatment stations.

[0004] Gas chromatography technology is mature, the equipment is cheap, and it is easy to operate. It has become a method for separating and detecting single components of VOCs in many industries. Chinese patent CN113063771A provides a method for calculating the concentration of volatile organic compounds using the concentration of non-methane hydrocarbons (NMHC) in exhaust gas, but this method requires obtaining multiple NMHC concentrations and the calculation is cumbersome.

[0005] Oilfield treatment stations continuously process produced fluids, crude oil, sewage, etc. The components and proportions of TVOCs are relatively stable, and there is a good correspondence between single components and TVOCs. Therefore, it is expected that the correspondence between single components and TVOCs can be used to obtain the total volatile organic compound concentration more easily. Summary of the invention

[0006] The purpose of the present invention is to provide a method for determining the total volatile organic compound concentration of an oilfield processing station by gas chromatography in view of the deficiencies in the prior art, and to provide an easy-to-operate gas chromatography detection single-component calculation method for oilfield processing stations with uninterrupted operation and stable emissions, thereby obtaining TVOCs concentration conveniently and economically, which can be used for daily detection, and the method is accurate and reliable, and the conditions of gas chromatography and mass spectrometry are controlled to make the test results have higher accuracy.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A method for measuring the total volatile organic compound concentration of an oil field processing station using gas chromatography comprises the following steps:

[0009] (1) Summa tank sampling / gas chromatography-mass spectrometry is used to measure the composition spectrum of the exhaust gas from the target emission source to obtain the concentration of each volatile organic compound (VOCs) and the concentration of total volatile organic compounds (TVOCs);

[0010] (2) analyzing the component spectrum obtained in step (1) and selecting a VOCs component as a representative component;

[0011] (3) detecting the concentration of the representative components selected in step (2) by gas chromatography;

[0012] (4) analyzing the concentration obtained in step (3) and the TVOCs concentration obtained in step (1) to obtain a corresponding relationship between the VOCs concentration and the TVOCs concentration;

[0013] (5) At other time points, the concentration of representative components is detected by gas chromatography, and the TVOCs concentration is obtained by theoretical calculation based on the corresponding relationship obtained in step (4).

[0014] In some embodiments, in step (1), the volatile organic matter in the exhaust gas of the target emission source comprises alkanes, carbon disulfide, dichlorodifluoromethane, and other components with a content of less than 1.2%.

[0015] In other embodiments, in step (1), the Suma tank sampling step includes: cleaning the Suma tank with high-purity nitrogen, evacuating to a vacuum degree of <10Pa, performing instantaneous sampling, pre-concentrating with a three-stage cold trap, heating for desorption, and then detecting.

[0016] Furthermore, the three-stage cold trap pre-concentration conditions are: first-stage cold trap: capture temperature: -150℃~-160℃; decomposition temperature: 8-10℃; valve temperature: 100-120℃; baking temperature: 150-160℃; second-stage cold trap: capture temperature: -150~-160℃; decomposition temperature: 180-200℃; baking temperature: 200-220℃; third-stage cold trap: focusing temperature: -150~-170℃; baking temperature: 150-200℃; transmission line temperature: 100-120℃.

[0017] Preferably, the three-stage cold trap pre-concentration conditions are: first-stage cold trap: capture temperature: -150°C; desorption temperature: 10°C; valve temperature: 120°C; baking temperature: 160°C; second-stage cold trap: capture temperature: -150°C; desorption temperature: 200°C; baking temperature: 220°C; third-stage cold trap: focusing temperature: -160°C; baking temperature: 180°C; gas chromatography transmission line temperature: 120°C.

[0018] In other embodiments, in step (1), the mixed standard gas used for gas chromatography and mass spectrometry is: n-butane, propane, isopentane, isobutane, n-pentane, carbon disulfide, ethane, 2-methylpentane, dichlorodifluoromethane, methylcyclohexane, cyclohexane, methylcyclopentane, n-heptane, n-octane, n-nonane, decane, undecane, dodecane, o-xylene, m-xylene and p-xylene, and the concentration is 0.5-50 mg / m 3 .

[0019] In other embodiments, in step (1), the gas chromatography conditions are:

[0020] Chromatographic column: polysiloxane gas chromatography column;

[0021] Column heating program: initial temperature 38-45°C, hold for 2-5 min, increase to 200-220°C at a rate of 3-8°C / min, hold for 5-8 min;

[0022] Inlet temperature: 200-220℃;

[0023] Carrier gas: helium;

[0024] Column flow rate 1-1.5mL / min, split ratio 15-20:1.

[0025] Preferably, in step (1), the gas chromatography conditions are:

[0026] Chromatographic column: TG-5MS gas chromatography column, 60m×0.25mm×1.0μm;

[0027] Column temperature program: initial temperature 40 °C, hold for 2 min, increase to 210 °C at a rate of 4 °C / min, hold for 6 min;

[0028] Inlet temperature: 200°C;

[0029] Carrier gas: helium;

[0030] The column flow rate was 1 mL / min and the split ratio was 20:1.

[0031] In other embodiments, in step (1), the mass spectrometry conditions are: EI ionization source, ionization energy 70 eV, ion source temperature 220-240°C, and transfer line temperature: 220-230°C.

[0032] Preferably, in step (1), the mass spectrometry conditions are: EI ionization source, ionization energy 70 eV, ion source temperature 230°C, and transmission line temperature: 220°C.

[0033] In other embodiments, in step (2), the selected VOCs component is an alkane, preferably an alkane with the highest concentration.

[0034] In other embodiments, in step (3), the gas chromatography uses n-butane as the standard gas.

[0035] In other embodiments, in step (3), the gas chromatography conditions are:

[0036] Chromatographic column: HP-PLOT Al2O3 column, or Porapak-Q column filled with 13X molecular sieve;

[0037] Column heating program: initial temperature 30-45°C, hold for 6-10 min, increase to 170-180°C at a rate of 15-30°C / min, hold for 10-25 min;

[0038] Inlet temperature: 200-210℃;

[0039] Column flow rate: 6-10mL / min, helium;

[0040] Air flow rate: 350-500mL / min;

[0041] Hydrogen flow rate: 30-45mL / min;

[0042] Thermal conductivity detector TCD reference flow rate: 25-40mL / min.

[0043] Preferably, in step (3), the gas chromatography conditions are:

[0044] Chromatographic column: HP-PLOT Al2O3 column, 50m×0.53mm×15μm;

[0045] Column temperature program: initial temperature 40 °C, hold for 8 min, increase to 175 °C at a rate of 20 °C / min, hold for 20 min;

[0046] Inlet temperature: 200°C;

[0047] Column flow rate: 8 mL / min, helium;

[0048] Air flow rate: 400mL / min;

[0049] Hydrogen flow rate: 40mL / min;

[0050] Thermal conductivity detector TCD reference flow rate: 30mL / min.

[0051] In other embodiments, the deviation between the representative component concentration obtained in step (3) and the concentration obtained in step (1) is less than 1%.

[0052] In other embodiments, in step (4), the corresponding relationship is: TVOCs concentration = n × VOCs; wherein n> 1. To ensure the accuracy and reliability of the corresponding relationship, the TVOCs concentration and VOCs concentration at least three time points are measured to calculate the corresponding relationship between the two.

[0053] In other embodiments, in step (5), the deviation between the TVOCs concentration obtained by theoretical calculation and the TVOCs concentration measured in step (1) is less than 2%.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] The present invention provides a method for selecting a single representative component by using Suma tank sampling / gas chromatography-mass spectrometry, detecting the concentration of the component by using a gas chromatograph, obtaining a corresponding relationship between the component and the accurate TVOCs concentration measured by the gas chromatography-mass spectrometry, and obtaining the TVOCs concentration by simple calculation; the method utilizes the stable and economical characteristics of the gas chromatography, reduces the TVOCs monitoring cost, improves the convenience of obtaining the TVOCs concentration, can be conveniently used for daily monitoring of the TVOCs concentration of oil field processing stations with uninterrupted and stable emissions, makes up for the shortcomings of the existing gas chromatography-mass spectrometry method, that is, the analysis cost is high and cannot be used for daily detection, controls the conditions of the gas chromatography and mass spectrometry, and makes the test results have higher accuracy.

[0056] Specific embodiment

[0057] The following non-limiting examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. The following content is merely an exemplary description of the scope of protection claimed, and those skilled in the art can make various changes and modifications to the invention according to the disclosed content, which should also fall within the scope of protection claimed.

[0058] The present invention is further described below by way of specific examples. Unless otherwise specified, the various chemical reagents used in the examples of the present invention are obtained through conventional commercial channels.

[0059] Example 1

[0060] This embodiment provides a method for measuring the total volatile organic compound concentration of an oil field processing station using gas chromatography, comprising the following steps:

[0061] (1) Using Suma tank sampling / gas chromatography-mass spectrometry, the volatile organic compound composition spectrum in the exhaust gas of the target emission source at three times was measured to obtain the concentration of each VOCs and TVOCs.

[0062] The sampling steps of the Suma tank include: cleaning the Suma tank with high-purity nitrogen, evacuating to a vacuum degree of <10Pa, performing instantaneous sampling, pre-concentrating with a three-stage cold trap, and performing gas chromatography determination after thermal analysis. The conditions of the three-stage cold trap are: first-stage cold trap: capturing temperature: -150°C; analysis temperature: 10°C; valve temperature: 120°C; baking temperature: 160°C; second-stage cold trap: capturing temperature: -150°C; analysis temperature: 200°C; baking temperature: 220°C; third-stage cold trap: focusing temperature: -160°C; baking temperature: 180°C; gas chromatography transmission line temperature: 120°C.

[0063] Preparation of mixed standard gas: dilute the mixed gas consisting of n-butane, propane, isopentane, isobutane, n-pentane, carbon disulfide, ethane, 2-methylpentane, dichlorodifluoromethane, methylcyclohexane, cyclohexane, methylcyclopentane, n-heptane, n-octane, n-nonane, decane, undecane, dodecane, o-xylene, m-xylene and p-xylene with high-purity nitrogen to 0.5-5.0 nmol·mol -1 Mixed standard gas.

[0064] The gas chromatography conditions were:

[0065] Chromatographic column: TG-5MS gas chromatography column, 60m×0.25mm×1.0μm;

[0066] Column temperature program: initial temperature 40 °C, hold for 2 min, increase to 210 °C at a rate of 4 °C / min, hold for 6 min;

[0067] Inlet temperature: 200°C;

[0068] Carrier gas: helium;

[0069] The column flow rate was 1 mL / min and the split ratio was 20:1.

[0070] The mass spectrometry conditions were: EI ionization source, ionization energy 70 eV, ion source temperature 230 °C, and transfer line temperature: 220 °C.

[0071] The results are shown in Table 1. Taking a certain thin oil treatment station as an example, the main VOCs of this thin oil treatment station are alkanes, among which n-butane has the highest content.

[0072] Table 1

[0073]

[0074] (2) Selecting the component with the highest content, n-butane, as the representative component of the treatment station;

[0075] (3) Determine the concentration of n-butane in the exhaust gas of the target emission source by gas chromatography;

[0076] The gas chromatography conditions were:

[0077] Chromatographic column: HP-PLOT Al2O3 column, 50m×0.53mm×15μm;

[0078] Column temperature program: initial temperature 40 °C, hold for 8 min, increase to 175 °C at a rate of 20 °C / min, hold for 20 min;

[0079] Inlet temperature: 200 °C, column flow rate: 8 mL / min, He;

[0080] Air flow rate: 400mL / min;

[0081] Hydrogen flow rate: 40mL / min;

[0082] Thermal conductivity detector TCD reference flow rate: 30mL / min.

[0083] The n-butane concentration was compared with the n-butane concentration measured by Suma tank sampling / gas chromatography-mass spectrometry in step (1) (as shown in Table 2 below). The results showed that the relative deviation of the n-butane concentration in the same sample detected by using n-butane standard gas and the n-butane concentration obtained by Suma tank sampling / gas chromatography-mass spectrometry was less than 1%, indicating that the n-butane concentrations detected by the two methods met the requirements;

[0084] Table 2

[0085]

[0086] (4) Analyze and form a corresponding relationship between the n-butane concentration obtained in step (3) and the TVOCs concentration; as shown in Table 3 below;

[0087] Table 3

[0088]

[0089] According to the data in Table 3, the deviations between the calculated values ​​and the measured values ​​at the three times are all less than 2%, indicating that the concentrations of n-butane detected by the two methods meet the requirements, and the TVOCs concentration is 5.09 times that of n-butane. Therefore, the corresponding relationship between the VOCs concentration and the TVOCs concentration is determined as follows:

[0090] TVOCs concentration = 5.09 × VOCs concentration;

[0091] (5) At other time points, the n-butane concentration is measured by gas chromatography, and the TVOCs concentration is obtained by theoretical calculation based on the corresponding relationship obtained in step (4), and compared with the Suma tank sampling / gas chromatography-mass spectrometry method.

[0092] The results are shown in Table 4.

[0093] Table 4

[0094] <![CDATA[Concentration (μg / m 3 )]]> Day 4 Day 5 Day 6 n-Butane concentration (gas chromatography) 386.5 373.2 407.5 TVOCs (calculation) 1967.3 1899.6 2074.2 TVOCs (Summa tank sampling / gas chromatography-mass spectrometry) 1904.6 1868.9 2023.1 Relative deviation % 1.62 0.81 1.25

[0095] It can be seen from the results in Table 4 that the deviations between the TVOCs concentration calculated based on the n-butane concentration and the TVOCs concentration after measuring the n-butane concentration at three times by chromatography and the TVOCs concentration measured by Suma tank sampling / gas chromatography-mass spectrometry are less than 2%, indicating that the method provided by the present invention is accurate and reliable.

[0096] Example 2

[0097] This embodiment provides another method for measuring the total volatile organic compound concentration of an oil field processing station using gas chromatography, and the steps are basically the same as those in the embodiment, except that, in this embodiment, the gas chromatography conditions in step (1) are:

[0098] Chromatographic column: TG-5MS gas chromatography column, 60m×0.25mm×1.0μm;

[0099] Column temperature program: initial temperature 38 °C, hold for 5 min, increase to 200 °C at a rate of 3 °C / min, hold for 5 min;

[0100] Inlet temperature: 200°C;

[0101] Carrier gas: helium;

[0102] Column flow rate 1 mL / min, split ratio 10:1;

[0103] The mass spectrometry conditions in step (1) are:

[0104] EI ionization source, ionization energy 70 eV, ion source temperature 220 ° C, transfer line temperature: 220 ° C;

[0105] The gas chromatography conditions in step (3) are:

[0106] Chromatographic column: HP-PLOT Al2O3 column, 50m×0.53mm×15μm;

[0107] Column temperature program: initial temperature 30 °C, hold for 6 min, increase to 170 °C at a rate of 15 °C / min, hold for 10 min;

[0108] Inlet temperature: 200°C;

[0109] Column flow rate: 6 mL / min, He;

[0110] Air flow rate: 400mL / min,

[0111] Hydrogen flow rate: 40mL / min;

[0112] Thermal conductivity detector TCD reference flow rate: 30mL / min.

[0113] The results of this example are shown in Tables 5 and 6 below.

[0114] Table 5

[0115]

[0116]

[0117] Table 6

[0118] <![CDATA[Concentration (μg / m 3 )]]> Day 4 Day 5 Day 6 n-Butane (gas chromatography) 360.8 353.7 366.1 TVOCs (calculation) 1800.4 1765.0 1826.8 TVOCs (Summa tank sampling / gas chromatography-mass spectrometry) 1767.9 1727.3 1778.1 Relative deviation % 0.91 1.08 1.35

[0119] Example 3

[0120] This embodiment provides another method for measuring the total volatile organic compound concentration of an oil field processing station using gas chromatography, and the steps are basically the same as those in the embodiment, except that, in this embodiment, the gas chromatography conditions in step (1) are:

[0121] Chromatographic column: TG-5MS gas chromatography column, 60m×0.25mm×1.0μm;

[0122] Column temperature program: initial temperature 45 °C, hold for 5 min, increase to 220 °C at a rate of 8 °C / min, hold for 8 min;

[0123] Inlet temperature: 220°C;

[0124] Carrier gas: helium;

[0125] Column flow rate 1 mL / min, split ratio 20:1;

[0126] The mass spectrometry conditions in step (1) are:

[0127] EI ionization source, ionization energy 70 eV, ion source temperature 240 ° C, transfer line temperature: 230 ° C;

[0128] The gas chromatography conditions in step (3) are:

[0129] Chromatographic column: HP-PLOT Al2O3 column, 50m×0.53mm×15μm;

[0130] Column temperature program: initial temperature 45 °C, hold for 10 min, increase to 180 °C at a rate of 30 °C / min, hold for 25 min;

[0131] Inlet temperature: 210°C;

[0132] Column flow rate: 10 mL / min, He;

[0133] Air flow rate: 400mL / min;

[0134] Hydrogen flow rate: 40mL / min;

[0135] Thermal conductivity detector TCD reference flow rate: 30mL / min.

[0136] The results of this example are shown in Tables 7 and 8 below.

[0137] Table 7

[0138]

[0139] Table 8

[0140] <![CDATA[Concentration (μg / m 3 )]]> Day 4 Day 5 Day 6 n-Butane (gas chromatography) 376.5 378.9 390.6 TVOCs (calculation) 1893.8 1905.9 1964.7 TVOCs (Summa tank sampling / gas chromatography-mass spectrometry) 1863.8 1845.7 1913.7 Relative deviation % 0.80 1.60 1.31

[0141] Example 4

[0142] This embodiment provides another method for determining the total volatile organic compound concentration of an oil field processing station using gas chromatography, and the steps are basically the same as those in the embodiment, except that, in this embodiment, the chromatographic column in step (3) is a Porapak-Q chromatographic column filled with 13X molecular sieve.

[0143] The results of this example are shown in Tables 9 and 10 below.

[0144] Table 9

[0145]

[0146] Table 10

[0147] <![CDATA[Concentration (μg / m 3 )]]> Day 4 Day 5 Day 6 n-Butane (gas chromatography) 392.5 382.6 403.2 TVOCs (calculation) 1939.0 1890.0 1991.8 TVOCs (Summa tank sampling / gas chromatography-mass spectrometry) 1904.6 1868.9 2023.1 Relative deviation 0.89 0.56 0.78

[0148] Comparative Example 1

[0149] This comparative example provides another method for determining the concentration of total volatile organic compounds (TVOCs) in an oilfield processing station, and the steps are basically the same as those in the embodiment, except that in this comparative example, the gas chromatography conditions in step (1) are:

[0150] Chromatographic column: TG-5MS gas chromatography column, 60m×0.25mm×1.0μm;

[0151] Column temperature program: initial temperature 30 °C, hold for 8 min, increase to 230 °C at a rate of 10 °C / min, hold for 10 min;

[0152] Inlet temperature: 230°C,

[0153] Carrier gas: helium;

[0154] Column flow rate 1 mL / min, split ratio 10:1;

[0155] The mass spectrometry conditions in step (1) are:

[0156] EI ionization source, ionization energy 70 eV, ion source temperature 230 °C, transfer line temperature: 230 °C.

[0157] The results of this example are shown in Tables 11 and 12 below.

[0158] Table 11

[0159]

[0160] Table 12

[0161] <![CDATA[Concentration (μg / m 3 )]]> Day 4 Day 5 Day 6 n-Butane (gas chromatography) 386.5 373.2 407.5 TVOCs (calculation) 1940.2 1873.5 2045.7 TVOCs (Summa tank sampling / gas chromatography-mass spectrometry) 2136.1 2117.6 2197.5 Relative deviation % 6.12 6.12 3.58

[0162] Comparative Example 2

[0163] This comparative example provides another method for determining the total volatile organic compound concentration of an oilfield processing station by gas chromatography, and the steps are basically the same as those in the embodiment, except that in this comparative example, the chromatographic conditions in step (3) are:

[0164] Chromatographic column: HP-PLOT Al2O3 column, 50m×0.53mm×15μm; bonded Porapak-Q column and 13X molecular sieve;

[0165] Column temperature program: initial temperature 30 °C, hold for 2 min, increase to 200 °C at a rate of 10 °C / min, hold for 5 min;

[0166] Inlet temperature: 220°C,

[0167] Column flow rate: 8 mL / min, He;

[0168] Air flow rate: 400mL / min,

[0169] Hydrogen flow rate: 40mL / min;

[0170] Thermal conductivity detector TCD reference flow rate: 30mL / min.

[0171] The results of this example are shown in Tables 13 and 14 below.

[0172] Table 13

[0173]

[0174] Table 14

[0175] <![CDATA[Concentration (μg / m 3 )]]> Day 4 Day 5 Day 6 n-Butane (gas chromatography) 437.9 422.8 447.1 TVOCs (calculation) 2163.2 2088.6 2208.7 TVOCs (Summa tank sampling / gas chromatography-mass spectrometry) 1904.6 1868.9 2023.1 Relative deviation % 6.36 5.55 4.39

[0176] As shown in the results of Table 5-14, the relative deviation between the calculated value of TVOCs obtained by the method described in the embodiment of the present invention and the actual measured value by Suma tank sampling / gas chromatography-mass spectrometry is small, the accuracy is high, and it is significantly lower than the comparative example. It can be seen that the chromatographic conditions and mass spectrometry conditions affect the accuracy of the determination results of volatile organic matter in the target emission source, thereby affecting the accuracy of the present invention's calculation of the total volatile organic matter concentration of the oilfield processing station by gas chromatography detection of a single component;

[0177] The conventional operations in the operating steps of the present invention are well known to those skilled in the art and will not be described in detail here. The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention, and the scope of patent protection of the present invention should be defined by the claims.

Claims

1. A method for measuring the total volatile organic compound concentration of an oil field processing station using gas chromatography, characterized in that: The following steps are involved: (1) Summa tank sampling / gas chromatography-mass spectrometry is used to measure the composition spectrum of the exhaust gas from the target emission source to obtain the concentration of each VOCs and TVOCs; (2) analyzing the component spectrum obtained in step (1) and selecting a VOCs component as a representative component; (3) detecting the concentration of the representative components selected in step (2) by gas chromatography; (4) analyzing the concentration obtained in step (3) and the TVOCs concentration obtained in step (1) to obtain a corresponding relationship between the VOCs concentration and the TVOCs concentration; (5) At other time points, the concentration of representative components is detected by gas chromatography, and the TVOCs concentration is obtained by theoretical calculation based on the corresponding relationship obtained in step (4).

2. The method according to claim 1, characterized in that In step (1), the gas chromatography conditions are: Chromatographic column: polysiloxane gas chromatography column; Column heating program: initial temperature 38-45°C, hold for 2-5 min, increase to 200-220°C at a rate of 3-8°C / min, hold for 5-8 min; Inlet temperature: 200-220℃; Carrier gas: helium; Column flow rate 1-1.5mL / min, split ratio 15-20:

1.

3. The method according to claim 2, characterized in that In step (1), the gas chromatography conditions are: Chromatographic column: TG-5MS gas chromatography column; Column temperature program: initial temperature 40 °C, hold for 2 min, increase to 210 °C at a rate of 4 °C / min, hold for 6 min; Inlet temperature: 200°C; Carrier gas: helium; The column flow rate was 1 mL / min and the split ratio was 20:

1.

4. The method according to claim 1, characterized in that: In step (1), the mass spectrometry conditions are: EI ionization source, ionization energy 70 eV, ion source temperature 220-240°C, and transmission line temperature: 220-230°C.

5. The method according to claim 4, characterized in that In step (1), the mass spectrometry conditions are: EI ionization source, ionization energy 70 eV, ion source temperature 230°C, and transmission line temperature: 220°C.

6. The method according to claim 1, characterized in that In step (2), the selected VOCs components are alkanes.

7. The method according to claim 6, characterized in that The selected VOCs component is the alkane with the highest concentration.

8. The method according to claim 1, characterized in that In step (3), the gas chromatography conditions are: Chromatographic column: HP-PLOT Al2O3 column, or Porapak-Q column filled with 13X molecular sieve; Column heating program: initial temperature 30-45°C, hold for 6-10 min, heat to 170-180°C at a rate of 15-30°C / min, hold for 10-25 min; Inlet temperature: 200-210℃; Column flow rate: 6-10mL / min, helium; Air flow rate: 350-500mL / min; hydrogen Flow rate: 30-45mL / min; Thermal conductivity detector TCD reference flow rate: 25-40mL / min.

9. The method according to claim 8, characterized in that In step (3), the gas chromatography conditions are: Chromatographic column: HP-PLOT Al2O3 column; Column temperature program: initial temperature 40 °C, hold for 8 min, increase to 175 °C at a rate of 20 °C / min, hold for 20 min; Inlet temperature: 200°C; Column flow rate: 8 mL / min, helium; Air flow rate: 400mL / min; Hydrogen flow rate: 40mL / min; Thermal conductivity detector TCD reference flow rate: 30mL / min.

10. The method according to claim 1, characterized in that In step (4), the corresponding relationship is: TVOCs concentration = n×VOCs; wherein n>1.

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