Test device and method for measuring residual gas of coal sample based on GC double-column method

Abstract

The invention discloses a test device and method for measuring residual gas of a coal sample based on a GC double-column method. The device comprises a high-purity hydrogen steel cylinder, a high-purity helium steel cylinder, a vacuum pump containing a vacuum gauge, a computer, and a liquid sealing coal sample tank, a sleeve type gas storage device and a gas chromatograph which are connected in sequence, a first heating thermocouple, an electromagnetic valve and a spherical grinding machine are arranged in the lower layer of the liquid sealing coal sample tank; a pressure gauge, a thermometer and a first flow sensor which are used for measuring gas are arranged at an outlet of the capacity-controllable sleeve type gas storage device; the gas chromatograph is provided with a sampling device, a double chromatographic column device, a double thermal conductivity detector, a second flow sensor and a temperature sensor which are connected in sequence; and a heating device is also arranged in the box body. According to the invention, double gas chromatographic columns and double thermal conductivity detectors are selected, the separation effect and detection effect of each component gas are more excellent, and the subsequently measured wave peak value and wave width are more accurate.

Description

Technical Field

[0001] The invention relates to the field of coal sample gas desorption amount determination, in particular to a test device and method for measuring residual gas in coal samples based on a GC double-column method. Background Art

[0002] The widely used gas desorption instrument mainly uses the drainage method to determine the gas desorption amount and desorption rate. The gas desorbed in the coal sample tank discharges the water in the desorption instrument measuring cylinder, and the desorption amount is obtained by the water column height difference. At the same time, the water column height difference per unit time is used to characterize the gas desorption rate. However, when the desorption instrument measures the desorption rate, it is easily affected by the water temperature and the saturated vapor pressure of water, causing errors, and it is limited by manual readings and cannot quickly and accurately obtain the desorption amount and desorption rate. The commonly used gas chromatograph quantitative analysis methods are the internal standard method and the external standard method, which require the entry and measurement of secondary sample gas, and the measurement steps are relatively cumbersome. Summary of the invention

[0003] In view of the problems existing in the above-mentioned prior art, the present invention discloses an experimental device and method for measuring residual gas in coal samples based on GC (Gas Chromatograph) double-column method, which has the characteristics of simple operation and accurate test results.

[0004] The invention discloses a test device for measuring residual gas in coal samples based on a GC double-column method, comprising: a high-purity hydrogen cylinder, a high-purity helium cylinder, a vacuum pump with a vacuum gauge, a computer, and a liquid-sealed coal sample tank, a sleeve-type gas storage device, and a gas chromatograph connected in sequence;

[0005] Among them, the high-purity helium cylinder and the high-purity helium cylinder are connected to the liquid-sealed coal sample tank through a vacuum pump, and a gas flow meter is provided between the vacuum pump and the liquid-sealed coal sample tank;

[0006] The liquid sealed coal sample tank includes two layers, the upper layer is used to place the sealing liquid for blocking the flow of gas, and the lower layer for placing the coal sample is provided with the first temperature-raising thermocouple, the electromagnetic valve, and the ball grinder;

[0007] The outlet of the capacity-controllable sleeve-type gas storage device is provided with a pressure gauge, a thermometer, and a first flow sensor for measuring the gas;

[0008] The gas chromatograph is provided with: a sampling device for connecting a sleeve-type gas storage device, a double chromatographic column device, a thermal conductivity detector I, a thermal conductivity detector II, a second flow sensor, and a temperature sensor, which are connected in sequence; and a heating device is also provided in the gas chromatograph;

[0009] The computer is electrically connected with the first temperature-raising thermocouple, the electromagnetic valve, the pressure gauge, the thermometer, the first flow sensor, the sample introduction device, the thermal conductivity detector I, the thermal conductivity detector II, the second flow sensor, the temperature sensor and the heating device.

[0010] Furthermore, the device also includes an outlet pipeline, a 4L high-purity helium cylinder and a high-purity helium cylinder connected to one end of the outlet pipeline, and the other end connected to the liquid-sealed coal sample tank; a check valve is also provided on the outlet pipeline;

[0011] A glass tube for adding sealing liquid is installed on the upper side of the liquid sealed coal sample tank; the main components of the sealing liquid are hydroxyethyl cellulose, polyacrylamide and potassium chloride.

[0012] Furthermore, the sample injection device comprises:

[0013] Flow control valve, controlled by computer using EPC carrier gas system;

[0014] A packed column inlet is used to realize the flow splitting of the detection gas;

[0015] The gas sample injection valve is used to ensure the accurate quantitative sampling of the test gas.

[0016] Furthermore, the dual chromatographic column device comprises: a gas chromatographic column I and a gas chromatographic column II connected in parallel, wherein the gas chromatographic column I connected to the sample injection device has an inner diameter of Φ0.25 mm, a column length of 2 m, and a column filling particle size of 40-60 mesh molecular sieve; the gas chromatographic column II connected to the thermal conductivity detector I has an inner diameter of Φ0.5 mm, a column length of 4 m, and a column filling material of β-β / oxydipropionitrile, dibutyl phthalate, and 40-60 mesh 6201 support in a mixing ratio of 20:40:10;

[0017] The parameters of the thermal conductivity detector I and the thermal conductivity detector II are as follows: sensitivity S ≥ 5000mV·mL / mL, noise ≤ 0.1mv, and stability ≤ 0.3mv / 30min.

[0018] Furthermore, the gas chromatograph also includes a gas chromatograph column housing, which is divided into two layers, an inner layer and an outer layer, the gap between the inner layer and the outer layer is filled with heat insulating cotton, and the outer layer is made of stainless steel metal;

[0019] The heating device comprises: a second temperature-raising thermocouple, a third temperature-raising thermocouple, a fourth temperature-raising thermocouple and a fifth temperature-raising thermocouple arranged in the inner layer of the gas chromatograph box, which are respectively used to realize the precise heating of gas chromatograph column I, gas chromatograph column II, thermal conductivity detector I and thermal conductivity detector II.

[0020] Furthermore, the computer uses the PID heating system to control the temperature of the chromatograph box to 80°C, the temperature of the gas chromatography column I and the gas chromatography column II to 120°C, and the temperature of the thermal conductivity detector I and the thermal conductivity detector II to 100°C through the second heating thermocouple, the third heating thermocouple, the fourth heating thermocouple, and the fifth heating thermocouple.

[0021] Furthermore, the sleeve-type gas storage device includes: a gas storage box, a compressible sleeve, and a transmission device; wherein the gas storage box is a closed rigid container made of acrylic plate, which is used to store coal sample gas to ensure that a sufficient amount of desorbed gas enters the chromatograph box for analysis; the computer is electrically connected to the transmission device, and is used to control the compression amount through the computer's PLC system.

[0022] Furthermore, the computer is equipped with an information data processing system, a PLC control system, an EPC control system, and a PID heating system. The information data processing system can collect, store, process, and send data from each sensor, as well as measure the retention time and peak area of ​​the chromatographic peak. The PLC control system controls the ball grinder, the compressible sleeve, the transmission device, the flow control valve, and the gas sample injection valve through the electromagnetic valve. In the EPC control system, the voltage signals of the flow meter and the pressure sensor can be sent to the PLC control system after digital-to-analog conversion to drive and adjust the flow control valve to obtain a stable carrier gas flow and pressure.

[0023] The present invention also discloses a test method for measuring residual gas in coal samples based on a GC double-column method, comprising:

[0024] Step 1: Open the high-purity hydrogen cylinder to check the air tightness of the device;

[0025] Step 2: start the ball grinder through the computer to grind the coal sample in the liquid sealed coal sample tank, and control the first temperature rising thermocouple to heat;

[0026] Step 3: The desorbed gas enters the gas storage box for collection and storage. The computer controls the compression amount of the compressible sleeve to select the appropriate gas storage capacity.

[0027] Step 4: Open the high-purity helium cylinder, control the helium gas to flow into the sleeve-type gas storage device at a stable pressure and constant speed, and mix with the gas therein to obtain a carrier gas flow, control the carrier gas flow to pass through the pressure gauge, the thermometer, the first flow sensor, and the sampling device, and then enter the inner layer of the gas chromatograph to reach the double chromatographic column device to separate the components of the gas, and then the carrier gas flow is detected and sampled by the thermal conductivity detector I and the thermal conductivity detector II and the signal is output to the computer for conversion into chromatogram sampling;

[0028] Step 5: The computer calculates the relative percentage concentration of each component separated on the gas chromatography column I based on the chromatogram sampling;

[0029] Step 6: The computer calculates the mixed peak correction factor based on the data obtained in step 5;

[0030] Step 7: Calculate the area occupied by each component in the mixed peak based on the area of ​​each component gas mixed peak, the relative concentration of each component gas, and the mixed peak correction factor.

[0031] Step 8: According to the calculation method of steps 5 to 7 above, after repeatedly calculating the relative percentage concentration of each component separated on gas chromatography column I and gas chromatography column II, the data obtained from the two are normalized to finally obtain the percentage concentration of each component in the coal sample.

[0032] Further, including:

[0033] Open the high-purity hydrogen cylinder, introduce hydrogen gas, and observe whether the flow meter reading is stable. If the reading is stable, the air tightness of the device is good and subsequent operations can be performed. Otherwise, the air tightness of the device needs to be checked again. After checking the air tightness of the device, close the high-purity hydrogen cylinder, turn on the vacuum pump to perform vacuum operation, and observe whether the mercury surface of the vacuum gauge is stable. After it is stable, continue to vacuum until the vacuum gauge reading reaches 10Kpa.

[0034] The step 2 comprises:

[0035] For the liquid sealed coal sample tank containing coal sample, the solenoid valve is controlled by the computer PLC control system to start the ball grinder to grind the coal sample. The computer runs the temperature PID control system to control the first temperature-raising thermocouple to heat the lower layer of the coal sample tank to 95°C. At this time, the residual gas in the coal sample is desorbed in this state.

[0036] The step three comprises:

[0037] The desorbed gas enters the gas storage box through the stainless steel gas pipe for collection and storage. The PLC control system controls the compression amount of the compressible sleeve through the transmission device, thereby selecting the appropriate gas storage capacity.

[0038] The step 4 comprises:

[0039] Open the high-purity helium cylinder, and the helium gas flows out of the high-purity helium cylinder. The computer uses the EPC control system to select a stable pressure and a constant speed to flow into the sleeve-type gas storage device, and is mixed with the previously stored gas to form a carrier gas flow containing various gas components. The carrier gas flow then passes through the pressure gauge, the thermometer, the first flow sensor, and the flow control valve to enter the inner layer of the gas chromatograph, and then passes through the filling column injection port and the gas sample injection valve in turn to reach the gas chromatography column I and the gas chromatography column II to separate the various gas components. The carrier gas flow containing the various gas components separated by the gas chromatography column I and the gas chromatography column II is detected and sampled by the thermal conductivity detector I and the thermal conductivity detector II to generate an output signal. The output signals of the thermal conductivity detector I and the thermal conductivity detector II are converted by the computer into chromatogram sampling.

[0040] Furthermore, the step 5 comprises: after sampling, the computer measures and stores the parameters including the peak area, peak height and half slit width of the measured chromatogram data; and separates the relative percentage concentration of each component on the chromatographic column I, which is expressed as follows:

[0041]

[0042] Where: q i is the relative percentage concentration of each component, unit %; S i is the peak area of ​​a component, S i =h i *b i ;h i is the peak height, in mm; b i is the half-slit width, in mm; k i is the component signal attenuation multiple; a i is the component correction factor;

[0043] The step six further includes:

[0044] The mixed peak correction factor is calculated by the following expression:

[0045]

[0046] Where: 混 is the mixed peak correction factor; σ i is the correction factor for each component gas; q i is the concentration of each component gas;

[0047] The step 7 further comprises: calculating the area occupied by each component in the mixed peak by the following expression:

[0048]

[0049] Where: S 混is the area occupied by the mixed peak; S i is the area of ​​the mixed peak of each component gas; q i is the relative concentration of each component gas.

[0050] The present invention has at least the following beneficial effects:

[0051] (1) The present invention realizes the advantages of both internal and external standard methods of gas chromatograph by using normalization method, does not require sample pretreatment, and greatly simplifies the gas content operation steps of residual gas content detection.

[0052] (2) The coal sample tank of the present invention is sealed with liquid, and the sealed liquid used can hinder the flow of gas, reduce gas leakage of coal sample gas, improve gas desorption effect, and enhance the measurement accuracy of gas desorption concentration.

[0053] (3) The present invention uses a sleeve-type gas storage device to measure the volume of residual gas, thereby avoiding errors caused by manual measurement when collecting gas volume using the drainage gas collection method.

[0054] (4) The present invention selects dual gas chromatography columns and dual thermal conductivity detectors, and the separation effect and detection effect of each component gas are more excellent, and the peak value and wave width measured subsequently are more accurate. At the same time, the two-column normalization method can save costs, improve detection accuracy, shorten analysis time, simplify operation and calculation, and is targeted for gas detection.

[0055] (5) The gas injection system selects the EPC system, which can achieve stable, accurate and controllable flow rate of the injected gas components.

[0056] Other beneficial effects of the present invention will be described in detail in the specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0058] Figure 1 It is a structural principle diagram of a test device for measuring residual gas in coal samples based on a GC double-column method disclosed in a preferred embodiment of the present invention.

[0059] Among them, 1 is a high-purity hydrogen cylinder; 2 is a high-purity helium cylinder; 3 is a vacuum pump; 4 is a vacuum gauge; 5 is a gas flow meter; 6 is a check valve; 7 is a liquid-sealed coal sample tank; 8 is a ball grinder; 9 is a first temperature-raising thermocouple; 10 is a solenoid valve; 11 is a glass tube; 12 is a gas storage box; 13 is a compressible sleeve; 14 is a transmission device; 15 is a pressure gauge; 16 is a thermometer; 17 is a first flow sensor; 18 is a gas chromatography column box; 19 is a flow control valve; 20 is a packing column injection port; 21 is a gas sample injection valve; 22 is a second temperature-raising thermocouple; 23 is a third temperature-raising thermocouple; 24 is a gas chromatography column I; 25 is a gas chromatography column II; 26 is a thermal conductivity detector I; 27 is a thermal conductivity detector II; 28 is a fourth temperature-raising thermocouple; 29 is a fifth temperature-raising thermocouple; 30 is a second flow sensor; 31 is a temperature sensor. DETAILED DESCRIPTION

[0060] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0061] Embodiment 1

[0062] like Figure 1 As shown, this embodiment discloses a test device for measuring residual gas in coal samples based on the GC double-column method. The vacuum degassing system in the device includes: a high-purity hydrogen cylinder 1 with a volume of 4L, and a high-purity helium cylinder 2 with a volume of 4L. The high-purity hydrogen cylinder 1 and the high-purity helium cylinder 2 are connected to a vacuum pump 3, a gas flow meter 5, and a check valve 6 in sequence through a stainless steel outlet pipeline. The vacuum pump 3 contains a vacuum gauge 4.

[0063] The adsorption-desorption system in the device includes: a liquid-sealed coal sample tank 7, a spherical grinder 8, a first temperature-raising thermocouple 9, a solenoid valve 10, and a glass tube 11. The liquid-sealed coal sample tank 7 is divided into two layers, the upper layer is equipped with a glass tube 11 for adding a sealing liquid, and the main components of the sealing liquid are hydroxyethyl cellulose, polyacrylamide, and potassium chloride. The sealing liquid can hinder the flow of gas, reduce gas leakage of coal sample gas, and improve the gas desorption effect. The lower layer is mainly used to place coal samples, and the first temperature-raising thermocouple 9 and the solenoid valve 10 are installed inside for temperature control and braking of the spherical grinder 8.

[0064] The sleeve type gas storage device comprises a gas storage box 12, a compressible sleeve 13, a transmission device 14, a pressure gauge 15, a thermometer 16, and a first flow sensor 17. The gas storage box 12 is a closed rigid container made of acrylic plate, which is used to store coal sample gas to ensure that a sufficient amount of gas desorption gas enters the chromatograph box 18 for analysis. The PLC system controls the compression amount of the compressible sleeve 13 through the transmission device 14, thereby achieving the purpose of controllable gas measurement.

[0065] The core components of the gas chromatograph in the device include: a gas chromatographic column housing 18, a flow control valve 19, a filling column injection port 20, a gas sample injection valve 21, a gas chromatographic column I 24, a gas chromatographic column II 25, a thermal conductivity detector I 26, a thermal conductivity detector II 27, a second flow sensor 30, and a temperature sensor 31. The gas chromatographic column housing 18 is divided into two layers, the inner layer and the outer layer. The gap between the inner layer and the outer layer is filled with heat insulation cotton, the outer layer is made of stainless steel metal, and the inner layer is equipped with a second temperature-raising thermocouple 22, a third temperature-raising thermocouple 23, a fourth temperature-raising thermocouple 28, and a fifth temperature-raising thermocouple 29, which are respectively used to realize the precise program temperature rise of the gas chromatographic column I 24, the gas chromatographic column II 25, the thermal conductivity detector I 26, and the thermal conductivity detector II 27. The computer uses the EPC carrier gas system to control the flow control valve 19, the filling column injection port 20 is used to realize the diversion of the detection gas, and the gas sample injection valve 21 is used to ensure the accurate quantitativeness of the detection gas injection.

[0066] The gas chromatography column I 24 and the gas chromatography column II 25 are connected in parallel. For the gas chromatography column I, the column inner diameter is Φ0.25 mm, the column length is 2 m, and the particle size of the filling in the column is 40-60 mesh molecular sieve; for the gas chromatography column II 25, the column inner diameter is Φ0.5 mm, the column length is 4 m, and the mixing ratio of the filling material in the column is 20:40:10, β-β / oxydipropionitrile, dibutyl phthalate, and 6201 support (40-60 mesh). The gas sample injection valve 21 ensures the accurate quantitativeness of the detection gas injection. The parameters of the thermal conductivity detector I 26 and the thermal conductivity detector II 27 are as follows: sensitivity S ≥ 5000 mV·mL / mL (volume sensitivity), noise ≤ 0.1 mv (peak to peak), stability ≤ 0.3 mv / 30min. The second flow sensor 30 and the temperature sensor 31 are connected to the thermal conductivity detector I 26 and the thermal conductivity detector II 27 .

[0067] The computer in the device is equipped with an information data processing system, a PLC control system, an EPC control system, and a PID heating system. The information data processing system can collect, store, process, and send data from each sensor, as well as measure the retention time and peak area of ​​the chromatographic peak. The PLC control system controls the ball grinder 8, the compressible sleeve 13 transmission device 14, the flow control valve 19, and the gas sample injection valve 21 through the solenoid valve 10. In the EPC control system, the voltage signal of the corresponding sensor can be sent to the PLC control system after digital-to-analog conversion to drive and adjust the flow control valve 19 to obtain a stable carrier gas flow and pressure. The PID heating system can control the temperature of the chromatographic analyzer box 18 to 80°C, the temperature of the gas chromatographic column I 24 and the gas chromatographic column II 25 to 120°C, and the temperature of the thermal conductivity detector I 26 and the thermal conductivity detector II 27 to 100°C by controlling the second heating thermocouple 22, the third heating thermocouple 23, the fourth heating thermocouple 28, and the fifth heating thermocouple 29.

[0068] The device realizes pipeline connection through a stainless steel gas guide pipeline. Specifically, the stainless steel gas guide pipeline passes through a high-purity hydrogen cylinder 1 and a high-purity helium cylinder 2, a vacuum pump 3, a check valve 6, a liquid-sealed coal sample tank 7, a gas storage box 12 in sequence, passes through a compressible sleeve 13, a transmission device 14 and a pressure gauge 15, a thermometer 16, and a first flow sensor 17, and then enters a gas chromatograph box 18, passes through a flow control valve 19, a filling column injection port 20, a gas sample injection valve 21, a gas chromatography column I 24, a gas chromatography column II 25, a thermal conductivity detector I 26, a thermal conductivity detector II 27, a second flow sensor 30, and a temperature sensor 31 in sequence.

[0069] Embodiment 2

[0070] This embodiment is a gas chromatograph gas relative concentration peak calculation method corresponding to the gas content measurement experimental device using a double-column gas chromatograph described in Example 1, and is specifically described in combination with O2, CH4, and N2:

[0071] Step 1: Check the air tightness of the device, open the high-purity hydrogen cylinder 1, pass hydrogen gas, and observe whether the gas flow meter 5 shows a stable reading. If the reading is stable, the air tightness of the device is good and subsequent operations can be performed. Otherwise, the air tightness of the device needs to be checked again. After checking the air tightness of the device, close the high-purity hydrogen cylinder 1, turn on the vacuum pump to perform vacuum operation, and observe whether the mercury surface of the vacuum gauge 4 is stable. After stabilization, continue to vacuum until the reading of the vacuum gauge 4 reaches 10KPa.

[0072] Step 2: For the liquid sealed coal sample tank 7 containing lump coal samples from a coal mine, the solenoid valve 11 is controlled by the PLC control system to start the spherical grinder 8 to grind the coal sample. The temperature PID control system controls the first temperature rising thermocouple 9 to heat the lower layer of the coal sample tank to 95°C. At this time, the residual gas in the coal sample is desorbed in this state.

[0073] Step 3: The desorbed gas enters the gas storage box 12 through the stainless steel gas pipe for collection and storage. The PLC control system controls the compression amount of the compressible sleeve 13 through the transmission device 14, thereby selecting a suitable gas storage capacity.

[0074] Step 4: Open the high-purity helium cylinder 2, and the helium gas flows out of the high-purity helium cylinder. The EPC control system selects a stable pressure (generally 0.4 MPa) and a constant speed to flow into the sleeve-type gas storage device box 12, and is mixed with the gas gas previously stored in the gas box 12 to form a carrier gas flow containing various components of the gas. The carrier gas flows through the compressible sleeve 13, the transmission device 14, the pressure gauge 15, the thermometer 16, the first flow sensor 17, and the flow control valve 19, and then enters the inner layer of the gas chromatograph. The carrier gas flows through the filling column injection port 20 and the gas sample injection valve 21 in turn to reach the gas chromatography column I 24 and the gas chromatography column II 25 for separation of various components of the gas. The carrier gas flow containing various components of the gas separated by the gas chromatography column I 24 and the gas chromatography column II 25 is detected and sampled by the thermal conductivity detector I 27 and the thermal conductivity detector II 28 to generate an output signal. The output signals of the thermal conductivity detector I 27 and the thermal conductivity detector II 28 are converted into chromatogram samples by a computer.

[0075] Step 5: After sampling, the computer calculates the peak area S of the chromatogram data measured i , peak height h i 、Half seam width b i The relative percentage concentration (q i ) The concentration calculation method is:

[0076]

[0077] Where: q i —Relative percentage concentration of each component, %; S i —Peak area of ​​a component, S i =h i *b i ,h i —Peak height (mm); b i —Half seam width (mm); k i —component signal attenuation multiple; a i—Component correction factor.

[0078] In this embodiment, the following calculation is performed based on the above formula (1):

[0079]

[0080] Step 6: Process the gas content data detected in step 5 by computer, and correct the poor gas detection accuracy by calculating the mixed peak correction factor to obtain the final detection result. The mixed peak correction factor is calculated by the following formula (2):

[0081]

[0082] Where: 混 —mixed peak correction factor; σ i —Correction factor for each component gas; q i —Concentration of each component gas.

[0083] In this embodiment, the following calculation is performed based on the above formula (2):

[0084]

[0085] Step 7: According to the area of ​​the mixed peak S = correction factor σ of the mixed peak 混 × Area S of the mixed peak of each component gas i , calculate the area occupied by each component in the mixed peak according to formula (3).

[0086]

[0087] Where: S 混 —the area occupied by the mixed peak; S i —The area of ​​the mixed peak of each component gas; q i —Relative concentration of each component gas.

[0088] In this embodiment, the following calculation is performed based on the above formula (3):

[0089]

[0090] Step 8: Repeat the calculation of the relative percentage concentration (mixed peak area) of each component separated on the gas chromatography column I 24 and the gas chromatography column II 25 according to the formulas in the above steps 5 to 7, and then normalize the data obtained by the two to finally obtain the percentage concentration of each component in the analysis sample. The normalization method is sometimes also called the percentage method, which directly calculates the normalization by peak area or peak height to obtain the content of the component to be measured. Its characteristic is that it does not require a standard substance and only requires one injection to complete the analysis.

[0091] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A test device for measuring residual gas in coal samples based on GC double-column method, characterized in that: include: High-purity hydrogen cylinder, high-purity helium cylinder, vacuum pump with vacuum gauge, computer, and liquid-sealed coal sample tank, sleeve-type gas storage device, and gas chromatograph connected in sequence; Among them, the high-purity helium cylinder and the high-purity helium cylinder are connected to the liquid-sealed coal sample tank through a vacuum pump, and a gas flow meter is provided between the vacuum pump and the liquid-sealed coal sample tank; The liquid sealed coal sample tank includes two layers, the upper layer is used to place the sealing liquid for blocking the flow of gas, and the lower layer for placing the coal sample is provided with the first temperature-raising thermocouple, the electromagnetic valve, and the ball grinder; The outlet of the capacity-controllable sleeve-type gas storage device is provided with a pressure gauge, a thermometer, and a first flow sensor for measuring the gas; The gas chromatograph is provided with: a sampling device for connecting a sleeve-type gas storage device, a double chromatographic column device, a thermal conductivity detector I, a thermal conductivity detector II, a second flow sensor, and a temperature sensor, which are connected in sequence; and a heating device is also provided in the gas chromatograph; The computer is electrically connected with the first temperature-raising thermocouple, the electromagnetic valve, the pressure gauge, the thermometer, the first flow sensor, the sample introduction device, the thermal conductivity detector I, the thermal conductivity detector II, the second flow sensor, the temperature sensor and the heating device.

2. The test device for measuring residual gas in coal samples based on the GC double-column method according to claim 1 is characterized in that: The device also includes an outlet pipeline, a 4L high-purity helium cylinder and a high-purity helium cylinder connected to one end of the outlet pipeline, and the other end connected to a liquid-sealed coal sample tank; a check valve is also provided on the outlet pipeline; A glass tube for adding sealing liquid is installed on the upper side of the liquid sealed coal sample tank; the main components of the sealing liquid are hydroxyethyl cellulose, polyacrylamide and potassium chloride.

3. The test device for measuring residual gas in coal samples based on the GC double-column method according to claim 2 is characterized in that: The sample introduction device comprises: Flow control valve, controlled by computer using EPC carrier gas system; A packed column inlet is used to realize the flow splitting of the detection gas; The gas sample injection valve is used to ensure the accurate quantitative sampling of the test gas.

4. The test device for measuring residual gas in coal samples based on the GC double-column method according to claim 3 is characterized in that: The double chromatographic column device comprises: a gas chromatographic column I and a gas chromatographic column II connected in parallel, wherein the gas chromatographic column I connected to the sample injection device has an inner diameter of Φ0.25 mm, a column length of 2 m, and a column filling particle size of 40-60 mesh molecular sieve; the gas chromatographic column II connected to the thermal conductivity detector I has an inner diameter of Φ0.5 mm, a column length of 4 m, and a column filling material of β-β / oxydipropionitrile, dibutyl phthalate, and 40-60 mesh 6201 support in a mixing ratio of 20:40:10; The parameters of the thermal conductivity detector I and the thermal conductivity detector II are as follows: sensitivity S ≥ 5000mV·mL / mL, noise ≤ 0.1mv, and stability ≤ 0.3mv / 30min.

5. The test device for measuring residual gas in coal samples based on the GC double-column method according to claim 4 is characterized in that: The gas chromatograph also includes a gas chromatograph column box, which is divided into two layers, an inner layer and an outer layer, the gap between the inner layer and the outer layer is filled with heat insulation cotton, and the outer layer is made of stainless steel metal; The heating device comprises: a second temperature-raising thermocouple, a third temperature-raising thermocouple, a fourth temperature-raising thermocouple and a fifth temperature-raising thermocouple arranged in the inner layer of the gas chromatograph box, which are respectively used to realize the precise heating of gas chromatograph column I, gas chromatograph column II, thermal conductivity detector I and thermal conductivity detector II.

6. The test device for measuring residual gas in coal samples based on the GC double-column method according to claim 5 is characterized in that: The computer uses the PID heating system to control the temperature of the chromatograph box to 80°C, the temperature of gas chromatography columns I and II to 120°C, and the temperature of thermal conductivity detectors I and II to 100°C through the second heating thermocouple, the third heating thermocouple, the fourth heating thermocouple, and the fifth heating thermocouple.

7. The test device for measuring residual gas in coal samples based on GC double-column method according to claim 5, characterized in that: The sleeve-type gas storage device includes: a gas storage box, a compressible sleeve, and a transmission device; wherein the gas storage box is a closed rigid container made of acrylic plate, which is used to store coal sample gas to ensure that a sufficient amount of desorbed gas enters the chromatograph box for analysis; a computer is electrically connected to the transmission device to control the compression amount through the computer's PLC system.

8. A test method for measuring residual gas in coal samples based on GC double-column method, characterized in that: include: Step 1: Open the high-purity hydrogen cylinder to check the air tightness of the device; Step 2: start the ball grinder through the computer to grind the coal sample in the liquid sealed coal sample tank, and control the first temperature rising thermocouple to heat; Step 3: The desorbed gas enters the gas storage box for collection and storage. The computer controls the compression amount of the compressible sleeve to select the appropriate gas storage capacity. Step 4: Open the high-purity helium cylinder, control the helium gas to flow into the sleeve-type gas storage device at a stable pressure and constant speed, and mix with the gas therein to obtain a carrier gas flow, control the carrier gas flow to pass through the pressure gauge, the thermometer, the first flow sensor, and the sampling device, and then enter the inner layer of the gas chromatograph to reach the double chromatographic column device to separate the components of the gas, and then the carrier gas flow is detected and sampled by the thermal conductivity detector I and the thermal conductivity detector II and the signal is output to the computer for conversion into chromatogram sampling; Step 5: The computer calculates the relative percentage concentration of each component separated on the gas chromatography column I based on the chromatogram sampling; Step 6: The computer calculates the mixed peak correction factor based on the data obtained in step 5; Step 7: Calculate the area occupied by each component in the mixed peak based on the area of ​​each component gas mixed peak, the relative concentration of each component gas, and the mixed peak correction factor. Step 8: According to the calculation method of steps 5 to 7 above, after repeatedly calculating the relative percentage concentration of each component separated on gas chromatography column I and gas chromatography column II, the data obtained from the two are normalized to finally obtain the percentage concentration of each component in the coal sample.

9. A test method for measuring residual gas in coal samples based on GC double-column method according to claim 8, characterized in that: The step 1 comprises: Open the high-purity hydrogen cylinder, introduce hydrogen gas, and observe whether the flow meter reading is stable. If the reading is stable, the air tightness of the device is good and subsequent operations can be performed. Otherwise, the air tightness of the device needs to be checked again. After checking the air tightness of the device, close the high-purity hydrogen cylinder, turn on the vacuum pump to perform vacuum operation, and observe whether the mercury surface of the vacuum gauge is stable. After it is stable, continue to vacuum until the vacuum gauge reading reaches 10Kpa. The step 2 comprises: For the liquid sealed coal sample tank containing coal sample, the solenoid valve is controlled by the computer PLC control system to start the ball grinder to grind the coal sample. The computer runs the temperature PID control system to control the first temperature-raising thermocouple to heat the lower layer of the coal sample tank to 95°C. At this time, the residual gas in the coal sample is desorbed in this state. The step three comprises: The desorbed gas enters the gas storage box through a stainless steel gas pipe for collection and storage. The PLC control system controls the compression amount of the compressible sleeve through a transmission device to select the appropriate gas storage capacity. The step 4 comprises: Open the high-purity helium cylinder, and the helium gas flows out of the high-purity helium cylinder. The computer uses the EPC control system to select a stable pressure and a constant speed to flow into the sleeve-type gas storage device, and is mixed with the previously stored gas to form a carrier gas flow containing various gas components. The carrier gas flow then passes through the pressure gauge, the thermometer, the first flow sensor, and the flow control valve to enter the inner layer of the gas chromatograph, and then passes through the filling column injection port and the gas sample injection valve in turn to reach the gas chromatography column I and the gas chromatography column II to separate the various gas components. The carrier gas flow containing the various gas components separated by the gas chromatography column I and the gas chromatography column II is detected and sampled by the thermal conductivity detector I and the thermal conductivity detector II to generate an output signal. The output signals of the thermal conductivity detector I and the thermal conductivity detector II are converted by the computer into chromatogram sampling.

10. A test method for measuring residual gas in coal samples based on GC double-column method according to claim 9, characterized in that: The step 5 comprises: after sampling, the computer measures and stores the parameters including the peak area, peak height and half slit width of the measured chromatogram data; and separates the relative percentage concentration of each component on the chromatographic column I, which is expressed as follows: Where: q i is the relative percentage concentration of each component, unit %; S i is the peak area of ​​a component, S i =h i *b i ;h i is the peak height, in mm; b i is the half-slit width, in mm; k i is the component signal attenuation multiple; a i is the component correction factor; The step six further includes: The mixed peak correction factor is calculated by the following expression: Where: 混 is the mixed peak correction factor; σ i is the correction factor for each component gas; q i is the concentration of each component gas; The step 7 further comprises: calculating the area occupied by each component in the mixed peak by the following expression: Where: S 混 is the area occupied by the mixed peak; S i is the area of ​​the mixed peak of each component gas; q i is the relative concentration of each component gas.

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