Gas dilution device and method

Abstract

A gas dilution device and method, the device comprises: a dilution gas source, a six-way valve, a vacuum pump, a sample syringe and a dilution syringe, the dilution gas source, the vacuum pump, the sample syringe and the dilution syringe are respectively connected to the six-way valve through pipelines, and the six-way valve is provided with a quantitative loop; a gas storage tank and a first switch valve are provided on the pipeline connecting the dilution gas source and the six-way valve; a second switch valve is provided on the pipeline connecting the vacuum pump and the six-way valve; a third switch valve is provided on the pipeline connecting the dilution syringe and the six-way valve; the pipeline connecting the vacuum pump and the six-way valve and the pipeline connecting the dilution syringe and the six-way valve are mutually connected through a pipeline, and a fourth switch valve is provided. The gas dilution device of the present invention can obtain dilution in a wider range, and can also improve the accuracy and work efficiency of dilution, and reduce human errors.

Description

Technical Field

[0001] The invention belongs to the field of sample detection, and specifically relates to a gas dilution device and method, which are particularly suitable for determining non-methane total hydrocarbons in oil and gas samples. Background Art

[0002] Non-methane hydrocarbons (NMHC) refer to the sum of all gaseous compounds other than methane that have corresponding gaseous compounds on the hydrogen flame ionization detector. Non-methane hydrocarbons are one of the important monitoring items in environmental monitoring. The collection containers for non-methane hydrocarbon samples include all-glass syringes and air bags. When monitoring the inlet and outlet of oil and gas recovery devices at oil storage depots or gas stations, the use of air bag samplers is prohibited due to explosion-proof requirements, so all-glass syringes are the only collection containers for oil and gas samples. Due to the high concentration of non-methane hydrocarbons in oil and gas samples, according to experience, the inlet of oil storage depots or gas station oil and gas recovery devices usually needs to be diluted 10,000 times, and the outlet usually needs to be diluted 100 times.

[0003] In the prior art, a dynamic gas diluter with a mass flow meter or a pressure sensor can be used to suck the collected gas into the cavity through a vacuumed Summa jar, and the sample in the Summa jar can be diluted by pressurization or multiple dilutions to achieve high-precision dilution.

[0004] This dynamic gas diluter has the following disadvantages:

[0005] The maximum dilution multiple of the dynamic gas diluter is 100 times. Oil and gas samples need to be diluted multiple times. One oil and gas sample needs to occupy multiple Summa tanks, and the Summa tanks also need to be equipped with a tank cleaning device.

[0006] Dynamic gas diluters and Summa tanks are difficult to clean after contact with high-concentration samples, which can easily cause residues;

[0007] The cost of dynamic gas diluters and Summa tanks is very high. Summary of the invention

[0008] In order to solve the problems existing in the prior art, the present invention proposes a gas dilution device and method, which can achieve dilution in a wider range, improve the accuracy and work efficiency of dilution, and reduce human errors.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A gas dilution device, comprising: a dilution gas source, a six-way valve, a vacuum pump, a sample syringe and a dilution syringe, wherein the dilution gas source, the vacuum pump, the sample syringe and the dilution syringe are respectively connected to the six-way valve through pipelines, and a quantitative ring is arranged on the six-way valve;

[0011] A gas storage tank and a first switch valve are arranged on the pipeline connecting the dilution gas source and the six-way valve, and the first switch valve is located downstream of the gas storage tank;

[0012] A second switch valve is provided on the pipeline connecting the vacuum pump and the six-way valve; a third switch valve is provided on the pipeline connecting the dilution syringe and the six-way valve; the pipeline connecting the vacuum pump and the six-way valve and the pipeline connecting the dilution syringe and the six-way valve are interconnected through a pipeline, and a fourth switch valve is provided, and the fourth switch valve is located downstream of the second switch valve and the third switch valve.

[0013] In some embodiments, the six-way valve is located in the heating chamber.

[0014] In some embodiments, the sample syringe and the dilution syringe are driven by a syringe driver.

[0015] In some embodiments, a pressure reducing valve and a pressure regulating valve are provided on the pipeline connecting the dilution gas source and the six-way valve. The pressure regulating valve is located upstream of the gas storage tank, and the pressure reducing valve is located upstream of the pressure regulating valve.

[0016] In some embodiments, a first pressure sensor is disposed on the gas storage tank.

[0017] In some embodiments, a second pressure sensor is provided on the pipeline connecting the vacuum pump and the six-way valve, and the second pressure sensor is located downstream of the second switch valve.

[0018] In some embodiments, the dilution gas source is a nitrogen cylinder or a nitrogen generator.

[0019] A gas dilution method using the gas dilution device comprises:

[0020] When the gas dilution device is in a dilution state, flushing the pipeline of the gas dilution device with the dilution gas in the dilution gas source, and starting the vacuum pump to put the dilution syringe into a negative pressure state;

[0021] When the gas dilution device is in a sampling state, the gas sample is injected into the quantitative loop using the sample syringe;

[0022] When the gas dilution device is in a dilution state, the dilution syringe is connected to the six-way valve, and the gas sample in the quantitative loop and the dilution gas in the dilution gas source are sucked into the dilution syringe together.

[0023] In some embodiments, the gas dilution method further comprises, after the gas dilution is completed, using the dilution gas in the dilution gas source to clean the pipeline of the gas dilution device to remove the residual gas sample in the pipeline.

[0024] In some embodiments, the process of removing the residual gas sample in the pipeline is performed under negative pressure and high temperature.

[0025] Compared with the gas dilution device in the prior art, the gas dilution device of the present invention can achieve a wider range of dilution, improve the accuracy and work efficiency of dilution, and reduce human errors. The gas dilution device of the present invention also has the advantages of being simple and convenient, low cost, high accuracy, easy to remove residues, and small space occupation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following drawings are intended only to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0027] Figure 1 A gas dilution device in a sampling state in an embodiment of the present invention;

[0028] Figure 2 A gas dilution device in a dilution state in an embodiment of the present invention;

[0029] Description of reference numerals:

[0030] 1-dilution gas source, 2-pressure reducing valve, 3-pressure regulating valve, 4-gas storage tank, 5-first switch valve, 6-quantitative ring, 7-six-way valve, 8-second switch valve, 9-vacuum pump, 10-sample syringe, 11-syringe drive system, 12-heating chamber, 13-dilution syringe, 14-first pressure sensor, 15-second pressure sensor, 16-fourth switch valve, 17-third switch valve. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0032] In the specification of the present invention, when "one embodiment" is mentioned, it means that the specific features, structures or parameters, steps, etc. described in the embodiment are at least included in one embodiment of the present invention. Therefore, in the specification of the present invention, if terms such as "one embodiment of the present invention" or "in one embodiment" are used, they are not used to specifically refer to the same embodiment, and if terms such as "in another embodiment", "different embodiments of the present invention", "another embodiment of the present invention" are used, they are not used to specifically refer to that the mentioned features can only be included in specific different embodiments. It should be understood by those skilled in the art that the specific features, structures or parameters, steps, etc. disclosed in one or more embodiments of the specification of the present invention can be combined in any suitable manner.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] The present invention provides a gas dilution device, which can dilute the gas in a full glass syringe by 100 times through a dilution device made of glass and polytetrafluoroethylene based on a six-way valve and a pressure balance principle, and can achieve other dilution times by replacing the dilution syringe volume or quantitative ring. The gas dilution device of the present invention is simple and convenient, low in cost, high in accuracy, easy to remove residues, and small in space.

[0035] like Figure 1 and 2 As shown, the gas dilution device of the present invention comprises a dilution gas source 1, a six-way valve 7, a vacuum pump 9, a sample syringe 10 and a dilution syringe 13, wherein the dilution gas source 1, the vacuum pump 9, the sample syringe 10 and the dilution syringe 13 are respectively connected to the six-way valve 7 through pipelines. A quantitative loop 6 is provided on the six-way valve 7, and the six-way valve 7 is located in a heating chamber 12. The sample syringe 10 and the dilution syringe 13 are driven by a syringe driver 11.

[0036] The dilution gas source 1 is used to provide a dilution gas for diluting the sample, such as an inert gas such as nitrogen. The dilution gas source 1 can be a nitrogen cylinder or a high-purity nitrogen generator. A pressure reducing valve 2, a pressure regulating valve 3, a gas storage tank 4 and a first switch valve 5 are sequentially arranged from upstream to downstream on the pipeline connecting the dilution gas source 1 and the six-way valve 7. A first pressure sensor 14 is arranged on the gas storage tank 4.

[0037] The pipeline connecting the vacuum pump 9 and the six-way valve 7 is provided with a second switch valve 8 and a second pressure sensor 15, and the second pressure sensor 15 is located downstream of the second switch valve 8. The pipeline connecting the dilution syringe 13 and the six-way valve 7 is provided with a third switch valve 17. The pipeline connecting the vacuum pump 9 and the six-way valve 7 and the pipeline connecting the dilution syringe 13 and the six-way valve 7 are interconnected through a pipeline, and a fourth switch valve 16 is provided, and the fourth switch valve 16 is located downstream of the second switch valve 8 and the third switch valve 17.

[0038] According to an embodiment of the present invention, a method for diluting gas using the gas dilution device comprises the following steps:

[0039] Step 1: put the six-way valve 7 in the dilution state, at which time the four switch valves are in the on state, and flush the entire pipeline of the device with nitrogen in the dilution gas source 1;

[0040] Step 2: Install the sample syringe 10 and the dilution syringe 13;

[0041] Step 3: Use the syringe driver 11 to push the piston of the dilution syringe to position the dilution syringe at the required volume position, close the second switch valve 8 and the third switch valve 17, put the fourth switch valve in the conducting state, and then start the vacuum pump 9. Under the action of the vacuum pump 9, the dilution syringe 13 is in a negative pressure state;

[0042] Step 4: put the six-way valve 7 in the injection state, use the syringe driver 11 to push the piston of the sample syringe 10 to inject the sample into the quantitative ring 6, and the excess gas is discharged through the discharge port;

[0043] Step 5: Put the six-way valve 7 in the dilution state. When the pressure of the first pressure sensor 14 reaches a negative pressure state below 20 mbar, close the pressure regulating valve 3, the second switch valve 8 and the fourth switch valve 16, and put the third switch valve 17 in the on state to connect the dilution syringe 13 with the six-way valve 7. Under the negative pressure of the dilution syringe 13, the sample gas in the quantitative ring 6 and part of the nitrogen in the gas storage tank 4 are sucked into the dilution syringe 13 together, and the pressure regulating valve 3 is driven to allow the nitrogen in the dilution gas source 1 to slowly inject into the gas storage tank 4, so that the nitrogen pressure in the gas storage tank 4 reaches the standard atmospheric pressure value. When the pressure of the first pressure sensor 14 reaches the standard atmospheric pressure, close the first switch valve 5, and finally close the valve on the dilution syringe 13, remove the connecting pipeline, and remove the dilution syringe 13 to complete the entire dilution process.

[0044] According to an embodiment of the present invention, the method for cleaning the gas dilution device comprises the following steps:

[0045] Step 1: Place the six-way valve 7 in a dilution state, close the fourth switch valve 16 and the third switch valve 17, place the second switch valve 8 and the first switch valve 5 in an on state, place the pressure regulating valve 3 in an on state, and allow the nitrogen in the dilution gas source 1 to be injected into the quantitative ring 6 and the corresponding pipeline.

[0046] Step 2: Start the heating chamber 12 to heat the temperature in the chamber to about 240°C, close the first switch valve 5, start the vacuum pump 9, and under the action of negative pressure, the boiling point of the residual organic matter in the pipeline is reduced, and under the assistance of high temperature, the residual organic matter is discharged by the vacuum pump 9 to achieve the purpose of purification;

[0047] Step 3: Make the second pressure sensor 15 reach below 20 mbar and keep it for 1 minute, open the first switch valve 5 and the pressure regulating valve 3 again to let nitrogen enter the system, and the vacuum pump 9 continues to work for 1 minute;

[0048] Step 4: Close the first switch valve 5 again, let the second pressure sensor 15 reach below 20 mbar again, repeatedly fill with nitrogen and evacuate the system to discharge the residual organic matter in the system, and further achieve the purpose of complete purification.

[0049] In one embodiment, the gas dilution device of the present invention is used to solve the problems of multiple manual dilutions required due to excessively high concentrations of non-methane total hydrocarbons in oil and gas samples, easy residues during dilution, and inaccurate gas volume measurement using a syringe. In this embodiment, the gas dilution device of the present invention is used to dilute an outlet sample of an oil and gas recovery device, and the sample can be diluted within 5 minutes, thereby improving the accuracy of dilution, greatly improving work efficiency, and reducing human errors.

[0050] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gas dilution device, comprising: A dilution gas source, a six-way valve, a vacuum pump, a sample syringe and a dilution syringe, wherein the dilution gas source, the vacuum pump, the sample syringe and the dilution syringe are respectively connected to the six-way valve through pipelines, and a quantitative ring is provided on the six-way valve; A gas storage tank and a first switch valve are arranged on the pipeline connecting the dilution gas source and the six-way valve, and the first switch valve is located downstream of the gas storage tank; A second switch valve is provided on the pipeline connecting the vacuum pump and the six-way valve; a third switch valve is provided on the pipeline connecting the dilution syringe and the six-way valve; the pipeline connecting the vacuum pump and the six-way valve and the pipeline connecting the dilution syringe and the six-way valve are interconnected through a pipeline, and a fourth switch valve is provided, and the fourth switch valve is located downstream of the second switch valve and the third switch valve; Wherein, the six-way valve is located in the heating cavity; The sample syringe and the dilution syringe are driven by a syringe driver.

2. The gas dilution device according to claim 1, wherein: A pressure reducing valve and a pressure regulating valve are arranged on the pipeline connecting the dilution gas source and the six-way valve. The pressure regulating valve is located upstream of the gas storage tank, and the pressure reducing valve is located upstream of the pressure regulating valve.

3. The gas dilution device according to claim 1, wherein: The gas storage tank is provided with a first pressure sensor.

4. The gas dilution device according to claim 1, wherein: A second pressure sensor is provided on the pipeline connecting the vacuum pump and the six-way valve, and the second pressure sensor is located downstream of the second switch valve.

5. The gas dilution device according to claim 1, wherein: The dilution gas source is a nitrogen cylinder or a nitrogen generator.

6. A gas dilution method using the gas dilution device according to any one of claims 1 to 5, comprising: When the gas dilution device is in a dilution state, flushing the pipeline of the gas dilution device with the dilution gas in the dilution gas source, and starting the vacuum pump to put the dilution syringe into a negative pressure state; When the gas dilution device is in a sampling state, the gas sample is injected into the quantitative loop using the sample syringe; When the gas dilution device is in a dilution state, the dilution syringe is connected to the six-way valve, and the gas sample in the quantitative loop and the dilution gas in the dilution gas source are sucked into the dilution syringe together.

7. The gas dilution method according to claim 6, wherein: The gas dilution method further comprises, after the gas dilution is completed, using the dilution gas in the dilution gas source to clean the pipeline of the gas dilution device to remove the residual gas sample in the pipeline.

8. The gas dilution method according to claim 7, wherein: The process of removing the residual gas sample in the pipeline is carried out under negative pressure and high temperature.

Images