Automatic sampling device and method for high-pressure natural gas

Abstract

The invention discloses an automatic sampling device and method for high-pressure natural gas, and belongs to the technical field of petroleum and natural gas development, gathering and transportation. According to the technical scheme, the system comprises a nitrogen replacement unit, a natural gas access unit, a heating unit, a double-throttling unit and a natural gas discharge unit which are sequentially connected through pipelines and controlled by a control unit. The device has the beneficial effects that the nitrogen replacement of the device is automatically realized through the explosion-proof PLC, the temperature of high-pressure natural gas is automatically raised to 90 DEG C in advance, and after the pressure is reduced to 0.4 MPa through two-stage throttling, the safe operation of a sampling worker on a sampling bottle under a low-pressure working condition is met, and the authenticity of components of an obtained natural gas sample can be ensured.

Description

Technical Field

[0001] The invention relates to a high-pressure natural gas automatic sampling device, belonging to the technical field of oil and natural gas development and gathering and transportation. Background Art

[0002] During the gas production process of natural gas fields and gas storages, it is necessary to obtain natural gas samples at the gas wellhead or in the gas production process to test its components. During the sampling operation, on-site personnel are usually required to manually operate and control to complete the replacement of the cylinder and gas sampling. There are the following problems: 1. The gas production pressure is high, and there are safety risks in manual operation and control sampling. During the sampling process, the replacement and sampling operations are all manually operated. If there is a valve control error or valve failure, it may cause personal injury to the sampler. 2. Manual operation and control sampling cannot accurately control the pressure. Manual control is used during sampling, and the replacement and filling process of the cylinder depends entirely on the observation and manual control of the on-site sampler, and there is a possibility of misoperation and operation errors. 3. Due to the high pressure, according to the requirements of GB / T13609-2017 "Guidelines for Natural Gas Sampling": Due to the Joule-Thompson effect, when the pressure decreases, the temperature decreases at a ratio of about 0.5℃ / 0.1MPa, and there is a possibility of condensation of heavy components. If condensation occurs, the sample is no longer representative. That is, no heating device is provided, and sample distortion affects the test results. Summary of the invention

[0003] In view of the technical problems such as the need to obtain produced natural gas samples from the gas production pipeline to test their components during the gas production process of natural gas fields and gas storage facilities, the existing sampling devices and methods have great safety risks due to the high pressure of produced gas, and the distortion of the obtained samples affects the test results. The present invention provides a high-pressure natural gas automatic sampling device and method, which can not only meet the safe operation of the sampling personnel during sampling, but also ensure the authenticity of the components of the obtained natural gas samples.

[0004] The technical solution of the present invention is: a high-pressure natural gas automatic sampling device, comprising a nitrogen replacement unit, a natural gas access unit, a heating unit, a double throttling unit and a natural gas discharge unit which are sequentially connected through pipelines and controlled by a control unit.

[0005] The nitrogen replacement unit comprises a pipeline a for connecting to a nitrogen tank, a nitrogen replacement valve connected to a control unit is arranged on the pipeline a, and the other end of the pipeline a is connected to a heating unit.

[0006] The natural gas access unit comprises a pipeline b connected to a natural gas container, a natural gas inlet valve is arranged on the pipeline b, the natural gas inlet valve is connected to the control unit, and the other end of the pipeline b is connected to the pipeline a.

[0007] The heating unit comprises an electric heater. The temperature transmitter is used to monitor the temperature of the electric heater. The temperature transmitter and the electric heater are connected to a control unit.

[0008] The dual throttling unit includes a temperature control valve, a primary throttling valve and a secondary throttling valve located on pipeline c. The temperature control valve and pressure transmitter a are connected to the control unit. Pipeline c is connected to the buffer tank. The end of pipeline c is connected to the natural gas discharge unit.

[0009] It also includes a pressure transmitter a and a pressure transmitter b, wherein the pressure transmitter a is located near the outlet of the first-stage throttle valve, and the pressure transmitter b is located near the inlet of the second-stage throttle valve.

[0010] The natural gas discharge unit comprises a natural gas outlet valve located on the pipeline d, the natural gas outlet valve is connected to the control unit, and the outlet of the pipeline d is detachably connected to a natural gas sampling bottle.

[0011] The inlet end and the outlet end of the natural gas sampling bottle are respectively provided with an inlet control valve and an outlet control valve.

[0012] The control unit is an explosion-proof PLC.

[0013] The present invention also claims protection for a sampling method based on a high-pressure natural gas automatic sampling device, comprising the following steps:

[0014] Step 1: Connect the nitrogen tank to the inlet of pipeline a, and connect the inlet of pipeline b to the natural gas container;

[0015] Step 2: Close the natural gas inlet valve through the explosion-proof PLC, open the nitrogen replacement valve, temperature control valve and natural gas outlet valve, replace the entire device with nitrogen for 30 seconds, and then close the nitrogen replacement valve and temperature control valve;

[0016] Step 3: Open the natural gas inlet valve, and the natural gas is introduced into the electric heater through pipeline b for heating. When the temperature transmitter detects that the natural gas temperature in the electric heater reaches 90 degrees Celsius, the temperature control valve opens, and the high-temperature and high-pressure natural gas passes through the first-level throttle valve, and the gas pressure drops to 3.5-5Mpa;

[0017] Step 4: After the first-level throttling, the natural gas passes through the second-level throttling valve, and the gas pressure is further reduced to 0.4Mpa;

[0018] Step 5: The gas after secondary throttling is discharged through pipeline d for 30 seconds, and then the outlet of pipeline d is connected to a natural gas sampling bottle to sample natural gas;

[0019] Step 6: After sampling, remove the natural gas sampling bottle and have the laboratory staff conduct laboratory analysis on the sample.

[0020] The beneficial effects of the present invention are as follows: the nitrogen replacement of the device can be automatically realized through the explosion-proof PLC, the high-pressure natural gas temperature can be automatically raised to 90°C in advance, and the pressure can be reduced to 0.4MPa through two-stage throttling, which can meet the safe operation of the sampling bottle by the sampling personnel under low-pressure conditions and ensure the authenticity of the natural gas sample components. At the same time, it can be disassembled and used in multiple sampling points in turn, which can greatly reduce the investment cost of the sampling device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the present invention.

[0022] The reference numerals in the figure are as follows: 1. Pipeline a, 2. Pipeline b, 3. Temperature transmitter, 4. Electric heater, 5. Explosion-proof PLC, 6. Buffer tank, 7. Nitrogen replacement valve, 8. Natural gas inlet valve, 9. Temperature control valve, 10. First-stage throttle valve, 11. Second-stage throttle valve, 12. Natural gas outlet valve, 13. Pipeline c, 14. Pressure transmitter a, 15. Pressure transmitter b, 16. Pipeline d. DETAILED DESCRIPTION

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below in combination with the accompanying drawings and detailed embodiments. 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 labor.

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0025] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0026] Secondly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0027] The following is combined with Figure 1 The present invention is described in further detail:

[0028] Example 1

[0029] A high-pressure natural gas automatic sampling device comprises a nitrogen replacement unit, a natural gas access unit, a heating unit, a double throttling unit and a natural gas discharge unit which are sequentially connected through pipelines and controlled by a control unit. The control unit is an explosion-proof PLC5.

[0030] The nitrogen replacement unit includes a pipeline a1 for connecting a nitrogen tank, a nitrogen replacement valve 7 connected to an explosion-proof PLC 5 is provided on the pipeline a1, and the other end of the pipeline a1 is connected to a heating unit. The nitrogen replacement unit replaces the sampling device with nitrogen to remove the residual oxygen in the pipeline to ensure the safety of the sampling work, and at the same time has a purge function to remove the residual impurities in the pipeline to ensure the authenticity of the sample components.

[0031] The natural gas access unit includes a pipeline b2 connected to a natural gas container, a natural gas inlet valve 8 is provided on the pipeline b2, the natural gas inlet valve 8 is connected to the control unit, and the other end of the pipeline b2 is connected to the pipeline a1. The natural gas inlet valve 8 controls whether the pipeline b2 is connected to the pipeline a1, thereby controlling the natural gas sample to enter the pipeline a1 from the pipeline b2.

[0032] The heating unit includes an electric heater 4, a temperature transmitter 3 is used to monitor the temperature of the natural gas in the electric heater 4, and the temperature transmitter 3 and the electric heater 4 are connected to a control unit. The electric heater 4 heats the incoming natural gas and automatically raises the temperature of the high-pressure natural gas to 90°C in advance. The temperature transmitter 3 is used to monitor the temperature of the natural gas. When the predetermined temperature is reached, the temperature transmitter 3 sends a signal to the explosion-proof PLC5, and the explosion-proof PLC5 sends a stop heating instruction to the electric heater 4, and the electric heater 4 stops heating. When the temperature of the natural gas in the electric heater 4 is lower than the preset temperature, the temperature transmitter 3 sends a signal to the explosion-proof PLC5, and the explosion-proof PLC5 sends a heating instruction to the electric heater 4, and the electric heater 4 starts heating.

[0033] The dual throttling unit includes a temperature control valve 9, a primary throttle valve 10 and a secondary throttle valve 11 located on the pipeline c13. The temperature control valve 9 and the pressure transmitter a14 are connected to the control unit, the pipeline c13 is connected to the buffer tank 6, and the end of the pipeline c13 is connected to the natural gas discharge unit. The dual throttling unit also includes a pressure transmitter a14 and a pressure transmitter b15. The pressure transmitter a14 is located near the outlet side of the primary throttle valve 10, and the pressure transmitter b15 is located near the inlet side of the secondary throttle valve 11. When the temperature of the natural gas in the electric heater 4 reaches 90°C, the explosion-proof PLC5 controls the opening of the temperature control valve 9, and the high-temperature and high-pressure natural gas passes through the primary throttle valve for primary throttling and pressure reduction, and the pressure is reduced to 3.5-5Mpa. The natural gas after primary throttling and pressure reduction enters the buffer tank 6, and then passes through the secondary throttle valve 11 to reduce the pressure to 0.4Mpa, which meets the safety operation of the sampling bottle by the sampling personnel under low-pressure conditions.

[0034] The natural gas discharge unit includes a natural gas outlet valve 12 located on the pipeline d16, the natural gas outlet valve 12 is connected to the explosion-proof PLC5, and the outlet of the pipeline d16 is detachably connected to the natural gas sampling bottle. The natural gas outlet valve 12 controls the connection and disconnection between the pipeline d16 and the natural gas sampling bottle, and the opening and closing of the natural gas outlet valve 12 is controlled by the explosion-proof PLC5.

[0035] The inlet end and the outlet end of the natural gas sampling bottle are respectively provided with an inlet control valve and an outlet control valve. The inlet control valve and the outlet control valve are provided to facilitate the natural gas sampling bottle to collect and discharge sample gas.

[0036] Example 2

[0037] A sampling method based on a high-pressure natural gas automatic sampling device comprises the following steps:

[0038] Step 1: Connect the nitrogen tank to the inlet of pipeline a1, and connect the inlet of pipeline b2 to the natural gas container;

[0039] Step 2: Close the natural gas inlet valve 8 through the explosion-proof PLC, open the nitrogen replacement valve 7, the temperature control valve 9 and the natural gas outlet valve 12, replace the entire device with nitrogen for 30 seconds, and then close the nitrogen replacement valve 7 and the temperature control valve 9;

[0040] Step 3: Open the natural gas inlet valve 8, and the natural gas is introduced into the electric heater 4 through the pipeline b2 for heating. When the temperature transmitter 3 detects that the natural gas temperature in the electric heater 4 reaches 90 degrees Celsius, the temperature control valve 9 opens, and the high-temperature and high-pressure natural gas passes through the primary throttle valve 10, and the gas pressure drops to 3.5-5Mpa;

[0041] Step 4: After the first-level throttling, the natural gas passes through the second-level throttling valve 11, and the gas pressure is further reduced to 0.4Mpa;

[0042] Step 5: The gas after secondary throttling is discharged through pipeline d16 for 30 seconds, and then the outlet of pipeline d16 is connected to the natural gas sampling bottle to sample the natural gas;

[0043] Step 6: After sampling, remove the natural gas sampling bottle and have the laboratory staff conduct laboratory analysis on the sample.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-pressure natural gas automatic sampling device, characterized in that: The invention comprises a nitrogen replacement unit, a natural gas access unit, a heating unit, a double throttling unit and a natural gas discharge unit which are sequentially connected through pipelines and controlled by a control unit.

2. The high-pressure natural gas automatic sampling device according to claim 1, characterized in that: The nitrogen replacement unit comprises a pipeline a (1) for connecting to a nitrogen tank, a nitrogen replacement valve (7) connected to a control unit is provided on the pipeline a (1), and the other end of the pipeline a (1) is connected to a heating unit.

3. The high-pressure natural gas automatic sampling device according to claim 2, characterized in that: The natural gas access unit comprises a pipeline b (2) connected to a natural gas container, a natural gas inlet valve (8) is provided on the pipeline b (2), the natural gas inlet valve (8) is connected to the control unit, and the other end of the pipeline b (2) is connected to the pipeline a (1).

4. The high-pressure natural gas automatic sampling device according to claim 1, characterized in that: The heating unit comprises an electric heater (4); a temperature transmitter (3) is used to monitor the temperature of natural gas in the electric heater (4); and the temperature transmitter (3) and the electric heater (4) are connected to a control unit.

5. The high-pressure natural gas automatic sampling device according to claim 1, characterized in that: The dual throttling unit comprises a temperature control valve (9), a primary throttling valve (10) and a secondary throttling valve (11) located on a pipeline c (13); the temperature control valve (9) and a pressure transmitter a (14) are connected to a control unit; the pipeline c (13) is connected to a buffer tank (6); and the end of the pipeline c (13) is connected to a natural gas discharge unit.

6. The high-pressure natural gas automatic sampling device according to claim 5, characterized in that: It also includes a pressure transmitter a (14) and a pressure transmitter b (15), wherein the pressure transmitter a (14) is located near the outlet of the first-stage throttle valve (10), and the pressure transmitter b (15) is located near the inlet of the second-stage throttle valve (11).

7. The high-pressure natural gas automatic sampling device according to claim 1, characterized in that: The natural gas discharge unit comprises a natural gas outlet valve (12) located on a pipeline d (16), wherein the natural gas outlet valve (12) is connected to a control unit, and an outlet of the pipeline d (16) is detachably connected to a natural gas sampling bottle.

8. The high-pressure natural gas automatic sampling device according to claim 7, characterized in that: The inlet end and the outlet end of the natural gas sampling bottle are respectively provided with an inlet control valve and an outlet control valve.

9. The high-pressure natural gas automatic sampling device according to claim 1, characterized in that: The control unit is an explosion-proof PLC (5).

10. A sampling method based on a high-pressure natural gas automatic sampling device, characterized in that: The steps include: Step 1: Connect the nitrogen tank to the inlet of pipeline a (1), and connect the inlet of pipeline b (2) to the natural gas container; Step 2: Close the natural gas inlet valve (8) through the explosion-proof PLC, open the nitrogen replacement valve (7), the temperature control valve (9) and the natural gas outlet valve (12), replace the entire device with nitrogen for 30 seconds, and then close the nitrogen replacement valve (7) and the temperature control valve (9); Step 3: Open the natural gas inlet valve (8), and the natural gas is introduced into the electric heater (4) through the pipeline b (2) for heating. When the temperature transmitter (3) detects that the temperature of the natural gas in the electric heater (4) reaches 90 degrees Celsius, the temperature control valve (9) opens, and the high-temperature and high-pressure natural gas passes through the first-stage throttle valve (10), and the gas pressure drops to 3.5-5 MPa; Step 4: After the first-stage throttling, the natural gas passes through the second-stage throttling valve (11), and the gas pressure is further reduced to 0.4Mpa; Step 5: The gas after secondary throttling is discharged through pipeline d (16) for 30 seconds, and then the outlet of pipeline d (16) is connected to a natural gas sampling bottle to sample natural gas; Step 6: After sampling, remove the natural gas sampling bottle and have the laboratory staff conduct laboratory analysis on the sample.

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