Apparatus and method for deep dehydration of raw natural gas and internal and external circulation regeneration

Abstract

This invention discloses a four-tower molecular sieve deep dehydration and internal / external circulation regeneration device for raw natural gas. It includes four molecular sieve dehydration towers, each connected via pipelines to an adsorption inlet manifold, a regenerated gas outlet manifold, an adsorption outlet manifold, and a regenerated gas inlet manifold. The device also includes a gas-to-gas heat exchanger, a regenerated gas air cooler, a regenerated gas separator, a regenerated gas compressor, a regenerated gas heater, a pre-filter, and a post-filter. This invention can meet the deep dehydration requirements for large-scale natural gas processing. The invention also discloses a method for deep dehydration and internal / external circulation regeneration of raw natural gas, including sequential impurity removal, adsorption dehydration, recovery treatment, and increased external transmission or circulation. This invention can adjust and control the deep dehydration of raw natural gas according to the adsorption effect without human intervention.

Description

Technical Field

[0001] This invention belongs to the field of natural gas processing and ethane and other light hydrocarbon recovery technology, and relates to a four-tower molecular sieve deep dehydration and internal and external circulation regeneration device for raw natural gas, as well as a method for deep dehydration and internal and external circulation regeneration of raw natural gas. Background Technology

[0002] Ethane is a high-quality feedstock for ethylene. The production cost of ethylene from ethane cracking is two-thirds that of naphtha. Internationally, C2-C4 accounts for about 48% of ethylene feedstock, but my country, constrained by raw material availability, mainly relies on naphtha. Recovering ethane from natural gas and using it as feedstock for steam cracking to produce ethylene has a positive effect on increasing ethylene production, reducing energy consumption in ethylene plants, and improving both quality and efficiency.

[0003] Raw natural gas is the feedstock for ethane recovery projects. Recovering ethane from natural gas requires cryogenic distillation to recover ethane and other light hydrocarbon components, with a minimum operating temperature of -100°C. To prevent moisture in the natural gas from freezing and clogging equipment and pipelines under low-temperature conditions, thus affecting the safe and stable operation of the system, the raw natural gas used for ethane recovery must undergo deep dehydration treatment. Therefore, to improve the quality and efficiency of ethane recovery, it is necessary to process and recover raw natural gas, especially for large-scale operations. Summary of the Invention

[0004] The purpose of this invention is to provide a four-tower molecular sieve deep dehydration and internal and external circulation regeneration device for raw natural gas, which can meet the deep dehydration requirements for large-scale natural gas processing.

[0005] Another objective of this invention is to provide a method for deep dehydration and internal / external circulation regeneration of raw natural gas, which can adjust and control the deep dehydration of raw natural gas according to the adsorption effect without human intervention.

[0006] The first technical solution adopted in this invention is a four-tower molecular sieve deep dehydration and internal and external circulation regeneration device for raw natural gas, which includes four molecular sieve dehydration towers. Each molecular sieve dehydration tower is connected to an adsorption inlet manifold, a regeneration gas outlet manifold, an adsorption outlet manifold, and a regeneration gas inlet manifold via pipelines. It also includes a gas-gas heat exchanger, a regeneration gas air cooler, a regeneration gas separator, a regeneration gas compressor, a regeneration gas heater, a pre-filter, and a post-filter.

[0007] The first technical solution of the present invention is further characterized in that,

[0008] An inlet pipeline is installed at the inlet of the pre-filter, and the outlet of the pre-filter is connected to the adsorption air intake manifold.

[0009] The gas-to-gas heat exchanger is connected to the regenerated gas air cooler and the regenerated gas heater via pipelines. The gas-to-gas heat exchanger is also connected to the regenerated gas outlet manifold and the natural gas outlet manifold.

[0010] The regenerated gas air cooler is connected to the regenerated gas separator via pipeline;

[0011] The regenerated gas separator is connected to the outlet regenerated gas manifold and the external condensate manifold. The outlet regenerated gas manifold is connected to the regenerated gas compressor. A shut-off valve is installed at the outlet of the outlet regenerated gas manifold. The outlet regenerated gas manifold is connected to the inlet pipeline of the pre-filter through the pipeline with the shut-off valve. The connection point between the outlet regenerated gas manifold and the inlet pipeline of the pre-filter is located between the shut-off valve at the outlet of the outlet regenerated gas manifold and the regenerated gas compressor.

[0012] The inlet of the post-filter is connected to the adsorption gas manifold, and the outlet is connected to the natural gas manifold of the outlet unit via a pipeline. The natural gas manifold of the outlet unit is equipped with a programmable valve, a regenerated gas regulating valve, a regenerated gas flow meter, and two shut-off valves in sequence from the gas-to-gas heat exchanger to the outlet of the natural gas manifold of the outlet unit. The connection between the post-filter and the natural gas manifold of the outlet unit is located between the two shut-off valves. The natural gas manifold of the outlet unit is also connected to a regenerated natural gas manifold. The connection between the regenerated natural gas manifold and the natural gas manifold of the outlet unit is located between the regenerated gas flow meter and the adjacent shut-off valve.

[0013] The regenerated gas heater is also connected to a regenerated gas inlet manifold, an outlet heat transfer oil manifold, and an inlet heat transfer oil manifold. The regenerated gas inlet manifold is connected to a regenerated gas outlet manifold and an outlet natural gas manifold via pipelines.

[0014] Each molecular sieve dehydration tower is equipped with a programmable valve on the pipelines connected to the adsorption inlet manifold, regeneration gas outlet manifold, adsorption outlet manifold, and regeneration gas inlet manifold. The programmable valves on the pipelines connected to the adsorption inlet manifold and regeneration gas outlet manifold are located above the top of the molecular sieve dehydration tower, while the programmable valves on the pipelines connected to the adsorption outlet manifold and regeneration gas inlet manifold are located below the bottom of the molecular sieve dehydration tower.

[0015] A shut-off valve is installed at the inlet of the inlet pipeline;

[0016] The renewable natural gas manifold is equipped with a shut-off valve;

[0017] The inlet and outlet of the regenerated gas compressor are connected to the regenerated gas manifold of the outlet device via pipelines. Both pipelines are equipped with shut-off valves, and shut-off valves are also installed between the two connection points of the regenerated gas manifold of the outlet device and the regenerated gas compressor.

[0018] A temperature detector A is installed on the regenerated gas outlet manifold near the connection point with the regenerated gas inlet manifold;

[0019] Programmable valves are installed on the connecting pipelines of the regenerated gas inlet manifold to the regenerated gas outlet manifold and the natural gas outlet manifold.

[0020] The regenerated gas separator is equipped with a level gauge, and a level regulating valve is installed on the external condensate drain manifold. The level gauge and the level regulating valve form a temperature regulation loop.

[0021] A temperature detector B is installed on the regenerated gas inlet manifold near the regenerated gas heater, and a heat transfer oil regulating valve is installed on the heat transfer oil inlet manifold. The temperature detector B and the heat transfer oil regulating valve form a temperature regulation circuit.

[0022] The second technical solution adopted in this invention is a method for deep dehydration and internal / external circulation regeneration of raw natural gas. This method uses a PLC controller to control the three-tower molecular sieve dehydration and regeneration device for natural gas ethane recovery, achieving deep dehydration of ethane. Specifically, it is implemented according to the following steps:

[0023] Step 1: Pass the raw natural gas from outside the boundary into the pre-filter to separate the impurities carried by the raw natural gas and obtain impurity-free natural gas;

[0024] Step 2: Connect the impurity-removed natural gas to the adsorption inlet manifold. Open the programmable valve on the pipeline connecting each molecular sieve dehydration tower to the adsorption inlet manifold. The impurity-removed natural gas enters the molecular sieve dehydration tower from top to bottom for adsorption and dehydration to obtain dehydrated natural gas.

[0025] Step 3: The programmable valve on the pipeline connecting each molecular sieve dehydration tower to the adsorption gas outlet manifold is opened. The dehydrated natural gas is introduced into the post-filter through the adsorption gas outlet manifold to filter out the molecular sieve particles it carries, and obtain impurity-free dehydrated natural gas. It is then transported through the natural gas outlet manifold to the liquid hydrocarbon recovery unit outside the boundary for recycling treatment. After recycling treatment, recycled natural gas is obtained.

[0026] Step 4: Regenerated natural gas is introduced into the regenerated natural gas manifold, and after being measured by the regenerated gas flow meter and regulated by the regenerated gas regulating valve, it is divided into two paths. One path is used as regenerated heating gas, and the other path is used as regenerated cold blowing gas. The two gas paths are switched and controlled by a programmable valve.

[0027] Step 5: After the regenerated heating gas is heated by heat exchange in the gas-to-gas heat exchanger, it enters the regenerated gas heater for heating. The programmable valve on the pipeline connecting the molecular sieve dehydration tower closest to the regenerated gas heater and the adsorption inlet manifold is opened. After the heated regenerated heating gas enters the regenerated gas inlet manifold, it enters the molecular sieve dehydration tower from bottom to top to heat and regenerate the molecular sieve dehydration tower, thus obtaining secondary heated regenerated gas. The secondary heated regenerated gas is cooled by the regenerated gas outlet manifold and the gas-to-gas heat exchanger, and then enters the regenerated gas air cooler and the regenerated gas separator in sequence to obtain heated gas circulating regenerated gas with condensate separated. The heated gas circulating regenerated gas is pressurized by the regenerated gas compressor and sent out or enters the inlet of the pre-filter for circulation.

[0028] Step 6: After the regenerated cold blowing gas is switched by the process control valve, it enters the regenerated gas inlet manifold and cools down the heated molecular sieve dehydration tower from bottom to top to obtain secondary regenerated cold blowing gas. The secondary regenerated cold blowing gas passes through the regenerated gas outlet manifold, gas-to-gas heat exchanger, regenerated gas air cooler, and regenerated gas separator in sequence to obtain cold blowing gas circulation regenerated gas. The cold blowing gas circulation regenerated gas is pressurized by the regenerated gas compressor and sent out or enters the inlet of the pre-filter for circulation.

[0029] The second technical solution of the present invention is further characterized in that,

[0030] The condensate separated by the regenerated gas separator in steps 5 and 6 is discharged to the wastewater treatment system through the condensate drain manifold.

[0031] The regenerated gas heater uses heat transfer oil introduced into the heat transfer oil system outside the boundary area through the inlet heat transfer oil manifold to achieve the heating purpose. After heating, the heat transfer oil is discharged out of the outlet heat transfer oil manifold and returned to the heat transfer oil system outside the boundary area.

[0032] The beneficial effects of this invention are:

[0033] This invention relates to a four-tower molecular sieve deep dehydration and internal and external circulation regeneration device for raw natural gas. It achieves deep dehydration of engineering raw natural gas and partial co-absorption of CO2 and H2S, meeting the quality requirement that the water dew point of the dehydrated natural gas reaches 0.1ppm, and can reduce the content of CO2 and H2S in the raw natural gas.

[0034] The present invention discloses a method for deep dehydration and internal and external circulation regeneration of raw natural gas. It employs four molecular sieve dehydration towers and a regeneration method to automatically complete the sequential control and circulation of molecular sieve dehydration adsorption, heating and cold blowing. The set cycle or sequence control steps can be adjusted at any time according to the adsorption effect, thereby achieving the purpose of deep dehydration of raw natural gas without human intervention. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the four-tower molecular sieve deep dehydration and internal and external circulation regeneration device for raw natural gas in Embodiment 3 of the present invention.

[0036] In the diagram, 1. Raw material natural gas, 2. Shut-off valve, 3. Pre-filter, 4. Adsorption inlet manifold, 5. Programmable valve, 8. Molecular sieve dehydration tower A, 9. Molecular sieve dehydration tower B, 10. Molecular sieve dehydration tower C, 11. Molecular sieve dehydration tower D, 14. Adsorption outlet manifold, 15. Regenerated gas inlet manifold, 16. Post-filter, 18. Natural gas exiting the unit, 19. Regenerated natural gas, 22. Regenerated gas flow meter, 23. Regenerated gas. 26. Regulating valve, 27. Gas-to-gas heat exchanger, 28. Regenerated gas air cooler, 29. Regenerated gas separator, 30. Regenerated gas compressor, 31. Regenerated gas outlet, 32. Level gauge, 33. Level regulating valve, 34. Condensate, 35. Heat transfer oil inlet, 46. Heat transfer oil regulating valve, 47. Heat transfer oil outlet, 48. Regenerated gas outlet manifold, 49. Temperature detector A, 40. Temperature detector B. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] This embodiment provides a four-tower molecular sieve deep dehydration and internal and external circulation regeneration device for raw natural gas, including four molecular sieve dehydration towers. Each molecular sieve dehydration tower is connected to an adsorption inlet manifold 4, a regeneration gas outlet manifold 41, an adsorption outlet manifold 14, and a regeneration gas inlet manifold 15 via pipelines. It also includes a gas-gas heat exchanger 26, a regeneration gas air cooler 27, a regeneration gas separator 28, a regeneration gas compressor 29, a regeneration gas heater 30, a pre-filter 3, and a post-filter 16.

[0040] Example 2

[0041] This embodiment provides a four-tower molecular sieve deep dehydration and internal / external circulation regeneration device for raw natural gas, such as... Figure 1 As shown, it includes four molecular sieve dehydration towers: molecular sieve dehydration tower A8, molecular sieve dehydration tower B9, molecular sieve dehydration tower C10, and molecular sieve dehydration tower D11. Each molecular sieve dehydration tower is connected to an adsorption gas inlet manifold 4, a regenerated gas outlet manifold 41, an adsorption gas outlet manifold 14, and a regenerated gas inlet manifold 15 via pipelines. It also includes a gas-to-gas heat exchanger 26, a regenerated gas air cooler 27, a regenerated gas separator 28, a regenerated gas compressor 29, a regenerated gas heater 30, a pre-filter 3, and a post-filter 16.

[0042] An inlet pipeline is installed at the inlet of the pre-filter 3, and the outlet of the pre-filter 3 is connected to the adsorption air intake manifold 4.

[0043] The gas-to-gas heat exchanger 26 is connected to the regenerated gas air cooler 27 and the regenerated gas heater 30 via pipelines. The gas-to-gas heat exchanger 26 is also connected to the regenerated gas outlet manifold 41 and the natural gas outlet manifold of the device.

[0044] The regenerated gas air cooler 27 is connected to the regenerated gas separator 28 via a pipeline;

[0045] The regenerated gas separator 28 is connected to the outlet regenerated gas manifold and the external condensate manifold. The outlet regenerated gas manifold is connected to the regenerated gas compressor 29. A shut-off valve 2 is installed at the outlet of the outlet regenerated gas manifold. The outlet regenerated gas manifold is connected to the inlet pipeline of the pre-filter 3 through the pipeline equipped with the shut-off valve 2. The connection point between the outlet regenerated gas manifold and the inlet pipeline of the pre-filter 3 is located between the shut-off valve 2 at the outlet of the outlet regenerated gas manifold and the regenerated gas compressor 29.

[0046] The inlet of the post-filter 16 is connected to the adsorption outlet manifold 14, and the outlet is connected to the outlet natural gas manifold via a pipeline. The outlet natural gas manifold is equipped with a programmable valve 5, a regenerated gas regulating valve 23, a regenerated gas flow meter 22, and two shut-off valves 2 in sequence from the gas-to-gas heat exchanger 26 to the outlet of the outlet natural gas manifold. The connection between the post-filter 16 and the outlet natural gas manifold is located between the two shut-off valves 2. The outlet natural gas manifold is also connected to a regenerated natural gas manifold. The connection between the regenerated natural gas manifold and the outlet natural gas manifold is located between the regenerated gas flow meter 22 and the adjacent shut-off valve 2.

[0047] The regenerated gas heater 30 is also connected to a regenerated gas inlet manifold 15, an outlet heat transfer oil manifold, and an inlet heat transfer oil manifold. The regenerated gas inlet manifold 15 is connected to a regenerated gas outlet manifold 41 and an outlet natural gas manifold via pipelines.

[0048] Each molecular sieve dehydration tower is equipped with a programmable valve 5 on the pipelines connected to the adsorption inlet manifold 4, the regeneration gas outlet manifold 41, the adsorption outlet manifold 14, and the regeneration gas inlet manifold 15. The programmable valves 5 on the pipelines connected to the adsorption inlet manifold 4 and the regeneration gas outlet manifold 41 are all located above the top of the molecular sieve dehydration tower, while the programmable valves 5 on the pipelines connected to the adsorption outlet manifold 14 and the regeneration gas inlet manifold 15 are all located below the bottom of the molecular sieve dehydration tower.

[0049] A shut-off valve 2 is installed at the inlet of the inlet pipeline;

[0050] A shut-off valve 2 is installed on the renewable natural gas manifold;

[0051] The inlet and outlet of the regenerated gas compressor 29 are connected to the regenerated gas manifold of the outlet device through pipelines. Both pipelines are equipped with shut-off valves 2. A shut-off valve 2 is also installed between the two connection points of the regenerated gas manifold of the outlet device and the regenerated gas compressor 29.

[0052] A temperature detector A42 is installed on the regenerated gas outlet manifold 41 near the connection with the regenerated gas inlet manifold;

[0053] Each of the regenerated gas inlet manifold 15 is equipped with a programmable valve 5 on the connecting pipelines to the regenerated gas outlet manifold 41 and the natural gas outlet manifold.

[0054] Example 3

[0055] This embodiment provides a four-tower molecular sieve deep dehydration and internal / external circulation regeneration device for raw natural gas, such as... Figure 1 As shown, based on Example 2, the regenerated gas separator 28 is equipped with a level gauge 35, and a level regulating valve 36 is installed on the external condensate drain manifold. The level gauge 35 and the level regulating valve 36 constitute a temperature regulation loop.

[0056] A temperature detector B43 is installed on the regenerated gas inlet manifold 15 near the regenerated gas heater 30, and a heat transfer oil regulating valve 39 is installed on the heat transfer oil inlet manifold. The temperature detector B43 and the heat transfer oil regulating valve 39 form a temperature regulation circuit.

[0057] Example 4

[0058] The natural gas produced by the Upper Paleozoic gas reservoirs in Changqing Oilfield contains a certain amount of ethane light hydrocarbon components, with an average content of 5.4%. Its natural gas production reaches 300 × 10⁻⁶. 8 m 3 / a, where 200×10 8 m 3 / a can be centrally recycled. The raw natural gas processing capacity of the Changqing Oilfield Shanggu Natural Gas Processing Plant is 6000 × 10⁻⁶. 4 m 3 / d (20 billion / year), with a total of 4 sets of liquid hydrocarbon recovery and treatment units of the same scale, each unit having a processing capacity of 1500 × 10 4 m 3 The plant can recover 1.0527 million tons of ethane, 356,300 tons of liquefied petroleum gas, and 93,000 tons of stabilized light hydrocarbons annually, making it a plant with high economic recovery value.

[0059] The feedstock natural gas is the raw material for the natural gas ethane recovery project. The feedstock natural gas from outside the boundary area consists of methane, ethane, and C3. + It is composed of CO2, N2, H2, He, H2S, etc., of which methane accounts for 92.54% by volume, ethane accounts for 4.45% by volume, and C3... + Volume content: 1.1%, CO2 volume content: 1.26%, N2 volume content: 0.46%, H2 volume content: 0.09%, He volume content: 0.6%, H2S content: 8 mg / m³ 3 The water dew point is -5℃ to 5℃, its pressure is 4.1MPa, its temperature is 7℃ to 26℃, and its flow rate is 1500×10⁻⁶. 4 m 3 / d, a low-temperature distillation process is required to recover light hydrocarbon components such as ethane, with a minimum operating temperature of -100℃. To prevent moisture in the natural gas from freezing and clogging equipment and pipelines under low-temperature conditions, thus affecting the safe and stable operation of the system, deep dehydration of the raw natural gas is necessary. Due to the low pressure, large gas volume, and high CO2 content of the natural gas in the Shanggu gas reservoir of Changqing Oilfield, and the significant seasonal variations in water dew point, a process flow mode with multiple towers adsorbing simultaneously and single towers switching sequentially in a cycle is required.

[0060] This embodiment provides a method for deep dehydration and internal / external circulation regeneration of raw natural gas. A PLC controller is used to control the four-tower molecular sieve deep dehydration and internal / external circulation regeneration device for raw natural gas in Embodiment 3, achieving deep dehydration and circulation regeneration of the natural gas. The specific implementation steps are as follows:

[0061] Step 1: Pass the raw material natural gas 1 from outside the boundary into the pre-filter 3 to separate the impurities carried by the raw material natural gas 1 and obtain impurity-free natural gas;

[0062] Step 2: Connect the impurity-removed natural gas to the adsorption inlet manifold 4. Open the programmable valve 5 on the pipeline connecting each molecular sieve dehydration tower to the adsorption inlet manifold 4. The impurity-removed natural gas enters the molecular sieve dehydration tower from top to bottom for adsorption and dehydration to obtain dehydrated natural gas.

[0063] Step 3: The programmable valve 5 on the pipeline connecting each molecular sieve dehydration tower to the adsorption outlet manifold 14 is opened. The dehydrated natural gas is introduced into the post-filter 16 through the adsorption outlet manifold 14 to filter out the molecular sieve particles it carries, resulting in impurity-free dehydrated natural gas 18. This is then transported through the outlet natural gas manifold to the external liquid hydrocarbon recovery unit for recycling. After recycling, regenerated natural gas 19 is obtained. Regenerated natural gas 19 is composed of methane and C2. + Composed of CO2, N2, H2, He, H2S, etc., with methane accounting for 98.57% by volume and C2 + Volume content: 0.2%, CO2 volume content: 0.58%, N2 volume content: 0.49%, H2 volume content: 0.10%, He volume content: 0.63%, H2S content: 3.8 mg / m³ 3 The water content is 0.1 ppm, the pressure is 4.4 MPa, the temperature is 50℃, and the flow rate is 1490 × 10⁻⁶. 4 m 3 / d;

[0064] Step 4: Regenerated natural gas 19 is introduced into the regenerated natural gas manifold, and after being measured by the regenerated gas flow meter 22 and regulated by the regenerated gas regulating valve 23, it is divided into two paths. One path is used as regenerated heating gas, and the other path is used as regenerated cold blowing gas. The two gas paths are switched and controlled by the programmable valve 5.

[0065] Step 5: After the regenerated heating gas is heated by heat exchanger 26, it enters regenerated gas heater 30 for heating. The programmable valve 5 on the pipeline connected to the molecular sieve dehydration tower and adsorption inlet manifold 4 closest to the regenerated gas heater 30 is opened. The heated regenerated heating gas enters regenerated gas inlet manifold 15 and enters the molecular sieve dehydration tower from bottom to top to heat and regenerate the molecular sieve dehydration tower, resulting in secondary heated regenerated gas. The secondary heated regenerated gas is cooled by regenerated gas outlet manifold 41 and heat exchanger 26 and then enters regenerated gas air cooler 27 and regenerated gas separator 28 in sequence to obtain heated gas circulating regenerated gas with separated condensate water. The heated gas circulating regenerated gas is pressurized by regenerated gas compressor 29 to obtain regenerated gas 34 exiting the device. Regenerated gas 34 exiting the device is either exported or enters the inlet of pre-filter 3 for circulation.

[0066] Step 6: After being switched by process control valve 5, the regenerated cold blowing gas enters the regenerated gas inlet manifold from bottom to top to cool down the heated molecular sieve dehydration tower and obtain secondary regenerated cold blowing gas. The secondary regenerated cold blowing gas passes through the regenerated gas outlet manifold 41, gas-to-gas heat exchanger 26, regenerated gas air cooler 27, and regenerated gas separator 28 in sequence to obtain cold blowing gas circulation regenerated gas. The cold blowing gas circulation regenerated gas is pressurized by regenerated gas compressor 29 to obtain regenerated gas 34 exiting the device. The regenerated gas 34 exiting the device is either exported or enters the inlet of the pre-filter 3 for circulation.

[0067] The condensate 37 separated by the regenerated gas separator 28 in steps 5 and 6 is discharged to the wastewater treatment system through the condensate drain manifold.

[0068] The regenerated gas heater 30 introduces heat transfer oil from the heat transfer oil manifold into the heat transfer oil system outside the boundary area to achieve the heating purpose: the temperature of the heat transfer oil 38 entering the device is 315℃, and after heating, it is discharged from the heat transfer oil manifold of the device and returned to the heat transfer oil system outside the boundary area. The temperature of the heat transfer oil 40 exiting the device is not lower than 285℃.

[0069] In summary, the four-tower molecular sieve deep dehydration and internal / external circulation regeneration device for raw natural gas of this invention can serve as the main unit for deep dehydration of raw natural gas and co-absorption of some CO2 and H2S in the ancient natural gas ethane recovery project. This is the first time in my country that a single unit has achieved a processing capacity of 1500 × 10⁻⁶ tons in a natural gas ethane recovery project. 4 m 3 This invention relates to the application of deep dehydration of medium and low-pressure feedstock natural gas. The method for deep dehydration and internal and external circulation regeneration of feedstock natural gas adopts three towers for adsorption simultaneously, one tower for heating or cold blowing, and sequential switching of a single tower, which ensures the stable operation requirements of feedstock natural gas dehydration and provides a guarantee for the stable operation of key units in the low-temperature distillation section of the natural gas ethane recovery project.

Claims

1. A deep dehydration and internal and external circulation regeneration device for raw natural gas, characterized by, It includes four molecular sieve dehydration towers, each of which is connected by pipelines to an adsorption inlet manifold (4), a regenerated gas outlet manifold (41), an adsorption outlet manifold (14), and a regenerated gas inlet manifold (15). It also includes a gas-to-gas heat exchanger (26), a regenerated gas air cooler (27), a regenerated gas separator (28), a regenerated gas compressor (29), a regenerated gas heater (30), a pre-filter (3), and a post-filter (16). The inlet of the pre-filter (3) is provided with an inlet pipeline, and the outlet of the pre-filter (3) is connected to the adsorption air intake manifold (4); The gas-to-gas heat exchanger (26) is connected to the regenerated gas air cooler (27) and the regenerated gas heater (30) respectively via pipelines. The gas-to-gas heat exchanger (26) is also connected to the regenerated gas outlet manifold (41) and the natural gas outlet manifold. The regenerated gas air cooler (27) is connected to the regenerated gas separator (28) via a pipeline; The regenerated gas separator (28) is connected to the outlet regenerated gas manifold and the external condensate manifold respectively. The outlet regenerated gas manifold is connected to the regenerated gas compressor (29). A shut-off valve (2) is provided at the outlet of the outlet regenerated gas manifold. The outlet regenerated gas manifold is connected to the inlet pipeline of the pre-filter (3) through the pipeline with the shut-off valve (2). The connection point between the outlet regenerated gas manifold and the inlet pipeline of the pre-filter (3) is located between the shut-off valve (2) at the outlet of the outlet regenerated gas manifold and the regenerated gas compressor (29). The inlet of the post-filter (16) is connected to the adsorption outlet manifold (14), and the outlet is connected to the outlet natural gas manifold via a pipeline. The outlet natural gas manifold is equipped with a programmable valve (5), a regenerated gas regulating valve (23), a regenerated gas flow meter (22), and two shut-off valves (2) in sequence from the gas-to-gas heat exchanger (26) to the outlet of the outlet natural gas manifold. The connection between the post-filter (16) and the outlet natural gas manifold is located between the two shut-off valves (2). The outlet natural gas manifold is also connected to a regenerated natural gas manifold. The connection between the regenerated natural gas manifold and the outlet natural gas manifold is located between the regenerated gas flow meter (22) and the adjacent shut-off valve (2). The regenerated gas heater (30) is also connected to a regenerated gas inlet manifold (15), a heat transfer oil manifold for the device outlet, and a heat transfer oil manifold for the device inlet. The regenerated gas inlet manifold (15) is connected to a regenerated gas outlet manifold (41) and a natural gas outlet manifold for the device outlet via pipelines. Each of the molecular sieve dehydration towers is equipped with a programmable valve (5) on the pipelines connected to the adsorption inlet manifold (4), the regeneration gas outlet manifold (41), the adsorption outlet manifold (14), and the regeneration gas inlet manifold (15). The programmable valves (5) on the pipelines connected to the adsorption inlet manifold (4) and the regeneration gas outlet manifold (41) are all located above the top of the molecular sieve dehydration tower, while the programmable valves (5) on the pipelines connected to the adsorption outlet manifold (14) and the regeneration gas inlet manifold (15) are all located below the bottom of the molecular sieve dehydration tower.

2. The deep dehydration and internal and external circulation regeneration apparatus for raw natural gas according to claim 1, characterized by A shut-off valve (2) is installed at the inlet of the inlet pipeline; The recycled natural gas manifold is equipped with a shut-off valve (2). The inlet and outlet of the regenerated gas compressor (29) are connected to the regenerated gas manifold of the outlet device through pipelines. Both pipelines are equipped with shut-off valves (2). A shut-off valve (2) is also provided between the two connection points of the regenerated gas manifold of the outlet device and the regenerated gas compressor (29). A temperature detector A (42) is installed on the regenerated gas outlet manifold (41) near the connection with the regenerated gas inlet manifold. Each of the regenerated gas inlet manifold (15) is equipped with a programmable valve (5) on the connecting pipelines to the regenerated gas outlet manifold (41) and the natural gas outlet manifold.

3. The raw natural gas deep dehydration and internal and external circulation regeneration device according to claim 1, characterized in that, The regenerated gas separator (28) is equipped with a level gauge (35), and the external condensate drain pipe is equipped with a level regulating valve (36). The level gauge (35) and the level regulating valve (36) constitute a temperature regulating circuit.

4. The deep dehydration and internal / external circulation regeneration device for raw natural gas according to claim 1, characterized in that, A temperature detector B (43) is installed on the regenerated gas inlet manifold (15) near the regenerated gas heater (30), and a heat transfer oil regulating valve (39) is installed on the heat transfer oil manifold of the inlet device. The temperature detector B (43) and the heat transfer oil regulating valve (39) constitute a temperature regulation circuit.

5. A method for deep dehydration and internal / external circulation regeneration of raw natural gas, wherein a PLC controller is used to control the deep dehydration and internal / external circulation regeneration device for raw natural gas as described in claim 1, thereby achieving deep dehydration and circulation regeneration of natural gas, characterized in that... The specific steps are as follows: Step 1: Pass the raw natural gas (1) from outside the boundary area into the pre-filter (3) to separate the impurities carried by the raw natural gas (1) and obtain impurity-free natural gas; Step 2: Connect the impurity-removed natural gas to the adsorption inlet manifold (4). Open the programmable valve (5) on the pipeline connecting each molecular sieve dehydration tower to the adsorption inlet manifold (4). The impurity-removed natural gas enters the molecular sieve dehydration tower from top to bottom for adsorption and dehydration to obtain dehydrated natural gas. Step 3: The programmable valve (5) on the pipeline connecting each molecular sieve dehydration tower to the adsorption outlet manifold (14) is opened. The dehydrated natural gas is introduced into the post-filter (16) through the adsorption outlet manifold (14) to filter out the molecular sieve particles it carries, and obtain the impurity-removed dehydrated natural gas (18). It is then transported to the liquid hydrocarbon recovery unit outside the boundary for recycling treatment through the natural gas manifold of the outlet unit, and after recycling treatment, the recycled natural gas (19) is obtained. Step 4: Regenerated natural gas (19) is introduced into the regenerated natural gas manifold and metered by the regenerated gas flow meter (22) and regulated by the regenerated gas regulating valve (23). It is then divided into two paths, one of which is used as regenerated heating gas and the other is used as regenerated cold blowing gas. The two gas paths are switched and controlled by the programmable valve (5). Step 5: After the regenerated heating gas is heated by heat exchanger (26), it enters the regenerated gas heater (30) for heating. The programmable valve (5) on the pipeline connected to the molecular sieve dehydration tower and the adsorption inlet manifold (4) closest to the regenerated gas heater (30) is opened. After the heated regenerated heating gas enters the regenerated gas inlet manifold (15), it enters the molecular sieve dehydration tower from bottom to top to heat and regenerate the molecular sieve dehydration tower, and obtains secondary heated regenerated gas. The secondary heated regenerated gas is cooled by regenerated gas outlet manifold (41) and gas-to-gas heat exchanger (26) and then enters the regenerated gas air cooler (27) and regenerated gas separator (28) in sequence to obtain heated gas circulating regenerated gas with separated condensate water. The heated gas circulating regenerated gas is pressurized by regenerated gas compressor (29) to obtain regenerated gas (34) of the device. The regenerated gas (34) of the device is output or enters the inlet of the pre-filter (3) for circulation. Step 6: After switching the regenerated cold blowing gas through the process control valve (5), it enters the regenerated gas inlet manifold from bottom to top to cool down the heated molecular sieve dehydration tower and obtain the secondary regenerated cold blowing gas. The secondary regenerated cold blowing gas passes through the regenerated gas outlet manifold (41), gas-to-gas heat exchanger (26), regenerated gas air cooler (27), and regenerated gas separator (28) in sequence to obtain cold blowing gas circulation regenerated gas. The cold blowing gas circulation regenerated gas is pressurized by the regenerated gas compressor (29) to obtain the outlet regenerated gas (34). The outlet regenerated gas (34) (3) is circulated at the inlet.

6. The method for deep dehydration and internal / external circulation regeneration of raw natural gas according to claim 5, characterized in that, The condensate (37) separated by the regenerated gas separator (28) in steps 5 and 6 is discharged to the sewage treatment system through the condensate drain manifold.

7. The method for deep dehydration and internal / external circulation regeneration of raw natural gas according to claim 5, characterized in that, The regenerated gas heater (30) is heated by introducing heat transfer oil into the heat transfer oil system outside the boundary area through the heat transfer oil manifold of the inlet device. After heating, it is discharged from the heat transfer oil manifold of the outlet device and returned to the heat transfer oil system outside the boundary area.

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