Helium extraction system combined with natural gas denitrification liquefaction process

Abstract

The utility model discloses a helium extraction system combined with a natural gas denitrification liquefaction process, which comprises a denitrification tower, the denitrification tower is provided with a cooling capacity inlet pipe and a cooling capacity outlet pipe, the top of the denitrification tower is connected with a gas-liquid separation tank, the top of the gas-liquid separation tank is provided with a non-condensable gas pipeline, and the top of the non-condensable gas pipeline is provided with a gas outlet pipe. One end, far away from the gas-liquid separation tank, of the non-condensable gas pipeline is connected with the low-temperature heat exchanger, and non-condensable gas at the top of the denitrification tower enters the low-temperature heat exchanger, the membrane separation system, the dehydrogenation device and the pressure swing adsorption device from the non-condensable gas pipeline to obtain high-purity denitrified helium; and desorbed gas in the pressure swing adsorption device is conveyed into the membrane separation system for secondary helium extraction. According to the utility model, a dehydration device is not needed, water can be discharged from the separator at the permeable gas pressurization outlet after membrane separation, the process is simple, the operation is convenient, meanwhile, the recovery rate of helium in the whole system is improved, and high-purity helium is obtained.

Description

Technical Field

[0001] The utility model relates to the technical field of liquefied natural gas denitrification, in particular to a helium extraction system combined with a natural gas denitrification liquefaction process. Background Art

[0002] At room temperature, helium is an extremely light, colorless, odorless, and tasteless monatomic gas. It is the most difficult of all gases to liquefy and cannot solidify at standard atmospheric pressure. After liquefaction, when the temperature drops to 2.174K, it exhibits unique properties such as low surface tension, strong thermal conductivity, and extremely low viscosity. Helium is used as a pressurizing agent and booster for rocket liquid fuel, a shielding gas in smelting and welding, and has excellent permeability. Helium has low mass and weight densities and is non-flammable. Liquid helium can be used in the manufacture of superconducting devices.

[0003] Extracting helium from natural gas not only safeguards my country's helium resources but also improves the overall utilization efficiency of natural gas and the economic benefits of liquefied natural gas plants. Existing helium extraction systems and processes are complex, with low helium recovery rates. Utility Model Content

[0004] The purpose of the utility model is to provide a helium extraction system combined with a natural gas denitrification liquefaction process. The helium extraction system, which consists of a denitrification tower, a low-temperature heat exchanger, a membrane separation system, a dehydrogenation device, a pressure swing adsorption device, etc., concentrates the denitrified natural gas tail gas to extract helium without the need for a dehydration device, thereby achieving high-purity helium purification and solving the above-mentioned problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention adopts the following solutions:

[0006] A helium extraction system combined with a natural gas denitrification liquefaction process comprises a denitrification tower provided with a cold inlet pipe and a cold outlet pipe, a gas-liquid separation tank connected to the top of the denitrification tower, a non-condensable gas pipeline provided on the top of the gas-liquid separation tank, and a low-temperature heat exchanger connected to the non-condensable gas pipeline at one end away from the gas-liquid separation tank. The non-condensable gas at the top of the denitrification tower enters the low-temperature heat exchanger, a membrane separation system, a dehydrogenation device and a pressure swing adsorption device through the non-condensable gas pipeline to obtain high-purity denitrified helium. The desorbed gas in the pressure swing adsorption device is transported to the membrane separation system for secondary helium extraction.

[0007] Preferably, the pressure swing adsorption device is connected to the filling compressor, the compressor outlet cooler and the helium filling system in sequence by arranging a pipeline mechanism, so as to be used for filling the helium after denitrification.

[0008] Preferably, the pipeline structure includes a first pipeline, a second pipeline, a third pipeline and a reflux pipeline, the first pipeline is located between the low-temperature heat exchanger and the membrane separation system, the second pipeline is located between the membrane separation system and the dehydrogenation device, the third pipeline is located between the dehydrogenation device and the pressure swing adsorption device, and the reflux pipeline is located between the pressure swing adsorption device and the membrane separation system.

[0009] Preferably, the pipeline mechanism also includes a fourth pipeline, a fifth pipeline and a sixth pipeline, the fourth pipeline is located between the pressure swing adsorption device and the filling compressor, the fifth pipeline is located between the filling compressor and the compressor outlet cooler, and the sixth pipeline is located between the compressor outlet cooler and the helium filling system.

[0010] Preferably, a discharge pipeline for discharging non-permeated gas is provided at the top of the membrane separation system.

[0011] Preferably, the dehydrogenation device is connected to the oxygen supply device to remove hydrogen from the concentrated helium.

[0012] Preferably, the operating pressure of the denitrification tower is 2 to 30 bar.

[0013] Preferably, each pipeline in the pipeline mechanism is provided with a valve.

[0014] The utility model has the beneficial effects that the moisture generated in the dehydrogenation process of the system can be separated by a pressure swing adsorption device, and the desorbed gas in the pressure swing adsorption device is returned to the membrane separation system. In this process, water circulates in the normal temperature area, and there is no need to set up a dehydration device. The moisture can be discharged from the separator at the permeate boost outlet after membrane separation. The process is simple and easy to operate. At the same time, the recovery rate of helium in the whole system is improved, and high-purity helium is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural diagram of the present utility model.

[0016] Figure numerals: 1-denitrification tower, 10-cold inlet pipe, 11-cold outlet pipe, 12-non-condensable gas pipeline, 2-low-temperature heat exchanger, 3-membrane separation system, 4-dehydrogenation device, 5-pressure swing adsorption device, 6-filling compressor, 7-compressor outlet cooler, 8-helium filling system, 90-first pipeline, 91-second pipeline, 92-third pipeline, 93-fourth pipeline, 94-fifth pipeline, 95-sixth pipeline, 96-reflux pipeline, 97-discharge pipeline, 100-oxygen supply device, 110-gas-liquid separation tank. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below in conjunction with the embodiments and drawings, but the implementation manner of the present invention is not limited thereto.

[0018] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inside", "outside", "front", "back", "top", "bottom", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the utility model product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0019] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "opened," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0020] Example 1

[0021] Embodiment 1 of the present invention is a helium extraction system combined with a natural gas denitrification liquefaction process, characterized in that it includes a denitrification tower 1, the denitrification tower 1 is provided with a cold inlet pipe 10 and a cold outlet pipe 11, the top of the denitrification tower 1 is connected to a gas-liquid separation tank 110, the top of the gas-liquid separation tank 110 is provided with a non-condensable gas pipeline 12, the end of the non-condensable gas pipeline 12 away from the gas-liquid separation tank 110 is connected to a low-temperature heat exchanger 2, the non-condensable gas at the top of the denitrification tower 1 enters the low-temperature heat exchanger 2, the membrane separation system 3, the dehydrogenation device 4 and the pressure swing adsorption device 5 from the non-condensable gas pipeline 12 to obtain high-purity denitrified helium, and the desorbed gas in the pressure swing adsorption device 5 is transported to the membrane separation system 3 for secondary helium extraction.

[0022] Specifically, if Figure 1As shown, the system of the present invention is combined with the natural gas liquefaction and denitrogenation process to produce high-purity helium. The non-condensable gas, approximately 2 to 30 bar, exits the top of the low-temperature denitrogenation tower 1 during the nitrogen-containing natural gas denitrogenation and liquefaction process. It is then reheated to room temperature after recovering its cooling capacity through a low-temperature heat exchanger 2. The non-condensable gas then passes through a membrane separation system 3 to separate the nitrogen, then enters a dehydrogenation unit 4 for dehydrogenation. It then enters a pressure swing adsorption unit 5 to obtain high-purity helium (99.99 to 99.999%), which is then bottled as finished helium. The desorbed gas from the pressure swing adsorption unit 5 is returned to the inlet of the membrane separation system 3 for recycling, where the helium in the desorbed gas is recovered. The gas then passes through the dehydrogenation unit 4 and the pressure swing adsorption unit 5 for secondary helium extraction, thereby improving the helium recovery rate of the entire system.

[0023] It should be noted that non-condensable gases are gases that cannot be liquefied within the condensing device under certain temperature and pressure conditions. In this embodiment, non-condensable gases primarily include nitrogen and helium. The membrane separation system 3 can perform single-stage or multi-stage separation of non-condensable gases from nitrogen. The non-permeate gas (primarily nitrogen) generated within the membrane separation system 3 is discharged to the outside. The cooling inlet pipe 10 is located in the middle of the denitrification tower 1.

[0024] The denitrification tower 1 is connected to the top and bottom of the gas-liquid separation tank 110 respectively, and is divided into a bottom pipe and a top pipe (not numbered in the figure). The material inside the denitrification tower 1 enters the gas-liquid separation tank 110 through the top pipe, and the liquid after gas-liquid separation enters the denitrification tower 1 through the bottom pipe for material reflux, and the gas enters the membrane separation system 3 through the non-condensable gas pipe 12.

[0025] In some preferred embodiments, the pressure swing adsorption device 5 is sequentially connected to a charging compressor 6, a compressor outlet cooler 7, and a helium filling system 8 via a pipeline mechanism for filling the denitrified helium. Specifically, the denitrified helium is pressurized and filled by the filling compressor 6, thereby forming a complete helium production and filling system.

[0026] In some preferred embodiments, the pipeline structure includes a first pipeline 90, a second pipeline 91, a third pipeline 92 and a reflux pipeline 96, the first pipeline 90 is located between the low-temperature heat exchanger 2 and the membrane separation system 3, the second pipeline 91 is located between the membrane separation system 3 and the dehydrogenation device 4, the third pipeline 92 is located between the dehydrogenation device 4 and the pressure swing adsorption device 5, and the reflux pipeline 96 is located between the pressure swing adsorption device 5 and the membrane separation system 3.

[0027] Specifically, the nitrogen-rich tail gas generated in the denitrification tower 1 enters the low-temperature heat exchanger 2 from the non-condensable gas pipeline 12 for reheating. The temperature after reheating reaches 5°C to 30°C, and enters the membrane separation system 3 through the first pipeline 90. At this time, the concentrated helium entering the membrane separation system 3 still contains a small amount of impurity components such as hydrogen, methane, and nitrogen. It enters the dehydrogenation device 4 through the second pipeline 91 for dehydrogenation and generates water. Oxygen is introduced into the dehydrogenation device 4 for catalytic reaction to remove other impurities such as hydrogen, methane, nitrogen and water. At the same time, the impurities removed by catalysis enter the pressure swing adsorption device 5 through the nitrogen-rich pipeline and are returned to the membrane separation system 3 as desorbed gas through the reflux pipeline 96 for circulation and recovery of the ammonia component therein, thereby improving the recovery rate of ammonia.

[0028] It should be noted that the moisture generated during the dehydrogenation process can be separated by the pressure swing adsorption device 5, and the desorbed gas in the pressure swing adsorption device 5 is returned to the inlet of the membrane separation system 3. In the entire process, water circulates in the normal temperature area, and there is no need to set up a dehydration device. The moisture can be discharged from the separator at the permeate boost outlet after membrane separation. The operation process is simple and easy to operate.

[0029] The low-temperature non-condensable gas (mainly including nitrogen and helium) transmitted from the top of the denitrification tower 1 is reheated through the low-temperature heat exchanger 2 to recover cold energy. It can also be reheated to room temperature without passing through the low-temperature heat exchanger 2 using other heat sources, such as natural gas heat source.

[0030] In some preferred embodiments, the pipeline mechanism further includes a fourth pipeline 93, a fifth pipeline 94, and a sixth pipeline 95. The fourth pipeline 93 is located between the pressure swing adsorption device 5 and the filling compressor 6, the fifth pipeline 94 is located between the filling compressor 6 and the compressor outlet cooler 7, and the sixth pipeline 95 is located between the compressor outlet cooler 7 and the helium filling system 8. Specifically, the integrated denitrification and helium extraction of concentrated ammonia and its filling are achieved.

[0031] In some preferred embodiments, a discharge pipeline 97 for discharging non-permeated gas is provided at the top of the membrane separation system 3. Specifically, the non-permeated gas here is mainly nitrogen.

[0032] In some preferred embodiments, the dehydrogenation device 4 is connected to an oxygen supply device 100 to remove hydrogen from the concentrated helium. Specifically, the oxygen supply device 100 is used to provide oxygen to the interior of the dehydrogenation device 4 for a catalytic reaction, removing other impurities such as hydrogen, methane, nitrogen, and water, and generating water through the catalytic reaction. The oxygen supply amount is set according to actual conditions.

[0033] In some preferred embodiments, the operating pressure of the denitrification tower 1 is 2 to 30 bar. Specifically, the operating pressure of the denitrification tower 1 can be adjusted within the range of 2 to 30 bar according to the requirements of the back-end high-purity helium extraction device, including the membrane separation system 3 and the dehydrogenation pressure swing adsorption device 5.

[0034] In some preferred embodiments, each pipeline in the pipeline mechanism is provided with a valve.

[0035] When the present invention is in use, the nitrogen-rich tail gas generated during normal operation of the natural gas denitrification tower 1 is reheated (5°C to 30°C) by the low-temperature heat exchanger 2 and then passes through the membrane separation system 3. The concentrated helium still contains a small amount of impurities such as hydrogen, methane, and nitrogen. The concentrated helium first passes through the dehydrogenation device 4, where oxygen is added to catalyze the reaction to remove hydrogen from the concentrated helium and generate water; then it enters the pressure swing adsorption device 5 for purification to remove other impurities such as hydrogen, methane, nitrogen, and water. The above impurity gases contain a considerable amount of helium, which is returned to the membrane separation system 3 as the desorbed gas from the pressure swing adsorption device 5 for circulation and recovery of the helium component therein; the purified high-purity helium is then sequentially passed through the filling compressor 6, the compressor outlet cooler 7, and the helium filling system 8 for filling and transportation. The moisture generated during the dehydrogenation process of this system can be separated by the pressure swing adsorption device 5, and the desorbed gas in the pressure swing adsorption device 5 is returned to the membrane separation system 3. In this process, water circulates in the normal temperature area, and there is no need to set up a dehydration device. The moisture can be discharged from the separator at the permeate gas pressurization outlet after membrane separation. The process is simple and easy to operate. At the same time, the helium recovery rate of the entire system is improved, and high-purity helium is obtained.

[0036] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Based on the technical essence of the present invention and within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement of the above embodiment shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A helium extraction system combined with a natural gas denitrification liquefaction process, characterized in that: The invention comprises a denitrification tower (1), wherein the denitrification tower (1) is provided with a cold inlet pipe (10) and a cold outlet pipe (11), the top of the denitrification tower (1) is connected to a gas-liquid separation tank (110), the top of the gas-liquid separation tank (110) is provided with a non-condensable gas pipeline (12), the end of the non-condensable gas pipeline (12) away from the gas-liquid separation tank (110) is connected to a low-temperature heat exchanger (2), the non-condensable gas at the top of the denitrification tower (1) enters the low-temperature heat exchanger (2), the membrane separation system (3), the dehydrogenation device (4) and the pressure swing adsorption device (5) from the non-condensable gas pipeline (12) to obtain high-purity denitrified helium, and the desorbed gas in the pressure swing adsorption device (5) is transported to the membrane separation system (3) for secondary helium extraction.

2. A helium extraction system combined with a natural gas denitrification liquefaction process according to claim 1, characterized in that: The pressure swing adsorption device (5) is connected to the filling compressor (6), the compressor outlet cooler (7) and the helium filling system (8) in sequence by arranging a pipeline mechanism, and is used for filling the helium after denitrification.

3. A helium extraction system combined with a natural gas denitrification liquefaction process according to claim 2, characterized in that: The pipeline structure comprises a first pipeline (90), a second pipeline (91), a third pipeline (92) and a reflux pipeline (96); the first pipeline (90) is located between the low-temperature heat exchanger (2) and the membrane separation system (3); the second pipeline (91) is located between the membrane separation system (3) and the dehydrogenation device (4); the third pipeline (92) is located between the dehydrogenation device (4) and the pressure swing adsorption device (5); and the reflux pipeline (96) is located between the pressure swing adsorption device (5) and the membrane separation system (3).

4. A helium extraction system combined with a natural gas denitrification liquefaction process according to claim 2, characterized in that: The pipeline mechanism further comprises a fourth pipeline (93), a fifth pipeline (94) and a sixth pipeline (95), wherein the fourth pipeline (93) is located between the pressure swing adsorption device (5) and the filling compressor (6), the fifth pipeline (94) is located between the filling compressor (6) and the compressor outlet cooler (7), and the sixth pipeline (95) is located between the compressor outlet cooler (7) and the helium filling system (8).

5. A helium extraction system combined with a natural gas denitrification liquefaction process according to claim 2, characterized in that: The top of the membrane separation system (3) is provided with a discharge pipeline (97) for discharging non-permeated gas.

6. The helium extraction system combined with the natural gas denitrification liquefaction process according to claim 3, characterized in that: The dehydrogenation device (4) is connected to the oxygen supply device (100) to remove hydrogen from the concentrated helium.

7. The helium extraction system combined with the natural gas denitrification liquefaction process according to claim 3, characterized in that: The operating pressure of the denitrification tower (1) is 2 to 30 bar.

8. The helium extraction system combined with the natural gas denitrification liquefaction process according to claim 3, characterized in that: Each pipeline in the pipeline mechanism is equipped with a valve.

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