Natural gas pressure swing adsorption device

Abstract

The utility model relates to the technical field of natural gas purification, in particular to a natural gas pressure swing adsorption device. The natural gas pressure swing adsorption device comprises a 3.5 MPa natural gas inlet pipeline, the 3.5 MPa natural gas inlet pipeline is connected with a heater A through a filter element type filter A, the heater A is connected with an adsorption tower through a buffer tank, a flow meter A is arranged between the filter element type filter A and the heater A, the flow meter A is connected with a natural gas and refrigerant heat exchanger through an expansion machine, and the expansion machine is connected with the natural gas and refrigerant heat exchanger. The natural gas and refrigerant heat exchanger is connected with the buffer tank through a pipeline. According to the device, the cleanliness of raw materials entering a factory is ensured by regularly switching the filters and replacing the filter elements of the filters. And the metering of the gas consumption of the downstream gas consumption device is realized through the flow meter. And the high-pressure natural gas is heated through the natural gas heater, so that gas temperature reduction caused by pressure reduction of the system is prevented.

Description

Technical Field

[0001] This utility model relates to the field of natural gas purification technology, specifically a natural gas pressure swing adsorption device. Background Technology

[0002] In many production facilities that use natural gas as a key feedstock, such as natural gas-to-hydrogen units and methane-based hydrogen cyanide units, the purity of methane in the natural gas plays a crucial role. It's important to understand that natural gas is not solely composed of methane; it also contains other alkane components. As the content of these other alkane components gradually increases, it can cause significant problems for the production unit. During production, these additional alkanes react on the catalyst surface, causing carbonization. Once carbonization occurs, the active sites of the catalyst are covered or destroyed, making it difficult for reactant molecules to combine effectively and react efficiently, thus significantly reducing the reaction rate. The originally efficient and orderly production process can be disrupted, and the output efficiency and quality of the product may fail to meet expected standards. Furthermore, sulfur in natural gas can also cause catalyst poisoning and deactivation, making the purification of natural gas from external pipelines particularly important. In practice, existing facilities often suffer from incomplete purification and depressurization, resulting in low purification efficiency. Utility Model Content

[0003] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a natural gas pressure swing adsorption device, which uses two filters to perform primary filtration of solid impurities contained in the incoming natural gas. By periodically switching the filters and replacing the filter elements, the cleanliness of the incoming raw materials is ensured.

[0004] This utility model is achieved using the following technical solution:

[0005] The natural gas pressure swing adsorption device includes a 3.5MPa natural gas inlet pipeline, which is connected to a heater A via a cartridge filter A. The heater A is connected to the adsorption tower via a buffer tank. A flow meter A is installed between the cartridge filter A and the heater A. The flow meter A is connected to a natural gas and refrigerant heat exchanger via an expander. The natural gas and refrigerant heat exchanger is connected to the buffer tank via a pipeline.

[0006] The 3.5MPa natural gas inlet pipeline is connected to heater B via a cartridge filter B, and heater B is connected to a buffer tank via a pipeline.

[0007] A pressure reducing valve A is provided between the heater A and the buffer tank, and a flow meter B is provided between the filter cartridge B and the heater B. The flow meter B is connected to the pipeline expander.

[0008] The adsorption tower is connected to a purified natural gas outlet pipe, which is connected to an online purified natural gas chromatograph. The adsorption tower is connected to a buffer tank via a backup pipeline programmable valve, and a backup pipeline is provided between the backup pipeline programmable valve and the buffer tank.

[0009] A temperature measuring port and a one-way valve are provided between the expander and the natural gas and refrigerant heat exchanger.

[0010] The expander is connected to the compressor via a generator, and the compressor is connected to the refrigerant and chilled water heat exchanger via a natural gas and refrigerant heat exchanger. The refrigerant and chilled water heat exchanger is connected to the compressor via a return pipe.

[0011] An expansion valve and a temperature detection port are provided between the natural gas and refrigerant heat exchanger and the refrigerant and chilled water heat exchanger.

[0012] The refrigerant and chilled water heat exchanger are connected to the chilled water pump via a chilled water tank. The chilled water pump is connected to the heat exchanger and refrigerant via chilled water.

[0013] After the 3.5MPa high-pressure natural gas from the external pipeline enters the unit through the boundary valve, it first undergoes primary filtration of solid impurities such as rust in the natural gas through a filter cartridge filter. The filtered natural gas is then divided into three streams after passing through a flow meter. One stream enters the natural gas expander, which is driven by the high-pressure natural gas to run at high speed. The expander drives the generator to generate electricity, which in turn drives the compressor to do work, and then pressurizes the refrigerant. The pressurized refrigerant exchanges heat with the natural gas from the expander outlet. The heat-exchanged natural gas is then merged into the raw material gas buffer tank through a valve. The refrigerant, after being cooled by heat exchange, is cooled a second time to -20℃ through the expansion valve. The expanded refrigerant then exchanges heat with the chilled water and returns to the compressor inlet. The cooled chilled water enters the chilled water tank and is then pumped to various cold and heat exchange equipment by the chilled water pump. The other two streams (one for use and one as backup) enter the natural gas heater and are heated to 80°C. The pressure is then reduced from 3.5 MPa to 1.0 MPa via a pressure reducing valve. The reduced pressure (1.0 MPa) natural gas enters the natural gas buffer tank, and then sequentially enters the adsorption tower through a programmable valve according to the system's predetermined procedure for adsorption and purification. Physical adsorption refers to adsorption that relies on the molecular forces between the adsorbent and adsorbate molecules. Its characteristics are: no chemical reaction occurs during adsorption; the adsorption process is extremely rapid; the equilibrium between the various phases involved in adsorption is achieved instantaneously; and this adsorption is completely reversible.

[0014] Compared with the prior art, the beneficial effects of this utility model are:

[0015] (1) This device uses two filters to perform primary filtration of solid impurities in the incoming natural gas. By periodically switching filters and replacing filter elements, the cleanliness of the incoming raw materials is ensured. A flow meter is used to measure the gas consumption of downstream gas-using devices. A natural gas heater is used to heat the high-pressure natural gas to prevent the gas temperature from dropping due to system depressurization. By adding pressure reducing valves to the two lines of heated high-pressure natural gas, the 1.0MPa natural gas pipeline network is always in a standby state, so that if one pressure reducer fails or is taken offline for maintenance and adjustment, the other line can still operate normally. The natural gas pipeline after depressurization is equipped with thermometers and pressure gauges to realize real-time monitoring of the operating status of the natural gas after depressurization.

[0016] (2) Vent valves and venting lines are installed between the natural gas filter, natural gas flow meter, and natural gas pressure reducing valve. When the natural gas filter needs cleaning or the flow meter and pressure reducing valve need to be taken offline for calibration and maintenance, the pressure can be released by disconnecting the hand valves before and after it and through the vent valves and venting lines. To ensure effective utilization of high-pressure natural gas, a separate high-pressure natural gas line is led out after the flow meter into the expander. The expander generates electricity, which is then connected to the grid, reducing the device's power consumption. A check valve is installed on the natural gas pipeline at the expander outlet to prevent backflow of 1.0MPa pipeline natural gas to the expander outlet when the expander outlet pressure drops.

[0017] (3) After the adsorption process is completed, multiple pressure equalization and depressurization are completed through programmable valves (programmable valves on other pipelines). During the entire depressurization process, the natural gas is introduced into other lower pressure adsorption towers that have completed regeneration along the adsorption direction. This process is not only a depressurization process, but also a process of recovering CH4 gas in the bed blind space. The multiple continuous pressure equalization and depressurization processes in this process can ensure that CH4 is fully recovered.

[0018] (4) After the equalization and depressurization process is completed, in order to ensure the adsorbent is completely regenerated, the adsorption bed is evacuated by a programmable valve (other programmable valves on the vacuum pump pipeline) and the vacuum pump in the opposite direction of adsorption to further reduce the partial pressure of impurity components and ensure the adsorbent is completely regenerated. After the vacuuming process is completed, the adsorption tower is pressurized sequentially with higher-pressure CH4 gas from other adsorption towers. This process corresponds to the equalization and depressurization process and is not only a pressurization process but also a process of recovering CH4 gas from the dead space of the beds of other towers. To ensure the CH4 gas recovery rate, this process includes multiple consecutive equalization and pressurization processes.

[0019] (5) After the adsorption tower completes the final step of pressurization (i.e., equalization), in order to ensure that the next adsorption process can be smoothly switched to the next adsorption process and to ensure that the product purity does not fluctuate during this process, the pressure of the adsorption tower is slowly and smoothly increased to the adsorption working pressure by purified natural gas through the final pressurization regulating valve.

[0020] (6) By using the A / B series vacuum system connecting valve of the vacuum system, the A / B series adsorption towers can be vacuumed by different vacuum pumps, which is more conducive to the stability of the vacuum system.

[0021] (7) The backup pipeline control valve can be used as an emergency backup cross-line for the pressure swing adsorption system. In the event of a system failure, the natural gas before purification and the natural gas after purification can be connected in series by starting the backup pipeline control valve, thus avoiding the downstream gas supply interruption caused by the system failure.

[0022] (8) A separate branch is led out from the top of the adsorption tower before the device exits to the online chromatograph to analyze the purified natural gas. The natural gas from the online analyzer enters the flare network through a one-way valve. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the natural gas pressure swing adsorption device of this utility model;

[0024] In the diagram: 1. 3.5MPa natural gas inlet pipeline; 2. Cartridge filter A; 3. Cartridge filter B; 4. Flow meter A; 5. Flow meter B; 6. Heater A; 7. Heater B; 8. Compressor; 9. Expander; 10. Buffer tank; 11. Adsorption tower; 12. Purified natural gas online chromatograph; 13. Return pipeline; 14. Generator; 15. Pressure reducing valve A; 16. Temperature measuring port; 17. Purified natural gas outlet pipeline; 18. Backup pipeline; 19. Backup pipeline programmable valve; 20. Check valve; 21. Natural gas and refrigerant heat exchanger; 22. Refrigerant and chilled water heat exchanger; 23. Chilled water tank; 24. Expansion valve; 25. Temperature sensing port; 26. Chilled water pump; 27. Chilled water inlet heat exchangers of various units. Detailed Implementation

[0025] To make the objectives and technical solutions of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings.

[0026] Example 1

[0027] like Figure 1As shown, the natural gas pressure swing adsorption (PSA) device includes a 3.5 MPa natural gas inlet pipe 1, which is connected to a heater A6 via a cartridge filter A2. The heater A6 is connected to an adsorption tower 11 via a buffer tank 10. A flow meter A4 is installed between the cartridge filter A2 and the heater A6. The flow meter A4 is connected to a natural gas-refrigerant heat exchanger 21 via an expander 9. The natural gas-refrigerant heat exchanger 21 is connected to the buffer tank 10 via a pipe. The 3.5 MPa natural gas inlet pipe 1 is connected to a heater B7 via a cartridge filter B3. The heater B7 is connected to the buffer tank 10 via a pipe. A pressure reducing valve A15 is installed between the heater A6 and the buffer tank 10. A flow meter B5 is installed between the cartridge filter B3 and the heater B7. The flow meter B5 is connected to the expander 9 via a pipe. The adsorption tower 11 is connected to a purified natural gas outlet pipe 17, which is connected to an online purified natural gas chromatograph 12. The adsorption tower 11 is connected to a buffer tank 10 via a backup pipe programmable valve 19, and a backup pipe 18 is provided between the backup pipe programmable valve 19 and the buffer tank 10. A temperature measuring port 16 and a one-way valve 20 are provided between the expander 9 and the natural gas and refrigerant heat exchanger 21. The expander 9 is connected to the compressor 8 via a generator 14, and the compressor 8 is connected to the refrigerant and chilled water heat exchanger 22 via the natural gas and refrigerant heat exchanger 21. The refrigerant and chilled water heat exchanger 22 is connected to the compressor 8 via a return pipe 13. An expansion valve 24 and a temperature detection port 25 are provided between the natural gas and refrigerant heat exchanger 21 and the refrigerant and chilled water heat exchanger 22. The refrigerant and chilled water heat exchanger 22 is connected to the chilled water pump 26 through the chilled water tank 23. The chilled water pump 26 is connected to the heat exchanger 27 of each device and the refrigerant and chilled water heat exchanger 22 through the chilled water inlet.

[0028] The above-mentioned natural gas pressure swing adsorption device, when in operation, includes the following steps:

[0029] (1) After the 3.5MPa high-pressure natural gas from the external pipeline enters the unit through the boundary valve, it first undergoes primary filtration of solid impurities such as rust in the natural gas through a filter cartridge filter. The filtered natural gas is then divided into three paths after passing through a flow meter. One path enters the natural gas expander 9, which is driven by the high-pressure natural gas to operate at high speed to achieve power generation and grid connection. (2) The expander 9 drives the generator 14 to generate electricity, and the generator drives the compressor 8 to do work. Then, the refrigerant is pressurized. The pressurized refrigerant exchanges heat with the natural gas from the outlet of the expander 9. The heat-exchanged natural gas is then connected to the buffer tank 10 through a valve, while the refrigerant is in the heat exchange tank. After the heat is cooled, the refrigerant is cooled to -20°C again through the expansion valve 24. The expanded refrigerant then exchanges heat with the chilled water. The refrigerant after heat exchange returns to the compressor 8 inlet. The cooled chilled water enters the chilled water tank 23 and is then sent to the chilled water inlet heat exchanger 27 of each device by the chilled water pump 26. (3) The other two paths (one for use and one for standby) enter the heater and are heated to 80°C. The pressure of the natural gas is reduced from 3.5MPa to 1.0MPa through the pressure reducing valve. The reduced pressure of 1.0MPa natural gas enters the natural gas buffer tank 10 and then enters the adsorption tower in sequence according to the predetermined program of the system through the program control valve for adsorption and purification.

Claims

1. A natural gas pressure swing adsorption device, characterized in that, It includes a 3.5MPa natural gas inlet pipeline (1), which is connected to a heater A (6) via a cartridge filter A (2). The heater A (6) is connected to an adsorption tower (11) via a buffer tank (10). A flow meter A (4) is installed between the cartridge filter A (2) and the heater A (6). The flow meter A (4) is connected to a natural gas and refrigerant heat exchanger (21) via an expander (9). The natural gas and refrigerant heat exchanger (21) is connected to the buffer tank (10) via a pipeline.

2. The natural gas pressure swing adsorption device according to claim 1, characterized in that, The 3.5MPa natural gas inlet pipeline (1) is connected to heater B (7) through filter cartridge filter B (3), and heater B (7) is connected to buffer tank (10) through pipeline.

3. The natural gas pressure swing adsorption device according to claim 2, characterized in that, A pressure reducing valve A (15) is provided between the heater A (6) and the buffer tank (10), and a flow meter B (5) is provided between the filter cartridge B (3) and the heater B (7). The flow meter B (5) is connected through a pipeline expander (9).

4. The natural gas pressure swing adsorption device according to claim 1, characterized in that, The adsorption tower (11) is connected to a purified natural gas outlet pipe (17), and the purified natural gas outlet pipe (17) is connected to an online chromatograph (12) for purified natural gas. The adsorption tower (11) is connected to the buffer tank (10) through a backup pipe programmable valve (19), and a backup pipe (18) is provided between the backup pipe programmable valve (19) and the buffer tank (10).

5. The natural gas pressure swing adsorption device according to claim 1, characterized in that, A temperature measuring port (16) and a one-way valve (20) are provided between the expander (9) and the natural gas and refrigerant heat exchanger (21).

6. The natural gas pressure swing adsorption device according to claim 1, characterized in that, The expander (9) is connected to the compressor (8) via the generator (14). The compressor (8) is connected to the refrigerant and chilled water heat exchanger (22) via the natural gas and refrigerant heat exchanger (21). The refrigerant and chilled water heat exchanger (22) is connected to the compressor (8) via the return pipe (13).

7. The natural gas pressure swing adsorption device according to claim 6, characterized in that, An expansion valve (24) and a temperature detection port (25) are provided between the natural gas and refrigerant heat exchanger (21) and the refrigerant and chilled water heat exchanger (22).

8. The natural gas pressure swing adsorption device according to claim 6, characterized in that, The refrigerant and chilled water heat exchanger (22) is connected to the chilled water pump (26) through the chilled water tank (23), and the chilled water pump (26) is connected to the chilled water inlet heat exchanger (27) and the refrigerant and chilled water heat exchanger (22) through the chilled water inlet heat exchanger (27).

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