Membrane contactor differential pressure automatic protection device and method of use and application

Abstract

The application discloses a membrane contactor differential pressure automatic protection device and a use method and application. The differential pressure automatic protection device comprises a shell with a cavity, and a piston is arranged in the shell. The piston divides the cavity into a liquid-phase chamber and a gas-phase chamber. The liquid-phase chamber is provided with a liquid-phase limit and a liquid-phase interface. The liquid-phase limit is arranged in the liquid-phase chamber close to the liquid-phase interface. The gas-phase chamber is provided with a gas-phase limit and a gas-phase interface. The gas-phase limit is arranged in the gas-phase chamber close to the gas-phase interface. The device can automatically adjust the gas-liquid phase pressure difference in the operation process of the membrane contactor, balance the pressure difference, prevent the membrane from being wetted, has the advantages of simple and compact structure, good durability, high safety and the like, and can be widely used in the fields of membrane absorption natural gas decarburization and other membrane contactors.

Description

Technical Field

[0001] This application relates to an automatic differential pressure protection device for a membrane contactor, its usage method, and its application, belonging to the field of membrane contactor technology. Background Technology

[0002] Natural gas is currently the world's third largest fossil fuel energy source. Compared to coal and oil, natural gas has a lower carbon intensity, higher thermal efficiency, and causes less pollution during combustion, making it cleaner. Developing the natural gas industry has become an important choice for countries worldwide to improve their environment and promote sustainable economic development. According to ExxonMobil's "Energy Outlook 2030," the world's energy structure will undergo significant changes by 2030, with natural gas accounting for approximately 25% of global energy consumption, up from 20%. At that time, total natural gas consumption will reach 182 trillion cubic feet, surpassing coal to become the world's second largest energy source.

[0003] Natural gas extraction typically involves the presence of acidic gases, such as carbon dioxide (CO2). These acidic gases not only reduce the calorific value of natural gas, increase transportation load and costs, but also corrode pipelines and equipment. Therefore, these acidic gases must be removed from natural gas before use and further processing. Currently, the most common industrial method for separating and removing CO2 from natural gas is absorption, such as the amine absorption process: natural gas containing CO2 is brought into cross-flow contact with an amine absorbent in an absorption tower; the CO2 reacts with the amine and is removed, thus purifying the natural gas. Alternatively, a rich amine solution can be heated to desorb CO2, achieving the regeneration and recycling of the absorbent.

[0004] Although traditional absorption tower technology is quite mature, it still has some drawbacks, such as large size, small effective mass transfer area, difficulty in independently controlling gas-liquid flow rates, and problems such as mist entrainment, flooding, and leakage. Furthermore, absorption tower technology also has limitations when used on offshore or mobile platforms: the equipment is tall, has weak resistance to wind and waves, posing safety hazards; swaying severely affects processing efficiency, requiring higher design margins than on land; and it occupies a large area, resulting in high foundation investment. Meanwhile, the ocean contains extremely rich natural gas resources (according to the International Oil and Gas Processing Institute, offshore natural gas reserves are as high as 1.40 × 10⁻⁶). 14 m 3 China accounts for more than 50% of the world's total natural gas reserves. Strengthening the exploration and development of offshore natural gas is crucial for ensuring natural gas supply and optimizing the energy structure, and has received high attention from many countries. In recent years, my country's offshore oil and gas extraction capacity has been continuously enhanced, and the offshore oil and gas industry is entering a period of rapid development. Therefore, developing new CO2 removal technologies, especially those suitable for offshore natural gas extraction, is of great significance.

[0005] Membrane contactor technology is a novel separation process that couples membrane technology with traditional chemical unit operations. It achieves interphase mass transfer without direct contact between the two phases, offering advantages such as compact equipment structure, high mass transfer efficiency, and high operational flexibility. It has broad application prospects in chemical separation and environmental protection, including offshore natural gas decarbonization and biogas purification. Ideally, the membrane pores should be in a gaseous atmosphere during membrane contactor decarbonization. However, due to the interaction between the membrane material and the absorbent, as well as fluctuations in the gas-liquid phase pressure difference, the membrane pores may become partially or completely occupied by the absorbent, resulting in semi-wetting or full wetting. When the membrane pores are partially or completely wetted, CO2 removal performance will be significantly affected. Therefore, preventing membrane wetting is of paramount importance in the operation of membrane contactors.

[0006] Developing a gas-liquid phase differential pressure protection system for membrane contactors to prevent excessive liquid phase pressure from causing absorbent to enter the membrane pores is one of the effective ways to solve membrane wetting. However, traditional pressure balancing systems have drawbacks such as long response time to pressure fluctuations and difficulty in controlling low differential pressures. Chinese invention patent CN108893153A (Pressure Balancing Device and Membrane Contactor) proposes a pressure balancing system for membrane contactors, which uses an elastic diaphragm installed inside the housing. The deformation of the elastic diaphragm structure automatically adjusts the chamber pressure, thereby regulating the pressure of the gas chamber and liquid chamber in the membrane contactor connected to it. However, the aforementioned devices still have some drawbacks: they are only suitable for situations where the gas and liquid pressures of the membrane contactor are roughly equal. If a slightly higher pressure is required on one side, the elastic diaphragm will deform continuously during use until it loses its regulating function. In reality, to avoid bubbling during membrane contactor operation, the liquid phase pressure is generally slightly higher than the gas phase pressure (e.g., 0.05 MPa). Furthermore, the differential pressure setting of the membrane contactor's gas and liquid phases cannot be adjusted as needed. The elastic diaphragm is usually made of polymer materials, which have poor chemical corrosion resistance and are prone to aging, potentially leading to gas-liquid mixing due to damage. To address these issues, this invention proposes an automatic differential pressure protection device for membrane contactors and its usage method, which can solve the aforementioned practical problems. Summary of the Invention

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] This invention provides an automatic differential pressure protection device for a membrane contactor and its usage method. The device mainly includes a cylindrical cylinder, a flat end plate, a piston, a limit switch, a gas phase interface, a liquid phase interface, a gas phase pipeline, and a liquid phase pipeline. The cylindrical cylinder and the flat end plate are connected to form a pressure-resistant, airtight cylinder, and a piston is installed inside. The flat end plate has a limit switch on one side facing the cylinder, and a gas phase interface or a liquid phase interface on the other side. The gas phase interface / liquid phase interface is connected to the gas phase pipeline / liquid phase pipeline, and the other end of the gas phase pipeline / liquid phase pipeline is connected to the gas phase outlet / liquid phase inlet of the membrane contactor, respectively. When the automatic differential pressure protection device for the membrane contactor is in use, the height of its liquid phase interface is lower than that of the liquid phase inlet of the membrane contactor. The specific height difference depends on the proposed liquid-gas phase differential pressure value of the membrane contactor and the density of the liquid phase medium.

[0009] According to one aspect of this application, an automatic differential pressure protection device for a membrane contactor is provided, the automatic differential pressure protection device comprising a housing having a cavity, wherein a piston is disposed within the housing;

[0010] The piston divides the cavity into a liquid phase chamber and a gas phase chamber;

[0011] The liquid phase chamber is equipped with a liquid phase limit and a liquid phase interface;

[0012] The liquid phase limiter is located in the liquid phase chamber near the liquid phase interface.

[0013] The gas phase chamber is equipped with a gas phase limit and a gas phase interface;

[0014] The gas phase limiter is located in the gas phase chamber near the gas phase interface.

[0015] Optionally, the piston mates with the housing. The airtight cylinder and the internal piston are dimensionally matched, allowing the piston to slide freely within the cylinder, separating the gas and liquid phases, and providing good sealing.

[0016] Optionally, the height of the liquid phase interface is higher than the height of the liquid phase inlet of the membrane contactor. When the automatic differential pressure protection device for the membrane contactor is in use, its liquid phase interface is higher than the height of the liquid phase inlet of the membrane contactor; the specific height difference between the liquid phase interface of the automatic differential pressure protection device and the liquid phase inlet of the membrane contactor depends on the proposed liquid-gas phase differential pressure value of the membrane contactor and the density of the liquid phase medium.

[0017] Optionally, in the initial state, the pressure at the liquid phase interface is lower than the pressure at the gas phase interface. During steady-state operation of the membrane contactor, the pressure at the liquid phase interface of the automatic differential pressure protection device is lower than the pressure at the gas phase interface, causing the piston to be normally positioned on the liquid phase limiting side.

[0018] Optionally, in the initial state, the absolute difference between the pressure at the liquid phase interface and the pressure at the gas phase interface is 0.0001 to 0.1 MPa.

[0019] Optionally, in the initial state, the piston is located on the side close to the liquid phase limit.

[0020] Optionally, the gas phase limit point is also equipped with an automatic alarm.

[0021] According to another aspect of this application, a method of using the above-described differential pressure automatic protection device is provided, the method comprising:

[0022] Connect the liquid phase inlet of the membrane contactor to the liquid phase interface, and connect the gas phase outlet of the membrane contactor to the gas phase interface;

[0023] When the pressure in the membrane contactor changes, the piston slides toward the gas phase interface. When the pressure in the membrane contactor is adjusted to the initial set value, the piston automatically returns to the liquid phase limit side.

[0024] Optionally, the automatic alarm will sound when the piston slides to the gas phase limit.

[0025] In this application, when the differential pressure automatic protection device is in use, its gas phase interface is connected to the gas phase outlet of the membrane contactor via a gas phase pipeline; when the differential pressure automatic protection device is in use, its liquid phase interface is connected to the liquid phase inlet of the membrane contactor via a liquid phase pipeline. During the operation of the membrane contactor, if pressure fluctuations occur and the pressure difference between the liquid phase inlet and the gas phase outlet increases, the piston in the differential pressure automatic protection device can slide from the liquid phase interface side to the gas phase interface side. The sliding of the piston can reduce the pressure difference between the liquid phase inlet and the gas phase outlet of the membrane contactor, automatically adjusting the gas-liquid phase pressure difference of the membrane contactor system to the initial set value. When the pressure fluctuations disappear and the membrane contactor returns to normal operation, the piston in the differential pressure automatic protection device automatically returns to the liquid phase limit side. The gas phase limit is equipped with an automatic alarm; when the pressure fluctuations are too large during the operation of the membrane contactor and the piston in the differential pressure automatic protection device reaches the gas phase limit, an automatic alarm is triggered.

[0026] According to another aspect of this application, an application of the aforementioned automatic differential pressure protection device is provided in membrane absorption natural gas decarbonization and biogas purification. The automatic differential pressure protection device can be used in the field of membrane contactors for membrane absorption natural gas decarbonization and biogas purification.

[0027] The beneficial effects that this application can produce include:

[0028] 1) The membrane contactor differential pressure automatic protection device provided in this application has the ability to precisely control the gas-liquid phase differential pressure setting value by adjusting the height difference between the liquid phase inlet of the membrane contactor and the liquid phase interface of the differential pressure automatic protection device as needed.

[0029] 2) The membrane contactor differential pressure automatic protection device provided in this application has the function that when the membrane contactor system experiences pressure fluctuations and the liquid-gas phase differential pressure is higher than the safe range, the piston will automatically slide under the action of the differential pressure, thereby reducing the volume of the cylinder on the gas phase side, causing the liquid phase pressure to drop, automatically balancing the gas-liquid phase differential pressure of the membrane contactor, and avoiding the risk of membrane wetting.

[0030] 3) The membrane contactor differential pressure automatic protection device provided in this application has a piston system to eliminate the aging problem of polymer materials, making the system safer and more reliable.

[0031] 4) The membrane contactor differential pressure automatic protection device provided in this application has an alarm function through limit setting. When an unexpected situation occurs in the membrane contactor system, the liquid phase pressure remains high, and the piston reaches the gas phase side limit, the differential pressure automatic protection device can issue an early warning. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the automatic differential pressure protection device for the membrane contactor in the embodiments of this application.

[0033] Figure 2 Two schematic diagrams are shown for the automatic differential pressure protection device for the membrane contactor in the embodiments of this application.

[0034] Figure 3 This is a schematic diagram of the membrane contactor of this application (A is the liquid phase inlet of the membrane contactor; B is the liquid phase outlet of the membrane contactor; C is the gas phase inlet of the membrane contactor; D is the gas phase outlet of the membrane contactor).

[0035] In the diagram: 1. Housing; 2. Piston; 3. Flat end plate; 4. Liquid phase limit; 5. Gas phase limit; 6. Liquid phase interface; 7. Gas phase interface; 8. Liquid phase pipeline; 9. Gas phase pipeline; 10. Membrane contactor liquid phase inlet; 11. Membrane contactor gas phase inlet. Detailed Implementation

[0036] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0037] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0038] Example 1

[0039] like Figure 1 and 2As shown, the membrane contactor differential pressure automatic protection device includes a housing 1 with a cavity, and a piston 2 is provided inside the housing 1. The piston 2 divides the cavity into a liquid phase chamber and a gas phase chamber. The liquid phase chamber is provided with a liquid phase limit 4 and a liquid phase interface 6. The liquid phase limit 4 is located in the liquid phase chamber near the liquid phase interface 6. The gas phase chamber is provided with a gas phase limit 5 and a gas phase interface 7. The liquid phase interface 6 is connected to one end of the liquid phase pipeline 8, and the other end of the liquid phase pipeline 8 is connected to the liquid phase inlet 10 of the membrane contactor. The gas phase interface 7 is connected to one end of the gas phase pipeline 9, and the other end of the gas phase pipeline 9 is connected to the gas phase inlet 11 of the membrane contactor.

[0040] When in use, the gas phase interface of the automatic differential pressure protection device is connected to the gas phase outlet of the membrane contactor via a gas phase pipeline; the liquid phase interface is connected to the liquid phase inlet of the membrane contactor via a liquid phase pipeline. During membrane contactor operation, if pressure fluctuations occur and the pressure difference between the liquid phase inlet and gas phase outlet increases, the piston in the automatic differential pressure protection device can slide from the liquid phase interface side to the gas phase interface side. This sliding of the piston reduces the pressure difference between the liquid phase inlet and gas phase outlet of the membrane contactor, automatically adjusting the gas-liquid phase pressure difference of the membrane contactor system to the initial set value. When the pressure fluctuations disappear and the membrane contactor returns to normal operation, the piston in the automatic differential pressure protection device automatically returns to the liquid phase limit side. The gas phase limit setting has an automatic alarm function; when the pressure fluctuations are too large during membrane contactor operation and the piston in the automatic differential pressure protection device reaches the gas phase limit, an automatic alarm is triggered.

[0041] Example 2

[0042] This invention provides an automatic differential pressure protection device for membrane contactors used in the process of membrane absorption and natural gas decarbonization.

[0043] When using membrane absorption for natural gas decarbonization, the absorbent is an aqueous solution of DMEA with a density of 1060 kg / m³. 3 To ensure stable system operation, the liquid inlet pressure of the membrane contactor needs to be controlled at 5.05 MPa and the gas outlet pressure at 5.00 MPa.

[0044] like Figure 3 As shown, the differential pressure automatic protection device of the present invention is used in the above-mentioned membrane contactor, wherein... Figure 2 In the differential pressure automatic protection device, the liquid phase inlet 10 of the membrane contactor is connected to the liquid phase inlet A of the membrane contactor, and the gas phase inlet 11 of the membrane contactor is connected to the gas phase outlet D of the membrane contactor. When in use, the installation height of the liquid phase interface 6 of the differential pressure automatic protection device is higher than that of the liquid phase inlet A of the membrane contactor, and the height difference is 5.0 meters.

[0045] When the membrane contactor is operating under steady-state conditions, the pressure at the liquid phase interface of the differential pressure automatic protection device is equal to the liquid phase inlet pressure of the membrane contactor (i.e., 5.05 MPa) and the static pressure difference caused by the height (i.e., 1060 kg / m²). 3 The difference between the pressure at the gas phase interface of the differential pressure automatic protection device and the pressure at the gas phase outlet of the membrane contactor is approximately equal to 51.94 kPa (0.052 MPa). At this time, the pressure at the liquid phase interface of the differential pressure automatic protection device is lower than the pressure at the gas phase interface, and the piston is located on the liquid phase limiting side.

[0046] When the pressure in the membrane contactor system fluctuates, such as when the liquid inlet pressure suddenly increases to more than 5.052 MPa, the piston will move towards the gas phase side. The volume of the liquid phase side of the membrane contactor will increase, causing the pressure to drop and ensuring that the gas-liquid pressure difference is stable, thus avoiding the risk of membrane wetting. When the pressure fluctuation in the membrane contactor system disappears, the piston will return to the liquid phase interface side.

[0047] Example 3

[0048] This invention provides an automatic differential pressure protection device for membrane contactors used in the decarbonization process of membrane absorption biogas.

[0049] When using membrane absorption for natural gas decarbonization, the absorbent is pure water with a density of 1000 kg / m³. 3 To ensure stable system operation, the liquid inlet pressure of the membrane contactor needs to be controlled at 0.83 MPa and the gas outlet pressure at 0.80 MPa.

[0050] like Figure 3 As shown, the differential pressure automatic protection device of the present invention is used in the above-mentioned membrane contactor, wherein... Figure 2 In the differential pressure automatic protection device, the liquid phase inlet 10 of the membrane contactor is connected to the liquid phase inlet A of the membrane contactor, and the gas phase inlet 11 of the membrane contactor is connected to the gas phase outlet D of the membrane contactor. When in use, the installation height of the liquid phase interface 6 of the differential pressure automatic protection device is higher than that of the liquid phase inlet A of the membrane contactor, with a height difference of 3.5 meters.

[0051] When the membrane contactor operates under steady-state conditions, the pressure at the liquid phase interface of the differential pressure automatic protection device is equal to the liquid phase inlet pressure of the membrane contactor (i.e., 0.83 MPa) and the static pressure difference caused by the height (i.e., 1000 kg / m²). 3The difference between the pressure at the gas phase interface of the differential pressure automatic protection device and the pressure at the gas phase outlet of the membrane contactor is approximately equal, i.e., 0.80 MPa. At this time, the pressure at the liquid phase interface of the differential pressure automatic protection device is lower than the pressure at the gas phase interface, and the piston is located on the liquid phase limiting side. (The pressure is calculated as follows: ×9.8 N / kg × 3.5 m = 34.3 kPa, i.e. 0.034 MPa).

[0052] When the pressure in the membrane contactor system fluctuates, such as when the liquid inlet pressure suddenly increases to more than 0.834 MPa, the piston will move towards the gas phase side. The volume of the liquid phase side of the membrane contactor will increase, causing the pressure to drop and ensuring that the gas-liquid pressure difference remains stable, thus avoiding the risk of membrane wetting. When the pressure fluctuation in the membrane contactor system disappears, the piston will return to the liquid phase interface side.

[0053] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An automatic differential pressure protection device for a membrane contactor, characterized in that, The differential pressure automatic protection device includes a housing with a cavity, and a piston is provided inside the housing; The piston divides the cavity into a liquid phase chamber and a gas phase chamber; The liquid phase chamber is equipped with a liquid phase limit and a liquid phase interface; The liquid phase limiter is located in the liquid phase chamber near the liquid phase interface. The gas phase chamber is equipped with a gas phase limit and a gas phase interface; The gas phase limit is located in the gas phase chamber near the gas phase interface. The height of the liquid phase interface is higher than the height of the liquid phase inlet of the membrane contactor; In the initial state, the pressure at the liquid phase interface is lower than the pressure at the gas phase interface.

2. The differential pressure automatic protection device according to claim 1, characterized in that, The piston mates with the housing.

3. The differential pressure automatic protection device according to claim 1, characterized in that, In the initial state, the absolute difference between the pressure at the liquid phase interface and the pressure at the gas phase interface is 0.0001~0.1MPa.

4. The differential pressure automatic protection device according to claim 1, characterized in that, In the initial state, the piston is located on the side close to the liquid phase limit.

5. The differential pressure automatic protection device according to claim 1, characterized in that, An automatic alarm is also provided at the gas phase limit point.

6. The method of using the automatic differential pressure protection device according to any one of claims 1 to 5, characterized in that, The method of use includes: Connect the liquid phase inlet of the membrane contactor to the liquid phase interface, and connect the gas phase outlet of the membrane contactor to the gas phase interface; When the pressure in the membrane contactor changes, the piston slides toward the gas phase interface. When the pressure in the membrane contactor is adjusted to the initial set value, the piston automatically returns to the liquid phase limit side.

7. The method of use according to claim 6, characterized in that, When the piston slides to the gas phase limit, the automatic alarm will sound automatically.

8. The application of the differential pressure automatic protection device according to any one of claims 1 to 5 in membrane absorption natural gas decarbonization and biogas purification.

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