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

Abstract

The invention discloses an automatic differential pressure protection device of a membrane contactor and a using method and application thereof. The automatic differential pressure 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 limiter is arranged in the liquid-phase chamber close to one side of the liquid-phase interface; the gas-phase chamber is provided with a gas-phase limit and a gas-phase interface; and the gas-phase limiter is arranged in the gas-phase chamber close to one side of the gas-phase interface. The device can realize automatic adjustment of the gas-liquid phase pressure difference in the operation process of the membrane contactor, plays roles in balancing the pressure difference and preventing the membrane from being wetted, has the advantages of simple and compact structure, good durability, high safety and the like, and can be widely applied to the field of membrane contactors such as membrane absorption natural gas decarburization.

Description

Technical Field

[0001] The present application relates to a membrane contactor pressure difference automatic protection device and a use method and application, belonging to the membrane contactor technical field. Background Art

[0002] Natural gas is the third largest fossil fuel energy in the world today. Compared with coal and oil, natural gas has low carbon intensity and high thermal energy utilization rate. Its combustion causes less pollution to the environment, so it is cleaner. Vigorously developing the natural gas industry has become an important choice for countries around the world to improve the environment and promote sustainable economic development. According to the "Energy Outlook 2030 Report" released by ExxonMobil Chemical Company, by 2030, the world's energy structure will undergo major changes, and the proportion of natural gas in global energy will increase from 20% to about 25%. By then, the total consumption of natural gas will reach 182 trillion cubic feet, surpassing coal to become the world's second largest energy type. With the increasing prominence of environmental problems such as haze in my country and the implementation of the "Air Pollution Prevention and Control Action Plan", the Chinese government is also constantly increasing the supply and use of natural gas.

[0003] Natural gas is usually accompanied by a certain amount of acidic gases, such as carbon dioxide (CO2), during the extraction process. These acidic gases not only reduce the calorific value of natural gas, increase transportation load and cost, but also corrode pipelines and equipment. Therefore, these acidic gases need to be removed from natural gas before use and further processing. At present, the most common method for separating and removing CO2 from natural gas in industry is absorption, such as the alcohol amine absorption process: natural gas containing CO2 is in cross-flow contact with alcohol amine absorbent in the absorption tower, CO2 reacts with alcohol amine and is removed, so that natural gas is purified; rich amine solution desorbs CO2 by heating and other methods to achieve regeneration and recycling of absorbent.

[0004] Although the traditional absorption tower technology is very mature, it still has some disadvantages, such as large size, small effective mass transfer area, difficulty in controlling the gas-liquid flow rate separately, and problems such as mist entrainment, liquid flooding, and liquid leakage. In addition, the absorption tower technology also has certain shortcomings when used on offshore platforms or mobile platforms: the equipment is relatively high, weak in wind and wave resistance, and there are safety hazards; the shaking seriously affects the processing efficiency, and the design margin needs to be higher than that on land; the land area is large, and the basic investment is high. The ocean is extremely rich in natural gas resources (according to the International Petroleum and Natural Gas Technology Research Institute, the marine natural gas reserves are as high as 1.40×10 14 m 3, accounting for more than 50% of the world's total natural gas reserves). Strengthening the exploration and development of marine natural gas will help ensure the supply of natural gas and optimize the energy structure, and has been highly valued by many countries. In recent years, my country's offshore oil and natural gas production capacity has been continuously enhanced, and the offshore oil and gas industry is entering a period of rapid development. Therefore, it is of great significance to develop new CO2 removal technologies, especially those suitable for offshore natural gas production.

[0005] Membrane contactor technology is a new type of separation process that couples membrane technology with traditional chemical unit operations. It realizes interphase mass transfer without direct contact between the two phases. It has the advantages of compact equipment structure, high mass transfer efficiency, and great operational flexibility. It has broad application prospects in the fields of chemical separation and environmental protection, including offshore natural gas decarbonization and biogas purification. During the decarbonization operation of the membrane contactor, ideally, the membrane pores should be filled with a gas phase atmosphere. However, due to the interaction between the membrane material and the absorbent and the fluctuation of the gas-liquid pressure difference, the membrane pores may be partially or fully occupied by the absorbent, that is, semi-wetting or full wetting. When the membrane pores are partially or fully wetted, the CO2 removal performance will be significantly affected. Therefore, preventing membrane wetting is a top priority in the operation of the membrane contactor.

[0006] Developing a gas-liquid pressure difference protection system for a membrane contactor to prevent the absorbent from entering the membrane pores due to excessive liquid pressure is one of the effective ways to solve the problem of membrane wetting. However, the traditional pressure balance system has disadvantages such as a long reaction time to pressure fluctuations and difficulty in controlling low pressure differences. Chinese invention patent CN108893153A (pressure balance device and membrane contactor) proposes a pressure balance system for a membrane contactor, which uses an elastic diaphragm in the shell to automatically adjust the chamber pressure through the deformation of the elastic diaphragm structure, thereby adjusting the pressure of the gas chamber and liquid chamber in the membrane contactor connected to it. However, the above device still has some disadvantages: it is only applicable to the situation where the gas-liquid pressure of the membrane contactor is equivalent. If the pressure on one side needs to be slightly higher, the elastic diaphragm will continue to deform during use until it loses its regulating function. In fact, in order to avoid bubbling during the operation of the membrane contactor, the liquid phase pressure is generally slightly higher than the gas phase pressure (for example, 0.05MPa); it is impossible to adjust the gas-liquid phase pressure difference setting value of the membrane contactor according to needs; the elastic diaphragm is usually a polymer material with poor chemical corrosion resistance and easy aging, which may cause gas-liquid fluid mixing due to damage. In view of the above problems, the present invention proposes a membrane contactor pressure difference automatic protection device and a method of use, which can solve the above practical problems. Summary of the invention

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

[0008] The present invention provides a membrane contactor pressure difference automatic protection device and a use method thereof. The device mainly comprises a cylindrical cylinder body, a plane end plate, a piston, a limiter, a gas phase interface, a liquid phase interface, a gas phase pipeline and a liquid phase pipeline, etc. The cylindrical cylinder body is connected with the plane end plate to form a pressure-resistant gas-tight cylinder body, and a piston is arranged inside; a limiter is provided on the side of the plane end plate facing the cylinder body, and a gas phase interface or a liquid phase interface is provided on the other side; the gas phase interface / liquid phase interface is respectively connected to the gas phase pipeline / liquid phase pipeline, and the other end of the gas phase pipeline / liquid phase pipeline is respectively connected to the gas phase outlet / liquid phase inlet of the membrane contactor; when the membrane contactor pressure difference automatic protection device is used, its liquid phase interface is lower than the height of the liquid phase inlet of the membrane contactor, and the specific height difference depends on the liquid-gas pressure difference value of the membrane contactor to be set and the density of the liquid phase medium.

[0009] According to one aspect of the present application, a membrane contactor pressure difference automatic protection device is provided, the pressure difference automatic protection device comprising a shell having a cavity, a piston being arranged in the shell;

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

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

[0012] The liquid phase limiter is arranged in the liquid phase chamber near one side of the liquid phase interface;

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

[0014] The gas phase limiter is arranged in the gas phase chamber close to one side of the gas phase interface.

[0015] Optionally, the piston is matched with the housing. The airtight cylinder body and the internal piston are matched with each other in size, and the piston can slide freely in the cylinder body to separate the gas and liquid phases with good sealing performance;

[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 pressure difference 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 pressure difference protection device and the liquid phase inlet of the membrane contactor depends on the liquid-gas pressure difference value of the membrane contactor to be set 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. When the membrane contactor is operated in a steady state, the pressure at the liquid phase interface of the pressure difference automatic protection device is lower than the pressure at the gas phase interface, so that the piston is normally located on the liquid phase limit 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 0.0001-0.1 MPa.

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

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

[0021] According to another aspect of the present application, a method for using the above-mentioned pressure difference automatic protection device is provided, and the method for using includes:

[0022] Connecting the liquid phase inlet of the membrane contactor to the liquid phase interface, and connecting 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, and 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, when the piston slides to the gas phase limit, the automatic alarm automatically sounds an alarm.

[0025] In the present application, when the pressure difference automatic protection device is in use, its gas phase interface is connected to the gas phase outlet of the membrane contactor through the gas phase pipeline; when the pressure difference automatic protection device is in use, its liquid phase interface is connected to the liquid phase inlet of the membrane contactor through the liquid phase pipeline. When pressure fluctuation occurs during the operation of the membrane contactor and the pressure difference between the liquid phase inlet and the gas phase outlet increases, the piston in the pressure difference 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, so that the gas-liquid pressure difference of the membrane contactor system is automatically adjusted to the initial set value; when the pressure fluctuation disappears and returns to normal during the operation of the membrane contactor, the piston in the pressure difference automatic protection device automatically returns to the liquid phase limit side; the gas phase side limit is set to automatically alarm, and when the pressure fluctuation is too large during the operation of the membrane contactor, the piston in the pressure difference automatic protection device reaches the gas phase side limit, and an automatic alarm is issued.

[0026] According to another aspect of the present application, an application of the above-mentioned pressure difference automatic protection device in membrane absorption natural gas decarbonization and biogas purification is provided. The pressure difference automatic protection device can be used in membrane contactor fields such as membrane absorption natural gas decarbonization and biogas purification.

[0027] The beneficial effects of this application include:

[0028] 1) The membrane contactor pressure difference automatic protection device provided in the present application has the function of accurately regulating the gas-liquid pressure difference setting value by adjusting the height difference between the liquid phase inlet of the membrane contactor and the liquid phase interface of the pressure difference automatic protection device as needed.

[0029] 2) The membrane contactor pressure difference automatic protection device provided in the present application has the function that when pressure fluctuation occurs in the membrane contactor system and the liquid-gas pressure difference is higher than the safe range, the piston will automatically slide under the action of the pressure difference, so that the volume of the cylinder on the gas phase side is reduced, and the liquid phase pressure is reduced, thereby automatically balancing the gas-liquid pressure difference of the membrane contactor and avoiding the risk of membrane wetting.

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

[0031] 4) The membrane contactor pressure difference automatic protection device provided in the present application has an alarm through a limit setting. When an unexpected situation occurs in the membrane contactor system, the liquid phase pressure continues to be high, and the piston reaches the limit on the gas phase side, the pressure difference automatic protection device can issue an early warning. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the membrane contactor pressure difference automatic protection device in an embodiment of the present application.

[0033] Figure 2 The second schematic diagram of the membrane contactor pressure difference automatic protection device in the embodiment of the present application is shown.

[0034] Figure 3 This is a schematic diagram of the structure of the membrane contactor of the present 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 figure: 1. Shell; 2. Piston; 3. Plane end plate; 4. Liquid phase limiter; 5. Gas phase limiter; 6. Liquid phase interface; 7. Gas phase interface; 8. Liquid phase pipeline; 9. Gas phase pipeline; 10. Liquid phase inlet of membrane contactor; 11. Gas phase inlet of membrane contactor. DETAILED DESCRIPTION

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

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

[0038] Example 1

[0039] like Figure 1 and 2As shown, the membrane contactor pressure difference automatic protection device includes a shell 1 with a cavity, a piston 2 is arranged in the shell 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 arranged in the liquid phase chamber near the liquid phase interface 6; the gas phase chamber is provided with a gas phase limit and a gas phase interface; the gas phase limit 5 is arranged in the gas phase chamber near the 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 the pressure difference automatic protection device is in use, its gas phase interface is connected to the gas phase outlet of the membrane contactor through the gas phase pipeline; when the pressure difference automatic protection device is in use, its liquid phase interface is connected to the liquid phase inlet of the membrane contactor through the liquid phase pipeline. When pressure fluctuation occurs during the operation of the membrane contactor and the pressure difference between the liquid phase inlet and the gas phase outlet increases, the piston in the pressure difference automatic protection device can slide from the liquid phase interface to the gas phase interface; the sliding of the piston can reduce the pressure difference between the liquid phase inlet and the gas phase outlet of the membrane contactor, so that the gas-liquid pressure difference of the membrane contactor system is automatically adjusted to the initial setting value; when the pressure fluctuation disappears and returns to normal during the operation of the membrane contactor, the piston in the pressure difference automatic protection device automatically returns to the liquid phase limit side; the gas phase side limit is set to automatically alarm, and when the pressure fluctuation is too large during the operation of the membrane contactor, the piston in the pressure difference automatic protection device reaches the gas phase side limit, and an automatic alarm is issued.

[0041] Example 2

[0042] The invention provides a membrane contactor pressure difference automatic protection device for use in a membrane absorption natural gas decarbonization process.

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

[0044] like Figure 3 As shown, the pressure difference automatic protection device of the present invention is used in the above membrane contactor, wherein Figure 2 The liquid phase inlet 10 of the membrane contactor in the pressure difference automatic protection device is connected to the liquid phase inlet A of the membrane contactor, and the gas phase inlet 11 of the membrane contactor in the pressure difference automatic protection device 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 pressure difference automatic protection device is higher than the liquid phase inlet A of the membrane contactor, and the height difference is 5.0 meters.

[0045] When the membrane contactor is operated in a steady state, the pressure at the liquid phase interface of the pressure difference automatic protection device is the liquid phase inlet pressure of the membrane contactor (i.e. 5.05MPa) and the static pressure difference caused by the height (i.e. 1060kg / m 3 ×9.8N / kg×5.0m=51.94KPa, that is, 0.052MPa), that is, 5.05MPa-0.052MPa=4.998MPa; the pressure at the gas phase interface of the pressure difference automatic protection device is basically equivalent to the gas phase outlet of the membrane contactor, that is, 5.00MPa. At this time, the pressure at the liquid phase interface of the pressure difference automatic protection device is lower than the pressure at the gas phase interface, and the piston is located on the liquid phase limit side.

[0046] When the pressure of the membrane contactor system fluctuates, for example, the liquid phase inlet pressure suddenly increases, when it is greater than 5.052MPa, the piston will move toward the gas phase side, and the volume of the liquid phase side of the membrane contactor will increase, causing the pressure to drop, ensuring that the gas-liquid pressure difference is in a stable state and avoiding the risk of membrane wetting; when the pressure fluctuation of the membrane contactor system disappears, the piston returns to the liquid phase interface side.

[0047] Example 3

[0048] The invention provides a membrane contactor pressure difference automatic protection device for use in the membrane absorption biogas decarbonization process.

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

[0050] like Figure 3 As shown, the pressure difference automatic protection device of the present invention is used in the above membrane contactor, wherein Figure 2 The liquid phase inlet 10 of the membrane contactor in the pressure difference automatic protection device is connected to the liquid phase inlet A of the membrane contactor, and the gas phase inlet 11 of the membrane contactor in the pressure difference automatic protection device 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 pressure difference automatic protection device is higher than the liquid phase inlet A of the membrane contactor, and the height difference is 3.5 meters.

[0051] When the membrane contactor is operated in a steady state, the pressure at the liquid phase interface of the pressure difference automatic protection device is the liquid phase inlet pressure of the membrane contactor (i.e. 0.83MPa) and the static pressure difference caused by the height (i.e. 1000kg / m 3×9.8N / kg×3.5m=34.3KPa, i.e. 0.034MPa), i.e. 0.83MPa-0.034MPa=0.796MPa; the pressure at the gas phase interface of the pressure differential automatic protection device is basically equivalent to the gas phase outlet of the membrane contactor, i.e. 0.80MPa. At this time, the pressure at the liquid phase interface of the pressure differential automatic protection device is lower than the pressure at the gas phase interface, and the piston is located on the liquid phase limit side.

[0052] When the pressure of the membrane contactor system fluctuates, for example, the liquid phase inlet pressure suddenly increases, when it is greater than 0.834MPa, the piston will move toward the gas phase side, and the volume of the liquid phase side of the membrane contactor will increase, causing the pressure to drop, ensuring that the gas-liquid pressure difference is in a stable state and avoiding the risk of membrane wetting; when the pressure fluctuation of the membrane contactor system disappears, the piston returns to the liquid phase interface side.

[0053] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A membrane contactor pressure difference automatic protection device, characterized in that: The pressure difference automatic protection device comprises a housing having a cavity, wherein a piston is arranged in the housing; 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 limiter is arranged in the liquid phase chamber near one side of the liquid phase interface; The gas phase chamber is provided with a gas phase limit and a gas phase interface; The gas phase limiter is arranged in the gas phase chamber close to one side of the gas phase interface.

2. The pressure difference automatic protection device according to claim 1, characterized in that: The piston is matched with the housing.

3. The pressure difference automatic protection device according to claim 1, characterized in that: The height of the liquid phase interface is higher than the height of the liquid phase inlet of the membrane contactor.

4. The pressure difference automatic protection device according to claim 1, characterized in that: In the initial state, the pressure at the liquid phase interface is lower than the pressure at the gas phase interface.

5. The pressure difference automatic protection device according to claim 4, 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 0.0001-0.1 MPa.

6. The pressure difference automatic protection device according to claim 1, characterized in that: In the initial state, the piston is located at the side close to the liquid phase limit.

7. The pressure difference automatic protection device according to claim 1, characterized in that: The gas phase limit position is also provided with an automatic alarm.

8. The method for using the pressure difference automatic protection device according to any one of claims 1 to 7, characterized in that: The method of use includes: Connecting the liquid phase inlet of the membrane contactor to the liquid phase interface, and connecting 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, and when the pressure in the membrane contactor is adjusted to the initial set value, the piston automatically returns to the liquid phase limit side.

9. The method of use according to claim 8, characterized in that: When the piston slides to the gas phase limit position, the automatic alarm automatically alarms.

10. Application of the pressure difference automatic protection device according to any one of claims 1 to 7 in membrane absorption natural gas decarbonization and biogas purification.

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