VOCs (Volatile Organic Compounds) gas purification method and system by combining membrane absorption with porous adsorption material slurry adsorption

Abstract

The invention provides a VOCs gas purification method and system by combining membrane absorption with porous adsorption material slurry adsorption, and the method comprises the following steps: filtering VOCs waste gas, enabling the VOCs waste gas to enter a fiber outer side space or a fiber inner side space in a membrane contactor, and enabling the porous adsorption material slurry to enter the fiber inner side space or the fiber outer side space; under the action of pressure difference between the VOCs waste gas side and the porous adsorption material slurry side, part of VOCs gas penetrates through the wall of the hollow fiber membrane assembly and enters the fiber inner side space or the fiber outer side space, target components in the VOCs gas are selectively adsorbed by the porous adsorption material, slurry rich in the porous adsorption material is obtained, and purified gas is discharged; the rich porous adsorption material slurry enters a desorption tower and then is heated, adsorbed VOCs are desorbed and subjected to combustion treatment, and lean material slurry obtained after desorption is collected and recycled. The device has the advantages of broad-spectrum applicability, high purification efficiency, continuous operation and the like.

Description

Technical Field

[0001] The present invention relates to a method and system for purifying VOCs gas by membrane absorption combined with slurry absorption of porous adsorbent materials, belonging to the technical field of volatile organic compound treatment. Background Technique

[0002] Volatile Organic Compounds (VOCs) are raw materials, solvents, extractants, etc. widely used in industries such as medicine, chemical industry, and packaging printing. They have high atmospheric chemical reactivity and are important precursors of fine particulate matter (PM2.5) and ozone (O3). Their emissions not only cause serious environmental pollution but also pose direct or indirect hazards to human health.

[0003] With the development of industry, the emissions of VOCs continue to increase, and their treatment has become a key area of air pollution control. Currently, industrial VOCs purification technologies mainly include adsorption method, absorption method, catalytic combustion method, and biological method, etc. Among them, the adsorption method has become one of the mainstream technologies due to its high efficiency and selectivity, but there are still significant problems. For example, although the zeolite rotor adsorption concentration technology can reduce the energy consumption of subsequent treatment by converting large-volume, low-concentration VOCs waste gas into small-volume, high-concentration waste gas, its desorption process relies on high-temperature hot air (usually >150°C), and the energy consumption further increases when treating high-boiling VOCs; at the same time, in a high-humidity environment, water molecules compete with VOCs for adsorption sites, resulting in a decrease in adsorption efficiency, and the zeolite material is prone to failure due to carbon deposition or poisoning and needs to be replaced frequently, increasing the operating cost. Secondly, in traditional zeolite rotors, the binding force between the loaded zeolite adsorbent material and the rotor substrate (such as glass fiber, ceramic or metal substrate) is insufficient, which is another major challenge faced by the rotor technology in practical applications. The adsorbed material loaded in the rotor usually exists in powder form and needs to be fixed on the substrate surface through a binder to form a rotor structure. However, the interfacial compatibility between the traditional binder and the adsorbent material is poor, resulting in the adsorbent being easily detached from the substrate surface, especially under the working conditions of high-speed rotation or high gas flow impact. This problem of insufficient binding force not only reduces the adsorption performance of the rotor but also shortens its service life and increases the maintenance cost.

[0004] Metal-organic framework materials (MOFs) show potential in the field of VOCs adsorption due to their high specific surface area, adjustable pore structure, and chemical stability. However, it is difficult to realize continuous adsorption-regeneration operation of powder MOFs in a fixed bed. Frequent start-stop will cause material fragmentation and loss, and its synthesis cost is relatively high. When loaded on a large scale, problems such as increased mass transfer resistance and pressure drop rise are likely to occur.

[0005] Traditional absorption methods usually use liquid absorbents (such as organic solvents or aqueous solutions), but they have low selectivity for low-concentration or hydrophobic VOCs, and the absorbent may carry VOCs into subsequent treatment processes, increasing the risk of secondary pollution. At the same time, the gas-liquid contact area is limited, and the mass transfer rate is limited by the design of traditional towers.

[0006] Although membrane separation technology has received attention in the field of gas purification due to its high mass transfer efficiency and low energy consumption, existing membrane technologies (such as gas permeation membranes) still face challenges such as membrane fouling (particulates or high-boiling components in VOCs are likely to cause membrane fouling) and insufficient selectivity (it is difficult for a single membrane material to balance high permeability and high selectivity) in the purification of VOCs.

[0007] In view of the above problems, there is an urgent need to develop a VOCs gas purification technology that combines high purification efficiency, low energy consumption, strong anti-fouling ability, continuous operation, and broad applicability. Summary of the Invention

[0008] In order to solve the above-mentioned disadvantages and deficiencies, the purpose of the present invention is to provide a method and system for purifying VOCs gas by combining membrane absorption and slurry adsorption of porous adsorbent materials. The method and system provided by the present invention can at least solve the problems existing in the existing VOCs gas purification technologies, such as low purification efficiency, weak anti-fouling ability, difficult continuous operation, and insufficient broad applicability, and have many advantages such as broad applicability, fast purification efficiency, and continuous operation.

[0009] In order to achieve the above purpose, on the one hand, the present invention provides a method for purifying VOCs gas by combining membrane absorption and slurry adsorption of porous adsorbent materials, wherein the purification method includes:

[0010] Step (1): After filtering the VOCs waste gas, it is introduced into the outer space or inner space of the fibers in the membrane contactor. At the same time, the slurry of porous adsorbent material is introduced into the inner space or outer space of the fibers. Under the pressure difference between the VOCs waste gas side and the slurry side of the porous adsorbent material, part of the VOCs gas passes through the wall of the hollow fiber membrane module into the inner space or outer space of the fibers, and the target components in the VOCs gas are selectively adsorbed by the porous adsorbent material, while the slurry of porous adsorbent material cannot enter the outer space or inner space of the fibers, obtaining a slurry rich in porous adsorbent material, and the purified gas is discharged from the outer space or inner space of the fibers of the membrane contactor;

[0011] Step (2): The slurry rich in porous adsorbent material is introduced into the desorption tower and heated to desorb the VOCs adsorbed in the slurry rich in porous adsorbent material and burn the desorbed VOCs. After desorption is completed, the obtained slurry poor in porous adsorbent material is collected and recycled.

[0012] In the present invention, the space outside the fibers refers to the voids between the hollow fiber membrane modules within the membrane contactor housing and the voids between the inner wall of the housing and the hollow fiber membrane modules, which can be regarded as a whole as the "shell side", and the space inside the fibers refers to the interior of the hollow fiber membrane modules, which can be regarded as the "tube side".

[0013] In the purification method described above in the present invention, when the VOCs waste gas enters the space outside the fibers and the porous adsorbent material slurry enters the space inside the fibers, correspondingly, in the corresponding purification system, the VOCs waste gas enters the third opening (raw material inlet) through a pipeline successively via a blower, a filter, a pressure reducing valve and a first flow controller, the lean porous adsorbent material slurry storage tank is connected to the first opening (slurry inlet) through a pipeline successively via a contactor feed pump and a second flow controller, the second opening (slurry outlet) is connected to the inlet of a desorption tower through a pipeline successively via a first back pressure valve, a rich porous adsorbent material slurry storage tank and a desorption tower feed pump, the desorption product outlet of the desorption tower is connected to the inlet of a combustion furnace through a pipeline successively via a third back pressure valve, a second flowmeter and a water ring vacuum pump, the liquid phase outlet of the desorption tower is connected to the lean porous adsorbent material slurry storage tank through a pipeline via a lean slurry transfer pump, the fourth opening (purified gas outlet) is connected to a purified gas pipeline, and a second back pressure valve and a first flowmeter are successively arranged on the purified gas pipeline starting from the side of the fourth opening; at this time, both the third opening (raw material inlet) and the fourth opening (purified gas outlet) are connected to the space outside the fibers, while both the first opening (slurry inlet) and the second opening (slurry outlet) are connected to the space inside the fibers; that is, in this first case, the VOCs waste gas and the lean porous adsorbent material slurry enter the space outside the fibers and the space inside the fibers of the membrane contactor respectively according to the principles that the VOCs waste gas enters from the bottom, the purified gas exits from the top, and the slurry enters from the top and exits from the bottom.

[0014] When the VOCs waste gas enters the inner space of the fiber and the porous adsorption material slurry enters the outer space of the fiber, correspondingly, in the corresponding purification system, the VOCs waste gas enters the second opening (raw material inlet) through the pipeline successively via the blower, filter, pressure reducing valve and the first flow controller. The lean porous adsorption material slurry storage tank is communicated with the fourth opening (slurry inlet) through the pipeline successively via the contactor feed pump and the second flow controller. The third opening (slurry outlet) is communicated with the inlet of the desorption tower through the pipeline successively via the first back pressure valve, the rich porous adsorption material slurry storage tank and the desorption tower feed pump. The desorption product outlet of the desorption tower is communicated with the inlet of the combustion furnace through the pipeline successively via the third back pressure valve, the second flow meter and the water ring vacuum pump. The liquid phase outlet of the desorption tower is communicated with the lean porous adsorption material slurry storage tank through the pipeline via the lean slurry transfer pump. The first opening (purified gas outlet) is communicated with the purified gas pipeline, and a second back pressure valve and a first flow meter are successively arranged on the purified gas pipeline starting from the side of the first opening; at this time, both the second opening (raw material inlet) and the first opening (purified gas outlet) are communicated with the inner space of the fiber, and both the fourth opening (slurry inlet) and the third opening (slurry outlet) are communicated with the outer space of the fiber; correspondingly, that is, in this second case, the VOCs waste gas and the lean porous adsorption material slurry also enter the inner space of the fiber and the outer space of the fiber of the membrane contactor respectively according to the principle that the VOCs waste gas enters from the bottom, the purified gas exits from the top, and the slurry enters from the top and exits from the bottom.

[0015] The purification method described above in the present invention is preferably carried out according to the first case, that is, preferably, the VOCs waste gas and the lean porous adsorption material slurry enter the outer space and the inner space of the fiber of the membrane contactor respectively according to the principle that the VOCs waste gas enters from the bottom, the purified gas exits from the top, and the slurry enters from the top and exits from the bottom.

[0016] The viscosity of the lean porous adsorption material slurry used in the purification method described above in the present invention must be greater than that of the VOCs waste gas. Therefore, making the VOCs waste gas enter from the bottom, the purified gas exit from the top, and the slurry enter from the top and exit from the bottom is more conducive to the flow of the slurry and is also more energy-saving.

[0017] As a specific embodiment of the purification method described above of the present invention, the purification method further includes: using a VOCs gas detector to monitor the concentration of VOCs components in the purified gas in real time. If the concentration of VOCs components in the purified gas meets the relevant emission standards, the purified gas is directly discharged. If the concentration of VOCs components in the purified gas does not meet the relevant emission standards, then one or more of the flow rate of the porous adsorbent material slurry, the flow rate of the rich porous adsorbent material slurry, the flow rate of the VOCs waste gas, the pressure and flow rate of the filtered VOCs waste gas (which is controlled by a first flow controller), the pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side, and the desorption pressure are dynamically adjusted, and then the purification of the VOCs waste gas is continued until the concentration of VOCs components in the purified gas meets the relevant emission standards and then it is discharged.

[0018] In the purification method described above of the present invention, the flow rate of the porous adsorbent material slurry and the flow rate of the rich porous adsorbent material slurry are respectively controlled by a contactor feed pump and a desorption tower feed pump, the flow rate of the VOCs waste gas is controlled by a blower, the pressure of the filtered VOCs waste gas is controlled by a pressure reducing valve, the flow rate of the filtered VOCs waste gas is controlled by a first flow controller, the pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side is controlled by a second back pressure valve and a first back pressure valve, and the desorption pressure is controlled by a third back pressure valve. In the purification method described above of the present invention, the pressure inside the desorption tower is controlled within a reasonable numerical range, that is, within 5 - 20 kPa, by the third back pressure valve. If the pressure inside the desorption tower is too small, the solvent in the slurry is easily extracted and the pipeline is blocked, while if the pressure inside the desorption tower is too large, the desorption effect may be too poor.

[0019] As a specific embodiment of the purification method described above of the present invention, the purification method further includes: using an alkali solution to absorb the acidic gas obtained by combustion treatment.

[0020] In the purification method described above of the present invention, the VOCs waste gas side and the porous adsorbent material slurry side respectively refer to the regions where the VOCs waste gas and the porous adsorbent material slurry enter. For example, when the VOCs waste gas enters the outer space of the fiber and the porous adsorbent material slurry enters the inner space of the fiber, the outer space of the fiber and the inner space of the fiber are respectively the VOCs waste gas side and the porous adsorbent material slurry side. It should be noted that an appropriate pressure difference should be maintained between the VOCs waste gas side and the porous adsorbent material slurry side. If the pressure on the VOCs waste gas side is too large, a large amount of VOCs waste gas raw materials will enter the porous adsorbent material slurry, resulting in a poor separation effect. If the pressure on the porous adsorbent material slurry side is too large, the fiber bundle will be damaged.

[0021] As a specific embodiment of the purification method described above in the present invention, the pressure on the VOCs waste gas side is controlled to be not lower than the pressure on the porous adsorbent material slurry side, and the pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side is 0 - 10 kPa. During specific implementation, the pressure difference between the second backpressure valve and the first backpressure valve is set to be 0 - 10 kPa by controlling the pressures set by the two valves. Under this relatively small pressure difference condition, some VOCs in the VOCs waste gas can pass through the wall of the hollow fiber membrane module and come into contact with the porous adsorbent material slurry for adsorption, while preventing a large amount of VOCs waste gas from passing through the wall of the hollow fiber membrane module, so as to improve the separation effect. Because if the pressure difference is large, many components that cannot be adsorbed by the porous adsorbent material slurry will be squeezed into the porous adsorbent material slurry, resulting in a decrease in its purification effect.

[0022] In addition, in the purification method described above in the present invention, in addition to controlling the pressure on the VOCs waste gas side to be not lower than the pressure on the porous adsorbent material slurry side, and the pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side to be 0 - 10 kPa, theoretically, the higher the pressures of the second backpressure valve and the first backpressure valve, the better. However, a higher pressure means that each device in the purification system, especially the membrane contactor and the desorption tower, etc., needs to withstand higher strength, which will also lead to an increase in the purification cost. Therefore, in a specific embodiment of the purification method described above in the present invention, the pressures of the second backpressure valve and the first backpressure valve are respectively controlled to be slightly higher than the atmospheric pressure, preferably 110 - 150 kPa.

[0023] As a specific embodiment of the purification method described above in the present invention, the residence time of the VOCs waste gas in the membrane contactor is 1 - 20 min, and the residence time of the porous adsorbent material slurry in the membrane contactor is 5 - 60 min.

[0024] As a specific embodiment of the purification method described above in the present invention, the material of the hollow fiber membrane module includes one or a combination of several of polytetrafluoroethylene (PTFE), polysulfone (PS), polyethersulfone (PES), polyethylene (PE), etc.

[0025] As a specific embodiment of the purification method described above in the present invention, the inner diameter of the hollow fiber membrane module is 0.5 - 10 mm, the wall thickness is 0.01 - 2 mm, the porosity is 40 - 80%, and the pore size distribution is 0.01 - 5 μm.

[0026] Theoretically, the present invention does not make specific requirements on the number of hollow fiber membrane modules, and can be reasonably selected and adjusted according to needs. For example, the number of hollow fiber membrane modules can be about dozens to 100. As the membrane contactor is enlarged, the number of hollow fiber membrane modules also increases, and can be up to about 1000, or even as high as about 10000.

[0027] In the purification method described above of the present invention, the desorption process needs to be carried out under stirring conditions. Correspondingly, a stirring device needs to be provided in the desorption tower. The stirring device can be an existing conventional stirring device and can be reasonably selected as required. For example, in some specific embodiments of the present invention, the stirring device can be a stirring paddle or the like.

[0028] As a specific embodiment of the purification method described above of the present invention, in the desorption carried out in the desorption tower, intermittent operation is adopted.

[0029] As a specific embodiment of the purification method described above of the present invention, the porous adsorbent material slurry is a solid-liquid suspension slurry, which is formed by uniformly dispersing the porous adsorbent material in a solvent and contains the porous adsorbent material and the solvent. Calculated based on the total mass of the porous adsorbent material slurry being 100%, the content of the porous adsorbent material is 5-50%.

[0030] As a specific embodiment of the purification method described above of the present invention, the porous adsorbent material includes one or a combination of several of metal-organic framework materials, covalent organic framework materials, molecular sieves, etc.

[0031] As a specific embodiment of the purification method described above of the present invention, the porous adsorbent material includes one or two of ZIF-8 and CALF-20, etc.

[0032] As a specific embodiment of the purification method described above of the present invention, the solvent includes one or a combination of several of water, alcohol solvents, ketone solvents, hydrocarbon solvents, etc.

[0033] As a specific embodiment of the purification method described above of the present invention, the solvent includes one or a combination of several of water, N,N-dimethylacetamide (DMAC), 1,3-dimethylpropyleneurea (DMPU), N-methylpyrrolidone (NMP), etc. In some embodiments of the present invention, the water can be, for example, high-purity water.

[0034] As a specific embodiment of the purification method described above of the present invention, the VOCs include one or a combination of several components such as alkanes, alkenes, halogenated hydrocarbons, alcohols, and aldehyde ketones.

[0035] As a specific embodiment of the purification method described above of the present invention, the VOCs include one or a combination of several of ethane, propane, n-butane, n-pentane, n-hexane, ethylene, propylene, dichloromethane, methanol, and acetone, etc.

[0036] In the purification method of the present invention described above, when the VOCs waste gas contains components such as ethane, propane, ethylene, and propylene, their concentrations are preferably controlled within 2000 ppm respectively. When the VOCs waste gas contains n-butane and n-pentane components, their concentrations are preferably controlled within 1000 ppm respectively. When the VOCs waste gas contains n-hexane and dichloromethane components, their concentrations are preferably controlled within 500 ppm respectively, and when the VOCs waste gas contains methanol and acetone components, their concentrations are preferably controlled within 200 ppm respectively.

[0037] On the other hand, the present invention also provides a VOCs gas purification system for realizing the VOCs gas purification method of membrane absorption combined with slurry adsorption of porous adsorbent materials described above. Among them, the system includes:

[0038] A membrane contactor, a lean porous adsorbent material slurry storage tank, a rich porous adsorbent material slurry storage tank, a desorption tower, and a combustion furnace;

[0039] The membrane contactor includes a housing and a plurality of hollow fiber membrane modules. The housing includes a shell body, an upper end cover, and a lower end cover respectively provided at the upper and lower ends of the shell body. The plurality of hollow fiber membrane modules are arranged in the shell body in a manner parallel to the central axis of the shell body, and the upper and lower ends of the plurality of hollow fiber membrane modules are respectively communicated with the upper end cover and the lower end cover. The upper end cover and the lower end cover are respectively provided with a first opening and a second opening, and the lower and upper parts of the outer side wall of the shell body are respectively provided with a third opening and a fourth opening;

[0040] The VOCs waste gas enters the third opening through a pipeline successively via a blower, a filter, a pressure reducing valve, and a first flow controller. The lean porous adsorbent material slurry storage tank is communicated with the first opening through a pipeline successively via a contactor feed pump and a second flow controller. The second opening is communicated with the inlet of the desorption tower through a pipeline successively via a first back pressure valve, a rich porous adsorbent material slurry storage tank, and a desorption tower feed pump. The desorption product outlet of the desorption tower is communicated with the inlet of the combustion furnace through a pipeline successively via a third back pressure valve, a second flow meter, and a water ring vacuum pump. The liquid phase outlet of the desorption tower is communicated with the lean porous adsorbent material slurry storage tank through a pipeline via a lean slurry transfer pump. The fourth opening is communicated with a purified gas pipeline, and a second back pressure valve and a first flow meter are successively arranged on the purified gas pipeline starting from the fourth opening side;

[0041] Alternatively, the VOCs waste gas enters the second opening successively through a pipeline via a blower, a filter, a pressure reducing valve, and a first flow controller. The lean porous adsorbent slurry storage tank is connected to the fourth opening through a pipeline successively via a contactor feed pump and a second flow controller. The third opening is connected to the inlet of a desorption tower through a pipeline successively via a first back pressure valve, a rich porous adsorbent slurry storage tank, and a desorption tower feed pump. The desorption product outlet of the desorption tower is connected to the inlet of a combustion furnace through a pipeline successively via a third back pressure valve, a second flowmeter, and a water ring vacuum pump. The liquid phase outlet of the desorption tower is connected to the lean porous adsorbent slurry storage tank through a pipeline via a lean slurry transfer pump. The first opening is connected to a purified gas pipeline, and a second back pressure valve and a first flowmeter are successively arranged on the purified gas pipeline starting from the first opening side.

[0042] As a specific embodiment of the purification system described above in the present invention, the purification system further includes an alkali liquor absorption tank, and the outlet of the combustion furnace is connected to the alkali liquor absorption tank through a pipeline.

[0043] As a specific embodiment of the purification system described above in the present invention, the purification system further includes a VOCs gas detector, which is arranged on the purified gas pipeline and close to the purified gas outlet.

[0044] As a specific embodiment of the purification system described above in the present invention, the purification system further includes a computer control system, which is electrically connected to the blower, the pressure reducing valve, the first flow controller, the contactor feed pump, the second flow controller, the first back pressure valve, the desorption tower feed pump, the third back pressure valve, the second flowmeter, the water ring vacuum pump, the lean slurry transfer pump, the second back pressure valve, the first flowmeter, and the VOCs gas detector respectively.

[0045] In the purification system described above in the present invention, the first flowmeter and the second flowmeter can only display flow values, while flow controllers such as the first flow controller and the second flow controller can control the flow and display the flow values.

[0046] The computer control system used in the present invention integrates and automatically controls the operation of the entire system, and can collect sensor signals of each key node in real time, including parameter signals such as temperature, pressure, and flow rate. Based on preset algorithms and logics, the computer control system receives in real time the concentration of the purified gas monitored by the VOCs gas detector and determines whether it meets the relevant emission standards, such as the "Emission Standard for Unorganized Emission of Volatile Organic Compounds" (GB 37822-2019) and other relevant emission standards. If it meets the standards, the purified gas is directly discharged. If it does not meet the standards, it is fed back to the control algorithm to dynamically adjust the operating parameters of valves (such as the first back pressure valve and the second back pressure valve, etc.), pump speeds (such as the contactor feed pump, etc.), and the blower, so as to optimize key parameters such as the slurry circulation rate and the operating conditions of the desorption tower. Finally, after ensuring that the purification efficiency meets the standards, the purified gas is directly discharged. In short, the computer control system can dynamically optimize the operating parameters to ensure that the purification efficiency meets the standards. It can also monitor the operating status of the entire purification system in real time, identify abnormal operating conditions, trigger the automatic protection mechanism, and ensure the safety of the equipment and the stability of the process. Compared with the prior art, the beneficial technical effects that can be achieved by the VOCs gas purification method and system provided by the present invention, which combines membrane absorption with slurry adsorption of porous adsorbent materials, include:

[0047] The purification system and method provided by the present invention mainly involve modules such as membrane contactors, slurry circulation units, and regeneration units. Among them, multiple hollow fiber membrane modules in the membrane contactor form a multi-stage cross-flow contact channel, and gas-liquid countercurrent flow and efficient mass transfer can be realized through the micropores on the wall of the hollow fiber membrane module; the slurry circulation unit uses a porous adsorbent material slurry formed by uniformly dispersing a porous adsorbent material in a solvent, which can selectively adsorb VOCs components; the regeneration unit can realize the recycling of the slurry through heating desorption and vacuum assistance.

[0048] In summary, the purification system and method provided by the present invention couple the porous adsorbent material slurry with the hollow fiber contactor, giving full play to the advantages of the porous adsorbent material slurry method in terms of broad-spectrum applicability and fast purification efficiency. At the same time, by using the design of the hollow fiber contactor, it overcomes the limitations of the existing zeolite rotor adsorption and concentration technology, which cannot achieve continuous operation, has a low purification rate, low selectivity of the absorption method, and poor anti-pollution performance of the membrane separation method, and realizes an efficient and stable purification process. It has the advantages of high purification efficiency, low energy consumption, strong anti-pollution performance, and broad-spectrum applicability (covering alkanes, alkenes, halogenated hydrocarbons, etc.), and is especially suitable for the treatment of industrial low-concentration VOCs waste gas. Description of the Drawings

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0050] Figure 1 FIG. is a schematic structural diagram of a VOCs gas purification system combining membrane absorption and slurry absorption of porous adsorbent materials provided in Embodiment 1 of the present invention.

[0051] Figure 2 FIG. is a schematic structural diagram of a VOCs gas purification system combining membrane absorption and slurry absorption of porous adsorbent materials provided in Embodiment 2 of the present invention.

[0052] Figure 3 FIG. is a schematic diagram showing the mass transfer of the VOCs waste gas to be purified and the porous adsorbent material slurry through a multi-stage cross-flow contact channel in Embodiment 1-1 of the present invention.

[0053] Figure 4 FIG. is an X-ray diffraction pattern of fresh ZIF-8 powder used in Embodiment 1-1 of the present invention and ZIF-8 powder recovered from ZIF-8 / 1,3-dimethylpropyleneurea slurry after 5 adsorption-desorption cycle experiments.

[0054] Main reference numeral descriptions:

[0055] Figure 1 - Figure 2 In which:

[0056] 1. Membrane contactor, 11. Inner fiber space, 12. Outer fiber space;

[0057] 21. Lean porous adsorbent material slurry storage tank, 22. Contactor feed pump, 23. Second flow controller, 24. First back pressure valve, 25. Rich porous adsorbent material slurry storage tank, 210. Feeding port;

[0058] 31. Blower, 32. Filter, 33. Pressure reducing valve, 34. First flow controller, 35. Second back pressure valve, 36. First flowmeter, 37. VOCs gas detector;

[0059] 41. Desorption tower feed pump, 42. Desorption tower, 43. Third back pressure valve, 44. Second flowmeter, 45. Water ring vacuum pump, 46. Combustion furnace, 47. Alkaline solution absorption tank, 48. Lean slurry transfer pump;

[0060] 51. Computer control system. Detailed implementation manners

[0061] It should be noted that the term "including" and any variations thereof in the description, claims and above-mentioned drawings of the present invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily limit to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0062] The "ranges" disclosed in the present invention are given in the form of lower and upper limits. There can be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundary of a particular range. All ranges defined in this way are combinable, that is, any lower limit can be combined with any upper limit to form a range. For example, ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, and ranges of 60 - 110 and 80 - 120 are understood to be also anticipated. In addition, if the minimum range values listed are 1 and 2, and the maximum range values listed are 3, 4 and 5, then the following ranges are all anticipated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4 and 2 - 5.

[0063] In the present invention, unless otherwise stated, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed in the present invention, and "0 - 5" is just an abbreviated representation of these numerical combinations.

[0064] In the present invention, if there is no special description, all embodiments and preferred embodiments mentioned in the present invention can be combined with each other to form new technical solutions.

[0065] In the present invention, if there is no special description, all technical features and preferred features mentioned in the present invention can be combined with each other to form new technical solutions.

[0066] In the present invention, if there is no special description, all steps mentioned herein can be carried out in sequence or randomly, but preferably in sequence. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out in sequence, or can also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c), or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.

[0067] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0068] Embodiment 1

[0069] This embodiment provides a VOCs gas purification system that combines membrane absorption and slurry absorption of porous adsorbent materials. The structural schematic diagram is as Figure 1 shown. It can be seen from Figure 1 that the system includes:

[0070] a membrane contactor 1, a lean porous adsorbent material slurry storage tank 21, a rich porous adsorbent material slurry storage tank 25, a desorption tower 42, a combustion furnace 46, an alkali solution absorption tank 47, and a computer control system 51;

[0071] The membrane contactor 1 includes a housing and a plurality of hollow fiber membrane modules. The housing includes a shell and upper and lower end caps respectively provided at the upper and lower ends of the shell. The plurality of hollow fiber membrane modules are arranged in the shell in a manner parallel to the central axis of the shell, and the upper and lower ends of the plurality of hollow fiber membrane modules are respectively communicated with the upper and lower end caps; the upper and lower end caps are respectively provided with a first opening and a second opening, and the lower and upper parts of the outer side wall of the shell are respectively provided with a third opening and a fourth opening;

[0072] VOCs waste gas enters the third opening (raw material inlet) through a pipeline successively via a blower 31, a filter 32, a pressure reducing valve 33, and a first flow controller 34, and thus enters the outer space 12 of the fibers inside the housing. The lean porous adsorbent slurry storage tank 21 is communicated with the first opening (slurry inlet) through a pipeline successively via a contactor feed pump 22 and a second flow controller 23. Thus, the porous adsorbent slurry enters the hollow fiber membrane module, that is, the inner space 11 of the fibers. The second opening (slurry outlet) is communicated with the inlet of a desorption tower 42 through a pipeline successively via a first back pressure valve 24, a rich porous adsorbent slurry storage tank 25, and a desorption tower feed pump 41. The desorption product outlet of the desorption tower 42 is communicated with the inlet of a combustion furnace 46 through a pipeline successively via a third back pressure valve 43, a second flowmeter 44, and a water ring vacuum pump 45. The outlet of the combustion furnace 46 is communicated with the alkali liquor absorption tank 47 through a pipeline. The liquid phase outlet of the desorption tower 42 is communicated with the feeding port 210 of the lean porous adsorbent slurry storage tank 21 through a pipeline via a lean slurry transfer pump 48. The fourth opening (purified gas outlet) is communicated with a purified gas pipeline, and a second back pressure valve 35, a first flowmeter 36, and a VOCs gas detector 37 are successively arranged on the purified gas pipeline starting from the side of the fourth opening;

[0073] The computer control system 51 is electrically connected to the blower 31, the pressure reducing valve 33, the first flow controller 34, the contactor feed pump 22, the second flow controller 23, the first back pressure valve 24, the desorption tower feed pump 41, the third back pressure valve 43, the second flowmeter 44, the water ring vacuum pump 45, the lean slurry transfer pump 48, the second back pressure valve 35, the first flowmeter 36, and the VOCs gas detector 37 respectively.

[0074] Example 2

[0075] This example provides a VOCs gas purification system combining membrane absorption and adsorption of a porous adsorbent slurry. The structural schematic diagram is as Figure 2 shown. It can be seen from Figure 2 that the system includes:

[0076] a membrane contactor 1, a lean porous adsorbent slurry storage tank 21, a rich porous adsorbent slurry storage tank 25, a desorption tower 42, a combustion furnace 46, an alkali liquor absorption tank 47, and a computer control system 51;

[0077] The membrane contactor 1 includes a housing and a plurality of hollow fiber membrane modules. The housing includes a shell and an upper end cover and a lower end cover respectively arranged at the upper and lower ends of the shell. The plurality of hollow fiber membrane modules are arranged in the shell in a manner parallel to the central axis of the shell, and the upper and lower ends of the plurality of hollow fiber membrane modules are respectively communicated with the upper end cover and the lower end cover; the upper end cover and the lower end cover are respectively provided with a first opening and a second opening, and the lower part and the upper part of the outer side wall of the shell are respectively provided with a third opening and a fourth opening;

[0078] The VOCs waste gas enters the second opening (raw material inlet) successively via a blower 31, a filter 32, a pressure reducing valve 33 and a first flow controller 34 through a pipeline, and thus enters the hollow fiber membrane module, that is, the inner space 11 of the fiber. The lean porous adsorbent slurry storage tank 21 is communicated with the fourth opening (slurry inlet) successively via a contactor feed pump 22 and a second flow controller 23 through a pipeline. Thus, the porous adsorbent slurry enters the outer space 12 of the fiber inside the shell. The third opening (slurry outlet) is communicated with the inlet of a desorption tower 42 successively via a first back pressure valve 24, a rich porous adsorbent slurry storage tank 25 and a desorption tower feed pump 41 through a pipeline. The desorption product outlet of the desorption tower 42 is communicated with the inlet of a combustion furnace 46 successively via a third back pressure valve 43, a second flowmeter 44 and a water ring vacuum pump 45 through a pipeline. The outlet of the combustion furnace 46 is communicated with the alkali liquor absorption tank 47 through a pipeline. The liquid phase outlet of the desorption tower 42 is communicated with the feeding port 210 of the lean porous adsorbent slurry storage tank 21 via a lean slurry transfer pump 48 through a pipeline. The first opening (purified gas outlet) is communicated with a purified gas pipeline, and a second back pressure valve 35, a first flowmeter 36 and a VOCs gas detector 37 are successively arranged on the purified gas pipeline starting from the first opening side;

[0079] The computer control system 51 is electrically connected to the blower 31, the pressure reducing valve 33, the first flow controller 34, the contactor feed pump 22, the second flow controller 23, the first back pressure valve 24, the desorption tower feed pump 41, the third back pressure valve 43, the second flowmeter 44, the water ring vacuum pump 45, the lean slurry transfer pump 48, the second back pressure valve 35, the first flowmeter 36 and the VOCs gas detector 37 respectively.

[0080] Example 1-1

[0081] This example provides a method for purifying VOCs gas by membrane absorption combined with adsorption of porous adsorbent slurry, which is realized by using the VOCs gas purification system provided in Example 1. In this example, the inner diameter of the outer shell of the membrane contactor used is 8 cm, the wall thickness is 1 cm, the length is 0.2 m, and 40 hollow fiber membrane modules are placed inside. The material of the hollow fiber membrane module is PTFE, the length is 0.2 m, the inner diameter is 8 mm, the wall thickness is 1 mm, the porosity is 50%, and the pore diameter is 0.1 μm.

[0082] The porous adsorbent material slurry used is composed of ZIF-8, 1,3-dimethylpropyleneurea, and water with a mass ratio of 3:5:2; the molar composition of the targeted VOCs waste gas is: 77.868842% nitrogen, 21.457879% oxygen, 0.22582% ethane, 0.153552% propane, 0.092575% n-butane, 0.062454% n-pentane, 0.02415% n-hexane, 0.015744% ethylene, 0.02255% propylene, 0.055278% dichloromethane, 0.011032% methanol, and 0.010124% acetone;

[0083] Among them, the purification method includes the following specific steps:

[0084] Step (1): Turn on the blower through the computer control system, and transport the above-mentioned VOCs waste gas prepared in advance to the filter through the blower for filtration to remove non-gaseous substances such as solid particles. After adjusting the pressure of the pressure reducing valve to 120 kPa and the flow rate of the first flow controller to 75.4 ml / min, the filtered VOCs waste gas to be purified is transported to the outer space of the fibers in the membrane contactor. At the same time, open the lean porous adsorbent material slurry storage tank, turn on the contactor feed pump and adjust the flow rate of the second flow controller to 20.1 ml / min, and transport the above-mentioned porous adsorbent material slurry into the hollow fiber membrane module, that is, the inner space of the fibers;

[0085] Adjust the pressure of the second back pressure valve to 120 kPa and the pressure of the first back pressure valve to 120 kPa. The slurry and the VOCs waste gas to be purified flow reversely in the membrane contactor through multiple hollow fiber membrane modules in the membrane contactor. During this process, part of the VOCs gas passes through the wall of the hollow fiber membrane module and enters the hollow fiber membrane module, and the target components in the VOCs gas are selectively adsorbed by the porous adsorbent material, that is, ZIF-8, through surface diffusion and pore confinement effect, to obtain a rich porous adsorbent material slurry. Among them, the schematic diagram of the mass transfer of the VOCs waste gas to be purified and the porous adsorbent material slurry through the multi-stage cross-flow contact channel is as Figure 3 shown; in this embodiment, the residence time of the VOCs waste gas in the membrane contactor is 5 min, and the residence time of the porous adsorbent material slurry in the membrane contactor is 20 min;

[0086] The purified gas is discharged from the outer space of the fiber through the purified gas pipeline. Before the purified gas is discharged, it is detected in real time by a VOCs gas detector, and the detection results are transmitted back to the computer control system in real time. The computer control system determines whether it meets the relevant emission standards such as the "Emission Standard for Unorganized Emission of Volatile Organic Compounds" (GB 37822-2019). If the concentration of VOCs components in the purified gas meets the relevant emission standards, the purified gas is directly discharged. If the concentration of VOCs components in the purified gas does not meet the relevant emission standards, one or more of the flow rate of the porous adsorption material slurry, the flow rate of the rich porous adsorption material slurry, the flow rate of the VOCs waste gas, the pressure of the VOCs waste gas to be purified, the pressure difference between the VOCs waste gas side and the porous adsorption material slurry side, and the desorption pressure are dynamically adjusted through the computer control system, and then the purification of the VOCs waste gas is continued until the concentration of VOCs components in the purified gas meets the relevant emission standards and then it is discharged;

[0087] Before the purified gas in this embodiment is discharged, it is detected in real time by a VOCs gas detector and it is found that the concentration of VOCs components in the purified gas is 9.66 mg / m 3 , which meets the relevant emission standards, and then it is directly discharged;

[0088] At the same time, gas is taken from the purified gas outlet and analyzed by chromatography. The analysis results show that only 2.67 ppm ethane, 1.80 ppm propane, 0.76 ppm n-butane, and 0.22 ppm acetone are detected in the purified gas, while n-pentane, n-hexane, ethylene, propylene, dichloromethane, and methanol are not detected. It can be seen that the purification rate of various VOCs gases in this embodiment is above 99.78%. Among them, the compositions of the VOCs waste gas and the purified gas are analyzed by an HP7890B chromatograph.

[0089] Step (2): The rich porous adsorption material slurry loaded with the target components in the VOCs gas enters the rich porous adsorption material slurry storage tank, and enters the desorption tower with a stirring device from the rich porous adsorption material slurry storage tank through the desorption tower feed pump; heating is started and heated to 95 °C, and at the same time, a water ring vacuum pump is started, and the pressure of the third back pressure valve is adjusted to 10 kPa to desorb the VOCs gas in the rich porous adsorption material slurry and discharge it from the desorption product outlet into the combustion furnace for combustion treatment. The acidic gases such as carbon dioxide and hydrogen chloride generated by combustion enter the alkali liquor absorption pool for absorption. After desorption is completed, the desorbed lean slurry is transported by the lean slurry transfer pump through the liquid phase outlet of the desorption tower to the lean porous adsorption material slurry storage tank for recycling. At the same time, the slurry can also be supplemented through the feeding port of the lean porous adsorption material slurry storage tank.

[0090] Meanwhile, after 5 cycles of repeated absorption and regeneration, the purification performance of the slurry did not show any decline. Subsequently, the reused slurry was dried to recover the ZIF-8 material, and then the fresh and recovered ZIF-8 materials were subjected to structural characterization. The obtained X-ray diffraction pattern is as shown in Figure 4 . Figure 4 The characterization results shown in

[0091] Example 1-2

[0092] This example provides a method for purifying VOCs gas by membrane absorption combined with slurry absorption of porous adsorbent materials, which is only different from Example 1-1 in that:

[0093] The pressure of the second back pressure valve is adjusted to 140 kPa.

[0094] Gas was taken from the purified gas outlet and analyzed by chromatography. The analysis results showed that 70.62 ppm of ethane, 54.41 ppm of propane, 23.46 ppm of n-butane, and 6.62 ppm of acetone were detected in the purified gas, while n-pentane, n-hexane, ethylene, propylene, dichloromethane, and methanol were not detected. Comparing the experimental results of Example 1-1 and Example 1-2, it can be seen that in Example 1-2, due to the relatively large pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side, the purification rate decreased. At the same time, due to the relatively large pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side, a large amount of gas entered the inner space of the fiber, resulting in a significant decrease in the flow rate of the purified gas outlet on the VOCs waste gas side compared to the raw material inlet flow rate. Intuitively, the reading of the first flow meter decreased from the original 75.4 ml / min to 56.5 ml / min, a decrease of about one-fourth. In addition, the relatively large pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side also caused a large amount of air in the waste gas to enter the inner space of the fiber and then enter the storage tank of the slurry rich in porous adsorbent material through the inner space of the fiber. Finally, it was transported to the desorption tower, and a large amount of foaming occurred during desorption, resulting in the slurry gushing out from the desorption product outlet of the desorption tower, affecting the normal operation of the device.

[0095] Example 2-1

[0096] This embodiment provides a method for purifying VOCs gas by membrane absorption combined with slurry absorption of porous adsorbents, which is realized by using the VOCs gas purification system of membrane absorption combined with slurry absorption of porous adsorbents provided in Embodiment 2. The inner diameter of the outer shell in the membrane contactor used in this embodiment is 8 cm, the wall thickness is 1 cm, and the length is 0.2 m. 40 hollow fiber membrane modules are placed inside it. The material of the hollow fiber membrane module is PTFE, the length is 0.2 m, the inner diameter is 8 mm, the wall thickness is 1 mm, the porosity is 50%, the pore size distribution is 0.1 μm. The porous adsorbent slurry used is composed of ZIF-8, 1,3-dimethylpropyleneurea and water with a mass ratio of 3:5:2. The molar composition of the VOCs waste gas targeted is: 77.868842% nitrogen, 21.457879% oxygen, 0.22582% ethane, 0.153552% propane, 0.092575% n-butane, 0.062454% n-pentane, 0.02415% n-hexane, 0.015744% ethylene, 0.02255% propylene, 0.055278% dichloromethane, 0.011032% methanol and 0.010124% acetone;

[0097] Among them, the purification method includes the following specific steps:

[0098] Step (1): Turn on the blower through the computer control system, and transport the above-mentioned VOCs waste gas prepared in advance to the filter through the blower for filtration to remove non-gaseous substances such as solid particles. After adjusting the pressure of the pressure reducing valve to 120 kPa and the flow rate of the first flow controller to 80.4 ml / min, the filtered VOCs waste gas to be purified is transported into the hollow fiber membrane module inside the membrane contactor, that is, the inner space of the fiber. At the same time, open the lean porous adsorbent slurry storage tank, turn on the contactor feed pump and adjust the flow rate of the second flow controller to 18.85 ml / min, and transport the above-mentioned porous adsorbent slurry to the outer space of the fiber inside the membrane contactor;

[0099] Adjust the pressure of the second back pressure valve to 120 kPa and the pressure of the first back pressure valve to 120 kPa. The slurry and the VOCs waste gas to be purified flow reversely inside the membrane contactor through multiple hollow fiber membrane modules inside the membrane contactor. During this process, part of the VOCs gas passes through the wall of the hollow fiber membrane module and enters the outer space of the fiber, and the target components in the VOCs gas are selectively adsorbed by the porous adsorbent, that is, ZIF-8, through surface diffusion and pore confinement effect, to obtain a rich porous adsorbent slurry. Among them, the schematic diagram of the mass transfer of the VOCs waste gas to be purified and the porous adsorbent slurry through the multi-stage cross-flow contact channel is as Figure 3 shown; In this embodiment, the residence time of the VOCs waste gas in the membrane contactor is 5 min, and the residence time of the porous adsorbent slurry in the membrane contactor is 20 min;

[0100] The purified gas is discharged from the inner space of the fiber through the purified gas pipeline. Before the purified gas is discharged, it is subjected to real-time detection by a VOCs gas detector, and the detection results are transmitted back to the computer control system in real time. The computer control system determines whether it meets the relevant emission standards such as the "Control Standard for Unorganized Emission of Volatile Organic Compounds" (GB 37822-2019). If the concentration of VOCs components in the purified gas meets the relevant emission standards, the purified gas is directly discharged. If the concentration of VOCs components in the purified gas does not meet the relevant emission standards, one or more of the flow rate of the porous adsorbent material slurry, the flow rate of the rich porous adsorbent material slurry, the flow rate of the VOCs waste gas, the pressure of the VOCs waste gas to be purified, the pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side, and the desorption pressure are dynamically adjusted through the computer control system, and then the purification of the VOCs waste gas is continued until the concentration of VOCs components in the purified gas meets the relevant emission standards and then it is discharged;

[0101] Before the purified gas in this embodiment is discharged, it is subjected to real-time detection by a VOCs gas detector, and it is found that the concentration of VOCs components in the purified gas is 9.96 mg / m 3 , which meets the relevant emission standards, and then it is directly discharged;

[0102] At the same time, gas is taken from the purified gas outlet and analyzed by chromatography. The analysis results show that only 2.74 ppm ethane, 1.86 ppm propane, 0.78 ppm n-butane, and 0.23 ppm acetone are detected in the purified gas, while n-pentane, n-hexane, ethylene, propylene, dichloromethane, and methanol are not detected. It can be seen that the purification rate of various VOCs gases in this embodiment is above 99.77%. Among them, the compositions of the VOCs waste gas and the purified gas are also obtained by analyzing with an HP7890B type chromatograph. Compared with Example 1-1, in Example 2-1, the VOCs waste gas enters the inner space of the fiber, while the porous adsorbent material slurry enters the outer space of the fiber. Comparing the experimental results of the two, it can be seen that the purification effect in Example 2-1 is slightly worse than that in Example 1-1.

[0103] Step (2): The slurry of the rich porous adsorbent material for the target component in the VOCs gas enters the storage tank of the rich porous adsorbent material slurry, and enters the desorption tower with a stirring device from the storage tank of the rich porous adsorbent material slurry through the desorption tower feed pump; start heating and heat to 95 °C, and at the same time start the water ring vacuum pump, adjust the pressure of the third back pressure valve to 10 kPa, so that the VOCs gas in the rich porous adsorbent material slurry is desorbed and discharged from the desorption product outlet and enters the combustion furnace for combustion treatment. The acidic gases such as carbon dioxide and hydrogen chloride generated by combustion enter the alkali liquor absorption pool for absorption. After desorption is completed, the poor slurry after desorption is transported by the poor slurry transfer pump through the liquid phase outlet of the desorption tower to the storage tank of the poor porous adsorbent material slurry for recycling. At the same time, the slurry can also be supplemented through the feeding port of the storage tank of the poor porous adsorbent material slurry.

[0104] At the same time, after 5 times of repeated absorption and regeneration, the purification performance of the slurry did not show any decline. Subsequently, the repeatedly used slurry was dried and the ZIF-8 material therein was recovered, and then the fresh ZIF-8 material and the recovered ZIF-8 material were subjected to structural characterization. The characterization results showed that: the characteristic structure of the recovered ZIF-8 was basically the same as that of the fresh ZIF-8, indicating that the structure of the ZIF-8 material remained intact after being repeatedly used many times.

[0105] Comparative Example 1

[0106] This comparative example provides a method for purifying VOCs gas, which uses the small-scale experimental device described in paragraphs

[0023] and

[0024] of the specification of CN102389686A to conduct the VOCs gas purification experiment. During the experiment, the same VOCs waste gas and porous adsorbent material slurry as those in Example 1-1 of the present invention were used. The specific operation of the experimental process was as follows: Use a balance kettle to fill the sapphire kettle with 120 kPa of VOCs waste gas. After 30 minutes, take gas from the purified gas outlet and analyze it with a chromatograph. The analysis results showed that: the composition of the purified gas was not much different from that of the purified gas obtained in Example 1-1 of the present invention. However, in Comparative Example 1, the treatment amount of the VOCs waste gas was only 100 ml / h, while the treatment amount of the VOCs waste gas in Example 1-1 of the present invention could be as high as 4500 ml / h. In the experimental devices with similar volumes, the treatment amount of the VOCs waste gas in Example 1-1 of the present invention reached 45 times that of Comparative Example 1.

[0107] Comparing the experimental results of Example 1-1 of the present invention and Comparative Example 1, it can be seen that on the premise of achieving roughly the same purification effect, the purification method provided in Example 1-1 of the present invention has a significantly higher treatment amount of VOCs waste gas than the purification method provided in Comparative Example 1.

[0108] The above are only specific embodiments of the present invention, and the scope of the invention cannot be limited thereby. Therefore, the replacement of equivalent components or equivalent changes and modifications made according to the scope of protection of the present invention should still fall within the scope covered by this patent. In addition, the technical features in the present invention can be freely combined and used among technical features, between technical features and technical inventions, and between technical inventions.

Claims

1. A method for purifying VOCs gas by membrane absorption combined with slurry adsorption of porous adsorption material, wherein, The purification method includes: Step (1): After filtering the VOCs waste gas, it is introduced into the outer space or inner space of the fibers in the membrane contactor. At the same time, the porous adsorbent material slurry is introduced into the inner space or outer space of the fibers. Under the pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side, part of the VOCs gas passes through the wall of the hollow fiber membrane module into the inner space or outer space of the fibers, and the target components in the VOCs gas are selectively adsorbed by the porous adsorbent material, obtaining a rich porous adsorbent material slurry. The purified gas is discharged from the outer space or inner space of the fibers out of the membrane contactor. Step (2): The rich porous adsorbent material slurry is introduced into the desorption tower and heated to desorb the VOCs adsorbed in the rich porous adsorbent material slurry and perform combustion treatment on the desorbed VOCs. After desorption is completed, the obtained poor porous adsorbent material slurry is collected and reused.

2. The purification method according to claim 1, wherein The purification method further includes: using a VOCs gas detector to continuously monitor the concentration of VOCs components in the purified gas. If the concentration of VOCs components in the purified gas meets the relevant emission standards, the purified gas is directly discharged. If the concentration of VOCs components in the purified gas does not meet the relevant emission standards, then one or more of the flow rate of the porous adsorbent material slurry, the flow rate of the rich porous adsorbent material slurry, the flow rate of the VOCs waste gas, the pressure and flow rate of the filtered VOCs waste gas, the pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side, and the desorption pressure are dynamically adjusted, and then the VOCs waste gas is continuously purified until the concentration of VOCs components in the purified gas meets the relevant emission standards and then it is discharged.

3. The purification method according to claim 1 or 2, wherein, The purification method further includes: using an alkali solution to absorb the acidic gas obtained from the combustion treatment.

4. The purification method according to claim 1 or 2, wherein, Control the pressure on the VOCs waste gas side to be not lower than the pressure on the porous adsorbent material slurry side, and the pressure difference between the VOCs waste gas side and the porous adsorbent material slurry side is 0 - 10 kPa; Preferably, the residence time of the VOCs waste gas in the membrane contactor is 1 - 20 min, and the residence time of the porous adsorbent material slurry in the membrane contactor is 5 - 60 min.

5. The purification method according to claim 1, wherein, The material of the hollow fiber membrane module includes one or a combination of several of polytetrafluoroethylene, polysulfone, polyethersulfone, and polyethylene.

6. The purification method according to claim 1 or 5, wherein The inner diameter of the hollow fiber membrane module is 0.5 - 10 mm, the wall thickness is 0.01 - 2 mm, the porosity is 40 - 80%, and the pore size distribution is 0.01 - 5 μm.

7. The purification method according to claim 1 or 2, wherein, The porous adsorbent material slurry is a solid-liquid suspension slurry, which contains a porous adsorbent material and a solvent. Based on the total mass of the porous adsorbent material slurry being 100%, the content of the porous adsorbent material is 5 - 50%; Preferably, the porous adsorbent material includes one or a combination of several of metal-organic framework materials, covalent organic framework materials, and molecular sieves; More preferably, the porous adsorbent material includes one or two of ZIF-8 and CALF-20; Still preferably, the solvent includes one or a combination of several of water, alcohol solvents, ketone solvents, and hydrocarbon solvents. Still more preferably, the solvent comprises one or a combination of several of water, N,N-dimethylacetamide, 1,3-dimethylpropyleneurea, and N-methylpyrrolidone.

8. The purification method according to claim 1 or 2, wherein, The VOCs comprise one or a combination of several of alkane, alkene, halogenated hydrocarbon, alcohol, and aldehyde-ketone components; Preferably, the VOCs comprise one or a combination of several of ethane, propane, n-butane, n-pentane, n-hexane, ethylene, propylene, dichloromethane, methanol, and acetone.

9. A membrane absorption combined with slurry adsorption of porous adsorbent VOCs gas purification system for implementing the VOCs gas purification method of membrane absorption combined with slurry adsorption of porous adsorbent as described in any one of claims 1-8, wherein, The system comprises: a membrane contactor, a lean porous adsorbent slurry storage tank, a rich porous adsorbent slurry storage tank, a desorption tower, and a combustion furnace; The membrane contactor comprises a housing and a plurality of hollow fiber membrane modules. The housing comprises a shell and an upper end cover and a lower end cover respectively disposed at the upper and lower ends of the shell. The plurality of hollow fiber membrane modules are disposed in the shell in a manner parallel to the central axis of the shell, and the upper and lower ends of the plurality of hollow fiber membrane modules are respectively communicated with the upper end cover and the lower end cover; the upper end cover and the lower end cover are respectively provided with a first opening and a second opening, and the lower and upper portions of the outer side wall of the shell are respectively provided with a third opening and a fourth opening; The VOCs waste gas enters the third opening through a pipeline successively via a blower, a filter, a pressure reducing valve, and a first flow controller. The lean porous adsorbent slurry storage tank is communicated with the first opening through a pipeline successively via a contactor feed pump and a second flow controller. The second opening is communicated with the inlet of the desorption tower through a pipeline successively via a first back pressure valve, the rich porous adsorbent slurry storage tank, and a desorption tower feed pump. The desorption product outlet of the desorption tower is communicated with the inlet of the combustion furnace through a pipeline successively via a third back pressure valve, a second flow meter, and a water ring vacuum pump. The liquid phase outlet of the desorption tower is communicated with the lean porous adsorbent slurry storage tank through a pipeline via a lean slurry transfer pump. The fourth opening is communicated with a purified gas pipeline, and a second back pressure valve and a first flow meter are successively arranged on the purified gas pipeline starting from the fourth opening side; Or the VOCs waste gas enters the second opening through a pipeline successively via a blower, a filter, a pressure reducing valve, and a first flow controller. The lean porous adsorbent slurry storage tank is communicated with the fourth opening through a pipeline successively via a contactor feed pump and a second flow controller. The third opening is communicated with the inlet of the desorption tower through a pipeline successively via a first back pressure valve, the rich porous adsorbent slurry storage tank, and a desorption tower feed pump. The desorption product outlet of the desorption tower is communicated with the inlet of the combustion furnace through a pipeline successively via a third back pressure valve, a second flow meter, and a water ring vacuum pump. The liquid phase outlet of the desorption tower is communicated with the lean porous adsorbent slurry storage tank through a pipeline via a lean slurry transfer pump. The first opening is communicated with the purified gas pipeline, and a second back pressure valve and a first flow meter are successively arranged on the purified gas pipeline starting from the first opening side.

10. The purification system according to claim 9, wherein, The purification system further comprises an alkali liquor absorption tank, and the outlet of the combustion furnace is communicated with the alkali liquor absorption tank through a pipeline; Preferably, the purification system further comprises a VOCs gas detector, which is arranged on the purified gas pipeline and close to the purified gas outlet; Also preferably, the purification system further includes a computer control system, which is electrically connected to a blower, a pressure reducing valve, a first flow controller, a contactor feed pump, a second flow controller, a first back pressure valve, a desorption tower feed pump, a third back pressure valve, a second flowmeter, a water ring vacuum pump, a lean slurry transfer pump, a second back pressure valve, a first flowmeter, and a VOCs gas detector respectively.

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