System and method for separating gas mixture comprising organic and inorganic compounds

Abstract

Systems and methods for separating a gaseous mixture of an organic gaseous compound and an inorganic gaseous compound are disclosed. The system includes a membrane unit having a membrane element at least partially coated with an organic liquid. The method includes separating a gaseous mixture of an organic gaseous compound and an inorganic gaseous compound using a membrane unit having a membrane element at least partially coated with an organic liquid.

Description

[0001] Cross-reference to related applications

[0002] none. Technical Field

[0003] The present invention generally relates to systems and methods for separating gas mixtures containing organic gaseous compounds and inorganic gaseous compounds. More specifically, the present invention relates to separating gas mixtures containing organic gaseous compounds and inorganic gaseous compounds using a gas membrane unit suitable for such separation. Background Art

[0004] Typically, in a plant for the production of ethylene oxide and ethylene glycol, a recycled gas stream is formed, which contains ethylene (5-30 wt%), carbon dioxide (30-90 wt%), argon (1-10 wt%), methane (1-10 wt%) and water (0.5-5 wt%). This recycled gas stream is usually recycled back to the ethylene oxide reactor. A certain amount of the recycled gas stream needs to be purged to avoid accumulation of argon and ethane in the feed stream of the ethylene oxide reactor. However, the purge rate is proportional to the amount of ethylene (feedstock) that will be lost.

[0005] One solution that has been implemented to address ethylene losses caused by scavenging is to install an ethylene recovery unit (ERU) that removes argon from the recovery gas stream and recycles the ethylene back to the ethylene oxide reactor. But even when an ERU is used, a large amount of scavenging is still required, which results in some ethylene losses. Typically, an ERU is not an effective unit operation to address the ethylene loss problem. In addition, the use of an ERU in an ethylene oxide / ethylene glycol production process is not energy efficient. Summary of the invention

[0006] The inventors disclose herein the use of membrane units to separate gas mixtures containing organic and inorganic compounds in an efficient manner. The present invention relates to the separation of gas mixtures (such as recovered gas from an ethylene oxide / ethylene glycol plant) using membranes that are suitable for performing such separations by soaking the membrane in an organic liquid and then using the pre-soaked membrane to remove carbon dioxide and argon from the recovered gas. In an ethylene oxide / ethylene glycol production process, for example, such separations can improve process efficiency and selectivity of the ethylene to ethylene oxide reaction. According to the present invention, such separations can eliminate or reduce gas removal rates, recover more ethylene and conserve raw materials.

[0007] Embodiments of the present invention include a method for separating a gas mixture containing organic gaseous compounds and inorganic gaseous compounds, wherein the method includes flowing the gas mixture into a membrane unit including a membrane element at least partially coated with an organic liquid, and separating the gas mixture in the membrane unit. The method further includes flowing a first gas stream from the membrane unit, the first gas stream containing a lower concentration of inorganic gaseous compounds than the gas mixture.

[0008] Embodiments of the present invention include a method for separating a gas mixture comprising ethylene, carbon dioxide, methane, and argon. The method includes flowing the gas mixture into a membrane unit comprising a membrane element at least partially coated with propylene oxide, ethylene oxide, methanol, benzene, or a combination thereof, and separating the gas mixture in the membrane unit. The method further includes flowing a first gas stream from the membrane unit, the first gas stream containing a lower concentration of carbon dioxide and argon than the gas mixture.

[0009] Embodiments of the present invention include a method for separating a gas mixture comprising ethylene, carbon dioxide, methane and argon. The method includes flowing the gas mixture into a membrane unit comprising a membrane element, the membrane element comprising a perfluoropolymer and / or cellulose acetate, wherein the membrane element is at least partially coated with propylene oxide, ethylene oxide, methanol, benzene or a combination thereof, and separating the gas mixture in the membrane unit. In addition, the method includes flowing an inert gas as a purge gas into the membrane unit. Further, the method further includes flowing a first gas stream from the membrane unit, the first gas stream containing a lower concentration of carbon dioxide and argon than the gas mixture.

[0010] Embodiments of the present invention include a system for separating a gas mixture comprising organic gaseous compounds and inorganic gaseous compounds. The system includes a membrane unit comprising a membrane element at least partially coated with an organic liquid.

[0011] Embodiments of the present invention include a system for separating a gas mixture comprising organic gaseous compounds and inorganic gaseous compounds. The system comprises: a membrane unit comprising a membrane element comprising a perfluoropolymer and / or cellulose acetate at least partially coated with propylene oxide, ethylene oxide, methanol, benzene, or a combination thereof.

[0012] Included below are definitions of various terms and phrases used throughout this specification.

[0013] The term "about" or "approximately" is defined as close to, as understood by those skilled in the art. In a non-limiting embodiment, the term is defined as within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0014] In the present invention, "X, Y and / or Z" may be interpreted as only X, only Y, only Z, or any combination of two or more of X, Y and Z (e.g., XYZ, XY, XZ, YZ).

[0015] The terms "wt %, "vol %" or "mol %" refer to the weight, volume or mole percentage of a component based on the total weight, total volume or total moles of the material including the component, respectively. In a non-limiting example, 10 mol of a component in 100 mol of a material is 10 mol% of the component.

[0016] The term "substantially" and variations thereof are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

[0017] When used in the claims and / or specification, the terms "inhibit" or "reduce" or "prevent" or "avoid" or any variation of these terms includes any measurable reduction or complete inhibition to achieve a desired result.

[0018] The term "effective" as used in the specification and / or claims means sufficient to achieve a desired, intended, or targeted result.

[0019] The use of the word "a" or "an" when used in conjunction with the terms "comprising," "including," "containing," or "having" in the claims or the specification may mean "one," but it is also consistent with the meaning of "one or more," "at least one," and "one or more than one."

[0020] The terms "comprise" (and any form of comprising, such as "comprising"), "have" (and any form of having, such as "having"), "include" (and any form of including, such as "including"), or "contains" (and any form of containing, such as "containing") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0021] The methods of the present invention may "comprise," "consist essentially of," or "consist of" specific ingredients, components, compositions, etc. disclosed throughout the specification.

[0022] The term "mainly" used in the specification and / or claims means greater than any one of 50 wt%, 50 mol% and 50 vol%. For example, "mainly" can include all values ​​and ranges between 50.1 wt% and 100 wt% and 50.1 mol% and 100 mol%, all values ​​and ranges between 50.1 mol% and 100 mol% and therebetween, or all values ​​and ranges between 50.1 vol% and 100 vol% and therebetween.

[0023] Other objects, features and advantages of the present invention will become clear through the following drawings, specific embodiments and examples. However, it should be understood that although the drawings, specific embodiments and examples indicate specific embodiments of the present invention, they are only provided for illustration and are not meant to be limiting. In addition, it can be expected that changes and modifications within the spirit and scope of the present invention will become clear to those skilled in the art according to this specific embodiment. In other embodiments, features from a specific embodiment can be combined with features from other embodiments. For example, features from an embodiment can be combined with features from any other embodiment. In other embodiments, additional features can be added to the specific embodiments described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] For a more complete understanding, reference is now made to the following description taken in conjunction with the accompanying drawings, wherein:

[0025] Figure 1 A system according to an embodiment of the present invention is shown for separating a gas mixture comprising organic gaseous compounds and inorganic gaseous compounds; and

[0026] Figure 2 A method according to an embodiment of the present invention is shown for separating a gas mixture comprising organic gaseous compounds and inorganic gaseous compounds. DETAILED DESCRIPTION

[0027] According to the present invention, a mixture of organic and inorganic gases can be effectively separated by using a membrane immersed in an organic liquid. For example, in an ethylene oxide / ethylene glycol plant, a recovered gas mixture comprising ethylene, carbon dioxide, methane and argon can be separated by flowing the gas mixture into a membrane unit, the membrane unit comprising: a membrane element comprising a perfluoropolymer and / or cellulose acetate, and the membrane element has been immersed therein and is therefore at least partially coated with propylene oxide, ethylene oxide, methanol, benzene or a combination thereof. In an embodiment of the present invention, coating the membrane element with propylene oxide, ethylene oxide, methanol, benzene or a combination thereof can be implemented by a method other than immersion or a method other than immersion (e.g., spraying or dipping).

[0028] Figure 1 A system 10 is shown for separating a gas mixture comprising organic gaseous compounds and inorganic gaseous compounds, according to an embodiment of the present invention. Figure 2 A method 20 is shown for separating a gas mixture comprising organic gaseous compounds and inorganic gaseous compounds according to an embodiment of the present invention. In an embodiment of the present invention, the method 20 is implemented by the system 10.

[0029] Systems for separating gas mixtures containing organic and inorganic compounds

[0030] According to an embodiment of the present invention, system 10 includes membrane unit 101, which has membrane element 102 arranged therein. According to an embodiment of the present invention, membrane element 102 includes perfluoropolymer or similar glassy polymer material, ceramic or hybrid polymer matrix-ceramic material (perfluoropolymer and / or cellulose acetate). In addition, according to an embodiment of the present invention, membrane element 102 is at least partially coated with organic liquid such as propylene oxide, ethylene oxide, methanol, benzene or its combination. Membrane element 102 can be realized by immersing membrane element 102 in propylene oxide, ethylene oxide, methanol, benzene or its combination with propylene oxide, ethylene oxide, methanol, benzene or its combination. Alternatively, organic liquid can be sprayed or dip-coated on membrane element 102. In one aspect, organic liquid flows through or contacts membrane element 102 for 2-5 hours, or 2.5-3 hours, and then dries or solidifies before separation step is carried out with the membrane element. Optionally, organic liquid is sprayed on membrane element for 20-60 minutes, or 25-35 minutes, and then dries or solidifies before separation step is carried out. In another aspect, the membrane element 102 is dip-coated in the organic liquid for 10-30 minutes, or 15-20 minutes, and then dried or cured before the separation step. It has been found that this contact with the organic liquid forms a coating or boundary of the organic liquid in or on the membrane element. It has been found that this helps to achieve the acceleration and more effective separation described herein.

[0031] In this way, the membrane unit 101 is adapted to receive and separate, for example, a recycled gas 100 (gas mixture) comprising ethylene, carbon dioxide, methane, and argon, thereby forming (1) a first gas stream 104 (recycle gas) comprising ethylene and methane, and (2) a second gas stream 103 (exhaust gas) comprising carbon dioxide and argon. Thus, according to an embodiment of the present invention, the membrane unit 101 is adapted to separate the recycled gas 100 to produce a first gas stream 104 comprising lower concentrations of carbon dioxide and argon (and higher concentrations of ethylene and methane) than the recycled gas 100. Accordingly, the membrane unit 101 is adapted to separate the recycled gas 100 to produce a second gas stream 103 comprising higher concentrations of carbon dioxide and argon (and lower concentrations of ethylene and methane) than the recycled gas 100. In an embodiment of the present invention, the system 10 comprises a compressor unit 105 adapted to flow nitrogen 106 as a purge gas through the membrane unit 101.

[0032] Method for separating a gas mixture containing organic and inorganic compounds

[0033] Method 20 can be implemented, for example, for a gas mixture that is a recycled gas stream from an ethylene oxide / ethylene glycol production plant. According to an embodiment of the present invention, method 20 includes, at box 200, and as implemented using system 10, flowing recycled gas 100 (gas mixture) into membrane unit 101, wherein membrane unit 101 includes a membrane element 102 at least partially coated with an organic liquid (e.g., propylene oxide, ethylene oxide, methanol, benzene, or a combination thereof). According to an embodiment of the present invention, membrane element 102 includes perfluoropolymer and / or cellulose acetate. According to an embodiment of the present invention, coating of membrane element 102 can include soaking membrane element 102 in an organic liquid (e.g., propylene oxide, ethylene oxide, methanol, benzene, or a combination thereof) for 2-5 hours before recycled gas 100 flows into membrane unit 101.

[0034] According to an embodiment of the present invention, the recycled gas 100 comprises ethylene, carbon dioxide, methane and argon. In some ethylene oxide / ethylene glycol production plants to which the present invention is applicable, the recycled gas 100 may comprise 5-30 wt% ethylene, 30-90 wt% carbon dioxide, 1-10 wt% argon, 1-10 wt% methane, and 0.5-5 wt% water.

[0035] According to an embodiment of the present invention, method 20 includes at box 201, making 20-30% of the nitrogen 106 of mass flow rate flow into membrane unit 101 as purge gas. In this way, according to an embodiment of the present invention, the separation at box 200 can be achieved using a combination of purge gas membrane separation, partial pressure difference and pore size filtration based on molecular size. Nitrogen can be used as a purge gas to further promote mass transfer, which produces a partial pressure difference between the feed and permeate (second gas stream 103) side. On the retentate (first gas stream 104) side, ethylene can be recovered and recycled back to the ethylene oxide reactor together with methane (CH4), which serves as a ballast gas for heat transfer control. Steam or nitrogen can also be used as ballast gas.

[0036] According to an embodiment of the present invention, the method 20 further includes separating the recovery gas 100 in the membrane unit 101 by the membrane element 102 at box 202; and flowing out the first gas stream 104 from the membrane unit 101 at box 203. According to an embodiment of the present invention, at box 202, carbon dioxide and argon having a molecular size lower than that of ethylene can permeate the membrane element 102 more than hydrocarbons and ethylene, so ethylene and other hydrocarbons will be retained on the high pressure side (i.e., the retentate side). In an embodiment of the present invention, the operating conditions in the membrane unit 101 include a temperature of 80-200° C., including 80-90° C., 90-100° C., 100-110° C., 110-120° C., 120-130° C., 130-140° C., 140-150° C., 150-160° C., 160-170° C., 170-180° C., 180-190° C., and 190-200° C.; a pressure of 10-50 bar, including 10-15 bar, 15-20 bar, 20-25 bar, 25-30 bar, 30-35 bar, 35-40 bar, 40-45 bar, and 45-50 bar; and a flow rate of 200-30000 kg / h, It includes 200-2000kg / h, 2000-4000kg / h, 4000-6000kg / h, 6000-8000kg / h, 8000-10000kg / h, 10000-12000kg / h, 12000-14000kg / h, 14000-16000kg / h, 16000-18000kg / h, 18000-20000kg / h, 20000-22000kg / h, 22000-24000kg / h, 2400-260000kg / h, 26000-28000kg / h, and 28000-30000kg / h.

[0037] According to an embodiment of the invention, as a result of the separation at box 200, the first gas stream 104 has lower concentrations of inorganic gaseous compounds, carbon dioxide, and argon (and higher concentrations of ethylene and methane) than the recycled gas 100. In an embodiment of the invention, the first gas stream 104 comprises 10-45 wt% ethylene, 20-50 wt% carbon dioxide, 0.5-8 wt% argon, 5-20 wt% methane, and 0.01-3 wt% water.

[0038] At box 204, according to an embodiment of the present invention, method 20 includes flowing out a second gas stream 103 from membrane unit 101. In an embodiment of the present invention, second gas stream 103 contains higher concentrations of carbon dioxide and argon (and lower concentrations of ethylene and methane) than recycled gas 100. In an embodiment of the present invention, second gas stream 103 contains 0.1-4wt% ethylene, 70-98wt% carbon dioxide, 1-20wt% argon, 0.4-8wt% methane, and 0.1-1wt% water. In an embodiment of the present invention, 85-87wt% carbon dioxide and 30-60wt% argon can be removed from recycled gas 100, and 90-93wt% ethylene can be recovered in first gas stream 104.

[0039] According to an embodiment of the present invention, in the absence of soaking, the carbon dioxide removal efficiency is 40%-60%, optionally 42%-58%, optionally 44%-58%, optionally 45%-58%, optionally 48%-58%, and in the case of soaking in feed / PO or EO or benzene or methanol or a combination thereof, the carbon dioxide removal efficiency is 70%-90%, optionally 70%-90%, optionally 72%-90%, optionally 75%-88%, and when combined with soaking and purge gas, the carbon dioxide removal efficiency is 75%-98%, optionally 75%-99%, optionally 78%-99%, optionally 80%-99%, optionally 80%-97%.

[0040] Although referenced Figure 2 The blocks of the present invention describe the embodiments of the present invention, but it should be understood that the operation of the present invention is not limited to Figure 2 The specific blocks and / or specific order of blocks shown. Therefore, embodiments of the present invention may use Figure 2 Different blocks in different orders are used to provide the functionality described herein.

[0041] The systems and methods described herein may also include various devices not shown and known to those skilled in the art of chemical processing. For example, some controllers, pipes, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, etc. may not be shown.

[0042] As part of the disclosure of the present invention, the following specific examples are included. The examples are for illustrative purposes only and are not intended to limit the present invention. Those skilled in the art will readily recognize parameters that can be changed or modified to produce substantially the same results.

[0043] Example

[0044] Bench scale experiments - membrane stability

[0045] Experiments were conducted at a laboratory scale to test the stability of the membrane when exposed to a hydrocarbon stream containing ethylene oxide. As part of the testing, the membrane was soaked for 2-4 hours to measure the increase in separation efficiency.

[0046] The two types of membranes were immersed in propylene oxide, and their respective separation performances before and after the immersion were measured. The types of membranes used in the experiments were: (1) perfluoropolymer, and (2) cellulose acetate.

[0047] The test results are shown in Table 1 below.

[0048] Table 1

[0049]

[0050] As can be seen from the results shown in Table 1, the perfluoropolymer is stable and effective in the target stream to be separated.

[0051] Table 2

[0052]

[0053] As can be seen from the results shown in Table 2, the perfluoropolymer is stable and effective in the target stream to be separated.

[0054] Simulation of membrane separation processes

[0055] The simulations were performed using Aspen Custom Modeler, JMP (DOE) in pilot scale tests, and Aspen v. 9 in the plant scenario example. The results are shown in Tables 3 and 4, respectively.

[0056] Table 3: DOE prediction data - membrane A (perfluoropolymer)

[0057]

[0058] Table 4: Factory Evaluation

[0059]

[0060] Experimental data on the effects of soaking and purge gases on separation performance

[0061] Tests were conducted to determine the effects of soaking the membrane and using a purge gas on separation performance. The feed gas was used to soak the membrane module for 2 hours. Nitrogen was used as the purge gas. The results shown in Tables 5-13 below show that the carbon dioxide removal rates for the embodiments without soaking were Table 5 (55%), Table 8 (51%), Table 11 (52%), while with soaking were Table 6 (85%), Table 9 (80%), Table 12 (78%), and the soaking and purge gas combination were Table 7 (94%), Table 10 (86%), Table 13 (83%).

[0062] Table 5: No soaking feed / PO, PO or EO

[0063] Stream Name Feed Retentate Permeate Mutually Gas Phase Gas Phase Gas Phase Total standard gas phase velocity <![CDATA[Nm 3 / h]]> 57.72 15.89 40.77 Total mass flow kg / h 100 22.59 76.56 temperature ℃ 125 25.73 25.9 pressure Bar(g) 22.01 21.51 0.5 Total molar composition percentage mol% <![CDATA[C2H4]]> 12.75 19.9 4.4 <![CDATA[O2]]> 0.85 0.4 1.3 <![CDATA[CO2]]> 72.86 61.0 86.7 <![CDATA[H2O]]> 2.16 3.4 0.7 <![CDATA[N2]]> 0.83 0.9 0.8 AR 2.14 2.6 1.6 <![CDATA[CH4]]> 7.75 10.8 4.2 <![CDATA[C2H6]]> 0.65 1.0 0.2

[0064] [CO2 removal rate = 55%]

[0065] Table 6: Use in feed / PO, PO or EO soaking (soaking time = 2 hours)

[0066] Stream Name Feed Retentate Permeate Mutually Gas Phase Gas Phase Gas Phase Total standard gas phase velocity <![CDATA[Nm 3 / h]]> 57.72 15.89 40.77 Total mass flow kg / h 100 22.59 76.56 temperature ℃ 125 25.73 25.9 pressure Bar(g) 22.01 21.51 0.5 Total molar composition percentage mol% <![CDATA[C2H4]]> 12.75 36.53 3.81 <![CDATA[O2]]> 0.85 0.48 1.02 <![CDATA[CO2]]> 72.86 36.52 88.93 <![CDATA[H2O]]> 2.16 0 0.45 <![CDATA[N2]]> 0.83 1.6 0.56 AR 2.14 2.86 1.92 <![CDATA[CH4]]> 7.75 20.11 3.14 <![CDATA[C2H6]]> 0.65 1.88 0.18

[0067] [CO2 removal rate = 85%]

[0068] Table 7: Using soaking in feed gas / PO or EO (2 hours) + purge gas (N2) (similar to feed flow rate on tube side)

[0069] Stream Name Feed Retentate Permeate Mutually Gas Phase Gas Phase Gas Phase Total standard gas phase velocity <![CDATA[Nm 3 / h]]> 57.72 15.89 40.77 Total mass flow kg / h 100 22.59 76.56 temperature ℃ 125 25.73 25.9 pressure Bar(g) 22.01 21.51 0.5 Total molar composition percentage mol% <![CDATA[C2H4]]> 12.75 45.73 2.03 <![CDATA[O2]]> 0.85 1.21 0.73 <![CDATA[CO2]]> 72.86 17.78 90.78 <![CDATA[H2O]]> 2.16 7.51 0.42 <![CDATA[N2]]> 0.83 1.61 0.58 AR 2.14 1.65 2.30 <![CDATA[CH4]]> 7.75 22.42 2.98 <![CDATA[C2H6]]> 0.65 2.10 0.18

[0070] [CO2 removal rate = 94%]

[0071] Table 8: Not soaked in benzene

[0072] Stream Name Feed Retentate Permeate Mutually Gas Phase Gas Phase Gas Phase Total standard gas phase velocity <![CDATA[Nm 3 / h]]> 58.14 16.01 41.77 Total mass flow kg / h 101 23.68 78.2 temperature ℃ 127 26.54 27.8 pressure Bar(g) 22.5 21.2 0.7 Total molar composition percentage mol% <![CDATA[C2H4]]> 13.17 37.53 3.95 <![CDATA[O2]]> 0.87 0.51 1.01 <![CDATA[CO2]]> 72.46 80.95 31.3 <![CDATA[H2O]]> 0.77 1.27 0.57 <![CDATA[N2]]> 0.85 1.58 0.57 AR 1.81 4.15 1.3 <![CDATA[CH4]]> 7.81 20.1 3.17 <![CDATA[C2H6]]> 0.68 1.95 0.19

[0073] [CO2 removal rate = 51%, argon removal rate = 45%]

[0074] Table 9: Soaking in benzene

[0075] Stream Name Feed Retentate Permeate Mutually Gas Phase Gas Phase Gas Phase Total standard gas phase velocity <![CDATA[Nm 3 / h]]> 58.14 16.01 41.77 Total mass flow kg / h 101 23.68 78.2 temperature ℃ 127 26.54 27.8 pressure Bar(g) 22.5 21.2 0.7 Total molar composition percentage mol% <![CDATA[C2H4]]> 13.15 37.54 3.91 <![CDATA[O2]]> 0.87 0.51 1.01 <![CDATA[CO2]]> 71.45 50.2 80.24 <![CDATA[H2O]]> 0.75 1.25 0.56 <![CDATA[N2]]> 0.85 1.58 0.57 AR 1.79 3.25 1.25 <![CDATA[CH4]]> 7.81 20.1 3.17 <![CDATA[C2H6]]> 0.64 1.87 0.19

[0076] [CO2 removal rate = 80%, argon removal rate = 50%]

[0077] Table 10: Soaking in benzene + purge gas

[0078] Stream Name Feed Retentate Permeate Mutually Gas Phase Gas Phase Gas Phase Total standard gas phase velocity <![CDATA[Nm 3 / h]]> 58.14 16.01 41.77 Total mass flow kg / h 101 23.68 78.2 temperature ℃ 127 26.54 27.8 pressure Bar(g) 22.5 21.2 0.7 Total molar composition percentage mol% <![CDATA[C2H4]]> 13.15 37.54 3.91 <![CDATA[O2]]> 0.87 0.51 1.01 <![CDATA[CO2]]> 71.55 40.25 95.15 <![CDATA[H2O]]> 0.75 1.25 0.56 <![CDATA[N2]]> 0.85 1.58 0.57 AR 1.81 2.29 1.64 <![CDATA[CH4]]> 7.81 20.1 3.17 <![CDATA[C2H6]]> 0.64 1.87 0.19

[0079] [CO2 removal rate = 86%, argon removal rate = 65%]

[0080] Table 11: No immersion in methanol

[0081] Stream Name Feed Retentate Permeate Mutually Gas Phase Gas Phase Gas Phase Total standard gas phase velocity <![CDATA[Nm 3 / h]]> 58.14 16.01 41.77 Total mass flow kg / h 101 23.68 78.2 temperature ℃ 127 26.54 27.8 pressure Bar(g) 22.5 21.2 0.7 Total molar composition percentage mol% <![CDATA[C2H4]]> 12.75 36.53 3.81 <![CDATA[O2]]> 0.85 0.48 1.02 <![CDATA[CO2]]> 75.46 53.36 22.15 <![CDATA[H2O]]> 2.16 0 0.45 <![CDATA[N2]]> 0.83 1.6 0.56 Ar 2.16 3.275 0.99 <![CDATA[CH4]]> 7.75 20.11 3.14 <![CDATA[C2H6]]> 0.65 1.88 0.18

[0082] [CO2 removal rate = 52%, argon removal rate = 44%]

[0083] Table 12: Soaking in methanol

[0084] Stream Name Feed Retentate Permeate Mutually Gas Phase Gas Phase Gas Phase Total standard gas phase velocity <![CDATA[Nm 3 / h]]> 58.14 16.01 41.77 Total mass flow kg / h 101 23.68 78.2 temperature ℃ 127 26.54 27.8 pressure Bar(g) 22.5 21.2 0.7 Total molar composition percentage mol% <![CDATA[C2H4]]> 13.15 37.54 3.91 <![CDATA[O2]]> 0.87 0.51 1.01 <![CDATA[CO2]]> 73.46 49.15 67.05 <![CDATA[H2O]]> 0.75 1.25 0.56 <![CDATA[N2]]> 0.85 1.58 0.57 Ar 1.79 3.25 1.25 <![CDATA[CH4]]> 7.81 20.1 3.17 <![CDATA[C2H6]]> 0.64 1.87 0.19

[0085] [CO2 removal rate = 78%, argon removal rate = 52%]

[0086] Table 13: Soaking in methanol + purge gas

[0087] Stream Name Feed Retentate Permeate Mutually Gas Phase Gas Phase Gas Phase Total standard gas phase velocity <![CDATA[Nm 3 / h]]> 58.14 16.01 41.77 Total mass flow kg / h 101 23.68 78.2 temperature ℃ 127 26.54 27.8 pressure Bar(g) 22.5 21.2 0.7 Total molar composition percentage mol% <![CDATA[C2H4]]> 12.75 36.53 3.81 <![CDATA[O2]]> 0.85 0.48 1.02 <![CDATA[CO2]]> 78.16 23.17 43.15 <![CDATA[H2O]]> 2.16 0 0.45 <![CDATA[N2]]> 0.83 1.6 0.56 Ar 2.21 4.65 3.79 <![CDATA[CH4]]> 7.75 20.11 3.14 <![CDATA[C2H6]]> 0.65 1.88 0.18

[0088] [CO2 removal rate = 83%, argon removal rate = 68%]

[0089] In the context of the present invention, at least the following 20 embodiments are disclosed. Embodiment 1 is a method for separating a gas mixture containing organic gaseous compounds and inorganic gaseous compounds. The method includes flowing the gas mixture into a membrane unit, which includes a membrane element at least partially coated with an organic liquid. The method further includes separating the gas mixture in the membrane unit. The method further includes flowing out a first gas stream from the membrane unit, the first gas stream containing inorganic gaseous compounds at a lower concentration than the gas mixture. Embodiment 2 is a method according to embodiment 1, wherein the gas mixture contains ethylene, carbon dioxide, methane and argon, and the first gas stream contains carbon dioxide and argon at a lower concentration than the gas mixture. Embodiment 3 is a method according to embodiment 2, wherein 90-93% of the ethylene in the gas mixture is recovered. Embodiment 4 is a method according to embodiment 2, wherein 85-87% of CO2 and 30-60% of Ar are removed from the gas mixture. Embodiment 5 is a method according to embodiment 2, wherein the gas mixture comprises 5-30 wt% ethylene, 30-90 wt% carbon dioxide, 1-10 wt% argon, 1-10 wt% methane, and 0.5-5 wt% water. Embodiment 6 is a method according to embodiment 2, wherein the first gas stream comprises 10-45 wt% ethylene, 20-50 wt% carbon dioxide, 0.5-8 wt% argon, 5-20 wt% methane, and 0.01-3 wt% water. Embodiment 7 is a method according to embodiment 2, wherein a second gas stream flows out of the membrane unit, the second gas stream containing 0.1-4 wt% ethylene, 70-98 wt% carbon dioxide, 1-20 wt% argon, 0.4-8 wt% methane, and 0.1-1 wt% water. Embodiment 8 is a method according to embodiment 1, wherein the membrane element is at least partially coated with propylene oxide, ethylene oxide, methanol, benzene or a combination thereof. Embodiment 9 is a method according to embodiment 8, wherein the method further comprises soaking the membrane in propylene oxide, ethylene oxide, methanol, benzene or a combination thereof for 2-5 hours before the gas mixture flows into the membrane unit. Embodiment 10 is a method according to embodiment 1, wherein the membrane unit comprises a membrane element comprising a perfluoropolymer and / or cellulose acetate. Embodiment 11 is a method according to embodiment 1, wherein the gas mixture comprises a recycled gas stream from an ethylene oxide-diol production plant. Embodiment 12 is a method according to embodiment 1, further comprising flowing 20-30% of the mass flow rate of nitrogen into the membrane unit as a purge gas. Embodiment 13 is a method according to embodiment 1, further comprising flowing 20-30% of the mass flow rate of nitrogen into the membrane unit as a purge gas.

[0090] Embodiment 14 is a system for separating a gas mixture containing organic gaseous compounds and inorganic gaseous compounds. The system comprises a membrane unit, which comprises a membrane element at least partially coated with an organic liquid. Embodiment 15 is a system according to embodiment 14, wherein the membrane element comprises a perfluoropolymer and / or cellulose acetate. Embodiment 16 is a system according to embodiment 14, wherein the membrane element is at least partially coated with propylene oxide, ethylene oxide, methanol, benzene or a combination thereof. Embodiment 17 is a system according to embodiment 14, wherein the gas mixture comprises ethylene, carbon dioxide, methane and argon. Embodiment 18 is a system according to embodiment 17, wherein the membrane unit is suitable for separating a gas mixture to produce a first gas stream, the first gas stream comprising a lower concentration of carbon dioxide and argon than the gas mixture. Embodiment 19 is a system according to embodiment 18, wherein the membrane unit is suitable for separating a gas mixture to produce a second gas stream, the second gas stream comprising a higher concentration of carbon dioxide and argon than the gas mixture. Embodiment 20 is a system according to embodiment 14, further comprising a compressor for passing a purge gas through the membrane unit.

[0091] All embodiments described above and herein can be combined in any way, unless explicitly excluded otherwise.

[0092] Although the embodiments and advantages thereof of the present application have been described in detail, it should be understood that different changes, substitutions and modifications can be made here without departing from the subject matter and scope of the embodiments defined by the appended claims. In addition, the scope of the present application is not intended to be limited to the specific embodiments of the methods, machines, manufactures, material compositions, devices, methods and steps described in the specification. As those skilled in the art will readily understand from the above disclosure, methods, machines, manufactures, material compositions, devices, methods or steps that currently exist or are developed later can be utilized to perform functions substantially the same as the corresponding embodiments described herein or to achieve substantially the same results. Therefore, the appended claims are intended to include such methods, machines, manufactures, material compositions, devices, methods or steps within their scope.

Claims

1. A method for separating a gas mixture (100) comprising ethylene, carbon dioxide, methane and argon, the method comprising: allowing the gas mixture (100) to flow into a membrane unit (101) comprising a membrane element (102) at least partially coated with an organic liquid; separating the gas mixture (100) in the membrane unit (101); and A first gas stream (104) flows out of the membrane unit (101), the first gas stream (104) comprising lower concentrations of carbon dioxide and argon than the gas mixture (100).

2. The method according to claim 1, wherein the operating temperature of the membrane unit (101) is 80°C-200°C; wherein the operating pressure of the membrane unit (101) is 10 bar-50 bar; wherein the operating flow rate of the membrane unit (101) is 200-30000 kg / h.

3. The method according to claim 1, wherein 90-93% of the ethylene in the gas mixture (100) is recovered.

4. The method according to claim 1, wherein 85-87% of CO2 and 30-60% of Ar are removed from the gas mixture (100).

5. The method according to claim 1, wherein the gas mixture (100) comprises 5-30 wt% of ethylene, 30-90 wt% of carbon dioxide, 1-10 wt% of argon, 1-10 wt% of methane, and 0.5-5 wt% of water.

6. The method according to claim 1, wherein the first gas stream (104) contains 10-45wt% of ethylene, 20-50wt% of carbon dioxide, 0.5-8wt% of argon, 5-20wt% of methane, and 0.01-3wt% of water; wherein a second gas stream (103) flows out of the membrane unit (101), and the second gas stream (103) contains 0.1-4wt% of ethylene, 70-98wt% of carbon dioxide, 1-20wt% of argon, 0.4-8wt% of methane, and 0.1-1wt% of water.

7. The method according to claim 1, wherein the organic liquid is selected from propylene oxide, ethylene oxide, methanol, benzene or a combination thereof.

8. The method of claim 1, wherein the membrane element (102) is at least partially coated with propylene oxide, ethylene oxide, methanol, benzene, or a combination thereof.

9. The method according to any one of the preceding claims, wherein the method further comprises: Before the gas mixture (100) flows into the membrane unit (101), the membrane is soaked in propylene oxide, ethylene oxide, methanol, benzene or a combination thereof for 2-5 hours.

10. The method according to claim 1, wherein the membrane unit (101) comprises: a membrane element (102) comprising a perfluoropolymer and / or cellulose acetate.

11. The method according to claim 1, further comprising: 20% to 30% of the mass flow of nitrogen is allowed to flow into the membrane unit (101) as a purge gas.

12. A system (10) for separating a gas mixture (100) comprising ethylene, carbon dioxide, methane and argon, the system comprising: A membrane unit (101) comprises a membrane element (102) at least partially coated with an organic liquid.

13. The system of claim 13, wherein the membrane element (102) comprises perfluoropolymer and / or cellulose acetate.

14. The system of claim 13, wherein the membrane element (102) is at least partially coated with propylene oxide, ethylene oxide, methanol, benzene, or a combination thereof.

15. The system of claim 13, further comprising a compressor for flowing a sweep gas through the membrane unit.

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