WO2016027713A1 - Separation device and regeneration method - Google Patents

Abstract

This separation device 10 is provided with: a supply path 20 for supplying a gas to be processed; a membrane separation part 40 that is provided with a zeolite membrane 45; a permeated gas recovery path 60 for recovering a permeated gas that has permeated through the zeolite membrane 45; and a non-permeated gas recovery path 80 for recovering a non-permeated gas that has not permeated through the zeolite membrane 45. This separation device 10 is provided with a regeneration path 100 which has a regeneration function of regenerating the zeolite membrane, which has been used for separation, on site and performs a regeneration process. The zeolite membrane 45 selectively allows the permeation of carbon dioxide. Meanwhile, the gas to be processed contains a hydrocarbon-based combustible gas and carbon dioxide. The zeolite membrane 45 is regenerated in the regeneration path 100 by being supplied with a regeneration gas that contains heated air.

Description

Separation apparatus and regeneration method

The present invention relates to a separation apparatus and a regeneration method.

Conventionally, it is known to use a separation membrane in order to selectively separate a predetermined component from a composition containing a plurality of components (see Non-Patent Document 1 and Patent Documents 1 to 4). For example, as described in Non-Patent Document 1, as a method for purifying natural gas, a method using a separation membrane whose main component is an organic substance that selectively permeates carbon dioxide over methane is known. It has been. Further, for example, Patent Document 1 proposes a DDR type zeolite membrane capable of separating one or more specific gas components from a mixed gas containing two or more specific gas components such as natural gas. Yes. Patent Document 2 proposes concentrating methane gas by separating and removing carbon dioxide gas from a digested gas containing methane generated from sewage sludge using a DDR type zeolite membrane.

By the way, a separation membrane such as a ceramic filter gradually accumulates fouling substances with use, and the separation performance deteriorates. Therefore, a cleaning process is performed at a predetermined time in order to recover the separation performance. As a cleaning method, a method of attaching a ceramic filter to a cleaning liquid, a method of flowing a cleaning gas or liquid into the ceramic filter, a so-called back cleaning method, and the like are known. In Patent Document 3, as a cleaning method capable of shortening the work time required for cleaning the ceramic filter, by supplying a cleaning medium to the primary side space of the ceramic filter, the secondary side space is decompressed. It has been proposed to pass a cleaning medium through a ceramic filter. Patent Document 4 proposes heating the zeolite membrane at a predetermined temperature in an atmospheric furnace as a simple method for regenerating the zeolite membrane after being exposed to water.

JP 2004-105942 A Japanese Patent No. 4803990 International Publication No. 2012/147534 International Publication No. 2014/069630

However, in Non-Patent Document 1 and Patent Documents 1 and 2, the regeneration of the separation membrane has not been studied. Further, in Patent Document 3, a method for recovering the separation performance of the separation membrane used for separation of the mixture of water and isopropyl alcohol by the pervaporation method has been studied, but regarding the regeneration of the separation membrane used for gas separation, No specific study was made. In Patent Document 4, the regeneration of the zeolite membrane used for gas separation is studied, but an air furnace for heating the zeolite membrane is separately required, and the zeolite membrane needs to be moved to the air furnace. In particular, when the number of membranes increases to several thousand, etc., there is a problem that an appropriate size of an atmospheric furnace is required, and the man-hour for transferring the zeolite membrane to the atmospheric furnace increases, which is inefficient.

The present invention has been made to solve such a problem, and a main object of the present invention is to provide a separation apparatus and a regeneration method capable of better regenerating a separation membrane used for gas separation.

In order to achieve the main purpose described above, the present inventors have intensively studied. Then, a gas to be treated containing hydrocarbon combustible gas and carbon dioxide is separated using a zeolite membrane that selectively permeates carbon dioxide, and a regeneration gas containing heated air is used to regenerate the zeolite membrane used for the separation. It has been found that regeneration of the zeolite membrane as the separation membrane can be performed more satisfactorily by using. Thus, the present invention has been completed.

That is, the separation device of the present invention is
A membrane separation unit comprising a zeolite membrane that selectively permeates carbon dioxide;
A gas to be treated containing hydrocarbon-based combustible gas and carbon dioxide is supplied to the membrane separation unit, and a permeate gas that has permeated the zeolite membrane and a non-permeate gas that has not permeated the zeolite membrane are separated and recovered. A separation path to
A regeneration path for regenerating the zeolite membrane by supplying a regeneration gas containing heated air to the membrane separation unit;
It is equipped with.

The reproduction method of the present invention includes:
A membrane separation part equipped with a zeolite membrane that selectively permeates carbon dioxide, and a permeate gas that supplies a gas to be treated containing hydrocarbon combustible gas and carbon dioxide to the membrane separation part and permeates the zeolite membrane. And a separation path for separating and recovering the non-permeate gas that has not permeated the zeolite membrane, and a regeneration method for regenerating the zeolite membrane in a separation device comprising:
A regeneration step of regenerating the zeolite membrane by supplying a regeneration gas containing heated air to the membrane separation unit;
Is included.

In the separation apparatus and the regeneration method of the present invention, the regeneration of the separation membrane used for gas separation can be performed better. The reason why such an effect can be obtained is assumed as follows. That is, since the separation membrane used for gas separation is a zeolite membrane, it has higher heat resistance than an organic membrane and is suitable for regeneration using a regeneration gas containing heated air. In addition, although a separation membrane used for gas separation does not like cleaning (regeneration) using a liquid, in the present invention, regeneration is performed using a regeneration gas, which is suitable for regeneration of a separation membrane used for gas separation. . In addition, since the gas to be treated contains hydrocarbon combustible gas and carbon dioxide, the fouling substance is oxidized with a regeneration gas containing heated air and discharged to the outside mainly as carbon dioxide or water vapor. The ring substance and the substances resulting from the ring substance hardly remain on the separation membrane. In addition, since the separation device includes a separation path and a regeneration path, the separation device can perform separation processing and regeneration processing.

FIG. 3 is an explanatory diagram showing an outline of the configuration of the separation device 10. FIG. 3 is an explanatory diagram showing an outline of the configuration of a membrane filter 41. FIG. 3 is an explanatory diagram showing a gas flow at the time of membrane separation in the separation apparatus 10. FIG. 3 is an explanatory diagram showing a gas flow during purging in the separation device 10. FIG. 3 is an explanatory diagram showing a gas flow during regeneration in the separation apparatus 10. Explanatory drawing which shows the flow of the gas at the time of the reproduction | regeneration in the separation apparatus 210. FIG. FIG. 3 is an explanatory diagram showing an outline of the configuration of a separation device 410. FIG. 3 is an explanatory diagram showing an outline of the configuration of a membrane filter 46.

Next, an embodiment for carrying out the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an outline of the configuration of a separation apparatus 10 according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing an outline of the configuration of the membrane filter 41. FIG. 3 is an explanatory diagram showing the gas flow during membrane separation in the separation apparatus 10. FIG. 4 is an explanatory diagram showing the gas flow during purging in the separation apparatus 10. FIG. 5 is an explanatory diagram showing the gas flow during regeneration in the separation apparatus 10.

(Separator)
The separation apparatus 10 includes a supply path 20 for supplying a gas to be processed, a membrane separation unit 40 including a zeolite membrane 45, a permeate gas recovery path 60 for recovering a permeate gas that has permeated the zeolite membrane 45, and a zeolite membrane 45. And a non-permeate gas recovery path 80 for recovering the non-permeate gas that has not permeated. Further, the separation apparatus 10 has a regeneration function for regenerating the zeolite membrane used for separation on the spot, and includes a regeneration path 100 for performing a regeneration process, and a purge path 120 for purging the membrane separation unit 40 before and after the regeneration. And.

The supply path 20 includes a pre-processing unit 22 that pre-processes the raw gas supplied from the outside to obtain a processing target gas, and a heat exchanger that heats the processing target gas to a temperature suitable for membrane separation in the membrane separation unit 40. 24. The supply path 20 includes valves 21 and 23 that adjust the flow of gas flowing through the supply path 20. The gas to be treated includes hydrocarbon combustible gas (hereinafter also simply referred to as combustible gas) and carbon dioxide (hereinafter also referred to as carbon dioxide gas). Examples of the flammable gas include saturated hydrocarbons such as methane, ethane, propane, and butane, unsaturated hydrocarbons such as ethylene, propylene, and butylene, and aromatic hydrocarbons such as benzene, toluene, and xylene. Of these, methane, ethane, propane, ethylene, propylene and the like are preferable. This is because when the number of carbon atoms in the hydrocarbon is 6 or more, it is difficult to be a gas body at normal temperature, and hydrocarbons having 5 or less carbon atoms are preferable. The concentration of the combustible gas in the gas to be treated can be, for example, in the range of 20% by volume to 99% by volume. Further, the concentration of carbon dioxide in the gas to be treated can be set in a range of 1% by volume to 80% by volume, for example. The pretreatment unit 22 is configured to perform a process of mainly reducing liquid hydrocarbons having 6 or more carbon atoms in the hydrocarbons contained in the raw gas. The heat exchanger 24 is provided with a combustion gas passage 38 through which a high-temperature combustion gas combusted by mixing air and fuel in the combustion furnace 30 flows. In the heat exchanger 24, the processing target gas is heated to a temperature suitable for membrane separation by heat exchange between the high-temperature combustion gas flowing through the combustion gas path 38 and the processing target gas flowing through the supply path 20. Connected to the combustion furnace 30 are an air supply fan 32 for introducing outside air, and a combustible gas supply path 36 that is connected to a non-permeate gas recovery tank 90 described later and includes a valve 31 and a fuel gas fan 34. A non-permeate gas containing a hydrocarbon-based combustible gas is used as the fuel. The non-permeating gas used as the fuel preferably contains 50% by volume or more of hydrocarbon-based combustible gas, more preferably 85% by volume or more (the same applies hereinafter). The temperature (separation temperature) suitable for membrane separation is preferably 0 ° C. or higher and 150 ° C. or lower, and more preferably 20 ° C. or higher and 60 ° C. or lower. Membrane separation is performed by adsorption of gas to the membrane and diffusion in the pores of the membrane. Adsorption is preferably at a low temperature, and diffusion is preferably at a high temperature. Therefore, there is an optimum temperature for membrane separation, and at such temperature, the efficiency of membrane separation is good. The separation temperature may be the temperature of the gas to be treated immediately after being heated by the heat exchanger 24, or may be a temperature measured by a temperature sensor (not shown) provided in the membrane separation unit 40. The supply flow rate of the gas to be processed to the membrane separation unit 40 is preferably adjusted so that the gas flow rate on the membrane surface is 0.5 m / s or more and 5 m / s or less. This is because when the flow rate is slow, gas mixing becomes poor and concentration polarization where non-permeate gas stays on the membrane surface may occur, resulting in poor separation performance. This is because it may become large.

The membrane separation unit 40 includes a membrane filter 41 on which a zeolite membrane 45 (see FIG. 2) that selectively transmits carbon dioxide is formed, and membrane filters 41B to 41D configured in the same manner as the membrane filter 41. As shown in FIG. 2, the membrane filter 41 is provided with a porous substrate 44 as a substrate for forming a plurality of cells 42 that serve as flow paths for the gas to be processed, and an inner surface of the porous substrate 44. And a zeolite membrane 45 having a function of separating the target gas. Thus, by forming the zeolite membrane 45 on the surface of the porous base material 44, even if the zeolite membrane 45 is a thin film, it is supported by the porous base material 44 and maintains its shape to prevent breakage and the like. Can do. In this membrane filter 41, among the gas to be processed that has entered the cell 42 from the inlet side, a permeated gas (for example, carbon dioxide) having a molecular size that can permeate the zeolite membrane 45 passes through the zeolite membrane 45 and the porous substrate 44. The light passes through and is sent out from the side surface of the membrane filter 41. On the other hand, a non-permeating gas (for example, a hydrocarbon-based combustible gas) that cannot permeate the zeolite membrane 45 flows along the flow path of the cell 42 and is sent out from the outlet side of the cell 42. The membrane filters 41, 41B to 41D are arranged vertically so that the longitudinal direction of the cell 42 coincides with the vertical direction, that is, the gas flows in the vertical direction. Note that the vertical direction does not need to exactly coincide with the vertical line, and may be inclined within a range of 10 ° (preferably within 5 °, more preferably within 3 °) with respect to the vertical line, for example. . The membrane filters 41, 41B to 41D are connected in series via the connection paths 50B, 50C, 50D. Specifically, the outlet side of the membrane filters 41, 41B, 41C and the inlet side of the membrane filters 41B, 41C, 41D are connected via connection paths 50B, 50C, 50D, respectively. The connection path 50C includes a valve 51 that adjusts the flow of gas flowing through the connection path 50C.

The porous substrate 44 may have a monolithic structure including a plurality of cells 42 or may have a tubular structure including a single cell. Although the external shape is not particularly limited, it can be a cylindrical shape, an elliptical column shape, a quadrangular column shape, a hexagonal column shape, or the like. Alternatively, the porous substrate 44 may be a tube having a polygonal cross section. The porous substrate 44 may have a multilayer structure of two or more layers in which fine grain portions 44b having small pore diameters are formed on the surface of coarse grain portions 44a having large pore diameters. The pore diameter of the coarse particle portion 44a can be set to, for example, about 0.1 μm to several hundred μm. The pore diameter of the fine-grained portion 44b only needs to be smaller than the pore diameter of the coarse-grained portion 44a. For example, the pore diameter can be about 0.001 to 1 μm. In this way, the permeation resistance of the porous substrate 44 can be reduced. Examples of the material constituting the porous substrate 44 include alumina (α-alumina, γ-alumina, anodized alumina, etc.), ceramics such as zirconia, metals such as stainless steel, and the like. From the viewpoint of easiness, alumina is preferable. Alumina is preferably molded and sintered using alumina particles having an average particle size of 0.001 to 30 μm as a raw material.

The zeolite membrane 45 selectively permeates (separates) carbon dioxide from the gas to be treated including hydrocarbon combustible gas and carbon dioxide. Here, “selectively separating carbon dioxide” not only separates and removes carbon dioxide having a purity of 100% from the gas to be treated, but also has a carbon dioxide content compared to the composition of the gas to be treated. It also includes separating out the raised gas. For example, carbon dioxide having a purity of 90% or more and carbon dioxide having a purity of 95% or more may be separated and extracted.

The type of the zeolite membrane 45 is not particularly limited as long as it selectively transmits carbon dioxide. Depending on the crystal structure of zeolite, LTA (A type), MFI (ZSM-5, silicalite), MOR (mordenite), AFI (SSZ-24), FER (ferrierite), FAU (X type, T type) There are many types such as DDR (deca-dodecacil-3R). The zeolite is an oxygen 8-membered ring, and the composition (molar ratio) preferably satisfies SiO ₂ / Al ₂ O ₃ ≧ 5, and DDR is more preferable. DDR is a crystal whose main component is silica, and its pores are formed by a polyhedron including an oxygen 8-membered ring, and the pore diameter of the oxygen 8-membered ring is 4.4 × 3.6 mm. Are known. The DDR type zeolite membrane is mainly composed of silica, and has a high SiO ₂ / Al ₂ O ₃ molar ratio (hereinafter also referred to as silica-alumina ratio) (eg, 200 or more, preferably infinite), and therefore has excellent acid resistance. Yes. Regarding acid resistance, for example, A-type zeolite has a silica-alumina ratio of about 2, and the content of alumina is high, so that the acid resistance is lower than that of DDR-type zeolite. The T-type zeolite has a slightly higher silica content than the A-type, but has a lower acid resistance than the DDR-type zeolite because the silica-alumina ratio is as low as 6-8. MOR type zeolite has a higher silica content, but its acid resistance is lower than DDR type zeolite because the silica / alumina ratio is about 40 or less. Thus, since the DDR type zeolite membrane has high acid resistance, it is also suitable for treatment of acidic gas. In addition, the DDR type zeolite membrane has high water resistance, unlike the A type zeolite membrane that selectively permeates water due to its strong hydrophilicity. For this reason, it is also resistant to water vapor and the like. Further, since the DDR type zeolite membrane has a high silica-alumina ratio, the organic solvent resistance, alkali resistance, and heat resistance are high. The manufacturing method of the DDR type zeolite membrane is not particularly limited as long as a dense DDR type zeolite membrane can be formed. For example, the content ratio of 1-adamantanamine and silica (1-adamantanamine / SiO ₂ ) in a molar ratio of 0.03 to 0.02 is used as in the method for producing a DDR type zeolite membrane described in JP-A No. 2003-159518. 0.4, the content ratio of water and silica (water / SiO ₂ ) in a molar ratio of 20 to 500, and the content ratio of ethylenediamine and 1-adamantanamine (ethylenediamine / 1-adamantanamine) in a molar ratio of 5 to It is good also as what was formed by hydrothermal synthesis using the raw material solution which is 32, and the DDR type | mold zeolite powder used as a seed crystal.

The thickness of the zeolite membrane 45 is preferably 0.01 μm or more and 10 μm or less, and more preferably 1 μm or more and 3 μm or less. When the thickness is 0.01 μm or more, the decrease in selectivity is suppressed and the mechanical strength is improved. On the other hand, when the thickness is 10 μm or less, a decrease in CO ₂ permeability can be suppressed. The thickness can be measured, for example, with a scanning electron microscope.

In the membrane separation unit 40, the zeolite membrane 45 and the porous base material 44 provide a supply side space in which the gas to be treated flows and a permeation side space in which the permeated gas separated from the membrane filter 41 to the permeate gas recovery path 60 flows. It is separated. In the membrane separation part 40, it is necessary to provide a differential pressure between the supply path 20 and the permeate gas recovery path 60 (permeation side space), and at least 0.1 MPa or more is required. If the supply path 20 is a gas having pressure, the permeate gas recovery path may be equal to or lower than the pressure of the supply path 20. When the supply path 20 is at atmospheric pressure, the permeate gas recovery path 60 is depressurized to transmit permeate gas (carbon dioxide) from the cell 42 to the permeate gas recovery path 60 side through the zeolite membrane 45 and send it out. At this time, the degree of vacuum (secondary pressure) in the transmission side space is preferably 1.3 kPa (10 Torr) or more and 13 kPa (100 Torr) or less. The concentration of the hydrocarbon-based combustible gas contained in the separation gas is preferably 10% or less, more preferably 5% or less, and further preferably 1% or less. On the other hand, the non-permeate gas that has not permeated the zeolite membrane 45 in the membrane separation unit 40 is sent to the non-permeate gas recovery path 80.

The permeated gas recovery path 60 includes an individual recovery path 62, 62B-62D connected to the permeate side of the membrane filters 41, 41B-41D, and a concentrated recovery path through which permeated gas flowing through the individual recovery paths 62, 62B-62D flows. 64. The concentrated recovery path 64 includes a valve 61 that adjusts the flow of gas that flows through the permeate gas recovery path 60 and a permeate gas recovery tank 70 that recovers the permeate gas that flows through the permeate gas recovery path 60. An extraction path 72 for extracting the permeated gas is connected to the permeated gas recovery tank 70, and the extraction path 72 includes a valve 71. The valve 71 is opened when the permeate gas is recovered from the permeate gas recovery tank 70, and is closed otherwise.

The non-permeate gas recovery path 80 is connected to the membrane filter 41D, and includes a valve 81 that adjusts the flow of gas flowing through the non-permeate gas recovery path 80, a purification unit 82 that performs a purification process of the non-permeate gas, A non-permeate gas recovery tank 90 that recovers the non-permeate gas flowing through the permeate gas recovery path 80. The purification unit 82 purifies the non-permeating gas by removing residual CO ₂ or removing residual moisture, mercury, or the like by, for example, a wet absorption method or an adsorption method. A non-permeate gas recovery tank 90 is connected to a take-out path 92 for taking out the non-permeate gas, and the take-out path 92 includes a valve 91. The valve 91 is opened when the non-permeate gas is recovered from the non-permeate gas recovery tank 90, and is closed otherwise.

The regeneration path 100 includes a concentrated supply path 102 for supplying regeneration gas, and individual supply paths 104, 104B to 104D branched from the concentrated supply path 102 and connected to the lower portions of the membrane filters 41, 41B to 41D. Yes. Further, the individual discharge paths 106, 106B to 106D connected to the upper parts of the membrane filters 41, 41B to 41D, the concentrated discharge path 108B into which the regeneration gas flowing through the individual discharge paths 106 and 106B flows, and the individual discharge paths 106C, And a concentrated discharge path 108D through which the regeneration gas flowing through 106D flows. A part of the concentrated supply path 102 is in common with a part of the supply path 20, and a regenerative air fan (corresponding to the air introduction path of the present invention) 110 that introduces air and a gas flow that flows through the regeneration path 100. And a heat exchanger 24 that heats the air to generate a regeneration gas having a temperature suitable for regeneration of the zeolite membrane 45. The temperature suitable for regeneration of the zeolite membrane 45 (regeneration temperature) is preferably 150 ° C. or higher and 500 ° C. or lower, more preferably 200 ° C. or higher and 450 ° C. or lower, and further preferably 380 ° C. or higher and 400 ° C. or lower. The regeneration temperature may be the temperature of the regeneration gas immediately after being heated by the heat exchanger 24, or may be a temperature measured by a temperature sensor (not shown) provided in the membrane separation unit 40. The supply flow rate of the regeneration gas to the membrane separation unit 40 is preferably adjusted so that the flow rate on the membrane surface is 0.1 m / s or more and 1 m / s or less. The individual supply path 104 is common with a part of the supply path 20, the individual supply paths 104B and 104C are common with a part of the connection path 50C, and the individual supply path 104D is a part of the non-permeate gas recovery path 80. And in common. The individual supply paths 104, 104B to 104D include valves 105B to 105D, respectively. The individual discharge paths 106 and 106B are common to a part of the connection path 50B, and the individual discharge paths 106C and 106D are common to a part of the connection path 50D. The concentrated discharge paths 108B and 108D are provided with valves 107B and 107D, respectively.

The purge path 120 includes a concentrated supply path 122 for supplying purge gas, individual supply paths 104, 104B to 104D branched from the concentrated supply path 122, individual discharge paths 106, 106B to 106D, concentrated discharge paths 108B and 108C, It has. Of these, the parts other than the concentrated supply path 122 are the same as those in the regeneration path 100, and thus the description thereof is omitted. The central supply path 122 is connected to the permeate gas recovery tank 70, a purge fan 124 that sends permeate gas as purge gas from the permeate gas recovery tank 70 to the membrane separation unit 40, and a valve 121 that adjusts the gas flow in the purge path 120. , 103. The concentrated supply path 122 uses a part of the concentrated supply path 102 in the regeneration path 100. The permeated gas as the purge gas preferably contains 90% by volume or more of carbon dioxide, more preferably 95% by volume or more.

Next, an embodiment of the reproduction method of the present invention will be described. This regeneration method is performed after the separation step, and includes a first purge step, a regeneration step, and a second purge step. Below, the case where the separation apparatus 10 is used is demonstrated.

(Separation process)
In the separation step, the gas to be processed is separated using a path (separation path 12) indicated by a thick arrow in FIG. At this time, the high-temperature combustion gas used in the heat exchanger 24 is supplied using the path indicated by the thin line arrow in FIG. Specifically, during membrane separation, the valves 21, 23, 31, 51, 81, 61 are opened, and the opening and closing of the valves is controlled by a control unit (not shown) connected to each valve so as to close the other valves. Further, the operation of the fan is controlled by a control unit (not shown) connected to each fan so that the air supply fan 32 and the fuel gas fan 34 are operated and the other fans are not operated. In the separation device 10, the raw gas supplied from the outside flows through the supply path 20, becomes a gas to be processed by membrane treatment in the pretreatment unit 22 in the middle of the supply path 20, and further performs heat exchange in the heat exchanger 24. The temperature is suitable for membrane separation by (heating), and is supplied to the membrane separation unit 40. In the membrane separation unit 40, the gas to be processed flows into the membrane filter 41 from below and flows upward, passes through the connection path 50B, flows into the membrane filter 41B from above, flows downward, passes through the connection path 50C, and passes through the membrane filter 41C. From the lower part and flows upward, passes through the connection path 50D, flows into the membrane filter 41D from the upper part and flows downward, and is sent to the non-permeate gas recovery path 80 as a non-permeate gas containing a large amount of hydrocarbon-based combustible gas. Is done. The sent non-permeate gas is purified by the purification processing unit 82 in the non-permeate gas recovery path 80 and stored in the non-permeate gas recovery tank 90. On the other hand, part of the gas to be treated passes through the zeolite membrane 45 and is sent to the permeate gas recovery path 60 as a permeate gas containing a large amount of carbon dioxide. The transmitted permeate gas flows through the central recovery path 64 through the individual recovery paths 62 and 62B to 62D in the permeate gas recovery path 60, and is stored in the permeate gas recovery tank. During membrane separation, a part of the non-permeate gas stored in the non-permeate gas recovery tank 90 is sent as fuel to the combustion furnace 30 via the combustible gas supply path 36. In the combustion furnace 30, this fuel is mixed with the outside air supplied from the air supply fan 32 and burned to become high-temperature combustion gas. This high-temperature combustion gas flows through the combustion gas path 38 and is used as a heat source for the heat exchanger 24.

(First purge step)
In the first purge step, a purge gas containing carbon dioxide is supplied to the membrane separation unit 40 to discharge the gas to be processed from the membrane separation unit 40, thereby purging the membrane separation unit 40. Here, purging of the membrane separation unit 40 is performed using a path (purge path 120) indicated by a thick arrow in FIG. Specifically, at the time of purging, the valve 103, 121, 105B to 105D, 107B, 107D is opened and the opening and closing of the valve is controlled by the above-described control unit connected to each valve so as to close the other valves. In addition, the operation of the fan is controlled by the above-described control unit connected to each fan so that the purge fan 124 is operated and the other fans are not operated. In the separation apparatus 10, at the time of purging, a purge fan 124 introduces a part of the permeated gas stored in the permeated gas recovery tank at the time of regeneration as a purge gas, and passes through the concentrated supply path 122 to the individual supply paths 104, 104 B to 104 D. Distribute and flow from the lower part of the membrane filters 41, 41B to 41D and flow upward. The used purge gas that has flowed out from the upper part of the membrane filters 41, 41B to 41D passes through the individual discharge paths 106, 106B to 106D and is discharged from the concentrated discharge paths 108B and 108D.

(Regeneration process)
In the regeneration step, a regeneration gas containing heated air is supplied to the membrane separation unit 40 to regenerate the zeolite membrane 45. Here, the zeolite membrane 45 is regenerated using a route (regeneration route 100) indicated by a thick arrow in FIG. At this time, the high-temperature combustion gas used in the heat exchanger 24 is supplied using the path indicated by the thin line arrow in FIG. Specifically, at the time of regeneration, the valves 23, 101, 103, 105B to 105D, 107B, 107D are opened, and the opening and closing of the valves is controlled by the above-described control unit connected to each valve so as to close the other valves. Further, the operation of the fan is controlled by the above-described control unit connected to each fan so that the air supply fan 32, the fuel gas fan 34, and the regeneration air fan 110 are operated and the other fans are not operated. In the separation device 10, during regeneration, air is introduced from the outside by the regeneration air fan 110, and the air is heated by a heat exchanger provided in the concentrated supply path 102 to be used as regeneration gas. This regeneration gas is distributed to the individual supply paths 104, 104B to 104D, flows in from the lower portions of the membrane filters 41, 41B to 41D, and flows upward. The used regeneration gas that has flowed out from the upper part of the membrane filters 41, 41B to 41D passes through the individual discharge paths 106, 106B to 106D and is discharged from the concentrated discharge paths 108B and 108D. During regeneration, a part of the non-permeate gas stored in the non-permeate gas recovery tank 90 at the time of membrane separation is sent as fuel to the combustion furnace 30 via the combustible gas supply path 36. This fuel is mixed with the outside air supplied from the air supply fan 32 in the combustion furnace 30 and burned to become high-temperature combustion gas. This high-temperature combustion gas flows through the combustion gas path 38 and is used as a heat source for the heat exchanger 24.

(Second purge step)
In the second purge step, a purge gas containing carbon dioxide is supplied to the membrane separation unit 40, the regeneration gas is discharged from the membrane separation unit 40, and the membrane separation unit 40 is purged. Here, purging of the membrane separation unit 40 is performed using a path (purge path 120) indicated by a thick arrow in FIG. Since the specific process is the same as the first purge process, the description thereof is omitted.

In the separation apparatus and the regeneration method of the above-described embodiment, the separation membrane used for gas separation can be more regenerated. The reason why such an effect can be obtained is assumed as follows. That is, since the zeolite membrane 45 is used as a separation membrane, it has higher heat resistance than an organic membrane and is suitable for regeneration using a regeneration gas containing heated air. In addition, although a separation membrane used for gas separation does not like cleaning (regeneration) using a liquid, in the present invention, regeneration is performed using a regeneration gas, which is suitable for regeneration of a separation membrane used for gas separation. . In addition, since the gas to be treated contains hydrocarbon combustible gas and carbon dioxide, the fouling substance is oxidized with a regeneration gas containing heated air and discharged to the outside mainly as carbon dioxide or water vapor. The ring substance and the substances resulting from the ring substance hardly remain on the separation membrane. Further, since the separation apparatus 10 includes the separation path 12 and the regeneration path 100, the separation apparatus 10 can perform the separation process and the regeneration process. Further, since the regeneration gas containing heated air is supplied to the membrane separation unit 40 (zeolite membrane 45), it is not necessary to provide a heating device or the like in the membrane separation unit.

In addition, since the separation device 10 includes the regeneration path 100, the zeolite membrane 45 can be regenerated on-site while being incorporated in the separation device 10, so that the trouble of replacing the membrane filter can be saved, and the cost can be reduced. Can be reduced. In addition, since the purge path 120 is provided and the first purge process is performed between the separation process and the regeneration process, the amount of hydrocarbon combustible gas in the regeneration path or the like is zero or small during regeneration, and heating during regeneration is performed. And ignition can be further suppressed. In addition, since a purge path is provided and the second purge process is performed between the regeneration process and the next separation process, the amount of oxygen in the separation path 12 or the like is zero or small at the time of separation, and overheating and ignition during separation are prevented. It can be suppressed more. Moreover, in the heat exchanger 24, since the high-temperature combustion gas obtained by using the non-permeated fluid obtained by membrane separation as a fuel is used as a heat source, it is not necessary to prepare fuel separately. Moreover, since the permeated fluid obtained by membrane separation is used as the purge gas, it is not necessary to prepare a purge gas separately. In the separation path 12, since the membrane filters 41, 41B to 41D are connected in series, the concentration of carbon dioxide contained in the non-permeable gas can be further reduced. In addition, since the membrane filters 41 and 41B to 41D are connected in parallel in the regeneration path and the purge path, regeneration and purge of the membrane filters 41 and 41B to 41D can be performed simultaneously under the same conditions, which is efficient. Further, since the regeneration path and the purge path are common except for the concentrated supply paths 102 and 122, the regeneration path can be efficiently purged. Further, the membrane filters 41, 41B to 41D are arranged vertically so that the gas flows in the vertical direction, and a purge gas containing carbon dioxide is allowed to flow from below the membrane filters 41, 41B to D in the purge path. Since the gas flows upward, the carbon dioxide contained in the purge gas easily pushes air or hydrocarbon-based combustible gas, which is lighter than carbon dioxide, to the upper part of the membrane filters 41, 41B to D. Further, by periodically regenerating, the period until the replacement of the membrane filter can be made longer than that of, for example, the organic membrane, and the cost can be reduced.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

For example, in the above-described embodiment, the separation apparatus 10 includes the purge path 120, but the purge path 120 may not be included. In addition, the regeneration method includes the first purge process, the regeneration process, and the second purge process. However, the regeneration method may not include the first purge process, or may not include the second purge process. However, both the first purge process and the second purge process may not be included. In the separation apparatus 10, a part of the permeate gas stored in the permeate gas recovery tank 70 is used as the purge gas. However, a separately prepared purge gas may be used.

In the separation apparatus 10 described above, the heat introduced from the regenerative air fan 110 is regenerated by heat exchange with the high-temperature combustion gas obtained by burning the combustible gas in the combustion furnace 30 in the heat exchanger 24. However, the present invention is not limited to this. For example, high-temperature combustion gas obtained in the combustion furnace 30 may be supplied as a regeneration gas. In the separation apparatus 10, a part of the non-permeate gas stored in the non-permeate gas recovery tank 90 is used as fuel in the combustion furnace 30, but a separately prepared hydrocarbon-based combustible gas is used as fuel. Also good.

In the above-described embodiment, the separation apparatus 10 is configured such that the membrane filters 41 and 41B to 41D are connected in series in the separation path 12, and are connected in parallel in the regeneration path and the purge path. Not. For example, the separation path may be connected in parallel, the regeneration path may be connected in series, or the purge path may be connected in series. As an example, FIG. 6 shows the gas flow during regeneration in the separation device 210 in which the membrane filters 41, 41B to 41D are connected in series in the separation path and regeneration path and connected in parallel in the purge path. In the separation device 210, the same components as those of the separation device 10 are denoted by the same reference numerals and description thereof is omitted. The separation device 210 includes a regeneration gas supply path 302 that supplies the regeneration gas to the membrane filter 41, and a regeneration gas discharge path 250 that branches from between the valve 81 and the purification unit 82 of the non-permeate gas recovery path 80. I have. Further, the recovery path 80 includes a valve 283 between the regeneration gas discharge path 250 and the purification processing unit 82. The regeneration path 300 is connected to the lower part of the membrane filter 41 and supplies a regeneration gas to the membrane filter 41. The regeneration gas supply path 302 connects the membrane filters 41, 41B to 41D in series. A regeneration gas discharge path 250 branched from the non-permeate gas discharge path 80 is connected to the lower part of the membrane filter 41D. A part of the regeneration gas supply path 302 is common with a part of the supply path 20, and includes a regeneration air fan 110 for introducing air, valves 101 and 23 for adjusting the flow of gas flowing through the regeneration path 300, and The heat exchanger 24 is provided that heats the air to generate a regeneration gas having a temperature suitable for regeneration of the zeolite membrane 45. In the separation apparatus 210 configured in this way, during regeneration, the zeolite membrane 45 is regenerated using the path indicated by the thick arrow in FIG. At this time, the high-temperature combustion gas used in the heat exchanger 24 is supplied using the path indicated by the thin line arrows in FIG.

In the embodiment described above, the separation device 10 includes four membrane filters 41, 41B to 41D. However, the number of membrane filters may be one, two or three, and five or more. But you can. FIG. 7 shows a separation device 410 having one membrane filter. The separation device 410 is configured in the same manner as the separation device 10 except that the membrane separation unit 440 includes only one membrane filter 41 as a membrane filter and a path connecting to the membrane filters 41B to 41D is omitted. .

In the above-described embodiment, the separation apparatus 10 includes the membrane filter 41 and the membrane filters 41B to 41D configured similarly to the membrane filter 41, but instead of these, the membrane filter 46 and the membrane filter 46 are the same. It is good also as a thing provided with the membrane filter comprised in this. In the membrane filter 46, the same components as those of the membrane filter 41 are denoted by the same reference numerals and description thereof is omitted. The membrane filter 46 includes a slit 47 that passes through the membrane filter 46 in a direction perpendicular to the longitudinal direction and communicates a plurality of cells 42 arranged in a row. The cell 42 connected to the slit 47 has plugging materials 48 formed at both ends thereof. In this membrane filter 46, permeating gas (for example, carbon dioxide) having a molecular size that can permeate the zeolite membrane 45 out of the gas to be processed that has entered the cell 42 from the inlet side passes through the zeolite membrane 45 and the porous substrate 44. The light passes through and is sent out from the side surface of the membrane filter 46 or from the slit 47. On the other hand, a non-permeating gas (for example, a hydrocarbon-based combustible gas) that cannot permeate the zeolite membrane 45 flows along the flow path of the cell 42 and is sent out from the outlet side of the cell 42.

In the above-described embodiment, the supply path 20 includes the preprocessing unit. However, the supply path 20 may not include the preprocessing unit. In addition, the supply path 20 includes the heat exchanger 24, but the heat exchange base 24 may not be included, and a heater or the like may be used instead of the heat exchanger 24. In the above-described embodiment, the non-permeate gas recovery path 80 includes the purification processing unit 82. However, the purification processing unit 82 may not be provided.

Hereinafter, an example in which the separation membrane is specifically regenerated using the separation device 410 will be described as an example. In addition, this invention is not limited to an Example.

[Example 1]
(Production of membrane filter)
As a porous substrate, a porous substrate made of alumina in a monolith shape having a diameter of 30 mm and a length of 160 mm was prepared. A DDR type zeolite membrane (permeate vaporization membrane that selectively permeates water) was formed on the surface of the porous substrate as described below to produce a membrane filter.

First, 6.21 g of ethylenediamine (manufactured by Wako Pure Chemical Industries, Ltd.) was put into a 100 ml wide-mouth bottle made of fluororesin, and then 0.98 g of 1-adamantanamine (manufactured by Aldrich) was added to precipitate 1-adamantanamine. It was dissolved so as not to remain. Put 53.87 g of water in a separate beaker, add 22.00 g of 30% by mass silica sol (Snowtex S, manufactured by Nissan Chemical Co., Ltd.) and stir lightly, then mix ethylenediamine and 1-adamantanamine. In addition to the wide-mouthed jar, it was shaken vigorously. Thereafter, the wide-mouth bottle was set on a shaker and shaken at 500 rpm for another hour to prepare a film-forming sol. The film-forming sol had a 1-adamantanamine / silica ratio of 0.0589, a water / silica ratio of 35, and an ethylenediamine / 1-adamantanamine ratio of 16 (all in molar ratio). Three film-forming sols were prepared.

Next, DDR type zeolite fine powder was applied to the porous base material and placed in a stainless steel pressure vessel with a fluororesin inner cylinder. Thereafter, the film-forming sol was poured into a pressure-resistant container and subjected to heat treatment (hydrothermal synthesis) at 150 ° C. for 16 hours. After the heat treatment, a DDR type zeolite membrane was formed on the surface of the base material. After washing with water and drying, the temperature was raised to 750 ° C. in an electric furnace at a rate of 0.1 ° C./min in the atmosphere, maintained for 4 hours, and then cooled to room temperature at a rate of 1 ° C./min. A new membrane filter was thus obtained.

(Production of separation device)
Using the membrane filter obtained as described above, a separation device 410 shown in FIG. 7 was produced.

(Separation test)
A gas to be treated containing 50% by volume (partial pressure 0.25 MPa) of methane, which is a hydrocarbon-based combustible gas, and 50% by volume (partial pressure 0.25 MPa) of carbon dioxide is circulated in the cell of the membrane filter produced above. I let you. The separation temperature was a value measured at the entrance of the membrane filter and was 25 ° C. The permeation side of the membrane filter was at normal pressure. Permeate gas from the side of the membrane filter was collected. At this time, the permeation | transmission flow rate of the carbon dioxide gas which permeate | transmitted the zeolite membrane was measured with the mass flow meter, and the permeation | transmission rate which is the permeation | transmission flow rate per unit time of a carbon dioxide was calculated | required.

(Performance degradation process (separation process))
In order to simulate that the raw gas was not sufficiently pretreated using a separation apparatus equipped with a new membrane filter, liquid hydrocarbons were attached to the membrane surface of the zeolite membrane. And the transmission rate after performance fall was calculated | required similarly to the above-mentioned. This transmission rate was 20 when the new transmission rate was normalized by 100.

(First purge step)
Using the permeate gas (carbon dioxide concentration 95% by volume) stored in the permeate gas recovery tank 70, the membrane separation unit 440 was purged.

(Regeneration process)
In the separator after the performance degradation, regeneration treatment was performed by supplying heated air at 200 ° C. at 5 L / min for 1 hour. Then, the transmission speed after reproduction was determined in the same manner as described above. This transmission rate was 98 when the new transmission rate was normalized by 100.

[Example 2]
In the regeneration step, the permeation speed after regeneration was determined in the same manner as in Example 1 except that the regeneration treatment was performed by supplying heated air at 380 ° C. at 5 L / min for 1 hour. This transmission rate was 100 when the new transmission rate was normalized by 100.

[Example 3]
For the separation apparatus that was subjected to the regeneration process in Example 2, the second purge step similar to the first purge step was performed. Subsequently, a second separation step, a first purge step, a regeneration step, and a second purge step were performed under the same conditions as in the steps of Example 2. Furthermore, the third separation step, the first purge step, and the regeneration step were performed under the same conditions as in the steps of Example 2. And after finishing each separation process and the regeneration process, the permeation speed was determined. When the new transmission rate is normalized by 100, the transmission rate after the second separation step is 32, the transmission rate after the second regeneration step is 100, and the transmission rate after the third separation step is 14 And the transmission rate after the third regeneration step was 100.

[Experimental result]
In each of Examples 1 to 3, it was found that the permeation speed can be returned to the same level as that of a new article by the regeneration process. Among these, the transmission rate of Example 2 regenerated at 380 ° C. was closer to that of the new product than Example 1 regenerated at 200 ° C. From this, it was found that the regeneration temperature is preferably 200 ° C. or higher, and more preferably 380 ° C. or higher.

This application is based on Japanese Patent Application No. 2014-168601 filed on August 21, 2014, and the entire contents of which are incorporated herein by reference.

The present invention can be used in the field of separating mixed gas.

10 separation device, 12 separation path, supply path, 21 valve, 22 pretreatment section, 23 valve, 24 heat exchanger, 30 combustion furnace, 31 valve, 32 air supply fan, 34 fuel gas fan, 36 combustible gas supply path , 38 combustion gas path, 40 membrane separation part, 41, 41B-41D membrane filter, 42 cell, 44 porous substrate, 44a coarse part, 44b fine part, 45 zeolite membrane, 46 membrane filter, 47 slit, 48 Plugging material, 50B-50D connection path, 51 valve, 60 permeate gas recovery path, 61 valve, 62, 62B-62D individual recovery path, 64 centralized recovery path, 70 permeate gas recovery tank, 71 valve, 72 takeout path, 80 non-permeate gas recovery path, 81 valve, 82 purification section, 90 non-permeate gas recovery , 91 valve, 100 regeneration path, 101 valve, 102 concentrated supply path, 103 valve, 104, 104B to 104D individual supply path, 105B to 105D valve, 106, 106B to 106D individual discharge path, 107B, 107D valve, 108B, 108D Concentrated exhaust route, 110 Regenerative air fan, 120 Purge route, 121 Valve, 122 Concentrated supply route, 124 Purge fan, 210 Separator, 250 Regeneration gas discharge route, 283 Valve, 300 Regeneration route, 302 Regeneration gas supply route 410 separation device, 440 membrane separation unit.

Claims (13)

1. A membrane separation unit comprising a zeolite membrane that selectively permeates carbon dioxide;
   A gas to be treated containing hydrocarbon-based combustible gas and carbon dioxide is supplied to the membrane separation unit, and a permeate gas that has permeated the zeolite membrane and a non-permeate gas that has not permeated the zeolite membrane are separated and recovered. A separation path to
   A regeneration path for regenerating the zeolite membrane by supplying a regeneration gas containing heated air to the membrane separation unit;
   Separation device with.
2. The separation apparatus according to claim 1, further comprising a purge path for supplying a purge gas containing carbon dioxide to the membrane separation unit to purge the membrane separation unit.
3. In the membrane separation unit, a membrane filter having one or more cells serving as a gas flow path is disposed so that the longitudinal direction and the vertical direction of the cells coincide with each other,
   The purge path includes a purge gas supply path that is connected to a lower part of the membrane filter and supplies the purge gas, and a purge gas discharge path that is connected to an upper part of the membrane filter and discharges the purge gas. The separation device as described.
4. The separation apparatus according to claim 2 or 3, wherein the purge path is connected to a permeate gas recovery unit provided in the separation path and supplies the permeate gas as a purge gas to the membrane separation unit.
5. The regeneration path includes an air introduction path for introducing air, and a heating unit that heats the introduced air using a combustible gas to obtain the heated air.
   The separation apparatus according to any one of claims 1 to 4.
6. The heating unit includes a combustion furnace that burns the combustible gas, and a heat exchanger that heats the introduced air by heat exchange with a high-temperature combustion gas obtained in the combustion furnace. The separation device according to claim 5.
7. The separation apparatus according to claim 5, wherein the heating unit includes a combustion furnace that heats the introduced air by mixing and combusting the combustible gas and the introduced air.
8. The separation apparatus according to any one of claims 1 to 7, wherein the regeneration is performed at 150 ° C or more and 500 ° C or less.
9. The separation apparatus according to any one of claims 1 to 8, wherein the zeolite membrane is a DDR type zeolite membrane.
10. The separation apparatus according to any one of claims 1 to 9, wherein the hydrocarbon-based combustible gas is at least one selected from the group consisting of methane, ethane, butane, and propane.
11. A purge path for supplying a purge gas containing carbon dioxide to the membrane separation unit and purging the membrane separation unit;
    The membrane separation section includes a plurality of membrane filters having one or more cells that serve as gas flow paths, the separation membrane is connected in series with the plurality of membrane filters, and the regeneration route and the purge route are The separation device according to any one of claims 1 to 10, wherein a plurality of membrane filters are connected in parallel.
12. A membrane separation part equipped with a zeolite membrane that selectively permeates carbon dioxide, and a permeate gas that supplies a gas to be treated containing hydrocarbon combustible gas and carbon dioxide to the membrane separation part and permeates the zeolite membrane. And a separation path for separating and recovering the non-permeate gas that has not permeated the zeolite membrane, and a regeneration method for regenerating the zeolite membrane in a separation device comprising:
    A regeneration step of regenerating the zeolite membrane by supplying a regeneration gas containing heated air to the membrane separation unit;
    A playback method including:
13. A purge step of purging the membrane separation unit by supplying a purge gas containing carbon dioxide to the membrane separation unit before at least one of the regeneration step and after the regeneration step;
    The reproduction | regenerating method of Claim 12 containing these.

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