JP6081348B2 - Porous membrane evaluation apparatus and porous membrane evaluation method - Google Patents

Description

  The present invention relates to a technique for evaluating a porous membrane.

  A microporous membrane such as a zeolite membrane enables highly selective permeation separation that is difficult to achieve with conventional separation membranes due to molecular sieve action and unique adsorption characteristics derived from the micropore structure. For example, an A-type zeolite membrane or a Y-type zeolite membrane can be used for liquid separation such as dehydration of ethanol. In an actual separation apparatus using a zeolite membrane, a porous tube (also referred to as “zeolite membrane element”) in which a zeolite membrane is formed on the outer peripheral surface of a porous cylindrical support formed of alumina or the like is used. . In the production of such a porous tube, the quality of the porous tube is confirmed by actually evaluating the alcohol dehydration performance such as ethanol or isopropyl alcohol (IPA).

Attempts have also been made to utilize zeolite membranes for gas separation such as carbon dioxide. For example, Patent Document 1 discloses a membrane separation and recovery system for CO ₂ . The CO ₂ membrane separation means of the system includes a hydrophilic zeolite membrane that has been dehydrated by heat treatment at 100 to 800 ° C. In the system, a dehydrating unit is provided in front of the CO ₂ membrane separating unit.

  On the other hand, Patent Document 2 discloses an apparatus for measuring a pore size distribution. In the apparatus, a subject having a pore is held such that one end of the pore communicates with the primary chamber and the other end of the pore communicates with the secondary chamber. The primary chamber is supplied with a test gas that is a mixed gas of a non-condensable gas and a condensable gas, and the test gas that has passed through the subject while changing the mixing ratio of the non-condensable gas and the condensable gas. The quantity is measured. This makes it possible to accurately measure the diameter of the pores and the distribution state thereof (so-called palm porometry method). Also in Patent Documents 3 and 4, an apparatus similar to that of Patent Document 2 is disclosed.

JP 2012-232274 A JP 2001-235417 A JP 2005-74382 A JP 2008-157826 A

  By the way, it has been clarified by experiments by the present inventors that a zeolite membrane that exhibits high performance in alcohol dehydration does not necessarily have high gas separation performance. Therefore, it is conceivable to use the palm porometry method for the evaluation of the porous film. However, in the apparatuses of Patent Documents 2 to 4, only one porous film can be evaluated, and the quality of a plurality of porous films is evaluated. Evaluation cannot be performed efficiently.

  This invention is made | formed in view of the said subject, and aims at performing quality evaluation of several porous membranes accurately and efficiently.

  The invention according to claim 1 is a porous membrane evaluation apparatus for evaluating a porous membrane, each of which contains a plurality of porous membranes, and the internal space is formed by the porous membrane, and the first space and the second space. And a plurality of first connecting pipes connecting in series the plurality of first spaces in the plurality of membrane accommodating portions and the first space in the last membrane accommodating portion to the exhaust port And a value obtained by dividing the partial pressure of the vapor by the saturated vapor pressure of the vapor is used as a relative vapor pressure, and a mixed gas containing the vapor having a predetermined relative vapor pressure and the dry gas is Provided in each of the plurality of second connection pipes and the plurality of second connection pipes respectively connected to the plurality of second spaces in the plurality of film housing parts, the mixed gas supply section continuously supplying one space Connected to a plurality of valves and the plurality of second connecting pipes It is, when the plurality of valves is opened individually, and a flow rate measurement unit that measures the flow rate of gas through the opened valve.

  The invention according to claim 2 is the porous membrane evaluation apparatus according to claim 1, wherein the predetermined relative vapor pressure is 0.2 or less.

  Invention of Claim 3 is a porous membrane evaluation apparatus of Claim 1 or 2, Comprising: The density | concentration of the said vapor | steam in the gas discharged | emitted from the said 1st space of the said last film | membrane accommodating part is measured. A vapor concentration measurement unit is further provided.

  A fourth aspect of the present invention is the porous membrane evaluation apparatus according to any one of the first to third aspects, wherein the porous membrane evaluation apparatus is provided in a first connection pipe that connects the last film housing portion and the exhaust port. A first pressure adjusting unit, a collecting discharge pipe to which ends of the plurality of second connecting pipes opposite to the plurality of film housing parts are connected, and a second pressure adjusting unit provided in the collecting discharge pipe; Is further provided.

  The invention according to claim 5 is a porous membrane evaluation method in a porous membrane evaluation device, wherein the porous membrane evaluation device accommodates a plurality of porous membranes, and the internal space is a porous membrane. A plurality of membrane accommodating portions partitioned into a first space and a second space and a plurality of first spaces in the plurality of membrane accommodating portions are connected in series, and the first space in the last membrane accommodating portion is used as an exhaust port. A plurality of first connection pipes to be connected; a plurality of second connection pipes respectively connected to a plurality of second spaces in the plurality of membrane housing parts; and a plurality of valves respectively provided in the plurality of second connection pipes The porous membrane evaluation method includes: a) the steam having a predetermined relative vapor pressure and a dry gas, with a value obtained by dividing the partial pressure of the vapor by the saturated vapor pressure of the vapor as a relative vapor pressure The mixed gas is passed through the first membrane housing And continuously feeding step between, b) when the said a) step in parallel opened individually the plurality of valves, and a step of measuring the flow rate of gas through the opened valve.

  Invention of Claim 6 is a porous membrane evaluation method of Claim 5, Comprising: Before the said a) process, only the said dry gas is in the said 1st space of the said 1st film | membrane accommodating part. D) a step of measuring the flow rate of gas passing through the opened valves when the plurality of valves are individually opened in parallel with the step c), and e) the step b) a step of calculating an evaluation value of each porous membrane based on the flow rate obtained by the step and the flow rate obtained by the step d).

  Invention of Claim 7 is a porous membrane evaluation method of Claim 5 or 6, Comprising: The density | concentration of the said vapor | steam in the gas discharged | emitted from the said 1st space of the said last film | membrane accommodating part is the said. The step b) is started when the concentration of the vapor in the mixed gas supplied to the first space of the first membrane housing portion coincides.

  According to the present invention, quality evaluation of a plurality of porous membranes can be performed accurately and efficiently.

It is a figure which shows the structure of a porous membrane evaluation apparatus. It is sectional drawing which shows a film | membrane accommodating part. It is a figure which shows the flow of the process which evaluates a porous membrane. Is a diagram showing the relationship between CO ₂ / _{H 2} permeation separation performance and water / IPA permeation separation performance. It is a diagram showing the relationship between CO 2 _/ H ₂ permeation separation performance and gas permeability contribution. It is a figure which shows the time-dependent change of the gas permeability in a porous membrane, and the time-dependent change of the dew point of the water vapor | steam contained in the gas in the last 1st connection pipe.

  FIG. 1 is a diagram showing a configuration of a porous membrane evaluation apparatus 1 according to an embodiment of the present invention. The porous membrane evaluation device 1 is a device for evaluating the quality of a plurality of porous membranes 9 used as separation membranes. The porous membrane evaluation apparatus 1 includes a plurality of membrane housing portions 2 that respectively accommodate a plurality of porous membranes 9, a plurality of first connection pipes 31 that connect the plurality of membrane housing portions 2 in series, and a plurality of membrane housings. A plurality of second connection pipes 32 respectively connected to the unit 2, a plurality of valves (for example, electromagnetic valves) 33 provided respectively in the plurality of second connection pipes 32, and a predetermined gas to the first film housing unit 2 A supplied mixed gas supply unit 4 and a control unit 10 responsible for overall control of the porous membrane evaluation apparatus 1 are provided. The gas from the mixed gas supply unit 4 sequentially flows from the first film housing unit 2 to the last film housing unit 2 in the plurality of film housing units 2 connected in series. In FIG. 1, five film accommodating portions 2 are illustrated, but the number of the film accommodating portions 2 may be two or more, for example, several tens.

  FIG. 2 is a cross-sectional view showing one film housing portion 2. The porous membrane 9 in the present embodiment is a zeolite membrane provided in a porous tube 91 (so-called zeolite membrane element or separation membrane element). The porous membrane 9 is formed on the entire outer peripheral surface of a porous cylindrical support 911 formed of alumina or the like. In FIG. 2, the porous membrane 9 is indicated by a thick solid line. For example, an A-type, Y-type, or MOR-type zeolite membrane is used as the porous membrane 9.

  Support ends 912 and 913 formed of dense alumina or the like are provided at both ends of the cylindrical support 911. One support end 912 is cylindrical, and one end of the cylindrical support 911 is closed by the support end 912. The other support end 913 is cylindrical, and one end of the second connection pipe 32 is fixed to the support end 913. Thus, the inside of the porous tube 91 is a space that communicates with the outside only through the porous membrane 9 except for the second connection tube 32. Preferably, the entire porous tube 91 is made of ceramic. The pores of the cylindrical support 911 are sufficiently larger than the pores of the porous membrane 9.

  Each membrane accommodating portion 2 has a cylindrical main body portion 21 whose both ends are closed, and the porous tube 91 is inserted into the main body portion 21. Actually, one end of the main body 21 is a lid that can be opened and closed, and the porous tube 91 can be replaced. For example, the main body 21 is made of a metal such as stainless steel. The membrane housing part 2 is also called a “single tube membrane module”. Two first connecting pipes 31 are connected to the main body portion 21 of each membrane housing portion 2 except for the first and last membrane housing portions 2 in FIG. 1. One first connection pipe 31 is provided in the vicinity of one support end 912. The other first connection pipe 31 is provided in the vicinity of the other support end 913.

  In the main body portion 21 of the first membrane housing portion 2, a supply pipe 42 (see FIG. 1) of the mixed gas supply portion 4 is provided in the vicinity of the support end portion 913 and is connected to the downstream membrane housing portion 2. A tube 31 is provided in the vicinity of the support end 912. In the main body portion 21 of the last membrane housing portion 2, a first connection pipe 31 connected to the upstream membrane housing portion 2 is provided in the vicinity of the support end portion 913, and another one denoted by reference numeral 31a in FIG. A first connection pipe (hereinafter referred to as “last first connection pipe 31 a”) is provided in the vicinity of the support end 912.

  The inside of the main body portion 21 of the membrane housing portion 2 has two first connection pipes 31 (in the main body portion 21 of the first membrane housing portion 2, the supply pipe 42 of the mixed gas supply portion 4 and the one first connection pipe 31). , And the second connection pipe 32 is a sealed space. Specifically, inside the main body portion 21, a space 201 (hereinafter referred to as “first space 201”) between the inner peripheral surface of the main body portion 21 and the outer peripheral surface of the porous tube 91, and the porous tube 91, a space 202 inside (hereinafter referred to as “second space 202”). The gas from the mixed gas supply unit 4 flows in series in the first spaces 201 of the plurality of membrane accommodating units 2, and the gas that has permeated through the porous membrane 9 flows into the second space 202. Therefore, it can be said that the first space 201 is a non-permeate side space with respect to the porous membrane 9 and the second space 202 is a permeate side space with respect to the porous membrane 9. In the porous membrane evaluation apparatus 1, the cylindrical support 911 and both support end portions 912 and 913 of the porous tube 91 are part of the membrane accommodating portion 2, and the internal space of the membrane accommodating portion 2 is porous. It can be understood that the first space 201 and the second space 202 are partitioned by the film 9.

  In FIG. 1, which shows a simplified structure of the membrane housing portion 2, the space on the left side of the porous membrane 9 shown by a thick solid line is the first space 201 inside the membrane housing portion 2 shown by a rectangle, The space is the second space 202. As described above, the plurality of first connection pipes 31 connect the plurality of first spaces 201 in the plurality of membrane housing parts 2 in series, and the last first connection pipe 31a is in the last film housing part 2. The first space 201 is connected to the exhaust port 50. For example, the exhaust port 50 opens outdoors. The plurality of second connection pipes 32 are respectively connected to the plurality of second spaces 202 in the plurality of film housing units 2. The plurality of membrane accommodating portions 2 are accommodated in a thermostatic chamber 11 indicated by a rectangular broken line in FIG. The temperature of the plurality of film accommodating units 2 can be adjusted by a thermostatic chamber 11 that is a temperature adjusting unit. Actually, the first connecting pipe 31 that connects the membrane accommodating portions 2 is also accommodated in the thermostatic chamber 11.

  A pressure gauge 51, a back pressure valve 52 that is a pressure adjusting unit, and a vapor concentration measuring unit 53 are provided in order from the last membrane housing unit 2 to the exhaust port 50 in the last first connection pipe 31 a. . As will be described later, when a gas containing steam is supplied from the mixed gas supply unit 4, the pressures in the first spaces 201 of the plurality of membrane accommodating units 2 are adjusted by the opening degree of the back pressure valve 52. Further, the vapor concentration measuring unit 53 measures the concentration of the vapor in the gas discharged from the first space 201 of the last film housing unit 2.

  The ends of the plurality of second connection pipes 32 opposite to the plurality of membrane housing parts 2 are connected to one collective discharge pipe 34. The collective discharge pipe 34 connects the plurality of second connection pipes 32 to the exhaust port 60. For example, the exhaust port 60 opens outdoors. The collective discharge pipe 34 is provided with a pressure gauge 61, a back pressure valve 62 that is a pressure adjustment unit, and a flow rate measurement unit 63 in order from the plurality of second connection pipes 32 toward the exhaust port 60. That is, the pressure gauge 61, the back pressure valve 62, and the flow rate measuring unit 63 are connected to the plurality of second connection pipes 32 via the collective discharge pipe 34. During measurement, which will be described later, the pressure in the second space 202 of the membrane housing portion 2 connected to the valve 33 is the back pressure valve in a state where only one valve 33 is opened among the plurality of valves 33 serving as the flow path opening / closing portions. It is adjusted by the opening degree of 62. Further, the flow rate of the gas passing through the opened valve 33 is measured by the flow rate measuring unit 63.

  The mixed gas supply unit 4 includes a dry gas generation unit 41 that generates a dry gas, and a supply pipe 42 that connects the dry gas generation unit 41 and the first space 201 of the first membrane housing unit 2. The dry gas generation unit 41 includes a dehumidifier and a compressor, and generates dry air as a dry gas (non-condensable gas) by compressing the surrounding air while dehumidifying it. Instead of the dry gas generation unit 41, a gas cylinder that stores high-pressure gas (may be gas other than air) can be attached. In the supply pipe 42, a regulator 43 that is a pressure adjusting unit, a flow rate controller (for example, a mass flow controller) 44, and a pressure gauge that is a pressure measuring unit in order from the dry gas generating unit 41 toward the first membrane housing unit 2. 45 is provided. The supply pipe 42 is attached with an auxiliary pipe 46 that connects a position between the regulator 43 and the flow rate controller 44 and a position between the flow rate controller 44 and the pressure gauge 45. The auxiliary pipe 46 includes, in order from the end on the regulator 43 side to the end on the pressure gauge 45 side, a flow rate controller (for example, a mass flow controller) 47, a bubbler 48 that is a steam supply unit, and a channel opening / closing unit. A certain valve (for example, electromagnetic valve) 49 is provided.

  In the mixed gas supply unit 4, the dry gas generated by the dry gas generation unit 41 is supplied to the supply pipe 42, and the pressure of the dry gas is adjusted by the regulator 43. The dry gas that has passed through the regulator 43 is guided to a flow rate controller 44 on the supply pipe 42 and a flow rate controller 47 on the auxiliary pipe 46. The dry gas from the flow controller 47 on the auxiliary pipe 46 is supplied into the water stored in the tank of the bubbler 48, and water vapor (condensable gas) is generated. In a state where the valve 49 is opened, the steam is mixed with the dry gas in the supply pipe 42 at a position between the flow controller 44 and the pressure gauge 45. Thereby, the mixed gas containing the steam and the dry gas is supplied to the first space 201 in the first film housing unit 2.

  Actually, the steam in the mixed gas supplied to the first membrane housing unit 2 is obtained by dividing the steam partial pressure (P) by the steam saturation steam pressure (Ps) as the relative steam pressure (P / Ps). The flow rate controller 44 of the supply pipe 42 and the flow rate controller 47 of the auxiliary pipe 46 are controlled so that the saturated vapor pressure becomes a predetermined value. The relative vapor pressure (also referred to as relative pressure) of the vapor can be calculated from the pressure in the pressure gauge 45, the temperature in the tank of the bubbler 48 (a thermometer is provided in the bubbler 48), and the like. When supplying only the mixed gas whose relative vapor pressure of the vapor is 0, that is, only the dry gas, to the first film housing unit 2, the valve 49 is closed. Note that the steam generated by the bubbler 48 may be steam other than water. For example, when the environmental load is small, the steam may be alcohol such as ethanol. Further, when a gas other than air (for example, carbon dioxide) is used as the dry gas, the gas discharged to the exhaust ports 50 and 60 is removed by a gas recovery unit including a dehumidifier and a compressor. In compressing while dehumidifying, the gas may be reused in the mixed gas supply unit 4 as a dry gas.

  FIG. 3 is a diagram showing a flow of processing for evaluating the porous film 9 in the porous film evaluation apparatus 1. When evaluating the porous membrane 9, first, a plurality of porous membranes 9 are prepared and attached to the plurality of membrane accommodating portions 2 (step S11). Subsequently, the plurality of (all) valves 33 provided in the plurality of second connection pipes 32 are opened, and the back pressure valve 52 of the last first connection pipe 31a and the back pressure valve 62 of the collective discharge pipe 34 are fully opened. The Further, the valve 49 provided in the auxiliary pipe 46 is closed. Then, the continuous supply of only the dry gas to the first space 201 of the first film housing unit 2 is started by the mixed gas supply unit 4 (step S12).

  At this time, the flow rate controller 44 adjusts the flow rate per unit time to a predetermined value (for example, 10 liters per minute (10 [L / min])), and the internal temperature of the thermostat 11 is higher than room temperature. (For example, 130 ° C.). The supply of the dry gas to the plurality of film housing units 2 is continued for a predetermined time (for example, 3 hours). As a result, the plurality of porous membranes 9 are dried, and moisture remaining in the porous membrane 9 is removed. When the permeability of the porous membrane 9 is very high, the porous membrane 9 is accommodated in the rear membrane accommodating portion 2 (the membrane accommodating portion 2 closer to the last first connection pipe 31a than the supply pipe 42 of the mixed gas supply portion 4). The supply of dry gas to the porous membrane 9 may be insufficient. In this case, it is preferable to ensure supply of the dry gas to the porous membrane 9 accommodated in the rear membrane accommodating portion 2 by restricting the back pressure valve 62 of the collective discharge pipe 34.

  In the porous membrane evaluation apparatus 1, the vapor concentration in the gas flowing through the last first connection pipe 31 a is measured (monitored) by the vapor concentration measurement unit 53, and the vapor concentration is constant at approximately zero. Thus, it can be determined that the drying of the porous membrane 9 has reached a steady state. As the vapor concentration measuring unit 53 for measuring the concentration of water vapor, for example, a water dew point meter (for example, TK-100 manufactured by TEKHNE) can be used. In this case, the vapor concentration is converted from the dew point. It is possible. After drying the plurality of porous membranes 9, the internal temperature of the thermostatic chamber 11 is lowered to a predetermined evaluation temperature (for example, 40 ° C.) while continuing to supply the drying gas. Since the plurality of porous membranes 9 are held in the sealed membrane housing portion 2, the porous membrane 9 does not come into contact with the outside air and moisture is not adsorbed again.

  When the internal temperature of the thermostatic chamber 11 reaches the evaluation temperature, a plurality (all) of the valves 33 are closed. In addition, the regulator 43 and the last first connection pipe so that the pressure (total pressure) of the dry gas supplied to the first space 201 of the first membrane housing unit 2 becomes a predetermined value (for example, 3 atmospheres). The back pressure valve 52 of 31a is adjusted. Then, the flow rate of the gas per unit time is measured by the flow rate measurement unit 63 in a state where the valve 33 of the second connection pipe 32 connected to the one membrane housing unit 2 is opened and the other valve 33 is closed. The above-described process of measuring only the gas flow rate by opening only the valve 33 corresponding to one membrane housing unit 2 is sequentially performed on the plurality of membrane housing units 2 by automatic control of the control unit 10. Thus, in parallel with continuous supply of the dry gas, when the plurality of valves 33 are individually opened, the flow rate of the gas passing through the opened valves 33 is measured (step S13).

  The gas flow rate acquired by the flow rate measuring unit 63 for each membrane accommodating unit 2 is the gas permeation amount of the porous membrane 9 accommodated in the membrane accommodating unit 2, and is output to the control unit 10. Further, the pressure in the pressure gauges 51 and 61 when the gas permeation amount of the porous membrane 9 is measured is also output to the control unit 10, and the pressure between the first space 201 and the second space 202 of the membrane housing unit 2 is output. The difference is obtained. In the preferred porous membrane evaluation apparatus 1, when measuring the gas permeation amount of each porous membrane 9, the gap between the first space 201 and the second space 202 of the membrane housing portion 2 in which the porous membrane 9 is accommodated. The back pressure valve 52 of the last first connection pipe 31a and the back pressure valve 62 of the collective discharge pipe 34 are adjusted so that the pressure difference is within a predetermined range.

  When the gas permeation amount of each porous membrane 9 when the relative vapor pressure of the vapor is 0 is acquired, the first space of the first membrane accommodating portion 2 of the mixed gas containing vapor is opened by opening the valve 49. Continuous supply to 201 is started (step S14). At this time, the relative vapor pressure of the vapor in the mixed gas is a relative vapor pressure satisfying a predetermined value greater than 0 (((P / Ps)> 0). The flow rate ratio of the flow rate controllers 44 and 47 is adjusted so as to be referred to as “relative vapor pressure”. All the valves 33 are in a closed state.

  Further, the vapor concentration measuring unit 53 constantly (in real time) measures the concentration of the vapor in the non-permeating gas discharged from the first space 201 of the last membrane housing unit 2. When the vapor concentration to be measured coincides with the vapor concentration in the mixed gas supplied from the mixed gas supply unit 4 to the first membrane housing unit 2, the adsorption amount of the vapor in the porous membrane 9 becomes constant. The measurement of the gas permeation amount of each porous membrane 9 is started assuming that it is in a steady state (that is, in a steady state). Specifically, while continuously supplying the mixed gas, the flow rate measurement unit 63 is opened by opening only the valve 33 of the second connection pipe 32 connected to the one membrane housing unit 2 as in the case of Step S13. Thus, the process of measuring the gas flow rate is sequentially performed on the plurality of film housing units 2. As described above, the flow rate measuring unit 63 measures the flow rate of the gas passing through the opened valves 33 when the plurality of valves 33 are individually opened in parallel with the continuous supply of the mixed gas containing steam. (Step S15). The gas flow rate acquired by the flow rate measuring unit 63 for each membrane accommodating unit 2 is output to the control unit 10 as the gas permeation amount of the porous membrane 9 accommodated in the membrane accommodating unit 2. Further, the pressure in the pressure gauges 51 and 61 when the gas permeation amount of the porous membrane 9 is measured is also output to the control unit 10, and the pressure between the first space 201 and the second space 202 of the membrane housing unit 2 is output. The difference is obtained.

  When measuring the gas permeation amount of the porous membrane 9, the flow rate of the mixed gas flowing through the first spaces 201 of the plurality of membrane accommodating portions 2 is preferably 5 [L / min] or more. Thereby, it is possible to shorten the time until the vapor concentration measured by the vapor concentration measurement unit 53 coincides with the vapor concentration of the mixed gas in the mixed gas supply unit 4. Further, the flow rate of the mixed gas flowing through the first space 201 of the plurality of film accommodating units 2 is preferably 500 [L / min] or less. Thereby, it can avoid that an excessive pressure gradient generate | occur | produces in the several film | membrane accommodating part 2 connected in series. When the permeability of the porous membrane 9 is very high, the gas permeation amount of the porous membrane 9 is 5 liters [L / min] by adjusting the back pressure valve 52 of the last first connecting pipe 31a. It is preferable to reduce the pressure difference between the first space 201 and the second space 202 sandwiching the porous membrane 9 so as to be as follows. Thereby, reduction of the flow rate of the mixed gas necessary for measurement of the gas permeation amount of the porous membrane 9 and reduction of the gradient of the relative vapor pressure inside each membrane accommodating unit 2 are realized.

  In the porous membrane evaluation apparatus 1, the evaluation relative vapor pressure is changed to another value as necessary, and the processes of steps S14 and S15 are repeated. When evaluating the porous membrane 9 that is a zeolite membrane, the gas permeation amount of the porous membrane 9 is measured while changing the evaluation relative vapor pressure to, for example, 0.08, 0.2, and 0.3. The In FIG. 3, illustration of the process of repeating steps S14 and S15 is omitted.

  When the measurement of the gas permeation amount of the porous membrane 9 at all evaluation relative vapor pressures is completed, the gas permeation amount Q at each relative vapor pressure is set between the first space 201 and the second space 202 sandwiching the porous membrane 9. The gas permeability P (= Q / (Δp · S)) is obtained by dividing by the pressure difference Δp and the area S of the porous membrane 9. The gas permeability is a unit pressure difference and a gas permeation amount per unit area. Then, a value obtained by dividing the gas permeability at the evaluation relative vapor pressure where the relative vapor pressure is greater than 0 by the gas permeability when the relative vapor pressure is 0 is obtained as the relative permeability of the evaluation relative vapor pressure. (Step S16). In the porous membrane 9, as the relative vapor pressure increases, the vapor is condensed in a larger gap and the gap is closed. Therefore, the higher the relative permeability of the evaluation relative vapor pressure is, the higher the relative vapor pressure is. It can be understood that the ratio of the gap larger than the gap of the size to be set is larger. Thus, based on the gas flow rate in the dry state obtained by the process of step S13 and the gas flow rate in the condensed state of the vapor obtained by the process of step S15, the evaluation value of each porous membrane 9 is obtained. The relative transmittance is calculated. Thus, the process for evaluating the porous membrane 9 is completed.

Next, the relationship between the gas separation performance and the dehydration performance of the porous membrane will be described, and then the relationship between the gas separation performance of the porous membrane and the relative transmittance obtained by the porous membrane evaluation apparatus 1 will be described. Table 1 shows the dehydration performance of a commercially available tubular Y-type zeolite membrane element (manufactured by Hitachi Zosen Corporation, length 115 cm, diameter 1.6 cm, effective membrane area 0.05 m ² ) and its gas separation performance. A comparison result is shown. Here, the water / IPA permeation separation performance is evaluated by the pervaporation separation method (feed mixture composition (weight%): water / IPA = 20/80, temperature: 75 ° C.), and CO ₂ / H ₂ permeation separation performance. Was evaluated by a gas separation method (feed gas composition (mol%): CO ₂ / H ₂ = 75/25, temperature: 60 ° C., total pressure: 2 MPa, supply gas total flow rate: 80 L (STP) / min).

As shown in Table 1, with respect to water / IPA permeation separation performance, the number 3 sample exhibits a higher separation performance α (water / IPA) than the number 1 and number 2 samples. On the other hand, with respect to the CO ₂ / H ₂ permeation separation performance, the number 3 sample exhibits higher separation performance α (CO ₂ / H ₂ ) than the number 1 sample, but lower separation performance α (CO ₂ / H ₂ ). Thus, a zeolite membrane that exhibits high performance in alcohol dehydration does not necessarily have high gas separation performance.

FIG. 4 is a diagram showing the relationship between the CO ₂ / H ₂ permeation separation performance and the water / IPA permeation separation performance, where the vertical axis represents the separation performance α (CO ₂ / H ₂ ) and the horizontal axis represents the separation performance α. (Water / IPA). As is clear from FIG. 4, there is no correlation between the CO ₂ / H ₂ permeation separation performance and the water / IPA permeation separation performance.

  The reason for such a result is presumed that the difference in the fine membrane structure of the zeolite membrane is largely involved. There are roughly two types of fluid permeation paths in the zeolite membrane: (1) pore paths in zeolite crystals and (2) pore paths between zeolite crystals. The size of the pores in the zeolite crystal is, for example, 0.38 nm for the CHA type and 0.74 nm for the Y type, and varies depending on the type of zeolite. On the other hand, the size of pores between zeolite crystals varies greatly depending on the film forming method and the like. There is no problem if the size is smaller than the size of the pores in the zeolite crystal, but if the gap between crystals becomes too large, the gap becomes a non-selective permeation path.

  In the case where a hydrophilic zeolite membrane is used for dehydration, water preferentially adsorbs on the zeolite and may block the voids between crystals. Intercrystalline voids (non-zeolite pores) that can be clogged with water will improve water permeation, and as a result, zeolite membranes with voids between crystals are often superior in dehydration performance. .

  On the other hand, in the case of gas separation, the zeolite membrane is used under dehydrating conditions (drying conditions) in order to effectively use the pores in the zeolite crystals. Therefore, the intercrystalline voids cannot be expected to be clogged with water, and the intercrystalline voids larger than the pores in the zeolite crystal become a non-selective permeation path, which is a factor that greatly reduces the gas separation performance.

  As described above, it must be said that the evaluation of the dehydration performance is insufficient as the quality evaluation of the porous membrane for gas separation. However, if a gas separation test at a high pressure is performed on each porous membrane as a quality evaluation of the porous membrane, the cost for manufacturing the porous membrane is greatly increased.

  Table 2 shows the relative transmittance obtained by the porous membrane evaluation apparatus 1 for the same sample as in Table 1. Here, water vapor is used as the vapor contained in the mixed gas from the mixed gas supply unit 4.

  In Table 2, when the evaluation relative vapor pressure (P / Ps) is 0.3, the samples 1 and 2 have the same relative transmittance of 0.11%, but the evaluation relative vapor pressure is 0.1. In the case of 2 or less, the difference in relative transmittance is clear.

  Moreover, in the sample of No. 1, when the evaluation relative vapor pressure is 0.08, the micropore closed by the condensation of the vapor is set as the micropore of interest, and the drying condition (when the relative vapor pressure is 0) is set. The contribution rate in gas permeation through the micropore of interest (hereinafter referred to as “gas permeation contribution rate”) is 100%, which is the relative permeation rate when the relative vapor pressure is 0, and the evaluation relative vapor pressure is By subtracting 3.63%, which is the relative transmittance at 0.08, it can be estimated as 96.4%. Similarly, when the evaluation relative vapor pressure is 0.2, the micropores blocked by the condensation of the vapor are taken as the micropores of interest, and the gas permeation contribution rate of the path via the micropores of interest under dry conditions is By subtracting 2.25%, which is the relative transmittance when the evaluated relative vapor pressure is 0.2, from 100%, it can be estimated as 97.7%. In addition, when the evaluation relative vapor pressure is 0.3, the micropores blocked by the condensation of the vapor are regarded as the micropores of interest, and the gas permeation contribution ratio of the path via the micropores of interest under the dry condition is By subtracting 0.11%, which is the relative transmittance when the evaluated relative vapor pressure is 0.3, from 100%, it can be estimated as 99.9%.

  Here, the maximum micropore diameters blocked when the evaluation relative vapor pressure is 0.08, 0.2, and 0.3 are R (P / Ps = 0.08) and R (P / Ps = 0.2), R (P / Ps = 0.3) (where R (P / Ps = 0.08) <R (P / Ps = 0.2) <R (P / Ps = 0.3)) It expresses. In this case, the gas permeation contribution ratio when the evaluation relative vapor pressure is 0.08 is the gas permeation contribution ratio with micro pores having a pore diameter of R (P / Ps = 0.08) or less as the target micro pores. (The same applies when the evaluation relative vapor pressure is 0.2 or 0.3).

FIG. 5 is a diagram showing the relationship between the CO ₂ / H ₂ permeation separation performance and the gas permeation contribution ratio, where the vertical axis represents the separation performance α (CO ₂ / H ₂ ) and the horizontal axis represents the gas permeation contribution ratio. Show. In FIG. 5, a point indicating the gas permeation contribution when the evaluation relative vapor pressure is 0.08 is indicated by a circle, and a point indicating the gas permeation contribution when the evaluation relative vapor pressure is 0.2 is a square. The point which shows the gas permeation contribution rate in case evaluation relative vapor pressure is 0.3 is shown with the triangle.

As shown in FIG. 5, when the evaluation relative vapor pressure is 0.2 or less, it can be seen that there is a very good correlation between the CO ₂ / H ₂ permeation separation performance and the gas permeation contribution rate. . Therefore, when the vapor contained in the mixed gas is water vapor, in addition to a dry state where the relative vapor pressure is 0, a predetermined evaluation relative vapor pressure of 0.2 or less (preferably an evaluation relative of 0.08 or more) It can be said that it is preferable to obtain the gas permeation amount of each porous membrane 9 in terms of vapor pressure. Thus, it is possible to infer the _CO 2 / _{H 2} permeation separation performance of the porous membrane 9. That is, as shown in Table 1 and FIG. 4, no correlation was shown between the CO ₂ / H ₂ permeation separation performance and the water / IPA permeation separation performance, but the relative vapor pressure was 0.1. By using a predetermined evaluation relative vapor pressure of 2 or less, a correlation is shown between the CO ₂ / H ₂ permeation separation performance and the gas permeation contribution ratio as shown in FIG. Therefore, in the method according to the present invention, the quality of the porous membrane 9 as the carbon dioxide separation membrane which is a gas separation membrane can be evaluated by setting the relative vapor pressure to a predetermined evaluation relative vapor pressure of 0.2 or less. It becomes possible. Here, in order to show a positive correlation between the CO ₂ / H ₂ permeation separation performance, the gas permeation contribution ratio is obtained. Of course, the CO ₂ / H ₂ permeation separation performance is directly determined from the relative permeation ratio. May be guessed. In addition, as a matter of course, in the evaluation according to the method of the present invention using the test apparatus for one film container 2 as shown in FIG. 2, the relative vapor pressure is set to a predetermined evaluation relative vapor pressure of 0.2 or less, It is also possible to evaluate the quality of the porous membrane 9 as a carbon dioxide separation membrane which is a gas separation membrane.

When the evaluation relative vapor pressure is 0.3, since most of the pores in the porous membrane 9 are blocked by the condensation of the vapor, the CO ₂ / H ₂ permeation separation performance and the gas permeation contribution rate are It is probable that no correlation was obtained. Depending on the type of the porous membrane 9, the quality of the porous membrane 9 can be evaluated even when the evaluation relative vapor pressure is 0.3 (or even when it is greater than 0.2). is there. Moreover, the said preferable range of evaluation relative vapor pressure is applicable also to zeolite membranes of types other than Y type, and a vapor | steam may be other than water.

  As described above, in the porous membrane evaluation apparatus 1, the first spaces 201 in the plurality of membrane accommodating units 2 are connected in series. A plurality of second connection pipes 32 are respectively connected to the second spaces 202 in the plurality of membrane accommodating portions 2, and a plurality of valves 33 are provided in the plurality of second connection pipes 32, respectively. And when the mixed gas containing the vapor | steam of predetermined | prescribed relative vapor pressure and dry gas is continuously supplied to the 1st space 201 in the first film | membrane accommodating part 2, when opening several valve | bulb 33 separately The flow rate of the gas passing through the opened valve 33 is measured. Thereby, it is realized that quality evaluation of a large number of porous films 9 is performed with high accuracy.

  By the way, if the first spaces in the N film accommodating portions are connected in parallel, when a gas is supplied to each of the N film accommodating portions at a flow rate of 10 [L / min], N × 10 [ It is necessary to supply a large amount of gas of [L / min]. Further, in a parallel arrangement of a plurality of membrane accommodating portions, it is also conceivable to perform measurement by providing a plurality of valves on the upstream side of the plurality of membrane accommodating portions and individually opening the plurality of valves. However, in this case, in order to accurately measure the gas permeation amount of the porous membrane, after each valve is opened, continuous supply of a mixed gas to bring the adsorption of vapor in the porous membrane into an equilibrium state (steady state) (Wait time) is required in the measurement for the porous membranes in all membrane accommodating portions.

  On the other hand, in the porous membrane evaluation apparatus 1 in which the first spaces 201 in the plurality of membrane accommodating portions 2 are connected in series, the amount of gas necessary for measurement can be reduced. Moreover, since the continuous supply of the mixed gas for bringing the porous membrane into a steady state is performed in parallel with respect to all the membrane accommodating portions 2, the time required for measurement can be greatly shortened. As a result, the quality evaluation of the plurality of porous membranes 9 can be performed efficiently.

  In the porous membrane evaluation apparatus 1, by providing the thermostatic chamber 11 that accommodates the plurality of membrane accommodating portions 2, the plurality of membrane accommodating portions 2 can be set to a constant temperature during measurement. As a result, the quality evaluation of the plurality of porous membranes 9 can be performed under certain conditions. Moreover, the several porous film | membrane 9 can be easily dried by making the several film | membrane accommodating part 2 into high temperature. As a result, the quality evaluation of the plurality of porous membranes 9 can be performed with higher accuracy.

  Further, when measuring the gas permeation amount, the back pressure valve 52 provided in the last first connection pipe 31 and the back pressure valve 62 provided in the collective discharge pipe 34 are controlled. Thereby, the differential pressure between the first space 201 and the second space 202 can be adjusted, and the quality evaluation of the plurality of porous membranes 9 can be performed more accurately.

  By using the dehumidified air as the dry gas in the mixed gas supply unit 4, the dry gas can be easily prepared and the safety of the operator can be easily ensured. Further, by using water vapor in the mixed gas, it is possible to reduce the environmental load without attaching a special device for removing the vapor from the exhausted gas.

  FIG. 6 shows the time-dependent change in gas permeability in the porous membrane 9 when the relative vapor pressure is changed from 0 (dry state) to 0.08 in the porous membrane evaluation apparatus 1, and the last membrane housing portion. It is a figure which shows a time-dependent change of the dew point of the water vapor | steam contained in the gas discharged | emitted from the 2nd 1st space 201. FIG. In FIG. 6, lines L1, L2, and L2 indicate changes in gas permeability of the first (first) membrane housing portion 2 and the porous membrane 9 accommodated in the second and third membrane housing portions 2, respectively. L3 is attached. Further, a line indicating a change in the dew point of the water dew point meter serving as the vapor concentration measuring unit 53 (that is, a change in the dew point of water vapor contained in the gas in the last first connection pipe 31a) is denoted by A1, and the mixed gas The dew point of water vapor in the mixed gas supplied from the supply unit 4 to the first membrane housing unit 2 is indicated by a broken line with a symbol A0.

  As is apparent from the lines L1 to L3 in FIG. 6, the change in gas permeability in the porous membrane 9 differs depending on the order (position) of the membrane housing portion 2, and the time until the gas permeability becomes constant is also shown. Depending on the order of the membrane accommodating portions 2, the difference is greatly different. Therefore, in order to directly determine whether the gas permeability is constant, that is, whether the condensation of the vapor in the porous membrane 9 is in a steady state, the amount of gas permeation in each porous membrane 9 is determined. The measurement needs to be repeated several times.

  On the other hand, the dew point of the water vapor contained in the gas in the last first connecting pipe 31a (see line A1 in FIG. 6) is the water vapor contained in the mixed gas supplied from the mixed gas supply unit 4 to the first film housing unit 2. After the time T1 when the dew point (see the broken line A0 in FIG. 6) is reached, the gas permeability of the plurality of porous membranes 9 housed in the plurality of membrane housing portions 2 is constant. Therefore, the porous membrane evaluation apparatus 1 measures the concentration of vapor in the gas discharged from the first space 201 of the last membrane accommodating unit 2, and the measured value of the vapor concentration is the first value of the first membrane accommodating unit 2. When the concentration of the vapor in the mixed gas supplied to the one space 201 coincides, measurement of the gas permeation amount in the porous membrane 9 accommodated in each membrane accommodating portion 2 is started. Thereby, it is possible to easily determine whether or not the vapor adhesion to the porous membrane 9 has reached a steady state without repeating the measurement of the gas permeation amount in each porous membrane 9 multiple times. The quality evaluation of the porous membrane 9 can be performed more efficiently. In addition, even if the porous film 9 is a new material that is difficult to determine the steady state, the reproducibility and reliability of the measurement data can be improved, and the quality evaluation of the plurality of porous films 9 can be performed with higher accuracy. It can be carried out.

  The porous membrane evaluation device 1 can be variously modified.

  For example, in the porous membrane evaluation apparatus 1, when only the quality pass / fail judgment is performed on the plurality of porous membranes 9, a reference porous membrane that is a reference for pass / fail is accommodated in one membrane housing portion 2. The gas permeation amount of the plurality of porous membranes 9 may be measured. In this case, the pass / fail of the porous membrane 9 can be determined by comparing the relative transmittance of each porous membrane 9 with the relative transmittance of the reference porous membrane.

In the porous membrane evaluation apparatus 1, gas permeation separation performance other than CO ₂ / H ₂ permeation separation performance may be evaluated. Moreover, the porous membrane evaluation apparatus 1 may be used for the evaluation of the liquid permeation separation performance of the porous membrane 9 and the evaluation of the porous membrane 9 other than the zeolite membrane. Depending on the performance required for the porous membrane 9, the quality of the porous membrane 9 may be evaluated based on only the gas permeation amount at a predetermined evaluation relative vapor pressure without measuring the gas permeation amount in the dry state. Good. In addition, when the temperature variation at the installation location of the porous membrane evaluation apparatus 1 is small, the thermostatic chamber 11 can be omitted.

  2 is merely an example, and may be variously changed according to the shape of the porous membrane 9.

  The configurations in the above-described embodiments and modifications may be combined as appropriate as long as they do not contradict each other.

DESCRIPTION OF SYMBOLS 1 Porous membrane evaluation apparatus 2 Membrane accommodating part 4 Mixed gas supply part 9 Porous membrane 31, 31a 1st connection pipe 32 2nd connection pipe 33 Valve 34 Collective discharge pipe 50,60 Exhaust port 52,62 Back pressure valve 53 Vapor concentration Measurement unit 63 Flow rate measurement unit 201 First space 202 Second space S11 to S16 Steps

Claims (7)

A porous membrane evaluation device for evaluating a porous membrane,
A plurality of membrane containing portions each containing a plurality of porous membranes, and an internal space partitioned into a first space and a second space by the porous membrane;
A plurality of first connection pipes that connect the plurality of first spaces in the plurality of membrane housing portions in series and connect the first space in the last membrane housing portion to the exhaust port;
A value obtained by dividing the partial pressure of the vapor by the saturated vapor pressure of the vapor is used as a relative vapor pressure, and a mixed gas containing the vapor having a predetermined relative vapor pressure and the dry gas is mixed in the first space in the first film housing unit. A mixed gas supply section for continuously supplying to
A plurality of second connection pipes respectively connected to a plurality of second spaces in the plurality of membrane accommodating portions;
A plurality of valves respectively provided in the plurality of second connection pipes;
A flow rate measuring unit that is connected to the plurality of second connection pipes and measures the flow rate of the gas passing through the opened valves when the plurality of valves are individually opened;
A porous membrane evaluation apparatus comprising: The porous membrane evaluation device according to claim 1,
The apparatus for evaluating a porous membrane, wherein the predetermined relative vapor pressure is 0.2 or less. The porous membrane evaluation device according to claim 1 or 2,
The porous membrane evaluation apparatus further comprising a vapor concentration measuring unit that measures the concentration of the vapor in the gas discharged from the first space of the last membrane accommodating unit. It is a porous membrane evaluation apparatus in any one of Claims 1 thru | or 3, Comprising:
A first pressure adjusting unit provided in a first connecting pipe connecting the last membrane housing unit and the exhaust port;
A collective discharge pipe to which ends of the plurality of second connection pipes opposite to the plurality of membrane housing parts are connected;
A second pressure adjusting unit provided in the collective discharge pipe;
A porous membrane evaluation device further comprising: A porous film evaluation method in a porous film evaluation apparatus,
The porous membrane evaluation device is
A plurality of membrane containing portions each containing a plurality of porous membranes, and an internal space partitioned into a first space and a second space by the porous membrane;
A plurality of first connection pipes that connect the plurality of first spaces in the plurality of membrane housing portions in series and connect the first space in the last membrane housing portion to the exhaust port;
A plurality of second connection pipes respectively connected to a plurality of second spaces in the plurality of membrane accommodating portions;
A plurality of valves respectively provided in the plurality of second connection pipes;
With
The porous membrane evaluation method comprises:
a) A value obtained by dividing the partial pressure of the vapor by the saturated vapor pressure of the vapor is used as a relative vapor pressure, and a mixed gas containing the vapor having a predetermined relative vapor pressure and the dry gas is mixed in the first film housing unit. A process of continuously supplying to one space;
b) measuring the flow rate of the gas passing through the opened valves when the plurality of valves are individually opened in parallel with the step a);
A porous membrane evaluation method comprising: The porous membrane evaluation method according to claim 5,
c) before the a) step, continuously supplying only the dry gas to the first space of the first film housing unit;
d) a step of measuring the flow rate of the gas passing through the opened valves when the plurality of valves are individually opened in parallel with the step c);
e) calculating the evaluation value of each porous membrane based on the flow rate obtained by the step b) and the flow rate obtained by the step d);
A method for evaluating a porous membrane, further comprising: The porous membrane evaluation method according to claim 5 or 6,
When the concentration of the vapor in the gas discharged from the first space of the last film housing unit matches the concentration of the vapor in the mixed gas supplied to the first space of the first film housing unit In addition, the method for evaluating a porous membrane is characterized in that the step b) is started.

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