Membrane separation system

Abstract

A membrane separation system according to the present invention comprises: at least one membrane separation part which separates a feed fluid into a permeate fluid and a non-permeate fluid; a heat pump which recovers heat from a first heat medium and moves the heat to a second heat medium; a condensation part which uses the first heat medium to cool and condense the permeate fluid; and a heat exchange part which uses the second heat medium to heat at least one selected from the group consisting of the feed fluid, the non-permeate fluid, and the at least one membrane separation part. The membrane separation system comprises, for example, a first temperature sensor which measures the temperature of at least one selected from the group consisting of the first heat medium and the permeate fluid and a second temperature sensor which measures the temperature of at least one selected from the group consisting of the second heat medium, the feed fluid, the non-permeate fluid, and the at least one membrane separation part.

Description

Membrane separation system

[0001] The present invention relates to a membrane separation system.

[0002] As a method for separating volatile organic compounds from a solution containing the same, a separation method using a separation membrane has been developed. As an example of a separation method using a separation membrane, pervaporation (pervaporation method) using a pervaporation membrane is known. The pervaporation method is suitable for separating volatile organic compounds from a solution containing the same. For example, Patent Document 1 discloses a system for separating and purifying ethanol from an ethanol fermentation broth using an ethanol-selective hydrophobic pervaporation separation membrane.

[0003] Japanese Patent No. 4048279

[0004] In a separation method using a separation membrane, a large amount of heat energy is consumed when separating a feed fluid. This tendency is remarkable when the separation membrane is a pervaporation membrane. For example, a membrane separation apparatus equipped with a pervaporation membrane is usually provided with a heating mechanism for maintaining the temperature of the membrane separation apparatus within an appropriate range in order to promote pervaporation. Since the permeation performance of the pervaporation membrane decreases when the temperature of the feed fluid supplied to the membrane separation apparatus decreases, heating the feed fluid using a heating device is also performed. In addition, the non-permeated fluid discharged from the membrane separation apparatus has a low temperature. Therefore, when a treatment apparatus such as a filtration separation apparatus for treating the non-permeated fluid is provided downstream of the membrane separation apparatus, it is desirable to heat the non-permeated fluid in order to suppress a decrease in the performance of the treatment apparatus. On the other hand, the permeated fluid discharged from the membrane separation apparatus is a gas. Therefore, the membrane separation apparatus is usually provided with a cooling mechanism for condensing and liquefying the permeated fluid. The consumption of heat energy by these heating mechanisms and cooling mechanisms leads to an increase in the cost of the entire system.

[0005] An object of the present invention is to provide a membrane separation system suitable for improving the utilization efficiency of heat energy.

[0006] The present invention provides a membrane separation system comprising: at least one membrane separation unit for separating a supply fluid into a permeable fluid and an impermeable fluid; a heat pump for recovering heat from a first heat medium and transferring it to a second heat medium; a condensation unit for cooling and condensing the permeable fluid using the first heat medium; and a heat exchange unit for heating at least one selected from the group consisting of the supply fluid, the impermeable fluid, and the at least one membrane separation unit using the second heat medium.

[0007] According to the present invention, a membrane separation system suitable for improving the efficiency of thermal energy utilization can be provided.

[0008] This is a schematic configuration diagram showing an example of a membrane separation system according to the first embodiment. This is a schematic cross-sectional view showing an example of a membrane separation section included in the membrane separation system. This is a schematic cross-sectional view showing an example of a separation membrane included in the membrane separation section. This is a schematic unfolded perspective view showing another example of a membrane separation section. This is a schematic configuration diagram showing a modified example 1 of the membrane separation system shown in Figure 1. This is a schematic configuration diagram showing a modified example 2 of the membrane separation system shown in Figure 1. This is a schematic configuration diagram showing a modified example 3 of the membrane separation system shown in Figure 1. This is a schematic configuration diagram showing a modified example 4 of the membrane separation system shown in Figure 1. This is a schematic configuration diagram showing a modified example 5 of the membrane separation system shown in Figure 1. This is a schematic configuration diagram showing a modified example 6 of the membrane separation system shown in Figure 1. This is a schematic configuration diagram showing an example of a membrane separation system according to the second embodiment. This is a schematic configuration diagram showing a modified example 1 of the membrane separation system shown in Figure 11. This is a schematic configuration diagram showing a modified example 2 of the membrane separation system shown in Figure 11. This is a schematic configuration diagram showing a modified example 3 of the membrane separation system shown in Figure 11.

[0009] A membrane separation system according to a first aspect of the present invention comprises: at least one membrane separation unit that separates a supply fluid into a permeable fluid and an impermeable fluid; a heat pump that recovers heat from a first heat medium and transfers it to a second heat medium; a condensation unit that cools and condenses the permeable fluid using the first heat medium; and a heat exchange unit that heats at least one selected from the group consisting of the supply fluid, the impermeable fluid, and the at least one membrane separation unit using the second heat medium.

[0010] In a second aspect of the present invention, for example, the membrane separation system according to the first aspect further comprises a first temperature sensor that measures the temperature of at least one selected from the group consisting of the first heat medium and the permeate fluid, and a second temperature sensor that measures the temperature of at least one selected from the group consisting of the second heat medium, the supply fluid, the non-permeate fluid, and the at least one membrane separation unit.

[0011] In a third aspect of the present invention, for example, in a membrane separation system according to the second aspect, at least one selected from the group consisting of (i) and (ii) below is performed: (i) Based on the monitoring result from the first temperature sensor, the operation of the heat pump is controlled so that the temperature of at least one selected from the group consisting of the first heat medium and the permeate fluid satisfies a first predetermined range. (ii) Based on the monitoring result from the second temperature sensor, the operation of the heat pump is controlled so that the temperature of at least one selected from the group consisting of the second heat medium, the supply fluid, the non-permeate fluid, and the at least one membrane separation unit satisfies a second predetermined range.

[0012] In a fourth embodiment of the present invention, for example, the membrane separation system according to the third embodiment further comprises a heating device for heating at least one selected from the group consisting of the supply fluid, the impermeable fluid, and the at least one membrane separation unit.

[0013] In a fifth embodiment of the present invention, for example, in the membrane separation system according to the fourth embodiment, if, after (ii) is performed, at least one temperature selected from the group consisting of the second heat transfer medium, the supply fluid, the impermeable fluid, and the at least one membrane separation unit does not satisfy the second predetermined range, the operation of the heating device is controlled to satisfy the second predetermined range.

[0014] In a sixth aspect of the present invention, for example, a membrane separation system according to any one of the third to fifth aspects further comprises a cooling device for cooling the first heat transfer medium.

[0015] In a seventh aspect of the present invention, for example, in the membrane separation system according to the sixth aspect, if, after (i) is performed, at least one temperature selected from the group consisting of the first heat transfer medium and the permeate fluid does not satisfy the first predetermined range, the operation of the cooling device is controlled to satisfy the first predetermined range.

[0016] In an eighth embodiment of the present invention, for example, in a membrane separation system according to any one of the first to seventh embodiments, the at least one membrane separation unit has a separation membrane, and the separation membrane includes a permeable vaporization membrane.

[0017] In a ninth aspect of the present invention, for example, in a membrane separation system according to any one of the first to eighth aspects, the supply fluid includes a raw fluid, and the raw fluid includes a solution containing a volatile organic compound.

[0018] In a tenth embodiment of the present invention, for example, the membrane separation system according to the ninth embodiment further comprises a supply unit for storing the raw fluid.

[0019] In the eleventh embodiment of the present invention, for example, the membrane separation system according to the tenth embodiment further comprises a return path for returning the impermeable fluid to the supply unit.

[0020] In a twelfth aspect of the present invention, for example, a membrane separation system according to any one of the first to eleventh aspects further comprises a first circulation path for circulating the first heat medium between the heat pump and the condensing unit, and a second circulation path for circulating the second heat medium between the heat pump and the heat exchange unit.

[0021] In a thirteenth embodiment of the present invention, for example, a membrane separation system according to any one of the first to twelfth embodiments further comprises a filtration separation unit for filtering and separating the impermeable fluid.

[0022] In a fourteenth aspect of the present invention, for example, a membrane separation system according to any one of the first to thirteenth aspects further comprises a depressurization section for reducing the pressure within the permeable space of the membrane separation section, the depressurization section including a vacuum pump.

[0023] In a fifteenth aspect of the present invention, for example, in a membrane separation system according to any one of the first to fourteenth aspects, the at least one membrane separation unit includes a plurality of membrane separation units.

[0024] In a sixteenth embodiment of the present invention, for example, a membrane separation system according to the fifteenth embodiment comprises a membrane separation unit in which a plurality of membrane separation units are connected in series such that the impermeable fluid discharged from the membrane separation unit located upstream is supplied as the supply fluid to the membrane separation unit located downstream.

[0025] The details of the present invention will be described below, but the following description is not intended to limit the present invention to any particular embodiment.

[0026] <Embodiment of Membrane Separation System> The membrane separation system of this embodiment comprises at least one membrane separation unit, a heat pump, a condensing unit, and a heat exchange unit. At least one membrane separation unit separates the supply fluid into a permeable fluid and an impermeable fluid. The heat pump recovers heat from a first heat medium and transfers it to a second heat medium. The condensing unit cools and condenses the permeable fluid using the first heat medium. The heat exchange unit heats at least one selected from the group consisting of the supply fluid, the impermeable fluid, and at least one membrane separation unit using the second heat medium.

[0027] According to the membrane separation system of this embodiment, heat recovered from the permeate fluid via the condensation unit can be supplied to at least one selected from the group consisting of the supply fluid, the impermeable fluid, and at least one membrane separation unit. Therefore, the heat exchange unit can efficiently heat at least one selected from the group consisting of the supply fluid supplied to the membrane separation unit, the impermeable fluid discharged from the membrane separation unit, and the membrane separation unit. In addition, the condensation unit can efficiently cool the permeate fluid discharged from the membrane separation device. As a result, the efficiency of thermal energy utilization in the membrane separation system can be improved.

[0028] In the membrane separation system of this embodiment, at least one membrane separation unit includes a plurality of membrane separation units.

[0029] The following describes a specific example of the membrane separation system of this embodiment with reference to the drawings.

[0030] (First Embodiment) Figure 1 is a schematic diagram showing an example of a membrane separation system according to the first embodiment. The membrane separation system 100A in Figure 1 includes a first membrane separation unit 10 as at least one membrane separation unit. The first membrane separation unit 10 separates the raw fluid F0, which is the supply fluid, into a first permeate fluid F1 and a first impermeable fluid F2. The membrane separation system 100A includes a heat pump 71 as a heat pump. The heat pump 71 recovers heat from the first heat medium M1 and transfers it to the second heat medium M2. The membrane separation system 100A includes a condensation unit 41 as a condensation unit. The condensation unit 41 cools and condenses the first permeate fluid F1 discharged from the first membrane separation unit 10 using the first heat medium M1. The membrane separation system 100A includes a second heat exchange unit 52 as a heat exchange unit. The second heat exchange unit 52 heats the first impermeable fluid F2 discharged from the first membrane separation unit 10 using the second heat transfer medium M2.

[0031] The membrane separation system of the first embodiment further comprises a filtration separation unit for filtering and separating non-permeable fluids.

[0032] The membrane separation system 100A includes a filtration separation unit 40 as a filtration separation unit. The filtration separation unit 40 filters and separates the first impermeable fluid F2 sent from the first membrane separation unit 10. The filtration separation unit 40 can separate and remove impurities contained in the first impermeable fluid F2. The filtration separation unit 40 has, for example, a filtration membrane. As the filtration membrane, for example, a reverse osmosis membrane, an ultrafiltration membrane, etc., can be used.

[0033] In the membrane separation system 100A, heat recovered from the first permeate fluid F1 via the condensation unit 41 can be transferred to the first impermeable fluid F2. Therefore, the first impermeable fluid F2 supplied to the filtration separation unit 40 can be efficiently heated. In addition, the condensation unit 41 can efficiently cool the first permeate fluid F1 discharged from the first membrane separation unit 10. As a result, the efficiency of thermal energy utilization in the membrane separation system 100A can be improved.

[0034] In the membrane separation system of the first embodiment, at least one membrane separation unit may have a separation membrane.

[0035] In the membrane separation system 100A, the first membrane separation unit 10 has a first separation membrane 11. The first separation membrane 11 separates the raw fluid F0, which is the supply fluid, into a first permeable fluid F1 and a first impermeable fluid F2. A membrane separation system 100A having such a configuration is suitable, for example, for separating organic compounds from a solution containing volatile organic compounds.

[0036] As described above, the heat pump 71 recovers heat from the first heat transfer medium M1 and transfers it to the second heat transfer medium M2. The first heat transfer medium M1 is cooled by the heat pump 71 and supplied to the condensation section 41. The second heat transfer medium M2 is heated by the heat pump 71 and supplied to the second heat exchange section 52.

[0037] The heat pump 71 may be a compression type heat pump or an absorption type heat pump. A compression type heat pump, for example, uses the temperature change due to the compression and expansion of the first heat medium M1 to transfer heat from the first heat medium M1 to the second heat medium M2. An absorption type heat pump, for example, continuously absorbs heat from the first heat medium M1 and releases heat to the second heat medium M2 by repeating a cycle of evaporation, absorption, regeneration, and condensation.

[0038] The temperature of the second heat medium M2 supplied to the second heat exchange section 52 is higher than the temperature of the first heat medium M1 supplied to the condensation section 41. The temperature of the first heat medium M1 supplied to the condensation section 41 is, for example, in the range of -80°C to 30°C. The temperature of the second heat medium M2 supplied to the second heat exchange section 52 is, for example, in the range of 25°C to 60°C.

[0039] For example, air, water, antifreeze, or heat transfer oil can be used as the first heat transfer medium M1 and the second heat transfer medium M2. The first heat transfer medium M1 and the second heat transfer medium M2 may be the same or different.

[0040] As described above, in the membrane separation system 100A, the second heat exchange unit 52 heats the first impermeable fluid F2 discharged from the first membrane separation unit 10 using the second heat transfer medium M2. More specifically, the second heat exchange unit 52 heats the first impermeable fluid F2 by performing heat exchange between the second heat transfer medium M2, which is used for heating, and the first impermeable fluid F2, which is used for cooling.

[0041] For example, the second heat exchange section 52 heats the temperature of the first non-permeate fluid F2 discharged from the first membrane separation section 10 to a range of 25°C or higher and 60°C or lower. The second heat exchange section 52 may heat the temperature of the first non-permeate fluid F2 discharged from the first membrane separation section 10 to a range of 30°C or higher and 45°C or lower, or may heat it to a range of 35°C or higher and 40°C or lower.

[0042] As described above, in the membrane separation system 100A, the condensing section 41 cools and condenses the first permeate fluid F1 discharged from the first membrane separation section 10 using the first heat medium M1. According to the condensing section 41, the gaseous permeate fluid is liquefied to obtain a liquid permeate fluid. The condensing section 41 is, for example, a gas-liquid heat exchanger that causes heat exchange between the first heat medium M1 and the gaseous first permeate fluid F1.

[0043] For example, the condensing section 41 cools the temperature of the first permeate fluid F1 discharged from the first membrane separation section 10 to a range of -80°C or higher and 30°C or lower. The condensing section 41 may cool the temperature of the first permeate fluid F1 discharged from the first membrane separation section 10 to a range of -20°C or higher and 20°C or lower, or may cool it to a range of -10°C or higher and 10°C or lower.

[0044] The membrane separation system according to the first embodiment may further comprise: a first temperature sensor that measures the temperature of at least one selected from the group consisting of the first heat medium and the permeate fluid; and a second temperature sensor that measures the temperature of at least one selected from the group consisting of the second heat medium, the feed fluid, the non-permeate fluid, and at least one membrane separation section.

[0045] The membrane separation system 100A includes a first temperature sensor 64 as a first temperature sensor. The first temperature sensor 64 measures the temperature of the first heat medium M1 discharged from the heat pump 71. The membrane separation system 100A also includes a second temperature sensor 62 located downstream of the second heat exchange unit 52 as a second temperature sensor. The second temperature sensor 62 measures the temperature of the first impermeable fluid F2 after it has been heated by the second heat exchange unit 52. Although not shown in the figures, the membrane separation system 100A may further include another second temperature sensor that measures the temperature of the first impermeable fluid F2 discharged from the first membrane separation unit 10 as a second temperature sensor. For example, the operation of the second heat exchange unit 52 may be controlled based on the monitoring results from the other second temperature sensor and the second temperature sensor 62.

[0046] In the membrane separation system of the first embodiment, at least one selected from the group consisting of (i) and (ii) below may be performed: (i) Based on the monitoring results from the first temperature sensor, the operation of the heat pump is controlled so that at least one temperature selected from the group consisting of the first heat medium and the permeate fluid satisfies a first predetermined range. (ii) Based on the monitoring results from the second temperature sensor, the operation of the heat pump is controlled so that at least one temperature selected from the group consisting of the second heat medium, the supply fluid, the non-permeate fluid, and at least one membrane separation unit satisfies a second predetermined range.

[0047] In the membrane separation system 100A, at least one selected from the group consisting of (i) and (ii) below may be performed: (i) Based on the monitoring results from the first temperature sensor 64, the operation of the heat pump 71 is controlled so that the temperature of the first heat medium M1 satisfies a first predetermined range. (ii) Based on the monitoring results from the second temperature sensor 62, the operation of the heat pump 71 is controlled so that the temperature of the first impermeable fluid F2 satisfies a second predetermined range.

[0048] By performing (i) above, the temperature of the first heat transfer medium M1 supplied to the condensing unit 41 can be stably maintained. By performing (ii) above, the temperature of the first impermeable fluid F2 supplied to the filtration separation unit 40 can be stably maintained.

[0049] In the membrane separation system 100A, both of the above (i) and (ii) may be performed.

[0050] The first predetermined range in (i) is, for example, a range of not lower than -80°C and not higher than 30°C. The first predetermined range may be a range of not lower than -20°C and not higher than 20°C, or may be a range of not lower than -10°C and not higher than 10°C. The second predetermined range in (ii) is, for example, a range of not lower than 25°C and not higher than 60°C. The second predetermined range may be a range of not lower than 30°C and not higher than 45°C, or may be a range of not lower than 35°C and not higher than 40°C.

[0051] Note that, at the start of operation of the membrane separation system 100A, the heating of the first non-permeate fluid F2 by the second heat exchange unit 52 may not be performed. For example, the operation of the second heat exchange unit 52 may be controlled to start heating the first non-permeate fluid F2 based on the difference between the temperature of the first non-permeate fluid F2 measured by the second temperature sensor 62 and the second predetermined range.

[0052] The membrane separation system of the first embodiment may further include a heating device that heats at least one selected from the group consisting of a feed fluid, a non-permeate fluid, and at least one membrane separation unit.

[0053] The membrane separation system 100A includes a heating device 57 as a heating device. The heating device 57 heats the first non-permeate fluid F2 discharged from the first membrane separation unit 10. For example, when the temperature of the first non-permeate fluid F2 is insufficient to satisfy the second predetermined range, the heating device 57 can be used as an auxiliary. This makes it possible to increase the temperature of the first non-permeate fluid F2 supplied to the filtration separation unit 40.

[0054] As shown in Fig. 1, the heating device 57 may be provided on the downstream side of the second heat exchange unit 52. The heating device 57 may be directly connected to the second heat exchange unit 52. As the heating device 57, for example, a heater or the like can be used.

[0055] For example, the heating device 57 heats the temperature of the first impermeable fluid F2 supplied to the filtration separation unit 40 to a range of 25°C to 60°C. The heating device 57 may heat the temperature of the first impermeable fluid F2 supplied to the filtration separation unit 40 to a range of 30°C to 45°C, or to a range of 35°C to 40°C. In other words, the heating device 57 heats the temperature of the first impermeable fluid F2 to satisfy a second predetermined range.

[0056] In the membrane separation system of the first embodiment, if, after (ii) above is performed, at least one temperature selected from the group consisting of the second heat transfer medium, the supply fluid, the impermeable fluid, and at least one membrane separation unit does not satisfy the second predetermined range, the operation of the heating device may be controlled to satisfy the second predetermined range.

[0057] In the membrane separation system 100A, if the temperature of the first impermeable fluid F2 does not meet the second predetermined range after (ii) above has been performed, the operation of the heating device 57 may be controlled to meet the second predetermined range. This makes it possible to stably maintain the temperature of the first impermeable fluid F2 supplied to the filtration separation unit 40.

[0058] The membrane separation system of the first embodiment may further include a cooling device for cooling the first heat transfer medium.

[0059] The membrane separation system 100A includes a cooling device 56. The cooling device 56 cools the first heat transfer medium M1 discharged from the heat pump 71. For example, the cooling device 56 can be used auxiliaryly when the temperature of the first permeate fluid F1 is insufficient to meet a first predetermined range. This makes it possible to stably maintain the temperature of the first heat transfer medium M1 supplied to the condensing section 41.

[0060] As shown in Figure 1, the cooling device 56 may be located upstream of the condensing unit 41. The cooling device 56 may also be directly connected to the condensing unit 41. For example, a chiller can be used as the cooling device 56.

[0061] For example, the cooling device 56 cools the temperature of the first heat medium M1 discharged from the heat pump 71 to a range of -80°C to 30°C. The condensing unit 41 may cool the temperature of the first heat medium M1 discharged from the heat pump 71 to a range of -20°C to 20°C, or to a range of -10°C to 10°C. In other words, the cooling device 56 cools the temperature of the first heat medium M1 to satisfy a first predetermined range.

[0062] In the membrane separation system of the first embodiment, if, after (i) above is performed, at least one temperature selected from the group consisting of the first heat transfer medium and the permeate fluid does not meet the first predetermined range, the operation of the cooling device may be controlled to meet the first predetermined range.

[0063] In the membrane separation system 100A, if the temperature of the first heat medium M does not meet the first predetermined range after (i) is performed, the operation of the cooling device 56 may be controlled to meet the first predetermined range. This makes it possible to stably maintain the temperature of the first heat medium M1 supplied to the condensing unit 41.

[0064] The membrane separation system 100A may further include a heating device 58. The heating device 58 heats the raw fluid F0 supplied to the first membrane separation unit 10. For example, if the temperature of the raw fluid F0 is low, the temperature of the raw fluid F0 supplied to the first membrane separation unit 10 can be increased by using the heating device 58 as an auxiliary device. For example, a heater can be used as the heating device 58.

[0065] For example, the heating device 58 heats the temperature of the raw fluid F0 supplied to the first membrane separation unit 10 to a range of 25°C to 60°C. The heating device 58 may heat the temperature of the raw fluid F0 supplied to the first membrane separation unit 10 to a range of 30°C to 45°C, or to a range of 35°C to 40°C.

[0066] The membrane separation system 100A may further include a second temperature sensor 63, which is provided downstream of the heating device 57. The second temperature sensor 63 measures the temperature of the first impermeable fluid F2 after it has been heated by the heating device 57. With this configuration, the operation of the heating device 57 can be controlled based on the monitoring results from the second temperature sensor 62 and the second temperature sensor 63. This makes it possible to maintain the temperature of the first impermeable fluid F2 supplied to the filtration separation unit 40 more stably.

[0067] The membrane separation system 100A may further include a second temperature sensor 61, which is provided downstream of the heating device 58. The second temperature sensor 61 measures the temperature of the raw fluid F0 after it has been heated by the heating device 58. With this configuration, the operation of the heating device 58 can be controlled based on the monitoring results from the second temperature sensor 61. This makes it possible to stably maintain the temperature of the raw fluid F0 supplied to the first membrane separation unit 10.

[0068] The membrane separation system 100A may further include a first temperature sensor 65 located downstream of the cooling device 56. The first temperature sensor 65 measures the temperature of the first heat medium M1 after it has been cooled by the cooling device 56. With this configuration, the operation of the cooling device 56 can be controlled based on the monitoring results from the first temperature sensors 64 and 65. This makes it possible to maintain the temperature of the first heat medium M1 supplied to the condensing unit 41 more stably.

[0069] The membrane separation system of the first embodiment may further include a depressurization unit that reduces the pressure within the permeable space of the membrane separation unit.

[0070] The membrane separation system 100A includes a depressurization section 42. The depressurization section 42 reduces the pressure within the permeate space of the first membrane separation section 10.

[0071] In the membrane separation system of the first embodiment, the depressurization section includes a vacuum device such as a vacuum pump. The depressurization section may also be a vacuum pump. The vacuum pump is typically a gas transport type vacuum pump, and examples include reciprocating vacuum pumps and rotary vacuum pumps. Examples of reciprocating vacuum pumps include diaphragm type and oscillating piston type vacuum pumps. Examples of rotary vacuum pumps include liquid-sealed pumps, oil rotary pumps (rotary pumps), mechanical booster pumps, and various dry pumps such as Roots type, claw type, screw type, turbo type, and scroll type. The pump as the depressurization section may be equipped with a variable speed mechanism for changing the rotational speed, etc. An example of a variable speed mechanism is an inverter that drives the motor of the pump. By controlling the rotational speed of the pump with the variable speed mechanism, the pressure in the permeable space of the membrane separation section can be appropriately adjusted.

[0072] In the membrane separation system 100A, the depressurization unit 42 may be a multi-stage Roots type vacuum pump or a diaphragm type vacuum pump. A multi-stage Roots type vacuum pump can, for example, raise the pressure in the space to a predetermined value in a short time and provide excellent durability. A diaphragm type vacuum pump can, for example, perform depressurization operations efficiently and at low cost.

[0073] In the example shown in Figure 1, one depressurization unit 42 is connected to the first membrane separation unit 10. However, the number of depressurization units is not limited to one. Two or more depressurization units may be connected to the first membrane separation unit 10.

[0074] As shown in Figure 1, the condensation section 41 may be provided upstream of the pressure reduction section 42. For example, if the raw fluid F0 is a solution containing a volatile organic compound, the permeate fluid may contain alcohol. If the permeate fluid containing alcohol gas flows directly into the pressure reduction section 42, the gas may condense within the pressure reduction section 42, generating liquid. The liquid generated within the pressure reduction section 42 may impair the function of the pressure reduction section 42. By providing the condensation section 41 upstream of the pressure reduction section 42, such problems can be avoided.

[0075] As shown in Figure 1, the condensing unit 41 may be connected to a recovery unit 75 for recovering the permeate fluid of the liquid obtained by condensation. The recovery unit 75 is, for example, a tank for storing the permeate fluid. If the raw fluid F0 is a solution containing volatile organic compounds, a concentration sensor for measuring the content of organic compounds in the condensed permeate fluid may be placed in the path connecting the condensing unit 41 and the recovery unit 75.

[0076] The membrane separation system of the first embodiment may further include a supply unit for storing the raw fluid.

[0077] The membrane separation system 100A includes a supply unit 60. The supply unit 60 stores the raw fluid F0 to be supplied to the first membrane separation unit 10. The supply unit 60 is, for example, a tank for storing the raw fluid F0. As will be described in the second embodiment later, the supply unit 60 may also be a culture tank for producing organic compounds by fermentation of a carbon source by microorganisms.

[0078] The membrane separation system of the first embodiment may further include a first circulation path for circulating a first heat medium between a heat pump and a condensing unit, and a second circulation path for circulating a second heat medium between a heat pump and a heat exchange unit.

[0079] The membrane separation system 100A includes a first circulation path 81 as a first circulation path and a second circulation path 82 as a second circulation path. The first circulation path 81 is a closed path that guides the first heat medium M1 cooled by the heat pump 71 to the condensation section 41 and the first heat medium M1, which has been heated by heat exchange with the first permeable fluid F1 in the condensation section 41, back to the heat pump 71. The second circulation path 82 is a closed path that guides the second heat medium M2, which has been heated by the heat pump 71, to the second heat exchange section 52 and the second heat medium M2, which has been cooled by heat exchange with the first impermeable fluid F2 in the second heat exchange section 52, back to the heat pump 71. A pump for controlling the flow rate of the first heat medium M1 may be provided in the first circulation path 81. A pump for controlling the flow rate of the second heat medium M2 may be provided in the second circulation path 82.

[0080] As shown in Figure 1, in the membrane separation system 100A, the first temperature sensor 64, the cooling device 56, and the first temperature sensor 65 are provided on the first circulation path 81.

[0081] The membrane separation system 100A further includes a source fluid path 91, a first permeable fluid path 92, and a first impermeable fluid path 93 as fluid pathways.

[0082] The raw fluid path 91 connects the raw fluid outlet 60b of the supply unit 60 and the raw fluid inlet 10a of the first membrane separation unit 10, and is a path that guides the raw fluid F0 from the supply unit 60 to the first membrane separation unit 10. A pump for controlling the flow rate of the raw fluid F0 may be placed in the raw fluid path 91. If the raw fluid F0 is a solution containing volatile organic compounds, a concentration sensor for measuring the content of organic compounds in the raw fluid F0 may be placed in the raw fluid path 91.

[0083] As shown in Figure 1, in the membrane separation system 100A, the heating device 58 and the second temperature sensor 61 are located on the raw fluid path 91.

[0084] The first permeable fluid path 92 connects the first permeable fluid outlet 10b of the first membrane separation unit 10 and the first permeable fluid inlet of the condensation unit 41, and is a path that guides the first permeable fluid F1 from the first membrane separation unit 10 to the condensation unit 41. If the raw fluid F0 is a solution containing a volatile organic compound, a concentration sensor for measuring the content of the organic compound in the first permeable fluid F1 may be placed in the first permeable fluid path 92.

[0085] The first impermeable fluid path 93 connects the first impermeable fluid outlet 10c of the first membrane separation unit 10 to the impermeable fluid inlet of the filtration separation unit 40, and is a path that guides the first impermeable fluid F2 from the first membrane separation unit 10 to the filtration separation unit 40. If the raw fluid F0 is a solution containing a volatile organic compound, a concentration sensor for measuring the content of the organic compound in the first impermeable fluid F2 may be placed in the first impermeable fluid path 93.

[0086] As shown in Figure 1, in the membrane separation system 100A, the second heat exchange unit 52, the second temperature sensor 62, the heating device 57, and the second temperature sensor 63 are provided on the first impermeable fluid path 93.

[0087] The membrane separation system of the first embodiment may further include a control unit that controls each component of the membrane separation system. The control unit is, for example, a DSP (Digital Signal Processor) that includes an A / D conversion circuit, input / output circuits, arithmetic circuits, and a memory device. The control unit stores a program for properly operating the membrane separation system.

[0088] The membrane separation system 100A includes a control unit 70 as a control unit, which controls each component of the membrane separation system 100A. For example, the control unit 70 controls the operation of the heat pump 71, heating device 57, cooling device 56, condensing unit 41, second heat exchange unit 52, etc. As a result, the first impermeable fluid F2 discharged from the first membrane separation unit 10 is efficiently heated. Also, the first permeable fluid F1 discharged from the first membrane separation unit 10 is efficiently cooled.

[0089] Each of the pathways in the membrane separation system of this embodiment consists of, for example, metal or resin piping, unless otherwise specified.

[0090] In the first embodiment, the raw fluid F0 supplied to the first membrane separation unit 10 may be a liquid or a gas. An example of a liquid raw fluid F0 is a solution containing a volatile organic compound. An example of a gaseous raw fluid F0 is a mixed gas containing an acidic gas, particularly a mixed gas containing carbon dioxide and nitrogen.

[0091] The raw fluid F0 is typically a solution containing a volatile organic compound (hereinafter sometimes referred to as organic compound C). Organic compound C is not particularly limited as long as it is volatile. In this specification, "volatile organic compound" means, for example, an organic compound whose boiling point at atmospheric pressure (101.325 kPa) is between 20°C and 260°C.

[0092] The number of carbon atoms in organic compound C is not particularly limited and may be, for example, 10 or less, 8 or less, 6 or less, or even 4 or less. The lower limit of the number of carbon atoms in organic compound C may be 1 or 2. Organic compound C has functional groups containing oxygen atoms, such as hydroxyl groups, carbonyl groups, ether groups, and ester groups. In organic compound C, the number of functional groups containing oxygen atoms is typically one.

[0093] Examples of organic compound C include alcohols, ketones, and esters, and are typically alcohols. The alcohol may be an alkyl alcohol composed only of an alkyl group and a hydroxyl group, or an aryl alcohol containing an aryl group and a hydroxyl group. The alkyl alcohol may be linear, branched, or cyclic. Examples of alkyl alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, isobutanol, t-butanol, and n-pentanol. Examples of aryl alcohols include phenol.

[0094] The ketone may be a dialkylketone composed only of an alkyl group and a carbonyl group. Examples of dialkylketones include methyl ethyl ketone (MEK) and acetone.

[0095] The ester may be a fatty acid alkyl ester composed solely of an alkyl group and an ester group. Examples of fatty acid alkyl esters include ethyl acetate.

[0096] Note that organic compound C is not limited to those described above. Organic compound C may also be an aromatic hydrocarbon such as benzene, toluene, or xylene.

[0097] The raw fluid F0 may contain one type of organic compound C, or it may contain two or more types of organic compound C. The content of organic compound C in the raw fluid F0 is, for example, 0.5 wt% or more, and may be 1 wt% or more, 2 wt% or more, or even 5 wt% or more. The upper limit of the content of organic compound C is not particularly limited, but is, for example, 50 wt%.

[0098] Organic compound C may be a fermented product produced by microorganisms fermenting a carbon source, or it may be alcohol produced by microorganisms (bio-alcohol). In other words, the raw fluid F0 may be a fermentation liquid containing organic compound C as a fermentation product. However, the raw fluid F0 is not limited to a fermentation liquid, but may also be waste liquid or wastewater discharged from a chemical plant or the like.

[0099] The raw fluid F0 may further contain other components besides water and organic compound C, such as microorganisms that produce fermentation products, a carbon source, a nitrogen source, and inorganic ions. The microorganisms that produce fermentation products are typically bacteria. Examples of carbon sources include polysaccharides such as starch and monosaccharides such as glucose.

[0100] Next, the first membrane separation unit 10 of the membrane separation system 100A will be described further.

[0101] [Membrane Separation Section] Figure 2 is a schematic cross-sectional view showing an example of the first membrane separation section 10. The first membrane separation section 10 comprises a first separation membrane 11 and a container 12. The container 12 has a first chamber 13 and a second chamber 14. The first chamber 13 functions as a supply space to which the raw fluid F0 is supplied. The second chamber 14 functions as a permeation space to which the first permeate fluid F1 is supplied. The first permeate fluid F1 is obtained by the raw fluid F0 permeating through the first separation membrane 11.

[0102] The first separation membrane 11 is located inside the container 12. Inside the container 12, the first separation membrane 11 separates the first chamber 13 and the second chamber 14. The first separation membrane 11 extends from one of a pair of walls of the container 12 to the other.

[0103] The first chamber 13 has a raw fluid inlet 10a and a first impermeable fluid outlet 10c. The second chamber 14 has a first permeable fluid outlet 10b. The raw fluid inlet 10a is an opening for supplying the raw fluid F0 to the supply space (first chamber 13). The first permeable fluid outlet 10b is an opening for discharging the first permeable fluid F1 from the permeation space (second chamber 14). The first impermeable fluid outlet 10c is an opening for discharging the raw fluid F0 (first impermeable fluid F2) that did not permeate the first separation membrane 11 from the supply space (first chamber 13). The raw fluid inlet 10a, the first permeable fluid outlet 10b, and the first impermeable fluid outlet 10c are each formed, for example, on the wall surface of the container 12.

[0104] The first membrane separation unit 10 is suitable for a continuous flow membrane separation method. However, the first membrane separation unit 10 may also be used in a batch membrane separation method.

[0105] [Separation Membrane] The first separation membrane 11 of the first membrane separation unit 10 is not particularly limited as long as it can separate the supply fluid into a permeable fluid and an impermeable fluid. For example, a permeation vaporization membrane, a reverse osmosis membrane, an ultrafiltration membrane, etc., can be used as the first separation membrane 11.

[0106] The first separation membrane 11 may be a permeable vaporization membrane that separates the raw fluid F0 into a first permeable fluid F1 and a first impermeable fluid F2.

[0107] When the raw fluid F0 is a solution containing a volatile organic compound, the first separation membrane 11 is preferably a permeable vaporization membrane.

[0108] Figure 3 is a schematic cross-sectional view showing an example of a first separation membrane 11 in the first membrane separation unit 10. The first separation membrane 11 comprises, for example, a separation functional layer 1 and a porous support 2 that supports the separation functional layer 1. The separation functional layer 1 is, for example, in direct contact with the porous support 2. The first separation membrane 11 has, for example, a main surface 11a on the separation functional layer 1 side exposed to the supply space and a main surface 11b on the porous support 2 side exposed to the permeation space.

[0109] If the first separation membrane 11 is a permeation vaporization membrane, the first separation membrane 11 may further include a protective layer (not shown) that protects the separation functional layer 1.

[0110] (Separation Functional Layer) The separation functional layer 1 is a layer that can preferentially permeate specific components contained in the raw fluid F0. If the raw fluid F0 is a solution containing organic compound C, the separation functional layer 1 is, for example, a layer that can preferentially permeate organic compound C contained in the solution.

[0111] If the separation functional layer 1 is a layer that can preferentially allow organic compound C contained in a solution containing organic compound C to pass through, it is preferable that the separation functional layer 1 contains a hydrophobic material. In this specification, "hydrophobic material" means, for example, a material in which, when a 10 μL drop of water (at a temperature of 25°C) is dropped onto the surface of a test piece made of the material, the static contact angle of water exceeds 90°. The static contact angle of water can be measured using a commercially available contact angle meter.

[0112] Examples of hydrophobic materials include compounds having siloxane bonds (Si-O-Si bonds), olefin polymers, oils, and fluorinated compounds. The separation functional layer 1 preferably contains a compound having siloxane bonds as a hydrophobic material. Compounds having siloxane bonds are typically silicone polymers. Silicone polymers may be solid or liquid at 25°C. Specific examples of silicone polymers include polydimethylsiloxane (PDMS). Specific examples of olefin polymers include polyethylene and polypropylene. Examples of oils include hydrocarbon oils such as liquid paraffin. Examples of fluorinated compounds include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). Hydrophobic materials can be used individually or in combination of two or more.

[0113] The separation functional layer 1 may contain a hydrophobic material as its main component, or may be composed substantially only of a hydrophobic material. "Main component" means the component that is present in the largest amount by weight in the separation functional layer 1.

[0114] The separation functional layer 1 may include a matrix containing a hydrophobic material and fillers dispersed in the matrix. The fillers are embedded within the matrix. Within the matrix, all fillers may be spaced apart from each other or partially aggregated.

[0115] The filler includes, for example, inorganic materials such as zeolite, silica, and bentonite. The zeolite included in the filler is preferably high-silica zeolite, which has a high silica-to-alumina ratio. High-silica zeolite is suitable for separating solutions containing organic compound C due to its excellent hydrolysis resistance. Examples of high-silica zeolite include HSZ (registered trademark) from Tosoh Corporation, HiSiv (registered trademark) from Union Showa Co., Ltd., USKY from Union Showa Co., Ltd., and Zeoal (registered trademark) from Nakamura Choko Co., Ltd.

[0116] The filler may contain a metal-organic framework (MOF). The metal-organic framework is also called a porous coordination polymer (PCP). The metal-organic framework is preferably hydrophobic. The metal-organic framework contains, for example, a metal ion and an organic ligand. Examples of metal ions include Zn ions. Examples of organic ligands include aromatic rings. Examples of aromatic rings included in the organic ligand include imidazole rings. Examples of organic ligands include 2-methylimidazole. A specific example of a metal-organic framework is ZIF-8.

[0117] The shape of the filler is, for example, particulate. In this specification, "particulate" includes spherical, ellipsoidal, flaky, and fibrous. The average particle size of the filler is not particularly limited, but is, for example, 50 μm or less, preferably 20 μm or less, and more preferably 10 μm or less. The lower limit of the average particle size of the filler is, for example, 0.01 μm. The average particle size of the filler can be determined, for example, by the following method: First, a cross-section of the separation functional layer 1 is observed with a transmission electron microscope. In the obtained electron microscope image, the area of ​​a specific filler is calculated by image processing. The diameter of a circle having the same area as the calculated area is considered to be the particle size (diameter of the particle) of that specific filler. The particle sizes of any number (at least 50) of fillers are calculated, and the average of the calculated values ​​is considered to be the average particle size of the filler.

[0118] The filler content in the separation functional layer 1 is, for example, 10 wt% or more, preferably 30 wt% or more, and more preferably 40 wt% or more. The upper limit of the filler content in the separation functional layer 1 is not particularly limited, but is, for example, 70 wt%. The matrix content in the separation functional layer 1 is not particularly limited, but is, for example, 30 wt% to 90 wt%.

[0119] If the separation functional layer 1 is a layer that can preferentially permeate organic compound C contained in a solution containing organic compound C, the thickness of the separation functional layer 1 is, for example, 200 μm or less, preferably 100 μm or less, and more preferably 80 μm or less. The thickness of the separation functional layer 1 may be 1.0 μm or more, 10 μm or more, or 30 μm or more.

[0120] If the separation functional layer 1 is a layer that can preferentially permeate organic compound C contained in a solution containing organic compound C, the separation functional layer 1 may have a microporous structure with an average pore size of less than 0.01 μm, but it may also be a dense layer without pores on its surface.

[0121] (Porous support) Examples of porous support 2 include nonwoven fabrics; porous polytetrafluoroethylenes; aromatic polyamide fibers; porous metals; sintered metals; porous ceramics; porous polyesters; porous nylons; activated carbon fibers; latex; silicones; silicone rubbers; permeable (porous) polymers containing at least one selected from the group consisting of polyvinyl fluoride, polyvinylidene fluoride, polyurethane, polypropylene, polyethylene, polystyrene, polycarbonate, polysulfone, polyetheretherketone, polyacrylonitrile, polyimide, and polyphenylene oxide; metal foams having open or closed cells; polymer foams having open or closed cells; silica; porous glass; mesh screens, etc. The porous support 2 may be a combination of two or more of these.

[0122] The porous support 2 has an average pore diameter of, for example, 0.01 to 0.4 μm. The thickness of the porous support 2 is not particularly limited, but is, for example, 10 μm or more, preferably 50 μm or more, and more preferably 100 μm or more. The thickness of the porous support 2 is, for example, 300 μm or less, and preferably 200 μm or less.

[0123] (Protective layer) The protective layer covers the surface of the separation functional layer 1, for example. The material of the protective layer is not particularly limited, and examples include silicone resin. The material of the protective layer may be the same as or different from the material of the matrix of the separation functional layer 1.

[0124] The thickness of the protective layer is not particularly limited, but is, for example, 0.5 μm or more, preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The thickness of the protective layer is, for example, 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less.

[0125] (Method for preparing a permeable vaporization membrane) A permeable vaporization membrane can be prepared, for example, by forming a separation functional layer 1 on a porous support 2. Specifically, first, a coating solution containing the material for the separation functional layer 1 is prepared. The coating solution may contain a filler along with a dispersant for dispersing the filler in the coating solution. If the coating solution contains a compound having a siloxane bond, the coating solution may further contain a catalyst for curing the compound. Next, a coating film is obtained by applying the coating solution onto the porous support 2. The separation functional layer 1 is formed by drying the coating film.

[0126] <Embodiment of Operating Method for Membrane Separation System> The operating method for the membrane separation system of this embodiment includes, for example, separating the supply fluid into a permeable fluid and an impermeable fluid in at least one membrane separation unit; recovering heat from a first heat medium and transferring it to a second heat medium using a heat pump; cooling and condensing the permeable fluid using the first heat medium in a condensing unit; and heating at least one selected from the group consisting of the supply fluid, the impermeable fluid, and at least one membrane separation unit using the second heat medium in a heat exchange unit. According to this operating method, the efficiency of thermal energy utilization in the membrane separation system can be improved.

[0127] Next, an example of the operation method of the membrane separation system 100A described above will be explained with reference to Figure 1. The operation method of the membrane separation system 100A includes, for example, separating the raw fluid F0 into a first permeable fluid F1 and a first impermeable fluid F2 in the first membrane separation unit 10 (step 1-1), and recovering heat from the first heat medium M1 and transferring it to the second heat medium M2 using the heat pump 71 (step 2). Furthermore, the operation method includes cooling and condensing the first permeable fluid F1 using the first heat medium M1 in the condensation unit 41 (step 3), and heating the first impermeable fluid F2 using the second heat medium M2 in the second heat exchange unit 52 (step 4-1).

[0128] According to the operating method of the membrane separation system 100A, heat recovered from the first permeate fluid F1 via the condensation unit 41 can be supplied to the first impermeable fluid F2. Therefore, it is possible to efficiently heat the first impermeable fluid F2 supplied to the filtration separation unit 40. In addition, the condensation unit 41 makes it possible to efficiently cool the first permeate fluid F1 discharged from the first membrane separation unit 10. As a result, the efficiency of thermal energy utilization in the membrane separation system 100A can be improved.

[0129] [Modifications of the Membrane Separation Section] The membrane separation section of the membrane separation system of the first embodiment may be a spiral-type membrane element, a hollow fiber membrane element, a disc-tube type membrane element in which multiple permeation vaporization membranes are stacked, a plate-and-frame type membrane element, etc. Figure 4 is a schematic exploded perspective view showing another example of the membrane separation section. The membrane separation section may be a spiral-type membrane element as shown in Figure 4.

[0130] In the following section, we will further explain the case where the first membrane separation unit 10 of the membrane separation system 100A described above is a spiral-type membrane element, using Figure 4 as an example.

[0131] The first membrane separation unit 10 (membrane element) shown in Figure 4 comprises a central tube 16 and a membrane leaf 19 having a first separation membrane 11 and wrapped around the central tube 16.

[0132] The central tube 16 has a cylindrical shape. Through holes 16h are formed on the surface of the central tube 16 to allow the raw fluid F0 to flow into the interior of the central tube 16. The number of through holes 16h is not particularly limited and may be one or two or more. Examples of materials for the central tube 16 include resins such as acrylonitrile butadiene styrene copolymer resin (ABS resin), polyphenylene ether resin (PPE resin), and polysulfone resin (PSF resin); and metals such as stainless steel and titanium. The inner diameter of the central tube 16 is, for example, in the range of 20 to 100 mm.

[0133] The first membrane separation unit 10 has a plurality of membrane leaves 19. Each membrane leaf 19 includes a first separation membrane 11 and a permeate-side flow channel material 17. For example, a membrane leaf 19 has two first separation membranes 11. The two first separation membranes 11 are overlapped and sealed on three sides to form a bag-like structure. The permeate-side flow channel material 17 is positioned between the two first separation membranes 11 so as to be located inside the bag-like structure. The permeate-side flow channel material 17 secures a space (permeate space) between the two first separation membranes 11 as a flow channel for the first permeable fluid F1. In this way, the permeate-side flow channel material 17 is used in combination with the first separation membrane 11. The number of membrane leaves 19 is not particularly limited and can be, for example, 2 to 30.

[0134] The first membrane separation unit 10 further includes a supply-side flow channel material 18. The supply-side flow channel material 18 is located outside the bag-like structure described above and is stacked on the membrane leaves 19. More specifically, multiple supply-side flow channel materials 18 and multiple membrane leaves 19 are stacked alternately. The supply-side flow channel material 18 secures a space (supply space) between the membrane leaves 19 that serves as a flow channel for the raw fluid F0.

[0135] For the supply-side channel material 18 and the permeate-side channel material 17, for example, a net, woven fabric, or knitted fabric made of a resin such as polyethylene, polypropylene, polyethylene terephthalate (PET), polyphenylene sulfide (PPS), or ethylene-chlorotrifluoroethylene copolymer (ECTFE) can be used.

[0136] The outer surface of the membrane element is composed of a shell (not shown) made of a material that prevents fluid from passing through. The shell may be made of fiber-reinforced plastic (FRP). The membrane element may be housed in a casing (not shown).

[0137] The first membrane separation unit 10 (membrane element) shown in Figure 4 can be operated, for example, in the following way. First, the raw fluid F0 is supplied to one end of the wound membrane leaf 19. The space inside the central tube 16 is depressurized. Depressurization can be performed by the depressurization unit 42. As a result, the first permeate fluid F1 that has permeated through the first separation membrane 11 of the membrane leaf 19 moves into the central tube 16. The first permeate fluid F1 is discharged to the outside through the central tube 16. The raw fluid F0 (first non-permeate fluid F2) processed in the first membrane separation unit 10 is discharged to the outside from the other end of the wound membrane leaf 19.

[0138] <Modifications of the Membrane Separation System> The membrane separation system of the first embodiment is not limited to the membrane separation system 100A shown in Figure 1. Hereinafter, modifications 1 to 6 of the membrane separation system of the first embodiment will be described with reference to Figures 5 to 10. In the following, elements common to the membrane separation system 100A described above will be given the same reference numerals, and detailed explanations will be omitted.

[0139] [Modification 1 of the Membrane Separation System] Figure 5 is a schematic diagram showing modification 1 of the membrane separation system of the first embodiment. The membrane separation system 100B of modification 1 shown in Figure 5 is equipped with a first heat exchange unit 51 instead of a second heat exchange unit 52. The first heat exchange unit 51 heats the raw fluid F0, which is supplied as a supply fluid to the first membrane separation unit 10, using a second heat transfer medium M2. Except for this, the membrane separation system 100B has basically the same configuration as the membrane separation system 100A (Figure 1) described above.

[0140] According to the membrane separation system 100B, the heat recovered from the first permeate fluid F1 via the condensation unit 41 can be supplied to the raw fluid F0. Therefore, it becomes possible to efficiently heat the raw fluid F0 supplied to the first membrane separation unit 10.

[0141] As shown in Figure 5, in the membrane separation system 100B, the first heat exchange unit 51 and the second temperature sensor 61 are located on the raw fluid path 91. In the membrane separation system 100B, the second temperature sensor 61 is located downstream of the first heat exchange unit 51 and measures the temperature of the raw fluid F0 after it has been heated by the first heat exchange unit 51.

[0142] Although not shown in the diagram, the membrane separation system 100B may also include a heating device 58 for heating the raw fluid F0 supplied to the first membrane separation unit 10.

[0143] The operating method of the membrane separation system 100B is the same as the operating method of the membrane separation system 100A (Figure 1) described above, but instead of heating the first impermeable fluid F2 using the second heat medium M2 with the second heat exchange unit 52 (step 4-1), the original fluid F0 is heated using the second heat medium M2 with the first heat exchange unit 51 (step 4-2).

[0144] [Modified Membrane Separation System 2] Figure 6 is a schematic diagram showing modified membrane separation system 2 of the first embodiment. The membrane separation system 100C of modified membrane separation system 2 shown in Figure 6 is equipped with a third heat exchange unit 53 instead of the second heat exchange unit 52. The third heat exchange unit 53 heats the first membrane separation unit 10 using the second heat transfer medium M2. Except for this, the membrane separation system 100C has basically the same configuration as the membrane separation system 100A (Figure 1) described above.

[0145] According to the membrane separation system 100C, the heat recovered from the first permeate fluid F1 via the condensation unit 41 can be supplied to the first membrane separation unit 10. This makes it possible to heat the first membrane separation unit 10, so that the first impermeable fluid F2 discharged from the first membrane separation unit 10 is efficiently heated.

[0146] The configuration of the third heat exchange unit 53 is not particularly limited, as long as it can heat the first membrane separation unit 10. The third heat exchange unit 53 may, for example, have a container provided so as to surround the first membrane separation unit 10. The first membrane separation unit 10 may be heated by flowing the second heat transfer medium M2 into the space between the outer periphery of the first membrane separation unit 10 and the inner periphery of the container.

[0147] Although not shown in the diagram, the membrane separation system 100C may also include a second temperature sensor, which measures the temperature of the first membrane separation unit 10.

[0148] Although not shown in the diagram, the membrane separation system 100C may include a heating device for heating the first membrane separation unit 10.

[0149] The operating method of the membrane separation system 100C is the same as the operating method of the membrane separation system 100A (Figure 1) described above, but instead of heating the first impermeable fluid F2 using the second heat medium M2 with the second heat exchange unit 52 (step 4-1), the third heat exchange unit 53 heats the first membrane separation unit 10 using the second heat medium M2 (step 4-3).

[0150] [Modification 3 of the Membrane Separation System] Figure 7 is a schematic diagram showing modification 3 of the membrane separation system of the first embodiment. The membrane separation system 100D of modification 3 shown in Figure 7 includes a first heat exchange unit 51 in addition to the second heat exchange unit 52. The first heat exchange unit 51 heats the raw fluid F0, which is supplied as a supply fluid to the first membrane separation unit 10, using a second heat transfer medium M2. In the membrane separation system 100D, the second heat transfer medium M2 is supplied from the downstream side to the upstream side, that is, in the order of the second heat exchange unit 52 and the first heat exchange unit 51, so that the second heat transfer medium M2 is supplied in that order. The second heat exchange unit 52 and the first heat exchange unit 51 are connected in series by a second circulation path 82. Except for this, the membrane separation system 100D has basically the same configuration as the membrane separation system 100A (Figure 1) described above.

[0151] In the membrane separation system 100D, the temperature of the second heat medium M2 supplied to the first heat exchange section 51 is lower than the temperature of the second heat medium M2 supplied to the second heat exchange section 52. As described above, the temperature of the impermeable fluid discharged from the membrane separation section is lower than the temperature of the supply fluid supplied to the membrane separation section. In the membrane separation system 100D, the temperature of the second heat medium M2 supplied to the heat exchange section decreases from the downstream side to the upstream side, so the heat recovered from the first permeable fluid F1 via the condensation section 41 can be utilized more efficiently.

[0152] The membrane separation system 100D includes a first condensation section 41a and a second condensation section 41b connected in series downstream of the first condensation section 41a. The second condensation section 41b, for example, further cools and condenses the permeate fluid sent from the first condensation section 41a. With this configuration, the concentration of the liquid permeate fluid obtained in the downstream second condensation section 41b can be increased. The condensation temperature of the second condensation section 41b may be the same as or different from that of the first condensation section 41a.

[0153] In the membrane separation system 100D, the second condenser 41b and the first condenser 41a are connected in series by a first circulation path 81 so that the first heat transfer medium M1 is supplied from downstream to upstream, that is, in the order of the second condenser 41b and the first condenser 41a. With this configuration, heat can be efficiently recovered from the permeate fluid via the first condenser 41a and the second condenser 41b.

[0154] The membrane separation system 100D includes two condensation sections (first condensation section 41a, second condensation section 41b) as condensation sections. However, the membrane separation system 100D may include three or more condensation sections.

[0155] As shown in Figure 7, the first condensing section 41a and the second condensing section 41b may be connected to a first recovery section 75a and a second recovery section 75b, respectively, for recovering the permeate fluid of the liquid obtained by condensation. The first recovery section 75a and the second recovery section 75b are, for example, tanks for storing the permeate fluid of the liquid. If the raw fluid F0 is a solution containing a volatile organic compound, concentration sensors for measuring the content of the organic compound in the condensed permeate fluid may be placed in the path connecting the first condensing section 41a and the first recovery section 75a, and in the path connecting the second condensing section 41b and the second recovery section 75b.

[0156] Although not shown in the diagram, the membrane separation system 100D may also include a heating device 58 for heating the raw fluid F0 supplied to the first membrane separation unit 10.

[0157] The operating method of the membrane separation system 100D is the same as the operating method of the membrane separation system 100A (Figure 1) described above, but includes heating the first impermeable fluid F2 using the second heat medium M2 by the second heat exchange unit 52 (step 4-1), and also includes heating the raw fluid F0 using the second heat medium M2 by the first heat exchange unit 51 (step 4-2).

[0158] [Modification 4 of the Membrane Separation System] Figure 8 is a schematic diagram showing modification 4 of the membrane separation system of the first embodiment. In the membrane separation system 100E of modification 4 shown in Figure 8, the second heat exchange unit 52 and the first heat exchange unit 51 are connected in parallel by a second circulation path 82 so that the second heat medium M2 is supplied to the second heat exchange unit 52 and the first heat exchange unit 51, respectively. Except for this, the membrane separation system 100E has basically the same configuration as the membrane separation system 100D of modification 3 (Figure 7) described above.

[0159] According to the membrane separation system 100E, the heat recovered from the first permeate fluid F1 via the condensation unit 41 can be efficiently utilized.

[0160] In the membrane separation system 100E, the second circulation path 82 has a first portion 821 and a second portion 822. The first portion 821 is the portion that guides the second heat medium M2 to the first heat exchange section 51. The second portion 822 is the portion that guides the second heat medium M2 to the second heat exchange section 52. The second portion 822 branches off from the first portion 821 at the branching position 82q. The first portion 821 and the second portion 822 merge at the confluence position 82p.

[0161] As shown in Figure 8, the first section 821 and the second section 822 may be provided with a first flow control valve 451 and a second flow control valve 452, respectively. With this configuration, the flow rate of the second heat medium M2 supplied to the first heat exchange section 51 and the second heat exchange section 52 can be controlled by adjusting the opening of the first flow control valve 451 and the opening of the second flow control valve 452, respectively.

[0162] In the membrane separation system 100E, the second condensation section 41b and the first condensation section 41a are connected in parallel by a first circulation path 81 so that the first heat transfer medium M1 is supplied to each of the second condensation section 41b and the first condensation section 41a, respectively. With this configuration, heat can be efficiently recovered from the permeate fluid via the first condensation section 41a and the second condensation section 41b.

[0163] In the membrane separation system 100E, the first circulation path 81 has a first portion 811 and a second portion 812. The first portion 811 is the portion that guides the first heat medium M1 to the first condensation section 41a. The second portion 812 is the portion that guides the first heat medium M1 to the second condensation section 41b. The second portion 812 branches off from the first portion 811 at the branching position 81q. The first portion 811 and the second portion 812 merge at the confluence position 81p.

[0164] As shown in Figure 8, the first portion 811 and the second portion 812 may be provided with a first flow control valve 461 and a second flow control valve 462, respectively. With this configuration, the flow rate of the first heat transfer medium M1 supplied to the first condensing section 41a and the second condensing section 41b can be controlled by adjusting the opening degree of the first flow control valve 461 and the opening degree of the second flow control valve 462, respectively.

[0165] Although not shown in the diagram, the membrane separation system 100E may also include a heating device 58 for heating the raw fluid F0 supplied to the first membrane separation unit 10.

[0166] The operation method of the membrane separation system 100E is the same as that of the membrane separation system 100D (Figure 7) in the modified example 3 described above, so the explanation is omitted. However, in the operation method of the membrane separation system 100E, steps 4-1 and 4-2 may be performed simultaneously.

[0167] [Modification 5 of the Membrane Separation System] Modification 5 of the membrane separation system of the first embodiment includes a plurality of membrane separation units, with at least one of them being a membrane separation unit. Figure 9 is a schematic configuration diagram showing Modification 5 of the membrane separation system of the first embodiment. The membrane separation system 100F of Modification 5 shown in Figure 9 includes a second membrane separation unit 20 and a third membrane separation unit 30 in addition to the first membrane separation unit 10. The second membrane separation unit 20 separates the first impermeable fluid F2, which is the supply fluid, into a second permeable fluid F3 and a second impermeable fluid F4. The third membrane separation unit 30 separates the second impermeable fluid F4, which is the supply fluid, into a third permeable fluid F5 and a third impermeable fluid F6. In the membrane separation system 100F, the second heat exchange unit 52 heats the third impermeable fluid F6 discharged from the third membrane separation unit 30 using the second heat transfer medium M2. The filtration separation unit 40 filters and separates the third impermeable fluid F6 sent from the third membrane separation unit 30. Aside from this, the membrane separation system 100F has basically the same configuration as the membrane separation system 100D (Figure 7) of the modified example 3 described above.

[0168] The membrane separation system 100F allows for more stable concentration of the final permeate fluid while efficiently utilizing the heat recovered from the first permeate fluid F1 via the condensation unit 41.

[0169] In the membrane separation system 100F, multiple membrane separation units are connected in series so that the impermeable fluid discharged from the membrane separation unit located upstream is supplied as a supply fluid to the membrane separation unit located downstream. In this embodiment, multiple membrane separation units connected in series in this manner are called a membrane separation unit. The membrane separation system 100F includes a membrane separation unit 300 in which a first membrane separation unit 10, a second membrane separation unit 20, and a third membrane separation unit 30 are connected in series. The membrane separation system 100F has a configuration in which the first membrane separation unit 10 is replaced with the membrane separation unit 300 in the membrane separation system 100D (Figure 7) of the modified example 3 described above.

[0170] The membrane separation system 100F includes a first heat exchange section 51 and a second heat exchange section 52, as well as a fourth heat exchange section 54 and a fifth heat exchange section 55. The fourth heat exchange section 54 heats the second impermeable fluid F4, which is supplied as a supply fluid to the third membrane separation section 30, using a second heat transfer medium M2. The fifth heat exchange section 55 heats the first impermeable fluid F2, which is supplied as a supply fluid to the second membrane separation section 20, using a second heat transfer medium M2. In the membrane separation system 100F, the second heat transfer medium M2 is supplied from downstream to upstream, that is, in the order of the second heat exchange section 52, the fourth heat exchange section 54, the fifth heat exchange section 55, and the first heat exchange section 51, so that the second heat transfer medium M2 is supplied in that order. The second heat exchange section 52, the fourth heat exchange section 54, the fifth heat exchange section 55, and the first heat exchange section 51 are connected in series by a second circulation path 82.

[0171] The second membrane separation unit 20 has a second separation membrane 21 that separates the first impermeable fluid F2 into a second permeable fluid F3 and a second impermeable fluid F4. The third membrane separation unit 30 has a third separation membrane 31 that separates the second impermeable fluid F4 into a third permeable fluid F5 and a third impermeable fluid F6. The configurations of the second membrane separation unit 20 and the third membrane separation unit 30 are basically the same as those of the first membrane separation unit 10, so their explanation is omitted.

[0172] In the membrane separation system 100F, the first impermeable fluid path 93 connects the first impermeable fluid outlet 10c of the first membrane separation unit 10 and the first impermeable fluid inlet of the second membrane separation unit 20, and is a path that guides the first impermeable fluid F2 from the first membrane separation unit 10 to the second membrane separation unit 20.

[0173] As shown in Figure 9, in the membrane separation system 100F, the fifth heat exchange section 55 is located on the first impermeable fluid path 93.

[0174] The membrane separation system 100F further includes a second permeable fluid path 94, a second impermeable fluid path 95, a third permeable fluid path 96, and a third impermeable fluid path 97 as fluid pathways.

[0175] The second permeable fluid path 94 is connected to the second permeable fluid outlet of the second membrane separation unit 20 and is a path for discharging the second permeable fluid F3 from the second membrane separation unit 20. If the raw fluid F0 is a solution containing a volatile organic compound, a concentration sensor for measuring the content of the organic compound in the second permeable fluid F3 may be placed in the second permeable fluid path 94.

[0176] In the membrane separation system 100F, the second permeable fluid path 94 merges with the first permeable fluid path 92 at the merging position 92p. This configuration allows the second permeable fluid F3 to be guided from the second membrane separation section 20 to the condensation section 41a.

[0177] The second impermeable fluid path 95 is connected to the second impermeable fluid outlet of the second membrane separation unit 20 and is a path for discharging the second impermeable fluid F4 from the second membrane separation unit 20. If the raw fluid F0 is a solution containing volatile organic compounds, a concentration sensor for measuring the content of organic compounds in the second impermeable fluid F4 may be placed in the second impermeable fluid path 95.

[0178] As shown in Figure 9, in the membrane separation system 100F, the fourth heat exchange section 54 is located on the second impermeable fluid path 95.

[0179] The third permeable fluid path 96 is connected to the third permeable fluid outlet of the third membrane separation unit 30 and is a path for discharging the third permeable fluid F5 from the third membrane separation unit 30. If the raw fluid F0 is a solution containing a volatile organic compound, a concentration sensor for measuring the content of the organic compound in the third permeable fluid F5 may be placed in the third permeable fluid path 96.

[0180] In the membrane separation system 100F, the third permeable fluid path 96 merges with the second permeable fluid path 94 at the confluence point 94p. This configuration allows the third permeable fluid F5 to be guided from the third membrane separation section 30 to the condensation section 41a.

[0181] The third impermeable fluid path 97 is connected to the third impermeable fluid outlet of the third membrane separation unit 30 and is a path for discharging the third impermeable fluid F6 from the third membrane separation unit 30. If the raw fluid F0 is a solution containing a volatile organic compound, a concentration sensor for measuring the content of the organic compound in the third impermeable fluid F6 may be placed in the third impermeable fluid path 97.

[0182] In the membrane separation system 100F, the third impermeable fluid path 97 is connected to the impermeable fluid inlet of the filtration separation unit 40.

[0183] As shown in Figure 9, in the membrane separation system 100F, the second heat exchange unit 52, the second temperature sensor 62, the heating device 57, and the second temperature sensor 63 are located on the third impermeable fluid path 97.

[0184] Although not shown in the diagram, the membrane separation system 100F may include a heating device 58 for heating the raw fluid F0 supplied to the first membrane separation unit 10.

[0185] The operating method of the membrane separation system 100F is the same as the operating method of the membrane separation system 100A (Figure 1) described above, and includes, in addition to separating the raw fluid F0 into a first permeable fluid F1 and a first impermeable fluid F2 in the first membrane separation unit 10 (step 1-1), separating the first impermeable fluid F2 into a second permeable fluid F3 and a second impermeable fluid F4 in the second membrane separation unit 20 (step 1-2), and separating the second impermeable fluid F4 into a third permeable fluid F5 and a third impermeable fluid F6 in the third membrane separation unit 30 (step 1-3). Furthermore, the operating method, in the operating method of the membrane separation system 100A described above, includes, instead of heating the first impermeable fluid F2 using the second heat medium M2 with the second heat exchange unit 52 (step 4-1), heating the third impermeable fluid F6 using the second heat medium M2 with the second heat exchange unit 52 (step 4-4), heating the second impermeable fluid F4 using the second heat medium M2 with the fourth heat exchange unit 54 (step 4-5), heating the first impermeable fluid F2 using the second heat medium M2 with the fifth heat exchange unit 55 (step 4-6), and heating the raw fluid F0 using the second heat medium M2 with the first heat exchange unit 51 (step 4-2).

[0186] [Modification 6 of the Membrane Separation System] Figure 10 is a schematic diagram showing modification 6 of the membrane separation system of the first embodiment. The membrane separation system 100G of modification 6 shown in Figure 10 comprises a first membrane separation unit 300a and a second membrane separation unit 300b as membrane separation units. In the membrane separation system 100G, the first membrane separation unit 300a and the second membrane separation unit 300b are connected in parallel so that the raw fluid F0 is supplied to the first membrane separation section 10 of the first membrane separation unit 300a and the first membrane separation section 10 of the second membrane separation unit 300b, respectively. Except for this, the membrane separation system 100G has basically the same configuration as the membrane separation system 100F (Figure 9) of modification 5 described above.

[0187] The membrane separation system 100G allows for more stable concentration of the final permeate fluid while efficiently utilizing the heat recovered from the first permeate fluid F1 via the condensation unit 41.

[0188] In the membrane separation system 100G, the second heat transfer medium M2 is supplied from downstream to upstream, that is, in the order of the second heat exchange section 52 of the first membrane separation unit 300a, the fourth heat exchange section 54 of the first membrane separation unit 300a, the fourth heat exchange section 54 of the second membrane separation unit 300b, the fifth heat exchange section 55 of the second membrane separation unit 300b, the fifth heat exchange section 55 of the first membrane separation unit 300a, and the first heat exchange section 51 of the first membrane separation unit 300a, with each heat exchange section connected in series by a second circulation path 82.

[0189] In the membrane separation system 100G, the raw fluid path 91 of the first membrane separation unit 300a branches off at branching position 91q to the raw fluid path 91 of the second membrane separation unit 300b. With this configuration, the raw fluid F0 can be guided to both the first membrane separation unit 300a and the second membrane separation unit 300b.

[0190] In the membrane separation system 100G, the third impermeable fluid path 97 of the second membrane separation unit 300b merges with the third impermeable fluid path 97 of the first membrane separation unit 300a at the confluence position 97p. With this configuration, the third impermeable fluid F6 can be guided to the filtration separation section 40 from both the first membrane separation unit 300a and the second membrane separation unit 300b.

[0191] In the membrane separation system 100G, the first permeable fluid path 92 of the first membrane separation unit 300a merges with the first permeable fluid path 92 of the second membrane separation unit 300b at the merging position 92p of the second membrane separation unit 300b. With this configuration, permeable fluid can be guided to the condensation section 41a from both the first membrane separation unit 300a and the second membrane separation unit 300b.

[0192] Although not shown in the diagram, the membrane separation system 100G may also include a heating device 58 for heating the raw fluid F0 supplied to the first membrane separation section 10 of the first membrane separation unit 300a and the first membrane separation section 10 of the second membrane separation unit 300b.

[0193] The operation method of the membrane separation system 100G is the same as that of the membrane separation system 100F (Figure 9) in the modified example 5 described above, so a detailed explanation is omitted.

[0194] (Second Embodiment) Next, a membrane separation system of the second embodiment will be described. In the following, elements common to the membrane separation system of the first embodiment described above will be given the same reference numerals, and detailed explanations will be omitted.

[0195] The membrane separation system of the second embodiment includes a return path for returning the impermeable fluid to the supply unit. The membrane separation system of the second embodiment does not necessarily have a filtration separation unit for filtering and separating the impermeable fluid.

[0196] Figure 11 is a schematic diagram showing an example of a membrane separation system according to the second embodiment. The membrane separation system 200A in Figure 11 includes a first non-permeable fluid path 93 as a return path. The membrane separation system 200A has the same configuration as the membrane separation system 100A of the first embodiment (Figure 1) described above, but with the filtration separation unit 40 replaced by a supply unit 60.

[0197] In the membrane separation system 200A, the supply unit 60 is a culture tank for producing organic compounds by fermentation of a carbon source by microorganisms. When the supply unit 60 is a culture tank, if the temperature of the raw fluid F0 stored in the supply unit 60 drops too low, fermentation by microorganisms may stop or the microorganisms may die. With the membrane separation system 200A, heat recovered from the first permeate fluid F1 via the condensation unit 41 can be supplied to the first impermeable fluid F2. Therefore, it is possible to efficiently heat the first impermeable fluid F2 supplied to the supply unit 60. As a result, the efficiency of thermal energy utilization in the membrane separation system 200A can be improved. Also, for example, if the raw fluid F0 is a fermentation liquid containing organic compound C as a fermentation product, when the first impermeable fluid F2 is returned to the supply unit 60, the fermentation liquid and the first impermeable fluid F2 are mixed in the supply unit 60. This reduces the content of organic compound C in the fermentation liquid. When the supply unit 60 is a culture tank, it is possible to suppress the cessation of fermentation by microorganisms. Therefore, the production of fermented products can be carried out continuously.

[0198] In the membrane separation system 200A, the first impermeable fluid path 93 is connected to the impermeable fluid inlet 60a of the supply unit 60. In other words, in the membrane separation system 200A, the first impermeable fluid F2 is mixed with the raw fluid F0 in the supply unit 60 and circulates through the raw fluid path 91 and the first impermeable fluid path 93. With this configuration, the first impermeable fluid F2 can be guided from the first impermeable fluid path 93 to the supply unit 60.

[0199] As shown in Figure 11, in the membrane separation system 200A, the second heat exchange unit 52, the second temperature sensor 62, the heating device 57, and the second temperature sensor 63 are located on the first impermeable fluid path 93, which serves as a return path.

[0200] The membrane separation system of the second embodiment may or may not include a heating device for heating the raw fluid supplied to the first membrane separation unit.

[0201] The operating method of the membrane separation system 200A further includes, in the operating method of the membrane separation system 100A of the first embodiment described above (Figure 1), returning the first impermeable fluid F2 to the supply unit 60 (step 5).

[0202] <Modifications of the Membrane Separation System> The membrane separation system of the second embodiment is not limited to the membrane separation system 200A shown in Figure 11. Hereinafter, modifications 1 to 3 of the membrane separation system of the second embodiment will be described with reference to Figures 12 to 14.

[0203] [Modification 1 of the Membrane Separation System] Figure 12 is a schematic diagram showing modification 1 of the membrane separation system of the second embodiment. The membrane separation system 200B of modification 1 shown in Figure 12 includes a first heat exchange unit 51 in addition to the second heat exchange unit 52. The first heat exchange unit 51 heats the raw fluid F0, which is supplied as a supply fluid to the first membrane separation unit 10, using a second heat transfer medium M2. In the membrane separation system 200B, the second heat transfer medium M2 is supplied to the second heat exchange unit 52 and then to the first heat exchange unit 51 in that order, and the second heat exchange unit 52 and the first heat exchange unit 51 are connected in series by a second circulation path 82. Except for this, the membrane separation system 200B has basically the same configuration as the membrane separation system 200A (Figure 11) described above.

[0204] In the membrane separation system 200B, the temperature of the second heat medium M2 supplied to the first heat exchange unit 51 is lower than the temperature of the second heat medium M2 supplied to the second heat exchange unit 52. As described above, the temperature of the impermeable fluid discharged from the membrane separation unit is lower than the temperature of the supply fluid supplied to the membrane separation unit. In the membrane separation system 200B, the temperature of the second heat medium M2 supplied to the heat exchanger decreases from the downstream side to the upstream side, so the heat recovered from the first permeable fluid F1 via the condensation unit 41 can be utilized more efficiently.

[0205] The operating method of the membrane separation system 200B further includes, in the operating method of the membrane separation system 100D (Figure 7) of the modified example 3 of the first embodiment described above, returning the first impermeable fluid F2 to the supply unit 60 (step 5).

[0206] [Modified Membrane Separation System 2] Figure 13 is a schematic diagram showing modified membrane separation system 2 of the second embodiment. The membrane separation system 200C of modified membrane separation system 2 shown in Figure 13 includes a first condensation section 41a and a second condensation section 41b connected in series downstream of the first condensation section 41a as condensation sections. Except for this, the membrane separation system 200C has basically the same configuration as the membrane separation system 200A (Figure 11) described above.

[0207] According to the membrane separation system 200C, the concentration of the final permeate fluid can be increased while efficiently utilizing the heat recovered from the first permeate fluid F1 via the condensation unit 41.

[0208] The second condensation section 41b, for example, further cools and condenses the permeate fluid after condensation that has been sent from the first condensation section 41a. The condensation temperature of the second condensation section 41b may be the same as or different from that of the first condensation section 41a.

[0209] In the membrane separation system 200C, the second condenser 41b and the first condenser 41a are connected in series by a first circulation path 81 so that the first heat transfer medium M1 is supplied from downstream to upstream, that is, in the order of the second condenser 41b and the first condenser 41a. With this configuration, heat can be efficiently recovered from the permeate fluid via the first condenser 41a and the second condenser 41b.

[0210] The membrane separation system 200C includes two condensation sections (first condensation section 41a, second condensation section 41b) as condensation sections. However, the membrane separation system 200C may include three or more condensation sections.

[0211] As shown in Figure 13, the first condensing section 41a and the second condensing section 41b may be connected to a first recovery section 75a and a second recovery section 75b, respectively, for recovering the permeate fluid of the liquid obtained by condensation. The first recovery section 75a and the second recovery section 75b are, for example, tanks for storing the permeate fluid of the liquid. If the raw fluid F0 is a solution containing a volatile organic compound, concentration sensors for measuring the content of the organic compound in the condensed permeate fluid may be placed in the path connecting the first condensing section 41a and the first recovery section 75a, and in the path connecting the second condensing section 41b and the second recovery section 75b.

[0212] The operating method of the membrane separation system 200C further includes, in the operating method of the membrane separation system 100D (Figure 7) of the modified example 3 of the first embodiment described above, returning the first impermeable fluid F2 to the supply unit 60 (step 5).

[0213] [Modification 3 of the Membrane Separation System] Modification 3 of the membrane separation system of the second embodiment includes a plurality of membrane separation units, with at least one being a membrane separation unit. Figure 14 is a schematic diagram showing modification 3 of the membrane separation system of the second embodiment. The membrane separation system 200D of modification 3 shown in Figure 14 includes a second membrane separation unit 20 and a third membrane separation unit 30 in addition to the first membrane separation unit 10. The membrane separation system 200D includes a membrane separation unit 300 in which the first membrane separation unit 10, the second membrane separation unit 20 and the third membrane separation unit 30 are connected in series. The membrane separation system 200D has a configuration in which the filtration separation unit 40 is replaced with a supply unit 60 in the membrane separation system 100F (Figure 9) of modification 5 of the first embodiment described above.

[0214] The membrane separation system 200D allows for more stable concentration of the final permeate fluid while efficiently utilizing the heat recovered from the first permeate fluid F1 via the condensation unit 41.

[0215] The membrane separation system 200D includes a third impermeable fluid path 97 as a return path, and the third impermeable fluid path 97 is connected to the impermeable fluid inlet 60a of the supply unit 60. Except for this, the membrane separation system 200D has basically the same configuration as the membrane separation system 100F (Figure 9) of the modified example 5 of the first embodiment described above. Therefore, a detailed explanation is omitted.

[0216] The operating method of the membrane separation system 200D further includes, in the operating method of the membrane separation system 100F (Figure 9) of the modified example 5 of the first embodiment described above, returning the first impermeable fluid F2 to the supply unit 60 (step 5).

[0217] The above-described embodiments are mutually applicable, insofar as they do not conflict with technical standards. Each of the above embodiments and each of its modifications may be combined with each other, insofar as they do not conflict with technical standards.

[0218] For example, by combining the membrane separation system 100A (Figure 1), membrane separation system 100B (Figure 5), and membrane separation system 100C (Figure 6) of the first embodiment, a configuration may be made in which at least one selected from the group consisting of the raw fluid F0 supplied to the first membrane separation unit 10 using the second heat transfer medium M2, the first impermeable fluid F2 discharged from the first membrane separation unit 10, and the first membrane separation unit 10 can be heated. For example, in the membrane separation system 200A (Figure 11) of the second embodiment, instead of the second heat exchange unit 52, a third heat exchange unit 53 that heats the first membrane separation unit 10 may be provided, as in the membrane separation system 100C (Figure 6) of the first embodiment. For example, in the membrane separation system 200C (Figure 13) of the second embodiment, the first circulation path 81 and the second circulation path 82 may be connected in parallel, as in the membrane separation system 100E (Figure 8) of the first embodiment.

[0219] The membrane separation system of this embodiment is particularly suitable for efficiently recovering volatile organic compounds from a solution containing such compounds.

Claims

1. A membrane separation system comprising: at least one membrane separation unit for separating a supply fluid into a permeable fluid and an impermeable fluid; a heat pump for recovering heat from a first heat medium and transferring it to a second heat medium; a condensing unit for cooling and condensing the permeable fluid using the first heat medium; and a heat exchange unit for heating at least one selected from the group consisting of the supply fluid, the impermeable fluid, and the at least one membrane separation unit using the second heat medium.

2. The membrane separation system according to claim 1, comprising: a first temperature sensor for measuring the temperature of at least one selected from the group consisting of the first heat transfer medium and the permeable fluid; and a second temperature sensor for measuring the temperature of at least one selected from the group consisting of the second heat transfer medium, the supply fluid, the non-permeable fluid, and the at least one membrane separation unit.

3. The membrane separation system according to claim 2, wherein at least one selected from the group consisting of (i) and (ii) below is performed: (i) Based on the monitoring result from the first temperature sensor, the operation of the heat pump is controlled so that the temperature of at least one selected from the group consisting of the first heat medium and the permeate fluid satisfies a first predetermined range; (ii) Based on the monitoring result from the second temperature sensor, the operation of the heat pump is controlled so that the temperature of at least one selected from the group consisting of the second heat medium, the supply fluid, the non-permeate fluid, and the at least one membrane separation unit satisfies a second predetermined range.

4. The membrane separation system according to claim 3, further comprising a heating device for heating at least one selected from the group consisting of the supply fluid, the impermeable fluid, and the at least one membrane separation unit.

5. If, after (ii) is performed, at least one temperature selected from the group consisting of the second heat transfer medium, the supply fluid, the impermeable fluid, and the at least one membrane separation unit does not meet the second predetermined range, the operation of the heating device is controlled to meet the second predetermined range, the membrane separation system according to claim 4.

6. The membrane separation system according to claim 3, further comprising a cooling device for cooling the first heat transfer medium.

7. If, after (i) is performed, at least one temperature selected from the group consisting of the first heat transfer medium and the permeate fluid does not meet the first predetermined range, the operation of the cooling device is controlled to meet the first predetermined range, according to claim 6.

8. The membrane separation system according to claim 1, wherein the at least one membrane separation unit has a separation membrane, and the separation membrane includes a permeable vaporization membrane.

9. The membrane separation system according to claim 8, wherein the supply fluid includes a raw fluid, and the raw fluid includes a solution containing a volatile organic compound.

10. The membrane separation system according to claim 9, further comprising a supply unit for storing the raw fluid.

11. The membrane separation system according to claim 10, further comprising a return path for returning the non-permeable fluid to the supply unit.

12. The membrane separation system according to claim 1, further comprising: a first circulation path for circulating the first heat medium between the heat pump and the condensing unit; and a second circulation path for circulating the second heat medium between the heat pump and the heat exchange unit.

13. The membrane separation system according to claim 1, further comprising a filtration separation unit for filtering and separating the non-permeable fluid.

14. The membrane separation system according to claim 1, further comprising a depressurization unit for reducing the pressure within the permeable space of the membrane separation unit, wherein the depressurization unit includes a vacuum pump.

15. The membrane separation system according to claim 1, wherein the at least one membrane separation unit comprises a plurality of membrane separation units.

16. The membrane separation system according to claim 15, comprising a membrane separation unit in which a plurality of membrane separation units are connected in series such that the impermeable fluid discharged from the membrane separation unit located upstream is supplied as the supply fluid to the membrane separation unit located downstream.

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