Culture device

Abstract

The present invention provides a culture apparatus that prevents the formation of stagnant algae within the pipe when the culture medium and microalgae are discharged from the flow pipe to the containment section. [Solution] The culture apparatus comprises a containment section 20, a flow pipe 54 inserted into the containment section 20, and a replacement gas supply section. In the flow pipe 54, the section between the opening 541 located inside the containment section 20 and the valve installation location 55 where a switching valve 58 is provided is referred to as the section 542. The replacement gas supply section supplies replacement gas G into the section 542. The algae RA that remain inside the section 542 are replaced by the replacement gas G. The algae RA that remain inside the pipe are discharged into the containment section 20 through the opening 541 of the flow pipe 54.

Description

Technical Field

[0001] This disclosure relates to a culture device.

Background Art

[0002] As described in Japanese Patent Application Laid-Open No. 2023-150307, a culture device for culturing microalgae includes a storage unit that stores a culture solution and microalgae. A culture gas containing carbon dioxide gas is supplied to the culture solution in the storage unit. The microalgae perform photosynthesis based on light such as sunlight, carbon dioxide gas in the culture gas, and water contained in the culture solution.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The culture solution and microalgae stored in the storage unit are, for example, stored in a storage tank in advance. When culturing microalgae in the storage unit, the culture solution and microalgae in the storage tank are sent to the storage unit through, for example, a pump and a flow pipe. The microalgae whose culture has ended in the storage unit are returned to the storage tank through the pump and the flow pipe. To perform such operations, one end of the flow pipe is inserted into the storage unit.

[0005] When allowing the culture solution and microalgae to flow out from the flow pipe into the storage unit, the liquid level of the culture solution in the storage unit rises. As a result, one end of the flow pipe is immersed in the culture solution. After the liquid level has risen to a predetermined height in this way, the transfer of the culture solution and microalgae is stopped. Along with this, microalgae remain in the inside of one end of the flow pipe. Hereinafter, the microalgae remaining in the flow pipe are referred to as "algae retained in the pipe".

[0006] Generally, the material of the flow pipe is an opaque, non-transparent resin. Therefore, it is difficult for the algae accumulating inside the pipe to perform photosynthesis. As can be understood from this, in a culture apparatus with the above configuration, it is not easy to effectively utilize a portion of the microalgae sent from the recovery tank to the containment section.

[0007] This disclosure aims to solve the problems described above. [Means for solving the problem]

[0008] Aspects of the present disclosure are culture apparatus for culturing microalgae in a culture medium, comprising: a containment section capable of containing the culture medium and the microalgae; a culture gas supply section for supplying culture gas to the culture medium contained in the containment section; a flow pipe inserted into the containment section and extending along the depth direction of the containment section, through which the culture medium and the microalgae flow; a switching valve provided in the portion of the flow pipe exposed from the culture medium, which switches the flow pipe between a flow state in which the culture medium and the microalgae can flow and a blocked state in which the flow of the culture medium and the microalgae is blocked; and a replacement gas supply section in the flow pipe for supplying replacement gas to replace the culture medium and the microalgae that have accumulated inside the section between an opening located in the containment section and a valve installation location where the switching valve is provided, wherein the replacement gas supply section supplies the replacement gas to the inside of the section, thereby discharging the culture medium and the microalgae inside the section into the containment section through the opening of the flow pipe. [Effects of the Invention]

[0009] According to this disclosure, algae remaining in the pipe can be sent from the section into the containment section and used for cultivation. In other words, microalgae can be effectively utilized. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram of the culture apparatus according to the first embodiment. [Figure 2]Figure 2 is a cross-sectional view of the main part of the storage section where the culture medium is being stored. [Figure 3] Figure 3 is a cross-sectional view of the main part of the container, showing the storage section after the culture medium has been stored. [Figure 4] Figure 4 is a cross-sectional view of the main section showing the containment area when the accumulated algae inside the pipe are being discharged from the section. [Figure 5] Figure 5 is a schematic diagram of the culture apparatus according to the second embodiment. [Figure 6] Figure 6 is a cross-sectional view of the main part of a modified culture apparatus. [Figure 7] Figure 7 is a cross-sectional view of the main part of the container, showing the storage section after the culture medium has been stored. [Figure 8] Figure 8 is a cross-sectional view of the main section showing the containment area when the accumulated algae inside the pipe are being discharged from the section. [Modes for carrying out the invention]

[0011] In the following, "culture gas" refers to gas containing carbon dioxide, which is useful for photosynthesis in microalgae. A specific example of culture gas is air. The culture gas may also be exhaust gas discharged from a factory's exhaust line.

[0012] Figure 1 is a schematic diagram of the culture apparatus 10A according to the first embodiment. The culture apparatus 10A includes one or more storage compartments 20. In the illustrated example, two storage compartments 20 are shown, but the number of storage compartments 20 is not limited to two. The number of storage compartments 20 may be one, three or more, or more.

[0013] The containment section 20 is made of, for example, a flexible bag material. In this case, the containment section 20 is supported by a support frame (not shown). The containment section 20 is positioned upright, for example, so that the depth direction of the culture medium CS coincides with the vertical direction. Alternatively, the containment section 20 is positioned at an angle so that the depth direction of the culture medium CS is inclined with respect to the vertical direction. An insertion opening 22 is formed at the upper end of the containment section 20. The containment section 20 may also be a box made of a rigid, non-flexible transparent resin.

[0014] The containment section 20 contains the culture medium CS and microalgae. The containment section 20 is a culture tank for culturing microalgae. A specific example of the culture medium CS is water. It is preferable that phosphorus, nitrogen, potassium, etc. are added to the culture medium CS. A specific example of microalgae is the "Honda DREAMO strain" deposited with the Patent Organism Depositary Center of the National Institute of Technology and Evaluation. The address of the Patent Organism Depositary Center of the National Institute of Technology and Evaluation is Room 120, 2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture. The deposit date for the Honda DREAMO strain was April 22, 2016, and the deposit number is FERM BP-22306.

[0015] The containment section 20 may be surrounded by a water reservoir (not shown). Water is stored in the water reservoir. The water is a cooling medium for cooling the culture medium CS inside the containment section 20. The water reservoir and the containment section 20 are each formed from a light-transmitting material. Therefore, light irradiated from outside the water reservoir passes through the water reservoir and the containment section 20 and reaches the inside of the containment section 20.

[0016] The culture apparatus 10A comprises a culture gas supply unit 30 and a replacement gas supply unit 32. In the illustrated example, the replacement gas supply unit 32 and the culture gas supply unit 30 are the same gas supply unit. That is, in this embodiment, the replacement gas supply unit 32 also serves as the culture gas supply unit 30 and supplies culture gas as replacement gas G (see Figure 4). However, the culture gas supply unit 30 and the replacement gas supply unit 32 may be separate gas supply units. In this case, the replacement gas supply unit 32 may supply a gas other than culture gas (for example, oxygen gas or an inert gas) as replacement gas G.

[0017] As shown in Fig. 1, the culture gas supply unit 30 has a gas supply source 34 and a supply pipe 38A. The gas supply source 34 is, for example, a compressor 36. The compressor 36 obtains compressed air from the atmosphere, for example, and sends this compressed air as culture gas to the supply pipe 38A. The compressor 36 may compress the exhaust gas from the factory to obtain compressed exhaust gas and send this compressed exhaust gas as culture gas to the supply pipe 38A. Alternatively, the gas supply source 34 may be a cylinder filled with compressed air or carbon dioxide gas.

[0018] The supply pipe 38A has a relay part 381 and a gas discharge part 382. The relay part 381 is connected to the compressor 36. A gas on-off valve 39 is provided in the relay part 381. The gas discharge part 382 is inserted into the housing part 20 through the insertion port 22 of the housing part 20 and is immersed in the culture solution CS. In this state, the gas discharge part 382 extends along the arrangement direction of the plurality of guide parts 40 described later. A plurality of discharge ports 383 are formed in the gas discharge part 382. The plurality of discharge ports 383 are arranged at intervals along the arrangement direction above the gas discharge part 382. In Fig. 1, the arrangement direction is the X direction.

[0019] The plurality of discharge ports 383 have a discharge port 383a for the flow pipe and a plurality of discharge ports 383b for the guide parts. The discharge port 383a for the flow pipe faces the opening 541 of the flow pipe 54 in the depth direction. The plurality of discharge ports 383b for the guide parts face the gas inlets 46 of the plurality of guide parts 40 respectively. When the depth direction is the vertical direction, the discharge port 383a for the flow pipe is located vertically below the opening 541, and each discharge port 383b for the guide part is located vertically below each gas inlet 46.

[0020] In the first embodiment, the culture device 10A includes a plurality of guide parts 40. The plurality of guide parts 40 are arranged in a row along the arrangement direction at intervals from each other. Each of the plurality of guide parts 40 is supported by a support frame, for example. Alternatively, each of the plurality of guide parts 40 is welded to the inner surface of the housing part 20. The plurality of guide parts 40 guide the culture gas discharged from the plurality of discharge ports 383 to the liquid surface of the culture solution CS. Note that the plurality of guide parts 40 are not essential.

[0021] In the following, to facilitate the distinction between multiple guide sections 40, an example will be given in which there are three guide sections 40, and the guide section 40 closest to the flow pipe 54 in the direction of alignment will be referred to as the first guide section 40a. In Figure 1, the guide section 40 located to the right of the first guide section 40a will be referred to as the second guide section 40b, and the guide section 40 located to the right of the second guide section 40b will be referred to as the third guide section 40c.

[0022] The first guide section 40a has a first guide section 42 and a second guide section 44. The first guide section 42 extends along the depth direction of the culture medium CS. The first guide section 42 has a gas inlet 46 at its lower part facing the guide section outlet 383b. In the first guide section 42, the side facing the second guide section 40b is preferably an open end. The second guide section 44 is connected to the upper end of the first guide section 42 so as to bend in the direction of alignment. In the second guide section 44, the side facing the second guide section 40b is an open end.

[0023] The second guide section 40b and the third guide section 40c have the same configuration as the first guide section 40a. Therefore, in the second guide section 40b and the third guide section 40c, the same reference numerals are used for components that are the same as those in the first guide section 40a, and detailed explanations are omitted.

[0024] In the first embodiment, the culture apparatus 10A includes a supply and discharge section 50 for supplying and discharging culture solution CS and microalgae to and from the containment section 20. The supply and discharge section 50 includes a recovery tank 52, a flow pipe 54, a bidirectional pump 56, and a switching valve 58. The bidirectional pump 56 is provided in the portion of the flow pipe 54 that is exposed from the culture solution CS.

[0025] The switching valve 58 is, for example, an on / off valve. When the switching valve 58 is open, the flow pipe 54 becomes a flowing state in which the culture medium CS and microalgae can flow. Conversely, when the switching valve 58 is closed, the flow pipe 54 becomes a blocked state in which the flow of the culture medium CS and microalgae is blocked. In this way, the switching valve 58 switches the flow pipe 54 between a flowing state and a blocked state.

[0026] The switching valve 58, which functions as described above, is installed in the flow pipe 54 at a valve installation location 55 that is exposed from the culture medium CS. In the illustrated example, the valve installation location 55 is located outside the housing 20, but the valve installation location 55 may also be located inside the housing 20. In the latter case, the valve installation location 55 is located above the liquid surface of the culture medium CS.

[0027] The flow tube 54 is formed from, for example, an opaque and non-transparent material. An example of such a material is polyvinyl chloride resin. The flow tube 54 is arranged in the direction of alignment together with the multiple guide sections 40. The flow tube 54 is positioned at one end in the direction of alignment. In the illustrated example, the flow tube 54 is located to the left of the first guide section 40a.

[0028] The flow pipe 54 has an opening 541. The opening 541 is the inlet for the culture solution CS and microalgae to flow into the flow pipe 54, and also the outlet for the culture solution CS and microalgae to flow out of the flow pipe 54 into the containment section 20. Hereinafter, the portion of the flow pipe 54 between the valve installation location 55 and the opening 541 will be referred to as the "section 542". In the section 542, the tip 543, including the opening 541, is inserted into the containment section 20 via the insertion opening 22 of the containment section 20 and extends along the depth direction of the containment section 20. When the culture solution CS and microalgae are contained in the containment section 20, the tip 543 of the section 542 is immersed in the culture solution CS. In this state, the opening 541 faces the outlet 383a for the flow pipe formed in the gas discharge section 382 of the supply pipe 38A.

[0029] In the illustrated example, the discharge port 383a for the flow pipe is located below (lower) the opening 541, and the discharge port 383b for the guide section is located below the gas inlet 46. However, the discharge port 383a for the flow pipe may be at the same height as the opening 541, and the discharge port 383b for the guide section may be at the same height as the gas inlet 46.

[0030] The culture apparatus 10A further comprises a control unit 60. The control unit 60 is electrically connected to the compressor 36, all gas on / off valves 39, all switching valves 58, and all bidirectional pumps 56. The control unit 60 controls the operation and stopping of the gas on / off valves 39, switching valves 58, and bidirectional pumps 56. Each of the housing units 20 may also be equipped with a control unit 60. However, the control unit 60 is not mandatory.

[0031] Next, a method for culturing microalgae using the culture apparatus 10A will be described. For the sake of simplicity, the following description will focus on a configuration in which the gas supply source 34 is a compressor 36, and compressed air is supplied as the culture gas and displacement gas G.

[0032] If microalgae cultivation is not taking place in the storage unit 20, the culture solution CS and microalgae are stored in the recovery tank 52, and the storage unit 20 is empty. Also, the compressor 36 is stopped, and the gas on / off valve 39 and the switching valve 58 are closed. To start microalgae cultivation, the culture solution CS and microalgae are transferred from the recovery tank 52 to the storage unit 20 from this state. Specifically, the operator inputs a "transfer start" command signal to the control unit 60.

[0033] Upon receiving this command signal, the control unit 60 energizes the bidirectional pump 56 and switches the switching valve 58 to the open state. As a result, the culture medium CS and microalgae in the recovery tank 52 are sucked in by the bidirectional pump 56 and flow through the flow pipe 54. As shown in Figure 2, the culture medium CS and microalgae flow out into the containment section 20 through the opening 541 via the section 542. Consequently, the culture medium CS and microalgae are gradually stored in the containment section 20. Along with this, the liquid level of the culture medium CS in the containment section 20 rises. The liquid level of the culture medium CS becomes higher than the opening 541. That is, the tip 543 of the section 542 is submerged in the culture medium CS.

[0034] A liquid level sensor (not shown) is provided in the storage section 20. As shown in Figure 3, when the liquid level of the culture medium CS reaches a predetermined height in the storage section 20, the liquid level sensor transmits an information signal to the control unit 60. The control unit 60 receives this information signal and transmits a "closed state" command signal to the switching valve 58 and a "stop operation" command signal to the bidirectional pump 56. As a result, the switching valve 58 switches to the closed state, and the flow pipe 54 switches to a blocked state that blocks the flow of the culture medium CS and microalgae.

[0035] When the flow pipe 54 is blocked, a reaction force acts on the culture medium CS and microalgae inside section 542 from the culture medium CS and microalgae inside the containment section 20. Due to this reaction force, it is difficult for the entire amount of culture medium CS and microalgae inside section 542 to leak out from the opening 541. Therefore, a predetermined amount of culture medium CS and microalgae remains inside section 542. That is, retained algae RA are formed inside the pipe. The height of the liquid level of retained algae RA inside the pipe is approximately the same as the height of the liquid level of culture medium CS inside the containment section 20.

[0036] Next, the control unit 60 (see Figure 1) energizes the compressor 36 and opens the gas on / off valve 39. As a result, compressed air flows through the gas discharge section 382 via the relay section 381 of the supply pipe 38A. The compressed air is discharged from each of the multiple discharge ports 383 into the culture medium CS in the containment section 20. The discharged compressed air rises along the depth direction toward the liquid surface of the culture medium CS.

[0037] As described above, among the multiple outlets 383, the outlet 383a for the flow pipe is located below the opening 541 of the flow pipe 54 and faces the opening 541. Therefore, the compressed air discharged from the outlet 383a for the flow pipe is supplied to the section 542 from the opening 541 as replacement gas G as shown in Figure 4. The replacement gas G flows into the section 542 from the opening 541. As a result, the algae RA remaining in the pipe are pushed out into the containment section 20 from the opening 541. In this way, the algae RA remaining in the pipe are replaced by the replacement gas G. That is, the section 542 is filled with replacement gas G (compressed air).

[0038] The relative density of the displacement gas G is lower than the relative density of the culture medium CS. Therefore, it is difficult for the culture medium CS in the containment section 20 to flow into the section 542 filled with displacement gas G. In other words, the reformation of stagnant algae RA in the section 542 is suppressed. In this state, the discharge of compressed air from the outlet 383a for the flow pipe continues.

[0039] On the other hand, among the multiple outlets 383, several guide outlets 383b are located below the gas inlet 46 and face the gas inlet 46. Therefore, the compressed air discharged from the guide outlets 383b rises from the gas inlet 46 along the second guide section 44, and then moves in the direction of alignment at the top of the culture medium CS by the second guide section 44. As a result, the culture medium CS and microalgae move together with the compressed air.

[0040] A portion of the culture medium CS and microalgae guided by the first guide section 40a moves toward the second guide section 40b, and then, upon contact with the side (closed end) of the first guide section 42 of the second guide section 40b, moves toward the bottom of the containment section 20. A portion of the culture medium CS and microalgae guided by the second guide section 40b moves toward the third guide section 40c, and then, upon contact with the side (closed end) of the first guide section 42 of the third guide section 40c, moves toward the bottom of the containment section 20. A portion of the culture medium CS and microalgae guided by the third guide section 40c moves toward the inner surface of the side of the containment section 20, and then, upon contact with the inner surface, moves toward the bottom of the containment section 20. As a result, convection occurs within the containment section 20, as shown by arrows A and B in Figure 1. This convection stirs the culture medium CS and microalgae. Therefore, the accumulation of microalgae at the bottom of the containment section 20 is suppressed.

[0041] The containment section 20 is exposed to light such as sunlight. Furthermore, the culture gas contains carbon dioxide. Therefore, the microalgae in the containment section 20 perform photosynthesis. As described above, the stagnant algae RA in the pipe are already mixed in the culture solution CS within the containment section 20. Consequently, the microalgae contained in the stagnant algae RA also participate in photosynthesis within the containment section 20. As can be understood from this, according to this embodiment, the stagnant algae RA can be sent from the section 542 into the culture solution CS within the containment section 20. Therefore, the microalgae supplied to the containment section 20 from the recovery tank 52 can be effectively utilized.

[0042] Furthermore, compressed air is continuously discharged from the outlet 383a for the flow pipe. This compressed air also plays a role as a culture gas while stirring the culture medium CS. Therefore, microalgae can perform photosynthesis sufficiently between the flow pipe 54 and the first guide section 40a.

[0043] For the reasons stated above, the culture device 10A makes it possible to sufficiently cultivate microalgae.

[0044] The first embodiment provides the following effects.

[0045] The culture apparatus 10A comprises a containment section 20, a culture gas supply section 30, a flow pipe 54, a switching valve 58, and a replacement gas supply section 32. The replacement gas supply section 32 supplies replacement gas G to push out the stagnant algae RA in the section 542 of the flow pipe 54. In other words, the replacement gas G replaces the stagnant algae RA in the pipe.

[0046] The stagnant algae RA discharged into the containment section 20 mix with the culture medium CS and microalgae in the containment section 20. In other words, the stagnant algae RA discharged from section 542 into the containment section 20 participate in photosynthesis in the containment section 20. Therefore, the microalgae supplied from the recovery tank 52 to the containment section 20 can be effectively utilized.

[0047] The replacement gas supply unit 32 also serves as the culture gas supply unit 30. Therefore, the replacement gas supply unit 32 supplies the culture gas as replacement gas G. In this case, the culture gas supply unit 30 and the replacement gas supply unit 32 can be configured as the same gas supply unit. This simplifies the configuration of the culture apparatus 10A and reduces capital investment.

[0048] The culture apparatus 10A is equipped with a plurality of guide sections 40. The plurality of guide sections 40 guide the culture gas from the bottom of the containment section 20 toward the liquid surface of the culture medium CS. The culture gas supply section 30 has a plurality of outlets 383. The plurality of outlets 383 include a flow pipe outlet 383a that supplies culture gas to the opening 541 of the flow pipe 54, and a plurality of guide section outlets 383b that supply culture gas to each of the plurality of guide sections 40.

[0049] As the culture gas discharged from each of the multiple outlets 383 rises along the guide section 40 through the culture medium CS, the culture medium CS in the containment section 20 is agitated. This agitation prevents microalgae from accumulating at the bottom of the containment section 20, thus allowing the culture to proceed efficiently. Furthermore, since the replacement gas G is also a culture gas, the continuous supply of replacement gas G to the culture medium CS agitates the culture medium CS and allows the microalgae to proceed efficiently.

[0050] The supply pipe 38A has a gas discharge section 382 with a plurality of outlets 383 formed therein. Of the plurality of outlets 383, the outlet 383a for the flow pipe supplies culture gas toward the opening 541 of the flow pipe 54. Of the plurality of outlets 383, the outlets 383b for the guide section supply replacement gas G toward the gas inlet 46 of the guide section 40.

[0051] As the replacement gas G flows into the flow pipe 54, it is easy to replace the stagnant algae RA inside the flow pipe 54 with the replacement gas G. In addition, since the culture gas easily rises along each of the multiple guide sections 40, convection is easily generated in the culture medium CS inside the containment section 20.

[0052] The containment section 20 has an inlet 22 located above the liquid level of the culture medium CS. The flow pipe 54 and the supply pipe 38A are inserted into the containment section 20 through the inlet 22 and immersed in the culture medium CS.

[0053] If an inlet 22 is formed on the side of the containment section 20, and the liquid level of the culture medium CS is above (higher than) the inlet 22, there is a concern that the culture medium CS and microalgae inside the containment section 20 may leak out of the containment section 20 from between the inner surface of the inlet 22 and the flow pipe 54 or supply pipe 38A. With the above configuration, this concern is eliminated.

[0054] The flow tube 54 is positioned at one end in the direction in which the multiple guide sections 40 are aligned. This prevents the flow tube 54 from obstructing the convection of the culture medium CS.

[0055] The culture apparatus 10A is equipped with multiple containment sections 20. A flow pipe 54, each of which is fitted with a switching valve 58, is inserted into the interior of each of the containment sections 20. This makes it possible to cultivate a large amount of microalgae simultaneously.

[0056] The culture apparatus 10A includes a control unit 60 that controls a switching valve 58 and a replacement gas supply unit 32. The control unit 60 executes a control to stop the supply of replacement gas G from the replacement gas supply unit 32 when the flow pipe 54 is in a flow state. On the other hand, the control unit 60 executes a control to supply replacement gas G from the replacement gas supply unit 32 when the flow pipe 54 is in a shut-off state. Therefore, there is no need for an operator to manually operate the switching valve 58.

[0057] In an embodiment where the culture apparatus 10A has multiple containment sections 20, microalgae can be successfully cultured in all of the containment sections 20. Therefore, it is possible to propagate microalgae on an industrial scale.

[0058] Next, with reference to Figure 5, the culture apparatus 10B according to the second embodiment will be described. Components identical to those of the culture apparatus 10A according to the first embodiment are given the same reference numerals, and detailed descriptions are omitted. Also, although the illustrated example shows one housing section 20, the number of housing sections 20 may be multiple, as in the first embodiment. Furthermore, an embodiment in which the culture apparatus 10B includes multiple guide sections 40 will be described, but multiple guide sections 40 are not essential.

[0059] The culture gas supply unit 30 includes a compressor 36 and a supply pipe 38B. The supply pipe 38B has a relay section 381, a main pipe section 385, and a plurality of sub-pipe sections 386 branching off from the main pipe section 385. A gas on / off valve 39 is provided in the relay section 381. The main pipe section 385 is supported, for example, by a support frame above the housing section 20 and extends along the direction in which the plurality of guide sections 40 are aligned.

[0060] Each of the multiple sub-tube sections 386 has a straight section 387 and a curved section 388. The straight section 387 is connected to the main tube section 385 and extends linearly along the depth direction of the culture medium CS. The curved section 388 curves from the lower end of the straight section 387 toward the liquid surface of the culture medium CS. As a result, the sub-tube section 386 has a roughly J-shape. The multiple sub-tube sections 386 are spaced apart from each other along the direction of alignment. In the second embodiment, each outlet 383 is formed at the upper end of the curved section 388 of each sub-tube section 386.

[0061] One of the multiple sub-pipe sections 386 is a sub-pipe section 386a for the flow pipe. The outlet 383 of the sub-pipe section 386a for the flow pipe is the outlet 383a for the flow pipe. The straight section 387 of the sub-pipe section 386a for the flow pipe is positioned along the side of the flow pipe 54. The side of the flow pipe 54 is, for example, the side of the flow pipe 54 opposite to the side facing the first guide section 40a. The curved section 388 curves to wrap around the side of the flow pipe 54. As a result, the outlet 383a for the flow pipe faces the opening 541.

[0062] The remaining of the multiple sub-pipe sections 386 are multiple sub-pipe sections 386b for the guide section. The outlets 383 of the multiple sub-pipe sections 386b for the guide section are multiple outlets 383b for the guide section. The straight section 387 of each sub-pipe section 386b for the guide section is arranged along the side of the first guide section 42 of the guide section 40 (first guide section 40a to third guide section 40c). The side of the first guide section 42 is, for example, the side opposite to the protruding direction of the second guide section 44. Each curved section 388 curves so as to wrap around the side of each guide section 40. As a result, the outlets 383b for the guide section face the gas inlet 46.

[0063] In the illustrated example, the discharge port 383a for the flow pipe is located below (lower) the opening 541, and the discharge port 383b for the guide section is located below the gas inlet 46. However, the discharge port 383a for the flow pipe may be at the same height as the opening 541, and the discharge port 383b for the guide section may be at the same height as the gas inlet 46.

[0064] As shown in Figure 5, in the culture apparatus 10B, a replacement gas G (for example, compressed air) is supplied to the stagnant algae RA in the section 542 from the outlet 383a of the sub-pipe 386a for the flow pipe. This replacement gas G pushes the stagnant algae RA out of the section 542. As a result, the stagnant algae RA are sent from the section 542 into the culture medium CS in the containment section 20. Also, similar to the first embodiment, the culture medium CS is guided by the first guide section 40a to the third guide section 40c, which generates convection in the culture medium CS. This agitates the culture medium CS, preventing microalgae from accumulating at the bottom of the containment section 20.

[0065] Therefore, the same effects as in the first embodiment can be obtained in the second embodiment as well.

[0066] In the second embodiment, a supply pipe 38B having a main pipe section 385 and a plurality of sub-pipe sections 386 is used. In this configuration, one of the plurality of sub-pipe sections 386 is designated as a sub-pipe section 386a for the flow pipe, and the outlet 383a for the flow pipe faces the opening 541 of the flow pipe 54. In this case, the culture gas flows easily into the flow pipe 54, making it easy to replace the microalgae in the flow pipe 54 with the culture gas.

[0067] Furthermore, since the culture gas easily rises along each of the multiple guide sections 40, convection is easily generated in the culture medium CS within the containment section 20.

[0068] Next, a modified example will be described with reference to Figures 6 to 8. In this modified example, supply pipe 38C is used. Supply pipe 38C is constructed similarly to supply pipe 38A shown in Figure 1. However, supply pipe 38C does not have a discharge port 383a for the flow pipe. Alternatively, a supply pipe can be used as a substitute for supply pipe 38C, by omitting the sub-pipe section 386a for the flow pipe from supply pipe 38B shown in Figure 5.

[0069] In the modified culture apparatus 10C, the supply and discharge section 51 includes a recovery tank 52, a flow pipe 54, a bidirectional pump 56, a three-way valve 70 as a switching valve 58, and a displacement gas supply line 72. The valve installation location 55 of the three-way valve 70 is the portion of the flow pipe 54 that is exposed from the culture medium CS.

[0070] The three-way valve 70 has a first port 701, a second port 702, and a third port 703. The replacement gas supply line 72 is connected to the second port 702. As a result, the replacement gas supply line 72 is connected to the flow pipe 54 via the three-way valve 70. The replacement gas supply line 72 is provided with a second gas on / off valve 74.

[0071] The culture apparatus 10C is equipped with a control unit 60. The control unit 60 controls the operation and stopping of the compressor 36, the gas shut-off valve 39, the three-way valve 70 (switching valve 58), the second gas shut-off valve 74, and the bidirectional pump 56. Figure 1 is shown for the control unit 60 and the gas shut-off valve 39.

[0072] In the modified configuration, upon receiving a "transfer start" command signal, the control unit 60 energizes the bidirectional pump 56 and sets the three-way valve 70 to a state where the first port 701 and the third port 703 are in communication, and the second port 702 and the third port 703 are blocked. This causes the flow pipe 54 to enter a flow state. Consequently, the culture solution CS and microalgae in the recovery tank 52 are sucked in by the bidirectional pump 56 and supplied to the containment unit 20 via the flow pipe 54.

[0073] As shown in Figure 7, when it is detected that a predetermined amount of culture solution CS and microalgae has been stored in the containment section 20, the control unit 60 sets the three-way valve 70 to a state where the communication between the first port 701 and the third port 703 is blocked and the second port 702 and the third port 703 are connected. Accordingly, the flow pipe 54 switches to a blocked state that blocks the flow of culture solution CS and microalgae. The control unit 60 then sends a "stop operation" command signal to the bidirectional pump 56.

[0074] At this stage, as in the first embodiment, retained algae RA are present in section 542. As shown in Figure 8, in order to discharge the retained algae RA from section 542, the control unit 60 energizes the compressor 36 and opens the second gas on / off valve 74. As a result, compressed air, which is the replacement gas G, flows into section 542 from the replacement gas supply line 72 via the three-way valve 70.

[0075] The replacement gas G (compressed air) supplied to section 542 via the three-way valve 70 has sufficient pressure. As a result, the replacement gas G pushes the stagnant algae RA in section 542 out into the containment section 20. Consequently, the stagnant algae RA in section 542 are replaced by the replacement gas G.

[0076] Thus, even in this modified form, the stagnant algae RA inside the pipe can be sent from section 542 to the culture medium CS in the containment section 20.

[0077] The following additional information is disclosed regarding the above embodiments.

[0078] (Note 1) The culture apparatus (10A~10C) of the present disclosure is a culture apparatus for culturing microalgae in a culture medium (CS), comprising: a containment section (20) capable of containing the culture medium and the microalgae; a culture gas supply section (30) for supplying culture gas to the culture medium contained in the containment section; a flow pipe (54) inserted into the containment section and extending along the depth direction of the containment section, through which the culture medium and the microalgae flow; and a portion of the flow pipe exposed from the culture medium, which controls the flow pipe to maintain a flow state in which the culture medium and the microalgae can flow, and the culture medium and The system includes a switching valve (58) that switches between a state that blocks the flow of the microalgae and a state that blocks the flow of the microalgae, and a replacement gas supply unit (32) that supplies a replacement gas (G) to replace the culture medium and microalgae that have accumulated inside the section (542) between the opening (541) located inside the containment section and the valve installation location (55) where the switching valve is provided, wherein the replacement gas supply unit supplies the replacement gas inside the section, thereby discharging the culture medium and microalgae inside the section into the containment section through the opening of the flow system.

[0079] As displacement gas is supplied to the section of the flow pipe, microalgae (retaining algae in the pipe) within that section are sent into the culture medium in the containment section. The microalgae sent out from the section then participate in cultivation in the containment section. This allows for the effective utilization of microalgae.

[0080] (Note 2) In the culture apparatus described in Appendix 1, the displacement gas supply unit also serves as the culture gas supply unit, and the culture gas may be supplied as the displacement gas.

[0081] In this case, the culture gas supply unit and the displacement gas supply unit can be configured as the same gas supply unit. This simplifies the configuration of the culture apparatus and reduces capital investment.

[0082] (Note 3) In the culture apparatus described in Appendix 2, a plurality of guide sections (40) are provided to guide the culture gas from the bottom of the containment section toward the liquid surface of the culture medium, the plurality of guide sections are spaced apart from each other and arranged in a line along the direction (X) within the containment section, and the culture gas supply section has a supply pipe (38A~38C) through which the culture gas flows and a plurality of outlets (383) for discharging the culture gas from the supply pipe, the plurality of outlets may have a flow pipe outlet (383a) for supplying the culture gas to the opening of the flow pipe and a plurality of guide section outlets (383b) for supplying the culture gas to each of the plurality of guide sections.

[0083] In this configuration, the culture gas discharged from each of the multiple outlets rises through the culture medium along the guide section, agitating the culture medium in the containment section. This agitation prevents microalgae from accumulating at the bottom of the containment section, thus allowing for efficient microalgae cultivation. Furthermore, since the displacement gas is also the culture gas, the continuous supply of displacement gas to the culture medium agitates the culture medium and allows for efficient microalgae cultivation.

[0084] (Note 4) In the culture apparatus described in Appendix 3, the supply pipe has a gas discharge section (382) that is inserted into the containment section and immersed in the culture medium, a plurality of outlets are formed in the gas discharge section, the outlet for the flow pipe supplies the culture gas toward the opening of the flow pipe at the same position as or below the opening of the flow pipe, and a plurality of outlets for the guide section may supply the culture gas toward the gas inlet at the same position as or below the gas inlet of the guide section.

[0085] With this configuration, the culture gas flows into the flow tube, making it easy to replace the microalgae in the flow tube with the culture gas. Also, since the culture gas easily rises along each of the multiple guide sections, convection is easily generated in the culture medium within the containment section.

[0086] (Note 5) In the culture apparatus described in Appendix 3, the supply pipe has a main pipe section (385) and a plurality of sub-pipe sections (386) that branch off from the main pipe section, are inserted into the containment section, and are immersed in the culture medium, and a plurality of outlets are formed in each of the plurality of sub-pipe sections, and the plurality of sub-pipe sections have a sub-pipe section for the flow pipe (386a) that supplies the culture gas to the flow pipe and a plurality of sub-pipe sections for the guide section (386b) that supplies the culture gas to each of the plurality of guide sections, and the sub-pipe section for the flow pipe has a discharge port for the flow pipe, and the discharge port for the flow pipe supplies the culture gas toward the opening of the flow pipe at the same position as the opening of the flow pipe or below the opening, and the plurality of sub-pipe sections for the guide section each have a plurality of discharge ports for the guide section, and the plurality of discharge ports for the guide section may supply the culture gas toward the gas inlet at the same position as the gas inlet of the guide section or below the gas inlet.

[0087] Since the culture gas, acting as a replacement gas, flows into the flow pipe, it is easy to replace the microalgae in the flow pipe with the replacement gas (culture gas). In addition, because the culture gas easily rises along each of the multiple guide sections, convection is easily generated in the culture medium within the containment section.

[0088] (Note 6) In the culture apparatus described in Appendix 5, the containment section has an inlet (22) located above the liquid surface of the culture medium, and the flow pipe and the plurality of sub-pipe sections may be inserted into the containment section through the inlet and immersed in the culture medium.

[0089] For example, if an inlet is formed on the side of the containment section, and the liquid level of the culture medium is above the inlet (higher), there is a concern that the culture medium and microalgae inside the containment section may leak out from between the inlet and the flow pipe or multiple sub-pipe sections. However, this concern is eliminated by the above configuration.

[0090] (Note 7) In the culture apparatus described in Appendix 3, the flow tube may be positioned at one end of the plurality of guide sections in the direction of alignment.

[0091] This prevents the flow tube from obstructing the convection of the culture medium.

[0092] (Note 8) In the culture apparatus described in Appendix 1, a plurality of the containment sections may be provided, and the flow pipe, which is equipped with the switching valve, may be inserted into the interior of each of the plurality of containment sections.

[0093] This configuration makes it possible to cultivate microalgae on an industrial scale.

[0094] (Note 9) In the culture apparatus described in any one of the appendices 1 to 8, a control unit (60) for controlling the switching valve and the replacement gas supply unit may be provided, wherein the control unit may stop the supply of the replacement gas from the replacement gas supply unit when the flow pipe is in the flow state, and supply the replacement gas from the replacement gas supply unit when the flow pipe is in the blocked state.

[0095] In this case, there is no need for the worker to manually operate the switching valve.

[0096] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the intent of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of Symbols]

[0097] 10A~10C...Culture apparatus 20...Storage section 22...Insertion port 30...Culture gas supply unit 32... Replacement gas supply unit 38A~38C... Supply pipe 40... Guide section 46... Gas inlet 52... Recovery tank 54... Flow pipe 55…Valve installation location 58…Switching valve 60...Control unit 70...Three-way valve 72... Replacement gas supply line 383... Discharge port 383a...Discharge port for flow pipe 383b...Discharge port for guide section 541...Opening 542...Section CS...Culture medium G...Replacement gas RA…Algae staying in the pipe

Claims

1. A culture apparatus for culturing microalgae in a culture medium, A containment section capable of containing the culture solution and the microalgae, A culture gas supply unit that supplies culture gas to the culture medium contained in the containment unit, A flow tube is inserted into the aforementioned containment section and extends along the depth direction of the containment section, through which the culture medium and the microalgae flow, The flow pipe is provided with a switching valve in the portion exposed to the culture medium, which switches the flow pipe between a flow state in which the culture medium and the microalgae can flow and a blocked state in which the flow of the culture medium and the microalgae is blocked. The flow pipe includes a replacement gas supply unit that supplies replacement gas to replace the culture medium and microalgae that have accumulated inside the section between the opening located within the containment section and the valve installation location where the switching valve is provided, Equipped with, A culture apparatus in which the displacement gas supply unit supplies the displacement gas into the interior of the section, thereby discharging the culture medium and microalgae inside the section into the containment section through the opening of the flow pipe.

2. A culture apparatus according to claim 1, wherein the replacement gas supply unit also serves as the culture gas supply unit, and the culture gas is supplied as the replacement gas.

3. The culture apparatus according to claim 2 is further comprising a plurality of guide parts for guiding the culture gas from the bottom of the containment section toward the liquid surface of the culture medium, wherein the plurality of guide parts are spaced apart from each other within the containment section and arranged in a line along the direction, The culture gas supply unit has a supply pipe through which the culture gas flows, and a plurality of outlets for discharging the culture gas from the supply pipe. A culture apparatus comprising a plurality of outlets, each having a flow pipe outlet for supplying the culture gas to the opening of the flow pipe and a plurality of guide outlets for supplying the culture gas to each of the guide sections.

4. In the culture apparatus according to claim 3, the supply pipe has a gas discharge section that is inserted into the containment section and immersed in the culture medium, and a plurality of outlets are formed in the gas discharge section. The discharge port for the flow pipe supplies the culture gas toward the opening of the flow pipe at the same position as the opening of the flow pipe or below the opening. A culture apparatus in which multiple discharge ports for the guide section supply the culture gas toward the gas inlet at the same position as or below the gas inlet of the guide section.

5. In the culture apparatus according to claim 3, the supply pipe has a main pipe section and a plurality of sub-pipe sections that branch off from the main pipe section, are inserted into the containment section, and are immersed in the culture medium, and the plurality of outlets are formed in each of the plurality of sub-pipe sections. Each of the multiple sub-tube sections comprises a sub-tube section for supplying the culture gas to the flow pipe, and a sub-tube section for supplying the culture gas to each of the multiple guide sections. The sub-pipe section for the flow pipe has a discharge port for the flow pipe, and the discharge port for the flow pipe supplies the culture gas toward the opening of the flow pipe at the same position as the opening of the flow pipe or below the opening. A culture apparatus comprising a plurality of sub-tubes for the guide section, each having a plurality of outlets for the guide section, the plurality of outlets for the guide section supplying the culture gas toward the gas inlet at the same position as the gas inlet of the guide section or below the gas inlet.

6. A culture apparatus according to claim 5, wherein the containment section has an inlet located above the liquid surface of the culture medium, and the flow pipe and the plurality of sub-pipe sections are inserted into the containment section from the inlet and immersed in the culture medium.

7. A culture apparatus according to claim 3, wherein the flow tube is arranged at one end in the direction of alignment of the plurality of guide portions.

8. A culture apparatus according to claim 1, wherein the apparatus comprises a plurality of containment sections, and the flow pipe, which is provided with the switching valve, is inserted into the interior of each of the plurality of containment sections.

9. A culture apparatus according to any one of claims 1 to 8, comprising a control unit that controls the switching valve and the replacement gas supply unit, A culture apparatus in which the control unit performs control to stop the supply of the replacement gas from the replacement gas supply unit when the flow pipe is in the flow state, and to supply the replacement gas from the replacement gas supply unit when the flow pipe is in the blocked state.

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