Culture device

Abstract

A culture device (10) is provided with a culture tank (12) having sidewalls that are formed from a translucent material, and cultures fine algae in a culture liquid (L2) that is accommodated in the culture tank (12) and through which light is emitted via the sidewalls. The culture device (10) is provided with a translucent insulating part (16) that covers the sidewalls. The insulating part (16) forms an air layer (52) that insulates the inside of the culture tank (12).

Description

[Technical field]

[0001] The present invention relates to a culture device for culturing microalgae. [Background technology]

[0002] For example, a culture device disclosed in JP2014-516550A is known. In this culture device, a culture solution is stored in a culture tank consisting of a V-shaped trough with an upper opening. In this culture device, microalgae are cultured in the culture solution while irradiating light from the upper opening of the culture tank in the depth direction of the culture solution. In this culture device, a foam insulation material is adhered to the side wall of the culture tank to improve the thermal insulation in the culture tank. This makes it possible to suppress the culture solution in the culture tank from being affected by changes in the external environment (e.g., outside air temperature or solar radiation intensity). As a result, it is possible to easily maintain the culture solution at a temperature suitable for culturing microalgae. This makes it possible to culture the microalgae well. Summary of the Invention

[0003] Meanwhile, a culture device has been proposed that includes a culture tank having a light-transmitting side wall. In this culture device, the microalgae are cultured while irradiating the microalgae with light from a direction intersecting the depth direction of the culture solution through the side wall. In this type of culture device, the ratio of the light receiving area to the culture volume of the microalgae can be easily increased, for example, compared to a culture device that irradiates light in the depth direction of the culture solution through an upper opening. This makes it possible to distribute light energy to a larger number of microalgae in the culture tank while suppressing excess or deficiency. This makes it possible to culture the microalgae well.

[0004] In a culture device in which light is irradiated into a culture tank through a side wall, it is possible to improve the thermal insulation inside the culture tank by attaching a foam insulation material to the side wall. However, when the foam insulation material is attached to the side wall, the foam insulation material prevents light from being irradiated through the side wall. For this reason, it has been difficult to increase the ratio of the light receiving area to the culture volume of microalgae while improving the thermal insulation inside the culture tank.

[0005] The present invention aims to solve the above-mentioned problems.

[0006] One aspect of the present invention is a culture apparatus having a culture tank with side walls formed from a light-transmitting material, which cultures microalgae in a culture solution contained in the culture tank and irradiated with light through the side walls, and which further comprises a light-transmitting insulating section covering the side walls, the insulating section forming an air layer that insulates the interior of the culture tank.

[0007] In this culture device, the sidewall of the light-transmitting culture tank is covered with a light-transmitting insulating part. Therefore, the inside of the culture tank is insulated by the air layer formed by the insulating part. In this case, light can be effectively irradiated into the inside of the culture tank through the insulating part, the air layer, and the sidewall, all of which are light-transmitting. As a result, the ratio of the light-receiving area to the culture volume of the microalgae can be increased, while the insulation inside the culture tank can be improved. Therefore, it is possible to effectively culture the microalgae. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic front view of a culture device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic front view illustrating a heat insulating section and a support mechanism of the culture apparatus in FIG. [Diagram 3] FIG. 3 is a schematic side view of the culture device illustrating a state in which the air layer is made thin by the support mechanism of FIG. [Figure 4] FIG. 4 is a schematic side view of the culture device illustrating a state in which the air layer is made thicker by the support mechanism of FIG. [Diagram 5] FIG. 5 is a schematic front view of the culture tank of the culture apparatus of FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is a schematic perspective view of a liquid storage tank of the culture device of FIG. [Figure 8] FIG. 8 is a schematic side view of a culture device illustrating a heat insulating part according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In the following drawings, components having the same or similar functions and effects are given the same reference symbols, and repeated explanations may be omitted.

[0010] The culture apparatus 10 according to this embodiment shown in FIG. 1 supplies light and a supply gas to microalgae in a culture solution L2 containing water. Examples of the supply gas include carbon dioxide gas or a carbon dioxide-containing gas (e.g., air). As a result, in the culture apparatus 10, the microalgae grow while performing photosynthesis. In other words, the culture apparatus 10 cultures the microalgae. In addition to water, the culture solution L2 contains nutrients (e.g., nitrogen, phosphorus, potassium) necessary for culturing the microalgae. The supply gas preferably contains carbon dioxide gas discharged from a factory or the like.

[0011] There are no particular limitations on the microalgae that can be cultured using the culture apparatus 10. When using the cultured microalgae to produce biofuels such as ethanol, it is preferable to culture microalgae classified into Chlorophyceae (e.g., Chlamydomonas, Chlorella), Prasinophyceae, Cryptophyceae, and Cyanobacteria (e.g., Spirulina) using the culture apparatus 10. A particularly suitable example of microalgae to be cultured using the culture apparatus 10 is the "HondaDREAMO strain" (deposited on April 22, 2016, accession number FERM BP-22306) deposited at the National Institute of Technology and Evaluation, Patent Organism Depositary Center (Room 120, 2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture).

[0012] The culture apparatus 10 is placed in an environment where the microalgae can be irradiated with light having a wavelength (e.g., 400 to 700 nm) necessary for the growth of the microalgae. An example of such an environment is outdoors where the microalgae can be irradiated with sunlight. However, the culture apparatus 10 may also be placed indoors where the microalgae can be irradiated with sunlight or artificial light.

[0013] In the following, the orientation of each component of the culture device 10 will be described based on the vertical direction (the direction of arrows X1 and X2 in FIG. 1), a first horizontal direction (the direction of arrows Y1 and Y2 in FIG. 1), and a second horizontal direction (the direction of arrows Z1 and Z2 in FIG. 1) perpendicular to the first horizontal direction when the culture device 10 is installed at an installation location where microalgae are cultivated, as shown in FIG. 1. Although not particularly limited, it is preferable that the first horizontal direction is the east-west direction and the second horizontal direction is the north-south direction.

[0014] As shown in Figs. 1 to 4, the culture device 10 includes a culture tank 12, a liquid storage tank 14, a heat insulating section 16, a support mechanism 18 (Figs. 2 to 4), a temperature sensor 20 (Figs. 3 and 4), a drive section 22 (Figs. 3 and 4), and a control section 24 (Figs. 3 and 4). As shown in Fig. 5, the culture tank 12 can accommodate microalgae and a culture solution L2. The culture tank 12 is formed from a material having flexibility and translucency, such as linear low density polyethylene (LLDPE). Note that translucency here means that light of a wavelength required for the growth of microalgae can be transmitted through the material. In this embodiment, the entire culture tank 12 is formed from a material having translucency. However, it is sufficient that at least the side surfaces (surfaces excluding the bottom surface and the top surface) of the culture tank 12 are formed from a material having translucency.

[0015] In this embodiment, a joint edge 26 is provided on the outer periphery (side and bottom) of the culture tank 12 excluding the upper end. The joint edge 26 is formed by joining the inner wall surfaces of the culture tank 12 together, for example, by welding. An opening that allows access to the inside of the culture tank 12 is provided at the upper end of the culture tank 12 where the joint edge 26 is not provided. Note that in FIG. 5, for convenience of explanation, the joints made by welding are indicated by diagonal lines.

[0016] The opening of the culture tank 12 may be always open toward the outside of the culture tank 12. The opening of the culture tank 12 may be configured to be openable and closable by an opening / closing part (not shown). When culturing microalgae with the opening open, the opening becomes a communication port 28 that communicates the inside and outside of the culture tank 12. It is possible to discharge exhaust gas from the inside of the culture tank 12 to the outside through this communication port 28. It is also possible for exhaust gas to enter the inside of the culture tank 12 from the outside again through the communication port 28. As described later, an example of the exhaust gas is the remaining gas that is not consumed in the photosynthesis of the microalgae out of the supply gas supplied from the gas supply port 30 into the culture tank 12. Another example of the exhaust gas is oxygen gas generated by photosynthesis.

[0017] On the other hand, when the opening of the culture tank 12 can be opened and closed, the opening may be, for example, normally closed. The opening may be opened only when accessing the inside of the culture tank 12, such as when recovering microalgae from the inside of the culture tank 12. When culturing microalgae with the opening closed in this manner, a communication port (not shown) that connects the inside and outside of the culture tank 12 is provided at the upper end of the culture tank 12 in addition to the opening. This makes it possible for exhaust gas to enter and exit the culture tank 12 through the communication port even when the opening is closed.

[0018] Furthermore, the culture tank 12 may not have an opening at the upper end. That is, the joint edge 26 may be provided on the entire outer periphery including the upper end of the culture tank 12. In this case, a communication port (not shown) that communicates the inside and outside of the culture tank 12 is provided at the upper end of the culture tank 12. This allows exhaust gas to enter and exit the culture tank 12 through the communication port. When the joint edge 26 is provided on the entire outer periphery of the culture tank 12 in this way, the culture tank 12 may be provided with, for example, a culture solution supply port and a microalgae recovery port, although neither are shown. It becomes possible to supply the culture solution L2 and the microalgae to the culture tank 12 through the culture solution supply port. It becomes possible to recover the microalgae cultured in the culture tank 12 through the microalgae recovery port.

[0019] The culture tank 12 is provided with partitions 32, joints 34, guides 36, circulation units 38, and gas supply ports 30. In this embodiment, the culture tank 12 is provided with two partitions 32, six joints 34, three guides 36, six circulation units 38, and three gas supply ports 30. However, the numbers of each of the partitions 32, joints 34, guides 36, circulation units 38, and gas supply ports 30 provided in the culture tank 12 are not particularly limited.

[0020] Each of the partitions 32, the joints 34, the guides 36, and the circulation section 38 extends vertically (up and down) inside the culture tank 12. Note that the extension directions of each of the partitions 32, the joints 34, the guides 36, and the circulation section 38 are not limited to being parallel to the vertical direction, and may be inclined relative to the vertical direction.

[0021] In this embodiment, the interior of the culture tank 12 is partitioned into three regions 40 aligned in a first horizontal direction (arrows Y1, Y2) by two partitions 32. With the regions 40 aligned in the first horizontal direction in this manner, the length of the culture tank 12 in the first horizontal direction is longer than the length in the second horizontal direction (arrows Z1, Z2).

[0022] The partitions 32 are formed by joining the inner wall surfaces of the culture tank 12 together, for example, by welding. Each region 40 in the culture tank 12 partitioned by the partitions 32 is further divided by a joint 34 formed by joining the inner wall surfaces of the culture tank 12 together, for example, by welding. As a result, each region 40 has one guide portion 36 and two circulation portions 38 arranged side by side on both sides of the guide portion 36 in the horizontal direction. Note that, for example, in order to suppress stress concentration, each of both ends in the extension direction of the partitions 32 and the joints 34 is preferably arc-shaped.

[0023] 6, when the culture solution L2 is contained in the culture tank 12, each of the guide part 36 and the circulation part 38 has a substantially cylindrical cross-sectional shape when viewed in the vertical direction. In this embodiment, the inner diameter of each circulation part 38 when viewed in the vertical direction is at least twice the inner diameter of the guide part 36 when viewed in the vertical direction, but is not particularly limited to this.

[0024] 5, the vertical length (extension direction) of the joint 34 and the partition 32 is shorter than the vertical length of the culture tank 12. Moreover, the vertical length of the partition 32 is equal to or greater than the vertical length of the joint 34. A guide inlet 42 that connects the guide 36 and the circulation unit 38 is formed below the joint 34 in the culture tank 12. Moreover, a guide outlet 44 that connects the guide 36 and the circulation unit 38 is formed above the joint 34 in the culture tank 12.

[0025] The gas supply port 30 is provided at the bottom of the culture tank 12. The gas supply port 30 is disposed below a guide portion 36 provided in each region 40 in the culture tank 12. As shown in FIG. 1, the gas supply port 30 is connected to a gas supply mechanism 50 via a gas supply pipe 48 provided with a supply fan 46. Therefore, the supply gas supplied from the gas supply mechanism 50 is supplied into the culture tank 12 via the gas supply pipe 48 and the gas supply port 30 by driving the supply fan 46.

[0026] As described above, the gas supply port 30 is provided below the guide part 36. Therefore, as shown in Fig. 5, the supply gas supplied into the culture tank 12 flows upward through the guide part 36. As a result, in each region 40 in the culture tank 12, a culture solution flow F is generated in which the culture solution L2 in the circulation part 38 flows into the guide part 36 from the guide part inlet 42, and the culture solution L2 in the guide part 36 flows out from the guide part outlet 44 into the circulation part 38.

[0027] 7, the liquid storage tank 14 is formed from a flexible and light-transmitting material such as linear low-density polyethylene (LLDPE) like the culture tank 12. The liquid storage tank 14 may be formed from a light-transmitting material such as acrylic resin, polycarbonate resin, or glass. In this embodiment, the entire liquid storage tank 14 is formed from a light-transmitting material. However, it is sufficient that at least the side surfaces (surfaces excluding the bottom and top surfaces) of the liquid storage tank 14 are formed from a light-transmitting material.

[0028] The liquid storage tank 14 stores therein the storage liquid L1 supplied from a storage liquid supply mechanism (not shown). The storage liquid L1 is a liquid having translucency such as water. As shown in FIGS. 1 to 4, the inner dimensions of the storage tank 14 are set to be larger than the outer dimensions of the culture tank 12. Therefore, the culture tank 12 can be installed inside the storage tank 14. Inside the storage tank 14, for example, an opening (communication port 28) at the upper end of the culture tank 12 is fixed above the liquid level of the storage liquid L1 in the storage tank 14. This prevents the storage liquid L1 from mixing with the culture liquid L2 in the culture tank 12. Also, the culture liquid L2 is prevented from mixing with the storage liquid L1 in the storage tank 14.

[0029] 1 to 4, 7, etc., show the liquid storage tank 14 in the form of a case with an open upper end. However, the liquid storage tank 14 may have various shapes capable of storing the storage liquid L1 therein and accommodating the culture tank 12. The liquid storage tank 14 may be, for example, bag-shaped. Furthermore, the culture device 10 does not necessarily have to include the liquid storage tank 14.

[0030] As shown in Figs. 1 to 4, the heat insulating section 16 is made of a material having translucency. The heat insulating section 16 covers the side wall of the culture tank 12. As a result, the heat insulating section 16 forms an air layer 52 that insulates the inside of the culture tank 12. In this embodiment, the heat insulating section 16 is formed in a sheet shape from a resin having translucency and flexibility, for example. The heat insulating section 16 is supported by a support mechanism 18 (Figs. 2 to 4) as described later. The heat insulating section 16 covers the side wall of the culture tank 12 from the outside of the side wall of the liquid storage tank 14. The heat insulating section 16 and the side wall of the liquid storage tank 14 are arranged with a predetermined gap between them. As a result, an air layer 52 is formed between the heat insulating section 16 and the side wall of the liquid storage tank 14.

[0031] As shown in Figs. 2 to 4, the heat insulating section 16 has a first heat insulating sheet 56 and a set of second heat insulating sheets 58. As shown in Figs. 3 and 4, the first heat insulating sheet 56 has a first portion 60, a second portion 62, and a third portion 64. The first portion 60 and the second portion 62 face each other across the culture tank 12 installed at the installation location in the second horizontal direction (the direction of the arrows Z1 and Z2). That is, the first portion 60 covers the side wall of the culture tank 12 on the arrow Z1 side. The second portion 62 covers the side wall of the culture tank 12 on the arrow Z2 side. The third portion 64 covers the upper surface (communication port 28) of the culture tank 12. The upper end of the first portion 60 and the upper end of the second portion 62 are continuous via the third portion 64. Therefore, the first heat insulating sheet 56 is in a band shape with the first horizontal direction (the direction of the arrows Y1 and Y2) as the width direction. Note that a portion of the first insulation sheet 56 extending in the direction of arrow Z1 beyond the first portion 60 may be fixed to the ground, for example, by a sheet fixing portion 66. A portion of the first insulation sheet 56 extending in the direction of arrow Z2 beyond the second portion 62 may be wound around a winding roller 68, for example.

[0032] As shown in Fig. 2, one of the pair of second insulating sheets 58 covers the side wall of the culture tank 12 installed at the installation location in the direction of the arrow Y1. The other of the pair of second insulating sheets 58 covers the side wall of the culture tank 12 in the direction of the arrow Y2. Each of the second insulating sheets 58 is provided so as to be stretchable in the second horizontal direction. The material forming the second insulating sheet 58 may itself be stretchable in the second horizontal direction. In addition, the second insulating sheet 58 may be provided with a stretchable structure such as a bellows structure or gathers (neither of which are shown in the figures) so as to be stretchable in the second horizontal direction.

[0033] The support mechanism 18 supports the heat insulating section 16 so that the first portion 60 and the second portion 62 can move relatively close to or apart from each other. Specifically, the support mechanism 18 includes two first supports 70 and two second supports 72. Each of these first supports 70 and second supports 72 extends vertically from the lower end of the culture tank 12 installed at the installation location to above the upper end of the culture tank 12. The number of each of the first supports 70 and second supports 72 is not particularly limited, and may be one or three or more.

[0034] 2, the two first pillars 70 are arranged in parallel and spaced apart along the width direction (directions of arrows Y1 and Y2) of the first portion 60. One of the two first pillars 70 is disposed at one end of the first portion 60 in the width direction (end in the direction of arrow Y1). The other of the two first pillars 70 is disposed at the other end of the first portion 60 in the width direction (end in the direction of arrow Y2).

[0035] The two second support pillars 72 (FIGS. 3 and 4) are arranged in parallel with a gap in the width direction (arrows Y1 and Y2 directions) of the second portion 62. One of the two second support pillars 72 is disposed at one end of the second portion 62 in the width direction (end in the arrow Y1 direction). The other of the two second support pillars 72 is disposed at the other end of the second portion 62 in the width direction (end in the arrow Y2 direction). Of the two second support pillars 72, the one disposed at the end in the arrow Y1 direction is not shown in the figures.

[0036] As shown in Figs. 3 and 4, at the end in the direction of the arrow Y2, the first support 70 and the second support 72 face each other with a gap in the directions of the arrows Z1 and Z2. Between the upper end of the first support 70 and the upper end of the second support 72, a telescopic support part 74 extending in the directions of the arrows Z1 and Z2 is provided. One end of the telescopic support part 74 in the extending direction (the end in the direction of the arrow Z1) is fixed to the first support 70. The other end of the telescopic support part 74 in the extending direction (the end in the direction of the arrow Z2) is fixed to the second support 72. The telescopic support part 74 has a nested structure in which, for example, the inner shaft part 78 is inserted inside the outer cylinder part 76. As a result, the telescopic support part 74 is configured to be telescopic in the directions of the arrows Z1 and Z2.

[0037] Although not specifically shown in the drawings, the first support pillar 70 and the second support pillar 72 at the end in the direction of the arrow Y1 face each other at a distance in the directions of the arrows Z1 and Z2, similar to the first support pillar 70 and the second support pillar 72 at the end in the direction of the arrow Y2. Also, between the upper end of the first support pillar 70 at the end in the direction of the arrow Y1 and the upper end of the second support pillar 72, an expandable support part 74 is provided so as to be expandable and contractible in the directions of the arrows Z1 and Z2, similar to between the upper end of the first support pillar 70 at the end in the direction of the arrow Y1 and the upper end of the second support pillar 72.

[0038] The first support 70 and the second support 72 are driven by the drive unit 22. This allows the first support 70 and the second support 72 to move relatively closer to or away from each other along the second horizontal direction (the directions of the arrows Z1 and Z2). At this time, the culture tank 12 and the liquid storage tank 14 are interposed between the first support 70 and the second support 72. When the drive unit 22 moves the first support 70 and the second support 72 closer to or away from each other, the expandable support unit 74 provided between them also expands and contracts accordingly.

[0039] In this embodiment, both the first support 70 and the second support 72 are movable in the second horizontal direction by the driving unit 22. However, the configuration for changing the horizontal distance between the first support 70 and the second support 72 is not limited to the above configuration. For example, either the first support 70 or the second support 72 may be fixed to the ground or the like. In this case, only the other of the first support 70 and the second support 72 is movable in the second horizontal direction by the driving unit 22. As the driving unit 22, a known configuration capable of moving the first support 70 and the second support 72 as described above can be adopted, and therefore a detailed description thereof will be omitted.

[0040] As shown in Figs. 2 to 4, a first lower end support portion 82 is provided at the lower end of the first support pillar 70 via a fixing portion 80. A first upper end support portion 84 is provided at the upper end of the first support pillar 70. At least one of the first lower end support portion 82 and the first upper end support portion 84 extends along the directions of the arrows Y1 and Y2, thereby connecting the parallel first support pillars 70 to each other. Note that in Figs. 2 to 4, both the first lower end support portion 82 and the first upper end support portion 84 extend along the directions of the arrows Y1 and Y2, thereby connecting the parallel first support pillars 70 to each other.

[0041] Moreover, each of the first lower end support part 82 and the first upper end support part 84 is rotatable with respect to the first support column 70 about the directions of the arrows Y1 and Y2 as axial directions. The first lower end support part 82 is fixed to the first support column 70 via a fixing part 80. As a result, the first lower end support part 82 is disposed farther away from the liquid storage tank 14 (closer to the end in the direction of the arrow Z1) than the first upper end support part 84.

[0042] A second lower end support portion 86 is provided at the lower end of the second support pillar 72 via a fixing portion 80. A second upper end support portion 88 is provided at the upper end of the second support pillar 72. At least one of the second lower end support portion 86 and the second upper end support portion 88 extends along the directions of the arrows Y1 and Y2 to connect the parallel second support pillars 72 to each other. Note that in Figs. 2 to 4, both the second lower end support portion 86 and the second upper end support portion 88 extend along the directions of the arrows Y1 and Y2 to connect the parallel second support pillars 72 to each other.

[0043] Additionally, each of the second lower end support part 86 and the second upper end support part 88 is rotatable with respect to the second support column 72 about its axial direction in the direction of the arrows Y1 and Y2. The second lower end support part 86 is fixed to the second support column 72 via a fixing part 80. As a result, it is disposed farther away from the liquid storage tank 14 (closer to the end in the direction of the arrow Z2) than the second upper end support part 88.

[0044] The first insulation sheet 56 is supported by the support mechanism 18. As a result, the first portion 60 extends from the first lower end support portion 82 toward the first upper end support portion 84. Also, the second portion 62 extends from the second upper end support portion 88 toward the second lower end support portion 86. Furthermore, the third portion 64 extends in the second horizontal direction from the first upper end support portion 84 toward the second upper end support portion 88.

[0045] In this embodiment, the first insulation sheet 56 extends from the sheet fixing portion 66 along the second horizontal direction, and then changes its extension direction to the vertical direction by contacting the lower portion of the first lower end support portion 82. The first insulation sheet 56 also changes its extension direction to the second horizontal direction by contacting the upper portion of the first upper end support portion 84. The first insulation sheet 56 also changes its extension direction to the vertical direction by contacting the upper portion of the second upper end support portion 88. The first insulation sheet 56 also changes its extension direction to the second horizontal direction by contacting the lower portion of the second lower end support portion 86.

[0046] With the first insulation sheet 56 supported by the support mechanism 18 as described above, the first support 70 and the second support 72 are brought closer to each other by the drive unit 22 as shown in Fig. 3. This allows the first portion 60 and the second portion 62 to be brought closer to each other. As a result, the air layer 52 formed between the first insulation sheet 56 and the side wall of the culture tank 12 can be made thinner.

[0047] 4, the first portion 60 and the second portion 62 can be separated by moving the first support 70 and the second support 72 away from each other using the drive unit 22. As a result, the air layer 52 formed between the first insulation sheet 56 and the side wall of the culture tank 12 can be made thicker.

[0048] Each of the first lower end support portion 82, the first upper end support portion 84, the second lower end support portion 86, and the second upper end support portion 88 is rotatable while in contact with the first insulation sheet 56. This reduces the frictional force generated between the first insulation sheet 56 and the support mechanism 18, allowing the first portion 60 and the second portion 62 to be moved closer to or apart from each other smoothly.

[0049] Furthermore, by bringing the first portion 60 and the second portion 62 closer to each other as described above, the length of the third portion 64 may be excessive relative to the distance between the first support 70 and the second support 72. In this case, for example, the winding roller 68 is rotated in the direction in which the first insulation sheet 56 is wound up. This makes it possible to eliminate the excess portion and to make the first insulation sheet 56 fit well along the side and top surfaces of the culture tank 12.

[0050] On the other hand, by separating the first portion 60 and the second portion 62 as described above, the length of the third portion 64 may be insufficient relative to the distance between the first support 70 and the second support 72. In this case, for example, the winding roller 68 is rotated in the direction in which the first insulation sheet 56 is unwound. This makes it possible to eliminate the insufficiency and to make the first insulation sheet 56 fit well along the side and top surfaces of the culture tank 12.

[0051] Instead of rotating the winding roller 68 as described above, or in addition to rotating the winding roller 68, the first insulation sheet 56 made of an elastic material may be expanded or contracted according to the distance between the first support pillar 70 and the second support pillar 72. This also makes it possible to eliminate any excess or deficiency in the lengths of the first portion 60, the second portion 62, and the third portion 64 that occurs when the first portion 60 and the second portion 62 are moved closer to or farther apart.

[0052] One of the pair of second insulating sheets 58 is supported by the expandable support part 74 at the end in the arrow Y1 direction, thereby covering the side wall of the end in the arrow Y1 direction of the culture tank 12 (liquid storage tank 14). The other of the pair of second insulating sheets 58 is supported by the expandable support part 74 at the end in the arrow Y2 direction, thereby covering the side wall of the end in the arrow Y2 direction of the culture tank 12 (liquid storage tank 14). Each of these second insulating sheets 58 expands and contracts in the second horizontal direction in response to the expansion and contraction of the expandable support part 74. As a result, even if the first support 70 and the second support 72 are moved closer to or farther apart as described above, the side walls at both ends in the first horizontal direction of the culture tank 12 are maintained in a state covered by the second insulating sheet 58.

[0053] The heat insulating section 16 is supported by the support mechanism 18 as described above to form a closed space 90 that houses the culture tank 12 inside. As shown in Fig. 1, a piping insertion port 92 is provided at the bottom of the heat insulating section 16. A gas supply piping 48 for connecting the gas supply port 30 of the culture tank 12 to a gas supply mechanism 50 provided outside the closed space 90 is inserted into the piping insertion port 92.

[0054] Further, a gas exhaust port 94 is provided on the upper part of the heat insulating section 16. The gas exhaust port 94 enables the exhaust gas discharged from the culture tank 12 to the closed space 90 through the communication port 28 to be discharged from the closed space 90. One end of a gas recovery pipe 98 is connected to the gas exhaust port 94. The gas recovery pipe 98 is provided with an exhaust fan 96. The gas recovery pipe 98 recovers the exhaust gas discharged from the gas exhaust port 94 by driving the exhaust fan 96. The other end of the gas recovery pipe 98 is connected to a part of the gas supply pipe 48 upstream of the supply fan 46. Therefore, the exhaust gas recovered in the gas recovery pipe 98 can be supplied to the culture solution L2 in the culture tank 12 through the gas supply pipe 48 and the gas supply port 30.

[0055] 3 and 4, the temperature sensor 20 is provided, for example, inside the closed space 90. The temperature sensor 20 measures the temperature of the culture solution L2 in the culture tank 12. The temperature sensor 20 may be of a contact type that measures the temperature by contacting the culture solution L2 in the culture tank 12. The temperature sensor 20 may be of a non-contact type that measures the temperature without contacting the culture solution L2. The measurement value of the temperature sensor 20 is sent to the control unit 24.

[0056] The control unit 24 is configured as, for example, a microcomputer equipped with a CPU (not shown) or the like. The control unit 24 executes a predetermined calculation according to a control program to perform various processes and controls related to the culture device 10. The control unit 24 controls the drive unit 22 so that the distance between the first portion 60 and the second portion 62 (the thickness of the air layer 52) becomes a length corresponding to the measurement value of the temperature sensor 20.

[0057] For example, the higher the measured value of the temperature sensor 20, the closer the first part 60 and the second part 62 are brought to the controller 24. This makes the air layer 52 formed between the first insulating sheet 56 and the side wall of the culture tank 12 thinner. This reduces the heat insulation of the air layer 52. This makes it easier to release the heat of the culture solution L2 in the culture tank 12 to the outside of the closed space 90. On the other hand, the smaller the measured value of the temperature sensor 20, the farther the first part 60 and the second part 62 are brought to the controller 24. This makes the air layer 52 formed between the first insulating sheet 56 and the side wall of the culture tank 12 thicker. This increases the heat insulation of the air layer 52. This prevents the heat of the culture solution L2 in the culture tank 12 from being transmitted to the outside of the closed space 90. In addition to the measured value of the temperature sensor 20, the controller 24 may adjust the thickness of the air layer 52 based on, for example, the sunlight intensity detected by a sunlight sensor (not shown). The control unit 24 may adjust the thickness of the air layer 52 based on a preset calendar or the like.

[0058] The culture device 10 according to this embodiment is basically configured as described above. An example of a method for culturing microalgae using the culture device 10 will be described. When culturing microalgae using the culture device 10, first, as shown in Figs. 1 to 4, the culture tank 12 is placed in the stored liquid L1 in the liquid storage tank 14. In this state, the culture liquid L2 supplied from a culture liquid supply mechanism (not shown) is accommodated inside the culture tank 12. The culture liquid L2 is supplied into the culture tank 12 within the stored liquid L1. This makes it possible to prevent the culture tank 12 from being damaged by the liquid pressure of the culture liquid L2.

[0059] Next, as shown in Figs. 1 and 5, the supply gas supplied from the gas supply mechanism 50 is supplied toward the guide portion 36 of each region 40 in the culture tank 12 via the gas supply pipe 48 and the gas supply port 30 by driving the supply fan 46. As a result, as shown in Fig. 5, a culture solution flow F can be generated in each region 40 of the culture tank 12. Therefore, the microalgae can be circulated together with the culture solution L2 in the culture tank 12. This allows the microalgae to be well dispersed. This allows the supply gas or light, etc. to be effectively supplied to the entire microalgae.

[0060] The stored liquid L1 is translucent. The heat insulating section 16 is made of a translucent material. The side walls of the culture tank 12 and the liquid storage tank 14 are each made of a translucent material. Therefore, light such as sunlight can be irradiated onto the microalgae through the heat insulating section 16 and the side walls of the culture tank 12 and the liquid storage tank 14. This ensures a large light receiving area relative to the culture volume of the microalgae compared to culture in a so-called open pond (raceway pond). As a result, it becomes possible to distribute light energy to a larger amount of microalgae in the culture tank 12 while preventing excess or deficiency.

[0061] The microalgae perform photosynthesis using carbon dioxide in the supply gas, light, and water in the culture solution L2. As a result, the microalgae grow and proliferate while accumulating starch and the like in the cells. The surplus of the supply gas that is not used for this photosynthesis is discharged from the culture tank 12 to the closed space 90 through the communication port 28 and becomes exhaust gas. In other words, the exhaust gas contains carbon dioxide gas. Therefore, by surrounding the culture tank 12 with the heat insulating part 16 to form the closed space 90, the carbon dioxide gas concentration around the culture tank 12 can be increased. This makes it easier to supply the carbon dioxide gas in the closed space 90 to the culture solution L2 again through the communication port 28. This makes it possible to improve the utilization efficiency of the carbon dioxide gas supplied from the gas supply mechanism 50.

[0062] When the exhaust gas discharged from the communication port 28 exceeds the volume of the closed space 90, the exhaust gas is discharged from the closed space 90. In this case, the exhaust gas discharged into the closed space 90 through the communication port 28 is recovered into the gas recovery pipe 98 through the gas exhaust port 94 provided on the upper part of the heat insulating section 16 by driving the exhaust fan 96. The exhaust gas recovered into the gas recovery pipe 98 is supplied again to the culture solution L2 in the culture tank 12 through the gas supply pipe 48 and the gas supply port 30 under the driving of the supply fan 46. This also makes it possible to improve the utilization efficiency of carbon dioxide gas.

[0063] Furthermore, when culturing microalgae in the culture tank 12 as described above, the temperature sensor 20 measures the temperature of the culture solution L2 in the culture tank 12. Furthermore, the control unit 24 controls the drive unit 22 based on the measurement value of the temperature sensor 20. As a result, the air layer 52 formed between the side wall of the culture tank 12 and the first insulation sheet 56 is adjusted to a thickness suitable for culturing microalgae. For example, the thickness of the air layer 52 may be adjusted based on the sunlight intensity and the calendar so that the inside of the culture tank 12 is maintained in an environment suitable for culturing microalgae.

[0064] It should be noted that the driving unit 22 is not limited to being controlled by the control unit 24. The driving unit 22 may be configured to adjust the thickness of the air layer 52 by operation by an operator. Furthermore, the support mechanism 18 is not limited to being driven by the driving unit 22. The support mechanism 18 may be configured to adjust the thickness of the air layer 52 by manually adjusting the distance between the first support column 70 and the second support column 72 by an operator.

[0065] As described above, the culture tank 12 is disposed in the storage liquid L1 stored in the storage tank 14. This prevents the culture liquid L2 and the microalgae in the culture tank 12 from being affected by changes in the external environment (e.g., outside air temperature, solar radiation intensity, amount of solar radiation, or duration of solar radiation) of the culture device 10. This makes it easy to maintain the temperature of the culture liquid L2 in the culture tank 12 at a temperature suitable for culturing the microalgae.

[0066] By culturing the microalgae as described above, the microalgae are sufficiently grown in the culture tank 12. Thereafter, the microalgae are collected together with the culture solution L2 from inside the culture tank 12, for example, through the communication port 28 exposed from the insulating section 16. Thereafter, the microalgae can be obtained by separating the microalgae from the culture solution L2.

[0067] As described above, in the culture device 10 according to this embodiment, the side wall of the light-transmitting culture tank 12 is covered with the light-transmitting heat insulating section 16. The inside of the culture tank 12 is insulated by the air layer 52 formed by this heat insulating section 16. The heat insulating section 16, the air layer 52, and the side wall are all light-transmitting. Therefore, light can be effectively irradiated into the inside of the culture tank 12 through the heat insulating section 16, the air layer 52, and the side wall. As a result, the ratio of the light-receiving area to the culture volume of the microalgae can be increased, while the heat insulating property inside the culture tank 12 can be improved. This makes it possible to effectively culture the microalgae.

[0068] In the culture device 10 according to the above embodiment, the heat insulating section 16 is in the form of a flexible sheet, and the air layer 52 is formed between the side walls arranged at an interval and the heat insulating section 16. With this simple configuration in which the flexible sheet-like heat insulating section 16 is arranged at an interval from the side walls of the culture tank 12, it is possible to increase the heat insulation inside the culture tank 12 without impeding the irradiation of light to the microalgae.

[0069] In the culture apparatus 10 according to the above embodiment, the heat insulating section 16 covers the side wall and the upper surface of the culture tank 12. In this way, the heat insulating section 16 forms an air layer 52 also on the upper surface of the culture tank 12, thereby improving the thermal insulation inside the culture tank 12.

[0070] The culture tank 12 of the culture device 10 according to the above embodiment is provided with a gas supply port 30 that enables a supply gas to be supplied to the culture solution L2 in the culture tank 12, and a communication port 28 that connects the inside and outside of the culture tank 12 is provided on the upper surface of the culture tank 12. The insulation section 16 forms a closed space 90 that houses the culture tank 12 inside, and a gas exhaust port 94 is provided on the upper part of the insulation section 16 to enable exhaust gas discharged from the culture tank 12 to the closed space 90 via the communication port 28 to be discharged from the closed space 90.

[0071] By forming the closed space 90 by the heat insulating section 16 in this manner, it is possible to improve the heat insulation in the culture tank 12 and to make it easier to keep the carbon dioxide gas contained in the exhaust gas around the culture tank 12. This makes it possible to supply the carbon dioxide gas contained in the exhaust gas again to the culture solution L2 in the culture tank 12 via the communication port 28. This makes it possible to improve the utilization efficiency of the carbon dioxide gas supplied from the gas supply mechanism 50.

[0072] In addition, a gas exhaust port 94 is provided in the heat insulating section 16. This makes it possible to prevent the heat insulating section 16 from being damaged by the pressure of the exhaust gas discharged into the closed space 90. Carbon dioxide gas is heavier than air and tends to gather at the bottom of the closed space 90. Therefore, by providing the gas exhaust port 94 at the top of the heat insulating section 16, it becomes relatively easy to increase the concentration of carbon dioxide gas in the closed space 90.

[0073] In the culture apparatus 10 according to the above embodiment, the gas supply port 30 is connected to the gas supply mechanism 50 via the gas supply piping 48, one end of a gas recovery piping 98 that recovers the exhaust gas discharged from the gas exhaust port 94 is connected to the gas exhaust port 94, and the other end of the gas recovery piping 98 is connected to the gas supply piping 48. The exhaust gas recovered in the gas recovery piping 98 is supplied to the culture solution L2 in the culture tank 12 via the gas supply piping 48 and the gas supply port 30.

[0074] This makes it possible to supply the carbon dioxide gas contained in the exhaust gas discharged from the closed space 90 to the gas supply port 30 of the culture tank 12. That is, it becomes possible to circulate the carbon dioxide gas between the culture tank 12 and the closed space 90. Therefore, the utilization efficiency of the carbon dioxide gas supplied from the gas supply mechanism 50 can be further effectively improved.

[0075] The culture device 10 according to the above embodiment is provided with a support mechanism 18 that supports the insulating section 16. The insulating section 16 has a first part 60 and a second part 62 that face each other horizontally across the culture tank 12 installed at the installation location, and the support mechanism 18 supports the insulating section 16 so that the first part 60 and the second part 62 can move closer to or farther apart relative to each other.

[0076] According to this, the distance between the first portion 60 and the second portion 62 can be adjusted by the support mechanism 18. This allows the thickness of the air layer 52 formed between the heat insulating section 16 and the side wall of the culture tank 12 to be adjusted. Therefore, the thickness of the air layer 52 can be adjusted according to, for example, the temperature of the culture solution L2 in the culture tank 12 and the environment (external environment) of the installation location where the culture tank 12 is installed. This makes it easy to maintain the inside of the culture tank 12 in an environment suitable for culturing microalgae.

[0077] In the culture device 10 according to the above embodiment, the support mechanism 18 has a first support 70 and a second support 72, and each of the first support 70 and the second support 72 extends vertically from the lower end of the culture tank 12 installed at the installation location to above the upper end of the culture tank 12, and a first lower end support portion 82 is provided at the lower end of the first support 70, a first upper end support portion 84 is provided at the upper end of the first support 70, a second lower end support portion 86 is provided at the lower end of the second support 72, and a second upper end support portion 87 is provided at the upper end of the second support 72. An upper end support portion 88 is provided, and the first support portion 70 and the second support portion 72 can move relatively close to or apart from each other along the horizontal direction with the culture tank 12 interposed between them, and the first portion 60 extends from the first lower end support portion 82 toward the first upper end support portion 84, and the second portion 62 extends from the second upper end support portion 88 toward the second lower end support portion 86, and the first portion 60 and the second portion 62 are continuous via the third portion 64 which extends horizontally from the first upper end support portion 84 toward the second upper end support portion 88.

[0078] According to this, the distance between the first portion 60 and the second portion 62 can be easily adjusted by moving the first support 70 and the second support 72 closer to or farther apart. Furthermore, the thickness of the air layer 52 formed between the insulation part 16 and the side wall of the culture tank 12 can be easily adjusted.

[0079] In the culture device 10 of the above embodiment, the first supports 70 are arranged in parallel in multiple rows along the width direction of the first part 60, and at least one of the first lower end support portion 82 and the first upper end support portion 84 extends along the width direction of the first part 60 to connect the parallel first supports 70 to each other, and the second supports 72 are arranged in parallel in multiple rows along the width direction of the second part 62, and at least one of the second lower end support portion 86 and the second upper end support portion 88 extends along the width direction of the second part 62 to connect the parallel second supports 72 to each other.

[0080] With this, the first insulation sheet 56 of the insulation section 16 can be well supported by at least one of the first lower end support portion 82 and the first upper end support portion 84 extending along the width direction of the first portion 60. Similarly, the first insulation sheet 56 of the insulation section 16 can be well supported by at least one of the second lower end support portion 86 and the second upper end support portion 88 extending along the width direction of the second portion 62.

[0081] Moreover, the parallel first supports 70 are connected to each other by at least one of the first lower end support portion 82 and the first upper end support portion 84, thereby suppressing deformation of the support mechanism 18. The parallel second supports 72 are connected to each other by at least one of the second lower end support portion 86 and the second upper end support portion 88, thereby suppressing deformation of the support mechanism 18. In other words, the support mechanism 18 can be firmly configured. This makes it possible to maintain the state in which the heat insulating section 16 is supported by the support mechanism 18 in a good condition.

[0082] The culture device 10 according to the above embodiment includes a temperature sensor 20 that measures the temperature of the culture solution L2 in the culture tank 12, a drive unit 22 that drives the first portion 60 and the second portion 62 in a direction to move them closer to or away from each other, and a control unit 24 that controls the drive unit 22 so as to adjust the distance between the first portion 60 and the second portion 62 according to the measurement value of the temperature sensor 20. This makes it possible for the control unit 24 to automatically adjust the distance between the first portion 60 and the second portion 62 based on the measurement result of the temperature sensor 20. This makes it even easier to maintain the inside of the culture tank 12 in an environment suitable for culturing microalgae.

[0083] The present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

[0084] For example, in the above embodiment, the heat insulating section 16 is in the form of a flexible sheet, and an air layer 52 is formed between the side wall and the heat insulating section 16, which are spaced apart from each other. However, the present invention is not particularly limited to this. For example, the culture device 10 may be provided with a heat insulating section 100 shown in FIG. 8, instead of the heat insulating section 16 shown in FIGS. 1 to 4. The heat insulating section 100 in FIG. 8 is, for example, an aerogel having heat insulating properties and permeability, such as silica aerogel. The heat insulating section 100 is disposed along the side wall of the culture tank 12. According to this, an air layer 102 that insulates the inside of the culture tank 12 is formed in the pores of the aerogel.

[0085] In this way, even when the heat insulating part 100 is made of aerogel, light can be well irradiated into the inside of the culture tank 12 through the heat insulating part 100, the air layer 102, and the side wall. Therefore, the ratio of the light receiving area to the culture volume of the microalgae can be increased while improving the heat insulating property in the culture tank 12. This makes it possible to well culture the microalgae. Moreover, in this case, the heat insulating property in the culture tank 12 can be improved by a simple configuration in which the heat insulating part 100 is aligned with the side wall of the culture tank 12. In addition, since the aerogel is relatively light, even if the heat insulating part 100 falls over the culture tank 12 and collides with the culture tank 12, damage to the culture tank 12 can be avoided.

[0086] In the above embodiment, inside the culture tank 12, a guide section 36 and a circulation section 38 are provided side by side in the horizontal direction, extending along the vertical direction when the culture tank 12 is installed at the installation location. The guide section 36 and the circulation section 38 communicate with each other via a guide section inlet 42 provided at the lower part in the vertical direction and a guide section outlet 44 provided at the upper part in the vertical direction. A gas supply port 30 that can supply gas from the bottom to the top of the guide section 36 is provided at the bottom of the culture tank 12. When gas is supplied from the gas supply port 30 to the guide section 36, a culture solution flow F is generated in which the culture solution L2 in the circulation section 38 flows into the guide section 36 from the guide section inlet 42, and the culture solution L2 in the guide section 36 flows out from the guide section outlet 44 into the circulation section 38.

[0087] According to this, a culture solution flow F can be generated in the culture tank 12 by a simple configuration in which gas required for culturing microalgae is supplied from the gas supply port 30 and circulated through the guide portion 36. Moreover, there is no need to provide and drive a special configuration for generating the culture solution flow F, such as a water pump. Therefore, it is possible to successfully cultivate microalgae with a simple configuration while suppressing an increase in energy consumption.

[0088] However, there is no particular limitation on the configuration of the culture tank 12. For example, in the culture tank 12, a culture liquid flow may be generated by a water pump (not shown) to circulate the culture liquid L2 in the culture tank 12.

Claims

1. A culture device (10) having a culture tank (12) with a side wall formed from a light-transmitting material, and culturing microalgae in a culture solution (L2) contained in the culture tank and irradiated with light through the side wall, The liquid storage tank (14) is made of a light-transmitting material and has a light-transmitting liquid (L1) stored therein. The culture tank is placed in the storage liquid stored in the storage tank, A light-transmitting heat insulating part (16, 100) is provided to cover the liquid storage tank, The heat insulating part forms an air layer (52, 102) between the heat insulating part and the liquid storage tank to insulate the inside of the culture tank, A culture apparatus in which light is irradiated into an inside of the liquid storage tank through the insulation section, the air layer, the liquid storage tank, and the side wall of the culture tank.

2. In the culture device according to claim 1, The heat insulating portion is an aerogel, The culture device, wherein the air layer is formed within the pores of the aerogel.

3. In the culture device according to claim 1, The heat insulating portion is in the form of a flexible sheet, A culture apparatus, wherein the air layer is formed between the liquid storage tank and the heat insulating section, which are arranged with a gap between them.

4. In the culture apparatus according to claim 3, The culture device, wherein the heat insulating section covers a side wall of the liquid storage tank, an upper surface of the liquid storage tank, and an upper surface of the culture tank.

5. In the culture apparatus according to claim 4, The culture tank is provided with a gas supply port (30) that can supply a supply gas to the culture solution in the culture tank, A communication port (28) that communicates the inside and outside of the culture tank is provided on the upper surface of the culture tank, The heat insulating section forms a closed space (90) that houses the culture tank inside, A culture apparatus, wherein a gas exhaust port (94) is provided at an upper portion of the heat insulating section, which enables exhaust gas discharged from the culture tank through the communication port into the closed space to be discharged from the closed space.

6. The culture apparatus according to claim 5, The gas supply port is connected to a gas supply mechanism (50) via a gas supply pipe (48); One end of a gas recovery pipe (98) that recovers the exhaust gas discharged from the gas exhaust port is connected to the gas exhaust port, and the other end of the gas recovery pipe is connected to the gas supply pipe, The exhaust gas recovered in the gas recovery pipe is supplied to the culture solution in the culture tank via the gas supply pipe and the gas supply port.

7. In the culture device according to any one of claims 3 to 6, A support mechanism (18) for supporting the heat insulating section is provided, The heat insulating part has a first part (60) and a second part (62) which face each other horizontally sandwiching the culture tank installed at the installation location, The support mechanism supports the insulation section so that the first section and the second section can move closer to or farther apart from each other, in a culture device.

8. A culture device (10) having a culture tank (12) with a side wall formed from a material having translucency, the culture tank being accommodated therein and for culturing microalgae in a culture solution (L2) to which light is irradiated through the side wall, A liquid storage tank (14) formed from a light-transmitting material and having a light-transmitting liquid (L1) stored therein; The culture tank is disposed in the storage liquid stored in the storage tank; a sheet-like heat insulating portion (16, 100) that is transparent and flexible and covers the liquid storage tank; An air layer (52, 102) formed between the liquid storage tank and the insulating part arranged at an interval and insulating the inside of the culture tank; A support mechanism (18) for supporting the heat insulating portion; Equipped with The heat insulating part has a first part (60) and a second part (62) which face each other horizontally sandwiching the culture tank installed at the installation location, the support mechanism supports the heat insulating portion such that the first portion and the second portion can move closer to or apart from each other; The support mechanism includes a first support column (70) and a second support column (72), Each of the first support and the second support extends vertically from the lower end of the culture tank installed at the installation location to above the upper end of the culture tank, A first lower end support portion (82) is provided at a lower end of the first support column, and a first upper end support portion (84) is provided at an upper end of the first support column, A second lower end support portion (86) is provided at a lower end of the second support column, and a second upper end support portion (88) is provided at an upper end of the second support column, The first support and the second support can move relatively close to or away from each other along the horizontal direction with the culture tank interposed between them, A culture device, wherein the first portion extends from the first lower end support portion toward the first upper end support portion, the second portion extends from the second upper end support portion toward the second lower end support portion, and the first portion and the second portion are continuous via a third portion (64) extending in the horizontal direction from the first upper end support portion toward the second upper end support portion.

9. The culture apparatus according to claim 8, The first support columns are provided in parallel along a width direction of the first portion, At least one of the first lower end support portion and the first upper end support portion extends along the width direction of the first portion and connects the first pillars arranged in parallel to each other, The second support columns are provided in parallel along a width direction of the second portion, At least one of the second lower end support portion and the second upper end support portion extends along the width direction of the second portion and connects the parallel second supports to each other.

10. In the culture device according to any one of claims 7 to 9, A temperature sensor (20) for measuring the temperature of the culture solution in the culture tank; a drive unit (22) that drives the first portion and the second portion in a direction to move them closer to or away from each other; A control unit (24) that controls the drive unit so that the distance between the first part and the second part is adjusted according to the measurement value of the temperature sensor.

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