Efficient microalgae culture device

Abstract

The invention discloses an efficient microalgae culture device, and belongs to the technical field of light energy utilization and biologication.The microalgae culture device comprises a culture container filled with microalgae liquid; the lower part of the light gathering element is immersed in the microalgae liquid, and the light gathering element is used for adjusting sunlight incident on the light gathering element into parallel light or divergent light and then downwards guiding the light into the microalgae liquid so as to increase the light intensity in the microalgae liquid; and the direction adjusting part is used for controlling the direction of the sunlight incident on the light condensing element. Sunlight incident on the light condensing element is adjusted into parallel light or divergent light through the light condensing element and then is downwards guided into the microalgae liquid, the light intensity in the microalgae liquid is increased, a light source needed by microalgae growth is guaranteed, meanwhile, the influence of the microalgae density or the microalgae liquid depth is avoided, only solar energy is used, and electric energy is not needed; the microalgae culture cost is reduced.

Description

Technical Field

[0001] The invention belongs to the field of light energy utilization and biotechnology, and relates to a high-efficiency microalgae cultivation device. Background Art

[0002] Microalgae refers to the general term for microorganisms that contain chlorophyll a and can perform photosynthesis. Microalgae biomass is rich in protein, oil, polysaccharides, etc., especially containing bioactive substances such as unsaturated fatty acids, polysaccharides, pigments, etc., and has the function of enhancing the body's immunity. Therefore, microalgae biomass can be used as a raw material source for high-value-added products such as microalgae food, health products, medicines, animal feed, bioenergy, etc., and has a good economic development prospect.

[0003] The cultivation of microalgae biomass was carried out in closed and open photosynthetic bioreactors.

[0004] A closed photosynthetic bioreactor refers to a reactor in which the microalgae do not come into contact with the external environment during the cultivation process, and the culture container needs to be sealed. The closed photosynthetic bioreactor has a relatively high cost, a long construction period, high operating requirements, is not easy to clean and scale up, and has high maintenance costs in the later stages of cultivation. In the middle and late stages of cultivation, as the density of the microalgae increases, the light transmittance of the closed reactor deteriorates, affecting the photosynthesis efficiency. The closed environment is prone to accumulate O2, which has a toxic effect on the growth of microalgae. Therefore, the closed photosynthetic bioreactor has not yet reached the level of large-scale utilization.

[0005] An open photosynthetic bioreactor refers to a reactor in which the microalgae are in contact with the external environment during the cultivation process, and the culture container does not need to be sealed. The main types are: shallow water pools and runway pools. Open photosynthetic bioreactors are widely used in large-scale commercial microalgae cultivation. Shallow water pools are shallow, small in volume, low in breeding density per unit area, and high in breeding costs. Runway pools are generally deeper than shallow water pools, which makes it difficult for the microalgae in the lower layer to absorb light, affecting their growth. Artificial light sources are required, such as LED light sources to supplement the light, which consumes a lot of electricity.

[0006] Therefore, it is necessary to propose an energy-saving, light-transmitting and efficient microalgae cultivation device. Summary of the invention

[0007] In order to at least solve the problem in the prior art that the light transmittance of the photosynthetic bioreactor for cultivating microalgae deteriorates due to the increase of microalgae density or the increase of pool water depth, thus affecting the growth of microalgae, the present invention provides the following technical solution: an efficient microalgae cultivation device, the microalgae cultivation device comprising:

[0008] a culture container filled with microalgae liquid;

[0009] A light-concentrating element, the lower part of which is immersed in the microalgae liquid, and the light-concentrating element is used to adjust the sunlight incident on the light-concentrating element into parallel light or divergent light and then guide it downward into the microalgae liquid to increase the light intensity in the microalgae liquid; and

[0010] A direction-adjusting member is used to control the direction in which the sunlight is incident on the focusing element.

[0011] Optionally, in the above-mentioned efficient microalgae cultivation device, the focusing element comprises:

[0012] A light-concentrating portion, the light-concentrating portion being used to adjust the sunlight incident on the light-concentrating portion into the concentrated light;

[0013] a light adjusting unit, the light adjusting unit being located below the light focusing unit and being used for adjusting the converged light from the light focusing unit into parallel light or divergent light; and

[0014] The conducting part is a hollow structure and is located below the dimming part. The conducting part is connected to the dimming part, and at least a part of the conducting part is immersed in the microalgae liquid. The conducting part is used to guide the parallel light or divergent light from the dimming part downward into the microalgae liquid.

[0015] Optionally, in the above-mentioned high-efficiency microalgae cultivation device, the light focusing part and the light modulating part are both Fresnel lenses, and the specification size of the light focusing part is larger than the specification size of the light modulating part; and / or

[0016] The transmission part is a light guide made of glass or light-transmitting plastic material; and / or

[0017] The parallel light is parallel to the axis of the light guide;

[0018] The divergent light is arranged at an angle to the parallel light.

[0019] Optionally, in the above-mentioned efficient microalgae cultivation device, the direction-adjusting member comprises: a solar tracker;

[0020] The solar tracker is installed on the focusing element to ensure that the sunlight is irradiated on the focusing element at a designed incident angle at all times.

[0021] Optionally, in the above-mentioned efficient microalgae cultivation device, the direction-adjusting member comprises: a reflective element;

[0022] The reflective element is used to reflect sunlight onto the focusing element.

[0023] Optionally, in the above-mentioned efficient microalgae cultivation device, the reflective element includes: a first reflector and a second reflector;

[0024] The first reflector is arranged above the culture container through a mounting frame;

[0025] The second reflector is located at the periphery of the culture container and is used to reflect the sunlight irradiated on the second reflector to the first reflector;

[0026] The first reflector is used to reflect the sunlight from the second reflector downward onto the focusing element.

[0027] Optionally, in the above-mentioned high-efficiency microalgae cultivation device, a sun tracker is installed on the second reflector to keep the second reflector facing the sun at all times.

[0028] Optionally, in the above-mentioned high-efficiency microalgae cultivation device, a solar tracker is installed on the first reflector to keep the sunlight from the first reflector vertically irradiating the top of the focusing element.

[0029] Optionally, in the above-mentioned efficient microalgae cultivation device, the sunlight incident on the light-concentrating element includes: direct light and indirect light;

[0030] The direct light is direct radiation from the sun;

[0031] The indirect light is sunlight reflected onto the focusing element.

[0032] Optionally, in the above-mentioned efficient microalgae cultivation device, the culture container is an open container, and the side wall plate of the culture container is made of a light-shielding material or is coated with a light-shielding coating; or

[0033] The culture container is a closed container, one end of the light focusing element passes through the top plate of the culture container and is immersed in the microalgae liquid, and the other end of the light focusing element is located outside the culture container.

[0034] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0035] The present application adjusts the sunlight incident on the focusing element into parallel light or divergent light through a focusing element and then guides the light downward into the microalgae liquid, thereby increasing the light intensity in the microalgae liquid and ensuring the light source required for the growth of microalgae. At the same time, the light source is not affected by the density of microalgae or the depth of the algae liquid. The present application only uses solar energy and does not require electrical energy, thereby reducing the cost of microalgae cultivation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of the specific structure of an efficient microalgae cultivation device provided by an embodiment of the present invention;

[0037] Figure 2A schematic diagram of the working principle of an efficient microalgae cultivation device provided by an embodiment of the present invention;

[0038] Figure 3 Another specific structural schematic diagram of a high-efficiency microalgae cultivation device provided by an embodiment of the present invention;

[0039] In the figure: 1. culture container; 2. focusing element; 21. large Fresnel lens; 22. small Fresnel lens; 23. light guide tube; 24. connecting tube; 3. reflecting element; 31. first reflector; 32. second reflector; 4. mounting frame; 5. solar tracker. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0041] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention. The terms "connected", "connected" and "set" used in the present invention should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a direct connection or an indirect connection through an intermediate component; it can be a wired electrical connection, a radio connection, or a wireless communication signal connection. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0042] See also Figure 1-3The present invention provides the following technical solutions: an efficient microalgae cultivation device, the microalgae cultivation device comprising: a culture container 1, a focusing element 2 and a direction adjusting member. The culture container 1 (also called a reaction tank body) is filled with microalgae liquid. The number of focusing elements 2 can be set according to actual needs. The focusing element 2 is fixed in the (open) culture container 1 by a bracket (not shown in the figure), or a through hole is opened on the top plate of the (closed) culture container 1. After the focusing element 2 is inserted into the through hole, it will not shake left and right. This embodiment does not limit the type of the culture container 1 to be an open or closed container. The lower part of the focusing element 2 is immersed in the microalgae liquid. The part of the focusing element 2 located in the microalgae liquid is made of glass or light-transmitting plastic material, and has good light transmittance. When in use, the focusing element 2 adjusts the sunlight incident on the focusing element 2 into parallel light (referring to light parallel to the axis of the focusing element 2) or divergent light (referring to approximately parallel light in this article, which is slightly deviated from the axis of the focusing element 2, and it can be understood that the divergent light and the parallel light are set at an angle). The purpose of the focusing element 2 to adjust the light (referring to sunlight) is because the light (referring to sunlight) propagates in the air before reaching the focusing element 2, and energy loss (light attenuation) occurs. The multiple weakened light rays are adjusted by the focusing element 2 for the first time to become convergent light to increase the energy density, and then adjusted by the focusing element 2 for the second time to become parallel light or approximately parallel light, and finally the parallel light or approximately parallel light propagates downward in the inner cavity of the focusing element 2, and the light is refracted outward through the lower tube wall of the focusing element 2 with good light transmittance (that is, the focusing element 2 guides the processed light downward) into the microalgae liquid, which increases the light intensity in the microalgae liquid, ensures the light source required for the growth of microalgae, and is not affected by the density of microalgae or the depth of the pool water. The direction-adjusting member is used to control the direction of sunlight incident on the focusing element 2, so that the sunlight can be kept irradiated on the focusing element 2 at the designed incident angle at any time. Preferably, the sunlight incident on the focusing element 2 in the present application includes: direct light and indirect light. Direct light is direct radiation from the sun, such as sunlight at noon. Indirect light is sunlight reflected onto the focusing element 2. The culture container 1 in the present application has a depth of 1 to 10 meters. Compared with a shallow water pond, the pool capacity is large, the breeding density per unit area is high, and the breeding cost is low. At the same time, the present application only uses solar energy and does not require electrical energy (i.e., energy saving), which reduces the cost of microalgae cultivation.

[0043] Reference Figure 2As shown, the focusing element 2 includes: a focusing part, a dimming part and a conducting part. Among them, the focusing part is used to adjust the sunlight incident on the focusing part into convergent light, that is, the function of the focusing part is to focus light, so that the light energy intensity per unit area can be increased. The dimming part is located below the focusing part, and the two are arranged at an interval. The dimming part is used to adjust the convergent light from the focusing part into parallel light or divergent light, that is, the dimming part changes the propagation direction of the light after the focusing part converges, and scatters the light to the conducting part. The conducting part is a hollow structure, which is located below the dimming part. At the same time, the conducting part is connected to the dimming part, and at least part of the conducting part is immersed in the microalgae liquid. The conducting part is used to guide the parallel light or divergent light from the dimming part downward through the bottom or inner wall of the conducting part into the microalgae liquid, supplement the light energy required by the microalgae, ensure the growth of the microalgae, and thus increase the concentration of microalgae cultivation.

[0044] As a preferred embodiment of the above, in this embodiment, the focusing part and the dimming part are both Fresnel lenses arranged coaxially. The Fresnel lens has high transmittance (light), small size, light weight, easy processing, and low cost. The Fresnel lens can be used to focus the light irradiated on the Fresnel lens into the transmission part, which can effectively collect and utilize solar energy. The Fresnel lens can be made of glass or polymethyl methacrylate PMMA and other materials. In order to achieve uniform focusing, compared with the traditional Fresnel lens, the focusing part preferably uses a multi-focus composite Fresnel lens or a toric focusing Fresnel lens. The size of the focusing part is larger than the size of the dimming part, which can also be understood as the projection area of ​​the focusing part is larger than the projection area of ​​the dimming part, so we call the focusing part a large Fresnel lens 21, and the dimming part is called a small Fresnel lens 22. The large Fresnel lens 21 is used for focusing, and the small Fresnel lens 22 is used to adjust the light into parallel light and / or approximately parallel light. The Fresnel lenses are connected by a connecting tube 24. It should be noted that in the actual installation on site, the total number of Fresnel lenses used in the process of adjusting the light is 2 to 5. These Fresnel lenses are arranged in order from large to small in size, and the shape can be square or round. Due to the existence of reflection loss, absorption loss, process loss and structural loss, the more Fresnel lenses pass through, the more energy loss and the lower the optical efficiency. This embodiment is introduced by taking two Fresnel lenses (focusing + scattering) as an example. In other embodiments, it can also be a combination of multiple Fresnel lenses (such as focusing + focusing + scattering), which will not be introduced one by one in this article. The transmission part is a light guide tube 23 made of glass or translucent plastic material. The light guide tube 23 is a hollow tube, the size of which should be suitable for the size of the small Fresnel lens 22, and can realize seamless connection and installation. Its diameter is 10 to 300 mm and the length is 1 to 10 m. The length of the light guide tube 23 is flexibly set according to the depth of the culture container 1 (or microalgae solution). Preferably, the bottom of the light duct 23 is about 200 mm close to the bottom of the culture container 1. It should be noted that before use, according to the actual needs of the site, whether to irradiate parallel light or divergent light into the microalgae liquid, the Fresnel lens assembly (referring to the large Fresnel lens 11 and the small Fresnel lens 12) is flexibly selected, and the Fresnel lens assembly is fixed on the top of the light duct 23. The number of focusing elements 1 can be flexibly set according to the actual needs of the site. For a culture container 1 with a large pool capacity, a plurality of light ducts 23 (i.e., focusing elements 2) with Fresnel lens assemblies are evenly arranged in the culture container 1 (i.e., the reaction tank body) according to the outer wall spacing of 100 to 500 mm. The present application uses a light duct 23 to introduce light into the microalgae liquid in the culture container 1, so as to achieve uniform light reception of the microalgae cells and improve the production efficiency per unit area.

[0045] In order to meet the optimal light intensity requirements for different types of microalgae cultivation, the large Fresnel lens 21 and the small Fresnel lens 22 in the device of the present invention are designed differently. For example, the large Fresnel lens 21 has a size of 600X600mm, and the small Fresnel lens 22 has a size of φ150mm, achieving 20 times light focusing.

[0046] As an embodiment of the specific structure of the above-mentioned steering member, in this embodiment, the steering member includes: a solar tracker 5. The solar tracker 5 is installed on the focusing element 2, such as the solar tracker 5 is installed on the light guide 23 (such as Figure 3 As shown), a solar tracker is used to keep the sunlight shining on the focusing element 2 at the designed incident angle at all times.

[0047] As another embodiment of the specific structure of the above-mentioned direction-adjusting member, in this embodiment, the light-adjusting member includes: a reflective element 3. The reflective element 3 is used to reflect sunlight onto the focusing element 2. Specifically, the reflective element 3 includes: a first reflector 31 and a second reflector 32. Among them, the first reflector 31 is arranged above the culture container 1 through a mounting frame 4. The second reflector 32 is located at the periphery of the culture container 1, and the second reflector 32 is used to reflect the sunlight irradiated on the second reflector 32 onto the first reflector 31. The first reflector 31 is used to reflect the sunlight from the second reflector 32 downward onto the focusing element 2, and downward here includes vertically downward and also includes tilted downward at an angle to the vertical direction. The angle between the divergent light emitted by the small Fresnel lens 22 and the center line of the light guide tube 23 is determined after design according to the length of the pipeline guide tube and the size of the small Fresnel lens 22. It should be noted that the first reflector 31 and the second reflector 32 are not a single reflector, but are composed of multiple groups of reflectors with different angles. Preferably, the sunlight reaches the focusing element 2 after being reflected 2 to 5 times. Figure 2 In the drawing shown, only two reflectors are used for illustration. The number of the first reflector 31 and the second reflector 32 is designed according to the specifications of the culture container 1. The second reflectors 32 can adopt a circular layout, and each second reflector 32 is in a staggered state; or a linear array layout, the second reflectors 32 are arranged on multiple parallel straight lines, and the second reflectors 32 on each row are located on the same straight line, and the second reflectors 32 between adjacent rows are staggered in the east-west direction. It should be noted that the words "first" and "second" are added in front of the reflectors only for distinction and have no other special meaning. In addition, the specific installation positions of all reflectors and Fresnel lenses in this application are determined by technicians based on several experimental simulations and on-site measurement data.

[0048] Reference Figure 2As shown, in order to keep the second reflector 32 facing the sun at all times, a solar tracker 5 is installed on the second reflector 32. The solar tracker 5 is a power device that allows the sunlight to vertically illuminate the second reflector 32 at any time. The solar tracker 5 on the market can be used, and this embodiment does not limit it. The first reflector 31 reflects the sunlight from the second reflector 32 obliquely downward onto the focusing element 2 (referring to the large Fresnel lens 21), so that the sunlight is successively formed into convergent light and divergent light through the large Fresnel lens 21 and the small Fresnel lens 22, and then obliquely illuminates the side wall of the culture container 1. Preferably, the culture container 1 is an open container, and the side wall plate of the culture container 1 is made of a shading material or coated with a shading coating. A concrete pool body can be used, and an insulation board can be set on the outer wall to achieve a heat preservation effect.

[0049] In other embodiments, the culture container 1 is a closed container, such as a tubular reactor, one end of the light-concentrating element 2 (referring to the conducting part, that is, the light guide tube 23) passes through the through hole on the top plate of the culture container 1 and is immersed in the microalgae liquid, and the other end of the light-concentrating element 2 (referring to the light-concentrating part, the light-adjusting part) is located above the microalgae liquid. On the basis of the solar tracker 5 installed on the second reflector 32, the first reflector 31 is also installed with a solar tracker 5 (not shown in the figure), which is used to keep the sunlight from the first reflector 31 vertically irradiated to the top of the light-concentrating element 2 (referring to the large Fresnel lens 21), that is, through the solar tracker 5, the first reflector 31 reflects the sunlight from the second reflector 32 vertically downward to the light-concentrating element 2, so that the sunlight is sequentially rectified into convergent light and parallel light through the large Fresnel lens 21 and the small Fresnel lens 22, and then vertically irradiated downward to the culture container 1.

[0050] Figure 3 An optional solution (without the reflective element 3) is provided, which is suitable for microalgae cultivation under the environment with sufficient sunlight, as shown in the figure: the focusing element 2 is an integral component composed of a focusing part (referring to the large Fresnel lens 21), a dimming part (referring to the small Fresnel lens 22) and a transmission part, and a solar tracker 5 is installed on the upper part of the transmission part (referring to the light guide 23). When the position of the sun moves, the focusing part, the dimming part and the transmission part can be moved and adjusted as a whole through the action of the solar tracker 5, and the incident angle of the sunlight irradiating the large Fresnel lens 21 is adjusted to the required angle, so as to ensure the focusing effect of the large Fresnel lens 21. One solar tracker 5 can act on the overall movement of one or more groups of focusing elements 2, but when the number of focusing elements 2 is large, multiple solar trackers 5 need to be set.

[0051] Figure 2 and Figure 3 The main considerations are to deal with the differences in light intensity in different geographical locations and the different optimal light intensities required by different microalgae species. Figure 2A reflective element 3 is provided in the middle, which can reflect more sunlight to the focusing element 2, and can make up for the influence of insufficient sunlight on microalgae cultivation. Figure 3 Eliminating the reflective element 3 can reduce the construction investment cost and is suitable for microalgae cultivation under environmental conditions with sufficient sunlight. Figure 2 In the figure, since the solar tracker 5 is arranged on the second reflector 32, the solar tracker 5 allows the sunlight to be irradiated vertically on the second reflector 32 at any time. Figure 3 In the embodiment, since the solar tracker 5 is disposed on the light guide 23, the solar tracker 5 allows the sunlight to be irradiated on the large Fresnel lens 21 at any time according to the designed incident angle. Figure 2 and Figure 3 In both cases, the choice should be made based on the local sunlight intensity and the type of microalgae being cultivated.

[0052] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. An efficient microalgae cultivation device, characterized in that: The microalgae cultivation device comprises: a culture container filled with microalgae liquid; A light-concentrating element, the lower part of which is immersed in the microalgae liquid, and the light-concentrating element is used to adjust the sunlight incident on the light-concentrating element into parallel light or divergent light and then guide it downward into the microalgae liquid to increase the light intensity in the microalgae liquid; and A direction-adjusting member is used to control the direction in which the sunlight is incident on the focusing element.

2. The high-efficiency microalgae cultivation device according to claim 1, characterized in that: The light focusing element comprises: A light-concentrating portion, the light-concentrating portion being used to adjust the sunlight incident on the light-concentrating portion into the concentrated light; a light adjusting unit, the light adjusting unit being located below the light focusing unit and being used for adjusting the converged light from the light focusing unit into parallel light or divergent light; and The conducting part is a hollow structure and is located below the dimming part. The conducting part is connected to the dimming part, and at least a part of the conducting part is immersed in the microalgae liquid. The conducting part is used to guide the parallel light or divergent light from the dimming part downward into the microalgae liquid.

3. The high-efficiency microalgae cultivation device according to claim 2, characterized in that: The light-collecting part and the light-adjusting part are both Fresnel lenses, and the size of the light-collecting part is larger than the size of the light-adjusting part; and / or The transmission part is a light guide made of glass or light-transmitting plastic material; and / or The parallel light is parallel to the axis of the light guide; The divergent light is arranged at an angle to the parallel light.

4. The high-efficiency microalgae cultivation device according to claim 2, characterized in that: The direction-adjusting component includes: a solar tracker; The solar tracker is installed on the focusing element to ensure that the sunlight is irradiated on the focusing element at a designed incident angle at all times.

5. The high-efficiency microalgae cultivation device according to claim 2, characterized in that: The direction-adjusting member comprises: a reflective element; The reflective element is used to reflect sunlight onto the focusing element.

6. The high-efficiency microalgae cultivation device according to claim 5, characterized in that: The reflective element comprises: a first reflector and a second reflector; The first reflector is arranged above the culture container through a mounting frame; The second reflector is located at the periphery of the culture container and is used to reflect the sunlight irradiated on the second reflector to the first reflector; The first reflector is used to reflect the sunlight from the second reflector downward onto the focusing element.

7. The high-efficiency microalgae cultivation device according to claim 6, characterized in that: A sun tracker is installed on the second reflector to keep the second reflector facing the sun at all times.

8. The high-efficiency microalgae cultivation device according to claim 6, characterized in that: A solar tracker is installed on the first reflector to keep the sunlight from the first reflector vertically irradiating the top of the focusing element.

9. The high-efficiency microalgae cultivation device according to claim 1, characterized in that: The sunlight incident on the focusing element includes: direct light and indirect light; The direct light is direct radiation from the sun; The indirect light is sunlight reflected onto the focusing element.

10. The high-efficiency microalgae cultivation device according to claim 1, characterized in that: The culture container is an open container, and the side wall of the culture container is made of a light-shielding material or is coated with a light-shielding coating; or The culture container is a closed container, one end of the light focusing element passes through the top plate of the culture container and is immersed in the microalgae liquid, and the other end of the light focusing element is located outside the culture container.

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