A three-lane raceway open pond for microalgae cultivation

Abstract

The utility model discloses a three flow channel runway formula open pool for microalgae culture, including open pool body, the open pool body be equipped with two side -by -side arrangement's partition wall, the partition wall will the space in open pool body divide into three side -by -side's flow channel, respectively two side flow channel and an intermediate flow channel, the both ends of adjacent two flow channels all communicate with each other, be equipped with the stirring paddle for driving microalgae culture solution flow in one end of intermediate flow channel. The utility model discloses the traditional two flow channel of runway formula open pool is improved to three flow channel, can effectively promote the flow rate of microalgae culture solution, reduce the mixed dead area, prevent microalgae deposition, reduce the collapse rate, improve microalgae culture efficiency. Especially suitable for the runway formula open pool of larger scale, reduce the energy consumption of same flow rate.

Description

Technical Field

[0001] This utility model belongs to the field of microalgae cultivation technology, and relates to a racetrack-type open pool, specifically a three-channel racetrack-type open pool for microalgae cultivation. Background Technology

[0002] Microalgae are a type of photosynthetic autotrophic microorganism, rich in high-value-added biological substances such as proteins, unsaturated fatty acids, polysaccharides, and pigments, and have high application value. Large-scale cultivation methods for microalgae can be divided into closed photobioreactors and open ponds. Among them, open ponds have been widely used in industrial production due to their low construction and maintenance costs and simple technology.

[0003] Traditional open culture tanks are often racetrack-shaped, consisting of two channels. An agitator is installed in one of the channels, typically at one end of the tank. Driven by a motor, the impeller rotates, circulating the culture medium within the racetrack. Figure 1 As shown, a circulating algal solution can solve problems such as uneven light and nutrient distribution, insufficient gas exchange, cell sedimentation, temperature gradients, waste accumulation, and contamination risks, thus promoting microalgae growth. If the flow channel is too wide or too long, large mixing dead zones may exist in areas far from the agitator, such as bends and near the sidewalls, leading to microalgae deposition and potentially culture failure.

[0004] To facilitate the flow of culture medium within open pools, existing technologies disclose the addition of submersible propellers to the ends or side walls of the raceway pool (see patent CN201721502126.4, Simple Raceway Pool for Microalgae Cultivation). This reduces energy consumption for liquid mixing, minimizes dead zones, and prevents algal cell sedimentation, thereby improving the area yield. However, its function is relatively limited, and there is room for further improvement. Utility Model Content

[0005] This invention addresses the shortcomings of the existing technology by providing a three-channel raceway-type open tank for microalgae cultivation, which can increase the flow rate of the microalgae culture medium in the raceway-type open tank, reduce dead zones, and improve the efficiency of microalgae cultivation.

[0006] The specific technical solution is as follows:

[0007] This utility model provides a three-channel racetrack-type open tank for microalgae cultivation, including an open tank body; the open tank body is provided with two side-by-side baffles, which divide the space inside the open tank body into three side-by-side channels, namely two side channels and one middle channel; the two ends of two adjacent channels are connected to each other; a stirring paddle for driving the flow of microalgae culture medium is provided at one end of the middle channel.

[0008] This invention improves the traditional two-channel system into a three-channel system, with a stirring paddle installed in the middle channel to drive the algal liquid flow within the tank. The flow directions of the two side channels are opposite to those of the middle channel, forming two flow cycles. While maintaining the same overall tank size, the narrower channel with the stirring paddle and shorter drive shaft result in increased stirring speed and liquid velocity at the same stirring power. This helps eliminate dead zones at bends and reduce radial velocity loss; maintaining the original flow velocity reduces energy consumption. This invention is beneficial for improving the cultivation efficiency of microalgae in racetrack-style open tanks.

[0009] Specifically, the two baffle walls are preferably arranged in parallel.

[0010] Specifically, the width of the middle flow channel is preferably 0.8 to 1.2 times that of the two side flow channels.

[0011] Specifically, the stirring paddle is driven by an electric motor.

[0012] Furthermore, the above technical solution can be improved as follows: a submersible propeller (submersible liquid propeller) can be installed within the open pool body to further increase the liquid flow rate, reduce dead zones, and lower the energy consumption for liquid mixing. In existing technologies, submersible propellers are water circulation devices used in aeration tanks and anaerobic tanks of industrial and municipal wastewater treatment plants, mainly used to assist in water treatment processes such as nitrification, denitrification, and phosphorus removal; they prevent sludge deposition and improve reaction efficiency by generating a strong water flow with low tangential flow.

[0013] Furthermore, the submersible thrusters are preferably located at both ends within the open pool body to improve flow at turns and reduce dead zones.

[0014] Specifically, it is preferable to install two submersible thrusters at each end of the open pool body, with the two submersible thrusters at each end targeting two flow channels respectively, and propelling the flow along the direction of liquid flow.

[0015] Furthermore, the submersible propulsion device is improved as follows: The submersible propulsion device includes a main body, with an outlet pipe connected to the outlet end of the main body. A section of nano-ceramic aeration pipe is installed inside the outlet pipe. The nano-ceramic aeration pipe is connected to external air or a carbon dioxide gas supply device via a vent pipe. This improvement combines liquid propulsion with carbon supplementation. Air or carbon dioxide gas containing carbon dioxide enters the nano-ceramic aeration pipe through the vent pipe. Under high pressure, carbon dioxide nanobubbles mix thoroughly with the rapidly flowing liquid. The effluent is then flushed into the microalgae culture medium, accelerating liquid flow. Simultaneously, the carbon-rich liquid containing carbon dioxide mixes with a large amount of microalgae culture medium. This operation reduces carbon dioxide escape and improves carbon source utilization.

[0016] Specifically, the pore size of the nano-ceramic aeration tube is preferably 0.1~0.3 μm.

[0017] Specifically, the length of the water outlet pipe is preferably 25-110 cm, and the diameter is preferably 25-50 mm; the length of the nano-ceramic aeration pipe is preferably 5-100 cm, and the diameter is preferably 6-20 mm.

[0018] Specifically, the nano-ceramic aeration pipe and the water outlet pipe are arranged in the same direction.

[0019] Furthermore, the length of the open pool body is preferably 30-100 m, and the width is preferably 3-10 m.

[0020] Specifically, the aforementioned three-channel raceway-type open pool is suitable for open cultivation of Spirulina, Chlorella, diatoms, etc.

[0021] The beneficial effects of this utility model are as follows:

[0022] This invention improves the traditional two-channel design of racetrack-type open ponds into a three-channel design, effectively increasing the flow rate of the microalgae culture medium, reducing mixing dead zones, preventing microalgae sedimentation, and improving the success rate and efficiency of microalgae cultivation. It is particularly suitable for large-scale racetrack-type open ponds, reducing energy consumption at the same flow rate. By improving the submersible propulsion device, it also incorporates carbon supplementation, enhancing the utilization rate of the carbon source. Attached Figure Description

[0023] Figure 1 This is a top view of a two-channel racetrack-type open pool in the prior art;

[0024] Figure 2 This is a top view of the three-channel raceway-type open tank used for microalgae cultivation in Example 1;

[0025] Figure 3 This is a top view of the three-channel raceway-type open tank used for microalgae cultivation in Example 2;

[0026] Figure 4 This is a schematic diagram of the submersible thruster in Example 2.

[0027] In the diagram: 1. Open pool body; 2. Baffle wall; 3. Agitator; 4. Submersible propeller; 4-1. Submersible propeller body; 4-2. Water outlet pipe; 4-3. Nano-ceramic aeration pipe; 4-4. Air vent pipe.

[0028] The arrows in the diagram indicate the direction of liquid flow. Detailed Implementation

[0029] The principles and features of this utility model are described below with reference to examples. The examples are only used to explain this utility model and are not intended to limit the scope of this utility model.

[0030] Example 1

[0031] A three-channel raceway-style open tank for microalgae cultivation, such as Figure 2 As shown, the system includes an open pool body 1, which contains two parallel flow barriers 2. These flow barriers 2 divide the space within the open pool body 1 into three parallel flow channels: two side flow channels and one central flow channel. The ends of any two adjacent flow channels are connected to each other. The racetrack-style open pool has dimensions of 100 m in length and 6 m in width, with each flow channel having a width of 2 m. The two ends of the open pool body 1 are outwardly convex arc shapes.

[0032] A stirring paddle 3 is provided at one end of the intermediate flow channel to drive the flow of microalgae culture medium. The stirring paddle 3 is driven by a motor.

[0033] Spirulina were cultured in a three-channel raceway-type open tank using Zarrouk medium at a depth of 40 cm and an algal cell inoculation density of 0.2 g / L. The flow rate of the microalgae culture medium within the channels was adjusted by regulating the motor speed. The flow direction of the two side channels was opposite to that of the central channel. The liquid flow direction was as follows: Figure 2 As shown by the arrows, in the middle channel, the liquid flows from one end where the agitator 3 is located to the other. The average liquid flow rate was maintained at 30 cm / s through multiple measurements. Nutrient concentration was monitored daily, and water was replenished as needed to maintain the depth of the microalgae culture medium. After 7 days of cultivation, the algal cell density reached 0.5 g / L, and the average daily agitation energy consumption was 26 kW·h.

[0034] Comparative Example 1

[0035] use Figure 1 The conventional two-channel raceway-style open tank for culturing Spirulina is shown. The dimensions of the open tank body 1 are the same as in Example 1. An impermeable wall 2 is installed inside the open tank body 1, dividing the space within the open tank body 1 into two interconnected channels, each 3 meters wide. One end of one of the channels is equipped with a stirring paddle 3 for driving the flow of the microalgae culture medium. The culture depth, inoculation density, and average liquid flow rate are the same as in Example 1. To maintain the same liquid flow rate of 30 cm / s, the energy consumption for stirring is increased. After 7 days of culture, the algal cells reached a concentration similar to that of Example 1, with an average daily stirring energy consumption of 34 kW·h, an increase of approximately 30% compared to Example 1.

[0036] Example 2

[0037] A three-channel raceway-style open tank for microalgae cultivation, such as Figure 3As shown, refer to Example 1. The difference from Example 1 is that two submersible thrusters 4 are provided at each end of the open pool body 1. The two submersible thrusters 4 at each end are respectively set for two flow channels and propel the flow along the direction of liquid flow.

[0038] like Figure 4 As shown, the submersible thruster 4 includes a submersible thruster body 4-1, and a water outlet pipe 4-2 is connected to the water outlet end of the submersible thruster body 4-1. A section of nano-ceramic aeration pipe 4-3 is provided inside the water outlet pipe 4-2. The nano-ceramic aeration pipe 4-3 is arranged in the same direction as the water outlet pipe 4-2. The nano-ceramic aeration pipe 4-3 is connected to a carbon dioxide gas supply device outside the liquid surface through a vent pipe 4-4 that extends out of the water outlet pipe 4-2.

[0039] The water outlet pipe 4-2 is 50 cm long and 50 mm in diameter.

[0040] The nano-ceramic aeration tube 4-3 is 10 cm long and 20 mm in diameter, with a pore size of 0.1~0.3 μm.

[0041] When using the aforementioned submersible thruster 4, it is placed below the liquid surface, with the vent pipe 4-4 extending out of the liquid and connected to the carbon dioxide gas supply device. Carbon dioxide enters the nano-ceramic aeration pipe 4-3 through the vent pipe 4-4. Under high pressure, the carbon dioxide nanobubbles mix thoroughly with the rapidly flowing liquid, and the effluent is flushed into the microalgae culture medium, accelerating the liquid flow. Simultaneously, the carbon-rich liquid containing carbon dioxide mixes with a large amount of microalgae culture medium. The liquid flow direction is as follows... Figure 3 , Figure 4 As shown by the arrow in the image.

[0042] Chlorella was cultured in a three-channel raceway-shaped open tank using BG11 medium at a depth of 30 cm and an algal cell inoculation density of 0.1 g / L. The flow rate of the microalgae culture medium within the channels was adjusted by regulating the motor speed and the number of switches on / off the liquid propellers 4. The flow direction of the two side channels was opposite to that of the central channel. The liquid flow direction was as follows: Figure 3 As shown by the arrow, in the middle channel, the liquid flows from one end where the agitator 3 is located to the other. The average liquid flow rate is maintained at 50 cm / s by multiple measurements; the pH of the Chlorella culture medium is controlled at 7.5. When the pH is higher than this value, carbon supplementation is initiated in the liquid propeller 4, and carbon supplementation is stopped when the pH is lower than 7.5.

[0043] Nutrient concentrations were monitored daily and water was replenished as needed to maintain the depth of the microalgae culture medium. After 4 days of cultivation, the algal cell density reached 0.3 g / L, with an average daily stirring energy consumption of 45 kW·h. The average carbon source utilization rate was calculated to be 90% by measuring the reduction in carbon dioxide in the gas supply device.

[0044] Comparative Example 2

[0045] Chlorella was cultured in a conventional two-channel raceway tank, the same as in Comparative Example 1, with the same culture depth, inoculation density, and average liquid flow rate as in Example 2. To maintain the same liquid flow rate of 50 cm / s, the energy consumption for stirring was increased. Furthermore, two nano-ceramic aeration tubes, identical in size and pore size to those in Example 2, were placed at each of the two bends in the flow channel, and the carbon supplementation method was the same as in Example 2.

[0046] After 4 days of cultivation, the algal cells reached a concentration similar to that of Example 1, with an average daily stirring energy consumption of 52 kW·h, which is about 15% higher than that of Example 2. More importantly, the carbon dioxide absorption rate was only 35%, which increased the cultivation cost of Chlorella compared to Example 2.

[0047] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A three-channel raceway-type open tank for microalgae cultivation, comprising an open tank body (1), characterized in that, The open pool body (1) is provided with two parallel flow-blocking walls (2), which divide the space inside the open pool body (1) into three parallel flow channels, namely two side flow channels and one middle flow channel; the two ends of the two adjacent flow channels are connected to each other; a stirring paddle (3) for driving the flow of microalgae culture medium is provided at one end of the middle flow channel.

2. The three-channel racetrack-type open pool according to claim 1, characterized in that, Two flow barriers (2) are set in parallel.

3. The three-channel racetrack-type open pool according to claim 2, characterized in that, The width of the middle flow channel is 0.8 to 1.2 times that of the two side flow channels.

4. The three-channel racetrack-type open pool according to any one of claims 1 to 3, characterized in that, A submersible thruster (4) is installed inside the open pool body (1).

5. The three-channel racetrack-type open pool according to claim 4, characterized in that, The submersible thruster (4) is located at both ends inside the open pool body (1).

6. The three-channel racetrack-type open pool according to claim 4, characterized in that, Two submersible thrusters (4) are installed at each end of the open pool body (1), and the two submersible thrusters (4) at each end are respectively set for the two side channels.

7. The three-channel racetrack-type open pool according to claim 4, characterized in that, The submersible propulsion device (4) includes a submersible propulsion body (4-1), and a water outlet pipe (4-2) is connected to the water outlet end of the submersible propulsion body (4-1). A section of nano-ceramic aeration pipe (4-3) is provided inside the water outlet pipe (4-2). The nano-ceramic aeration pipe (4-3) is connected to the outside air or carbon dioxide gas supply device through a vent pipe (4-4).

8. The three-channel racetrack-type open pool according to claim 7, characterized in that, The pore size of the nano-ceramic aeration tube (4-3) is 0.1~0.3 μm.

9. The three-channel racetrack-type open pool according to claim 7, characterized in that, The water outlet pipe (4-2) has a length of 25~110 cm and a diameter of 25~50 mm; the nano-ceramic aeration pipe (4-3) has a length of 5~100 cm and a diameter of 6~20 mm.

10. The three-channel racetrack-type open pool according to any one of claims 1 to 3, characterized in that, The open pool body (1) is 30-100 m long and 3-10 m wide.

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