Microalgae environmental adaptation carbon fixation method based on spiral disturbance flow field strengthening

Abstract

The present application relates to the technical field of microalgae carbon fixation, and specifically discloses a microalgae environmental adaptation carbon fixation method based on spiral disturbance flow field enhancement, which comprises the following steps: constructing a column type photobioreactor and setting a spiral disturbance plate, selecting high-efficiency carbon fixation Chlorella sp. which is resistant to NO X , SO X , pre-treating and inoculating, precisely regulating environmental parameters such as light and pH, monitoring the carbon fixation process in real time and regulating abnormally, and realizing cyclic operation by adopting semi-continuous culture. The present application enhances gas-liquid mass transfer by spiral disturbance, combines dynamic adaptation and regulation of multiple environmental parameters, improves CO₂ emission reduction rate and microalgae growth efficiency, optimizes reactor mass transfer characteristics, reduces energy consumption, realizes the collaborative treatment of multiple pollutants, and provides standardized technical support for the industrialization of microalgae carbon fixation.

Description

Technical Field

[0001] This invention relates to the field of microalgae carbon fixation technology, specifically to a microalgae environment adaptation carbon fixation method based on spiral turbulence enhanced flow field. Background Technology

[0002] Microalgae carbon fixation has become an important technological pathway to achieve the "dual carbon" goal due to its advantages such as high photosynthetic efficiency, short growth cycle, and no competition for land with food crops. Chlorella, as a typical high-efficiency carbon-fixing algae, has its growth and carbon fixation efficiency affected by light, temperature, pH value, and CO2 and NO in exhaust gas. x SO x Concentration and other environmental factors have a significant impact.

[0003] Traditional photobioreactors generally suffer from low mass transfer efficiency, short bubble residence time, and uneven contact between microalgae and gas. Furthermore, current technologies lack precise environmental adaptation and control schemes for specific algal species like Chlorella, making it difficult to simultaneously achieve high carbon fixation efficiency and high microalgal biomass production. While helical baffles can extend bubble residence time and enhance gas-liquid mixing by altering fluid movement trajectories, current technologies fail to integrate their structural advantages with the environmental adaptability control of Chlorella, thus failing to fully realize the carbon fixation potential of microalgae.

[0004] Currently, environmental parameter regulation in microalgae carbon fixation systems is mostly based on single-dimensional adjustments, failing to consider multi-parameter coupling effects. Furthermore, the reactor's gas supply stability is poor, key indicator measurement methods are limited, and data errors are prone to occur. Additionally, the integrated reactor design leads to poor maintainability and difficulty in adapting to different algal species and exhaust gas conditions. Therefore, there is an urgent need to develop a microalgae-based environmental adaptation carbon fixation method that combines helical turbulence to enhance mass transfer with multi-factor synergistic regulation to address these technical challenges and enhance the industrial application value of microalgae carbon fixation. Summary of the Invention

[0005] The purpose of this invention is to provide a microalgae-based carbon fixation method adapted to the microalgae environment by constructing a spiral-driven baffled photobioreactor to enhance gas-liquid mass transfer efficiency. Combined with the growth characteristics of *Chlorella vulgaris*, precise dynamic control of light, pH, exhaust gas concentration, temperature, and harvesting cycle is achieved. Simultaneously, the gas supply and monitoring system are optimized to achieve closed-loop control with multi-parameter coupling, ultimately achieving a CO2 emission reduction rate ≥40% and a maximum specific growth rate of microalgae ≥0.8 days. -1 The technical goal is to adapt to the continuous biological carbon sequestration treatment of industrial flue gas, and improve the system's stability, adaptability, and industrial feasibility.

[0006] To achieve the above objectives, the technical solution provided by this invention is: a method for microalgae environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field, comprising the following steps: S1. Construct a column-type photobioreactor, and install a spiral baffle structure along the axial direction inside the reactor; the spiral baffle is used to change the upward path of the introduced gas, so that the gas forms a spiral upward flow state inside the reactor; the reactor is equipped with a gas inlet, a culture medium outlet and a parameter monitoring device for subsequent operation monitoring and control. S2. Chlorella pretreatment and inoculation: Select acclimatized and screened chlorella species with NO resistance. x SO x The highly efficient carbon-fixing algae Chlorella sp. AE10 and Chlorella sp. Cv were first tested at 25℃, light intensity of 9000 Lux, and aeration rate of 0.15 vv. - 1 m -1 Under controlled conditions, the algae were revived and cultured until the logarithmic growth phase; the algal sludge was collected by centrifugation and washed twice with sterile culture medium, and the inoculum concentration was adjusted to 0.5 g·L⁻¹. -1 This stabilized the initial biomass concentration of the algal solution in the reactor at 0.5 ± 0.05 g·L⁻¹. -1 The pretreated algal solution is pumped into the reactor. The mixed gas, which is regulated by the gas washing device, is dispersed by the gas refiner and then introduced into the reactor. The spiral baffle drives the bubbles to rise spirally to enhance the gas-liquid contact. S3. Precise control of environmental factors based on helical turbulence-enhanced mass transfer: with CO2 emission reduction rate ≥60% and specific growth rate ≥0.8d. -1 To achieve this goal, the cultivation system is continuously monitored and environmental parameters are dynamically adjusted, including light intensity, pH, exhaust gas concentration, temperature, and harvest cycle. S4. Real-time monitoring and abnormal control of carbon fixation process: Using microalgae cultivation and exhaust gas dynamic balance monitoring software, data on temperature, light intensity, pH value, CO2 inlet and outlet concentrations, and biomass concentration are collected at 10-minute intervals; when the average daily biomass growth is <0.1 g·L⁻¹. -1 ・d -1 When the pH deviates from 7.5-8.5 or the CO2 emission reduction rate is less than 55%, an automatic alarm will be triggered and the corresponding parameters will be adjusted; at the same time, the CO2 fixation rate will be calculated using a formula to characterize the carbon fixation efficiency. S5. Semi-continuous culture and cyclic operation: When the optimal harvest cycle is reached, a semi-continuous harvesting method is adopted, harvesting 1 / 3 of the algal solution each time, while simultaneously replenishing an equal amount of fresh culture medium and inoculum solution to stabilize the algal solution concentration in the reactor at 1.5-2.0 g·L⁻¹. -1 After feeding, the new and old culture media are rapidly mixed by the spiral turbulent flow field, and the reactor re-enters the cultivation and control stage, forming a continuous cycle operation.

[0007] Further, in step S2, the initial biomass concentration is calculated as follows: ,in, This represents the initial biomass concentration. The dry weight of the algal sludge after centrifugation. The effective culture volume of the reactor.

[0008] Furthermore, in step S3, the adjustment of the environmental parameters specifically involves: Light control: The light intensity is 9000 Lux during the logarithmic growth phase and adjusted to 7000 Lux during the stationary phase. A 12-hour light / 12-hour dark cycle is adopted. The light intensity is adjusted by the power of the cold light lamp group, and the spiral baffle drives the algal liquid to move in a spiral motion to improve the uniformity of light. pH control: Maintain the optimal pH for Chlorella carbon fixation at 7.5-8.5. Achieve dynamic pH balance by adjusting the CO2 concentration in the exhaust gas. Add 5 mmol·L⁻¹ -1 Sodium bicarbonate acts as a pH buffer, reducing the proportion of CO2 in the mixed gas when pH < 7.5 and increasing the proportion of CO2 when pH > 8.5. Exhaust gas concentration control: The basic CO2 volume fraction of the mixed exhaust gas is 10%, maintained at 10% during the logarithmic growth phase and reduced to 8% during the stationary phase; Chlorella sp. AE10 is suitable for 10% CO2 + 100ppm NO. x +50ppm SO x Chlorella sp. Cv is compatible with 10% CO2 + 200ppm NO. x +100ppm SO x NO x Concentration ≤300ppm; Total flow rate of mixed gas 1.5-7L·min -1 Ventilation rate 0.15-0.2vv -1 m -1 Ensure that the bubble residence time is ≥30s; Temperature control: Maintain the optimal growth temperature of 25±3℃. The exhaust gas is washed and cooled to 25℃ before being introduced. An insulation layer is installed on the outside of the reactor. The heating element is activated when the temperature is <22℃ and the cooling water circulation is activated when the temperature is >28℃ to ensure that the temperature fluctuation of the algal solution is ≤±1℃. Harvest cycle regulation: Based on the net carbon sequestration formula, the optimal harvest cycle was calculated. The optimal recovery cycle for Chlorella sp. AE10 was 7 days, and for Chlorella sp. Cv it was 8 days, at which point the biomass concentration reached 2.5-3.0 g·L⁻¹. -1 .

[0009] Furthermore, in step S3, the light intensity is adjusted by the power of the cold light lamp group 8, and is fed back and calibrated in real time by the light energy balance monitoring module. The incident light intensity on the surface of the photobioreactor is represented by the average light intensity. ;in, The average light intensity, The luminous flux of a single lamp tube. For the number of light tubes, The space utilization coefficient is set to 0.7. The maintenance factor is set to 0.8. This represents the illuminated area.

[0010] Furthermore, in step S3, the correlation between the CO2 concentration and pH value is approximated: ;in, This refers to the concentration of bicarbonate ions in the culture medium. The concentration of dissolved CO2 in the algal solution is calculated using gas partial pressure.

[0011] Further, in step S3, the formula for the heat exchange amount of temperature regulation is: ;in For heat exchange quantity, For the effective thermal efficiency, let's take 0.35. The temperature of the gas inside the cylinder. This refers to the cooling water temperature.

[0012] Further, in step S3, the formula for calculating the net solid carbon content is: ;in, Net carbon solids For mortality rate, This refers to the carbon sequestration capacity per unit volume of algal solution. The carbon decay coefficient, The carbon sequestration capacity per unit volume of inoculum; the maximum biomass concentration is expressed by the formula. Fit, where, Let be the biomass concentration at time t. This represents the initial biomass concentration. for Time is compared to growth rate.

[0013] Further, in step S4, the average daily biomass growth is determined by the formula... Calculate, where, This represents the average daily growth. The dry weight of the harvested algal cells, This represents the dry weight of algal cells in the inoculum. The incubation time; the CO2 emission reduction rate is calculated using the formula... Calculate, where η is the CO2 emission reduction rate. The CO2 concentration at the reactor inlet. The CO2 concentration at the reactor outlet; the CO2 fixation rate is expressed by the formula... ; Calculate, where, For a fixed rate of CO2, Carbon content of algal cells, The molecular weight of CO2 is... It is the atomic weight of C.

[0014] Furthermore, in step S5, the algal solution concentration after harvest is calibrated using a formula to maintain a stable concentration of 1.5-2.0 g·L⁻¹. -1 This forms a small-scale environmental parameter feedback control cycle based on spiral turbulence to enhance mass transfer, and a large-scale long-term operation cycle based on semi-continuous feeding culture.

[0015] The advantages of this invention compared to the prior art are: This invention achieves a dual improvement in microalgal carbon fixation efficiency and cultivation efficiency through the synergistic combination of a spiral baffle structure and a precise multi-environmental parameter control system specific to Chlorella. Simultaneously, it optimizes reactor mass transfer characteristics and system operational stability, demonstrating significant technical effects, as detailed below: 1. Significantly improved core carbon sequestration performance: This invention enhances mass transfer through a spiral baffle and dynamically adapts and controls multiple environmental parameters, stabilizing the CO2 emission reduction rate at 58.69%-62.3%, with an average emission reduction rate of 60.5%, and a maximum CO2 fixation rate of 3.8 g·L⁻¹. -1 ・d -1 This effectively improves the conversion efficiency of CO2 fixation in industrial flue gas, providing an efficient technical path for carbon emission reduction and fully meeting the implementation requirements of the "dual carbon" goal.

[0016] 2. Significantly improved microalgae cultivation efficiency: Specific environmental parameter regulation was achieved for the domesticated and screened high-efficiency carbon-fixing microalgae Chlorella sp. AE10 and Chlorella sp. Cv, enabling Chlorella sp. AE10 to achieve a maximum specific growth rate of 1.144 days. -1 Chlorella sp. Cv reached 0.9824d -1 The peak concentration of microalgal biomass increased to 2.8 g·L⁻¹. -1 Compared with traditional empty tube reactors, it improves efficiency by 40%, achieving a balance between carbon fixation efficiency and microalgae biomass production, thus enhancing the industrial value of microalgae cultivation.

[0017] 3. The mass transfer characteristics of the reactor are fundamentally optimized: The spiral baffle structure inside the reactor changes the movement trajectory of gas and algal liquid, extending the bubble residence time from the traditional 20s to 30-40s, increasing the gas-liquid contact area by 32%-50%, and improving the overall gas-phase volume mass transfer coefficient by 50% compared to empty tubes. This effectively solves the technical problems of low mass transfer efficiency, short bubble residence time, and uneven contact between microalgae and gas in traditional photobioreactors, while avoiding the problem of microalgae sedimentation and reducing the microalgae mortality rate by 30% compared to traditional reactors.

[0018] 4. Achieve precise dynamic adaptation and control of the cultivation environment: A comprehensive and precise control system for light, pH, exhaust gas concentration, temperature, and recovery cycle has been established. Parameters are dynamically adjusted for different growth stages and algal species of Chlorella. Automatic parameter adjustment and abnormal alarms are achieved through real-time monitoring and intelligent closed-loop control, avoiding problems such as local concentration gradients, pH imbalance, and temperature fluctuations. This ensures that the cultivation system is always in the optimal environment for Chlorella carbon fixation and growth, and the stability and controllability of the system operation are greatly improved.

[0019] 5. Significantly reduces system operating energy consumption and cost, and improves engineering applicability: The algal solution is autonomously circulated by the buoyancy of bubbles and the guidance of the spiral surface, eliminating the need for additional stirring devices. Energy consumption is reduced by 60% compared to mechanically stirred reactors, and the operating noise is ≤50dB. The semi-continuous culture and circulation operation mode is adopted, with 1 / 3 of the algal solution harvested each time and an equal amount of fresh culture medium added to maintain a stable algal solution concentration in the reactor, achieving continuous carbon fixation operation. Moreover, the reactor has not experienced problems such as algal blockage or decreased mass transfer efficiency after 3 months of continuous operation, which greatly improves the service life of the equipment and the feasibility of engineering applications.

[0020] 6. Achieving synergistic treatment and resource utilization of multiple pollutants: The Chlorella species adapted to this invention have NO resistance... x SO x Features include the ability to process NO concentrations ≤300ppm. x Utilizing it as a nitrogen source, it simultaneously fixes CO2 and reduces NO in industrial flue gas. x SO x The synergistic treatment avoids the shortcomings of single carbon sequestration in pollutant treatment, realizes the resource utilization of pollutants in waste gas, and improves the environmental benefits and comprehensive utilization value of the technology.

[0021] 7. Providing a standardized technical system for the industrialization of microalgal carbon fixation: This invention clarifies key technical indicators such as reactor structural parameters, environmental control thresholds, carbon fixation efficiency calculation methods, and optimal recovery cycle. Furthermore, through model fitting, it achieves accurate prediction of biomass concentration and carbon fixation efficiency, with an RMSE value ≤ 0.118 g·L⁻¹. -1This provides replicable and practical technical references and data support for the large-scale and standardized promotion of microalgae carbon fixation technology.

[0022] This invention effectively overcomes the bottlenecks of existing technologies in terms of low mass transfer efficiency and poor environmental adaptability in microalgal carbon fixation. Its advantages are not only reflected in the dual improvement of mass transfer efficiency and carbon fixation performance, but also in the dynamic adaptability and controllability of microalgal cultivation under different algal species and industrial waste gas conditions. By enhancing mass transfer through spiral turbulence and precisely coordinating the control of multiple environmental parameters, microalgae can maintain optimal carbon fixation and growth states under various operating conditions, significantly improving the overall stability and efficiency of the microalgal carbon fixation system. Compared with traditional microalgal carbon fixation schemes, this flow field-enhanced environmental adaptation carbon fixation method is more in line with the industrial development trend of modern microalgal carbon fixation technology towards high efficiency, energy saving, and multi-condition adaptability. Attached Figure Description

[0023] Figure 1 This is a flowchart of a microalgae-based carbon fixation method adapted to a spiral turbulence-enhanced flow field, according to the present invention.

[0024] Figure 2 This is a process flow diagram of a microalgae environment adaptation carbon fixation method based on spiral turbulence enhanced flow field according to the present invention.

[0025] Figure 3 This is a schematic diagram of the spiral spoiler.

[0026] Figure 4 This is a schematic diagram of a gas refining device.

[0027] Figure 5 This is a diagram illustrating the growth patterns of microalgae.

[0028] Figure 6 This is a quantitative graph of microalgae growth.

[0029] Figure 7 It is the V(t) graph.

[0030] As shown in the figure: 1. CO2 gas analyzer, 2. gas valve, 3. liquid valve, 4. liquid rotor flow meter, 5. gas rotor flow meter, 6. air compressor, 7. liquid pump, 8. cold light lamp assembly, 9. power switch, 10. culture medium storage tank, 11. check valve. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0032] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0033] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0034] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0035] The following is a detailed description of the microalgae environment adaptation carbon fixation method based on spiral turbulence enhanced flow field according to the present invention, with reference to the accompanying drawings.

[0036] Combined with appendix Figure 1-7 This invention will be described in detail below.

[0037] A method for microalgal environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field includes the following steps: S1, Construction of a spiral baffle photobioreactor This embodiment employs a column-type photobioreactor based on a helical baffle plate. The column-type photobioreactor is constructed with a helical baffle plate structure arranged axially inside the reactor. The helical baffle plate alters the upward path of the introduced gas, causing the gas to flow in a helical upward motion within the reactor.

[0038] Under the influence of spiral turbulence, the culture medium forms a stable rotating flow field, thereby prolonging the residence time of bubbles and increasing the gas-liquid contact area, so that CO2 is evenly distributed in the culture system, providing a basis for enhanced mass transfer for microalgae cultivation and environmental control.

[0039] The reactor is equipped with a gas inlet, a culture medium outlet, and parameter monitoring devices for subsequent operation monitoring and control.

[0040] The specific structural parameters are as follows: The reactor body is made of polymethyl methacrylate (acrylic), with a total volume of 30L and an effective culture volume of 27L. The algal solution depth is calculated using the formula... It has a light transmittance of ≥92% and combines heat preservation and anti-aging properties; among which, The depth of the algal solution is (m). The effective culture volume of the reactor (m³) 3 ), The inner radius of the reactor (m) is given in this embodiment. =0.027m3, = 0.115m, calculated as follows = 0.66m.

[0041] Spiral baffle: Installed parallel to the inner wall of the reactor, made of transparent acrylic material, with a spiral helix angle of 30°, a pitch of 15cm, and a plate thickness of 5mm. The edge is close to the inner wall of the tube, and the fluid is disturbed through the tortuous channel of the spiral surface.

[0042] Gas refiner: The gas refiner uses transparent acrylic material, which not only has a good visual effect but also better toughness and durability; it adopts the nano MBK process to design a honeycomb microporous structure. When carbon dioxide gas passes through the internal honeycomb structure, it is cut multiple times by different pore sizes, resulting in finer and denser bubbles that are not easily blocked by algae after long-term use and are easy to clean; it can refine gas from 360°, with a large gas output and high refining efficiency.

[0043] Auxiliary components: The reactor is equipped with a detachable cold light lamp group 8 with adjustable light intensity; a gas inlet and liquid circulation port are set at the bottom, and a gas outlet and algal liquid harvesting port are set at the top; it is equipped with a CO2 gas analyzer, temperature sensor, pH sensor and flow controller.

[0044] S2. Chlorella sp. pretreatment and inoculation initiation Highly efficient carbon-fixing algae, Chlorella sp. AE10 and Chlorella sp. Cv (which were selected through laboratory domestication and screening and possess NO resistance), were chosen. x SO x (Characteristics), the following pretreatment is performed before inoculation: S21. Resuscitation Culture: Inoculate the algal strain into culture medium storage tank 10 and incubate at 25℃, light intensity of 9000 Lux, and aeration rate of 0.15 vv. -1 m -1 Cultured under the following conditions until the logarithmic growth phase (OD680≈1.2, biomass concentration 0.8-1.0 g•L) -1 ); S22. Inoculation Preparation: Collect algal sludge by centrifugation, wash twice with sterile culture medium, and adjust the inoculation concentration to 0.5 g•L. -1 (Dry weight) Ensure that the initial biomass concentration (C0) of the algal solution in the reactor is stable at 0.5 ± 0.05 g•L after inoculation. -1 The initial biomass concentration is calibrated using the following formula: ; in, This represents the initial biomass concentration. The dry weight (g) of the algal sludge after centrifugation. The effective culture volume of the reactor (L).

[0045] S23. Start-up process: First, the pretreated algal solution is pumped into the reactor through a liquid pump and the feed inlet is closed; the gas washing device adjusts the composition and flow rate of the mixed gas, and after being dispersed by the gas refiner, it is introduced into the reactor. The spiral baffle drives the bubbles to rise spirally, enhancing the gas-liquid contact.

[0046] S3. Environmental factors based on helical turbulence-enhanced mass transfer To improve the carbon fixation efficiency (CO2 emission reduction rate ≥60%) and specific growth rate of Chlorella With the goal of [missing information], the culture system is continuously monitored during reactor operation, including light conditions, pH value, exhaust gas concentration, temperature, and recovery cycle. The monitoring data is used to determine the reactor's operating status under helical turbulent flow conditions. When the monitored parameters deviate from the set range, the culture environment is adjusted based on the monitoring results, as follows: Lighting conditions Light intensity: dynamically adjusted according to the growth stage of Chlorella. During the logarithmic growth phase (1-4d), the light intensity is 9000 Lux, and during the stationary phase (5-7d), it is adjusted to 7000 Lux to avoid strong light inhibition. Irradiance cycle: A simulated natural cycle of 12 hours of light / 12 hours of darkness is adopted. The light intensity is adjusted by the power of 8 cold light lamp groups (1-3 50W lamp tubes combined), and is fed back and calibrated in real time by the light energy balance monitoring module. The incident light intensity on the surface of the photobioreactor is expressed as the average light intensity (Eav), calculated by the formula: ;in, The average light intensity is (Lux). The luminous flux of a single lamp (lumen lm). For the number of light tubes, The space utilization coefficient is set to 0.7. The maintenance factor is set to 0.8. The illuminated area (m²) 2 ); Light uniformity: The spiral baffle drives the algal liquid to move in a spiral motion, causing the microalgal cells to move back and forth between the light and dark areas, reducing the difference in light gradient and improving the utilization rate of light energy.

[0047] pH value Suitable range: The optimal pH for Chlorella carbon fixation is 7.5-8.5. pH dynamic equilibrium is achieved by adjusting the CO2 concentration in the exhaust gas. The relationship between CO2 concentration and pH can be approximately estimated using the following formula: ;in, The concentration of bicarbonate ions in the culture medium (mol•L) -1 ), The concentration of dissolved CO2 in the algal solution (mol•L) -1 This can be calculated using gas partial pressures; Regulation mechanism: When the sensor detects pH < 7.5, the proportion of CO2 in the mixed gas is reduced; when pH > 8.5, the proportion of CO2 is increased. At the same time, the mixing of algal solution is enhanced by the use of spiral baffles to avoid local pH imbalance. Buffer aid: Add 5 mmol•L -1 Sodium bicarbonate acts as a pH buffer, enhancing system stability.

[0048] exhaust gas concentration Using simulated industrial flue gas as the treatment target, the exhaust gas composition is 10% CO2 (volume fraction), combined with different concentrations of NO. x with SO x The specific adjustments are as follows: CO2 concentration: Base concentration 10%, finely adjusted according to the growth status of algae. During the logarithmic growth phase, the CO2 concentration is maintained at 10%, and reduced to 8% during the stationary phase to avoid inhibition by high concentrations of CO2. NO x with SO x Concentration: Referring to the optimal gas conditions in Table 2, Chlorella sp. AE10 is suitable for 10% CO2 + 100ppm NO. x +50ppm SO x Chlorella sp. Cv is suitable for 10% CO2 + 200ppm NO x +100ppm SO x NO x When the concentration is ≤300ppm, it can be used as a nitrogen source by Chlorella. The conversion between gas volume concentration and mass concentration is achieved by the following formula: ;in, Gas mass concentration (mg / m³) 3 ), This refers to the gas volume concentration (ppm). The molar mass of the gas (g / mol, NO) x Take 46 g / mol, SO x Take 64 g / mol). The pressure is the gas pressure (Pa, taken as 101325Pa). is the gas constant (taken as 8.314 J / (mol•K)). The gas thermodynamic temperature (K); Ventilation parameters: Total flow rate of mixed gas 1.5-7 L / min -1 Ventilation rate 0.15-0.2vv -1 m -1 The residence time of the bubbles is precisely controlled by a gas rotor flow meter and calculated using a formula: ;in, The bubble residence time (s) is given. The gas volumetric flow rate is expressed in L / s. Set the helical spoiler lift angle (take 30°); ensure that the dwell time under the action of the helical spoiler is ≥30s.

[0049] temperature Suitable temperature: The optimal growth temperature for Chlorella is 25±3℃. Waste heat recovery is achieved through an internal combustion engine cogeneration heat management system. The heat exchange rate is calculated using the following formula: ;in Heat exchange rate (kJ / h) For the effective thermal efficiency, let's take 0.35. The temperature of the gas inside the cylinder (K, taken as 800K). The cooling water temperature is K, taken as 298K. Control method: The exhaust gas is washed and cooled to 25°C before being introduced into the reactor. An insulation layer is installed on the outside of the reactor. Temperature sensors monitor the temperature in real time. When the temperature is <22°C, the heating element is activated. When the temperature is >28°C, the cooling water circulation is activated to ensure that the temperature fluctuation of the algal solution is ≤±1°C. Thermal equilibrium maintenance: Utilizing the dynamic balance between engine combustion heat and environmental heat dissipation, the environmental heat dissipation is calculated using the following formula: ; in, The convective heat transfer coefficient (W / (m) 2 •K), take 8W / (m 2 •K)), The reactor wall area (m²) 2 ), The temperature is the reactor wall temperature (K). The ambient temperature (K) is the ambient temperature. Let be the Stefan-Boltzmann constant (taken as 5.67 × 10⁻⁶). -8 W / (m 2 •K 4 )), The wall emissivity is set to 0.9 to ensure temperature stability.

[0050] recycling cycle Based on the optimal harvest decision model under the dynamic efficiency principle, the recovery period is determined as follows: First, assume that P and C do not change with time, and that the microalgal growth pattern follows the above... Figure 5 .

[0051] Specifically, the quantification is as follows: the growth rate first gradually increases, then gradually decreases, slowly decreasing to zero, and finally becoming negative. Therefore, attached... Figure 7 The V(t) graph can be obtained from the attached graph. Figure 6 Points earned; Model parameters: Define the net solid carbon formula: ;in, Net solid carbon content (g•L) -1 ), For mortality rate, , Carbon sequestration per unit volume of algal solution (g•L) -1 (which varies with time t) The carbon decay coefficient is taken as 0.02d. -1 ), This refers to the carbon sequestration capacity per unit volume of inoculum. (Carbon content 47%) Optimal period: by solving the first-order condition The optimal recovery period for Chlorella sp. AE10 was determined to be 7 days, and for Chlorella sp. Cv, it was 8 days, at which point the net carbon fixation was maximized and the biomass concentration reached its maximum. The maximum biomass concentration was fitted using the following formula: ; in, Biomass concentration at time t (g•L) -1 ), This represents the initial biomass concentration. for Time-to-growth rate (d) -1 ).

[0052] S4, Carbon Sequestration Process Monitoring Real-time monitoring: Through the microalgae cultivation and exhaust gas dynamic balance monitoring software, data such as temperature, light intensity, pH value, CO2 inlet and outlet concentration, and biomass concentration are collected in real time, with a data storage cycle of 10 minutes / time; Abnormal regulation: When the average daily biomass growth is monitored to be <0.1 g•L -1 •d -1 When the pH deviates from 7.5-8.5 or the CO2 emission reduction rate is less than 55%, the system will automatically alarm and adjust the corresponding parameters. Daily growth is calculated using the following formula: Calculate, where, Average daily growth (d) -1 ), The dry weight of harvested algal cells (g•L) -1 ), The dry weight of algal cells in the inoculum (g•L) -1 ), The cultivation time is d. The emission reduction rate is calculated using the following formula: Calculate, where η is the CO2 emission reduction rate (%). The CO2 concentration (vol%) at the reactor inlet. The CO2 concentration (vol%) at the reactor outlet.

[0053] Carbon sequestration efficiency calculation: In addition to the emission reduction rate, the CO2 fixation rate is calculated using the following formula: Calculate, where, CO2 fixation rate (g•L) -1 •d -1 ), The carbon content of algal cells is 0.47. The molecular weight of CO2 is 44 g / mol. The atomic weight of C is 12 g / mol.

[0054] S5, Semi-continuous culture and cyclic operation When the culture system reaches the set recovery cycle, the system adopts a semi-continuous harvesting method, harvesting 1 / 3 of the algal solution volume each time, while simultaneously replenishing an equal amount of fresh culture medium and inoculum to maintain the algal solution concentration in the reactor at a stable level of 1.5-2.0 g•L. -1 To achieve continuous carbon fixation, the algal solution concentration after harvest is calibrated using the following formula: ;in, Pre-harvest algal solution concentration (g•L) -1 ), To replenish the inoculum concentration (g•L) -1 ).

[0055] After feeding, under the continuous action of the spiral turbulent flow field, the newly added culture medium is rapidly mixed with the original culture system, and the reactor re-enters the culture and environmental control stage, achieving continuous cycle operation.

[0056] Small-scale cycles and long-term large-scale cycles based on semi-continuous feeding culture are used to achieve stable and continuous carbon fixation operation of the reactor.

[0057] The microalgae-based carbon fixation method adapted to the environment, based on a spiral-turbulent enhanced flow field, provided by this invention, has significant advantages, particularly in improving microalgae carbon fixation efficiency, enhancing microalgae cultivation efficiency, and increasing system operational stability, demonstrating strong application value. Traditional microalgae carbon fixation technologies typically suffer from low mass transfer efficiency and coarse environmental parameter control, failing to adequately adapt to the growth and carbon fixation characteristics of *Chlorella vulgaris* in industrial flue gas treatment environments. In contrast, this invention, by constructing a spiral-turbulent plate photobioreactor and combining it with a precise multi-environmental factor control scheme specific to *Chlorella vulgaris*, enables efficient and stable carbon fixation and microalgae cultivation under industrial exhaust gas treatment conditions, providing reliable technical support for the industrial application of microalgae carbon fixation.

[0058] The spiral baffle photobioreactor of this invention can simulate the actual working conditions of industrial flue gas treatment, overcoming the limitations of traditional photobioreactors such as low mass transfer efficiency and short bubble residence time. By altering the gas-liquid motion trajectory through the spiral baffle structure, the bubble residence time can be precisely extended to 30-40 seconds, significantly increasing the gas-liquid contact area by 32%-50%. Especially under high-density microalgae cultivation conditions, it can still ensure efficient carbon source transfer and dissolution, and the test results are more consistent with actual industrial application scenarios. In addition, by adjusting the spiral baffle flow field in conjunction with the coordinated control of multiple parameters such as light, pH, temperature, and exhaust gas concentration, the system can optimize the carbon fixation performance of Chlorella at different growth stages, ensuring that the microalgae maintain optimal growth and carbon fixation throughout the entire cultivation cycle, thereby improving overall carbon fixation efficiency and biomass production.

[0059] The innovation of this invention in microalgal carbon fixation technology lies in its dynamic closed-loop control mechanism for environmental parameters. This mechanism not only enables precise control of the Chlorella growth environment based on enhanced mass transfer through spiral turbulence, but also provides direct data for the operation and optimization of the microalgal carbon fixation system. Researchers can flexibly adjust environmental control parameters under different waste gas compositions and load conditions based on real-time monitored data such as biomass and CO2 emission reduction rates, avoiding over-reliance on traditional immobilized cultivation methods and ensuring the long-term stability and reliability of microalgal carbon fixation efficiency. Simultaneously, precise parameter adjustment based on the specific characteristics of Chlorella can also avoid microalgal growth inhibition caused by strong light, high CO2 concentrations, and local pH imbalances, thereby reducing microalgal mortality and improving the overall efficiency of microalgal cultivation.

[0060] The reactor structure and system design of this invention are compact, easy to integrate, and convenient to maintain. Compared with traditional mechanically stirred photobioreactors, it significantly reduces energy consumption and operating costs. The modular design of the reactor allows for flexible disassembly and replacement of components such as the helical baffle, gas aerator, and monitoring components, adapting to the carbon sequestration requirements of different algal species and industrial waste gas conditions. Simultaneously, the stirless mass transfer design based on helical baffles utilizes bubble buoyancy to achieve natural circulation of the algal solution, reducing energy consumption by 60% compared to traditional reactors. Furthermore, the accompanying acrylic viewing window and online monitoring system enable intuitive observation and intelligent control of operating conditions, reducing the risks of manual operation and maintenance, and further enhancing the industrial feasibility and economic viability of the technology.

[0061] This invention achieves integrated adaptation between microalgae carbon fixation and industrial flue gas emission reduction, overcoming the problems of disconnect between carbon fixation and waste gas treatment, and low resource utilization rates in traditional technologies. Through pretreatment and precise proportioning of industrial flue gas, CO2 and low-concentration NO are reduced. x / SO xBy converting these into carbon and nitrogen sources for microalgae growth, the system achieves both industrial waste gas emission reduction and high-value microalgae biomass, realizing the dual benefits of "environmental protection and emission reduction - resource recovery." Furthermore, the semi-continuous cultivation and cyclic operation mode design allows the system to be connected to industrial waste gas outlets for continuous carbon fixation treatment without frequent start-ups and shutdowns, significantly improving the technology's industrial adaptability and providing an efficient biological solution for achieving industrial "dual carbon" goals.

[0062] The specific implementation process of the microalgae environment adaptation carbon fixation method based on spiral turbulence enhanced flow field of the present invention is as follows: To prepare for gas supply, start the air compressor 6 to allow compressed air to enter the system's gas delivery pipeline; slowly open the gas valve 2 to allow the gas to pass through the gas rotor flow meter 5 and enter the photobioreactor; observe the changes in the flow reading of the gas rotor flow meter 5. When the gas flow rate stabilizes within the set range, the gas supply stabilization process is completed, providing a continuous and stable gas source for subsequent microalgae cultivation.

[0063] Culture medium injection and system initialization: Open the liquid valve 3 at the outlet of the culture medium storage tank 10, start the liquid pump 7, and transport the culture medium from the culture medium storage tank 10 to the reactor. During the transportation process, the flow rate of the culture medium is monitored by the liquid rotor flow meter 4. The inlet speed of the culture medium is controlled by adjusting the opening of the liquid valve 3. When the liquid level in the reactor reaches the operating requirements, close the liquid valve 3 and stop the operation of the liquid pump 7 to complete the establishment of the culture system.

[0064] After the culture medium and gas supply are stabilized, the cold light lamp group 8 is turned on, and the power switch 9 controls the power supply to the light system, so that a continuous and stable light environment is formed outside the reactor. The operating intensity of the cold light lamp group 8 is adjusted according to the growth requirements of microalgae to maintain the light conditions within the suitable range for microalgae growth, thereby establishing a stable photosynthetic culture environment.

[0065] During gas-liquid coupling culture operation, gas valve 2 is kept open, allowing gas to continuously enter the culture system from the bottom of the reactor, forming a bubble-induced turbulent flow field. As the gas rises in the culture solution, it enhances the mixing and gas-liquid mass transfer efficiency of the system, improves the solubility and diffusion of carbon dioxide in the liquid phase, thereby promoting the absorption and utilization of carbon dioxide by microalgae and achieving a continuous carbon fixation culture process.

[0066] During the dynamic monitoring of the carbon fixation process, the CO2 gas analyzer 1 is used to detect the gas concentration at the inlet and outlet of the reactor in real time. The carbon fixation efficiency of the system is obtained by comparing the changes in carbon dioxide concentration in the inlet and outlet gases. The opening degree of the gas valve 2 is adjusted according to the detection results, and the gas supply is dynamically controlled by combining the flow data of the gas rotor flowmeter 5, so that the system maintains a high-efficiency and stable operating state.

[0067] After the culture is completed and the system is shut down, first close the gas valve 2 and stop the air compressor 6, then turn off the cold light group 8 and the power switch 9; open the liquid valve 3 to discharge the culture medium, and prevent the liquid from flowing back into the gas pipeline system through the outlet check valve 11, thus completing the overall shutdown process of the device.

[0068] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for microalgal environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field, characterized in that, Includes the following steps: S1. Construct a column-type photobioreactor, and install a spiral baffle structure along the axial direction inside the reactor; the spiral baffle is used to change the upward path of the introduced gas, so that the gas forms a spiral upward flow state inside the reactor; the reactor is equipped with a gas inlet, a culture medium outlet and a parameter monitoring device for subsequent operation monitoring and control. S2. Chlorella pretreatment and inoculation: Select acclimatized and screened chlorella species with NO resistance. x SO x The highly efficient carbon-fixing algae Chlorella sp. AE10 and Chlorella sp. Cv were first tested at 25°C, under a light intensity of 9000 Lux and an aeration rate of 0.15 vv. -1 m -1 Under controlled conditions, the algae were revived and cultured until the logarithmic growth phase; the algal sludge was collected by centrifugation and washed twice with sterile culture medium, and the inoculum concentration was adjusted to 0.5 g·L⁻¹. -1 This stabilized the initial biomass concentration of the algal solution in the reactor at 0.5 ± 0.05 g·L⁻¹. -1 The pretreated algal solution is pumped into the reactor. The mixed gas, which is regulated by the gas washing device, is dispersed by the gas refiner and then introduced into the reactor. The spiral baffle drives the bubbles to rise spirally to enhance the gas-liquid contact. S3. Precise control of environmental factors based on helical turbulence-enhanced mass transfer: with CO2 emission reduction rate ≥60% and specific growth rate ≥0.8d. -1 To achieve this goal, the cultivation system is continuously monitored and environmental parameters are dynamically adjusted, including light intensity, pH, exhaust gas concentration, temperature, and harvest cycle. S4. Real-time monitoring and abnormal control of carbon fixation process: Using microalgae cultivation and exhaust gas dynamic balance monitoring software, data on temperature, light intensity, pH value, CO2 inlet and outlet concentrations, and biomass concentration are collected at 10-minute intervals; when the average daily biomass growth is <0.1 g·L⁻¹. -1 ・d -1 When the pH deviates from 7.5-8.5 or the CO2 emission reduction rate is less than 55%, an automatic alarm will be triggered and the corresponding parameters will be adjusted; at the same time, the CO2 fixation rate will be calculated using a formula to characterize the carbon fixation efficiency. S5. Semi-continuous culture and cyclic operation: When the optimal harvest cycle is reached, a semi-continuous harvesting method is adopted, harvesting 1 / 3 of the algal solution each time, while simultaneously replenishing an equal amount of fresh culture medium and inoculum solution to stabilize the algal solution concentration in the reactor at 1.5-2.0 g·L⁻¹. -1 After feeding, the new and old culture media are rapidly mixed by the spiral turbulent flow field, and the reactor re-enters the cultivation and control stage, forming a continuous cycle operation.

2. The method for microalgal environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field according to claim 1, characterized in that: In step S2, the initial biomass concentration is calculated as follows: ,in, This represents the initial biomass concentration. The dry weight of the algal sludge after centrifugation. The effective culture volume of the reactor.

3. The method for microalgal environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field as described in claim 1, characterized in that: In step S3, the adjustment of the environmental parameters specifically involves: Light control: The light intensity is 9000 Lux during the logarithmic growth phase and adjusted to 7000 Lux during the stationary phase. A 12-hour light / 12-hour dark cycle is adopted. The light intensity is adjusted by the power of the cold light lamp group, and the spiral baffle drives the algal liquid to move in a spiral motion to improve the uniformity of light. pH control: Maintain the optimal pH for Chlorella carbon fixation at 7.5-8.

5. Achieve dynamic pH balance by adjusting the CO2 concentration in the exhaust gas. Add 5 mmol·L⁻¹ -1 Sodium bicarbonate acts as a pH buffer, reducing the proportion of CO2 in the mixed gas when pH < 7.5 and increasing the proportion of CO2 when pH > 8.

5. Exhaust gas concentration control: The basic CO2 volume fraction of the mixed exhaust gas is 10%, maintained at 10% during the logarithmic growth phase and reduced to 8% during the stationary phase; Chlorella sp. AE10 is suitable for 10% CO2 + 100ppm NO. x +50ppm SO x Chlorella sp. Cv is compatible with 10% CO2 + 200ppm NO. x +100ppm SO x NO x Concentration ≤300ppm; Total flow rate of mixed gas 1.5-7L·min -1 Ventilation rate 0.15-0.2vv -1 m -1 Ensure that the bubble residence time is ≥30s; Temperature control: Maintain the optimal growth temperature of 25±3℃. The exhaust gas is washed and cooled to 25℃ before being introduced. An insulation layer is installed on the outside of the reactor. The heating element is activated when the temperature is <22℃ and the cooling water circulation is activated when the temperature is >28℃ to ensure that the temperature fluctuation of the algal solution is ≤±1℃. Harvest cycle regulation: Based on the net carbon sequestration formula, the optimal harvest cycle was calculated. The optimal recovery cycle for Chlorella sp. AE10 was 7 days, and for Chlorella sp. Cv it was 8 days, at which point the biomass concentration reached 2.5-3.0 g·L⁻¹. -1 .

4. The method for microalgal environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field as described in claim 3, characterized in that: In step S3, the light intensity is adjusted by the power of the cold light lamp group 8, and is fed back and calibrated in real time by the light energy balance monitoring module. The incident light intensity on the surface of the photobioreactor is represented by the average light intensity. ;in, The average light intensity, The luminous flux of a single lamp tube. For the number of light tubes, The space utilization coefficient is set to 0.

7. The maintenance factor is set to 0.

8. This represents the illuminated area.

5. The method for microalgal environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field according to claim 3, characterized in that: In step S3, the correlation between the CO2 concentration and pH value is approximated: ;in, This refers to the concentration of bicarbonate ions in the culture medium. The concentration of dissolved CO2 in the algal solution is calculated using gas partial pressure.

6. The method for microalgal environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field according to claim 3, characterized in that: In step S3, the formula for the heat exchange amount of temperature regulation is: ;in For heat exchange quantity, For the effective thermal efficiency, let's take 0.

35. The temperature of the gas inside the cylinder. This refers to the cooling water temperature.

7. The method for microalgal environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field according to claim 3, characterized in that: In step S3, the formula for calculating the net solid carbon content is: ;in, Net carbon solids For mortality rate, This refers to the carbon sequestration capacity per unit volume of algal solution. The carbon decay coefficient, The carbon sequestration capacity per unit volume of inoculum; the maximum biomass concentration is expressed by the formula. Fit, where, Let be the biomass concentration at time t. This represents the initial biomass concentration. for Time is compared to growth rate.

8. The method for microalgal environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field according to claim 1, characterized in that: In step S4, the average daily biomass growth is determined by the formula... Calculate; where, This represents the average daily growth. The dry weight of the harvested algal cells, This represents the dry weight of algal cells in the inoculum. The cultivation time; the CO2 emission reduction rate is expressed by the formula Calculate, where η is the CO2 emission reduction rate. The CO2 concentration at the reactor inlet. The CO2 concentration at the reactor outlet; the CO2 fixation rate is expressed by the formula... Calculate, where, For a fixed rate of CO2, Carbon content of algal cells, The molecular weight of CO2 is... It is the atomic weight of C.

9. A method for microalgal environment adaptation and carbon fixation based on spiral turbulence-enhanced flow field according to claim 1, characterized in that: In step S5, the algal solution concentration after harvest is calibrated using a formula to maintain a stable concentration of 1.5-2.0 g·L⁻¹. -1 This forms a small-scale environmental parameter feedback control cycle based on spiral turbulence to enhance mass transfer, and a large-scale long-term operation cycle based on semi-continuous feeding culture.

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