A uniform gas distribution optimization design method for a gas flow distributor of a biogas liquid reactor

Abstract

This invention provides a method for optimizing the uniform gas distribution of an airflow distributor in a biogas-liquid reactor, belonging to the technical field of biogas-liquid reactors. It solves the problem of the lack of a systematic optimization method in existing technologies. The method includes: estimating the critical velocity for seepage at the jet orifices; calculating and initially selecting the required number of jet orifices, the total length and number of all jet pipes, and initially selecting the airflow distributor structure; determining the frictional resistance coefficient f, momentum recovery coefficient k, and jet orifice flow coefficient c; analyzing the pressure drop distribution characteristics along the pipe length and the total pressure loss within the pipe; based on the analysis results, determining the airflow distributor parameter combination that meets the conditions; and outputting the final airflow distributor design parameters when the jet velocity and non-uniformity of each jet orifice simultaneously meet the preset seepage prevention conditions and non-uniformity requirements. This invention achieves optimized design of the airflow distributor structure.

Description

Technical Field

[0001] This invention belongs to the field of biogas-liquid reactor technology and relates to a method for optimizing the uniform gas distribution of a biogas-liquid reactor gas flow distributor. Background Technology

[0002] In bubble-type bioreactors, gas distributors propel lighter phases such as air and carbon dioxide into the liquid environment in the form of bubbles through jet orifices, completing the physical processes of bubble transport and diffusion within the reactor's liquid environment. For animal cell immersion culture within bubble-type bioreactors, the gas jet serves to maintain dissolved oxygen, carry carbon dioxide, and provide the necessary liquid concentration for cell development, growth, and reproduction. Although the gas transport in the form of bubbles is essential for cell reproduction, the shear stress generated by the formation, development, deformation, oscillation, and collapse and coalescence of bubbles on the surface of the gas distributor's jet orifices is a significant factor in cell damage. This is especially true in large-scale, high-efficiency commercial reactors where high-speed gas jets and high bubble movement velocities pose a fatal threat to sensitive species such as animal cells and certain bacterial cells.

[0003] In processes such as animal cell culture, the intense turbulence, high shear forces, and bubble breakage caused by high gas jet velocities (e.g., exceeding 30 m / s) are the main causes of cell damage and death. Simultaneously, uneven jet velocity distribution exacerbates problems such as "weeping seepage" and orifice blockage, creating a vicious cycle that severely impacts reactor efficiency and stability. Existing research focuses heavily on reactor parameters (such as gas content and mass transfer), but lacks systematic optimization methods and universal design principles for the gas distributor itself, especially for the uniform gas distribution design of multi-branch structures.

[0004] The reasons for this are as follows: (1) the intrinsic relationship between jet uniformity, pressure redistribution and frictional pressure drop in multi-branched porous pipes is not well understood; (2) the internal flow mechanism is complex and heavily dependent on geometric parameters, and the relevant fluid dynamics laws need to be further revealed; (3) the experimental data for supporting models and simulation studies are insufficient, making it difficult to effectively guide engineering design. Therefore, establishing a set of general optimization design methods and processes for radial multi-branched straight pipe annular airflow distributors has become an urgent need to improve the performance of bioreactors and achieve efficient commercial scale-up. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a method for optimizing the uniform gas distribution of a gas flow distributor in a biogas-liquid reactor. The technical problem to be solved is: how to optimize the design of the gas flow distributor structure to improve cell culture efficiency.

[0006] The objective of this invention can be achieved through the following technical solution: a method for optimizing the uniform gas distribution of a gas flow distributor in a biogas-liquid reactor, wherein the gas flow distributor comprises a jet pipe, jet holes on the jet pipe, and a pipe end head, and the method for optimizing the uniform gas distribution of the gas flow distributor in the biogas-liquid reactor includes the following steps:

[0007] S1. Based on the given range of jet orifice diameter, the range of the ratio of orifice spacing to jet orifice diameter, gas-liquid physical properties, and liquid phase height in the reactor, estimate the critical velocity for jet orifice seepage to ensure that seepage does not occur.

[0008] S2. Based on the critical velocity of seepage through the jet orifice and the set apparent gas flow velocity, calculate and initially select the required total number of jet orifices, the total length of all jet tubes, and the required number of jet tubes; and initially select the airflow distributor structure with the jet tube diameter and the tube end diameter as parameter variables.

[0009] S3. Based on the gas flow characteristic parameters and the initially selected combination of airflow distributor parameters, determine the frictional resistance coefficient f, momentum recovery coefficient k, and jet orifice flow coefficient c.

[0010] S4. Based on the given pressure value of the jet pipe and the mass flow rate of the jet pipe, calculate the pressure distribution along the length of the jet pipe, and analyze the pressure drop distribution characteristics along the length of the pipe and the analysis results of the total pressure loss in the pipe.

[0011] S5. Given the pressure drop ratio criterion for characterizing jet velocity uniformity, determine the airflow distributor parameter combination that satisfies the pressure drop ratio criterion based on the pressure drop ratio criterion and the analysis results in step S4.

[0012] S6. Based on the airflow distributor parameter combination determined in step S5, calculate the jet velocity of each jet hole and the non-uniformity distribution of the jet velocity of multiple jet holes. When the jet velocity of the jet holes and the non-uniformity distribution simultaneously meet the preset seepage prevention conditions and non-uniformity requirements, output the final airflow distributor design parameters; otherwise, return to step S2, re-select the required number of all jet holes, the total length of all jet pipes, and the required number of jet pipes, and initially select the airflow distributor with the jet pipe diameter and the pipe end diameter as parameter variables.

[0013] In the application of this biogas-liquid reactor gas distributor uniform gas distribution optimization design method, the critical velocity for jet hole seepage that ensures the jet velocity does not exhibit seepage phenomena is first estimated. Then, based on the critical velocity for seepage, the total length of the jet tube, the number of jet tubes, and the number of jet holes are determined. Next, using the jet tube diameter and the diameter of the tube end as key variables, several gas distributor structural schemes are initially selected. For each initially selected structure, based on its specific geometric parameters and gas flow characteristic parameters (Reynolds number, etc.), the frictional resistance coefficient f, momentum recovery coefficient k, and jet hole flow coefficient c are calculated. Then, the pressure distribution is calculated, and the pressure drop distribution characteristics along the tube length and the total pressure loss within the tube are analyzed. This allows for the selection of the optimal combination of jet tube diameter and tube end diameter that achieves the best pressure balance, ensuring that the uniformity of the jet velocity in each jet hole meets the pressure drop ratio criterion. This step is crucial for ensuring uniform flow rate in each hole. For the selected airflow distributor, the actual jet velocity of each jet orifice is calculated, and its non-uniformity is evaluated. If the calculation results simultaneously meet the preset anti-leakage conditions and non-uniformity requirements, the airflow distributor structure can be determined as a superior design, and the final airflow distributor design parameters are output. This method fundamentally changes the traditional design process that relies on trial and error based on experience. Through theoretical calculations and quantitative criteria, it achieves optimized design of airflow distributor performance. This not only significantly shortens the development cycle and reduces R&D costs, but more importantly, it ensures that the airflow distributor achieves highly uniform gas distribution within the reactor, thereby effectively reducing cell death caused by local hypoxia or uneven shear force, and significantly improving the process stability and efficiency of cell culture.

[0014] In the above-mentioned method for optimizing the uniform gas distribution of the gas flow distributor in a biogas-liquid reactor, in step S1, the critical velocity of the jet orifice seepage is estimated using the following formula two:

[0015]

[0016] In the formula, The critical velocity for seepage at the jet orifice. Given the diameter of the jet orifice, and g as the acceleration due to gravity, For gas density, The density of liquid water, For liquid height, The distance between the two jet orifices is denoted by , and t is the wall thickness of the jet tube. "Weeping seepage" is a flow instability phenomenon that, once it occurs, completely destroys the uniformity of air distribution. This method first calculates the critical velocity for weeping seepage in the jet orifices, avoiding ineffective design and narrowing the optimization design space to a safe and meaningful range, effectively improving the reliability and efficiency of the airflow distributor structural optimization design.

[0017] In the above-mentioned method for optimizing the uniform gas distribution of the gas flow distributor in a biogas-liquid reactor, in step S2, the total number of all jet holes is calculated using formula three, the total length of all jet tubes is calculated using formula four, and the number of jet tubes is calculated using formula five.

[0018] Formula 3 is as follows: ,

[0019] In the formula, The total number of jet holes, Given the jet orifice diameter, The critical velocity for seepage at the jet orifice. Where is the reactor diameter, The apparent gas jet velocity in the reactor;

[0020] Formula four is as follows: ,

[0021] In the formula, L is the total length of all jet tubes. The distance between the two jet orifices;

[0022] Formula five is: ,

[0023] In the formula, The number of jet tubes, This refers to the length of a single jet tube.

[0024] In this step, the number of jet holes, the total length of the jet tube, and the number of jet tubes are calculated using the critical velocity of the jet hole seepage as a parameter. This can fundamentally ensure the accuracy and safety of the design, and ensure that the parameters are designed without damaging the cells or causing seepage, thereby improving the efficiency of the optimization design.

[0025] In the above-mentioned method for optimizing the uniform gas distribution of the gas flow distributor in a biogas-liquid reactor, in step S3, the frictional resistance coefficient f is obtained by formula six, the momentum recovery coefficient k is obtained by formula seven, and the jet orifice flow coefficient c is obtained by formula eight.

[0026] Formula six is:

[0027] ;

[0028] Formula seven is:

[0029] ;

[0030] Formula 8 is as follows:

[0031] ;

[0032] In the formula, For the local jet orifice Reynolds number, , The mass flow rate entering the jet tube, The mass flow rate through the jet orifice. , The critical velocity for seepage at the jet orifice. The density of hydrogen gas, The cross-sectional area of ​​the jet orifice. The dynamic viscosity of hydrogen. The diameter of the jet tube. Here, is the Euler number, and FA is the effective area of ​​gas flow based on a single jet tube. , Where is the side area of ​​the jet tube, and N is the total number of jet holes.

[0033] Obtaining these coefficients through calculation provides a foundation for more accurate predictions of pressure distribution and velocity uniformity, and helps improve the reliability of optimized airflow distributor design.

[0034] In the above-mentioned method for optimizing the uniform gas distribution of the gas flow distributor in a biogas-liquid reactor, in step S4, the pressure distribution along the length of the jet pipe is calculated using Formula Nine, which is:

[0035] ,

[0036] In the formula, For the pressure distribution along the length of the jet tube, This refers to the inlet pressure at the jet orifice. For the mass flow rate entering the straight jet tube, The mass flow rate through the jet orifice. The density of hydrogen gas, Let be the distance (m) from the head of the pipe end, and q, s, and r be intermediate variables. , , , This represents the gas dynamic viscosity.

[0037] Calculating the pressure distribution along the length of the jet tube is the most crucial and insightful step in the entire airflow distributor design and optimization process. The pressure distribution pattern along the tube length is the core decision-making basis for diagnosing the uniformity of air distribution and achieving precise flow equalization optimization, thus ensuring the accuracy of the airflow distributor optimization design.

[0038] In the above-mentioned method for optimizing the uniform gas distribution of the gas flow distributor in a biogas-liquid reactor, step S4 involves analyzing the pressure drop distribution characteristics along the pipe length and the total pressure loss within the pipe, including:

[0039] The ratio of frictional pressure drop inside the jet tube to pressure drop through the jet orifice is calculated using Formula 11, and the total pressure loss of the airflow distributor is calculated using Formula 12.

[0040] The analysis results are obtained by analyzing the ratio of the calculated frictional pressure drop inside the jet tube to the pressure drop through the jet orifice and the total pressure loss of the airflow distributor.

[0041] Formula eleven is as follows: ,

[0042] Formula 12 is: ,

[0043] In the formula, The frictional resistance pressure drop along the length of the jet tube, For the pressure drop through each jet orifice, The density of hydrogen gas, The gas velocity entering the jet tube, The diameter of the jet tube. The velocity of the gas flow inside the pipe. U is the dimensionless jet velocity.

[0044] In the above-mentioned method for optimizing the uniform gas distribution of the gas flow distributor in a biogas-liquid reactor, the dimensionless jet velocity U is calculated using Formula Fourteen, which is:

[0045] ,

[0046] In the formula, The differential symbol, , , This represents the ratio of the jet hole area to the internal surface area of ​​the pipe. , The diameter of the jet tube. Given the jet orifice diameter, f is the frictional resistance coefficient, k is the momentum recovery coefficient, and c is the jet orifice flow rate coefficient.

[0047] By calculating the ratio of the frictional pressure drop inside the jet tube to the pressure drop through the jet hole, the pressure drop ratio of each structural scheme can be seen from the calculation results. By calculating the total pressure loss of the airflow distributor, the pressure loss of each structural scheme can be seen from the calculation results. The structural scheme that best meets the requirements can be determined quickly and accurately, ensuring that the uniformity of the jet distribution meets the pressure drop ratio judgment condition, and improving the certainty and reliability of the design results.

[0048] In the above-mentioned method for optimizing the uniform gas distribution of the gas flow distributor in a biogas-liquid reactor, in step S6, the critical jet orifice diameter is calculated using formula thirteen.

[0049] Formula thirteen is: ,

[0050] In the formula, Where is the critical jet orifice diameter, and N is the total number of jet orifices. Where is the diameter of the jet tube, and L is the total length of all jet tubes.

[0051] Critical jet orifice diameter Used to finally determine the total number of jet tubes N and the diameter of the jet tubes. When considering structural parameters such as the total length L of all jet tubes, these parameters serve as key verification criteria to ensure the selected jet orifice diameter... Not greater than the critical jet orifice diameter This fundamentally avoids the occurrence of seepage during crying from the structural design perspective.

[0052] In the above-described method for optimizing the uniform gas distribution of the gas flow distributor in a biogas-liquid reactor, in step S6, the jet velocity of each jet orifice is calculated using formula X.

[0053] Formula 10 is:

[0054]

[0055] In the formula, This represents the jet velocity of jet orifice i, where i is the orifice number. Given the external reactor pressure of the gas flow distributor, and These are the pressure values ​​of the i-th jet orifice and the pressure value of the previous orifice number i+1, respectively. and According to Formula 9, c represents the jet orifice flow coefficient;

[0056] The degree of non-uniformity distribution of the jet velocity in a multi-jet orifice is calculated using Formula Fifteen, which is:

[0057] ,

[0058] In the formula, For the non-uniform distribution of jet velocity in multi-jet orifices, The jet velocity is represented by the last hole numbered N in the straight pipe jet orifice distribution along the pipe length. The jet velocity is the first jet hole number 1 distributed along the length of the straight pipe jet hole.

[0059] The non-uniformity distribution of jet velocity in each jet orifice and the jet velocity in multiple jet orifices are calculated and judged against the set judgment conditions. This can verify the final determined gas distributor structural parameters, ensuring that the determined gas distributor structural parameters are the optimal design and help improve cell culture efficiency.

[0060] In the above-mentioned method for optimizing the uniform gas distribution of the gas flow distributor in a biogas-liquid reactor, in step S6, the preset anti-seepage condition is:

[0061] When the jet velocity in the jet orifice is greater than 25% of the critical velocity for seepage prevention in the jet orifice, the jet velocity in the jet orifice is deemed to meet the preset seepage prevention condition.

[0062] The preset non-uniformity requirement is:

[0063] When the non-uniformity of the jet velocity distribution in the multi-jet orifice is less than 15%, the non-uniformity is deemed to meet the preset uniformity requirement.

[0064] Setting this criterion ensures that the jet velocity does not exhibit seepage or leakage during cell culture, and combined with a smaller degree of non-uniformity, reduces damage to cell culture.

[0065] Compared with existing technologies, the uniform gas distribution optimization design method of the gas flow distributor in this biogas-liquid reactor has the following advantages:

[0066] 1. This invention optimizes gas flow pressure drop within the pipeline and ensures the jet velocity exceeds the critical seepage threshold. Through systematic optimization of key structural parameters such as the number of jet tubes, pipe diameter, and number of jet orifices, it significantly improves the performance of the airflow distributor. Based on theoretical modeling and algorithm selection, this method efficiently determines the optimal combination of structural parameters during the design phase, greatly reducing the R&D costs and time required for traditional trial-and-error approaches. The airflow distributor optimized using this method achieves more uniform and stable gas distribution within the reactor, effectively reducing cell mortality and improving the efficiency and controllability of the cell culture process.

[0067] 2. This invention, through systematic optimization of key structural parameters such as the number of jet tubes, tube tip diameter, jet tube diameter, jet orifice diameter, and orifice spacing, significantly improves the uniformity of jet velocity along the tube length while minimizing system pressure drop and effectively suppresses seepage through the jet orifices. This method reveals the intrinsic regulatory laws governing the uniform distribution of gas jets through fluid dynamics and structural parameters, providing a theoretical basis for the optimized design and large-scale scaling of bioreactors, and contributing to improved uniformity and survival rate of cell culture within the reactor. Attached Figure Description

[0068] Figure 1 This is a flowchart of the design method for uniform jet distribution in the airflow distributor of the present invention;

[0069] Figure 2 This is a schematic diagram of the airflow distributor of the present invention;

[0070] Figure 3 This is a schematic diagram of the jet tube structure in the airflow distributor of the present invention;

[0071] Figure 4 This is a graph showing the relationship between the pressure loss ratio and the number of airflow distributors in a multi-airflow distributor system.

[0072] Figure 5 This is a graph showing the relationship between pressure loss and the number of airflow distributors in a multi-airflow distributor system.

[0073] Figure 6 This is a graph showing the relationship between the jet tube diameter and the number of airflow distributors;

[0074] Figure 7 This is a graph showing the relationship between the jet tube diameter and the total pressure drop;

[0075] Figure 8 It is the distribution of normalized jet velocity along the jet orifice number;

[0076] Figure 9 This is a schematic diagram of the reactor structure using the airflow distributor of the present invention;

[0077] Figure 10 This is a graph showing the relationship between the jet orifice flow coefficient and the Reynolds number and geometric parameters;

[0078] Figure 11 This is a graph showing the relationship between the momentum restitution coefficient and the Reynolds number and geometric parameters;

[0079] Figure 12 This is a graph showing the relationship between experimental and simulation results for the jet orifice flow coefficient.

[0080] Figure 13 This is a graph showing the relationship between the experimental and simulation results of the momentum restitution coefficient;

[0081] Figure 14 It is the distribution characteristics of the normalized jet velocity of the jet as a function of pipe length under different inlet velocities;

[0082] Figure 15 This is a distribution diagram of the non-uniformity of the jet velocity in the jet orifice as a function of the Reynolds number;

[0083] Figure 16 This is a comparison chart of experimental and simulation results of jet velocity nonuniformity in jet orifice;

[0084] Figure 17 This is a distribution diagram of the jet velocity as a function of the jet orifice number.

[0085] In the diagram, 1 is the reactor; 2 is the airflow distributor; 21 is the pipe end; 22 is the jet pipe; and 23 is the jet orifice. Detailed Implementation

[0086] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0087] Example 1:

[0088] like Figure 2 and Figure 3 As shown, each airflow distributor 2 consists of a jet pipe 22, multiple jet holes 23 distributed on the jet pipe 22, and a pipe end head 21. The design of this biogas-liquid reactor airflow distributor's uniform gas distribution optimization method aims to obtain the optimal uniform distribution of jet velocity under conditions of minimum pressure drop. Specific operating steps are as follows... Figure 1 As shown, the apparent gas velocity in the reactor is first set to 0.1 m / s. Then, the average gas content in the reactor is calculated using Formula 1, and the critical velocity for seepage through the jet orifice is estimated using Formula 2. Formula 1 is:

[0089] ,

[0090] In the formula, The average gas content, and The surface tensions (N / m) of water and hydrogen, respectively. and The values ​​are the dynamic viscosity (Pa.s) of water and hydrogen, respectively. and The densities of hydrogen and air are respectively (kg / m³). 3 ).

[0091] Formula 2 is:

[0092]

[0093] In the formula, The critical velocity (m / s) for seepage at the jet orifice. Given the jet orifice diameter (m), The ratio of the orifice spacing to the jet orifice diameter, where g is the acceleration due to gravity 9.8 ( ), Gas density ( ), The density of liquid water ( ), For liquid height, t is the distance between the two jet holes (m), and t is the thickness of the jet tube wall (m).

[0094] In this design, the diameter of the jet orifice ranges from 0.001 to 0.006 m, and the ratio of the orifice spacing to the orifice diameter ranges from 2 to 8, which facilitates the estimation of the critical velocity of the jet orifice seepage.

[0095] Calculated critical velocity of jet orifice seepage and the set apparent gas flow rate The required number of jet holes N is calculated using Formula 3, the total length L of all jet tubes is calculated using Formula 4, and the required number of jet tubes is calculated using Formula 5. Formula 3 is: ,

[0096] In the formula, This represents the total number of jet holes. Given the diameter of the jet orifice (m). The jet velocity (m / s) is the velocity of the jet stream through the jet orifice. The diameter of the reactor is (m). The apparent gas jet velocity in the reactor is (m / s).

[0097] Formula four is: ,

[0098] In the formula, L is the total length of all jet tubes. The distance between the two jet orifices (m);

[0099] Formula 5 is: ,

[0100] In the formula, For the number of jet tubes, The length of a single jet tube is 0.6m or 1.5m.

[0101] The required total number of jet tubes N, the total length of all jet tubes L, and the required number of jet tubes After calculation, the initial selection of the required total number of jet tubes N, the total length of all jet tubes L, and the required number of jet tubes is determined. The initial value is based on the diameter of the jet tube. and pipe end diameter For an airflow distributor with parametric variables, Scheme A: =0.1m, =0.025m; Scheme B: =0.165m, =0.038 m; Scheme C: =0.12m, =0.032 m; Scheme D: =0.12m, =0.025m.

[0102] Subsequently, based on the gas flow characteristic parameters and the initially selected combination of airflow distributor parameters, the frictional resistance coefficient f, momentum recovery coefficient k, and jet orifice flow coefficient c are determined. Specifically, the frictional resistance coefficient f is calculated using Formula 6, the momentum recovery coefficient k is calculated using Formula 7, and the jet orifice flow coefficient c is calculated using Formula 8. The parameter combination includes the jet tube diameter. Pipe end diameter Total length L of the jet tube, given diameter of the jet orifice and the ratio of the orifice spacing to the jet orifice diameter. The total number of jet tubes N, the total length of all jet tubes L, and the required number of jet tubes. ;

[0103] Formula six is:

[0104] ;

[0105] Formula 7 is:

[0106] ;

[0107] Formula 8 is:

[0108] ;

[0109] In the formula, For the local jet orifice Reynolds number, , This is the mass flow rate (kg / s) entering the jet tube, and this value is a given value; , The critical velocity for seepage at the jet orifice. The density of hydrogen gas, The cross-sectional area of ​​the jet orifice. The dynamic viscosity of hydrogen. The diameter of the jet tube. For Euler number, The Euler number is set in the range of 0.5 to 0.8. The gas velocity entering the jet tube, , The cross-sectional area of ​​the jet tube is... ; The pressure variation along the pipe length is calculated using Formula Nine. Given the inlet pressure of the jet pipe, Given the external reactor pressure of the gas flow distributor, FA is the effective area of ​​gas flow based on a single jet tube. , The side area of ​​the jet tube (m²) 2 N represents the total number of jet holes.

[0110] The pressure distribution along the length of the jet tube is calculated using Formula 9, which is:

[0111] ,

[0112] In the formula, For the pressure distribution along the length of the jet tube, The inlet pressure at the jet orifice (Pa). The mass flow rate (kg / s) entering the jet tube. The mass flow rate (kg / s) through the jet orifice. The density of hydrogen gas, Let be the distance (m) from the head of the pipe end, and q, s, and r be intermediate variables. , , , The value is the gas dynamic viscosity (Pa·s).

[0113] Then, the ratio of the frictional pressure drop inside the jet tube to the pressure drop through the jet orifice was calculated using Formula 11, and plotted as follows: Figure 4 The diagram shows the relationship between the pressure loss ratio within a multi-airflow distributor and the number of airflow distributors; Formula eleven is:

[0114] ,

[0115] The total pressure loss of the airflow distributor is calculated using Formula Twelve, and the result is plotted as follows: Figure 5 The diagram shows the relationship between pressure loss and the number of airflow distributors; Formula 12 is:

[0116] ,

[0117] In the formula, This indicates the total pressure loss (kPa) flowing through the head of the pipe and the jet pipe. The frictional resistance pressure drop (Pa) along the length of the jet tube. The pressure drop (Pa) through the jet orifice. , Let i be the pressure value of the i-th jet orifice. The velocity of the gas flow inside the pipe. U is the dimensionless jet velocity.

[0118] The momentum balance equation for gas flow along the pipe length due to jet discharge from the jet orifice includes factors such as pressure drop due to frictional pressure loss and pressure increase due to continuous momentum reduction. The dimensionless jet velocity U is calculated using Equation Fourteen, which is:

[0119] ,

[0120] , , ,

[0121] In the formula, The symbol is a differential, and U is the dimensionless jet velocity. This represents the ratio of the jet hole area to the internal surface area of ​​the pipe. The velocity of the gas entering the jet tube (m / s). This is the distance (m) from the head of the pipe. The diameter of the jet tube is (m).

[0122] Given a pressure drop ratio criterion for characterizing jet velocity uniformity, the ratio of the frictional pressure drop inside the jet tube to the pressure drop through the jet orifice is set to be less than or equal to 0.1 to ensure a jet uniformity of 95%. Based on this pressure drop ratio criterion, from... Figure 4 The diagram shows that only schemes A and B meet the requirements, as they cover and satisfy the requirements for the total number of branch jet tubes. Specifically, within the range of the minimum and maximum number of branch tubes, the pressure drop ratio is less than 0.1. From... Figure 5 The diagram shows that the minimum pressure drop losses of schemes A and B are very low and similar. Based on the principles of minimum fixed cost and minimum pressure drop, and according to Formula Nine, the pressure drop range of the airflow distributor fluctuates within 600 Pa. Therefore, scheme A is more reasonable, and the pipe end diameter is determined accordingly. and jet tube diameter The value is: =0.1m, =0.025m.

[0123] Based on the determined pipe end diameter and jet tube diameter The critical jet orifice diameter is calculated using Formula Thirteen based on the combination of airflow distributor parameters. Ensure the selected jet orifice diameter Not greater than the critical jet orifice diameter This avoids seepage during crying from a structural design perspective; Formula thirteen is:

[0124] ,

[0125] In the formula, N represents the total number of jet holes. Let L be the diameter of the jet tube (m) and L be the total length of all jet tubes.

[0126] The jet velocity of each jet orifice is calculated using Formula 10.

[0127]

[0128] In the formula, This represents the jet velocity of jet orifice i, where i is the orifice number. Given the external reactor pressure (Pa) of the gas flow distributor. and These are the pressure values ​​(Pa) of the i-th jet orifice and the pressure value (Pa) of the previous orifice number i+1, respectively. and Calculated according to Formula 9, c represents the jet orifice flow coefficient. The jet velocity (m / s) is represented by jet orifice i.

[0129] The non-uniformity distribution of the jet velocity in a multi-jet nozzle is calculated using Formula 15, which is: ,

[0130] In the formula, For the non-uniform distribution of jet velocity in multi-jet orifices, The jet velocity (m / s) is the last jet numbered N along the pipe length. The jet velocity (m / s) of the first jet hole number 1 distributed along the length of the straight pipe jet hole.

[0131] Based on preset seepage prevention conditions and non-uniformity requirements, when the preset conditions are met simultaneously, i.e. , Set to 15%, and When determining that parameters such as the number of jet tubes, jet orifice diameter, jet orifice spacing, and tube end diameter meet the requirements, the final airflow distributor design parameters are output.

[0132] For all schemes, the hole spacing ratio In solving for the pressure drop and the number of branch straight pipes, keep them constant. The solution for the end pipe head diameter and jet pipe diameter is similar to the steps described above. Figure 6 It can be seen that the minimum pressure drop corresponds to the jet orifice diameter. =0.005m and the ratio of hole spacing The corresponding number of branch straight pipes is 18. However, the pressure inside the reactor is 1.0 MPa, and due to geometric space design limitations, this number of airflow distributors cannot be arranged. Therefore, the preferred compromise is a jet pipe number of 10, i.e., a gas flow distributor number of 10, a jet orifice diameter of 0.004 m, and an orifice spacing ratio of [missing value]. At this point, the corresponding maximum total pressure drop is approximately 3900 Pa (see...). Figure 7 ).

[0133] Based on the pressure drop calculation results and the selection of jet orifice parameters, the distribution diagram of jet orifice velocity along with jet orifice number is as follows: Figure 8 As shown in the figure, the normalized jet orifice velocity on the vertical axis is defined as the flow velocity of each jet orifice divided by the velocity value of the first orifice of the first airflow distributor. The figure shows that the maximum velocity value is at the farthest jet orifice in the jet tube, and the minimum value is at the jet orifice near the inlet. The average non-uniformity of the jet velocity is 11.5%, less than the specified 15%. The optimized design parameters have achieved the target, and the final airflow distributor design parameters are output.

[0134] The optimized airflow distributor has a total of 300 jet holes, requiring 10 jet tubes with a diameter of 0.025 m and a jet hole diameter of 0.004 m. The hole spacing ratio is [missing value]. The main design parameters are shown in Table 1.

[0135] Table 1 Main Design Parameters of Airflow Distributor

[0136]

[0137] Example 2:

[0138] The technical solution in this embodiment is basically the same as that in Embodiment 1. The difference is that, in order to further verify the accuracy of the theoretical values ​​of the main design parameters of the airflow distributor 2, the airflow distributor 2, which was optimized and designed in Embodiment 1, was placed in the reactor 1 for experimentation. Figure 9 As shown, the experimental equipment mainly includes a reactor 1, several gas flow distributors 2 located within the reactor 1, a data acquisition system for measuring gas flow pressure, and a mass flow controller for controlling the gas flow rate in the input jet pipes 22. The external gas source is hydrogen or any other gas type suitable for the reactor 1. In this embodiment, the liquid phase in the biogas-liquid reactor 1 uses room temperature tap water, and compressed hydrogen is used as the bubble gas source. The operating pressure is 1.0 MPa, the operating temperature is room temperature (20°C), and the apparent gas velocity in the reactor is set to 0.1 m / s. The biogas-liquid reactor 1 has a height of 6000 mm and a diameter of 1600 mm, and is made of polyvinyl chloride. All jet pipes 22 are made of 304 stainless steel. The gas jet is achieved by compressed air flowing through the radial multi-flow distributors 2, forming an inlet jet on their surface through jet holes 23, providing the air source driving force for bubble generation and movement. Bubbles are generated from the outlet of the multi-jet pipes 22 at the multi-jet holes 23, and gradually develop, detach, and are transported into the liquid phase environment.

[0139] The experimental measurement system for measuring the jet velocity in a radial multi-straight-tube multi-jet-hole system mainly consists of: an independently developed LabVIEW-integrated data acquisition system and a Seven Star CS230A mass flow controller with a range of 150 L / min. The gas pressure distributed along the pipe length is measured using a hydrostatic pressure gauge, model Yuanhengtong QX1208, with a range of ±89.6 kPa.

[0140] Ten airflow distributors 2 were placed inside reactor 1 for testing. The set volumetric flow rate was introduced, and the pressure at each jet orifice 23 was measured.

[0141] Based on the measured pressure at each of the 23 jet orifices, the experimental jet velocity at each of the 23 jet orifices was calculated using Formula 19, and the experimental non-uniformity distribution of the jet velocity across the multiple jet orifices was calculated using Formula 15. It was determined that the experimental jet velocity and experimental non-uniformity distribution at each jet orifice also met the preset seepage prevention conditions and non-uniformity requirements. Verification by experimental measurement data showed good agreement. Further verification confirmed that the theoretical parameters determined in Example 1, such as the number of jet tubes, jet orifice diameter, jet orifice spacing, and tube end diameter, were the preferred options. All experimental measurements were repeated multiple times, such as 5 times, and the average value was taken as the experimental value.

[0142] Furthermore, for the bubbling bioreactor 1 with a relatively low height-to-diameter ratio, the performance parameters of reactor 1 mainly depend on the optimized design of the geometry of the airflow distributor 2 and the parameters of the jet orifices 23. This step involves experimentally measuring the flow characteristics of the airflow distributor 2 and solving and simulating the problem using the constructed optimization algorithm. It quantitatively analyzes and clarifies the intrinsic relationship between the airflow characteristics within the pipe and the design parameters and operating conditions of the jet orifices 23, revealing their influence and variation patterns on the non-uniform distribution of jet velocities in each jet orifice. Simultaneously, experimental results are used to verify the optimization model, laying an important foundation for the scale-up and optimization strategies of reactor 1.

[0143] Four different airflow distributors 2 with varying structural types and parameters were selected as the research objects. The diameter of the jet orifices ranged from 0.002 to 0.006 m, the ratio of the distance between jet orifices to the diameter of the jet orifices ranged from 2 to 8, the lengths of the airflow distributors were 0.6 m and 1.5 m, and the gas velocity entering the jet tube 22 ranged from 13 to 39 m / s. Specific parameters are shown in Figure 2.

[0144] Table 2 Main Design Parameters of Four Types of Airflow Distributors

[0145]

[0146] like Figure 7 As shown, the effects of Reynolds number and the geometric parameters of the airflow distributor 2 on the jet orifice flow coefficient and momentum recovery coefficient are presented. Figure 10As can be seen, for the short-tube airflow distributors S1 and S2 with a length of 0.6 m, the flow coefficient gradually increases with the increase of the Reynolds number, while for the long-tube airflow distributors S3 and S4 with a length of 1.5 m, the flow coefficient remains basically unchanged with the increase of the Reynolds number. This shows that the flow coefficients of the short-tube airflow distributors S1 and S2 are highly dependent on the change of the Reynolds number, while the dependence of the long-tube airflow distributors S3 and S4 is very weak. Figure 11 As can be seen, the momentum recovery coefficients of all four types of airflow distributors 2 increase with the increase of Reynolds number. Figure 12 and 13 The graph shows the consistency between experimental and simulation results for the jet orifice flow coefficient and momentum recovery coefficient. The calculated results from the empirical formulas agree well with the experimental results, with correlation coefficients around 0.96.

[0147] Due to the pressure recovery phenomenon at the jet orifice 23, the jet velocity at the jet orifice 23 also increases gradually from the side near the air inlet to the far side. To compare the jet velocities of each jet orifice 23, a normalized value is used for comparison, i.e., the velocity is normalized by dividing by the velocity value of the first jet orifice. Figure 14 The figure shows the normalized jet velocity distribution of different types of airflow distributors. The normalization result can well describe the non-uniformity of the jet velocity distribution. As can be seen in the figure, increasing the jet orifice diameter will increase the non-uniformity distribution. This is because at the far-end jet orifice 23, the effects of flow rate and kinetic energy recovery are greater than frictional resistance; therefore, the jet flow rate and velocity at these orifices are higher than those at the near-end jet orifice 23. In the near-end jet orifice 23 region, the effects of friction and momentum recovery will have opposite effects, resulting in a pressure flow decrease followed by a pressure rise trend. A reasonable dynamic balance between these two effects will reduce the non-uniformity of the jet velocity distribution.

[0148] With a fixed orifice spacing ratio, increasing the orifice diameter induces frictional resistance far less than the effect of momentum change, leading to a worsening of non-uniformity. Furthermore, increasing the pipe length also increases the non-uniformity distribution. For a fixed orifice diameter, increasing the orifice spacing leads to frictional resistance between two consecutive orifices, which will reduce the non-uniformity of the jet velocity distribution.

[0149] like Figure 15 As shown, the nonuniformity of the jet velocity varies with the Reynolds number. The maximum value occurs when the diameter of the jet orifice 23 in the long tube S3 is 2.0 mm and the orifice spacing is 8.0 mm, while the minimum value occurs when the diameter of the jet orifice 23 in the short tube S2 is 3.0 mm and the orifice spacing is 8.0 mm. With the increase of the Reynolds number, the nonuniformity generally shows a slightly decreasing trend. Figure 16The graph shows the consistency between experimental and simulation results of jet velocity nonuniformity. The calculated results from the empirical formula agree well with the experimental results, with correlation coefficients around 0.98. Figure 17 This represents the distribution of jet velocity with respect to orifice number under two different inlet velocity conditions. Therefore, properly controlling the orifice diameter and orifice spacing is key to achieving a uniform jet velocity distribution. Keeping the jet velocity and its uniformity at a low level is an important optimization direction for reducing fluid shear stress-induced cell damage and improving culture efficiency.

[0150] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for optimizing the uniform gas distribution of a gas flow distributor in a biogas-liquid reactor, wherein the gas flow distributor comprises a jet pipe, jet holes on the jet pipe, and a pipe end head, characterized in that... The method for optimizing the uniform gas distribution of the gas flow distributor in this biogas-liquid reactor includes the following steps: S1. Based on the given range of jet orifice diameter, the range of the ratio of orifice spacing to jet orifice diameter, gas-liquid physical properties, and liquid phase height in the reactor, estimate the critical velocity for jet orifice seepage to ensure that seepage does not occur. S2. Based on the critical velocity of seepage in the jet orifice and the set apparent gas flow velocity, calculate and initially select the required total number of jet orifices, the total length of all jet tubes, and the required number of jet tubes; and initially select the airflow distributor with the jet tube diameter and the tube end diameter as parameter variables. S3. Based on the gas flow characteristic parameters and the initially selected combination of airflow distributor parameters, determine the frictional resistance coefficient f, momentum recovery coefficient k, and jet orifice flow coefficient c. S4. Based on the given pressure value of the jet pipe and the mass flow rate of the jet pipe, calculate the pressure distribution along the length of the jet pipe, and analyze the pressure drop distribution characteristics along the length of the pipe and the analysis results of the total pressure loss in the pipe. S5. Given the pressure drop ratio criterion for characterizing jet velocity uniformity, determine the airflow distributor parameter combination that satisfies the pressure drop ratio criterion based on the pressure drop ratio criterion and the analysis results in step S4. S6. Based on the airflow distributor parameter combination determined in step S5, calculate the jet velocity of each jet hole and the non-uniformity distribution of the jet velocity of multiple jet holes. When the jet velocity of the jet holes and the non-uniformity distribution simultaneously meet the preset seepage prevention conditions and non-uniformity requirements, output the final airflow distributor design parameters; otherwise, return to step S2, re-select the required number of all jet holes, the total length of all jet pipes, and the required number of jet pipes, and initially select the airflow distributor with the jet pipe diameter and the pipe end diameter as parameter variables.

2. The method for optimizing uniform gas distribution in a biogas-liquid reactor gas distributor according to claim 1, characterized in that, In step S1, the critical velocity for seepage in the jet orifice is estimated using the following formula two: In the formula, The critical velocity for seepage at the jet orifice. Given the diameter of the jet orifice, and g as the acceleration due to gravity, For gas density, The density of liquid water, For liquid height, t is the distance between the two jet holes, and t is the thickness of the jet tube wall.

3. The method for optimizing uniform gas distribution in a biogas-liquid reactor gas distributor according to claim 2, characterized in that, In step S2, the total number of jet holes is calculated using Formula 3, the total length of all jet tubes is calculated using Formula 4, and the number of jet tubes is calculated using Formula 5. Formula 3 is as follows: , In the formula, This represents the total number of jet holes. Given the jet orifice diameter, The critical velocity for seepage at the jet orifice. Where is the reactor diameter, The apparent gas jet velocity in the reactor; Formula four is as follows: , In the formula, L is the total length of all jet tubes. The distance between the two jet orifices; Formula five is: , In the formula, The number of jet tubes, This refers to the length of a single jet tube.

4. The method for optimizing uniform gas distribution in a biogas-liquid reactor gas distributor according to claim 3, characterized in that, In step S3, the frictional resistance coefficient f is obtained by formula six, the momentum recovery coefficient k is obtained by formula seven, and the jet orifice flow rate coefficient c is obtained by formula eight. Formula six is: ； Formula seven is: ； Formula 8 is as follows: ； In the formula, For the local jet orifice Reynolds number, , The mass flow rate entering the jet tube, The mass flow rate through the jet orifice. , The critical velocity for seepage at the jet orifice. The density of hydrogen gas, The cross-sectional area of ​​the jet orifice. The dynamic viscosity of hydrogen. The diameter of the jet tube. Here, is the Euler number, and FA is the effective area of ​​gas flow based on a single jet tube. , Where is the side area of ​​the jet tube, and N is the total number of jet holes.

5. The method for optimizing uniform gas distribution in a biogas-liquid reactor gas distributor according to claim 1, characterized in that, In step S4, the pressure distribution along the length of the jet pipe is calculated using Formula Nine, which is: ， In the formula, For the pressure distribution along the length of the jet tube, This refers to the inlet pressure at the jet orifice. The mass flow rate entering the jet tube, The mass flow rate through the jet orifice. The density of hydrogen gas, Let be the distance from the head of the pipe end, and q, s, and r be intermediate variables. , , , This represents the gas dynamic viscosity.

6. The method for optimizing uniform gas distribution in a biogas-liquid reactor gas distributor according to claim 5, characterized in that, In step S4, the analysis results of obtaining the pressure drop distribution characteristics along the pipe length and the total pressure loss inside the pipe include: The ratio of frictional pressure drop inside the jet tube to pressure drop through the jet orifice is calculated using Formula 11, and the total pressure loss of the airflow distributor is calculated using Formula 12. The analysis results are obtained by analyzing the ratio of the calculated frictional pressure drop inside the jet tube to the pressure drop through the jet orifice and the total pressure loss of the airflow distributor. Formula eleven is as follows: , Formula 12 is: , In the formula, The frictional resistance pressure drop along the length of the jet tube, For the pressure drop through each jet orifice, The density of hydrogen gas, The gas velocity entering the jet tube, The diameter of the jet tube. The velocity of the gas flow inside the pipe. U is the dimensionless jet velocity.

7. The method for optimizing uniform gas distribution in a biogas-liquid reactor gas distributor according to claim 6, characterized in that, The dimensionless jet velocity U is calculated using Formula Fourteen, which is: ， In the formula, The differential symbol, , , This represents the ratio of the jet hole area to the internal surface area of ​​the pipe. , The diameter of the jet tube. Given the jet orifice diameter, f is the frictional resistance coefficient, k is the momentum recovery coefficient, and c is the jet orifice flow rate coefficient.

8. The method for optimizing uniform gas distribution in a biogas-liquid reactor gas distributor according to claim 4, characterized in that, In step S6, the critical jet orifice diameter is calculated using Formula Thirteen. Formula thirteen is: , In the formula, Where is the critical jet orifice diameter, and N is the total number of jet orifices. Where is the diameter of the jet tube, and L is the total length of all jet tubes.

9. The method for optimizing uniform gas distribution in a biogas-liquid reactor gas flow distributor according to any one of claims 1 to 8, characterized in that, In step S6, the preset seepage prevention conditions are: When the jet velocity in the jet orifice is greater than 25% of the critical velocity for seepage prevention in the jet orifice, the jet velocity in the jet orifice is deemed to meet the preset seepage prevention condition. The preset non-uniformity requirement is: When the non-uniformity of the jet velocity distribution in the multi-jet orifice is less than 15%, the non-uniformity is deemed to meet the preset uniformity requirement.

10. The method for optimizing uniform gas distribution in a biogas-liquid reactor gas flow distributor according to any one of claims 5 to 7, characterized in that, In step S6, the jet velocity of each jet orifice is calculated using Formula 10, which is: In the formula, This represents the jet velocity of jet orifice i, where i is the orifice number. Given the external reactor pressure of the gas flow distributor, and These are the pressure values ​​of the i-th jet orifice and the pressure value of the previous orifice number i+1, respectively. and According to Formula 9, c represents the jet orifice flow coefficient; The degree of non-uniformity distribution of the jet velocity in a multi-jet orifice is calculated using Formula Fifteen, which is: ， In the formula, For the non-uniform distribution of jet velocity in multi-jet orifices, The jet velocity is represented by the last hole numbered N in the straight pipe jet orifice distribution along the pipe length. The jet velocity is the first jet hole number 1 distributed along the length of the straight pipe jet hole.

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