Method for optimizing linear jet velocity uniform distribution of multi-jet orifice straight pipe gas distributor

Abstract

The application discloses a method for optimizing linear jet velocity uniform distribution of a multi-jet orifice straight pipe gas distributor, an auxiliary pipe is arranged in a main pipe, and the following optimization design variables are used: an axial interval of adjacent jet orifices of the auxiliary pipe, a jet orifice diameter of the auxiliary pipe, a jet orifice number of the auxiliary pipe, a main pipe inclination angle, an interval between a main pipe inlet end and an auxiliary pipe inlet end, and a center distance between the main pipe and the auxiliary pipe; under the constraint that an error between a main pipe inlet mass flow and a total sum of mass flows of all jet orifices is less than an error threshold, linear jet velocities at all jet orifices in the main pipe are corrected, so that the coming flow gas is subjected to pressure redistribution at all jet orifices in the main pipe, and the structure optimization design of the straight pipe gas distributor with uniform linear jet velocity distribution at all jet orifices is realized. The linear jet velocity distribution uniformity of the multi-jet orifice straight pipe gas distributor optimized by the application is significantly improved, and cell culture damage and death or leakage phenomena in a bioreactor can be reduced or basically eliminated.

Description

Technical Field

[0001] This invention belongs to the technical field of gas-liquid multiphase turbulent flow dynamics characteristics in bioreactors, specifically relating to a method for optimizing the uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor in a bioreactor. Background Technology

[0002] Gas jetting in a gas-liquid bioreactor is a heat and mass transfer process that involves introducing gas in the form of bubbles into a liquid medium. This is achieved through a gas distributor with multiple jet orifices. As the gas exits from the jet orifices, bubbles form, which then undergo upward transport and diffusion within the liquid medium submerged in the pipes. In bubbling bioreactors for animal cell immersion culture, the gas jetting and transport process via the gas distributor can be used to maintain suitable liquid phase concentrations of dissolved oxygen, carbon dioxide, and other gases required for cell or microbial growth.

[0003] High linear jet velocities at the jet orifices of a gas distributor can cause significant cell damage, even death and apoptosis. Reducing the linear jet velocity at the jet orifices can effectively prevent cell damage and death. However, reducing the gas velocity can lead to a condition called "leakage," where some jet orifice openings discharge gas at extremely low linear velocities (or in some cases, zero linear velocity), inevitably reducing the overall efficiency of gas delivery to the liquid medium. Furthermore, leakage can cause cells to grow and accumulate at or near the outlet of the gas delivery device. This can clog the outlet and increase the linear jet velocity, leading to unnecessary downtime for maintenance (e.g., cleaning of the gas delivery device). This interaction between cell accumulation and leakage creates a vicious cycle: outlet blockage leads to increased local velocity, which in turn exacerbates the risk of cell damage. Therefore, a method is needed to design a system that allows each jet orifice of a multi-jet gas distributor to deliver gas uniformly at a relatively constant linear velocity, thereby reducing cell damage, death, and leakage. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes an optimization method for uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor based on fluid dynamics theory and optimization of airflow distributor structure design, thereby achieving the goal of uniform distribution of linear jet velocity at the multi-jet holes of the straight pipe gas distributor.

[0005] The present invention discloses an optimization method for uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor. An auxiliary pipe is placed within the main pipe, and the following design variables are optimized: axial spacing between adjacent jet holes in the auxiliary pipe, diameter of the jet holes in the auxiliary pipe, number of jet holes in the auxiliary pipe, inclination angle of the main pipe, distance between the inlet ends of the main pipe and the auxiliary pipes, and center distance between the main pipe and the auxiliary pipes. Under the constraint that the error between the mass flow rate at the main pipe inlet and the sum of the mass flow rates of all jet holes is less than an error threshold, the linear jet velocity at each jet hole in the main pipe is corrected.

[0006] Preferably, the specific process for optimizing design variables is as follows:

[0007] ① Initialize the linear jet velocity of each jet orifice in the main pipeline.

[0008] ② Calculate the sum of the mass flow rates of all jet orifices in the main pipeline and the error between this sum and the mass flow rate at the inlet of the main pipeline. .

[0009] ③Judgment Check if the value is less than the error threshold. If it is, obtain the values ​​of each design variable; otherwise, adjust the values ​​of the design variables and proceed to step ④.

[0010] ④ The desired pressure at the i-th jet orifice of the main pipeline after the auxiliary pipeline redistributes pressure to the main pipeline, taking into account frictional resistance loss along the pipeline and jet orifice pressure drop, is expected to be achieved. , If the inlet gas pressure of the main pipeline is the corrected linear jet velocity of the i-th jet orifice in the main pipeline:

[0011]

[0012] Where c is the momentum recovery coefficient of the jet orifice. For gas density, The pressure at the i-th jet orifice of the main pipeline that is desired to be achieved when only frictional resistance loss along the pipeline is considered after the auxiliary pipeline redistributes the pressure to the main pipeline.

[0013] ⑤ Return to step ② and continue until the judgment in step ③ is reached. If the error threshold is less than 1, the final combination of each design variable is obtained.

[0014] Preferably, the auxiliary pipe is parallel to the main pipe, and the length and inner diameter of the auxiliary pipe are not adjusted after being given.

[0015] More preferably, step ① is as follows: Given the volumetric flow rate of compressed air flowing through the inlet of the main pipeline. Initialize the jet velocity of the i-th jet orifice in the main pipe:

[0016] .

[0017] Among them, A i is the cross-sectional area of ​​the i-th jet orifice in the main pipe, and n is the total number of jet orifices in the main pipe.

[0018] More preferably, step ② is as follows: Calculate the total mass flow rate m of all jet orifices in the main pipeline:

[0019]

[0020] in, The mass flow rate of the i-th jet orifice in the main pipeline. .

[0021] Calculate the mass flow rate at the inlet of the main pipeline Error relative to the sum of mass flow rates m from all jet orifices:

[0022] .

[0023] More preferably, the pressure at each jet orifice of the main pipeline that is expected to be achieved after the auxiliary pipeline redistributes the pressure to the main pipeline, considering only the frictional resistance loss along the pipeline, is calculated as follows:

[0024] Calculate the inlet gas flow velocity of the main pipeline and auxiliary pipeline:

[0025]

[0026] in, The gas flow velocity at the main pipeline inlet. To assist the gas flow velocity at the pipeline inlet, Main pipe inner diameter, To assist in determining the inner diameter of the pipe and the volumetric flow rate at the pipe inlet. .

[0027] Calculate the gas pressure p at the main pipe inlet using Bernoulli's energy conservation equation. S .

[0028] The frictional resistance coefficient of gas flowing in the main pipe is calculated using the Colbrook equation. The coefficient of frictional resistance of gas flowing in the auxiliary pipe .

[0029] The Darcy-Weisbach formula is used to calculate the pressure difference caused by frictional resistance between adjacent jets in the main pipeline. Pressure difference due to frictional resistance loss between adjacent jet orifices in the auxiliary pipeline and the auxiliary pipeline. :

[0030]

[0031] in, The axial spacing between adjacent jet holes in the main pipe. This is to assist in determining the axial spacing between adjacent jet holes in the pipeline.

[0032] Construct a pressure coupling equation that considers only frictional resistance losses along the pipeline after the pressure redistribution from the auxiliary pipeline to the main pipeline:

[0033]

[0034] in, To determine the desired pressure at the (i+1)th jet orifice in the main pipeline after the auxiliary pipeline redistributes pressure to the main pipeline, considering only frictional resistance losses along the pipeline, .

[0035] More preferably, the Bernoulli energy conservation equation is expressed as follows:

[0036]

[0037] in, It is a constant.

[0038] More preferably, the frictional resistance coefficient and The solution is as follows:

[0039]

[0040] in, The surface roughness of the main pipeline, To assist in the surface roughness of the pipeline;

[0041] Reynolds number of gas flowing in the main pipeline The Reynolds number of the gas flowing in the auxiliary pipe. The calculation is as follows:

[0042]

[0043] in, This represents the gas dynamic viscosity.

[0044] The present invention has the following beneficial effects:

[0045] This invention focuses on the linear jet velocity at the jet orifices of a straight-tube gas distributor in a gas-liquid bioreactor. With the objective of ensuring the error between the mass flow rate at the main pipe inlet and the sum of the mass flow rates at all jet orifices is less than an error threshold, and based on the incompressible Bernoulli energy conservation equation, the Körbruck equation, and the Darcy-Weisbach formula, a method for optimizing the uniform distribution of linear jet velocity in a multi-jet-orifice straight-tube gas distributor is proposed. This method corrects the linear jet velocity at the numerous jet orifices in the main pipe and obtains the axial spacing between adjacent jet orifices in the auxiliary pipe, the orifice diameter of the auxiliary pipe, the number of jet orifices in the auxiliary pipe, the inclination angle of the main pipe, the distance between the inlet ends of the main pipe and the auxiliary pipe, and the final combination of the center distance between the main pipe and the auxiliary pipe. This allows for pressure redistribution of the incoming gas at each jet orifice in the main pipe, achieving a structurally optimized design for a straight-tube gas distributor with uniform linear jet velocity distribution at each jet orifice. The linear jet velocity distribution uniformity of the multi-jet straight pipe gas distributor optimized by the method of this invention is significantly improved, which helps to reduce or essentially eliminate cell culture damage and death or leakage in bioreactors and has significant commercial value. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the data measurement system in this invention.

[0047] Figure 2 This is a schematic diagram of placing an auxiliary pipe in the main pipe in this invention.

[0048] Figure 3 This is a comparison diagram of the linear jet velocities of each jet orifice before and after placing the auxiliary pipe in the main pipe according to the present invention. Detailed Implementation

[0049] The present invention will now be further described with reference to the accompanying drawings.

[0050] like Figure 1 As shown, the method for optimizing the uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor of the present invention includes the following steps:

[0051] Step 1: In this embodiment, the dimensions of the bubbling bioreactor are 1200 mm in height, 600 mm in length, and 25.4 mm in width. The material is polyvinyl chloride (PVC). The main pipe of the straight gas distributor in the bubbling bioreactor is 420 mm long and has an inner diameter of 6.4 mm. Three jet hole groups are arranged at 5 mm intervals along the circumference. Each jet hole group consists of 17 jet holes arranged at 3 mm intervals along the axial direction. Figure 2As shown, the jet orifice diameter is 1.8 mm, the spacing between adjacent jet orifices is 5 mm, the liquid phase in the bubbling bioreactor uses room temperature tap water, and the external gas source is compressed air (compressed oxygen or other compressed gases can also be used). This invention places a pressure redistribution auxiliary pipe in the main pipeline. The auxiliary pipe is 300 mm long and has an inner diameter of 2.4 mm. Both the main and auxiliary pipelines are made of stainless steel. Compressed air flows through a gas mass flow controller and a straight-pipe gas distributor, forming jets at the jet orifices in the main and auxiliary pipelines. This provides the air source for bubble generation and movement. Bubbles are generated from the jet orifices in the main and auxiliary pipelines, gradually detach, rise, collide, and coalesce, and are transported into the liquid phase environment.

[0052] Step 2: Optimize the axial spacing between adjacent jet holes in the auxiliary pipe, the diameter of the jet holes in the auxiliary pipe, the number of jet holes in the auxiliary pipe, the inclination angle of the main pipe, the distance between the inlet end of the main pipe and the inlet end of the auxiliary pipe, and the center distance between the main pipe and the auxiliary pipe. Under the constraint that the error between the mass flow rate at the inlet of the main pipe and the sum of the mass flow rates of all jet holes is less than the error threshold, the linear jet velocity at each jet hole in the main pipe is corrected. The specific process is as follows:

[0053] ①Given the volumetric flow rate of compressed air flowing through the inlet of the main pipeline. In this embodiment, the velocity is set to 0.15 L / min. The initial linear jet velocity of the gas flowing through the i-th jet orifice of the main pipe and into the external liquid environment is:

[0054] (1)

[0055] Among them, A i is the cross-sectional area of ​​the i-th jet orifice in the main pipe, and n is the total number of jet orifices in the main pipe.

[0056] ② Calculate the total mass flow rate (m) of all jet orifices in the main pipeline:

[0057]

[0058] in, The mass flow rate of the i-th jet orifice in the main pipeline. .

[0059] Calculate the mass flow rate at the inlet of the main pipeline Error relative to the sum of mass flow rates m from all jet orifices:

[0060]

[0061] ③Judgment Whether it holds true or not, in this embodiment, an error threshold is used. If true, then the axial spacing between adjacent jet holes in the auxiliary pipe is obtained. The final combination of the following parameters is required: the diameter of the jet orifice in the auxiliary pipe, the number of jet orifices in the auxiliary pipe, the inclination angle of the main pipe, the distance between the inlet ends of the main pipe and the auxiliary pipe, and the center distance between the main pipe and the auxiliary pipe (wherein, the auxiliary pipe is parallel to the main pipe, and its length and inner diameter are given and not adjusted). Otherwise, adjust the axial spacing between adjacent jet orifices in the auxiliary pipe. The parameters for the auxiliary pipe's jet orifice diameter, number of auxiliary pipe jet orifices, main pipe inclination angle, distance between the main pipe inlet and auxiliary pipe inlet, and center distance between the main pipe and auxiliary pipe (optimization algorithms, such as gradient optimization algorithm, ant colony algorithm, etc., can be used) are determined, and step ④ is executed.

[0062] ④ Calculate the inlet gas flow velocity of the main pipeline and auxiliary pipeline:

[0063] (2)

[0064] in, The gas flow velocity at the main pipeline inlet. To assist the gas flow velocity at the pipeline inlet, Main pipe inner diameter, To assist in determining the inner diameter of the pipe and the volumetric flow rate at the pipe inlet. .

[0065] Calculate the inlet gas pressure of the main pipe using Bernoulli's energy conservation equation. Bernoulli's energy conservation equation is expressed as follows:

[0066] (3)

[0067] in, It is a constant, determined based on experimental fitting. This represents the gas density.

[0068] The frictional resistance coefficient of gas flow in the main pipe is determined using the Colebrook equation. The coefficient of frictional resistance of gas flowing in the auxiliary pipe :

[0069] (4)

[0070] in, The surface roughness of the main pipeline, To assist in the surface roughness of the pipeline;

[0071] Reynolds number of gas flowing in the main pipeline The Reynolds number of the gas flowing in the auxiliary pipe. The calculation is as follows:

[0072]

[0073] in, The axial spacing between adjacent jet holes in the main pipe. To assist in the axial spacing of adjacent jet holes in the pipeline, This represents the gas dynamic viscosity.

[0074] The Darcy-Weisbach formula is used to calculate the pressure difference caused by frictional resistance between adjacent jets in the main pipe. Pressure difference due to frictional resistance loss between adjacent jet orifices in the auxiliary pipeline and the auxiliary pipeline. :

[0075] (5)

[0076] Construct a pressure coupling equation that considers only frictional resistance losses along the pipeline after the pressure redistribution from the auxiliary pipeline to the main pipeline:

[0077] (6)

[0078] in, To determine the desired pressure at the i-th jet orifice in the main pipeline after the auxiliary pipeline redistributes pressure to the main pipeline, considering only frictional resistance losses along the pipeline, To determine the desired pressure at the (i+1)th jet orifice in the main pipeline after the auxiliary pipeline redistributes pressure to the main pipeline, considering only frictional resistance losses along the pipeline, .

[0079] The pressure at the i-th jet orifice of the main pipeline after the pressure redistribution from the auxiliary pipeline to the main pipeline, taking into account both frictional resistance loss along the pipeline and pressure drop at the jet orifice (momentum recovery after passing through the jet orifice):

[0080] (7)

[0081] Where c is the jet orifice momentum recovery coefficient, which is determined based on experimental fitting.

[0082] Hope to achieve Then, the linear jet velocity of the i-th jet orifice in the main pipe is corrected as follows:

[0083] (8)

[0084] ⑤ Return to step ② and continue until the judgment in step ③ is reached. The axial spacing between adjacent jet holes in the auxiliary pipe is obtained. The final combination of the auxiliary pipe's jet orifice diameter, number of auxiliary pipe jet orifices, main pipe inclination angle, distance between the main pipe inlet and auxiliary pipe inlet, and center distance between the main and auxiliary pipes. In this embodiment, the optimized axial spacing of adjacent jet orifices in the auxiliary pipe is 10mm, the orifice diameter is 2.7mm, the number is 5, the main pipe inclination angle is 0° (for simplicity, this embodiment directly fixes the main pipe inclination angle at 0° in actual operation), the distance between the main pipe inlet and auxiliary pipe inlet is 60mm, and the center distance between the main and auxiliary pipes is 2mm.

[0085] The following describes the construction of a non-contact data measurement system for measuring the linear jet velocity of each jet orifice in the main pipeline. The system compares the linear jet velocities of each jet orifice before and after placing the auxiliary pipeline in the main pipeline, and verifies the effectiveness of the linear jet velocity correction model for the main pipeline jet orifices of this invention.

[0086] like Figure 1 As shown, the data measurement system includes an air tank 3, a laser 4, a laser controller 5, a CCD camera 6, and a particle image velocimeter. The outlet of the air tank 3 is connected to the main pipe inlet of the straight pipe gas distributor 2 in the bubbling bioreactor 1 via a flow meter 7. The laser 4 and the CCD camera 6 are both located on the side of the bubbling bioreactor 1. The control terminal of the laser 4 is connected to the laser controller 5, and the signal output terminal of the CCD camera 6 is connected to the particle image velocimeter. Both the laser controller 5 and the particle image velocimeter are connected to a PC. Hollow glass spheres with a diameter of 30 μm are added to the liquid phase in the bubbling bioreactor as tracer particles. Laser controller 5 controls laser 4 to emit laser light. CCD camera is used to capture images of the hollow glass spheres moving at the outlet of each jet hole in the main pipe under laser irradiation. Particle image velocimeter is used to receive the images captured by CCD camera and calculate the velocity of the hollow glass spheres at the outlet of each jet hole in the main pipe, thereby obtaining the linear jet velocity of each jet hole in the main pipe (e.g., taking the average velocity of each hollow glass sphere at a certain moment at the outlet of the jet hole in the main pipe as the gas jet velocity of that jet hole).

[0087] During the experiment, an auxiliary pipe was first placed inside the main pipe to measure the jet velocity at each jet orifice in the main pipe. Then, the auxiliary pipe was removed, and the jet velocity at each jet orifice in the main pipe was measured again. The two measurements were then compared. Figure 3 As shown, Figure 3 The jet orifices are numbered sequentially from the inlet to the outlet of the main pipe. Without auxiliary pipes, the maximum linear jet velocity occurs at the jet orifice furthest from the main pipe inlet, reaching 64.8 m / s, a difference of 20.6 m / s from the minimum of 44.2 m / s. However, with auxiliary pipes, the maximum linear jet velocity of 56.5 m / s differs from the minimum of 50.9 m / s by only 5.6 m / s. Therefore, the uniformity of the linear jet velocity distribution in the multi-jet straight pipe gas distributor is significantly improved after optimization using the method of this invention.

Claims

1. A method for optimizing the uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor, characterized in that: An auxiliary pipe is placed in the main pipe, and the design variables are optimized as follows: axial spacing between adjacent jet holes in the auxiliary pipe, diameter of the jet holes in the auxiliary pipe, number of jet holes in the auxiliary pipe, inclination angle of the main pipe, distance between the inlet end of the main pipe and the inlet end of the auxiliary pipe, and center distance between the main pipe and the auxiliary pipe. Under the constraint that the error between the mass flow rate at the inlet of the main pipe and the sum of the mass flow rates of all jet holes is less than the error threshold, the linear jet velocity at each jet hole in the main pipe is corrected.

2. The method for optimizing the uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor according to claim 1, characterized in that: The specific process for optimizing design variables is as follows: ① Initialize the linear jet velocity of each jet orifice in the main pipeline; ② Calculate the sum of the mass flow rates of all jet orifices in the main pipeline and the error between this sum and the mass flow rate at the inlet of the main pipeline. ; ③Judgment Check if the value is less than the error threshold. If it is, obtain the values ​​of each design variable; otherwise, adjust the values ​​of the design variables and proceed to step ④. ④ The desired pressure at the i-th jet orifice of the main pipeline after the auxiliary pipeline redistributes pressure to the main pipeline, taking into account frictional resistance loss along the pipeline and jet orifice pressure drop, is expected to be achieved. , If the inlet gas pressure of the main pipeline is the corrected linear jet velocity of the i-th jet orifice in the main pipeline: Where c is the momentum recovery coefficient of the jet orifice. For gas density, The pressure at the i-th jet orifice of the main pipeline that is desired to be achieved when only frictional resistance loss along the pipeline is considered after the auxiliary pipeline redistributes the pressure to the main pipeline. ⑤ Return to step ② and continue until the judgment in step ③ is reached. If the error threshold is less than 1, the final combination of each design variable is obtained.

3. The method for optimizing the uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor according to claim 1, characterized in that: The auxiliary pipe is parallel to the main pipe, and its length and inner diameter are not adjusted once given.

4. The method for optimizing the uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor according to claim 2, characterized in that: Step ① is as follows: Given the volumetric flow rate of compressed air flowing through the inlet of the main pipeline. Initialize the jet velocity of the i-th jet orifice in the main pipe: ； Among them, A i is the cross-sectional area of ​​the i-th jet orifice in the main pipe, and n is the total number of jet orifices in the main pipe.

5. The method for optimizing the uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor according to claim 4, characterized in that: Step ② is as follows: Calculate the total mass flow rate (m) of all jet orifices in the main pipeline: in, The mass flow rate of the i-th jet orifice in the main pipeline. ; Calculate the mass flow rate at the inlet of the main pipeline Error relative to the sum of mass flow rates m from all jet orifices: 。 6. The method for optimizing the uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor according to claim 4 or 5, characterized in that: The pressure at each jet orifice of the main pipeline, after the pressure redistribution from the auxiliary pipeline to the main pipeline, considering only frictional resistance losses along the pipeline, is calculated as follows: Calculate the inlet gas flow velocity of the main pipeline and auxiliary pipeline: in, The gas flow velocity at the main pipeline inlet. To assist the gas flow velocity at the pipeline inlet, Main pipe inner diameter, To assist in determining the inner diameter of the pipe and the volumetric flow rate at the pipe inlet. ; Calculate the gas pressure p at the main pipe inlet using Bernoulli's energy conservation equation. S ; The frictional resistance coefficient of gas flowing in the main pipe is calculated using the Colbrook equation. The coefficient of frictional resistance of gas flowing in the auxiliary pipe ; Calculate the pressure difference between adjacent jet orifices in the main pipeline to account for frictional resistance losses. Pressure difference due to frictional resistance loss between adjacent jet orifices in the auxiliary pipeline and the auxiliary pipeline. : in, The axial spacing between adjacent jet holes in the main pipe. To assist in the axial spacing of adjacent jet holes in the pipeline; Construct a pressure coupling equation that considers only frictional resistance losses along the pipeline after the pressure redistribution from the auxiliary pipeline to the main pipeline: in, To determine the desired pressure at the (i+1)th jet orifice in the main pipeline after the auxiliary pipeline redistributes pressure to the main pipeline, considering only frictional resistance losses along the pipeline, .

7. The method for optimizing the uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor according to claim 6, characterized in that: The Bernoulli energy conservation equation is expressed as follows: in, It is a constant.

8. The method for optimizing the uniform distribution of linear jet velocity in a multi-jet straight pipe gas distributor according to claim 6, characterized in that: The frictional resistance coefficient and The solution is as follows: in, The surface roughness of the main pipeline, To assist in the surface roughness of the pipeline; Reynolds number of gas flowing in the main pipeline The Reynolds number of the gas flowing in the auxiliary pipe. The calculation is as follows: in, This represents the gas dynamic viscosity.

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