Key design principles for gas distributors in stirrer tanks

This is related to the processing method; if high dispersion isn’t required, the gas can be directly introduced into the tube, with the stirring paddle being used to disperse it. Alternatively, it can be installed at the bottom of the tank – this depends on the properties of the material

My reaction is a gas-liquid reaction, which requires a high degree of uniform distribution of the gas within the liquid phase; the uniformity of this dispersion directly determines the quality of the product. How should such a gas distributor be designed? Please be as specific as possible, thank you!

I specifically looked up information on gas distributors on HaiChuan; here are some references: 1. http://bbs.hcbbs.com/viewthread.php?tid=352018&highlight=%C6%F8%CC%E5%B7%D6%B2%BC%C6%F7 2. HaiYou LanTian WuHen said that there is a master’s thesis titled “Study on the Performance and Scaling Laws of Double-Annular Circulation Gas Distributors”; you can go and take a look at it. Maybe there’s something you want. I don’t have this paper; it’s available for purchase online. The abstract of the original text is as follows: This paper uses the computational fluid dynamics software FLUENT to study the influence of structural parameters of a double-cut annular gas distributor on its distribution performance, thereby determining the effects of various parameters on gas distribution. The performance of the distributor is quantitatively evaluated using the distributor pressure drop ΔP and the gas distribution uniformity M, while qualitative analysis is conducted through contour plots of velocity, pressure, turbulent kinetic energy, and turbulent kinetic energy dissipation rate at different sections. The main factors affecting the distributor’s performance include the distance between the tower wall and the inner cylinder, the height of the inner cylinder, the height of the baffles, the number of baffles, and the eccentricity of the inner cylinder. In addition, this paper also examines the performance of distributors equipped with lift pipes. Under the conditions studied in this paper, it was found that among all the structural parameters, the distance between the tower wall and the inner cylinder has the greatest impact on distributor performance, with an optimal value of (0.25/6)D. When the lower edge of the inner cylinder is below the lower edge of the inlet pipe, as the height of the inner cylinder increases, M gradually decreases while ΔP gradually increases. According to the simulation results, the optimal height of the inner cylinder is (2.5/1.5)d. Once the height of the first baffle approaches or exceeds the centerline of the inlet pipe, changes in M due to variations in baffle height become less significant, while ΔP increases rapidly. When the height of the first baffle is (0.75/1.5)d, the distributor performs better. An excessive number of baffles does not effectively improve the distribution performance of the distributor; instead, it increases the distributor’s pressure drop. A suitable number of baffles is 7. For eccentric inner cylinder distributors, when the inner cylinder is tilted toward the inlet side, it helps to achieve more even gas distribution, but the distributor’s pressure drop increases. When the inner cylinder is far from the inlet, the distributor’s pressure drop decreases significantly, while M increases gradually. The use of lift pipes in double-cut annular gas distributors significantly improves the gas distribution effect. To verify the reliability of the model and software, experimental measurements were taken of the flow field in an experimental tower equipped with a lift-type gas distributor. The flow field of this device was then simulated using FLUENT, and the simulation results were compared with the experimental results, showing good agreement. This confirms that using FLUENT software to study the flow field of gas distribution devices in packed towers yields reliable results.

Detailed Table of Contents
Abstract
English Abstract
Statement of Originality and Authorization for Use of Thesis Copyright
Introduction
Chapter 1 Literature Review
1.1 Basic Structure and Performance of Various Packed Tower Gas Distributors
1.2 Influence of Gas Distribution on Packed Tower Performance
1.3 Current Research Status on Gas Distributor Performance
1.4 Theoretical Research Methods for Gas Distributors – Computational Fluid Dynamics
1.4.1 Mathematical Models of Computational Fluid Dynamics
1.4.2 Solution Process of Computational Fluid Dynamics
1.4.3 Introduction to Commonly Used Software in Computational Fluid Dynamics
1.5 Research Content of This Thesis
Chapter 2 Computational Fluid Dynamics Models and Solution Methods
2.1 Fundamental Equations
2.2 Turbulent Closure Models
2.2.1 Standard k-ε Two-Equation Model
2.2.2 RNG (Renormalized Group) k-ε Model
2.2.3 Realizable k-ε Model
2.3 Turbulent Wall Models
2.4 Multiphase Flow Models
2.5 Numerical Solutions to Differential Equations
2.5.1 Discretization Techniques for Equations
2.5.2 Numerical Calculation Methods
2.5.3 Solution of Discrete Equations
Chapter 3 Model Establishment and Computer Simulation of Double-Cut Annular Gas Distributors
3.1 Model Establishment
3.1.1 Physical Model
3.1.2 Mathematical Model
3.1.3 Boundary Conditions
3.2 Quantitative Indicators for Evaluating Gas Distributor Performance
3.2.1 Distributor Pressure Drop ΔP
3.2.2 Gas Distribution Uniformity M
3.3 Simulation Plan and Establishment/Solution of the Calculation Model
3.4 Results and Discussions
3.4.1 Influence of Distance Between Tower Wall and Inner Cylinder on Distributor Performance
3.4.2 Influence of Inner Cylinder Height on Distributor Performance
3.4.3 Influence of Baffle Height on Distributor Performance
3.4.4 Influence of Number of Baffles on Distributor Performance
3.4.5 Influence of Inner Cylinder Eccentricity on Distributor Performance
3.4.6 Influence of Distance Between Lift Pipes and Distributor on Distributor Performance
Chapter 4 Experimental Measurement and Numerical Simulation of Lift-Type Gas Distributor Performance
4.1 Experimental Study on Distribution Performance of Lift-Type Gas Distributors
4.1.1 Experimental Procedure
4.1.2 Experimental Equipment and Conditions
4.1.3 Experimental Steps
4.1.4 Data Processing
4.2 Numerical Simulation of Lift-Type Gas Distributor Performance
4.2.1 Simulation Steps
4.2.2 Simulation Results and Analysis
4.2.3 Comparison between Simulation Results and Experimental Results
Chapter 5 Conclusions
References
Information on Published Papers and Research Activities
Symbol Explanation
Appendix: Experimental Data on Lift-Type Gas Distributors
3. The design of gas distributors is closely related to the internal components of the tower, and they are generally designed by the suppliers of these internal components

Upstairs, the double-cut annular gas distributor is used only in the empty tower section and cannot be used for distributing gas in liquids. In a mixing tank, the gas distributor can take the form of perforated tubes or a porous plate. The diameter and number of distribution holes are determined based on the gas flow rate.

Regarding the gas-liquid distribution issue raised by the poster, the following measures can be taken: 1. The gas distributor should be designed as a ring-shaped one, with 4 openings at 90-degree intervals or 3 openings at 120-degree intervals; spiral nozzles should be installed at these openings to ensure a more even distribution of the gas. 2. The gas distributor should be installed in conjunction with the stirrer; placing the distributor in the area where the stirring intensity is highest can effectively improve the distribution of gas and liquid.

5# tanmx: either the perforated tube type or the porous plate type; personally, I think the latter is better! It has a simple structure and the performance should be okay; it’s easy to understand! If that doesn’t work, we’ll have to resort to high technology, hehe···

When using tubular gas distributors, it is important to take into account the properties of the material when determining the size of the distribution holes. For materials that tend to stick together, measures must be taken to prevent clogging. Our company has also used such distributors; they were designed with only uniform distribution in mind, but the distribution holes turned out to be too small, resulting in clogging!

Self-priming agitation is a commonly used tool in industry for gas intake and distribution in tanks; several generations of it have been developed to date, and the technology is now well-established. If the owner’s vessel has a large tonnage or high added value, it is recommended to use a loop reactor