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An ideal static mixer can achieve efficient mixing at low pressure drops. Owing to the excellent performance of the tridimensional rotational flow sieve tray (TRST) in a gas–liquid two‐phase system, the TRST structure was modified into a rotational–perforated static mixer (RPSM) to enhance mixing in multicomponent liquid systems. The energy consumption characteristics of the RPSM were experimentally studied based on Reynolds numbers in the range of 986–7892, gap L = 0–80 mm, and relative angle γ = 0–45°. The effects of the element installation method, number, gap, relative angle, fluid Reynolds number, fluid properties, and other parameters on the RPSM pressure drop were also investigated. An interaction analysis of each factor was performed using the factorial design method and an empirical model of the RPSM Z‐factor was established. Additionally, pressure drop in the RPSM was compared with those of other commonly used static mixers. Results show that, when the element is backward‐installed, the pressure drop is higher than that in the forward direction because the fluid is constantly twisted. Moreover, the pressure drop increases with increasing element gap, and the average increase is 43.64% and 19.28% for the forward and backward installations, respectively. The influence of the relative angle on the pressure drop is mainly reflected when the gap L = 0. Subsequently, the degree of influence of each factor was determined, and the Z‐factor was calculated and found to be consistent with the experimental values (relative error of less than 15%). [ABSTRACT FROM AUTHOR]

A composite tridimensional rotational flow sieve tray (CTRST) is proposed. The flow patterns of CTRST were visually categorized, combined with the standard deviation of the pressure difference. In the TRST area of the internal packing‐type tray, the membrane‐drip column and foam‐embolic flow is present, while bubbly and milk froth‐ribbon flow is present in the packing area of the external packing‐type tray. The effect of the tray structure parameters on the pressure drop under co‐current flow was investigated. The dry and wet pressure drop is within 160 and 900 Pa, respectively. Under the same structural parameters, the pressure drop of the internal packing‐type tray was higher than that of the external packing‐type tray. The flow characteristics of the standard tray under the countercurrent flow were compared. The CTRST was found to be more suitable for co‐current flow. A prediction model pressure drop under co‐current was established with an error of 15.5%. [ABSTRACT FROM AUTHOR]

The blade unit of the tridimensional rotational flow sieve tray (TRST) makes the fluid form a rotational–perforated flow. The analysis of the flow properties of the unit is helpful to understand the hydrodynamic characteristics of TRST. The gas–liquid concurrent flow field was studied using the multi-fluid VOF method. The rotational and perforated flows at each section were analyzed based on the section rotational flow ratios. The section rotational flow ratio for the gas phase was between 0.6 and 0.85, and the transition section of the rotational and perforated flows of the liquid phase was z = 30 mm. The relationships between TRST and blade unit were clarified. The simulation performed for analyzing the mass transfer and structural optimization of the blade unit and TRST. • The rotational and perforated flows are separated by the simulation. • The variation for rotational–perforated flow at each section for gas–liquid phase is studied. • The simulation clarified the transition point of rotational-perforated flow on the blade unit. • The relationships between the blade unit and TRST are analyzed. [ABSTRACT FROM AUTHOR]

• Construction of flowable interior mesh faces on a blade in tridimensional rotational flow sieve tray (TRST). • The effects of centrifugal force, projected area of the sieve holes, and rotational fluid accumulation were clarified. • The formulas were established to calculate the proportions along the flow direction. The distribution law of the rotational and perforated fluid in tridimensional rotational flow sieve trays (TRST) is the key point for revealing its working mechanism and engineering application. Due to complex issues such as overlapping blades, rotational fluid accumulation, and centrifugal force within TRST, it is very difficult to accurately calculate the flow ratio. In this paper, the flowable interior mesh faces were constructed at all sieve holes on a blade, and the velocity distribution on the interior faces was simulated as the fluid perforated through the different sieves, thus calculating the volume flow rate and ratio of the flow through perforations. And the three-blade unit experiment was designed to calculate the perforated ratio of the entire blade. Compared with the simulated values, the relative differences of the gas and liquid phases were within 25% and 10%, respectively, which were in good agreement. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The tridimensional rotational flow sieve tray (TRST) is a novel column internal. • There are two kinds of gas flow pattern coupled with each other in the TRST. • The effect of varied structural parameters on the flow field were investigated. • A correlation to evaluate the tray performance was established. Abstract Using CFD simulation, we first investigated the flow field distribution of the tridimensional rotational flow sieve tray (TRST) under different structural parameters (i.e. number of the blades, twist angle of the blades, tray height and sieve hole diameter) and installation methods (forward and backward) when gas flows downward through the TRST. Secondly, we carried out a comparative study of three modified structures of the tray, i.e. no supporting ring, a closed internal cylinder and no sieve holes present. Finally, we studied the transformed situations of the rotational flow and propose a dimensionless correlation to evaluate the performance of the tray. The results show that, apart from the tray with a smaller twist angle of the blade, the gas flow field distributions for all the other types of trays are similar. When two trays are installed, the gas flow field of the second tray in a forward installation is obviously different to that of a backward installation. The transformed position of the rotational flow for most types of trays is about half the depth of the tray. After comprehensive evaluation, the optimized tray structures are identified as a configuration with 8 blades, a 90° twist angle of the blades, a tray height of 40 mm, and sieve holes of 5 mm diameter. In addition, the tray should have open internal cylinder without a supporting ring. When a multi-tray is installed, the backward installation method should be adopted. [ABSTRACT FROM AUTHOR]

• There are rotational flow, flow through one perforation and flow through two perforations in a tridimensional rotational flow sieve tray (TRST). • The main characteristic of the flow through one perforation is the conversion between rotational liquid film and perforated liquid column. • The flow through two perforations has a more prominent shear effect on the fluid. • The flow through one perforation in the liquid phase was dominant, and the rotational flow in the gas phase was dominant. • The proportions of rotational flow and flow through perforations in coupled state in the TRST are determined. Tridimensional rotational flow sieve trays (TRST) have a variety of gas–liquid flow structures, such as rotational flow, flow through one perforation and flow through two perforations, it is important to have a deep understanding of the coupling and distribution laws of rotational flow and flow through perforations for the selection and regulation of actual working conditions. In this study, the flow structures and proportions for the rotational–perforated coupling flow in a TRST were analyzed and predicted using the measured distribution ratio for the three-blade unit. The results showed that the gas phase mainly flowed in a rotational pattern, and its proportion was approximately 62%–83%. The proportion of flow through perforations in the liquid phase was relatively large, and the proportion of flow through one perforation was approximately 51%–57%. The proportion of flow through two perforations was approximately 27%–29%. [ABSTRACT FROM AUTHOR]

• A improved TRST made by 3D printing was proposed. • The pressure drops of the improved TRST is much lower than that of the original TRST. • The mass transfer performance of TRST was studied. • An energy consumption factor to evaluate the comprehensive performance of TRST was designed. • The optimal geometric parameters of TRST was determined. In this study, the pressure drops and mass transfer performance of a improved tridimensional rotational flow sieve tray (TRST) manufactured by 3D printing under the condition of gas–liquid concurrent flow were investigated experimentally. Results suggest that the pressure drops of the improved TRST are much lower than that of the original TRST due to the transition of the arc surface of the blades is smoother. Dry pressure drop of the TRST is within 12 Pa, and wet pressure drop is within 80 Pa. A volumetric overall mass transfer coefficient of the tray section was proposed, which increased first and then decreased with increased superficial flow factor and concentrations of NaOH solution, increased with the increasing spray density and decreased with the increasing partial pressure of CO 2. For tray geometric parameters, the influence of blade numbers is strongest, twist angle of the blades is weakest, and tray heights and sieve hole diameters are the middling. We also designed an energy efficiency factor to reasonably evaluate the comprehensive performance of TRST. Through comparative analysis, TRST with 8 blades, a 60° or 90° twist angle of the blades, a tray height of 15 mm, and sieve holes of 2 mm diameter were found to has the optimal geometry. [ABSTRACT FROM AUTHOR]

• Hydrodynamic of TRST under the countercurrent flow operation was investigated. • The pressure drop of the TRST is less than 300 Pa. • A mathematical model for predicting TRST's pressure drop is established. • The structure of the TRST or process still requires more significant improvements. The hydrodynamic performance of the TRST in a gas-liquid countercurrent flow column was investigated experimentally in this article. The results show that the operating field can be divided into low and high loading areas according to the increasing rate of the pressure drop. The space utilization of the tray is low, and the flow patterns are mainly droplet-column and continuous film flows. The pressure drops of the tray at each installed locations are different, indicating that the gas-liquid load of each tray is unbalanced. Compared with concurrent flow operation, the range of gas flux is at least 45% less, and the liquid flux range is at least 37.5% less. Compared with other new tray types under countercurrent flow operation, the pressure drop of the TRST is smaller, less than 300 Pa, but the range of gas-liquid flux is also narrow. The empirical models of the pressure drops, loading curve, and flooding curve agree well with the experimental data. [ABSTRACT FROM AUTHOR]