Asymmetric Flow Splitter for Micro-Reactor Mixing

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Solution Overview

Problem

Existing fluid mixing structures in continuous reaction reactors face challenges in multiphase reactions due to uneven flow distribution and phase segregation, leading to inadequate mixing and mass transfer in micro-reactors, especially during scale-up and scale-down processes.

Innovation Solution

A fluid mixing structure with a contraction zone, expansion zone, and retention zone, featuring a polygonal or flame-shaped flow splitter that splits and mixes fluid flows to ensure a non-zero average flow component in the inflow direction, preventing centrifugal forces and promoting homogenization, thereby enhancing mixing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If parallel rows of mixers are used to increase flow rate, then productivity increases, but flow distribution uniformity deteriorates due to pressure fluctuations from phase interfaces

Engineering Contradiction:
Improveflow rateVSAvoidflow distribution uniformity
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The continuous reactor is divided into multiple parallel rows of mixing structures, each handling a portion of the total flow. This segmentation allows the system to process higher overall flow rates while maintaining controlled flow distribution in each individual row, resolving the contradiction between productivity and flow uniformity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The mixing structure employs asymmetric geometry with a spade-like element that has different curvature radii on its convex and concave sides. This asymmetric design creates favorable flow patterns that reduce pressure fluctuations and improve flow distribution uniformity across parallel rows, addressing the stability issue while maintaining high productivity.

Inventive Principle:
Principle #4Asymmetry

2Ease of manufacture

If symmetric spade-like mixing structures are used, then manufacturing is simplified, but phase segregation increases due to centrifugal forces pushing denser fluid outward

Engineering Contradiction:
Improvestructural symmetryVSAvoidphase mixing quality
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The mixing structure deliberately uses asymmetric geometry where the convex side has a different curvature radius than the concave side. This asymmetry counteracts the centrifugal forces that cause phase segregation in symmetric designs, allowing the denser fluid to be redistributed more effectively and maintaining phase mixing quality while remaining manufacturable.

Inventive Principle:
Principle #4Asymmetry

3Temperature

If smaller process channel dimensions are used in micro-reactors, then heat transfer efficiency improves due to increased surface-to-volume ratio, but mass transfer rate deteriorates due to diffusion-driven laminar flow

Engineering Contradiction:
Improveheat transfer rateVSAvoidmass transfer rate
Core Design Contradiction:
TemperatureVSProductivity

Solution Approach 1:

The asymmetric spade-like mixing structure generates turbulent flow patterns and secondary flows that enhance mass transfer by disrupting the laminar diffusion-driven flow. This mechanical disturbance increases the mass transfer rate while maintaining the efficient heat transfer characteristics of small-scale micro-reactor channels.

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

The invention changes the flow regime parameters by introducing turbulent flow through the asymmetric mixing structure. This parameter change from laminar to turbulent flow enhances mass transfer coefficients, allowing high productivity to be achieved in small-diameter channels while preserving the heat transfer advantages of micro-reactor geometry.

Inventive Principle:
Principle #35Parameter changes

4Stability of the object's composition

If complex micro-reactors with multiple consecutive fluid mixing structures are used, then mixing efficiency improves, but pressure loss increases and residence time decreases

Engineering Contradiction:
Improvemixing efficiencyVSAvoidpressure loss
Core Design Contradiction:
Stability of the object's compositionVSStress or pressure

Solution Approach 1:

The reactor is segmented into multiple parallel rows of mixing structures rather than using a single complex sequential arrangement. This parallel segmentation achieves high mixing efficiency through distributed mixing while reducing cumulative pressure losses compared to multiple consecutive mixing elements in series.

Inventive Principle:
Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design achieves improved mixing and mass transfer by generating a fully dispersed flow regime with increased interfacial area, resulting in higher mass transfer coefficients and more efficient reaction conditions, even at lower flow rates, compared to traditional structures.

Implementation Method 1

transport phenomena are diffusion driven and thus relatively slow

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

techniques are used to generate secondary flow regimes resulting in a flow field that resembles transitional or turbulent flow

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

techniques are used to generate secondary flow regimes resulting in a flow field that resembles transitional or turbulent flow rather than laminar flow

Methodology Applied
Scientific EffectTurbulence: Turbulence

Implementation Method 4

The centrifugal forces in such curvatures push the denser fluid towards the outside perimeter

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 5

recirculatory motion within the slug flow homogenizes (i. e. makes more homogeneous or enhances the homogeneity) its interior and reduces the thickness of the boundary layer at the interface, thus increasing mass transfer rate along the channel axis

Methodology Applied
Scientific EffectMass transfer: Diffusion

Implementation Method 6

The continuous dissipation of energy can generate and maintain dispersion smaller than slugs throughout the reactor's volume

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 7

The geometry may strongly effect the interfacial area available for mass, momentum or energy exchange between the phases

Methodology Applied
Scientific EffectInterfacial area: Surface Tension

Data Source

PatentEP3031518B1Fluid mixing structure, continuous reaction unit, continuous reaction reactor and method of using the same
Publication Date: 2021.01.20 LONZA AG
  • EP3031518B1 patent drawingFigure 1A~1B
  • EP3031518B1 patent drawingFigure 1C~1D
  • EP3031518B1 patent drawingFigure 2A~2C

AI summary

A fluid mixing structure (10) for mixing at least two fluidic components has a flow inlet port and a flow outlet port and comprises a contraction zone (12), an expansion zone (14), and a retention zone (16), arranged in this order in an inflow direction (IFD) of a fluid flow to flow through said fluid mixing structure (10) and being composed of said at least two fluidic components, and a flow splitter (32) arranged in a space (30) formed by said expansion zone (14) and said retention zone (16) to split said fluid flow in a first sub fluid flow and a second sub fluid flow flowing in a first flow path and a second flow path, respectively, formed in the fluid mixing structure, and to mix said first and second sub fluid flows within said space (30) to generate and discharge a homogenized fluid flow, wherein said flow splitter (32) is arranged and configured to let any flow element of each of said first and second sub fluid flows prior to their mixing have a non-zero average flow component in said inflow direction (IFD).