Microscale Reactor Microposts for BHD Mass Transfer
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Solution Overview
Problem
Conventional large-scale batch reactor systems for producing biohydrogenated diesel (BHD) face mass and heat transfer limitations, leading to inefficient catalyst use and high energy requirements, as well as issues with mass transfer between the bulk phase and catalyst surface in multiphase reactors.
Innovation Solution
Microscale-based reactors with a high specific surface-to-volume ratio, featuring microchannel designs with catalyst-coated microposts, enhance mass and heat transfer by reducing transfer resistance and improving mixing of reactants, thereby increasing reactor efficiency and product yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional large-scale batch reactor systems are used for BHD production, then production capacity is achieved, but mass and heat transfer limitations occur leading to inefficient catalyst use and high energy requirements
Solution Approach 1:
The reactor system is segmented into microscale channels with characteristic dimensions less than 1 mm, creating numerous small reaction zones instead of a single large batch reactor. This segmentation increases the total surface area for mass and heat transfer while maintaining production capacity through parallel flow paths.
Solution Approach 2:
The invention transitions from macro-scale three-dimensional batch mixing to micro-scale two-dimensional laminar flow with enhanced surface-to-volume ratio. This dimensional change at the microscale fundamentally improves mass and heat transfer efficiency by reducing diffusion distances.
2Reliability
If conventional multiphase reactors (fluidized bed or fixed bed) are used, then reactor operation is achieved, but mass transfer is limited due to low specific interfacial area
Solution Approach 1:
The continuous catalyst bed in conventional reactors is segmented into discrete microposts arranged in arrays within microchannels. This segmentation creates numerous small catalyst surfaces exposed to flowing reactants, dramatically increasing the specific interfacial area while maintaining reliable continuous operation.
Solution Approach 2:
The invention uses controlled fluid flow through microchannels to achieve effective contact between gas-liquid reactants and catalyst surfaces. The hydraulic design ensures uniform distribution and appropriate residence time, replacing the need for fluidized bed dynamics while achieving superior mass transfer.
3Quantity of substance
If microchannel reactors are used for gas-liquid catalytic reactions, then mass transfer is improved by diffusion, but channel clogging occurs leading to flow channeling and high pressure drops
Solution Approach 1:
The microchannel geometry is designed with varying local characteristics including gradual expansions, contractions, and optimized cross-sections at critical locations. This local quality variation prevents uniform clogging by creating zones that facilitate particle suspension and reduce deposition, maintaining flow stability while preserving mass transfer efficiency.
Solution Approach 2:
The reactor design incorporates dynamic flow management through carefully designed inlet/outlet configurations and channel geometries that adapt to changing operating conditions. This dynamic design prevents stagnant zones and promotes continuous particle-catalyst interaction, reducing clogging while maintaining efficient mass transfer.
4Volume of moving object
If microchannel reactors are used for gas-liquid reactions, then compact design is achieved, but reactants are not well mixed and in good intimate contact with catalyst at channel wall
Solution Approach 1:
Microposts with curved or rounded surfaces are used instead of sharp-edged structures. The curvature promotes fluid circulation and prevents dead zones around catalyst surfaces, enhancing mixing efficiency while maintaining the compact microchannel geometry. The curved surfaces also reduce flow separation and improve contact between reactants and catalyst.
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
The microscale reactors enable more efficient production of BHD by improving mass transfer, reducing channel clogging, and enhancing reaction efficiency, yield, and selectivity, while allowing for scalable and continuous production.
Implementation Method 1
mass transfer between bulk phase and catalyst surface primarily occurs by diffusion, which can eliminate the mass transfer effect limitation
Implementation Method 2
these reactors have a very high surface-to-volume ratio that significantly effects mass transfer by reducing mass transfer distances, thus decreasing transfer resistance
Data Source
AI summary
Disclosed microscale reactors comprise lamina for carrying out multi-phase reactions for making desired chemical products, such as biohydrogenated diesel (BHD). Microreactor embodiments include a bottom clamp plate, a top clamp plate, and at least one catalyst plate positioned between and operatively associated with the bottom clamp plate and the top clamp plate. Catalyst plates include a catalyst associated for catalyzing the production of product from feedstock. To address the problems encountered when using microchannel reactors, the microscale-based reactors may include a mixer plate assembly and/or at least one catalyst lamina comprising an array of microscale posts. Disclosed microreactor systems for producing BHD include a feedstock source, a hydrogen source and an inert gas source each fluidly coupled to respective microreactor inlets. Certain method embodiments include operating a microreactor or a microreactor system to produce BHD from a suitable feedstock selected from animal fats, vegetable oils, or combinations thereof.