Reactor Design for Immiscible Fluid Hydrogenation
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Solution Overview
Problem
Existing reactors face challenges in optimizing the reaction between immiscible fluids of different densities, as excess hydrogen gas reduces the available reaction volume and limits efficient hydrogenation due to incomplete mixing and backmixing.
Innovation Solution
A reactor design featuring a cylindrical shell with distinct zones for backmixed, limited backmixing, and plug-flow, utilizing internal elements and mixing apparatuses like stirrers and jet nozzles to ensure optimal contact and residence time distribution, preventing backmixing through random or structured packings, and employing a loop reactor with an external heat exchanger for efficient hydrogenation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If excess hydrogen gas is used to ensure complete hydrogenation conversion, then reaction conversion is improved, but the available reaction volume is reduced and mixing efficiency deteriorates
Solution Approach 1:
The reactor is segmented into multiple zones with different flow characteristics: a backmixed zone for initial reaction and heat removal, a transition zone for limited backmixing, and a plug-flow zone for completion of conversion. This segmentation allows optimal utilization of reaction volume while ensuring complete hydrogenation through progressive conversion in each zone.
Solution Approach 2:
Different zones within the reactor are assigned different local flow characteristics and mixing intensities. The backmixed zone provides intense mixing for efficient hydrogen dissolution and heat removal, while the plug-flow zone maintains unidirectional flow for high conversion efficiency. This local differentiation optimizes both reaction volume utilization and conversion completeness.
2Stability of the object's composition
If backmixing is increased to improve mixing efficiency, then hydrogen dissolution is improved, but residence time distribution deteriorates and reaction efficiency is reduced
Solution Approach 1:
The reactor is divided into zones with progressively decreasing backmixing intensity. The first zone allows strong backmixing for efficient hydrogen dissolution and heat removal, while subsequent zones reduce backmixing to maintain favorable residence time distribution and prevent premature product removal from the reaction zone.
Solution Approach 2:
The reactor design maintains continuous progressive conversion through multiple zones, where each zone contributes to the overall hydrogenation process. The transition from backmixed to plug-flow characteristics ensures continuous improvement of conversion while maintaining efficient mixing in the initial zone, preventing any single zone from becoming a bottleneck.
3Device complexity
If a single reaction zone is used to simplify reactor structure, then device complexity is reduced, but residence time distribution and conversion efficiency deteriorate
Solution Approach 1:
The reactor is segmented into multiple functional zones (backmixed zone, transition zone, plug-flow zone) that can be implemented using relatively simple internal structures such as baffles, packing materials, or changes in cross-sectional area. This segmentation achieves complex residence time distribution patterns without requiring overly complicated reactor geometries or control systems.
Solution Approach 2:
The reactor exploits changes in flow parameters (mixing intensity, flow direction, residence time) along the axial direction to achieve different reaction objectives in different zones. By varying physical parameters such as cross-sectional area, presence of packing materials, or baffle configurations, the reactor optimizes conversion efficiency without requiring fundamental changes to the basic reactor structure.
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 enhances the residence time distribution, allowing for complete conversion of reactants and optimal utilization of reaction space by minimizing backmixing and maintaining a single liquid phase in critical zones, thereby improving hydrogenation efficiency.
Implementation Method 1
the backmixed zone comprises at least one inlet and the plug-flow zone comprises an outlet and the backmixed zone comprises at least one mixing apparatus selected from a stirrer, a jet nozzle and means for injecting the fluid of lower density
Implementation Method 2
WO 2009/153123 describes a continuous process for the hydrogenation of organic compounds in a multiphase system in the presence of a homogeneous or heterogeneous catalyst in which the process is performed in two stages, the first being performed in a loop reactor with external heat exchanger
Implementation Method 3
the interior is divided by internals into a backmixed zone, a zone of limited backmixing preferably arranged below the backmixed zone and a plug-flow zone which are at least consecutively traversable by one of the fluids
Data Source
AI summary
A reactor for performing a reaction between two immiscible fluids of different density, comprising an interior formed by a cylindrical, vertically oriented elongate shell, a bottom and a cap, wherein the interior is divided by internals into a backmixed zone, a zone of limited backmixing preferably arranged below the backmixed zone and a plug-flow zone which are at least consecutively traversable by one of the fluids, wherein the backmixed zone comprises at least one inlet and the plug-flow zone comprises an outlet and the backmixed zone comprises at least one mixing apparatus selected from a stirrer, a jet nozzle and means for injecting the fluid of lower density, a first cylindrical internal element which in the interior extends in the longitudinal direction of the reactor, which delimits the zone of limited backmixing from the plug-flow zone and which comprises a first passage to the backmixed zone and a second passage to the plug-flow zone, a second internal element which delimits the backmixed zone from the plug-flow zone such that there is no direct fluid connection between the backmixed zone and the plug-flow zone, and backmixing-preventing third internal elements in the form of random packings, structured packings or liquid-permeable trays arranged in the zone of limited backmixing. The reactor allows an optimal residence time distribution in the reaction of the two immiscible fluids of different density. The invention further relates to a process for performing a continuous reaction in the reactor.