Fluidized Bed Reactor Internals for Early Bubble Breakup
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Solution Overview
Problem
The presence of vertical internals in fluidized bed reactors affects bubble formation and mixing in propylene ammoxidation reactions, impacting the production of acrylonitrile, and existing designs do not effectively limit or break up bubbles, leading to inefficiencies in heat and mass transfer.
Innovation Solution
Optimizing the distribution and design of heat removal water pipes and cyclone separators within the reactor, with specific ratios and configurations of cross-sectional areas and circumferences, to promote early flow pattern changes, break bubbles, and reduce back mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional vertical internals (heat removal water pipes and cyclone separators) are used in fluidized bed reactor, then heat removal and catalyst separation functions are achieved, but bubble growth is not effectively limited and back mixing occurs reducing mass transfer efficiency
Solution Approach 1:
The patent changes the geometric parameters of vertical internals by optimizing the ratio of outer contour circumference to cross-sectional area (L1/S1) to fall within 2.0-4.3 m⁻¹. This parameter optimization enables the internals to effectively break bubbles and limit bubble growth while maintaining heat removal and catalyst separation functions, thereby improving both productivity and transfer efficiency.
Solution Approach 2:
The patent makes the vertical internals multi-functional by designing them to simultaneously perform heat removal, catalyst separation, and bubble breaking functions. The optimized vertical internals structure allows a single component to achieve multiple objectives: removing heat from the reaction zone, separating catalyst from gas stream, and breaking bubbles to improve mass transfer, thus resolving the contradiction between productivity and transfer efficiency.
2Productivity
If vertical internals are added to break bubbles and improve mass transfer, then conversion rate and product yield increase, but device complexity and structural optimization requirements increase
Solution Approach 1:
The patent simplifies the design process by establishing a specific parameter range (L1/S1 = 2.0-4.3 m⁻¹) that automatically ensures effective bubble breaking performance. Instead of requiring complex iterative optimization, designers can directly select vertical internals within this parameter range to achieve the desired conversion rate and product yield without excessive structural complexity.
3Reliability
If vertical internals are optimized to break bubbles early in the reaction zone, then mass transfer efficiency improves and deep oxidation products are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines a practical parameter range (L1/S1 = 2.0-4.3 m⁻¹) that balances manufacturing precision requirements with mass transfer efficiency. This range is wide enough to accommodate normal manufacturing tolerances while still ensuring effective bubble breaking and early flow pattern changes, reducing deep oxidation products without requiring excessive dimensional accuracy.
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
Improves conversion rates of feed gas, increases yield of target products, and enhances heat and mass transfer efficiency while prolonging the operation period of the reactor.
Implementation Method 1
The heat removal water pipe can remove a large amount of heat generated during the reaction out of the reaction system in time and maintain the reaction temperature in a stable state
Implementation Method 2
the presence of vertical internals helps to break up the bubbles, and that small bubbles are more conducive to mass transfer than large bubbles
Implementation Method 3
the cyclone separator can capture the catalyst carried by the gas moving upwards and return the catalyst to the catalyst bed through the dipleg
Implementation Method 4
The reaction is strongly exothermic and is accompanied by a large amount of heat generation
Data Source
AI summary
Disclosed is a fluidized bed reactor and a heat removal water pipe and application thereof in acrylonitrile production. The fluidized bed reactor comprises at least a reaction cooling section and a vertical inner component provided in the reaction cooling section. Where, at a cross section transverse and perpendicular to a central axis of the fluidized bed reactor, an area of the cross section of the reaction cooling section is designated as S1 (expressed in a unit of m2) and an outer contour circumference of the cross section of the vertical inner component is designated as L1 (expressed in a unit of m), L1/S1=2.0-4.3 m−1. The fluidized bed reactor can promote the breaking of bubbles as early as possible and effectively limit the growth of the bubbles.