Bubble Column Reactor Oxygen Distribution
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Solution Overview
Problem
Conventional liquid-phase oxidation reactors for producing terephthalic acid, such as CSTRs and bubble column reactors, face issues with oxygen starvation, mechanical failures, and costly purification processes, leading to impurities and high production costs.
Innovation Solution
A bubble column reactor design with an external and internal reaction vessel configuration, where the internal reaction vessel has direct openings for fluid communication between zones, optimizing oxygen distribution and minimizing unaerated zones to enhance oxidation efficiency and reduce mechanical agitation, thereby producing crude terephthalic acid with lower impurities and lower energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If mechanical agitation means are used in CSTRs to provide thorough mixing, then mixing efficiency is improved, but capital cost and maintenance requirements increase
Solution Approach 1:
The patent replaces mechanical agitation systems with a gas sparging system that introduces gas bubbles into the reaction medium. The rising bubbles create natural convection and mixing without requiring mechanical agitators, motors, or sealed bearings, thereby eliminating the complex mechanical components while achieving thorough mixing through fluid dynamics
Solution Approach 2:
The invention uses gas sparging - introducing gas through spargers at the bottom of the reactor - to create liquid circulation and mixing. The gas-liquid interaction generates turbulent flow patterns that distribute reactants uniformly throughout the reaction medium, achieving mixing efficiency through pneumatic means rather than mechanical agitation
2Device complexity
If gas sparging is used to provide agitation without mechanical equipment, then capital and maintenance costs are reduced, but oxygen distribution uniformity may be insufficient
Solution Approach 1:
The patent divides the gas sparging system into multiple spargers positioned at different locations (bottom and side walls) rather than using a single sparger. This segmentation of the gas introduction points creates more uniform oxygen distribution throughout the reaction medium by eliminating localized high and low oxygen zones
Solution Approach 2:
The invention positions spargers at specific locations (bottom center and side walls at different heights) to address local oxygen distribution needs. The side wall spargers specifically target regions that might be oxygen-starved in conventional bottom-sparging-only systems, creating locally optimized oxygen distribution throughout the reactor volume
3Quantity of substance
If liquid phase contains insufficient molecular oxygen concentration, then oxygen availability for reaction is reduced, but side-reactions generate impurities
Solution Approach 1:
The patent extracts or removes oxygen-starved zones from the reaction system by implementing multiple spargers that ensure adequate oxygen distribution throughout the entire reaction medium. This eliminates the conditions that lead to oxygen starvation and subsequent impurity-generating side reactions
Solution Approach 2:
The multi-sparger configuration provides a feedback mechanism where gas is introduced at multiple points to maintain uniform oxygen levels. The system self-regulates by ensuring that no region becomes oxygen-depleted, as the distributed sparging prevents the formation of oxygen-starved zones that would trigger unwanted side reactions
4Productivity
If excess concentration of oxidizable compound is present in liquid phase, then reaction rate increases, but side-reactions generate impurities
Solution Approach 1:
The uniform oxygen distribution provided by multiple spargers creates a feedback mechanism that maintains optimal reactant ratios throughout the reaction medium. By ensuring adequate oxygen availability in all regions, the system prevents oxygen starvation that would otherwise cause side reactions, allowing high concentrations of oxidizable compound to be processed cleanly
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 optimized reactor system achieves higher oxygen solubility, reduced impurity generation, and lower production costs by minimizing oxygen-starved zones and mechanical failures, resulting in a more efficient and economical process for producing terephthalic acid.
Implementation Method 1
Agitation of the reaction medium in the reaction zone is provided primarily by the natural buoyancy of gas bubbles rising through the liquid phase of the reaction medium
Implementation Method 2
At least a portion of the molecular oxygen introduced into the reactor as a gas dissolves into the liquid phase of the reaction medium to provide oxygen availability for the liquid-phase reaction
Data Source
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AI summary
Disclosed is an optimized process and apparatus for more efficiently and economically carrying out the liquid-phase oxidation of an oxidizable compound. Such liquid-phase oxidation is carried out in a bubble column reactor that provides for a highly efficient reaction at relatively low temperatures. When the oxidized compound is para-xylene and the product from the oxidation reaction is crude terephthalic acid (CTA), such CTA product can be purified and separated by more economical techniques than could be employed if the CTA were formed by a conventional high-temperature oxidation process.