Bubble Column Sparger for Liquid-Phase Oxidation
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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 high capital and maintenance costs, mechanical failures, and inefficient purification processes that result in impure crude terephthalic acid requiring costly purification steps like hydrogenation and multi-step crystallization.
Innovation Solution
A bubble column reactor design with a sparger that introduces molecular oxygen through a plurality of oxidant openings, optimizing the pressure drop and direction of the oxidant stream to enhance oxygen solubility and reduce impurity formation, allowing for the production of crude terephthalic acid that can be purified without heat-promoted dissolution in water and hydrogenation, using a process that includes introducing a predominately liquid-phase stream and a predominately gas-phase stream into the reactor via a common sparger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional CSTRs with mechanical agitation are used, then thorough mixing of the reaction medium is achieved, but capital cost and maintenance costs increase due to expensive motors, fluid-sealed bearings, and complex stirring mechanisms
Solution Approach 1:
The patent replaces mechanical agitation systems with gas-phase sparging to achieve mixing and mass transfer. Gas bubbles rising through the liquid phase provide natural convection and agitation, eliminating the need for motors, bearings, and complex stirring mechanisms while maintaining uniform distribution of oxygen and reactants
Solution Approach 2:
The patent uses gas-phase oxidant streams introduced through spargers to achieve both mixing and oxygen transfer. The gas-liquid flow patterns created by sparging provide effective agitation and mass transfer without mechanical moving parts, reducing capital and maintenance costs
2Quantity of substance
If high pressure drop is applied to the oxidant stream, then oxygen dissolution into the liquid phase is enhanced, but energy consumption and operating costs increase
Solution Approach 1:
The patent optimizes sparger design parameters including pore size, pore density, and gas flow rates to achieve effective oxygen transfer at low pressure drops. By changing the physical parameters of the sparging system rather than increasing pressure, the patent achieves high dissolved oxygen concentrations with minimal energy loss
Solution Approach 2:
The patent employs porous spargers that distribute gas through numerous small pores, creating fine bubbles with high surface area-to-volume ratio. This enhances oxygen dissolution efficiency without requiring high pressure drops, as the porous structure provides extensive gas-liquid interfacial area for mass transfer
3Manufacturing precision
If conventional purification processes are used, then crude terephthalic acid is purified, but costly steps including hydrogenation and multi-step crystallization are required
Solution Approach 1:
The patent extracts or removes impurity formation mechanisms by optimizing reaction conditions and sparging to prevent side reactions. By taking out the problematic side reactions that generate impurities in the first place, the patent eliminates the need for complex downstream purification steps including hydrogenation and multiple crystallization operations
Solution Approach 2:
The patent converts the potential harm of oxygen starvation (which causes impurity formation) into a benefit by using controlled sparging to ensure uniform oxygen distribution. This prevents side reactions and impurity generation, simplifying the purification process while maintaining high product purity
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 solution reduces capital and maintenance costs, minimizes mechanical failures, and produces pure terephthalic acid through a more economical and efficient process that eliminates the need for costly purification steps, resulting in a more effective and economical production of terephthalic acid.
Implementation Method 1
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
Implementation Method 2
wherein the pressure drop associated with discharging the oxidant stream from the conduit is not more than about 0.3 megaPascals (MPa)
Implementation Method 3
a liquid-phase feed stream and a gas-phase oxidant stream are introduced into a reactor and form a multi-phase reaction medium in the reactor
Implementation Method 4
Agitation of the reaction medium is supplied in an effort to promote dissolution of molecular oxygen into the liquid phase of the reaction medium, maintain relatively uniform concentrations of dissolved oxygen in the liquid phase of the reaction medium
Implementation Method 5
liquid-phase catalytic partial oxidation of para-xylene to terephthalic acid
Implementation Method 6
liquid-phase catalytic oxidation of an aromatic compound
Data Source
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.