Terephthalic Acid Purge Filtration Rate Control
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Solution Overview
Problem
Current processes for producing terephthalic acid result in a purge stream with high catalyst and impurity content, leading to catalyst loss and impurity accumulation, making it economically unattractive to dispose of or treat the oxidizer purge stream effectively.
Innovation Solution
A process involving evaporative concentration, controlled water addition, filtration, and extraction to recover metal catalysts from the oxidizer purge stream, minimizing impurities and catalyst loss by optimizing water usage and filtration steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the oxidizer purge stream is disposed of or treated conventionally, then impurity removal is achieved, but catalyst loss occurs and economic viability deteriorates
Solution Approach 1:
The patent applies the discarding and recovering principle by implementing a multi-step process that first separates and discards impurities from the purge stream through filtration and extraction, then recovers the valuable metal catalyst through precipitation and filtration. The recovered catalyst is dried and can be reused in the oxidation process, thereby minimizing catalyst loss and improving economic viability while effectively removing impurities.
2Quantity of substance
If evaporative concentration is applied to the purge stream, then catalyst concentration is improved for recovery, but filtration rate deteriorates due to slurry concentration
Solution Approach 1:
The patent applies preliminary action by performing evaporative concentration of the purge stream before filtration to pre-concentrate the metal catalyst in the slurry. This preliminary concentration step, while increasing catalyst content, is followed by controlled water addition to optimize the slurry for filtration, ensuring that the high catalyst concentration is maintained while filtration rate is preserved through proper slurry conditioning.
Solution Approach 2:
The patent applies parameter changes by controlling the water content in the filter feed slurry within a specific range (5-25 weight percent) to optimize both catalyst concentration and filtration rate. By adjusting the water parameter in the slurry, the process achieves a balance where sufficient catalyst concentration is maintained for effective recovery while the filtration rate remains adequate for productive operation.
3Productivity
If water is added to the super concentrated purge slurry, then filtration rate is improved, but catalyst concentration is reduced
Solution Approach 1:
The patent applies parameter changes by optimizing the water content parameter in the filter feed slurry to a specific range (5-25 weight percent). This controlled parameter adjustment improves filtration rate by reducing slurry viscosity and enhancing filter cake formation, while the water amount is carefully controlled to minimize catalyst dilution. The parameter optimization ensures both high filtration productivity and adequate catalyst concentration for effective recovery.
4Manufacturing precision
If multiple purification steps are implemented, then impurity removal is enhanced, but process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the purification process into distinct sequential steps: evaporative concentration to concentrate the catalyst, filtration to separate solids from liquid, extraction to remove organic impurities, and precipitation to recover the metal catalyst. Each step targets specific impurities or recovery objectives, achieving high impurity removal efficiency through modular, segmented operations that are easier to control and optimize than a single complex process.
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 process effectively recovers metal catalysts and reduces impurity content in the purge stream, enabling reuse of the catalyst and minimizing catalyst loss, thus improving the economic viability of terephthalic acid production.
Implementation Method 1
subjecting an oxidizer purge stream formed in a terephthalic acid process to evaporation in a 1st evaporator zone to produce a 1st concentrated purge stream and a water vapor stream and subjecting the 1st concentrated purge stream to evaporation in a 2nd evaporator zone to produce a super concentrated purge slurry stream and a 2nd water vapor stream
Implementation Method 2
combining a mass of water from a water stream with the super concentrated purge slurry stream in a mix zone to produce a water rich super concentrated purge slurry
Implementation Method 3
filtering the water rich super concentrated purge slurry in a filtration zone to form a mother liquor and a filter cake
Implementation Method 4
washing the filter cake in a wash zone to produce a washed filter cake and wash liquor
Implementation Method 5
contacting an extraction solvent with the aqueous mixture in an extraction zone to form an extract stream comprising organic impurities and a raffinate stream comprising the metal catalyst
Implementation Method 6
separating the extract stream in a separation zone to form a high boiling point organic impurities stream and a recovered extraction solvent stream
Data Source
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AI summary
The process relates improving the recovery of a metal catalyst from an oxidizer purge stream produced in the synthesis of carboxylic acid, typically terephthalic acid, while utilizing pressure filtration.