Acetic Acid Decanter Liquid Level Feedback Control
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Solution Overview
Problem
Existing processes for producing acetic acid through methanol carbonylation with metal catalysts face challenges in efficiently removing acetaldehyde impurities, leading to quality deterioration and instability in the production process due to fluctuating flow rates and liquid levels in decanters.
Innovation Solution
A closed process is implemented where part of the condensed overhead is recycled back to the reaction system or stored in a buffer tank to stabilize the liquid level in the decanter, adjusting the flow rate to the acetaldehyde separation process, ensuring consistent operation and efficient removal of acetaldehyde.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acetaldehyde is removed from the process circulation liquid to improve product quality, then the concentration of reducing impurities decreases, but the flow rate fluctuates and liquid level becomes unstable
Solution Approach 1:
The patent implements a feedback control mechanism where the liquid level in the decanter is continuously monitored and the flow rate of acetaldehyde removal is adjusted based on the liquid level signal. When the liquid level rises above the set value, the acetaldehyde removal flow rate is increased; when it falls below, the flow rate is reduced. This closed-loop feedback system maintains process stability while ensuring product quality.
Solution Approach 2:
The patent dynamically adjusts the flow rate parameter of acetaldehyde removal based on liquid level conditions. By changing the flow rate from a fixed value to a variable parameter controlled by liquid level feedback, the system achieves both high purity acetic acid production and stable operation.
2Manufacturing precision
If acetaldehyde removal flow rate is increased to improve product quality, then reducing impurity concentration decreases, but energy consumption increases
Solution Approach 1:
The patent optimizes the acetaldehyde removal flow rate parameter based on actual liquid level conditions rather than maintaining a high constant flow rate. This dynamic parameter adjustment reduces energy consumption during normal operation while still achieving the required product purity specifications.
Solution Approach 2:
The patent maintains continuous acetaldehyde removal at an optimized flow rate rather than using intermittent high-intensity removal. This continuous low-level removal is more energy-efficient while still preventing impurity accumulation and maintaining product quality.
3Ease of manufacture
If ordinary distillation is used to remove carbonyl compounds and alkyl iodides, then the separation process is simple, but the boiling points are too close for sufficient removal
Solution Approach 1:
The patent extracts acetaldehyde from the process circulation liquid using a decanter before it can react to form other carbonyl compounds and alkyl iodides. By removing the primary impurity source (acetaldehyde) through phase separation rather than distillation, the system avoids the boiling point proximity problem while maintaining process simplicity.
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 approach allows for stable and efficient production of high-purity acetic acid by maintaining consistent liquid levels and flow rates, effectively recycling methyl iodide and reducing acetaldehyde concentrations, thereby improving product quality and process stability.
Implementation Method 1
a decanter (4) for temporarily holding the condensed overhead (3A)
Implementation Method 2
storing in a buffer tank to stabilize the liquid level in the decanter
Implementation Method 3
adjusting the flow rate to the acetaldehyde separation process
Data Source
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AI summary
A process for stably producing high-purity acetic acid while efficiently removing acetaldehyde is provided. The process for producing acetic acid comprises a reaction step for allowing methanol to react with carbon monoxide in the presence of a metal catalyst, a halide salt, and methyl iodide; a step for continuously feeding a flasher with the reaction mixture and separating a lower boiling point component (2A) containing acetic acid and methyl iodide and a higher boiling point component (2B) containing the metal catalyst and the halide salt; a step for feeding a distillation column with the lower boiling point component (2A), and separating a lower boiling point component (3A) containing methyl iodide and acetaldehyde and a stream (3B) containing acetic acid to collect acetic acid; a condensation step for condensing and temporarily holding the lower boiling point component (3A) in a decanter and discharging the lower boiling point component (3A) from the decanter; and a step for separating the lower boiling point component (3A) discharged from the decanter into acetaldehyde and a liquid residue and recycling the liquid residue to the react ion system . In the condensation step, the amount of the lower boiling point component (3A) to be held is controlled based on a fluctuating flow rate of the lower boiling point component (3A) to be fed to the decanter.