Acetic Acid Production Crotonaldehyde Control Dehydration Column
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Solution Overview
Problem
The industrial production of acetic acid through the carbonylation of methanol method faces challenges in achieving a good potassium permanganate test value without incurring high costs, primarily due to the presence of by-products like crotonaldehyde and 2-ethyl crotonaldehyde, which require expensive equipment for removal.
Innovation Solution
Controlling the crotonaldehyde concentration in the acetic acid stream to not more than 2.2 ppm by mass or setting the reflux ratio of the dehydration column to not less than 0.32 in the carbonylation process, allowing for the efficient production of high-quality acetic acid without the need for large-scale acetaldehyde removal equipment and ozonation equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If expensive separation and removal equipment (acetaldehyde removal equipment and ozonation equipment) is used to decrease crotonaldehyde and improve potassium permanganate test value, then the quality of acetic acid is improved, but the equipment cost increases significantly
Solution Approach 1:
The invention extracts and removes crotonaldehyde from the acetic acid stream using a dehydration column operating at specific reflux ratios (not less than 0.32), separating the harmful by-product from the main product without requiring expensive ozonation equipment. This extraction approach achieves the same quality improvement through a simpler, more cost-effective separation process.
Solution Approach 2:
The invention changes the operational parameters of the dehydration column, specifically setting the reflux ratio to not less than 0.32, to optimize crotonaldehyde removal efficiency. By adjusting this parameter, the system achieves effective separation and improved potassium permnymate test value without requiring additional expensive equipment.
2Manufacturing precision
If conventional methods (acetaldehyde removal and ozonation) are used to control crotonaldehyde, then the potassium permanganate test value is improved, but the process complexity and equipment investment increase
Solution Approach 1:
The invention combines the dehydration function with crotonaldehyde removal in a single dehydration column, merging two functions that would traditionally require separate equipment. By operating this column at a reflux ratio of not less than 0.32, it simultaneously removes water and crotonaldehyde, simplifying the overall process while maintaining product quality.
Solution Approach 2:
The invention converts the harmful presence of crotonaldehyde into a manageable separation challenge that can be addressed through optimized distillation. Instead of using complex ozonation processes, the system uses the dehydration column's separation capability, turning a quality problem into a solvable separation task with controlled operational parameters.
3Quantity of substance
If acetaldehyde is separated and removed from methyl iodide to suppress crotonaldehyde production, then crotonaldehyde concentration decreases, but separation and removal equipment cost increases
Solution Approach 1:
The invention performs preliminary dehydration and crotonaldehyde removal in the dehydration column before the acetic acid stream proceeds to subsequent processing. By setting the reflux ratio to not less than 0.32, the system proactively removes crotonaldehyde early in the process, preventing its accumulation and eliminating the need for downstream acetaldehyde removal equipment.
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 enables the production of acetic acid with improved potassium permanganate test values while reducing equipment costs, as the crotonaldehyde concentration is effectively managed within the process, eliminating the need for costly separation and removal equipment.
Implementation Method 1
a dehydration column to not less than a specific value
Implementation Method 2
The reaction mixture is evaporated in an evaporator, and the vapor phase is purified
Data Source
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AI summary
It is intended to provide a method capable of industrially and efficiently producing acetic acid having a good potassium permanganate test value without a large cost. A method for producing acetic acid according to the present invention is a method for producing acetic acid comprising: a carbonylation reaction step; an evaporation step; a lower boiling point component removal step; and a first overhead stream recycle step of recycling at least a portion of an aqueous phase and/or an organic phase obtained by condensing a first overhead stream obtained in the lower boiling point component removal step to a reaction vessel, wherein a crotonaldehyde concentration in a first acetic acid stream obtained in the lower boiling point component removal step is controlled to not more than 2.2 ppm by mass. The catalyst system may further contain an ionic iodide. The method for producing acetic acid may further comprise an acetaldehyde separation and removal step of distilling at least a portion of the aqueous phase and/or the organic-phase obtained by condensing the first overhead stream to separate and remove acetaldehyde.