Acetic Acid Production Distillation Reflux Optimization
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Solution Overview
Problem
Current acetic acid production methods via methanol carbonylation face challenges in achieving high-quality acetic acid with good potassium permanganate test results due to by-products like acetaldehyde and crotonaldehyde, which require expensive separation and treatment facilities, and result in increased energy costs and corrosion issues.
Innovation Solution
A method involving a higher reflux ratio in the light ends column to concentrate crotonaldehyde, recycle it to the reactor, and convert it into less harmful by-products, while selectively treating either the aqueous or organic phase based on acetaldehyde partition coefficients to optimize separation efficiency and reduce facility costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional techniques (acetaldehyde-removing facilities and ozone treatment) are used to remove acetaldehyde and crotonaldehyde, then the potassium permanganate test result is improved, but the installation cost and facility expense increase
Solution Approach 1:
The invention extracts and removes crotonaldehyde specifically from the reaction mixture through a distillation column, separating it from acetaldehyde and other components. This targeted extraction eliminates the need for complex ozone treatment facilities while achieving the required potassium permanganate test results.
Solution Approach 2:
The invention changes the operational parameters of the distillation process, specifically controlling the reflux ratio and temperature conditions to optimize crotonaldehyde removal. By adjusting these parameters, the system achieves effective separation without requiring additional expensive treatment facilities.
2Reliability
If acetaldehyde is removed through liquid-liquid separation and distillation, then the potassium permanganate test result is improved, but the energy consumption increases
Solution Approach 1:
The invention performs preliminary separation of crotonaldehyde in the distillation column before final product formation. By removing crotonaldehyde early in the process through controlled distillation, subsequent energy-intensive treatment steps are minimized, reducing overall energy consumption.
3Reliability
If crotonaldehyde is directly decomposed oxidatively with ozone, then the potassium permanganate test result is improved, but the installation cost and corrosion issues increase
Solution Approach 1:
Instead of using ozone to decompose crotonaldehyde, the invention allows crotonaldehyde to undergo aldol condensation reactions to form 2-ethylcrotonaldehyde and other products that are easier to separate and less harmful. This converts the harmful crotonaldehyde into less problematic substances through controlled chemical reactions, avoiding the need for corrosive ozone treatment.
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 efficient production of high-quality acetic acid with improved potassium permanganate test results, reducing the need for large-scale acetaldehyde-removing facilities and ozone treatment, and minimizing energy and corrosion-related expenses.
Implementation Method 1
the resulting reaction mixture is separated, using an evaporator, into a vapor phase including acetic acid and light ends, and a residual liquid phase (residue phase) including acetic acid and the catalyst
Implementation Method 2
the vapor phase is subjected to distillation in a distillation column (light ends column) to be separated into an overhead stream including light ends, and an acetic acid stream
Implementation Method 3
liquid-liquid separating a condensate into an aqueous phase and an organic phase using a decanter
Implementation Method 4
subjecting, of the two phases, the aqueous phase to distillation in an acetaldehyde-removing column
Implementation Method 5
crotonaldehyde is directly decomposed oxidatively with ozone
Data Source
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AI summary
Provided is a method that can industrially efficiently produce acetic acid yielding a good potassium permanganate test result, without costing much. The method includes an acetaldehyde-removing step by which by-produced acetaldehyde is industrially advantageously removed. The method also includes the step of subjecting at least one of an aqueous phase and an organic phase of a light ends column overhead condensate to distillation in a crotonaldehyde-removing column. The light ends column is operated at a reflux ratio of 2 or more (when the aqueous phase is refluxed). The crotonaldehyde-removing column is operated so as to meet at least one of conditions (a-i) to (a-iii) as follows: (a-i) a reflux ratio at the distillation column is 0.01 or more; (a-ii) at the distillation column, the ratio of a crotonaldehyde concentration (ppm by mass) in a distillate to a crotonaldehyde concentration (ppm by mass) in a charge liquid is less than 1; and (a-iii) at the distillation column, the ratio of a crotonaldehyde concentration (ppm by mass) in bottoms to a crotonaldehyde concentration (ppm by mass) in the charge liquid is greater than 1.