Heavy Ends Column Draw-Off for Acetic Acid Water Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for manufacturing acetic acid struggle with the inability to effectively remove water from the product acetic acid, leading to quality deterioration due to increased water content, especially when alkaline agents are used to prevent corrosion in the heavy ends column.
Innovation Solution
A method involving a flash evaporation step followed by a light ends column and a heavy ends column for purifying the reaction product, where product acetic acid is drawn from an intermediate stage of the heavy ends column to control water content, and the bottoms liquid surface level is maintained by adjusting the amount drawn out from this stage in response to changes in the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If product acetic acid is drawn out from the column top of the heavy ends column, then the distillation process is simple, but the water content of the product acetic acid cannot be adjusted and quality deteriorates
Solution Approach 1:
The patent divides the heavy ends column into multiple drawing stages: an intermediate drawing stage for drawing out product acetic acid with controlled water content, and a column top drawing stage for removing water-rich streams. This segmentation allows independent control of product quality while maintaining process simplicity.
Solution Approach 2:
The patent extracts water from the product acetic acid stream by drawing out the acetic acid at an intermediate stage rather than from the column top, where water content is lower. This extraction approach enables precise control of the product's water content while the column top continues to handle water removal.
2Reliability
If aqueous alkaline agent is added to prevent corrosion in heavy ends column, then corrosion is prevented, but water content of product acetic acid increases and quality deteriorates
Solution Approach 1:
The patent segments the drawing process into intermediate stage (for product acetic acid with controlled water content) and column top (for water removal). This allows the system to tolerate the presence of aqueous alkaline agents for corrosion prevention while still achieving acceptable product quality through the intermediate drawing stage.
Solution Approach 2:
The intermediate drawing stage acts as an intermediary between the corrosion protection function (aqueous alkaline agent addition) and the product quality requirement. It allows water and impurities to be removed while maintaining product acetic acid quality, effectively mediating between these conflicting requirements.
3Reliability
If water content in crude acetic acid increases due to operation changes or alkaline agent addition, then corrosion is prevented, but product acetic acid quality deteriorates
Solution Approach 1:
The patent implements feedback control by monitoring the water content and composition in the heavy ends column and adjusting the drawing rates at the intermediate stage and column top accordingly. This feedback mechanism allows the system to maintain product quality despite variations in crude acetic acid water content caused by operation changes or alkaline agent addition.
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 stabilizes the water content of the product acetic acid, maintaining its quality and ensuring continuous operation by controlling the liquid surface level in the heavy ends column, reducing fluctuations and enhancing the efficiency of the purification process.
Implementation Method 1
a flash evaporation step of introducing the reaction product into a flasher vessel and vaporizing a part thereof to thereby separate the reaction product into a vapor-phase mixture containing acetic acid and low-boiling point components lower in boiling point than acetic acid, and a liquid-phase mixture containing acetic acid and a high-boiling point component higher in boiling point than acetic acid
Implementation Method 2
a first distillation step of introducing the vapor-phase mixture into a light ends column consistig of at least one column and distilling the vapor-phase mixture to thereby separate and remove at least a part of the low-boiling point components from the vapor-phase mixture and obtain crude acetic acid
Implementation Method 3
a second distillation step of introducing the crude acetic acid into a heavy ends column and distilling the crude acetic acid to thereby further purify the crude acetic acid and obtain product acetic acid
Data Source
AI summary
Acetic acid is manufactured by a method of carbonylating raw material with carbon monoxide, the method comprising: a reaction step of forming a reaction mixture containing acetic acid inside a reactor; and a purification step of purifying the reaction mixture to thereby obtain product acetic acid. The purification step includes: a flash evaporation step of separating the reaction mixture into a vapor-phase mixture and a liquid-phase mixture; a first distillation step of distilling the vapor-phase mixture to thereby separate and remove low-boiling point components and obtain crude acetic acid; and a second distillation step of introducing the crude acetic acid into a heavy ends column and distilling the crude acetic acid to thereby purify the crude acetic acid and obtain product acetic acid. In the second distillation step, the low-boiling point components remaining in the crude acetic acid are drawn out from a column top of the heavy ends column.