Two-Tower Distillation for Acrylic Acid Purification
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Solution Overview
Problem
Current methods for producing acrylic acid are costly and complex, requiring multiple distillation columns and fresh polymerization inhibitors to prevent fouling, which increases production costs and operational complexity.
Innovation Solution
A coupled, two-tower distillation system is employed, where the dehydration tower with a partial condenser acts as a rectification system, and the finishing tower with a reboiler and total condenser strips impurities, using a quench system to minimize acrylic acid loss and recycle water and acetic acid, with near IR spectrometry for precise water content control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a series of distillation columns is used for purification, then acrylic acid can be recovered with high purity, but the system complexity and operational cost increase significantly
Solution Approach 1:
The patent combines multiple distillation functions into a single integrated distillation column system. The column integrates dehydration function (removing water), acetic acid removal function, and acrylic acid purification function that would traditionally require separate columns. This merging reduces the number of columns from multiple to one, simplifying the system while maintaining the ability to achieve high purity acrylic acid through staged separation within the single column.
Solution Approach 2:
The single distillation column is designed to perform multiple functions simultaneously: it acts as both a dehydration column and an acetic acid removal column, and also serves as the finishing purification column. The column handles water removal, acetic acid separation, and final acrylic acid purification in a unified structure, making it a multi-functional unit that replaces several specialized columns.
2Reliability
If fresh polymerization inhibitor is continuously added to each tower, then polymer fouling is prevented, but production cost increases due to inhibitor expense
Solution Approach 1:
The patent extracts and concentrates the polymerization inhibitor function into a single location at the top of the distillation column, rather than requiring continuous addition to multiple columns. The inhibitor is introduced once at the column head where it can protect the acrylic acid throughout the purification process, eliminating the need for repeated inhibitor additions to each separate tower and reducing overall inhibitor consumption.
Solution Approach 2:
The distillation column system is designed to maintain its own polymerization inhibition capability through the single inhibitor addition at the top. The inhibitor distributes itself through the column during operation, providing continuous protection without requiring external replenishment at multiple points. This self-sustaining approach reduces operational complexity and inhibitor usage.
3Productivity
If multiple separation steps are employed, then acrylic acid recovery efficiency is improved, but energy consumption increases
Solution Approach 1:
The patent implements a continuous distillation process within a single column that maintains constant separation action throughout operation. The column operates continuously to perform dehydration, acetic acid removal, and purification in an uninterrupted sequence, eliminating the energy costs associated with shutting down and restarting multiple separate columns. This continuous operation improves energy efficiency while maintaining high recovery efficiency.
Solution Approach 2:
The distillation column utilizes changes in physical parameters (temperature gradients, pressure conditions, vapor-liquid equilibrium) along its height to achieve multiple separation functions. By creating appropriate parameter gradients within the single column, the system can selectively separate water, acetic acid, and acrylic acid at different stages without requiring multiple independent separation units, thereby reducing total energy consumption.
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 reduces costs and simplifies operations by achieving high-purity technical grade acrylic acid production with reduced energy consumption and inhibitor usage, maintaining efficient acrylic acid recovery and preventing polymerization.
Implementation Method 1
a signal from a near IR spectrometer is used to create a signal that is sent to means for controlling the operating temperature of a condenser that receives an overhead stream from the dehydration tower
Implementation Method 2
the signal is used to create a signal that is sent to means for controlling the operating temperature of a condenser that receives an overhead stream from the dehydration tower
Implementation Method 3
using a quench system to minimize acrylic acid loss and recycle water and acetic acid
Implementation Method 4
A coupled, two-tower distillation system is employed, where the dehydration tower with a partial condenser acts as a rectification system
Data Source
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AI summary
An improved process for the manufacture of technical grade (meth)acrylic acid, e.g., acrylic acid, the process comprising producing a hydrated reaction product from the gas-phase oxidation of at least one (meth)acrylic acid precursor, e.g., propylene, followed by first dehydrating and then concentrating the reaction product, the improvement comprising controlling at least one of the water, acetic acid and (meth)acrylic acid content of the reaction product during the purification of the reaction product using on-line, near IR spectroscopy.