Multistage Separation of Unsaturated Carboxylic Acid
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Solution Overview
Problem
The commercial production of acrylic acid via aldol condensation of formaldehyde and acetic acid faces challenges due to low selectivity and high energy requirements in separation processes, particularly in separating unsaturated carboxylic acid from crude product streams containing saturated carboxylic acid, water, and heavy by-products, which are not efficiently addressed by existing methods.
Innovation Solution
A multistage separation process where water is carried from a first separation column to a second column, utilizing the strong interaction between saturated and unsaturated carboxylic acids to reduce column duties and enhance separation efficiency, with specific operating conditions and the use of entrainers to facilitate separation and reduce polymerization risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional separation methods are used to separate unsaturated carboxylic acid from crude product stream, then separation can be achieved, but energy input is high and separation efficiency is low
Solution Approach 1:
The separation process is divided into multiple stages: first stage separates unsaturated carboxylic acid from saturated carboxylic acid using a first separation column, second stage removes water and heavy by-products using a second separation column. This segmentation allows each stage to be optimized independently, reducing overall energy input while maintaining high separation efficiency.
Solution Approach 2:
Water is carried as an intermediary from the first separation column to the second separation column. The strong interaction between saturated carboxylic acid and water acts as a mediator to enhance separation efficiency in the second stage, reducing the energy required for complete separation while improving productivity.
2Manufacturing precision
If high purity unsaturated carboxylic acid is achieved through conventional separation, then product quality is improved, but energy consumption increases
Solution Approach 1:
The purification process is segmented into two distinct stages: first stage achieves partial purification by separating unsaturated from saturated carboxylic acid, second stage completes purification by removing water and heavy by-products. This segmentation enables high purity product with reduced overall energy consumption compared to single-stage conventional methods.
Solution Approach 2:
Water serves as an intermediary substance that is deliberately carried between separation stages. The strong interaction between water and saturated carboxylic acid enhances the separation efficiency in the second stage, enabling high purity product recovery with lower energy consumption by leveraging this natural interaction.
3Ease of operation
If separation process is simplified to reduce complexity, then operational ease is improved, but separation efficiency decreases
Solution Approach 1:
The separation process is segmented into two well-defined stages with distinct functions: first stage handles the bulk separation of unsaturated from saturated carboxylic acid, second stage handles water and heavy by-product removal. This segmentation maintains operational simplicity while achieving high separation efficiency through systematic division of tasks.
Solution Approach 2:
Water is used as an intermediary that simplifies the separation process by leveraging its strong interaction with saturated carboxylic acid. This natural interaction reduces the need for complex separation mechanisms, making the process easier to operate while maintaining high separation efficiency in the second stage.
4Device complexity
If conventional single-stage separation is used, then device complexity is reduced, but manufacturing precision and separation efficiency both deteriorate
Solution Approach 1:
The separation process is segmented into two specialized stages: first stage focuses on separating unsaturated from saturated carboxylic acid, second stage focuses on removing water and heavy by-products. This segmentation improves manufacturing precision and separation efficiency while keeping device complexity manageable through functional specialization.
Solution Approach 2:
Water acts as an intermediary that enhances separation efficiency in the second stage through its strong interaction with saturated carboxylic acid. This natural mediator enables high precision separation without requiring excessively complex equipment, as the water-carboxylic acid interaction provides the separation mechanism.
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 significantly reduces energy input by up to 10% on a feed mass basis and achieves high purity of unsaturated carboxylic acid, suitable for crystallization, while also addressing the issue of heavy by-products and polymerization, thereby improving the economic viability of the process.
Implementation Method 1
a first separation column operated at a temperature and pressure to form an intermediate product stream comprising product unsaturated carboxylic acid, a portion of the water from the feed stream, a portion of the saturated carboxylic acid and heavy by-products where present
Implementation Method 2
utilizing the strong interaction between saturated and unsaturated carboxylic acids to reduce column duties and enhance separation efficiency
Data Source
AI summary
A process for purification of a crude product stream recovered from the production of an unsaturated carboxylic acid by an aldolization reaction is disclosed. The product stream comprises the unsaturated carboxylic acid, aldehyde, saturated carboxylic acid, water, non-condensable vapours and optionally heavy by-products. The process comprises: providing the crude product stream in the vapour phase to a first separation column operated at a temperature and pressure to form an intermediate product stream comprising product unsaturated carboxylic acid, a portion of the water from the feed stream, a portion of the saturated carboxylic acid and heavy by-products where present; and passing the intermediate product stream to a second separation column operated at a temperature and pressure such that the unsaturated carboxylic acid product is separated and recovered.