Acrylic Acid Purification via Dividing Wall Column Side Offtake
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Solution Overview
Problem
Current processes for purifying acrylic acid from compositions containing it and accompanying products, such as acetic acid and aldehydes, require multiple distillation columns, leading to high costs and energy consumption, with existing methods inadequately addressing the removal of high-boiling products.
Innovation Solution
A process involving fractional distillation in a single distillation column with a side takeoff, where high-boiling constituents are removed from the bottom and low-boiling constituents from the top, using an entrainer to form a heterogeneous minimum azeotrope and recirculate the entrainer, while the acrylic acid is taken off from the side takeoff, either in liquid or gaseous form, utilizing a dividing wall column configuration to enhance separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple distillation columns are used to purify acrylic acid, then the removal of low- and high-boiling accompanying products is improved, but the device complexity and operating costs increase
Solution Approach 1:
The patent combines the functions of multiple distillation columns into a single distillation column with a side offtake. The column simultaneously performs removal of low-boiling products (from the top), high-boiling products (from the bottom), and purified acrylic acid collection (from the side offtake), thereby reducing the number of columns from three to one while maintaining purification effectiveness
Solution Approach 2:
The patent introduces a side offtake as an additional dimension for product removal. Instead of using sequential columns, the side offtake provides a lateral extraction point that enables simultaneous separation of the main product (acrylic acid) from both low-boiling and high-boiling impurities within a single column structure
2Manufacturing precision
If multiple distillation columns are used, then the removal of accompanying products is improved, but the energy consumption increases
Solution Approach 1:
By merging multiple distillation operations into a single column with side offtake, the patent eliminates redundant heating and cooling cycles that would occur in sequential columns. The single column performs all separations simultaneously, reducing total energy input required for vaporization and condensation operations
3Manufacturing precision
If multiple distillation columns are used, then the removal of accompanying products is improved, but the inhibitor consumption increases
Solution Approach 1:
The patent reduces the number of distillation steps from three to one, thereby reducing the number of times inhibitor must be added to prevent polymerization. With fewer columns, the acrylic acid stream undergoes fewer thermal processing stages, reducing cumulative inhibitor consumption while still achieving complete removal of impurities
4Manufacturing precision
If more distillation columns are used, then the removal of high-boiling products is improved, but the polymerization of acrylic acid increases
Solution Approach 1:
The side offtake configuration allows acrylic acid to be rapidly extracted from the distillation column at an intermediate point, minimizing its residence time in the high-temperature zone. This quick extraction reduces the opportunity for polymerization reactions while still enabling complete removal of high-boiling products through the bottom outlet
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 capital and operating costs, minimizes polymerization of acrylic acid, and achieves high product purity with fewer process steps and lower thermal stress, thereby increasing yield and simplifying column maintenance.
Implementation Method 1
an entrainer which forms a heterogeneous minimum azeotrope with the water of the liquid solution is added to the liquid solution
Implementation Method 2
the liquid solution is separated by distillation into an overhead product containing the minimum azeotrope and a bottom product containing acrylic acid and accompanying product
Implementation Method 3
the fractional distillation of the bottom product is carried out in a distillation column which has a side offtake and from the bottom of which high-boiling constituents of the accompanying product are taken off, from the top of which low-boiling constituents of the accompanying product are taken off and from the side offtake of which the acrylic acid is taken off
Data Source
AI summary
The present process separates acrylic acid from a composition containing acrylic acid and at least one accompanying product. The process first involves contacting the composition with an aqueous liquid stream to give a liquid solution of acrylic acid, accompanying product, and water. The water then forms an azeotrope with an entrainer, which is added to the solution. Distillation then separates the solution into an overhead product containing the azeotrope and a bottom product containing acrylic acid and accompanying product. The overhead product is separated into water and entrainer and the bottom product is separated in a distillation column into acrylic acid and accompanying product. The process provides a way to remove high- and low-boiling products with a small number of distillation columns.