Dividing Wall Column for Acrylate Distillation
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Solution Overview
Problem
The existing distillation processes for isolating pure 2-ethylhexyl acrylate and 2-propylheptyl acrylate from crude acrylate mixtures are inefficient, requiring two-column arrangements and high energy and capital costs due to the small differences in relative volatilities of the components, and are prone to fouling from polymerization-prone mixtures.
Innovation Solution
A single dividing wall column with separation-active internals and a vaporizer is used, where the dividing wall divides the column into upper and lower joint regions, allowing for a side feed and side takeoff, and employing dual-flow trays and precise gas distribution to reduce fouling and energy consumption, enabling efficient separation at uniform pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a two-column distillation arrangement is used to separate crude acrylate into pure acrylate, then the separation purity is improved, but the device complexity and capital costs increase
Solution Approach 1:
The patent combines two separate distillation columns into a single dividing wall column, where the dividing wall creates two distinct separation zones within one column structure. This merging maintains the separation purity of two columns while reducing device complexity and capital costs by eliminating redundant equipment such as additional condensers, reboilers, and support structures.
Solution Approach 2:
The dividing wall column is segmented into two functional sections by a vertical dividing wall: a first section for separating low boilers and a second section for separating high boilers. Each section has its own feed point, side offtake point, and separation-active internals, allowing independent optimization of separation conditions while operating within a single integrated column structure.
2Productivity
If a two-column distillation arrangement is used for acrylate purification, then the separation efficiency is improved, but the energy consumption increases
Solution Approach 1:
By merging two distillation processes into a single dividing wall column, the patent enables thermal integration where the vapor and liquid streams from different sections can exchange heat internally. This reduces the total energy input required compared to two separate columns, as the condensation heat from one section can be utilized for vaporization in another section, while maintaining high separation efficiency.
Solution Approach 2:
The dividing wall column enables continuous operation with both separation sections functioning simultaneously and continuously. The integrated design allows for continuous heat and mass transfer between sections, eliminating the energy losses associated with startup/shutdown cycles and heat transfer inefficiencies that would occur in two separate batch or semi-continuous operations.
3Manufacturing precision
If conventional distillation columns are used for acrylate separation, then the separation is achieved, but fouling from polymerization reduces operation duration
Solution Approach 1:
The patent applies local quality by positioning separation-active internals at specific locations within each section of the dividing wall column, and by optimizing the local flow conditions around the dividing wall. This creates zones of enhanced mass transfer and reduced residence time in high-temperature regions, minimizing polymerization fouling while maintaining effective separation. The side feed and side offtake points are strategically positioned to avoid dead zones where fouling could accumulate.
Solution Approach 2:
The dividing wall column design accelerates the passage of acrylate through the separation zones by creating high-velocity vapor and liquid flows. The polymerization-prone acrylate is rapidly transported through the column without prolonged exposure to conditions that would promote polymerization, thereby reducing fouling and extending operation duration while achieving the required separation.
4Manufacturing precision
If the side feed and side offtake points are positioned optimally in the dividing wall column, then the separation performance is improved, but the device complexity increases
Solution Approach 1:
The dividing wall structure serves multiple functions simultaneously: it acts as a physical separator between the two sections, provides support for separation-active internals, facilitates heat and mass transfer between sections, and guides the vapor and liquid flows. The side feed and side offtake points are integrated into this multi-functional structure, adding separation performance capabilities without requiring additional separate components, thus avoiding increased device complexity.
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 process achieves high purity of 2-ethylhexyl acrylate or 2-propylheptyl acrylate with reduced capital and energy costs, extending column operation time, and adhering to specifications while minimizing fouling and polymerization risks.
Implementation Method 1
The isolation of acrylate from the crude acrylate is a complicated distillation problem because of the small differences in the relative volatilities of the components
Implementation Method 2
a vaporizer (7) and in which a dividing wall (8) is arranged
Data Source
AI summary
Process for isolating pure 2-ethylhexyl acrylate or pure 2-propylheptyl acrylate from the corresponding crude alkyl acrylate by distillation, wherein the process is carried out in a dividing wall column (1) which has separation-active internals and vaporizer (7) and in which a dividing wall (8) is arranged in the longitudinal direction of the column to form an upper joint column region (9), a lower joint column region (14), an inflow section (10, 12) having a side feed point (2) and an offtake section (11, 13) having a side offtake point (3), the column has a number of theoretical plates in the range from 10 to 60, where the number of theoretical plates of the dividing wall column (1) relates to the sum of the theoretical plates in the joint upper column region (9), the joint lower column region (14) and the inflow section (10, 12), the side feed point (2) for the corresponding crude alkyl acrylate is arranged at a theoretical plate in the region commencing at least two theoretical plates above the bottommost theoretical plate and ending at least two theoretical plates below the uppermost theoretical plate, the side offtake point (3) for the pure 2-ethylhexyl acrylate or pure 2-propylheptyl acrylate is arranged at a theoretical plate in the region commencing at least two theoretical plates above the bottommost theoretical plate and ending at least two theoretical plates below the uppermost theoretical plate and the dividing wall (8) is arranged in the column in the region commencing at least one theoretical plate above the bottommost theoretical plate and ending at least one theoretical plate below the uppermost theoretical plate, where the ratio of amount of liquid at the upper end of the dividing wall (8) going to the enrichment section (10) and the stripping section (11) of the column is set in the range from 1:0.2 to 1:5.