Dividing Wall Column Reflux Phase Splitting
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Solution Overview
Problem
Conventional phenol fractionation processes using multiple columns result in high capital and operating costs, inefficient recovery of acetone, and increased processing needs due to excessive acetone in streams, necessitating a more economical and simplified design for phenol and acetone yield improvement.
Innovation Solution
A dividing wall column system that separates and controls the flow of two liquid phases in the reflux stream above the dividing wall, directing one phase entirely to the product side and splitting the other phase to both sides, ensuring optimal reflux distribution and reducing fouling and distillation performance issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single dividing wall column is used instead of multiple columns, then capital equipment costs and operating costs are reduced, but the recovery of acetone to overhead steam becomes inefficient and excessive acetone remains in streams requiring additional processing
Solution Approach 1:
The single dividing wall column is segmented into two distinct sections separated by a dividing wall: a feed side section and a product side section. This segmentation allows independent optimization of acetone recovery on the feed side while maintaining phenol purification on the product side, resolving the contradiction between simplified structure and effective acetone separation.
Solution Approach 2:
Different operational conditions are applied to different sections of the column. The feed side section operates with conditions optimized for acetone recovery to overhead steam, while the product side section maintains conditions for phenol purification. This local differentiation of operational parameters enables simultaneous achievement of both simplified structure and effective acetone recovery.
2Loss of substance
If excessive acetone is present in net side draw aqueous and organic streams, then additional processing is required to remove acetone, but implementing such additional processing increases capital and operating costs
Solution Approach 1:
Acetone recovery is performed preliminarily within the dividing wall column itself through the feed side section, which is designed to efficiently strip acetone from the feed stream and deliver it to overhead steam. This preliminary recovery action prevents excessive acetone from entering downstream streams, eliminating the need for additional acetone removal processing equipment.
3Ease of operation
If two liquid phases form in the reflux stream above the dividing wall, then reflux must be apportioned to both sides, but splitting the reflux stream creates problems including potential disappearance of aqueous phase and fouling
Solution Approach 1:
A decanter is introduced as an intermediary device positioned above the dividing wall to receive and separate the two liquid phases from the reflux stream. The decanter mediates the reflux distribution by providing a controlled interface where aqueous and organic phases are separated and then distributed to appropriate sides of the dividing wall, preventing phase disappearance and fouling while enabling reliable operation.
4Reliability
If the aqueous phase reflux is directed to the feed side, then aqueous phase may disappear causing increased formic acid concentration and corrosion, but directing to product side maintains stability
Solution Approach 1:
The decanter serves as an intermediary that controls the direction of aqueous phase reflux. By separating and directing the aqueous phase to the product side of the dividing wall rather than the feed side, the decanter prevents the aqueous phase from disappearing and avoids the formation of highly concentrated formic acid, thereby eliminating corrosion hazards while maintaining phase stability.
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, enhances phenol and acetone recovery, and minimizes fouling by maintaining a stable reflux composition, thereby improving the overall efficiency of the phenol fractionation process.
Implementation Method 1
the liquid reflux immediately above a dividing wall forms or could form two liquid phases
Implementation Method 2
a fractionation technology that is used to create crude acetone and crude phenol streams using a dividing wall column intended to remove cumene, alpha-methyl styrene and water from the product side of the wall
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to the fractionation technology that is used to create purified phenol and acetone products. More specifically, the present invention relates to a fractionation technology that is used to create crude acetone and crude phenol streams using a dividing wall column intended to remove cumene, alpha-methyl styrene and water from the product side of the wall.