Propylene Separation via Dividing Wall Column and Membrane Integration
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Solution Overview
Problem
The existing membrane technology cannot eliminate the need for a C3/C4 splitter column, as it cannot perform carbon number separation, leading to increased costs and complexity in producing polymer grade propylene.
Innovation Solution
A process involving a combined C3/C4 splitter with a membrane system, where a feed stream is passed through a column to produce overhead and product streams, with portions recycled and treated, and the permeate stream from a membrane unit is used to produce polymer grade propylene, utilizing facilitated transport membranes with nanoporous support membranes and hydrophilic polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional C3 splitter with over 120 equilibrium trays is used, then high-purity propylene can be produced, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent combines a C3/C4 splitter column with a membrane separation unit into an integrated system. The membrane unit is positioned to receive overhead stream from the splitter, and the retentate stream is recycled back to the column. This merging of conventional distillation with membrane technology achieves high-purity propylene separation while dramatically reducing the number of equilibrium trays needed in the column.
2Productivity
If membrane technology is integrated around the C3 splitter, then propylene production efficiency improves, but the device complexity and overall cost increase
Solution Approach 1:
The patent extracts the C3 splitting function from a complex multi-column system and concentrates it into a single C3/C4 splitter column operated at optimized pressure (10-50 psig). By taking out and simplifying the splitting function, the overhead stream is enriched in propylene and sent to the membrane unit, reducing the overall system complexity while maintaining high productivity.
3Ease of manufacture
If the C3/C4 splitter is eliminated, then equipment cost decreases, but carbon number separation capability is lost
Solution Approach 1:
The patent changes the operating pressure parameter of the C3/C4 splitter to 10-50 psig, which is lower than conventional operating pressures. This parameter change optimizes the separation efficiency and allows the membrane unit to operate more effectively. The pressure optimization enables the system to achieve both cost reduction and maintained separation capability.
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 minimizes the membrane section and overall cost, enabling the production of high-purity propylene while reducing the number of equilibrium trays and equipment required, thereby enhancing separation efficiency and reducing operational pressures.
Implementation Method 1
passing the treated stream to a membrane unit; passing a retentate stream from the membrane unit back to the stripper and passing a permeate stream from the membrane unit to produce a polymer grade propylene stream
Implementation Method 2
utilizing facilitated transport membranes with nanoporous support membranes and hydrophilic polymers
Data Source
AI summary
Process for separating a highly pure propylene product from a liquefied petroleum gas stream is disclosed, which eliminates a C3 splitter having over 120 trays and the additional equipment that a C3 splitter requires. The process includes passing a feed stream to a dividing wall column to produce an overhead stream, a first side draw stream, a second side draw stream, and a product stream. The first side draw stream is passed to a treatment unit to produce a treated stream. The treated stream is passed to a membrane unit and a permeate stream is passed from the membrane unit to produce a polymer grade propylene stream.