Integrated Rectifying Stripping Column for Propylene Recovery
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Solution Overview
Problem
Propane dehydrogenation processes for producing olefins like propylene require significant energy input, leading to high costs and operational inefficiencies due to the need for multiple distillation columns and energy-intensive processing steps.
Innovation Solution
A fractionation system with a single vessel housing a rectifying column and a stripping column of uniform diameter, where the rectifying column is positioned above the stripping column, and both columns share a side-by-side stacked arrangement of fractionation trays, allowing for efficient heat recovery and reduced energy consumption by utilizing a heat pump compressor's excess heat to reheat streams and optimize reflux and reboiling processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple distillation columns are used for fractionation, then separation efficiency is improved, but capital cost and device complexity increase
Solution Approach 1:
The patent combines a rectifying column and a stripping column into a single integrated distillation column. The column includes a rectifying section with trays above the feed inlet and a stripping section with trays below the feed inlet, both within the same vessel. This merging reduces capital cost and device complexity while maintaining separation efficiency through the unified design that allows continuous counter-current contact between vapor and liquid phases throughout the entire column height.
2Manufacturing precision
If multiple distillation columns are used for fractionation, then separation efficiency is improved, but operating cost and energy consumption increase
Solution Approach 1:
The integrated column combines rectifying and stripping sections in one vessel, allowing heat integration between the two sections. The reboiler at the bottom of the column provides vapor that rises through both the stripping section and rectifying section, while liquid flows downward through both sections. This configuration reduces energy consumption by eliminating the need for separate reboilers and condensers that would be required for multiple independent columns, while maintaining effective separation through continuous mass and heat transfer throughout the column.
3Device complexity
If a single vessel houses both columns, then capital cost and device complexity are reduced, but vapor-liquid contact efficiency may worsen
Solution Approach 1:
The single column is segmented into distinct functional sections: a rectifying section with multiple trays above the feed inlet and a stripping section with multiple trays below the feed inlet. Each section is optimized for its specific function - the rectifying section for enriching overhead product and the stripping section for removing light components from bottoms. The segmentation is achieved through strategic placement of feed inlets and product outlets at different heights, creating independent mass transfer zones within the unified column structure that maintain high vapor-liquid contact efficiency in each section.
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 configuration reduces capital and operating costs, simplifies control and operation, and achieves high recovery rates of propylene while minimizing unreacted propane recycle and energy consumption, thereby enhancing the overall efficiency and cost-effectiveness of the dehydrogenation process.
Implementation Method 1
a rectifying column having a feed inlet between a top and a bottom plate, a reflux inlet at the top plate, a fluid inlet at the bottom plate, an overhead product outlet at the first plate, and a bottoms outlet at the bottom plate
Implementation Method 2
at least a portion of the bottoms stream from the rectifying column is reheating reheated in a rectifying column reboiler, and at least a portion of the bottoms stream from the stripping column is reheated in a stripping column reboiler
Implementation Method 3
a reflux inlet at the top plate
Data Source
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AI summary
Fractionation systems utilizing a single rectifying column with a stripping column housed in the same vessel and having a uniform diameter are described. The fractionation system includes a rectifying column and a stripping column. The rectifying column and the stripping column are in a single vessel having a uniform diameter, and the rectifying column is positioned above the stripping column. Methods of separating feed streams using the fractionation systems are also described.