Annular Divided Wall Column With Independent Thermal Expansion
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Solution Overview
Problem
Existing annular divided wall columns for cryogenic rectification of air face challenges such as maldistribution of vapor and liquids, lower performance due to thermal expansion/contraction differences, and inadequate pressure boundaries, leading to increased capital costs and space requirements.
Innovation Solution
The design incorporates a conical transition wall to isolate the annulus and core column regions, allowing independent thermal expansion and contraction, and uses structured packing elements with varying surface area densities and geometries in both regions, along with specialized collectors and distributors to enhance vapor and liquid distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a divided-wall column is used to reduce column cost and space requirements, then capital cost and space are reduced, but maldistribution of vapor and liquids occurs due to large wall surface areas
Solution Approach 1:
The column is segmented into multiple independent thermal zones using divided walls with gaps, allowing each section to be optimized independently for vapor and liquid distribution while maintaining overall column integration
Solution Approach 2:
Collection bridges and distribution bridges are introduced as intermediary structures to facilitate uniform vapor and liquid distribution across the divided sections, compensating for the potential maldistribution caused by wall segmentation
2Productivity
If an inner annular wall is added to create divided sections, then separation efficiency is improved, but thermal expansion and contraction differences cause performance degradation
Solution Approach 1:
The column structure is divided into separate thermal zones with independent walls that can expand and contract independently, preventing thermal stress accumulation and performance degradation
Solution Approach 2:
The design accommodates thermal phase transitions through expansion gaps and flexible connections between divided sections, allowing each section to respond independently to temperature changes while maintaining overall structural integrity
3Productivity
If structured packing is used to enhance mass transfer, then separation performance is improved, but liquid maldistribution increases due to large wall surface areas
Solution Approach 1:
Distribution bridges and collection bridges are used as intermediary structures to ensure uniform liquid distribution across the structured packing, compensating for the maldistribution tendency caused by large wall surface areas in divided-column configurations
Solution Approach 2:
The packing and distribution structures are locally optimized in different column sections to account for varying flow patterns and thermal conditions, ensuring uniform liquid distribution despite the presence of divided walls
4Productivity
If multiple columns are used for air separation, then separation capacity is increased, but capital cost and space requirements increase
Solution Approach 1:
Multiple separation functions that would traditionally require separate columns are merged into a single integrated divided-wall column, reducing plant footprint while maintaining separation capacity through efficient spatial utilization
Solution Approach 2:
The design transitions from a horizontal arrangement of multiple columns to a vertical integrated structure with divided sections, utilizing the vertical dimension to achieve multiple separations within a single column footprint
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 improves the performance and efficiency of the rectification process by reducing capital costs and space requirements, while maintaining effective vapor and liquid distribution and thermal management.
Implementation Method 1
a plurality of packing elements or trays disposed within the interior core column region and the annulus column region
Implementation Method 2
thermal expansion and contraction of the second annular column wall in a radial direction and in an axial direction is independent of the thermal expansion and contraction of the first annular column wall
Data Source
AI summary
An annular divided wall column for the cryogenic rectification of air or constituents of air is provided. The annular divided wall column includes a first annular column wall and a second annular column wall disposed within the first annular column wall to define an annulus column region and an interior core column region. The present annular divided wall column further includes structured packing elements disposed within at least the annulus column region as well as a ring-shaped cantilevered collector; and a ring-shaped distributor disposed in the annulus column region above or below the plurality of structured packing elements. The thermal expansion and contraction of the second annular column wall in a radial direction and in an axial direction is independent of the thermal expansion and contraction of the first annular column wall in the radial and axial directions.