Parallel Flow Downcomer Tray Layout for High-Capacity Mass Transfer
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Solution Overview
Problem
Conventional mass transfer columns face limitations in high-capacity vapor-liquid contacting due to restricted active area and downcomer configuration, leading to inefficiencies in mass transfer, particularly in high-pressure distillation systems.
Innovation Solution
A multiple pass downcomer tray design featuring an annular tray with multiple mass transfer decks, central and peripheral downcomers, and liquid channel structures, promoting a serpentine liquid flow path and parallel vapor-liquid interaction across successive trays, enhancing mass transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional single pass or two pass trays are used, then the tray structure is simple, but the mass transfer efficiency is limited due to restricted active area and downcomer configuration
Solution Approach 1:
The tray is divided into multiple mass transfer decks (at least four) with distinct active areas, each handling vapor-liquid contact independently. This segmentation increases the total active area available for mass transfer while organizing the complex flow patterns into manageable sections, thereby improving mass transfer efficiency without overwhelming structural complexity
Solution Approach 2:
The invention transitions from conventional single-plane trays to a multi-deck three-dimensional structure where mass transfer occurs across multiple horizontal planes. This dimensional expansion effectively increases the active area within the same column footprint, enhancing productivity while the modular deck design keeps the structural complexity manageable
2Productivity
If the amount of descending liquid or ascending vapor exceeds the tray capacity, then flooding of the tray occurs, but increasing tray capacity requires larger downcomer areas
Solution Approach 1:
The downcomer system is segmented into multiple independent downcomers (at least two) positioned at different locations on the tray. Each downcomer handles a portion of the liquid flow, distributing the total liquid capacity across multiple channels. This allows the tray to handle higher liquid rates without requiring a single large downcomer area, thus increasing tray capacity while limiting the area occupied by individual downcomers
Solution Approach 2:
The liquid flow path is extended from a single-plane vertical drop to a multi-level journey across stacked mass transfer decks. Liquid traverses multiple horizontal active areas before entering downcomers, effectively increasing the processing capacity within the same vertical column space without proportionally increasing downcomer area
3Productivity
If liquid flows completely across one tray before entering the downcomer, then the liquid handling path is simple, but the mass transfer efficiency is reduced due to non-uniform driving forces
Solution Approach 1:
The liquid flow path is segmented into multiple passes across different mass transfer decks rather than a single continuous flow. Liquid is distributed to multiple decks where it undergoes sequential mass transfer operations, creating more uniform driving forces across each segment. This segmented approach improves mass transfer efficiency while the modular structure keeps the flow path complexity manageable
Solution Approach 2:
The liquid undergoes periodic mass transfer actions as it sequentially passes through multiple decks, with each deck providing a distinct mass transfer stage. This periodic interaction between liquid and vapor across multiple stages enhances the overall mass transfer efficiency by maintaining consistent driving forces throughout the process
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
The design significantly improves mass transfer efficiency by maintaining uniform driving forces across trays, reducing weir loading, and optimizing liquid flow paths, thereby increasing the overall capacity and performance of mass transfer columns.
Implementation Method 1
the upwardly flowing vapor or gas stream to become selectively enriched with the lighter components of the mixture, i.e., those components with relatively high volatilities, while the generally downwardly flowing liquid stream becomes selectively enriched with the heavier component of relatively low volatilities
Implementation Method 2
The vapor and liquid interaction on the tray desirably causes a froth to build up on the tray. Because the liquid phase remains substantially continuous in the froth, the vapor and liquid interaction continues in the froth and results in greater mass transfer efficiencies
Data Source
AI summary
A multiple pass, parallel flow downcomer tray for a mass transfer column and method for liquid-vapor contacting in a mass transfer column is provided. The multiple pass, parallel flow downcomer tray has at least four mass transfer decks configured to provide contact between an ascending vapor passing upward through apertures on the tray surface and a traversing liquid on the tray surface. The tray further includes a central downcomers disposed near a central axis of the tray and two or more peripheral downcomers disposed near the edge of the tray and spaced apart from the central axis, wherein at least two of the four mass transfer decks are configured to discharge the traversing liquid into the peripheral downcomers and two of the four mass transfer decks are configured to discharge the traversing liquid into the central downcomer.