Enlarged Funnel Downcomer for Distillation Column Flooding
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Solution Overview
Problem
Distillation columns used for separating permanganate reducing compounds from an aqueous stream face hydraulic imbalances and flooding issues due to insufficient open area in the top downcomer region, leading to reduced production rates and increased impurities in the final product, making it costly and inefficient to replace existing trays or adjust operating parameters.
Innovation Solution
A distillation column design with tray assemblies featuring enlarged, funnel-shaped downcomers in the upper region and a constant cross-sectional area in the lower region, which can be retrofitted into existing columns by modifying the tray panels and support structures, increasing the upper downcomer area without requiring extensive re-design or replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the feed rate and reflux rate are increased to achieve higher production, then productivity increases, but the bottom section pressure drop increases exponentially causing flooding and reducing reliability
Solution Approach 1:
The downcomer is designed with non-uniform cross-sectional area, having a larger area at the top and a smaller area at the bottom. This local variation in geometry allows the downcomer to accommodate the varying liquid flow rates at different heights, preventing flooding at the tray level while maintaining efficient liquid delivery to the tray, thus enabling higher production rates without compromising operational stability
Solution Approach 2:
The invention transitions from a conventional uniform downcomer design to a tapered downcomer with varying cross-sectional area along its height. This dimensional change in the downcomer geometry provides additional hydraulic capacity at the top where liquid flow is highest, resolving the flooding issue that limits production rate increases
2Productivity
If existing trays are replaced with redesigned trays to increase downcomer area, then flooding is prevented and productivity can increase, but the cost and time for re-design and replacement increase significantly
Solution Approach 1:
The invention changes the geometric parameters of the downcomer by providing a tapered configuration with larger top area and smaller bottom area. This parameter change can be achieved by modifying existing tray components or adding attachments to current trays, rather than requiring complete tray replacement, thus reducing downtime and replacement costs while still preventing flooding and enabling higher production rates
3Reliability
If the downcomer area is increased to prevent flooding, then reliability improves, but the amount of material and device complexity increases
Solution Approach 1:
The downcomer is designed with non-uniform cross-sectional area, having a larger area at the top and a smaller area at the bottom. This local variation in geometry allows the downcomer to accommodate the varying liquid flow rates at different heights, preventing flooding at the tray level while maintaining efficient liquid delivery to the tray, thus enabling higher production rates without compromising operational stability
Solution Approach 2:
The tapered downcomer design uses a curved or conical transition from larger top area to smaller bottom area, which provides smooth flow transition and reduces turbulence. This curved geometry achieves the flooding prevention function more efficiently than abrupt transitions, minimizing the additional material required while maintaining reliability
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 design enhances the hydraulic capacity of distillation columns, allowing for up to 35% higher production rates without flooding, while maintaining the same or less material usage and minimizing downtime and costs associated with re-design and replacement.
Implementation Method 1
a downcomer panel assembly that defines a downcomer having, in a downward direction, a funnel-shaped upper region of decreasing cross-sectional area, and a lower region of substantially constant cross-sectional area
Implementation Method 2
Vapor-liquid contact tray assemblies are used in mass transfer or exchange columns to facilitate contact between, for example, upwardly flowing vapor streams and downwardly flowing liquid streams
Implementation Method 3
Most of the area of the tray panels includes a pattern of apertures to allow vapor to flow upwardly through the tray panel for interaction with liquid flowing across the top surface of the tray panel
Implementation Method 4
the first distillation column concentrates the PRCs, and in particular the acetaldehyde in the overhead stream thereof
Data Source
Figure 1
Figure 2A
Figure 2B~3B
AI summary
A distillation column is provided with a downcomer having an enlarged upper region to increase a processing rate for the removal of permanganate reducing compounds (PRCs) formed by the carbonylation of methanol in the presence of a catalyst to produce acetic acid. The distillation column includes a vertically extending distillation housing; and a plurality of tray assemblies, at least one of which includes a horizontally extending tray panel and a downcomer having, in a downward direction, an enlarged, funnel-shaped upper region defined by a top downcomer panel oriented at an angle to the vertical, and a lower region of substantially constant cross-sectional area defined by a vertically-oriented bottom downcomer panel.