Perforated Cascade Tray for Rectification Columns

Solution Overview

Problem

Cascade trays in rectification columns experience inefficiencies due to uneven liquid levels across the tray, leading to reduced separation performance, especially at low throughput conditions, where 'raining through' occurs, causing steam to pass through dry sections and reducing mass transfer efficiency.

Innovation Solution

The introduction of cascade trays with openings in the cascade weir, designed to maintain consistent liquid levels on both sides by adjusting the height and configuration of the cascade and outflow weirs, and incorporating optional closable openings for steam passage, ensures balanced liquid flow and reduced differences in liquid levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cascade trays are used to reduce liquid level difference, then separation performance is improved, but at low throughput the liquid level becomes uneven causing 'raining through' and reduced efficiency

Engineering Contradiction:

Improveseparation performanceVSAvoidthroughput efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The cascade weir is designed with openings (perforations) that allow liquid to pass through when the liquid level is low, preventing complete drainage and maintaining a minimum liquid level on the inlet side. This porous approach ensures that steam always has liquid to contact, eliminating the 'raining through' effect while maintaining separation performance across all throughput conditions.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The liquid level control mechanism changes from passive (relying on weir height alone) to active (using openings to dynamically adjust liquid flow). At low throughput, the openings maintain a minimum liquid level; at high throughput, the openings allow excess liquid to pass through, automatically adapting to flow conditions to prevent both 'raining through' and liquid level imbalance.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the cascade weir is designed higher to maintain liquid level, then liquid level difference is reduced, but steam flow distribution becomes uneven and mass transfer efficiency decreases

Engineering Contradiction:

Improveliquid level uniformityVSAvoidmass transfer efficiency

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The perforated cascade weir allows liquid to pass through the openings at controlled rates, maintaining a relatively uniform liquid level across the tray surface. This uniform liquid distribution ensures that steam flows evenly through all openings, maximizing mass transfer efficiency while preventing the liquid level differences that cause uneven steam distribution and energy loss.

Inventive Principle:

Principle #31Porous materials

3Stability of the object's composition

If cascade trays with openings in cascade weir are used, then liquid level consistency is improved, but device complexity increases

Engineering Contradiction:

Improveliquid level consistencyVSAvoidtray structure complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The cascade weir is designed with openings (perforations) that allow liquid to pass through when the liquid level is low, preventing complete drainage and maintaining a minimum liquid level on the inlet side. This porous approach ensures that steam always has liquid to contact, eliminating the 'raining through' effect while maintaining separation performance across all throughput conditions.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The liquid level control mechanism changes from passive (relying on weir height alone) to active (using openings to dynamically adjust liquid flow). At low throughput, the openings maintain a minimum liquid level; at high throughput, the openings allow excess liquid to pass through, automatically adapting to flow conditions to prevent both 'raining through' and liquid level imbalance.

Inventive Principle:

Principle #35Parameter changes

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 separation performance of rectification columns by minimizing the occurrence of 'raining through' and maintaining efficient mass transfer across varying operating conditions, increasing the availability and reducing energy consumption and downtimes.

Implementation Method 1

liquid (1) flows from an inlet side to an outlet side

Methodology Applied

Scientific EffectGravity: Gravitation

Implementation Method 2

the cascade weir (600) has openings (900) for the passage of the liquid (1)

Methodology Applied

Scientific EffectFluid flow through openings: Flow Separation

Implementation Method 3

openings (800) for the passage of the upflowing steam (2)

Methodology Applied

Scientific EffectMass transfer: Diffusion

Implementation Method 4

the at least one cascade base (100) has an offset (700) at the position of the at least one cascade weir (600)

Methodology Applied

Scientific EffectHydraulic gradient: Pressure Gradient

Data Source

PatentEP3551308B1Cascade tray, rectifying column containing said cascade tray, method for operating such a rectifying column, and use of same

Publication Date: 2023.09.20 COVESTRO INTELLECTUAL PROPERTY GMBH & CO KG

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AI summary

The invention relates to a cascade tray suitable for use in a rectifying column and comprising openings in the weir-type cascade edge, to a rectifying column containing at least one cascade tray according to the invention, to a method for operating such a rectifying column, and to the use of a claimed rectifying column in the fractionation of specific substance mixtures.