Cross-flow Base Downcomer Liquid Seal Polymer Prevention
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Solution Overview
Problem
Crossflow trays used in mass transfer columns for producing (meth)acrylic monomers suffer from undesirable polymerization, leading to deposit formation that can obstruct gas passage openings and require frequent column shutdowns for cleaning.
Innovation Solution
A crossflow tray design featuring downcomers that protrude into collecting cups with a larger cross-sectional area and a peripheral wall with an overflow, preventing gas bypass and ensuring a liquid seal, which reduces polymer formation by maintaining liquid contact and preventing gas entrainment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If downcomers are provided with liquid weirs to adjust liquid level, then liquid closure of downcomer is achieved, but gas preferentially rises above the downcomer and exchange between gas and liquid is impaired
Solution Approach 1:
The collecting cup is nested below the downcomer, with the downcomer protruding into the collecting cup. This nested arrangement allows the liquid seal to form within the collecting cup while the gas flows through the passage openings in the tray, resolving the contradiction between achieving liquid closure and maintaining gas-liquid exchange efficiency
Solution Approach 2:
The collecting cup acts as an intermediary structure between the downcomer and the tray below. It provides a location for the liquid seal to form without interfering with the gas flow path through the passage openings, thus mediating between the need for liquid closure and gas-liquid exchange
2Reliability
If collecting cups are arranged below downcomers to obtain static liquid closure, then gas bypass through downcomer is prevented, but resistance to gas in downcomer area increases and gas preferentially rises above downcomer
Solution Approach 1:
The liquid seal is created locally within the collecting cup area, while the rest of the tray maintains its gas flow characteristics. The downcomer protrudes into the collecting cup where liquid accumulates to form the seal, but the passage openings in the tray remain accessible to gas flow, creating different local conditions for liquid closure and gas flow
3Productivity
If mass transfer column operates for longer periods, then productivity increases, but undesirable polymerization occurs and deposit formation obstructs gas passage openings
Solution Approach 1:
The liquid flowing through the collecting cup and over the peripheral wall acts hydraulically to suppress polymerization. The continuous liquid flow through the downcomer into the collecting cup and over the peripheral wall creates a wet environment that prevents polymer deposits from forming on the tray surfaces, enabling longer operation times
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 effectively reduces or prevents the formation of unwanted polymer deposits, allowing for extended operation of mass transfer columns without interruption, as the liquid seal and overflow configuration enhance liquid-gas contact and prevent polymer formation in areas wetted by the liquid.
Implementation Method 1
The liquid flowing down the downcomer into the collecting cup and over the peripheral wall suppresses polymerization
Implementation Method 2
passage openings for a gas through which a gas flows, whereby no liquid runs off through the passage openings
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a cross-flow base for a material exchange column (27) in which a gas a guided in counterflow to a fluid, wherein the cross-flow base (1) has through openings (3) for the gas and at least two drain shafts (5), wherein the drain shafts (5) project over the upper side of the cross-flow base (1) and a collection cup (13) is arranged underneath each drain shaft (5). The drain shaft (5) projects into the collection cup (13), the minimum horizontal cross-sectional area of the collection cup (13) is 1.2 to 4 times larger than the horizontal cross-sectional area of the drain shaft (5) at the outlet, and the collection cup (13) has a circumferential wall (15) with an overflow device (19). The invention also relates to a material exchange column containing the cross-flow base, and to a use of the material exchange column.