Contact Tray Baffle Wall for Low Liquid Flow Entrainment
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Solution Overview
Problem
Mass transfer columns experience reduced operating efficiencies due to significant liquid entrainment in ascending vapor during low liquid flow rates, which restricts vapor flow and reduces interaction between fluid streams.
Innovation Solution
The tray design features a serpentine flow path created by baffle walls that forces liquid to change direction multiple times, lengthening its path and reducing entrainment, along with apertures for vapor interaction and a downcomer for efficient liquid discharge, positioned to align with the inlet of the underlying tray.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid flows across the active area of the tray at low flow rates, then mass transfer interaction between liquid and vapor occurs, but significant liquid entrainment in ascending vapor reduces operating efficiency
Solution Approach 1:
The tray deck is segmented into active area and inactive area using a partial chordal plate, which divides the liquid flow path. This segmentation allows liquid to flow through a longer, controlled path while vapor passes through apertures in the inactive area, reducing liquid entrainment in vapor without compromising mass transfer efficiency
Solution Approach 2:
The invention introduces a vertical dimension to the flow path by using a partial chordal plate that extends upwardly from the tray deck. This creates a three-dimensional flow pattern where liquid flows over the plate while vapor passes through apertures, separating the phases in the vertical dimension and reducing entrainment
2Use of energy by moving object
If liquid flow rate is low, then energy consumption is reduced, but vapor flow restriction increases due to entrained liquid
Solution Approach 1:
The harmful effect of liquid entrainment is extracted and removed from the vapor phase by providing a separate liquid collection system. The partial chordal plate and associated downcomers capture entrained liquid and return it to the liquid phase, preventing it from restricting vapor flow and increasing pressure drop
3Productivity
If tray deck area is increased to improve mass transfer, then liquid-vapor interaction is enhanced, but liquid flow path width increases reducing flow concentration
Solution Approach 1:
Different areas of the tray deck are given different functions: the active area contains apertures for vapor-liquid mass transfer, while the inactive area contains the partial chordal plate for liquid flow control. This local differentiation allows each area to optimize its specific function without compromising overall performance
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 liquid-vapor interaction efficiency by minimizing liquid entrainment and increasing the volumetric flow rate, thereby improving the overall performance of mass transfer columns at low liquid flow rates.
Implementation Method 1
baffle walls extending upwardly from the upper surface of the tray deck and positioned to narrow a width of a flow path of the liquid when it flows from the inlet area to the outlet and to force the liquid to change its direction of flow at least twice and thereby lengthen the flow path
Implementation Method 2
a plurality of apertures distributed across an area of the tray deck and extending through the tray deck to permit upward passage of fluid through the tray deck for interaction with the liquid
Implementation Method 3
a downcomer extending downwardly from the outlet to receive liquid when it enters the outlet and then convey it downwardly to a discharge outlet located at a lower end of the downcomer
Implementation Method 4
Under low liquid flow rates, such as rates less than 25 U.S. gallons per minute per foot of the width of the liquid flow path (25 gpm/ft of flow path width), a significant portion of the liquid flowing across the active area of the tray may become entrained as droplets in the ascending vapor
Data Source
AI summary
A contact tray for use in a mass transfer or heat exchange column and having multiple baffles walls that cause the liquid flowing on an upper surface of a tray deck tray to change its direction of flow and narrow its flow path width and extend the length of the flow path when the liquid flows from an inlet area to an outlet on the tray deck. By narrowing the flow path, the volumetric flow rate of the liquid at any portion of the deck increases and reduces the opportunity for vapor entrainment of the liquid at low liquid flow rates. A downcomer extends downwardly from the outlet to receive liquid when it enters the outlet and then convey it downwardly to a discharge outlet located at a lower end of the downcomer. The downcomer includes an inclined or horizontal portion that causes the discharge outlet to be positioned beneath and in vertical alignment with the inlet area on the tray deck.