Gas and liquid contact apparatus – Contact devices – Wet baffle
Patent
1988-09-23
1990-04-10
Miles, Tim
Gas and liquid contact apparatus
Contact devices
Wet baffle
428184, B01F 304
Patent
active
049158783
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a packing structure especially for use in a column mainly for contacting liquid and gas phases.
BACKGROUND OF THE INVENTION
In the chemical industry for carrying out chemical operations that require the contacting of different phases that meet mostly in a counterflow e.g. such as absorption, distillation, etc. columns are used which can comprise several stages of plates, random or stacked packings or regular tower packings.
The efficiency of a phase-contacting assembly can be characterized by a few number of operational parameters e.g. by the quantity of material that can be processed in a unity volume of column or by the pressure drop that relates to a theoretical stage, etc. Regularly arranged packing structures can generally process higher quantities of material per unity volume of column with smaller pressure loss per theoretical stage than other packing bodies or trays can. Owing to such properties orderly arranged packing structures are especially appropriate for use under vacuum.
In tray columns in which the contact of different phases takes place in a stagewise manner, the expansion of the interfacial area, which decisively influences the mass transfer, occurs mainly on account of the flow energy of the gas phase i.e. it is associated with a higher pressure drop. The gas overcomes the hydrostatic pressure of the liquid on the plates, penetrates therethrough and it raises a fraction of the liquid in the form of a foam or droplets in the space between the plates, and the material transfer takes place through the so obtained free liquid surface i.e. at the phase boundary surface. For avoiding direct liquid transport only a portion of the space between the plates can thus be utilised which is connected with the less effective utilization of the column.
In packed columns in which there is a continuous contact between the phases, the liquid is flowing down along the mantle surfaces of the packing bodies, while the gas phase flows up through the space between the bodies which space defines free cross sections of flow. This free cross section can vary from layer to layer and it varies sometimes even within a layer as well. The interfacial area is constituted primarily by the wetted surface of the bodies. A portion of the flow energy of the gas phase gets lost as a friction loss on the surface of the bodies and other parts of this energy get lost mainly due to shape resistance and to swirling losses in the zig-zag channels between the bodies having varying cross sections.
In case of wetted packing bodies a portion of the increased loss of flow energy of the gas phase is utilised to wet the surface of the packing more effectively, whereby an increased interfacial area is obtained. In the smaller gas flow channels the gas retains more liquid, while in the larger passage channels the liquid can flow down in narrow streams without forming a film. This results first in the forward mixing of parts of the liquid phase i.e. both the flow profile and concentration profile will differ from the ideal piston-like flow and on the other hand in excess pressure drop. The increase of the liquid volume being jammed in contracting channel sections results in further increase in pressure losses and might cause local flooding. If the random packing has an inappropriate structure, the free cross section of flow can be decreased to such extents in one or more horizontal planes of the column that might cause the formation of `liquid plugs`.
The use of ordered or regular packing structures can overcome most of such drawbacks of randomly packed columns. Ordered packing structures consist of sheets or ribbons arranged regularly in a side by side relationship.
Ordered packing structures comprise passage channels which can be considered to represent the elementary units thereof. The passage channels are open both at their upper and lower ends. In a counterflow operation the liquid phase enters the passage channels from above, while the gas enters from below. The liquid flows down on
REFERENCES:
patent: 2940168 (1960-06-01), Monroe
patent: 3227429 (1966-01-01), Renzi
patent: 3415502 (1968-12-01), Munters
patent: 3485485 (1969-12-01), Faigle
patent: 4228943 (1980-10-01), Tanabe et al.
patent: 4363753 (1982-12-01), Bozon et al.
patent: 4455339 (1984-06-01), Meier et al.
patent: 4548766 (1985-10-01), Kinney, Jr. et al.
patent: 4623454 (1986-11-01), Tauscher et al.
Gyorgy Fabry
Pal Manczinger
Meller Michael N.
Miles Tim
LandOfFree
Packing structure especially for use in a column mainly for cont does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Packing structure especially for use in a column mainly for cont, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Packing structure especially for use in a column mainly for cont will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2298070