Gas and liquid contact apparatus – Contact devices – Porous mass
Reexamination Certificate
1998-09-18
2001-02-06
Simmons, David A. (Department: 1724)
Gas and liquid contact apparatus
Contact devices
Porous mass
C261SDIG007
Reexamination Certificate
active
06182950
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods and apparatus for enhancing exchange processes between two fluids. More particularly, the present invention relates to random packing elements for use in exchange process chambers, such as are utilized in mass transfer or heat exchange processes, for example.
BACKGROUND OF THE INVENTION
Many commercial and chemical processes involve mass transfer or heat exchange, and utilize packed columns or chambers to carry out process steps. Such processes can include distillation, absorption and desorption, gas cleaning and drying, scrubbing and various biological processes, such as filtration. Two fluids, usually a gas and a liquid, although two liquids may be utilized, are intermingled within a chamber, typically as counterflow streams wherein two fluids move generally in opposite directions along the same flow axis. The two fluids may however move in the same direction along a flow axis (in a co-current system) or in separate, intersecting directions (in a cross-current system).
Mass transfer and/or reaction rates in such processes increase with increasing amounts of effective surface area that can be wetted by liquid within the chamber and over which the two fluids can then interface with each other. Packing elements are placed in the chamber to increase the surface area available for such interfacing. Packing systems come in two basic types: structured and random. Structured packing systems generally include extended arrays of structured packing elements that are arranged within the chamber. Random packing systems utilize large numbers of individual packing elements which are dumped into the chamber, thereby forming a random array.
Several considerations influence the design of random packing elements. It is important to maximize mass transfer and/or reaction rates through the packing system. A method of maximizing mass transfer and/or reaction rates is to maximize the surface area that can be wetted by a liquid within the chamber, thereby maximizing the area over which two or more fluids may interface. It is important to minimize pressure drop through a packing system. A method of minimizing pressure drop is to maximize the amount of free volume within the chamber by minimizing the volume of random packing element material within the chamber. It is important that the random packing elements be sufficiently strong and rigid to maintain their shape while supporting the weight of other random packing elements located higher in the chamber. It is also important that these random packing elements be capable of low-cost mass production. Indeed, one great advantage of random packing systems over higher-efficiency (high mass transfer and/or reaction rates per unit of pressure drop across the system) structured packing systems is the relatively low cost of random packing systems.
Myriad examples of random packing elements configurations have been utilized in random packing systems. However, a strong need is still felt for random packing elements which, when utilized, can more closely approach the high efficiency of structured packing columns while maintaining the cost advantages of random packing systems. The present invention provides improvements to existing random packing elements which address these needs.
SUMMARY OF THE INVENTION
The present invention provides improvements to random packing elements for use in exchange process apparatus involving at least two fluids, wherein the random packing element comprises a body, which in turn includes at least one transfer element. A plurality of protuberances extend from at least one surface of the transfer element. These protuberances have a curved surface and are preferably convex in shape. Each protuberance is preferably matched with a cavity on the opposite surface of the transfer element, and apertures may penetrate through the protuberances and into the corresponding cavities. The apertures in the protuberances may be oriented in a particular direction if so desired.
The present invention also provides a random packing element having a transfer element including at least one edge which comprises a plurality of alternating curved extensions and depressions. The extensions and depressions are preferably substantially semi-circular in shape and have radii of about 3 millimeters, thereby making the edge of the transfer element substantially sinuous in configuration.
Random packing elements of the present invention may be manufactured from a single sheet of material, preferably a metal, which is substantially rectangular in shape. The sheet is then punched to form the desire protuberances, cavities, and apertures, and sinuous incisions are made to define the desired number of transfer surfaces. The transfer surfaces are then bent to achieve a random packing element of the desired configuration.
The random packing elements of the present invention increase available surface area on transfer elements over which fluids in a random packing bed may interact, improve structural rigidity and strength, increase the likelihood of impact between a transfer element edge and descending droplets of fluid, and work in conjunction with the beading tendencies of liquids to increase the area of on a transfer element over which a given volume of fluid may spread.
REFERENCES:
patent: 2602651 (1952-07-01), Cannon
patent: 4366608 (1983-01-01), Nagaoka
patent: 5543088 (1996-08-01), Halbirt
Hopkins Robert A.
Locke Liddell & Sapp LLP
Simmons David A.
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