Heat exchange – With first fluid holder or collector open to second fluid
Reexamination Certificate
2001-04-09
2003-12-30
Bennett, Henry (Department: 3743)
Heat exchange
With first fluid holder or collector open to second fluid
C165S115000, C165S174000
Reexamination Certificate
active
06668913
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of matter and/or heat exchange columns, particularly columns for scrubbing or distilling gas mixtures. More specifically, it relates to manifolds that collect the liquid descending down inside these columns and distribute it over the upper surface of the active zone of the column that they overhang.
During the processes of separating the various constituents of a gaseous mixture inside a column, it may be necessary to extract the gases ascending up inside this column so as to subject them to a treatment such a heat exchange operation intended to return them to a given temperature. This is the case in particular when scrubbing the ascending gases inside the column using a liquid constituent. As an example of such a method, mention may be made of the operation of separating hydrogen from mixtures containing hydrogen, CO and methane which are obtained by the reforming of methane with steam. During the separation operation aimed at collecting pure hydrogen at the top of the column, the hydrogen may be scrubbed with liquid methane that is introduced into the upper part of the column.
For such a scrubbing operation to be as effective as possible, a temperature as close as possible to −180° C. needs to be maintained throughout the column, even though the scrubbing is exothermal. For this purpose, it is a known practice to extract the ascending gases at various points on the column, to pass them through a heat exchanger aimed at cooling them, and to reintroduce them into the column at a level above the level at which they were tapped. The drop in temperature of the collected gases after they have passed through the exchanger causes the less volatile compounds of the gaseous mixture to condense. This condensed liquid is collected by liquid traps which pour it out into manifold containers. These manifold containers have a perforated bottom which allows them to distribute the liquid they contain over the upper surface of an active zone, such as a packing, that they overhang.
These liquid trap-manifold assemblies constitute relatively bulky members, the overall height of which can be as much as a few meters. As the column generally has a number of packings and stages where the ascending gases are extracted, cooled and then reintroduced into the column, this construction of necessity entails building very tall columns, therefore having a high cost price. In addition, these liquid trap-manifold assemblies are of complex structure and are in themselves costly to produce.
SUMMARY OF THE INVENTION
The object of the invention is to provide users of matter and/or heat exchange columns with liquid-gas manifolds which are appreciably less complicated than the existing manifolds, so as to allow a reduction in the cost of construction of the column, and possibly in its overall height.
To this end, a subject of the invention is a liquid-gas manifold for a matter and/or heat exchange column, characterized in that it comprises a single container of roughly cylindrical overall external shape, designed to define an annular space between its side wall and the interior wall of the said column and having a perforated bottom, means for connecting the container to the interior wall of the column, and means allowing the gases to be transferred from the said annular space to the space located above the container.
The latter means may consist of openings formed in an upper lip of the said manifold, or in the side wall of the container.
As a preference, the container has a narrowing of its internal cross section in its central part.
Another subject of the invention is a matter and/or heat exchange column comprising at least one liquid-gas manifold collecting the descending liquid to distribute it to an active zone that it overhangs, characterized in that the said manifold is in accordance with the type described above.
According to one variant of the invention, the said means allowing the transfer of the ascending gases from the said annular space into the space located above the container comprise a pipe for tapping the ascending gases from the said annular space and a pipe for reintroducing the said gases into the column above the container.
According to another variant of the invention, openings are made in an upper lip of the container, and open into an heat exchanger incorporated into the said column.
As will have been appreciated, the invention consists in incorporating into the liquid-gas manifold, a single container of cylindrical overall shape with a perforated bottom, with which no separate liquid trap is associated. According to the various variants of the invention, the container collaborates with the wall of the column to send the ascending gases to undergo a treatment in apparatus located outside or inside the column, or allows the ascending gases to pass through.
REFERENCES:
patent: 3070360 (1962-12-01), Rafferty et al.
patent: 3668881 (1972-06-01), Thibault et al.
patent: 3744440 (1973-07-01), Gardner
patent: 4816191 (1989-03-01), Berven et al.
patent: 5478535 (1995-12-01), Fierz et al.
patent: 5692394 (1997-12-01), Ozaki et al.
patent: 680 908 (1992-12-01), None
patent: 1 501 731 (1969-12-01), None
Bennett Henry
L'Air Liquide-Societe Anonyme a Directoire et Conseil de Su
Patel Nihir
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