Stock material or miscellaneous articles – Structurally defined web or sheet – Nonplanar uniform thickness material
Reexamination Certificate
1998-11-17
2001-06-26
Loney, Donald J. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Nonplanar uniform thickness material
C428S183000, C428S184000, C261S112200, C261SDIG007
Reexamination Certificate
active
06251499
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to cross-corrugated packing. It is applicable particularly to air distillation columns on board floating oil platforms or on barges.
BACKGROUND OF THE INVENTION
As is well known, cross-corrugated packing is used in certain distillation columns in place of distillation plates, to ensure material and heat exchange between a rising gas and a falling liquid. These cross-corrugated packings are constituted by a superposition of sections. Each section is formed by a stack of corrugated strips each disposed in a ith generally vertical plane, one against the others. The corrugations are oblique and descend in opposite directions from one strip to the next.
The strips generally comprise dense small diameter perforations, with a perforation proportion of about 10l, to permit the liquid to flow on opposite sides of the corrugated strips.
British 1,004,046 and Canadian 1,095,827 disclose such cross-corrugated packings.
A cross-corrugated packing is generally produced from a flat product, namely metallic sheets in the form of strips. The strips are first bent (or folded) so as to form a corrugated metal sheet in a strip whose corrugations are oblique relative to the axis of the strip. The bent strips are then cut off in sections, then stacked alternately reversed. The packing sections thus obtained are often called “packs”.
WO-A-90/10 497 discloses among other things a packing analogous to the mentioned cross-corrugated packings, but perforated in a different way. The term “cross-corrugated packing” used here also comprises such a packing, as well as any analogous packing.
Oil platforms at sea produce residual gases. For economic and environmental reasons, it is becoming more and more necessary to recover these gases, one method consists in their conversion into heavier hydrocarbons, in liquid form and hence more easily transportable, by the Fischer-Tropsch process, which consumes large quantities of oxygen.
SUMMARY OF THE INVENTION
The basic problem that the invention seeks to solve consists in providing an air distillation column capable of operating in satisfactory conditions on board a platform or a barge, which is to say in the presence of oscillations due to swell and whose amplitude is typically comprised between 5° and 10° in all directions. It is thus imperative that the liquid distributed at the head of the column ensures substantially uniform wetting of the packing over all the cross section of the column despite the mentioned oscillations.
To this end, the invention has for its object a corrugated strip for cross-corrugated packing, characterized in that it comprises on its lower edge, in front view, at least one downwardly projecting motif whose contour is such that, if &agr;
m
and &agr;
M
indicate the extremes of the algebraic value of the angle that the tangents to the contour form with the horizontal direction, then
−&agr;
m
>&agr;
0
and &agr;
M
>&agr;
0
,
in which ai designates a predetermined angle at least equal to 5°.
The corrugated strip according to the invention can comprise one or several of the following characteristics:
the motif repeats a plurality of times along the lower edge of the strip, the motifs being adjacent each other or separated by substantially rectilinear segments;
each motif is obtained by bending a flat strip according to a corrugation of a height H, an opening angle &ggr; and a radius r at the summit of the bend, with the bend generatrices inclined at an angle &dgr; seen face on, the parameters H,&ggr;, r and &dgr; being selected such that
sin
δ
·
tan
μ
·
sin
(
γ
2
)
+
cos
δ
1
+
tan
2
μ
·
sin
2
(
γ
2
)
<
cos
α
0
,
wherein,
tan
μ
=
tan
δ
·
[
r
·
sin
(
γ
2
)
+
H
2
-
r
]
+
π
180
·
(
90
-
γ
2
)
·
cos
(
γ
2
)
r
sin
(
γ
2
)
·
[
r
·
sin
(
γ
2
)
+
H
2
-
r
]
+
cos
2
(
γ
2
)
·
r
each motif is obtained by cutting out two recesses in the lower edge of the strip before bending the latter.
The invention also has for its object a cross-corrugated packing section comprising a stack of corrugated strips of which at least one is as defined above, with their corrugations inclined alternately in opposite directions.
The invention also has for its object a distillation column which comprises a superposition of sections of cross-corrugated packing having at least two different angular orientations, at least one of the sections being as defined above, and in which there is at least one direction such that the mean of the cosines of the angles which comprise the assembly of the strips of the section in each direction, the cosines being given an absolute value, is less than 0.5.
When the column is on board a floating structure having a preferred direction of oscillation, which is generally the case with barges, said direction is this preferred oscillation direction.
In particular, in one embodiment, the superposition of the sections is constituted by sections of strips parallel to the preferred direction of oscillation and of sections with strips perpendicular to this direction, the number of these latter being comprised between about ⅔ and ¾ of the total number of sections of said superposed sections.
REFERENCES:
patent: 3526393 (1970-09-01), Meek
patent: 4800047 (1989-01-01), Monjoie
patent: 5632934 (1997-05-01), Billingham et al.
patent: 11 95 779 (1965-07-01), None
patent: 0 273 191 (1988-07-01), None
patent: WO 84/04048 (1984-10-01), None
Lehman Jean-Yves
Werlen Etienne
L'Air Liquide, Societe Anonyme pour l'Etude et l'
Loney Donald J.
Young & Thompson
LandOfFree
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