CA1168149A - Packing material and apparatus - Google Patents

Abstract

Abstract of the Disclosure Packing material is formed of stacked panels of expanded metal, each of which has intersecting sets of parallel linear metal strips, Each panel has a horizontal set of linear strips oriented parallel to a corresponding set of linear strips on an adjacent panel and perpendicular to a vertical fluid flow direct-second set of linear strips inclined about 45° from the vertical.
ion which is parallel to the panels; and, each, each panel has a in a direction opposite to the inclination of the corresponding .
inclined set of strips on the adjacent panel. The strips of adjacent panels are canted in opposite directions relative to the planes of their respective panels. Alternative orientations and directions are also disclosed. The packing material is used in packed towers and with crossflow trays.

Description

!
: ', ' , ~ I
81~9 BACKGROUND_OF TIIE INVENTI0~1 ~ ~ 1li ' . ;, 1 .
This invention relates to improved packing materials for gas-liquid contacting in paclced towers, cross Elow tray jlcolumns, motionless mixers and like apparatus.
i Chemical processing apparatus frequently includes towers filled with a packing material which provides many liquid-supporting surfaces. Liquid introduced at the upper end of the : lltower flows downwardly as a thin film on the suraces of the packing material. Gaseous vapors are injected into the lower end of the tower and ascend through spaces in the packing material,;
moving through the tower in intimate contact with the liquid film on the surface of the packing. The contact between the liquid and vapor can produce a variety of effects such as mass ~ransfer, chemical reactions, heat exchange and scrubbing or !l deentrainment Considerable efforts have been devoted to the develop-ment oE paclcing materials which provlde a reasonable latitude of ~gas and liquid throu~hput, a high mass transfer rate and a low . pressure drop. Random packings formed of loose rings! cylinders ; lor saddles are commonly used; and, packings oE preEormed sec- j iltions which extend the full transverse extent of the tower have ; ¦¦been developed as exemplified by U.S. Patents 3,285,587 and 3,927,165.
There have been some efEorts to develop paclcing mate-rials which, lilce the present invention, are formed of parallel sheets of expanded sheet material such as expanded metal.
1l !
Ij - 2 -., ,, ~. I

~6~1~9 !
!
il . .
Such sheets are manufactured by forrning stagzered parallel rows .
of longitudinally aligned slits in a flat continuous sheet of jmetal and then deforming the sheet to lengthen it transversëiy of the openlngs and open the s:Lits to create diamond or almond- ¦
! shaped openin~s. The openings are disposed irl rows whicll angular-ly intersect. The strips of metal between the openings become canted relative to the plane of the panel and they take on an ~undulating configuration. Each strip may be regarded as having successively arranged sets of four segments in which the first and third segments define the edges of the openings and the second and fourth segments are connected to the opposite segments on the adjacent strips. Segments of the unclulating strips are aligned to form two intersecting sets of parallel linear strips ~hich lie between and define the angularly intersecting rows of openings.
I British patent specification 427 087 discloses a - ~ I scrubber formed of a stack of sheets of expan~ed meta`l pre-ferably vertically disposed with the short lengths of the diamond - shaped openings of successive sheets bcing oriented so that one sheet has its short mesh vertical the next sheet has it-s long mesh vertical the next sheet is reversed and has its short mcsh vertical and the next sheet is reversed and has its long mesh vertical.
British patent specification 977 752 of ]964 discloses a packed tower in which stacks of expanded metal slleets have their stretching directions alternately horizontal and vertical. The planes of the panels in alternate layers lie at right angles to , ~ I

.s 1' I

.

:~

l, ~ ~B~149 , . , , ~j .
. . ~ j . I
',the planes of the panels in the other layers. ~ panel which 'directs liquid droplets toward the vertical central plane is l I,situated ne~t ~o a panel which causes the droplets to travel more .~ ,toward the center of the tower. .
British patent specification 734,874 of 1955 relates to j ¦,a tower packing formed of layers of expanded metal sheets which ;¦ I are somewhat nested and oriented so that the inclined webs in or~e layer are oppositely inclined to those in tlle adjacent layer, i I thereby producin~ a louver effect on thé gas which flows in a general direction perpendicular to the layers.
lthough the foregoing discussion has dealt primarily with packed towers, it is believed that the invention is also ~suitable for use in connection with cross flow tray systems such as those shown in U.S. patent 4,105,723, conduit-connected jmotionless mixers of the genre exemplified by U.S. patent 3,286,992 and other types of apparatus.
.. . , !i .,~ , . . ,. I
';
.: !

. i~: , I .
, .
:, . i, .

: !
,, .:','' 1.
, I i .j .

... .. . . ... . _ _ .. . . .

:. I Summclry of the Invention 7 According to the present invention, sheets of expanded ! sheet material are stacked and disposed relatively to each other ,or relative to the fluid flow direction in a manner which is theorized to improve the dispersion, contact efficiency, mixing or coalescence of fluids passing through the stack of panels. In ¦
one respect, the invention is characterized as a stack of panels : 'in which adjacent panels have sets of linear strips oriented ~ parallel to each other and other sets of linear strips angularly j disposed relative to ea.ch other. In another respect, the invention involves a stack of panels in which the respective ` ~ ,ilinear strips of a given panel are oriented to lie both sub- !
: !
stantially parallel and substantially perpendicular to the linear 'strips o~ the panels adjacent the.reto.
- i The invention also involves a stack of panel.s arranged `: 'so that a first panel has a series of linear strips which are .
: ,!inclined a given angle rom the vertical in one direction, and ¦la second panel which lies adjacent to the first panel and has its series of linea~.strips inclined from the vertical an equal angle ;,but in an opposite direction. Further, the invention involves ¦jfluid contacting apparatus which includes packing material in the ~ ~ Ipath o~ fluid moving ir- a generally axial direction, wherein a ;~ first panel has a series of the linear strips inclined a given :angle in one direction from the axial dlrection, and a second ,panel adjacent to the ~irst yanel has its linear strips inclined ,, !
I

. ,, . I

_ rl - ' llS~1~9 by the given angle from the axial direction in an opposite direction. Preferably, the orientation of the linear strips in the packing is related to the flow path of fluid through the ! packing so that each panel has a series of linear strips which ; ¦1 are oriented abou~ 90 relative to each other and about 45~ re-l lative to the axial flow direction through tlle paclcing material.
.
~ ~ I The axial flow direction is preferably vertical as is the case v, in conventional packed columns or towers.
il The invention also pertains to improvements that this j; type of packing provides when used in conjunction with crossflow ' type tray devices.

1 ~lthough the invention may take a wide variety of con figurations, preferred embodiments thereof are disclosed in the following description and are shown in the accompanying drawings. ¦
,, - .
Description of the Drawings Fig. 1 is a schematic view showing a packed tower con- I
tainillg staclce~ sections of the packing material of the invention. !

. ,' '' , . , . . ~

~68~9 . 1, .
"
i Fig. 2 is an exploded view of small segments of four I successive panels in the stack, showing their relative orienta-tions. ~--I Fig. 3 is a sectional view as seen along the line 3-3 ¦joE Fig. 2, showing the panels slightly spaced apart from the lmutually contacting, adjacent stacked relationship they occupy during normal use. ~
Fig. 4 is a sectional view as seen along the line 4-4 of Fig. 2, showing the panels slightly spaced apart from their normal mutually contacting staclced relationship.
¦I Fig. 5 is a diagra~natic representation of the preferen-¦Itial directions of liquid and vapor flow produced by the panels oE Figs. 2-4.
¦, Fig. 6 sllows the pàcking material in a crossflow tray ¦iapparatus, wherein some sections of the packing lie in the liquid llon the tray deck and other sections of the packing lie below the succeeding tray in the vapor flow path to act as coalescing or eentrainment devices.
Fig. 7 is a sectional view as seen along the line 7-7 ¦,in Fig. 6.

,, ' ' I' , I

1: _, ,,_ . ..... _._ !

, 9 l i ~
,j Brief Description of a Prefe-rred Embodiment .
, .
Fig. 1 shows a packed tower which includes a vertical l cylindrical shell 2 and a liqui~ inlet pipe 4 with a spray head 5 or other distribution device, ~liformly introducing liquid into ¦~ stacked sections 6 of the packing material of this in-vention.
While passing through the packing, the liquid i.s contacted by ! and subjected to the distributive action of ascending vapors which are introduced into the lower end of the tower shell 2 by the vapor inlet pipe 8. The liquid and vapor move axially through the packing in countercurrent vertical flow paths in-dicated by the arrow 10 and, after passing through the tower, liquid is withdrawn through drain pipe 12 and vapor is withdrawn through vapor exhaust pipe 14.
Each section 6 of pack:ing in the tower is formed of a stack of panels which are arranged in face-to-face vertical dis-position, substantially parallel to the axial flow paths of fluids in the tower. Each panel has an appropriate length and orientation to provide its section 6 with a cylindrical con-figuration to fit the tower. Each section has a height of about i four to six inches. To reduce the possibility of channelling, the panels in.adjacent sections are turned relative to each other j ¦ so that they lie in intersecting vertical planes. With this ~isposition, which is yreferably perpendicular, any sheet-like flow released from one section 6 will not conform to the mechan-ical configuratiorl o~ the packing it conEronts in the succeeding section. I

I
, . .

y `-- l I ~ 6 8 ~

~ach panel is a sheet of exyanded sheet materiaI, ¦~
preferably formed of steel or other metal. ~s shown in Fig. 2, such sheets are formed of a series of canted, undulating strips which are interconnected at spaced locations to form openings , 16 therebetween. Small portions of ~our typical panels are shown in Fig. 2, where one such undulating strip lies between ' the two lines A-A. Each undulating strip has successively ,arranged sets of successively arranged segments a, b, c and d, I
of wnich se&ments b and d are connected to an adjacent undulating !
,strip. The panel is fabricated with a die set which shears and , then draws segments a, b and c away from segments a, d and c.
r During this fabrication, the segment d is dra~n slightly, forming i a small angle with segment b. The segments a and r lie at obtuse angles relative to each other, measured in the plane of the panel j and, together with exposed edges of segments b and d, they define 1 . .
the edges of the openings 16. The openings 16 are arranged in intersecting rows which lie respectively between the lines B-B
and C-C. Between and parallel to tllese rows o~ opcnings 16 are sets of linear strips 18 and 20 wllicll extend respectively along the intersecting lines B-B and C-C. Stripsl8are formed of segments a, b and d; and, strips 20 are formed of segments b, c and d. On each panel, all strips 18 are parallel to each other, as are all strips 20.
The four panels in Fig. 2 are designated 22, 24, 26 and 28. At the preferred panel orientation, the linear strips 18 of all panels are horizontal, parallel to each otller an~
perpendicular to the axial fluid flow path. The strips 20 of !

.. ,, -I
"

.. . .

116~9 I;
adjacent panels are substantially perpendicular to eacll other and they lie at equal and opposite inclinations of about 45 relative to the vertical axial fluid flow path.
~ s may be seen in Figs. 2 and 3, the surfaces of tlle segments a, b, c and d are canted relative to the vertical axia~
fluid flow path. These surfaces of adjacent panels are canted ' in opposite directions relative to the planes of their respective panels as sho~ in Fig. 3. It is evident in Fig. 3 that panels 22 and 26 will deflect ascending vapors to the right and panels 24 and 28 will deflect such vapors to the left so that the vapors will be dispersed laterally into the facing areas of adjacent panels. Tlle vapor velocity vectors also have opposite compollents ¦
measured parallel to the panels, as can be seen in Fig. 2 where l,segments a snd c of panels 22 and 2& will deflect the ascending vapors to the right; and, the segments a and c on panels 24 and ;28 will deflect the vapors to the left. ~rom the vantage point of Flg. 2, the panels 22 and 26 will also deflect the vapors away ;
from the vie-~er, and tlle segMents of panels 24 and 28 wil~ deflect tlle vapors Loward the viewer.
j I The edges of segments b and d project Erom the opposite i faces of the panels. The projections formed by segments b are j,somewhat higher than the projections formed by segments ~ due to ¦,the configuration and operation of the manufacturing dies. These spaced projections are aligned to Eorm ridges along the opposite faces of the panels. The primary ridges of this type, i.e.
'those wllicll disl)lay the greatest valley-to-peak heigllt, I.ie 1, .. . . . . .. . ... ..

11681~9 l,parallel to lines A-A of their respective panels. The projections ¦lare also disyosed to for~ secondary ridges of lesser height, ;
observable by sighting along the lines B-B and C-C.
Fi~. 4 shows the profiles of the assembled panels ~2, 1l24, 26 and 2~, as seen when looking parallel to the undulating ¦Istrips, at section line 4-4 in Iig. 2. It will be noted that the jridges on opposite sides of each panel are not of equal height, ¦! the ridges formed by the edges of segments d being somewhat flatter than the ridges formed by the edges of segments b. When the pack is assembled, the primary ridges which lie parallel to ¦IA_A are ori.ented substantially perpendicular to the corresponding ridges of the adjacent panels. These ridge dispositions tend to ¦prevent the panels from sliding relative to each other when they are bound together. The secondary ridges which lie parallel to C-C of one panel are parallel to and project between the corres- i ponding secondary ridges of an adjacent panel.
~ ach two panels with segments d facing each other will lie closer together than two panels witll the segments b facing each other. 'l'his could cause the liquid ancl vapor to favor the ¦l larger s?ace provided by segments b, but this efEect may be ¦I counteracted by se~ments a and c which are oriented to direct the ¦I vapor inLo the narrower between-panel spaces where segments d contact eacll other. The liquid could favor the narrower spaces ¦because they provide a greater surface-to volume ratio. If un-wanted channelling ef~ects are experience~ in the respective sections of the packing, this can be averted by reducing the 1~ heigllt of the sections.

8~
~1 1 One suitable expanded metal panel, formed oE a sheet ¦l about 1 mm thick, had an ovérall thickness of about 5 r~n The undulating strips were about 3.5 rnm wide. The apertures 16 between two such strips were spaced apart about 8 n~n; and, the individual apertures had a length of about 23 r~ and a width of about 8 n~n. Either the length of the openings 16 or, preferably, the width of the linear strips lS, 20 may be changed to vary I! the surface area per unit of packing volume for different system applications. ' The net effec~ of the improved packlng in a tower is that the liquid on adjacent panels will tend to move do~nwardly ¦ in opposite mutually perpendicular inclined directions, and the -; I ascending vapor will move upwardly in opposite mutually perpen-dicular inclined directions. The vapor from adjacent panels will have opposite left~right components and opposite inward/outward components relative to the pa~e in Fig. 2. This is illustrated il in ~i~. 5 where a film of descending liquid will tend to flow parallel to the panels in the direction of arrows 30, established by the orien~ation o~ the linear strips 20 shown in ~i~. 2. The ; ascending vapors strike the canted surfaces of the panels and are , deflected in the directions of arrows 32. From the vantage point ¦
of lig. 5, the vapors are deflected rearwarclly to the right by ¦I panels 22 and 26, and they are deflected forwardly to the left by ¦
panels 24 and 2~. The alternate vapor deflection pattern will produce lateral dispersion with turbulence and shearing effects that will enhance interfacial contact between the liquid and vapor.
, The packing material of this invention may be useful in connection with a variety of fl.uid contacting systems other than the vertical packed tower or column described above. For example,l i it may be substituted for the plate mesh 26 and deentrainment mesh¦

!

1 ~81~9 30 of Mix et al U.S. paten~ 3,~87,665; or, it may serve as an impingement type vapor-liquid separator in lieu of the cellular material 40 of Mix U.S. patent 4,105,723.
An envisioned construction of this nature is illustrated in Figs. 6 and 7 which show a vertical column or tower 34 with cross flow trays 36 of the aperture or sieve tray type. The illustrated tray has lateral apertures and is constructed according to U.S. patent 3,463,464~
Liquid is introduced to one side of each tray 36 by a downcomer 38 at one end of the tray- The liquid flows across the tray where it is subjected to the action of vapor which moves upwardly through apertures in the tray. Liquid from each tray is discl~arged at the opposite end of the tray over an overflow weir into the downcomer of the succeeding stage of the apparatus. In Fig. 6 and 7, a section 40 of the packing material of Figs. 2-5 lies on the tray, in the liquid, and another section 42 of such a packing material is spaced above the liquid to act as an impingement-type deentrainment baffle. ~linute liquid droplets adhere to the baffle 42, coalesce and fall as larger drops rather than being injected with the vapor into the liquid on the next tray thereabove.
The sections 40 and 42 of packing material are formed of vertical panels which lie parallel to the horizontal liquid flow direction across the tray. The panels are oriented as shown in Fig. 2, with the linear strips 18 being horizontal so as to be parallel to the axial liquid flow direction, and the linear strips 20 being at an inclination of about 45 to the vertical. The strips 20 of adjacent panels are mutually perpendicular. It is also possible to orient the panels perpendicular or at an acute angle relative to the liquid or vapor flow directions.

, jj - 13- 1 1~81~9 Persons familiar with the field of this invention will recognize that the disclosed packing material may take many forms, so it is herein emphasized that the invention is not limited only to the disclosed embodiments but is embracing of modifications thereto and improvements thereof which fall within the spirit of the following claims.

Claims (29)

CLAIMS:

1. Fluid contacting apparatus including packing material comprising a stack of upstanding parallel panels of expanded sheet material, means for distributing liquid onto said panels at an upper portion thereof so the liquid will flow gravitationally downwardly on said panels, means for moving a gas through the packing in an upward vertical direction which is parallel to the planes of the panels, said gas moving between the panels to contact the liquid supported on the panels, each panel being formed of a plurality of undulating strips which are connected at spaced locations to form openings therebetween, said openings being arranged in angularly intersecting rows, segments of said undulating strips forming, in each of said panels, two intersecting sets of parallel linear strips which extend laterally across their respective panels, said sets of linear strips extending at opposite inclinations between said rows of openings, a first said panel having a set of said linear strips inclined at a given angle of less than 90° from the vertical in one direction, and a second panel adjacent to said first panel having a said set of linear strips inclined at said given angle of less than 90° from the vertical in an opposite direction, said opposite inclinations of the linear strips being operable to cause the liquid on adjacent panels to flow downwardly in opposite inclined directions established by the orientation of the linear strips,and wherein each of said panels has another set of linear strips extending thereacross in a direction which is substantially perpendicular to said flow direction.

2. The apparatus of claim 1 in which said panels each have a said set of linear strips extending laterally thereacross in a direction which is substantially parallel to a set of linear strips of an adjacent panel.

3. The apparatus of claim 1 in which said parallel sets of linear strips project from the faces of their respective panels to form spaced parallel ridges on opposite faces of said panels, said ridges of one panel projecting between the ridges of an adjacent panel.

4. The apparatus of claim 1 in combination with an additional stack of panels as claimed, said panels in one stack being turned relative to the panels in an adjacent stack to lie in intersecting planes.

5. The apparatus of claim 1 in which said linear strips on adjacent panels have their surfaces canted in opposite directions relative to the planes of their respective panels.

6. The apparatus of claim 1 in which the given angle is about 45°.

7. The apparatus of claim 1 wherein said undulating strips have their surfaces canted relative to the planes of their respective panels, adjacent said panels having their undulating strips canted in opposite directions rela-tive to the axial flow direction so as to deflect fluids in opposite directions relative to the planes of said panels.

8. Fluid contacting apparatus, comprising, a cross flow tray, a downcomer for introducing liquid at one end of the tray and an overflow weir at the other end thereof, said tray having apertures therein which enable vapor to flow up-wardly through the tray into a liquid which is flowing from the downcomer to the weir, packing material lying in the liquid on the tray, said packing material comprising a stack of panels of expanded sheet material, each panel being formed of a plurality of undulating strips which are interconnected at spaced locations to form openings therebetween, each of said undulating strips including successively arranged sets of successively arranged segments, each set of segments in-cluding a first segment, a second segment, a third segment, and a fourth segment, said first segments extending across the panel in one direction, said second segments being connected to the fourth segments of an adjacent undulating strip, said third segments extending across the panel at an angle to said first segments and said fourth segments being connected to second segments of another adjacent strip, said first, second and fourth segments being generally aligned to provide on each panel a first set of parallel linear strips, said second, third and fourth segments being generally aligned to provide on each panel a second set of parallel linear strips, said panels being stacked with their first sets of linear strips extending across -their respective panels in directions parallel to each other and their second sets of linear strips extending across their respective panels in directions angularly disposed to each other.

9. The packing material of claim 8 in which said first linear strips project from the faces of their respective panels to form spaced parallel ridges on opposite faces of said panels, said ridges of one panel projecting between the ridges of an adjacent panel.

10. The packing material of claim 8 in which said linear strips on adjacent panels have thier surfaces canted in opposite directions relative to the planes of their respective panels.

11. The packing material of claim 8 wherein the flow direction of the liquid flowing from the downcomer to the weir lies substantially parallel to the planes of the panels.

12. The packing material of claim 8 wherein said undulating strips have their surfaces canted relative to the planes of their respective panels, adjacent said panels having their undulating strips canted in opposite directions relative to the liquid flow direction so as to deflect fluids in opposite directions laterally of the liquid flow direction.

13. The combination of claim 8 wherein said panels of the packing material are vertical and lie parallel to the path of liquid movement which extends from the downcomer to the overflow weir, adjacent said panels having their second sets of linear strips lying perpendicular to each other and having an inclination angle of about 45°.

14. The apparatus of claim 8, wherein the apertures are oriented to introduce the vapor into the liquid in a direction which is lateral relative to the tray and sub-staunchly perpendicular to the path of liquid flowing from the downcomer to the weir, said packing material being located above the apertures such that said tray is unobstructed between adjacent apertures.

15. Fluid contacting apparatus, comprising, a cross flow tray, a downcomer for introducing liquid at one end of the tray and an overflow weir at the other end thereof, said tray having apertures therein which enable vapor to flow up-wardly through the tray into a liquid which is flowing from the downcomer to the weir, packing material lying in the liquid on the tray, said packing material comprising a stack of panels of expanded sheet material, each panel being formed of a plurality of undulating strips which are interconnected at spaced locations to form openings therebetween, said openings being arranged in angularly intersecting rows, said undulating strips having segments which form two intersecting sets of parallel linear strips which extend laterally across the respective panels, said sets of strips extending at opposite inclinations between said rows of openings, a said panel having said first set of linear strips extending substantially parallel to a first set of said linear strips on the panel adjacent thereto and a second set of linear strips extending substan-tially perpendicular to a second set of said linear strips on the panel adjacent thereto.

16. The packing material of claim 15 in which said first set of linear strips project from the faces of their respective panels to form spaced parallel ridges on opposite faces of said panels, said ridges of one panel projecting between the ridges of an adjacent panel.

17. The packing material of claim 15 in which said linear strips on adjacent panels have their surfaces canted in opposite directions relative to the planes of their respective panels.

18. The packing material of claim 15 wherein the flow direction of the liquid flowing from the downcomer to the weir lies substantially parallel to the planes of the panels.

19. The packing material of claim 15 wherein said undulating strips have their surfaces canted relative to the planes of their respective panels, adjacent said panels having their undulating strips canted in opposite directions relative to the liquid flow direction so as to deflect fluids in opposite directions laterally of the liquid flow direction.

20. The combination of claim 15 wherein said panels of the packing material are vertical and lie parallel to the path of liquid movement which extends from the downcomer to the overflow weir, adjacent said panels having their said second sets of linear strips inclined about 45° from the vertical.

21. The apparatus of claim 15, wherein the apertures are oriented to introduce the vapor into the liquid in a direction which is lateral relative to the tray and sub-stantially perpendicular to the path of liquid flowing from the downcomer to the weir, said packing material being located above the apertures such that said tray is unobstructed be-tween adjacent apertures.

22. Fluid contacting apparatus, comprising a cross flow tray, a downcomer for introducing liquid at one end of the tray and an overflow weir at the other end thereof, said tray having apertures therein which enable vapor to flow upwardly through the tray into a liquid which is flowing from the downcomer to the weir, packing material lying in the liquid on the tray, said packing material comprising a stack of vertically disposed panels of expanded sheet material, each panel being formed of a plurality of undulating strips which are interconnected at spaced locations to form openings there-between, said openings being arranged in angularly intersecting rows, said undulating strips having segments which form two intersecting sets of parallel linear strips which extend across their respective panels, said sets of strips extending be-tween said rows of openings, a first said panel having one set of said linear strips inclined a given angle from the vertical in one direction, and a second panel adjacent to said first panel having one set of said linear strips inclined said given angle from the vertical in an opposite direction.

23. The packing material of claim 22 in which the other said set of linear strips on each panel extends laterally thereacross substantially parallel to the other said set of linear strips of an adjacent panel.

24. The packing material of claim 23 in which the other said linear strips project from the faces of their respective panels to form spaced parallel ridges on opposite faces of said panels, said ridges of one panel projecting between the ridges of an adjacent panel.

25. The packing material of claim 22 in which said sets of linear strips on adjacent panels have their surfaces canted in opposite directions relative to the planes of their respective panels.

26. The packing material of claim 22 wherein the flow direction of the liquid flowing from the downcomer to the weir lies substantially parallel to the planes of the panels.

27. The packing material of claim 22 wherein said undulating strips have their surfaces canted relative to the planes of their respective panels, adjacent said panels having their undulating strips canted in opposite directions relative to the liquid flow direction so as to deflect fluids in opposite directions laterally of the liquid flow direction.

28. The combination of claim 22 wherein said panels of the packing material lie parallel to the path of liquid movement which extends from the downcomer to the overflow weir, said given angle of inclination of said second strips being about 45°.

29. The apparatus of claim 22, wherein the apertures are oriented to introduce the vapor into the liquid in a direction which is lateral relative to the tray and sub-stantially perpendicular to the path of liquid flowing from the downcomer to the weir, said packing material being located above the apertures such that said tray is unobstructed between adjacent apertures.