US 3374992 A
Description (OCR text may contain errors)
March 26 1968 K. R. GREER 3 374 9 GAS-LIQUID CONTACT APPARATUS Filed March 4, 1964 s Sheets-Sheet 1 Filed March 4, 1964 3 Sheets-Sheet March 26, 1968 K. R. GREER 3,374,992
7 GAS-LIQUID CONTACT APPARATUS 7 Filed March 4, 1964 3 Sheets-Sheet 5- LIQUID V sAs i United States Patent ()fiice 3,374,992 Patented Mar. 26, 1968 This invention relates to improvements in or relating to packings and in particular to packings for water cooling towers and more particularly to improved film flow packings within the towers.
In my Patent No. 3,260,511 I have disclosed a packing unit comprising a stack of alternate flat and corrugated sheets of rigid thermoplastic organic polymeric material held together and arranged such that points or lines of contact of a corrugated sheet with one side of a fiat sheet are co-linear with the points or lines of contact with that flat sheet of the corrugated sheet on the other side of that same flat sheet.
When the liquid to be cooled is distributed from above the packings which are situated such that the corrugations lie in the vertical plane, I have described in the aforesaid patent a preferred embodiment wherein the corrugations described a curvi-linear path in the plane of the sheet, so that all the cooling liquid contacts the surfaces of the packings. This necessitates, however, that the pressure of the cooling air is increased in order to flow through the curved corrugations.
It is an object of the present invention to provide a packing that minimises this increase in air pressure while still allowing substantially all the cooling liquid to con tact the surfaces of the packings.
According to the present invention I provide packings comprising at least one unit having the structure which comprises a rigid stack of alternate fiat and corrugated sheets held together such that rigidity is provided by the lines or points of attachment of one corrugated sheet with a flat sheet which correspond with the lines of attachment or at least some of the points of attachment of that same flat sheet to the next adjacent corrugated sheet, each corrugation being displaced laterally in the plane of the sheet to follow a curved path over a minor part of its length such that from the point of entry, as herein- I after defined, to the end of said displacement, a straight line passage through the corrugation is prevented by the curvature of the corrugation.
'According to a further feature of my invention I provide .packings in which each corrugation of said corrugated sheets is displaced laterally in the plane of the sheet to follow a curved path over a minor part of the length of the corrugation near the point of entry, as here- .in after defined, such that, either the corrugation following said curved path is displaced wholly to one side of or the corrugation following said curved path is initially displaced to one side of said main axis and is thereafter displaced to the other side of said main axis, the maximum lateral separation between points on the apex of the corrugattion lying on each side of the main axis being at 1 least equal to the width of the corrugation, the remainder of the corrugation beyond the initial curved path following either a straight line or a gentle curve.
By the term point of entry I mean the end of the corrugation at which liquid normally enters the packing.
By the term main axis of the corrugation I mean the line of the apex of the corrugation if it followed a straight path from the point of entry.
By the term width of corrugation I mean the distance between the apices of two adjacent corrugations.
I prefer to use in the packings of the invention cor-.
rugated sheets having corrugations which are displaced equally about the main axis since in this case approximately equal amounts of liquid will contact each surface of the corrugated sheet, thereby providing a large surface of the liquid to the elfec-t of the air current.
The invention is illustrated but in no way limited by reference to the three embodiments shown in the accompanying drawings wherein:
FIGURE 1 is an elevation of one corrugation of a corrugated sheet of the first em bodiment.
'FIGURE 2 is an elevation of one corrugation of a corrugated sheet of the second embodiment.
FIGURE 3 is an elevation of one corrugation of a corrugated sheet of the third embodiment.
I .FIGURE 4 is a perspective view of a packing of the third embodiment in which the corrugated sheets have corrugations similar to those in FIGURE 3.
FIGURE 5 is a perspective view of a packing similar to that shown in FIGURE 4 except that the corrugations of one corrugated sheet curve in the opposite direction from the corrugations of the next corrugated sheet.
FIGURE 6 is a vertical section-a1 vie-w of a gas-liquid contact apparatus containing a plurality of the packing units of the present invention.
In FIGURES 1 to 3 corrugations are shown each one having two sides 1, 2 and an apex 3. The two sides form a V at the apex with an included angle of 60. The liquid normally enters the corrugation at 4 in the direction of the arrow, and so 4 represents the point of entry. If the corrugation was not curved, the apex 3 would lie along the line 5 in each case and so line 5 is the main axis of the corrugation.
In FIGURE 1 the corrugation has a curved portion 6 and a linear portion 7. This linear portion is displaced from the main axis 5 by the distance A. In this emibodiment this distance A is made equal to the width of the corrugation which was hereinbefore defined as the distance between the apices of adjacent corrugations. This width of the corrugation may also be defined as that distance represented by distance B in FIGURE 1. Thus distance A equals distance B in the embodiments shown in FIGURE 1, but in other embodiments the distance A may be greater than distance B. All the liquid entering, in the direction indicated by the arrow, the V formed by the sides 1 and 2 of the corrugation at the point of entry 4, must contact the surface 1 of the corrugation between the points 8 and 9 and so no liquid can fall through the corrugation without contacting the surface 1. This embodiment suffers from the disadvantage that no liquid falls on surface 2 and therefore useful surface area is wasted.
This disadvantage is overcome by using the corrugatiOns shown in FIGURES 2 and 3 where the corrugation is displaced on both sides of the main axis 5. Curve 10 causes the initial displacement from the main axis 5 of an amount equal to the distance C. Curve 11 then causes a displacement on the other side of the main axis 5 of an amount equal to distance D. The sum of distances C and D must be equal to or greater than the width of the corrugation (distance B) if all the liquid entering the V of the corrugation at 4 is to contact a surface. Preferably the sum of distances C and D equals distance B and, to ensure even distribution of the liquid between the surfaces 1 and 2 of the corrugation, distances C and D should be equal. Thus I prefer distances C and D each to equal half of distance B. In this case, liquid entering the V at the point of entry 4 in the direction of the arrow between points 12 and 13 will contact the surface 2 of the corrugation between points 12 and 14. Liquid entering the V between points 13 and 15 will contact surface 1 of the corrugation between points 16 and 17. If equal distribution of the liquid over the point of entry 4 is assumed, then equal distribution of the liquid on to surface 1 and 2 will result.
In FIGURE 3 the remaining portion 18 of the corrugation is gently curved until the exit point 19 is lined up with the point of entry 4. In this case, the packings may be installed directly above one another as opposed to the necessary displacement between layers when packings using the form of corrugation of FIGURES l and 2 are used. Furthermore, since the entry and exit points are lined up the packing can stand stably without the need for supporting members.
The main curved portions of the corrugation should only occupy a small portion of the length of the corrugation in order that the greatest possible area of the surface of the corrugation may be used for cooling and the like.
In FIGURE 4 three layers of corrugated sheets 20, 21, 22 are shown interleaved with three flat sheets 23, 24, 25. The corrugations of the corrugated sheets have the form of the corrugation shown in FIGURE 3. The laterally protruding parts 26, 27, 28 and 29 of the corrugated sheets fit into the corresponding free spaces in adjacent packings.
The packings are made up from alternate corrugated and flat sheets. Alternate corrugated sheets may be arranged in such a way that either the curved portions of the corrugations all curve in the same direction as in FIGURE 4 or the curved portions of one corrugated sheet curve in the opposite direction to the curved portions of the corrugated sheet on the other side of that flat sheet. This latter arrangement is shown in FIGURE 5 wherein two corrugated sheets are shown fixed on opposite sides of a flat sheet. Only one corrugation of each sheet is shown.
One corrugation 30 of a corrugated sheet is shown fixed to the front face 31 of a flat sheet 32. The corrugation has the form shown in FIGURE 3. A second corrugated sheet is fixed to the rear surface 33 of the sheet 32. One corrugation 34 of this second corrugated sheet is shown. This second corrugation 34 also has the same form as that shown in FIGURE 3. The points of entry and exit of the two corrugations 30, 34 are aligned and the three sheets are fastened together by press studs and sockets preformed in the sheets at the points encircled and numbered 35. It will be noticed that each of these points corresponds to the points where, if the fiat sheet were omitted, the two corrugations would contact each other. The points encircled and numbered 36 correspond to points where the corrugations shown are fastened to the corrugations forming the remainder of the two c-orrugated sheets.
FIGURE 6 illustrates schematically a gas-liquid contact apparatus, such as a cooling tower, comprising a vertical hollow tower structure 50 containing a plurality of the packing units 52 of the present invention suitably supported within the tower structure. In operation of the apparatus liquid enters the top of the tower structure and flows downwardly over the surfaces of the packing units 52 while cooling gas passes upwardly through the passages in the units 52.
When packings are made from sheets having the corrugations hereinbefore described, each packing has a low resistance to air pressure blowing in the direction opposite to the flow of liquid.
Suitable methods of fixing the components together are described in my aforesaid Patent No. 3,260,511.
The flat and corrugated sheets may be made from any rigid material such as metals, asbestos cement or rigid thermoplastic materials. I prefer to use organic thermoplastic materials since these are generally lighter and more readily processable than other sheet materials. Suitable organic thermoplastic materials include polyvinyl chloride, polymethyl rnethacrylate, polypropylene, high density polythene, 'polyvinylidene chloride, copolymers of vinyl chloride and vinyl acetate, polystyrene, oxymethylene polymers, rubber/resin compositions (e.g. mixtures of butadiene/acrylonitrile copolymer rubbers and styrene/ acrylonitrile resins).
The packings of my invention may be used for cooling many liquids and are particularly useful for corrosive liquids, the material of the packings being selected for resistance to corrosion from the liquids that will be encountered.
They may also be used where it is desirable to contact a large surface with a liquid while presenting a relatively small bulk. Such applications include the treating of effluents with microorganisms.
1. A gas-liquid contact unit for apparatus in which a gas stream contacts a film of liquid flowing as a film over the surfaces of a contact unit, said unit comprising:
alternate flat and corrugated Sheets of rigid thermoplastic organic polymeric material stacked in contact,
the corrugations of each corrugated sheet having apices forming lines of contact with the flat sheets; all the corrugated sheets defining with all the flat sheets a plurality of passages all of which extend from one common face of the stack to the opposite face;
the corrugations in the corrugated sheets following a curved path over a minor proportion of their length such that a straight line through said passages is intercepted by said curved path of said corrugations.
2. Gas-liquid contact apparatus for contacting a gas stream with a film of liquid flowing over contact surfaces within the apparatus, said apparatus including at least one contact unit as claimed in claim 1.
3. A packing unit is in claim 1 wherein said corrugations are generally V-shaped.
4. A packing unit as in claim 1 wherein said curved paths defined by said corrugations are located near one end of said corrugations, and wherein the remainder of said corrugations are substantially straight.
5. A packing unit as in claim 4 wherein each of said corrugations in the region of said curved path has a main axis from which the apex of the respective corrugation is displaced, the maximum displacement being at least equal to the distance between apices of two adjacent colrugations.
6. A packing unit as in claim 1 wherein said curved paths defined by said corrugations are located near one end of said corrugations, and wherein the remainder of said corrugations follow a gentle curve.
7. A packing unit as in claim 6 wherein the curved corrugations in one corrugated sheet curve in the opposite direction from the curved corrugations in the corrugated sheet which is on the opposite side of the common fiat sheet.
equal to the distance between apices of two adjacent corrugations.
(References on following page) 5 6 References Cited 3,112,184 11/1963 Hollen-bach 161-68 X UNITED STATES PATENTS 3,262,682 7/1966 Bredberg 26129 5/1894 Leaver 161136 FOREIGN PATENTS 23;; Z 5 238,412 9/1911 Germany.
2/1941 450,524 4/ 1935 Great Britain.
6/1942 Farr 875,611 8/1961 Great Britain.
1(5); SimQnS. FRANK W. LUTTER, Primary Examiner.
5/ 1961 Kramig 261112 X E. H. RENNER, Assistant Examiner.