IL43090A - Tower packing elements - Google Patents

Description

TOWER PACKING ELEMENTS This invention is concerned with packing elements for use in fluid-fluid contact apparatus of the packed tower type.

Fluid-fluid contact apparatus of the packed tower type for effecting mutual gas (vapour)/liquid and liquid/liquid contact is well known.

Basically, fluid-fluid contact apparatus of the packed tower type comprises a tower or other structure contanining one or more beds of packing elements and having means for introducing the fluids to be brought into contact with each other into said bed. In many applications, the fluids are brought into contact in countercurrent flow, the more dense fluid (i. e. th.e liquid in the case of gas (vapour) /liquid contact apparatus) flowing downwardly through the packed bed whilst the less dense fluid (i. e. the gas or vapour in the gas(vapour)/liquid contact apparatus) flows upwardly through the bed. In other applications (e. g. cross-flow cooling towers) the fluids flow are generally at right angles to each other, for example with a liquid flowing downwardly through the bed whilst a gas or vapour flows across the bed. It is not necessary that both fluids be forcibly fed to the bed and thus, for example, in the case of a so-called sewage filtration bed, liquid effluent is irrigated onto the surface of a packed bed through which air is allowed to permeate (usually without forced flow) to permit aerobic biological treatment of the effluent. The present invention is concerned with packing elements for all apparatus in which two different fluids are brought together in a packed bed for some action between them.

A wide variety of packing elements are known for such apparatus, for example, fabricated packings such as Raschig rings, Berl saddles, Intalox saddles and Pall rings. In the case of packing elements such as Raschig rings or Pall rings the beds may be stacked beds, (i. e. beds in which the element are individually placed in position) or dumped beds, ( i. e . beds in which at least a portion of the elements have been dumped in situ in the apparatus). In the case of the saddles the beds will almost always be "dumped"beds.

It is an object of the present invention to provide an improved tower packing member.

Broadly,, the present invention consists in a packing member comprising an open-ended tubular member having a diameter namely its maximum transverse dimension in a plane perpendicular to its length (defined above) greater than its width, namely on the length of a right tube having the same cross-section as the tubular member and having the same surface area as the projected surface of the tubular member on a coaxial right tube of the same cross-section, in vhich the diameter of one end of the tubular member is greater than that of the other end thereof and which has a plurality of radial ribs extending from the centre of the tubular member to the side wall thereof* It has been proposed, see United States Patent No.2,055, 162 to employ packing elements having a height less than their diameter in fluid-fluid contact apparatus, plate-like or ringlike members being particularly mentioned. In that Patent particular stress is laid upon the method whereby the packing elements achieve a regular orientation in the tower. In contrast, the packing elements of the present invention do not have to be introduced in such a manner but may merely be dumped into the tower and when so dumped, the packing elements of the invention take up a more random orientation leading to a low pressure drop and high efficiency in the bed formed of the packing elements. This orientation is due to the presence of the internal ribs a d the configuration of the side walls of the packing elements of the invention, neither of which features are mentioned i the said U.S. Patent.

In the following description reference will be made to the accompanying drawings illustrating packing elements in accordance with the invention, in which:- Figure 1 is a plan view of a packing element in accordancce with the invention:- V Figure 2 is a diametric cross-section through a packing element in accordance with the invention having the plan view shown in Figure 1 and having straight walls; Figure 3 is a diametric cross-section through a packing element in accordance with the invention having the plan view shown in Figure 1 of the drawings and having salient curved side walls; Figure 4 is a plan view of a preferred element in accordance with the invention; and Figure 5 is a diametric section on the line AA in Figure 4· In the drawings the side walls of any tubular member are referred to by the numeral 1, internal radial ribs by the numeral 2, auxiliary tubular members by the numeral 3, apertures in the side walls of the tubular member by the numeral 4 and external ribs by the numeral 5.

The tubular members forming the packing elements in accordance with the invention may have any desired cross-section but are preferably circular in cross-section. The ratio of their diameter to their width is preferably more than 1*5:1 but less than 10si, advantageously the ratio of their diameter to their width will be in the range 2:1 - 5*1 and, particularly, in the range 2:1 ~ 4:1· In general, the ratio of the diameters of the two ends of the packing element is preferably such that the cone angle defined by the two ends is preferably less than 30 degrees* The walls of the tubular element between the ends thereof may be straight (see Figure 1) or curved and when they are curved they may be saliently curved, i. e. curve away from the centre of the tubular member (see Figure 3), or may be re-entrantly curved, i. e. inwardly curved towards the centre of the tubular member,(see Figure 5).

Alternatively, the walls of the tubular member may be comprised of a series of straight elements forming a general curve.

In general, the internal radial ribs in the packing elements of the invention will be planar with the planes thereof parallel to the longitudinal axis of the tubular member and whilst these ribs may have a depth equal to the whole of the width of the tubular member they will preferably have a depth somewhat less than the width of the tubular member say about half the width of the tubular member. The ribs are preferably diametric so that there will be an even number of radial ribs in the member and, thus, there may be four (see Figure 1), six o more (see Figure 4) radial, ribs in the packing element, the number of ribs generally increasing with increasing diameter of the packing element. The packing element may, further, be provided with two or more sets of ribs at different levels angularly staggered with respect to each other (see Figures 4 and 5), in this case the upper set of ribs will preferably bisect the angles formed between the lower set of ribs. Again, it will generally be desirable to have more than one set of ribs as the size and diameter of the tubular member increases and, also, where the ribs are provided in a number of layers they will generally have a lesser depth than ribs provided in only one layer and may, - for example, have a depth of from one quarter to one third of the width of the tubular member. The outer surface of the walls of the tubular member may also be provided with ribs which may be circumferential strengthening ribs (see Figure 5) or may be external extensions of the internal radial ribs .

The walls of the packing elements of the invention are, desirably, apertured, especially in the case of the larger sizes of packing elements (see Figures 4 and 5). These apertures may be provided as a single row of apertures or, in the case of the larger packing elements, as two or more rows of apertures. The shape of the apertures may vary, as desired and thus, for example, the apertures may be circular, oblong, square or rectangular in shape .

The packing elements may .also be provided with subsidiary inner rings joining the internal radial ribs which rings will serve not only to strengthen the element but also serve to break up the flow of gas and/or liquid therethrough to provide and promote desirable turbulence.

The pacldng elements in accordance with the invention will tend to orient when dump/ed in fluid-fluid contact apparatus, so that they will in general, demonstrate an increased capacity and reduce the pressure drop as compared with conventional tower packing elements.

The packing elements of the invention are particularly adapted for manufacture from plastics materials by an injection moulding process and any suitable plastics material may be employed provided, of course, that it is chemically resistant to the materials with which it will come into contact in operation. In particular, the packing elements of the invention may be formed of polypropylene or glass-filled polypropylene.

The present invention also provides fluid -fluid contact apparatus comprising a packed bed and means for introducing fluids to said bed for contact therein in which at least a part of the bed is formed of the packing members in accordance with the invention. In such apparatus the ratio of the diameter of the packing elements to that of the bed is conveniently 1 : 3 or more.

The fluid -fluid contact apparatus of the invention may take any of the forms in which packed beds of elements are utilized to effect fluid-fluid contact; for example may take the form of distillation, absorption, desorktion, water-cooling, biological treatment (e. g. effluent "filtration"), gas - scrubbing, gas-humidification, liquid -liquid extraction apparatus or . general microbiological wash apparatus or combinations thereof.

The bed (s) of packing elements within the apparatus may simply be prepared by dumping the elements into the bed. Where the apparatus is of the cross -flow type it may be advisable to turn the elements in the bed through 90 degrees and this may be achieved by physically turning the bed on a suitable support or by flooding the apparatus.

The invention also provides a method of contacting a fluid with another fluid which comprises bringing the fluids into contact in an apparatus according to the invention.

Claims (8)

•CLAIMS ,φ

1. A tower packing element comprising an open-ended tubular member, preferably of circular cross-section, having a diameter (as hereinbefore defined) greater than its width (as hereinbefore defined) characterized in that the diameter of one end of the tubular member is greater than that of the other end thereof and which element has a plurality of radial, preferably diametric ribs extending from the centre of the tubular member to the side wall thereof.

2. A tower packing element as claimed in claim 1 characterized in that the ratio of the diameter of the tubular element to its width is from 1.5:1 "to 10:1, preferably from 2:1 to 5:1, more preferably from 2:1 tc :1. J.

3. A tower packing element as claimed in claim 1 or claim 2 characterized in that the ratio of the diameters of the two ends of the tubular member is such that the cone angle defined by the two ends is less than 30 degrees.

4. -, A tower packing element as claimed in any one of the preceding claims characterized in that the internal radial ribs are planar with their planes parallel to the longitudinal axis of the tubular member, the ribs preferably having a depth less than the width of the tibular member.

5. A tower packing element as claimed in any one of the preceding claims characterized in that it has two or more sets of ribs at different levels, and angularly staggered with respect to each other.

6. Λ tower packing element as claimed in any one of the preceding claims in which the outer surface of the tubular member is provided with ribs and/or apertures.

7. '.. Λ tower packing element as claimed in any one of the preceding claims characterized in that it is also provided with one or more subsidiary inner rings joining the internal radial ribs.

8. Fluid-fluid contact apparatus comprising a packed bed and means for introducing fluids to said bed for contact therein characterized in that at least a part of the bed is formed of tower packing elements as claimed in any one of the preceding claims. - - -