GB1602182A

GB1602182A - Tower packaging element

Info

Publication number: GB1602182A
Application number: GB2009877A
Authority: GB
Original assignee: LEVA M
Current assignee: LEVA M
Priority date: 1977-05-13
Filing date: 1977-05-13
Publication date: 1981-11-11

Description

(54) TOWER PACKING ELEMENT (71) I, MAX LEVA, a citizen of the United States of America of 1, Hodgson Avenue, Pittsburgh, Pal 4205, United States of America, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a novel tower packing element for use in random poured packed beds in towers and columns, to bring about mass and heat transfer in gas absorptions, distillations, reactors and similar apparatus extensively used in chemical and physical operations.

The most commonly used packings for such purposes are various sizes of rings and saddles.

Although widely used, these packings all suffer from the same shortcomings, namely, they will not really form truly physically stable packed beds. Thus, in the randomly poured beds composed of rings and saddles, the pieces are not truly individually interlocked and will, therefore, with time, continue to shift and settle in the towers. This shortcoming has the obvious disadvantage that the flow resistance, which these beds will offer to the fluids that are passing through them, will steadily increase.

Pressure drops and energy requirements for pumping are, therefore, very difficult to predict in advance for such packings, with any great degree of assurance, because these quantities are forever changing.

Another severe shortcoming of the various ring and saddle packings is due to the fact that the beds, formed by these packings, are not truly homogeneous in their texture.

With rings, one always finds large numbers of the pieces aligned in tandem arrangement.

This tandem arrangement is particularly objectionable because a channel is thus formed that is ideal for passing the liquids downwardly, and the liquids are thereby often entirely separated from the gas phase that moves along somewhere else. This separation of flows, which is virtually impossible to control and prevent, is one of the reasons why the contacting efficiencies of these packings are not accurately predictable. Furthermore, this separation of the phases results, in all instances, in a low contacting efficiency.

With saddles, the pieces tend to "nest", which is a generally accepted term with saddles, to indicate the pieces will build up into stacks, the individual pieces fitting into each other snugly and preventing large portions of the packing surfaces to become accessible to the flowing liquid and gas phases. Obviously, nesting is, therefore, a major cause of poor contacting efficiency. Thus it is seen that the usual ring and saddle packings offer, in their randomly dumped beds, substantial regions of high and low local packing densities. As already stated, this undesirable situation leads to channeling of the liquids and hence to actual physical separations of the gas and liquid phases. The result is that these packings are much less effective to bring about heat and mass transfer between the liquid and gas or vapour phases than could be achieved if the packings would not encourage this phase separation.

The present invention relates to a modification or improvement of the invention set forth in the Complete Specification of U.K.

Patent No. 1562402. In that Specification was described a tower packing element comprising an open-ended curved strip having an integral tongue struck out from the strip to leave a slot therein and extending away from the plane of the curved strip.

The material of which the packing element was proposed to be constructed was any metal or plastics sheeting, clay or ceramic product or other that permits the formation of the element by various means.

In the Complete Specification of our U.K.

Patent Application No. 2727/78 (Serial No.

1602183) we have disclosed a tower packing element comprising an open-ended curved strip provided with at least one aperture, and a tongue integral with the strip and extending inwardly of the curvature of the strip from one circumferential end of the aperture, the length of the tongue being greater or less than the circumferential length of the aperture.

According to the present invention a tower packing element comprises an open-ended curved strip provided with at least two apertures arranged in a row extending longitudinally of the strip, a row of two tongues of unequal lengths associated with the row of apertures, each tongue being integral with the strip and extending inwardly of the curvature of the strip from one end of the respective aperture, and the arrangement of the tongues being chosen such that they all lie substantially between the curved strip and the chord that extends between the two ends of the strip, and such that the free end of the longer tongue of each row is located on or closely adjacent to the chord.

This arrangement of the tongues prevents substantial inter-penetration of adjacent packing elements yet ensures an adequate density of packing.

Preferably each tongue has been produced by striking the tongue from the strip, but, as disclosed in the Complete Specification of Application No. 2727/78, (Serial No. 1602183) the tongue may not have been produced from the material of the strip but could be formed by moulding for example.

Preferably there are three apertures in each row, and each of the three apertures has an associated tongue.

Although one tongue of the row could extend from the strip in the opposite direction to the other two tongues, preferably all three tongues extend from the strip in the same direction and from the corresponding ends of the apertures.

Preferably said longer tongue is the central tongue, and the length of the central tongue, measured along its surface, is substantially twice the corresponding length of each of the other two tongues of the row.

Preferably there are two parallel rows of tongues and apertures, and the tongues of the two rows extend from the strip in opposite directions.

The strip will usually extend for an arc of between 90 and 1800, an angle of 1800 being preferred.

Preferably two axially displaced and oppositely directed tongues are arranged such that when the tongues are viewed in the axial direction of the element they intersect each other twice, or intersect once and meet again at their free ends.

These intersecting tongues produce turbulance in gas flowing substantially axially of the elements and thus lead to increased contacting of gas and liquid.

Preferably the intersecting tongues constitute said longer tongues of the two rows.

The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: Figures 1 to 5 are axial views of various packing element in accordance with the invention; Figure 6 is a view of the element of Figure 3 looking from the right in that Figure; Figure 7 is a similar view of a modification; Figure 8 shows, for comparison purposes, an element disclosed in the Complete Specification of U.K. Patent No. 1562402; and Figure 9 is a graph showing some typical gas absorption performance data.

Each of the elements of Figures 1 to 5 comprises an oblong-rectangular strip 1 of sheet metal which has been rolled into a semicylindrical shape. The circumferential length of each strip is approximately one and a half times the axial width of the strip. Two parallel rows of three rectangular tongues 2 and 3 have been formed by striking the tongues from the material of the strips to leave two corresponding rows of rectangular apertures 4 and 5 respectively, shown in Figure 6. The root of each tongue, where it joins the curved strip, has been bent through an acute angle from its original position in the strip. In the drawings the tongues and apertures of one row have been identified by the letter a and those of the other row by the letter b. In each of the embodiments of Figures 1 to 5 the elements a of one row extend from the strip 1 in the opposite direction to the tongues b of the other row and in a symmetrical manner to the tongues in the other rows.

It will be seen that, in accordance with the invention, in each of Figures 1 to 5 the tongues lie within a chord connecting the free ends of the curved strip and that in each case the free end of at least one tongue lies on the chord. In Figures 1 to 4 both central tongues 2a and 2b of the two rows of tongues have their free ends on the chord, whereas in Figure 5 two of the tongues 3a and 3b have their free ends on the chord.

In the embodiments of Figures 1 and 3 the central tongues 2a and 2b, as viewed in those Figures, are seen to intersect each other twice whereas in Figure 2 the central tongues 2a and 2b, as viewed in that Figure, intersect once and meet again at their free end. In Figure 4, on the other hand, the central tongues 2a and 2b do not intersect once.

As shown in Figure 6, the curved strip 1 of the element of Figure 3 is formed adjacent to its opposite axial edges with respective longitudinally extending recesses 6 to increase the rigidity of the strip.

Figure 7 shows a modification in which the free ends of the curved strip 1 are each formed with three teeth 7 to increase the number of point contacts between adjacent elements and to help with liquid run-off.

The graph of Figure 9 shows absorption results obtained when the elements of Figures 3 and 8, and conventional pall-type rings, were tested in an experimental tower of 14 inches diameter and carrying five feet of the packing.

The absorption involved the removal of CO2 from air, by using a four per cent solution of NaOH in water. The pall-type rings were of size 1 - 'h inch, which size most nearly corresponds to the sizes of the new packings tested.

All packings were made of carbon steel and were subjected to a gas mass velocity of 500 lb/hr. ft.2, and liquid mass velocities ranging from 400 to 1000 lb/hr.ft.2. As is customary, the absorption performance was reported in terms of so-called absorption coefficient KGa, expressed as lb-moles/hr.ft.3 atm, and shown in relation to the liquid irrigation rate.

It will be seen from Figure 9 that the packing of Figure 3 is substantially more effective than either the previously proposed packing of Figure 8 or the pall-type rings.

Although the elements shown in the draw- ings are each provided with two rows of three tongues, it will be appreciated that with the larger sizes of packing elements employed in industry there may be more than three tongues in each row and that there may be more than two rows of tongues.

WHAT I CLAIM IS: 1. A tower packing element comprising an openended curved strip provided with at least two apertures arranged in a row extending longitudinally of the strip, a row of two tongues of unequal lengths associated with the row of apertures, each tongue being integral with the strip and extending inwardly of the curvature of the strip from one end of the respective aperture, and the arrangement of the tongues being chosen such that they all lie substantially between the curved strip and the chord that extends between the two ends of the strip, and such that the free end of the longer tongue of each row is located on or closely adjacent to the chord.

2. A tower packing element as claimed in Claim 1 in which there are three apertures in each row, and each of the three apertures has an associated tongue.

3. A tower packing element as claimed in Claim 1 or Claim 2 in which the tongues of each row extend from the strip in the same direction and from corresponding ends of the apertures.

4. A tower packing element as claimed in Claim 2 or Claim 3 as appended to Claim 2 in which said longer tongue is the central one of the three tongues.

5. A tower packing element as claimed in Claim 4 in which the length of the central tongue is substantially twice the length of each of the other two tongues of the row.

6. A tower packing element as claimed in any of the preceding claims in which there are two parallel rows of tongues and apertures.

7. A tower packing element as claimed in Claim 6 as appended to Claim 3 in which the tongues of the two rows extend from the strip in opposite directions.

8. A tower packing element as claimed in Claim 7 in which two axially displaced and oppositely directed tongues are arranged such that when they are viewed in the axial direction of the element they intersect each other twice, or intersect once and meet again once at their free ends.

9. A tower packing element as claimed in Claim 8 in which the two intersecting tongues are said longer tongues of the two rows.

10. A tower packing element as claimed in any of the preceding claims in which the strip is of substantially semi-cylindrical shape.

11. A tower packing element as claimed in any of the preceding claims in which at least one end of the curved strip is provided with teeth.

12. A tower packing element as claimed in any of the preceding claims in which-the strip is provided adjacent to at least one of its longitudinal edges with a longitudinally extending recess.

13. A tower packing element as described with reference to Figure 1 of the accompanying drawings.

14. A tower packing element substantially as described with reference to Figure 2 of the accompanying drawings.

15. A tower packing element substantially as described with reference to Figures 3 and 6 of the accompanying drawings.

16. A tower packing element substantially as described with reference to Figure 4 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. terms of so-called absorption coefficient KGa, expressed as lb-moles/hr.ft.3 atm, and shown in relation to the liquid irrigation rate. It will be seen from Figure 9 that the packing of Figure 3 is substantially more effective than either the previously proposed packing of Figure 8 or the pall-type rings. Although the elements shown in the draw- ings are each provided with two rows of three tongues, it will be appreciated that with the larger sizes of packing elements employed in industry there may be more than three tongues in each row and that there may be more than two rows of tongues. WHAT I CLAIM IS:

1. A tower packing element comprising an openended curved strip provided with at least two apertures arranged in a row extending longitudinally of the strip, a row of two tongues of unequal lengths associated with the row of apertures, each tongue being integral with the strip and extending inwardly of the curvature of the strip from one end of the respective aperture, and the arrangement of the tongues being chosen such that they all lie substantially between the curved strip and the chord that extends between the two ends of the strip, and such that the free end of the longer tongue of each row is located on or closely adjacent to the chord.