GB2055612A - Packing element for column apparatuses - Google Patents

Abstract

A column packing element is a profiled ring 1 having one end 2 circular and the other end 3 oval or an ellipse. The ratio of the area of the circular end to that of the oval end is from 1.2 to 3.0. In the side face of the element and symmetrically to its axis there may be at least two cut-outs forming tongues bent towards the axis of the ring and between the ends of the tongues there may be a slot 2 to 5 mm wide. <IMAGE>

Description

SPECIFICATION Packing element for column apparatuses This invention relates to packing elements for column apparatuses, particularly absorption columns, t be used for the mass transfer of aggressive agents.

Various structures of packing elements have already been developed in order to optimize the processes of heat and mass transfer.

From the prior art there have already been known and used for a long time annular elements, such as Raschig rings with smooth and grooved surfaces and various modifications thereof, Lessing rings with a single or double partition, Dixon rings made of a wire gauze with or without a partition, Pall rings with rectangular cutouts in the side face arched towards the axis, and Forming rings with a partition and with circular cutouts in the side face.

Polish Patent Specifications No. 100 674 and 100 716 disclose column packing elements made of a single ring, or of a plurality of concentric rings, with perforated side faces and a combination of trapezoidal-cylindrical inserts situated inside the said ring, or of a vane and links situated radially between the said rings.

Polish Patent Specifications Nos. 88 110, 88 476, 93 153 and 99 846 disclose packing elements made of partial rings with strips cut along the side face edge, or in the side face bent in the shape of half-rings, or along a broken line towards the centre of the said ring.

Polish Patent Specifications Nos. 55 193, 83 1 50 and 101 1 35 disclose rings provided with cutouts in the shape of isoceles triangles with triangular sectors bent towards the centre of the ring, or with additional cutouts in the said sectors bent at an arbitrary angle towards the centre of the ring. The said sectors form open flow planes covering the section of the ring in the free flow space.

Polish Patent Specification No. 77 366 discloses spiral-like packing elements having the shape of an open geometrical solid, or a truncated open cone, possessing stiffening cutouts and indentations in the side faces, serving as flow turbulators.

Also used are packing elements in the shape of Berl saddles, or Intalox saddles and spirally wound strips for fixing the spacing of the strip coils.

All the above mentioned rings, both the smooth ones and those provided with partitions, have a common drawback consisting in a non-uniform distribution of the liquid over the entire packing height and considerable resistance to the gaseous phase.

The rings with developed surfaces in the shape of cutouts with a small ratio of the hole area to the total outer ring area, e.g. the Pall and Bialecki rings, do not ensure a free flow of the gaseous phase into the ring. Consequently, a large amount of gas flows round the rings on the outer side and the developed inner face only insignificantly participates in the mass transfer process.

The packing elements with a large degree of development of surface ensure better conditions of contact of the liquid and gaseous phase, but on the other hand, they are hardly obtainable and have lower mechanical strength and thermal resistance.

The other rings so far known lead to the appearance of numerous undesirable chimneys because of non-uniform liquid and gas distribution. However, they retain some amount of liquid which does not participate in the mass transfer process and allow a free flow of the liquid streams.

This invention has been aimed at the development of a simple and cheap packing element having a considerable mechanical strength, low resistance to flow and a continuous and uniform distribution of the liquid phase on the packing surfaces.

The invention consists in designing a packing element in the shape of a profiled ring obtained by an appropriate deformation of a simple ring, having one circular end and one oval or elliptical end. The cross section area in a plane perpendicular to the axis of the ring varies smoothly from the circular end to the other end as a function of the height of the ring. The ratio of the area of the circular end to the other end is from 1.2:1 to 3:1.

In the side face of the ring there are preferably at least two opposite cutouts, preferably of an oval shape, and the two tongue sectors thus obtained are deflected towards the ring axis; between the deflected ends of the tongue sectors there should be a gap of a constant width, preferably in the range 2 to 10 mm.

The area of the said cutouts in the side face preferably ranges from 5 to 1 5 percent of its total outer area.

The ends of the deflected tongue sectors are located approximately at mid-height of the said ring.

Packings according to this invention are of simple design and low production costs, compared with those of the known annular elements having developed surfaces.

The column packings composed of the present elements are characterised by a small resistance to the gaseous phase, a uniform distribution of the liquid and high absorptivity.

These gackings also allow high loadings with gaseous and liquid phases to be used with a forced continuous renewal of the phase contact surface. In the described packings there are also no dead spaces, no channeling, and no retaining of liquid on the surfaces of the ring. The packing has a high mass transfer efficiency.

Embodiments of the invention are shown in the accompanying drawings, wherein, Figure 1 is an axial vertical section of a packing element, Figure 2 is a section on line A-A of the packing element shown in Fig. 1, Figure 3 is a top view of the packing element, Figure 4 is a bottom view of the packing element, Figure 5 is an axial vertical section of a packing element with cutouts, Figure 6 is a section on line B-B of the element shown in Fig. 5, Figure 7 is a top view of elements as shown in Figs. 1 to 4 representing a portion of a packing layer, Figure 8 is a section on line C-C of a portion of a packing layer shown in Fig. 7, Figure 9 is a top view of a portion of another packing layer, and Figure 10 is a section on line D-D of a portion of the packing layer shown in Fig. 9 As may be seen in Figs. 1 to 4, the packing element is made in the form of a shaped ring 1 obtained by a deformation of a simple (plane) ring.

The ring 1 has one circular end 2 and one oval (or elliptical) end 3 situated in parallel planes perpendicular to the axis of the ring.

The side face 4 of the said ring forms a spherical surface passing smoothly from the circular end 2 to the other end 3. The slope of the side face 4 is determined by the magnitude of deformation of the simple circular ring one end of which has been shaped in such a way that it possess a symmetrical oval contour. The ratio of the area of the circular ring surface to the oval area representing the so called dynamic coefficient of packing ranges within the limits from 1.2 up to 3.0. The area of the cross section perpendicular to the axis of the ring changes smoothly from one end to the other.

Another packing element is shown in Figs.

5 and 6. In this packing element, there are two opposite oval cutouts 5 in the side face 4.

The ends of the tongue sectors 6 thus obtained are bent towards the axis of the ring, and between the edges of the said ends there is a slot s ranging in width from 2 to 10 mm.

The tongue secotrs can have a shape resembling any geometrical figure, e.g. a halfcircle, triangle, trapezium, etc.

The area of the said cutouts 5 is 5 to 1 5 per cent of the total area of the side face 4 of the said ring.

The bent ends of the tongue sectors 6 are situated approximately at the mid-height of the ring 1.

The number, size and shape of the said -tongue sectors 6 determine the degree of covering of the through surface of the ring, this exerting an essential influence upon the uniform distribution of the liquid after packing and producing an optimum contact surface between the liquid and gaseous phase.

The packing elements are laid alternately in rows thus forming successive packing layers 7' and 7" as shown in Figs. 7 and 8 wherein the individual rings 1 are in contact with each other at four points lying on generatrices. The adjacent layers 7' and 7" are offset relative to one another by a distance equal to half the inner diameter of the circular ends of the rings.

The rings 1 can also be arranged in the adjacent layers in such a way that the ends 3 are in contact with the circular ends 2 and vice versa, the individual rings in the various layers being coaxial with one another. In both the aforementioned arrangements the packing fully covers the flow area thus creating favourable mass transfer conditions.

In still another packing system, shown in Figs. 9 and 10, the rings 1 are arranged in the adjacent layers 7 in such a way that in a vertical plane along the axis the successive rings 1 are in contact at their circular ends 2 and at their oval ends 3 thus forming separate vertical ducts 8 with a uniformly widening and narrowing cross section. In the individual layers 7 the rings 1 are in contact with each other along lines lying on the side face as in Fig. 8.

Still another design consists in making tubes (shaped tubes) of an arbitrary length with a gradually changing cross section area from the said rings 1; from the said tubes similar column packings can be obtained.

The liquid supplied to the packing from above is uniformly distributed over the outer and inner coned surfaces of the rings thus ensuring an intensive renewal or regeneration of the contact surface with the gaseous phase introduced in the upstream direction from below. The varying cross section areas of the rings along the successive packing layers produce an effect similar to that produced by a system consisting of confusers and diffusers.

in consequence, the streams of the liquid and gasseous phase are alternately speeded-up and slowed down which intensifies the mass transfer.

The dynamics of flow varies in terms of the magnitude of deformation of the rings 1 and is determined by the coefficient of dynamics, that is by the ratio of the circular cross section area of one end of the ring to the oval or elliptical cross section area of the other end.

In this way, by modifying appropriately the shape of the rings, a type-series of rings of given dynamic characteristics can be obtained adapted to packings for definite mass transfer conditions and various media.

The packing elements according to this in Invention can be used as a component part of a laid-in packing with an orderly arrangement in the section of the column.

The above mentioned elements can also be used, either as poured packings, or as structural type packings by forming in the said packings systems of rigid annular blocks producing the individual layers in the columns.

This can be obtained either by connecting the side faces of the said packing elements so that they form flat (two-dimensional) systems, or by connecting their bases so as to obtain profiled tubes.

The packing elements can also be used for other means and heat transfer processes, for instance in distillation, rectifying and extraction columns.

Rings 1 can be made of various materials, e.g. metal, plastics, glass, ceramic material.

Claims (7)

1. A column packing element comprising a packing ring having at one end a circular cross section and at the other end an oval cross section, the cross section of the ring varying gradually from one end to the other, and the ratio of the area of the one end to that of the other end being in the range 1.2:1 to 3:1.

2. A packing element as claimed in claim 1 having a perforated wall.

3. A packing element for column apparatuses, especially absorption columns to be used for the mass transfer of aggressive agents, made of an arbitrary material in the shape of a profiled ring, characterised in that one end of the said ring has a circular shape, whereas the second end has a shape of an elongated ellipse, the cross section area in a plane perpendicular to the axis of the said ring varying gradually from one end to the other, and the ratio of the area of the circular end to that of the elliptical end ranging within the limits from 1.2 to 3.0.

4. A packing element as claimed in claim 1 or 3 in which in the side face of the ring there have been cut at least two opposite tongues bent towards the axis of the ring and between the ends of the said tongues there is a slot having a width of 2 to 10 mm, the area of the cutouts ranging from 5 to 1 5 per cent of the total outer area of the side face.

5. A packing element as claimed in claim 4 in which the tongues are oval.

6. A packing element as claimed in claim 4 or 5 in which the ends of the bent tongues are situated approximately at the mid-height of the ring.

7. A column packing element substantially as herein described with reference to the accompanying drawings.