GB2132503A

GB2132503A - Packing element for a biological filter or for use in mass transfer

Info

Publication number: GB2132503A
Application number: GB08332260A
Authority: GB
Inventors: Alpo Hypponen
Original assignee: Aaltosen Tehtaat Oy
Current assignee: Aaltosen Tehtaat Oy
Priority date: 1982-12-23
Filing date: 1983-12-02
Publication date: 1984-07-11
Also published as: DE3346558C2; FI66824C; FI824431L; FI66824B; DE3346558A1; GB8332260D0; FI824431A0; GB2132503B

Abstract

A horizontally positioned packing element for a biological filter or for use in mass transfer, comprising one or more rims providing trickling faces (1, 2) along which a liquid or gas is arranged to flow in contact with another medium, e.g. oxidizing air. Trickling faces (1,2) are angled at 1 DEG -50 DEG , preferably 5 DEG -15 DEG , with respect to the intended main flow direction of the liquid or gas to be treated. The diameter of said packing element is greater than its height. At least one side of the packing element is provided with a depression (8). The number of rims may be 1-5, and these may be circular, elliptic, or square in cross-section, or may be a continuous wound spiral, the rims are joined by webs (4), and may have reinforcing webs (3), all of these being rounded off at their extremities (5). <IMAGE>

Description

SPECIFICATION Packing element for a biological filter or for use in mass transfer The present invention relates to packing element for a biological filter or for use in mass transfer, said element comprising one or more preferably concentric rims, along whose trickling faces the liquid or gas to be purified is caused to flow in contact with another medium, e.g.

oxidizing air, said trickling faces being angled at about 1 to 500, preferably 5 to 150 with respect to the vertical axis of said packing element providing large wet surfaces and the diameter of said packing element exceeding the height thereof.

Operation of a biological filter is based on the activity of micro-organisms occurring on the surface of the packing element in a filter. The effluent to be purified is evenly distributed upon the biological filter for packing elements. Effluent trickles down the surface and comes into intimate contact with upwardly flowing air.

A biological filter can be employed as a pretreatment stage or an actual biological treatment depending on loading. A biological filter system can be made more complete with chemical treatment.

Filters of the past were usually filled with rocks but those have been discarded mainly because of their poor efficiency, clogging hazard and great weight.

A more extensive application of biological filters has heretofore been impeded by the high price of filter material. However, plastic packing elements have changed this situation and made the use of biological filters more economical.

British Patent publication No. 1 498 360 discloses a plastic packing element comprising a cylindrical body fitted with a plurality of inclined ring elements mounted within each other. Since these packing elements are intended to be introduced into a filter vessel quite randomly, said ring elements are provided with relatively large openings and voids so that liquid can trickle as freely as possible through the layer formed by said packing elements. This means, however, that there will be no intact surfaces of substantial size in any of the packing elements along which liquid could trickle in contact with oxidizing air.

British Patent publication No. 1 439 745 also discloses ,filter packing element comprising a tube member which is provided with various spacing and filling means and whose wall can be perforated. The tube is of relatively great length and the fitting thereof in a filter may cause clogging of the flow.

Our Finnish Patent publication 62 274 further discloses a disc-shaped packing element provided with a plurality of concentric rims and whose central portion is thicker than its edge portions.

This prior art packing element can be well positioned nearly horizontally, the trickling faces formed by said rims setting in a preferred angle with respect to the liquid flow.

An object of the present invention is now to provide a packing element for utilizing as efficiently as possib!e a scrubbing tower space and for preventing the liquid flow from channelling.

According to the present invention there is provided a packing element for a biological filter or for use in mass transfer, comprising a body of disc-like form having one or more rims having trickling faces along which a liquid or gas to be purified is arranged to flow in contact with another medium, e.g. oxidizing air, said trickling faces being angled at about 10--500, preferably 50--1 50 with respect to the vertical axis of said body the width of said body exceeding the height thereof, the top and/or bottom side of said body being provided with a depression. By virtue of said depression, the trickling faces of superimposed packing elements are not in full contact with each other. Thus, the liquid flow has interceptions which prevent the undesired channelling of liquid flow.

In a preferred case, the height of a packing element decreases towards its central portion.

The horizontal positioning of a packing element is facilitated by per se known rounded projections provided on the outer rim of said packing element.

The trickling surfaces of the packing element preferably comprise a plurality of concentric circular, elliptical, triangular, quadratic, polygonal rims connected by intermediate ribs. Such arrangement provides as large a continuous trickling surface area as possible and the wet surface of said element will be of substantial area.

In a preferred embodiment of the invention the number of rims is 1 to 5.

Efficiency of the packing element can be further increased by various treatments of trickling surfaces. The surface can be roughened, patterned, grooved, provided with ridges, projections or ribs. They can also be perforated or notched or provided with various openings.

Naturally it is also possible to combine two or more of the above-mentioned surface patterns.

The invention will now be described in more detail with reference to the accompanying drawings, in which: Figure 1 shows a packing element of the invention in cross-section; Figure 2 is a plan view of the packing element of Figure 1; Figures 3 and 5 to 7 show embodiments of the invention in cross-section; Figure 4 is a plan view of one embodiment of the invention; Figure 8 shows a helical packing element; and Figure 9 shows various surface patterns.

Figures 1 and 2 illustrate the main principles of a packing element of the invention. As viewed from above, the packing element comprises a disc-shaped element having an outer rim 1 and inner rim 2 connected by radial connecting ribs 4.

Outer rim 1 is further provided with radial reinforcement ribs 3 located between connecting ribs 4. Ribs 3 and 4 extend beyond rim 1 and their projecting portion 5 is rounded. Ribs 3 and 4 also define the outline of said element as viewed in cross-section. In the embodiment shown in Figure 1, the height of the element increases towards the outer rim providing depressions 8 on the top and bottom side of said packing element.

Rims 1 and 2 are mounted at an inclined angle relative to the vertical axis so that a liquid to be purified can trickle along both the top and bottom side of surfaces 1 and 2 whereby a most effective use of the entire surface of the rims becomes possible. Angle of inclination of 1--500, preferably 5-1 So, which has been found out experimentally. If the angle of inclination is considerably greater, the liquid flow disengages from the underside of the surface, particularly with major flow rates, in which case the wet surface naturally decreases in area.

Figure 3 is a cross-sectional view of another embodiment of the invention in which a discshaped packing element is provided with two auxiliary rims 6 and 7 in addition to the outer and inner rims 1, 2. The rims connecting ribs 4 as well as reinforcement ribs 3 extend outer rim 1 by their rounded portion 5.

Figure 4 shows a packing element whose rim configuration is quadratic. Even in this case, the outer and inner rims 1 and 2 are connected by connecting ribs 4 whose ends are provided with rounded portions 5 projecting beyond said outer rim 1.

Figure 5 illustrates an embodiment of the invention in which the top surface 9 of a packing element rises upwards and the bottom surface 8 is depressed. In this case, both the bulge and depression are conical so that the apexes locate in the central portion of a packing element aligned with each other and even so that the surfaces are parallel. Within the scope of the invention, it is obviously possible for the shapes of bulge 9 and depression 8 to be different.

Figure 6 shows an embodiment of the invention in which the top surface 10 is flat and bottom surface 8 depressed as viewed in cross-section of a packing element.

The embodiment shown in Figure 7 complies with the packing element shown in Figure 3, except that the upper and lower edges of trickling surfaces 1, 2 and 6, 7 are provided with ducts 11, 12 which follow the rims and open upwards and downwards. The purpose of these ducts is to improve the liquid distribution on a packing element.

Figure 8 shows an embodiment of the invention in which a packing element is viewed from above.

in this embodiment, the trickling surfaces are combined into a single continuous surface which has been given a helical shape 13.

Figure 9 illustrates three different surface patterns. The purpose of this surface pattern is to obtain a more effective contact between liquids or gases and liquids on a packing element. The trickling surfaces of a packing element can be provided with the patterns shown in Figure 9, i.e.

with various coggings, knurlings or grooves. It is also possible to roughen said trickling surfaces.

It is envisaged that the shape of a packing element may differ from those described with regard to its configuration and the number of rims as well as connecting and reinforcement ribs. A preferred number of rims is 1-5 but naturally the number may be greater. In the described embodiments, the inclination of rims is opposite in adjacent rims. It is possible however to arrange the rims so as to be parallel.

A packing element of the invention is intended for use in biological filters but of course such packing elements can be used for mass transfer in general, e.g. in various tower scrubbers.

Claims

1. A packing element for a biological filter or for use in mass transfer, comprising a body of disclike form having one or more rims having trickling faces along which a liquid or gas to be purified is arranged to flow in contact with another medium, e.g. oxidizing air, said trickling faces being angled at about 10--500, preferably 5a#1 50 with respect to the vertical axis of said body the width of said body exceeding the height thereof, the top and/or bottom side of said body being provided with a depression.

2. A packing element according to Claim 1, wherein the height of said body decreases towards its central portion.

3. A packing element according to Claim 1 or 2, wherein that the one side of said body bulges upwards and its opposite side is depressed, said sides being preferably parallel.

4. A packing element according to Claim 1 or 2, wherein one side of said body is flat and the opposite side is depressed.

5. A packing element according to any of the preceding claims, wherein said trickling faces are helically combined into a continuous surface.

6. A packing element according to any of Claims 1 to 4, wherein said trickling faces are concentrically arranged.

7. A packing element according to Claim 6 wherein said trickling faces are roughened or surface patterned.

8. A packing element according to Claim 6 or 7, wherein the outer portion of the body is defined by rounded projecting portions.

9. A packing element according to any of the preceding claims wherein at least some of the trickling faces are provided with one or more ducts.

10. A packing element according to Claim 9, wherein the ducts are mounted on the upper and lower edges of said trickling faces and are open upwards and downwards, respectively.

11. A packing element according to Claim 9 or 10, wherein the bottom of the ducts are provided with openings.

12. A packing element substantially as described with reference to and as illustrated in any of the accompanying drawings.