Liquid And Gas Contact Apparatus

Abstract

Gas and liquid contact apparatus employing a contact fill composed of layers having downwardly inclined folds or pleats crossing one another and bearing against one another in adjacent layers, the folds having vertical cuts near the lowermost edge thereof or being cut off short of the adjacent layer edge so that liquid flowing along the folds changes its direction of flow prior to the liquid reaching the edge.

Description

This invention relates to a liquid and gas contact apparatus.

More particularly this invention relates to a liquid and gas contact apparatus of the type having a contact fill or insert housed in a casing, which fill is composed of layers having folds or pleats crossing one another and bearing against one another in adjacent layers, passageways extending from end to end and formed between said layers being passed simultaneously by the gas in a substantially horizontal direction of flow and by the liquid in a substantially vertical direction of flow.

One example of contact apparatus of the kind in consideration which are operated according to the so-called crossflow principle are cooling towers in which thus the air has a substantially horizontal direction of flow through the passageways, the water passing through the contact fill in substantially vertical direction. Another field of application of the invention are moistening apparatus which are intended to increase the moisture content of the stream of air passing through the apparatus.

It is known in the prior art to provide at the air outlet side of the contact fill separate screens composed of lamellae which are pleated and bear against one another, the folds and the channels formed by them extending with an upward inclination in the direction of flow of the air. Thereby the lamellae at the outlet side guide the air flow in an upward direction with such angle of inclination and otherwise under such conditions that the outgoing air is prevented from entraining water droplets from the interior of the contact fill. Thus, the screens are intended to act as so-called eliminators, which trap these droplets so as to cause them to flow back towards the contact fill. A similar screen may be applied to the air inlet side of the contact fill in the apparatus, but it has then for its main object to prevent daylight from penetrating into the interior of the contact body and thereby to promote nondesired growth of algae or the like on the elements from which the contact fill is built up. According to another proposal emanating from the applicant the lamellae constitute a continuation of, and are integral with, the layers of the fill preferably made of a plastic material, and their folds.

One main object of the invention is to provide an improvement of such contact fills, in particular from the viewpoint of manufacture, when the layers are of less formable material such as impregnated asbestos paper, the sheets with the eliminator at the same time forming an independent unit. According to one main feature of the invention the folds having a downward inclination at the inlet side and if desired also at the outlet side at a short distance from the edge of the layers are formed with cuts extending in vertical direction in such a manner that liquid flowing down along the folds changes its direction of flow at said cut prior to the liquid reaching said edge.

Further objects and advantages of the invention will become apparent from the following description considered in connection with the accompanying drawings, which form part of this specification, and of which:

FIG. 1 is a vertical longitudinal section through a cooling tower embodying the invention.

FIG. 2 is a partial perspective view of a portion of a contact fill forming part of said cooling tower.

FIG. 3 is a partial perspective view of a contact fill according to a modified embodiment.

Referring to FIG. 1, reference numeral 10 denotes a casing of substantially square shape with two opposite openings 12 into which contact fills 14 are inserted. The casing 10 rests on legs 16 and forms at its bottom a sump 18 the water level of which is controlled by a float 20 and which has an outlet 21 controlled by a valve 22 for the cooled water. Air is introduced through the lateral openings 12 according to the arrows 24 into the contact fills 14 and is sucked therefrom in an upward direction through a central portion of the tower by a fan 26 driven by a motor 28 and located in an outlet socket 30. Water is supplied to the contact bodies 14 from above through pipes 32 at the underside of which transverse longish troughs 34 formed with outlet holes and extending along the rectangular front area of the fill may be provided.

The contact fills 14 are composed of vertically positioned thin layers or sheets 36, 38 (FIG. 2) which all of them preferably are formed with pleats or undulations 40, 42 crossing one another in adjacent layer in the inner main portion of a contact fill. The layers may be constituted of paper of cellulose or asbestos impregnated with a substance which by itself or in combination with another substance gives to the paper required mechanical strength, especially in wet condition. A suitable substance is a resin, such a phenol-formaldehyde resin.

The pleats or folds 40 and 42, respectively, cross one another and bear against one another so as to form between the sheets channels or passageways with continuously varying width both in vertical and in horizontal direction. This will result in that the gas or the air will in the interior of the contact fill come into contact with the water flowing from the top of the fill along the layers under the most favorable flowing conditions to bring about a high yield such as an effective cooling of the water.

The height of the pleats or folds and therewith the average spacing between the layers may amount to 5-10 mm. and more, such as up to 20 mm. The layers 36, 38 of the contact fill may be united together at the places of contact by means of a particular glue. In the inner main portion of the layers these places of contact have the form of points, since the folds 40, 42 cross one another. In the embodiment shown the folds have relatively sharply bent ridges and the intermediate portions between the ridges and the valley bottoms are plane or slightly curved only. The folds may, however, also have some other configuration such as that of a gentle sinus line.

According to FIG. 2, those layers or sheets the folds or pleats of which have a downward inclination in the direction 24 of the gas flow are formed with one or several vertical rows of slots 46 located close to the vertical outlet edge 44 of the contact fill. At the gas inlet edge 48 the folds of the same layer may, however, be uninterrupted. In the same manner the intermediate layers 36 may be provided with one or several vertical rows of slots 50 close to the gas inlet edge 48. The individual slots 46 and 50, respectively, extend suitably on both sides of the ridges or valley bottoms of the folds or pleats.

In operation of a cooling tower the water supplied from above is distributed over the layer surfaces at their folds 40, 42 crossing one another, and flows downwards within the contact fill, while meeting the air streaming in a horizontal main direction of flow. Thereby the water is cooled by evaporation of a minor portion thereof into the air. The cooled water is collected in the sump 18 and withdrawn through the pipe 21 to the place of utilization. When the water at that place has been warmed up again it returns through the conduit 32 to the top of the cooling tower.

Due to the slots or perforations 46 at the outlet side of the contact fill water particles are effectively prevented from becoming entrained out from the cooling tower by the gas stream. As a matter of fact the downward inclination towards the outlet edge 44 of the folds 38 promotes a flow of water along said folds, but when the water meets a slot 46 it will change its direction of flow and instead stream downwards within the interior of the fill proper. The same holds true with regard to the slots 50 in the layers 38. The dimensions of the slots formed in the layers must be chosen with due regard to actual surface tension forces which tend to bridge over the open area of the slots. The slots 46 and 50, respectively, in a pair of adjacent rows are formed on both sides of the pleated layer so that all ridges and bottom valleys are cut open by said slots.

In the embodiment shown in FIG. 3, the layers 38 the folds 42 of which in the direction of the gas stream 24 are directed downwards towards the outlet side 44, are cut off along a cutting line 52 located at a minor distance from the outlet edge 44. The portions thus cut off form ribs 54 which are turned so that their folds 56 have an upward inclination in the direction of the gas stream towards the air outlet edge 44. To ensure that these strips 54 the folds 56 of which now become parallel to the folds 40 in the adjacent layers 36 do not slide down into said folds, narrow thin spacing ribbons 58 or similar elements may be interposed between the strip 54 and at least one of the adjacent layers 36. The ribbons 58 may be cemented together with the strip 54 or said layer 36 by means of some suitable binding agent. Also along the inlet edge 48 the edge portions of the layers 38 may be cut off along a line 59 and be replaced by strips 60 the folds of which in a similar manner extend upwardly towards the edge 48. These strips may be retained in position by means of spacing ribbons 62.

Water following the pleats or folds 42 and 40 in the downward direction is prevented by the strips 54 and 60, respectively, to flow out from the vertical edge of the contact fill. Instead, the water flows downwards at the transition between the layers and the strips, and as far as the water particles are entrained upwards on the strips, the folds thereof create a counterforce which guides the water back into the interior of the fill. The lateral deviations of the water reach obviously a maximum value at the outlet side of the contact fill for the gas stream where the folds there have a downward inclination, since the flow components of the water and the gas coincide here.

The strips 54 and 60, respectively, are housed within the outer contour of the contact fill and form part of the coherent unit formed by the layers 36, 38.

If the contact fill in a similar manner as in the embodiment shown in FIG. 3, has separate strips 60 with inverted folds at the air inlet side also, said strips also counteract penetration of sun rays into the interior wetted portions of the fill, whereby algae and similar micro-organisms are given unfavorable growing conditions. In comparison to the known embodiment described at the outset of this description the additional advantage is obtained with the invention that any collection of water in the edge portions with losses in pressure on the gas side resulting thereof are eliminated totally.

In the embodiments shown the layers 36, 38 are of mutually identical shape. The crossing of the inner folds or pleats 40, 42 is solely brought about by turning each second layer by 180.degree. about a vertical central plane through the contact fills which stand transversally to the plane of the drawing.

Especially in connection with moistening apparatus it is of great importance that the layers are water absorbing which property is obtained by impregnation with a phenol-aldehyde resin, for example. In the edge portions where the slots 46, 50 and the strips 54 and 60, respectively, are located it is to the contrary advantageous that the layers do not absorb water by capillary force because here no cleaning by flushing with water will occur, so that a continuous evaporation of water would result in precipitation of salts and similar "minerals" carried along with the water which may gradually clog the passageways between the layers. For this reason it is advantageous to give these edge portions nonabsorbing or water repelling properties by impregnation with a suitable agent such as a solution of neoprene rubber.

The water supply to the contact fill may to advantage be conducted intermittently, for example by filling troughs with water and thereafter emptying the same more or less instantaneously.

While several more or less specific embodiments of the invention have been shown and described, it is to be understood that this is for purpose of illustration only, and that the invention is not to be limited thereby, but its scope is to be determined by the appended claims.

Claims

What I claim is:

1. A liquid and gas contact apparatus having at least one contact fill housed in a casing and composed of layers with folds crossing one another and bearing against one another in adjacent layers, passageways extending from end to end formed between said layers being passed simultaneously by the gas in a substantially horizontal direction and by liquid in a substantially vertical direction of flow, characterized in that those folds which have a downward inclination towards the outlet side for the gas at a short distance from the layer end edge are formed with cuts extending in vertical direction in such a manner that liquid flowing down along the folds changes its direction of flow at said cuts prior to said liquid reaching said edge.

2. The contact fill of claim 1, characterized in that the layers, the folds of which have an upward inclination towards an adjacent layer edge, extend uninterrupted out to said edge.

3. The contact fill of claim 1, characterized in that the folds having a downward inclination towards the inlet side for the gas at a short distance from the layer end edge are formed with vertically extending cuts.

4. The contact fill of claim 1, characterized in that the layers, the folds of which have a downward inclination towards an adjacent layer edge, are formed with at least one row of mutually spaced slots for downward diversion of the water.

5. The contact fill as claimed in claim 4, characterized in that the strips of the layers thus cut off are reunited with the contact fill upon such a turning operation that their folds have an upwardly directed inclination towards the edge in consideration.

6. A liquid and gas contact apparatus having at least one contact fill housed in a casing and composed of layers with folds crossing one another and bearing against one another in adjacent layers, passageways extending from end to end formed between said layers being passed simultaneously by the gas in a substantially horizontal direction and by liquid in a substantially vertical direction of flow, characterized in that those folds which have a downward inclination towards the outlet side for the gas are entirely cut off in a vertical direction at a short distance from the layer end edge.