DE2602008A1 - METHOD AND DEVICE FOR CONTACTING A GAS WITH A LIQUID - Google Patents

Description

Patent attorneys
Dipl.-Ing. Helmut Missling 63 Giessen 20.1.

, _n ,, Bismarckstrasse 43

Dipl.-Ing. Richard Schlee _{Telephone: (Q641) 710ig}

Dipl.-Ing. Arne Missling

S / B 12.710 BERTIN & Cie, 78570-PLAISIR / France,

P.O. Box 3

Method and device for bringing a gas into contact with a liquid

Many industrial processes require a gas and a liquid to be as close as possible to one another bring into contact.

This is the case, for example, with washing or dedusting of a gas, in the absorption of a gas in a liquid and in the transfer of heat between one Gas and a liquid.

The simplest and oldest method is the injection of gas into the liquid mass, which perfects the principle it became clear that the contacts were duplicated in a column, the stacks of plates or other organs and is traversed in countercurrent by the liquid and the gas.

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The present invention aims to obtain a large contact effect between gas and liquid without a large amount of energy, especially for the compression of the gas, is required and without a complicated and expensive equipment is needed.

The invention is also intended to achieve rapid separation between liquid and gas after they have been brought into contact will.

In the method according to the invention, a liquid is used which is without a particular tendency to foam and which is none Contains foaming agent.

Such a liquid is carried in the form of a veil on the upper part of a sloping base, which many is broken through small holes and on which the liquid, left to its own devices, trickles under the effect of gravity, to be caught in the lower part of the pad, while the gas is guided under the pad with a pressure sufficient to allow the gas to close the holes in the pad and the trickling liquid curtain penetrate. The small jets of gas that emerge through the holes are divided into many small ones in the liquid

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Bubbles and the active contacts between the gas and the liquid take place in this way on the surfaces of the bubbles instead of.

Studies have been carried out on the absorption of gas by foams formed by gas jets which permeate a liquid such as water to which a foaming agent has been previously added in such a way that that a foam of large volume and a certain stability is produced. But this leads to great devices in order to be able to collect the foam during the time necessary for the absorption and the complete separation of the gas phases and liquids is required and incidentally entails a large amount of energy to produce a foam layer of to break through great thickness. On the other hand, the foaming agent remaining in the liquid contaminates the liquid. Such a method cannot be used in particular if a gas is only washed or dedusted or for the transfer of heat between gas and liquid.

The method according to the invention avoids manufacture a stable foam, which is why the liquid

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is non-foaming. The liquid can be ordinary water be that is free of a foaming agent, so that foam that is in the trickling liquid veil can form, only lasts for a short time and disappears very quickly at the lower end of the openwork base, whereby a quick separation between liquid and gas is made possible.

According to a further development of the invention, you can if necessary add a foam-preventing agent to the liquid. In other words: if a foam made up of small Bubbles is formed, the life of which characterizes the stability of this foam, is chosen for the purposes of the invention the physicochemical conditions such that the through The bubbles produced by the gas have a lifespan of the order of a second or less.

The invention also relates to a device for implementation of the procedure.

The invention is further explained below with reference to the drawing. The drawing represents embodiments of Devices for carrying out the process are shown schematically.

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Show it:

1 shows a schematic vertical section through a device according to a first Embodiment of the invention,

FIG. 2 is a side view in the direction of arrow F in FIG. 1, with the housing partially cut out is and

FIG. 3 shows an illustration corresponding to FIG. 1 second embodiment.

The liquid, e.g. water, fills a container 2, passes a horizontal overflow 3 and reaches the upper area a plate inclined from top to bottom 4. The liquid trickles down on this plate and becomes collected in a box 5 below. The plate is steeply inclined. One has good results with an incline of the plate from 45 to 60 ° relative to the vertical. In particular, it was found that the smallest diameter of the bubbles corresponds to an inclination of 60 °.

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The plate has essentially the shape of a rectangle, the long sides of which are located below the overflow 3, so that the plate following the overflow is covered with a veil of the same thickness, the streamlines of which are parallel to each other get lost. The plate is pierced by many small holes 6, which are distributed over its entire surface and the diameter of which is of the order of millimeters and, for example, three millimeters with a gap of mm between the holes.

The various organs are enclosed by a closed jacket 7. The part 7a of the defect that is below the plate is located, receives through one or more tubes 8 the gas that is introduced at 9 under a certain pressure will. The gas passing through the holes 6 is forced to penetrate and obstruct the liquid curtain at the same time the liquid begins to fall from the plate through the holes. The gas tries in the liquid to form small jets, the speed of which is higher relative to the liquid, the higher the flow speed the liquid itself is. The small jets of gas are in this way from the beginning through the Liquid dissolved, forming many small bubbles,

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on the surface of which the exchange between liquid and gas takes place.

The gas that has penetrated the liquid is discharged in the upper part 7b of the jacket via a line 10 to finally to be withdrawn at 11, while the liquid collected at the lower end of the plate in the box 5 at 12 from the Box is withdrawn, for example by means of a pump 13, to finally be collected at 14.

In such a device, the flow losses of the gas when passing through the perforated plate and the liquid curtain are relatively low, which is why the feed pressure of the gas does not need to be very high at 9, what it allows the work for the compression of the gas to be kept low.

Of course, these pressure losses are of the thickness of the trickling down Water veil dependent. However, this water veil can be given a relatively small thickness, e.g. a thickness of 10 mm above the plate by regulating the supply of the overflow 3 accordingly and can liquid

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slide back from the lower end of the plate upwards, to multiply the contacts between gas and liquid. In fact, it's more economical to use the liquid to raise the plate height than to increase the compression of the gas so that the gas has a greater flow resistance could overcome, as it would result from a thick layer of liquid.

In the example already mentioned, in which the holes are 3 mm Diameter and spaced 30 mm from each other and the liquid layer above the plate a thickness of 10 mm the pressure loss of the gas is 30 mm water column with a gas quantity of 100 nr per hour for 1 m Plate area.

The circulation can be effected with simple devices.

In the drawing, a line 15 is shown, which circulates part of the liquid supplied the pump 13 allowed. There is also a line in the drawing 16 for the circulation of part of the gas, e.g. by means of a jet pump 17, which by means of the jet from fresh, entering at 9 and pressurized

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Gas is operated. Suitable valves 18, 19, 20, 21, which are arranged in the liquid line and the gas line allow the circulation flow rates to be metered.

Since the contact time between liquid and gas, i.e. the life of each bubble is very short and for example is of the order of 0.1 seconds, the transfer coefficient is commonly referred to as "gas-liquid conductance" can denote maximum and reaches this maximum value with each circulation of the liquid in which new bubbles are created.

As can be seen from the above description, the device is very simple.

It was found that in spite of this simplicity and in spite of the low expenditure of energy required, the device due to the low pressure loss in the gas and the low Consumption of the circulation pump allows a remarkably high efficiency of the exchange to be obtained.

Although the ratio of molecular weight of the liquid stream to the molecular weight of the gas flow is large (far greater than 10), the contact area per nr

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Liquid be a multiple of the contact area that can be achieved with plate columns, whereby the energy consumption is on the order of half or a third. Indeed, there are no stagnant zones and no preferential paths for the liquid and gas.

In addition, the perforated plate is constantly washed by the turbulent flow of the liquid, since the flow is solid Deposits conveyed into the box 5, on which a sludge discharge nozzle 5a is expediently provided.

It has also been found that the effectiveness of the contact and the energetic efficiency are very little by changes in the strength of the gas and / or liquid flows, even if these changes are considerable e.g. these currents increase from single to double. This is a major advantage in the Comparison with known methods.

Several devices, such as that of Figures 1 and 2, can be connected in series, e.g. one above the other, so that the liquid flows over the perforated plates one after the other, moving from plate to plate

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while the gas penetrates the plates one by one, or several devices can be arranged in parallel, as shown in FIG.

In this figure there are three inclined perforated plates :; 4a, 4b and 4c, which are similar to the plate 4 already described. The liquid arriving through the channel 22 feeds three collecting troughs 23a, 23b and 23c which extend along the upper edge of the respective plate and from which the liquid overflows in order to trickle over the plates. The liquid is collected at the bottom by a channel 24 and can be circulated as described above.

The gas arriving through the line 25 extending over the entire width of the device divides into three parallel streams, two of which flow around the line 24 to end under the perforated plates and to penetrate these plates and the liquid curtains trickling down on the plates . The gas is collected at 26 and can be circulated as described above.

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Simultaneous one behind the other and parallel arrangement is also possible.

The embodiments described are for illustrative purposes only and could be modified without leaving the framework the invention is abandoned.

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Claims (8)

- 13 claims: Method for bringing a gas into contact with a liquid, the liquid emerging from an overflow due to the effect of gravity in the form of a veil on an inclined, perforated surface trickles and is collected by a collector in the lower area of the pad and the gas flow with a pressure below the inclined Underlay sufficient to penetrate the holes and the liquid curtain, characterized in that, that the liquid, which is not foaming, is in shape a very thin and turbulent flowing veil of liquid is distributed and da.3 the small bubbles that form when the gas passes through the liquid curtain, have a lifespan of less than a second. 2. The method according to claim 1, characterized in that a foam preventing agent is added to the liquid will. 3. The method according to any one of the preceding claims, characterized in that at least part of the gas under the openwork pad (4j 4a, 4b, 4c) is circulated. - 14 - 60983 1/0874 4. Device for performing the method according to one of claims 1 to 3, characterized in that the pad (4j 4a, 4b, 4c) on which the liquid curtain flows, consists of a flat, essentially rectangular plate, which is pierced by a large number of holes (6), which have a very small diameter and which are at an angle between 4-5 ° and 60 ° relative to the vertical is inclined. 5. Apparatus according to claim 4, characterized in that several perforated documents (4a, 4b, 4c) in parallel can be fed with the liquid and the gas can also flow through it in parallel. 6. Apparatus according to claim 4, characterized in that several perforated documents in parallel with the liquid can be fed and the gas can flow through in series. 7. Apparatus according to claim 4, characterized in that that several perforated documents can be fed in series by the liquid and the gas can flow through them in parallel. 8. Device according to one of claims 5 and 6, characterized in that it has a jacket in the form of a parallel 6098 3 1/08 7 - ή 5 - having epipedes, which has a substantially horizontal base plate and inclined, mutually parallel flat Contains boxes, the inclined surface of each box being pierced by one of the inclined holes (6) Documents (4a, 4b, 4c) is formed and the bottom with a collecting line (24) for the liquid and the top with an overflow (23a, 23b, 23c) work together. 609831/0874 Blank page