CA1133400A

CA1133400A - Gas scrubber

Info

Publication number: CA1133400A
Application number: CA319,995A
Authority: CA
Inventors: Pierre De Castella
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-01-20
Filing date: 1979-01-19
Publication date: 1982-10-12
Also published as: NO153446B; GB2012612B; DK22079A; GB2012612A; JPS54117139A; IT1119251B; DE2901448A1; CH619622A5; NO790194L; FR2414945A1; IT7967124A0; JPS6148049B2; SE438602B; NL7900268A; SE7900462L; NO153446C; FR2414945B1

Abstract

ABSTRACT

A gas scrubber is provided with a driven rotor having at least two discs rotating about a common axis and spaced from each other, at least one of the rotors having a central intake opening. The surface of at least one rotor is corrugated or otherwise deformed and is absorbent. The rotation of the rotors causes the flow of scrubbed gas through the intake opening and radially outwardly between the discs while particles suspended in the gas are adsorbed to the rotor surfaces. The invention thus avoids the need of filters passed through by the scrubbed gas, thus eliminating the problems associated with the clogging of same. The capacity of the scrubber is increased.

Description

GAS SCRUBBER
The invention relates to a gas scrubber comprising a motor and a rotor driven by the motor.
A very large number of gas scrubbers are kncwn, particularly those for scrubbing air. These scrubbers generally consist of a fan driven by a motor and of a filter located in the fluid stream produced by the fan, the filter being traversed by this stream. The particles in suspension in the fluid to be scrubbed are thus retained by the filter which becomes saturated or block more or less rapidly depending upon the quantity and nature of the particles to be retained.
The purpose of the invention is to provide a scrubber comprising elements which are not traversed by the stream of gas to be scrubbed.
The gas scrubber in accordance with the invention is characterized in that the rotor comprises at least two discs having a common axis of rotation or symmetry and being spaced from each other, at least one of the discs is driven by the motor and a central intake opening is formed in at least one of the discs.
In the scrubber in accordance with the invention, the filter is no longer traversed by the stream of fluid to be scrubbed; its surfaces move into intimate contact with said stream so as to retain the particles in suspension therein. On the other hand, the scrubbing function and the ventilation function are carried out by the same means, that is to say by the shape and design of the surfaces of the rotor. This arrangement operates like a radial fan possessing the additional feature of scrubbing the gas traversing it.
In a preferred arrangement, at least one of the rotor discs is of conical form, the distance between the discs being less at the periphery than at the centre.
This arrangement, and the rotor in particular, scrubs the air by adsorption. We shall refer to the article in this new method of exploiting the known phenomena of adsorption as an "adsorbant rotor", since it is a true adsorbant, operating on il33~0~ ' ' a physical, physico-chemical or chemical basis. The best known adsorbant is wood charcoal which adsorbs toxic gases and odours.
The scientific encyclopaedias dealing with adsorption state that "pulverulant or porous solids possess the property of retaining the molecules of the gas or liquid phase in contact with their surfaces". This physico-chemical phenomenon has been called adsorption, from the Latin "ad" - on - "sorbere" -to retain - so as to differentiate it from absorption which is not a surface phenomenon. The solid is called the adsorbent and the gas or the liquid, the adsorbate. Adsorbents may be solids or liquids, and adsorbates may be gaseous, liquid, in solution, or even suspension. It would seem that not much attention has been paid so far to the phenomena of adsorption of a solid on a solid, or of a liquid on a solid. The filtering rotor of the present invention also fulfills these two functions perfectly.
In the mechanics of fluids, "the theory of the limiting layer" has been known since the last century; in this theory, the particulars of the movement of the viscous fluid are studied for high Reynolds numbers. Within the limiting layer, which is the layer of fluid in contact with a moving solid (or vice versa), there may exist a laminar flow or turbulent flow system. The passage of laminar flow to turbulent flow in the limiting layer takes place when the Reynolds number reaches its critical value.
The present invention exploits the consequences of the turbulent flow system in which the particles of fluid move along disordered trajectories, which stem from the frictional forces between the fluid and the moving solid walls. In turbulent flow the value of the speed of the particles of the fluid at each point in space undergoes continuous change both in magnitude and direction. This disordered movement of masses of fluid promotes excellent contact between -the latter and the solid faces forming adsorbent surfaces. Attachment of the solid or liquid particles suspended in the fluid, upon contact with the solid surfaces surrounding them, increases with the roughness of the surfaces.
--1~33~0 Hitherto, it has not been possible to establish theore-tically the exact form of the law relating to resistance for the turbulent limiting layer. For this purpose, use is made of results of experimental research work on the laminar limiting layer, as well as the various simplifying hypotheses.
For this reason the modern methods of calculating the turbulent limiting layer are semi-empirical, and their accuracy depends upon the authenticity of the test materials used as a basis when determining the laws relating to the distribution of speeds and resistances. With some exceptions, all the research work has been carried out to avoid the occurrence of turbulent movement when moving solids are in contact with a gaseous fluid (or vice versa), whereas the object of the present invention is to create these turbulent movements so as to obtain therefrom a hitherto unexploited effect: the filtration of gaseous fluids by physical or chemical adsorption or by the two simultaneously, when the material forming the adsorbent rotor is impregnated with a chemical reactant, the catalytic effect of which chemically converts the pollutant gas in suspension in the fluid to be scrubbed. This chemical adsorption phenomenon is also known as "chemisorption".
When rotated, the rotor causes the polluted gaseous fluid to be drawn in, scrubs it by adsorption and throws out a scrubbed fluid. This rotor may turn in free air like a simple axial fan, and it causes convection movement of the surrounding air, then removal of air, in a closed circuit, from the area in which it is located, and progressive scrubbing of the air from that location. The rotor may also be enclosed in a casing which enables polluted air to be picked up in an enclosure and makes it possible for this same scrubbed air to be passed into another enclosure. Measurements made on a chromic acid aerosol have indicated average filtration efficiency of between 92.8% and 98.5% after a single passage of the polluted air through the casing of the scrubber equipped with various forms of adsorbent rotor.
The material of which the rotor is made will preferably be rough. It may be a fibrous material which is rigid or 11334~o ;' flexible, woven or agglomerated, embossed, striated or honeycombed.
On the other hand, this material will be impregnated or coated with at least one chemical reagent capable of reacting with polluted gases (chemisorption) or odiferous particles contained in the gas to be scrubbed and which are required to be trapped; conversely, the rotor material may incorporate odiferous particles required to be added to the scrubbed fluid.
If required or desirable, this material can be treated with a flame-proofing agent so as to prevent burning when the reaction with the impurities proceeds too violently or when the gas is at a critical temperature.
A cylindrical deflection surface or a surface in the form of a fixed truncated cone may be fitted around the rotor of the scrubber so as to cause the stream of gas, set in motion, by the rotor, to be deflected upwardly and/or downwardly.
This cylindrical surface consists of a rigid material and may be smooth, thougn it is preferably rough, ie., striated, embossed, honeycombed or folded.
A plurality of cylindrical or annular surfaces may be arranged in series so as to present to the flow of gas escaping from the rotor a solid obstacle which causes further turbulence in the stream and/or deflects it. The object aimed at is to cause each of the polluting particles suspended in the gas moved by the rotor to enter into contact with one of the adsorbing surfaces placed in its path.
As in the case of the rotor itself, the cylindrical surface or surfaces downstream of the rotor can be impregnated or coated with at least one chemical reagent so as to neutralize chemically or physically the gases mixed with the drawn-in gaseous fluid. These annular surfaces may be humidified so that the air that strikes and sweeps over its surfaces is humidified; the scrubbing is completed by humidifying the gas moved by the rotor. These surfaces may be perfumed, flame-proofed or coated with germicidal agents, depending upon the functions that they are to fulfil. Also, they can be made of metal and connected to a cooling means.

1133~

The annexed drawings illustrate, by way of examples, some forms of construction of a gas scrubber in accordance with the invention.
In the drawings:
Fig. 1 is a side view of a first form of scrubber in the form of an adsorbent rotor, Fig. 2 is a section through the scrubber along line II-II of Fig. 3, Fig. 3 is a plan view of the scrubber illustrated in Figs. 1 and 2, Fig. 4 is a cross-sectisn through a second form of scrubber comprising a casing supporting a fixed scrubbing part disposed on either side of an adsorbent rotor, Fig. 5 is a plan view of the Fig. 4 arrangement, Fig. 6 is a cross-section through a third form of scrubber also in the form of an adsorbent rotor, Fig. 7 is a plan view of a fourth form of scrubber consisting of two creased discs surrounded by a cylinder, Fig. 8 is a section along line VIII-VIII of Fig. 7, and Fig. 9 is a side view of a fifth form of scrubber.
The scrubber illustrated in Figs. 1 to 3 comprises a rotor 1 consisting of two discs 2 and 3 each formed from a creased round element and disposed about a common axis of rotation 4.
The disc 3 is fixed on and lies against a flat, circular baseplate 5, and the periphery of the disc 2, which is in the form of a truncated cone, is firmly secured to the periphery of the disc 3 so that laterial openings 6 which are to serve as outlet ports of the rotor 1 are formed. The baseplate 5, and the disc 3, and the disc 2 have respective central openings 7 and 8 which are to serve as intake orifices. The creased disc 2, in the form of a truncated cone, is held at its centre by a string 9 intended to prevent the disc from opening up when the rotor 1 turns. The baseplate 5 has means, not shown, for enabling it to be secured to a plate, likewise not shown, driven by a motor. The securing means, not shown, for the plate 5, may be "Velcro" (TM) strips, self-adhesive strips, pins, press-studs, etc. The central opening 7 of the disc 3 ~133~

_ ~ ~ 7 -will not be used in the case where the scrubber 1 is secured on a plate as described abo~e.
The creased discs 2 and 3 of the rotor 1 are each formed from a rectangular strip of thin material having a rough surface, which strip is creased in the manner of bellowsin the direction of its width to form a succession of parallel folds, the two end folds being connected end to end to form the creased circle.

t 1133~6~0 The material used for forming the creased discs should have a relatively rigid surface that is as rough as possible, for example, blotting paper, material based on compressed fibres or surfaces covered with an agylomerate having an embossed configuration or comprising hollows and peaks which are able to retain the particles in suspension in the gas to be scrubbed when the latter sweeps said surfaces.
The motor for driving the rotor 1 is not shown.
The drive can be imparted in various ways, the choice of which does not affect the adsorbent action of said rotor.
In the preferred arrangement, the rotor is secured by causing adhesive strips to adhere to the plate 5 which has the same diameter as the rotor and is arranged con-centrically with the shaft of the motor. In view of the light weight of the rotor 1, this method of fixing enables the motor to be placed in any position without the rotor becoming detached from the plate integral with the motor shaft. The adsorbent rotors can thus be interchanged without the need for special tools.
The adsorbent action of the rotor begins as soon as it starts to turn. The speed of rotation must be suited to the dimensions and quality of the material selected for the rotor 1. However, this speed must be great enough to cause, around and within the rotor, a turbulent movement of the gas which is automatically caused to circulate in the direction indicated by the arrows 10 and 11 (Fig. 2). In other;words, starting up of the rotor causes a drop in pressure at the upper centre of the rotor (the opening 8 shown in Figs. 1 to 3), accompanied by the intake of surrounding air along the outer wall of the rotor, as well as within the rotor along the upper wall and the circular base (disc 3 as seen in Fig. 2).

., ~. .

1133~o - -~

g Gas drawn into the interior of the rotor is discharged by centrifugal force through the peripheral openings 6 shown in Figs. 1 to 3. As gas approaches the periphery of the rotor, its speed increases, and this has the effect of reducing the static pressure (Bernouilli's theorem).
The depth h indicated in Fig. 2 is kept constant by the annular binder 9 at the upper portion of the cone

2 where the creased conical wall forms spirals. This same creased wall is secured at its periphery to the circular base of the creased part of the rotor by means of hooks, point stitching, gumming etc., so as to create openings 6.
The circular base 5 is rigid and may be cut from the same material as that of which the discs 2 and 3 are formed. These discs may also be made from surfaces of revolution or uncreased planar elements. The creased form increases the turbulence of the fluid and the effective surface of the rotor which promotes the deposition of impurities on the walls of the rotor.
As mentioned above, the creased base disc or the upper creased cone 2 can be formed in a simple manner, and can be obtained from a rectangular strip of thin mater-ial which has rough or honeycombed faces and is folded in the manner of an accordion.
It is possible to superpose a number of concentric cones on the shaft of the motor (this not being shown in Figs. 1 to 3) so as to increase the areas of contact of the selected material with the fluid circulating between these superposed walls. Creased cones may alternate with smooth ones, or all the cones can be creased or smooth.
In each case the fluid does not pass through the conical or planar walls; it simply sweeps along these walls in a turbulent movement, that is to say at a speed higher than the critical speed, below which, movement of the fluid would be laminar.

.

l ~133~0 Two conical rotors identical to that shown in Figs. l to 3 can be secured back to back to form a single rotor having two oppositely disposed inlets for the drawn-in fluid, with parallel peripheral discharge of the scrubbed fluid. The effect of this arrangement comprising in effect three discs, one of which is flat and the other two conical, each disc, together with the adjacent disc, delimiting an air outlet which narrows towards its periphery, is to double the throughput of fluid drawn in by a single rotor without appreciably increasing the space occupied by the scrubber. In certain applications for scrubbing the atmosphere assoc-iated with units of great héight, this arrangement may be found useful since it improves the convergent effect of the contaminated air towards the scrubber suspended from the top of the unit. Such an arrangement, which will be obvious to the person skilled in the art, is not illustrated in the drawings.
The frusto-conical form of the rotor 1 that has been described has the effect of greatly increasing the throughput and turbulence of the drawn-in gas as com-pared with a flat rotor, and at the same time it ensures that the fluid makes better contact with the walls. The same dynamic effects are achieved by enclosing a creased and flat rotor in a fixed double-tapering casing.
Figs. 4 and 5 illustrate a form of scrubber wherein a creased rotor 12 is secured to the periphery of a motor 13 having an exterior rotor 14, the shaft 15 and the suspension ring 16 all of which are fixedly secured to one another.

1~33~30 A stator 17 fixedly connected to the motor consists of two parts: the lowerpart 18 is remoyably secured at 19 and acts as a lower cover so that the rotor and the upper and lower covers 20 and 21 of the stator can be replaced. This stator is made of metal or moulded plastics material. It comprises an upper orifice 22 and a lower orifice 23 whereby drawn-in polluted fluid enters the stator when the motor starts to turn: it also has peripheral openings 24 through which the scrubbed air is able to escape. The inner surfaces of this stator may be provided with creased rings 25 and 26 made of the same material as the adsorbent rotor 12 or a similar material.
These fittings have the effect of increasing the turbulence of the gas within the scrubber and of participating in this scrubbing action by retaining on their surfaces impurities suspended in the fluid. These components can be removed and replaced when saturated. They are held against the inner walls of the stator by clips, adhesive strips or any other suitable fixing means, not illustrated.
Together with the annular folded attachments 25 and 26, secured to the stator the rotor 12 forms a circular passage for the conveyance of the gas to be scrubbed, which passage narrows, the upper portion of the rotor 12 and the attachment 25, as well as the lower portion of the rotor 12 and the attachment 26 forming an arrangement functionally similar to that described by reference to Figs. 1 to 3, the only difference being that the parts 25 and 26 are stationary.
In the embodiment illustrated in Fig. 6, the rotor or adsorbent element 30 comprises a base disc 31 made for example of thin sheet metal, and an upper disc 32 also made of thin sheet metal and in the form of a very wide truncated cone 1133~

delimiting a central intake opening 33. The peripheries of the discs 31 and 32 retain a stack 34 of rough annular sheets 35 spaced from each other by interposed pieces 36, the entire assembly being held together by pins 37. The inner surfaces of the discs 31 and 32 are covered with a rough layer 38 consisting of fibres bonded together by an adhesive, or consisting of woven fibres.
On the outer surface of the base disc 31, the adsorbent rotor 30 comprises fixing means, not illustrated, for securing it to the drive plate of the motor, not illus-trated. To increase the throughput of the adsorbent rotor shown in Fig. 6, it is obviously possible to provide a second central intake opening, not illustrated, in the base disc, or to provide a number of frusto-conical discs as mentioned above in connection with the arrangement shown in Figs. 1 to 3. The discs 31 and 32 may also be formed of creased materials, the inner surfaces of which may or may not be treated. They may also be formed by plain sheets, and the dust which collects with time imparts the required rough configuration to their surfaces.
The advantage provided by the arrangement illus-trated in Fig. 6 is that of combining the advantages of the conical adsorbent rotor with those of the plain annular multi-layer rotor, which advantages are:
large adsorbent surface;
excellen~ contact with the fluid to be scrubbed;
ease of impregnation for adsorbing gases chemically (chemisorption), as a variant, neutralization of odours by means of c~"

V

rings cut from sheets of papex impregnated with activated charc~al, for example, and as a further ~ariant, neutralization of troublesome odours by discharging a perfume with which the rings have been previously impregnated.
~ To summarize, the central (conical) portion of the rotor picks up, at a great rate and a relatively high pressure (20 - 30 mm CE), the fluid to be scrubbed,from which it removes dust, aerosols, soot, pollen, etc., and the impregnated annular part completes this scrubbing by chemical neutralization of harmful gases still remaining in suspension in the fluid.
Chemical impregnation of the central part is not excluded but is not very necessary when the annular part is chemically impregnated for neutralizing the gases passing through it.
The fourth form of scrubber illustrated in Figs. 7 and 8 is a variant of the rotor illustrated in Figs. 1 to 3 described above, but with the addition of a fixed cylindrical annular creased surface, parallel to the axis of rotation of the rotor.
As illustrated in Figs. 7 and 8, two creased rotors 40 and 41, spaced from each other, are secured by means, not illustrated, to the shaft, likewise not illustrated, of a drive motor. The shaft and its motor, not illustrated, are designed to impart rotation to the adsorbent rotor along the axis 42 shown in Fig. 8 and in the same manner as the rotor in the arrangements illustrated in Figs. 1 to 6. An annular cylindrical surface 43 is arranged concentrically with and at a distance from the rotors 40 and 41 so as to act as a direction-changing surface for the gas stream set up at the periphery of the rotors.

113~

The surface 43 constitutes a support for a second creased surface 44 secured at points 45 to the surface 43. The creased surface 44 may, for example, be hooked or bonded at points to the cylindrical surface 43. In the em-bodiment illustrated in Figs. 7 and 8, the creased sur-face 44 may have a crease similar to that of the rotors 40 and 41. However, as in the case of the rotors of the previous~y described arrangements (Figs. 1 to 6), the crease may be replaced by a striation or an embossed formation, or in the extreme case a smooth surface may be used.
When the two rotors 40 and 41 are caused to rotate, the gas in which they rotate is drawn to the centre as indicated by the arrows 46 and 47 (Fig. 8) and flows along surfaces to impinge upon the cylindrical creased surface 44 where it undergoes a 90 change of direction. The stream of fluid then emerges upwardly and downwardly in the direction of the arrows 48 and 49. As in the previous-ly described arrangements of Figs. 1 to 6, the rotors 40 and 41 will be driven at a speed such that the stream of gas is converted into a turbulent flow. Furthermore, the arrangement that hs just been described will be contained in a casing as is the arrangement shown in Figs. 4 and 5.
On the other hand, it will be clear to the person skilled in the art that other deflection surfaces, similar to that represented by the cylindrical creased surface 44, could be added. For example, it is possbile to provide planar annular surfaces, not illustrated, which would be located above and below the surface 44 in such a way that the stream of gas leaving the surface 44 and shown at 48 and 49 (Fig. 8) strikes the planar annular surfaces in a substantially perpendicular direction.
In the arrangement 50 shown in Fig. 9, two conical creased 11334(~10 ' '' discs 51 and 52 are joined at their peripheries so as to leave lateral openings 53 acting as outlet orifices. The two creased discs can be connected together by hooks or by spot bonding. Alternatively, the two discs 51 and 52 can consist of a single piece of material formed from a previously creased rectangular sheet with cut-~way portions forming the lateral opening 53. The two opposite edges of the sheet, not illustrated, which are parallel to the creases are brought into contact and connected to form of a cylinder.
The ends of this cylinder are finally crimped together to form the rotor illustrated in Fig. 9.
The upper end of the creased disc 51 comprises a collar 54 designed to be secured on the drive shaft 55 of a motor, not illustrated. When the rotor 50 of Fig. 9 is caused to turn, the fluid enters its interior in the direction of the arrows 56 and re-emerges at 57 through the orifices 53. The stream of fluid passing through the interior of the rotor thus sweeps over the inner surfaces of the creased conical discs 51 and 52, and the particles suspended in the fluid are able to become deposited on these inner surfaces. Similarly, the surrounding fluid is carried along the outer surfaces of the conical discs 51 and 52 in the direction of the arrows 58. The arrangement 50 of Fig. 9 offers the advantage that it can be creased to a very small volume before use. It will then be in the form of a creased double fan occupying a minimum space when instore and being transported. At the time of its use, all that is required is to hook or bond its opposite edges together along one of its generatrices.
In Fig. 9 embodiment, the rotor 50 has a single inlet or intake opening located near the bottom. However, it will be clear to the person skilled in the art that it is possible to provide, on the collar 54, a fixing means, for example, three rods, not illustrated, evenly spaced around the axis 59 and hooked to the collar 54, the fluid being enabled to enter within said collar. In this variant, the rotor will operate with two intake or entry orifices, one being at the top and the other at the bottom of the rotor. On the other hand, as 1~33400 in the arrangement shown in Figs. 7 and 8, it is possible to provide creased or plain deflection surfaces opposite the outlet orifices 53.
The material used for producing the flat, creased, frusto-conical, annular, etc. discs will preferably be a rough material. The same material may also be used for the annular sheets and the deflection surfaces. Bonded, woven or non-woven fibrous materials in particular, may be used.
If it is preferred, these materials should be capable of being impregnated with, for example, chemical products, perfumes, insecticides, bacteriological products or simply water; then not only will material having rough surfaces be selected, but also absorbent materials. However, these materials only need to be absorbent if it is required to impregnate them with a solution. They may also be coated by spraying with aerosols.
The materials of which the rotor or the rings are made can be impregnated with any natural or chemical product, and the operation can range from a simple humidification with water to treatment with any chemical reagents, (for example a basic substance adapted to fix the acid products of oxidation of the impurities contained in the fluid to be scrubbed) metallic oxidizers (such as activated manganese dioxide, MnO2, which may or may not contain potassium permanganate)~, paper with activated charcoal incorporated in its fibre material, non-inflammable, perfumed, etc. papers or tissues. The materials can therefore be specifically selected to suit the particular chemical pollutant to be neutralized. However, whatever the chemical impregnation selected, the rotor will retain dust and aerosols, whatever their form and what-ever their quantity, ranging from the smallest (tcbacco smoke, for example) to an upper limit which is a function of the centrifugal force applied to the particles suspended in the liquid to be scrubbed (probably 100 microns at the normal speeds of rotation used, ie., between 200 and 1500 r.p.m.).
In principal, there is not limit to the si-ze of the construction of the above-described types of adsorbent 4~

scrubbing means. The greatex the diameter, the greater the adsorbent surface and the greater will be the throughput of aspirated fluid.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows

1. A gas scrubber comprising a motor and a rotor driven by the motor, characterized in that it comprises at least two discs having a common axis of rotation or symmetry and being spaced from each other, at least one of the discs comprises the rotor being driven by the motor, a central intake opening is formed in at least one of the discs, at least one of the discs is of conical form, the distance between the discs at the periphery of the rotor being less than the distance at the centre, and the discs comprising rough surfaces able to retain particulate impurities carried in the fluid which travels along the surfaces.

2. A scrubber according to claim 1, characterized in that at least one of the discs is pleated.

3. A scrubber according to claim 1, characterized in that the rotor comprises a plurality of discs, at least one of which is of conical form, the distance between the discs at the periphery of the rotor being less than the distance at the centre.

4. A scrubber according to claim 3, characterized in that the rotor comprises three discs, one of which is flat and the other two conical, each disc, together with the adjacent disc, delimiting an air outlet which narrows towards it periphery.

5. A scrubber according to claim 3, characterized in that the discs of the rotor are solidly connected to each other at their peripheries in such a manner as to form one or more outlet orifices.

6. A scrubber according to claim 5, characterized in that a stack of annular sheets is provided at the periphery of the discs opposite the outlet orifice and firmly fitted therein.

7. A scrubber according to claim 3, characterized in that two discs are of conical form and in that their common periphery contains lateral outlet orifices.

8. A scrubber according to claim 1, characterized in that a rigid annular deflection surface surrounds the rotor parallel to its axis of rotation.

9. A scrubber according to claim 8, characterized in that the annular surface may be cylindrical or frusto-conical.

10. A scrubber according to claim 1, characterized in that the discs are made of an absorbent material having rough surfaces.

11. A scrubber according to claim 1, characterized in that the discs are creased surfaces made of bonded woven or non-woven fibrous material.

12. A scrubber according to claim 1, characterized in that the discs are made of a material having honeycombed, striated or embossed surfaces.

13. A scrubber according to claim 6, characterized in that the annular sheets are impregnated or covered with a chemical reagent adapted to fix undesirable particles of gaseous component in the fluid to be scrubbed.

14. A scrubber according to claim 13, characterized in that the chemical reagent is activated manganese dioxide which may or may not contain potassium permanganate.

15. A scrubber according to claim 14, characterized in that the chemical reagent is a basic substance adapted to fix acid products of oxidation of impurities contained in the fluid to be scrubbed.

16. A scrubber according to claim 9, characterized in that the annular surface surrounding the rotor is made of porous material.

17. A scrubber according to claim 1, characterized in that the rotor is a replaceable element which can be dis-posed of after use.

18. A scrubber according to claim 6, wherein the annular sheets are made of an absorbent material having rough surfaces.

19. A scrubber according to claim 8, wherein the deflection surface is made of an absorbent material having rough surfaces.

20. A scrubber according to claim 8, wherein the deflection surface is formed of creased surfaces made of bonded woven or non-woven fibrous material.

21. A scrubber according to claim 8, wherein the deflection surface is impregnated or covered with a chemical reagent adapted to fix undesirable particles of gaseous component in the fluid to be scrubbed.

22. A scrubber according to claim 6, wherein the annular sheets are replaceable element which can be disposed of after use.

23. A scrubber according to claim 8, wherein the deflection surface is a replaceable element which can be disposed of after use.