GB1571514A

GB1571514A - Apparatus for cleaning gaseous fluids

Info

Publication number: GB1571514A
Application number: GB4798776A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1975-11-25
Filing date: 1976-11-17
Publication date: 1980-07-16
Also published as: FR2332790B1; ATA865276A; DE2652297A1; FR2332790A1; JPS6013728B2; CA1108379A; AT372296B; DE2652297C2; JPS5265369A

Description

(54) APPARATUS FOR CLEANING GASEOUS FLUIDS (71) I, PIERRE DE CASTELLA, a Swiss Citizen of La Vuachere, 1111 Monnaz, Switzerland do hereby declare the invention for which I pray that a Patent may be granted to me and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to apparatus for cleaning gaseous fluids, comprismatur- bine including a motor and a rotor drivingly connected with the motor to be rotated thereby; the rotor being shaped and positioned to induce a turbulent flow of gaseous fluid when rotated.

Conventional air cleaning or purifying apparatus include screens of filter paper or fabric, or baskets (corfs) or baffles enclosing active substances in granular or liquid form and through which air is drawn or blown.

Active carbon, beds of granular potassium permanganate and sawdust impregnated with manganese dioxide leave all been proposed as active filtering material which retains impurities in the air by physical or chemical action. These known cleaning apparatus require means for moving the air which are sufficiently powerful to overcome the pressure loss produced during passage of the air through the filters. The consumption of power and of costly chemical products used is high and is contrary to the efforts being made to economize power and depletable materials. Also, the noise produced by the pumped air is a nuisance and cleaning and replacement of the filters is generally a difficult and dirty operation.

An aim of the invention is to provide an apparatus for cleaning gaseous fluids which is of simple structure, economical, easy to service, quiet in operation, has a low power consumption and which is capable of cleaning fluids chemically and/or by mechanical absorption of impurities.

According to the present invention there is provided an apparatus for cleaning gaseous fluids, comprising a turbine, the turbine including a motor and a rotor drivingly connected with the motor to be rotated thereby, the rotor comprising at least one rotary disc having a pleated shape able to produce a turbulent flow of fluid along the surfaces thereof when the rotor is rotated, said surfaces further being rough surfaces able to retain particulate impurities carried in the fluid which travels along the surfaces without passing through the surfaces, whereby the rotor cleans the fluid in addition to circulating it.

According to the nature of the cleaning or purification to be carried out, the manner of construction of the turbine can vary.

The turbine rotor may advantageously be made of a woven or non-woven fibrous material and is constructed in such a manner that when it is rotated, it produces a turbulent flow of the gaseous fluid. The rotor disc is pleated, namely is folded so as to extend back and forth in the axial direction. In a preferred embodiment, the rotor of the filtering turbine may be made of at least one radially-folded disc made by placing together the narrow ends of a rectangular sheet folded across its width in zig-zag configuration, and which may be impregnated or coated with at least one chemical reagent capable of reacting with the gaseous fluid to be cleaned, or nonimpregnated.

The turbine may have a stator, i.e. a casing which surrounds the rotor, of any known form, for example: a simple protcctive grid for the rotor; a closed sheet metal casing having at least one fluid inlet on the rotor axis and one or several peripheral outlets; or a shaped volute as is common in centrifugal or radial flow fans. The motor driving the rotor is fixed with the stator.

As in centrifugal fans, the rotation of the rotor produces a displacement of the gaseous fluid to be cleaned from the centre of the turbine towards the periphery, through the rotor. By virtue of the laws of fluid mechanics, in particular when the speed of flow of the fluid through the rotor is greater than the critical speed, the flow is turbulent. In turbulent flow, the speed of the fluid at each point of the space in the rotor undergoes continuous changes, both in value and direction. This random mixture of the fluid masses favourizes an excellent contact with the filtering surfaces. Gases to be neutralized thus come into contact with the impregnated surfaces and are chemically transformed. Dusts, aerosols and other materials in suspension in the gaseous fluid are deposited on the walls of the rotor.

To increase this phenomenon of turbulence due to the viscosity of the gaseous fluids and to assist the retention of particles, the surface of the constituent material of the filtering rotor is rough, i.e. has visible irregularities the dimensions of which will depend on the nature of the cleaning to be carried out. absorbent material forming the turbine (or stator) surfaces may be a fibrous, rigid or flexible, woven or agglomerated material, such as a carboard-like material, corrugated paper, sheets of porous or cellular plastics material, or sheets of non-woven fibres (cotton, polyester, glass, etc.) or woven fibres.

Furthermore, the material with a rough surface may be impregnated or coated with at least one chemical reagent capable of reacting with polluting gases or smelly particles contained in the gaseous fluid to be cleaned, and which are to be removed. Such a chemical reagent will be chosen so that when the polli*,ng gases or smelly particles come into contact with the impregnated or coated surfaces of the rotor (or stator), it transforms them into salts which remain fixed on the rough surfaces.

The absorbent material may also be impregnated with a bacteriological agent, for example germicide solutions for killing micro-organisms contained in the fluid to be cleaned.

In a preferred embodiment of the invention, the chemical reagent is an oxidising agent, in particular a permanganate and/or activated manganese dioxide. Activated MnO2 is well known in the art; it exerts a greater and more rapid oxidising action than ordinary MnO2, and is usually formed by a careful partial reduction of KMnO4. It is believed that the activated MnO2 still contains some KMnO4. It has been found that, most surprisingly, activated MnO2 is formed quasiautomatically by impregnating paper with an aqueous solutlon of KMnO4. Preferably, as material of discs of the rotor, one uses cellulose which is as pure as possible. It is though that the cellulose acts as a reducing agent for transforming KMnO4 into activated Mono2.

The KMnO4/MnO2 system also has another advantage. Since the salts of bivalent manganese (Mn(II)) which are formed when the oxidising agent is depleted are white, this forms an indicator for the system. The decolouration thus indicates that the active material is reaching exhaustion, and the filter is changed.

Other oxidising agents may be used for the impregnation or coating of the discs: for example salts, oxides or hydroxides of Fe(III), the chromates or bichromates or salts of Sn(IV), Pb(IV), Ce(III), Ti(IV), vanadium, etc. It is also possible to use cyanoferrates (III) and addition composites of H202, for example perborates, urea peroxide etc. These oxidising agents, including KmnO4 and activated MnO2, may be used alone or mixed.

Use of an oxidising agent is preferred since the most usual impurities of air are easily oxidisable. These impurities are, for example, H2S, SO2, solvent vapours (alcohols, ketones, esters, hydrocarbons, aldehydes), amines, greases, mercaptans, and so on.

Some of these impurities when oxidised give acidic products. For example, H25 and SO2 are oxidised to S03. Normally, these oxidised products are retained by the material of the sheets, for example according to the follc -ing relationship: S03 n nO AnO MnSO4, the MnO being the prod. r of the reaction SO2 + MnO2 S03 + MnO.

To further increase the retaining power of the filter, one may add to the oxidising agent with which the rotor discs are impregnated or coated, a base such as KOH, NaOH, Na2CO3 or K2C03. It is also possible to apply the oxidising agent to the median part of the rotor and to impregnate or coat the periphery with the base. As a variation, a cylindrical (or non-cylindrical) body is placed about the rotor and the air leaving the rotor comes to hit this body which is impregnated with a different reagent to that of the rotor; if it is for example impregnated with a base, this body will thus retain the acidic products of oxidation.

The discs may also be impregnated with perfumes, as may said cylindrical body if one is provided. It is also possible, of necessary or desired, to incorporate a fireproofing agent in the treating material to avoid fire when the reaction with the impurities takes place violently or when the gaseous fluid @ a critical temperature.

The accompanying @@a ings show, by way of example, two embodiments of a gaseous-fluid cleaning apparatus according to the invention. In the drawings: Figure 1 is a schematic top plan view of a gaseous-fluid cleaning apparatus comprising a rotor which acts as a centrifugal filter; Figure 2 is a side view of the rotor of the apparatus of Figure 1; Figure 3 is a top plan view of a variation of the rotor of the embodiment of Figures 1 and 2, and Figure 4 is a side view of the rotor of Figure 3.

The gaseous-fluid cleaning apparatus shown in Figures 1 and 2 comprises a rotor 61 arranged to operate, without a casing, in a gaseous fluid to be cleaned. The rotor 61 is in the form of a pleated disc fixed on a shaft 62 by means of upper and lower securing washers 63 and 64. Shaft of is driven by a motor, not shown. The disc 61 is made simply from a rectangular band of thin material with a rough or cellular surface which is folded across its width and the two ends joined together edge-to-edge, to form a radially pleated ring with a central opening through which the shaft 62 passes. The securing washers 63, 64 may be simple friction washers fitted on the shaft 62, or may be se re@ @y screws, not shown. The disc 61 @@@b @sembled to the shaft 62, and possibly to rewashers 63 and 64, by an adhesive.

Operation of the apparatus is as fallows: when the motor is started, it turns the rotor 61 which acts as a centrifugal @an@@@ing the fluid towards the exterior. The gaseous fluid is driven outwards by the rotor and as the fluid approaches the periphery of the rootr/ filter its speed increases and, as a result, the static pressure drops (Bernouill's law). The gaseous fluid is thus made to lick the faces of the disc 61, and during this intimate contact particles of dust are @@noved from the fluid by adherence and p@@@uing gaseous well as polluants in the @erosol state and which are capable of chemical transformation can be captured by @@ @@@ chemical reaction with reagent @@@reg@ated in the disc.

The apparatus of Figures 1 and 2 is particularly suitable for cleaning air since such an apparatus with a multi-folded rotor operating an en enclosure such as a room produces a circulation of air in the enclosure with the apparatus as point of convergence.

This natural suction of the ambient air through the apparatus takes place silently, though even at slow speeds of rotation, there is a great flow of air through the apparatus. The pleated disc 61 perfectly functions as rotor and filter. The flow of air produced by a disc 61 of 400 mm external diameter rotating at 200 r.p.m. is of the order of 300 m3/h per face of the disc, or 600 m3/h for the two faces of the pleated rotor.

At this very low speed of rotation, the apparatus makes no noise. The 400 mm diameter disc with which the above-quoted flow measurements were carried out was made of a semi-rigid cellulose paper about 1 mm thick, and folded to provide a disc thickness of 3 to 4 cm.

When the apparatus of Figures 1 and 2 is used to purify air containing polluting gases (H2S or SO2 for example), the pleated disc 61 may be impregnated or coated with an appropriate chemical reagent, according to the polluting gas to be removed, The paper of the disc forming the rotor may be of natural or synthetic fibres and is impregnated with chemical reagents, usually an aqueous solution of KMnO4 which is dried in air at a temperature between 20 and 50 C.

The disc 61 may, as previously mentioned, be impregnated with perfumes or germicides. Also, the apparatus of Figure 1 can be arranged to act as an air humidifier, by saturating the disc 61 with water. This can be achieved in a simple manner, for example by directing a jet of water against the disc or by making the rotor shaft of a porous material and placing it in contact with water in, for example, a tank. The disc 61 may also be treazed chemically or bacteriologically to kill all living germs and neutralize odours or bacteriological products may be added to the water instead of being directly applied to the filter.

Figure 3 and 4 show a variation comprising three discs 65, 66 and 67 similar to the disc 61 of Figure 1, supported and spaced apart by @@t circular sheets 68, 69, 70 and 71 (Figure formed of a similar material to the pleated discs 65 to 67. The folding of discs 65 to 67 is arranged to leave a central hole 72 @@@ @ @ sheets 68, 69 and 70 have like circular @@@ positioned so that when the rotor is rotated, air is drawn into the centre of the turbine and, as indicated by arrows 73, Figure 4 passes through hole 72 and flows out bewteen channels formed by the pleats of the three discs 65, 66 and 67 and the sheets 68, 69, 70 and 71. The bottom sheet 71 has a smaller central opening than the other sheets, to receive the driving shaft 74 of a motor, not shown. Sheet 71 is secured to the shaft 74 by two washers 75, 76. The rotor formed by the pleated discs 65 to 67 and sheets 58 to 71 may be assembled by an adhesive, by rivetting, etc.

The sheet material used to make the turbine of Figures 3 and 4 is the same as that described for the embodiment of Figures 1 and 2, and may be subjected to the same treatments.

The rotor of Figures 3 and 4 may advantageously be enclosed in a casing, for example a cylindrical or volute-shaped casing with a central intake and radial or tangential outlet.

If the rotor is made of semi-rigid cellular plastics material, it may for example be assembled by heat welding. However, it will be apparent to persons skilled in the art that the rotors of the described embodiments can be assembled by any known means, such as stapling, rivetting or sewing.

The rotor may be made of newsprint paper, or could alternatively be crepe or corrugated paper. Newsprint sheets have the required porosity and a sufficient mechamcal strength to withstand rotation at speeds up to 2000 r.p.m. It is, however, evident that these newsprint sheets may be replaced by sheets of other materials having a sufficient porosity, for example blotting paper, sheets of porous plastics materials, sheets formed of compressed fibres covered with mineral materials, etc.

It has been observed that a rotor/filter made of simple sheets of rough paper adequately stops all particles in suspension in the air, notably smoke, pollen, dusts and aerosols. Bacterial contained in the air are in general always carried by dust or other carriers. As dust particles are stopped by the filter, the latter has an air-purifying effect and may deliver practically sterile air.

The sheets composing the rotor/filter may be chemically or bacteriologically treated to kill all harmful germs contained in the air.

They may thus be steeped with bacteriological products or geriii'fies - well as perfumes of all types. Also, as previously mentioned, the sheets of the multi-layer filter may be chemically treated to neutralize odours or toxic gases contained in the gaseous fluid to be cleaned.

The described emobodiments operate in the same manner. The gas flows through the rotors with a turbulent flow. With such a turbulent flow, the particles in suspension or particles of unwanted gases to be fixed in the case where the rotor is treated wif a chemical reagent, have the greatest possibil fty of being retained on the rough surfaces of the turbine. The arranfflement of the rough surfaces produces discontinuities in the flux of fluid which travels along the rough surfaces without passing through the rough surfaces, whereby the impurities are deposited and retained on the rough parts of the rotor surfaces. It is also clear that several rotors can be assembled to form a unit with several stages, as illustrated for the embodiment of Figures 3 and 4, and the rotors can be enclosed in a casing with air intake and outlet orifices, or can be unencased.

Of course, the described filters are interchangeable and may even be cleaned for re-use. Their cost price is moderate. The material of which they consist may be treated chemically, for example coated with activated manganese dioxide, alone or con taXning potassium permanganate or a basic substance able to retain acidic products of oxidation of the impurities. They may also be coated with perfume or bacteriological agents. It will be understood that the materials may be coated with not one but several chemical reagents, each chosen to retain or react with a particular gaseous component.

A fixed cylindrical or frusto-conical body may be placed about the rotor of the apparatus to upwardly and/or downwardly deviate the current of gaseous fluid produced by the turbine. Such a body of porous material may have at least one chemical reagent able to react with and retain the products of reaction of the impurities which pass out of the filter, or may be impregnated or coated with a perfume and/or impregnated with a germicide. It may also be saturated with water to humidify the purified air which leaves the rotor. Alternatively, such a body may be a cooled metal surface which dries purified air leaving the periphery of the filter unit by condensing water on the cold surface.

Persons skilled in the art will realize that many types of turbines other than those shown in Figures 1 to 4 can be used. The invention, in its broader aspects, is thus not limited to the described cleaning apparatus, but in particular, according to one aspect, concerns cleaning apparatus fitted with all types of turbines provided of a material with a rough surface adapted to retain particles in suspension in a gaseous fluid driven by the turbine, which thus carries out two functions, a v milafion function and a cleaning or purifXl zg function. Finally, of course, all of the de3cribesil cleaning apparatus can, as described for the embodiment of Figure 1, be transformed -- also act as a humidifier.

Claims

WHAT I CLAIM IS:

1. An apparatus for cleaning gaseous fluids, comprising a turbine, the turbine including a motor and a rotor drivingly connected with the motor to be rotated thereby, the rotor comprising at least one rotary disc having a pleated shape able to produce a turbulent flow of fluid along the surfaces thereof when the rotor is rotated, said surfaces further being rough surfaces able to retain particulate impurities carried in the fluid which travels along the surfaces without passing through the surfaces, whereby the rotor cleans the fluid in addition to circulating it.

2. Apparatus according to Claim 1, which comprises a shaft, a stack of at least two said rotary discs mounted on the shaft, the stack of discs having adjacent to its centre at least one fluid-intake opening and at least an annular plane disc placed between the or each two adjacent said rotary discs, the annular plane disc being of the same material as the rotary discs.

3. Apparatus according to Claim 1, in which the rotor material is a fibrous nonwoven material.

4. Apparatus according to Claim 1, in which the rotor is comprised of sheets of semi-rigid cellulose paper having a rough surface.

5. Apparatus according to Claim 1, in which the rotor material is comprised of a cellular plastics material.

6. Apparatus according to Claim 1, in which the material of the rotor is impregnated with a chemical reagent able to fix Impurities of a gaseous component of the fluid to be cleaned.

7. Apparatus according to Claim 6, in which the chemical reagent is activated manganese dioxide optionally containing potassium permanganate.

8. Apparatus according to Claim 6, in which the chemical reagent is a basic substance able to fix acidic products of oxidation of impurities contained in the fluid to be cleaned.

9. Apparatus according to Claim 1, in which the rotor is impregnated with a germicide.

10. Apparatus according to Claim 1, in which the rotor is impregnated with a perfume.

11. Apparatus according to any one of Claims 1 to 10 comprising means for soaking the material of the rotor with water whereby the cleaning apparatus operates as a humidifier.

12. Apparatus according to any one of Claims 1 to 11 in which the rotor is surrounded by a fixed generally cylindrical body arranged to deviate the gaseous fluid leaving the rotor.

13. Apparatus according to Claim 12 in which said cylindrical body is comprised of porous material.

14. Apparatus according to Claim 13, in which said body of porous material is imnregnated with a chemical reagent able to fix non-desirable gaseous components of the fluid to be cleaned.

15. Apparatus according to Claim 13, in which sald body of porous material is impregnated with a germicide.

16. Apparatus according to Claim 13, in which said body of porous material is impregnated with perfume impregnated with perfume 7. An apparatus for cleaning gaseous fluids constructed and arranged to operate substantially as described with reference to and shown in the respective Figures of the accompanying drawings.