WO1993003819A1

WO1993003819A1 - Device and method for the biological cleaning of pollutant gas

Info

Publication number: WO1993003819A1
Application number: PCT/FR1992/000794
Authority: WO
Inventors: Gérard TERROM
Original assignee: Terrom Gerard
Priority date: 1991-08-14
Filing date: 1992-08-14
Publication date: 1993-03-04
Also published as: FR2680323B1; FR2680323A1

Abstract

The invention disclosed relates to the biological cleaning of pollutant gas. The device is comprised of a housing (1) consisting of a cyclone wherein the biofilter (20) is separated from the truncated portion (3) of the cyclone (2) by means of a wall (11) delimiting with said truncated portion an inlet chamber (12) for the fluid to be cleaned, and extending radially under the biofilter (20) from at least one inlet orifice (6) for the supply means (4, 5) to an annular outlet orifice (13) adjacent to the internal walls of the cyclone, so as to create a radial and centrifugal inlet flow in the chamber (12). Application to industrial gas effluents.

Description

DEVICE AND PROCESS FOR THE PURIFICATION OF GASEOUS POLLUTANTS BY BIOLOGICAL USE "

FIELD OF THE INVENTION:

05

The present invention relates to a device and a method for the biological purification of polluting fluids of all kinds and from all origins.

The present invention preferably applies to

1JD the elimination of gaseous pollutants of organic origin, such as solvents or mercaptans or even the elimination of gases, such as HS, SO or even, more generally, to gases of generic formula SOx, the pollutants gaseous to be removed being contained in air, or other gaseous mixtures.

The invention finds its application in the treatment and purification of all gaseous effluents resulting directly or indirectly from manufacturing processes of the industrial type, such as residues from the manufacture of fungicides, pesticides or insecticides and, more generally , to the purification of all

20 gaseous products resulting from the chemical industry. The invention can also find its application as a complementary treatment to a first phase or to a first device for treatment or purification by biological means of a gaseous pollutant.

25. PRIOR ART:

The invention uses the well-known general principles of biotransformation resulting from the contacting of a gaseous effluent containing dissolved organic substances with

30 organisms or microorganisms which develop, either by using as nutritive supports the organic substances which it is precisely necessary to eliminate, or from cellular organelles. The organisms or microorganisms used constitute what is called biomass, which can be made up of all

35 types of cellular organisms, such as bacteria, mushrooms or yeast, for example. Organelles can be enzymes fixed by conventional techniques.

It is already well known in the prior art to use a transformation biomass fixed on a support arranged inside a reactor. A conventional device of the prior art of this type is for example described in the document FR-A-2 484 447 which reveals an enclosure containing a biomass fixed on suitable supports, integral with the interior of the enclosure. Such a device is particularly designed for the purification of liquid effluents, which are introduced into the upper part of the enclosure by means of a venturi disposed outside. of the enclosure. The liquid to be depolluted is mixed with an oxygenation gas emerging through a pipe at the level of the venturi neck, so as to form a liquid-gas phase emulsion in the divergent part of the venturi. The emulsion thus produced then reaches a diffuser placed above the biomass bed from which the emulsion or The mixture produced flows by gravity runoff over the bed of biomass which it crosses. Many other similar devices are based on the same principle of mass transfer between the effluent and the biomass.

It must first be noted that such a device is not suitable for the purification of gaseous pollutants for which specific conditions for keeping the biomass alive are necessary to carry out the purification operation. Indeed, in such a case, it is imperative, to keep the biomass alive, to saturate the air with a relative humidity close to 100%, in order to maintain a sufficient quantity of water available to the biomass. Apart from this specific aspect for the purification of gaseous effluents, Most of the known prior art devices, in particular that described in patent FR-A-2 484 447, suffer from a major drawback linked to insufficient control. of the path of the effluent to be purified through the biofilter. This insufficiency of the mastery of the journey leads to a residence time too brief relative effluent or fluid in the biofilter leading to equally insufficient and incomplete purification of the pollutant.

BRIEF DESCRIPTION OF THE INVENTION:

The object of the present invention therefore aims to provide a device and a method of purification by biological means particularly suitable for the purification of gaseous effluents in which the path of the effluent through the biofilter is controlled and the extended residence time.

Another object of the invention aims to provide a purification device in which the residence time of the gaseous effluent is lengthened while retaining a device of reduced dimensions.

Another object of the invention aims to provide a device and a method of purification which are easy to use and adaptable downstream of primary purification methods and devices. The objectives assigned to the invention are achieved using a device for the biological purification of polluting fluids and, in particular, gaseous pollutants comprising:

- a treatment enclosure inside which a biofilter is arranged including a biomass fixing support,

means for supplying and evacuating respectively the fluid to be depolluted entering the enclosure and the fluid treated after it has passed through the biofilter, characterized in that: the enclosure consists of a cyclone in which the biofilter is separated from the frustoconical part of the cyclone by a wall delimiting with said frustoconical part an inlet chamber for the fluid to be depolluted, extending radially under the biofilter, from at least one inlet orifice for the means supply to an annular outlet orifice bordering the internal walls of the cyclone, so as to create a radial and centrifugal inlet flow into the chamber.

The objectives assigned to the invention are also achieved by means of a purification process, characterized in that it consists:

to introduce the pollutant into the frustoconical central part of an inlet chamber separate from the bio i Itre, to create a radial and centrifugal flow from and into this chamber,

- to impose on the pollutant at the outlet of the chamber, a change of direction constituting a centripetal flow to pass the pollutant through the biofilter in a radial and centripetal manner,

- to recover the gas treated in the central part of the biofilter and to evacuate it.

BRIEF DESCRIPTION OF THE DRAWINGS:

Various other characteristics will emerge from the description given below with reference to the appended drawings which show, by way of nonlimiting examples, embodiments of the subject of the invention. Fig. 1 watch, in cross section

Longitudinal, an embodiment of a purification device according to the invention.

Fig. 2 shows a cross-sectional view of a purification device according to the invention, taken along line II-II of FIG. 1

BEST WAY TO IMPLEMENT THE INVENTION:

Fig. 1 shows, in a longitudinal cross-sectional view, a device for the biological purification of gaseous pollutants comprising a treatment enclosure 1, the main body of which consists of a cyclone 2, of axis of symmetry χ-χ ', connected by the central zone of its frustoconical part 3 to means 4 for supplying gaseous effluent treat. In the particular example shown in fig. 1, The supply means 4 consists of a tubular connection 5, coaxial with the axis x-x ', opening through its upper part into the frustoconical part 3 to form an inlet orifice 6 and connected by its part lower than a source of gaseous effluent to be purified, not shown. Cyclone 2, preferably arranged so that its axis x-x ', extending substantially vertically, is for example mounted in abutment against a support element 10 surrounding the tubular connection 5.

The frustoconical part 3 of the cyclone 2 extends from its upper limit by a peripheral envelope 8 of the cyclone 2. Advantageously, the envelope 8 is curved and present, as shown in FIG. 1, the concavity turned or directed towards the center of the cyclone, materialized by the axis of symmetry x-x *. The upper part of the cyclone is provided with an upper closure cap 9.

The inclined internal part 3_b of the part 3 defines, with an internal skirt of revolution 11, also frustoconical, an inlet chamber 12 for the gaseous effluent coming from the supply means 4, at constant distance from the latter. The internal skirt 11 extends above and at a distance from the internal face of the frustoconical part 3, up to the vicinity of the casing 8 to provide an annular outlet orifice 13. The internal skirt 11 is provided, in its central portion extending above the inlet orifice 6, of a bore 14, preferably coaxial with the axis x-x '. The inlet chamber 12 thus defines a volume extending radially and parallel to the frustoconical underside of the cyclone 2 from the inlet orifice 6, to the annular outlet orifice 13.

The inlet chamber 12 is advantageously provided with means for guiding and inflection of the circulating gaseous effluent radially from the inlet orifice 6. The guiding and inflection means, intended to create a vortex flow at least at the outlet of the chamber 12, are preferably constituted by helical blades 15 (see fig. 2) fixed by any appropriate means and in particular by welding. The helical blades 15 are preferably four in number, diametrically opposite two by two, substantially relative to the axis χ-χ 'and extending radially from the inlet 6, up to the end of the frustoconical part 3 at the edge of the side wall 8. The blades 15 also advantageously constitute the means for fixing the internal wall 11 in the internal volume of the cyclone 2. In the example shown in FIG . 2, The helical blades thus define four sectors A., A _? , A ,, A ,, advantageously equal, dividing the inlet chamber 12. The entrance area of each sector, in the vicinity of port 6, forms a baffle accelerating the gas flow and initiating a transforming Llonnaire peat movement at least at the outlet orifice 13 in a helical ILcnna re tourbi flow. It is obvious that instead of the helical blades 15, other equivalent technical means can be used, such as a series of baffles or deflection plates.

The cyclone 2 also includes a biofilter 20 separated from the frustoconical part 3 by the internal partition 11 and extending, advantageously, in the axial direction defined by the axis x-x ', from the latter to the cap 9. The biofilter 20 is supported by the internal wall 11 and therefore has an inclined base 20JD and of frustoconical shape. The biofilter 20 extends radially from the axis χ-χ ', substantially up to the peripheral edge of the internal wall 11 and stops at a distance from the envelope 8, so as to delimit, between the latter and the end wall 21 of the biofilter, a peripheral deflection chamber 22 in the form of a ring around the biofilter 20. The deflection chamber 22 is disposed above the outlet orifice 13, the latter opening directly or indirectly by L '' centripetal deflection means of the gas flow in the deflection chamber 22. In the example shown in FIG. 1, the centripetal deflection means of the gas flow consist of the casing 8 of the cyclone 2 which thus forms, thanks to its curvature, centripetal deflection means directly extending the intake chamber 12. Obviously, it is possible to '' use other means - centripetal deflection and attach deflector plates on the casing 8, above the outlet orifice 13, so that the inlet chamber 12 is indirectly extended by means of deflection.

The biofilter 20 comprises a central well 23, preferably aligned with the axis of symmetry x-χ 'of the cyclone 2, said central well 23 being sealed by an internal lining 24 stopping at a distance from the cap 9 to constitute a threshold 25 spill of the gaseous fluid into the central well 23 from the biofilter 20. The lower end of the lining 24 is constituted by an evacuation channel 26 coaxial with the bore 14 and opening into a recovery pipe 27, connected to the drilling 14. The central well 23 is connected to means 28 for evacuating the gaseous fluid, said means advantageously comprising an outlet column 29 concentric with the central well 23, of section smaller than the latter, so as to provide a passage annular evacuation 30 between column 29 and packing 24. Column 29 penetrates into central well 23 over most of its height and is preferably provided at the bottom disposal ages 31 for the gaseous effluent.

The process for purifying gaseous pollutants by biological means consists in introducing the pollutant, by the supply means 4, according to arrow f., Into the intake chamber 12 through the inlet orifice 6 (arrow f Beforehand, a relative humidity close to 100% of the gaseous effluent can be obtained by circulating the gaseous fluid through a water column. It is also possible to permanently inject a certain quantity of water and nutrients necessary for the development of the biomass by diffusing an aqueous mist in the gaseous fluid, prior to its treatment in the cyclone 2. Depending on the solubility of the gaseous pollutants in the aqueous phase, it is possible to use a water-organic phase mixture. This organic phase can itself be soluble or insoluble in the aqueous phase.

The presence of the helical blades 15 in the intake chamber 12 contributes to creating a radial and centrifugal flow (arrow f,) from this chamber and to the outlet orifice 13. When leaving the intake chamber 12, the gaseous fluid undergoes a change of direction (arrow f,) in the deflection chamber 22 by striking the concave face of the casing 8, which sends the gaseous fluid, in a centripetal and radial manner (arrow f,.), in the direction of the x-χ 'axis. This creates a centripetal flow of the gaseous fluid, which is led to pass through the biofilter 20, also in a radial and centripetal manner. The gaseous fluid then passes through the annular strip 25, then into the central well 23, after having undergone a biological purification in the biofilter 20. The treated gaseous fluid pours in a downward flow f, in the passage 30, then enters, through the holes 31, in the outlet column 29 from which it is discharged (arrow f- outwards. During its descending discharge phase in the passage 30, the condensates of the gaseous fluid can be recovered and flow by gravity through the orifice 26 in the discharge channel 27.

The particular arrangement of the purification enclosure according to the invention leads to optimal control of the path of the gaseous fluid leading to increasing the residence time of the fluid to be treated within the biofilter itself, while retaining a relatively treatment structure. compact. It should also be noted that the cyclone reactor can be very easily converted at the outlet of a primary purification reactor, via the tubular connection 5. The invention is not limited to the examples described and represented, because various modifications can be made without departing from its scope.

POSSIBILITY OF INDUSTRIAL APPLICATION:

Biological elimination of gaseous polluting fluids contained in industrial or any other type of gaseous effluents.

Claims

CLAIMS:

1 - Biological purification device for polluting fluids and, in particular, gaseous pollutants comprising:

- a treatment chamber (1) inside which is disposed a biofilter (20) including a biomass fixing support,

means of supply (4, 5) and evacuation (28) respectively of the fluid to be depolluted entering the enclosure (1) and of the fluid treated after its passage through the biofilter (20), characterized in that : the enclosure (1) consists of a cyclone (2) in which the biofilter (20) is separated from the frustoconical part (3) of the cyclone (2) by a wall (11) delimiting with said frustoconical part a chamber inlet (12) of the fluid to be depolluted, extending radially under the biofilter (20), from at least one inlet orifice (6) for the supply means (4, 5) up to an annular outlet orifice (13) bordering the internal walls of the cyclone, so as to create a radial and centrifugal inlet flow into the chamber (12).

2 - Device according to claim 1, characterized in that the intake chamber (12) comprises means for guiding and inflection (15) of the fluid flow, extending from the inlet orifice (6) at the outlet orifice and capable of creating a L Lonnai re turbi intake flow.

3 - Device as claimed in claim 2, characterized in that the guide and inflection means consist of helical blades (15). 4 - Device according to one of the preceding claims, characterized in that the biofilter (20) extends in the cyclone (2) at a distance from the casing (8 ⁾ of the cyclone (2), so as to provide a chamber of peripheral deflection (22) in which opens the outlet orifice (13) of the intake chamber (12), which extends into the deflection (22) by means of centripetal deflection (8) of the flow to direct the latter through the biofilter (20) towards the discharge means (28).

5 - Device according to claim 4, characterized in that the deflection means comprise curved deflector plates, preferably formed by the casing (8) of the cyclone (2), which have their concavity turned towards the longitudinal axis (xx *) of cyclone (2).

6 - Device according to one of the preceding claims, characterized in that the biofilter (20) comprises a central well (23) sealed for recovering the treated fluid, said well (23). Being aligned with the axis of symmetry (xx *) of the cyclone (2) and connected to the evacuation means (28).

7 - Device according to claim 6, characterized in that the discharge means (28) comprise an outlet column (29) of air or gas, concentric with the central well (23), of section smaller than that of the well central (23), penetrating into the latter and emerging in the upper part of the cyclone (2), outside. 8 - Device according to claim 7, characterized in that the discharge means (28) comprise a discharge channel (26) of the condensates of the treated fluid, said channel being connected, in the lower part of the central well (23), to a recovery line (27). 9 - Biological purification process for polluting fluids, and in particular gaseous pollutants in which the pollutant is passed through a biomass fixed on a biofilter, characterized in that it consists:

- to introduce the pollutant into the frustoconical central part of an inlet chamber separate from the biofi Ltre,

- to create a radial and centrifugal flow from and into this chamber,

- to impart to the pollutant, at the exit of the chamber, a change of direction constituting a flow centripetal to pass the pollutant through the biofilter in a radial and centripetal manner, - to recover the gas treated in the central part of the biofilter and to evacuate it. 10 - A method according to claim 9, characterized in that it consists in creating a circular helical intake flow. 11 - Method according to one of the preceding claims, characterized in that it consists in recovering the treated gas in a central evacuation well and in imparting to it, before its evacuation in the upper part of the well, a downward path in the well to recover the condensates.