WO1998054402A1

WO1998054402A1 - Perfected reactor for liquids purification

Info

Publication number: WO1998054402A1
Application number: PCT/EP1998/003119
Authority: WO
Inventors: Flavio Magaraggia
Original assignee: Comer S.P.A.
Priority date: 1997-05-30
Filing date: 1998-05-27
Publication date: 1998-12-03
Also published as: CA2261664A1; IN192430B; ITVI970081A1; CA2261664C; US6068132A; JPH11514925A; NO990129D0; ES2203972T3; EP0916000A1; NO314948B1; IT1293000B1; EP0916000B1; DE69816940T2; DE69816940D1; NO990129L; JP3340751B2; ITVI970081A0; ATE246744T1

Abstract

The invention realises a reactor (1) for liquids purification comprising: a tank (2) containing the liquid to be purified; a plurality of upper injectors (3) suitable for introducing in the tank (2) said liquid to be purified with an aeriform substance dispersed in it in the form of bubbles; one or more blades (40) arranged inside said tank (2) and connected with a rotating shaft (41); one or more intermediate injectors (17, 28) cooperating with said first interception means (21) suitable for sucking the liquid up and introducing it again in the tank (2) in a lower position in comparison with said upper injectors (3). Said reactor comprises at least a low box (9), arranged at an intermediate height in said tank (2), suitable for receiving the descending liquid (8, 19) during a purification phase, which is supplied with interception means (91) suitable for permitting the suction and the re-flowing of said liquid inside said tank (2).

Description

PERFECTED REACTOR FOR LIQUIDS PURIFICATION The invention concerns a perfected reactor suitable for realising liquids purification, particularly suitable for realising the de - inking of aqueous suspensions of recycled paper. As it is known, fittings, which, using the flotation, realise the de - inking of fibrous suspensions of recycled paper, are used in the paper working field. In particular a reactor belonging to the known technique for liquids purification is described in the patent having reference number MI93A001455, registered on behalf of the same depositor of the present invention. Said reactor is substantially formed of a cylindrical tank in which the liquid to be purified is introduced by a sequence of injectors which are arranged in a circumference in comparison with the tank itself just below the free surface of the suspension to be purified. The suspension to be purified is pumped in the tank through a feeding pipeline, in parallel to which, a suction pipeline which communicates with the outside, is arranged. The liquid through the feeding pipeline sucks air up from the outside, by Venturi effect, through the suction pipeline, in order that inside the tank an emulsion, formed of the suspension to be purified, in which air bubbles are dispersed, is introduced. The air bubbles, helped by the presence of chemical reagents, capture the impurities present in the liquid and they carry them away, purificating it. A first flotation, which leads to the formation of a foam loaded with impurities, is this way realised. Said foam rises towards the surface, where a rotating spatula conveys it towards an evacuation conduct, while the liquid comes down towards the bottom of the tank where a suction hood is present.

The liquid is therefore sucked up by said suction hood through further delivery pipelines connected in parallel to further suction pipelines, is re - introduced in an intermediate position in the tank by further injectors in order to undergo a second flotation. This way the liquid already partially purified which, re - introduced in the tank, during the descent, undergoes a counter - washing by the air bubbles which rise and which are loaded again with the impurities, according to the same process previously described. When the liquid re - enter for the second time in the suction hood arranged on the bottom of the tank, it has substantially finished its purification cycle, and by pumps is conveyed for the utilisation.

The known technique includes that the purification is always realised using two machineries of the described kind, arranged in a cascade connection and this in order to obtain an optimum purification of the liquid to be treated. The present invention sets a purpose for realising a perfected reactor which, having the same dimensions of the reactors belonging to the known technique, and in particular of the reactor of the patent here mentioned, permits to realise the same degree of purification which, according to the known technique, is obtained using two of said reactors belonging to the known technique, arranged in a cascade connection.

The mentioned purpose is achieved by the realisation of a reactor for liquids purification which, according to the main claim, comprises:

- a tank suitable for containing the liquid to be purified;

- a plurality of upper injectors arranged in a circumference in comparison with said tank, in correspondence with the free surface of the liquid to be purified, suitable for introducing in the tank itself said liquid to be purified with an aeriform substance dispersed in it, in the from of bubbles;

- one or more blades arranged inside said tank and connected with a rotating shaft suitable for set them on rotation in order to agitate said liquid in which they are immersed;

- one or more intermediate injectors cooperating with said first interception means arranged on the bottom of said tank and suitable for sucking up and re - introducing in the tank in a lower position, in comparison with said upper injectors, the liquid itself with an aeriform substance dispersed in it, in the form of bubbles;

- draining means suitable for moving away from the free surface of said liquid the foam formed by said bubbles loaded with the impurities captured from said liquid; and it is characterised in that said reactor comprises at least a low box arranged inside said tank at an intermediate height, suitable for receiving the descending liquid during the purification phase, being said low box supplied with second interception means suitable for permitting the suction and the re - flowing of said liquid inside said tank.

Advantageously the perfected reactor of the invention permits to install a unique operative unit instead of two of it, obtaining the same purification efficiency with lesser encumbrances.

Still advantageously the installation of a unique operative unit permits to reduce the length of the pipelines and the number of valves, for the benefit of the saving in the installation and maintenance expenses. Not last advantage is also that, using a unique reactor instead of two of it, the quantity of purified liquid which inevitably is moved away with the foams, is reduced.

According to a preferred embodiment said low box has substantially the shape of a basin with a bottom slightly conical, converging towards the centre and it is arranged inside the tank in a position substantially median in comparison with the height.

Both on the bottom of said tank and inside said basin, interception means of the liquid are present. These are formed of a hood with the shape of a truncated cone, converging upwards, laterally to which a pipeline that, by pumping means with which it is connected, conveys again the liquid inside the tank for a further purification, branches out. To sum up, the presence of such low box arranged at an intermediate position in comparison with the height of said tank, permits to realise a further flotation of the liquid to be purified inside the tank. The said purpose and advantages will be better pointed out during the description of a preferred embodiment of the invention given as an example but not as a restriction and represented in the enclosed drawings where:

- fig. 1 shows the reactor of the invention represented in a longitudinal section with the indication of the directions of the flows during the functioning;

- fig. 2 shows the reactor of fig. 1 in a top view where one of the rotating blades with which it is supplied is in evidence;

- fig. 3 shows in a top view the baffle applied to each blade which equips the reactor of the invention; - fig. 4 shows the cross section of the baffle of fig. 3;

- fig. 5 shows an enlarged particular of the section of the baffle represented in fig. 4.

As fig. 1 shows, the reactor of the invention, indicated as a whole with 1, is formed of a cylindrical tank 2 in which a sequence of upper injectors 3, that are arranged in a circumference in comparison with the tank itself, introduces in it, by a first feeding pipeline 6, the liquid to be purified which comes from a feed manifold 4 with which said first pipeline 6 is connected. A first suction pipeline 5 which, by Venturi effect, sucks air up from the outside, when the liquid to be purified flows, according to the direction 10, through the first feeding pipeline 6 which leads to the injectors 3, is arranged in parallel to the feeding pipeline 6. This way, an emulsion formed of the liquid to be purified, mixed with air, where the air bubbles, helped by chemical reagents which are present, capture the impurities present in the liquid, is introduced inside the tank. This way, a first flotation which produces a foam that is brought towards the surface where it is removed by a rotating blade 7 which conveys it towards a draining conduct 12, is obtained.

The liquid, which descends according to the direction 8, is therefore received at a middle height by a low box 9 which, as it can be observed, presents the shape of a basin whose bottom 91 is converging towards the centre of the tank.

Interception means which are formed of a hood 92, are arranged inside said low box 9. Said hood has a conicity converging upwards, that communicates with a pipeline 93, by which pumping means, not represented, suck up the liquid that is brought, according to the direction 13, towards a second manifold 14.

A second feeding pipeline 15 branches out from said second manifold. A second suction pipeline 16 which communicates with the outside and permits the liquid which flows through said second feeding pipeline 15 to suck air up by Venturi effect, is arranged in parallel to it.

The liquid is therefore immediately re - introduced above the low box 9 by a first intermediate injector 17, arranged above the low box 9 itself and below said upper injectors 3. A second flotation of the liquid which has been already purified, happens in correspondence with said first intermediate injector 17. Indeed, the air emulsified with the liquid which is re - introduced, is mixed with the impurities still present in the liquid and comes to the surface in the form of a foam which is removed by the rotating blade 7 and pushed away through the draining pipeline 12. A first part, indicated with 19, of the liquid which is re-introduced in the tank by the upper injectors 3, as fig. 1 shows, re - enters in the low box 9 from which it is made to flow again, according to the direction 13, while a second part, indicated with 20, comes towards the bottom of the tank. On the bottom of the tank, second interception means, indicated as a whole with 21 , are present. Said interception means comprise a hood 22 with a conicity converging upwards, and a pipeline 23, with it connected, which permits the suction of the purified liquid by pumping means. A part 24 of liquid is for the utilisation, and it is the "accepted", while the remaining part 25 flows in a third manifold 26 from which, through a third pipeline 27 and through further intermediate ejectors 28, it is re - introduced in the tank, upon emulsion with air which is sucked up by Venturi effect through third suction pipeline 30 which is arranged in parallel to said third feeding pipeline 27. The liquid which flows towards the bottom of the tank according to direction 29, results therefore quite completely purified.

It is possible to comprehend for what it has been said, that the liquid runs many times inside the tank 2, in which it realises many flotations obtaining, this way, the same purification result which is usually obtained, using two reactors belonging to the known technique in the already mentioned patent. Inside the tank 2, as fig. 1 shows, a plurality of blades 40, being one of them visible also in fig. 2, is present. Said blades, by a vertical shaft 41 , connected with a ratiomotor group 42, are set on rotation, creating turbulence in the liquid contained in the tank. The surface of said blades is of a porous material, and therefore, each of them substantially forms a reactor which makes easy the intimate exchange in between the air bubbles and the liquid to be purified, and the capture of the pollutant by the air bubbles.

A baffle, indicated as a whole with 50, and represented in plan in fig. 3, is applied on each blade 40, in order to stabilize the turbulent flows which are created. Said baffle, as it can be observed, is formed of a disk 51 , on whose surface, as figs. 4 and 5 show in particular, a plurality of openings 52 is realised.

Said openings are realised opening by shearing in the disk 51 a plurality of longitudinal slots 52, and bending a part of the sheared material in order to realise a plurality of tongues 53, being each of them inclined upwards with an angle 54.

Such angle of inclination 54 is substantially corresponding with the angle, according to which, the resultant speed, which is obtained compounding the ascent speed of the aeriform substance dispersed in the liquid to be purified, with the rotation speed of the disk 51 itself, is inclined.

This way a stabilization of the flow of the descending liquid, according to the direction 80, and of the ascending air bubbles containing the impurities captured by the liquid, according to the direction 90, is obtained. Besides, it can be observed that said openings 52 are realised in all the four quadrants of 90°, according to which the disk 51 is divided, and are arranged in such a way that the openings 52 and the corresponding tongues 53 realised in any of the quadrants, are orthogonal to the openings and to the corresponding tongues realised in the next quadrants and this in order to obtain an improvement of the purification efficiency. The presence of the baffle 50, with the presence of the low box 9, permits to the perfected reactor of the invention to improve the purification efficiencies, making them equivalent to the purification levels achievable by a couple of reactors belonging to the known technique, arranged in a cascade connection. During the executive phase some changes could be introduced in the reactor of the invention, or it could be realised according to building variants which, if based on the same idea of solution described, are to be considered protected by the present patent.

During the executive phase some changes in different measures of the rotating blades or of the outward covering which forms the reactor itself, could be introduced in the reactor of the invention.

Therefore it is clear that said reactor could be realised with any shape or dimension.

Claims

1) Reactor (1) for liquids purification comprising:

- a tank (2) suitable for containing the liquid to be purified;

- a plurality of upper injectors (3) circularly arranged in respect of said tank (2) and in correspondence with the free surface of the liquid to be purified, suitable for introducing in said tank (2) said liquid to be purified with an aeriform substance, dispersed in it, in the form of bubbles;

- one or more blades (40) arranged inside said tank (2) and connected with a rotating shaft (41 ) suitable for setting them on rotation in order to agitate said liquid in which they are immersed;

- one or more intermediate injectors (17, 28) cooperating with first interception means (21 ), arranged on the bottom of said tank (2) and suitable for sucking up and re - introducing the liquid into the tank (2), in a lower position in respect of said upper injectors (3), together with an aeriform substance dispersed in it, in the form of bubbles;

- draining means (7, 12) suitable for pushing away from the free surface of said liquid the foam formed by said bubbles loaded with the impurities captured from said liquid, characterized in that it comprises at least a low box (9) arranged inside said tank (2) at an intermediate height suitable for receiving the descending liquid (8, 19) during the purification, being said low box (9) supplied with second interception means (91 ) suitable for permitting the suction and the re-flowing of said liquid inside said tank (2).

2) Reactor (1) according to the claim 1) characterized in that said low box (9) is formed of a container having the shape of a basin with the bottom converging towards the centre.

3) Reactor (1) according to the claim 1) characterized in that said interception means (21, 91) suitable for permitting the suction and the re - flowing of said liquid inside said tank (2), are formed of a hood (22, 92) with a conicity converging upwards that communicates with a pipeline (23, 93) which cooperates with pumping means for the suction of said liquid.

4) Reactor (1) according to the claim 1) characterized in that said draining means suitable for pushing away from the free surface of said liquid the foam formed by said bubbles loaded with the impurities captured by said liquid, comprise a rotating blade (7) connected with said rotating shaft (41) and a draining conduct (12) which communicates with the inner volume of said tank (2) in correspondence with the free surface of said liquid.

5) Reactor (1) according to the claim 1) characterized in that said injectors (3, 17, 28) are connected with feeding pipelines (6, 15, 27) of the liquid to be purified, being each of them connected in parallel to a suction pipeline (5, 16, 30) which communicates in atmosphere and through which the fluid that flows through said feeding pipelines (6, 15, 27) sucks air up from the environment by Venturi effect.

6) Reactor (1) according to the claim 1) characterized in that one or more of said rotating blades (40) is supplied with a baffle (50) which is formed of a disk (51), supplied with a plurality of through openings (52) suitable for permitting the passing of the descending flow (80) of liquid during the purification and of the ascending flow (90) of an aeriform substance dispersed in said liquid.

7) Reactor (1) according to the claim 6) characterized in that said openings are formed of a plurality of slots (52) realised in said disk (51 ), being each of them delimited by a tongue (53) arranged inclined upwards of an angle (54) in comparison with the plane of said disk (51).

8) Reactor (1) according to the claim 7) characterized in that said slots (52) and said tongues (53) are realised in all the four quadrants of 90° in which said disk (51) is divided, being said slots (52) and said tongues (53) belonging to any of said quadrants and parallel among them and orthogonal to the slots (52) and to the tongues (53) realised in any of the other next quadrants.

9) Reactor (1) according to the claim 1) characterized in that said rotating shaft (41) is set on rotation by a ratiomotor group (42) with which it is mechanically connected.