Abstract:
In a method and to a device for treating a compound, such as a chemical and/or organic and/or microorganism compound, which is carried by a liquid, the liquid is driven axially through an axial inlet ( 21 ) into a central inlet portion of a radial cavitation chamber ( 18 ) having a peripheral outlet ( 30 ), such that the liquid is diverted into the central inlet portion and flows into the radial chamber in various radial directions towards the peripheral outlet; and the liquid flow conditions between the inlet and the peripheral outlet of the radial chamber are capable of generating cavitation bubbles or pockets ( 31 ) and subsequently causing the collapse or implosion of the bubbles or pockets in order to treat the compound at least partially.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to the field of treating compounds such as chemical or organic compounds or species, or micro-organisms. 
     Description of the Related Art 
     Unwanted chemical compounds are frequently found in water which has been polluted by, for example, volatile compounds such as hydrocarbons or chlorinated compounds (for example, trichloroethylene) or by not very volatile compounds such as PCBs (polychlorobiphenyl), PCPs (pentachlorophenol) used as fungicides or certain molecules which are considered as endocrine disrupters. These bodies are usually carcinogenic and can cause illness in animals and humans. 
     These unwanted bodies are currently destroyed or transferred using a number of techniques including activated carbon adsorption, thermolysis, electrolytic reduction, ultraviolet irradiation or oxidation by chemical compounds such as ozone, peroxide or Fenton&#39;s reagent. Some treatments combine several of these basic methods. In all cases, the methods are expensive and awkward to implement. 
     The water can also contain living micro-organisms such as bacteria or microscopic algae. It is often desirable to destroy them to avoid pathological effects. Techniques equivalent to those used for chemical compounds are used for this destruction, for example sterilization using chloride or peroxide or ultraviolet irradiation. 
     To carry out some treatments, it has also been proposed to use ultrasonic waves emitted into liquids which are to be treated and/or to use cavitation inside the liquids which are to be treated and flowing in Venturi tubes or in equivalent axial-flow tubes. Such arrangements are described in the documents EP 1 738 775, US 2007/0280861, W02005/028375. 
     The documents U.S. Pat. Nos. 5,749,650, 5,899,564 and US 2006/256645 describe treatment devices in which the liquid passes radially through annular micro-slits formed between axially superposed and axially adjustable rings. The liquid escapes through the slits, forming radial jets which are dispersed in large peripheral evacuation spaces, these jets causing turbulence in these spaces without any cavitation pocket being formed. 
     The document U.S. Pat. No. 6,200,486 describes a device which comprises an inner cylindrical wall having orifices and an outer cylindrical wall, which form a large space between them. As in the documents referred to in the paragraph above, the flow at the outlet of the orifices is in the form of jets in this large space. 
     The document U.S. Pat. No. 4,585,357 describes a device which comprises a radial micro-slit opposite which a deflecting wall is installed at a great distance. Here too, the flow through the slit causes dispersion jets. 
     The document JP 11 42432 describes a device in which two opposite flows collide. The resultant flow flows away radially and is discharged into a peripheral evacuation chamber, here too in the form of dispersion jets. 
     The document DE 3728946 describes a device in which an axial flow is deflected toward a radial chamber which has a peripheral opening. This chamber is in the shape of a truncated cone and formed such that its thickness reduces in the direction of the outside. Turbulence phenomena occur only beyond the peripheral opening of the radial chamber, in the large evacuation chamber. 
     The document JP 2008/207099 describes a device in which the liquid is introduced axially into a blind hole and is evacuated through divergent radial channels in the shape of truncated cones which are formed in the wall of the blind hole, at a distance from the base. In fact a Venturi-type mode of operation occurs in each divergent radial channel in the shape of a truncated cone, axially thereto. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to produce a particular cavitation effect which can improve the mechanical and/or chemical and/or bacteriological effects and/or the effects on the micro-organisms, on the compound or compounds carried in a liquid to be treated. 
     In order to achieve this object, the present invention is based on a cavitation effect which causes the formation of bubbles or pockets of vapor in a liquid under the action of reduced pressure and in which the bubbles or pockets of vapor produced during this application of reduced pressure then suddenly condense when the pressure rises again. Under certain conditions, this rapid condensation, also called collapse, takes place for periods of time between, for example, one ten thousandth of a second and a microsecond depending on the initial size of the bubble or the pocket, wherein this reaction can be sufficiently rapid that the gases are compressed and heated to temperatures greater than, for example, 2000° C., thus producing a plasma. 
     The present invention thus seeks in particular to increase the combined effects of the intense turbulence which prevails in the collapse zone of the cavitation bubbles or pockets and the very high speeds of the wall of the latter; and/or to increase the effects resulting from the plasma produced in the cavitation bubbles or pockets and capable in particular of producing radiation in the liquid; and/or to destroy compounds present in the cavitation bubbles or pockets; and/or to cause the production of molecules, ions or species or chemical radicals which can migrate into the liquid and act on the compounds carried in the liquid; and/or to produce the intense sound waves in the liquid. 
     The subject of the present invention is first a method for treating a compound, such as a chemical and/or organic compound and/or a micro-organism, carried by a liquid. 
     This method is such that two substantially radial faces arranged opposite each other delimit between them a radial cavitation chamber, one of said faces having an axial inlet orifice formed axially in its central part and said faces forming a peripheral outlet opening; that the liquid supplied axially through the axial inlet orifice is deflected and flows into said radial cavitation chamber in various radial directions toward the peripheral outlet opening; and that the thickness of said cavitation chamber ( 18 ), between said radial faces, is selected such that it is between 0.1 and 0.25 times the diameter of said axial inlet orifice and is preferably 0.14. 
     The flow conditions of the liquid thus generate cavitation bubbles or pockets in the first part of the radial flow, around a central inlet orifice. Also, the cavitation bubbles or pockets thus implode before they reach the peripheral outlet opening, in order to treat said compound at least partially in said cavitation chamber. 
     The distance between the axis of said central inlet orifice and said peripheral opening of said cavitation chamber can be selected so that it is more than twice the diameter of said central inlet orifice. 
     The ratio between the absolute pressure upstream of said cavitation chamber and the pressure downstream of this chamber can be between 1.5 and 6. 
     The subject of the present invention is also a device for treating at least one compound, such as a chemical and/or organic and/or a micro-organic, carried by a liquid. 
     This device comprises a first element having a substantially radial face and a substantially axial liquid-inlet orifice, and a second element having a substantially radial face. 
     Said radial faces are arranged opposite each other so that they form between them a space forming a radial cavitation chamber having a peripheral outlet opening, said axial inlet orifice of the first element opening out into a central part of this cavitation chamber opposite said radial face of the second element. 
     The thickness of said cavitation chamber, between said radial faces, is between 0.1 and 0.25 times the diameter of said axial inlet orifice and is preferably 0.14. 
     The liquid which is supplied axially through the axial inlet orifice is thus deflected in the central inlet part and flows into said radial cavitation chamber in various radial directions toward the peripheral outlet opening and the flow conditions of the liquid generate cavitation bubbles or pockets in the first part of this flow, around the central inlet orifice, and that the cavitation bubbles or pockets implode before they reach the peripheral outlet opening, in order to treat said compound at least partially. 
     Said radial faces delimiting said radial cavitation chamber can be parallel. 
     The distance between the axis of the central inlet orifice and said peripheral opening of said cavitation chamber can be more than twice the diameter of said central inlet orifice. 
     Said peripheral outlet orifice of said radial cavitation chamber can communicate with a secondary chamber connected to at least one outlet passage. 
     A different treatment means can be associated with said secondary chamber, in particular an emitting means, i.e., an emitter, generating ultraviolet radiation in said secondary chamber. 
     The first element and the second element can comprise two walls which form a space between them, one of the walls having a plurality of inlet orifices for the liquid and the other wall having a plurality of outlet orifices, so as to form a plurality of cavitation chambers in said space and between said inlet orifices and said outlet orifices. 
     Said inlet orifices can open out into an inlet collecting chamber and the outlet orifices can open out into an outlet collecting chamber, where said walls can be annular and concentric and are preferably cylindrical or concentric, or flat. 
     Said first element can have a bevel on the edge of said axial inlet orifice, where this bevel can be rounded and have a radius between 0.1 and 0.5 times the distance between said radial faces in the central part of the cavitation chamber or be in the shape of a truncated cone arranged at an angle between 30° and 60°, preferably at 45°, and over a height, in the direction of the axis of said axial inlet orifice, between 0.1 and 0.5 times the distance between said radial faces in the central part of the cavitation chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       The present invention will be better understood on studying treatment devices with a cavitation chamber which are described by way of non-limiting example and illustrated in the drawings, in which: 
         FIG. 1  shows a longitudinal section of a treatment device; 
         FIG. 2  shows a cross-section along the line II-II of the treatment device in  FIG. 1 ; 
         FIG. 3  shows an enlarged radial section of the cavitation chamber of the treatment device in  FIG. 1 ; 
         FIG. 3B  corresponds to an enlarged central portion of  FIG. 1  and which includes initial  FIG. 3 ; 
         FIG. 4  shows a longitudinal section of an alternative embodiment of the treatment device; 
         FIG. 5  shows a radial section along the line V-V of the treatment device in  FIG. 4 ; 
         FIG. 6  shows a longitudinal section of an alternative embodiment of the treatment device; 
         FIG. 7  shows an internal side view of the treatment device in  FIG. 6 ; 
         FIG. 8  shows an enlarged radial section of the central part of the cavitation chamber in an alternative embodiment; and 
         FIG. 9  shows an enlarged radial section of the central part of the cavitation chamber in an alternative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A treatment device  1  shown in  FIGS. 1 to 3  comprises a casing  2  which comprises two opposite shells  3  and  4  having a vertical axis  5  and delimiting between them a radial cavity  6  which is formed between an annular radial face  7  of the shell  3  and an annular radial face  8  of the shell  4 . The shells  3  and  4  can be identical and placed opposite each other. 
     In the radial cavity  6 , a spacer  9  is arranged which comprises a disk  10  which has a radial face  11  bearing against the annular radial face  7  of the shell  3  and which comprises a cylindrical peripheral part  12  which projects relative to the disk  10  and bears against the annular radial face  8  of the shell  4 . 
     The shells  3  and  4  have adjacent peripheral parts  13  and  14  connected by bolts  15  to fix them together and maintain the bearing contact described above. 
     An O-ring  16  is installed between the periphery of the cylindrical peripheral part  12  of the spacer  9  and the periphery of the cavity  6 , in the annular zone of the facing radial faces of the adjacent peripheral parts  13  and  14  of the shells  3  and  4 . 
     Inside its annular radial face  7 , the shell  3  (first element) has a recess  17  which delimits, with the radial face  11  of the disk  10  (second element), a cavitation chamber  18 , the base  19  of the recess  17  extending radially, parallel to the radial face  11  of the disk  10 . 
     The shell  3  has an axial passage  20  which has at the end a, for example cylindrical, central orifice  21  which opens out axially into the central part of the cavitation chamber  18 , through the radial face formed by the base  19  of the recess  17 . The end of the duct  22  for supplying a liquid  23  is engaged and fixed leaktightly in the passage  20 , for example by an annular packing gland system  24 . 
     The shell  4  has an axial passage  25  which opens out axially, for example through a central orifice  26  at the end, into the central part of the secondary chamber  27  formed in the spacer  9 , opposite the radial cavitation chamber  18 . The end of the duct  28  for evacuating the liquid  23  is engaged and fixed leaktightly in the passage  25 , for example by an annular packing gland system  29 . 
     The disk  10  of the spacer  9  has a plurality of through passages  30  which open out, on the one hand, into the periphery of the radial cavitation chamber  18  and, on the other hand, into the secondary chamber  27 . The through passages  30  are regularly distributed over a circumference so as to form a peripheral outlet opening of the radial cavitation chamber  18 . These through passages  30  can be formed by cylindrical holes or circumferential slits. 
     The liquid  23  supplied by the supply duct  22  is thus introduced into the central part of the radial cavitation chamber  18  through the central orifice  21 , is then deflected radially in this central part, and then flows into the radial cavitation chamber  18  in various radial directions toward the peripheral outlet opening formed by the through passages  30 . The liquid issued from the through passages  30  is then collected in the secondary chamber  27 , and then evacuated through the evacuation duct  28 . 
     The conditions of the radial flow of the liquid  23  in the radial cavitation chamber  18 , from the central inlet orifice  21  to the peripheral through passages  30 , are such that this flow is hydrodynamic, that cavitation bubbles or pockets  31  appear in the first part of this flow, around the central inlet orifice  21 , and then collapse or implode immediately before, preferably well before, these cavitation bubbles or pockets  31  reach the peripheral outlet through passages  30 . 
     The phenomenon of the creation and collapse of the cavitation bubbles or pockets results from the effect of reduced pressures followed immediately by elevated pressures. During the creation of the bubbles, gases dissolved in the liquid tend to be released in these bubbles. During the collapse, an adiabatic compression is produced which causes very high temperatures and very high pressures in the bubbles which implode. 
     The cavitation produced is a hydrodynamic cavitation which results from the acceleration of the flow due to a reduction in its passage cross-section followed by a gradual increase in said passage cross-section in a virtually radial direction. This cavitation makes it possible to create a very sudden rise in pressure in the condensation zone or collapses, which causes an increase in the intensity of the above-described effects for a given flow rate. Furthermore, the particular shape of this device causes the phenomenon to occur with a loss of pressure and hence a minimal expense of energy. 
     The cavitation pockets or bubbles  31  can include a main annular pocket or bubble very close to the inlet orifice  21  and sticking to or situated against the radial face  19  of the shell  3 , supplied with gas dissolved by the liquid which flows through. This main annular pocket or bubble is split into smaller-sized pockets or bubbles which move away from the center of the chamber and which condense, collapse or implode. 
     By virtue of the treatment device  1 , the cavitation bubbles or pockets  31  produced are able to at least partially treat the compound or compounds carried by the liquid. This treatment can be chemical, thermal, chemical and thermal and/or may be sonic as the cavitation phenomenon may produce sound waves which radiate in the liquid. 
     The formation against the wall  19  and the collapse of the bubbles or pockets of vapor  31  can be localized in a virtually predetermined fashion and/or can be controlled. Because the thickness of the radial cavitation chamber  18  is adapted relative to the cavitation bubbles or pockets  31  produced, the cavitation affects all of the liquid to be treated which flows into this chamber  18 . 
     When the liquid such as water carries one or more chemical compounds, specific chemical radicals or species can be formed in the cavitation bubbles  31  produced and collapse, these specific chemical radicals or species being capable of reacting with these chemical compounds and producing other compounds. The chemical effects can cause the destruction of compounds present in the bubbles, generally volatile compounds initially dissolved in the liquid by the production of molecules, ions or radicals which can migrate in the liquid and have an action on the compounds which it carries. Among these actions, oxidation by OH° radicals makes it possible to destroy dissolved molecules which are difficult to remove. 
     When the liquid such as water carries one or more micro-organisms, the cavitation bubbles  31  produced can make it possible to attack these micro-organisms and/or films or accumulations of the latter, in order to destroy, disperse or break them up by chemical or mechanical effects or by intense pressure waves. 
     The flow conditions of the liquid in the cavitation chamber  18  of the treatment device  1  can result from a subsequent dimensioning. 
     The thickness of the cavitation chamber  18  between the opposite radial faces  7  and  19  can be between 0.1 and 0.25 times the diameter of the central supply orifice  21 . 
     The thickness of the cavitation chamber  18  can in particular be 0.14 times the diameter of the central supply orifice  21 . 
     The distance between the axis  5  of the central supply orifice  21  and the circumference on which is formed the peripheral opening of the cavitation chamber  18  determined by the through passages  30  can be more than 2.5 times the diameter of the central supply orifice  21 . 
     The ratio between the inlet pressure and the outlet pressure can be between 1.5 and 6. 
     In one exemplary embodiment, the diameter of the supply orifice  21  can be 8 mm, the thickness of the cavitation chamber  18  can be 1.12 mm, the distance between the axis  5  of the central supply orifice  21  and the circumference on which is formed the peripheral opening of the cavitation chamber  18  determined by the through passages  30  can be 30 mm. 
     According to one alternative embodiment shown in  FIG. 8 , said first element  3  can have a rounded bevel  21   a  formed on the edge of the axial inlet orifice  21  and joining the face  17 . This rounded bevel  21   a  can have a radius r which is between 0.1 and 0.5 times the distance between the radial faces  11  and  19  in the central part of the cavitation chamber  18 . 
     In another alternative embodiment shown in  FIG. 9 , said first element  3  can have a bevel  21   b  in the shape of a truncated cone and formed on the edge of the axial inlet orifice  21 . This bevel  21   b  in the shape of a truncated cone can be arranged at an angle of between 30° and 60°, and preferably at 45°. Its height h, in the direction of the axis of the axial inlet orifice  21 , can be between 0.1 and 0.5 times the distance between the radial faces  11  and  19  in the central part of the cavitation chamber  18 . 
     The bevels  21   a  or  21   b  can facilitate the formation of the cavitation pocket  31  at their periphery. 
     With reference to  FIGS. 4 and 5 , it can be seen that a different treatment device  100  is shown which comprises a cylinder  101  (first element) which has a radial front face  102  in which is formed a cylindrical recess  103  and which comprises a circular disk  104  (second element) engaged at a distance in the cylindrical recess  103  and fixed axially against three inner fingers  105  of a circular washer  106  bearing against the radial front face  102  of the cylinder  101 . 
     The stack formed by the cylinder  101  and the circular washer  106  is engaged in the end of an outer cylindrical tube  107  such that the washer bears against an inner shoulder  108  of this tube  107 . The cylinder  101  has a peripheral shoulder  109  and fixing screws  110  which pass through this shoulder and are screwed into the cylindrical tube  107  so as to fix this stack. An O-ring  111  ensures the leaktightness between said stack and the cylindrical tube  107 . 
     The circular disk  104  is placed in the cylindrical recess  103  such that a radial face  112  of this disk  104  and the radial base  103   a  of this recess  103  form between them a cavitation chamber  113  of constant thickness and that the periphery of the disk  104  and the periphery of the recess  103  determine between them an annular through passage  114  determining a peripheral opening of the cavitation chamber  113  and opening out inside the tube  107 , between the inner fingers  105  of the circular washer  106 . 
     In order to ensure a constant thickness of the cavitation chamber  113 , the radial base  103   a  of the recess  103  is provided with projecting bulges  103   b  against which bears the radial face  112  of the disk  104 , these bulges  103   b  being placed at the periphery so as not to adversely affect the flow of the liquid. The bulges  103   b  also center the disk  104  in the recess  103 . 
     The cylinder  101  has an axial passage  115  which has a, for example cylindrical, central orifice  116  at the end, which opens out axially into the central part of the cavitation chamber  113 . A connector  117  in which the end of the duct  118  supplying a liquid is fixed leaktightly is screwed into the passage  115 . 
     The structure thus formed is such that the cavitation chamber  113  is equivalent to the cavitation chamber  18  of the treatment device  1 . 
     The treatment device  100  can advantageously be connected in series with another treatment device  100   a  as described below. 
     The other end of the cylindrical tube  107  is closed by a radial wall  119  and has a lateral outlet opening  120  in the vicinity of this wall  119 . A duct (not shown) can be connected to the lateral outlet opening  120  in order to evacuate the treated liquid. 
     The wall  119  is traversed leaktightly, via a seal  119   a  held by a sleeve  119   b , by an inner axial cylindrical tube  121  made, for example, from quartz, a closed end  122  of which is situated in proximity to the circular disk  104 , the inner fingers  105  of the circular washer  106  being extended by tips  123  for centering and holding the end  122  of the inner cylindrical tube  121 . 
     The inner tube  121  is connected to known means (not shown) which can generate in this tube  121  ultraviolet radiation radiating in the annular chamber  124  formed between the outer tube  107  and the inner tube  120 . 
     A liquid such as water carrying one or more compounds to be treated is thus, in a first step, treated by the treatment device  100  and then immediately, in a second step, treated by the treatment device  100   a  in the annular secondary chamber  124  by the ultraviolet radiation generated by the inner tube  120 , and then evacuated through the lateral outlet opening  120 . The radiation radiates throughout the annular secondary chamber  124 . As the disk  104  is made of quartz, the radiation can also reach the annular through passage  114  and the cavitation chamber  113 . 
     Such an arrangement is particularly advantageous when micro-organisms carried by water need to be destroyed in order to treat the latter and make it less polluted. 
     In an alternative, the means for generating radiation could be placed around the outer tube  107 . 
     In an alternative embodiment illustrated in  FIGS. 6 and 7 , a treatment device  200  comprises an inner cylindrical wall  201  and an outer cylindrical wall  202  which are concentric and delimit between them a cylindrical space  203  of constant thickness which is closed at its ends by any known means. 
     The inner cylindrical wall  201  has a plurality of inlet orifices  204  opening out, on the one hand, into the space  203  and, on the other hand, into the internal space  205  of this wall  201 , this internal space  205  forming a longitudinal inlet collecting chamber. 
     The outer cylindrical wall  202  has a plurality of outlet orifices  206  which open out, on the one hand, into the space  203  and, on the other hand, into a peripheral space  207  delimited by a cylindrical peripheral wall  208 , the peripheral wall  207  forming a longitudinal annular outlet collecting chamber. 
     The outlet orifices  206  are distributed around and at a distance from the inlet orifices  204  so as to form a plurality of substantially radial cavitation chambers  209  with substantially parallel flows, which function respectively like the cavitation chambers described in the preceding examples. 
     In the example shown, as shown in more detail in  FIG. 7 , the inlet orifices  204  are distributed evenly spaced apart all around the inner cylindrical wall  201  and longitudinally relative to the latter, and the outlet orifices  206  are distributed evenly spaced apart all around the outer cylindrical wall  202  and longitudinally relative to the latter, offset by half a pitch relative to the inlet orifices  204 , circumferentially and longitudinally. The outlet orifices  206  advantageously have cross-sections which are considerably larger than the cross-sections of the inlet orifices  204 . 
     In the example shown, as shown in more detail in  FIG. 6 , the internal space  205  forming an inlet collecting chamber is closed at one end by a radial wall  205   a  and can communicate at its other end with an axial inlet duct  210  which can be connected to a source of liquid to be treated. The peripheral space  207  forming an outlet collecting chamber is closed at one end by an annular wall  207   a  and can communicate with an axial outlet duct  211  for the liquid treated in parallel in the cavitation chambers  209 , this axial outlet duct  211  being opposite the axial inlet duct  210 . The inner and outer cylindrical walls  201  and  202  are carried at one end by the wall  205   a  and at the other end by the wall  207   a  in leaktight fashion via O-rings  205   b  and  207   b.    
     In other alternative embodiments, the walls  201  and  202  could have different annular shapes, for example have the shape of a truncated cone, or could be flat. 
     In another alternative embodiment, any one of the treatment devices described above could be connected in series, the liquid outlet of one device communicating with the liquid inlet of the following device.