Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
  • B01F27/27—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices
  • B01F27/272—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices with means for moving the materials to be mixed axially between the surfaces of the rotor and the stator, e.g. the stator rotor system formed by conical or cylindrical surfaces
  • B01F27/2722—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices with means for moving the materials to be mixed axially between the surfaces of the rotor and the stator, e.g. the stator rotor system formed by conical or cylindrical surfaces provided with ribs, ridges or grooves on one surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
  • B01F27/27—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices
  • B01F27/272—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices with means for moving the materials to be mixed axially between the surfaces of the rotor and the stator, e.g. the stator rotor system formed by conical or cylindrical surfaces
  • B01F27/2723—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices with means for moving the materials to be mixed axially between the surfaces of the rotor and the stator, e.g. the stator rotor system formed by conical or cylindrical surfaces the surfaces having a conical shape

Definitions

• the present invention relates to a controlled cavitation device.
• a cavitation device is disclosed in EP 610914.
• This device comprises a housing defining a chamber formed by a cylindrical side wall and a pair of end plates, a shaft passing through an axis of the chamber and a rotor mounted on the shaft within the chamber so as to rotate with the shaft.
• the rotor has a surface toward the side wall provided with uniformly-spaced inwardly-directed recesses or bores at a selected angle. These recesses produce turbulence of fluid within a cavitation zone defined between the rotor and the inner surface of the chamber.
• This device comprises also an inlet port for the introduction of fluid into the space between the rotor and the inner surface of the chamber and an outlet port for the removal of treated fluid.
• a first and a second fluid connections are connected to the inlet and outlet ports which are oriented axially or radially in the two proposed embodiments.
• a different cavitation device is disclosed in EP 1289638.
• an inlet port is axially provided on either side of the housing in order to equalize the hydraulic pressure on the rotor and an outlet port is radially provided in the housing in the cylindrical wall of the housing to communicate with the cavitation zone in a region of the rotor intermediate or between the arrays of bores.
• the position of the outlet port ensures that the entire volume of the gas/liquid mixture traverses at least one of the arrays of bores and thus moves through the cavitation zone prior to exiting the housing.
• the cavitation devices mentioned above suffer of problem when treating abrasive fluids, such as biological fluid, manure, sewage, waste, mud any other fluid which incorporates solid particles that may create friction.
• the fluid must vary suddenly its direction and speed when enters and/or exits the chamber of the housing. This change of the direction and speed of the fluid causes wear of the inlet and outlet ports.
• a further cavitation device is disclosed in document EP 15169737 filed by the Applicant.
• This cavitation device comprises: a shaft , a housing, a cylindrical rotor comprising at least two arrays of bores realized on its lateral surface, a fluid inlet conduit and a fluid outlet conduit.
• the inlet direction of the inlet axis of the fluid inlet conduit is perpendicular to the axial direction of the rotor axis of the shaft.
• the outlet direction of the outlet axis of the fluid outlet conduit is perpendicular to the axial direction.
• the inlet and outlet ports of the housing are positioned at an axial position spaced apart from the rotor.
• the object of the present invention is to provide a cavitation device which is more efficient with respect to the known cavitation devices.
• Another object of the present invention is to provide a cavitation device where the direction and speed of the fluid entering and exiting the chamber of the housing is controlled thereby preventing damage of the inlet and outlet ports.
• FIG. 1 shows a top view of a cavitation device according to the present invention
• figure 2 shows a front view of the cavitation device of figure 1 ,
• figure 3 shows a section view of the cavitation device of figure 1 along the section line A- A
• figure 4 shows a perspective view of the cavitation device of figure 1.
• figure 1 shows a cavitation device 10 coupled with an electric motor 1 to define a cavitation apparatus 100.
• the cavitation device 10 comprises a shaft 11, a housing 20 and a rotor 30.
• the shaft 11 extends along an axial direction X-X and is configured to be coupled with the electric motor 1.
• the electric motor 1 comprises a driving shaft 2 coupled with the shaft 11 of the cavitation device 10 through transmission means 3 to put in rotation the shaft 11.
• the housing 20 defines a cylindrical chamber 21 having a inner cylindrical surface 21a and has a fluid inlet port and 22 and a fluid outlet port 23.
• the housing 20 has one single fluid inlet 22 and one single fluid outlet 23.
• the rotor 30 is arranged within the cylindrical chamber 21 of the housing 20 and is mounted on the shaft 11 to rotate about a rotor axis X extending along the axial direction X-X.
• a fluid inlet conduit 24 is coupled to the fluid inlet port 22 for supplying fluid into the cylindrical chamber 21 of the housing 20.
• This fluid inlet conduit 24 has an inlet axis B extending along an inlet direction B-B.
• a fluid outlet conduit 25 is coupled to the fluid outlet port 23 for receiving fluid from the cylindrical chamber 21 of the housing 20.
• This fluid outlet conduit 25 has an outlet axis C extending along an outlet direction C-C.
• the housing 20 comprises a first side wall 26a and a second side wall 26b axially spaced from the first side wall 26a along the axial direction X-X.
• the housing 20 comprises also a cylindrical body 27 extending axially between the first side wall 26a and the second side wall 26b and joining the first and second side walls 26a, 26b.
• the cylindrical body 27 and the first and second side walls 26a, 26b define the cylindrical chamber 21 of the housing 20.
• the rotor 30 comprises a first side surface 31 and a second side surface 32 axially spaced from the first side surface 31 along the axial direction X-X.
• the rotor 30 comprises also a peripheral surface 33 extending between the first side surface 31 and the second side surface 32 and joining the first and second side surfaces 31, 32.
• the rotor 30 is shaped as a conical frustum, which is a truncated cone of a right circular cone having a circular section and two opposite circular base surfaces, i.e., the first and second side surfaces 31, 32, which extend parallel to each other and perpendicular to the axial direction X-X of the rotor Xx.
• the peripheral surface 33 of the rotor 30 is shaped as a conical surface which extends in a tapered manner between the first and second side surfaces 31 , 32.
• first and second side surfaces 31, 32 are the two flat surfaces of the conical frustum, while the peripheral surface 33 is the lateral tapered surface of the conical frustum.
• the radial distance between rotor axis X and the peripheral surface 33 defines the rotor radius R of the rotor 30.
• the axial distance between the first side surface 31 and the second side surface 32 defines the axial extension of the rotor 30.
• the radius R of the conical frustum shaped rotor 30 decreases gradually along the axial direction X-X of the rotor axis X from the first side surface 31 to the second side surface 32, such that the radius R reaches a maximum value on the first side surface 31 and a minimum value on the second side surface 32.
• the maximum radius Rmax corresponds to the maximum radial distance between the rotor axis X and the peripheral surface 33 measured on the first side surface 31 of the rotor 30.
• the minimum radius Rmin corresponds to the minimum radial distance between the rotor axis X and the peripheral surface 33 measured on the second side surface 32 of the rotor 30.
• the cavitation device having a conical frustum shaped rotor 30 provides a more efficient cavitation with respect to the known cavitation devices.
• the conical frustum shaped rotor 30 has an opening angle a ranging from 4° to 60°, more preferably ranging from 10° to 40°, even more preferably the opening angle a measures 20°.
• the opening angle a is the angle comprised between the two generatrix lines G of the peripheral surface 33 (i.e., lateral surface of the cone).
• the perimeter of the base of a cone, i.e., the first side surface 31 is the directrix, and each of the line segments between the directrix and the apex of the cone is a generatrix line G of the peripheral surface 33.
• the opening angle a or otherwise named as the aperture of the right circular cone, is the maximum angle between two generatrix lines G (figure 3).
• the aperture angle of the conical frustum corresponds to the opening angle a measured between two generatrix lines G at the virtual apex of the conical frustum (figure 3).
• each generatrix line G makes an angle a/2 (i.e., the half of the opening angle a) to the axial direction X-X of the rotor axis X (figure 3). Therefore, an alternative way for defining the conicity of the conical frustum would be to refer to the angle a/2.
• the conical frustum shaped rotor 30 has a conicity ranging from 2° to 30°, more preferably ranging from 5° to 20°, even more preferably the conicity is 10°
• At least two arrays of bores 34 are formed in the peripheral surface 33.
• the rotor 30 comprises three arrays of bores.
• the bores 34 of each array of bores are arranged in a row extending around the peripheral surface 33.
• each bore 34 extends radially into the rotor 30 from the peripheral surface 33.
• the bores of the at least two array of bores 34 extend radially into said rotor 30 from said peripheral surface 33 for a depth Db which decreases in adjacent arrays of bores 34 along said axial direction X-X of said rotor axis X from the first side surface 31 to the second side surface 32.
• each array of bores 34 comprises a predetermined number of radial bores 34 which have a predetermined diameter and depth Db.
• the depth Db is maximum Dbmax in the first array of bores 34 which is located on the peripheral surface 33 proximate to the first side surface 31 , which is closer to the fluid inlet 22.
• the depth Db decreases in the next arrays of bores 34 which are closer to the fluid outlet 23 until the last array of bores 34 that has the minimum depth Dbmin, and which is located on the peripheral surface 33 proximate to the second side surface 32, which is closer to the fluid outlet 23 (figure 3).
• this particular configuration of the bores 34 promotes cavitation inside the bores 34.
• cavitation occurs inside the volume defined by each bore 34 in an internal and/or recessed portion of the body of the rotor 30.
• the increased efficiency generated by the conical rotor 30 is consequent to the fact that the fluid velocity decreases subsequently to the first array of bores 34 due to the turbulence created by the first cavitation events. Consequently, cavitation will be less efficient in correspondence the last array of bores 34.
• the conical rotor 30 the speed loss of the fluid determined by the turbulence generated by the bores 34 subsequent to the first array of bores 34 is compensated by the acceleration of the fluid induced by the change (i.e., decrease) in diameter of the conical rotor 30. Therefore, the most preferable technical solution is to realize a conical frustum shaped rotor 30 having an opening angle a that allows fluid to maintain a constant speed.
• the optimum opening angle a can be calculated depending on the design of the rotor and of the power that expresses the same, in order to keep the fluid speed constant along the peripheral surface 33, from the fluid inlet to the fluid outlet.
• the bores 34 of each array of bores have a peripheral circular edge formed in the peripheral surface 33 which is at least partially rounded (figure 3). More preferably, the peripheral circular edge of the bores 34 of each array of bores can be entirely rounded.
• the peripheral circular edge of the bores 34 is rounded by a radius Rb (figure 3) which preferably ranges between 10% of the diameter of the bore 34 and 50% of the diameter of the bore 34, and more preferably the radius Rb measures 30% of the diameter of the bore 34.
• this particular configuration of the bores 34 improves cavitation control inside the bores 34, especially if combined in a synergic manner with the above mentioned variable depth configuration of the adjacent arrays of bores 34.
• a cavitation zone 35 is defined inside the bores 34.
• the bores 34 can be realized as holes and/or recesses and/or grooves which extend into the body of the roto 30 from the peripheral surface 33. More preferably, the bores 34 can be shaped as bores or recesses with variable depth, and with different section profiles, such as circular, polygonal, rectangular, triangular, etc. In other words, the bores 34 can be realized with different shapes in order to improve cavitation inside the bores 34.
• the cylindrical chamber 21 comprises an inlet cylindrical chamber 28a formed between the first side surface 31 and the first side wall 26a and an outlet cylindrical chamber 28b formed between the second side surface 32 and the second side wall 26b.
• the fluid inlet port 22 is positioned in the housing 20 to introduce fluid into the inlet cylindrical chamber 28a at an axial position spaced apart from the first side surface 31 of the rotor 30.
• the fluid outlet port 23 is positioned in the housing 20 to receive fluid from the outlet cylindrical chamber 28b at an axial position spaced apart from the second side surface 32 of the rotor 30.
• the axial distance between the fluid inlet port 22 and the first side surface 31 of the rotor 30 is equal to or greater than the axial extension of the rotor 30.
• the axial distance between the fluid outlet port 23 and the second side surface 32 of the rotor 30 is equal to or greater than the axial extension of the rotor 30.
• the inlet direction B-B of the inlet axis B is perpendicular to the axial direction X-X of the rotor axis X and the outlet direction C-C of the outlet axis C is perpendicular to the axial direction X-X of the rotor axis X.
• the fluid inlet conduit 24 and the fluid outlet conduit 25 are arranged on the stator 20 such that the fluid supplied through the fluid inlet port 22 and delivered through the fluid outlet port 23 follows within the cylindrical chamber 21 a helical path.
• the inlet axis B and the outlet axis C are substantially tangential to this helical path.
• the inlet cylindrical chamber 28a and the outlet cylindrical chamber 28b make available two chamber so that, in use, the mass of fluid axially arranged before the rotor 30, in the inlet cylindrical chamber 28a, and after the rotor 30, in the outlet cylindrical chamber 28b, guarantee a rotational inertia which opposes the axial speed of the fluid, with respect to the radial and tangential speed set by the speed of the rotor 30.
• the axial speed of the fluid is independent from the speed of the rotor 30 and the cavitation is thereby controlled.
• the inlet port 22 is positioned in the housing 20 to introduce fluid into the inlet cylindrical chamber 28a at an axial position adjacent to the first side wall 26a of the housing 20 and the outlet port 23 is positioned in the housing 20 to receive fluid from the outlet cylindrical chamber 28b at an axial position adjacent the second side wall 26b of the housing 20.
• the fluid inlet conduit 24 and the fluid outlet conduit 25 are positioned such that the inlet axis B and the outlet axis C are parallel to and proximate to respective tangential directions to the peripheral surface 33 of the rotor 30 or to respective tangential directions to the inner cylindrical surface 21a of the cylindrical chamber 21 of the stator 20.
• the fluid inlet conduit 24 and the fluid outlet conduit 25 have respective first portions 24a, 25a facing a respective plane, in the example a same plane P', passing through the rotor axis X and parallel to the corresponding inlet axis B and outlet axis C and opposite second portions 24b, 25b.
• the second portions 24b, 25b of the fluid inlet conduit 24 and the fluid outlet conduit 25 join the stator 20 substantially tangentially to the inner cylindrical surface 21a of the cylindrical chamber 21 of the stator 20.
• the inlet axis B and the outlet axis C are parallel.
• the distance between the outlet axis C and the rotor axis X along a direction Y-Y perpendicular to the outlet axis C and the rotor axis X ranges between 70% and 100% the rotor maximum radius Rmax measured on the first side surface (31).
• the inlet axis B and the outlet axis C intersect a plane P passing through the rotor axis X and perpendicular to the inlet and outlet axes B, C at a distance D from the rotor axis X between 70% and 100% the rotor maximum radius Rmax measured on the first side surface (31).
• the housing 20 comprises two lateral portions 20a, 20b defined at opposite sides relative to the plane P passing through the rotor axis X and perpendicular to the inlet and outlet axes B, C.
• the fluid inlet port 22 and the fluid outlet port 23 are positioned on one of the two lateral portions 20a, 20b, namely in the lateral portion 20a.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

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Citations (7)

• 2016
  • 2016-08-03 EP EP16182624.3A patent/EP3278868B1/de active Active
• 2017
  • 2017-08-03 WO PCT/EP2017/069609 patent/WO2018024810A1/en active Application Filing

Patent Citations (7)

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