EP1985357A1

EP1985357A1 - Method and apparatus for processing liquids under cavitation conditions

Info

Publication number: EP1985357A1
Application number: EP08460013A
Authority: EP
Inventors: Andrzej Podwysocki; Tomasz Rybicki
Original assignee: Podwysocka Violetta; Podwysocki Spolka Jawna
Current assignee: Podwysocka Violetta; Podwysocki Spolka Jawna
Priority date: 2007-04-24
Filing date: 2008-04-21
Publication date: 2008-10-29
Also published as: PL382264A1; PL211672B1

Abstract

A method and apparatus for processing liquid fluids with use of cavitation process is being disclosed, consisting of bringing a liquid to be cavited in between two planar elements, one stationary, one rotary, said planar elements having regular, concentric structure of alternate protrusion and channels, divided into arched segments by radial channels in both planar elements, complementary on both stationary and rotary elements, so they create labyrinth like arrangement, with some clearance in both radial and axial directions, between the protrusions and channels which create said labyrinth. The process is particularly suitable for heating liquid fluids, mixing different liquids, dispersing suspensions within liquid fluid, decontamination of wastewater and many other processes.

Description

Technical field

The present invention relates to method and apparatus for creating cavitation process within liquid fluids by means of flow through an apparatus containing rotating and stationary elements, with a gap between them through which a flow of a liquid passes through.

Background of the invention

According to Bernoulli's principle, as the flow velocity of a liquid increases at any given elevation, the pressure will drop. If the velocity is becoming high enough, the pressure can become so low that the liquid flashes over into small vapor bubbles, which then collapse suddenly. Usually this is to be avoided, because it causes damage to the apparatus elements, like centrifugal pumps rotors, screw propellers and so on. Nevertheless the cavitation process is advantageously applied in many fields like liquid mixing, decontamination of used water, heating of liquids, creating of colloidal suspensions and so on.
There are many methods of creating cavitation for use in various processes. One of which consists of forcing liquid to flow though a gap between a stationary element and high speed-rotating element of which one having a surface directed to the gap smooth, the other having on the surface directed to the gap blind holes, channels protrusion etc. Apparatus for this method, which was disclosed in US patent No 5,385,298 , consists of a housing within which rotates a cylindrical rotor having a quantity blind holes on its external surface. The housing has inlet and outlet stub pipes at its opposite ends, and liquid is forced to flow through the gap between the rotating rotor and the internal surface of the housing. Another apparatus which can be applied for this method was disclosed in PCT patent No WO 2005/030659 A1 , the apparatus consisting of two planar elements, one stationary, one rotating with gap between them, contained in a housing having liquid inlet and outlet, where one of the planar elements having a flat, smooth surface and the second having a structure on its internal surface, facing the first planar element, said structure consisting of system of protrusions and channels, facilitating creation of the cavitation bubbles. Cavitation creating by the known apparatus is turbulent and fluctuant, difficult to control, and difficult to adapt for processing various liquids, which can be contaminated with various suspensions, or of various density, and difficult to adapt for various purposes like mixing, dispersing or decontamination, or heat generating.

Summary of the invention

The method according to this invention consists of bringing a liquid to be processed in between two planar, round elements, one stationary one rotary, having regular, concentric structure of alternate protrusion and channels, divided into arched segments by radial channels in both planar elements, complementary on both stationary and rotary elements, so they create labyrinth like arrangement, with some clearance in both radial and axial directions, between the protrusions and channels which create said labyrinth, putting into motion the rotary element, catching liquid adhering to the rotating surfaces, creating difference of velocity of liquid flow within the circular spaces of said labyrinth, and consequently, creating the pressure difference along the channels of said labyrinth, where the pressure decreases in the direction of rotation, and increasing the velocity of the rotating element up to the point when the liquid pressure falls beyond the vapor point thus creating cavitation bubbles, and causing the liquid to flow in self-sucking manner or in assisted manner, the last, by adding an action of an auxiliary pump and intensifying the process cavitation .by pressing the liquid into radial channels in both stationary and rotating elements, and due to rotation of the rotary element, closing and opening said radial channels in rapid succession thus creating micro-jets which enhance the process of cavitation bubbles' creation, where the process of cavitation bubbles is most efficient when the rotational velocity of rotating element is contained within the range of 1500 -5000 r.p.m. The process according this invention is controlled by changing rotational velocity of said rotating element and by changing the quantity and pressure of liquid delivered by auxiliary pump. The process according to the invention is applied to heating liquids, mixing of various liquids, colloids producing, waste water decontamination, sewage cleaning and the likes.
The apparatus for carrying out the method according to this invention is composed of a conventional, stationary housing, having inlet and outlet of liquid to be processed, where inside the housing there are two planar round elements, at the peripheries of which, within the housing, is situated a collecting chamber, in the shape of quasi spiral, constituting outlet manifold, one planar element being stationary and the second one being rotary and being fixed on a rotating shaft, said planar elements facing each other, and creating a narrow space between them, where on faces of said planar elements , directed to each other, there are a system of concentric protrusions and channels, divided into arched segments by radial channels on both planar elements, formed in such a manner, that protrusions of one planar element enter into channels of the opposite planar element, where said liquid inlet to the housing is being connected to the said space between said stationary planar element and rotary planar element and liquid outlet is connected to said collecting chamber situated within the housing in the proximity of the periphery of said rotating element. Between the protrusions and channels in both planar elements there is a clearance, in both radial and axial directions, creating labyrinth like passing for the liquid, where the size of said clearance is selected from the range of a fraction of millimeter to four millimeters.. In preferred embodiment the protrusion segments and channel segments are strictly rectangular in section along axis of rotation, in another embodiment arched segments at sides along the circumferential channels, having a form of arcs, in still another embodiment, the radial channels have form of spiral segments directed in the direction of rotation of said rotating element. In yet another embodiment the protrusion segments in section along the axis of rotation have form of sinusoids. In still another embodiment the protrusion segments and fitting channels have various width, the wider in the proximity of axis of rotation of said rotary element, and narrower in the proximity of periphery of the planar elements, where the width of the protrusion and channels changes along radius of the planar elements. In still another embodiment there is a doubled arrangement consisting of two stationary planar elements and one rotary element situated between them, where the said rotary element has two surfaces with the system of protrusions and channels on its opposite sides, facing two respective surfaces of stationary elements, where the device has two liquid inlets connected to the housing at opposite sides of the rotary element, and one outlet situated on the mutual collecting chamber, which is in the quasi spiral shape, situated at the periphery of said rotary planar element within the housing. In an embodiment of said doubled arrangement the rotating element has form of wedge in section along the axis of rotation with fitting form of stationary elements, where the base of said wedge is fixed on the rotating shaft.. The protrusions of both rotary and planar elements are made from corrosion resistant material, in some embodiments from stellite.

Brief description of the drawings

Fig 1 is a cross sectional view of a basic embodiment of a device according to the present invention;
Fig 2 is a view of a rotating planar element illustrating the structure of concentric protrusions and concentric channels and radial channels;
Fig 3 illustrates a partial axonometric view of the arrangement of protrusions and channels in the planar elements;
Fig 4 illustrates the same partial axonometric view of the system of protrusions and channels in the planar element, but with arc wise form of protrusions sides along the circumferential channels;
Fig 5 illustrates a segment of protrusion taken from Fig 4 along arrow "W"
Fig 6 illustrates a segment of protrusion taken from Fig 4 along arrow "Z"
Fig 7 illustrates the view of protrusion and channel system of the rotating planar element, where the radial channels constitute segments of a spiral
Fig 8 is a fragment of cross sectional view of protrusions and channels arrangement where the protrusions and channels sides are in form of sinusoids;
Fig 9 is a fragment of cross sectional view of protrusions and channels system, where the protrusions and respective channels have different widths;
Fig 10 is a schematic expanded axonometric view of the device in doubled arrangement
Fig 11 is a cross sectional view of the device type illustrated in Fig 8, where the rotating element is of tapered shape

The mode for carrying out the invention

As shown in Fig 1, the device according to the invention, in briefest terms, is composed of a conventional, stationary housing 1, having inlet 2, communicated with an inlet chamber 18 in said housing 1 and outlet 3 of cavitated liquid, where inside the housing there are two planar round elements, a rotary planar element 4 on a shaft 5 and a stationary planar element 6 , spaced from each other, where the stationary element 6 being fixed to the housing 1, or constituting the extension part of the housing 1, where the internal periphery of said housing 1 constitutes a collecting chamber 7 , situated within the housing in the proximity of the periphery of said rotating element, said chamber 7 , constitutes outlet manifold, being shaped in a manner of quasi spiral. Said planar elements 4 and 6 , have on faces directed to each other, a system of concentric protrusions 8a on the stationary element and 8b on the rotary element and respective concentric channels 9a, on the stationary element and 9b on rotary element, formed in such a manner, that protrusions of one planar element enter into channels of the opposite planar element, where said concentric protrusions 8a and 8b on both planar elements_are divided into arched segments of longer sides in arcs, by radial channels10 (Fig 2) in both said planar elements, where said liquid inlet 2 to the housing 1 is connected through the chamber 18 to space between said rotating element 4 and stationary element 6, and cavited liquid outlet 3 is connected to said collecting chamber 7situated within the housing 1 in the proximity of the periphery of said rotating element. Between the protrusions 8a and bottoms of channels 9b, there is a clearance α, and between bottoms of channels 9a and protrusions 8b there is a clearance β, and between radial sides of protrusion segments 8a and 8b there is a clearance γ, thus creating labyrinth like passage for the liquid to be cavitated. The sizes of the clearances α, β, γ are selected from a portion of millimeter to 4 millimeters, preferably 1 millimeter. In preferred embodiment the sides of arched segments being strictly rectangular in section along axis of rotation,(Fig 3), in another embodiment arched segments at sides along the circumferential channels, having a form of arcs with radius r (Fig 4, Fig 5 and Fig 6), in still another embodiment, the radial channels 10 have form of spiral segments (Fig 7),directed in the direction of rotation of said rotating element 4. In yet another embodiment the protrusion and channel segments in section along the axis of rotation of said rotary element have form of sinusoids, with a gap δ (Fig 8). In still another embodiment the protrusion segments and respective channels have various width,(Fig 9), the wider in the proximity of axis of rotation of the rotary element, and narrower in the proximity of periphery of the planar elements, where the width of the protrusions and channels changes along radius of the planar elements In still another embodiment there is a doubled arrangement (Fig 10) consisting of two stationary planar elements 12 being fixed to the housing or constituting the extension portions of the housing, which, is , in this arrangement, composed of two separate parts 13 and 14, and having one rotating element 15 situated between said stationary elements 12, where the said rotating element 15 has two surfaces with the system of protrusions 8 and channels 9 on its opposite sides, facing two respective surfaces of stationary elements 12 ,where the device has two liquid inlets 2 connected to each parts of the housing 13 and 14, and one outlet 3 situated on the mutual collecting chamber 16 of the quasi spiral shape, situated at the periphery of said planar elements 12 and rotary element 15 within the both parts 13 and 14 of the doubled housing. One embodiment of said double arrangement of the apparatus for carrying out the method according to the invention is that, where the rotating element has a form wedge in the section along the axis of rotation of rotary element, with fitting shape of stationary elements. (Fig 11). The material of which are made the both planar elements is corrosion resistant, and cavitation resistant, preferably stellite.
The apparatus according to the invention operates in such a manner that a liquid to be processed enters into inlet stub pipe 2 either entirely by self-suction action or being additionally fed from a pump, not shown, and then enters into inlet chamber 18 and then, to the labyrinth like gap created by clearances α, β, γ between rotary element 4 and stationary element 6 . Rotary element rotates with speed selected from the range from 1500 rpm to 5000 rpm, preferably 3000 r.p.m. The cavitation process is being created under action of rotation of said rotary element 4 where its protrusions 8b shaped into arched segments 8 catch the liquid contained within gap formed by the clearances α, β, γ thus giving them speed, while the protrusion segments 8a of stationary elements hold the liquid, creating considerable difference of speed of the liquid within the gap, from near zero speed close to stationary surfaces to maximum speed close to rotating surfaces, thus creating pressure difference, and when the rotational speed of said rotary element 4 or 15 is high enough, the lower pressure within the gap falls under vapor point of the liquid thus creating cavitation bubbles. The cavitation process is being enhanced by the portions of the liquid, which enter into radial channels 10and then, which are pushed out in quick succession in form of micro-jets by protrusions 8b.
The apparatus according to the invention is preferably applied for heating liquids, (basic embodiment), for mixing two separate liquids, (embodiment in double arrangement) or for producing colloidal dispersion (in basic or double arrangement embodiment).
Changing the rotational speed of the rotary element, or increasing the clearance α between said planar elements or, changing the pressure and flow of the liquid from the pump, if the pump is applied, are factors by which the cavitation process can be easily controlled..

Claims

The method according to this invention consisting of bringing a liquid to be processed in between two planar elements, one stationary, one rotary, characterized by the fact, that said planar elements having regular, concentric structure of alternate protrusion and channels, divided into arched segments by radial channels in both planar elements, complementary on both stationary and rotary elements, so they create labyrinth like arrangement, with some clearance in both radial and axial directions, between the protrusions and channels which create said labyrinth, putting into motion the rotary element, catching liquid adhering to the rotating surfaces, creating difference of velocity of liquid flow within the circular spaces of said labyrinth, and consequently, creating the pressure difference along the channels of said labyrinth, where the pressure decreases in the direction of rotation, and increasing the velocity of the rotating element up to the point when the liquid pressure falls beyond the vapor point thus creating cavitation bubbles, and causing the liquid to flow in self-sucking manner or in assisted manner by adding an action of an auxiliary pump and intensifying the process cavitation .by pressing the liquid into radial channels in both stationary and rotating elements, and closing and opening said radial channels in rapid succession thus creating micro-jets which enhance the process of cavitation bubbles' creation.
Apparatus for carrying out the method according to invention, being composed of a conventional, stationary housing, having inlet of liquid to be processed, and outlet of cavitated liquid, where inside the housing there are two planar round elements, at the peripheries of which is situated a collecting chamber within the housing, constituting outlet manifold, one planar element being stationary and the second one being rotary and being fixed on a rotating shaft, said planar elements facing each other, and creating a narrow space between them, characterized by the fact, that on faces of said planar elements ( 4 and 6 ), directed to each other, there are a system of concentric protrusions( 8a and 8b ) and channels ( 9a and 9b ), formed in such a manner, that protrusions of one planar element enter into channels of the opposite planar element, where said concentric protrusions are divided into arched segments by radial channels(10) in both said planar elements, where said liquid inlet(2)to the housing (1) being connected to the said space between said stationary planar element (6) and rotary planar element (4), and liquid outlet(3) is connected to said collecting chamber(7) situated within the housing (1)in the proximity of the periphery of said rotating element (4)
Apparatus according to claim2, characterized by the fact, that between the protrusions ( 8a and 8b )and channels( 9a and 9b ) in both planar elements ( 4 and 6 )there is a clearance α, β, γ, in both radial and axial directions, creating labyrinth like passing for the liquid, where the size of said clearance is selected from the range of a fraction of millimeter to four millimeters
Apparatus according to claim2, characterized by the fact, that in preferred embodiment the protrusion and channel segments are strictly rectangular in section along axis of rotation
Apparatus according to claim2, characterized by the fact, that in another embodiment the arched segments at sides along the circumferential channels, having a form of arcs with radius r
Apparatus according to claim2, characterized by the fact, that in another embodiment the radial channels ( 10 ) have form of spiral segments directed in the direction of rotation of said rotating element
Apparatus according to claim2, characterized by the fact, that in another embodiment the protrusion and channel segments in section along the axis of rotation have form of sinusoids
Apparatus according to claim2, characterized by the fact, that in another embodiment the protrusion segments (8)and fitting channels (9) have various width, the wider in the proximity of axis of rotation of said rotary element, and narrower in the proximity of periphery of the planar elements where the width of protrusions and channels changes radially.
Apparatus according to claim2, characterized by the fact, that in another embodiment there is a doubled arrangement consisting of two stationary planar elements (12) and one rotary element (15) situated between them, where the said rotary element(15) has two surfaces with the system of protrusions(8) and channels (9) on its opposite sides, facing two respective surfaces of stationary elements, where the device has two liquid inlets (2) connected to the housings (13 and 14) at opposite sides of the rotary element (15) and one outlet (3) situated on the mutual collecting chamber(16) situated in the vicinity of the periphery of said rotary planar element.(15)
Apparatus according to claim 9, characterized by the fact, that in another embodiment of said doubled arrangement the rotating element(15) has form of wedge in section along the axis of rotation with fitting form of stationary elements, where the base of said wedge is fixed on the rotating shaft (5)
Apparatus according to claim2, characterized by the fact, that the protrusions of both rotary and planar elements are made from corrosion resistant material
Apparatus according to claim2, characterized by the fact, that the protrusions of both rotary and planar elements are made from stellite
Apparatus according to claim2, characterized by the fact, that rotational speed of said rotary element is selected from range from 1500 r.p.m to 5000 r.p.m.
Apparatus according to claim2 and 9 characterized by the fact, that the collecting chamber ( 7 or 16 )is of quasi spiral shape