DE102022211480A1 - Device and method for generating a pulsating liquid jet containing cavitation bubbles for the cavity-forming removal of material from solid bodies, in particular rocks - Google Patents

Abstract

A method for generating a pulsating liquid jet containing cavitation bubbles for the cavity-forming removal of material from solid bodies, in particular rocks, by cavitation erosion uses a device (100a) which has a cavitation nozzle (3a) which has a nozzle body (4) through which a first flow channel (5) extends with an inlet (6) for the entry of the pulsating liquid jet and an outlet (7) for the pulsating liquid jet containing cavitation bubbles. A device arranged upstream of the cavitation nozzle (3a) for generating a self-induced pulsating movement in the liquid jet has a housing detachably connected to the nozzle body (4), through which a second flow channel (16) extends with an inlet (17) connectable to a pressurized fluid source and an outlet (18) which opens into a cavity (23) which is connected to the inlet (6) of the first flow channel (5). To structurally simplify the device and increase the erosive effect of the liquid jet, the housing comprises an outer housing part (1) and an inner housing part (2) having the second flow channel (16), which is arranged in the outer housing part (1) so as to be movable in and against the flow direction.

Description

The invention relates to a device and a method for generating a pulsating liquid jet containing cavitation bubbles for the cavity-forming removal of material from solid bodies, in particular rocks, with a cavitation nozzle which has a nozzle body through which a first flow channel extends with an inlet for the entry of the pulsating liquid jet and an outlet for the pulsating liquid jet containing cavitation bubbles, and with a device arranged upstream of the cavitation nozzle for generating a pulsating movement in the liquid jet, wherein the device has a housing detachably connected to the nozzle body, through which a second flow channel extends with an inlet connectable to a pressurized fluid source and an outlet which opens into a cavity which is connected to the inlet of the first flow channel.

Such a device is known from US-PS 3528704 In this device, a constant flow of pressurized fluid is fed into a central distributor housing, from which the pressurized fluid is fed via radially running pipes to a number of cavitation nozzles corresponding to the number of pipes, each of which has a nozzle body through which a flow channel extends between a laterally arranged inlet and a centrally arranged outlet, which narrows towards the outlet, whereby cavitation bubbles form in the liquid jet emerging from the outlet, which contribute to the material being removed from a solid body by cavitation erosion, forming a cavity when the liquid jet hits the solid body. To increase the eroding effect of the liquid jet, the constant flow of pressurized fluid fed into the distributor housing is given a pulsating movement by actuating valves that are arranged at the inlet of the radially running pipes in the distributor housing. The use of valves to generate a pulsating movement in the liquid jet is technically complex and leads to a loss of flow energy. In addition, the valves are subject to wear and tear and are therefore susceptible to failure. Furthermore, friction in the pipes reduces the pulsating movement of the fluid flow. The result is that the fluid jet emerging from the cavitation nozzle only pulsates at a weaker rate, meaning that the eroding effect of the fluid jet is not significantly increased by the pulsation of the pressure fluid flow.

From the US Patent 5495903 is a nozzle that generates a pulsating fluid flow for installation in a drilling tool for rock drilling. The pulsating movement of the fluid flow is generated in this nozzle without the use of additional movable flow control valves or the like. It is therefore referred to as a "self-induced" pulsating movement. This nozzle has a nozzle body through which a flow channel extends, which has an inlet for the entry of a pressurized fluid into the flow channel and an outlet that opens into a cylindrical cavity in the nozzle body. The cavity has a wider cross-section than the circular cross-section at the outlet of the flow channel and is delimited by two opposing flat wall sections of the nozzle body that extend transversely to the flow direction and by a cylindrical wall section of the nozzle body. The cavity is connected to the inlet of another flow channel that is located in the nozzle body and is arranged axially aligned with the one flow channel. The circular cross-section of the further flow channel at its inlet is larger than the circular cross-section of the one flow channel at its outlet and smaller than the cross-section of the cavity, the distance between the two opposite wall sections of the nozzle body running transversely to the flow direction being fixed. An increase in the speed of the pulsating liquid jet emerging from the further flow channel can be achieved by the liquid jet entering a further cavity in the nozzle body and leaving the further cavity again via a third flow channel which has a cross-section which is smaller than the cross-section of the further cavity and larger than the cross-section of the further flow channel. The shape, arrangement and relative dimensions of the flow channels and the cavity or cavities alone impose a self-induced pulsating movement on the liquid flow entering the cavity through the one flow channel, which it retains when it exits the further flow channel. However, this liquid flow does not have cavitation bubbles, so that its eroding effect is weak.

From the US Patent 8424620 A method and a device for creating lateral underground boreholes that extend laterally away from a vertical main borehole are known. In this case, a cavitation or pulsation nozzle is used for the discharge of a cavitating or pulsating fluid jet in order to guide the drilling tool during cavity-forming removal. of rock material laterally from the vertical main borehole.

The object of the invention is to further develop the generic device in such a way that the structural complexity for the device is reduced, the eroding effect of the liquid flow impinging on the solid body is increased and a simple and rapid adaptation of the device and the eroding effect achieved with it to a changed nature of the solid body to be processed is possible. A method is also to be specified in which this device can be used.

The object is achieved according to the invention by a device according to claim 1 and a method according to claim 14. Advantageous further developments of the invention can be found in the subclaims.

The device according to the invention has the advantage of a compact design, particularly in comparison to the device known from the US patent, as well as the advantage of being able to quickly and easily change the geometry of the components of the device that generate the pulsation and cavitation, the modular design of the device and the axial displaceability of the inner housing part contributing significantly to the geometry of these components being able to be changed quickly and easily if the respective nature of the solid bodies to be processed requires changes in the intensity of the pulsation and/or cavitation of the liquid jet.

• 1 einen äußeren Gehäuseteil der erfindungsgemäßen Vorrichtung schematisch im Querschnitt,
• 2 einen inneren Gehäuseteil der erfindungsgemäßen Vorrichtung schematisch im Querschnitt,
• 3 die gesamte erfindungsgemäße Vorrichtung einschließlich einer ersten Ausführungsform einer Kavitationsdüse schematisch im Querschnitt,
• 4 die gesamte erfindungsgemäße Vorrichtung einschließlich einer zweiten Ausführungsform der Kavitationsdüse schematisch im Querschnitt,
• 5 die gesamte erfindungsgemäße Vorrichtung einschließlich einer dritten Ausführungsform der Kavitationsdüse schematisch im Querschnitt,
• 6 die gesamte erfindungsgemäße Vorrichtung einschließlich einer vierten Ausführungsform der Kavitationsdüse schematisch im Querschnitt,
• 7 eine größere Darstellung der gesamten erfindungsgemäßen Vorrichtung einschließlich der nur als Beispiel gewählten ersten Ausführungsform der Kavitationsdüse schematisch im Querschnitt, wobei zusätzlich einige nur als Beispiel gewählte Maße und Maßbereiche von baulichen Merkmalen der erfindungsgemäßen Vorrichtung angegeben sind,
• 8 eine schematische Darstellung eines mit der erfindungsgemäßen Vorrichtung erzielbaren unterirdischen Bohrungsmusters, das eine vertikale Hauptbohrung, eine davon abgezweigte seitliche Bohrung und ein davon abgehendes Mikrobohrloch beinhaltet,
• 9 eine schematische perspektivische Darstellung eines gesamten mit der erfindungsgemäßen Vorrichtung erzielbaren unterirdischen Bohrmusters, das eine vertikale Hauptbohrung, davon auf verschiedenen Höhen der Hauptbohrung abgezweigte radiale und seitliche Bohrungen und von den radialen und seitlichen Bohrungen ausgehende Mikrobohrlöcher enthält,
• 10a ein Foto eines mit der erfindungsgemäßen Vorrichtung in einem Sandstein erzeugtes Bohrloches mit den beim Erzeugen des Bohrloches entstandenen, unregelmäßig verteilten und unterschiedlich tiefen, seitlichen Mikrobohrlöchern,
• 10b ein vergrößerter Ausschnitt aus dem in 10a gezeigten Foto, und
• 11 eine Tabelle, die für verschiedene beispielhafte Eingangsdruckwerte („Inlet/Pump pressure“)in bar am Eingang des ersten Strömungskanals der erfindungsgemäßen Vorrichtung und für die entsprechenden Ausgangsdruckwerte („Outlet/bit pressure“)in bar am Ausgang der Kavitationsdüse und für die daraus errechneten Druckverhältnisse („Pressure ratio“) die jeweilige Stärke („Effect“) der Kavitation und Pulsation des Flüssigkeitsstrahles mit der Bezeichnung „Maximal“ („Maximum“) oder „Schwach“ („Mild“) wiedergibt.

An embodiment of the invention is shown in the accompanying drawings and is described in more detail below with reference to the drawings. It shows

• 1 an outer housing part of the device according to the invention schematically in cross section,
• 2 an inner housing part of the device according to the invention schematically in cross section,
• 3 the entire device according to the invention including a first embodiment of a cavitation nozzle schematically in cross section,
• 4 the entire device according to the invention including a second embodiment of the cavitation nozzle schematically in cross section,
• 5 the entire device according to the invention including a third embodiment of the cavitation nozzle schematically in cross section,
• 6 the entire device according to the invention including a fourth embodiment of the cavitation nozzle schematically in cross section,
• 7 a larger representation of the entire device according to the invention including the first embodiment of the cavitation nozzle chosen only as an example, schematically in cross section, with some dimensions and dimension ranges of structural features of the device according to the invention chosen only as an example being indicated,
• 8th a schematic representation of an underground borehole pattern achievable with the device according to the invention, which includes a vertical main borehole, a lateral borehole branching off from it and a microborehole branching off from it,
• 9 a schematic perspective view of an entire underground drilling pattern that can be achieved with the device according to the invention, which includes a vertical main borehole, radial and lateral boreholes branching off from it at different heights of the main borehole and microbores emanating from the radial and lateral boreholes,
• 10a a photograph of a borehole created in a sandstone using the device according to the invention, with the irregularly distributed and differently deep lateral micro-bores created during the creation of the borehole,
• 10b an enlarged section of the 10a shown photo, and
• 11 a table which shows the respective strength (“effect”) of the cavitation and pulsation of the liquid jet with the designation “maximum” (“maximum”) or “mild” (“mild”) for various exemplary inlet pressure values (“inlet/pump pressure”) in bar at the inlet of the first flow channel of the device according to the invention and for the corresponding outlet pressure values (“outlet/bit pressure”) in bar at the outlet of the cavitation nozzle and for the pressure ratios (“pressure ratio”) calculated therefrom.

First, the 1 , 2 , 3 and 7 As can be seen from these figures, a device 100a according to the invention for generating a pulsating liquid jet containing cavitation bubbles for the cavity-forming removal of material from solid bodies, in particular rocks, has a cavitation nozzle 3a which has a nozzle body 4 through which a first cylindrical flow channel 5 with an inlet 6 for the entry of the pulsating liquid ity jet and an outlet 7 for the pulsating liquid jet containing cavitation bubbles. Furthermore, the device 100a has a device for generating a pulsating movement in the liquid jet, arranged upstream of the cavitation nozzle 3a. This device has a housing consisting of an outer housing part 1 and an inner housing part 2, the inner housing part 2 being accommodated in the outer housing part 1 so as to be movable in and against the flow direction F of the liquid jet, as described in more detail below.

The outer housing part 1 has a cylindrical outer surface and a concentrically arranged interior space 8 which is open at its opposite ends and which comprises an upstream cylindrical section 9 and a downstream cylindrical section 10 which has a smaller diameter than the upstream section 9 of the interior space 8. Between the two cylindrical sections 9 and 10 of the interior space 8 there is an annular flat transition surface 11a. The cylindrical section 10 has an internal thread 12 with which an external thread 13 on a cylindrical section 14 of the inner housing part 2 is engaged.

The inner housing part 2 has a further cylindrical section 15 which is located upstream of the cylindrical section 14 and has a larger diameter than the cylindrical section 14. Between the two cylindrical sections 14 and 15 there is a flat annular transition surface 11b. The diameters of the cylindrical sections 9 and 15 are matched to one another in such a way that the cylindrical section 15 of the inner housing part 2 fits into the cylindrical section 9 of the interior 8 of the outer housing part 1 with clearance.

The inner housing part 2 has a concentrically arranged second flow channel 16 which extends between an inlet 17, which can be connected to a pressure fluid source (not shown), at the upstream end of the inner housing part 2 and an outlet 18 at the downstream end of the inner housing part 2, wherein the second flow channel 16 has several sections which follow one another in the direction of flow, of which a section 19 which tapers conically in the direction of flow is arranged between two cylindrical coaxial sections 20 and 21, of which the upstream cylindrical section 20 has a larger diameter than the downstream cylindrical section 21, which extends to the outlet 18 of the second flow channel 2. A further cylindrical section 22, which has a larger diameter than the section 20 and the section 21, extends between the cylindrical section 20 and the inlet 17 of the second flow channel 16.

The cylindrical section 21 of the second flow channel 16 opens at its outlet 18 into a cavity 23 which is delimited by a flat second wall section 24 of the inner housing part 2 having the outlet 18 of the second flow channel 16, an opposite first wall section 25 of the nozzle body 4 having the inlet 6 of the first flow channel 5 and an inner cylindrical wall section 26 of the outer housing part 1. The cylindrical wall section 26 and the cylindrical section 10 of the interior 8 have the same diameter.

The first wall section 25 of the nozzle body 4 of the cavitation nozzle 3a is conically convex and projects into the cavity 23 and is surrounded by an annular flat wall section 27 (contact surface) of the nozzle body 4. An annular flat wall section 28 (front surface) of the outer housing part 1 and the annular flat wall section 27 lie against one another and are pulled against one another by screws 29 which detachably connect the nozzle body 4 and the outer housing part 1.

The first flow channel 5 opens at its outlet 7 into a conically widening recess 30 in the nozzle body 4 of the cavitation nozzle 3a.

By rotating the inner housing part 2 relative to the outer housing part 1, the inner housing part 2 is moved in or against the flow direction depending on the direction of rotation as a result of the engagement between the external thread 13 on the cylindrical section 14 of the inner housing part 1 and the internal thread 12 in the cylindrical section 10 of the interior 8 of the outer housing part 1, with the wall section 24 of the inner housing part 2 moving accordingly. A movement of the wall section 24 in or against the flow direction also changes the distance D between the wall sections 24 and 25, with the distance between these two wall sections determining the maximum length of the cavity 23.

In the 3 and 7 In the position of the inner housing part 2 shown, the annular flat transition surfaces 11a and 11b lie against one another, whereby further movement of the inner housing part 2 in the flow direction relative to the outer housing part 1 is prevented.

During operation of the device according to the invention, pressure fluid, such as water at ambient temperature, is fed from the pressure fluid source (not shown) to the inlet 17 of the second flow channel 16 in the inner housing part 2. In the flow channel 16, the speed of the liquid flow is increased due to the cross-sectional reduction of the flow channel progressing towards the outlet 18 of the second flow channel 16. When the liquid flow accelerated in the second flow channel 16 enters the cavity 23, the flow cross-section of the liquid flow suddenly expands to the significantly larger diameter of the cavity 23. This causes the formation of violent flow vortices in the liquid flow in the cavity 23, which in turn results in rapid pulsation of the liquid flow. The pulsation of the liquid flow is therefore induced by the flow itself. The pulsating flow leaves the cavity 23 via the first flow channel 5 in the cavitation nozzle 3a, whereby the speed of the pulsating flow in the first flow channel 5 is accelerated again due to the cross-section of the first flow channel 5 being considerably reduced compared to the cavity 23, and its pressure is reduced at least to such an extent that when the liquid jet exits the outlet 7 of the cavitation nozzle 3a, cavitation bubbles form in the pulsating liquid jet, which implode when they hit the solid body, whereby material is removed from the solid body, forming a cavity.

• Durchmesser des ersten Strömungskanals 5:2,4 mm;
• Durchmesser des zweiten Strömungskanals 16 am Ausgang 18: 2,0 mm;
• Maximale Länge des Hohlraumes 23: im Bereich zwischen 7 und 18 mm;
• Durchmesser des Hohlraumes 23: im Bereich zwischen 12 und 24 mm.

At the 7 enlarged view of the 3 In addition to the device according to the invention shown, some dimensions and dimension ranges of structural features of the device according to the invention are given which are to be regarded only as preferred examples. For the following structural features of the device according to the invention, the following dimensions and dimension ranges are chosen, for example:

• Diameter of the first flow channel 5:2.4 mm;
• Diameter of the second flow channel 16 at the outlet 18: 2.0 mm;
• Maximum length of the cavity 23: in the range between 7 and 18 mm;
• Diameter of the cavity 23: in the range between 12 and 24 mm.

To change the diameter of the cavity 23, at least the outer housing part 23 is replaced with another outer housing part that results in a different diameter of the cavity 23. For example, outer housing parts 23 are available that allow a cavity diameter of 12, 16, 20 or 24 mm.

The 4 , 5 and 6 The devices 100b, 100c and 100d shown differ from the device shown in the 1 , 2 , 3 and 7 shown device 100a only by a changed geometry of the nozzle body 4 of the respective cavitation nozzle 3b, 3c, 3d. Therefore, the same reference numerals are used for those parts of the devices 100b, 100c and 100d that are the same or similar in the device 100a.

At the 4 In the device 100b shown, the wall section 25 of the nozzle body 4 delimiting the cavity 23 is flat and extends transversely to the flow direction. The outlet 7 of the first flow channel 5 opens into a truncated cone-shaped recess 30 which widens conically outwards.

At the 5 In the device 100c shown, the wall section 25 of the nozzle body 4 delimiting the cavity 23 is concave or bowl-shaped, with the inlet 6 of the first flow channel 5 located at the base of the bowl-shaped wall section 25. The outlet 7 of the first flow channel 5 is located in a flat wall section of the nozzle body 4 running transversely to the flow direction.

At the 6 In the device 100d shown, the wall section 25 of the nozzle body 4 delimiting the cavity 23 is convexly curved. The first flow channel 5 opens at its outlet 7 into a conical recess 30 which is deeper than the conical recess 30 in the device 100a and widens more than the conical recess 30 in the device 100a.

The described and illustrated different shapes of the nozzle body 4 of the devices 100a, 100b, 100c and 100d make it possible to optimally adapt the pulsation and/or the cavitation bubble formation in the liquid jet to the respective nature of the solid body to be processed, in particular the rock, in order to achieve the best possible result in the formation of cavities in the solid body.

8th shows a schematic representation of an underground borehole pattern that can be achieved with the device according to the invention by cavitation erosion and pulsation of a liquid jet, which includes a vertical main borehole 31, a lateral borehole 33 branching off from it at an intersection 32 and a microborehole 34 branching off from it.

A in 9 A schematic and perspective view of an underground drilling pattern that can be produced with the device according to the invention comprises a vertical main bore 31, radial and lateral bores 32 branching off from the main bore 31 at different heights, and microbores 33 extending from the radial and lateral bores 32.

Of course, the invention is not limited to the embodiments shown. The above description is therefore not to be regarded as restrictive, but as explanatory. The following claims are to be understood in such a way that a named feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. If the claims and the above description define "first" and "second" embodiments, this designation serves to distinguish between two similar embodiments without establishing a priority.

List of reference symbols

1

outer housing part

2

inner housing part

3a, 3b, 3c, 3d

Cavitation nozzle

4

Nozzle body

5

first flow channel

6

Entrance

7

Exit

8th

inner space

9

cylindrical section

10

cylindrical section

11a

Transition surface

11b

Transition surface

12

inner thread

13

External thread

14

cylindrical section

15

cylindrical section

16

second flow channel

17

Entrance

18

Exit

19

conical section

20

cylindrical section

21

cylindrical section

22

cylindrical section

23

cavity

24

second wall section

25

first wall section

26

cylindrical section

27

Wall section (contact surface)

28

Wall section (front face)

29

Screws

30

Recess

31

Main bore

32

Crossing

33

side hole

34

Microborehole

100a, 100b, 100c, 100d

contraption

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• US3528704 [0002]
• US5495903 [0003]
• US8424620 [0004]

Claims (14)

Device (100a, 100b, 100c, 100d) for generating a pulsating liquid jet containing cavitation bubbles for the cavity-forming removal of material from solid bodies, in particular rocks, with a cavitation nozzle (3a, 3b, 3c, 3d) which has a nozzle body (4) through which a first flow channel (5) extends with an inlet (6) for the inlet of the pulsating liquid jet and an outlet (7) for the pulsating liquid jet containing cavitation bubbles, and with a device arranged upstream of the cavitation nozzle (3a, 3b, 3c, 3d) for generating a pulsating movement in the liquid jet, wherein the device has a housing detachably connected to the nozzle body (4), through which a second flow channel (16) with an inlet (17) connectable to a pressurized liquid source and an outlet (18) which opens into a cavity (23) which is connected to the inlet (6) of the first flow channel (5), characterized in that the housing comprises an outer housing part (1) with an interior space (8) and an inner housing part (2) which has the second flow channel (16) and which is arranged in the interior space (8) of the outer housing part (1) so as to be movable in and against the flow direction, and the cavity (23) is delimited at least by a first wall section (25) of the nozzle body (4) which has the inlet (6) of the first flow channel (5) and a second wall section (24) of the inner housing part (2) which is opposite the first wall section (25) and has the outlet (18) of the second flow channel (16), wherein a distance (D) between the first wall section (25) and the second wall section (24) can be changed by moving the inner housing part (2) relative to the outer housing part (1). Device according to Claim 1 , characterized in that the first wall section (25) is flat or has a convex or concave shape, which is rounded, conical or frustoconical in each case, wherein the inlet (6) of the first flow channel (5) is arranged centrally in the first wall section (25) and the first flow channel (5) and the second flow channel (16) are axially aligned. Device according to Claim 1 or 2 , characterized in that the cavity (23) is delimited by a third wall section (26) which is located on an inner side of the outer housing part (1) facing the interior space (8). Device according to one of the preceding claims, characterized in that the first wall section (25) is surrounded by a contact surface (27) which is opposite an end face (28) of the outer housing part (1), and the contact surface (27) and the end face (28) are pulled against one another by screw connection means (29) which detachably connect the nozzle body (4) to the outer housing part (1). Device according to one of the preceding claims, characterized in that the second flow channel (16) has a smaller cross-sectional area at its outlet (18) than at its inlet (17). Device according to Claim 5 , characterized in that the first flow channel (5) has a cross-sectional area at its outlet (7) which is larger than the cross-sectional area at the outlet (18) of the second flow channel (16). Device according to one of the preceding claims, characterized in that the first flow channel (5) has a constantly large cross-sectional area between its inlet (6) and its outlet (7). Device according to one of the preceding claims, characterized in that the first flow channel (5) is cylindrical between its inlet (6) and its outlet (7). Device according to one of the preceding claims, characterized in that the second flow channel (16) has at least one section (19) tapering conically in the flow direction. Device according to one of the preceding claims, characterized in that the second flow channel (16) has several cylindrical sections (20, 21, 22) whose diameters decrease in the flow direction. Device according to one of the preceding claims, characterized in that the first flow channel (5) opens at its outlet (7) into a conical or frustoconical recess (30) in an outer wall section of the nozzle body, the recess tapering in cross section towards the outlet of the first flow channel (5). Device according to one of the Claims 1 until 10 , characterized in that the outlet (7) of the first flow channel (5) is located in a flat outer wall section of the nozzle body (4). Device according to one of the preceding claims, characterized in that the Cavity (23) is cylindrical and has a diameter selected from a group of different diameters. Method for generating a pulsating liquid jet containing cavitation bubbles for the cavity-forming removal of material from solid bodies, in particular rocks, characterized in that the pulsating movement of the liquid jet is carried out using a device according to one of the Claims 1 until 13 itself is induced and the pressure and the speed of the liquid jet flowing through the nozzle body (4) are selected such that cavitation bubbles are formed in the pulsating liquid jet emerging from the nozzle body (4), which contribute to the removal of material of the solid body by cavitation erosion, forming cavities, when the liquid jet strikes a solid body.

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