Acid fracturing fluid mixing device and mixing method

Abstract

The acid fracturing fluid mixing device comprises a tank body, a tank cover matched with the tank body for use is arranged on the tank body, a stirring shaft is arranged in the tank cover, a net plate is rotationally connected to the inner wall of the tank body in the height direction of the tank body, and the net plate comprises a first separation net and a second separation net which are used for cutting colloidal cakes. Telescopic cutting pieces are arranged on the first partition net and the second partition net, a plurality of stirring frames for stirring in the height direction of the tank body are arranged on the tank cover and are arranged in a central symmetry mode relative to the stirring shaft, and a transverse frame is arranged at the end, close to the bottom of the tank body, of the stirring shaft; the problems that in the prior art, colloidal cakes appear after a thickening agent is added, and small cakes cannot be treated in time due to the fact that the stirring direction of a mixing device is single are solved, and the device has good application prospects in the field of oil exploitation.

Description

Technical Field

[0001] This invention relates to the field of petroleum equipment technology, specifically to an acid fracturing fluid mixing device and mixing method. Background Technology

[0002] The main components of acidizing fracturing fluid are hydrochloric acid, hydrofluoric acid, thickener, and corrosion inhibitor. During operation, these materials need to be mixed and stirred beforehand. After the thickener is added, due to its inherent properties, it often forms gel-like clumps. Most mixing devices on the market rotate in one direction, causing the gel-like clumps to rotate with the liquid flow. Because they are constantly in motion, the mixing device cannot effectively break them up, thus failing to achieve a good mixing effect.

[0003] Patent application number 201410009226.8 describes a "continuous mixing and supply method for acidizing fracturing fluid." This method includes: simultaneously feeding a thickener premixed solution, acid, and various liquid additives into an integrated mixing system for solution mixing to obtain a uniformly mixed acidizing fracturing fluid; and a dispensing step: supplying and discharging the acidizing fracturing fluid obtained in the mixing step. The mixing method of this invention enables the continuous mixing and supply of water, acid, dry powder or paste, and various liquid additives, resulting in good mixing effect, uniform mixing, and high-quality fracturing fluid.

[0004] The aforementioned patent provides a method for continuous mixing and delivery of acidizing fracturing fluid. However, this existing method cannot solve the problem of colloidal clumps not being broken up during movement, thus failing to promptly handle the colloidal clumps and affecting the mixing quality of the acidizing fracturing fluid. Summary of the Invention

[0005] The purpose of this invention is to provide an acid fracturing fluid mixing device and mixing method, which aims to improve the problem that existing methods cannot solve the problem that gel-like clumps cannot be broken up while moving, and thus cannot be processed in time, thereby affecting the mixing quality of acid fracturing fluid.

[0006] This invention is implemented as follows:

[0007] To achieve the above objectives, according to one aspect of the present invention, an acid fracturing fluid mixing device is provided, comprising a tank body, a tank cover for use therewith, a stirring shaft inside the tank cover, and a mesh plate rotatably connected to the inner wall of the tank body along its height direction. The mesh plate includes a first mesh and a second mesh for separating gelatinous clumps. Multiple first and second meshes are arranged sequentially and evenly along the inner wall of the tank body. The first and second meshes have an arc-shaped structure suitable for the inner wall of the tank body and are arranged end-to-end to form a structure covering the entire inner wall of the tank body. Each of the first and second meshes is provided with a retractable cutting blade, forming a structure where, after the first and second meshes rotate, the cutting blades move out to separate the gelatinous clumps attached to the surfaces of the first and second meshes. A stirring frame for stirring along the height direction of the tank body is provided on the tank cover. Multiple stirring frames are arranged centrally symmetrically about the stirring shaft. A crossbar is provided at one end of the stirring shaft near the bottom of the tank body, and a wheel is provided at one end of the crossbar near the bottom and inner wall of the tank body.

[0008] Preferably, the mesh plate is provided with a rotating shaft at one end near the inner wall of the tank, the inner wall of the tank is provided with support feet, there are multiple support feet arranged in pairs along the vertical direction, the support feet are provided with round holes for cooperating with the rotating shaft, the end of the rotating shaft away from the bottom of the tank is provided with a gear, one end of the tank is provided with a gear ring for cooperating with each gear, and the tank cover is provided with a drive gear and a motor for driving the gear ring and driving the gear to rotate.

[0009] Preferably, the tank body is provided with an annular groove for use with the gear ring, a roller is provided at the bottom of the annular groove, a detachable positioning post is provided on one side of the gear ring, a positioning groove is provided inside the tank body for use with the annular groove and the positioning post, and a partition is provided on the inner wall of the tank body near the gear.

[0010] Preferably, the stirring rack includes vertical plates fixed on the tank lid. There are multiple vertical plates arranged in pairs opposite each other. Rollers are rotatably connected to both ends of the vertical plates. A ring-shaped connecting belt is sleeved on the outside of the two rollers. Hanging plates are provided on the connecting belt. There are multiple hanging plates arranged at even intervals. A motor for driving the rollers to rotate is provided at one end of the vertical plate, forming a structure in which the connecting belt and hanging plates rotate and stir in the vertical direction.

[0011] Preferably, the first mesh includes a frame fixed to the rotating shaft, and a fixing strip fixed in the horizontal direction is provided in the frame. There are multiple fixing strips that are parallel to each other and evenly spaced along the height direction of the tank. A dividing strip is provided on one side of the fixing strip. The dividing strip has a triangular cross-section, and the cutting blade is located inside the fixing strip.

[0012] Preferably, the second mesh includes a frame fixed to the rotating shaft, and a fixing strip fixed in the vertical direction is provided in the frame. There are multiple fixing strips that are parallel to each other and evenly spaced along the width direction of the tank. A dividing strip is provided on one side of the fixing strip. The dividing strip has a triangular cross-section, and the cutting blade is located inside the fixing strip.

[0013] Preferably, the fixing strip has an elongated hole on one side near the dividing strip, a sealing ring is provided in the elongated hole, the fixing strip has a hollow structure inside, and a spring is provided at the center line of the fixing strip along its length. There are two springs, and a retainer is provided at one end away from the inner wall of the fixing strip. A cutting piece is fixed at the end of the two retainers away from the spring, forming a structure in which the cutting piece is moved out of the fixing strip by the sealing ring and then reset under the action of the spring.

[0014] Preferably, the fixing bar is provided with impellers at both ends, the impellers are connected to a rotating shaft by a flat key, and a pulley mechanism is provided at the end of the rotating shaft away from the impellers. The belt of the pulley mechanism is provided with a connecting plate that cooperates with the card seat, forming a mechanism in which the impeller drives the pulley mechanism and the cutting blade to move under the influence of the liquid inside the tank.

[0015] Preferably, the cross frame includes a central frame fixed to the stirring shaft, and the central frame has multiple crossbars along its edge, with multiple discs rotatably connected to each crossbar for separating gelatinous clumps.

[0016] According to a second aspect of the present invention, a method for mixing acid fracturing fluid is provided, wherein the acid fracturing fluid is mixed using the mixing apparatus described in any one of the claims.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. A rotatable mesh plate is installed on the inner wall of the tank. The rotation of the first mesh and the second mesh separates the gelatinous clumps that are close to the inner wall of the tank. The first mesh and the second mesh are arranged sequentially and their internal fixing strips are perpendicular to each other to more effectively separate the gelatinous clumps. The crossbar at the end of the stirring shaft and the wheel on the crossbar facilitate the cleaning of the clumps at the bottom of the tank and achieve a better mixing effect.

[0019] 2. The mixing rack on the tank lid supports the connecting belt and rollers through a vertical plate extending into the tank body. Together with the motor connected to the rollers and the hanging plate on the connecting belt, it enables the mixing of the upper and lower layers of fracturing fluid. It also facilitates the vertical dispersion of colloidal clumps, preventing excessive accumulation at the bottom that is difficult to handle.

[0020] 3. The support feet on the inner wall of the tank, in conjunction with the rotating shaft, provide support for the rotation of the screen plate. The gear at the end of the rotating shaft facilitates the rotation of the screen plate under the drive of the gear ring. The ring groove on the tank and the roller at the bottom of the ring groove, together with the positioning groove and the positioning post that can be disassembled and reassembled on the gear ring, facilitate the rotation of the gear ring along the ring groove and drive each screen plate to rotate.

[0021] 4. The cutting blades inside the first and second partitions facilitate the cleaning of gelatinous clumps adhering to the surfaces of the first and second partitions. The mounting bracket and spring facilitate the reset of the cutting blades by the springs after they are removed from the fixing strip. The impellers at both ends of the fixing strips are driven to rotate by the rotating fracturing fluid, and the movement of the cutting blades is achieved through the transmission of the connecting plate that works with the mounting bracket on the pulley mechanism. Attached Figure Description

[0022] Figure 1 This is a structural diagram of the acid fracturing fluid mixing device of the present invention;

[0023] Figure 2 This is a top view of the tank body of the acid fracturing fluid mixing device of the present invention;

[0024] Figure 3 This is an enlarged view of point A in the top view of the tank body of the acid fracturing fluid mixing device of the present invention;

[0025] Figure 4 This is a front view of the first partition screen of the acidizing fracturing fluid mixing device of the present invention;

[0026] Figure 5 This is an enlarged view of section B in the main view of the first mesh of the acidizing fracturing fluid mixing device of the present invention;

[0027] Figure 6 This is a cross-sectional view of the fixing bar of the acid fracturing fluid mixing device of the present invention;

[0028] Figure 7 This is a front view of the second mesh of the acid fracturing fluid mixing device of the present invention;

[0029] Figure 8 This is a top view of the tank body when the acid fracturing fluid mixing device of the present invention is in use.

[0030] The components are as follows: 1. Tank body; 2. Tank cover; 3. Stirring shaft; 4. Mesh plate; 5. First partition mesh; 6. Second partition mesh; 7. Splitter; 8. Stirring frame; 9. Horizontal frame; 10. Wheel; 11. Rotating shaft; 12. Support foot; 13. Gear; 14. Gear ring; 15. Annular groove; 16. Roller; 17. Positioning column; 18. Positioning groove; 19. Partition plate; 20. Vertical plate; 21. Roller; 22. Connecting belt; 23. Hanging plate; 24. Frame; 25. Fixing strip; 26. Dividing strip; 27. Long hole; 28. Sealing ring; 29. ​​Spring; 30. Card seat; 31. Impeller; 32. Rotating shaft; 33. Pulley mechanism; 34. Connecting plate; 35. Central frame; 36. Horizontal bar. Detailed Implementation

[0031] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details:

[0033] Example

[0034] like Figure 1 , Figure 4 and Figure 8The diagram shows an acid fracturing fluid mixing device, comprising a tank 1, a tank cover 2 for use with the tank 1, and a stirring shaft 3 inside the tank cover 2. A mesh plate 4 is rotatably connected to the inner wall of the tank 1 along its height direction. A rotating shaft 11 is snapped onto one end of the mesh plate 4 near the inner wall of the tank 1. Support legs 12 are screwed to the inner wall of the tank 1. Multiple support legs 12 have a rectangular block structure and are arranged in pairs along the vertical direction. The support legs 12 have circular holes for use with the rotating shaft 11, and bearings with interference fits to the rotating shaft 11 are installed in the circular holes. The mesh plate 4 includes a first mesh 5 and a second mesh 6 for separating gelatinous agglomerates. Multiple first meshes 5 and second meshes 6 are arranged evenly and sequentially along the inner wall of the tank 1. The first meshes 5 and second meshes 6 have an arc-shaped structure suitable for the inner wall of the tank 1 and are arranged end-to-end to form a structure covering the entire inner wall of the tank 1. The first partition 5 includes a frame 24 fixed to the rotating shaft 11. The frame 24 has a rectangular ring structure. Multiple fixing strips 25 are screwed into the frame 24 and are evenly spaced and parallel to the height of the tank 1. A dividing strip 26 with a triangular cross-section is screwed onto one side of each fixing strip 25. The second partition 6 also includes a frame 24 fixed to the rotating shaft 11. Multiple fixing strips 25 are vertically fixed within the frame 24 and are evenly spaced and parallel to the width of the tank 1. A dividing strip 26 is provided on one side of each fixing strip 25. Both the first and second partitions 5 and 6 are equipped with retractable cutting discs 7 located inside the fixing strips 25. This creates a structure where, after the first and second partitions 5 and 6 rotate, the cutting discs 7 move out and divide the gelatinous clumps adhering to their surfaces. The tank cover 2 is equipped with a stirring frame 8 for stirring fracturing fluid along the height direction of the tank body 1. There are multiple stirring frames 8, which are arranged symmetrically about the stirring shaft 3. A cross frame 9 is provided at one end of the stirring shaft 3 near the bottom of the tank body 1. The cross frame 9 includes a central frame 35 fixed to the stirring shaft 3. The central frame 35 has a hollow regular hexagonal structure. Multiple crossbars 36 are bolted to the edge of the central frame 35. The crossbars 36 are evenly spaced. Multiple discs 10 for cutting gelatinous agglomerates are rotatably connected to each crossbar 36. The discs 10 are existing technology and cut the gelatinous agglomerates by their own tilt angle.

[0035] like Figure 1 , Figure 2 and Figure 3As shown: A gear 13 is keyed to the end of the rotating shaft 11 away from the bottom of the tank body 1. An annular groove 15 is provided at one end of the tank body 1. A gear ring 14, which rotatably connects to the annular groove 15 and cooperates with each gear 13, is rotatably connected within the annular groove 15. A circular groove recessed into itself and used for the rotation of the gear ring 14 is provided on the side of the tank cover 2 near the tank body 1. A motor is fixed to the inner wall of the tank cover 2 by mounting bolts. A drive gear 13, which drives the gear ring 14 and drives the gear 13 to rotate, is keyed to the output shaft of the motor. A roller 16 is provided at the bottom of the annular groove 15. The roller 16 includes a vertical rod fixed to the bottom of the annular groove 15. A rotating roller is rotatably connected to the end of the vertical rod away from the bottom of the annular groove 15. A detachable positioning post 17 is snapped onto one side of the gear ring 14. The positioning post 17 has a round rod structure. A positioning groove 18, which communicates with the annular groove 15 and cooperates with the positioning post 17, is provided inside the tank body 1. A partition plate 19, which has an annular structure, is bolted to the end of the inner wall of the tank body 1 near the gear 13.

[0036] like Figure 1 , Figure 2 and Figure 3 As shown: The stirring rack 8 includes vertical plates 20 bolted to the tank cover 2. There are multiple vertical plates 20 arranged in pairs opposite each other. Rollers 21 are rotatably connected to both ends of the vertical plates 20. A ring-shaped connecting belt 22 is sleeved on the outside of the two rollers 21. Hanging plates 23 are fixed to the connecting belt 22 by screws. There are multiple hanging plates 23 arranged at even intervals. A motor for driving the rollers 21 to rotate is fixed to one end of the vertical plate 20 by mounting seat bolts, forming a structure in which the connecting belt 22 and the hanging plates 23 rotate and stir in the vertical direction.

[0037] In such Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown: A long hole 27 penetrating the thickness direction of the fixing strip 25 is provided at the center line position of the side of the fixing strip 25 near the dividing strip 26. A sealing ring 28 is glued inside the long hole 27. A long slit for the cutting blade 7 to enter and exit is provided on the center line of the sealing ring 28. The fixing strip 25 has a hollow internal structure. A groove recessed into itself is provided at the center line position of the fixing strip 25 along its length direction. A spring 29 is engaged in the groove. There are two springs 29. The ends of the springs 29 away from the inner wall of the fixing strip 25 are engaged with the retaining bases 30. The ends of the two retaining bases 30 away from the springs 29 are fixed with the cutting blade 7, forming a structure in which the cutting blade 7 is moved out of the fixing strip 25 through the sealing ring 28 and reset under the action of the springs 29. Impellers 31 are provided at both ends of the fixing strip 25. The impellers 31 are existing technology. The impellers 31 are connected to the rotating shaft 32 by a flat key. A support plate for supporting the rotating shaft 32 is fixed inside the fixing strip 25 by screws. A pulley mechanism 33 is fixed to the end of the rotating shaft 32 away from the impellers 31 by the support plate. A connecting plate 34 for cooperating with the card seat 30 is fixed to the belt of the pulley mechanism 33 by screws. This forms a mechanism in which the impellers 31 drive the pulley mechanism 33 and the cutting blade 7 to move under the influence of the liquid inside the tank 1.

[0038] Working principle: By setting a rotatable mesh plate 4 on the inner wall of the tank 1, the first mesh 5 and the second mesh 6 are rotated to separate the gelatinous clumps rotating near the inner wall of the tank 1. The first mesh 5 and the second mesh 6 are arranged in sequence with their internal fixing strips 25 perpendicular to each other to more effectively separate the gelatinous clumps. The cross frame 9 at the end of the stirring shaft 3 and the wheel 10 on the cross frame 9 are set to facilitate the cleaning of the clumps at the bottom of the tank 1 and achieve a better mixing effect.

[0039] The stirring rack 8 on the tank lid 2 supports the connecting belt 22 and roller 21 via the vertical plate 20 extending into the tank body 1. This, along with the motor connected to the roller 21 and the hanging plate 23 on the connecting belt 22, facilitates the mixing of the upper and lower layers of fracturing fluid. It also helps disperse gel-like clumps vertically, preventing excessive accumulation at the bottom. The support feet 12 on the inner wall of the tank body 1, in conjunction with the rotating shaft 11, provide support for the rotation of the mesh plate 4. The gear 13 at the end of the rotating shaft 11 facilitates the rotation of the mesh plate 4 under the drive of the gear ring 14. The annular groove 15 on the tank body 1 and the roller 16 at the bottom of the annular groove 15... The positioning post 17, which is designed to be disassembled and repositioned in conjunction with the positioning groove 18 and the toothed ring 14, facilitates the rotation of the toothed ring 14 along the annular groove 15 and drives the rotation of each mesh plate 4. The cutting blade 7 inside the first partition 5 and the second partition 6 facilitates the cleaning of the gelatinous clumps attached to the surfaces of the first partition 5 and the second partition 6. The mounting base 30 and the spring 29 facilitate the reset of the cutting blade 7 by the spring 29 after it is removed from the fixing strip 25. The impellers 31 at both ends of the fixing strip 25 are driven to rotate by the rotating fracturing fluid and are driven by the connecting plate 34 on the pulley mechanism 33 that works with the mounting base 30, thereby realizing the movement of the cutting blade 7.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An acid fracturing fluid mixing device, comprising a tank (1), wherein a tank cover (2) is provided on the tank (1) for use therewith, and a stirring shaft (3) is provided inside the tank cover (2), characterized in that, The inner wall of the tank (1) is rotatably connected to a mesh plate (4) along its height direction. The mesh plate (4) includes a first mesh (5) and a second mesh (6) for dividing gelatinous lumps. There are multiple first meshes (5) and second meshes (6) arranged evenly and sequentially along the inner wall of the tank (1). The first meshes (5) and second meshes (6) have an arc-shaped structure suitable for the inner wall of the tank (1) and are arranged end to end to form a structure that covers the inner wall of the tank (1). Both the first meshes (5) and second meshes (6) are provided with retractable cutting blades. 7) After the first partition (5) and the second partition (6) are rotated, the cutting blade (7) moves out to divide the gelatinous clumps attached to the surface of the first partition (5) and the second partition (6). The can lid (2) is provided with a stirring rack (8) for stirring along the height direction of the can body (1). There are multiple stirring racks (8) and they are arranged symmetrically about the stirring shaft (3). A crossbar (9) is provided at one end of the stirring shaft (3) near the bottom of the can body (1). A wheel (10) is provided at one end of the crossbar (9) near the bottom and inner wall of the can body (1).

2. The acid fracturing fluid mixing device according to claim 1, characterized in that, The mesh plate (4) is provided with a rotating shaft (11) at one end near the inner wall of the tank (1). The inner wall of the tank (1) is provided with support feet (12). There are multiple support feet (12) arranged in pairs along the vertical direction. The support feet (12) are provided with round holes that cooperate with the rotating shaft (11). The end of the rotating shaft (11) away from the bottom of the tank (1) is provided with a gear (13). One end of the tank (1) is provided with a gear ring (14) that cooperates with each gear (13). The tank cover (2) is provided with a drive gear (13) and a motor for driving the gear ring (14) and driving the gear (13) to rotate.

3. The acid fracturing fluid mixing device according to claim 2, characterized in that, The tank body (1) is provided with an annular groove (15) that cooperates with the gear ring (14). A roller (16) is provided at the bottom of the annular groove (15). A detachable positioning post (17) is provided on one side of the gear ring (14). A positioning groove (18) that communicates with the annular groove (15) and cooperates with the positioning post (17) is provided inside the tank body (1). A partition plate (19) is provided on the inner wall of the tank body (1) at the end near the gear (13).

4. The acid fracturing fluid mixing device according to claim 1, characterized in that, The stirring rack (8) includes vertical plates (20) fixed on the tank lid (2). There are multiple vertical plates (20) arranged in pairs opposite each other. Rollers (21) are rotatably connected to both ends of the vertical plates (20). A connecting belt (22) with a ring structure is sleeved on the outside of the two rollers (21). A hanging plate (23) is provided on the connecting belt (22). There are multiple hanging plates (23) and they are evenly spaced. A motor for driving the rollers (21) to rotate is provided at one end of the vertical plate (20), forming a structure in which the connecting belt (22) and the hanging plate (23) rotate and stir in the vertical direction.

5. The acid fracturing fluid mixing device according to claim 1, characterized in that, The first partition (5) includes a frame (24) fixed to the rotating shaft (11). The frame (24) is provided with a fixing strip (25) fixed in the horizontal direction. There are multiple fixing strips (25) that are parallel to each other and evenly spaced along the height direction of the tank (1). A dividing strip (26) is provided on one side of the fixing strip (25). The dividing strip (26) has a triangular cross section. The cutting piece (7) is located inside the fixing strip (25).

6. The acid fracturing fluid mixing device according to claim 1, characterized in that, The second mesh (6) includes a frame (24) fixed to the rotating shaft (11). The frame (24) is provided with a fixing strip (25) fixed in the vertical direction. There are multiple fixing strips (25) that are parallel to the width direction of the tank (1) and are evenly spaced. A dividing strip (26) is provided on one side of the fixing strip (25). The dividing strip (26) has a triangular cross section. The cutting piece (7) is located inside the fixing strip (25).

7. An acidizing fracturing fluid mixing device according to claim 5 or 6, characterized in that, The fixing strip (25) has an elongated hole (27) on one side near the dividing strip (26). A sealing ring (28) is provided inside the elongated hole (27). The fixing strip (25) has a hollow structure inside. A spring (29) is provided at the center line of the fixing strip (25) along its length. There are two springs (29), and a retainer (30) is provided at one end away from the inner wall of the fixing strip (25). A cutting piece (7) is fixed at the end of the two retainers (30) away from the spring (29), forming a structure in which the cutting piece (7) moves out of the fixing strip (25) through the sealing ring (28) and then resets under the action of the spring (29).

8. The acid fracturing fluid mixing device according to claim 7, characterized in that, The fixed strip (25) is provided with impellers (31) at both ends. The impellers (31) are connected to a rotating shaft (32) by a flat key. The end of the rotating shaft (32) away from the impellers (31) is provided with a pulley mechanism (33). The belt of the pulley mechanism (33) is provided with a connecting plate (34) that works with the card seat (30), forming a mechanism in which the impellers (31) drive the pulley mechanism (33) and the cutting blade (7) to move under the influence of the liquid inside the tank (1).

9. The acid fracturing fluid mixing device according to claim 7, characterized in that, The cross frame (9) includes a central frame (35) fixed to the stirring shaft (3). The central frame (35) has multiple crossbars (36) along its edge. Each crossbar (36) is rotatably connected to multiple discs (10) for dividing the gelatinous clumps.

10. A method for mixing acidizing fracturing fluid, characterized in that, The acidizing fracturing fluid is mixed using any of the mixing devices described in claims 1-9.

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