MXPA06007338A - Device and methodology for improved mixing of liquids and solids - Google Patents

Abstract

An eductor for mixing liquids and solid particles includes a nozzle, an initial mixing chamber, a first diffuser, an intermediate mixing chamber and a second diffuser. The nozzle includes a semicircular nozzle outlet that is offset from a centrally-located frst axis. Motive flow is accelerated through the nozzle through a first and second acceleration segment. Solid particles are added to the motive flow in the initial mixing chamber and directed to the first diffuser. Each diffuser includes an acceleration and a deceleration segment separated by an elliptically-shaped throat. The intermediate mixing chamber is located between the first and second diffusers. A method for mixing liquids and solids includes introducing a motive flow finto an initial mixing chamber, creating a vacuum in the initial mixing chamber to induce solids irto the motive fluid, providing a region of turbulence to enhance mixing of the motive flow and solid particles, and diffusing the motive flow to further increase boundary flow separation conducive to mixing.

Description

DEVICE AND METHODOLOGY FOR IMPROVED MIXING OF LIQUIDS AND SOLIDS BACKGROUND OF THE INVENTION The efficient mixing of fluids and solids is essential for many sectors of the industry. The means by which this mixing is carried out are many, the choice of medium depends on the nature of the materials being mixed and the degree and speed of mixing required. Many concepts have been developed and frequent efforts have been made to improve the efficiency and effectiveness of liquid and solid mixing systems. Some notable methods that have met with relative success, depending on the nature of the materials being mixed, include: geometric nozzle distortion, pulsation of motive fluid, and the introduction of a diffuser as part of the system. The nozzle distortion attempts to create turbulent flow by altering the geometry of the motor flow interaction with the surface of the nozzle, as shown in Figures la and Ib. The result of this alteration is to change the speed of the motor fluid as it leaves the outlet of the nozzle, creating vortices where liquid-liquid or liquid-solid mixing can occur. Referring to Figure 2a, typical geometries generate a narrow circular or nearly circular jet 300 that minimizes entrainment of solids, thus minimizing the effectiveness of mixing liquid-liquid or liquid-solid vortices. As shown in FIGS. 2a-d, the nozzle distortions 300 will deteriorate rapidly and will eventually return to a circular or near-circular shape. Further, when the solids 310 are introduced from the top by gravity into a larger cavity containing liquid jet stream 300, only a small portion of the solids contacts the liquid. Referring to Figure 3, a fluid velocity profile for a prior art nozzle is shown. The liquid jet stream 300 emanating from the initial mixing chamber reaches a higher range of 16.33 to 20.42 meters / second, which is shown as reference 320. As can be seen, this high speed passes through the solids that are introduced from above. Slower fluid velocities in the range of 12.25 to 16.33 meters / second are shown as reference 322 and are presented in front of the upper speed stream 320 and in a boundary layer around the stream 320. The fluid velocity becomes more slow even further downstream to a range of 8.16 to 12.25 meters / second, as shown by reference 324. At the time of entry to restricted area 312, and divergence area 314, the speed becomes slower, in the range of 4.08 to 8.16 meters / second, as shown by reference 326. It is in this entry to restricted area 312 that the velocity profile shows a single mixing zone 330. The slowest speed, 0.00 to 4.08 meters / second, which is shown with reference 328, is present along the edges of divergent area 314 as well as in the initial mixing chamber where solids 310 are added at a normal angle to, or almost normal to, the direction of the fluid through the nozzle. In the pulsation of motive flow, the oscillation of the speed of the motor flow, with or without a nozzle, changes the speed that creates turbulent flow, but it will not allow the maintenance of a vacuum conducive to a fast and consistent induction of the secondary solid. In addition, such efforts require additional control systems and external energy reducing the efficiency of the procedure. A third methodology that has observed more positive results is that of the motor flow that uses the combination of nozzle and diffuser. This combination is referred to as an eductor. The relative speed of the motor flow passing through the hole in the outlet of the nozzle keeps, effectively, the vacuum that is required to allow the induction of secondary solids, but does not create sufficient recirculation zones in size and intensity to allow optimal mixing. The action of the motor flow through the nozzle into the hollow space at the outlet of the nozzle carries the secondary solid into the interior of the eductor but is unsuccessful in mixing the two at an optimum level. All nozzle geometries create vortices at the micro level of downstream of the nozzle. It has been suggested that some nozzle geometries, such as lobed nozzles, can create these vortices faster (ie, at smaller tube diameter lengths) for liquid-in-liquid applications. However, the intensity of the vortices does not change and the applications of solids induced in liquid are unknown. In addition, the speed at which micro vortices are created in the eductor, based on liquid-solid mixing applications, is not critical since several tube diameters are available before discharge. The creation of a vacuum to induce solids into the interior of motive fluid and vortices of large eddy currents is necessary to drag and mix the solids with the driving fluid. Therefore, without the addition of a downstream diffuser, which is used to create vacuum and to create large short and intense vortices, mixing is limited and solids are simply carried along the plane of the motor flow, only for inefficiently mixing several diameters of downstream pipe at a very slow speed. An effective method to control the location of the large swirls and recirculation mixing zones created between the outlet of the nozzle and the diffuser inlet is through the geometry and position of the nozzle and diffuser. Through the combination of these geometries and positions, several large eddies are generated which maximize the induction of solids and the solid-liquid relationship while limiting the pressure drop. Typically, nozzles with or without distorted geometries are placed in the center of the motive flow and produce only limited contact with the solids and the driving fluid. Therefore, the turbulence and the consequent mixing along the linear axis of the motor flow are limited. In addition, protruding nozzles can be an impediment to the induction of solids. Said impediment will reduce the speed of induction and will have a negative impact on the mixing performance.

This problem has been addressed with the introduction of a multi-lobed circular nozzle in conjunction with a slightly tapered single-neck diffuser. Although effective, this concept can be improved in such a way that the speed at which the secondary solids can be introduced into the motor flow can be increased, improving the contact of the solid-liquid surface through a flat current profile. jet, to improve the generation of three large swirl currents through the use of diffuser geometry, maintain turbulent flow in the mixing body through the nozzle and diffuser geometry, increase and maintain the vacuum that facilitates rapid induction of solids, reduce the loss of pressure through the eductor system by means of the nozzle geometry and improve the overall mixing performance as measured by the hydration rate of the secondary solids.

SUMMARY OF THE INVENTION In one aspect, the subject matter claimed generally focuses on an improved in-line liquid / solid nozzle. The present invention provides an improved fluid mixing nozzle that achieves one or more of the following: accelerates the drive fluid; provides improved mixing of fluids and secondary solids; uses a unique semicircular nozzle geometry; improves the vacuum in the gap between the outlet of the nozzle and the entrance of the diffuser; improves the induction rate of the secondary solid; allows the use of a shorter diffuser section; uses a diffuser section with non-uniform diffuser inlet angles; uses a diffuser with a primary mixing zone plus two additional mixing zones in the diffuser; improves pre-wetting of solids in the primary mixing zone; creates a turbulent flow zone; induces macro and micro vortices in the motor flow; improves the hydration speed of solids; increases the speeds of the motor flow through the nozzle; allows consistent performance with inconsistent or low line pressure; reduces the pressure drop through the eductor, in addition to other benefits that those skilled in the art should appreciate. The eductor includes a nozzle, an initial mixing area, and a segmented diffuser. The nozzle is a semicircular orifice that is off center from a central axis. The outlet of the nozzle feeds the motor flow into the initial mixing area. The solid material is also directed into the interior of the initial mixing area. The initial mixing area is of sufficient size to create a temporary vacuum within the area, improving mixing in this first mixing zone. From the initial mixing area, the combined motive flow and the entrained solid are fed into the segmented diffuser. The diffuser has two segments, the first of which contains an inclined entrance that converges to a neck and an inclined exit that diverges to an intermediate cavity. The neck of the diffuser is elliptical, consistent with the shape of the jet stream. The entrance of the second segment is also inclined, converging to a neck while the outlet is inclined, diverging at the outlet of the eductor. The intermediate cavity serves as a second mixing zone, while the outlet of the second diffuser serves as a third mixing area. Another illustrated aspect of the subject matter claimed is a method for mixing liquids / solids. A liquid fluid that acts as a motor flow passes through a nozzle into a hole. The motor flow through the nozzle and into the hollow creates a temporary vacuum, which allows the improved induction of a separate solid entrained within the motor flow external to the nozzle. The flat profile of the jet stream allows for improved entrainment of solids. The nozzle produces a large turbulent region that has a turbulent intensity at a minimum pressure loss. This region of turbulence leads to the mixing of the motor flow and the induced solid. The motor flow carries the induced solid into the interior of the diffuser section. In each of the diffuser cavities, recirculation mixing zones and large eddy currents are created as the velocity increases and limit flow separation occurs. In these recirculating mixing zones and converging diffuser sections, there are areas of turbulent flow leading to mixing. The mixed fluid is discharged from the diffuser unit. Other aspects and advantages of the claimed subject matter will be apparent from the following description and appended claims.

BRIEF DESCRIPTION OF THE FIGURES Figures la and Ib are views of a mouthpiece of the prior art. Figures 2a to 2d are contours of volume fractions of solids through a nozzle of the prior art. Figure 3 is a computer generated velocity profile of fluid through a prior art nozzle and the addition of a downstream solid.

Figure 4 is a rear view of the inventive nozzle. Figure 5 is a sectional side view of the inventive nozzle. Figure 6 is a front view of the inventive nozzle. Figure 7 is a sectional side view of a mixing apparatus including the nozzle. Figures 8a to 8d are contours of volume fractions of solid particles through the eductor. Figure 9 is a side view of the contour of volume fractions of solid particles through the eductor. Figure 10 is a computer-generated velocity profile of fluid through the inventive eductor with solid particles added downstream from the nozzle. Figure 11 is a side view of a prior art nozzle. Figure 12 is a front view of a prior art nozzle.

DETAILED DESCRIPTION OF THE INVENTION The claimed subject matter refers to an eductor 100 and a method for mixing liquids with solids. Referring to Figure 7, the eductor 100 includes a nozzle 110, an initial mixing chamber 150, a funnel 154, a first diffuser 160, an intermediate mixing chamber 168, and a second diffuser 170. Returning to Figures 4-6 , three views of a nozzle embodiment 110 are shown. A motor flow is introduced into an initial mixing chamber 150 through the nozzle 110. A nozzle inlet 112 is circular about a first axis 102 and has an inlet diameter. of nozzle 114. In an inlet segment 116 of the nozzle 110, the inner surface 118 has an inner diameter 120, which is equal to the nozzle inlet diameter 114. The nozzle 110 has a nozzle outlet 134, wherein a upper outlet edge 136 is flat and a lower exit edge 138 is semicircular. The upper and lower exit edges 136 and 138 share common side points 142 and 144 and the lower exit edge 138 extends the nozzle exit height 146 from the upper exit edge 136 to the lowest point. The upper exit edge 136 is deviated from the first axis 102 by a deviation distance 140. Between the nozzle entry 112 and the nozzle outlet 134, a first acceleration segment 122 is defined by a cross-sectional area that is gradually reduced , wherein an upper portion 124 of the interior surface 118 is gradually flattened and tilted toward a plane which is a deviation distance 140 below the first axis 102, aligned with the upper exit edge 136. In a second acceleration segment 128 of the nozzle 110, the radial length 130 is also reduced between a lower portion 132 of the inner surface 118 and the first axis 102 to conform to the shape of the lower exit edge 138. A standard round nozzle can be incorporated. 200 in the eductor 100 instead of the nozzle 134. As shown in FIGS. 11 and 12, the round nozzle 200 has an outlet 210 that is circular about a nozzle axis 212. When inert solids, such as bentonite, are mixed with a fluid, the semicircular nozzle 134. can be used. As will be discussed, when partially hydrophilic and more active solids, such as polymers, are added to a fluid, the round nozzle 200 is preferred. Returning to FIG. Initial mixing chamber 150 receives both the motor flow and the solid particles. The motor flow is received from the outlet of the nozzle 134 or 210 through a first chamber inlet 152, while the solid particles are received from the funnel 154 through a second chamber inlet 156. A first mixing zone 220, which is shown in Figures 9 and 10, is created within the initial mixing chamber 150. When the semicircular nozzle 134 is used to direct the fluid into the initial mixing chamber 150, the first mixing zone 220 is more turbulent than when the round nozzle 210 is used to direct the fluid into the initial mixing chamber 150. The first mixing zone 220 often extends to the second chamber inlet 156 when the semicircular nozzle 134 is used, because at the fluid velocity created by the nozzle 134. For this reason, when adding active and partially hydrophilic solids to the motor flow, it is preferred that the round nozzle 210 minimize the inlet of fluid to, and the accumulation of solid particles within. of the second chamber inlet 156. When more inert solid particles are added to the motor flow, a semicircular nozzle 134. can be used. A chamber outlet 15 8 directs the initial mixture of the motor flow and the solid particles into the diffuser segments of the eductor 100. The chamber outlet 158 is aligned with the nozzle inlet 134, thus minimizing the energy lost by the motor flow as solid particles are received in the interior of the initial mixing chamber 150 at an angle substantially normal to the flow of the motor flow. The chamber outlet 158 feeds the initial mixture into a first diffuser 160. The first diffuser 160 includes a first convergent section 162 and a first divergent section 166, between which is a first neck 164. The first neck 164 has a shape in elliptical cross section (not shown), consistent with the shape of the jet stream. The convergent and divergent sections 162, 166 of the first diffuser 160 serve to induce turbulence in the flow, improving the mixing of the motor flow and the solid particles. The first diverging section 166 feeds the initial mixture into the intermediate mixing chamber 168, which is aligned with the first diffuser 160. Within the intermediate mixing chamber 168, a second mixing zone 222, which is shown in FIGS. Figures 9 and 10, is created through eddies that are formed therein before the driving fluid and the solid particles are further directed downstream. From the intermediate mixing chamber 168, the intermediate mixture is fed into a second diffuser 170. The second diffuser 170 is similar to the first diffuser 160, having a second converging section 172, a second neck 174, and a second diverging section 176. The additional mixing is enhanced by the turbulence created by the second diffuser 170. Downstream from the second diffuser 170, a third mixing zone 224 is formed, as shown in Figures 9 and 10, causing further mixing of the fluid and the solids. Referring to the cross-sectional views of the flow through the eductor 100 shown in Figs. 8a-8d, the degree of mixing at points of the eductor 100 can be seen. Fig. 8a shows the contour of the motor flow fluid 180 that enters through the nozzle outlet 134 (shown in figure 5). Said fluid is virtually free of solids and is denoted as reference 180 in this description. The addition of solids from the funnel 154 to the motive flow is shown in Figure 8b, where the reference number 188 denotes a cross-sectional area that is primarily solids. Those skilled in the art will appreciate that there may be traces of solids in the fluid 180 through the eductor 100, while at the same time there may be traces of fluids in the areas that are primarily solid 188. For this description, additional increments of the mixing between solid free fluid 180 and solids 188. Reference 184 refers to a mixture, wherein the solids are effectively entrained in the fluid. Boundary layers of inefficiently mixed fluid 182 and inefficiently mixed solids 186 are also shown. In Figure 8b it can be seen that an effective mixing area 184 has begun to form centrally between the solids-free fluid 180 and the particles. solid 188. A limit layer of inefficiently mixed solids 186 is located around the effective mixing area 184, while an inefficiently mixed fluid boundary layer is located below the solids-free fluid 180. Referring to FIG. 8c, effective mixing areas 184 include the area toward the center of the cross-sectional area and above the stream. of fluid 180 emanating from nozzle 110. Mainly, streams of solid particles 188 are present along the edges of the cross-sectional area. Other boundary layers of effectively mixed fluid 184 are present at the top and bottom of the cross-sectional area and around the solid-free fluid stream 180. The boundary layers of inefficiently mixed solids 186 are present around the streams of solid particles 188. Referring to Figure 8d, the solids free fluid stream 180 has been elongated around a large part of the cross-sectional area. The stream of solid particles 188 is joined in a single stream that is slightly off-center. A limit layer of inefficiently mixed solids 186 surrounds the stream of solid particles 188. An effectively mixed fluid ring 184 surrounds the inefficiently mixed solids 186. A boundary layer of inefficiently mixed fluid 182 is between the layer limit of the effectively mixed fluid 184 and solids-free fluid 180. Referring to Figure 9, it can be seen more clearly that the stream of solid particles 188 and the solid-free fluid stream 180 are mixed in the chamber initial mix 150. Downstream, the solids-free layer 180 gradually decreases in height and flows near the bottom of the eductor 100. Additional mixing eddies can be seen in the intermediate mixing chamber 168. The generated water velocity profile by computer, shown in Figure 10, shows several ranges of fluid velocity. Reference 190 shows the fluid velocity in the range of about 10.08 to 12.61 meters / second. The range shown by 190 includes the flow of fluid out of the nozzle 110 and through the initial mixing chamber 150. From the profile, it appears that the fluid velocity remains in this upper range until it enters the first neck 164. The Speed range shown by reference 192 is around 7.58 to 10.08 meters / second. The range shown by reference 192 is in a boundary layer around the range 190 as well as in the second neck 174. Reference 194 shows the fluid velocity in the range of 5.05 to 7.58 meters / second. The range 194 is present in a boundary layer around the range 192 and through the first diffuser 160, the intermediate mixing chamber 168 and the second diffuser 170. The range of fluid velocity shown by 196 is in the range of 2.52 to 5.05 meters / second, which is mainly in mixing eddies of the initial mixing chamber 150 and the intermediate mixing chamber 168, as well as downstream of the second diffuser 170. The fluid velocity in the range of 0.0049 to 2.52 meters / second it is shown as reference 198 and is located in the area where the solid particles are added at an angle, normal or near normal, to the direction of the fluid flow of the nozzle 110. The slower fluid velocities 194, 196, 198 through the first diffuser 160, the intermediate mixing chamber 168 and the second diffuser 170 help to improve the mixing of the liquid and the solids by creating turbulence.

Test A test was performed using a variety of powder materials representative of solids that would be mixed with base liquid to form a drilling mud. The same funnel was used with the exception that the indicated mixing nozzles were used. Bentonite, polyanionic cellulose and XC polymer were introduced to the base liquid through several nozzles. Said particles are representative of other particles having the same or similar densities. The rheological properties of the resulting drilling muds were measured and recorded. These properties included fish eyes, creep point, and chimney viscosity. Fish eyes are known to those skilled in the art as a partially hydrated polymer globule caused by poor dispersion during the mixing process. The yield point is the yield stress extrapolated to a shear stress of zero. The yield point is used to evaluate the capacity of a mud to lift cuts from the rings of the well drilling. A high fluence point involves a non-Neo-ton fluid, one that carries cuts better than a fluid of similar density but with a lower yield point. Chimney viscosity is the time, in seconds for a quarter of mud, to flow through a chimney flue. This is not a true viscosity, but it serves as a qualitative measure to know the thickness of the mud sample. Chimney viscosity is useful only for relative comparisons. The comparison of each of these rheological properties can be seen in table 1 below: As can be seen, the fish eyes in the mud made of bentonite mixed with the inventive nozzle weighed less by volume than that mixed with the nozzles of the prior art. In addition, the creep point of the sludge was higher than the mud mixed with the nozzles of the prior art. The mechanical properties of the resulting drilling muds were also measured and recorded. These properties included the mixing energy, pressure drop, motive flow, vacuum, and induction of solids.

From the table, it can be seen that the eductor 100 can draw almost the same volume of solids per hour in the drive stream at a lower mixing energy than the prior art mixer. A method for mixing solid particles with a motor flow includes introducing a motor flow into an initial mixing chamber 150. This can be done through the nozzle 110, previously described. Within the initial mixing chamber 150, a vacuum is created due to the motor flow. The solids are introduced into the initial mixing chamber 150 and are induced to the driving fluid by the vacuum that has been created. A turbulence region is provided to initially mix the motive flow and the induced solids. The motor flow, which now carries the induced solids, diffuses to further entrain the solid particles. The initial mixture is further mixed in an intermediate mixing chamber. The intermediate mixing is then diffused again to provide additional turbulence to improve mixing. Before each diffusion, the mixture can be subjected to an increased flow rate by reducing the cross-sectional area through which the mixture flows. Although the claimed subject matter has been described with respect to a limited number of modalities, those skilled in the art, which have the benefit of this description, will appreciate that other modalities may be contemplated which do not depart from the scope of the subject matter claimed. , as described in the present invention. Therefore, the scope of subject matter claimed should be limited only by the appended claims.

Claims (15)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as a priority: CLAIMS

1. - An apparatus for mixing solids and liquids comprising: a nozzle having a nozzle inlet and nozzle outlet; an initial mixing chamber having a first chamber inlet, a second chamber inlet and a chamber outlet, wherein the first chamber inlet is in fluid communication with the nozzle outlet; a funnel that operates to supply solid particles to the initial mixing chamber through the second chamber inlet; a first diffuser having a first diffuser inlet in fluid communication with the chamber outlet, a first diffuser neck, and a first diffuser outlet; a second diffuser having a second diffuser inlet, a second diffuser neck and a second diffuser outlet; an intermediate mixing chamber that provides fluid communication between the first and second diffusers.

2. The apparatus according to claim 1, characterized in that the nozzle outlet is semicircular, and wherein the round entrance is centered around a first axis and the nozzle outlet is offset from the first axis.

3. The apparatus according to claim 2, characterized in that the nozzle outlet further comprises: a flat upper outlet edge located at a deflection distance below the first axis; and a semicircular lower edge that shares common side points with the upper edge and that defines an opening therethrough which has a nozzle outlet height.

4. The apparatus according to claim 3, characterized in that the nozzle further comprises: an interior surface extending from the nozzle inlet to the nozzle outlet; a first acceleration segment, wherein a top portion of the inner surface slopes downward and flattens toward a coextensive plane with the upper trailing edge; and a second acceleration segment, wherein a lower portion of the inner surface is inclined upwardly and inwardly to engage the lower edge of the nozzle outlet.

5. The apparatus according to claim 1, characterized in that the neck of the first diffuser and the neck of the second diffuser have an elliptical cross-sectional shape.

6. The apparatus according to claim 1, characterized in that the first diffuser further comprises: a first convergence section between the entrance of the first diffuser and the neck of the first diffuser; and a first divergence section between the neck of the first diffuser and the outlet of the first diffuser.

7. The apparatus according to claim 6, characterized in that the second diffuser further comprises: a second convergence section between the entrance of the second diffuser and the neck of the second diffuser; and a second diffusion section between the neck of the second diffuser and the outlet of the second diffuser.

8. An eductor for mixing solid particles in a driving fluid comprising: a nozzle having a nozzle inlet and nozzle outlet; an initial mixing chamber that receives the motor flow from the nozzle and receives solid particles, wherein a first mixing zone is formed within the initial mixing chamber to combine the driving fluid and the solid particles in an initial mixture; a first diffuser including a first convergence segment, a first neck, and a first divergence segment aligned in series; a second diffuser segment that includes a second convergence segment, a second divergence segment and a second neck aligned in series; an intermediate mixing chamber receiving the initial mixture from the first diffuser, wherein a second mixing zone is formed within the intermediate mixing chamber to further mix the initial mixture to provide an intermediate mixture of the driving fluid and the solid particles.

9. The eductor according to claim 8, characterized in that the nozzle inlet is circumferential about a first axis and the nozzle outlet is semicircular, defined by a flat portion a deflection distance of the first axis and a distal round portion of the first axis.

10. The eductor according to claim 8, characterized in that the nozzle further comprises: an upper exit edge located a distance of deviation below the first axis and extending in a straight line between opposite lateral points; a curved bottom trailing edge between the opposite lateral points of the upper trailing edge to define an aperture having a nozzle outlet height;

11. The eductor according to claim 10, characterized in that the nozzle further comprises: an input segment having an inner surface with an inner diameter; a first acceleration segment in fluid communication with the input segment and having an upper portion of the inner surface inclined downward and flattened and a lower portion of the inner surface remaining at a constant radial distance from the first axis; a second acceleration segment in fluid communication with the first acceleration segment and the nozzle outlet, wherein the upper portion of the inner surface continues to be inclined downward and flattened to engage the upper outlet edge below the first axis and the portion bottom of the inner surface is inclined upward to engage the curve of the lower outlet edge;

12. The eductor according to claim 8, characterized in that the first neck and the second neck each have an elliptical cross section.

13. A method for mixing a solid and a liquid comprising: introducing a driving fluid into an initial mixing chamber; create a vacuum to induce solids into the interior of the motive fluid; providing a first mixing zone for the mixing of the driving fluid and the induced solids; diffuse the driving fluid that carries the induced solids to increase the separation of the flow limit; and creating a second mixing zone to further mix the driving fluid with the solids.

14. The method according to claim 13, further comprising: repeatedly diffusing the motor flow to create a plurality of mixing zones to further mix the driving fluid with the solids.

15. The method according to claim 13, further comprising: diffusing the driving fluid a second time; and creating a third mixing zone to further mix the driving fluid with the solids.