The present disclosure relates to a conical spin contactor for performing, by means of solid particles, a biological or chemical transformation, or physical or chemical trapping from, or release of agents to, a fluidic media. The disclosure further refers to a process for performing such an operation using a conical spin contactor.
To get the best utilization of heterogenous catalysts and scavengers, it is necessary for the heterogenous rates of reaction and adsorption to be as high as possible. For reaction rates to be sufficient, it is preferred for smaller particles to be used. For example, when a test scavenger was exposed to a bulky molecule of palladium dichloride bis(triphenylphosphine), it was found that a scavenger under 150 microns in particle size diameter provided for rapid removal of palladium species. However, a 700-micron sized scavenger provided a much slower removal of the palladium species.
In conventional packed bed systems, it is necessary to have larger size particles in order to keep pressure drops low. However, the reaction rate is much slower with larger particle size. While smaller particles are desirable, they can be more difficult to contain. One way to deal with this tension is to use materials having a higher density.
A reactor filled with a packed bed of active ingredients spun driven by an external motor has been introduced. This reactor is submerged into a working fluid in a process vessel. As the bed reactor is rotated, liquid is pushed out of the cylinder's porous external wall via centrifugal force and is pulled into the reactor from the top and the bottom. It is believed that operation of this system would require large particles to limit the pressure drop across the packed bed.
A spin contactor is provided for contacting a particulate with a fluid. The spin contactor has a containment section containing the solid particulate, a lower fluid inlet, and an upper fluid outlet. The particulate may be a catalyst for catalyzing constituents in the fluid to react or an adsorbent or scavenger for adsorbing constituents in the fluid.
The containment section comprises a first particulate separator, a second particulate separator, and a conical wall. Optionally, the spin contactor includes a shaft to be operatively coupled to a motor for spinning the spin contactor causing fluid to be drawn upwardly through the fluid inlet to contact the particulate in the containment section and then be expelled through the fluid outlet.
Also provided is a process for treating a fluid composition, comprising charging or sending the fluid composition to a spin contactor which comprises a conical wall that defines a volume for containing particulates, rotating the spin contactor at a velocity sufficient to fluidize the particulates within the fluid composition in the defined volume, and contacting the fluid composition with the fluidized particulates to effect a physical or chemical transformation of the fluid composition. The transformed fluid composition is then discharged from the spin contactor while retaining the fluidized particulates in the spin contactor.
It has now been found that a rotating fluidized bed can efficiently adsorb or desorb species or catalyze reactants in a process vessel. A spin contactor has been designed to work with the small particle size diameters of scavengers and catalysts to achieve enhanced rates of reaction and utilization of these adsorbents and catalysts. The gains provided by the spin contactor enhance the end users' cost of ownership by minimization of the active agents needed, increasing reaction rates, and reducing process costs by simplification of the operation.
The basic design of a spin contactor 10 shown in
A first particulate separator 12 and a second particulate separator 28 constrain particles to remain within the containment section 14. Particulate separators at or near the top and bottom of the containment section 11, respectively, constrain particles, which are also referred to as particulate herein, to remain within the spin contactor 10. When a scavenger, adsorbent or catalyst is added to the spin contactor 10, a first particulate separator 12 and a second particulate separator 28 retain the particles within the containment section 11 of the spin contactor The particulate may be a material that is not reactive with the fluid.
In an embodiment of the spin contactor in
The top section 18 may be integral with or attached to the main containment section 14, such as by having matching screw threads or other mechanical connectors. The top section 18 may have a lower wall 19. The lower wall 19 may be frustoconical. In
The top section 18 may be equipped with a shaft 30. The shaft 30 may be coupled to a motor (not shown) that is employed to spin the spin contactor 10. An associated coupling bushing (not shown) may be employed to couple the shaft 30 to a shaft of the motor.
The conical section 9 can be truncated to define an open cone inlet 17 of the conical wall 15. The diameter of the open cone inlet will affect the pressure drop across the lower particulate separator. The open cone inlet 17 should be large enough to permit adequate flow through the spin contactor 10 but sufficiently small to draw fluid therethrough while spinning at an adequate flow rate to levitate the largest particles in the spin contactor.
The overall inner diameter of the spin contactor will be determined by the desired flow rate of the fluid. The overall height of the spin contactor 10 will be determined by the volumetric flow rate of fluid to be processed and the desired volume of the containment section 11.
A bottom containment section 13 may depend from the bottom of the main containment section 14. The bottom containment section 13 may be cylindrical and be contiguous with the open cone inlet 17 in the bottom of the main containment section 14. The bottom containment section 13 of the spin contactor 10 may attach to the main containment section 14 by matching screw threads or other mechanical connectors onto the bottom of the main containment section 14 or be integral with it. The spin contactor 10 may include a fluid inlet 24. In the orientation of
An external motor may be used to rotate the spin contactor. This motor may be a speed-controlled DC motor that may produce a rotational speed of, for example, about 50 to about 200 rpm. The rotational speed will be variably selected according to the diameter of the spin contactor, the density of the particles, and the particular liquid composition being processed.
The spin contactor 10 is submerged in a vessel containing fluid to be treated. Spinning or rotating the spin contactor 10 at a sufficient rotational velocity draws the liquid from the vessel to enter the lower fluid inlet 24 in the bottom containment section 13 of the spin contactor thus charging fluid to be treated to the spin contactor 10. The fluid fills the containment section 14 of the spin contactor through the cone inlet 17 as air is displaced by liquid. As a consequence of spinning the spin contactor 10, the containment section 14 is spun, in an embodiment. When the spin contactor is rotated, centrifugal force pushes liquid in the spinning containment section 14 in a direction perpendicular to the rotational axis 16, so as to contact the particulates therein. The centrifugal force is determined by the equation F=m2r where F is the centrifugal force, m is the mass of the liquid spinning, is the rotation rate and r is the radius of the mass of the fluid spinning. The radius of the mass of the fluid is dictated by the inner radius of the contactor 10.
In a cylindrical contactor with a cylindrical wall, the centrifugal force increases only as the rotation rate increases. However, in the disclosed spin contactor with an inverted frustoconical wall 15, the inner radius of the vessel increases with the height of the spin contactor 10 in the main containment section 14 defined by the conical wall 15. Since the centrifugal force increases as the radius increases with the height of the spin contactor 10, the fluid within the frustoconical containment section 14 will be propelled to rise within the spin contactor 10. The fluid in the spin contactor contacts the particulates therein, thus fluidizing the particulates. The particulates contacting the fluid impart a physical or chemical transformation to the fluid composition. For example, material may be scavenged from the fluid, desorbed into the fluid, or reactant(s) in the fluid may be catalytically converted to product(s). The treated or transformed fluid exits the main containment section 14 through the containment outlet 26 into the top section 18. The upward fluid movement eventually urges the treated fluid in the top section 18 out the fluid discharge outlet(s) 22 in the top section while the particulates are retained in the spin contactor 10.
The conical main containment section 14 is truncated at the vertex of the cone to provide a frustum. Truncation provides a fluid inlet 24 which minimizes the pressure drop through the lower particulate separator 12. The fluid inlet 24 must be sized to draw an adequate flow rate through the spin contactor 10 sufficient to levitate the largest particles in the spin contactor. Sizing of the fluid inlet 24 should also consider the pressure drop imposed by the lower particulate separator 12. In our testing, we have found the fluid inlet 24 having an inner diameter of about ¼ to ⅓ the inner diameter of a base of the cone defined by the conical wall 15 has been adequate to achieve these considerations. The base of the cone defined by the conical wall 15 may also define the containment outlet 26 in
At a given value of w, pressure drop in the contactor 10 generated by obstruction of the upper and lower particulate separators 28, 12 and general viscosity effects limit the flow rate through the spin contactor 10. Solids loading is defined as the ratio of the mass of solid particulates to the sum of the mass of solid particulates and fluid in the containment section. The solids loading will depend on the particular application of the spin contactor. The solids loading should be sufficiently low to allow fluidization of the particles in the containment section while the contactor is spinning. Notably, when the solids loading is less than about 5 wt % to about 20 wt %, the viscosity of the native diluent is not very sensitive to the levels of solids. The flow of liquid is from the bottom to the top of the spin contactor. This flow levitates the particles in the fluid. At these loading levels, viscosity of the solution will not promote pinning the particulate to the upper particulate separator 28 and still promote sufficient reaction, adsorption or desorption rate.
The shape of the spin contactor is important. Preferably, flat areas or horizontal ledges on the interior walls are to be avoided because they provide settling points for the particles. When an active ingredient settles out, mass transfer to the particle is reduced and these areas may generate dead zones. Therefore, it has been found that conical transitions along the sides of the wall of the containment section may be preferred, so levitated particles can continue to fall to lower regions of the containment section if not rising and freely circulate therein.
In the majority of applications, the particulate material in the containment section will have a particle size distribution (PSD) that is not monodisperse. The conical wall 15 of the main containment section 14 will generate a gradient of fluid velocities as the diameter of the containment section increases with height. This gradient of fluid velocities allows for the levitation of the entire range of the PSD. The particulates may have an average particle size of about 1 to about 3000 microns, typically about 10 to about 500 microns, suitably about 10 to about 150 microns, or preferably about 30 to about 150 microns. It is also envisioned that the containment section 11 alternatively has decreasing internal radius with height in which centrifugal force would increase from top to bottom.
In the ideal case, a sufficient amount of particulate active ingredient (scavenger or catalyst) is desired to complete the kinetic transformation in the spin contactor of a given volume of the containment section 11 during the time necessary to transport the fluid through the spin contactor 10. That is to say, the feed within the spin contactor is completely exchanged in a given unit of time required to move 1 bed volume through the spin contactor. Through routine experimentation the rotation rates for a particular size of spin contactor and fluid being processed can be optimized. It is envisioned that in one embodiment the spin contactor 10 may be in downstream communication with an upstream reactor or an adsorption vessel, so the spin contactor 10 may provide polishing treatment of the fluid.
In order to avoid a high pressure drop across lower particulate separator 12, the rotation rate should be fast enough to levitate the particulates above lower particulate separator 12, so that the particulates become fluidized and do not form a packed bed on the lower particulate separator 12. Similarly, in order to avoid a high pressure drop across upper particulate separator 28, the rotation rate should be slow enough such that the levitated particulates remain fluidized in containment section 14 but do not form a packed bed against upper particulate separator 28. A rotation rate of about 30 to about 250 rotations per minute, preferably about 50 to about 200 rotations per minute were found to be suitable.
In a purely conical or frustoconical profile, the maximum flow due to centrifugal force will be at the maximum diameter of the conical body. The result is that the maximum flow moves up the side of the conical wall 15 as shown by arrow 32. The particles will therefore be at a higher concentration along the conical wall 15 of the main containment section 14. This could lead to an uneven distribution of particles within the containment section 11 which could lead to lower conversion or adsorption efficiencies.
This effect can be minimized by several approaches that may be used individually or in combination. The effect can be minimized operationally by rotating the spin contactor 10 at a rotational velocity sufficient to disperse or fluidize the particles within the spin contactor but insufficient to cause the particles to gravitate or channel against the conical wall 15.
The spin contactor 10 can be configured to minimize aggregation of particulate along the conical wall 15 by several ways. First, a cylindrical top section 18 above the main containment section 14 as shown in
Second, the fluid outlet 29 could be configured to further straighten flow even more deliberately by locating the fluid outlet only in the center of the partition 23 as shown in
Third, fluid flow can be straightened by installing a flow straightener 214 into the spin contactor as shown in
The flow straightener 214 comprising outlet tubes 212 is disposed above the upper particulate separator 217, so the particles do not accumulate above the flow straightener. The flow straightener 214 is not shown in phantom, so it is better visualized. The inlets of the outlet tubes 212 are above the upper particulate separator 217 and the outlets of the outlet tubes 212 can communicate through the partition 223 which comprises a tube sheet. The flow of the fluid through the outlet tubes 212 pulls the fluid up from the conical containment section 205 of the spin contactor 200. Hence, in the conical containment section 205 below the outlet tubes 212, the flow is more purely vertical. As shown in
Fourth, baffles or other turbulence inducing structures may be added to the inner wall of the containment section.
External blades 304 allow elimination of separate stirring equipment. These blades may allow the user to agitate the fluid before the fluid is charged through the spin contactor. In general, such external blades can extend significantly below the bottom inlet of the spin contactor.
As shown in
In one embodiment is provided a spin contactor for contacting a particulate with a fluid, said spin contactor comprising a containment section containing said particulate and having a conical side wall, a fluid inlet, and a fluid outlet. The spin contactor comprises an upper particulate separator and a lower particulate separator. The spin contactor has a shaft to be operatively coupled to a motor for spinning the spin contactor whereby the fluid is drawn upward through the lower fluid inlet to contact the particulate in the containment section and then is expelled through the upper fluid outlet. The fluid outlet may comprise one or more openings disposed above the upper particulate separator. The containment section may further comprise a cylindrical wall above or below, or both above and below the partially conical wall. The upper and lower particulate separators can comprise a screen, a fabric, a frit, or any other material that will allow the fluid and its desired components to pass into and out of the containment section, while retaining the particulates within the containment section. The upper particulate separator may comprise a screen positioned above the containment section and configured to constrain particles to remain within the containment section of the spin contactor. The lower particulate separator may comprise a screen positioned below the containment section at or near the bottom of the spin contactor and configured to constrain particles to remain within the containment section of the spin contactor. The spin contactor may comprise a non-reactive material disposed within the spin contactor. The spin contactor may have about 60-90% of a height of the containment section having a conical profile and about 10-40% of the height of the containment section having a cylindrical profile. In the embodiment of
In another embodiment is provided a process of treating a fluid composition, comprising charging the fluid composition to a spin contactor comprising a conical wall that defines a volume containing particulates, rotating the spin contactor at a velocity sufficient to fluidize the particulates, contacting the fluid composition with the fluidized particulates to effect a physical or chemical transformation of the fluid composition, and discharging the transformed fluid composition from the spin contactor while retaining said fluidized particulates in the spin contactor. There may further be a particulate separator at or near a top of the spin contactor that constrains said particulates to remain within said spin contactor. The particulates have an average particle size of 1-3000 microns, 10-500 microns, 10-150 microns, or 30-150 microns. The spin contactor is rotated at a sufficient velocity so that particulates within the spin contactor are dispersed wherein said sufficient velocity is less than a maximum velocity at which particles are forced against the walls of the spin contactor. The spin contactor may be positioned in a vessel containing the fluid composition. In the process, the mixture enters the spin contactor through an opening at or near a bottom of the spin contactor and exits through the top. The spin contactor may be partially or completely submerged into a liquid in a vessel. The process may further comprise generating a gradient of particle size distribution of the particulate in a containment section. The flow may be straightened through the top of the spin contactor. It is anticipated that a fluid after flowing through the spin contactor will exit but then may return to the spin contactor to be further treated or reacted.
This application claims priority from U.S. Provisional Application No. 63/345,870, filed May 25, 2022, which is incorporated herein in its entirety.
Number | Date | Country | |
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63345870 | May 2022 | US |