Abstract:
The invention provides a thin film tube reactor, including an elongate tube that is rotatable about its longitudinal axis. A mixing plate rotatable about the tube&#39;s longitudinal axis may be positioned within the tube near the inlet. A plurality of fluid process components are fed into the tube and directed toward the mixing plate. In the absence of the mixing plate, the process components are directed toward the inner surface of the tube. Heating and cooling elements surround the tube to control the process temperature at particular points along the tube. A structured surface that is integral with or affixed to the inner surface of the tube immobilizes a catalyst slurry applied to the inner surface. A separation reservoir includes an end plate with a plurality of radially spaced outlet ports for controlling the output of the products from said separation reservoir.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to chemical reactors and thermal processing equipment.  
       BACKGROUND OF THE INVENTION  
       [0002]     A common problem in chemical reaction processes is how to achieve the proper hydrodynamics in the reactor to efficiently produce the desired products. The reactants must be mixed so that the molecules of the reaction components come into contact with the other components in the reaction including catalysts. The presence of a gaseous reactant requires the increase of the surface area of the boundary between the gas and the liquid components to increase the efficiency of the reaction. Many processes require fine temperature control or added energy from an electromagnetic field. In some cases rapid temperature changes are desired though difficult to achieve due to the thermal inertia of the reaction components. Also, it is often difficult to ensure proper saturation of the reaction components by an electromagnetic field as the outermost portion of the mixture of reactants tends to be exposed to more radiation than the innermost portion.  
         [0003]     Thin film reactors are known to overcome many of these issues however an improved thin film reactor is needed. For example, techniques are known for applying a catalyst to a surface for use as a thin film reactor to thereby provide improved contact with the process components. Such techniques include sol-gel or washcoating, which can be used to adhere a catalytically active coat onto the inner wall of a reactor. However, these coats tend to suffer from attrition and will inevitably deactivate with time. Further, there a number of patents in the art that attempt to address some of the above issues are described below.  
         [0004]     U.S. Pat. No. 6,742,774 to Holl discloses a reactor that produces a gas-in-liquid emulsion for providing increased interfacial contact area between the liquid and the gas for-improved-reaction of the gas with the liquid, or more rapid solution or reaction of a gas in or with a liquid. Rotor and stator cylindrical members are mounted for rotation relative to one another and have opposing surfaces spaced to form an annular processing passage. The gap distance between the opposing surfaces and the relative rotation rate of the cylindrical members are such as to form a gas-in-liquid emulsion. Holl is thus directed to a process for mixing a gas and a liquid into an emulsion to increase the contact between the gaseous and liquid components rather than forming a thin film with a large surface area.  
         [0005]     U.S. Pat. No. 6,512,131 to Best, et al. discloses a process for carrying out a multi-phase reaction in a continuously operated tube reactor with a liquid phase flowing downwards as a thin film in said tube reactor and components of a continuous gas flowing upward in said tube reactor are brought to material transfer, or reaction respectively. Best uses gas pressure modulation to maintain the thin film and thus does not rotate the tube to provide or maintain the thin film nature of the liquid phase of the reaction. Further, Best does not provide for the separation of multiple products in an integrated separation reservoir.  
         [0006]     U.S. Pat. No. 4,675,137 to Umetsu discloses a method for producing a polyacetylene film by introducing acetylene gas into a vessel for storing Ziegler-Natta catalyst to polymerize the acetylene gas with the catalyst. Rotating the vessel coats the side wall with the catalyst. Thus, the acetylene gas introduced into the vessel is polymerized with the catalyst to produce the polyacetylene film. Umetsu&#39;s method is not a continuous process and the catalyst is not immobilized.  
         [0007]     U.S. Pat. No. 4,353,874 to Keller, et al. discloses a rotary tube reactor, having at least one treatment line composed of tubes with individual sections having gas chambers that are sealed from each other. Each section has a gas outlet and adjacent sections are joined together by material passages. The reactor is used for thermal treatment. Keller relies on multiple tubes to transport reactants within the rotating tube and does not form a thin film on the inner surface of the rotating tube.  
         [0008]     U.S. Pat. No. 4,335,079 to Vander Mey discloses an apparatus for a continuous process which comprises introducing a liquid onto a spherical rotating reaction surface as a thin film and rotating the reaction surface at a velocity such that the thin film is continuously moved toward the periphery of the reaction surface. Vander Mey divides the reaction surface into a plurality of areas and deposits within each area a controlled quantity of gas over the liquid film. A sub-atmospheric pressure is maintained while the temperature of the reaction surface is controlled. The reaction product moves to the periphery of the reaction surface by centrifugal action and the reaction product is continuously collected. Vander Mey is directed specifically toward reacting a thin film with a gas. Further, Vander Mey relies on a spherical reaction surface to move the film toward the product collection element and does not discuss the separation of multiple products.  
         [0009]     U.S. Pat. No. 4,311,570 to Cowen, et al. discloses chemical processes using thin films of reactants carried out on the surface of a body rotating at high speed. The solid and insoluble liquid products are isolated by using centrifugal force to fling the products from the rim of the body into the surrounding atmosphere. Thus, Cowen relies on products that are solid, such as fibers or powders, or liquids that are incompatible with other products for separation. Further, Cowen requires that-at least part of the reaction surface of the reactor be inclined with respect to the axis of rotation.  
         [0010]     Therefore, a reactor or thermal processor that utilizes a rotating tube to create a thin film of process components for a continuous reaction is desired. Further, a reactor or thermal processor that utilizes an improved separation means is desired.  
       SUMMARY OF THE INVENTION  
       [0011]     The invention comprises, in one form thereof, a thin film tube reactor, including an elongate tube that is rotatable about its longitudinal axis. A mixing plate rotatable about the tube&#39;s longitudinal axis may be positioned within the tube near the inlet. A plurality of fluid process components are fed into the tube and directed toward the mixing plate. In the absence of the mixing plate, the process components are directed toward the inner surface of the tube. Heating and cooling elements surround the tube to control the process temperature at particular points along the tube. A structured surface that is integral with or affixed to the inner surface of the tube immobilizes a catalyst slurry applied to the inner surface. A separation reservoir includes an end plate with a plurality of radially spaced outlet ports for controlling the output of the products from the separation reservoir. The invention is especially suited for such reaction types as photoprocessing, reactive distilling, and stripping processes.  
         [0012]     An advantage of the present invention is that the rotating tube creates a thin film of process components for a continuous reaction.  
         [0013]     A further advantage of the present invention is that the separation of components in the film occurs in the outlet section of the invention to minimize downstream processing. Also, the separation reservoir may be integral with the reactor such that the invention provides a continuous reaction and separation in a single enclosed module. A particular advantage of an integral separation reservoir is that as the products are removed from the system, unspent reactants continue to react to form additional products, thereby reducing the waste of unspent reactants.  
         [0014]     An even further advantage of the present invention is that the thin film has a low thermal inertia for rapid temperature changes and allows simplified exposure to electromagnetic fields. The thin film further allows all constituent components to be rapidly mixed on the molecular level and the shear stresses applied to the thin film by the rotating tube further promote mixing. The thin film has a large surface area and therefore there is excellent contact between a gaseous component and the film.  
         [0015]     A still further advantage of the present invention is that several tube reactors may be connected in series wherein the separate tube reactors may have different processing parameters such as angular velocity and diameter. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become apparent and be better understood by reference to the following description of particular embodiments of the invention in conjunction with the accompanying drawings, wherein:  
         [0017]      FIG. 1A  is a schematic of a tube reactor of the present invention;  
         [0018]      FIG. 1B  is a schematic of one configuration of the input of  FIG. 1A ;  
         [0019]      FIG. 2A  is a schematic of the tube reactor of  FIG. 1A  having output passages and a drive wheel;  
         [0020]      FIG. 2B  is a schematic of the tube reactor of  FIG. 2A  having a weir configuration;  
         [0021]      FIG. 3  is a schematic of multiple tube reactors connected in series;  
         [0022]      FIG. 4  is a schematic of the tube reactor of  FIG. 1A  having heating and cooling elements;  
         [0023]      FIG. 5  is a sectional view of the tube reactor with a structured surface for immobilizing a catalyst element;  
         [0024]      FIG. 6  is a schematic of a tube reactor configured for controlling the residence time of a slow moving film; and  
         [0025]      FIG. 7  is a cross-sectional view of a tube reactor having a plurality of reaction surfaces. 
     
    
       [0026]     Corresponding reference characters indicate corresponding parts throughout the several views. The examples set out herein illustrate particular embodiments of the invention but should not be construed as limiting the scope of the invention in any manner.  
       DETAILED DESCRIPTION  
       [0027]     Referring to  FIG. 1A , there is shown the thin film tube reactor of the present invention. The tube reactor  10  includes a primary tube  12 , and a separation reservoir  14 .  
         [0028]     The primary tube  12  includes a feed tube  20  configured for depositing reactants onto an inner surface  22  of the primary tube  12 . Alternatively, one or more feed tubes  20  configured in an array or coaxially as shown in  FIG. 1B  direct reactants toward a rotating mixing plate  24 . The mixing plate  24  may be circular or any other shape. This adaptation allows rapid mixing of the reactant streams and is particularly suited for processes which require the mixing of reactants of different viscosities or the mixing of steams with vastly different flow rates. The centrifugal force then transfers the fluid from the mixing plate  24  to the inner wall  22 . The surface of the mixing plate  24  may include structures to improve the hydrodynamics of the thin film on the surface. For example, a spiral structure on the surface of the mixing plate  24  may slow the outward flow of the thin film.  
         [0029]     The primary tube  12  is rotated by a motor, which, in one embodiment, is coupled to a drive wheel  25  by a timing belt. Alternatively, the drive wheel  25 , shown in  FIG. 2A , is driven by gears in communication with the motor or the primary tube  12  is connected to the drive shaft directly. The interface between the feed tube  20  and the primary tube  12  may be a clearance fit or a sealed bearing to allow the primary tube  12  to rotate while the feed tube  20  does not.  
         [0030]     The reactants are fed to the feed tube  20  by a method suited to the properties of the reactants. For example, a screw feed hopper may be used to deliver certain solids and liquids. A pneumatic delivery system may be used to deliver certain solids. Fluids may be delivered by a pump system.  
         [0031]     The separation reservoir  14  includes a reservoir inner wall  26  and an end plate  28 . The end plate  28  forms a plane that is substantially perpendicular to the axis of rotation and includes two or more radially spaced outlets  30 . Each of the outlets  30  are positioned and sized such that the stream that exits through a particular outlet has a particular concentration of one component of the fluids and/or solids in the separation reservoir  14 .  FIG. 2A  shows a plurality of outlet passages  31  in fluid communication with the outlets  30 . In a particular embodiment shown in  FIG. 2B , weirs  29  are used to control output of the reaction products. Alternatively, a weir  29  may be used in conjunction with the end plate  28 .  
         [0032]     In a particular embodiment of the invention, a crossflow filtration membrane is incorporated into the reservoir inner wall  26 . The membrane filter is configured to remove a particular mixture component in the separation reservoir. For example, the membrane filter may be hydrophilic, hydrophobic, or size selective to remove such components as water, oils, or certain particulates. Further, a dead-end filtration membrane may be incorporated into the channels  31  connected to the outlets  30 .  
         [0033]     Alternative filtration methods that may be incorporated into the tube reactor  10  include ultrafiltration, reverse osmosis, and nanofiltration. In ultrafiltration, a composite membrane is spiral-wound about a central axis and the feed is axially driven through the resultant ultrafiltration cylinder. The composite membrane used in ultrafiltration may be configured to retain such contaminants as solids, colloids, and large organic molecules. Reverse osmosis is a particularly fine filtration method that uses a semi-permeable membrane in a crossflow configuration to remove contaminants from fluids such as water, ethanol, and glycol. Reverse osmosis requires a pressure differential across the membrane. Nanofiltration is a reverse osmosis technique that uses a less discriminating membrane that allows certain ions such as Na+, K+, and Cl− to pass.  
         [0034]     The separation reservoir  14  is in fluid communication with the primary tube  12 ; however, the separation reservoir  14  may be connected to the primary tube  12  through a coupling that allows the separation reservoir  14  to rotate at a different rate than the primary tube  12 . Further, a plurality of primary tubes  12  may be connected in series as shown in  FIG. 3 . A reaction process may require that the primary tubes  12  each have different-diameters and axial velocities. The plurality of primary tubes  12  may be driven by a single drive system that is geared to drive each primary tube  12  at the axial velocity required by the reaction process. The primary tubes  12  are connected by non-rotating connecting pipes  32 , each of which may connect two or more tube reactors  10 . The connecting pipes  32  are coupled to the primary tubes  12  by a rotating to non-rotating union  34  that comprises a bushing or a bearing. Alternatively, a connecting pipe  32  is coupled to a primary tube  12  using a simple bearing with a seal. The connecting pipes  32  allow the introduction of additional components to the reaction process between tube reactors  10  as well as the removal of products and waste such as by the use of a separation reservoir  14 . The advantage of using multiple tube reactors  10  is that the parameters of each tube reactor  10  may be configured so that the system of reactors achieves the required hydrodynamic regime according to the process requirements.  
         [0035]     In a particular embodiment shown in  FIGS. 2A, 2B , and  4 , one or more heating jackets  36  and cooling jackets  38  are applied to the primary tube  12  for controlling the reaction temperature. Further, since the fluids in the primary tube  12  form a thin film on the inner surface  22 , the fluids have a low thermal inertia. Thus the fluids in the primary tube  12  may be rapidly heated and cooled by heating jackets  36  and cooling jackets  38 . Therefore, the tube reactor  10  is well suited for thermal processing and separation of components with or without a chemical reaction. The heating jackets  36  may comprise inductive, resistive, or conductive heat transfer elements. Alternatively, a heat transfer fluid is used. The heating jackets  36  and cooling jackets  38  may incorporate special heating structures to improve the thermal performance. Further, the inner surface  22  may incorporate structures that break down the boundary layer in the thin film to thereby increase the performance of the heat transfer. More particularly, surface roughness on the inner wall  22  causes more turbulent flow in the thin film. Thus, there is greater mixing of the thin film and the thermal boundary layer is reduced. A small thermal boundary layer indicates a small thermal gradient and improved heat transfer performance.  
         [0036]     Further to modifying the inner wall  22 , the outer surface of the primary tube  12  may be affected to improve the heat transfer between the wall and a heat transfer fluid. For example, surface effects such as fins may be included to increase the surface area of the outer surface. Also, the surface roughness of the outer surface may be configured to reduce the boundary layer of the heat transfer fluid to increase heat transfer.  
         [0037]     It is often desirable to use a catalyst to initiate or speed up a reaction process. As shown in  FIG. 5 , a slurry of catalytically active solid particles  40  is immobilized on the inner wall  22  through the use of a structured surface  42  such as a mesh. The structured surface  42  is bonded or machined onto the inner wall  22  with substantially no passages between compartments in the mesh  42 . The catalyst slurry  40  is passed through a non-rotating or a slowly rotating reactor until the catalyst slurry  40  has wetted the entire mesh  42 . At this point, the rotational rate is increased to the reaction process velocity. The centrifugal force acts to hold the particulates in the catalyst slurry  40  in the pores of the mesh  42 . The process fluid readily flows over the mesh  42  and contacts the catalyst slurry  40 . The bed activity can be maintained by adding small amounts of catalyst slurry  40  to the feed  20 . The entire catalyst slurry  40  is replaced by slowing the rotation of the tube reactor  10  and flushing the spent catalyst slurry  40  with a fluid. The new catalyst slurry  40  is then administered as described above. Alternatively, a catalyst that does not require frequent replacement is simply affixed to the inner wall  22 .  
         [0038]     Many processes require an external energy input such as electromagnetic radiation to promote the reactants to a state where reaction can take place. The tube reactor  10  is particularly well suited to exploit these field effects due to the hydrodynamics and scale of the film thickness. The film is sufficiently thin that almost complete saturation will occur. This ensures that all the reaction components will be exposed to substantially the same level of irradiation, which ensures good product uniformity and can be used to promote selectivity. As the tube reactor  10  is rotating it is not essential to illuminate the entire wall. By controlling the rotational rate, it is possible to ensure that the fluid passes through the zone of illumination as many times as is required by the process. Further, since the tube reactor  10  is hollow, the radiation source may be within the tube reactor  10  to thereby irradiate the thin film from inside the tube. This has the benefit of increased flexibility in the tube materials since the tube is not required to be transparent to the radiation.  
         [0039]     The wall of the tube reactor  10  may be replaced entirely or in parts with transparent sections. This allows indirect and non invasive techniques to collect valuable data regarding the process conditions and degree of reaction. Such examples of these techniques include Raman spectroscopy and IR thermometry. The transparent sections may also be used to expose the fluid to sources of electromagnetic field radiation as described above.  
         [0040]     The tube reactor  10  is particularly accommodating to a gaseous process component such as a catalyst or a reactant. The large surface area of the thin film provides excellent contact between the gas and the film. For example, a gaseous process component may be added to remove a particularly volatile component of the film in the form of a gas. Further, a vacuum device may be used to enhance the ability of the tube reactor  10  to remove unwanted components that will exit the thin film in the form of a gas when under negative pressure. Normally, the gasses are introduced or the vacuum is applied using a coaxial passage, however, other methods may be imagined by one skilled in the art. For example, a stationary manifold having a sealing engagement with a perforated portion of the primary tube  12  while allowing the primary tube  12  to rotate may be used to apply a vacuum or introduce a gas to the reactor  10 . Alternatively, a rotating to non-rotating union  34  in communication with the primary tube  12  and/or the separation reservoir  14  may act as a manifold for applying a vacuum or introducing a gas.  
         [0041]     In use, the process components are fed into the tube reactor  10  through the feed tubes  20 . For process components that tend to mix well, a mixing plate  24  is not needed and the process components are directed toward the inner wall  22  as shown in  FIG. 1A . The primary tube rotates at a particular velocity to form a thin film of the reactants on the inner surface  22 . Further, shear stresses due to slippage between the inner wall  22  and the film enhance the mixing of the process components. Some process components need additional mixing and thus the mixing plate  24  may be included. In this case, the feed tubes  20  direct the process components toward the mixing plate  24 , which rotates about the axis of rotation of the primary tube  12 . The centrifugal force of the mixing plate  24  mixes the process components and forces them outward to the inner wall  22 . As the process components are added to the inner wall  22  and the centrifugal force forms them into a thin film, previously added process components are forced out from under the newer components in the only direction available which is along the inner wall  22  toward the separation reservoir. As the components traverse the primary tube  12  they react with each other and any gas that may be present to result in the process products. Further, temperature control is affected by heating jackets  36  and cooling jackets  38  and any electromagnetic radiation required by the process is added to the thin film through the wall of the primary tube  12 .  
         [0042]     The products of the reaction process, and any remaining process components, build up in the separation reservoir  14  and the centrifugal force causes components of the separation mixture to separate. More particularly, the higher the density of a mixture component, the closer to the inner surface  26  that component resides in the separation reservoir  14 . Since the composition of the separation mixture is known, the outlets  30  are radially spaced on the end plate  28  such that it is known which component exits through which outlet. In this manner waste products are separated from the useful products.  
         [0043]     In the case that multiple tube reactors  10  are connected in series, the products of a first tube reactor enter the non-rotating connecting pipe  32  through the union  34 . While products may be added and removed along the primary tube  12 , the connection pipe  32  is convenient for products to be removed or additional reaction components to be introduced to the system. Subsequently, the components pass into a second tube reactor through another union  34  for the next stage of the process.  
         [0044]     A more specific use of the invention is a heat treatment process for pasteurization. The pasteurization process requires that a volume of fluid is heated to a temperature and held for sufficient time that bacterial organisms are killed. Heating to a higher temperature reduces the time but can lead to protein denaturing. For example, milk pasteurization requires that the milk be maintained at a temperature of about 63° C. for at least about 30 minutes, 72° C. for at least about 16 seconds, or 138° C. for at least about 2 seconds. The primary tube  12  is surrounded by the heating jacket  36  and then the cooling jacket  38 . The fluid, such as milk, is input to the rotating primary tube  12  through feed tube  20  and forms a thin film on the inner wall  22 . The heating jacket  36  rapidly heats the thin film to the required temperature. A particular embodiment of the invention is capable of generating heat transfer coefficients over 8000 W/m 2 ·K (Watts per square meter per degrees Kelvin). The thin film is then rapidly cooled by the cooling jacket  38  to prevent product denaturing. The fluid then enters the separation reservoir  14  where high fat content milk (cream) is separated from lower fat content milk (skimmed).  
         [0045]     A further specific use of the invention is a method of ink jet toner preparation. In such a method, a polymer is dissolved in a volatile organic solvent to form an aqueous emulsion. Chemical additives are added and the emulsion is fed into the primary tube  12  through feed tube  20 . A vacuum is applied to the reactor  10  as described above and a heating jacket  36  is included as shown in  FIG. 2A . The organic phase is then removed from the aqueous phase and the emulsions become a suspension. The suspension flows into the separator section  14  where the solid phase tends towards the reservoir inner wall  26  and the aqueous phase more inner-wards. A slight outward taper of the separation reservoir  14  aids in the flow of the solids towards the end plate  28 . The high solids phase is drawn out through the outlets  30  using a suitable pumping device such as a diaphragm pump.  
         [0046]     A further specific use of the invention is a particular chemical reaction. In such chemical reaction, alkali is dissolved in a low order alcohol and the stream is fed onto the center of the mixing plate  24  through a feed tube  20  as shown in  FIG. 1B . A stream of triglyceride is also fed to the mixing plate  24  through a separate feed tube  20 . The mixing plate  24  acts to mix the streams and initiate reaction. The inner wall  22  of the primary tube  12  is heated by heating jacket  36  to further heat the reactants thereby increasing the reaction rate. The stream enters the separation reservoir  14  where a stream containing fatty acid derived methyl ester tends innermost, exiting the reactor  10  through the innermost outlets  30 . The second product stream, exiting through the outermost outlets  30 , contains glycerol, alkali catalyst, alcohol and soap.  
         [0047]     An even further specific use of the invention is the mixture and reaction of two or more reactants that form an insoluble particle. Particularly, the feed tubes  20  co-feed two salt solutions, such as a sodium carbonate solution and a calcium sulfate solution, into the primary tube  12 . The rotation of the primary tube  12  rapidly mixes the reactants while forming the mixture into a thin film on the inner wall  22 . Within the thin film mixture, the two salt solutions exchange ions and during this exchange, the calcium ions and the carbonate ions combine to form fine particles of calcium carbonate. The products of the reaction enter the separation reservoir  14  where the centrifugal action causes the insoluble calcium carbonate particles to precipitate out from the product stream in a slurry. The calcium carbonate slurry is then easily removed from the reactor  10  through the outlets  30 , separate from the other products of the reaction. The rapid mixing and the formation of the thin film put the salt solutions, and thus the different ions, in close proximity allowing an improved number of calcium ions to come into contact with carbonate ions. Therefore, the reactor  10  has an improved reaction efficiency for forming calcium carbonate particles.  
         [0048]     In a further embodiment shown in  FIG. 6 , a low rate tube reactor  110  is configured for a reaction process with inherently slow kinetics. The low rate tube reactor  110  produces a slow moving film with a controlled residence time. In this particular embodiment, the tube reactor  110  includes a straight separation section  114 . The end plate  128  comprises two radially spaced exits  130 . The exits  130  are situated in the end plate  128  or, alternatively, one exit  130  is located in the circular wall with one or more exits  130  in the end plate  128 . This arrangement leads to thicker films than the tube reactor described in the previous embodiments and has the added advantage that a considerable amount of slippage will occur between the inner wall  122  and the inner most surface of the film. This creates another mixing regime and ensures that although the film is moving with a lower axial velocity, it is still experiencing significant shear stress.  
         [0049]     The thickness of the film may be alternatively controlled using the reactor  10  with a separation reservoir  14  having a larger diameter than the primary tube  12  as described in the first embodiment. In this case, the reaction is initiated normally except that the products are not initially allowed to exit the separation reservoir  14 . The components build up in the separation reservoir  14  and subsequently cause the film in the primary tube  12  to thicken. Once the desired thickness is achieved, the products are removed through the exits  30  at the same rate the reactants are fed to the primary tube  12 . Thus, the desired film thickness is maintained.  
         [0050]     In a further embodiment, the reactor  210  comprises several reaction surfaces  222  formed by channels  244  in a substantially symmetric rotating body such as a rotating cylinder  212 . The cross-section of an example of such a reactor  210  is shown in  FIG. 7 . This configuration allows several separate reactions to run simultaneously in reactor  210 . A multistage reaction may be accommodated by reactor  210  by merging two or more channels  244  at some point along the length of the reactor  210  to combine the products of the reactions in the merged channels  244  and start a second stage of the reaction in the new channel.  
         [0051]     It should be particularly noted that a spinning disk similar to the mixing plate  24  of  FIG. 1B  may be sufficient to carry out certain thin film reactions, however, mechanical restrictions limit the residence time of reactants on such spinning disks. The addition of a rotating primary tube  12  according to the present invention may increase the residence time of the reaction while maintaining the proper hydrodynamics. The spinning disk may be driven by the same drive mechanism as the primary tube  12 , a separate drive mechanism, or the feed tubes may be configured to supply the reactants and drive the spinning disk. The spinning disk may therefore spin at different rates in order to achieve the proper hydrodynamics of the reaction. Further, the spinning disk may be heated or cooled to improve the efficiency of the reaction.  
         [0052]     It should be noted that the residence time of a reaction in the tube reactor  10  as shown in  FIG. 1A  may be calculated using the following formula from U.S. Pat. No. 4,311,570 to Cowen, et al. (Cowen): 
 
 t =((6 πr   2 μl 5 )/( Q   3   f   2 ρ)) 1/4  
 
 Where t is the residence time, ρ is the density of the liquid, μ is the viscosity of the liquid, Q is the volumetric feed rate of the liquid, and I is the length, r is the radius, and f is the rate of rotation of the primary tube  12  in revolutions per unit time. Further, the film thickness may be calculated for a measured residence time using the following formula, also from Cowen: 
 
(Qt)/(2πrl) 
 
         [0053]     It should be noted that although the invention has been described with a cylindrical tube, myriad tube shapes may be imagined for further embodiments of the invention. For example, a tapered primary tube  12  may be required to maintain the hydrodynamics of the reaction if the thin film changes viscosity as the reaction progresses. In a further example, it may be desirable to incorporate a tapered transition between the primary tube  12  and the separation reservoir  14 . In an even further example, a tapered separation reservoir  14  may be desired for certain solids that tend to contact the reservoir inner wall  26 . Such solids may not readily migrate to the end plate  28  unless the separation reservoir  14  is tapered.  
         [0054]     While the invention has been described with reference to particular embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope of the invention.  
         [0055]     Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope and spirit of the appended claims.