Abstract:
Systems and apparatus for mixing, cooling, and distributing multiphase fluid mixtures within a reactor, wherein reactor internal apparatus of the present invention provides not only improved fluid mixing and distribution to each underlying catalyst bed surface, but also offers other advantages including: decreased mixing tray height; easier maintenance, assembly and disassembly; and decreased amounts of fabrication material. In an embodiment, fluid may be evenly distributed to a catalyst bed from a fluid distribution unit comprising a nozzle tray including a plurality of nozzles, wherein the nozzles include at least one liquid inlet disposed tangentially to an inner surface of the nozzle.

Description:
FIELD OF THE INVENTION 
     This invention relates to systems and apparatus for multiphase fluid contact and distribution. 
     BACKGROUND OF THE INVENTION 
     Many catalytic processes are performed in reactors containing a series of separate catalytic beds. Reactors used in the chemical, petroleum refining, and other industries for passing liquids or mixed-phase liquid/gas mixtures over packed beds of particulate solids are employed for a variety of different processes. Examples of such processes include: catalytic dewaxing, hydrotreating, hydrodesulphurization, hydrofinishing, and hydrocracking. In these processes a liquid phase is typically mixed with a gas or vapor phase and the mixture passed over a particulate catalyst in a packed bed within a downflow reactor. 
     In downflow reactors, it is necessary that the gas and liquid are properly mixed and uniformly distributed across the horizontal cross section of the reactor prior to contacting each catalyst bed. Such uniform distribution of the gas and liquid provides major advantages, including: efficient utilization of catalyst, reduced catalyst top layer attrition, improved yields, improved product quality, and increased run lengths. Generally in a downflow catalytic reactor, a plurality of catalyst beds are arranged within the reactor, and a distributor system for the efficient mixing of gas and liquids is disposed above each catalyst bed. The region between catalyst beds is normally provided with a gas injection line to provide additional gas to compensate for gas consumed in the previous catalyst bed. The injected gas can also act as a quench gas for cooling the feed exiting a catalyst bed prior to the feed entering the next catalyst bed. Generally, the injected gas is hydrogen or comprises hydrogen. The liquid feed falling from the above-lying catalyst bed is allowed to accumulate on a collection tray. The quench gas and liquid then pass into a mixing chamber where a swirling movement of the liquid is provided. This enables good mixing of the liquid and thereby provides even temperature conditions of the liquid. Gas-liquid mixing also takes place inside the mixing chamber. 
     The fluid from the mixing chamber flows downward onto a deflector or impingement plate, whereby the flow is redirected onto a distributor tray having a large number of downflow openings for the passage of liquid. For cross-sectional liquid flow distribution, the downflow openings of conventional apparatus can comprise one or more conduits, or chimneys. The chimney is a cylindrical structure with an open top and one or more openings in the upper portion of its height through which a gas phase can enter. The gas phase travels downward through the length of the chimney. The lower portion of the chimney can have one or more lateral openings for liquid flow through which a liquid phase can enter the chimney and contact the gas phase. As liquid continues to accumulate on the distributor tray, the liquid will rise to a level that covers the lateral opening(s) in the chimney so that the passage of gas is precluded and so that the liquid can enter through the lateral opening(s) into the chimney. Gases and liquids egress via an opening in the bottom of the chimney, through the distributor tray, and onto an underlying catalyst bed. A disadvantage of conventional conduits or chimneys is that, due to the low turbulence around liquid streams, only limited mixing between the two phases will occur. 
     A good flow distribution device for a catalytic reactor should meet the following four basic requirements: provide even distribution of feed to a catalyst bed over a range of gas and liquid feed rates; be tolerant to certain out-of-levelness of the distribution tray; provide good gas-liquid mixing and heat exchange, and require minimum catalyst bed height to fully wet the underlying catalyst bed. Because conventional chimneys rely on the static liquid height on the tray as the driving force for liquid flow into the chimney, they are deficient in meeting these criteria due to poor tolerance for deviations from levelness of the distributor tray, as well as exhibiting suboptimal spray discharge of fluids onto the underlying catalyst bed, and other deficiencies. 
     One of the key considerations in flow distributor design is the discharge pattern of liquid and gas from the device. A conventional chimney distributor provides a limited number of points of contact of the liquid feed with the catalyst bed. As a result, a larger distance from the chimney to the bed is required to wet the catalyst surface. 
     U.S. Pat. No. 7,473,405 to Kemoun et al. discloses a nozzle device for coupling with a fluid distribution conduit. 
     There is a continuing need for hydroprocessing reactor apparatus providing improved hydrogen/oil mixing at the mixing tray, more uniform and consistent liquid distribution on the catalyst bed, a decreased mixing tray height, and decreased amounts of fabrication material, as well as easier maintenance, assembly and disassembly. There is also a need for systems and apparatus that provide improved tolerance for distributor tray out-of-levelness conditions. There is still a further need for fluid distribution apparatus that can provide more uniform distribution of liquid on a catalyst bed under liquid-only conditions. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention there is provided a reactor system comprising a reactor shell, a primary feed distribution unit disposed within the reactor shell, and at least one secondary feed distribution unit disposed beneath the primary feed distribution unit within the reactor shell. The primary feed distribution unit comprises a primary deflector plate and a first nozzle tray disposed beneath the deflector plate. The at least one secondary feed distribution unit comprises a collection tray and a second nozzle tray disposed beneath the collection tray. Each of the first nozzle tray and the second nozzle tray comprises a plurality of nozzles, the nozzles each comprise a nozzle body including a distal body portion having at least one liquid inlet configured for the passage of liquid therethrough. The distal body portion defines a substantially cylindrical distal void. Each liquid inlet is disposed tangentially to an inner surface of the distal body portion. 
     In an embodiment, the present invention also provides a reactor system comprising a reactor shell having an inner wall, a primary feed distribution unit disposed within the reactor shell, and at least one secondary feed distribution unit disposed beneath the primary feed distribution unit within the reactor shell. Each secondary feed distribution unit comprises a collection tray, a nozzle tray disposed beneath the collection tray, at least one support ring affixed to the reactor shell inner wall, and a plurality of trusses. Each truss spans the at least one support ring. Each truss has an upper flange and a lower flange, the upper flange supports the collection tray and the lower flange supports the nozzle tray. 
     In another embodiment of the present invention, there is provided a feed distribution unit for a catalytic reactor, the feed distribution unit comprising a deflector plate and a nozzle tray disposed beneath the deflector plate. The nozzle tray includes a plurality of nozzles. Each nozzle comprises a nozzle body including a distal body portion having at least one liquid inlet configured for the passage of liquid therethrough. The distal body portion defines a substantially cylindrical distal void. Each liquid inlet is disposed tangentially to an inner surface of the distal body portion. 
     In an embodiment, the present invention further provides a nozzle for the even distribution of a multi-phase fluid mixture, the nozzle comprising a nozzle body having a proximal body portion, an intermediate body portion, and a distal body portion. The proximal body portion defines a substantially cylindrical proximal void, and the proximal body portion has at least one gas inlet configured for the passage of gas therethrough into the proximal body portion. The intermediate body portion defines a substantially cylindrical intermediate void in fluid communication with the proximal void. The distal body portion has a body wall and at least one liquid inlet configured for the passage of liquid therethrough into the distal body portion. The distal body portion defines a substantially cylindrical distal void, and the at least one liquid inlet is disposed tangentially to an inner surface of the distal body portion. 
     In another embodiment of the present invention, there is provided a fluid distribution apparatus for a reactor, the apparatus comprising a nozzle tray; a plurality of chimneys affixed to, and extending through, the nozzle tray; and a fluid distribution nozzle disposed within each chimney. Each chimney has a chimney wall defining a substantially cylindrical void extending substantially vertically from a lower surface of the nozzle tray to a location above an upper surface of the nozzle tray. The chimney has an open proximal end and an open distal end, and the chimney wall has at least one lateral opening therein. The nozzle comprises a nozzle body comprising a proximal body portion, an intermediate body portion, and a distal body portion having a distal body wall. The proximal body portion defines a substantially cylindrical proximal void, and the open proximal end is configured for the passage of gas therethrough. The intermediate body portion defines a substantially cylindrical intermediate void in fluid communication with the proximal void. The distal body portion has a liquid inlet configured for the passage of liquid therethrough into the distal body portion. The distal body portion defines a substantially cylindrical distal void. The liquid inlet comprises a curved channel within the distal body wall, and the curved channel has an inner terminus disposed tangentially to an inner surface of the distal body portion. 
     In another embodiment, the present invention still further provides a fluid distribution device comprising a substantially cylindrical hollow nozzle body having a plurality of outer slots disposed circumferentially around the nozzle body; a cap affixed to a proximal portion of the nozzle body, the cap having an axial proximal opening therein; a base affixed to a distal portion of the nozzle body, the base having an axial distal opening therein; and a substantially cylindrical inner conduit disposed axially within a proximal portion of the nozzle body. The inner conduit is disposed within the proximal opening of the cap, and the inner conduit extends proximally from the cap to define a proximal end of the inner conduit. The inner conduit has a plurality of inner slots disposed circumferentially around the proximal end of the inner conduit. A distal end of the inner conduit extends distally to a location proximal to a distal end of each of the outer slots. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram schematically representing a reactor system, according to an embodiment of the present invention; 
         FIG. 2  is a block diagram schematically representing a catalytic unit for a reactor system, according to an embodiment of the present invention; 
         FIG. 3  is a block diagram schematically representing a reactor system, according to another embodiment of the present invention; 
         FIG. 4A  is a block diagram schematically representing a primary feed distribution unit, according to an embodiment of the present invention; 
         FIG. 4B  is a block diagram schematically representing a secondary feed distribution unit, according to an embodiment of the present invention; 
         FIG. 5A  shows a schematic cut-away view of a portion of a reactor shell with associated reactor internal apparatus, according to an embodiment of the present invention; 
         FIG. 5B  is a plan view of a feed distribution unit as seen along the lines  5 B- 5 B of  FIG. 5A  and showing a plurality of collection tray segments; 
         FIG. 5C  is a plan view of a portion of the feed distribution unit of  FIG. 5B  with the collection tray segments removed and showing a plurality of nozzle tray segments; 
         FIG. 5D  is a sectional view of a portion of the feed distribution unit of  FIG. 5B  as seen along the lines  5 D- 5 D of  FIG. 5B ; 
         FIG. 5E  is a side view of a truss bearing a plurality of nozzle tray segments, as seen along the lines  5 E- 5 E of  FIG. 5C ; 
         FIG. 6A  is a perspective view of a primary feed distribution unit showing a primary deflector plate in relation to a nozzle tray, according to an embodiment of the present invention; 
         FIG. 6B  is a perspective view of a mixing box in relation to a secondary deflector plate of a secondary feed distribution unit, according to an embodiment of the present invention; 
         FIG. 6C  is a schematic side view of a secondary feed distribution unit including a secondary deflector plate, according to an embodiment of the present invention; 
         FIG. 6D  is a schematic sectional side view of a secondary deflector plate in relation to a riser on a collection tray, according to an embodiment of the present invention; 
         FIG. 7A  is a schematic plan view of a mixing box, and  FIG. 7B  is a schematic plan view of the separated halves of the mixing box of  FIG. 7A , according to another embodiment of the present invention; 
         FIG. 7C  is a perspective view of one half of a mixing box disposed on a collection tray segment of a secondary feed distribution unit, according to another embodiment of the present invention; 
         FIG. 8  is a schematic plan view of a portion of a nozzle tray showing an array of fluid distribution nozzles, according to an embodiment of the present invention; 
         FIG. 9A  shows a fluid distribution nozzle as seen from the side, according to an embodiment of the present invention;  FIG. 9B  is a longitudinal sectional view of the nozzle as seen along the lines  9 B- 9 B of  FIG. 9A ; and  FIG. 9C  shows liquid inlets in the nozzle along the lines  9 C- 9 C of  FIG. 9A ; 
         FIG. 10  is a schematic plan view of a portion of a nozzle tray showing an array of fluid distribution chimneys, according to an embodiment of the present invention; 
         FIG. 11A  shows a fluid distribution nozzle as seen from the side;  FIG. 11B  is a longitudinal sectional view of the nozzle of  FIG. 11A  as seen along the lines  11 B- 11 B;  FIG. 11C  is a plan view of the nozzle of  FIG. 11A  along the lines  11 C- 11 C; and  FIG. 11D  shows a curved liquid inlet in the nozzle body along the lines  11 D- 11 D of  FIG. 11A , according to an embodiment of the present invention; 
         FIG. 12A  is a front view of a fluid distribution chimney;  FIG. 12B  is a side view of the chimney of  FIG. 12A ; and  FIG. 12C  is a longitudinal sectional view of the chimney of  FIG. 12A  showing the nozzle of  FIG. 11A  inserted therein, according to another embodiment of the present invention; 
         FIG. 13  is a schematic longitudinal sectional view of a fluid distribution nozzle, according to another embodiment of the present invention; 
         FIG. 14A  is a schematic cut-away side view of a portion of a reactor shell showing a catalyst support unit in relation to a feed distribution unit;  FIG. 14B  is a plan view of the catalyst support unit as seen along the lines  14 B- 14 B of  FIG. 14A  and showing a plurality of screen panels;  FIG. 14C  is a plan view of the catalyst support unit of  FIG. 14B  with the screen panels removed and showing a plurality of grid panels;  FIG. 14D  is a plan view of a portion of the catalyst support unit of  FIG. 14B  with the screen panels and grid panels removed and showing a plurality of catalyst support beams;  FIG. 14E  is a sectional view showing the catalyst support beams, grid panels and screen panels, as seen along the lines  14 E- 14 E of  FIG. 14B ; and  FIG. 14F  is a sectional view showing the catalyst support beams in relation to the reactor shell and shell ledge, as seen along the lines  14 F- 14 F of  FIG. 14D , according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides reactor internal apparatus for the even distribution of fluids for downflow multi-bed catalytic reactors. Such reactors may be used in the chemical and petroleum refining industries for effecting various reactions such as catalytic dewaxing, hydrotreating, hydrofinishing and hydrocracking. The present invention is particularly useful for effecting mixed-phase reactions between a liquid, such as a liquid hydrocarbon feed and a gas, such as hydrogen gas. More particularly, the invention relates to systems and apparatus for improving the mixing and distribution of gas and liquid phases above a bed of solid catalyst, while at the same time minimizing the height of the reactor internals. The instant invention is particularly useful for catalytic reactors in which gas-liquid mixtures are passed through a plurality of beds of solid catalyst particles in a broad range of processes, particularly for downflow catalytic reactors used for hydrotreating and hydrocracking in oil refining operations. 
     Unless otherwise specified, the recitation of a genus of elements, materials, or other components from which an individual or combination of components or structures can be selected is intended to include all possible sub-generic combinations of the listed components and mixtures thereof. Also, “include” and its variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that may also be useful in the materials, elements, structures, compositions, and methods of this invention. 
     With reference to the drawings,  FIG. 1  is a block diagram schematically representing a reactor system  10 , according to an embodiment of the present invention. Reactor system  10  may comprise a reactor shell  30  having reactor shell walls which may be at least substantially vertical. Reactor shell  30  may house at least one catalytic unit  100  (see, e.g.,  FIG. 2 ). In an embodiment, reactor system  10  may comprise a plurality of catalytic units, as represented in  FIG. 1  as a first (1 st ) catalytic unit  100   a  and an n th  catalytic unit  100   n . The number of catalytic units  100  within reactor shell  30  may typically be in the range from one (1) to about eight (8), e.g., n may be in the range from about two (2) to eight (8). 
       FIG. 2  is a block diagram schematically representing a catalytic unit  100  for a reactor system  10 , according to the present invention. In an embodiment, catalytic unit  100  may comprise a feed distribution unit  200 / 200 ′, a catalyst support unit  400 , and a catalyst bed  402 . The feed distribution unit may be a primary feed distribution unit  200 ′ (see, e.g.,  FIG. 4A ) or a secondary feed distribution unit  200  (see, e.g.,  FIG. 4B ). In an embodiment, feed distribution unit  200 / 200 ′ may be disposed above an associated catalyst bed  402 , and catalyst bed  402  may be supported on or by catalyst support unit  400 . In an embodiment, catalyst bed  402  may comprise a layer of solid catalyst. 
       FIG. 3  is a block diagram schematically representing a reactor system  10 , according to another embodiment of the present invention. Reactor system  10  may comprise a primary feed distribution unit  200 ′ and at least one secondary feed distribution unit  200 . In the embodiment of  FIG. 3 , reactor system  10  may comprise a first secondary feed distribution unit  200   a  and an n th  feed distribution unit  200   n . The number of secondary feed distribution unit s  200  within reactor shell  30  may typically be in the range from one (1) to about eight (8). The total number of primary and secondary feed distribution unit s  200 ′/ 200  within reactor shell  30  may correspond to the number of catalytic units  100  within reactor shell  30 . 
       FIG. 4A  is a block diagram schematically representing a primary feed distribution unit  200 ′, according to an embodiment of the present invention. Primary feed distribution unit  200 ′ may comprise a primary deflector plate  210  and a nozzle tray  260 . Primary deflector plate  210  may be disposed above nozzle tray  260 . Primary deflector plate  210  may have a plurality of perforations therein (see, for example,  FIG. 6A ). Primary deflector plate  210  may be configured for allowing the passage of fluid through primary deflector plate  210  to nozzle tray  260 . Nozzle tray  260  may include a plurality of fluid distribution nozzles  600  (see, for example,  FIG. 8 ). In an embodiment, primary deflector plate  210  may be supported on fluid distribution nozzles  600 . 
       FIG. 4B  is a block diagram schematically representing a secondary feed distribution unit  200 , according to an embodiment of the present invention. Secondary feed distribution unit  200  may comprise a mixing box  220 , a collection tray  240 , a secondary deflector plate  250  and a nozzle tray  260 . Mixing box  220  may be disposed on collection tray  240 . Secondary deflector plate  250  may be disposed beneath collection tray  240  and above nozzle tray  260 . Secondary deflector plate  250  may include a first peripheral portion and a second peripheral portion each having a plurality of perforations therethrough (see, for example,  FIG. 6B ). Secondary deflector plate  250  may further include a central entire portion lacking perforations therein (see, for example,  FIGS. 6B and 6D ). Nozzle tray  260  may include a plurality of fluid distribution nozzles (see, for example,  FIG. 8 ). In an embodiment, secondary deflector plate  250  may be supported on fluid distribution nozzles  600 . 
       FIG. 5A  shows a schematic cut-away view of a portion of a reactor  20  including a reactor shell  30  having shell walls  32 , according to an embodiment of the present invention. Reactor shell  30  may house a primary feed distribution unit  200 ′ and at least one secondary feed distribution unit  200 . A catalyst bed  402  may be disposed beneath each of primary feed distribution unit  200 ′ and secondary feed distribution unit(s)  200 . Each catalyst bed  402  may be disposed on a catalyst support unit  400  (see, for example,  FIGS. 14A-F ). Each of primary feed distribution unit  200 ′, secondary feed distribution unit(s)  200 , and catalyst support unit  400  may be supported by the walls  32  of reactor shell  30 . The shell walls  32  at the location of primary feed distribution unit  200 ′, secondary feed distribution unit(s)  200 , and catalyst support unit(s)  400  may be at least substantially vertical. Each of primary feed distribution unit  200 ′, secondary feed distribution unit(s)  200 , and catalyst support units  400  may be disposed at least substantially orthogonal to shell walls  32 . 
       FIG. 5B  is a plan view of a secondary feed distribution unit  200 , as seen along the lines  5 B- 5 B of  FIG. 5A . Secondary feed distribution unit  200  may include a plurality of collection tray segments  242 . Collection tray segments  242  jointly define collection tray  240  (see, for example,  FIG. 6C ). Collection tray segments  242  may be reversibly affixed to each other to allow for the convenient assembly and disassembly of collection tray  240 . In an embodiment, collection tray segments  242  may be affixed to each other via a plurality of pins, such as wedge pins (not shown). One collection tray segment  242  is shown in  FIG. 5B  as being removed to reveal a nozzle tray segment  262  (see, for example,  FIG. 5C ). It is to be understood that secondary feed distribution unit  200  is not limited to the configuration of collection tray segments  242  as shown in  FIG. 5B , but rather other numbers and configurations of collection tray segments  242  are also within the scope of the present invention. 
       FIG. 5C  is a plan view of a portion of the secondary feed distribution unit  200  of  FIG. 5B  with collection tray segments  242  removed. Secondary feed distribution unit  200  further comprises a plurality of nozzle tray segments  262 . Nozzle tray segments  262  jointly define nozzle tray  260  (see, for example,  FIGS. 8 and 10 ). In  FIG. 5C , one of the nozzle tray segments  242  is shown as being displaced. Each of collection tray segments  242  and nozzle tray segments  262  may be supported by a plurality of trusses  302  (see, for example,  FIG. 5D ). Trusses  302  may in turn be supported by a support ring  34 . Support ring  34  may be affixed to an inner surface  32   a  of shell wall  32 . In an embodiment, support ring  34  may comprise a plurality of brackets (not shown) configured for the attachment of trusses  302 . Each truss may span reactor shell  30 . Although two (2) trusses  302  are shown in  FIG. 5C , other numbers of trusses  302  are also within the scope of the present invention. Typically, the number of trusses  302  spanning reactor shell  32  may be in the range from one (1) to about six (6). 
     With further reference to  FIG. 5C , support ring  34  may be affixed, e.g., welded, to the inner surface  32   a  of reactor shell wall  32 , and support ring  34  may be disposed circumferentially thereon. In an embodiment, support ring  34  may comprise a metal skirt (not shown) having an upper shelf and a lower shelf, the upper and lower shelves configured for supporting collection tray  240  and nozzle tray  260 , respectively. In another embodiment, support ring  34  may comprise an upper ring and a lower ring coaxial with, and vertically spaced from, the upper ring (neither of the upper ring nor the lower ring are shown); wherein each of the upper ring and the lower ring may be affixed (e.g., welded) to the inner surface  32   a  of reactor shell wall  32 . 
     With still further reference to  FIG. 5C , nozzle tray segments  262  may be reversibly affixed to each other to allow for the convenient assembly and disassembly of nozzle tray  260 . In an embodiment, nozzle tray segments  262  may be affixed to each other via a plurality of pins, such as wedge pins (not shown). It is to be understood that secondary feed distribution unit  200  is not limited to the configuration of nozzle tray segments  262  as shown in  FIG. 5C , but rather other numbers and configurations of nozzle tray segments  262  are also within the scope of the present invention. 
       FIG. 5D  is a sectional view of a portion of secondary feed distribution unit  200  of  FIG. 5B , as seen along the lines  5 D- 5 D of  FIG. 5B , showing a pair of spaced apart trusses  302 . Each truss  302  may comprise an upper flange  304  and a lower flange  306 . A plurality of collection tray segments  242  may be disposed on, and supported by, upper flange  304 . A plurality of nozzle tray segments  262  may be disposed on, and supported by, lower flange  306 . 
       FIG. 5E  is a side view of a truss  302  bearing a plurality of nozzle tray segments  262  on truss lower flange  306 , as seen along the lines  5 E- 5 E of  FIG. 5C . In an embodiment, truss  302  may be supported at each end by a bracket (not shown) attached to support ring  34 . In  FIG. 5E , collection tray segments  242  are shown as being removed from truss  302 . 
       FIG. 6A  is a perspective view of a primary deflector plate  210  in relation to a nozzle tray  260  of a primary feed distribution unit  200 ′, according to an embodiment of the present invention. In an embodiment, primary deflector plate  210  may be at least substantially circular. Primary deflector plate  210  may typically have an area in the range from about 70% to 100% of the cross-sectional area of reactor shell  30 , and often from about 90% to 100% of the cross-sectional area of reactor shell  30 . Typically, nozzle tray  260  may have an area in the range from about 95% to 100% of the cross-sectional area of reactor shell  30 . Nozzles  600  (see, e.g.,  FIGS. 9A-C ) are omitted from  FIG. 6A  for the sake of clarity of illustration. Both nozzle tray  260  and primary deflector plate  210  may be disposed at least substantially orthogonal to reactor shell wall  32 . 
       FIG. 6B  is a perspective view of a mixing box  220  in relation to a secondary deflector plate  250  of a secondary feed distribution unit  200 , according to an embodiment of the present invention. Collection tray  240  is omitted from  FIG. 6B  for the sake of clarity of illustration. Secondary deflector plate  250  may be disposed beneath mixing box  220 . Secondary deflector plate  250  may include a first peripheral portion  254   a , a second peripheral portion  254   b , and a central entire portion  252 . Each of first peripheral portion  254   a  and second peripheral portion  254   b  may have a plurality of perforations  256  therethrough. In contrast, central entire portion  252  may at least substantially lack perforations, holes or voids therein. Secondary deflector plate  250  may be configured for the passage of liquid through perforations  256 . 
       FIG. 6C  is a schematic side view of a secondary feed distribution unit  200 , according to an embodiment of the present invention. Secondary feed distribution unit  200  may include a collection tray  240  having an upper surface  240   a , a mixing box  220  disposed on upper surface  240   a , a secondary deflector plate  250  disposed beneath collection tray  240 , and a nozzle tray  260  disposed beneath secondary deflector plate  250 . Secondary feed distribution unit  200  may further include a riser  244 . Riser  244  may be at least substantially cylindrical and affixed to upper surface  240   a  of collection tray  240 . Riser  244  may extend at least substantially orthogonal to collection tray  240 . 
       FIG. 6D  is a schematic sectional side view of a secondary deflector plate  250  in relation to a riser  244  on a collection tray  240 , according to an embodiment of the present invention. Secondary deflector plate  250  comprises central entire portion  252  having an entire surface and lacking any perforations, holes, or voids therein. Central entire portion  252  may be disposed between first and second peripheral portions  254   a ,  254   b  of secondary deflector plate  250 . In an embodiment, central entire portion  252  may occupy an area greater than a cross-sectional area of riser  244 . In a sub-embodiment, the area of central entire portion  252  may be delineated by the base of a frusto-conical volume defined by a straight line extending at an angle, θ from collection tray  240  at the location of the inner wall of riser  244  to secondary deflector plate  250 . Typically, θ may be in the range from about 20° to 70°, usually from about 30° to 60°, and often from about 40° to 50°. The vertical clearance, C H  between secondary deflector plate  250  and collection tray  240  may be typically in the range from about 25% to 50% of the diameter of riser  244 . In another sub-embodiment, central entire portion  252  may occupy an area about twice (2×) to five times (5×) the cross-sectional area of riser  244 . 
       FIG. 7A  is a schematic plan view of a mixing box  220 , and  FIG. 7B  is a schematic plan view of the separated halves of mixing box  220  of  FIG. 7A , according to an embodiment of the present invention. Mixing box  220  may comprise a first half  220   a  and a second half  220   b . First and second mixing box halves  220   a ,  220   b  may each include a coupling flange  222  for joining or coupling first and second halves  220   a ,  220   b  together. In an embodiment, first and second halves  220   a ,  220   b  may be reversibly affixed to each other at their coupling flanges  222  via a plurality of pins, such as wedge pins (not shown). 
       FIG. 7C  is a perspective view of one half of a mixing box  220  disposed on a collection tray segment  242 , according to another embodiment of the present invention. A riser  244  may be disposed on collection tray segment  242  beneath mixing box  220 . Riser  244  may be disposed above secondary deflector plate  250 . Riser  244  may include at least one baffle (not shown) disposed on an inner surface of riser  244 . Only one collection tray segment  242  is shown in  FIG. 7C . In practice, a plurality of collection tray segments  242  jointly form collection tray  240 . 
       FIG. 8  is a schematic plan view of a portion of a nozzle tray  260  including an array of fluid distribution nozzles  600 , according to an embodiment of the present invention. Each nozzle  600  may be configured for the mixing and even distribution of fluid to a catalyst bed  402  disposed beneath nozzle tray  260 . The array of nozzles  600  on nozzle tray  260  may have a triangular pitch with a nozzle spacing typically in the range from about 5 to 10 inches, and often in the range from about 6 to 8 inches.  FIG. 8  represents only a portion of nozzle tray  260 ; in practice nozzle tray  260  may include many more nozzles  600 . 
     With reference to  FIGS. 9A-9C ,  FIG. 9A  shows a fluid distribution nozzle  600  as seen from the side, according to an embodiment of the present invention.  FIG. 9B  is a longitudinal sectional view of nozzle  600  as seen along the lines  9 B- 9 B of  FIG. 9A .  FIG. 9C  shows liquid inlets  614  in nozzle  600  as seen along the lines  9 C- 9 C of  FIG. 9A . Nozzle  600  may comprise a nozzle body  602 , a nozzle proximal end  600   a , a nozzle distal end  600   b , a plurality of gas inlets  612 , and at least one liquid inlet  614 . Nozzle proximal end  600   a  may be sealed with a nozzle cap  604 . In an embodiment, cap  604  may be integral, e.g., cast, with nozzle body  602 . 
     With reference to  FIG. 9B , nozzle body  602  may comprise a proximal body portion  602   a , an intermediate body portion  602   b , and a distal body portion  602   c.    
     Proximal body portion  602   a  defines a substantially cylindrical proximal void. Intermediate body portion  602   b  defines a substantially cylindrical intermediate void in fluid communication with the proximal void. Distal body portion  602   c  defines a substantially cylindrical distal void in fluid communication with the intermediate void. The proximal void may have a first diameter, the intermediate void may have a second diameter, and the distal void may have a third diameter. The first diameter may be substantially greater than the third diameter, and the third diameter may be substantially greater than the second diameter. 
     Each gas inlet  612  may be disposed laterally at proximal body portion  602   a . Each gas inlet  612  may be configured for the passage of gas therethrough into proximal body portion  602   a . Nozzle  600  may further comprise a gas nozzle  606 . Gas nozzle  606  may be disposed substantially orthogonal to the walls of nozzle body  602  between proximal body portion  602   a  and distal body portion  602   c  to define intermediate body portion  602   b . In an embodiment, gas nozzle  606  may be integral with nozzle body  602 . In another embodiment, gas nozzle  606  may comprise a metal ring disposed within and affixed to nozzle body  602 . 
     Each liquid inlet  614  may be disposed laterally at distal body portion  602   c.    
     Each liquid inlet  614  may be configured for the passage of liquid therethrough. As can be seen, for example in  FIG. 9C , each liquid inlet  614  may be disposed tangentially to an inner surface  616  of distal body portion  602   c . In an embodiment, each liquid inlet  614  may be linear. 
     With further reference to  FIG. 9C , each liquid inlet  614  may have a liquid inlet length, I L , and a liquid inlet width, I W . In an embodiment, a ratio (I L :I W ) of liquid inlet length, I L  to liquid inlet width, I W  may be in the range from about 2:1 to 5:1. The liquid inlet length, I L  shown in  FIG. 9C  may represent a minimum length of each liquid inlet  614 , e.g., due to the tangential orientation of liquid inlets  614  with respect to nozzle body  602 . 
     Each of liquid inlets  614  may be configured for forming a film of liquid on inner surface  616  of distal body portion  602   c , and each of liquid inlets  614  may be configured for promoting the spiral flow of liquid on inner surface  616  of distal body portion  602   c , wherein the flow of liquid is in a direction distal to liquid inlets  614 . 
     Nozzle  600  may further comprise a converging first frusto-conical portion  608  in fluid communication with distal body portion  602   c . Nozzle  600  may still further comprise a diverging second frusto-conical portion  610  distal to, and in fluid communication with, first frusto-conical portion  608 . Nozzle  600  may still further comprise a plurality of indentations  620  located at distal end  600   b  of nozzle  600 . Indentations  620  may be configured to further promote the dispersion of fluid emanating from nozzle distal end  600   b  as an evenly dispersed spray, e.g., having a conical spray pattern. 
       FIG. 10  is a schematic plan view of a nozzle tray  260  including an array of fluid distribution chimneys  700 , according to an embodiment of the present invention. Each chimney  700  may be fitted, e.g., retrofitted, with a fluid distribution nozzle  600 ′ (see, for example,  FIGS. 11A-D , and  12 A-C) for the efficient mixing and even distribution of fluid to a catalyst bed  402  disposed beneath nozzle tray  260 . The array of chimneys  700 , and their associated nozzles  600 ′, arranged on nozzle tray  260  may have a triangular pitch with a chimney  700 /nozzle  600 ′ spacing typically in the range from about 5 to 10 inches, and often in the range from about 6 to 8 inches.  FIG. 10  represents only a portion of nozzle tray  260 ; in practice nozzle tray  260  may include many more chimneys  700 . 
       FIG. 11A  shows a fluid distribution nozzle  600 ′ as seen from the side, according to an embodiment of the present invention.  FIG. 11B  is a longitudinal sectional view of nozzle  600 ′ of  FIG. 11A  as seen along the lines  11 B- 11 B,  FIG. 11C  is a plan view of nozzle  600 ′ of  FIG. 11A  along the lines  11 B- 11 B.  FIG. 11D  shows a liquid inlet  614 ′ in the nozzle body along the lines  11 D- 11 D of  FIG. 11A . Nozzle  600 ′ may comprise a nozzle body  602 , a nozzle proximal end  600 ′ a , a nozzle distal end  600 ′ b , a gas inlet  612 ′, and at least one liquid inlet  614 ′. Nozzle  600 ′ may be sized and configured for insertion in a fluid distribution chimney, for example chimney  700 , during retrofitting an existing, conventional fluid distribution tray to provide a highly efficient nozzle tray for a hydroprocessing reactor, according to an embodiment of the instant invention (see, e.g.,  FIGS. 12A-C ). 
     With reference to  FIG. 11B , nozzle body  602  may comprise a proximal body portion  602   a , an intermediate body portion  602   b , and a distal body portion  602   c.    
     Proximal body portion  602   a  defines a substantially cylindrical proximal void. Intermediate body portion  602   b  defines a substantially cylindrical intermediate void in fluid communication with the proximal void. Distal body portion  602   c  defines a substantially cylindrical distal void in fluid communication with the intermediate void. The proximal void may have a first diameter, the intermediate void may have a second diameter, and the distal void may have a third diameter. The first diameter may be substantially greater than the third diameter, and the third diameter may be substantially greater than the second diameter. 
     In an embodiment, gas inlet  612 ′ may comprise a proximal axial opening in nozzle body  602 . Gas inlet  612 ′ may be configured for the passage of gas therethrough into proximal body portion  602   a . Nozzle  600 ′ may further comprise a gas nozzle  606 . Gas nozzle  606  may be disposed substantially orthogonal to the walls of nozzle body  602  between proximal body portion  602   a  and distal body portion  602   c  to define intermediate body portion  602   b . Nozzle  600 ′ may further comprise a converging first frusto-conical portion  608  in fluid communication with distal body portion  602   c . Nozzle  600  may further comprise a diverging second frusto-conical portion  610  distal to, and in fluid communication with, first frusto-conical portion  608 . 
       FIG. 11C  is a plan view of nozzle  600 ′ of  FIG. 11A , as seen along the lines  11 C- 11 C, showing gas nozzle  606  within nozzle body  602 . In an embodiment, gas nozzle  606  may be integral with the nozzle body. In another embodiment, gas nozzle  606  may comprise a metal ring disposed within and affixed to nozzle body  602 . Gas nozzle  606  may be disposed concentrically with nozzle body  602 . 
       FIG. 11D  shows a liquid inlet  614 ′ in nozzle body  602 . Liquid inlet  614 ′ may be disposed laterally at distal body portion  602   c . Liquid inlet  614 ′ may be configured for the passage of liquid therethrough into distal body portion  602   c . In an embodiment, liquid inlet  614 ′ may comprise a curved channel  615  disposed within the wall of nozzle body  602 . As can be seen, for example in  FIG. 11D , an inner terminus of curved channel  615  may be disposed tangentially to an inner surface  616  of distal body portion  602   c . In an embodiment, curved channel  615  may subtend an angle, α in the range from about 60° to 180°, typically from about 70° to 170°, and often from about 80° to 160°. In an embodiment, curved channel  615  may have a substantially rectangular cross-sectional shape. 
     Liquid inlet  614 ′ may be configured for forming a film of liquid on inner surface  616  of distal body portion  602   c , and liquid inlet  614 ′ may be configured for promoting the spiral flow of liquid on inner surface  616  of distal body portion  602   c , wherein the flow of liquid is in a direction distal to liquid inlet  614 ′. 
     Nozzle  600 ′ may still further comprise a plurality of indentations  620  located at distal end  600   b  of nozzle  600 ′. Indentations  620  may be configured to promote the dispersion of fluid emanating from nozzle distal end  600   b  as an evenly dispersed spray, e.g., having a conical spray pattern. 
       FIG. 12A  is a front view of a fluid distribution chimney  700 ,  FIG. 12B  is a side view of the chimney of  FIG. 12A , and  FIG. 12C  is a longitudinal sectional view of the chimney of  FIG. 12A  with the nozzle of  FIG. 11A  inserted therein, according to another embodiment of the present invention. Chimney  700  may comprise a chimney wall  702 , a chimney proximal end  700   a , and a chimney distal end  700   b . Chimney wall  702  may define a substantially cylindrical void therein. Chimney  700  may be affixed to a nozzle tray  260  at chimney distal end  700   b . Chimney wall  702  may include a plurality of lateral holes  704 / 704 ′ therein. In an embodiment, nozzle  600 ′ may be inserted within chimney  700  such that nozzle distal end  600 ′ b  protrudes distally beyond a lower surface  260   b  of nozzle tray  260 . Nozzle  600 ′ may be configured for alignment of liquid inlet  614 ′ with at least one lateral hole  704 . When inserted in chimney  700 , nozzle  600 ′ may occlude and at least partially seal lateral holes  704 ′. 
       FIG. 12C  is a longitudinal sectional view of chimney  700  having nozzle  600 ′ ( FIG. 11A ) inserted therein. Chimney wall  702  may be affixed, e.g., welded, to nozzle tray  260 , and nozzle  600 ′ may be affixed, e.g., welded, to chimney wall  702 . Features and elements of nozzle  600 ′ are described hereinabove, for example, with reference to  FIGS. 11A-D . Nozzle  600 ′ when inserted within chimney wall  702  may serve to evenly mix and distribute fluids, e.g., a mixture of liquid feed and hydrogen gas, to a catalyst bed in a reactor for petroleum refinery hydroprocessing reactions. 
       FIG. 13  is a schematic longitudinal sectional view of a fluid distribution nozzle  800 , according to another embodiment of the present invention. Nozzle  800  may comprise a substantially cylindrical hollow nozzle body  802  having a proximal portion  802   a  and a distal portion  802   b , a cap  804  affixed to proximal portion  802   a , a base  808  affixed to distal portion  802   b , and a substantially cylindrical inner conduit  806  disposed axially within proximal portion  802   a.    
     Cap  804  may have an axial proximal opening  805  therein, and inner conduit  806  may be disposed within proximal opening  805 . Inner conduit  806  may extend proximally beyond cap  804  to define a proximal end  806   a  of inner conduit  806 . Nozzle body  802  may have a plurality of outer slots  814  disposed circumferentially around nozzle body  802 . A distal end  806   b  of inner conduit  806  may terminate distally at a location proximal to a distal end  814   b  of each of outer slots  814 . 
     Each of cap  804  and base  808  may be at least substantially dome-shaped, wherein cap  804  tapers distally from narrow to broad, and base  808  tapers distally from broad to narrow. Each of cap  804  and base  808  may be threaded. Cap  804  may be sealingly engaged with nozzle body  802  via threads on proximal portion  802   a . Base  808  may be sealingly engaged with nozzle body  802  via threads on distal portion  802   b . Base  808  may have an axial distal opening  810  configured for the passage and distribution of fluid therethrough. 
     Inner conduit  806  may be sealingly engaged with cap  804  and disposed substantially concentrically with nozzle body  802 . Nozzle body  802  and inner conduit  806  may jointly define a void within nozzle  800 , wherein the void may comprise an annular proximal void  803   a  and a substantially cylindrical distal void  803   b . Inner conduit  806  may have a plurality of inner slots  812  disposed circumferentially around proximal end  806   a . The configuration of inner slots  812  and outer slots  814  may be at least to some extent a matter of design choice for the skilled artisan. 
     Each of inner slots  812  may be in fluid communication with the void via inner conduit  806 . Inner conduit  806  may be configured for the passage of gas therethrough from inner slots  812  to distal void  803   b . Nozzle  800  may be configured for the passage of liquid through outer slots  814  to distal void  803   b  within nozzle body  802 . Axial distal opening  810  may be frusto-conical and taper distally from narrow to broad. Nozzle  800  may be affixed to a nozzle tray  260 , e.g., at distal portion  802   b.    
     In an embodiment, fluid distribution nozzle  800  may provide an efficient fluid mixing and distribution nozzle for a nozzle tray of a reactor, wherein nozzle  800  may be easily and inexpensively assembled using off-the-shelf pipe parts. In an embodiment, components of nozzle  800 , e.g., nozzle body  802 , cap  804  and base  808 , may be constructed from threaded, standard stainless steel pipe, e.g., having National Pipe Thread (NPT) threads according to ANSI/ASME standard B1.20.1. 
       FIG. 14A  is a schematic cut-away side view showing a portion of a reactor  20 , according to another embodiment of the present invention. Reactor  20  may house a primary feed distribution unit  200 ′, a secondary feed distribution unit  200 , and a catalyst support unit  400 . Primary feed distribution unit  200 ′ and secondary feed distribution unit  200  may each comprise elements, features, and characteristics as described hereinabove, e.g., with reference to  FIGS. 4A-13 . 
     Reactor  20  may comprise a reactor shell  30 . At least a portion of reactor shell  30  may have substantially vertical shell walls  32 . Each of catalyst support unit  400 , primary feed distribution unit  200 ′, and secondary feed distribution unit  200  may be disposed at least substantially horizontally and orthogonal to the walls of reactor shell  30 . Only two catalyst support units  400 , one primary feed distribution unit  200 ′, and one secondary feed distribution unit  200  are shown in  FIG. 14A . In an embodiment, reactor  20  may house a plurality of secondary feed distribution units  200 . Each secondary feed distribution unit  200  may have a corresponding catalyst support unit  400  for supporting a catalyst bed  402  disposed beneath each secondary feed distribution unit  200  (see, for example,  FIG. 5A ). Each catalyst support unit  400  may comprise a plurality of catalyst support beams  406 , a plurality of screen panels  408 , and a plurality of grid panels  410 . Catalyst beds  402  are omitted from  FIGS. 14A-F  for the sake of clarity of illustration. 
       FIG. 14B  is a plan view of reactor shell  30 , as seen along the lines  14 B- 14 B of  FIG. 14A , and shows components of catalyst support unit  400  including a plurality of catalyst support beams  406  and a plurality of screen panels  408 . Each of catalyst support beams  406  may span reactor shell  30 . Screen panels  408  may jointly define a catalyst screen which may occupy at least substantially 100% of the cross-sectional area of reactor shell  30 . With further reference to  FIG. 14B , one screen panel  408  is shown as being displaced to reveal a grid panel  410 . 
       FIG. 14C  is a plan view of the catalyst support unit  400  of  FIG. 14B  with all screen panels  408  removed and showing a plurality of grid panels  410 . Grid panels  410  may be supported by catalyst support beams  406 . Screen panels  408  may in turn be supported by grid panels  410 . Peripherally located grid panels  410  having an arcuate outer edge may be jointly supported by catalyst support beam  406  and a circumferential shell ledge  404 . Each catalyst support beam  406  may comprise a pair of lateral support bars  414  (see, for example,  FIG. 14E ). Three grid panels are shown in  FIG. 14C  as being removed to reveal portions of shell ledge  404  and support bars  414 . 
     With further reference to  FIGS. 14B and 14C , it is to be understood that catalyst support unit  400  is not limited to the configuration of grid panels  410  and screen panels  408  as shown in  FIGS. 14B and 14C , but rather other numbers and configurations of both grid panels  410  and screen panels  408  are also within the scope of the present invention. In an embodiment, components of catalyst support unit  400  may be readily assembled and disassembled. In a sub-embodiment, components of catalyst support unit  400  may be affixed to each other via a plurality of pins, e.g., wedge pins (not shown). 
       FIG. 14D  is a plan view of a portion of catalyst support unit  400  with both screen panels  408  and grid panels  410  removed to more fully reveal catalyst support beams  406  and shell ledge  404 . In an embodiment, shell ledge  404  may comprise weld build-up material on an inner surface  32   a  of shell walls  32 . Although  FIG. 14D  shows two catalyst support beams  406 , the invention is by no means limited to two such beams per catalyst support unit  400 . In an embodiment, each catalyst support unit  400  may typically comprise from about two (2) to six (6) catalyst support beams  406 . 
       FIG. 14E  is a sectional view showing the catalyst support beams  406 , grid panels  410 , and screen panels  408 , as seen along the lines  14 E- 14 E of  FIG. 14B ; and  FIG. 14F  is a sectional view showing a catalyst support beam  406  in relation to the reactor shell wall  32  and shell ledge  404 , as seen along the lines  14 F- 14 F of  FIG. 14D . As noted hereinabove, catalyst support beams  406  may each comprise a pair of lateral support bars  414 . Support bars  414  may be configured for supporting at least a portion of each grid panel  410 . The plurality of grid panel  410  may in turn jointly support the plurality of screen panels  408 . The plurality of screen panels  408  may jointly form a screen configured for spanning substantially the entire cross-sectional area of reactor shell  30 , and the plurality of screen panels  408  may be jointly configured for supporting a catalyst bed  402  (see, e.g.,  FIG. 5A ). Each catalyst bed  402  may comprise a layer of particulate solid catalyst, as is well known to the skilled artisan. 
     Numerous variations of the present invention may be possible in light of the teachings and examples herein. It is therefore understood that within the scope of the following claims, the invention may be practiced otherwise than as specifically described or exemplified herein.