Abstract:
An apparatus comprising a reactor inlet distributor and a perforated deflector. In this apparatus the relationship between the diameter of the perforated deflector (D D ), the height of the opening of the inlet distributor pipe of the reactor inlet distributor (H SLOT ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   D   =OD   DP +2( xH   SLOT )
       wherein x is at least ½.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a non-provisional application which claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/604,332 filed Feb. 28, 2012, entitled “Apparatus for Modifying Flow of a Reactor Distributor Inlet,” which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     An apparatus for uniformly distributing vapor in a reactor inlet distributor. 
     BACKGROUND OF THE INVENTION 
     Radial flow reactors are widely used to contact fluid reactants that are typically vapor with particulate catalyst. Radial flow reactors typically include a cylindrical vessel with a main inlet duct (inlet distributor) at one end and an annular chamber or series of chambers (scallops) arranged annularly around the interior periphery of the vessel for distributing reactants to an annular catalyst bed disposed inwardly of the scallops. A central outlet pipe (center-pipe) is disposed inwardly of the annular catalyst bed and is connected to a reactor outlet for the exit of product from the reactor. The scallops and the outlet center-pipe are permeable to fluid flow but impermeable to catalyst flow to contain the catalyst bed therebetween. 
     Examples of processes carried out in such an apparatus include various hydroprocessing techniques such as catalytic reforming, hydrotreating, dehydrogenation, dehydrocyclodimerization and isomerization. Additionally, radial flow reactors can be used in continuous-catalyst-regeneration reactor systems. 
     As mentioned above, a known type of radial reactor includes a series of scallops arranged concentrically around an outer periphery of the bed of catalyst. Each scallop is open at the top to allow vapor from the reactor head space to travel down the scallop. The top (open end) of the scallop typically protrudes above a cover deck that prevents downward vapor flow through the top section of the catalyst bed. The desired flow pattern is an equal amount of vapor going down each scallop arranged around the periphery of the reactor vessel. The vapor would then flow out of the scallops, through the catalyst and into the center-pipe. The scallops are formed by connecting multiple scallop members together into one long scallop chamber. A radially-inward face of each scallop is constructed of a screen or perforated plate to permit fluid flow from the scallop radially inwardly to the bed of catalyst. A center-pipe is constructed of a plurality of parallel wires or screen mesh covering a perforated pipe so as to permit the passage of vapor and prevent individual catalyst particles from passing through the screen. 
     However, these conventional scallops and center-pipes may cause or fail to correct the non-uniform distribution of vapor through the catalyst. A properly designed reactor inlet distributor is required to direct vapor toward the scallops within the headspace of the radial flow reactor. The non-uniform distribution of vapor could have detrimental effects on the reactor performance through the non-uniform utilization of catalyst and large variation in the force exerted by the vapor on the coverdeck or other internals. The non-uniform distribution of vapor in the reactor can negatively impact the yield of products from the reactor and reduce the efficiency or yield of the reactor; therefore, a need exists for a modified reactor inlet distributor to cause the flow to be more uniformly distributed within the head space of the reactor. Reactor inlet distributors can be made from materials commercially available; however, the specific design of these inlet distributors has a significant impact on the flow of vapors within the reactors head space. 
     SUMMARY OF THE INVENTION 
     An apparatus comprising a reactor inlet distributor and a perforated deflector. In this apparatus the relationship between the diameter of the perforated deflector (D D ), the height of the opening of the inlet distributor pipe of the reactor inlet distributor (H SLOT ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   D   =OD   DP +2( xH   SLOT )
 
     wherein x is at least ½. 
     In another embodiment the apparatus comprises a reactor inlet distributor and a perforated deflector. In this embodiment the relationship between the diameter of the perforated deflector (D D ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   H   =N (½( D   D   −OD   DP ))
 
     wherein N is any number between 0 and 1. 
     In yet another embodiment the apparatus comprises a reactor inlet distributor and a perforated deflector. In this embodiment the relationship between the height of the perforated deflector (D H ), the diameter of the perforated deflector (D D ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   H   =N (½( D   D   −OD   DP ))
 
     wherein N is any number between 0 and 1. 
     In one embodiment the apparatus comprises a reactor inlet distributor and a perforated deflector. In this embodiment the dimensional relationship between the perforated deflector and the reactor inlet distributor is selected from at least one of the following three relationships:
         a) wherein the relationship between the height of the perforated deflector (D H ), the diameter of the perforated deflector (D D ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   H   =N (½( D   D   −OD   DP ))
   wherein N is any number between 0 and 1;   b) wherein the relationship between the diameter of the perforated deflector (D D ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   H   =N (½( D   D   −OD   DP ))
   wherein N is any number between 0 and 1; and   c) wherein the relationship between the diameter of the perforated deflector (D D ), the height of the opening of the inlet distributor pipe of the reactor inlet distributor (H SLOT ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   D   =OD   DP +2( xH   SLOT )
       

     wherein x is at least ½. 
     In yet another embodiment the apparatus comprises a reactor inlet distributor and a perforated deflector. In this embodiment the relationship between the height of the perforated conical deflector (D H ), the diameter of the perforated conical deflector (D D ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   H   =N (½( D   D   −OD   DP ))
 
     wherein N is any number between 0 and 1. 
     Additionally, the relationship between the diameter of the perforated conical deflector (D D ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   H   =N (½( D   D   −OD   DP ))
 
     wherein N is any number between 0 and 1 
     Finally, the relationship between the diameter of the perforated conical deflector (D D ), the height of the opening of the inlet distributor pipe of the reactor inlet distributor (H SLOT ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   D   =OD   DP +2( xH   SLOT )
 
     wherein x is at least ½. 
     The current embodiments also disclose a method of providing uniform distribution of vapor though the catalyst of a reactor inlet distributor through use of a perforated deflector. In this method the dimensional relationship between the perforated deflector and the reactor inlet distributor is selected from at least one of the following three relationships:
         a) wherein the relationship between the height of the perforated deflector (D H ), the diameter of the perforated deflector (D D ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   H   =N (½( D   D   −OD   DP ))
       

     wherein N is any number between 0 and 1;
         b) wherein the relationship between the diameter of the perforated deflector (D D ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   H   =N (½( D   D   −OD   DP ))
       

     wherein N is any number between 0 and 1; and
         c) wherein the relationship between the diameter of the perforated deflector (D D ), the height of the opening of the inlet distributor pipe of the reactor inlet distributor (H SLOT ) and the outer diameter of the inlet distributor pipe (OD DP ) is:
 
 D   D   =OD   DP +2( xH   SLOT )
       

     wherein x is at least ½. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention, together with further advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a generic schematic of one type of radial flow reactor. 
         FIG. 2  is an inlet distributor nozzle with a porous deflector plate design attached to the inlet pipe. 
         FIG. 3  is an inlet distributor nozzle with a porous deflector plate design resting on the reactor inlet flange. 
         FIG. 4  is a porous deflector plate attached to the cover-deck where no inlet distributor nozzle is present. 
         FIG. 5  is a porous deflector plate attached to, but raised up off the cover-deck where no inlet distributor nozzle is present. 
         FIG. 6  is an inlet distributor nozzle with a porous deflector made of expanded metal screen wrapped around the nozzle. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, not as a limitation of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations that come within the scope of the appended claims and their equivalents. 
     Now referring to the drawings, wherein like numerals designate like components,  FIG. 1  illustrates an embodiment of a generic radial flow reactor. The radial flow reactor  10  is operated to treat or react vapor across a bed of catalyst. Although the radial flow reactor depicted in  FIG. 1  is a fixed-bed reactor, the apparatus and method can be applied to any type of radial-reactor bed such as a continuously or periodically moving reactor bed. 
     As illustrated in  FIG. 1 , the radial flow reactor can include a reactor vessel  10  having a wall which is cylindrical in shape. This particular reactor vessel includes a reactor inlet  11  (otherwise known as a top head) having a reactor inlet flange  12  and duct  13 . Vapor to be treated is introduced from an inlet pipe (not shown) through the reactor inlet  11  into a reactor inlet distributor nozzle  20 . The inlet distributor nozzles  20  used may be of varying design and typically have slots or openings of varying sizes. Vapor flows from the reactor inlet distributor nozzle  20  through the inlet distributor slot  21  into the reactor head space  70 . The inlet distributor nozzle  20  may be attached in a variety of ways. Examples of different ways the inlet distributor nozzle  20  can be attached to the inlet pipe (not shown) include welding or by an inlet distributor flange support  22  which rests on the reactor inlet flange  12 . The reactor cover deck  30  prevents vapor from flowing downward through the catalyst  60  and helps direct vapor flow toward the scallop openings  43 . The scallops are arranged around the periphery of the interior of the reactor vessel  10 ; each sits on a scallop support ring  17 . Each scallop has a top section with a solid front  42  and a main scallop body  40  with a perforated front  41 . The scallop perforations are aligned with perforations in the center-pipe  50  to promote even vapor flow from the scallop body  40  to the center-pipe  50 . In this particular embodiment the center-pipe  50  is disposed along a central axis of the reactor vessel  10 . The annular space between the scallop body  40  and center-pipe  50  is filled with catalyst  60 . Sitting on bottom inert support material  61  and covered with a layer of top inert support material  62 . In one embodiment the center-pipe  50  is a perforated pipe covered by a center-pipe screen  51 . The center-pipe screen  51  prevents catalyst migration into the center-pipe  50 , while the perforated center-pipe controls the vapor flow evenly across the catalyst  60 . The top of the center-pipe  52  is covered to prevent vapor and catalyst from entering the center-pipe  50 . The bottom of the center-pipe  53  is connected with the reactor-outlet duct  16  in the bottom of the radial-flow reactor  10 . The reactor outlet duct  16  is connected to the reactor outlet flange  15  which together make up the reactor outlet  14 . During operation vapor flows from the bottom of the center-pipe  53  into the reactor outlet  14  and into the outlet pipe (not shown). 
     Still referring to  FIG. 1 , it will be generally understood that vapor follows a general path indicated by the arrows, entering from an inlet pipe (not shown) into the reactor  10  at the main inlet  11 , through the inlet distributor nozzle  20  into the reactor head space  70 , down the scallops  40 , through the catalyst bed  60  into the center pipe  50 , through the reactor outlet  14  into the outlet pipe (not shown). 
     As previously discussed, a conventional reactor inlet distributor may cause or fail to correct the non-uniform distribution of vapor entering the headspace of the radial flow reactor, which can have detrimental effects on the reactor performance. Retrofitting an existing reactor inlet distributor nozzle  20  or redesigning it with a porous deflector improves the radial flow reactor  10  performance, resulting in more uniformly distributed flow to the reactor catalyst  60 . A porous deflector can be connected to an inlet distributor nozzle  20  so as to modify the fluid flow through the distributor and within the head space  70  of the reactor by causing a change in the direction of the vapor flow exiting the distributor. The perforated deflector can be manufactured from the same material used in the existing inlet distributor. The shape of the perforated deflector can be any shape that can deflect the vapor inside the radial flow reactor including a conical or flat shaped perforated deflector. 
     The porous deflector reduces the likelihood of damage to the cover deck  30  in high space velocity reactors. Redesigning the reactor inlet distributor  20  may be necessary to allow the porous deflector to fit through the reactor inlet duct  13 . In radial-flow reactor  10  designs where an inlet distributor is absent, the deflector plate may be attached to the cover deck  30  or raised up off the cover deck. 
     In  FIG. 2 , the porous deflector is a perforated conical deflector attached to the bottom of the inlet distributor nozzle  20  which is attached to the inlet pipe (not shown). The perforated conical deflector  201  has a smaller diameter than the reactor inlet duct  13  but is wider that the inlet distributor nozzle  20 . The porosity of the perforated conical deflector plate  201  is made using circular perforations or rectangular slots that are arranged to maintain a symmetric vapor flow pattern around the perforated conical deflector plate  201 . The size and density of the perforations may be varied to adjust pressure drop. In one embodiment the size of the perforations in the perforated deflector can be from ¼″ to 1″ in size. In other embodiments the size can be from ⅛″ to 1¼″ or even ⅙″ to 1¼″ in size. The porosity controls the fraction of the inlet flow to pass through the perforated conical deflector plate  201  and consequently the fraction of redirected flow to the radial flow reactor vessel wall. 
     In one embodiment the diameter of the perforated deflector (D D ) can be determined with a relationship between the height of the opening in the inlet distributor pipe (H SLOT ) and the outer diameter of the inlet distributor pipe (OD DP ) utilizing the following relationship:
 
 D   D   =OD   DP +2( xH   SLOT )
 
Where x is at least ½.
 
     Alternatively in another embodiment, the diameter of the perforated deflector (D D ) can be determined with a relationship with the outer diameter of the inlet distributor pipe (OD DP ) utilizing the following relationship:
 
 D   D   =OD   DP +2(⅓ OD   DP )
 
     In yet another embodiment, the height of the perforated deflector can be a fraction of the diameter of the inlet distributor pipe and/or the height of the inlet distributor pipe openings. In determining the height of the perforated conical deflector (D H ), a relationship between the diameter of the perforated deflector (D D ) and the outer diameter of the inlet distributor pipe (OD DP ) is utilized, providing:
 
 D   H   =N (½( D   D   −OD   DP ))
 
where N is any number between 0 and 1.
 
     The internal angle between the conical perforated deflector and the inlet distributor pipe is determined by the height and diameter of the conical perforated deflector. 
     In  FIG. 3 , the porous deflector is a perforated conical deflector attached to the bottom of the inlet distributor nozzle  20  which is not attached to the inlet pipe (not shown), but rather is an insert supported by the reactor inlet flange  12 . Since the existing conventional inlet distributor nozzle  20  is likely slightly smaller diameter than the reactor inlet duct  13 , the entire inlet distributor nozzle is redesigned to allow the conical porous deflector plate  201  to be added to the inlet distributor nozzle. Calculations for the conical porous deflector plate dimensions can be done similar as explained above once a diameter for the inlet distributor nozzle is determined. 
       FIG. 4 , the porous deflector is a perforated conical deflector attached to the cover deck  30  in reactor designs where the cover deck to too near the reactor inlet  11  to allow an inlet distributor nozzle  20 . The diameter of the conical porous deflector can be determined from the diameter of the reactor inlet duct  13  and can be installed in two pieces on the cover deck. Calculations for the conical porous deflector plate dimensions can be done similar as explained above once a diameter is determined. 
       FIG. 5 , the porous deflector is a perforated conical deflector attached to, but elevated above the cover deck  30  in reactor designs where the cover deck is too near the reactor inlet  11  to allow an inlet distributor nozzle  20  but far enough away to need some elevation to function properly or in other reactor designs where installation of a reactor inlet nozzle is impractical. The diameter of the conical porous deflector can be determined from the diameter of the reactor inlet duct  13  and can be installed in two pieces on the cover deck. Calculations for the conical porous deflector plate dimensions can be done similar as explained above once a diameter is determined. 
       FIG. 6 , the porous deflector is an expanded metal screen deflector  301 . The expanded metal screen deflector is placed over the inlet distributor nozzle  20  for a reactor inlet duct  13  marginally larger than the inlet distributor nozzle  20 . The expanded metal screen deflector is placed over the slots in the inlet distributor pipe. The sizes of the slots are increased according to the solidity of the expanded metal screens. The strands of the expanded metal screens act like vanes to alter the fluid flow direction. The vanes will be oriented such that the intended direction of flow after passing through the expanded metal screen is upwards or in a direction opposite to the upstream vapor flow. The angle of the vanes is dependent on the width of the expanded metal screen strands and the size of the expanded metal screen opening. The size of the expanded metal screen openings is either a fraction of the open height of the inlet distributor pipe openings or the outer diameter of the inlet distributor pipe or the amount of area reduction by the expanded metal screen for vapor flow. 
     In an embodiment, flow turning vanes may be inserted inside of the elbows of the reactor inlet pipe (not shown) to reduce the circumferential variation in the feed vapor. 
     In an embodiment, flow turning vanes may be installed in the inlet distributor nozzle  20  openings or slots to achieve the intent of the perforated deflector or expanded metal screens. 
     The use of the perforated deflector reduces the energy required to achieve an equivalent uniform fluid flow distribution when compared to throttling or reducing the inlet distributor nozzle slot open area. The reduced energy and lower pressure drop across the inlet distribution reduces the operating cost of improved vapor flow distribution. 
     In closing, it should be noted that the discussion of any reference is not an admission that it is prior art to the present invention, especially any reference that may have a publication date after the priority date of this application. At the same time, each and every claim below is hereby incorporated into this detailed description or specification as additional embodiments of the present invention. 
     Although the systems and processes described herein have been described in detail, it should be understood that various changes, substitutions, and alterations can be made without departing from the spirit and scope of the invention as defined by the following claims. Those skilled in the art may be able to study the preferred embodiments and identify other ways to practice the invention that are not exactly as described herein. It is the intent of the inventors that variations and equivalents of the invention are within the scope of the claims while the description, abstract and drawings are not to be used to limit the scope of the invention. The invention is specifically intended to be as broad as the claims below and their equivalents.