Patent Publication Number: US-8967919-B2

Title: System and process for injecting catalyst and/or additives into a fluidized catalytic cracking unit

Description:
CROSS REFERENCE TO RELATED APPLICATIONS: 
     This application is a divisional of U.S. patent application No. 10/593,499 filed Sep. 20, 2006 which is a continuation in part of U.S. patent application No. 10/806,563 filed Mar. 23, 2004, the contents of which are incorporated by reference herein in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to equipment used in fluidized catalytic cracking (FCC) operations and, more particularly, to systems and processes for injecting catalyst and/or additives into equipment units employed to conduct FCC operations. 
     BACKGROUND OF THE INVENTION 
     FCC units commonly include a circulating inventory of bulk catalyst. The bulk catalyst is typically used to perform a primary function, such as producing naptha from petroleum feedstock, the naptha being further processed into gasoline. Additives, which are often in the same fluidizable and particulated form as the catalyst, are often introduced into the circulating inventory of bulk catalyst to perform a secondary function such as reducing certain types of emissions, e.g., SOx or NOx, produced by the FCC unit. These emissions are produced in the catalyst regenerator of the FCC unit where coke deposits from the cracked petroleum are burned off and the regenerated catalyst returned to the circulating catalyst inventory, These additives are usually introduced into the regenerator using an injection device commonly referred to as a “loader.” Loaders are also used to add catalyst to the bulk inventory as additional catalyst becomes necessary due to factors such as attrition and deactivation. 
     Loaders used for catalyst and/or additive injection typically comprise a transfer pot, and a storage hopper or silo located above or proximate the transfer pot. The catalyst and/or additive is usually transferred to the storage hopper from a storage bin using a suitable technique such as vacuum transfer. During operation of the loader, a predetermined amount of catalyst and/or additive can be metered to the transfer pot from the storage hopper. The transfer pot can subsequently be pressurized, and the catalyst and/or additive can be injected into the regenerator in response to the pressure within the transfer pot. This process is usually repeated on a cyclical basis. 
     The amount of catalyst metered to the transfer pot and injected during each cycle is usually small in comparison to the overall volume of the storage hopper. In other words, a relatively large volume of catalyst and/or additive is typically stored in the hopper so that relatively small doses of the catalyst and/or additive can be metered to the transfer pot during each cycle. A typical storage hopper is relatively large due to the need to accommodate a large amount of additive or catalyst therein. For example, a typical storage hopper can have a diameter of five feet or more, and height of fifteen feet or more. 
     The relatively large size of conventional storage hoppers can limit the number of suitable locations in which the loader can be installed. This characteristic can be particularly disadvantageous at a refinery, where space can be and often is limited. The need for a relatively large area to accommodate the loader (and in particular the storage hopper) can thus necessitate placing the loader in a less than optimal location. 
     Moreover, the loader can only be used to inject one type of catalyst and/or additive at a time, due to the need for a dedicated storage hopper for each type of catalyst and/or additive. In other words, the transfer pot can only inject the catalyst and/or additive stored in its associated hopper, until the catalyst and/or additive is replaced with another type of catalyst and/or additive. Hence, loading different types catalyst and/or additives on simultaneous or near-simultaneous (back to back) basis can only be accomplished using multiple loaders. Each additional loader requires additional outlays of time, labor, and money to purchase, install, operate, and maintain. Moreover, each loader consumes potentially valuable space within the refinery. 
     The storage hopper may be pressurized in some applications to facilitate transfer of the catalyst and/or additive to the transfer pot. The pressurized air within the hopper can adversely affect the measurements that provide and indication of how much catalyst and/or additive has been added to the transfer pot. Also, the catalyst and/or additive may be exposed to pressurized air from the refinery (commonly referred to as “plant air”) while it is being transferred to, or stored in the hopper. Plant air often contains moisture or other contaminates that can adversely affect the catalyst and/or additive. 
     SUMMARY OF THE INVENTION 
     A preferred embodiment of a system for injecting catalyst and/or additives into a fluidized catalytic cracking unit comprises a dust collector in fluid communication with a storage bin holding one of the catalyst and/or additives, and a vacuum producer in fluid communication with the dust collector so that the vacuum producer generates a vacuum within the dust collector that draws the one of the catalyst and/or additives into the dust collector. 
     The system also comprises a transfer pot for receiving the one of the catalyst and/or additives from the dust collector. The transfer pot is in fluid communication with the fluidized catalytic cracking unit and a source of pressurized air so that the one of the catalyst and/or additives is transferred to the fluidized catalytic cracking unit in response to a pressure differential between the transfer pot and the fluidized catalytic cracking unit. 
     A preferred embodiment of a system for loading catalyst and/or additives into a fluidized catalytic cracking unit comprises a bin for storing at least one of the catalyst and/or additives, and a loading unit in fluid communication with the storage bin and the fluidized catalytic cracking unit on a selective basis. The loading unit is capable of being evacuated so that a resulting vacuum within the loading unit draws the at least one of the catalyst and/or additives from the bin, and the loading unit is capable of being pressurized so that the least one of the catalyst and/or additives is transferred from the loading unit to the fluidized catalytic cracking unit. 
     Another preferred embodiment of a system for loading catalyst and/or additives into a fluidized catalytic cracking unit comprises a first bin for storing a first of the catalyst and/or additives, a second bin for storing a second of the catalyst and/or additives, and a loading unit in fluid communication with the first and second bins and the fluidized catalytic cracking unit. The system also comprises a first valve for isolating the first bin from the loading unit on a selective basis, a second valve for isolating the second bin from the loading unit on a selective basis, and a third valve for isolating the second bin from the fluidized catalytic cracking unit on a selective basis. 
     A preferred embodiment of a system for introducing catalyst and/or additives into a fluidized catalytic cracking unit comprises a dust collecting means in fluid communication with a storage bin holding one of the catalyst and/or additives, and a vacuum producing means in fluid communication with the dust collecting means so that the vacuum producing means draws the one of the catalyst and/or additives into the dust collecting means. The system also comprises a means for receiving the one of the catalyst and/or additives from the dust collecting means and injecting the one of the catalyst and/or additives into the fluidized catalytic cracking unit. 
     A preferred process for introducing catalyst and/or additives into a fluidized catalytic cracking unit comprises generating a vacuum within a loading unit, drawing one of the catalyst and/or additives from a storage bin and into the loading unit in response to the vacuum, pressurizing the loading unit, and injecting the one of the catalyst and/or additives into the fluidized catalytic cracking unit in response to the pressurization of the loading unit. 
     A preferred process for loading catalyst and/or additives into a fluidized catalytic cracking unit comprises storing at least one of the catalyst and/or additives at a first location, vacuuming the at least one of the catalyst and/or additives into a loading unit positioned at a second location, and injecting the at least one of a catalyst and/or additives into the fluidized catalytic cracking unit from the loading unit. 
     A preferred embodiment of a system for introducing one or more particulate substances into a fluid stream comprises a dust collecting means in fluid communication with at least one storage bin holding the one or more particulate substances. The system also comprises a vacuum producing means in fluid communication with the dust collecting means so that the one or more particulate substances is drawn into the dust collecting means from the at least one storage bin by a vacuum. The system further comprises a means for receiving the one or more particulate substances from the dust collecting means and injecting the one or more particulate substances into the fluid stream. 
     A preferred conveying process comprises generating a vacuum within a dust collector of a loading unit, and drawing a particulate material from a storage bin and into the dust collector in response to the vacuum so that the particulate material enters a transfer pot of the loading unit adjoining the dust collector. The process also comprises pressurizing the transfer pot, and discharging the particulate material from the transfer pot in response to the pressurization of the transfer pot. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of a preferred embodiment, are better understood when read in conjunction with the appended diagrammatic drawings. For the purpose of illustrating the invention, the drawings show an embodiment that is presently preferred. The invention is not limited, however, to the specific instrumentalities disclosed in the drawings. In the drawings: 
         FIG. 1  is a schematic side view of a preferred embodiment of a system for injecting catalyst and/or additives into an FCC unit, showing a dust collector and a transfer pot of the system longitudinal cross section; 
         FIG. 2  is a diagrammatic side view of the system shown in  FIG. 1 ; 
         FIG. 3  is a diagrammatic side view of the system shown in  FIGS. 1 and 2 , from a perspective rotated approximately 180 degrees from the perspective of  FIG. 2 ; 
         FIG. 4  is a diagrammatic side view of the system shown in  FIGS. 1-3 , from a perspective rotated approximately 90 degrees from the perspective of  FIG. 2 ; 
         FIG. 5  is a magnified view of the area designated “A” in  FIG. 3 ; 
         FIG. 6  is a block diagram depicting a control system of the system shown in  FIGS. 1-5 ; 
         FIG. 7  is a flow diagram depicting operation of the system shown in  FIGS. 1-6 ; 
         FIG. 8  is a top view of a manifold for use with an alternative embodiment of the system shown in  FIGS. 1-6 ; 
         FIG. 9  is a top view of another alternative embodiment of the system shown in  FIGS. 1-6 , with a cover of a dust collector of the system removed; and 
         FIG. 10  is a top view of another alternative embodiment of the system shown in  FIGS. 1-6 , with a cover of a dust collector of the system removed. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A preferred embodiment of a system  10  for injecting catalyst and/or additives into an FCC unit is depicted in  FIGS. 1-6 . The loading system  10  forms part of an overall system  11  for storing and loading catalyst and/or additives. The system  11  includes the loading system  10 , and one or more storage bins  37 . 
     The loading system  10  comprises a loading unit  14  having a dust collector  16  and an adjoining transfer pot  18 . The loading system  10 , as discussed in detail below, produces a vacuum that draws catalyst and/or additive from the storage bins  37  and into the dust collector  16 . The catalyst and/or additive falls to the bottom of the dust collector  16  and into the transfer pot  18 . The transfer pot  18  is subsequently pressurized, and the catalyst and/or additive is injected into a regenerator of the FCC unit in response to the pressure within the transfer pot  18 . 
     The loading unit  14  can be housed within a cabinet  19  (see  FIGS. 2-4 ). (The cabinet  19  is shown in the figures with its side panels removed, for clarity.) The loading unit  14  is preferably supported by a plurality of legs  20  affixed to the transfer pot  18 . 
     Cabinet  19  is optional and can be configured to accommodate the particular configuration and size of the injection system. Preferably side panels to the cabinet are removable (and/or designed as doors which are easily opened) and substantially full length and width of the enclosure to give an operator or repair person full access to the system. Alternatively, closable portals can be placed in walls that are more substantially affixed to the system&#39;s base, with the portals used for access to relatively small components of the system. 
     The cabinet serves to protect the system from damaging elements in the environment, e.g., plant dust, rain, direct sunlight, as well as reduces dusting created by the movement of catalyst as it is drawn in and then injected by the system. The cabinet also can retain any catalyst particulate that may spill or leak from broken or damaged hoses that transport catalyst into and throughout the system, as well as retain any fugitive emissions from the contained equipment. 
     The cabinet can also be designed to be large enough to provide shelter for an operator or repair person. The cabinet also “unitizes” the system, thereby making it easier to transport and install the system. Indeed, the cabinet could be designed to serve as a shipping container in addition to serving as a protective enclosure. 
     The dust collector  16  comprises a sidewall  17 . The sidewall  17  should be of a suitable strength and thickness to withstand the presence of a vacuum within the dust collector  16 . 
     The cross section and overall shape of the dust collector  16  can vary. The dust collector  16  depicted in the figures has a substantially cylindrical upper portion  16   a , and a substantially conical lower portion  16   b  that adjoins the upper portion  16   a . An opening  23  is formed in the center of the lower portion  16   b  (see  FIG. 1 ). A screen  24  is positioned across the lower portion  16   b . In other embodiments, the cross section of the upper portion  16   a  and the lower portion  16   b  can be square or rectangular, and the overall shape can be in the form of a square or rectangular column. (Directional terms such as “upper,” “lower,” etc. are used herein with reference to the component orientations depicted in  FIG. 1 . These terms are used for exemplary purposes only, and are not intended to limit the scope of the appended claims.) 
     The dust collector  16  also includes a cover  25 . The cover  25  mates with an upper edge of the sidewall  17 . A gasket is positioned between the cover  25  and the sidewall  17  to form a substantially airtight seal therebetween. The sidewall  17  and the cover  25  define an internal volume  26  within the dust collector  16  (see  FIG. 1 ). 
     The dust collector  16  also comprises a suitable filter  32  (see  FIG. 1 ). The filter  32  can be, for example, a Mactiflo model E376094 filter. 
     The filter  32  is mounted within the upper portion  16   a  of the dust collector  16 . The sidewall preferably includes a hatch  33  to provide access to the interior of the upper portion  16   a  (and the filter  32 ) (see  FIGS. 1 and 4 ). The hatch  33  is preferably secured the sidewall  17  of the dust collector  16  using brackets  34  that permit the hatch  33  to be removed with a minimal expenditure of time and effort, thereby facilitating replacement of the filter  32  with a minimum of time and effort. Alternative embodiments of the loading system  10  can be equipped with more than one of the filters  32 . 
     The system  10  also comprises suitable vacuum producer  30  (see  FIGS. 1 and 2 ). For example, the vacuum producer can be an Empire two-inch Vacutran S150 vacuum producer. 
     The vacuum producer  30  is mounted within the cabinet  19  (see  FIG. 2 ). The vacuum producer  30  is preferably mounted separately from the loading unit  14 . The vacuum producer  30  is in fluid communication with the filter  32  by way of a hose  35 . 
     The vacuum producer  30  is in fluid communication with a suitable source of pressurized air (not shown). (The source of pressurized air can be the plant air typically available at refineries.) The flow of pressurized air into the vacuum producer  30  can be regulated by a suitable valve  36  having an actuator  36   a  (see  FIG. 1 ). 
     The vacuum producer  30  can operate in a manner commonly known to those skilled in the art of vacuum-chamber design. In particular, opening the valve  36  permits the pressurized air to flow through the vacuum producer  30 . The flow of pressurized air through the vacuum producer  30  causes the vacuum producer  30  to draw air from the internal volume  26  of the dust collector  16 , thereby generating a vacuum within the internal volume  26 . (The vacuum producer  30  draws the air through the filter  32 , thereby causing the dust collector  16  to collect the dust generated by the flow of catalyst and/or additive into the dust collector  16 .) The respective directions of various airflows within the loading system  10  are denoted by arrows  39  in  FIG. 1 . 
     The loading system  10  draws catalyst and/or additive from storage bins in response to the vacuum within the internal volume  26 . In particular, the dust collector  16  is in fluid communication with storage bins  37  (see  FIG. 1 ). The storage bins  37  hold catalyst and/or additives to be injected into the FCC unit. The storage bins  37  can be, for example, the shipping containers used to transport the catalyst and/or additives to the refinery at which the loading system  10  is installed. 
     Each storage bin  37  is coupled to the dust collector  16  by a corresponding hose (or pipe)  38 . A suitable valve  42  having an actuator  42   a  is located between each hose  38  and the dust collector  16 . Each valve  42  isolates its associated storage bin  37  from the dust collector  16  on a selective basis. The valves  42  are installed on the upper portion  16   a  of the dust collector  16 , and are in fluid communication with the internal volume  26  by way of corresponding openings formed in the upper portion  16   a  of the dust collector  16 . (The hoses  38  and valves  42  thus form part of the system  11  for storing and loading catalyst and/or additives). 
     The hoses  38  can be coupled to the upper portion  16   a  by way of a common manifold  74  in alternative embodiments, as shown in  FIG. 8 . 
     The hoses  38  are preferably equipped with fittings that permit the hoses  38  to be readily removed from the dust collector  16  (or the manifold  74 ) and the storage bins  37 . 
     Opening one of the valves  42  permits catalyst and/or additive to be drawn from the associated storage bin  37  by way of the associated hose  38 , in response to the vacuum within the internal volume  26 . The catalyst and/or additive is thus drawn directly from the storage bin  37  and into the loading system  10 , without a need to load the catalyst and/or additive into a storage hopper. 
     The loading system  10  is depicted as being equipped with three sets of the valves  42  and hoses  38 , for exemplary purposes only. Alternative embodiments can be equipped with more or less than three valves  42  and three hoses  38 , and can draw catalyst and/or additive from more or less than three of the storage bins  37 . 
     One or more (2, 3, 4, etc.) storage bins  37  can be positioned at a location remote from the loading system  10 . For example, the storage bins  37  can be located up to twenty feet from the loading system  10 . (The maximum distance between the loading system  10  and the storage bins  37  is application dependent, and can vary with factors such as the capacity of the vacuum producer  30 , the diameter of the hoses  38 , etc. A particular value for this parameter is specified for exemplary purposes only.) 
     The dust collector  16  preferably includes three pipe guides  40 . Each pipe guide  40  is in fluid communication with an associated one of the hoses  38 . 
     The catalyst and/or additive drawn into the internal volume  26  by way of one of the pipe guides  40 . The pipe guides  40  discharge the catalyst or additive proximate into the internal volume  26 , proximate the screen  24 . 
     Alternative configurations of manifold  74  include an internal manifold, such as the manifold  100  depicted in  FIG. 9 . In such an embodiment, one or more individual hoses  38  can be routed through portals in the upper portion  16   a , with the portals preferably sealed via gaskets or the like. One or more pipe guides  102  can be secured to the sidewalls of the upper portion  16   a  by a suitable means such as welds, flanges, brackets, fasteners, etc., so that the pipe guides  102  extend into the upper portion  16   a.    
     Each of the hoses  38  are then coupled by way of the common manifold  100  that is located inside the upper portion  16   a . The manifold  100  can include valves, such as the valves  42 , for placing the manifold  100  (and the dust collector  16 ) in fluid communication with the associated hose  38  and storage bin  37  on a selective basis. A single discharge pipe guide  104  (as opposed to the multiple pipe guides  40  illustrated in  FIG. 1 ) can descend from the manifold  100  in the direction of the bottom portion of  16   b . The end of the discharge pipe guide  104  preferably is located approximately six inches above the opening  23  formed in the lower portion  16   b  of the dust collector  16 . (The optimal distance between the end of the discharge pipe guide  104  and the opening  23  can vary by application; a specific value for this distance is presented for exemplary purposes only.) This configuration of hoses  38 , manifold  100 , and single discharge pipe guide  104  create a “spider” arrangement of hoses such that the single discharge pipe guide  104  can be positioned in the center of the upper portion  16   a . Centering the manifold  100  and the associated discharge pipe guide  104  insures that catalyst and/or additive is deposited at the bottom of dust collector  16 . This configuration helps reduce catalyst and/or additive striking the sides of the upper portion  16   a , and thereby reduces any potential build up of catalyst and/or additive on those walls. This configuration also potentially reduces catalyst and/or additive attrition that could occur as the catalyst and/or additive particulate strikes the sidewalls. 
     Another arrangement for discharging the catalyst and/or additive into the dust collector  16  is depicted in  FIG. 10 . In this embodiment, one or more of the individual hoses  38  can be routed through portals in the upper portion  16   a , with the portals preferably sealed via gaskets or the like. One or more pipe guides  110  can be secured to the sidewall of the upper portion  16   a  by a suitable means such as welds, flanges, brackets, fasteners, etc., so that each pipe guide  110  receives catalyst and/or additive from a respective hose  38 . A valve, such as the valve  42 , can be mounted on each pipe guide  110  to place the pipe guide  110  (and the dust collector  16 ) in fluid communication with the associated hose  38  and storage bin  37  on a selective basis. Each valve  42  can be mounted on the sidewall of the upper portion  16   a  by a suitable means such as flanges. 
     The pipe guides  110  each extend inward from the sidewall of the upper portion  16   a , so that the respective ends of the pipe guides  110  are located proximate the centerline of the dust collector  16 . The ends of the pipe guides  110  can be secured to each other by a suitable means such as welding, fasteners, brackets, etc. Each pipe guide  110  thus discharges catalyst and/or additive proximate the centerline of the dust collector  16 . The pipe guides  110  preferably extend downward, at an angle of approximately seventy degrees in relation to the horizontal direction. (The optimal orientation of the pipe guides  110  can vary by application; a specific orientation is presented for exemplary purposes only.) The ends of the pipe guides  100  preferably are located approximately six inches above the opening  23  formed in the lower portion  16   b  of the dust collector  16 . (The optimal distance between the ends of the pipe guides  110  and the opening  23  can vary by application; a specific value for this distance is presented for exemplary purposes only.) This configuration helps reduce catalyst and/or additive striking the sides of the upper portion  16   a , and thereby reduces any potential build up of catalyst and/or additive on those walls. This configuration also potentially reduces catalyst and/or additive attrition that could occur as the catalyst and/or additive particulate strikes the sidewalls. 
     It should be noted that the depiction of the system  11  in  FIG. 1  is schematic in nature, and the relative positions of the various hoses, piping, etc. of the system  11  can be different than those depicted in  FIG. 1 . For example, the openings formed in the upper portion  16   a  of the dust collector  16  to accommodate the hoses  38  can be positioned around the circumference of the upper portion  16   a , in lieu of the vertical arrangement depicted in  FIG. 1 . In other embodiments, multiple hoses can be positioned on two or more sides of upper portion  16   a.    
     The catalyst or additive drops toward the bottom of the dust collector  16 , i.e., toward the lower portion  16   b , after being discharged from the pipe guides  40  (or the discharge pipe guide  104  or pipe guides  110 ) due to gravity. The catalyst and/or additive passes through the screen  24  as it drops (see  FIG. 1 ). The mesh of the screen  24  is preferably chosen to block the passage of relatively large clumps or catalyst and/or additive (or foreign objects), while permitting relatively fine granules of catalyst and/or additive to flow freely therethrough. The substantially conical shape of the lower portion  16   b  directs the catalyst and/or additive toward the opening  23  in the lower portion  16   b.    
     The loading system  10  includes the valve  43  for covering and sealing the opening  23  on a selective basis. The valve  43  can be, for example, a plug valve comprising a seat  44  and plug  45 . The seat  44  is secured to the lower portion  16   b , around the periphery of the opening  23 . The plug  45  is movable between an upper and a lower position (the plug  45  is depicted in its lower position in  FIG. 1 ). 
     The valve  43  is actuated by pressurized air. The pressurized air is directed to the valve  43  by way of piping  46  that extends through the transfer pot  18 . The flow of pressurized air into the piping  46  can be initiated and interrupted on a selective basis by a valve  48  in fluid communication with the piping  46 . The valve  48   a  includes an actuator  48   a.    
     The pressurized air impinges upon the plug  45  after exiting of the piping  46 . More particularly, the pressurized air is directed to the interior of the plug  45 , and urges the plug  45  into its closed position against the seat  44 . The contact between the plug  45  and the seat  44  substantially seals the opening  23 . 
     The plug  45  drops from its closed to its open position when the pressurized air is interrupted by closing the valve  48 . The resulting gap between the plug  45  and the seat  44  permits catalyst and/or additive reaching the bottom of the lower portion  16   b  to pass through the opening  23  and into the transfer pot  18  (see  FIG. 1 ). 
     The loading system  10  preferably includes a volume chamber and moisture trap  49  in fluid communication with the piping  46  (see  FIGS. 1 and 2 ). The volume chamber and moisture trap  49  removes moisture from the pressurized air directed to the valve  43 . 
     The transfer pot  18  comprises a sidewall  51 . The sidewall  51  should be of a suitable strength and thickness to withstand pressurization of the transfer pot  18 . 
     The cross section and overall shape of the transfer pot  18  can vary. The transfer pot  18  depicted in the figures has a substantially cylindrical upper portion  18   a , and a substantially conical lower portion  18   b  that adjoins the upper portion  18   a . The upper portion  18   a  and the lower portion  18   b  of the transfer pot  18 , and the lower portion  16   b  of the dust collector  16  define an internal volume  50  within the transfer pot  18  (see  FIG. 1 ). (The lower portion  16   b  and the valve  43  thus form a boundary between the internal volume  26  of the dust collector  16  and the internal volume  50  of the transfer pot  18 .) 
     An opening  53  is formed in the center of the lower portion  18   a  of the transfer pot  18 . The transfer pot  18  is coupled to the regenerator of the FCC unit by piping  54 . The piping  54  is in fluid communication with the opening  53 . Catalyst and/or additive enters the piping  54  by way of the opening  53  and subsequently flows to the regenerator, as discussed below. 
     A valve  55  having an actuator  55   a  is installed in piping  54 . The valve  55  permits the transfer pot  18  to be isolated from the regenerator on a selective basis. A suitable transfer pot  18  can be obtained, for example, by adapting a Clemtex, Inc. model 2452 six-cubic foot sandblasting pot, or a model 1648 two-cubic-foot sandblasting pot to mate with the dust collector  16 . (The sandblasting pot can be mated with the dust collector  16  by securing the lower portion  16   b  of the dust collector  16  to the upper periphery of the sandblasting pot by a suitable means such as welding.) 
     The loading unit  14  is supported by a plurality of load cells  56  (see  FIGS. 1 and 4 ). The load cells  56 , as discussed below, provide a measure of the weight of the loading unit  14  in both an unloaded and loaded condition, i.e., with and without catalyst and/or additive therein. The load cells  56  are preferably mounted between a base  19   a  of the cabinet  19 , and a plate  57  fixedly coupled to the legs  20  of the transfer pot  18 . 
     Each load cell can be restrained from substantial horizontal movement by a corresponding restraint  61  (the restraints  61  are shown only in  FIG. 5 , for clarity.) Each restraint  51  is pivotally coupled to the base  19   a  of the cabinet  19 . 
     The loading system  10  can include a plurality of jack assemblies  62  (the jack assemblies  62  are shown only in  FIG. 5 , for clarity.) Each jack assembly  62  comprises a threaded shaft  62   a  fixedly coupled to the base  19   a  of the cabinet  19 . Two nuts  62   b  are threadably coupled to each shaft  62   a . The nuts  62   b  are located above and below the plate  57 . The lower nuts  62   b  can be raised so that the lower nuts  62   b  support the plate  57  (and the portion of the loading system  10  positioned on the plate  57 ). The upper nuts  62   b  can be lowered to lock the plate  57  in position, i.e., the plate  57  can be sandwiched between the upper and lower nuts  62   b.    
     The jack assemblies  62  can thus substantially isolate the load cells  57  from the weight of the loading system  10 . This feature can be used, for example, to protect the load cells  57  from being damaged by impact loads during shipping of the loading system  10 . 
     External connections to the loading unit  14  are preferably configured so as to introduce a negligible tare into the load cell readings. For example, the piping  54  includes a flexible sections  46   a  that substantially decouples the transfer pot  18  from the portion of the piping  54  connected to the regenerator, thereby minimizing any tare introduced into the load cell readings (see  FIG. 1 ). The piping  46  likewise includes a flexible section  46   a  that substantially decouples the transfer pot  18  from the portion of the piping  46  connected to the plant-air equipment. Moreover, the hoses  35 ,  38  preferably have sufficient flexibility so that any tare introduced thereby is negligible. 
     The internal volume  26  of the dust collector  16  and the internal volume  50  of the transfer pot  18  are in fluid communication on a selective basis by way of piping  58 . A valve  59  having an actuator  59   a  is located in the piping  58  to selectively open and close the path formed by the piping  58 . The piping  58  is used to equalize the pressures within the internal volumes  26 ,  50 , as discussed below. 
     The loading system  10  preferably comprises a controller  60  (see  FIGS. 3 and 6 ). The actuators  36   a ,  42   a ,  48   a ,  55   a ,  59   a  of the respective valves  36 ,  42 ,  48 ,  55 ,  59  are electrically coupled to the controller  60 . This feature permits the operation of the valves  36 ,  42 ,  48 ,  55 ,  59  to be controlled by the controller  60 . 
     The controller  60  is a programmable loop controller (PLC), although virtually any type of computing device such as a minicomputer, microcomputer, etc. can be used as the controller  60  in alternative embodiments. A server or mainframe computer that controls other equipment and processes at the refinery in which the loading system  10  is operated can also be used to control the loading system  10  in the alternative. For example, a computer based system known as a “distributed control system” or DCS is an example of a centralized system used by FCC unit operators to control a number of unit operations. Controller  60  can be coupled to and/or communications lines can be established between controller  60  and the DCS so that the DCS controls the loading system through the controller. 
     The controller  60  can include a control panel  64  for inputting commands and operating data to the controller  60  (see  FIGS. 3 and 6 ). The controller  60  and the control panel  64  can be mounted on the cabinet  19 . The control panel  64  by itself, or both the control panel  64  and the controller  60  can be mounted at a convenient location remote from the remainder of the loading system  10  in alternative embodiments. For example, the control panel  64  can be mounted in a central control room of the refinery, thus allowing the operation of the loading system  10  to be controlled on a remote basis. 
     The controller  60  can be configured to cause a predetermined amount of catalyst and/or additive to be injected into the regenerator. The predetermined amount can be input to the controller  60  by the user via the control panel  64 . 
     Moreover, the controller  60  can be configured to facilitate injection of the catalyst and/or additive on a cyclical basis. For example, the controller  60  can be programmed to facilitate the injection of a predetermined amount of additive over a twenty-four hour period, i.e., per day, using a predetermined number of discrete injections over that period. The operation of the loading system  10  over one such cycle is described below, and is depicted in the form of a flow diagram in  FIG. 7 . 
     (The controller  60  can also be configured to facilitate injection of the catalyst and/or additive on a non-cyclical basis. In other words, the controller  60  can be programmed to facilitate periodic injections of varying amounts of catalyst and/or additive.) 
     The total amount of catalyst and/or additive to be injected over the twenty-four hour period can be input to the controller  60  by the user using the control panel  64 . The number of discrete injections to be performed per day can also be input by way of the control panel  64 . (The controller  60  can be programmed to operate based on other inputs in alternative embodiments. For example, the controller  60  can be programmed to inject a predetermined amount of additive per cycle, using predetermined interval between injections.) 
     The controller  60  can be programmed to automatically calculate the amount of catalyst and/or additive to be injected during each cycle based on the above-noted inputs. The controller  60  can also be programmed to calculate the time interval between the start of each injection. The interval is calculated by dividing twenty-four hours by the required number of injections per day. Moreover, the controller  60  can be configured to accept an input denoting the particular storage bin  37  from which the catalyst and/or additive is to be drawn. 
     The controller  60  sends a control input to the actuator  42   a  of the valve  42  associated with the particular storage bin  37  from which the catalyst and/or additive is to be drawn (see  FIG. 7 ). The control input causes the actuator  42   a  to open the valve  42 , thereby placing the storage bin  37  in fluid communication with the dust collector  16 . (The valves  36 ,  42 ,  48 ,  55 ,  59  are in their respective closed positions, and the plug  45  of the valve  43  is in its open (lower) position at the start of the cycle.) 
     The controller  60  also sends an input to the actuator  36   a  of the valve  36 , thereby allowing pressurized air to flow through the vacuum producer  30 . The vacuum producer  30  creates a vacuum within the internal volume  26  of the dust collector  16  in response to the flow of pressurized air therethrough, as discussed above. 
     The vacuum within the internal volume  26  draws the catalyst and/or additive from the storage bin  37  and into the upper portion  16   a  of the dust collector  16 . (The direction of travel of the catalyst and/or additive through the loading system  10  is denoted by arrows  65  in  FIG. 1 .) The catalyst and/or additive subsequently falls toward the lower portion  16   b  due to gravity, and enters the transfer pot  18  by way of the opening  23  in the lower portion  16   b , as noted previously. 
     The controller  60  continually monitors the weight of the loading unit  14 , and the weight of the catalyst and/or additive added thereto. (The combined weight of the loading unit  14  and any catalyst and/or additive therein is hereinafter referred to as the “live weight” of the loading system  10 ). In particular, the load cells  56  are electrically coupled to the controller  60 . The controller  60  receives inputs from each of the load cells  56 , and adds the inputs to determine the live weight of the loading system  10 . 
     The controller  60  calculates the amount of catalyst and/or additive that is added to the loading system  10 . The controller  60  performs this calculation by subtracting the live weight of the loading system  10  at a given instant from the live weight of the loading system  10  at the start of the cycle, i.e., immediately prior to the opening of the valves  36 ,  42  (the loading unit  14  is assumed to be substantially empty of catalyst and/or additive at the start of the cycle). 
     The controller  60  stops the flow of catalyst and/or additive to the dust collector  16  as the amount of catalyst and/or additive added to the loading system  10  approaches the amount to be injected into the regenerator during each cycle (this amount is subsequently referred to as a “target value”). In particular, the controller  60  sends a control input to the actuator  42   a  of the open the valve  42  as the weight of the catalyst of additive approaches its target value. The control input causes the valve  42  to close, thereby interrupting the flow of catalyst and/or additive to the dust collector  16 . (The controller  60  can be programmed to commence the closing of the valve  42  when the weight of the catalyst and/or additive is below the target weight by a predetermined amount, so as to compensate for the lag between the issuance of the “close” command to the valve  42 , and the point at which the valve  42  is fully closed). 
     The controller  60  also sends a control input to the actuator  36   a  of the valve  36  as the weight of the catalyst of additive in the loading system  10  reaches its target value. The control input causes the actuator  36   a  to close the valve  36 , thereby interrupting the flow of pressurized air through the vacuum producer  30 . 
     The controller  60  subsequently sends a control input to the actuator  48   a  of the valve  48  to cause the valve  48  to open. Opening the valve  48  permits pressurized air to enter the internal volume  50  of the transfer pot by way of the piping  46 . The pressurized air impinges on the plug  45  of the valve  43  upon exiting the piping  46 , and thereby urges the plug  45  into its closed (upper) position against the lower portion  16   b  of the dust collector  16 , as discussed above. The contact between the plug  45  and the lower portion  16   b  covers and seals the opening  23 . 
     The pressurized air pressurizes the internal volume  50  of the transfer pot  18  after the opening  23  has been sealed by the plug  45 . (The pressurized air, as discussed above, is dried by the volume chamber and moisture trap  49  before reaching the transfer pot  18 , thereby minimizing the potential for contamination of the catalyst and/or additive within the transfer pot  18 .) 
     The controller  60  receives an input from a first pressure transducer  68  that measures the pneumatic pressure in the internal volume  50  (see  FIG. 6 ). The controller  60  also receives an input from a second pressure transducer  70  that measures the pneumatic pressure in the regenerator proximate the location at which the catalyst and/or additive is injected. 
     The controller  60  sends a control input to the actuator  48   a  of the valve  48  when the difference between the pneumatic pressures in the internal volume  50  and the regenerator  14  reaches a predetermined value, i.e., when the pressure in the internal volume  50  exceeds the pressure in the regenerator by a predetermined amount. This control input causes the valve  48  to close. 
     The controller  60  subsequently sends a control input to the actuator  55   a  of the valve  55  to cause the valve  55  to open. The differential between the pressures in the internal volume  50  and the regenerator causes the catalyst and/or additive in the transfer pot  18  to flow into the regenerator by way of the piping  54 . 
     The controller  60  sends a control input to the actuator  55   a  to close the valve  55 , after a predetermined interval has passed following issuance of the control input to open the valve  55 . (The predetermined interval should be chosen so as to allow sufficient time for substantially all of the catalyst and/or additive in the transfer pot  18  to be injected into the regenerator). Alternatively, the controller  60  can send a control input to the actuator  55   a  to close the valve  55  when the pressure differential between the internal volume  50  and the regenerator reaches approximately zero. 
     The controller  60  subsequently sends a control input to the actuator  59   a  of the valve  59  to cause the valve  59  to open. The opening of the valve  59  permits the pneumatic pressures within the internal volumes  26 ,  50  to substantially equalize. In particular, opening the valve  59  relieves the relatively high pressure in the internal volume  50  (which is approximately equal to pressure within the regenerator  14 ) by way of the piping  58 . 
     The controller  60  sends a control input to the actuator  59   a  of the valve  59  when the pressure differential between the internal volumes  26 ,  50  is approximately zero (the pneumatic pressure in the internal volume  26  can be measured by a third pressure transducer  72  located therein). This control input causes the valve  59  to close. 
     The controller  60  can be programmed to repeat the above process after the calculated interval between the start of each injection cycle (discussed above) has passed. 
     Moreover, the controller  60  can be programmed to inject catalyst and/or additive from any of the other storage bins  37  after the above-described cycle has been completed. In other words, another injection cycle can be performed in a manner identical to that described above, with the exception that the valve  42  associated with one of the other storage bins  37  can be opened to allow the catalyst and/or additive from that particular storage bin  37  to be drawn into the dust collector  16 . 
     Vacuuming the catalyst and/or additive directly from its storage bin  37  can provide substantial flexibility in the operation of the loading system  10 . For example, the loading system  10  can draw catalyst and/or additive from virtually any location at the refinery accessible by a hose such as the hose  38 . Hence, the storage bins  37  can be positioned at an optimal location within the refinery. Moreover, the use of vacuum as a means to transport the catalyst and/or additive to the loading system  10  can permit the catalyst and/or additive to be drawn directly from its shipping container. Hence, the expenditure of time and labor associated with transferring the catalyst and/or additive from its shipping container to a storage unit can be eliminated through the use of the loading system  10 . 
     Moreover, vacuuming the catalyst and/or additive directly into the dust collector  16  can obviate the need to transfer the catalyst and/or additive into a relatively large storage hopper (as is typically required with conventional loaders). Hence, the expenditure of time and labor associated with transferring the catalyst and/or additive to a storage hopper can be eliminated through the use of the loading system  10 . 
     Eliminating the need for a storage hopper can also minimize the amount of space needed to accommodate the loading system  10 . For example, the footprint the loading system  10  is approximately four feet by four feet, and the maximum height of the loading system is approximately five feet. A conventional loader of comparable capacity (with its storage hopper) can have a footprint of approximately five feet by eight feet, and a height of approximately twenty feet. (The dimensions of the loading system  10  will vary by application, and specific dimensions are provided herein for exemplary purposes only.) Moreover, in contradistinction to many conventional loaders, the loading system  10  can be installed without the use of special mounting provisions such as a base specifically tailored to a particular installation. 
     The loading system  10  can be repositioned with relative ease due to the absence of a storage hopper. In particular, the absence of a storage hopper provides a measure of portability to the loading system  10 , and can facilitate movement of the loading system  10  between different locations within the refinery (or between different refineries) with a minimal expenditure of time and effort in comparison to conventional loaders. Portability and ease of use for the user of the loading system  10  is further enhanced when the loading system  10  is used in conjunction with portable storage bins, e.g., known as “totes,” which are normally built to hold approximately 2,000 pounds (approximately 900 kilograms) of catalyst and/or additive. 
     The absence of a storage hopper, it is believed, can also minimize the amount of time necessary to install the loading system  10  in relation to conventional loaders. The ability to install the loading system  10  in a minimal amount of time can be particularly beneficial, for example, where the use of the loading system  10  is required on an immediate basis to comply with a particular regulatory standard. 
     The loading system  10  can be used to inject different types of catalyst and/or additives with no mechanical reconfiguration, and without the need to unload and reload a storage hopper. In particular, the loading system  10  can inject one type of catalyst and/or additive from one of the storage bins  37 , and can immediately thereafter inject another type of catalyst from another of the storage bins  37  by manipulating the valves  42  in the appropriate manner. Of course, the loading system  10  can also be used to load product stored in just one storage bin. In any event, the need for multiple loaders to inject different types of catalyst and/or additives can thus be eliminated through the use of the loading system  10 . It is believed that that substantial savings in time, labor, refinery space, and money can be achieved by eliminating the need to purchase, install, and maintain multiple loaders each dedicated to a particular type of catalyst and/or additive. 
     Eliminating multiple loaders and employing the invention also eliminates multiple lines from the loaders being connected to the catalyst and/or additive addition line of the FCC unit, and in particular the catalyst and/or additive addition line to the FCC unit&#39;s regenerator. Having multiple lines routed into the catalyst and/or additive addition line can lead to blockages at the point where the multiple lines converge, or causes blockages close thereto. Typical embodiments of the invention, however, are designed to have only one supply line exiting the loading system and to be connected to the catalyst and/or additive addition line of the FCC unit, and therefore does not provide a routing configuration that leads to the aforementioned blockages. 
     Eliminating the use of a storage hopper can also reduce the amount of moisture to which the catalyst and/or additive is exposed. In particular, the use of the loading system  10  permits the catalyst and/or additive to remain in the storage bins  37  until a point immediately prior to its injection into the regenerator  14 . The environment in the storage bins  37 , it is believed, can be controlled more closely than that within a storage hopper. In particular, catalyst and/or additive is typically exposed to plant air when being transported to and stored in a hopper. Plant air is often a source of moisture, oil based products, or other contamination that can adversely affect catalyst and/or additive. Hence, minimizing the exposure of the catalyst and/or additive to plant air, as in the loading system  10 , can reduce the potential for contamination of the catalyst and/or additive. Reducing such contamination also reduces the catalyst and/or additive from agglomerating or clumping together. Such agglomeration makes the catalyst and/or additive less fluid, and can lead to plugging of hoses and supply lines. The invention thereby helps insure that the catalyst remains fluid as it is transported through the system. 
     As a result of the invention reducing contamination and inadvertent water absorption, the invention can be employed to load and/or transport hygroscopic material wherein it is desirable to process, handle and deliver such material with little increase in water uptake. By “hygroscopic”, it is meant having the property of absorbing atmospheric moisture. Hygroscopic materials include, but are not limited to, food products, pharmaceuticals and industrial chemicals, as well as catalyst and/or additives, e.g., FCC catalysts and/or additives. The invention is also suitable for delivering materials that are formulated or otherwise possess pyrophoric properties when used, e.g., spark or flame inducing. 
     For the purpose of understanding such uses, one can refer to earlier descriptions relating to delivering catalyst and/or additive and apply those teachings when using the invention to store, process, handle and/or deliver hygroscopic or pyrophoric material. For example, it is envisioned that the invention be can used to transport and/or deliver hygroscopic material and pyrophoric material to delivery vehicles, reactor units, mixers, or storage containers designed for delivery of the materials to individual consumers of the relevant product. 
     The pressurized volume loading system  10  is believed to be less than that of conventional loaders of comparable capacity. Hence, less pressurized air is required to operate the loading system  10  in comparison to conventional loaders. This feature can reduce the operating cost of the loading system  10  in relation to conventional loaders. For example, in instances where multiple conventional loaders are employed in a plant, consumption of pressurized plant air can be significant, especially when multiple conventional loaders are being operated simultaneously. Indeed, there can be large pressure drops when simultaneously using multiple loaders of the conventional type. Such pressure drops can lead to incomplete delivery of catalyst and/or additive, as well detrimentally affect the performance of other plant operations that employ plant air. These pressure drops, however, can be avoided when using typical embodiments of the invention. 
     The loading unit  14  is substantially isolated from sources of pressurized air as the catalyst and/or additive is transferred thereto, due primarily to the use of a vacuum to transfer the catalyst and/or additive. Hence, the potential for the readings of the load cells  56  to be biased by forces induced by pressurized air is believed to be minimal. (Some types of conventional loaders, as discussed above, transfer catalyst and/or additive under pressure from a storage hopper to a transport unit. The pressurized air used effect the transfer can adversely affect readings of the transfer pot&#39;s weight.) 
     The foregoing description is provided for the purpose of explanation and is not to be construed as limiting the invention. While the invention has been described with reference to preferred embodiments or preferred methods, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Furthermore, although the invention has been described herein with reference to particular structure, methods, and embodiments, the invention is not intended to be limited to the particulars disclosed herein, as the invention extends to all structures, methods and uses that are within the scope of the appended claims. Those skilled in the relevant art, having the benefit of the teachings of this specification, may effect numerous modifications to the invention as described herein, and changes may be made without departing from the scope and spirit of the invention as defined by the appended claims. 
     PARTS LIST 
     
         
         Loading system  10   
         System  11  for storing and loading catalyst and/or additives 
         Loading unit  14   
         Dust collector  16   
         Upper portion  16   a  (of dust collector  16 ) 
         Lower portion  16   b    
         Sidewall  17  (of dust collector  16 ) 
         Transfer pot  18   
         Cabinet  19   
         Base  19   a  (of cabinet  19 ) 
         Legs  20  (on loading unit  14 ) 
         Opening  23  (in lower portion  16   b ) 
         Screen  24   
         Cover  25   
         Internal volume  26  (within dust collector  16 ) 
         Vacuum producer  30   
         Filter  32   
         Hatch  33  (in dust collector  16 ) 
         Brackets  34   
         Hose  35   
         Valve  36   
         Actuator  36   a  (of valve  36 ) 
         Storage bins  37   
         Hoses  38   
         Arrows  39   
         Pipe guides  40   
         Valve  42   
         Actuator  42   a  (of valve  42 ) 
         Valve  43   
         Seat  44   
         Plug  45  (of valve  43 ) 
         Piping  46   
         Flexible section  46   a  (of piping  46 ) 
         Valve  48   
         Actuator  48   a  (of valve  48 ) 
         Volume chamber and moisture trap  49   
         Internal volume  50  (within transfer pot  18 ) 
         Sidewall  51  (of transfer pot  18 ) 
         Opening  53  (in lower portion  18   a  of transfer pot  18 ) 
         Piping  54   
         Flexible section  54   a  (of piping  54 ) 
         Valve  55   
         Actuator  55   a  (of valve  55 ) 
         Load cells  56   
         Plate  57   
         Piping  58   
         Valve  59   
         Controller  60   
         Brackets  61   
         Jack assemblies  62   
         Shafts  62   a  (of jack assemblies  62 ) 
         Nuts  62   b    
         Control panel  64  (of controller  60 ) 
         Arrows  65   
         First pressure transducer  68   
         Second pressure transducer  70   
         Third pressure transducer  72   
         Manifold  74   
         Manifold  100   
         Pipe guides  102 . 
         Discharge pipe guide  104   
         Pipe guides  110