Abstract:
A measurement device for measuring the elevation of particles in a vertical tube, including a reel, means for driving said the in forward and backward directions, a cable wound onto the reel and having a free end, a sensor mounted on the free end of the cable, the sensor including a particle contact portion, and trigger means responsive to the particle contact portion&#39;s contacting the particles in the tube.

Description:
[0001]    This application is a divisional of U.S. patent application Ser. No. 12/331,477, filed Dec. 10, 2008, which claims priority from U.S. Provisional Application Ser. No. 61/007,144 filed Dec. 11, 2007. 
     
    
     BACKGROUND 
       [0002]    It is often important to be able to load particles, such as catalyst particles, to the correct elevation in the tubes of a vertical tube chemical reactor. This can become even more critical when the tubes require special loading, with catalyst particles at certain elevations and inert spacer particles in other specific elevations or with different types of catalyst particles at different elevations. 
       SUMMARY 
       [0003]    The present invention provides an arrangement for precision loading of particles at the correct elevations within the tubes of a vertical tube chemical reactor that is accurate and treats the particles gently, avoiding damage to the particles during dispensing and measurement. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a schematic, partially broken away, section view of a chemical reactor vessel including a loading arrangement made in accordance with the present invention; 
           [0005]      FIG. 2A  is a partially broken away, side view of the loading arrangement of  FIG. 1 ; 
           [0006]      FIG. 2B  is the same view as  FIG. 2A , but with the framework removed for clarity; 
           [0007]      FIG. 3  is an enlarged schematic section view of a sensor from  FIG. 2B ; 
           [0008]      FIG. 4A  is a side view of the sensor of  FIG. 3  as it is being inserted into a reactor tube; 
           [0009]      FIG. 4B  is the same view as  FIG. 4A  but showing the sensor having made contact with the particles in the reactor tube; 
           [0010]      FIG. 4C  is a view along line  4 C- 4 C of  FIG. 4A ; 
           [0011]      FIG. 4D  is a view along line  4 D- 4 D of  FIG. 4B ; 
           [0012]      FIG. 5  is the same view as  FIG. 2B  but with the sensor extending into one of the reactor tubes and with the plate closing off the feed from the dispensing bin to the conveyor belt; 
           [0013]      FIG. 6  is the same view as  FIG. 5  but with the sensor retracted and the reactor tube fully loaded with particles; 
           [0014]      FIG. 7  is a schematic front view of the arrangement of  FIG. 2B  with one reactor tube full and the next adjacent tube still filling; 
           [0015]      FIG. 8  is a schematic top view of the mounting support for the bin of  FIG. 2A ; 
           [0016]      FIG. 9  is a schematic front view of the mounting support of  FIG. 8 ; 
           [0017]      FIG. 10  is a schematic top view of the plate from  FIG. 8 ; 
           [0018]      FIG. 11  is a schematic top view of the end of the belt and the funnels of the arrangement of  FIG. 2B ; 
           [0019]      FIG. 12  is a view similar to  FIG. 2B , but for a different embodiment of a loading arrangement, with the tubes being loaded with particles; 
           [0020]      FIG. 13  is the same view as  FIG. 12 , but with the diverter plate sending the particles to the collection bin and the sensor in position to be deployed; 
           [0021]      FIG. 14  is the same view as  FIG. 13  but with the sensor deployed to determine the elevation of particles in the tube; 
           [0022]      FIG. 15  is a view similar to  FIG. 2B , but for a different embodiment of a loading arrangement, with the tubes being loaded with particles; 
           [0023]      FIG. 16  is the same view as  FIG. 15 , but with the diverter mechanism sending the particles to the collection bin and the sensor deployed to measure the elevation of particles in the tube; 
           [0024]      FIG. 17  is an enlarged schematic section view of an alternate embodiment of a sensor as it is inserted into a reactor tube, which may be used with any of the loading arrangements disclosed; 
           [0025]      FIG. 18  is the same view as  FIG. 17  but showing the sensor having made contact with the particles in the reactor tube; 
           [0026]      FIG. 19  is a view similar to that of  FIG. 16  but for a different embodiment of a loading arrangement; 
           [0027]      FIG. 20  is a side view of a catalyst container; 
           [0028]      FIG. 21  is a front view of the catalyst container of  FIG. 20 , secured to a magazine by means of a strap; and 
           [0029]      FIG. 22  is a side view of the catalyst container and magazine of  FIG. 21 . 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  depicts a typical chemical reactor vessel  10 , which is a vertical shell and tube heat exchanger, having an upper tubesheet  12  and a lower tubesheet  14  with a plurality of vertical tubes  16  welded or expanded to the tubesheets  12 ,  14  to form a tightly packed tube bundle. There may be from one to many hundreds or even thousands of tubes  16  extending between the tubesheets  12 ,  14 . Each tube  16  has a top end adjacent the upper tube sheet  12  and a bottom end adjacent the lower tubesheet  14 . The vessel  10  includes a top dome (or top head)  13  and a bottom dome (or bottom head)  15 , as well as manways  17 ,  18 ,  20  for access to the tubesheets  12 ,  14  inside the vessel  10 . The manways are closed during operation of the reactor but are opened for access, such as during catalyst handling. In this instance, the tubes  16  are filled with catalyst particles (not shown in this view), which facilitate the chemical reaction. However, similarly-shaped shell and tube vessels may be used for other purposes, such as for a boiler or other heat exchanger, and the particles may be inert spacers or other particles besides catalyst particles. 
         [0031]    Reactors have either fixed or removable heads. In this embodiment, the heads are fixed, and they include manways  17  and  18  at the top and  20  at the bottom. 
         [0032]    This particular reactor vessel  10  is fairly typical. Its tubes can range in length from 5 feet to 65 feet, and it is surrounded by a structural steel skid or framework  22 , which includes stairways or elevators (not shown) for access to the tubesheet elevations of the reactor vessel  10  as well as access to intermediate elevations and to a topmost elevation which may be located at or near the elevation of the top opening  18  of the reactor vessel  10 . On a regular basis, which can be every 2 to 48 months or longer, as the catalyst becomes less efficient, less productive, or poisoned, it is changed out, with some or all of the old catalyst being removed and a new charge of catalyst being installed in the tubes  16  of the reactor vessel  10 . Catalyst handling also can occur on an unplanned and undesirable schedule. 
         [0033]    A catalyst change operation requires a complete shutdown of the reactor, resulting in considerable lost profits due to lost production. (The disclosed invention can be used not only for catalyst change operations but also on new reactors and tubes for their initial catalyst loading.) It is desirable to minimize the amount of time required for the catalyst change operation and yet the catalyst loading operation must be done carefully to ensure proper loading of the catalyst or other particles in the tubes  16  as these particles have a tendency to bridge and create voids inside the reactor tube if they are loaded improperly.  FIG. 1  also schematically depicts an example of a particle loading arrangement  24  made in accordance with the present invention. 
         [0034]    Referring now to  FIG. 2A , this particular particle loading arrangement  24  is skid mounted on a framework  26  which can be broken down readily into subassemblies  28 ,  30  which can be handled easily, especially for introduction into the top head  13  via one of the manways  17 ,  18 . In this embodiment, the framework  26  includes a top subassembly  28 , which rests atop the bottom subassembly  30 . These two subassemblies  28 ,  30  may be temporarily held together via fasteners (not shown) such that they may be moved as a unit when assembled inside the top head  13  of the reactor vessel  10 . Of course, the framework  26  may include any number of subassemblies as may be desired for ease of handling and in order to fit through the manways to introduce the loading arrangement  24  into the reactor head  13 . 
         [0035]    Vertical tube chemical reactors typically have rows of reactor tubes extending between upper and lower tube sheets with the alternate rows being offset from each other so that the tubes lie on an equilateral triangular pitch.  FIG. 2B  is a side view, partially in section, of a particle loading arrangement  24  and shows the upper tube sheet  12  and several different tubes  16   a ,  16   b ,  16   c ,  16   d ,  16   e ,  16   f ,  16   g  which lie on several different respective rows  116   a ,  116   b ,  116   c ,  116   d ,  116   e ,  161   f ,  116   g . This loading arrangement is intended to advance from row to row, loading several tubes within a row at a time. In this particular case, ten adjacent tubes  16   c  along the row  116   c  have just been loaded, and the device is now in the process of loading ten adjacent tubes  16   b  in row  116   b . After these tubes  16   b  have been loaded, the device will advance further left to load ten of the tubes  16   a  in row  116   a , and so forth. Thus, while  FIG. 2B  shows only one of the tubes  16  in each row  116 , it is understood that the device actually is loading ten tubes  16  in each row as it advances from one row to the next. 
         [0036]    This loading arrangement includes several components, as is best appreciated in  FIG. 2B . There is a dispensing bin  32 , which holds a supply of particles and dispenses them for loading into the tubes. There is a wide conveyor belt  34 , which spans the distance of the ten adjacent tubes  16  and conveys the particles from the dispensing bin  32  to the ten reactor tubes  16  along a row  116 . In this view, the loading arrangement  24  currently is loading ten adjacent tubes  16   b  in row  116   b . There is a measuring system  36 , which includes a plurality of sensors  66  on reels  60  to independently measure the elevation (or level) of particles  21  in each of the ten tubes  16   b , and there are ten individual diverter plates  58 , which divert falling particles  21  away from their respective tubes  16   b  and into a collection bin  40  (as depicted in  FIG. 6 ) once the respective tube  16   b  has been loaded to the desired elevation. 
         [0037]    It should also be pointed out that the particle loading arrangement  24  may be designed and installed with some of its elements being outside the dome  13  of the reactor vessel  10 . For instance, the dispensing bin  32  may be mounted outside the reactor vessel  10 , and the conveyor belt  34  may extend through the manway  17  and into the reactor dome  13  with the motor  52  and belt drive  48  for the belt  34  being located either inside or outside of the reactor vessel  10 . 
         [0038]    The magazine closure at the bottom of the dispensing bin  32  is shown in more detail in  FIGS. 8 ,  9 ,  21 , and  22 . The bin  32  is open at the bottom and is secured by a strap  88  to a rail  42 , which is received in a support panel  43  that is secured to the top subassembly  28 , as by welding. A sliding shut-off plate  44  (See also  FIG. 10 ) is also supported on the rail  42  and can be slid in and out, acting as a guillotine-type gate, to regulate the size of the opening through which particles fall onto the belt  34 . This sliding shut-off plate  44  is shown in the closed-off position in  FIGS. 2A and 5 , and is shown in a partially open position in  FIGS. 2B ,  6 , and  12 - 14 . The position of this plate  44  is controlled by a central processor which controls a linear actuator (not shown) connected to the plate  44 . A sensor  45  senses the position of the plate  44  and communicates that information to the central controller.  FIG. 2B  depicts the shut-off plate  44  in a partially open position to allow the flow of particles out of the dispensing bin  32  and onto the belt  34 . 
         [0039]    Stationary V-shaped divider plates  38  (Seen in  FIGS. 2A and 11 ) are located between the dispensing bin  32  and the belt  34 , either resting directly on the belt  34  or preferably being mounted at an elevation just slightly above the belt  34 . These divider plates  38  are oriented substantially in the direction of travel of the belt and serve to divide the flow of particles along the belt into ten lanes, each aligned with its respective tube  16 . 
         [0040]    The divider plates  38  or other device in contact with the belt  34 , such as a roller (not shown) in contact with the bottom surface of the belt  34  also may be attached to a vibratory motor  46  (Shown in  FIG. 11 ) such as the type found in cell phones, using a rotating eccentric mass of sufficient size and vibratory force capacity to fluidize the particles on the belt to help them adequately segregate into a proper volume on the belt  34 , to help ensure that the volume along the belt  34  remains substantially constant and with a consistent packing density. The vibratory motor  46  may also be attached to the top of the divider plates  38  by means of a horizontal bar, as shown in  FIG. 11 , and located perpendicular to them in such a manner to form a weir  47 , or gate, to regulate the height and therefore the volume of particles on the belt  34 . Alternatively, a separate, non-vibratory weir  47  may be used. 
         [0041]    The conveyor belt  34  is driven by a drive roller, which is driven by a drive belt  48 , which extends around pulleys  50  and is driven by a motor  52 , the speed of which is controlled by the central controller. 
         [0042]    There are ten funnels  54 , one funnel  54  in each of the tubes  16   b  that are being loaded, and the end of the conveyor belt  34  is aligned with the openings in the funnels  54  so that the particles  21  falling off the end of the conveyor belt  34  fall into the funnels  54  and into the tubes  16   b.    
         [0043]    The funnels  54  are mounted on a movable frame  31  that is connected to the frame  30  of the loading device  24  so they can be raised and lowered together, raising them to remove them from one row of tubes  16   b , for example, and then advancing the loading device  24  and then lowering the funnels  54  into the next set of tubes  16   a . The movable frame  31  may be moved manually by an operator shifting a lever, or it may be moved automatically by a central processor that controls an actuator connected to both the movable frame  31  and the frame  30 . 
         [0044]    When it has been determined that a particular tube  16   b  has been filled to the desired height, or when it is otherwise desired to stop loading a particular tube, its respective actuator  56  actuates its respective diverter plate  58 , pivoting the diverter plate  58  toward the conveyor belt  34  to the diverting position shown in  FIG. 6 , diverting the particles  21 , that would otherwise fall into that tube  16   b , into the collection bin  40 .  FIG. 7  shows two of the diverter plates  58 , with the diverter plate  58  on the right side in the diverting position and the diverter plate  58  on the left in the non-diverting position. The other eight diverter plates  58  and their respective actuators  56  are not shown here, but it is understood that there is one for each tube  16   b  that is being filled and that each actuator  56  is independently controlled by the central controller. Once the ten tubes  16   b  have all been filled, the plate  44  is slid to the closed position, as shown in  FIG. 5 , and the conveyor belt  34  is stopped. Then the device is advanced to the next row  116   a  of tubes  16   a  to load those tubes  16   a  in the same manner. 
         [0045]    The measuring arrangement  36  for each tube being loaded includes a reel  60 , a wire cable  62 , an encoder  64 , and a sensor  66 . The sensor  66  is shown in more detail in FIGS.  3  and  4 A- 4 D and is explained in more detail below. 
         [0046]    As shown in  FIG. 3 , the wire cable  62  includes a ground wire  68  and a power cable  70 , which support a weight  72 . The ground wire  68  is electrically connected to a spring  74 . The upper end of the spring  74  is suspended from the weight  72 , and the lower end of the spring  74  defines a downwardly-projecting extension  76  which projects below a rubber boot  78  which partially encases the spring  74 . 
         [0047]    A pin  80  is electrically connected to the power cable  70 , is suspended from the weight  72 , and is centered inside the spiral spring  74 , as shown in  FIGS. 3 and 4C . 
         [0048]    Each wire cable  62  is wound onto its respective reel  60 , which is controlled by a motor including an encoder  64 . This powered reel  60  is controlled by the central controller as well as being calibrated and indexed to quantify the length of wire  62  that has played out as the sensor  66  is lowered into the tube in order to know the elevation of the sensor  66  at all times. 
         [0049]    As the sensor  66  is being lowered into the reactor tube  16   b , as shown in  FIGS. 4A and 5 , the pin  80  extends axially through the spring  74 , and the pin  80  does not make contact with the spring  74 . 
         [0050]    As the sensor  66  is lowered further, the extension  76  of the spring  74  makes contact with the particles  21 , as seen in  FIG. 4B . With a slight additional downward movement of the weight  72 , the extension pushes the lower portion of the spring  74  sideways, which moves the spring  74  into contact with the pin  80 , as shown in  FIG. 4D . This completes an electrical circuit, acting as a switch or trigger which signals that the sensor  66  has reached the level of the particles  21 . The closing of this switch is registered by the encoder  64 , which sends a signal to the central controller to indicate the elevation (or level) of particles  21  in that tube  16   b.    
         [0051]    The switch may be connected to an operational amplifier triggering circuit, not shown but well understood in the field of electronics, which serves as the input to a flip-flop circuit that can be read as a digital input/output and then reset as desired. The flip-flop circuit can be tuned to ensure that the sensor  66  has actually touched the particles  21  so as not to give false particle level indications. 
       Operation: 
       [0052]    In order to operate this loading arrangement  24 , the dispensing bin  32  is loaded with particles  21 , the funnels  54  are aligned with and inserted into the tubes  16   b  to be loaded within the row  116   b , and a button is pushed to turn the device on to begin loading. This causes the central processor to turn on the motor  52  and slide the shut-off plate  44  outwardly, as shown in  FIG. 2B , to create the desired size of opening for dispensing the particles from the bin  32 . The particles  21  fall onto the conveyor belt  34 , being divided into separate, substantially equal volume streams by the dividers  38  and the vibrating weir  47 . The height of the weir  47  above the belt  34  preferably is adjusted to allow only a single layer of particles to continue on the belt  34  in order to help ensure a uniform density of particles  21  to permit each funnel  54  to feed its corresponding tube  16   b  without causing bridging in the tube  16   b . Any excess particles  21  rejected by the weir  47  will fall into the collection bin  40  for later reuse. 
         [0053]    As the particles  21  reach the end of the belt  34 , they fall off the end of the belt  34  and into the funnels  54 . The particles  21  then flow through the funnels  54  and into the respective tubes  16   b.    
         [0054]    The central controller is programmed to close the plate  44  and stop the belt  34  at a preset time before loading is completed. Preferably, the time is set to correspond with the tubes  16  being loaded approximately to 80%-90% completion. Then, the central controller causes an elevation measurement of the particles  21  to be taken in each tube  16   b  that is being loaded. In this embodiment, this measurement is accomplished by lowering a sensor  66  into each tube  16   b  being loaded. As the cable  62  plays out, the encoder  64  keeps track of how much cable  62  has played out so as to determine the exact position of the sensor  66  at all times. Once the sensor  66  makes contact with the particles  21  in the tube  16   b  (See  FIG. 4B ), the spring  74  is deflected until it makes contact with the pin  80  (See  FIG. 4D ), signaling the central processor that the sensor has reached the elevation of the particles  21  in the tube  16   b . The central processor captures the length of cable  62  which has been played out as indicated by the encoder  64 , which corresponds to an elevation of particles  21  in the tube  16   b.    
         [0055]    Based on the feed rate (indicated by the sensed position of the plate  44 ) and the time it took to reach that elevation, the processor calculates what is needed to complete the loading of the tube  16   b  to the desired target elevation. This calculation can be as simple as a calculation of how much longer the belt  34  has to run in order to complete loading that tube, or it can calculate both a new feed rate as well as an additional time based on this new feed rate. Therefore, the calculation may assume either a constant feed rate of the particles or an adjustable feed rate. In both instances, the feed rate is a controlled feed rate. It generally is preferable to maintain a constant feed rate. 
         [0056]    Then, the central controller causes the elevation sensor  66  to be pulled out of the tube  16   b  by reversing the direction of rotation of the reel  60 , and, once the elevation sensor  66  is out of the way (as shown in  FIG. 2B ), the central controller causes the belt  34  to begin moving again and the plate  44  to be slid open again, to resume loading particles  21 . As the remaining time for each tube  16   b  elapses, the controller causes its respective actuator  56  to actuate its respective diverter plate  58  (as shown in  FIG. 6 ), altering the particle flow path from the original path, which sent particles from the bin  32  to the tube  16   b , to a second path, diverting those particles to the collection bin  40 , which stops the loading for that tube  16   b , while the conveyor belt  34  continues to run and one or more other tubes continue to be loaded. Once the calculated time has elapsed for all the tubes  16   b  being loaded, the central controller causes the plate  44  to be closed and the belt  34  to be stopped. 
         [0057]    The central controller may then cause the elevation sensors  66  to be lowered again to measure the elevation of particles  21  in each tube  16   b  to ensure that the tubes are loaded to the correct elevation. If more loading is needed, the central controller may cause loading to continue for one or more tubes, as desired, with the other lanes having their diverter plates  58  actuated. Since it is easy to correct by adding particles and more difficult to correct by removing particles, this system may be deployed conservatively to avoid overloading. 
         [0058]    The particles in the collection bin  40  may periodically be poured into the dispensing bin  32  by manually opening the lid  84 , pouring in the particles, and then closing the lid  84 . 
         [0059]    Once the correct elevation of particles has been reached in all the tubes  16   b , the central controller causes the funnels  54  to be raised. The operator then positions the loading device over the next group of tubes  16   a  to be loaded, the funnels  54  are lowered, and the process is repeated until all the tubes are loaded to the desired elevation. 
         [0060]    Laser tracking of the position of the loading device  24  may be done automatically as part of the automated sequence by means of a laser measuring device mounted on the loading device  24 . The laser measuring device reflects a light beam off of a reflector at a known position within the reactor vessel and the distance to the reflector is used to automatically determine the position of the loading device  24  and which tubes are being loaded. The elevation measurement data, loading times, plate position, belt speed, and other related data may be associated with and recorded for each tube in a similar manner to that in which the position and data were recorded for the tubes in U.S. Pat. No. 6,725,706, which is hereby incorporated herein by reference. This device also may transmit its data to a remote location in real time, as described in that referenced patent, and the data for each tube may be reported graphically at the remote location as described in that patent. The process described above may be repeated for each layer of particles in the tubes  16 . 
         [0061]    The device described above may be mounted on wheels, on a skid plate, or in some other manner that permits it to be supported on the upper tube sheet  12  and moved from place to place along the upper tube sheet  12 . It also may have locator pins (not shown) that may be inserted into holes in the tube sheet  12  in order to help align it with the tubes to be loaded. Alternatively, the funnels  54  may be used to align the device  24  with the reactor tubes. It should be noted that, once the particle loading arrangement  24  (or any of the alternate embodiments described herein) has been aligned with a row of tubes, the operator just pushes a button (or otherwise signals the processor) to begin the sequence which will automatically run, with no further input required from the operator, until the particle loading arrangement  24  has properly filled that batch of tubes. 
         [0062]    It should also be noted that, if for any reason a tube  16   b  in a row  116   b  is not to be loaded with particles (for instance, the tube  16   b  may have been permanently plugged, it may need to be hand loaded because it is a thermocouple location, or it may correspond to a tubesheet support), then the diverter plate  58  associated with that particular tube  16   b  may be left in the diverting position shown in  FIG. 6  to divert the particles away from the tube  16   b  and into the collection bin  40  while the other tubes in the group are being loaded. 
       Alternate Embodiments 
       [0063]      FIGS. 12 ,  13 , and  14  depict an alternate embodiment of a particle loading arrangement  24 ′ made in accordance with the present invention. A comparison of  FIG. 12  with  FIG. 2B  shows that the difference is that in this embodiment the measuring system  36  has been repositioned from a position that is substantially vertically above the actuator  56  in  FIG. 2B  to a position that is at a lower elevation than the actuator  56  and is offset forward of the actuator  56 . 
         [0064]    This reconfiguration allows the sensor  66  to be deployed to take a reading of the particle elevation in the tube  16   b  being loaded without interrupting the flow of particles from the dispensing bin  32  or along the conveyor belt  34 . As shown in  FIG. 13 , when it is desirable to check the elevation of particles  21  in the tube  16   b , the controller causes the actuator  56  to move the diverter plate  58  such that the diverter plate  58  deflects the particles falling from the conveyor belt  34  away from the funnel  54  and into the collection bin  40 . In this embodiment, the cable  62  that is connected to the elevation sensor  66  extends through a pulley mounted on the diverter plate  58 , so that movement of the diverter plate  58  to the deflection position depicted in  FIG. 13  also places the sensor  66  in a position directly above the funnel  54 . 
         [0065]    Therefore, in this embodiment of a loading arrangement  24 ′, the flow of particles  21  from the dispensing bin  32  and the flow of particles on the conveyor belt  34  are never disrupted or changed. Instead, when it is time to take a reading of the elevation of the particles  21  in the tube  16   b , the path of the particles is altered from a first path, which led from the bin  32  to the tube  16   b , to a second path, which sends the particles  21  away from the tube  16   b  and to a collection bin  40 . In this embodiment  24 ′, this is accomplished by a diverter plate  58  which simultaneously diverts the particles  21  to the collection bin  40  and places the sensor  66  is position to be deployed into its respective tube  16   b . (As will be appreciated in embodiments described later, other means may be used to alter the path of the particles  21  away from the inlet of the tube  16   b .) 
         [0066]    In  FIG. 14 , the elevation sensor  66  has been deployed to measure the elevation of particles  21  in the tube  16   b . The shut-off plate  44  in the dispensing bin  32  is still in its open position, allowing particles  21  to continue to flow onto the conveyor belt  34 . Furthermore, the particles  21  continue to flow along the conveyor belt  34 , but the particles for this particular lane are now being diverted into the collection bin  40  by their respective diverter plate  58 . This allows the elevation of particles  21  in the tube  16   b  to be measured without changing any of the settings. This helps maintain a constant feed rate of the particles  21  in the loading arrangement  24 ′ so that, once the diverter plate  58  is returned to its non-diverting position, the particles  21  will resume being fed at the same rate as before, with no change at start-up that might occur if the belt had been stopped and started instead of just diverting the flow of particles. This also allows the elevations of different tubes to be measured at different times, as desired, while particles continue to flow along with the moving belt  34 . 
       Operation of this Alternate Embodiment 
       [0067]    In order to operate this loading arrangement  24 ′, the dispensing bin  32  is loaded with particles, the funnels  54  are inserted into the tubes  16   b  to be loaded within the row  116   b , and the motor  52  is turned on. The shut-off plate  44  is slid outwardly, as shown in  FIG. 12 , to create the desired size of opening for dispensing the particles from the bin  32 , and the particles fall onto the conveyor belt  34 , being divided into separate, substantially equal volume streams by the dividers  38  and vibrating weirs  47 . 
         [0068]    If desired, a constant flow rate of the particles  21  may first be established by diverting the particles  21  into the collection bin  40  for a period of time before beginning to load the tubes. (This could be done in other embodiments, as well, if desired.) Once a constant flow rate has been established, the diverter plates  58  are moved to their vertical, non-diverting position (as shown in  FIG. 12 ), and the particles begin to flow into the tubes  16   b.    
         [0069]    The central controller starts a timer the instant the diverter plates  58  are shifted to the non-diverting position to allow the particles  21  to flow into the tubes  16   b . After a user-determined amount of time has elapsed (estimated to be the amount of time required for the tubes  16   b  to be 80% to 90% loaded), the actuators  56  move the diverter plates  58  so as to divert the particles  21  into the collection bin  40 , and a sensor  66  is reeled down into its respective tube at each tube location to take a measurement reading of the elevation of particles  21  in each respective tube  16   b . These readings are compared with the desired setpoint elevation, and an algorithm converts the ratio (of actual reading to desired reading) into a very accurate estimate of the additional loading time required, at the constant flow rate, to reach the desired setpoint for each tube  16   b . That is, based on the time it took to reach that elevation, the computer calculates how much longer the particles must continue to flow in order to complete loading each individual tube. Each diverter plate  58  corresponding to each tube  16   b  which is being loaded is then returned to its vertical, non-diverting position (as shown in  FIG. 12 ) to allow particles  21  to continue to be loaded in the tube  16   b  for the calculated additional loading time required to reach the fully loaded condition. 
         [0070]    Since, in this operating condition, the position of the shut-off plate  44  and the speed of the conveyor belt  34  remain unchanged, the particle flow rate remains constant, so the calculation as to the remaining time required to reach the setpoint (the desired elevation) for each tube  16   b  can be made very precisely, very accurately, and with a very high degree of repeatability. 
         [0071]    As the remaining time for each tube  16   b  elapses, its respective actuator  56  actuates its respective diverter plate  58  back to the diverting position shown in  FIG. 13 , stopping the loading for that tube  16   b  and diverting the particles  21  for that particular tube  16   b  into the collection bin  40 . At that point, the sensor  66  for that tube  16   b  may be lowered again to measure the elevation of particles in that tube to ensure that the tube is properly loaded. If additional loading is needed, the diverter plate  58  may be returned to the non-diverting position, and loading may continue for a desired period of time. Once it is confirmed that the correct elevation of particles  21  has been achieved for each tube  16   b  being loaded, the plate  44  is closed and the belt  34  is stopped. 
         [0072]    An algorithm may be used by the central controller to compare the particle elevation of each tube  16   b  (either in the intermediate measurement or at the final measurement elevation, or both) against one or more parameters (such as the overall mean, the highest elevation, the lowest elevation, the elevation of the adjacent tubes, etc.) and, if a deviation of more than a target amount (for instance, a deviation from the overall mean of more that 5%) is detected, a warning may be raised to flag the particular tube with an out-of-range reading. For instance, an excessively low reading could indicate an “open tube” condition wherein the retaining spring at the bottom of the tube was inadvertently omitted, causing the particles to fall right through the problem tube. Likewise, an excessively high reading may indicate a partially plugged tube or a tube which has experienced a bridging of the particles as it is being loaded into the problem tube. 
         [0073]    If the position of the shut-off plate  44  is consistently open to the same extent, and the speed of the conveyor belt  34  is also consistently set at the same speed, then the steady state flow rate should also be very consistent and repeatable as the loading arrangement  24 ′ is moved from one row of tubes  116   b  to the next row of tubes  116   a . In this instance, the calculations to compare the particle elevation in the tubes  16   b  may be made not only against the other tubes being loaded at the same time, but also against the tubes that were loaded previously or even against the entire population of tubes being loaded, even if other tubes are being loaded by a different loading arrangement  24 ′ (as long as its settings of conveyor belt  34  speed and shut-off plate  44  opening are the same). 
         [0074]      FIGS. 15 and 16  depict an alternate embodiment of a loading arrangement  24 ″ made in accordance with the present invention. This new embodiment  24 ″ is very similar to the embodiment  24  described earlier and depicted in  FIGS. 2B and 5 . The most significant difference is that the funnel  54 ′ is much taller, reaching almost to the point where the particles  21  fall off of the conveyor belt  34 . Furthermore, the funnel  54 ′ is skewed to the right, and it incorporates the actuator  56 ′ and the diverter plate  58 ′ right into the funnel  54 ′. 
         [0075]    The operation of this loading arrangement  24 ″ is quite similar to that of the loading arrangement  24 ′ described earlier, in that the shut-off plate  44  in the dispensing bin  32  and the conveyor belt  34  may continue to operate during the process of taking an elevation measurement of the particles  21  in the tube  16   b  being loaded, as depicted in  FIG. 16 . The path of the particles  21  is altered by opening the side of the funnel  54 ′, in a manner similar to that of a trap door by having the actuator  56 ′ move the diverter plate  58 ′ to the lowered position which allows the particles  21  to fall through the opening on the side of the funnel  54 ′ and into the collection bin  40 . This clears the way for the sensor  66  to be deployed into the tube  16   b  being loaded without the particles  21  interfering with the deployment, even though the steady state flow of the particles  21  remains uninterrupted. 
         [0076]      FIG. 19  depicts yet another embodiment of a loading arrangement  24 * made in accordance with the present invention. This embodiment  24 * is quite similar to the loading arrangement  24 ″ disclosed above, with the most significant difference being the elimination of the actuator  56 ′ and of the diverter plate  58 ′. In this embodiment  24 * the funnel  54 * is simply shifted such that the skewed portion of the funnel  54 * faces away from the conveyor belt  34  during the process of taking a measurement of the elevation of particles  21  in the tube  16   b  being loaded. The particles  21  simply fall directly into the collection bin  40  so as not to interfere with the deployment of the sensor  66 , even though the steady state flow of the particles  21  remains uninterrupted, as was the case with the loading arrangement  24 ″. 
         [0077]    The shifting of the skewed portion of the funnel  54 * may be accomplished by any number of means. For instance, the funnel  54 * may be rotated 180 degrees about its longitudinal axis to obtain the desired configuration. This could be achieved by a rotary actuator or manually. It is preferable for the movement to be automated so it can be controlled by the central controller in order for the central controller to accurately know the time period during which the tube is being filled. In another example, the conical mouth of the funnel  54 * may be hinged (like an accordion-like hinge of a drinking straw) at its stem to allow the funnel  54 * to shift (from the position shown in  FIG. 15  to that shown in  FIG. 19 ) without having to move its stem. The funnel  54 * could then be shifted automatically, as desired, by a mechanical linkage (not shown) or even by a non-mechanical linkage (such as by a puff of air, or by magnetic attraction and repulsion). 
         [0078]    The operation of this loading arrangement  24 * is substantially the same as that for the loading arrangement  24 ″ described earlier. The main difference is in the mechanism for altering the path of the particles  21 . In this embodiment  24 *, the mechanism for altering the path is simply the removal of a part of the original path to allow the particles  21  to fall directly into the collection bin  40 . 
         [0079]      FIGS. 17 and 18  depict an alternate of a sensor  66 ′ which may be used instead of the sensor  66  described above. The wire cable  62  includes a ground  68 ′ and a power cable  70 ′ which support a housing  78 ′. A guide  72 ′ is mounted to the housing  78 ′ and guides a rod  76 ′ for vertical movement relative to the housing  78 ′. A shorting plate  74 ′ is mounted on the rod  76 ′ for movement with the rod  76 ′, and a shorting pad  80 ′ is fixed within the housing  78 ′. The lowermost tip  82 ′ of the rod  76 ′ may be enlarged as shown to provide a larger surface for contacting the particles  21  and to provide protection for the rod  76 ′. 
         [0080]    As the sensor  66 ′ is being lowered into the reactor tube  16   b , the rod  76 ′ is in its lowermost position relative to the housing  78 ′, with the shorting plate  74 ′ resting on the shorting pad  80 ′ to complete the circuit. When the lowermost tip  82 ′ of the rod  76 ′ contacts the particles  21  within the tube  16   b  (as shown in  FIG. 18 ), the rod  76 ′ moves upwardly relative to the housing  78 ′, thereby breaking the contact between the shorting plate  74 ′ and the shorting pad  80 ′. The opening of this switch is registered by the central controller. The central controller then reverses the direction of rotation of the reel  60 , raising the sensor  66 ′ until the shorting plate  74 ′ again contacts the shorting pad  80 ′, closing the switch and serving as a trigger responsive to the sensor contacting the particles in the tube. The position that is indicated by the encoder  64  when the switch closes is recorded and indicates the elevation of particles  21  in that tube  16   b . It may therefore be seen that the operation of the measuring system  36  is substantially the same regardless of whether the sensor  66  or  66 ′ used. 
         [0081]      FIGS. 20-22  show how the dispensing bin  32  may actually be a catalyst container, which may be provided by the catalyst manufacturer and shipped to the customer packed with catalyst. This helps minimize handling of the catalyst particles, which is desirable since the catalyst can be friable and abrasive, and unnecessary handling can result in excessive dust and fines which can undesirably restrict gas flow in a given tube as well as creating other process problems such as localized and destructive exothermic heating. In this embodiment, the container  32  is a rectangular box with a lid  84 . (The container could be cylindrical or have other shapes, in which case the shapes of the mating parts would be changed accordingly.) In order to use the container  32  as a dispensing bin, it is flipped upside down and the bottom is removed, with a can opener for instance, and the magazine  86  is secured to the open end of the container  32  by means of a strap  88 . The magazine  86  includes the rail  42  and the guillotine plate  44 , which were described earlier. 
         [0082]    The dispensing bin/container  32  is then flipped right side up and, with the strap  88  keeping the magazine  86  secured over the open bottom of the bin, it is lowered into magazine support panel  43 , which is shown in  FIG. 2A . 
         [0083]    It will be obvious to those skilled in the art that modifications may be made to the embodiments described above without departing from the scope of the present invention. For instance, even though the description refers to taking particle elevation readings at approximately 80% to 90% of the desired final elevation, any number of intermediate particle elevation readings may be taken, and these readings may be at any desired estimated “percentage complete” elevation. Also, as was indicated earlier, some of the components of the particle loading arrangement may be installed outside the reactor vessel  10 , and the collection bin  40  may be replaced by a second conveyor belt to take any diverted particles to another location, such as back into the dispensing bin or out of the reactor vessel  10 .