Abstract:
A method for loading structured packing into a tower, such as a vacuum tower in a petrochemical plant. The system uses a removable slide positioned in a manway opening, wherein the structured packing is slid down to a bottom stage in the receiving area. The packing is then unloaded and stacked onto a distribution tray. As the packing reaches a pre-determined height, the bottom stage is repositioned on top of the structured packing. To accommodate the new angle and distance between the bottom stage and manway, a section of the slide is removed. While the slide is in use, its upper receiving area partially blocks the manway opening. To afford workers to capability to exit through the manway, the upper receiving area swings upward and away from the manway, and is stowed inside the tower.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to a system of loading structured packing into a tower. Specifically, the invention describes a system comprising a removable slide mechanism for internal placement and stacking of structured packing on distribution trays inside a process tower, such as a vacuum tower. 
     2. Related Art and Background Information 
     The art of using ramps and slides for transporting material has long been known. In the field of construction and maintenance, particularly in the petrochemical industry, material slides are used primarily for removing trash and demolished materials, where the effect on the material from being slid down a chute or slide does not matter. The present invention, however, is designed specifically to minimize the damage to specialized material, specifically structured packing material. 
     In the petrochemical industry, process towers, including vacuum towers, are used to promote liquid/vapor interfaces between different chemicals inside the tower during chemical processing. Typically, the liquid is sprayed or sprinkled downward inside the top portion of the tower, and continues to fall to the bottom of the tower due to gravity. At the same time, the lighter vapor from the interior bottom of the tower is forced upward, typically by a vacuum pulling from the top. As the heavier liquid and lighter vapors interface by passing across each other, a chemical reaction occurs, creating the desired product. 
     Located within the tower is packing that provides a greater interior surface area. This large area provides more surface to which the liquids and vapors each adhere, thus promoting their interaction and subsequent chemical reaction and/or bonding. The packing is often structured packing, which is comprised of structured packing sections, each section being a quadrilateral prism comprising metal corrugated sheets. A typical dimension for a structured packing section is 72″×12″×8″, weighing 30-40 pounds. This packing must be replaced when internal modifications or repairs to the tower are required, or when a new design of the structured packing and structured packing sections is developed. The old packing is removed by hand and discarded. 
     Distribution trays supporting the structured packing are located in the interior of the tower. The structured packing sections are typically stacked on top of each other until they nearly reach the next highest distribution tray in the tower. The manway to access the interior of the tower is located just below each distribution tray, and worker access to the lower distribution tray is achieved by climbing through the manway and down a portable flexible rope. 
     In the prior art, new structured packing was lowered through a manway with a rope down to a supporting distribution tray inside the tower. This method had two main disadvantages. 
     First, the process was slow. A packing replacement operation may involve over 12,000 sections of structured packing. The time required to rig each section, lower it down, and untie it from the rope was costly, both in labor cost as well as lost production time for the tower. Due to the high number of sections being singularly installed, a reduction of even one minute per section in the time required to lower it into position would have great cost savings. In the case of a 12,000 section turnaround job, a one minute per section saving would translate to reducing the time that the tower was out of operation by over eight days. It is common for such towers to produce over $1,000,000 worth of product per day. Thus, the cost savings of the current invention, which is estimated to save between 1-3 minutes per section, are significant. 
     Second, the process of lowering each structured packing section often damaged the packing, which is typically constructed of thin corrugated metal sheets. This resulted in reduced process efficiency due to the damaged structured packing. 
     It would therefore be a new and useful improvement of the prior art for a method to afford quick and efficient loading and arrangement of structured packing sections into processing towers without damaging the structured packing. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, the objectives of this invention are to provide, inter alia, a new and improved method of loading structured packing into a process tower that: 
     is time efficient; 
     does not damage the structured packing; 
     can be built to accommodate standard sized structured packing; 
     is lightweight and easily set up within the process tower; 
     is relatively inexpensive; and 
     is easily modifiable to accommodate different heights and levels of packing. 
     These objectives are addressed by the structure and use of the inventive removable slide loading system. The structured packing is slid down to a receiving area, and then stacked on a distribution tray to form a packing bed. As the packing bed gets higher from the stacking of the structured packing sections, the slide is shortened and the bottom stage is raised. 
     Other objects of the invention will become apparent from time to time throughout the specification hereinafter disclosed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts a typical process tower in cut-away view. 
     FIG. 2 depicts a typical section of structured packing material. 
     FIG. 3 depicts the preferred embodiment of the inventive slide. 
     FIG. 4 depicts a cross-sectional view of the bottom stage across line A—A seen in FIG.  3 . 
     FIG. 5 depicts a slide slope section. 
     FIG. 6 depicts a preferred supporting section bracket. 
     FIG. 7 depicts the hinge connection of the top loading receiver. 
     FIG. 8 depicts placement of the top loading receiver in a manway opening. 
     FIG. 9 depicts a cross section of the top loading receiver in a manway opening across line B—B seen in FIG.  8 . 
     FIG. 10 depicts the inventive loading system in position for use in a process tower. 
     FIG. 11 depicts the inventive loading system positioned away from an entry manway to afford worker egress from the process tower. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is described and depicted as loading system  10 . 
     A typical process tower  50  is depicted in FIG.  1 . Process tower  50  may be over  150 ′ high, have a radius between  25 ′ and  30 ′, and typically has multiple packing beds  60  each supported by a separate distribution tray  55 . Where process tower  50  is a vacuum tower, liquid is sprinkled downward from the top interior of process tower  50 , while lighter vapors are pulled upward from the bottom interior of process tower  50 . Packing beds  60  provide increased surface areas for the heavier liquid and lighter vapors to adhere and interact. 
     A typical structure of structured packing section  65  is depicted in FIG.  2 . Packing beds  60  comprising structured packing sections  65  are formed by stacking structured packing sections  65 . Packing beds  60  typically reach from their supporting distribution tray  55  to within a foot below the next highest distribution tray  55 . 
     Packing beds  60  are replaced when an improved design of the distribution system or structured packing sections  65  is developed. The old packing is typically discarded by manually unloading it through a manway  25 , and manually loaded into a material basket attached to a crane for lowering to the ground. Since the old packing is often discarded, it usually does not matter if the old packing is damaged when removed. 
     Loading system  10 , comprising bottom stage  40 , slide slope  30  and top loading receiver  20 , is depicted in FIG.  3 . 
     Bottom stage  40  is located in receiving area  45 . Receiving area  45  is initially located directly on distribution tray  55 , as shown in FIG.  1 . As structured packing sections  65  are unloaded and stacked on distribution tray  55 , receiving area  45  moves upward as bottom stage  40  is repositioned on top of the stacked structured packing sections  65 . Bottom stage  40  comprises at least one bottom staging section  41 . In the preferred embodiment, bottom staging section  41  is constructed of  20  gauge sheet metal. Bottom stage  40  is supported by a plurality of support legs  47 , which rest either directly on distribution tray  55 , or on a load distributing surface (such as a sheet of plywood, not shown) that is laid on top of the stacked structured packing sections  65  as described above. As seen in the cross sectional view of FIG. 4, bottom staging section  41  is attached, preferably with easily engaged attachment mechanism such as carriage bolts with wing nuts, between support legs  47 . If there are more than one bottom staging section  41 , they are connected end-to-end to each other with similar attachment mechanisms, depicted in FIG. 4 as bottom staging section connectors  48 . 
     In the preferred embodiment, radius section  35  provides a transition curve between bottom stage  40  and slide slope  30 . In the preferred embodiment, radius section  35  and slide slope  30  are constructed of  20  gauge sheet metal, and have a coefficient of friction small enough to allow structured packing sections  65  to slide all the way down to bottom stage  40  at all levels of receiving area  45  described below, while having a coefficient of friction high enough such that structured packing sections  65  are not damaged by excessive velocity when reaching bottom stage  40 . For the same reason, radius section  35  has a radius of curvature appropriate for the size of structured packing sections  65  after they slide down slide slope  30  and before reaching bottom stage  40 . 
     Slide slope  30  is constructed of at least one slide slope section  31 , depicted in FIG.  5 . If there are more than one slide slope sections  31 , they are connected end-to-end with slide slope section connectors  29 , which, like bottom staging section connectors  48 , are preferably easily engaged with the bare hand or with common hand tools. Slide slope section connectors  29  traverse through slide slope section connection holes  34 , which are aligned as the ends of slide slope sections  31  overlap to form a double layer for said connection, and secure section brackets  36 , shown in FIG. 6, for additional support. In the preferred embodiment, section brackets  36  are similarly used for additional support in all end-to-end connections, including those found in bottom stage  40  and radius section  35 . These connections create a strong and rigid slide slope  30  from slide slope sections  31 . As noted above, slide slope sections  31  are preferably constructed of 20-gauge sheet metal with appropriate coefficients of friction between their surface and structured packing sections  65 . 
     Slide slope  30  connects to top loading receiver  20 . In the preferred embodiment shown in FIG. 7, this connection is accomplished through the use of top loading receiver hinge  21 . Top loading receiver hinge  21  is preferably a locking piano hinge, such that it allows top loading receiver  20  to swing downwards as seen in FIG. 10 to attach to manway  25 , while restricting upward travel of top loading receiver  20  beyond the slide slope axis  33  of slide slope  30 , as shown in FIG.  11 . The primary restriction of upward travel of top loading receiver  20  beyond slide slope axis  33  of slide slope  30  is from the shape and orientation top loading receiver  20 , which mates against the interior bottom surface uppermost slide slope section  31 , as depicted in FIG.  11 . 
     Top loading receiver  20  traverses through manway opening  24  when loading system  10  is in use. As shown in the preferred embodiment depicted in FIG.  8  and FIG. 9, top loading receiver  20  is secured to manway flange  26  with mounting bracket  27 , which is part of top loading receiver  20 . Top loading receiver  20 , as well as slide slope sections  31  and bottom staging sections  41 , preferably have stiffening lips  28 , to provide a rigid support structure to prevent buckling and rotational twisting of loading system  10 . 
     OPERATION 
     After old packing material is removed from a packing bed volume of process tower  50 , loading system  10  is erected inside process tower  50 . Access to the interior of process tower  50  is afforded through manways  25 . Proximate to manways  25  at elevations are grating landings  23 , on which workers can walk and material can be staged. 
     In a typical embodiment, support legs  47  and bottom staging sections  41  are first lowered down through manway opening  24  to receiving area  45 , using ropes or an equivalent hoisting device. Support legs  47  are placed vertically on distribution tray  55 , and fastened to at least one bottom staging section  41  to form bottom stage  40 . Slide slope  30  is constructed outside of process tower  50  by fastening together slide slope sections  31  end-to-end as described above. Radius section  35  is fastened to slide slope  30  as described above, slide slope  30  is hinged to top loading receiver  20  using top loading receiver hinge  21 , and the combined radius/slope/top assembly  32  is inserted through manway opening  24 . Radius section  35  is attached to bottom stage  40 , and mounting bracket  27  is attached to manway flange  26 , thus forming a stable and rigid loading system  10 . 
     Structured packing sections  65  are staged outside manway  25 , typically on grating landings  23  at elevations, and each structured packing section  65  is then placed on top loading receiver  20 . Structured packing sections  65  are pushed into process tower  50 , where they slide down slide slope  30  and down to bottom stage  40  in receiving area  45 . Structured packing sections  65  are offloaded and stacked on distribution tray  55 . As more structured packing sections  65  are offloaded and stacked, they surround bottom stage  40 . When the stacked structured packing sections  65  reach a pre-selected level, bottom stage  40  is detached from radius/slope/top assembly  32 . A load distributing device, such as a piece of plywood, is placed on top of the stacked structured packing sections  65 , and bottom stage  40  is placed on top of the plywood. Other structured packing sections  65  are positioned and stacked in the area where bottom stage  40  originally stood, thus forming a now continuous higher level of flooring made of structured packing sections  65 . Bottom stage  40  is repositioned on a second load distributing structure (such as a sheet of plywood) that is on top of the stacked structured packing sections  65 . At this higher level of flooring, a slide slope section  31  is removed from radius/slope/top assembly  32 , and bottom stage  40  is moved laterally closer to manway  25 . When bottom stage  40  is then reattached to the shortened radius/slope/top assembly  32 , the slope angle of slide slope  30  remains essentially the same, and the speed at which structured packing sections  65  slide down slide slope  30  remains essentially the same as before. This process is repeated until the stacked structured packing sections  65  reach a pre-determined height, that being where additional structured packing sections  65  can be handed directly to a worker inside process tower  50  through manway opening  24 . At that point, mounting bracket  27  is disconnected from manway flange  26 , radius slope/top assembly  32  is extracted our through manway opening  24 , bottom stage  40  is disassembled and its components extracted through manway opening  24 . The remaining required structured packing sections  65  are handed to the worker inside process tower  50  to finish out the required height of packing bed  60 . 
     In the alternative, radius section  35  and slide slope sections  31  can be assembled inside process tower  50  and then attached to bottom stage  40 , using the same method described above. 
     The foregoing description of loading structured packing sections  65  is accomplished when loading system  10  is positioned as shown in FIG. 10, with top loading receiver  20  attached to manway  25  by securing mounting bracket  27  to manway flange  26 . If an employee needs to exit process tower  50  in the middle of a loading job, loading system  10  occludes too much of manway opening  24  to allow egress. To afford such egression, mounting bracket  27  is disconnected from manway flange  26 , and top loading receiver  20  is rotated upward. When mounting bracket  27  clears above manway flange  26 , top loading receiver  20  is moved through manway opening  24 . This movement can be through movement of all of loading system  10 , or by first disconnecting any desired part of loading system  10  and moving only top loading receiver  20  and its attached components of loading system  10 . Typically, at least radius/slope/top assembly  32  remain assembled during this step. Top loading receiver  20  is pulled inside process tower  50 , and the fully rotated upward until top loading receiver  20  is aligned along slide slope axis  33 . Because top loading receiver hinge  21  is a single direction hinge attached to the shape and orientation of top loading receiver  20  described above, top loading receiver  20  is locked against firther upward movement when aligned along slide slope axis  33 . Top loading receiver  20  can then be rested against the interior of process tower  50  away from manway opening  24 , and the worker can egress, often with the aid of a rope ladder hanging from manway  25 . After the worker re-enters process tower  50 , these steps are reversed and loading system  10  is again ready for use. 
     The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.