Abstract:
A liquor gun holder for a recovery furnace includes a rail assembly, a carriage assembly moveably mounted onto the rail assembly such that the carriage assembly is moveable longitudinally along the rail assembly, a pivot pin supported by a bearing and extending laterally from the carriage assembly, and a cleaning assembly pivotally mounted onto the pivot pin such that the cleaning assembly is rotatable about a horizontal axis extending longitudinally through the pivot pin and is positioned laterally from the carriage assembly and the rail assembly, the cleaning assembly including a clamp adapted to secure a liquor gun thereon such that the liquor gun is rotatable with the cleaning assembly and is positioned laterally from the carriage assembly.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
   This patent application claims the benefit of U.S. provisional patent application 60/575,669, filed May 28, 2004. 

   FIELD OF THE INVENTION 
   The present invention relates generally to recovery boilers and furnaces which are used to process waste liquor, and more particularly relates to the liquor gun used to spray the waste liquor into the recovery furnace. 
   BACKGROUND OF THE INVENTION 
   Paper pulp is manufactured by treating wood in a boiling liquid at high temperatures and pressures. After the boiling process, the remaining liquid contains a number of chemicals and retains some of the wood substance, forming a “weak liquor”. In a typical mill, the water is removed from the weak liquor and a “black liquor” is obtained, and is then supplied as fuel to the recovery boiler. The recovery boiler provides a reduced atmosphere at 1000° C. to burn the remaining wood substance and release energy that is conveyed away in the form of high-pressure steam. A regeneration of the chemicals contained in the black liquor is also performed in the recovery boiler. 
   The black liquor is normally supplied to the recovery furnace through burners commonly referred to as liquor guns. These liquor guns often include simple nozzles provided with some form of splash or deflection plate that is mounted on the nozzle. Typically, the liquor guns are mounted for rotation about a horizontal axis, whereby the vertical position of the nozzle and deflector plate may be adjusted in order to direct the spray of the black liquor. Due to the harsh environment of the mill and recovery furnace, the entire spray gun assembly, including the tilting mechanism, must be very sturdily constructed. At the same time, the harsh environment requires that the liquor guns be serviced relatively frequently. For example, the nozzle portion of the gun projects inside the recovery furnace and is constantly exposed to high temperatures and the black liquor. Thus, the nozzles need cleaning, repair or replacement. 
   Accordingly, there exists a need to provide a liquor gun assembly that is not only well adapted for the harsh environment of a recovery furnace, but which also facilitates access and service of the liquor gun. 
   BRIEF SUMMARY OF THE INVENTION 
   A liquor gun holder in accordance with this invention generally comprises a spray rod (splash plate cleaning device), a carriage assembly and a rail assembly. The spray rod and gun holder is rotatably connected to the carriage assembly. The carriage assembly is mounted to the rail assembly for linear translation relative to a wall of the recovery furnace. The liquor gun thus includes a retractable spray rod which may be translated from an active position where its nozzle is positioned within the interior chamber of the furnace, to a service position where the spray rod is retracted and the nozzle is outside the chamber. The retractable spray rod permits service on liquor gun, including the nozzle of the spray rod. 
   According to more detailed aspects, the carriage assembly includes a tilting mechanism which allows the spray rod and gun holder to be tilted relative to a horizontal axis. Preferably, the tilting mechanism and the carriage assembly are positioned laterally (i.e. to the side) of the spray rod. When a cleaning assembly is provided to remove accumulated black liquor from the deflector plate, the cleaning assembly is preferably vertically aligned with the spray rod, and thus also positioned laterally from the carriage assembly. In this manner, the spray rod and cleaning assembly may be tilted, while at the same time permitting axial translation of the spray rod and scraper assembly via the carriage and rail assemblies which are positioned to prevent interference with the spray rod. 
   According to even further aspects of the invention, the rail assembly is preferably positioned vertically below the carriage assembly, and importantly is also positioned laterally from the spray rod. The rail assembly typically includes a connection plate and tab which correspond with vertically extending mounting plates attached to a wall plate of the recovery furnace wall. The wall plate generally includes an elongated slot or aperture for providing access to the interior chamber of the recovery furnace. While the nozzle of the spray rod must be aligned with this opening for spraying black liquor into the furnace, the carriage assembly and rail assembly are preferably laterally positioned from the spray rod so that these mechanisms are not aligned with the opening, and thereby partially sheltered from that environment. At the same time, the retraction of the spray rod and its nozzle does not cause any black liquor to leak or seep onto the carriage assembly or rail assembly, as they are laterally positioned therefrom. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view, partially in cross-section and partially in hidden, of a liquor gun constructed in accordance with the teachings of the present invention; 
       FIG. 2  is an end view of the liquor gun depicted in  FIG. 1 ; and 
       FIG. 3  is a side view partially in cross-section and partially in hidden, showing the liquor gun of  FIG. 1  in a retracted service position. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Turning now to the figures,  FIGS. 1 and 2  depict side and end views of a liquor gun holder  20  designed to support a liquor gun  22  to provide black liquor to the internal chamber  10  defined by the exterior wall  12  of a recovery furnace. The liquor gun holder  20  generally comprises a cleaning assembly  16  connected to a carriage assembly  40 , which in turn is connected to a rail assembly  60  for linear translation of the cleaning assembly  16  relative to the chamber  10  of the furnace.  FIG. 1  depicts the cleaning assembly  16  and carriage assembly  40  in an extended active position. 
   The liquor gun  22  generally comprises an inlet tube  24  fluidically connected to a spray tube  26 , which in turn is fluidically connected to a nozzle  28 . The inlet tube  24  is connected to the spray tube  26  by way of a hinge coupling  30  which allows the inlet tube  24  and spray tube  26  to rotate relative to one another. The nozzle  28  is coupled to the spray tube  26  by way of a coupling  32 , thereby allowing the nozzle  28  to be individually replaced or repaired. The nozzle  28  projects through a port  14  formed in the exterior wall  12  of the recovery furnace. The distal end of the nozzle  28  includes a deflector plate  34  as is known in the art for forming a spray pattern with the black liquor to promote vaporization and recovery in the recovery furnace. 
   The liquor gun  22  is connected to the carriage assembly  40  by way of a clamp  35 . The clamp  35  is secured to the horizontal arm of an L-shaped bracket  36 . The downwardly depending arm of the L-shaped bracket  36  is mechanically connected to the cleaning assembly  16  which includes a cylinder  17  operatively connected to a scraper or cutting head  18 . As is known in the art, the cleaning assembly  16  translates the cutting head  18  into engagement with the deflector plate  29  to scrape the deflector plate  34  and free any black liquor or other debris that has collected thereon. In sum, the liquor gun  22  and cleaning assembly  16  are rigidly connected by way of the L-shaped bracket  36 . 
   The L-shaped bracket  36  is attached to a pivot pin  38  which extends laterally from the cleaning assembly  16 , as best seen in  FIG. 2 . The carriage assembly  40  includes opposing first and second plates  42 ,  44  which have a bearing  46  extending therebetween for receiving the pivot pin  38 . Accordingly, it will be seen that the cleaning assembly  16  and the liquor gun  22  are thus pivotally connected to the carriage assembly  40  by way of the pivot pin  38  and the bearing  46 . As is known in the art, the cleaning assembly  16  and the liquor gun  22  are rotatable about a horizontal axis defined by the pivot pin  38  to change the position of the nozzle  28 . The carriage assembly  40  includes a mechanism to rotate the cleaning assembly  16  and the liquor gun  22  and to secure the cleaning assembly  16  and the liquor gun  22  in a particular pivoted position. As shown, a crank  39  is rotated to drive a toothed shaft (not shown), which in turn drives a gear mechanism (not shown) housed in the carriage assembly  40  between the opposing plates  42 ,  44 . 
   The first plate  42  extends downwardly from the pivot pin  38  and the bearing  46  for connection to the rail assembly  60 , as will be described below. As best seen in  FIG. 1 , the rail assembly  60  generally includes a bracket  62  attached to a connection plate  64 . The connection plate  64  includes a pair of distally projecting tabs  66  for attaching the rail assembly  60  to a wall plate  72  forming a portion of the furnace wall  12 . The wall plate  72  defines an elongated slot or aperture  74  ( FIG. 2 ) providing access to the internal chamber  10  of the recovery furnace. The wall plate  72  includes a pair of opposing mounting plates  68  having a plurality of apertures  70  which are vertically spaced. The mounting plates  68  receive the tabs  66 , and the plurality of apertures  70  allow the rail assembly  60  to be vertically positioned relative to the furnace and internal chamber  10 . This in turn allows the liquor gun holder  20  to be vertically positioned on the furnace. 
   Referring now to  FIG. 2 , an end view of the rail assembly  60  can be seen. The bracket  62  includes a rail  76  projecting laterally therefrom, the rail including a pair of opposing guides  78 . The guides  78  each preferably comprise a cylindrically shaped metal rod which provides stable translation of the carriage assembly  40  relative to the rail assembly  60 . It can also be seen in  FIG. 2  that the first plate  42  of the carriage  40  includes an axle plate  48  which supports a pair of opposing rollers  50  shaped to correspond with the guides  78 . The rollers  50  translate over with the guides  78  formed in the rail  76 . A stop  82  is positioned at a proximal end of the rail  76  to prevent inadvertent removal of the carriage assembly  40 , cleaning assembly  16 , and liquor gun  22  therefrom. The liquor gun holder  20  is structured for manual translation of the liquor gun  22  and carriage assembly  40 , although a motor or other mover can be employed to facilitate the withdrawal of the liquor gun  22  from the recovery furnace. 
   A block  52  is connected to a lower end of the first plate  42 , and includes a plurality of apertures  74  as seen in  FIG. 1 . In this way, a pin  80  may be fitted through the bracket  62  of the rail and positioned within one of the apertures  74  of the block  52 . Thus, the pin  80  and block  52  form a lock which fixes the position of the carriage assembly  40 , cleaning assembly  16 , and liquor gun  22  relative to the rail assembly  60 . Other locking mechanisms will be readily envisioned by those of ordinary skill in the art. 
   In operation, the liquor gun holder  20  permits axial, preferably horizontal, translation of the cleaning assembly  16  and the liquor gun  22  via the carriage assembly  40 , to selectively position the liquor gun  22  relative to the internal chamber  10  of the recovery furnace. A retracted service position of the liquor gun  22  and carriage assembly  40  has been depicted in  FIG. 3 . As shown, both the liquor gun  22  as well as the cleaning assembly  16  may be horizontally adjusted relative to the internal chamber  10 , and to move the nozzle  28  into or out of the internal chamber  10  of the recovery furnace. In, the service position, the ports into the furnace may be closed off, and the liquor gun  22  allowed to cool prior to servicing. Furthermore, the cleaning assembly  16  may be activated while the liquor gun  22  is in either the active or service positions. As is known, the liquor gun  22  is periodically purged with steam to clean the interior passageway of the liquor gun  22 . 
   In addition to the axial translation of the liquor gun  22  described above, the carriage assembly  40  and its tilt mechanism (not shown) permit the liquor gun  22 , and the cleaning assembly  16 , to be rotated about a horizontal axis defined by the pivot pin  38 . The opening  71  formed in the wall plate  72 , as well as the port  14  defined in the furnace wall  12 , are sized to permit the axial translation of the liquor gun  22  and carriage assembly  40  relative to the rail assembly  60  regardless of whether the liquor gun  22  is in a horizontal or tilted position. Likewise, the ability to tilt as well as axially translate the liquor gun  22 , either sequentially or simultaneously, is permitted by virtue of placing the carriage assembly  40  and corresponding rail assembly  60  laterally from the cleaning assembly  16  and the liquor gun  22 , as best seen in the end view of  FIG. 2 . 
   It will also be seen that the opposing plates  42 ,  44  of the carriage assembly  40 , which house the bearing  46  and gearing assembly for tilting the cleaning assembly  16  and the liquor gun  22 , are vertically positioned above the rail assembly  60 , and in particular the rail  76  and guides  78 . Accordingly, the liquor gun  22  may be translated horizontally and away from the internal chamber  10  of the recovery furnace, to thereby allow service or replacement of the liquor gun  22  as well as cleaning or other maintenance. At the same time, the liquor gun  22  may be tilted and the carriage assembly  40 , including the tilting mechanism, and rail assembly  60  are protected from the harsh environment of the recovery furnace.