Rotary kiln heat exchanger and method of assembling same

Abstract

Rotary kiln heal exchangers having precast hub and leg assemblies are disclosed. The hub and leg assemblies include interlocking features which secure the heat exchanger components together. A method of installing such heat exchangers in rotary kilns is also disclosed. Installation is relatively fast and simple, and the heat exchangers are capable of withstanding the harsh operating conditions of rotary kilns for extended periods of time.

What is claimed is: 
     
       1. A rotary kiln comprising:
 a refractory lining in the kiln; and   a heat exchanger assembly in the kiln including a heat exchanger hub comprising recesses, and heat exchanges legs received in the heat exchanger hub recesses wherein the legs are installed adjacent to the refractory lining with at least one course of raised bricks.   
     
     
       2. A rotary kiln comprising:
 a refractory lining in the kiln; and   a heat exchanger assembly in the kiln including a heat exchanger hub comprising recesses, and heat exchanger legs received in the heat exchanger hub recesses, wherein the legs are installed adjacent to the refractory lining with at least two courses of raised bricks, and the courses of raised bricks have different heights.   
     
     
       3. A method of installing a heat exchanger in a rotary kiln comprising:
 positioning first and second heat exchanger legs in the kiln at initial positions;   installing a hub between the first and second legs by moving the first and second legs from their initial positions to installed positions in which the first and second legs are engaged with the hub; and   installing a third heat exchanger leg by engaging the third heat exchanger leg with the hub.   
     
     
       4. The method of  claim 3 , wherein the first and second heat exchanger legs are positioned at four o'clock and eight o'clock positions, respectively. 
     
     
       5. The method of  claim 3 , wherein the third heat exchanger leg is installed at a twelve o'clock position. 
     
     
       6. The method of  claim 3 , wherein at least one of said first and second heat exchanger legs includes recesses and projections dimensioned to engage and interlock with projections and recesses an said hub. 
     
     
       7. The method of  claim 6 , wherein a third heat exchanger leg slides into position relative to said hub. 
     
     
       8. The method of  claim 6  further comprising the step of inserting shims between said kiln and the outer end of at least one of said heat exchanger legs. 
     
     
       9. The method of  claim 3 , wherein at least one of said heat exchanger legs includes recesses and projections dimensioned to engage and interlock with projections and recesses on said hub, and at least one of said heat exchanger legs is pinned to said hub. 
     
     
       10. A trefoil structure for a rotary kiln, said kiln having a cylindrical body having a metal shell and a refractory brick lining therewithin, said trefoil structure, comprising:
 a central hub comprised of a plurality of side-by-side, pre-formed refractory hub sections, said hub sections aligned along a central axis that extends through said cylindrical body; and   a plurality of legs extending radially outward from said hub to said metal shell, each of said legs comprised of side-by-side pre-formed leg sections, each of said leg sections being a unitary cast refractory shape that extends between said central hub and supports on said metal shell.   
     
     
       11. A trefoil structure of  claim 10 , wherein said hub sections are axially thicker than said leg sections, wherein each hub section engages at least two side-by-side leg sections. 
     
     
       12. A trefoil structure of  claim 11 , wherein shims are disposed between said metal shell and at least one of said legs. 
     
     
       13. A trefoil structure of  claim 10 , wherein the leg sections that form at least one of said legs are axially slidable into engagement with said hub sections forming said hub. 
     
     
       14. A trefoil structure of  claim 13 , wherein said leg sections are pinned to said hub sections. 
     
     
       15. A trefoil structure of  claim 10 , wherein at least one of said legs is comprised of leg sections that have innermost ends that interlockingly engage with said hub sections, and at least one of said legs is comprised of leg sections that have innermost ends that slide axially along the central axis of said cylindrical body into engagement with said hub sections. 
     
     
       16. A trefoil structure of  claim 15 , wherein said leg sections that slide into engagement with said hub sections are locked in position by pins extending into aligned slots in said slidably-aligned leg sections and said hub sections. 
     
     
       17. A trefoil structure of  claim 15 , wherein said leg sections that interlock with said hub sections have a plurality of recesses and protrusions formed along said innermost end of said leg sections that mate with opposing protrusions and recesses on said hub sections. 
     
     
       18. A trefoil structure for a rotary kiln, said kiln having a cylindrical body having a metal shell and a refractory brick lining therewithin, said trefoil structure, comprising:
 a refractory hub oriented along an axis that extends axially through said cylindrical body; and   a plurality of elongated leg sections that extend radially from said hub to said metal shell, each of said leg sections being an elongated cast refractory shape dimensioned to have an innermost end that engages and interlocks with said hub and an outermost end supported by said metal shell of said cylindrical body.   
     
     
       19. A trefoil structure of  claim 18 , wherein groups of said leg sections are arranged side-by-side to form a plurality of equally spaced trefoil legs that extend from said hub to said metal shell. 
     
     
       20. A trefoil structure of  claim 19 , wherein each of said leg sections includes a protrusion on one lateral side and a recess on another lateral side, said protrusion and said recess being dimensioned, wherein a protrusion on one leg section is matingly received in a recess in another leg section when multiple leg sections are arranged side-by-side to form a trefoil leg. 
     
     
       21. A trefoil structure of  claim 20 , wherein said hub is comprised of a plurality of side-by-side pre-formed refractory hub sections. 
     
     
       22. A trefoil structure of  claim 21 , wherein a hub section is thicker than a leg section, wherein each hub section engages at least two side-by-side leg sections. 
     
     
       23. A trefoil structure of  claim 18 , wherein said leg sections are supported by said metal shell by elongated bars attached to said metal shell, said bars being received in channels formed in the outermost ends of said leg sections. 
     
     
       24. A trefoil structure of  claim 23 , wherein said channels are formed in the edge of said leg sections. 
     
     
       25. A trefoil structure of  claim 18 , wherein shims are disposed between said metal shell and the outermost end of at least one of said leg sections. 
     
     
       26. In a rotary kiln having a refractory lining in the kiln, a heat exchanger assembly, comprised of:
 a heat exchanger hub comprising recesses;   multiple heat exchanger legs, each heat exchanger leg having an inner end received in the recesses of said heat exchanger hub and an outer end installed adjacent said refractory lining, each heat exchanger leg comprised of side-by-side preformed leg sections, each of said leg sections being a unitary cast refractory shape that extends between said heat exchanger hub and said refractory lining, said leg sections being stacked together along the axial length of the kiln, each of said heat exchanger leg sections having an elongated protrusion on one side of the leg section and an elongated recess on an opposite side of the leg section, said protrusion on a heat exchanger leg section dimensioned to fit in mating fashion within a recess on an adjacent heat exchanger leg section to interlock adjacent heat exchanger leg sections and to prevent lateral movement of the adjacent leg sections relative to one another, said protrusion and recess extending along a major portion of the length of said elongated leg section in a direction between said inner end and said outer end of said leg section.    
     
     
       27. A rotary kiln as defined in claim 26, wherein each heat exchanger leg section includes a flared, outer end dimensioned to be positioned along the inner surface of said kiln.  
     
     
       28. A rotary kiln as defined in claim 26, wherein each said heat exchanger leg section has an overall length L greater than about three (3) feet.  
     
     
       29. A rotary kiln as defined in claim 26, wherein each said heat exchanger leg section has a flared, inner end.  
     
     
       30. A rotary kiln as defined in claim 28, wherein said heat exchanger assembly includes a plurality of hub sections, said inner end of said legs interlocking with said hub sections.  
     
     
       31. An elongated, pre-cast leg section for use in forming a leg in a heat exchanger in a rotary kiln by stacking a plurality of said leg sections together along the axial length of said kiln, said leg section having an inner end and an outer end and an elongated protrusion on one side thereof and an elongated recess on an opposite side thereof, said protrusion and said recess being dimensioned such that a protrusion on one leg section fits in mating fashion within a recess on an adjacent leg section to interlock said one leg section to said adjacent leg section and to prevent lateral movement of the adjacent leg sections relative to one another when said legs are stacked together along the axis of said kiln, said protrusion and recess extending along a major portion of the length of said elongated leg section in a direction between said inner end and said outer end of said leg section.