Patent Publication Number: US-3874442-A

Title: Pack of heat absorbing material and a support member therefor

Description:
United States Patent Johnsson [451 Apr. 1, 1975 2,549,583 4/1951 Eckersley................................165/5 Bo Johnsson, Kungsbacka, Sweden Primary ExaminerAlbert W. Davis, Jr. Attorney, Agent, or Firm-Flynn &amp; Frishauf [73] Assignee: Svenska Rotor Maskiner Aktiebolag,  
 Nacka, Sweden ABSTRACT [22] Filed: Feb. 9, 1973 [57] A pack of heatabsorbing material for a rotary regen- 21 Appl. No.: 331,245  
  erative heat exchanger composed of a stack of plate [30] Forelgn Apphc auon Pl-l0my Data elements and a support member therefor. The support 1972 member comprises a frame structure contacting one end of the stack and a lift element extending through the stack and projecting from the opposite end [51] Int. F28d 19/00 thereof The Stack is further provided with two rods [58] Field of 165/5, 10  
 passing through&#39;the plates and each having a head projecting outside the plates at opposite fronts of the stack.  
 References Cited UNITED STATES PATENTS 2,432,198 Karlsson et al. 165/10 19 Claims, 3 Drawing Figures FATENTED APR l [975 SHEET 1 BF 2 PTENTEU APR 1 75 SHEET 2 [IF 2 PACK OF HEAT ABSORBING MATERIAL AND A SUPPORT MEMBER THEREFOR This invention relates to rotary regenerative heat exchangers such as air preheaters and more particularly to means for facilitating the filling of the substantially cylindrical regenerator body with profiled element plates forming the regenerative mass of the heat exchanger.  
  The number of plates contained in a regenerator body of an air preheater may amount to 100 000 or more. It is evident that the filling of such a regenerator body manually with separate plates would involve a very time-consuming work. It has therefore become common practice to put plates together to form stacks of suitable size and form already in connection with the cutting of the plates at the workshop and these stacks are placed in basket-like structures or the plates in the stack are kept together by other means to form units which may be easily transported to the place where the boiler plant is erected. The units are then placed in the regenerator body according to a predetermined plan.  
  Different embodiments of such units are shown for instance in British Patent specifications Nos. 1,061,454, 1,103,207 and 1,174,513.  
  Hitherto used packs or units are rather expensive. Further, the several designs of the units are all such that there must necessarily remain gaps or voids between adjacent units and between the units and the walls of the sectorial compartments of the regenerator body.-  
 These empty spaces form leakage paths for the fluids in which the heat exchange is very poor. In addition, the known units are often difficult to handle.  
  The invention has for its main object to provide a pack of rectangular element plates for rotary regenerative heat exchangers which eliminates or reduces the drawbacks mentioned above. The pack is of the type which includes a stack of plates which are profiled such as to form open-ended passages for the heat exchanging fluids extending between two parallel surfaces of the stack.  
  One feature of the invention is a support member comprising a frame structure engaging one of said parallel end surfaces and strapped to the stack during transport. The frame structure is provided with at least one elongated lift element secured to said frame structure and projecting perpendicularly therefrom through the stack, the free end of said lift element being accessible at the other of said parallel end surfaces and shaped to be engaged by a hoisting device. The lift element is further located such as to pass substantially through the centre of gravity of the pack.  
 Another feature of the invention is a number of rods passing through the stack of plates generally in parallel with the carrying frame structure. Those rods prevent relative motion of the plates in directions transverse to the direction-of the rods during transport of the pack before the insertion thereof into the regenerator body. A further aim of those rods is to prevent the outer plates of the pack to slip beyond the carrying frame structure, when the pack is inserted in the regenerator body and unstrapped.  
  The invention also includes a support member for a stack of rectangular element plates for a rotary regenerative heat exchanger. The support member comprises a frame structure on which, in use, the element plates are supported and at least one elongated lift element secured to the frame structure, the lift element having a length so as to project beyond the plates when supported on the frame structure.  
  This and other objects of the invention will be apparent from the following description of an embodiment of the invention illustrated in the accompanying drawing, in which FIG. 1 shows a perspective view of a rotary regenerative air preheater provided with plate packs according to the invention,  
  FIG. 2 shows a perspective view of such a pack before insertion in the preheater, and  
  FIG. 3 shows diagrammatically two superimposed packs, the packs being shown separated from each other in order to simplify the explanation of their cooperation.  
  In the figures numeral 10 generally indicates a plate pack including a plate stack 12 and a support member 14. The stack is joined to the support member by means of straps 16.  
  The plates are of rectangular shape and provided with spacing means such as notches (not shown) in the plates so that they define open-ended passages for the heat exchanging fluids. All the plates are of the same height but of successively changing width resulting in a substantially trapezoidal stack form. The upper and lower end surfaces of the stack are parallel, whereas the two side surfaces of the stack converge from the right front plate 15 towards the left front plate 17 of the stack as viewed in FIG. 2.  
  The design of the support member 14 is shown in detail in FIG. 3 which illustrates two packs 10A and 10B of two superimposed pack layers, the plate stacks 12 being indicated by chain-dotted lines.  
  According to FIG. 3 each support member 14 comprises a frame structure including two longitudinal girders 20 interconnected by three cross-pieces 22, and a lift element 24 in the form of a flat rod secured to the intermediate cross-pieces 22 and projecting perpendicularly from the frame structure while extending through stack 12 between two plates thereof. At its free end protruding through the upper end surface of the stack the lift element 24 is provided with an opening 26 for a hook or the like of a hoisting device.  
  The intermediate cross-piece 22 is located such that the lift element 24 passes at least near the centre of gravity of the pack 10. Thus, when the pack is lifted by means of a hoisting device it will occupy a substantially horizontal position.  
  Before the stack 12 is joined to the support member 14 by means of the straps 16 it is elastically compressed.  
  The contour of the frame structure is substantially similar to that of the contacting lower surface of the plate stack but of smaller width. Thus, the plates extends a small distance beyond the girders 20. In its compressed state the stack 12 has substantially the same length as the frame structure whereas in expanded state of the stack 12 the front plates 15, 17 project outside the ends of the girders 20. In order that the straps 16 shall be able to effectively maintain the stack in its compressed condition the cross-pieces 22 at the ends of the frame structure are located at a suitable distance from the ends of the girders 20.  
  Often the regenerative mass is subdivided into two or more layers. In such a case the packs of the lowermost pack layer may rest on brackets secured to the radial partitions and cooperating with the girders of the packs while the packs of the next layer may with their girders rest on the packs located below. It is evident that if the packs of the two layers were identically alike the lift element 24 of a lower pack 10A would interfere with that of an upper pack 10B. In order to obviate such interference the lift element of one of the packs is secured to one side of the intermediate cross-piece 22 while the lift element of the other pack is secured to the other side thereof as illustrated in FIG. 3.  
  In most heat exchangers the sectorial compartments of the regenerator body are subdivided into two or more chambers by tangential walls. Usually the packs are dimensioned and shaped such that one single pack substantially entirely fills the cross-section of the specific chamber for which it is intended. After the pack has been sunk down into the chamber by means of a hoisting device the straps 16 are cut off and removed thereby permitting the plate stack to expand in radial direction into elastic contact with the tangential walls of the chamber. Each plate of the stack 12 is provided with two holes located adjacent to one side edge of the plate and preferably punched simultaneously with the cutting of the edge. The holes of adjacent plates register with each other to form two straight channels extending through the stack 12 generally in parallel with the plane of the girders 20. In each channel a rod 28 is slidably mounted and in compressed and strapped state of pack projecting from both fronts 15, 17 thereof. Each rod 28 is at one end thereof&#39;prpvided with a thin head preventing the adjacent front plate 15, 17 to slide beyond the end of the rod 28. The heads 30 of the two rods 28 are located at opposite fronts 15, 17 of the pack. When the straps 16 are cut offand the stack 12 expands in radial direction of the regenerator body the rods 28 will consequently slide within the pack and each head 30 will contact the respective front plate l5, 17 so that all the plates will be kept in a fixed axial position of the regenerator body relative to each other. The side edges of the plates will further be guided and prevented from tilting by the surrounding radial walls of the body so that the stack 12 will keep its form in spite of the fact that the stack projects outside the ends of the girders 20.  
  The rods 28 further guarantee that the plates of the pack 10 do not move in transverse direction during the transport of the pack from the workshop to the erection site owing to mishaps or careless handling.  
  It is evident that the support members 14 also facilitate the removal of the plates (for instance for replacement) even though measures must be taken to keep the plates together before they are entirely outside the chamber.  
  In British Patent specification No. l2744/7l there is disclosed a machine for cutting and stacking element plates. Such a machine may be controlled such that it stops when the stack has reached a height corresponding to the level at which the centre of gravity of the complete pack is located. At this moment the support member 14 is brought in position along one side of the stack with the lift element 24 resting on the top of the incomplete stack and the machine is restarted. When the stack has reached its predetermined height it is compressed and provided with straps. It may then be tilted to horizontal position and removed from the machine. 1  
  Preferably the thickness of the lift element 24 is smaller than the distance between the middle planes of adjacent plates so that the lift element does not appreciably affects the homogeneity of the stack.  
 I claim:  
  1. A pack of rectangular element plates for rotary regenerative heat exchangers which have a cylindrical regenerator body including radial and circumferential division plates defining walls of sectorial compartments of the regenerator body, said pack of rectangular element plates comprising:  
 a stack of plates which are profiled to form openended passages for the heat exchanging fluids, and have a first pair of opposite edges forming two parallel end surfaces of the stack between which the open-ended passages extend and a second pair of opposite edges forming together with faces of the outermost plates side surfaces of the stack exposed to the walls of the sectorial compartment;  
 means engaging said plates to at least retain said plates in a preset relative alignment;  
 a support member comprising a frame structure supportingly engaging one of said parallel end surfaces of the stack of plates and exposing the side surfaces of the stack; and  
 at least one elongated lift element secured to said frame structure and extending through the stack between two adjacent plates, the free end of said lift element being accessible at the other of said parallel end surfaces and having means adapted to be engaged by a hoisting device, said plates of the stack when positioned in a sectorial compartment being held together and to said lift element by the walls of said sectorial compartment and said frame structure, respectively.  
  2. A pack as defined in claim 1, including means for releasably joining the plate stack to the support memher.  
  3. A pack as defined in claim 2, in which the plate stack is in a compressed state when joined to the support member.  
  4. A pack as defined in claim 3, including strapping means joining the plate stack to the support member.  
 5. A pack as defined in claim 1, in which the frame structure includes two longitudinal girders, extending substantially perpendicular to the plates of the stack, and a number of cross-pieces, extending substantially parallel to the plates and interconnecting said girders.  
 6. A pack as defined in claim 5, in which the contour of the frame structure is substantially similar to that of the contacting surface of the plate stack but of smaller size.  
  7. A pack as defined in claim 6, in which each plate is provided with at least one hole therein, said holes registering with each other to form a channel through the stack generally perpendicular to said open-ended passages, said channel enclosing a rod slidably 10. A pack as defined in claim 5, in which the lift element is secured to one of the cross-pieces.  
  11. A pack as defined in claim 10, in which the thickness of the lift element is smaller than the distance between the middle planes of the two adjacent plates.  
  12. A pack as defined in claim 11, in which the lift element is disposed perpendicularly to the plane of the frame structure.  
  13. A pack as defined in claim 1 wherein said means engaging said plates comprises at least one rod extending through substantially aligned apertures in said plates.  
  14. A pack as defined in claim 13 comprising a pair of said rods, each extending through a plurality of said plates from respective opposite ends of said pack.  
  15. A pack as defined in claim 1, in which said lift element is located so as to substantially pass through the center of gravity of the pack.  
  16. A pack of rectangular element plates for rotary regenerative heat exchangers having walled sectorial compartments, comprising:  
 a stack of plates defining open-ended passages between adjacent plates;  
 means engaging said plates to at least retain said plates in a preset relative alignment;  
 a frame structure on which said plates are mounted and supported; and  
 at least one elongated lift element secured to the frame structure, said lift element having a length so as to extend from the frame structure and to project beyond the plates when the plates are supported on the frame structure, said plates of the stack ,when positioned in a sectorial compartment being held together and to said lift element by the walls of said sectorial compartment and said frame structure, respectively.  
  17. A pack as defined in claim 16, in which the lift element extends through the stack of plates between two adjacent plates.  
  18. A pack as defined in claim 16 wherein said means engaging said plates comprises at least one rod extending through substantially aligned apertures in said plates.  
  19. A pack as defined in claim 16 comprising a pair of said rods, each extending through a plurality of said plates from respective opposite ends of said pack.