Rotary Drum Heat Exchanger

This invention relates to a rotating drum type heat exchanger. The object of the invention is to provide a heat exchanger able to recover the residual heat in waste fluids of any nature and origin, in particular sludge, waste water, etc., containing solids in suspension, such as discharge waters from chemical processors in general, particularly bleaching and dyeing plants, etc.

A further object of the invention is to provide a heat exchanger of this type that permits, under any operating conditions, a continuous and efficient heat exchange between the two fluids as a function of temperature, and also permits easy accessibility to the different parts of the heat exchanger itself (especially to the parts handling sludge and/or waste water) for periodic cleaning, maintenance, etc.

The heat exchanger according to this invention embodies a shell provided with fittings for inlet and discharge of the fluids to be treated. At least one rotor is rotatably housed in said shell and consists of a series of hollow bodies provided with internal diaphragms to regulate the flow of the other liquid under treatment. These hollow bodies are connected hydraulically to each other in succession, and their ends are joined with adequate fittings by means of rotary seals in order to permit circulation in counter-current of the other liquids under treatment in the rotor.

In one preferred embodiment of the heat exchangers of the of the invention, the shell (which rotatably houses at least one rotor) is provided with perforated supporting gudgeons at its opposite ends. The gudgeons connect the chambers of the hollow bodies with the exterior, and are held by supports connected movably to the side walls of the shell. The openings in the gudgeons are hydraulically interconnected by means of the sealing devices in the fixed gudgeons, which are in turn fastened to a base structure by means of supports which permit convenient rotation of the rotor and capsizing of the shell for cleaning and maintenance of the different parts of the heat exchanger.

The invention will now be described in detail in conjunction with the drawings, which illustrate by way of example only one preferred embodiment of the heat exchanger according to the invention, used mainly (but not exclusively) for heat recovery from waste waters.

FIG. 1 is a front view in cross section of the heat exchanger of the invention.

FIG. 2 is a view of the end of the heat exchanger of FIG. 1.

FIG. 3 is an axial cross-section of the right hand end of the heat exchanger shown in FIG. 1.

The heat exchanger illustrated in the drawings comprises a Shell A, in which one of the two fluids under treatment is caused to circulate. The shell A houses, rotatably, one or more drums or rotors B in which a second liquid under treatment circulates in counter-current.

In the depicted embodiments shell A includes a substantially parallelipiped shaped vessel 10, the opposite end walls 12 and 14 of which are suitably reinforced and provided with respective supports 16 and 18 in their central part, which supports project toward the interior of the vessel 10 itself. Each one of supports 16 and 18 is operationally associated with roller bearings 20 (see FIG. 3) of rotary sealing elements 22 for tubular gudgeons 24 and 26 projecting longitudinally or axially outward from end walls 12 and 14 of the vessel 10. The inside ends of the gudgeons 24 and 26 terminate with flanges 28 and 30, secured to gudgeons 24 and 26 and also to the walls 12 and 14 of vessel 10. Moreover, flanges 28 and 30 are suitably perforated to receive screws 25 which secure said supports 16 and 18 to walls 12 and 14 of the vessel 10. The ends of the gudgeons 24 and 26 are connected hydraulically via rotary seals 22 to the hollow ends 32 and 34 of a shaft 36 carrying rotors B. The end surfaces of shaft 36 are flush with the longitudinally inward surface of flanges 28 and 30, respectively, to permit removal of rotor B from shell A, if necessary.

It follows that rotor B is rotatably supported in shell A and connected hydraulically to the exterior via removable fittings 38 and 40 in the free ends of tubular gudgeons 24 and 26, to connect gudgeons 24 and 26 with the pipes carrying the second of the two liquids under treatment.Tubular gudgeons 24 and 26 are secured to brackets 42 and 44, respectively. The brackets 42 and 44 are located at the top of stanchions 46, the latter being in turn anchored to base plate 48. A latching device 50 is supported by each bracket. A part of the brackets permit removal of shell A from its associated base plate 48, while the remaining parts engage the side end walls 12-14 of the shell A and hold this in working position (as shown on the drawings) or in the capsized or overturned position to which the shell A can be rotated around gudgeons 24 and 26 to permit cleaning of vessel 10.

It will be clear from the above-description that shell A can be locked in the working position by means of a single set of latches 50 which could consist, for example, of devices adequate to secure the arms of brackets 42 and 44 to each other and hence also gudgeons 24 and 26.

Shaft 36 of rotor B securely holds a plurality of lenticular shaped hollow bodies 52 arranged coaxially on shaft 36 and adjacent to each other. These lenticular bodies 52 each consist of two concave covers or caps 54 and 55 (see FIG. 3) whose edges are joined, for example, by welding.

The centers of the covers or caps 54 and 55 perforated, and edges 56 and 57 of the perforations are oriented in opposite directions to engage, head to head (and in seal tight relation) edges 57 and 56 respectively, of adjacent hollow bodies 52. Said hollow bodies 52 are in turn secured to shaft 36 by two sets of perforated diaphragms 58 and 60 interposed between the hollow bodies 52. Specifically: the first annular diaphragm 58 is formed by rings with edges folded over to partially engage said shaft 36; the remaining folded edges 56 and 57 of two adjacent bodies 52 are joined to each other, for example by the welding of two contiguous hollow bodies 52, whilst the intermediate walls of rings forming diaphragm 58 are perforated.

Annular diaphragms 60, on the other hand, consist of perforated discs extending from shaft 36 into the interior of hollow bodies 52; The folder inner edges 62 of these perforated discs engage shaft 36. The radially outer zones of said discs, on the other hand, are secured and locked in place, for example by welding, between the internal opposite faces of indentations 64 and 65, which project into the interior of hollow body 52. Ridges 64 and 65 are suitably spaced with respect to each other to provide a set of three communicating chambers C.sub.1, C.sub.2 and C.sub.3 inside each hollow body 52. Edges 56 and 57 of the longitudinally outermost of hollow bodies 52 are joined by welding to caps 55. The bottom parts of caps 55 are perforated to permit insertion of hollow ends 32 and 34 of shaft 36. The hollow end portions 32 and 34 of the shaft 36 are also provided with perforations, radially, to allow communication between annular chambers C.sub.4 in the caps 55 and chambers C.sub.1 -C.sub.3 bodies 52. The presence of diaphragms 58 and 60 inside hollow bodies 52 imparts adequate stiffness to bodies 52, even if these bodies are of considerable size and are necessarily fabricated of thin steel plate material.

Additional, fixed diaphragms 66 are arranged and firmly secured inside vessel 10 and extend over its full height. According to this particular arrangement, a succession of chambers is formed inside the vessel, said chambers being hydraulically connected to each other through openings 68 in the top part of the single diaphragms 66; these openings 68 permit passage of the collar formed by the folded edges 56 and 57 of hollow bodies 52.

Rotor B is caused to rotate at a suitable speed by a motor D secured by means of plate 70 to the top part of vessel 10. The motor is hydraulic and advantageously drives rotor B by means of a pinion 72, chain 74 and crown wheel 75.

The first hydraulic loop of the exchanger takes one liquid to be treated in the case of the preferred embodiment sludge, waste water, etc. from a duct 76 in end wall 12 and feeds it into vessel 10. The opposite end wall 14 is provided with an elbow shaped discharge duct 78 leading into an overflow vessel or weir 80 provided with a bottom drain 82.

The diameter of these ducts is related to the nature and flow rate of the fluid under treatment, which, as stated above, may be sludge or waste water.

The arrangement described permits liquid flow from inlet to outlet practically without obstructions, especially in its flow through the chambers formed by diaphragms 66. The bottom part of these diaphragms, may be provided, if necessary, with flow orifices or ports.

The second hydraulic loop of the heat exchanger operates in counter current with the first. The second liquid enters from detachable fitting 40; after flowing through the first collecting chamber C.sub.4 the liquid flows in succession through chambers C.sub.1, C.sub.2, C.sub.3 of all the bodies 52 to collect finally, in the other chamber C.sub.4 and discharge through port 38.

The objects of the invention are thus fully conformed i.e. heat recovery from residual liquids in general which may also come in the form of sludge; moreover, the heat exchanger surfaces of rotor B are continually renewed with respect to the circulating liquid in vessel 10, thus ensuring constant heat exchange and, consequently, optimum thermal efficiency.

It is likewise confirmed that scale formed on the heat exchanger's metal surfaces is easily removable both from shell A and from rotor B, as the rotor B can be disassembled from the shell via latches 50 and related screws 25 which secure supports 18 to walls 12 and 14 of vessel 10, since the surfaces at which ends 32, 34 of shaft 36 and those of gudgeons 24 and 26 meet coincide with the faces of flanges 28 and 30. All outer surfaces of the exchanger are thus made accesible to the cleaning media (water jets, brushes, etc.) and in particular the internal surfaces of vessel 10. Once cover 84 and rotor B are removed from the vessel 10, the vessel 10 can be conveniently overturned on gudgeons 24 and 26. If necessary, diaphragms 66 can also be removed, in case they are secured to the walls of vessel 10, for example, by fitting said walls with guides to hold the diaphragms 66 slidably.

It will be clear to those skilled in the art that various modifications and changes may be introduced, depending on particular application requirements, without departing from the spirit and scope of this invention.