US2855346A - Heat exchanger and boiler construction for a sea water evaporator - Google Patents

Description

Oct. 7, 1958 w. R. WILLIAMSON 2,855,346

HEAT EXCHANGER AND BOILER CONSTRUCTION FOR A SEA WATER EVAPORATOR Filed May 3, 1956 2 Sheets-Sheet 1 IN V EN TOR.

W/AZ/AM R. W/LA/AMSO/V (0/9 amt! Oct. 7, 1958 Filed May 3, 1956 W. R. WILLIAMSON HEAT EXCHANGER AND BOILER CONSTRUCTION FOR A SEA WATER EVAPORATOR 2 Sheets-Sheet 2 IN VEN TOR. MZ/AM 1?. W/lZ/flMiO/V ,4 FOR/V1575 United States Patent C HEAT EXCHANGER AllD BOILER CONSTRUC- TION FOR A SEA WATER EVAPORATOR William R. Williamson, Wethersfield, Conn, assignor to The Maxim ilencer Company, Hartford, Conn, a corporation of Connecticut Application May 3, 1956, Serial No. 582,385

2 Claims. (Cl. 202Z35) This invention relates to a sea water evaporator of the general type shown in the Williamson et al. U. S. Patent No. 2,649,408, and the invention involved here relates most specifically to improvements in the boiler and heat exchanger construction for such an evaporator.

As shown and described in the said patent, sea water evaporators of the type under consideration here comprise a substantially Vertical shell which is divided by transverse partitions into a plurality of chambers or compartments. The lowermost compartment may comprise a boiler chamber wherein a heat exchanger is disposed to boil sea Water and drive off steam therefrom. The steam generated in the boiler chamber is then passed into the chamber above the boiler chamber and whirled therein to separate salt-retaining entrained water from the steam. Generally there are two'stages or" water and steam separation, the second or final stage of separation taking place in the third or uppermost chamber of the shell. After final separation of water and steam, the steam is condensed to provide a fresh water supply. Evaporators of this type are used extensively aboard ships to supply fresh water, but such evaporators are also used in land based installations.

The type of heat exchanger employed in the evaporator uses a fluid heating medium and is adapted to receive the heating medium internally and to transfer heat therefrom to sea water in the boiler chamber, the said heat exchanger being disposed within the boiler chamber. This type of heat exchanger has become known as a basket type heat exchanger and is characterized by a vertically disposed generally cylindrical wall which is closed at both ends and which is deeply corrugated to provide a plurality of radially projecting corrugations having longitudinally extending inner and outer recesses. Steam or any other desirable fluid heating medium is introduced to the heat exchanger by means of a conduit extending through one end thereof and is then circulated through the inner recesses of the corrugations to trans fer heat to the sea water. In transferring or giving up heat to-the surrounding sea water, the steam is condensed and flows downwardly into a condensate sump or chest from which it is withdrawn for any desired use.

It is the .generalobject of this invention to provide a sea water boiler and heat exchanger construction of the type described above but which provides greater heat transfer efficiency and which is particularly adapted for access to and removal and replacement of the heat exchanger Within the boiler chamber so that the necessary service and cleaning operations can be accomplished with greater ease.

The more specific objects as well as advantages of the invention will become apparent to those skilled in the art from the following description having reference to the annexed drawing wherein, by way of preferred example only, one specific embodiment of the invention is shown. It will be understood that the drawings and the description of the singleernbodiment shown are not to f atented Oct. 7, 1958 ICC be taken as defining the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawings,

Fig. l is a vertical sectional view taken through the boiler chamber of a sea water evaporator which incorporates my improved boiler and heat exchanger construction;

Fig. 2 is a transverse sectional view through the boiler chamber taken as indicated by the line 22 of Fig. 1; and

Fig. 3 is a fragmentary vertical sectional view of the bottom central portion of the boiler chamber.

As mentioned above, a sea water evaporator of the type shown in the Williamson et al. Patent No. 2,649,408 comprises a substantially vertical shell which is divided into chambers by transverse partitions, the lowermost chamber being the boiler chamber wherein the sea water is evaporated. Heretofore, it has been the practice to provide the shell in substantially cylindrical form. A departure is made from the conventional practice in accordance with the present invention by providing a lower shell or shell section it which is not cylindrical. The lower shell 10 defines the sea water boiler chamber C and is of rectilinear configuration in transverse section, a square section being preferred. The shell 10 is closed at the top and at the bottom by partitions or headers 12 and 14, respectively, which further define or close the boiler chamber C. A cylindrical upper shell or shell section 16 is secured above the square shell ill and defines a separating chamber S wherein entrained water is separated from steam generated in the boiler chamber C. The construction of the separating chamber S and the other elements of the evaporator may be identical or similar to the construction shown in the aforementioned Williamson et a1. patent and further disclosure and description is deemed to be unnecessary for an understanding of the present invention.

A heat exchanger indicated generally by the reference numeral 18 is disposed within the boiler chamber C and is adapted to utilize a fluid heating medium for out-ofcontact heat transfer to sea water within said boiler chamber for the purpose of evaporating the same. The steam produced in such evaporation is discharged from the boiler chamber C through a conduit 20 which extends through the upper shell 16 and is disposed substantially horizontally in the separating chamber S but which has an elbow connection extending through a central opening 21 in the top header 12 of the boiler chamber. The steam which i discharged through the conduit 20 is readmitted to the separating chamber S at a tangential opening (not shown) in the shell 16 so that the said steam will be whirled within the chamber S. The whirling movement separates salt-carrying water from the steam by centrifugal force and the separated water will flow into an annular sump 22 defined below the central opening 21 in the header 12 by the angularly related frusto- conical plates 23 and 25. The salt-concentrated water is removed from the sump 22 through at least one drain conduit 2 extending therefrom and through the boiler chamber shell 10.

A sea water inlet conduit 26 also opens through the shell 10 to admit sea water to the chamber C and a discharge conduit 28 has an opening in the chamber C through the bottom header 14 to receive and discharge brine from the said boiler chamber. A large circular opening is provided in the central portion of the bottom header 14 and the top end of a cylindrical shell 30 is secured therein. The bottom end of the shell 30 is closed by a header 32 to define a condensate chamber or sump 34 for receiving condensate from the heat exchanger 18 as will be more fully described. A conduit 36 is provided in the shell 30 to remove condensate from the sump 34 as desired.

It is a further important aspect and feature of, the

'boiler construction that a substantial opening is provided in one side of the shell for access to the boiler chamber C, the said opening being normally closed by a detachable cover 38. Attachment and removal of the cover 38 is made easy by providing a flange 40 which is welded to the shell 10 externally thereof adjacent and around the opening in the said one side. The flange 48 is provided with a plurality of openings for receiving bolts to secure the cover in place. A suitable seal 42 is located on the flange 40 between it and the cover 38. The purpose of having the opening and the detachable cover 38 is to permit access to the boiler chamber C for cleaning the same and to permit removal and replacement of the heat exchanger 18 which will now be described.

The heat exchanger 18 is in many respects like that shown in the aforementioned patent. That is, the heat exchanger 18 comprises a generally cylindrical heat transfer wall which is disposed vertically within the chamber C and which has a plurality of radially projecting deep corrugations 44, 44 which define internal recesses 46, 46 and external recesses 48, 48. The corrugations 44, 44 are closed at the top 50 and at the bottom 52 whereby the longitudinally extending internal recesses 46, 46 are closed at the ends. The top opening in the cylindrical wall is closed by a dome-like header 54 which is upwardly convex and downwardly concave, the periphery of the header 54 being welded to the radially inner ends of the corrugations 44, 44. A ring 56 is similarly secured at the bottom end of the cylindrical wall and embraces and is secured to a cylindrical shell 58 which extends into the central opening in the bottom header 14 of the boiler chamber. The bottom edge of the cylindrical shell 58 is disposed closely adjacent to the top edge of the shell 30 wherein the condensate. sump 34 is defined. Thus, the shell 58 provides a passage from the generally cylindrical wall of the heat exchanger into the said condensate sump.

An annular flange 60 is secured as by welding or the like around the bottom end of the cylindrical shell 58, and the said flange is detachably secured to the bottom header 14 of the boiler chamber C. An annular seal 62 is provided between the flange 60 and the header 14 and bolts are extended through suitable openings in the flange and the header to secure the flange to the header. When the flange 60 is secured to the bottom header 14, the heat exchanger 18 is supported in the vertical position shown.

Additional support for the heat exchanger 18 is provided by a fluid-directing skirt 64 disposed internally thereof. The skirt comprises a vertically disposed imperforate cylindrical section 66 having an upper end which terminates in spaced relationship to the top header 54 of the heat exchanger and a bottom end which is spaced above the ring 56. A perforate cylindrical section 68 extends between the top header 54 of the heat exchanger and the top edge of the imperforate cylindrical section 66 and is fixedly secured to said top header as by welding or the like. If desired, the perforate cylindrical section 68 may be formed integrally with the imperforate section 66, but is preferably detachably connected therewith. The skirt 64 also includes a downwardly converging frusto-conical section 70 which is secured to the bottom edge of the imperforate section 66 and which extends downwardly to terminate in substantially the same plane as the top surface of the bottom header of the boiler chamber C. The bottom edge of the frusto-conical section 70 snugly embraces the upper end portion of a vertically disposed steam inlet conduit 72 which extends through the bottom header 32 of the condensate chamber or sump 34.

The connection between the frusto-conical section of the skirt 64 and the upper end portion of the steam inlet conduit is merely a sliding connection, no securing means being provided. However, a seal is provided at such connection by means of a frusto-conical collar 74 which is fixedly secured around the steam conduit 72 and which diverges upwardly to provide an annular trough which is packed with grease G and which receives the bottom edge of the skirt. There are several commercially available greases which may be used to seal the connection between the steam inlet conduit and the skirt, the selection of a grease being guided by the desire to use a high viscosity grease and one which is resistant to high temperature. When the skirt is positioned in the manner shown, i. e., with its bottom end in the collar '74, the heat exchanger 18 is additionally supported by the said skirt.

It will be obvious that the heat exchanger 18 and the internal skirt 64 can be removed as a unit merely by removing the bolts from the heat exchanger flange 6i and by lifting the heat exchanger a slight amount so that the bottom edge of the skirt will clear the top end of the steam inlet conduit 72. Then, the unitary heat exchanger and skirt can be removed from the boiler chamber through the side opening provided by removing the cover 38.

It is an important function of the skirt 64 to direct the steam or other fluid heating medium into the internal recesses 46, 46 of the heat exchanger corrugations. As explained in the co-pending application of John P. Tyskewicz, Serial No. 582,371, filed May 3, 1956, if the fluid heating medium is confined to passage within the internal recesses 46, 46, highvelocity flow will occur and heat transfer efficiency will be enhanced. The skirt 64 does confine flow to the internal recesses by reason of its closely spaced or skirting relationship to the radially inner ends of the corrugations 44, 44. The skirt 64 of this invention further enhances heat transfer efficiency by providing the perforate section 68 at the top of the imperforate cylindrical section 66. That is, the perforations in the section 68 provide a plurality of orifices for even distribution or discharge of the steam or other fluid heating medium from within the skirt into the top ends of the recesses 46, 46.

In flowing downwardly within the inner recesses 46, 46 of the heat exchanger corrugations, the steam will transfer heat to the sea water in the external recesses 48, 48 and will be condensed. The downward rush of the steam serves to wipe the condensate from the walls of the recesses and the condensate will flow downwardly into the sump 34. The high velocity downward movement of the steam within the inner recesses provides for improved heat transfer efficiency.

As explained in my copending application Serial No. 563,571, filed February 6, 1956, the sea water boiling in the chamber C rushes upwardly in the external recesses 48, 48. The boiling mixture rushing upwardly in the external recesses is at least partially separated at the annular apex of the frusto- conical plates 23 and 25. defining the annular sump 22. The steam contained in the boiling mixture and a part of the sea water in the mixture passes outwardly through the conduit 20 and the remainder of the mixture, mostly sea water, spills over the top of the currugations 44, 44 and back into the body of sea water within the boiler chamber. As further explained in my said co-pending application, it is desirable to have high velocity circulation of the sea water in the boiler chamber for heat transfer efiiciency. The square or rectangular boiler chamber provided in accordance with the present invention facilitates the sea water circulation and thus enhances the heat transfer efliciency. That is, the square boiler chamber provides ample space at its corners for the return of sea water spilling over the top ends of the heat exchanger corrugations 44, 44. Thus, another, but less apparent, heat transfer advantage is attained with the boiler and heat exchanger construction provided in accordance with this invention.

The advantage of having the heat exchanger and skirt removable as a unit from the boiler chamber is quite apparent. That is, persons skilled in the art will recognize the ease with which the interior of the boiler chamber and exterior of the heat exchanger can be cleaned by removing the heat exchanger. necessary to clean the interior of the heat exchanger and the interior of the skirt, access thereto can be improved merely by enlarging the diameter of the shell 58 so that the cylindrical section 66 of the skirt 64 can be withdrawn through the said shell. It should be noted that the perforate section 68 and imperforate cylindrical section 66 are preferably detachably connected as by interiorally disposed pin and slot type connectors (not shown) or their equivalents so that one section can be attached and detached from the other merely by relative rotation or twisting movement.

The invention claimed is:

1. A boiler and heat exchanger construction for a sea water evaporator and comprising in combination, a substantially vertical shell having a substantial side opening, a cover detachably secured to said shell to close the opening therein, a top header and a bottom header closing the ends of the shell to define a boiler chamber therein, said bottom header having an opening, means defining a condensate sump below the opening in said bottom header, means for introducing sea water to the boiler chamber, conduit means for discharging steam from the boiler chamber, and a substantially vertically disposed generally cylindrical heat exchanger located within said boiler chamber for out-of-contact heat transfer from steam to sea water in the boiler chamber, said heat exchanger being detachably connected to the bottom end header and having a condensate outlet in communication with the opening therein whereby the heat exchanger is supported within the boiler chamber but is removable therefrom through the side opening in the shell, a steam inlet conduit projecting through said condensate sump and the opening in said bottom header to introduce steam If it is believed to be r to the heat exchanger, a collar secured to said steam inlet conduit adjacent its open end, a flow-directing skirt disposed within said heat exchanger and comprising an upper perforate section and a lower imperforate section and also comprising a downwardly converging frustoconical section engaging said collar to support the skirt and to additionally support said heat exchanger, said skirt being constructed and arranged to receive steam from said conduit and to distribute the same within said heat exchanger by discharge through its perforate section.

2. A boiler and heat exchanger construction for a sea water evaporator comprising, a substantially vertical. shell having end headers and a substantial side opening and an opening in the bottom end header, a cover detachably secured to the shell and closing the side opening, means for introducing sea water to the shell, means for discharging steam from the shell, a substantially vertically disposed generally cylindrical closed heat exchanger detachably connected within the shell over said opening in the bottom end header thereof, a steam inlet conduit opening into said heat exchanger through the said opening in the bottom end header of the shell, a

' collar secured to said steam inlet conduit adjacent its open end, and a flow-directing skirt disposed within said heat exchanger with its upper end secured to the upper end of the heat exchanger and with its lower end engaging said collar to support the skirt and additionally to sup port said heat exchanger, said skirt being constructed and arranged to receive steam from said steam inlet conduit and to distribute the same within said heat exchanger for out-of-contact heat transfer to the sea water within the shell.

References Cited in the file of this patent UNITED STATES PATENTS 1,359,276 Rushworth Nov. 16, 1920 1,580,323 Paul Apr. 13, 1926 2,475,481 Clemens July 5, 1949 2,649,408 Williamson et a1. Aug. 18, 1953

Claims (1)

1. A BOILER AND HEAT EXCHANGER CONSTRUCTION FOR A SEA WATER EVAPORATOR AND COMPRISING IN COMBINATION, A SUBSTANTIALLY VERTICAL SHELL HAVING A SUBSTANTIAL SIDE OPENING, A COVER DETACHABLY SECURED TO SAID SHELL TO CLOSE THE OPENING THERIN, A TO HEADER AND A BOTTOM HEADER CLOSING THE ENDS OF THE SHELL TO DEFINE A BOILER CHAMBER THEREIN, SAID BOTTOM HEADER HAVING AN OPENING, MEANS DEFINING A CONDENSATE SUMP BELOW THE OPENING IN SAID BOTTOM HEADER, MEANS FOR INTRODUCING SEA WATER TO THE BOILER CHAMBER, AND A SUBSTANTIALLY VERTICALLY DISPOSED BOILER CHAMBER, AND A SUBSTANTIALLY VERTICALLY DISPOSED GENERALLY CYLINDRICAL HEAT EXCHANGER LOCATED WITHIN SAID BOILER CHAMBER ROR OUT-OF-CONTACT HEAT TRANSFER FROM STREAM TO SEAT WATER IN THE BOILER, SAID HEAT EXCHANGER BEING DETACHABLY CONNECTED TO THE BOTTOM END HEATER AND HAVING A CONDENSATE OUTLET IN COMMUNICATION WITH THE OPENING THERIN WHEREBY THE HEAT EXCHANGER IS SUPPORTED WITHIN THE BOILER CHAMBER BUT IS REMOVABLE THEREFROM THROUGH THE SIDE OPENING IN THE SHELL, A STEAM INLET CONDUIT PROJECTING THROUGH SAID CONDENSATE SUMP AND THE OPENING IN SAID BOTTOM HEADER TO INTRODUCE STEAM

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