US3327777A

US3327777A - Heat interchanger

Info

Publication number: US3327777A
Application number: US409861A
Authority: US
Inventors: Albert E Kovalik; Samuel H S Raub
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1964-11-09
Filing date: 1964-11-09
Publication date: 1967-06-27
Anticipated expiration: 1984-06-27

Description

June 1967 A. E. KOVALIK ETAL 3,327,777

HEAT INTERGHANGER Filed Nov. 9, 1964 2 Sheets-Sheet 1 INVENTORS ALBERT E. KOVALIK SAMUEL H.S. RAUB June 1967 A. E. KOVALIK ETAL 3,

HEAT INTERCHANGER 2 Sheets-Sheet 2 Filed Nov. 9, 1964 INVENTORS ALBERT E. KOVALIK SAMUEL H.S.RAUB

United States Patent O 3,327,777 HEAT INTERCHANGER Albert E. Kovalik, Cleveland, and Samuel H. S. Raub,

Bay Village, Ohio, assignors to Union Carbide Corporation, a corporation of New York Filed Nov. 9, 1964, Ser. No. 409,861 Claims. (Cl. 165-81) The present invention relates, in general to improvements in heat exchangers, and in particularly, to heat exchangers of the shell and tube type, and more particularly to totally enclosed tube bundle heat exchangers of the character containing non-metallic tubes of carbon or graphite construction for conducting corrosive fluid media.

The particular improvement advanced by this invention is directed to novel and improved floating head arrangements.

An excellent heat interchanger of the totally enclosed type wherein certain gaskets are sealed by spring pressure means internally mounted is disclosed in copending United States application Ser. No. 409,860, filed Nov. 9, 1964, the assignee of the subject invention being'also the assignee of the above-referred to application. The heat exchanger disclosed in the copending application comprises a totally enclosed or armored tube type exchanger wherein a carbonaceous tube bundle is fixedly held at one end of the shell and floating supported at the other end thereof. Resilient loading means such as compression springs are positioned within the shell such that the springs and hydraulic pressure impressed by the shell side fluid act in the same direction against the floating end of the tube bundle to compressively load the carbonaceous tubes and to increase the effectiveness of gasket sealing.

This type of heat exchanger like all exchangers, may, by reason of improper use require some maintenance or repair, particularly of the metallic elements or the internally mounted resilient means since the shell side fluid which flows in and around the springs may be corrosive saline water in contrast to fresh water, thus these elements could be subject to corrosion. In addition, when replacing a defective spring one must dismantle most of the floating end of the heat exchanger.

It is, therefore, the principal object of the invention to overcome the disadvantages of the prior art heat exchangers and to provide a floating head arrangement including a tube sheet and closure therefor, wherein the gaskets between the end domes or covers and the tube sheets on both ends of the enclosed tube bundle, and the gaskets between the fixed end plate and the fixed cover are exclusively sealed by spring pressure on the floating end. The use of externally mounted springs in this application is unique in that they maintain the abovenoted gaskets leak tight under all operating conditions of temperature and pressure and they they are readily accessible for ordinary servicing and are not in contact with any fluid media. The tube bundle comprising a plurality of tubes is conventionally stayed by 'bafiles spaced on normal centers along the tube length.

Since the invention is primarily concerned with a floating heat structure arrangement to be used with the more or less conventional 'forms of totally enclosed tube bundle heat exchangers, the other portions of such exchanger including the shell and the fixed end of the tube bundle although shown in the accompanying drawings will not be described in great detail since such heat exchangers are well known and understood by those skilled in the art.

The primary object and other objects and advantages of the invention will be readily understood from the following detailed description when read in conjunction with the accompanying drawing, which illustrates the preferred forms of the heat interchanger, and in which like charac- 3,327,777 Patented June 27, 1967 ters of reference designates like parts throughout the several views, and in which:

FIG. 1 is a side elevation view, partly in section, show ing the preferred form of the invention;

FIG. 2 is another side elevational view, partly in sec- 7 ti-on showing another form of the invention; and

FIG. 3 is a greatly enlarged fragmentary view, largely in section showing the floating end of yet another modified exchanger similar to the exchanger of FIG. 2.

Referring now to the drawings, and particularly to FIG. 1, there is shown a two pass heat exchanger of the shell and tube type generally indicated by the numeral 10. A combined fixed inlet and outlet end dome or cover 12 and a fixed tube sheet 14, both of impervious carbon or graphite, are rigidly aflixed to the longitudinal metallic shell 16 of the heat exchanger 10 'by means of flange 18, end plate 20 and suitable tie-rods and bolts, 22 and 24 respectively. Within the shell 16 is mounted a bundle of uniformly disposed impervious carbon or graphite tubes 26, which pass through correspondingly spaced holes in bafiles (not shown). The fixed tube sheet 14 supports one end of the tubes 26.

Floating tube sheet 30 is in juxtaposition with a closed two pass floating dome or cover 32 also of carbon or graphite. The tubes 26 as is done in the art are conventionally cemented into open-ended sockets in the

tube sheets

14 and 30.

A flange 34 is conventionally secured to the shell 16, such as by welding, and a seal ring 36 which maintains the packing or gasket 38 in place is suitably fastened tightly to flange 34 with the usual connecting rods and

bolts

40 and 42.

The improved feature of the heat exchanger 10 of the invention centers around the floating head arrangement or floating end members which permit the tube bundle (tube sheets, tube 'bafiles, etc.) to be under continuous compressive loading and seal-s the

gaskets

44 and 46 between the

covers

12 and 32 and

tube sheets

14 and 30, and the gasket 48 between the fixed cover 12 and fixed end plate 20. Gasket 50' also provides a seal between flange 18 and fixed tube sheet 14.

A plurality of externally mounted compression springs 52 are positioned about the periphery of end plate 54. Guide and support studs 56 which bear against and maintain the springs 52 in place against the end plate 54 are locked by means of nuts 57 to flange 34. The springs 52 bear against the end plate 54, a gasket-like bearing disk 58 disposed between the end 60 of the floating cover 32 which is seated against the floating tube sheet 30. The floating tube sheet 30 in turn bears toward the fixed tube sheet 14, thus loading the tubes 26 in compression.

It is important to note that the end plate 54 is provided with a projecting tube like element 62 which is adapted to closely fit about the end 60 of the floating cover 32. This element 62 not only renders the floating head arrangement totally enclosed, but it acts in conjunction with the packing 38 located between the seal ring 36 and flange 34 to preclude the shell side fluid from leaking out between the seal ring 36 and the tube-like element 62 and from gaining access to the far end 60 of the floating cover 32. Thus, no hydraulic pressure can be impressed against the cover 32 in the direction of the spring loading.

Since carbon and graphite is much stronger in compression than in tension, it is highly advantageous to utilize the invention for such shell and tube type heat exchangers employing a tube bundle assembly. Moreover, continuous spring loading follows the gasket material under all conditions of cold flow, maintains pres-sure over full range of differential thermal expansion, and eliminates complete relaxation of bolt loading which occurs when the bolt heads rust against their bearing surfaces or when the nuts vibrate loose. Further, the spring loading under these conditions control the gasket loading as opposed to the excessive and variable bolt loading necessary when standard bolts are used to seal the gaskets. Since all of the carbonaceous members are totally enclosed within the shell structure the heat exchanger of the invention can be considered of armored construction.

In FIGURE 2, there is shown a modified form of the heat exchanger of the invention. In this view, the objects of the invention are illustrated as applied to a single pass shell and tube type heat exchanger 66. This embodiment is very similar to the exchanger of FIG. 1 except for the covers and in the arrangement of the floating head. At the fixed end 68 of the heat exchanger 66 the fixed carbon or graphite tube sheet 70 and the fixed dome or cover 72 is fixedly secured to the shell 74 and fixed end plate 78 by conventional securing means, such as nuts and bolts 80 and 82, respectively. The carbon or graphite tubes 84 joining the fixed tube sheet 70 and the floating tube sheet 86 are, of course, as is conventionally done in the art, stayed and braced by suitable baflies (not shown).

Gaskets

88 and 90 are respectively located between floating cover 92 and floating tube sheet 86 and the fixed end tube sheet 70 and cover 72. These gaskets as well as gasket 94 disposed between the fixed cover 72 and fixed end plate 78 are similarly held under compressive loading by a plurality of springs 96 which bear against the floating end plate 98, and a gasket-like bearing disk which in turn bears against the floating cover 92.

In this modification, flange 102 which is suitably welded to the shell 74, is used as the anchoring means for the seal ring 106 and the floating end plate and projecting tube-like element 98 and 108 respectively. Seal ring 106 maintains packing or gasket 112 in place, which gasket precludes shell side fluid leakage from between the seal ring 106 and tube-like element 108. The seal ring 106 also contributes in totally enclosing the heat exchanger, if desired, seal ring 106 can be eliminated if gasket 112 is placed in a suitable groove or channel. Of course, the tube sheet and cover must still be enclosed by other means such as a sleeve like exterior of the flange which would telescope inside the tube-like element 108. As mentioned in connection with FIG. 1, there also is no hydraulic pressure impressed against the cover 92 in this modification.

If desired because of space requirements or other reasons, the springs 96 may be located on the opposite side 110 of the flange 102 as shown by the phantom (dotted) lines. This of course, would facilitate access to the end plate 98 more readily, particularly when assembling a conduit to the floating end plate studs 114. Regardless of where the springs are mounted, they must still be unloaded when removing either the fixed or floating cover.

FIGURE 3 shows the construction of another modified floating head arrangement of a totally enclosed tube bundle heat exchanger. The structure of this partially shown heat exchanger is similar to that described in connection with FIG. 2, but differs in that the end plate 118 is limited in diameter to about the size of the shell 120 and a peripheral flange 122 is provided about the end 124 of the tube-like element 126. These parts are conventionally secured together, such as by welding and the peripheral flange 122 is employed as a bearing surface for springs 128 which are guided and supported by studs 130 locked by means of nuts 132 to flange 134.

The advantages of the invention may be summarized as follows: the improved heat exchanger provides compressive spring loading as opposed to the excessive and variable bolt loading necessary when standard bolts are used to seal the gaskets in heretofore totally enclosed tube bundle heat exchangers, spring loading of the gaskets is provided for under all conditions of cold flow, uniform pressure is maintained over full range of differential thermal expansion and relaxation of bolt loading which 4 occurs when the bolt heads rust against their hearing surfaces or when the nuts vibrate loose is eliminated.

What is claimed is:

1. A heat exchanger, comprising a shell, a tube bundle therein, a floating tube sheet for slidably supporting one end of said tube bundle within said shell, a flange on said shell at the floating tube sheet end thereof, a floating cover abutting said floating tube sheet, an end plate for the floating end of said heat exchanger, a tube element secured to said end plate, said tube element being adapted V to closely fit about the endof said floating cover whereby shell side fluid is prevented from leaking out of said exchanger and whereby hydraulic pressure is prevented from being impressed against saidcover, and resilient loading means disposed about means for securing said end plate to said flange for loading the tubes of said tube bundle compressively.

2. The heat exchanger of claim 1 wherein said resilient means comprise a plurality of compression springs positioned about a plurality of studs which maintain said compression springs in place against said end plate.

3. A heat exchanger, comprising a shell, a tube bundle therein, a fixed tube sheet for supporting one end of said tube bundle Within said shell, a fixed cover and a gasket between said fixed tube sheet and said fixed cover, a floating tube sheet for slidably supporting the opposite end of said tube bundle within said shell, 21 flange on said shell at the floating tube sheet end thereof, a floating cover and a second gasket between said floating tube sheet and said floating cover, an end plate for the floating end of said heat exchanger, a tube element secured to said end plate, said tube element being adapted to closely fit about the end of said floating cover whereby shell side fluid is prevented from leaking out of said exchanger and whereby hydraulic pressure is prevented from being impressed against said cover, and resilient loading means disposed about means for securing said end plate to said flange for loading said gaskets compressively.

4. A heat exchanger, comprising -a shell, a tube bundle therein, a fixed tube sheet for supporting one end of said tube bundle within said shell, a fixed cover and a gasket between said fixed tube sheet and said fixed cover, an end plate for the fixed end of said heat exchanger and a second gasket between said fixed cover and said end plate, a floating tube sheet for slidably supporting the opposite end of said tube bundle within said shell, a flange on said shell at the floating tube sheet end thereof, a floating cover and a third gasket between said floating tube sheet and said floating cover, a second end plate for the floating end of said heat exchanger, a tube element secured to said end plate, said tube element being adapted to closely fit about the end of said floating cover whereby shell side fluid is prevented from leaking out of said exchanger and whereby hydraulic pressure is prevented from being impressed against said cover, and resilient loading means disposed about means for securing said end plate to said flange for loading said gaskets compressively.

5. A heat exchanger, comprising a shell, a tube bundle therein, an impervious carbonaceous tube sheet fixed to one end of said shell for supporting one end of said tube bundle Within said shell, an imprevious carbonaceous fixed cover and a gasket between said fixed tube sheet and said fixed cover, an impervious carbonaceous floating tube sheet for slidably supporting the opposite end of said tube bundle within said shell, a flange on said shell at the floating tube sheet end thereof, an impervious carbonaceous floating cover and a second gasket between said floating tube sheet and said floating cover, an end plate for the floating end of said heat exchanger, a tube element secured to said end plate, said tube element being adapted to closely fit about the end of said floating cover whereby shell side fluid is prevented from leaking out of said exchanger and whereby hydraulic pressure is prevented from being impressed against said cover and resilient loading means disposed about means for securing said end plate to said flange for loading said gaskets and the tubes of said tube bundle compressively.

6. A heat exchanger comprising a shell, an impervious carbonaceous tube sheet fixed to one end of said shell, an impervious carbonaceous floating tube sheet at the opposite end of said shell, a bundle of substantially parallel impervious carbonaceous tubes extending between said tube sheets and communicating with corresponding openended sockets in said tube sheets, a flange on said shell at the floating tube sheet end thereof, an impervious carbonaceous floating cover abutting said floating tube sheet, an end plate for the floating end of said heat exchanger, a tube element secured to said end plate, said tube element being adapted to closely fit about the end of said floating cover whereby shell side fluid is prevented from leaking out of said exchanger and whereby hydraulic pressure is prevented from being impressed against said cover, and externally mounted resilient loading means disposed about means for securing said end plate to said flange for loading said tubes compressively between said tube sheets.

7. The heat exchanger of claim 6 wherein said resilient means comprise a plurality of compression springs positioned about a plurality of studs which maintain said compression springs in place against said end plate.

8. A heat exchanger comprising a shell, a tube bundle therein, a floating tube sheet for slidably supporting one end of said tube bundle within said shell, a flange on said shell at the floating tube sheet end thereof, a floating cover abutting said floating tube sheet, an end .plate and housing for substantially covering said floating cover, a tube element secured to said end plate, said tube element being adapted to closely fit about the end of said floating cover whereby shell side fluid is prevented from leaking out of said exchanger and whereby hydraulic pressure is prevented from being impressed against said cover, a gasket disposed between said floating tube sheet and said flange, a ring for maintaining said gasket in place secured to said flange, and resilient lOading means disposed about means for securing said end plate to said flange for compressively loading the tubes of said tube bundle.

9. A heat exchanger comprising a shell, a tube bundle therein, a floating tube sheet for slidably supporting one end of said tube bundle within said shell, a flange on said shell at the floating tube sheet end thereof, a floating cover abutting said floating tube sheet, an end plate and tubular shaped sleeve for substantially covering said floating cover, a tube element secured to said end plate, said tube element being adapted to closely fit about the end of said floating cover whereby shell side fluid is prevented from leaking out of said exchanger and whereby hydraulic pressure is prevented from being impressed against said cover, a gasket disposed between said floating tube sheet and said flange, a ring secured to said flange disposed between said tubular shaped sleeve and said floating tube sheet and said cover for maintaining said gasket in place and resilient loading means disposed about means for securing said end plate to said flange for compressively loading the tubes of said tube bundle.

10. A totally enclosed heat exchanger comprising a shell, a tube bundle therein, a floating tube sheet for slidably supporting one end of said tube bundle Within said shell, a flange on said shell at the floating tube sheet end thereof, a floating cover abutting said floating tube sheet, an end plate and housing for substantially covering said floating cover, a tube element secured to said end plate, said tube element being adapted to closely fit about the end of said floating cover whereby shell side fluid is prevented from leaking out of said exchanger and whereby hydraulic pressure is prevented from being impressed against said cover, a gasket disposed between said floating members and said flange, and resilient loading means disposed about means for securing said end plate to said flange for compressively loading the tubes of said tube bundle.

References Cited UNITED STATES PATENTS 464,159 12/1891 Link -82 826,966 7/1906 Schneible 16582 1,591,174 7/1926 Mailey 165-81 X 2,887,303 5/1959 Reys 16582 2,956,787 10/ 1960 Raub 165-82 3,221,808 12/1965 Pyle 165158 FOREIGN PATENTS 1,211,918 10/ 1959 France.

908,028 4/ 1954 Germany.

929,701 6/ 1963 Great Britain.

ROBERT A. OLEARY, Primary Examiner. A. W. DAVIS, Assistant Examiner.

Claims

1. A HEAT EXCHANGER, COMPRISING A SHELL, A TUBE BUNDLE THEREIN, A FLOATING TUBE SHEET FOR SLIDABLY SUPPORTING ONE END OF SAID TUBE BUNDLE WITHIN SAID SHELL, A FLANGE ON SAID SHELL AT THE FLOATING TUBE SHEET END THEREOF, A FLOATING COVER ABUTTING SAID FLOATING TUBE SHEET, AN END PLATE FOR THE FLOATING END OF SAID HEAT EXCHANGER, A TUBE ELEMENT SECURED TO SAID END PLATE, SAID TUBE ELEMENT BEING ADAPTED TO CLOSELY FIT ABOUT THE END OF SAID FLOATING COVER WHEREBY SHELL SIDE FLUID IS PREVENTED FROM LEAKING OUT OF SAID EXCHANGER AND WHEREBY HYDRAULIC PRESSURE IS PREVENTED FROM BEING IMPRESSED AGAINST SAID COVER, AND RESILIENT LOADING MEANS DISPOSED ABOUT MEANS FOR SECURING SAID END PLATE SO SAID FLANGE FOR LOADING THE TUBES OF SAID TUBE BUNDLE COMPRESSIVELY.