US2223313A - Heat exchanger - Google Patents

Description

Nov. 26, 1940.

R. R. COLLINS HEAT EXGHANGER Filed sept. 14, 1939 INVENTOR @www @am By/ v ATTORNEY Patented Nov. 26 1946 UNITED STATES PATENT OFFIC if" maar EXCHANGER Application September 14, 1939, Serial No. 294,796

3 Claims.

This invention relates to improvements in heat exchangers and more particularly to improvements in the floating head construction thereof.

It is known that in heat exchangers of the 5 shell and tube type, it is commonly found desirable to provide a iloating tube sheet of a diameter smaller than the interior of the shell in order that the tube bundle may be withdrawn as desired. Such tube sheet is provided with a oating tube sheet cover by which the ow through the various tubes is redirected and such cover is customarily7 removable in order that the tubes may be cleaned. Such cover should be removable from the oating tube sheet end of the exchanger so that complete dismantling of the exchanger is unnecessary at each cleaning operation.

The manner of securing the floating head cover to the oating tube sheet of a shell and tube type heat exchanger has been the subject of considerable thought, due to the fact that space limitations and pressure limitations prevent a simple solution of the problem. lit is not only desirable to remove the tube sheet through the shell, but it is equally important to keep the shell diameter as small as possible to avoid excessive costs oi.' shell and ilanges and to have a highly emclent heat exchanger with a minimum volume with respect to the number of available tubes.

In the past, it has been suggested that individual bolts of J form. or splitl rings be used. The J bolts were spaced around the periphery of the cover and of necessity gave intermittent contact. 'I'he split rings were more eective in securing the joint, but elaborate means were required to prevent the split ring segments from canting outward and destroying the seal. .afterexpansion and contraction, it was almost impossible to have a tight joint between the cover and tube sheet. It has also been suggested that the cover be 0 bolted directly to the tube sheet, but this requires a substantial extension of the rim of the cover and of the tube sheet which requires an increased shell diameter. It thebolts are projected through the cover, leaking invariably occurs.

The principal object of the present invention is to provide an improved heat exchanger having a floating head cover which is provided with a depending integral skirt portion overlapping a split interlocking ring for securing the cover to the tube sheet, suchcoyer thereby also preventing the interlocking ring from canting on application of sealing pressures.

A more specific object of the invention is to provide an improved type of interloc split ring for securing the iloating head cover to the. floating tube sheet of a shell and tube type heat exchanger, in which the split ring is of inverted T shape with a substantial lever arm acting as a beam for reinforcing the tube sheet and oering 5 a substantial support for the floating head cover securing means.

Further objects and advantages of my invention will appear from the following disclosure of a preferred form of embodiment thereof, taken in lo connection with the attached drawing, in which Fig. l is a central vertical section of the iloating tube sheet end of the heat exchanger;

Fig. 2 is a partial horizontal section taken substantially along the line 2 2 of Fig. l; 15

Fig. 3 is a detailed vertical section taken substantially along the line 3-3 of Fig. 2;

Fig. 4: is a perspective View of a part of the retaining ring.

In accordance with a preferred form of em- 20 bodiment of my invention, the shell it is of a typical heat exchanger and has anges ii,\to which the shell cover i2 is secured as by its flanges I3. Within such shell is a tube bundle generally .indicated at ill, consisting of a plurality 25 of tubes which terminate in the floating tube sheet i5. A floating tube sheet of this type is generally necessary to take care of the normal expansion and contraction of the tubes, as it is customary for the other end of the tubes to be 3@ secured to a fixed tube sheet (not shown) which is anchored to the. shell. The iloating tube sheet i5 is of a diameter smaller than the internal diameter of the shell lo, so that it may be withn drawn with the tube bundle. 3

A iloating head cover I6 is provided for the tube sheet i5 so that liquids passing through certain of the tubes in the tube bundle it may be redirected to other tubesin the bundle. The cover i6 must be secured to the oating tube m sheet i5 in a pressure tight manner. In the present construction, the cover iii `is provided with a rim. il, which engages a gasket i t, as more particularly shown in detail in Fig. 3, and the tube sheet i5 terminates at the line ld only a 45 slight distance beyond the edge of the gasket it. The securing bolts 2t clear the outer diameter These bolts 2t project through an interlocking ring t2, a portion of which is shown in Fig. i, 5o such ring being of inverted T shape having an upstanding arm 23 and a crosspiece it'. 'The assembly is illustrated in Fig. 3, it being noted that the inwardly extending portion of the cross piece 2t projects under the tube .sheet it and the 5d arm 23 extends upwardly and in close contact with the outer diameter i511 of the tube sheet. This ring 22 is of segmental construction, preferably being in two pieces, and is suitably drilled as at 25 to receive the bolts 20, which extend from the boss 86a on the edge of the cover i6 and project downwardly through the segmental ring 22 to hold the cover to the tube sheet. The arm 23 can be substantially the same width as the thickness of the bolts without increasing the diameter of the parts, and such increased width greatly improves its characteristic as a beam, not only to prevent canting, but to improve the strength between bolts thereby improving the continuity of seal between cover and tube sheet.

As the bolts 20 are beyond the edge of the tube sheet, the out-of-line stresses are such that there is a couple tending to rotate the segments of the ring away from the bottom of the tube sheet and under variations in temperature the excess loading has been known to deform the parts such that when the parts become cool leakage occurs. In my construction, however, the T-shape of the segmental ring 22 acts as a substantial beam, the arcuate form of which serves to resist, to a. high degree, the tendency of the ring to cant outward.

' In addition, the cover i6 has -a continuous ring skirt portion IBb which surrounds the marginal portion of the tube sheet and overlaps the arm portion 23 of the ring 22 to such an extent that canting is completely resisted.

The construction is extremely simple to manu-' facture. The cover I6 is readily machined to a diameter to embrace the ring 22 and there are no substantial changes of diameter or shape.

The ring 22 is also made as a simple machine operation and may be suitably split after machining. There are a minimum number of parts, and,

the mere assembly of the apparatus insures that all the parts are in place. The contact is with substantially the entire periphery of the tube sheet, and the boss Ilia and depending skirt |617 of the cover; as well as the T shape of the ring,

act as beams between securing bolts 20, and fewer bolts for a uniformly tight seal can be used. There is also established a minimum size of tube sheet for the number of tubes as the tube sheet has but the single function of anchoring the tubes. The bolt diameter for bolts 20 is also a minimum for clearance of the tube sheet, with a resulting smaller shell cover.

While I have shown and described a preferred form of embodiment of my invention, I am aware that modications may be made thereto, and I,

therefore, desire a broad interpretation of mf' invention within the scope and spirit of the description herein and of the claims appended hereinafter.

I claim:

1. In a heat exchanger having a shell, a tube bundle therein, a tube sheet for one end of the tube bundle, a cover for said tube sheet having a rim ,engaging the outer face thereof, said cover having a projecting marginal portion surrounding the tube sheet and spaced therefrom to form a marginal channel, the combination of a ring member having a stem portion in the channel embracing the periphery of the tube sheet and embraced by the marginal portion of the cover, said ring member having an integral inner shoulder portion underlying a part of the tube sheet and securing means extending through the ring member, in the channel portion, and through the cover for securing said cover to said tube sheet.

2. A heat exchanger of the class described in claim l, in which the ring member is of inverted T-shape having a portion underlying in part the marginal-,portion of the cover to form a support forthe securing means.

3. In a heat exchanger having a shell, a tube bundle therein, a tube sheet for one end of the tube bundleand a cover for said tube sheet, said cover having arim. engaging the outer face of the tube sheet, said cover having a projecting marginal portion surrounding the tube sheet and spaced therefrom to form a marginal channel, the combination of means for securing said cover to said tube sheet, said means including a plurality oi.segments forming a ring, said segments being T-shaped in cross-section, the stem of which extends into said marginal channel and embraces the periphery of the tube sheet and is Aembraced by the marginal portion of the cover, the head of said ring having a shoulder portion engaging under the periphery of the tube sheet and a. second portion projecting under the pev ripher-y of the marginal portion of the cover,

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