US1524595A - Heat exchanger - Google Patents

Description

Jan, 27, 1925.

C. W. SWARD HEAT EXCHANGER Filed Sept. 18, 1922 f J -VI/I,

ATTORNEY @ma d. a?, i

CEGIL WILL SWARD, OF CHICAGO, ILLINOIS, .ASSIGNOR TO THE surseoir-RUSSELL comm, or new Yoan, n. Y., A CORPORATION or DELAWARE HEAT EXCHANGER Application led September 18, 1922. Serial No. 588,929.

To all whom t may cmwem:

Be it known that I, CEGIL `W1LLIAM Swann, a citizen of the United States, resid- Iing at Chicago, in the county of Cook,

a State of Illinois, have invented certain new and useful Improvements Ain Heat EX- changers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable .10 others skilled in the art to which it appertains to'make and use the same.

The present invention relates to heat intercha-ngers and has to do particularly with that type of heat interchanger in which the heat interchange fluids are both liquids, al-

though the apparatus may be used as a condenser, or t-he like, if desired.

Apparatus at present employed as heat interchangers of the character referred to,

usuallyV comprises an outer shell and a plurality of metallic n tubes extending through the shell. One of the heat interchanging liquids is passed from one end of the shell to the other through the metallic tubes while the other liquid is circulated about in the space within the shell so that it comes in contact with the outer walls of the tubes, the heat interchange occurring through the metal of the tubes. Suitable inlet and outlet openings are, of course, provided at the respective ends. of the apparatus. One objection to apparatus of this nature is the stresses which result from expansion and contraction of the tubes and other parts with changes in temperature.

The general direction of the two liquids through the shellis usually opposite, inasmuch as by thus employing the counter current principle a better heat transfer results.' F or instance,-if the incoming fluid is, say, a hot liquid, and the cooling liquid is passed through the shell in a direction counter to the flow of the hot liquid, the hot liquid immediately as itenters the apparatus will come into heat transferring relation with that portion ofthe cooling liquid which has already traversed the length vof the shell and which has consequently been warmed considerably by the heat derived from the hot walls of the tubes.

As the liot liquid passes on through the shell it gradually becomes cooler, but near the outlet end of the shell it is in contact with the freshly admitted cooling fluid whose temperature is relatively 10W. In

` this manner the hot 'Huid as itis discharged tact between the heat interchanging liquids l' and the heat transferring surfaces of the tubes.' For this purpose baiies are generally provided 'to cause the fluid inthe space within the shell to follow a circuitous path so that the entire volume of thefluid will be brought repeatedly in to direct contact with the tubesurface's. This is particularly true when one -or more of the heat interchanging fluids are Viscous in character or are of such nature that their viscosity changes with changes in temperature, such as oils. Itis furthermore desirable to maintain at all points as great a. temperature difference between `the heat interchanging fluids as 'is possible and also to produce as high a velocity of the fluid along the heat transferring surfaces as ispracticable without unduly increasing the total pressure difference required across the apparatus to maintainy a 'continuous4 flow. In order to provide for sufficiently lhigh velocities the diameter of .the apparatus is more or less restricted between certain limits. That is, according to the best theoretical conditions the apparatus is usually relatively long and slender, the diameter being greatly less than the total length of the apparatus which must be sufficient to maintain the heat interchanging liquids in heat transferring relation for such a length of time as will insure proper temperature results, and which frequently proves to be inconvenient from the standpoint of manufacture or installation.

It is an object of the present invention to provide a heat interchange apparatus particularly adapted for effecting heat transfer between two liquids in which the liquids are directed repeatedly into contact vwith the heat. transferring surfaces so that a complete heat transfer is assured, andin which the fluid passages may be made. sufficiently long to obtain the desired temperature results under all conditions without necessitating a total length of apparatus greater than the length of tubes which can be satisfactorily obtained on a commercial scale or increasing the length of the apparatus to 'transferring provide a single in which the heat interchanging apparatus of the abovev general type 1n which counter flow of the heat interchanging fluids is obtained throughout and which at the same time permits of a wide variatio'n in design as to the type of baffle which may be used for directing the flow of the liquid, and the like, whereby the apparatus is readily adaptable to the varying operating conditions encountered in practice.

ln an apparatus embodying my invention one of the heat transferring liquids is preferably conveyed by means ot metallic tubes extending longitudinaly of the apparatus, suitable heads being provided at the ends of the apparatus tor admitting and discharging the liquid. v'llhe entire body of tubes. is constructed as a single unitary bundle, and the tube ends at one extremity of the bundle are secured in a rigidly supported tube sheet while the tube ends at the other extremity of the bundle are supported in such manner as to permit of longitudinal expansion and contraction of the tubes under the influence of temperature changes and thus avoid stresses which would normally result. Although'the tube bundle is thus formed as a single unit, l may nevertheless arrange a plurality of Huid circuits through' the tubes of the unit. For instance, l may divide the tubes into two secf tions, one of .which conveys fluid in one direction through the shell and the other of which conveys the fluid on its return passage in the opposite direction. The circulating 'liquid' is contained in the space surrounding the tubes and suitable 'passages and guiding walls are provided to direct its flow in a circuitous fashion about the tubes so thatadequate heat interchange will be insured,

'the general direction of dow ot the cooling Huid following the. flow of fluid through the passages formed by the gro-ups of tubes but in a reversev direction so that the advantages of the counter flow method may be obtained. ln this manner l am able to secure a fluid-passage through the heat transerring tubes of length which is a multiple of `the length of the apparatus and also a. passage for the working fluid many times the length of the shell and of such nature as of vthe heat neaaeea to repeatedly bring the entire volume of the working duid into intimate contact with the heat transferring surfaces of the tubes.

I have illustrated a preferred embodiment of my invention in the accompanying drawings in which Figure lis a longitudinal sectional view illustrating an apparatus embodying my invention.y Fig. 2 is a. transverse sectional view of the apparatus shown in Fig. 1; Fig. 3 is a partial sectional view similar to Fig. l illustrating a modification; Fig. 4 is a transverse sectional view illustrat-ing a detail of the apparatus;` and Fig. 5 is a plan view of a special type ofbaiie.

Referring to the drawings, l indicates the containing shell of the apparatus, and 2 indicates the plurality of longitudinal heat transferringvtubes which extend lengthwise of the shell and whose walls constitute the heat transferring surfaces of the apparatus. The upper ends of the entire group of tubes 2 are expanded or otherwise secured in a tube sheet 3 fitting upon the upper end ot the shell l. At their lower ends the tubes 2 are secured in one wall of a head or chamber d, which chamber is of outside diameter substantially equal to the inner diameter of the shell so that the entire head t is free to move longitudinally of the shell under the induence ot the expansion or. contraction of the tubes.' A ring ot packing 5 and a retaining flange 6 serve to keep the joint between thev head All and the adjacent shell walls fluid-tight. By this arrangement strains on the tubes'or other parts ot the apparatus due to sudden temperature changes are alvoided. The head 4 may be a closed chamber fitted with a cover plate 7, as shown, in order to render it fluid-tight. lt is particularly to be noted that the entire construction of the apparatus is essentially lunitary in nature, and the entire group of tubes is assembled and built as a single bundle which is tree to move as a unit under the influence of temperature changes.

At the upper end of the shell is a hollow head 8 having in addition to its outer walls a downwardly extending-cylindrical partition or wall 9, the lower edge .of which rests snugly against the upper t'ace of the tube sheet 3 and serves to divide the upper ends .of the tubes into two groups, one being the central cylindrical column of tubes open ing into thechamber l0 formed within the cylindrical wall 9 and the other being the annular group `of tubes surrounding the central tube column and opening at their upper ends into the annular space 11 immediately surrounding the cylindrical parti- Ition 9. An opening inthe upper face of the head 8 and directly above the cylindrical chamber -10 may serve as an inlet for one of the heat transferring liquids, say, the hot liquid, and the o ening 13 communicating with the annular chamber l1 may serve as inesatta the outlet for the same liquid after its passage through the shell. As the liquid enters through the inlet 1 2 it gathers within the chamber 10 and from thence nds its way'downwardly throu h the central'group of .tubes until it is ischarged; into the floating head 4. This head is in communiall lenfrth. Furthermore, the total pres.

sure dierence required to maintain a flowthrough the apparatus is no greater than' woul be required were the'same length of passage provided in a single pass type of apparatus. However, this additional length of fluid passage is obtained without increasing the length of the shell, the diameter and cross sectional area of the yshell being increased to accommodate the double passage. Such increase in diameter is not undesirable inasmuch as the working pressures in installations of this typeare normally -very low and no ditculty will be-encountered in casting a shell of suiicient` strength. p This is in contrast to the situation as presented when the length of the shell must beincreased, for in that case the length often exceeds that of tubing which may be commerciallyv obtained as well as exceeding convenient dimensions for installation.

The working fluid, for instance the coo]- ing liquid, enters the shell through -an inlet 14 into thel space surrounding t For the purpose of confining the circulation of this entering liquid toV the space surrounding the annular Agroup of tubes discharging into chamber v11,.a cylindrical core .tube 15 is provided to incase thel central grou of tubes and in effect divide the space within the shell into two chambers. The lower end of the core tube 15 stops short of the bottom of the apparatus, so th'at the cool` ing liquid admitted at the opening 14 may find its way down the length of the shell and from thence up inside the core tube 15 untiljt is discharged at the outlet opening 16. With thissituation a complete counter flow of the. two heat interchanging duids is accomplished vthroughout the entire length of the apparatus.

For the purpose of properl directly the flotw of the working u1d into eat transferrin relationy with the. tubes 2 the space rovided with baiiles 17 and 18. These yba es maybe ofr'generally e tubes 2. 4

- tube so that the liquid in helical conformation so that the cooling liquid will 'be directed during its passage 'through the shell across the length of the heat transferring tubes and will' be ybrought into re eated and intimate contact with them. he battles here shown are of the eneral type illustrated in the patent to yussell C. ones No. 1,335,506, vand-the bafde blades may be conveniently vformed by stamping them out of sheet metal and so cutting them. thatl the central portion of thesheet can be.used for the baliies-'IS inside the core tube l5 while the outer portion of the stamped sheet may be used to constitutethe baie 17 in the'annular space adjacent the walls of the shell. Near the upper end of the shell is a perforated annular disc 19 which litssnugly over tubes 2 and is of such dimensions as to fit snugly within the interior of the shell 1. The perforations in the disc 19 are so arranged as to block olf the space between the tubes constituting the f outer annular group, with the result that thev liquid entering the annular space through the inlet 14-will not be permitted to rise into that part of the shell above the disc 19. After descending to the bottom of the shell and again ascendingthe central core` tube 15 the liquidmay find its way through the central opening providediin the dlsc 19 so that itmay enter the space above the disc and be dischar ed at the outlet 16.

I havev shown a sligtlydiierent modilication in F ig. 3A in which the continuous helical baliie 1s provided only in the annular space surrounding the central core tube 15. Within the core tube I have provlded la, bame consisting of a plurality of elements each having a number of radial blades or vanes so that the liquid in passing through the space surrounding the tubes impin es upon co-adjacent blades or vanes and is t us kept in thorough agitation and is brought re eatedly into contact with the heat vtrans 4erring surfaces of the tubes.

This particular type of baille is disclosed in need not be employed, it being possible to utilize any desired system of battling which will direct the working fluid in such manner as to e'ect an eflicient heat interchange.

For instance, the'baile may consist of a series ofhorizontally positioned baiie ele-y ments lWhose. alternate blades extend out from opposite sides of the retaining shell or length of the' shell will ev directed in a circuitous path around the ends of the sucpassing along the cessive baille blades. Batlle blades of all descriptions may even be omitted underycertain conditions, if desired, and the liquid allowed to flow longitudinally along the tubes. Furthermore, the space surrounding the annular group of tubes may be equipped with a baffle similar to that shown within the core tube in Fig. 3, or the structure of Fig. 3 may be reversed so that the helical baille is Within the core tube and the horilzontally positioned baffle sheets are placed in the annular chamber surrounding the central core. In general, any appropriate system of ballles may be employed. The central core tube 15 may simply be a continuous sheet of metal, but for the purpose of removal I prefer to constitute it as shown in Fig. 4 of a longitudinally split cylinder having its free end 2() engaging in slots 21 provided in the baille sheets so that when it is desired to remove the central tube for cleaning or other purposes it may be fed out through the slots 21 in the baflles to the outside of the tube bundle. This operation is, of course, performed after the tube bundle is removed from its shell. y.

M inventiondoes not contemplate broadly t e provision of a heat interchange in which the heatinterchange fluids are passed twice along the length of the shell, nor is it strictly confined to the provisicnof any particular type of baille construction. The invention resides primarily in the particular construction illustrated and described, whereby the advantages of freedom from strains due to temperature changes, and the like, are obtained, yet in which fluid passages of great length relative to the length of the shell, as well as other advantages, are obtained. The scope of the invention is defined in the appended claims.

I claim:

1.Apparatus of the class described, comprising tubes for conveying one of the-heat interchange fluids, said 'tubes being divided into a centrally disposed group for conveying fluid in one direction and a surrounding group of annular conformation forconveying Huid in the opposite direction, a shell surrounding said tubes for containing thev other heat interchange fluid, a cylindrical core tube surrounding said centrally disposed group of tubes for dividing the space within the shell into two portions, said core tube consisting of a sheet of flexible material wound into substantially cylindrical form and adapted'to be unwound upon disassembling of the apparatus, and means disposed within said respective portions for bringing the fluid therein into intimate heat transferring relation lwith said tubes. A

2. Apparatus ofthe class described, comprising tubes for conveying one kof the heat interchange fluids, said tubes being divided into a centrally disposed group for conveyi interchanging uids, saldtubes bein lin a circuitous path across the tubes of one of said groups throughout the length of the shell and returning it similarly along the lother of said groups of tubes on its return `passage through the shell, saidl baffles being provided with slots thruy which said sheet of flexible material passes upon disassembling of the apparatus.

3. Apparatus of. the class described, comprising tubes for conveying one of the heat interchange fluids, said tubes being divided into a centrally disposed group for conveying fluid in one direction and a surrounding group of annular conformation for conveying fluid in the opposite direction, a shell surrounding said tubes for containing the other heat interchange fluid, a cylindrical core tube surrounding said centrally disposed group of tubes for dividing the space within the Shell into an inner cylindrical portion and an outer annular portion, and baffles disposed within said respective'portions for directing thefluid therein in a substantially continuous helical path across the tubes of oney of said groups, and then passing it similarly across the tubes of the other group, said baflles comprisinga plurality of independent cooperating units arranged one above the other in the shell, each of said baffle units in the outer annular portion of the space within the shell and the corresponding baffle unit arranged at the same height in the inner cylindrical portion of the space within the shell constituting a single disc of material of diameter equal to the inner diameter of the shell, said disc being cut to admit said central core tube and having portions deformed to constitute the bale units. y

4. Apparatus of the class described, comprising tubes for conve ingone of the heat divided into a centrally dis osed group or conveyin Huid in one irection and a surrounding grou of annular conformation for conveying uid in the op osite direction, a shell surrounding ,said tu es for containing the other heat interchange fluid, a transversely disposed disc adapted to fit around said tubes and block the spaces betweenthe tubes of said ,annular grou a cylindrical core tube surrounding sai centrally dielOl) posed group of tubes for dividing the space 'nieation with the spade within said cylinwithin the shell into two portions, an inlet drical core tube for receiving Huid issuing for admitting iuid to the portions surfrom said space.

rounding said annular group of tubes at In testimony whereof I ax my signa- 5 a point farther fromv the end of the shell ture.

than said disc, whereby the space above said disc constitutes a chambery in commu- CECIL WILLIAM SWARD

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