US2365878A - Heat exchanger - Google Patents

Description

Dect 26, L. Cl HET EXCHANGER Filed April 20, 1942 2 Sheets-Sheet 1 ATTORNE-V L.. C. HUFF HEAT EXCHANGER Filed April 20. 1942 Dec. 26, 1944.

2 Sheets-Sheet 2 R O T N E V N LYMAN C. HUFF ATTORNEY Patented Dec. 26, 1944 UNITED STATES v l HEAT EXCHANGER Lyman C. Huff, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware Application VApril 20,

3 Claims.

` This invention relates tc an improved form of heat exchanger of the type employing a plurality of U-tubes enclosed within a shell for establishing indirect contact and heat exchange between a convective fluid flowing through said tubes vand ahflid circulating about the tubes Within said s e invention is advantageous as applied to a wide variety of uses, it is particularly Well adapted for use where the convective uid enters at relatively high temperatures and the fluid tobe heated ismaintained at a relatively high pressure, such, as, for example, in a waste heat boiler employing as .the convective fluid, hot regenerating gases from the catalyst regenerator of a hydrocarbon conversion process, such as catalytic cracking or catalytic dehydrogenation.

In processes for the catalytic cracking of hydrocarbon oils, a deleterious deposit comprising carbonaceous cr hydrocarbonaceousmaterials accumulates upon the catalyst particles and must be removed to render thecatalyst suitable for further Vuse in the process.

deleterious material is usually accomplished by passing heated air or hot flue gases containing regulated quantities of oxygen in contact with the catalyst to burn the combustible contaminants from the catalyst, thus liberating large quantities of heat which are carried from the regenerating zone in the outgoing stream of regenerating gas. 'I'he temperature of this outgoing gas stream is usually quite high and substantial quantities of useful heat can and should be recovered' therefrom for economical operation of the process. Various waste heat boilers have heretofore been proposed for this purpose.

y One of the main difficulties encountered in de' signing waste heat boilers, suitable for the class 'of service above mentioned, is the tendency, with ordinary design, for le'akageto occur where the heatexchanger tubes are attached to the tube sheet. This leakage is the result of unequal expansion and contraction in different portions of the apparatus due to wide temperature diier ences in the stream of heating duid entering and leaving the apparatus as well as in` the stream of heat absorbing fluid. The tube sheet or sheets in a conventional waste heat boiler'for this class of service must be quite thick in order to withstand the high pressures maintained inthe shell and, when exposed to diiferenttemperatures on its opposite sides, expansion stresses result which cause the tube sheet to warp or bow and distort thev tube ports so that leakage occurs therethrough Although the heat exchanger provided by the This removal of c 1942, Serial No. 489,758 (Cl. 257-239,)

around the tubes. 'I'his is one of the major causes of shut-down and aside from being troublesome and dangerous, necessitates frequent and costly repairs. 4 5 The present invention provides a heat exchanger embodying advantageous and novel features which obviate this diillculty.

As applied to a heat exchanger employing U-tubes, the invention utilizes a plurality of relatively smalltube sheets mounted on the shell or head of the exchanger, instead of one large tube sheet. The reduced area of the smaller ltube sheets permits lighter construction (i. e., thinner sheets) in which more uniform temperatures prevail on opposite sides of the tube sheet, thus greatly reducing the likelihood of distortion. Also, by using separate inlet and outlet tube sheets the temperature of cach is more uniform throughout its area as compared with a single tube sheet carrying the tubes at both their inlet and outlet ends.

Another feature of the invention resides in the substantially V-shaped arrangement of the tube bank. This provides a substantially uniform disof the shell to provide more uniform heating of the fluid which flows through the shell about the tubes.

'Ihe features and advantages of the present in- 30 erence to the accompanying diagrammatic drawings and following description thereof.

Figure 1 is an elevational view, showing principally in section, of one form of the apparatus provided by the invention. y

Figure 2V is an end view of the same apparatus.

Figure 3 is an elevational view, shown prin-v cipally in section of a modied form of apparatus employing the features of the invention.

Figure 4 is an end view of the heat exchanger illustrated in Figure 3. y Referring to Figuresll and 2 the main body of the apparatus comprises, .in this particular in-` tribution of heating surface across the diameter n vention will be more yclearly understood with refan integral head 2 and at the opposite end by a- .for conducting steam produced in the boiler to any desired apparatus in which its contained heat is to be utilized. Attached to the inside of the ilanged opening 9 is a T-shaped conduit I0 closed at its opposite ends and provided with a plurality of small openings II through the upper portion of its wall. The purpose of this T-shaped conduit, generally called a dry pipe,y

steam from carrying with it any substantial quantity of water. In operation the water level |.2 within the vessel will always be maintained below theT-shaped Amember I0. To make this I 'water level more readily maintainable, the level indicator .2I is provided on the shell I'. Any condensate formed in the steam conduit I3 attached to the nozzle 9 is returned to member Ill and will either be revaporizedfthereln or will ilow f through the drain holes I4 provided in the lower portionof the member III.

is to prevent priming, i, e. prevent the outgoing.

vThe yremovable head 3 is provided with two.

relatively small tube sheets I6 and a relatively large tube sheet I all integral with and spaced from the head 3 by short hollow cylindrical members I8 and I'I-respectively. These tube sheets are faced and drilled to receive suitable flanged f conduits, not shown, for ydirecting the convective fluid to and from the vessel. In the particular vessel herein illustrated although one large tube sheet I5 and two smaller tube sheets I6 are provided, it is within th'scope of the invention to employ a greater number when desired;

Heating tubes -I9.in the form of al U are each secured at one end to the tube sheet I5 and at smaller tube sheets I 6, thus providing a .plurality of streams. for the llow of a convective uid their opposite ends to one or the other of the tube sheet I5 on one side of the vertical center line through the latter are connected lat their opposite end to one [of the tube sheets-.I6 and l the tubes on the opposite side of this'vertical center line are-connected at their opposite ends t@ the othertbe sheet le. 'rhsthe tube meer or bank is in the form of a V so that the heating,

surface of tubes I9 is well distributed-across the shell -of the vessel transverse toits longitudinal To support tubes I9 within the shell structural members ,20 .and stay plates 20 are providedand secured to the lower portion-tof .the shell If by welding or other suitable manner.

'I'-heow.cf. convective viiuid maybe directed into the-tubes attached-tothe single. largerfbube sheet] 5 andout .of the tubes at ther smaller tuhef sheets I6 orthe flow may. be reversed, depend' ing upon'the heatingmedlum used and .the Amost mally secured together with bolts not shown.

The stationary head 23 is provided with a flanged removable head is provided the flanged nozzle 29 and connectingconduit 30 lfor introducing fluid to be heated into the vessel or for removing heated iluid from the vessel.

In the upper portion of shell'22 adjacent thel stationary head a similar. flanged nozzle 3| is provided and connected with conduit 32 which serves as an inlet conduit for iluid 'to be heated when conduit 3B and nozzle 29 are employed as outlet connections for the heated fluid, and -vice versa. i l

Tube supporting baiiles 33 and 34 secured to the shell and extending into the vessel from opposite Sides o'f the shell are disposed at longitudinally spaced points within the shell and direct the flow of the fluid to be heated across the bank oitubes 35 and back from top to bottom of the vessel between its ends. Baiiies 36 extending from adjacent the rremovable head to adjacent the bends of the tubes occupy a position between the parallel portions of the U-shaped tube bundles. ,l The various bailles cooperate tov form a path lfor the iluid to be heated in a con- 7^to the larger tube sheet 38 and at its opposite end to one or the other of the smaller tube sheets 31 thus providing two bundles of tubes arranged transversely across the vessel in the form oi a V, as in thecase illustrated in Figures 1v and 2 Iclaim as my invention:- 1 .i

1. A waste heat boiler comprising an elongated 'shell provided with end closure means one of which is,detachab1y, secured to said.shell,"two small ltube sheets and one larger' tube. sheet` spaced from the main body portion of 'and in. tegral with lsaid detachably secured closure means, a plurality of U-bent tubes extending ln-l gitudinally within said shell ifrom said detachably secured .closure meansto adjacent the opposite end, all ofjsaid tubes being attached at one en'd to said larger tube sheet and a' portion of them being attached at the other to one or said small tube sheets and the remainder to the other of said small tube sheets, means for dl.l

convenient. way of connecting the .boilenherein A illustrated to other equipment.- v

- Referring now tofFig'ures 3. and 4 the .main i body of this modied .form of the invention.cinn-A prise's a cylindrical shell. 22 .closed at one end by .an integral 'head 23 and at theopposite end@ bya :removable head 24. The shell 22 and-'theremovable head'24 areprovided with companion l441s is`-25and2trespectivelrwhich are-ncris s. shell.

recting convectiveiluid into and out oi said tubes,

means for :introducing liquid into said shell'ami means for direct-.ingo generated -vapors out of said 2.The apparatus defln -in claim l` lIllither characterized in that saidy small tube sheets are disposed equi-distant above, sald.- larger ltube y 3. TheI apparatus dened .in claim 1 further characterized in thatan. equal number of, tube ends are attached to each of said small sheets;l

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