US2590465A - Heat exchanger - Google Patents

Description

, INVENTOR KENNETH B. R/S

K. B. Ris

HEAT EXCHANGER 111111111111 lnulmllllllrrl l im!! 151ml!!! nmrmmmummmn March 25, 1952 Filed Nov. 14, 1944 HIS ATTORNEYS I March 25, 1952 K B, Rls 2,590,465

' HEAT EXCHANGER Filed NOV. 14, 1944 2 SHEETSSHEET 2 x ENA/ETH 5.. F/S v 1% 'g' Hl's ATTORNEYS Patented Mar. 25, 1-95 UNITED STATES PATENT OFFICE 2,590,4654 HEAT IEXCHANGER lennethBfRis, Garden City, N; Y., assignor to TheGrrisconi Russell Company, New York, N. Y., a-corporation of Delaware, Appiieationnovemberm, 1944seria1fNo. 563,434

This invention relates to'heat exchange appa-` ratus, and, more particularly, toV heat exchangers for cooling powdered solid material with which is mixed a sufficient amount of gaseous material to cause the powdered material to flow like a iluid through the exchanger.

Certain types of catalysts are` employed in nely divided form and when used in-carrying out'certain chemical reactions become contaminatedV with carbon. Such catalysts may be reactivated by burning the carbon from4 the individual particles of the catalyst. This rmay be accomplished in a reactivating chamber whereinv provision is made for suitably. controllingI the,v `rate fr combustion. To this end the; powdered catalyst is recirculated between the re'activating chamber and a heat exchanger. Ordinarily vthe heat ex;- changer is located at' a lower' level than the. reactivating chamber, for example-on al lower Hoor of the building.

The powdered catalytic material ows by gravity from the reactivating chamber througha suitable conduit to approximately the level of; the bottom of the heat exchanger and may havea density oi approximately 25; pounds per cubic foot. At the lowest point 'of' its travel gaseousmaterial in the form of an; inert gas is introduced into the catalyst mass, lowering the densityjof the mixture to about `1.1 pounds' per cubic foot. In this condition the vi-lne'ly divided solidv andgas mixture is caused torrisethrough the heat exchanger and then returnv to the reactivati-ng chamber, the purpose of the heat exchange'ribeing to control thev average temperature existing in the reactivating chamber. The temperature of the mixture Yentering the inlet chamber at the bottom of theheat exchanger may be in the neighborhood of 1100 F. and its temperature as it leaves the outlet chamberat the top ofthe heat exchanger may be in' the neighborhood-fof 950 F.

The' object of the present invention is to provide a heat exchanger to meet these'requiree ments; A numberV of problems are involvedV on account of the comparatively high average temperature of operation, the temperature differences between diierent parts of' the apparatus, Vthe eroding effect of the iinely' divided solids and the necessity of maintaining reasonably uniform velocity of flow of the `nely dividedv 'solid and gas mixture throughout the Aheat exchangerin order to avoid such a low velocity that the solid material will not be carried along by the gaseousy material and in order. to avoid `such high, velocity as toproducc damaging'erosion.

4H claims. (o1. 257-2128) Another object 'of the'. invention is to provide a heat exchangerv for the purpose-described which can be. taken apart without diliculty or undue expensejin order to clean both sides, that is, both the passages for the fluid and the passages forthe-mixture of gaseous andiiinely divided solids.

The. invention will be yunderstood from a consideration of the accompanying drawings illustrating. oneY embodiment of the'invention by way of example. Inthese drawings:

Fig. l is a view of the heat exchanger invertical central section; i

Fig. 2 is a plan View of the heat exchanger with certain parts broken away to show the heat exchanger tube layout and with certain of the tubes and a portionv ofthe heat exchanger shell shown in horizontal; section; l

Fig. 3j is a view in vertical section drawn to an enlarged scale.. showing the details of a single heat exchange'. element, thefarrangernent for supporting-its' twoconcentric tubes and the arrangement for directing the gaseous mixture into the lower end of the element;

Fig.. 4, isa horizontal section taken on line 4-4 of Fig. 3;'

Fig. 5 is a bottom plan'view of a fragment of the lower tube. supporting and mixture 4directing plate;

Fig. Gis a; section taken on line @-6. of Fig. 5;

Fig. 7 is a, fragmentary bottom plan view of the lower'tubesupporting plate, showing a modification;

Fig. 8 isa section taken on line 8-.8 of Fig. 7; and

Fig. 9 is a section taken on line 9-9 of Fig. 7.

Referring now to the accompanying drawings, the heatexch'anger comprises a cylindrical shell I o'f any Suitablelength and diameter, but the length usually. being 'several times the diameter, making lan:clongated structure. At itslower end the cylindrical shell terminates'in a conical portion` Zwithin which is the inlet chamber 3 for the mixture o1"- gaseousfandnelyi divided solid materia-ls; Conical portion?` is provided at its lower end-with asuitable; inlet connection 4.

At its-upper'end' cylindrical shell l has a flange 5-by means of; which a tubeshefet' 5 and a conical hood '1 are securedfto it through the'v instrumentality of a series of bolts S. Withinfthe hood 'I is the mixtureV outlet chamber S whichextends from the topfcf the tube sheet Vi'to the outlet connection lll `at the top.` The interior walls of inlet 'chamber 3yandl of cylindrical shelll are line/dv with a substantialthicknes's of insulation l I'.

The heat exchanger mechanism, which may for" lconvenience be referred to as the tube bundle I2, consists of a plurality of shell tubes I3 for conveying the mixture of gaseous and nely divided solid materials, and within which is mounted a tube I4 for the fluid, in this case a cooling iiuid, tube I4 being of considerably smaller diameter than shell tube I3 and preferably provided with external longitudinal ns I5. One such element I3, I4 of the tube bundle I2 is illustrated in Fig.

3. The cooling iiuid passes through the interior of tube I4 and the mixture of gaseous and nely divided solid materials passes upwardly between the fins I5 through the annular space bounded by the outside surface of tube I4 and the interior walls of shell tube I3.

The shell tubes I3 are tted at their upper ends into apertures in tube sheet 6. The heat exchange elements I3, I4 extend downward from tube sheet 6 to the inlet chamber 3 where the shell tubes I3 are held in suitably spaced relation by means of a floating plate I6, the lower ends of tubes I3 being received in perforations in plate I5. Floating plate I6 also serves as a partition for directing the mixture into shell tubes I5. It is suspended from tube sheet 6 by means of rods II having substantially the same coe'icient of expansion as the heat exchange elements and having holding nuts I8 threaded on their upper and lower ends. A thin perforated plate I9 may be placed intermediate tube sheet 6 and floating plate I6 for the purpose of providing lateral support for the heat exchange elements. This plate I9 is also supported on rods I'I and the position of the plate as well as the spacing of tube sheet B and plate I6 is maintained by means of sleeves surrounding rod I'I.

Perforated plate I9 and floating plate I6 are maintained in centered relation to cylindrical shell I of the apparatus by means of vertical guide strips 2| and 22 (Fig. 1). There are four of these guide strips 2I cooperating with the periphery of plate I9 at points 90 apart, as may be seen in Fig. 2. Guide strips 22 are similarly arranged to coact with the periphery of iioating plate I6. Guide strips 2| and 22Aextend radially inward from the interior of shell I slightly more than the thickness of insulation I I. They loosely engage the edges of plates I9 and I6; hence the tube bundle I2 may be easily inserted and removed from shell I for cleaning purposes. Insulation II may, if desired, be provided with an interior metal sheathing to assist in holding the insulation in place and to prevent damage thereto through the insertion or removal of tube bundle I2.

The heat exchange elements I3, I4 are so arranged, as shown in plan view, Fig. 2, as to cause the tube bundle I2 to substantially ll the central space within the exchanger. Such spaces as are left between the outside tubes and the surface of insulation II and between the various shell tubes constitute dead spaces, that is to say, there is no circulation other than that which may be produced thermally. Such spaces become filled with the mixture of inert gas and finely divided solids, which Works its way upward around the periphery of floating plate I6 and performs an insulating action supplementing that of insulation II.

The mixture of gaseous and pulverized solid materials is directed from inlet chamber 3 into the open lower ends of shell tubes I3 by means of guiding or deecting elements formed on the lower surface of the iioating plate I6 (see Figs. 3, 5 and 6). These elements are formed by intersectng 1in-like formations 23 and 24 at right angles to one another and projecting downwardly from the lower surface of floating plate I6 between the perforations for shell tubes I3. Fin-like formations 23 and 24 intersect one another at equally spaced points 25 between pairs of diagonally related tubes I3.

Between such intersecting points both sets of iins 23'and 24 are preferably scalloped along their lower edges, as shown at 26 in Figs. 3 and 6. Fins 23 and 24 are thicker at their bases adjacent the surface of plate I6 than at thenlower edges, and substantially fill the spaces between adjacent perforations for tubes I3 so as to be substantially tangential with the surfaces of the tubes (see Figs. 3 and 5). The walls of ns 23 and 24 at each intersection 25 are nlleted to form curved surfaces 21 (Fig. 5) sloping outwardly and upwardly from the lowest point of the intersections 25 towards the outer periphery of the edges of shell tubes I3. Thus at each point of intersection 25 with these curved sloping surfaces 2'I there is formed a deiiecting element for directing the mixture towards the mouths of the shell tubes. In this way the mouth of each shell tube is surrounded by what amounts to an inverted funnel, square in outline along the lower edges of ns 23 and 24 and gradually becoming round, in proximity to the lower edges of shell tubes I3.

Such an arrangement offers little opportunity for erosion by the particles of solid catalyst material carried along by the inert gas. The single stream moving upwardly through inlet chamber 3 is divided into small sections when it meets the lower sharpened edges of the fins 23 and 24 and the gently sloping surfaces of these fins and of the deflecting elements just described direct the mixture into the shell tubes with a minlmum of erosion.

As mentioned above, there is within each shell tube I3 a coolant tube I4 having radial longitudinal fins I5. Thus the tube bundle I2 includes a group of these tubes I4 for the coolant which is of the same arrangement and number as the shell tubes I3. This group of coolant tubes I4 is divided into sections, in this instance 4, as shown in Fig. 2, and the coolant, usually reduced crude petroleum at high temperature and also usually at high pressure, may be delivered to the heat exchanger through an inlet pipe 28 which is connected by flange connections 29 to each of the four inlet tubes 30, 3|, 32 and 33. The coolant is thus divided into four streams, each flowing through an equal number of tubes I4 in series. The outlet tubes at each of these sections are shown at 30', 3I', 32 and 33 and are connected to expansion bends, two of which are shown at 36 and 3'I. These are connected by outlet connections 38 and 39 'to outlet pipe 40.

Both the outlet connections such as 38 and 39 and the inlet pipes 3l--33, inclusive, are led out of and into the heat exchanger, respectively, through the conical hood 1. In this way the usual stationary head for the tube side of a unit is eliminated and there are a minimum of parts in the path of the upwardly flowing catalyst and gas mixture. The inlet pipes and the outlet connections extend in the same general direction as the motion of the stream of mixture from the upper ends of shell tubes I3 to the outlet connection I0. In order to provide tight joints for the inlet tubes 30-3I and the outlet connections such as indicated by 38 and 39, sleeves 4I are welded into suitable apertures cut .through the hood 1 and the upper ends of each of these sleeves is restricted to fom au conical seat 42e.. Coacting withthis seat is a member 43 which is brazed or welded to the exterior surface ofthe outlet connection such'as 38, and has an upper conical surace which is held in engagement with the seat 42` by means of( a nut 44 threaded onto the outlet connection above the enel` ofsleeve 4 I.

The tubes I4 for the coolant uid system adjacentr heatI exchange elements lf3, I4 are made.

jecting beyond the tops of these shell rtubes. They y are then connected in series withr neighboring hairpin tubes of the same section by means of return bends 46 and couplings '41. The arrangement of the successive connections between the coolant fluid tubes of the various heat exchange elements I3, I4 is shown in Fig. 2. All of the U- shaped or hairpin tubes vhave equal length legs except those which include inlet tubes 33, 3 I, 32 and 33, wherein the legs constituting these fourinlet tubes extend through the hood 1in order to conneet with the inlet pipe 2S. Theopposite legsv of thesefour tubes, therefore, are shorter, inasmuch as they extend only to the couplings 41 of certain ofthe return bends 46.

The arrangement for supporting the coolant tubes I4 will now be described. Welded to the outside surface of each of tubes I4 a short distance below couplings 41 is a collar 48 (Fig. 3) preferably hexagonal in shape, to receive a wrench to prevent the tube from turning when couplings 41 are applied or removed. Collar 48 rests upon a pair of flat metal strips or bars 49. These strips are thus spaced apart slightly more than the diameter of tubes I4 and a pair of such strips extends along each row of tubes as laid out in Fig. 2. across the top of tube sheet 16. Strips 49 are maintain-ed in edgewise upright position by means of pins 5U which are threaded into the upper surface of tube sheet I6 on both sides of both strips between each two apertures rfor the shell tubes I3 as illustrated in Fig. 2. Strips 49 are fastened at their ends by means of small bolts 5| to upright clips 52 which may be welded to the upper surface of tube sheet l (see Figs. 2 and l).

By means of this construction, the tube bundle I2 can be removed from the heat exchanger I and completely taken apart for cleaning. This procedure, furthermore, is not particularly diflcult or expensive. It involves disconnection of the iianged couplings for fthe inlet fluid pipes -33, inclusive, and the corresponding outlet pipes on the other side of hood 1 and the removal of hood 1 by taking out bolts 8 which also hold tube sheet 6 in position. Then the tube bundle I2 can be lifted out bodily. Aftemthis each heat exchange element I3, I4 can be disassembled by removing couplings 41 and return bolts 46, then unfastening the ends of the edgewise placed supporting strips 49 from the clips 52 and sliding them laterally between the rows of pins 50. rIhereup'cn each o-f the tube bars I4 or hairpin tubes, can be removed from the floating plate end of the tube bundle.

With the heat exchanger of the present invention, the path of travel of the mixture of gaseous and finely divided materials is nearly straight from the entrance chamber 3 to the exit chamber 9.-; The, velocity Qi the mixture. the inlet and exit `char11-,ber preferably somewhat more than seven feet-pes second, which insures that a stream of gas willV carry the powdered catalyst along with it.v However, the impingement of the solidparticles against objects directly in its path neces-v sarily tends to produce erosion. Accordingly, the return" bends 4,5, for each pair of tubes I4 at the bottornyare provided with metallic hoods orprotesting boots 5,3. Also tubes I4 between supporting shoulders 48 and couplings 41 are preferably provided-withprotecting sleeves 54. Also anelon-f gated tubular hood of oval section 55 is placed oveneach of the temperature. expansion bends; 36 and,

Referringnow to Figs. 7., 8 and 9, there ishere shown amodieation of the means for deilectir'igI or directing a mixture of .gaseous and nely `divided solid materials into the lower ends offshell tubes I3. This is a cempositionstructure instead oft being formed integrally with tube sheet I6 as are, the devices previously described in connection wit-h Figs. 3, 5 and 6. Tube sheet I6a (Fig. 8)r which is' perforated as before to receive. the shell tubes I'3a within which are the coolant tubes I4a, has secured to its lower surface a plurality of deecting elements 55. These.` are mounted, one centrally between each set of four o f the shell' tubes I3 which will be understood from Fig. '1. They are held in place by means` of bolts 56 which are threaded at both ends andl have their opposite ends screwed into taped holes inveloatingrplate ld. Nuts 51 are threaded on the lower ends of bolts 56 and hold elements 55 in place. These nuts are preferably streamlined, as

shown in Figs. 8 and 9, in order to sharpen the apexes of elements 55.

By means of the present invention, there has been provided a heat exchanger for the purpose specified through which the mixture of powdered catalyst and inert gas will flow readily without clogging, and which, because of the arrangement for direct straight line ow through the exchanger, prevents the various parts thereof from being eroded by impact of the solid particles.

Moreover, the heat exchanger can be readily taken apart for cleaning both sides of the unit, that is to say, both the passages through which the mixture flows, and also the tubular passages through which the coolant flows. This is'of considerable importance where a material such aS reduced crude petroleum is used as the coolant.

It will be understood that the preferred einbodiment of the invention has been illustrated by way of example but that changes may be made in the arrangement and construction and withq out departing from the spirit of the invention, the scope of which is set forth in the appended claims,

I claim:

1. In a heat exchanger for transferring heat between a fluid and a mixture of gaseous and nely divided solid materials. a shell supported in upright position having an inlet chamber for the mixture at the bottom and an outlet chamber therefor at the top, a tube sheet adjacent said outlet chamber, a plurality of upright mixture conveying tubes having their'upper ends secured in said tube sheet and descending to said inlet chamber, tubes for conveying said fluid disposed one within each of said mixture conveying tubes leaving a now space for said mixture between the walls of said two tubes, a partition in said inlet chamber having perforations coacting with the lower ends of the mixture conveying tubes to maintain them in spaced relation, and deflecting elements on said mixture directing partition for directing the said mixture into said tubes.

2. In a heat exchanger for transferring heat between a fluid and a mixture of gaseous and finely divided solid materials, a shell supported in upright position having an inlet chamber for the mixture at the bottom and an outlet chamber therefor at the top, a tube sheet adjacent said outlet chamber, a plurality of upright mixture conveying tubes having their upper ends secured in said tube sheet and extending between said outlet and inlet chambers, tubes for conveying said fluid disposed one within each of said mixture conveying tubes, and means on said tube sheet for individually suspending said fluid conveying tubes to provide passages for said mixture from said mixture conveying tubes into said outlet chamber.

3. In a heat exchanger for transferring heat between a fluid and a mixture of gaseous and finely divided solid materials, a shell supported in upright position having an inlet chamber for the mixture at the bottom and an outlet chamber therefor at the top, a plurality of upright mixture conveying tubes arranged to receive said mixture at the inlet chamber and discharge the same into the outlet chamber, a tube sheet adjacent the outlet chamber, said tube sheet having rows of perforations therein into each of which the upper end of a mixture conveying tube is secured, tubes for conveying said fluid disposed one within each of said mixture conveying tubes, and

means for supporting said iiuid conveying tubes comprising a pair of thin metal bars disposed on the upper side of said tube sheet in parallel relation and on the opposite sides of the iiuid conveying tubes in each row, said fluid conveying tubes extending above the tops of said bars and each having a collar secured thereto and resting on the upper edges of said bars, thereby providing free access to said outlet chamber for the said mixture entering the outlet chamber from the upper ends of said mixture conveying tubes.

4. A heat exchanger as claimed in claim 1 in which the deflecting elements are formed individually and separately from the mixture directing partition and bolted thereto.

KENNETH B. RIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 307,480 Luttgens NOV. 4, 1884 445,536 Broekman Feb. 3, 1891 856,141 Griesser June 4, 1907 1,779,538 Grady Oct. 28, 1930 1,806,176 Owens May 19, 1931 1,884,778 Lucke et a1. Oct. 25, 1932 2,001,663 Carlson May 14, 1935 2,101,782 Kuhner Dec. 7, 1937 2,250,864 Gordon July 29, 1941 2,409,780 Mekler Oct. 22, 1946

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