US2274247A - Heat exchanger - Google Patents

Description

l Feb. 24; 1942. Kf B. Ris

. HEAT EXCHANGER Filed Aug. 2, 1958 4 Sheets-Sheet l Filed Aug. 2, 1958' 4 Sheets-Sheet 2 fw ATTORNEYS Feb. 24, 1942.

K. B. RIS

HEAT EXCHANGER Filed Aug. 2, 1938 4 Sheets-Sheet 4 INVENTOR /fennc '5. /17/5 ATTORNEYS Patented Feb. 24, 1942 ICE 2,274,247 HEAT EXCHANGER Kenneth B. Ris, Garden City, N. Y., assignor to The Griscom-Russell Company, New York, N. Y., a corporation of Delaware 'Application August 2, 193s, serial No. 222,538

1 Claim.

This invention relates to heat exchangers and more particularly to heat exchangers suitable for use as evaporators in regions where the water contains scale forming impurities. An object of the invention is`to providea heat exchanger of such a. nature that the desired-heat transfer is obtained at maximum eciency during all operating conditions. This object may be obtained to a considerable extent by providing within the heat exchanger a preheating zone orchamber and a main heating zone or chamber communicating therewith, the arrangement being such that portions of the main heating unit are never cooled to an abnormal extent by surges of. cold water or other liquid supplied to the heat exchanger. I prefer to employ a preheating chamber and a preheating unit thereinvforV I heating the water before it comes in contact with i any portion of the main heating unit.

`In regions Where the water. contains large quantities of scale forming impurities the efciency ofv an ordinary'heat exchanger is soon impaired by the deposits forming on the tubes of the heating unit. My invention contemplates la construction such that the scale is automatically cracked of the tubes by lateral distortion thereof occurring uponchangesin the vvtemperav ture of the tubes. VFor this purpose I 'prefer to a employ a flexible tube bundle for carrying the heating medium and to provide tie rods, or the like, for holding the ends of the tube bundle in substantially iixed relation to each other. Whenever there is any appreciable increase in'the temperature of the tubes they have a tendency lchamber and the other vin the main heating chamber. Where such units are employed, the tube bundles are preferably mounted, at one end,

tol; 257-240) in the form of a vertical dam or Weir which dividesk the shell into two heating zones the arrangement being such that the water, or other liquid to be heated, first enters a preheating zone and then flows over the top of the partition into thepmain heating zone. I may also construct or arrange the partition in such a way 'that restrictedpassage of the fluid to be heated is provided at points below the top of thepartition so that at these points the preheated fluid may flow into the main heating chamber.` This p feature is of particular value when the apparatus is being operated at low capacity at which time some if not all of the `fluid being heated may pass from the preheating chamber into the main heating chamber at one or more points below the top of the vertical partition or Weir.

With the` tube' bundles mounted in Va lsingle tube sheet at one end as mentioned above thev heating units may be removed from the shell as a single unit for ready inspection and repair. The headers at one end of the tube bundles may be mounted on or between guide rails or tracks carried by the shell. These tracks facilitate the insertion of the heating units and also their removal from the shell. Suitable end connections areprovided for the tube bundles for causing multipassf'fiow` `of the heating medium through the tube bundles and the connections may be arranged s o as to provide any desired combination of series or series-parallel flow. Also, if desired; one heating medium maybe suppliedto the preheating unit, and another heating me-y dium, or a heating medium from a separate source of supply, may be supplied to the main heating unit.

vFor commercial installations Where it is -desirable to use hot tar, or other heavy liquid containing carbon or other substances which have nature that they insure approximately. streamin a single tube sheet which may form a closure for one end of the heat exchanger shell, andfat the other end, the tube bundles may be supported in separate headers. The shell may be provided with a longitudinally extending partition sepa- -rating the preheating chamber from the main line flow of the heating medium throughout the heating element. When hot tar is used as a heating medium in a heat exchanger there is a tendency for deposits of coke to form at points where there is an abrupt change in velocity ordirection of flow and inf order to minimize this tendency I may employ curved end connections which avoid abrupt changes in velocity as the heating medium is discharged from one tube or bank of tubes and returned to another tube or v tube bank. Also I prefer in such installations to heating chamber. This partition is preferably employ individual U-shaped end connections,

' constitutes a dam or weir.

separately detachable so as to provide ready access to any tubes which have become clogged or fouled, without the necessity foropening all of the tube passages.

The various objects and advantages of. my invention will be more apparent upon considering the following detailed description of certain embodiments thereof illustrated in the accompanying drawings in which Fig. 1 is a horizontal longitudinal section view of a heat exchanger embodying the invention, this view being taken on line I-I of Figs. 3 and 4;

Fig. 2 is a longitudinal vertical section view of the heat exchanger taken on line 2-2 of Figs. 3 and 4;

Fig. 3 is a front elevation of the heat exchanger;-

Fig. 4 is a transverse section view taken on line 4--4 of Fig. 2;

Fig. 5 is a longitudinal horizontal section view of another embodiment of my invention taken on line 5-5 of Figs. 7 and 8;

Fig. 6 is a longitudinal vertical section view taken on line 6-6 of Figs. '7 and 8;

Fig. 7 is a front elevationl of the heat exchanger illustrated in Figs. 5 and 6 and Fig. 8 is a transverse section View taken on line 8-'8 of Fig. 6.

Referring to the embodiment of the invention illustrated in Figs. 1-4 inclusive it will be noted that it comprises a cylindrical shell I having a closed rear end 2 and a combination cover and tube sheet 3 at the front end of the shell. The heat exchanger shell is intended to be mounted in a horizontal position on suitable supports 4. Within the shell there is a longitudinally extending vertical partition 5 fixed to the shell in any suitable manner and serving to divide the space within the shell into two zones or chambers, a preheating chamber A and a main heating chamber B. These chambers communicate with each other over the top of the partition 5 which thus A suitable inlet connection 6 is provided for supplying water, or other liquid, to the preheating chamber A and a vapor discharge connectiony 1 is provided at the top of the shell.

A heating unit is provided in each of the chambers within the shell for heating the water, or other liquid, supplied to the shell. The heating unit in the preheating chamber A comprises a vertical bank of tubes 8 constituting a exible 4 tube bundle having its front end mounted in the tube sheet 3 and its rear end mounted in a suitable header 9. A manifold .Ill having an inlet II and an-outlet I2 is mounted on the outer vface of the tube sheet or shell cover 3, in any suitable manner as by a series of bolts I3. This manifold may contain a series of partitions I4 for directing the steam or other heating medium through the heatingA tubes, as illustrated by the arrows inthe manifold. The heatingunit in the main heating chamber B may likewise consist of a plurali'ty of tubes I5 constituting a flexible tube bundle with its front end mounted in the tube sheet 3 and its rear end mounted in a header I6 containing internal partitions Il for directing The tubes of each heating unit are preferably made of thin walled copper nickel alloy tubing, and the tube bundles of exible tubing are preferably, although not necessarily, initially bowed in a direction away from theA partition 5. The headers 9 and I6 may be held in iixed relation to the tube sheet 3 by a number of tie rods I8 connecting the header 9 to the tube sheet 3 and another series of tie rods IS connecting the header I5 to the tube sheet 3. As illustrated in Fig. 2 the front ends of the tie rods may be screw threaded and mounted in threaded bores or openings provided in the tube sheet, as shown at 20. The rear ends of the tie rods may be secured to the headers 9 and I6 in any suitable manner as by means of nuts 2l threaded onto the ends of the tie rods. These tie rod connections may be adjusted so as to hold the tube bundles in position with the tubes initially bowed outward from the partition 5, as best illustrated in Fig. 1. The tubes of each tube bundle may be supported at intermediate points by suitable cages such as those shown at 22 and 23 in the main heating chamber and at 24 and 25 in the preheating chamber. These cages may consist of a vertical series of horizontal bars passing 4between adjacent horizontal rows of tubes, with the ends of the bars welded or otherwise connected to vertical bars, as illustrated at 26 and 21 in Fig. 1. These cages confine the flexible tubes so that any lateral distortion of the tubes the flow of iluid from one group of tubes to anmust occur in horizontal planes parallel with the cross bars of the cages.

The cages 22 and 23 may be welded or otherwise secured to angle members I9 (see Fig. 4)

and in like manner the cages 24 and 25 may be secured to angle members I8. The angle members I8 and I9' embrace the tie rods extending between the tube sheet 3 and the headers 9 and I6.

With the ends of the tube bundles tied together by means of the tie rods I8 and I9, or the like, it will be understood that any substantial increase in the temperature of the tubes will cause the tubes to bow laterally rather than elongate and this 1atera1 distortion of the tubes is effective in cracking on scale deposits forming on the tubes during the operation of the heat exchanger. This is of great importance Where the apparatus is employed as an evaporator and the water supplied to the evaporator contains scale-forming impurities. 'Ihe tie rods which are preferably made of steel, or the like, are not in direct contact with the heating medium and in. any event they do not tend to expand as much as the flexible tubes and, accordingly, whenever there is an abnormal increase in the temperature of the tubes the tubes are distorted laterally to such. an extent that they crack oi any s'cale deposited on the tubes.

For removing accumulated scale in the bottom of the shell a number of blow down connections may be provided, such as those illustrated at 28 and 2g in the bottom of the main heating chamber B and at 28' and 29' in the bottom of the preheating chamber B, and, if desired, the front cover 3 may be provided with openings near the bottom thereof, as shown at 30 and 30', and a suitable detachable cover 3l, for facilitating the removal of loose scale from the chamber B and A respectively.

During normal operation of the apparatus the liquid to be heated is supplied to the preheating chamber A thru the inlet 5 and this preheating chamber may be provided with one or more transytube bundles.

verse names 32 andes for directing the nquid into contact with the tubes 8y /of the preheating unit. After being preheated in ,this manner liquid may flow over the top of the partition 5 into the main heating chamber where it comes into direct contact with the main heating unit. I prefer to employ a partition 5 so associated with the shell that restricted flow of the fluid being heated is permitted at a plurality of points below the top of the partition so thatat these points the preheated iluid may pass directly into the main heating chamber. Such passages for supplying the preheated fluid into the main heating chamber may be provided at any desired points in or around the partition 5, for example, the rear .end of thel partition may be spaced from the closed end 2 of the shell so as to provide a restricted iiuid passage, vas best illustrated at 3 in Fig. 2. i

With both tube bundles mounted at one end in a single tube sheet 3 and at the other end in separate headers 9 and l,6,the tube bundles and tube sheet may be removed from the shell as A plurality of guide rails or tracks in each of the compartments or chambers.` For example, I

lll

have shown a pair of horizontally spaced guide rails 36 in the main heating chambeigas best illustrated in Fig. 4, and another pair of vertically spaced tracks 31 in the preheating chamber.

These tracks 36 and 31 engage the headers and thus support the tube bundles and hold them in proper position in the shell. lThe several ltracks may be mountedon suitable brackets 38, 39, 46 and 4I, as best illustrated in Fig. 4.

nections for the tube bundles which will minimize the tendency of the hot tar to cok at the points where the heating medium is supplied to and discharged from the several tube passes. Such a construction is illustrated in Figs. 5 to 8 inclusive. Upon referring to these flgures it will be noted that the apparatus there illustrated is substantially the same as that illustrated in Figs.

1 to 4 inclusive except for the tube bundle end connections and, accordingly, where applicable the same reference characters have been applied and the-above description may be regarded as a description of this modicationof the appa.

ratus except` for the end connections for the Referring to Figs. 5 to 8 inclusive the manifold 42 mounted on the ,face vor the tube sheet s is 6 provided with an inlet 43 and an outlet 4,4 for the hot tar or similar heating medium. The several connecting 'chambers 45 in the manifold have smooth curved Walls for conducting the heating medium to and from the several banks being such as to provide approximately streamline flow of the heating medium from one set of tubes to the. adjacent group of tubes.

The rear end of the preheater tube bundle is mounted in a tube sheet 46 having. tapered openings for receiving the taperedends of U-shaped connections 41 one such connection being provided for'each adjacent pair of tubes, as best illustrated in Fig. 5. 'Ihe internal bore of each of these connections 41 is substantially the same diameter as that of the tubes communicating therewith and thus the U-shaped end connections 41 provide streamline ow for the heating medium at the rear end of the heat exchanger. Each ofthe U-shaped end connections 41 is held in place by means of suitable brackets 48 and bolts 49 which secure the end connections to the tube sheet 46.

In like manner the tubes I5 of the main (heating unit may be mounted in a tube sheet 50 having tapered bores for receiving the tapered ends of U-shaped end connections 5I. These end connections may be like the end connections 41 of the preheating' unit and in like manner they may be held in place by suitable brackets 52 and bolts 53 secured to the tube sheet 50. The individual detachable end connections 41 and 5I and the .manifold 42 with its curved passages substantially increase the eciency of the apparatus when hot tar, or `the like, is used as a heating medium for they prevent the abrupt changes in direction or velocity of flow of the heating medium which ordinarily results in the formation of deposits of carbon or coke. .The use of separately detachable end connections makes it possible to inspect and clean some of the tubes without opening up all of the tube passages.

It is to be understood that the embodiments of my invention described in detail herein are merely illustrative of heat exchangers employing my improvements and that the invention is not confined to such embodiments but includes all modifications thereof falling Within the scope l of the appended claim.

I claim: v

A heat exchanger comprising a horizontal shell, a vertical partition in said shell providing therein a'heating chamber and a preheating chamber communicating therewith over the top of said partition, separate tube bundles in said chambers and means for holding the opposite ends of said tube bundles in substantially fixed relation to each other, whereby changes in tube temperature cause lateral distortion of the tubes, said partition being spaced from the shellat points below the top ofthe partition and extending to the bottom vthereof to provide restricted flow of uid from one chamber to "the, other at these points.

KENNETH B. RIS.

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