US2134058A - Heat exchanger - Google Patents

Description

Och K. B. ms 2,134,058

HEAT EXCHANGER Filed Jqne 16, 1956 M5 ATTORNEYS '55 mixtures. 1 Que to the Iar Patented- :Oct. 25, 1938 UNITED STAT-ES PATENT OFFiCE HEAT EXCHANG 4 Kenneth B. Bis, Garden City, N. Y., assignor to r The Griscom-Bussell Company, New York,

medium operating-pressure, and a very slow rate of flow.

It is among the principal objects of this invention to provide a heat-exchanger which 'will operate on a small pressure difierential and medium-to-low, operating pressure, with low velocity of flow-through of the medium to be cooled or condensed, yet which will condense or cool the vapors to be condensed very eiiiciently and completely. f

It is also an object of the invention to provide a condenser of this character, which will not only condense the condensible fluid to its'temperature- 01 condensation, but will also sub-cool the condensate so formed, in the one and-same flowthrough.- v

A further object of the invention is to provide, in a condenser for gaseous media having special cooling elements, means forpreventing the hot vapors tobe cooled from by-passing -thesewooling elements and which, instead, will cause, the vapors to come into close contact with the cooling elements to thereby increase the cooling rate I beyond that ordinarily achievable. I

A particular object of the invention is to provide, in a heat exchanger of this character, means,

for preventing the incoming cooling medium from absorbing heat from the outgoing, cooling fluid.

Another particular object of the invention is to provide, in a heat-exchanger for condensing the condensible components of a mixture of condensible vapors and non-.condensible gases, means for separating the condensate from the non-condensible gases; and for removing the non-condensil'ile gases without entraining any condensate in them.

, The heat-exchanger embodying these and other objects obviates floating heads, and hence the apparatus incorporates no joints between the .working fluid side and the other side; there is hence little likelihood of gas escaping, the device thus being rendered quite suitable ionhandling noxious, poisonous, or explosive gases or gas ends of all tubes bei l N. Y., a corporation of Delaware Application June l6, 1936, Serial No. 85,475

left free, there'is no tension or other strain put on any tube sheet or tube, either by temperature rises, or otherwise, By virtue of the construc-- tion of the tubes, etc., the number of holes it has hitherto been necessary to make in either tube 5 sheet for an apparatus of.- a given capacity, is

reduced considerably, usually by half, which is worthy of note in a fleld where usually it is deemed necessary to employ a remarkably great number of large-diameter tube holes and tubes. 10

Due to end-entrance of the slowly-moving, highvacuum vapors without having to flow as per usual practice, across at right angles to tubes, the power needed to operate the device is less than usual, yet fuller condensation is obtained. 15

The. other objects and advantages of the invention will be made manifest as this specification proceeds. k

The presently preferred embodiment of the invention is shown in the accompanying draw- 2o ing, but it is to be understood that the invention is limitedin its embodiments-only by the scope of the sub-joined claims. 'In thedrawing,

Fig. 1 is a vertical, substantially central section of the apparatus, a part being shown iragmen- 25 tarily; l

Fig. 2 is a cross-sectional detail of one of the elements thereof; Fig. 3 is a side elevation, on a different scale,

01' a modified form of this element; 39

Fig. 4 is a similar view of a further modified form thereof, and Fig. 5 is a detailed cross-section of another element of the apparatus. P

The apparatus illustrated in the accompany- 35 in g drawing, comprises .a verticallyarranged P such a nature as to present more effective transfer surface per linear foot than a much larger 50 bundle of tubes. To this end, each tube 3 is provided with a plurality of heat-conducting members, here shown as. longitudinally attached, radially extending, metallic ribs or flns, 4, and shown as being about twentyefour in number to.

'10 across the exchanger.

each tube 3, and as being such as to increase the surface area of each tube by about 500%.

The-upper end of. each tube -3 is preferably closed on, by means of a closure-member i, pref- 5 erably streamlined to the flow of the fluid supplied to the shell. The lower ends 01! the tubes 3 are left plain and are not finned, in order to.

provide a substantially unobstructed passage way. for the easy flow of gasand condensate These lower, plain ends of. the tubes'3 are expanded into, or otherwise secured to a tube-plate 8, suitably held between two annular flanges, 6' and t". formin part of the shell. a

1:, Plain tubes I of lesser diameter and greater length than tubes 3, are arranged concentrically within the 'tubes 3, and have both ends open. Their lower ends are attached in a tube-sheet 3, which is held between flanges 3' and 8" on 20 the shell. This arrangement 'deflnesand provides a-long, annular passage 9 in each heat exchangeelement, between the inner and the outer tubes. Any desired operating velocity may be provided by increasing or decreasing the size 25 of the annular passages, by increasing or decreasing the diameter of tubes 1 with respect to that of tubes 3.

A cooling-fluid inlet, 10, is provided on one side of the shell, in the upper one of the two 80 headers shown, and cooling fluid flows upwardly,

in parallel, through each of the annular passages 9, preferably at high velocity, and reaches the caps 5 and is thereby directed back down-1.

the so-called "napkin-ring" type, encircling the outside of. thefins and afiixed thereto but not to the bame. The baille has apertures therein 45 of sufilcient diameter to permit the ferrules to ,move easily therein, thus preventing abrasion thereof and of the fins. The entering gases are bythis structure prevented from by-passing the tubes and are instead forced to pass directly 50 along the tubes between the fins and also come into very close contact with the tubes. The baiiles also serve rigidly'to hold the tubes properly spaced from each other and from the shell.

- Other baflles, such "as shown at I! and I2", 55 and ferrules i3, are provided at suitable points .along the shell. It will be noted that the bailles l2, l2 and I! are located at a point remote from the inlet 2 and that they are arranged closer to each other than the distance between the first 60 baille' i2 and the upper ends of the tubes. As the vapor enters the shell lin a direction parallel 9 with the tubes it first encounters the upper ends of these tubes so that substantial condensation may occur as the vapor enters-the shell. The

quantity of uncondensed vapor thus es as the vapor pro resses through the shell and in order to insure efiicient heat transfer between the uncondensed vapor as it .approaches the lower "'end of the shell, and the tubes carrying 70 the cooling fiuid, the baiiles cause the uncondensed-vapor advancing from the upper end of the shell to come into intimate contact with the tubes and between the adjacent fins on the tubes. It is thus desirable to have the bailles V concentrated at a point remote from the inlet and from the upper ends of the. tubes, as illutrated in Fig. 1. 1

,Any condensate forming on the tubes 3 flows downwardly in the form of a thin film on the fins and on thesurface of the tube, in a direc- 5 tion opposite to that of the cooling fluid, so that as the condensate falls lower, it meets cooler and cooler regions of the tubes 3. Thereby not only is the condensible vapor quite eflectively condensed on the tubes 3 at its temperature of con- 10 densation, but it is reduced to a temperature belowits temperature of condensation by the time it reaches the lower ends of tubes 3, The gas is thus not only condensed, but,' in the one flow-through, the condensate is also sub-cooled.

A fluid outlet I4 is provided'near the lower end of the upper section of the shell, and through this outlet may be drawn off, if desired, both the condensate and .the non-condensible components of the gas mixture which entered at point 2 with the condensible components. Howe. ever, there is instead preferably-provided a cylindrical hood, or envelope-baiiie, II, of considerable length and of a diameter sufilclent to enclose one or more of the finned tubes 3. This hood is arranged above the condensate level and near the side of the shell. The hood has an opening it in its side near its top, and the shell has an-outlet I! connected thereto by a-length of pipe I8 which extends further outwardly to so connect with other apparatus. The non-con densible gases being thus directed back upwardly again over a very cool portion of the tubes 3, are thereby again cooled somewhat, and hence drop out any entrained condensate they may 35 have contained. Thereupon they pass out the outlet i1.

A circular-plate; member I9, havingapertures about the size of the outside diameter of the tubes I, is preferably provided in the upper of 40 the. two headers, as shown. It normally lies on the tube-plate I, or can be, if desired, releasably attached thereto. When the smaller tubes '6 are to be withdrawn for repair or replacement,

upon reassembling the exchanger they may be easily replaced in tube sheet I and properly arranged concentrically within tube 3, by means of this guide member. When there are a large number of tubes Ito be replaced, as when extensive corrosion thereof occurs, a quite appreciable saving'ln time-costs and operating expenses can be etfectuated by the use of this guide member. v

In Fig. 3 there is shown a form ofworkingelement according to the present invention, in which the externally-applied heat-conducting surface is made in the form of long helices 23, instead of as longitudinal ribbons, thereby in-' corporating in the heat-transferring elements the advantages due to giving more or less of a rotary, corkscrew motion to the gases. 1

7 At the bottom of the tubes the volume of the vapor to be cooled is decreasing and hence it is desirable that. the vapors given a greater amount of relative. motion. In Fig. 4 the fin II 55 is made to extend nearly longitudinally at the upper ends of the tubes. The relative angle of fin to the longitudinalaxis of the tube, is however,- increasedeto form a sharper helix as it approaches the bottom of the tube. 4 7

As shown most clearly in Fig. 5, it is pref able for the tubes I to have their exteriors, interiors, or both, suitably covered with a suitable heat-insulation material 22, such as an asbestos composition. This insulation may extend for any is desired length of the tube, and is sumcient to 1 minimize, or prevent, exchange of heat from the heated working-fluid outgoing in tubes I, to the cool working-fluid entering the header or tubes 3. The apparatus of Fig. 1 may be mounted, if

desired, upside down, retaining the construction lated as hereinbefore described. This arrange-.

ment is desirable when it is deemed advisable to employ gravity to remove the condensate, as when it is not deemed advisable to employ a pump or other suction device in outlet M to remove the condensate. In this event, outlet I i may be closed, as by a cap plate or the like, not shown.

For use in working on very viscous fluids, such as in heating viscous oils,-the apparatus is arranged horizontally, with outlet I l pointing upwardly. The fluid to be heated then enters from the left, through opening 2', and steam is -entrained through opening. and tubes 1. It is condensed in the annular spaces 9, and leaves the apparatus as water through opening I0.

I claim: 1

l. A heat exchanger comprising a tube sheet, a group of tubes having open ends secured to said tube sheet, a second group of tubes each of smaller diameter than the tubes of the first group whereby they may be inserted into the first" group .of tubes through the open ends thereof, means for rigidly supporting the second group of 'tubes in spaced relation to each other, said supporting means being disposed near one end of said second group of tubes and an aperture guide plate strung onto said second group of tubes and loosely engaging the same, said guide plate being mov 'able into 'close proximity into. the open ends of said first group of tubes with the apertures in the guide plate registering with these openings, to facilitate the insertion of said second group of tubes into the first group of tubes. 1

2. A heat' exchanger comprising a shell, a

bundle of concentrically arranged innerand outer tubes in said shell, heat conducting fins carried,

by the outer tubes and extending. generally lengthwise thereof, means for passing a fluid through said shell in contact with said finned tubes, and means for passing a second fluid through said tubes, the fins. extending parallel to said tubes throughout a portion thereof and ex-' tending around saidtubes throughout another portion thereof.

' KENNETH B. R18.

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