US2467741A - Heat exchange apparatus - Google Patents

Description

April 19, 1949. c. F. HANCOCK HEAT EXCHANGE APPARATUS 2 Sheets-Sheet 1 Filed sept. so, 1947 ilu ATTORNEY c. F. HANcocK VHEAT EXCHANGE APPARATUS April 19, 1949.

Filed sept. s'o, 1947 2 Sheets-Sheet 2 INVENI'OR CHESTER Ha/vcocn WITNSSES:

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ATTORNEY Patented Apr. 19, 1949 HEAT EXCHANGE APPARATUS vChester F. Hancock, Primos, Pa., asslgnor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 30, 1947, Serial No. 776,900

The invention relates to heat exchangers of the hairpin tube type and it has for an object to increase the tube surface accommodated in a given shell by providing groups of longer and shorter tubes with the space between the tube portions of the longer tubes partially occupied by the tube portions of the shorter tubes and with the tube bends of the latter extending transversely relative to those of the longer tubes.

In heat exchangers, it is customary to arrange the tube passes so that fluid flows through the tubes from the bottom to the top of the shell, where the latter is horizontal; and from side to side of the shell, where the latter is vertical. If tubes of the hairpin type are used, this arrangement of successive passes limits the number of tubes that can be installed in a given shell because of contour of the latter and the wide central lane occurring because the minimum radius of tube bending must be several times the tube dialneter. To make more effective use of the shell with hairpin tubes, the first and second tube passes are arranged so that the tubes go from one side to the opposite side of the shell, thereby taking full advantage of the shell contour, and

the central space between such passes is partially occupied by shorter hairpin tubes having their tube bends arranged transversely or at right angles to the bends of the rst tubes and arranged to dene third and fourth tube passes and which also go from one side to the opposite side of the shell. This arrangement is particularly useful for a horizontal shell where the first pass tube portions are at the bottom and are used to subcool condensate resulting from condensation of vapors by the other passes.

A further objectof the invention is to provide a horizontal heater wherein a group of longerI hairpin tubes provide a rst pass along the bottomof the shell and a second pass along the top of the shell and a group of shorter hairpin tubes provide third and fourth passes along the sides of the shell, this arrangement of tube portions providing for first pass tube portions spaced below the other tube portions to afford room for change in level of condensate submerging tube portions of the first pass and being cooled by media passing therethrough.

The foregoing and other objects are effected by the invention as will be apparent from the fol.-

2 Claims. (Cl. 257-32) lowing description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a longitudinal sectional view of a/ heat 'exchanger incorporating the present imp/rovel ment;

Fig. 2 is a sectional view takenlalong the line II-II of Fig. 1;

Fig. 3 is a. sectional view taken along the line III- HI of Fig. 1; and y Fig. 4 is a sectional view taken along the line IV-IV of Fig. 1 and looking in the direction of the arrows. I

Referring to the drawings more in detail, there is shown a cylindrical shell 8 having a spherical wall 9 closing one end and having its other end Ill open. The open end of the shellis closed by a box construction Il having a tube plate I2. The tube plate I2 carries a n/est of hairpin tubes,- at I4. The box construction is compartmented by partitions or walls I5 s'o that fluid entering the inlet I6 flows through the tubes to the out-V let I1. The shell has an inlet I8 and an outlet I9 providing for flow of medium therethrough and about the tubes.

In order that the shell may accommodate the maximum number of hairpin tubes, the latter are divided into two groups comprising a longer group of hairpin tubes, at 2U, and a shorter group of hairpin tubes, at 2l, the group of longerhairpin tubes being nested and arranged to define a space a between the first and second pass tube portions 22 and 23 thereof andlthe group of shorter hairpin tubes being arranged to occupy partially such space, with the bends of the latter tubes extending transversely of, or at right angles to, the bends of the tubes of the longer group. The

tubes of each group vary in length and radius of bend to provide for the tubes of both groups conforming to the cylindrical contour of the shell, to provide for the tubes of the longer group conforming to the spherical contour of the closed end of the shell, and to provide for increase in nest depth inwardly from the sides of each group so tube portions 22 and the second pass tube portions 23 of the longer group of tubes to the compartment 25. As the compartment 25 places the second pass tube portions 23 in communication with the third pass tube portions 26 of the tubes of the shorter group, fluid flows from such compartment through the third pass tube portions 26 and the fourth pass tube portions 21 of the tubes of the shorter group to the outlet compartment 28 and the outlet I1.

As shown, the heater is horizontal and arranged for subcooling of condensate. To this end, the first pass provided by tube portions of the longer group extends along the bottom of the shell and the second pass provided by the tubes of such group extends along the top thereof, and the third and fourth passes provided by the tubes of the shorter group extend along the sides of the shell, the bends of the tubes of the longer and shorter groups being arranged at right angles so that the tubes of the shorter group may be located in the space between the rst and second pass tube portions, whereby submerged tube portions of the first pass may be spaced below the remaining tube portions to provide a space or lane b for change in level of submerging liquid. As shown in Figs. 1, 3 and 4, submergence of tube portions of the first pass is assured by having the condensate outlet I9 opening into the shell interior above the lowermost point thereof.

Preferably, the shell interior is divided by a horizontal baille 3l into a lower subcooling space 32 and an upper condensing space 33. Vertical baiiies 34 in the condensing space constrain condensible heating medium entering the inlet I8 to flow to and fro across tubes of the nest, as indicated in Fig. 4. Condensate collecting on top of the horizontal baille 3| runs off the tube bend ends thereof and enters the lower subcooling space 32. The subcooling space has ballies 35 which constrain condensate to flow to and fro across the tube portions therein before leaving through the outlet I9. Wherever necessary, clearance spaces between tube portions of the passes and between the shell and tube portions are blocked by baliies4 36 to insure iiow across tubes ofthe nest without by-passing.

As shown, tube portions 22 of the first pass are arranged to provide a group 38 below the horizontal baille and in the subcooling space and a group 39 spaced a suitable distance above the baille and in the condensing space, the spacing of the baule and of the tube portions of the group 38 below the remaining tube portions assuring of adequate room above the baille for change in level of condensate in the shell and submerging the tube portions below the baille.

From the foregoing it will be apparent that the invention improves generally hairpin tube heat exchange apparatus in that the arrangement of tubes provides for increased surface in relation to shell size and for the tubes conforming to the shell contour. In particular, the invention improves subcooling horizontal heaters, as the subcooling section provided by the rst pass tube portions of the longer group of tubes at the bottom of the shell assures, not only of high thermal efliciency, but of the temperature of the condensate leaving the heater being depressed suiliciently to avoid flashing of the condensate into steam unless the pressure is very substantially reduced. In addition, this arrangement of tubes has the latter disposed and bailied so as to secure the most effective condensing and cooling actions.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible .of various changes and modifications without departing from the spirit thereof.

What is claimed is:

1. In heat exchange apparatus, a shell having one end open and the other end closed; a box closing the open end of the shell and including a tube plate; hairpin tubes carried by the tube plate; said tubes including iirst'and second pass tube portions joined by vertical bends and including third and fourth pass tube portions joined by horizontal bends so that the latter tube portions may be located vertically in space between the first and second pass tube portions; said box including an inlet and outlet connections and means for causing liquid medium entering the inlet connection to flow in series through the first, second, third and fourth pass tube portions to the outlet connection; said shell including an inlet for condensible medium located at the upper portion thereof adjacent to said box and an outlet for condensate located at the lower portion thereof adjacent to said box; said first pass tube portions including a first group extending along the bottom of the shell and a second group spaced thereabove and arranged below the third and fourth pass tube portions; a horizontal baille dividing the shell interior into upper condensing and lower cooling spaces which communicate at the closed end of the shell; said tube portions of the first pass being located in the cooling space and such tube portions and thehorizontal baille being spaced below the remaining tube portions of the passes; vertical bailies in the condensing space and arranged to constrain medium entering the inlet and flowing toward the closed end of the shell to pass to and fro across the tube portions therein; vertical batlies in the cooling space and constraining condensate flowing therealong from the closed end of the shell to the outlet to pass to and fro across the tube portions therein; and means providing for discharge of condensate through the shell outlet so as to maintain submergence of tube portions below the horizontal baille.

2. In heat exchange apparatus, a shell having one end open and the other end closed; a box closing the open end of the shell and including a tube plate; hairpin tubes carried by the tube plate; said tubes including first and second pass tube portions joined by vertical bends and including third and fourth pass tube portions joined by horizontal bends so that the latter tube portions may be located vertically in space between the first and second pass tube portions; said box including an inlet and outlet connections and means for causing liquid medium entering the inlet connection to flow in series through the first, second, third and fourth pass tube portions to the outlet connection; said shell including an inlet for condensible medium located at the upper portion thereof adjacent to said box and an outlet for condensate located at the lower portion thereof adjacent to said box; said first pass tube portions including a first group ex- .tending along the bottom of the shell and a second group spaced thereabove and arranged below the third and fourth pass tube portions; a horizontal baille dividing the shellinterior into upper condensing and lower cooling spaces which communicate at the closed end of the shell; said horizontal baille being arranged between said rst and second groups of tube portions of the rst passvand spaced beiow the second group thereof; vertical bailles in the condensing space and arranged to constrain medium entering the linlet and flowing toward the closed end of the shell to pass to and fro across the tube portions therein; vertical bailies inthe cooling space and constraining condensate therealong from the closed end of the shell to the outlet to pass to and froacross the tube portions therein; and means providing for discharge of condensate through the shell outlet so as to maintain submergence of the tube portionsbelow the hori-A zontal baille.

CHESTER F. HANCOCK.

- 6 REFERENCES crrnn The following references are of record in the ille of this patent:

UNITED STATES PATENTS

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