US2279552A - Heat exchange apparatus - Google Patents

Description

April 14, 1942 R. A. BowMAN l 2,279,552

HEAT EXCHANGE APPARATUS Filed NOV. 22, 1940 f mtl; es. 'uml' I l Fflcnl. 34

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wn'NEssEs: Ww RM Mbw' ATTORNEY Patented` Apr. 14, 1942 HEAT EXCHANGE APPARATUS Robert A. Bowman, Folcroft,'Pa., assigner to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 22, 1940, Serial No. 366,584

1 Claim.

This invention relates to heat exchange apparatus, more particularly to heat exchangers containing a desuperheating section, and has for an object the provision of improved apparatus of this character.

Another object of the invention is the provision of heat exchange apparatus having a desuperheating section comprised by a, plurality of vertically-extending inverted U-tubes, together with means between the legs of the U-tubes for separating the space surrounding said tubes into a desuperheating irst section and a condensing second section, the length of said U-tubes being selected so as to assure that the line between desuperheating and condensing occurs in 'the second condensing pass past the bend in the U- tubes.

Yet another object of the invention is the provision of heat exchange apparatus having a desuperheating section and including a plurality of inverted U-tubes with a group of the tubes of lesser length than the remaining tubes and a portion of the shorter tubes constituting a desuperheating section.

These and other objects are effected by the invention as will be apparent from the following description an-d claim taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a vertical sectional view taken along the line I-I of Fig. 3 looking in the direction of the arrows and showing apparatus constructed in accordance with the present invention;

Fig. 2 is a view similar to Fig. 1 but taken along the line II-II of'Fig. 3 looking in the direction of the arrows; and

Fig. 3 is a transverse sectional view taken along the line III-III of Fig. 1 looking in the direction of the arrows.

Referring to the drawing more in detail, there is shown heat exchange apparatus of the vertical type comprising a shell 9 having an exhaust steam inlet connection I0 and housing a plurality of longitudinally-extending, inverted U-tubes having their terminal portions extending through and supported by the tube plate I2. Preferably, this tube plate is a portion of the waterbox structure I3, which is provided with a water inlet I4 and a water outlet I5, which, together with the 5 therein, provide for circulapartitions I6 and I 'I tion of water through the tubes in a plurality of passes, in this case four passes. The waterbox may be provided with openings I8 in alignment with the terminal portions of the tubes Il,

-pass B. The lower end heating rst steam the openings being closed byvconventional means such as the covers I9, held in place by the bolts 20 and bolting rings 2I. The vupper end of the shell is closed in anysuitable manner, as by the cover 23 welded thereto, as at 24.

A baille 26 extends longitudinally of the shell from wall to wall thereof and separates algroup 21 of the tubes II from the remaining tubes, at 28. Preferably, the baiiie 26 is sealed with respect to the shell at its vertical edges by 'suitable means, such as the Lamiflex seals 2 9, described in United States Patent Nos. 1,803,034 and 1,803,- 035.

. A similar but shorter baille 3| extends vertically between the legs of the U-tubes of the separated group 21 and divides the space within the shell surrounding this group into a desuperheating first steam pass A and a condensing second steam of the desuperheating pass A is in communication with the steam inlet I0, while the second steam pass B has at its lower end an opening 32 through the baille 26 whereby steam enteringl the apparatus through the inlet IIJ passes upwardly through the desuperpass, over the top of the baiiie 3 I, downwardly along the second steam pass B and through the opening 32 into the' inal conl densing steam pass Condensate collecting in the steam passages B and C leaves the apparatus through the condensate outlet 34, while air and non-condensable gases are led ol from the top of the shell through the air oitake 35, pos" "ioned above the nal steam pass C. Preferably, the bale 3l separating. rst and second steam passes, A and B, respectively, is provided with suitable sealing means betweenits vertical edges and the shell, such as the Lamiex seals 36.

'I'he tubes of the separated group 21 are shorter than those of the remaining group 28 to insure that desuperheating will occur throughout the length of the rst steam pass A with the transition point from'desuperheating to condensing occurring past the bends in the tubes of the group 21 considered in the ldirection of steam flow, whereby it is assured vthat no condensate will collect on any portion of the tubes where it could flow down onto the desuperheating surface. g

Inasmuch as this transition point between desuperheating and condensing may vary in location with changes in operating conditions, it may be desirable that the tubes be of such length thatthe transition point, under normal' of this group operating conditions, will occur about midway of the second steam pass B. This provides, in effect, a factor ofsafety, whereby upon change in operating conditions there is still suitable length of condensing surface available in the second pass to take care of shifting of the transition point. relative to the high point in the bend of the Utubes.

In order to prevent steam which may pass over the top of the longitudinally-extending baille 26 from condensing at the other side thereof and the condensate collecting upon the tubes of the desuperheating section, there is provided a transversely-extending baille 3B over-- lying the tubes of the first two steam passes and sealed with respect to the shell, as at 39. An opening 40 is provided through the baille 26 just above the transverse baille 38 to provide for -iiow of condensate collecting uponl the latter to aired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claim.

What is claimed is:

Heat exchange apparatus comprising a vertically-disposed shell, a plurality of inverted U-tubes extending vertically in said shell, waterbcx structure associated with the terminal portions of said tubes and providing for circulation of water therethrough in a plurality of passes, a first vertical baille separating a group of the U-tubes from the remainder thereof, a second vertical baille disposed betwen the legs of the U-tubes of said separated group and dividing the space surrounding the latter within the shell into ilrst and second steam passes, said shell having a steam inlet to the lower end of the i'lrst steam pass and a condensateoutlet from the lower end of the last steam pass, and the U-tubes of said separated group being shorter than the remaining tubes and of such length that the transition point from 'desuperheating to condensing occurs in the second .steam pass beyond the bend in the tubes considered in the direction ofsteam flow.. A

ROBERT A. BowMAN.'

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