US1960770A - Heat exchanger - Google Patents

Description

5. BROWN HEAT EXCHANGER Filed May 21. 1952 2 Sheets-Sheet l 24 Hiii LESS FfliilESiiilL ll 22/ lNVENTOR J BY ATTORNEYS 5'. BROWN HEAT EXCHANGER May 29, 1934.

Filed May '21. 1952 2 Sheets-Sheet 2 INVENTOR ATTORN EYS Patented May 29, 1934 UNITED STATES HEAT EXGHANGER Stanley Brown, Garden City, N. Y., assignor to The Griscom Russell Company, New York, N. Y., a corporation of Delaware Application'May 21, 1932, Serial No. claim 20 Claims.

This invention relates to heaters and particularly to feed water heaters of both the shell and tube type and the contact type.

In the contact type of feed water heater the steam used as a heating medium is brought into direct contact with the feed water and in the common shell and tube type of feed. water heater the steam is brought into heat exchanging relation with the water through a heat transferring surface. Ordinarily exhaust steam is used for the purpose of heating the feed water.

My invention relates particularly to a method and apparatus for utilizing superheated steam,

although it is to be understood that my improved apparatus can be used in a system employing steam at or near the saturation temperature. According to'my invention superheated steam can be used in an efficient manner to heat feed water to the end that the water may be brought to a relatively high temperature before being supplied to the boiler. By utilizing my invention it is possible to raise the temperature of the water to a value in'excess of that of the saturated temperature of the steam employed in heating the water. In general, the principal object of my invention is accomplished by continuously passing superheated steam and 'water in heat exchanging relation in such a manner that the water is first heated by steam at or near its saturated temperature and subsequently heated by the superheated steamat the maximum temperature of this heating medium. My invention contemplates the use of a heat transfer surface for transferring heat from the superheated steam to the water and after this has been accomplished the steam may be brought into direct contact with water at a lower temperature, or it mayotherwise be brought into heat exchanging relation with the water.

In general, my improved apparatus comprises ashell equipped with means for supplying water thereto and with means for supplying superheated steam to the shell. I prefer to employ means within the shell for first confining superheated steam in heat exchanging relation with a portion of the water in the shell and for subsequently bringing the steaminto heat exchanging relation with the remaining portion of the water in the shell. For example, the shell may be provided with two heating zones for the water, in the first of which the raw water is brought into contact with steam which has previously delivered its superheat to water in the second heating zone. In this first heating zone the steam mayor may not be in direct contact with thewater, whereas, in the second heating zone the superheated steam is preferably out of direct contact with the water but in eflicient heat transferring relation with the water through metal surfaces, such as the walls of metal tubes through which the water may be port of the heater.

I may employ a cylindrical baflle enveloping a group of tubes within the shell and adapted to confine the superheated steam in contact "with passed to the discharge the tubes within the baflle. This baifle is preferably spaced from the wall of the shell to thereby preventthe superheated steam from coming in .direct contact with the shell wall. This arrangement prevents excessive heating of the shell and the warping or buckling of the shell which might occur if the superheated steam were brought into direct contact therewith.

The various objects and advantages of my invention will be more apparent upon considering the following detailed description which is to be taken in conjunction with the accompanying drawings of which:

Figure 1 is a verticalsectional view of a feed water heater embodying my invention.

Figure 2 is a transverse sectional view taken on line 2-2 of Figure 1.

Figure 3 is a transverse sectional view taken on line 3-3 of Figure 1.

Figure 4 is a vertical sectional view partly in diagrammatic form, of another embodiment of my invention as applied to a feed water heater of the contact type, and

Figure 5 is a transverse sectional view taken on line 5-5 of Figure 4.

The embodiment of my invention illustrated in Figures 1 to 3 inclusive comprises a cylindrical shell 1, having a cap 2, closing one end thereof, and a header 3 closing the other end of the shell. The header 3 comprises a tube sheet 4 and a cover plate 5 secured thereto by any suitable meanssuch as the bolts -6. A plurality of tubes '7 are expanded into or otherwise secured to the tube sheet 4. The tube sheet 4 and the cover plate 5 are formed so as to provide a plurality of chambers 8, 9 and 10. A floating .head 11 is provided within the shell 1 and comprises a tube sheet 12 and a cover plate 13 secured to the tube sheet by bolts 14. The tube sheet 12 and the cover plate 13 are formed so as to provide chambers 15 and 16, communicating with separate groups of the tubes 7.

The chamber 8 is in direct communication with several of the tubes '1 within the shell 1, and this chamber also communicates with an intake port 1'7. In like manner the chamber 10 communicates with a discharge port 18.

. The arrangement of thesevera'l parts referred to above, is such that water may enter the chamber 8 through the intake port 1'7 and pass through a group of the tubes 7 into the chamber 15 in the floating head 11. The water then passes back through an adjacent group of tubes into thechamber 9 which serves to direct the water into. a third group oftubes communicating with the the battle chamber.

chamber 16 in the floating head 11.' From the chamber 16 the water flows through a fourth group of tubes to the chamber 10 from which it is discharged through the port 18. The tubes '7 are thus arranged to provide a four-pass flow of the water, or in other words, the water in passing through the apparatus traverses the length of the tube bundle four times before it reaches the discharge port 18. It is to be understood, however, that any desired number of passes may be employed. The water in passing through the tubes '7 within the shell 1 may be heated by means of a hot medium brought into heat exchanging relation with the tubes. I prefer to employ super-heated steam for this purpose and to first v confine the super-heated steam in heat exchanging relation with a group of the tubes near the discharge port, to the end that the water in the tubes may be brought to a temperature close to that of the superheated steam entering the apparatus.

In the apparatus shown in Figures 1 to 3 inclusive, the shell 1 is provided with a gland 19 adapted to receive super-heated steam and discharge the same into a chamber within the shell 1, formed by a baflie 20 arranged in such a manner that it envelopes a group of the tubes '7 within the shell. In the construction illustrated in Figures 1 to 3 inclusive, the baflle 20 encloses one half of the tubes and these tubes are in relatively close proximity to the discharge port 18 and the chamber 10 in direct communication therewith. The baiiie 20 engages the tube sheet 4 but terminates short of the tube sheet 12, and accordingly the chamber formed by the baffle is adapted to discharge steam from within this chamber into heat-exchanging relation with the tubes '7 located outside of the bafile chamber. If desired, a plurality of transverse baffies 21 maybe provided within the baflie chamber to cause the superheated steam flowing through this chamber to follow'a circuitouspath before it is discharged into the space within the shell 1 not occupied by Other transverse baffles 22 may be provided for the purpose of directing the steam into eflicient heat-exchanging relation with the tubes located outside" of the baflie chamber.

i The cap 2 closing one end of the shell 1 is provided with a discharge port 23 for removing condensate from the apparatus, and a discharge port 24 is provided in the shell 1 for removing uncondensed vapor from within the shell. It will be understood that the super-heated steam enter- 5.

ing the apparatus through the gland 19 heats the water flowing toward the chamber 16 and toward the chamber 10, to a temperature near that of the super-heated steam entering the apparatus, and that thereafter the steam is brought into heat-exchanging relation with the tubes communicating with the chambers 8 and 15, and which carry water at a much lower temperature. That portion of the steam which condenses within the apparatus is discharged through the drain .port 23 and the uncondensed vapor passes ofl through the port 24. .It will be ,noted that the baflie 20 which forms a baffle chamber containing a group of the tubes 7, is spaced apart from the wall of .the shell 1 and this serves to confine the superheated steam entering the apparatus, in a region remote from the shell wall, thus preventing excessive heating of the heat-exchanger shell.

Atthe same time the battle forms a passage of restricted cross section which brings about a high velocity 0! the superheated steam and greatly haproves the efficiency of the heat transfer. The steam is brought into contact with the heat-exchanger shell only after it is discharged from the baflie chamber, and this does not take place until the temperature of the steam has been lowered considerably by contact with the tubes within the bafiie chamber.

The apparatus shown in Figs. 1 to 3 inclusive, is of the shell and tube type wherein the water being heated is at all times out of direct contact with the heating medium.

In Figs. 4 and 5, I have illustrated an embodiment of my invention as applied to a feed water heater of the contact type, wherein the steam employed as a heating medium is brought into direct contact with the water being heated, at one stage of the operation. The apparatus of Figs. 4 and 5 comprises a cylindrical shell 25 hav ing a cap 26 closing the lower end thereof and a cap 27 closing the upper end-of the shell. The apparatus of Figs. 4 and 5 issimilar to that shown in Figs. 1 to 3 inclusive, to the extent that it includes a baffle 28 within the shell and forming a baffle chamber enclosing -a plurality of tubes 29. The enveloping baffle 28 is spaced apart from the shell wall and is supported by the cap 27 by means of a fluid connection 30 having an intake port 31 and a discharge port32. A tube sheet 33 is located near the upper end of the baffle 28 and supports the tubes 29. The tubes 29 may be regarded as consisting of two groups one of which communicates with the chamber 34, and the other of which communicates with the chamber 35. I The chamber 34 communicates with the intake port 31 and the chamber 35 is in direct communication with the discharge port 32. The floating head 36 is provided with a tube sheet 37 and with a chamber 38 communicating with the lower ends of the tubes which are mounted in the tube sheet 37. The arrangement is 'such that water entering the port 31 flows first into the chamber 34, then through a group of the tubes 29 into the chamber 38 in the floating head 36', then through the remaining group of tubes to the chamber 35 a and to the discharge port 32.

The shell 25 is provided with a water inlet 39 and with a drain connection 40. In diagrammatic form I have illustrated a pipe connection 41 connecting the drain port 40 with the inlet 31, and a pump 42 is provided for pumping water from the lower end of the shell 25 to the intake port 31 which communicates with thetubes 29 within the baflie chamber. v

Super-heated steam may be admitted to the apparatus through a pipe connection 43 which communicates directly with the interior ofthe bafl'le chamber. The super-heated steam is thus brought into heat-exchanging relation with the water flowing through'the pipes 29 whereby the temperature of the water is brought to a value near that of the entering steam. The steam is then discharged from the lower end of the baflle water and is removed from the lower endof the shell by the pump 42. The water passing through the Shell 1 is thus heated by steam at the saturation temperature and is then supplied to the tubes 29 by means of the pump 42 where the water is brought into heat-exchanging relation with the super-heated steam entering the apparatus. In order to facilitate the transfer of heat from the super-heated steam to the water in the pipes 29, these pipes are preferably provided with longitudinal fins 46. Fins of this character increase the effective surface of the heat exchanger tubes without materially interfering with the free passage of the steam through the bafile chamber. The desired distribution of the super-heated steam within the baflle chamber is obtained by eliminating the longitudinal fins from the upper extremities of the tubes 29 in the vicinity .oi' the superheated steam connection 43, as best illustrated ,in Figure 4. This provides ample space in the upper end of the bafiie chamber for transverse flow of the steam whereby the steam is brought into intimate contact with all of the tubes in the bafile chamber.

Regardless of whether my inventionis applied to a feed water heater of the contact type or to apparatus of the shell and tube type, it is of particular value because of the possibility of heating the water to a temperature above the saturation temperature of the steam, and this is accomplishedwithout bringing super-heated steam into direct contact with the shell. In this way the full advantage of using super-heated steam can be realized without heating any portion of the shell to an abnormally high temperature.

It is to be understood that my invention is not limited to the particular embodiments illustrated and described in detail, but includes such modifications thereof as fall within the scope of the appended claims. For example, the invention may be applied to single pass exchangersas well as to heat exchangers of the multipass type, certain forms of which are illustrated in the accom panying drawings. In single pass apparatus the internal enveloping baffle, or the, like, may be employed for the purpose of keeping the heating medium initially out of contact with the shell while providing'high yelocity of flow in heat exchanging relation with a portion of the fluid to be heated.

1. Appara us of the type described comprising a shell, me 5 for supplying a fluid to said shell, means for supplying a heating medium to said shell to heat the said fluid, and means within the shell for first confining said heating medium out of contact with the shell-wall and in heat exchanging relation with a portion of said fluid and then discharging the heating medium into changing relation with the remaining portion of the said fluid. V 3

3. Apparatus of the type described comprising a shell, means for supplying a fiuid to said shell, means for supplying a heating medium to said shell to heat the said fluid, and means within said shell for first confining said heating medium in from within the same into direct contact heat exchanging relation with a portion of said fluid and then discharging the heating medium into direct contact with the remaining portion of the said fluid.

4. Apparatus of the type described comprising a shell, means for supplying. a fluid to said shell, means for supplying a heating medium to said shell'to heat the said fluid, and means within the shell and spaced from the wallthereof for first confining said heating medium in heat exchanging relation with a portion of said fluid and then discharging the heating medium into direct contact withthe remaining portion of the said fluid.

5. Apparatus of the type described comprising a shell containing two heating zones arranged so that fluid to be heated may be passed through the zones in series, means for supplying a fluid to one of said zones and for discharging the same from the second zone, and means for supplying a heating medium, first to said second zone and then to the other zone into direct contact with said fluida 6. Apparatus of the type described comprising a shell containing at least two heating zones arranged so that fluid to be heated may bepassed through the zones in series, means for supplying a fluid to one of said zones and for discharging the same 7 from the second zone, and means for supplying'a heating medium, first to said second zone and then to the other zone, said zones being arranged so that the heating medium is out of contact with the shell wallwhile in said second zone and in contact with the shell wall while in the first zone.

7. Apparatus of the type described compris'ng a shell, a plurality of tubes within said shell, a battle e'nveloping'at least a portion of said tubes,

.means for supplying a fluid to said shell and for .causing the fluid to flow through the tubes withfle into heat exchanging relation with the flui enter'ng said shell.

8.'Apparatus 01' the type described comprising a'shell, a plurality of tubes within said shell,

a bailie enveloping at least a portion of said tubes, means for supplying a fluid to said shell and for causing the fluid to flow through the tubes within said baflle, and means for supplying a heating medium. .to the interior of said bailie to heat the fluid in the tubes therein, the said baflle'being arranged to discharge the heating medium from within the same into heat exchang'ng relawall.

9. Apparatus of the type described compristion'with the fluid entering said shell and the said baflle being out of contact with the shell ing a shell, a plurality of tubes w.thin said shell. a baflle enveloping at least a portion of said tubes means for supplying a fluid to said shell-and for ing medium to the interior of sa d baflle to heat the fluid in-the tubes therein, the said bafile being arranged to discharge the heating medium with the fluid entering said shell. 1

10. Apparatus of the type described comprising a shell, a plurality of tubes within said shell,

means for supplying fluid "to said tubes and fordischarging the fluid therefrom, headers arranged to produce multi-pass flow of the fluid through said tubes, a baflie separating the tubes of the final pass from the tubes of the initial pass'and disposed out of contact with the shell, and means for bringing a heating medium into heat exchanging relation, first with the tubes of the final pass and subsequently with thetubes of the initial pass.

11. Apparatus of the type described comprising a shell, a fluid inlet port, a group of tubes within said shell communicating with said inlet port, a fluid discharge port, a second group of tubes within said shell communicating with the first group of tubes and with the fluid discharge port, a baflle separating the said groups of tubes, and means for bringing a heating medium into heat exchanging relation with said second group of tubes, the said bafile being arranged to confine the heating medium in heat exchanging relation wlth said second group of tubes and out of contact with the shell wall and to then discharge the said heating medium into heat exculating the same through the tubes within said shell, and means within the shell for first confining the heating medium supplied thereto in heat exchanging relation with said tubes and then discharging the heating medium into direct contact with the fluid in said shell.

13. Apparatus of the type described comprising a shell, a plurality of tubes within said shell,

. a baifle enveloping at least a portion of said tubes,

ranged to discharge the heating medium from within the same into heat exchanging relation with the fluid entering said shell.

-14. Apparatus of the type described comprising a shell, a plurality of tubes within said shell,

the said tubes having longitudinally extending fins thereon, a baffle enveloping said tubes, means for supplying a fluid to said shell and for causing the fluid to flow through the tubes within said baflie, and means for supplying a heating medium to the interlor'of said baille to neat the fluid in the tubes therein, the said baille being arranged to discharge the heating medium from within the same into heat exchanging relation with the "fluid entering saidshell; v 1

v 15. Apparatus of the type described comprising a shell, a plurality of tubes within said shell, a baflle enveloping at least a portion of said tubes, means for supplyinga fluid to said shell and for causing the fluid to flow through the tubes within said baflie, means for supplying a heating medium to the interior of said baflle to heat the fluid in the tubes therein, and a plurality of bafile plates within said tube enveloping baflle for causing the heating medium to .flow in a circuitous path in contact with the tubes, the said tube enveloping baffle being arranged to discharge the heating medium from within the same into heat exchanging relation with thefluid entering said shell.

16. Apparatus of the type described comprising a shell, a fluid inlet port, a group of tubes within said shell communicating with said inlet port, a fluid discharge port, a second group of tubes within said shell communicating with the first group of tubes and with the fluid discharge port, a battle separating the said groups of tubes, means for bringing a heating medium into heat exchanging relation with said second group of tubes, the said baifle being arranged to confine the heating medium in heat exchanging relation with said second group of tubes and out of contact with the shell wall and to then discharge the heating medium into heat exchanging relation with said first .groupof tubes, a plurality of baflie plates within said separating bafiie for causing the heating medium to fiow in a circuitous path in contact with said second group of tubes and a plurality of bafiles within said shell for causing the heating medium to flow in a circuitous path in contact with said first group of tubes.

.17. The method of heating water with superheated steam which comprises continuously passingthe superheated steam and water into heat exchanging relation with each other in countercurrent relation, whereby the water is heated to a temperature above the saturation temperature of the steam, the steam being at first out of direct contact with the water and subsequently in direct contact therewith. 110

18. Apparatus of the type described comprising a shell, 2. fluid inlet port, a group of tubes within said shell communicating with said inlet port, a

second group of tubes within said shell communicating with said first group of tubes, a bafile separating the said groups of tubes, and means for bringing a heating medium into heat exchanging relation with said second group of tubes, the said bafile being arranged to confine the heating medium in heat exchanging relation with said second group of tubes and out of con: tact with the-shell wall and to then discharge the said. heating medium into heat exchanging relation with said first group of tubes.

.19. Apparatus of the type described comprising a shell, a plurality of tubes within said shell, the said tubes having fins thereon, a baflle enveloping said tubes; means for supplying fluid to said shell and for causing the fluid to flow through the tubes within said baflie, and means for supplying a heating medium to the interior of said baflle to heat the fluid in the tubes therein, the said baflie being arranged to discharge the heating medium from within the same into heat exchanging relation with the fluid entering said shell.

20. Apparatus of the type described, comprising a shell containing at least two progressive heating zones in communication with each other, means for supplying a heating medium, first to one of said zones and then to the other zone, and

baflie means separating said first zone from the shell wall whereby the heating medium is prevented trom coming into contact with the shell well until after its temperature has been considerably reduced.

STANLEY BROWN.

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