US1578830A - Heat exchanger - Google Patents

Description

March SQ @236,

R. c. JONES ET AL HEAT EXCHANGER Filed August l2, 1921 5 Sheets-Sheet 1 March 30 1926.

' R. C. JONES ET AL HEAT EXCHANGER,

Filed August 12, 5 Sheets-Sheet 2 March 30,1926.[ 1,578,830

R. c. JONES ET AL HEAT EXCHANGER 5 Shets-Sheet Filed August 12 'ag w March 30,1926. 378,830 R. C. JONES ET AL HEAT EXCHANGER Filed August 12,- 1921 5 Sheets-Sheet 4 M T WWW Patented Mar, 3*

RUSSELL 0.

1,578,830 PA ENT OFFICE.

JONES, 035 BBONXVILLE, AND JOSEPH PRICE, 0.! NEW YORK, N. Y., AS-

N' TO THE G M-EK L COMPANY, OF NEW YORK, N. Y., A CORPORA- TIQN 0F ZDELA HARE.

HEAT EXCHANGEB.

To 11 M whom it mayconcern.

Be ithnown that we, Russnnn C. Jones and .losurn PRICE, both citizens of the llnited States, residin respectively, at l l'ronxville, l'Vcstchester County, New York state, and No. Briggs Avenue, New York city, Bronx County, State of New York, have invented certain new and useful .lmprm'emcnts in Heatl lxchangers; and we do hereoy declare the following to be a t'ulhclear. and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to heat exchangers for oils or similar viscous liquids which become more fluid with rise of t(1l'l'- peraiure.

In the use ot oil as a fuel. burners are employed that comprise passages through which the oil is pumped and mixed with air, and thence delivered into the combos; tion chamber in a iineiy atomized state. To secure complete atomization and perfect combustion under the boilers it. is necessary that the oil, as it passes to the burner, be in a limpid condition. Many crude oils used for fuel are of high viscosity at ordinary tenuperaiurc, but, however. become sutiiciently lluid at temperature oi between 20H and .300" F. to he used and readily atomized in a burner. burning plants it is customary to preheat the fuel oil before it passes to the burners.

it is an object of this invention to provide a device for changing the temperature of any viscous liquid that becomes more fluid with increase in temperature, and more particularly in providing a heater for fuel oil which receives the. oil in a viscous state, heats it in the most elficient manner, and presents it to the burner in proper condition for atomization, the heater being compactly and conveniently constructed.

H erctoforc the heating of fuel oil has been largelyaccomplished in heat exchangers of the type employed as feed water heaters, using steam as the heating medium. Such heaters consist usually of a steam jacket or shell containing tubes for the passage of the feed water, the tubes usually being arranged in a number of groups connected to provide several passes of the water through the shell.

Accordingly in oil- Experience has demonstrated that such heaters, while practically operative, do not give as satisfactory results when'used as oil heaters as they do when heating feed water, and it is the object of our present invention 'to provide an oil heater of the same general type as the above described heat exchangers, but capable of heating fuel oil rapidly and efliciently in a manner impossible with. heaters of present design. The essential feature of our invention is the provision of. a passage of varying cross sectional area for the oil th'roughthe heater,

the portion of the passage of largest cross section being at the intake end of the passage .where the cold oil is received from the supply tank, the cross section of the passage being gradually reduced in accordance with the emerging condition of the oil.

This principle of our heat exchanger may also be used to double advantage in refineries for condensing and cooling oil and in oil to oil. heat exchangers, the cold oil being used as a medium for cooling the hot oil. In such cases the viscosity of both the working fluid and the fluid acted upon vary with the temperature, and it is an object.

of our present inventionto provide a heat exchanger in which an elficient transfer of heatis obtained when both mediums are liquids of variable viscosity. When applied to this purpose we provide passages of variable cross section for each of the two heat exchanging mediums, the area of each passage decreasing in the direction of decreasing viscosity of the'liquid.

\Ve have made an investigation of the operation of these heat exchangers when used as oilheaters, and have ascertained some facts as to the nature of'the action which takes place. The cold oil as it enters the passage is exceedingly viscous, and its average temperature is much lower than that at the exterior of the containing tubes. Under these conditions the oil immediately adjacent to the walls of the tubes quickly become warmed. However, owing to the viscosity of the cold oil at the center of the tubes, and its consequent resistance to movement, there are practically no convection currents established, or other form of agitation, that would bring about a uniform heat distribution throughout the oil. The

result-is that the layer. of oiladjacent to .v

the walls of the passage becomes heated to a temperature nearly equal to that at the exterior of the tubes, while the oil at the center of the tube remains for a time substantially .at its original temperature and viscosity and-.isheated very gradually in its subsequent passage through the heaten- Due to'this fact, the pressure head required per foot of travel through the first part of {the fluid passage is materially greater than that necessary to maintain the flow through the latter portions of the passage. I have found that the necessary pressure head impressed over the first one-third of the length of the passage is fully one-half of the total pressure difference required between the inlet and outlet in passages having a uniform cross section throughout.

"Conduction of heat to the-inner portion of the oil column takes place but slowly. In oil to oil heat exchangers the entire volume of oil must therefore be brought into intimate-contact with the heat transferring surfaceby passing it over battles or forcing it through the fluid" passage at a relatively high velocity for 'the purpose of causing a turbulent flowto insure uniform heat transfer throughout the entire volume. The provision ofbaiile arrangements is well adapted to certain situationsbut, as is well known in the art, such construction is subject to certain definite limitations and may be prohibitive-in cost. On the other hand, it is not economical to employ an excessive pressure head to. give the oil a high velocity through the heat transferring apparatus, parti ularly since the onl pressure head available is sometimes a ow gravity head. Applicant avoids these limitations by providing a heat transferring apparatus embodyinga fluid passage of such construction that a high average velocity, of flow throughout the ap paratus may be obtained and yet in which the velocity of the most"viscous portivln of the fluid is relatively low' and the total pressure difference required between the inlet and outlet is kept within the practical limits.

The pressure head is consumed unifrirmly along the length of the passage. "This fea ture necessarily implies a uniform change in fluid pressure along the length of the passage, and increased agitation of the liquid during'the portion of its passage in which it is more fluid.

Entirely analogous conditions exist when oil is beingcooled. That portion immediately adjacent to the coolin surface becomes cooled to a temperature nearly equal to that of the surface of itself and a thin film of oil congeals about the cooling tubes, while the inner portion of the volume tends to remain at its original temperature. Thus in a heat exchanger for cooling oil or other viscous medium inwhich a viscous liquid is also emfor the hot oil should be of smaller area atfuel oil heater constructed with three passes, 4

Fig. 215 a sectional view taken on hne 22 of Fig. 1;

F ig. 3 is a View of the bottom head taken on line 3-3 of Fig. 1;

Fig. 4 is a sectional View taken on line H of Fig. 1, and showing the construe 'tion of the upper head;

Figs. 5 and 6 are views similar to Figs. 2- and 4 respectively, except that they show a heater having five passes.

Fig. 7 is a vertical section showing a modifiedform of apparatus adapted for installations in which both heat transferring mediums are viscous liquids;

Fig. 8 is a horizontal section taken on line 8-8 of Fig. 7;

Fig. 9 is a vertical scctional'vicw showing'another modified form of apparatus.

Fig..10 is a horizontal section taken on line 10--10 of Fig. 9;

Fig. 11 is a vertical sectional view showing a still further modification.

Fig. 12 is a vertical sectional view showing an apparatus similar to that shown in Fig. 7, but illustrating a modified form of tube construction.

Fig. 13 is a l'lorizontal sectional View on line 13 13 of Fig. '12.

,Fig. 14 is a sectional view illustrating a type of apparatus similar to that shown in Fig. 9 but with a modified form of tube construetion.

Fig. 15 is a' transverse sectional view on line 15-15 of Fig. 14.

Referring to the drawings, particularly to -Figs. 1 to l, the heater consists of a number of parallel tubes 1 having their ends secured in tubes plates 2, and mounted longitudinally within a sl1ell3. The shell and tube plates are welded together at' l. The heater is provided with a top head 5 and a bottom tubes lextend through the plates 2 and open into the various compartments.

Referring to Fig. 2 it is seen that the tubes are divided into three groups 13, 14

and 15. Group 13 contains approximately allows the oil to flow up through group 15 into com artment 8, and from thence through t e outlet 9 to the burner. Thus the oil traverses the length of the heater three times, each time through a smaller group of tubes. Steam is admitted at the opening 16, encounters the bafile plate 17,

circulates about the tubes 1, and when condensed is drawn off through the drain 18.

The invention is in no wise limited to a three pass heater. Fig. 5 shows a five pass construction, and any convenient number may be selected, depending upon the degree of uniformity of'pressure drop desired along the passage. In Figs. 5 and 6 the oil would pass successively through groups 19, 20, 21, 22 and 23, each grou after the first containing a smaller num erof tubes than the immedi ately preceding group. The arrange- 'IIlI1t of the compartments in the top and bottom heads would be as shown. That is the first compartment 11 into which the inlet pipe-1O leads is coextensive in area with the first group of tubes 19. The second compartment 7* connects the group 19 with group. 20 and is coextensive with both groups. The third compartment 12 connects groups 20 and 21. The fourth compartment 8 connects groups 21 and 22 and the fifth compartment 12 connects groups 22 and 23', while the sixth compartment 8 forms an outlet chamber for the heater.

Figs. 7 and 8 illustrate a modified form of the apparatus designed particularly "for .use where it is desired to cool hot oil by the tially a shell 3 and a plurality of longitudi-- nal tubes supported Within it inthe manner previously described. the tubes serving as a passage for one of the fluids and the space surrounding the tubes serving as a passage for the other fluid. Either the hot or cold liquid may be passed through the tubes. In Fig. 7 the tubes are shown as constituting a path for the coolingliqiiid, the space surrounding the tubes constitutingthe path of the hot liquid.

The shell 3 is provided with an upper head divided into chambers 26 and 27 and a lower head comprising chambers 28 and These heads are in direct communication with the tubes, the lower head being provided with an inlet 30 and the upper head with an outlet 31. At the upper end of the shell 3 adjacent to outlet 31 there is provided an inlet.32 for the hot fluid, and

at the other end of shell 3 adjacent to inlet 30' there is provided an outlet 33, the passages 32 and 33 being in direct communication with the space surrounding the tubes.

Group 13 ot' the tubes constitutes the first pass for the cold liquid and comprises the greatest number of tubes. Group 14 constitutes the second pass, having a lesser number of tubes than are contained in the first pass and within which the direction of flow is opposite to that in the first pass. Group 15 constitutes the last pass and contains the least number of tubes.

The cold liquid having a high veloity en- I tors chamber 28 through the inlet 30. This chamber is in direct communication with the lower ends of the tubes in group 13, constituting the first pass through the shell, and allows the liquid to pass through this group oi? tubes and. out into thejchamber 26 at the communication with the tubes of the second and third passes and serves to direct the discharge from the second pass into the open ends of the tubes constituting-the third pass, -from whence it is discharged into the small chamber 27 communicating with the outlet ends of these, tubes and is discharged through outlet 31. Thus, the cross sectional area. of the passage for the cold liquid decreases in the direction of decreasing viscosity which is also in the direction of its .fiow.

The space in the shell surrounding the tubes constitutes a passage for the hot liquid, this space being divided by partitions 3-1 and 35 into three compartments. surrounding the tubes ot'the respective-passes. The area of the space surrounding the tubes of the first pass is greatest, that surrounding the tubes of the second pass is smaller. :.'and that surrounding the tubes of the third pass is smallest. -To obtain an efficient transfer of heat the counter flow principle is enmloyed, the inlet 32 serving to admit the hot fluid to" the pass of smallest cross sectional area. The hot fluid flows along in this space to the end of the shell and then passes around the end of battle which'is made shorter than the length of the shell, intothe space surrounding group 14 of the tubes ('mistituting the second pass. The flow rgntiuuesalong tubes 14' lo the opposite end of the shell where. the lllllll pa ses around the end ol' the baille through the spare lel't for this purpose after which it again traverses the length of the shell through they space sari-minding group 1;} oi the tubes and passes out at Thus the area of the passage l'oi' the hot. liquid also rlerriu-iscs in lhi direction oi dccreasing viscosity which in this case. however. is opposite in the direction oi ilow.

In Figs. 5) and lo there is illusti'atial a, uiodi tied torui oi apparatus having each pass arranged in a separate shell instead of being contained in a common shell as in Fig. 7. The tubes may serve a a passage either i'or the hot or cold fluids. For instance the cold medium may be admitted through the inlet 30 to the spare sari-minding group 13 of the tubes constituting the first pass and haw.

ing the greatest area, in which ease it would travel the. length of the shell, through connecting pipes 36 into lhe'space surrounding the tubes-1 ot I the second pass, along the length. of this second pass into the third pass by means oi a comwct-ing tube 37, and from thence to the outlet 31. The hot fluid is admitted at inlet 32 into the tubes of the pass ofsuiallest section, issues from them through connecting pipe 38 into the tubes of the second pass, and from thence through the second pass into the space of largest area by means of connecting tube 39, from whence it issues through the outlet In this form of apparatus each of the fluid pas sages decreases in the direction of decreasing "viscosity, or increases in the direction of in creasing viscosity as the case may be.

- in Fig. 11 there is shown a still "further i'nodiflcation ot the type of apparatus adapted to transfer heat between two viscous liquids, in which the. various passes are contained in separate shells. in this design common heads 10 are employed for the tubes of the various passes, with chambers coextensive with the heads for directing the flow of liquid through the tubes. The tubes are however arranged in separate groups and separate cylindrical shells .surround each gror'ip, the separate shells being connected by pipes 36 and 37. The cold medium may be admitted through inlet 30 into the shell surrounding the tubes of the first pass, from whence it makes its way throughthe successive passes by means of the connecting tubes 36 and 37 and finally issues from the outlet 31 substantially as in the apparatus shown in Fig. 9. The hot medium is admitted to the chamber 27 which is in communication with the tubes of the pass having the "smallest cross sectional area. The liquid is discharged from the first pass into the chamber 29, which'is in communication with both the pass of smallest area and that of the next largest area. The discharge from the second pass is received in chamber 26 construction. Figs. 12 and 13 show an appa ratus in which the elements are contained within, a single shell 3 having a lower head (3 provided with the usual inlet passage 30 and outlet passage 31 for the fluid being acted upon. The tubes constituting the fluid passage are of an inverted U-shape, the open ends of the tubes being expanded or otherwise secured in a tube sheet 2. Three groups oftnbes are provided for obtaining a fluid passage of variable cross section, the group 13 having the greatest number of tubes and consequently being of the largest cross section. The fluid admitted at the inlet 3O passes up through the tube 13 and subsequently traverses the length of shell in the reverse direction after passing around the bends at the upper end of the tube elements. At the bottom of the shell the fluid is discharged into a chamber 12 which is also in communication with the inlet end of the tubes comprising the group 14. The entire Volume of the liquid admitted thus travw erses each of the three groups of tubes pass ing up and down the length of the shell during its passage through each group, and

is subsequently discharged from the outlet 31. Cooling liquid is admitted to the shell through the inlet opening 32 and by means of baffles 41 and 41* is directed up and down the length of shell substantially in conformity with the path followed b the fluid being acted upon, except that its 0w is in the reverse direction, and is subsequently discharged at the outlet 33. The baifles 41 are preferably supported by the tube sheet 2, while the intermediate baffles ll are seeured to the removable upper head 42 and extend down to the interior of the shellc This type of tube construction is particularly valuable in that a damaged tube element may be withdrawn by simply retrieving the upper. head 42, loosening the two ends of the tube element which-are secured inthe tube sheet,

and plugging up the holes thus'formed.

Figs. 13 and 14 disclose a similar type of tube construction, the various groups of tubes being enclosed in individual shells. The arrows indicate that the fluid being cooled is passed through the tubes. Each shell is provided with a removable head 42 for the purpose of'affording ready access to the tube elements and contains. a. central bafile 41 extending upwardly from the tube sheet 2 and serving to direct the flow ofthe working fluid along the length of the tubdti:

The modification illustrated'in Figs. 12 to 15 afi'ord a fluid passage of graduated area dividedv into three sections of equal length, each section having a different area; Since the fluid in traversing each group of tubes passes up and down the length of the shell, an apparatus comprising three groups as shown constitutes a six-pass cooler. It is obvious that any number of passes desired may be built into a-given apparatus. The apparatus as shown is designed as an oil to oil heat exchanger, and the sectional area of "the passage surroundingrthe tubes change'in about the same proportion as does the passsage within the tubes} The transfer of'ncat by a liquid depends largely on the tempe 'ature difference between the liquid and its immediate surroundings, and upon the agitation in the liquid itself, which mixes the liquid at the walls of the container with the liquid from the interior and secures a uniform heat distribu tion.

The common practice is to build heaters or coolers of this type with the passage for the liquid to'be acted upon of constant cross sectional area throughout. This type of coi'istruction necessitates the'same fluid velocity in all parts of the passage. If the liquid is viscous at the lower temperature,

this velocity is determined by the rate at which the viscous liquid can be fed through the passage. Furthermore, most of the pressure head is consumed in that portion of the passage at which the liquid is most viscous, which results in a retarded flow of theliquid during that part of its path in which it is more fluid, and consequently an absence of the agitation so necessary to ellicient transfer of heat.

With our improved heat exchanger the viscous oil moves slowly through the pass of larger area but its velocity increases niaterially upon entering the passes of smaller cross section. The change in cross sectional area of the fluid passages is proportional to the changing viscosity of the liquid so that a substantially uniform pressure drop per unit of length will be obtained throughout the apparatus. In this manner a high average velocity is maintained with a correspondingly high heat transfer etliriency.

If desired twisted metal strips as shown in Fig. 1 may be inserted in the tubes and fastened at the ends to serve as an agitator. These strips are used only in the last pass, or last several passes, in which portion of the passages the oil is relatively limpid, where an agitation of the oil will beeffected without adding undue resistance to the feed. WVe have described the apparatus shown in Figs. 1 to 6 as an oil heater employing steam in the shell as the heating medium, but it will be understood that the apparatus may be used to advantage as an oil cooler by reversing the direction of the flow of the oil through the tubes and using a coolin fluid in the shell. It will bealso understood that our invention is not limited to the details of construction of the various modifications here described, but that the structural features of the several designs may be variously modified for convenience of manufacture and to suit di'llerent conditions.

We claim 1. Apparatus for heating a. viscous liquid, comprising a shell, a plurality of metal tubes arranged longitmlinally within said shell and constituting a passage for the liquid, said shell having an inlet for steam and a drain for removing the residual water, means at the ends of the shell for etl'ecting the division of the tubes into successive groups connected in series, each of said successive groups containing a fewer nam ber of tubes than the preceding group, thereby decreasing the cross sectional area of the passage in the direction of decreasing viscosity oi the liquid.

2. In an apparatus vtor heating a viscous liquid, the combination of a support, a -plu- 3. An apparatus for ransferring heat between two liquids whose viscosity varies.

with change in temperature, a passageway for each of said liquids in heat exchanging proximity to the other, the cross sectional area of each said passageway varying in the direction of the flow of the liquid therethough, and means "for directing liquids at ditlerent temperatures through said passageways in such direction that the passageway of the liquid losing its heat increases in area and the passageway of the liquid absorbing heat decreases in area.

4. An apparatus for transferring heat between two liquids whose viscosity varies with change in temperature, a passageway for one of said liquids comprising a plurality of parallel tubes, a passageway for the other liquid surrounding said tubes, the cross sectional area" of each said passageway varying in the direction of the flow of the liquid therethrough, and means for directing liquids at dilferent temperatures throu h said passageways in such direction that the passageway of the liquid losing its heat increases in area and the passageway of the liquid absorbing heat decreases in area. v

5. In an apparatus for transferring heat between two liquids whose viscosity varies with change in temperature, a plurality of parallel tubes. constituting a passage for one of said liquids,'meansfor effecting a division of said tubes into successive groups connected in series, each of said successive groups containing a tower number of tubes than the. preceding group, and passage for the other o1 said liquids comprising a-com-- partment surrounding each group of tubes, said compartments being connected in series and each successive compartment having a smaller area than the preceding one.

I 6. The method of changing the temperature of a viscous liquid comprising passing said liquid through a passage whose crosssaid viscous liquid.

sectional area varies as the viscosity of the liquid varies and bringing heat transferring fluid into heat exchanging relation with 7. The method of changing the temperature of a viscous liquid which comprises directingthe liquid through a passage whose cross-sectional area diminishes as the Viscosity of the liquid diminishes whereby the velocity of flow is greater in that portion of the passage Where the liquid is most fluid and bringing a heat exchanging medium into heat transferring relation "with the liquid in said passage for changing" the temperature thereof.

In testimony whereof we aflix our: signatures.

JOSEPH PRICE. RUSSELL o. JONES,

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