US2085677A - High pressure heat exchanger - Google Patents

Description

C. H. THAYER HIGH PRESSURE HEAT EXGHANGER June 29, 1937.

Filed Aug'. 15, 1935 4 sheets-sheet 1 EN. FJH

June 29, 1937. c. H. THAYER HIGH PRESSURE HEAT EXCHANGER Filed Aug. 15, 1935 4 Sheets-Sheet 2 June 29, 1937. Q H. THAYER 2,085,677

- HIGH PRESSURE HEAT EXCHANGER 4 Sheets-Sheva"y 3 Filgd Aug. 15, 1935 L Nw J m f Mw M/ m Hw Ism m mm/ QW Nm\ Q w W1 A@ aV/N, @o 5.21 bv f m June 29, A1937'. f C, H, @AYER 2,085,677

HIGH PRESSURE HEAT EXCHANGER Filed Aug. 15, 1955 4 sheets-sheet 4 7 i Q N y 03 "1 M N) lo. w

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I I l Patented June 29: 1937 men PRESSURE HEAT EXCHANGER "Clarence H. Thayer, Wallingford, Pa., assigner to 'SllnOil Company, Philadelphia, Pa., a corporation of New Jersey Apnliee'tien August 15, 1935, serial e. 36,333 4 o laiine.4 71.257-7-247) This invention relates to a heat exchanger of `the type comprised of an outer tube conveying a lluid, with inner tubes arranged therein, conveying another fluid, flowing. in a counter-direc- 1 5 tien te the uuid in the enter tubes, 'and wherein one ofthe uids gives up part' of its heat to the other fluid. More particularly this invention relates tosuchheat 'exchangerswherein one or both of the uids is under avery high pressure.

AIn order -tobring aboutan eilicient heat exchange and to decrease the amount of space occupied by the heat exchanger, it is customary to provide a'number of outer tubes connected` end to end by return bends and a number' of inner tubes connected end to end by return bends. Due to thenumber of connections necessary at the return bends, and `du'e to the unequal expansion of the tubes, it'has been extremely diiiicult to construct a heat exchanger which will 20 remain tight, especially when the uids in the exchanger are under ahigh pressure. This is `lnu'ticularly' true-with the heat exchangers used at oil`re1'ineries, for here all joints should be absolutely tight as the oils in the heat exchangers 25 are generally above their flash point, and any leaks might 'have disastrous results.' Also the tubes inthe heat exchangers must be lept clean and therefore the return bends must not only be tigLt, but must also be readily removable to provide easy access to the tubes for cleaning. f Dimculty liasalso been experienced at the inlet tofthe exchanger; since it has been customary to connect the supply linevl to a relatively large header to which the tubes ofthe exchanger are connected. The "velocityoffthe fluid necessarily decreases while flowing! through the relatively large header and if the fluid is a hot synthetic crude, lthasV a decidedly increased tendency to 4o devsit'carbg- *4..A1S0ews9nhas been very greet `atithe inlet andoutlet ofthe exchanger, `due to the: change inldijrcetion efnew ef the snide,

' '.is therefore'anpbject of this inventionI to .provide a :heat exchanger, which is suitable for 5 use with `ulds whichare'under a high pressure, ani-1 Will be tight even with the relatively Y high expansion d iil'erences, but at the same .time will provide easy access to the tubes for cleaning. ,MQthBt `liject of myl invention :is to provide 0 integral, Amanifold fQr introducing lluid into and withdrawingfluid froma heat exchanger in i which thevelocity'of the ,iluid will remain'substantiallythe same as in `the supply lines, and in which the` number of sharp bends will be sreducedtoaminimum. 'I

l Other and further objects will appearas the description progresses.

In the drawings accompanying the specication, and forming a part thereof, and in which like numerals refer to like parts throughout: 5

Fig. 1 is a side elevation of the heat exchanger embodied in this invention withl theone side 'of the casing removed.

Fig. 2 is a top plan view of the heat exchanger with the top of the casing removed.

Fig. 3 is an end View taken on'the line '3-3 of Fig. 1, with the end cover plates on Vthe outer return connections removed.

Fig. 4 is an end elevation partly in section,

taken enl the line 4 4 ef Fig. 2. 15

rest on the beams 'I and suitable side plates 9 are secured to the uprights II. The top of the heat exchanger is covered by top plates I0.'

4Spaced a short distance in from the ends of the body of the heat exchanger are en d plates I2, having openings therein through which the outer tubes of the exchanger pass. 30

" At each end of the exchanger there is a box composed of a bottom plate I3 resting on thev beams "I, side plates I4, and top plates I5, one end .of which box is closed by a plate I64 having opening therein Athrough which the outer tubes of the exchanger pass. :The outer end of these boxes'is closed by doors I 'I. All outside plates anddoorsin these boxes are covered on oneV side by suitable insulating V'material I8.

'I'heheat exchanger proper is composed of a 40 number of outer tubes 20, within which are ar- Y' ranged inner' tubesZI of smaller diameter than the outer tubes, vand having suitable projections 22 to hold them in spaced' relation from theouter tubes. tubes,` extend through the entire length ofthe casing passing throughplates I2 and I BQand are supported in the casing by cross bars or` tubes 23" ext ending between the'uprights II. The space betweenv plates I2 and I6 is lled with arefractory or insulatingcementu, poured in place after the tubes are in place. The space l aroundthe tubes within the casing is filled with a powdered vinsulating -material 25.

'rue'.fiuid te be heated and the heating nu'id are introduced into land Withdrawnfrom the tubes 26 and 2| through two manifolds 21 and.v

`pipe 26 is bolted to flange 36 on the manifold 21.

The oil flows through the opening 2|, extending the entire. length of the'manifolds, into spaces 22. 'I'he other end of the manifold is closed by plate 62 bolted to flange 64.

The inner tubes -2| communicate with the space 22 in the manifold and pass through the space 22 in the manifold with which the outer tubes 26 are in communication. The inner tubes'pass through opening 24, and are rolled into this opening as shown at 25 so as to make. a tight joint. T'he other end of space 22 is closed by a tapered plug 26, which closes an opening through which a cleaning tool may be inserted, and which is held in place by a tap bolt 21 screwed through the plate 26 held in place by semi-annular shoulders 66 in the manifold body. 'I'his plate and bolt,.26 and 21 respectively, are of the type ordinarily used to hold lU return bends in place.

In order to minimize corrosion, the manifolds 26 and 21 may be constructed of 'a cast stainless steel suchl as a chrome molybdenum steel castins. Such material is subject to air hardening and therefore cannot be welded inthe field where the weld cannot be properly annealed. In order that the heat exchanger tubes may be welded to the' manifold, a collar '29 of plain .l0-.20 carbon steel may be inserted in the manifold and welded thereto b y weld 46. Likewise, the supply lines 46 may be welded tothe manifold by inserting a plain carbon steel collarV 42 in the manifold and welding it thereto by a weld 44. It is to be understood that the welds 46 and 44 will be made inv the shop and will be properly annealed to prevent or overcome embrittlement of the manifold due to air hardening. When theheat exchanger attached to the manifold by screwing them into' the manifold and welding them to collar 42 by weld 42. It is apparent that the welds 4| and 42 may be made in the field without annealing since the collars 29 and 42 are plain carbon steel and therefore are not subject to air hardening. If the manifolds 26v and 21 are of lplain cast steel or some other material not subject to air hardening, the collars 29 and 42 may be omitted and the ktubes attached to the manifold by screwing them lthereinto and welding them directly thereto.

At their other end the outer tubes in the top bank are rolled into a return header body 46 (as shown in detail in Fig. 5) and welded thereto as shown at 41. The fluid in one outer tube connected with the return header 46 flows into the space 46 therein, and into the other outer tube connected to the return header.

The inner tubes enter the space 46 and enter lthe return connection 49 placed therein, and are rolled into this return connection as shown. Openings closed by tapered screw'plugs 56 are provided in the return connection 49 opposite the inner tubes 2|, through which an expanding tool for rolling the inner tubes, or a cleaning tool may be inserted.

An annular ypacking groove 5| is provided in the return header 46, and the space 46 in the header is closed by cover plate 52 having an annular pachng groove and packing 52 and 54 respectively therein. The cover 52 is held to the return headerbody by tap bolts 55. Four key slots 56, are cut in the return header body as shown.

It is preferred to place both manifolds at one end of the exchanger, and the vbottom manifold 26 Pis supported from Athe bottom plate I2 by spacers v51, another spacer 56 rests on top of manifold 26 and'is keyed thereto by key 59 rest- Y ing in key slot 6| in the manifold. A return header 46, is keyed to the spacer 56,'and to the return headers 46 immediately above and beside it by keys 59 in key slots 56.v At the top a spacer 66 is keyed to the top return header and the top manifold 21 is keyed to this spacer and rests thereon. By supporting the return headers on the bottom manifold and each other, and the top manifold on the return headers, a ver'y simple construction is provided. Also, by keying the return headers to each other and to the manifolds, a very rigid construction is provided, so that when the bolts 55 holding the cover 52 on the return header body 46 are turned, the header will .be held by the manifold and adjoining headers against turning`,'.and so the tubes will not be twisted and the joints between the tubes and headers weakened.

-I At the other end (as shown in Fig. 4)y the headers 46, in the bottom row, are supported on and keyed to a beam 62, the next row of headers 46, is supported by the row below them and each header is keyed to the headers about it by keys 59 in"slots 56. Thus a simple and rigid construction for this end of the heat exchanger is provided.

-When the heat exchanger is used to heat up gas oil being charged to a still, by flowing it in heat exchange relation with synthetic crude coming from the still, it is preferredv to have the gas oil flow through the outer tubes, and the syn- `thetic crude flow through the inner tubes, since vthe hot synthetic crude has a tendency to deposit carbon, and it is necessary to clean the tubes through which it flows.

The hot synthetic crude enters through pipe 26 and flows through the central opening 2| in the manifold 21 entering the spaces 32, from here it enters the inner tubes 2| and flows down these tubes to the return connection 49, where it enters space 65 and from here enters the next inner' tube and flows back to the top return connection at the manifold end. The oil continues its ow back and forth through the inner tubes until it reaches the space 22- in thel bottom manifold 26. Here it flows' out through central opening 3| to oiftake pipe 66. During its flow through the inner tubes, the hot oil gives upvsome of its heat to the oil in the outer tubes.

The charging oil to the still enters the spac 33 in the bottom manifold 26 from pipes 61, and from this space enters the outer tubes 2li. The oil flows through the lower bank of outer tubes, and enters the spaces 46 in the lower row of return headers and its flow is reversed, and the fluid flows back through the next bank of outer tubes. 'I'he fluid continues this ilow back and forth until it i'iows into the spaces 39 in the top manifold 21, andleaves the heat exchanger through pipes 45. During its travel through the outer tubes, theJ fluid takes up a great deal of heat from the fluid in the inner tubes.

It is to be noted that the inner tubes 2| are in no way connected to the outer tubes 20, and the return connections 49of the inner tubes are not connected to the body 46 of the return headferently due to the difference in the temperature ofthe fluids being transmitted. By having the inner tubes and their return connections iloat'in the outer tubes and theirreturn headers, this unequal expansion may take place without placing undue strain on the joints in the exchanger and weakening them to cause leaks. It is also apparent that as the temperature of the fluid in the outer tubes rises as it travels through the exchanger, there will be greater expansion in the upper banks of outer tubes than thelower tubes. Since the return headers are not xedly connected to each other, thisl unequal expansion is permitted to take place without unduly strainingthe joints in the exchanger and causing leaks.

It is apparent that while this heat exchangerV has been described as having the heating fluid flow through the inner tubes and the other iiuid flow vthrough the outer tubes, this flow may be reversed.

If it is desired to increase the capacity ofthe exchanger, its size may be doubled by removing 4plate 63 and' pipe 66 from manifolds 21 and 26 "scribed as having both manifolds at one end of the exchanger casing, it is apparent that the inlet manifold may be placed at one end of the casing and the outlet manifold at the other end.

What I claim anddesire to protect by Letters Patent is as follows:

1. A heat exchanger comprising a multiplicity of series of tubes of relatively large diameter, a multiplicity of series of tubes ofrelatively small diameter, return headers joining adjacent pairs of said tubes of relatively large diameter, return 4connections arranged within said return headers and `joining adjacent pairs of said tubes of relatively small diameter, an integral manifold at each end of said multiplicity of series of tubes for introducing fluid into one of saidseries of tubes and withdrawing fluid from the other of said series of tubes, each of said manifolds comprising a longitudinal chamber with which said tubes of relatively small diameter communicate, and chambers surrounding the ends of said tubes of relatively small dlameterand with which said diameter, return headers joining adjacent pairs of said tubes of relatively large diameter, return connections arranged within said return headers and joining adjacent pairs of said tubes of rela, tively small diameter, an integral manifold Aat each endof said multiplicity of series of tubes for introducing fluid into one of said series of tubes and withdrawing fluid from the other of said series of tubes, each of said manifolds comprising a longitudinal chamber with which said tubes of relatively small diameter communicate and chambers surrounding the ends of said tubes of relatively small diameter and with which said tubes of relatively large diameter communicate, keys interlocking the headers by means of which headers on a lower level support headers on a higher level, and spacing devices interposed be-F tween said manifolds and the adjacent headers by means of which the headers are supported by one manifold and support the other manifold.

3. A heat exchanger comprising a multiplicity of series of tubes of relatively large diameter, a multiplicity of series'- of tubes of relatively small diameter, return headers joining adjacent pairs of said tubes of relatively large diameter, return connections arranged within said return headers and joining adjacent pairs of said tubes of relatively small diameter, an integral manifold at each end of said multiplicity of series of tubes for introducing fluidinto one of said series of tubes and withdrawing fluid from the other of said series of tubes, each of said manifolds comprising a longitudinal chamber with which said tubes of relatively small diameter communicate and chambers surrounding the ends of said tubes of relatively small diameter and with which said tubes of relatively large diameter communicate, keys interlocking the headers by means of which headers on a lower level support headers on a higher level, and spacing devices interposed between said manifolds and the adjacent headers by means of which theheaders are supported by one manimultiplicity of series of tubesof relatively small diameter, return headers joining adjacent pairs of said tubes of relatively large diameter, return connections arranged within said return headersy and joining adjacent pairs of said tubes of relatively small diameter, an integral Imanifold at each end of said multiplicity of series of tubes for introducing fluid into one of said series of tubes and withdrawing fluid from the other of said series of tubes, each of said manifolds comprising a longitudinal chamberwith which said tubes of relatively small diameter communicate. openings in said longitudinal chamber opposite the ends of said tubes of relatively small diameter,

removable plugs closing said openings, and chambers surrounding the ends of said tubes of rela- F0 tively small diameter and with which said tubes of y relatively large diameter communicate, means for interlockingadjacent return headers, and means for interlocking said manifolds and the return headers adjoining the same.

" CLARENCE H. THAYER.

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