US2745639A

US2745639A - Heat exchanger

Info

Publication number: US2745639A
Application number: US368064A
Authority: US
Inventors: Patrick F Dougherty
Original assignee: Sun Oil Co
Current assignee: Sunoco Inc
Priority date: 1953-07-15
Filing date: 1953-07-15
Publication date: 1956-05-15
Anticipated expiration: 1973-05-15

Description

P. F. DOUGHERTY HEAT EXCHANGER 2 Sheets-Sheet l ATTORNEY May 15, 1956 Filed July 15, 1953 MAT EXSHANGER Patrick F. Dougherty, Chester Weights, Pa., assigner to Sun @il Company, Philadelphia, Pa., a corporation of New Jersey Application July 15, 1953, Serial No. 368,064

2 Claims. (Si. 257-1) This invention relates generally to heat exchange apparatus of the tubular type and more particularly to improvements in cleaning such devices for continued eicient operation.

Heat exchangers as used in the refining of petroleum, for example, are constructed of tubes arranged in parallel through which a heating medium is conducted. The petroleum derivative requiring further treatment is circulated around these tubes in heat exchange relation. After a time, Varying with the nature of the petroleum derivative circulated and the temperatures transmitted to the device, the spaces between the tubes become clogged with gum and sludge, and, more particularly, corrosion products, reducing the efiiciency of the exchanger. The device must then be cleaned or otherwise reconditioned to recover the necessary economical operating conditions.

This necessary cleaning has been approached from many ways and with a variety of tools aording some improvement but not complete satisfaction. Short of removal and replacement of critical tubes making the clogged sections available to the further manual removal of the fouling material, the procedure of cleaning has not been entirely successful. ln most cases, frequent partial cleaning with resultant nal complete fouling over a comparatively short time has been the accepted procedure. Under these practices, it is frequently necessary to replace the entire tubular structure, which is very expensive. lt is an object of this invention to provide a device of this class which can be completely cleaned of all fouling material with a minimum of dismantling of the elements.

Mechanical devices for performing these operations as an integral part of the completely assembled heat exchanger are known to the art. They take the form of nozzles insertable through automatically controlled openings, permanent nozzles housed in xed positions among the tubes, and like arrangements. All such devices are objectionable because they become embedded in the corrosion products, gum and sludge, so firmly as to be immovable, or plugged, and consequently inoperative. It is a further object of this invention to provide a cleaning means insertable in predetermined spaces among the heat exchange tubes not subject to becoming inoperative through clogging.

Where insertable nozzles for cleaning have been used in the past, it has always been a major problem to guide these cleaning means into the spaces selected for the operation. Exteriorly arranged brackets and interior movable guides have been suggested. The exterior bracket is objectionable as interfering with normal operations, While the interior guide is subject to becoming frozen in one position by the residue and corrosion products from the process, as generally noted above. To insert an unguided cleaning element through a space between the tubes is a threat to both the tubes and the transversely arranged tube sheets and bafles. Deviation to one side of the permissive space and connecting tube sheet openings will destroy the exchanger. Consequently it is a further object to provide a heat exchanger in which permanently accessible spaces selected in the tubular strucnited States Pate ture are available to a guided cleaning element incapable of rupturing the heat exchange elements.

For a full understanding of the invention a detailed description of a construction embodying the same in one operating form is now given in connection with the accompanying drawings forming a part of this specification, in which:

Figure l is an elevational view, partly in section, of the device in operational assembly.

Figures 2 and 3 are sectional views of Figure 1 taken on lines 2 2 and 3 3 respectively.

Figure 4 is a foreshortened detail of one of the operating elements. l

Figure 5 is a detail of the cleaning means showing the cooperating end for use with other operating elements.

Figure 6 is a detail of the cleaning elements being assembled.

Figure 7 is an elevational view in section showing the cleaning operation.

Figure 8 is a second sectional view of Figure l taken on line 3--3.

As indicated above, this invention is two-fold in purpose in that it provides a modilied heat exchanger of the tubular type and the cleaning elements necessary to cooperate with the exchanger. The purpose served, .as indicated by the above stated objects, is to combine the heat exchanger and cleaning elements into a device which can be cleaned completely of fouling obstructions Without damage to the elements. Additional-ly the insertable cleaning element is required to follow a predetermined path among the tubes preventing rupture to the internal assembly and insuring complete cleaning. These advantages will be evident in the following disclosure of detailand operation.

Referring to Figure l, a conventional, horizontal-tube heat exchanger is illustrated as one form with which the cleaning structure is readily adaptable. The casing 10 from which the tube bank l2 is removable for the cleaning operatic-n is here indicated merely as a shell. The hanged

openings

14 and 16 admit and remove the petroleum fraction, or other liquid, circulated in thermal exchange in the casing 10. On the ends of the casing 10, separated from the volume connected by

openings

14 and 16, are

heating fluid compartments

18 and 20.

Tube sheets

22 and 24 separate the heat exchange volume 26 around the tube bank 12 from these compartments by sealing the tubes therein. At spaced intervals along the length of the tubes, baiiies 28 support the tubes transverse their length, lending rigidity to the device and act as a guide for the circulated liquid in volume 26. Additionally, in the illustrated device, the interior space 26 is divided into quadrants by the vertical and

horizontal baffles

30 and 32 respectively for additional eciency. This arrangement of elements pictorially suggests a typical heat exchanger and is not intended to limit the invention to this specic form of device.

Consideration of Figures 2 and 3 in conjunction with Figure l shows the tubes in the tube bank 12 to be arranged in regular, or symmetrical, order. The order shown is oneof several dilerent arrangements aud is not intended to be exclusive. As described later it Will be understood that the present invention is applicable to any or all tubular arrangements, or combinations of the same.

Within the tube bank l2, a number of inoperative or dummy tubes d2, as distinguished from the active tubes above described as part of the tube bank 12, are located in each quadrant. These are so spaced as to give overlapping cleaning spaces between the active tubes 4l but do not exceed 15% of the eective heat exchange tubes area as required for most eihcient opera.- tion.

Interspersed among the tube ends in Figures l and 2, larger diameters are indicated and caps are shown extending beyond the

baffles

22 and 24 illustrating the above mentioned dummy tube placement. r[his structure is detailed in Figures 4 and 6,V wherein the caps 34 are shown to be threadedly attached to the nipples 36, which are connected to the

tube sheets

22 and 24. Thus the caps 34 seal the

tube sheets

22 and 24 over the

apertures

38 and 40. Slidably positioned to rest in these apertures and free to revolve, slide longitudinally or otherwise move, these dummy tubes or rod-like members 42 are assembled.

These members 42, solid or hollow and made of glass, plastic, metal, wood or any material selected for resisting the binding eiect of the fouling material deposited from the liquid in heat exchange, are assembled within the device either` during t' ci' later modiiication. Because the niovability o.- rcds which is maintained under operating conditions by the flow of the liquid and temperature and pressure variations, the ends are shaped to permit insertion of holding tools to prevent turning as a part of the operation. This is necessary when coupling the nozzle shown in Figures 5, 6 and 7, which the member 42 is also adapted to receive on either end.

A hollow rod 44, apertured at 46 and closed on the connecting end by threads 4S and an operating handle 50 on the opposite end, forms the cleaning means. As a spray nozzle, it may be increased in pressure characteristics by shaping and directing the apertures 46 for specic purposes. Figure 7 shows a hose 52 connected to carry the cleaning liquid, which may include suspended solids or be comprised of solids only such as sand or other abrasives, selected because of their particular effect on the fouling material.

Consideration of the detailed description of the elements as given above, in connection with the figures of the drawing already discussed, will fully reveal the operation of the device. However, to emphasize the particula'r utility of the combination and describe its advantages c-ver current practice, the operation of cleaning will be discussed.

As shown in Figure 7, the tube bank 12 is removed from the casing 10 in preparation for the cleaning operation. Caps 34 are removed from the supporting apertures on each end of the selected dummy tube. As noted the cleanable area in the vicinity of the dummy tube is pre-selected when the heat exchanger is constructed or modified for the purposes disclosed here. A holding tool 54, such as is shown in Figure 6, is inserted to engage the slot 56 and keep the tube from turning. The nozzle 44 is placed in position to engage its threaded end 48 in the threaded hole S3 of the dummy tube 42.

When theV tube 42 and nozzle 44 are engaged, the tool S4 is removed and the nozzle moved longitudinally of the tube bank 12 in cleaning operation. This is illustrated in Figure 7. The rod 42 guides the nozzle 44 through the tube sheets 2S and in alignment with the tube bank 12, preventing injury, and directing the cleaning material to a selected space between and around adjacent tubes.

A suggestion of the stream direction in the area surrounding the nozzle and the service section of several dummy tubes is illustrated in Figure 8. The active tubes 41 are omitted for clarity. Proper spacing of the dummy tubes and successive use of the cleaning means in each preselected area, plus rotation and longitudinal movement, insures complete, safe cleaning.

On completionl of the cleaning operation, the nozzle is withdrawn to the insertion position of Figure 6 and the tool 54 engaged in the free end of the dummy tube or rod 42. The nozzle is disengaged and the caps 34 replaced. This is repeated throughout the device.

By including in the heat exchanger structure nonbinding guide-rod members, properly spaced and within the allowable number short of affecting eiiiciency, cleaning can be accomplished when desirable. The cleaning material conducting member, noted as a nozzle, is not a part of the permanent structure but is introduced therein only during the cleaning operation. By connecting the guide-rod and nozzle-rod together during this cleaning operation, the nozzle is limited to a predetermined effective area, and prevented from doing injury to the stationary elements in the exchanger.

l claim:

l. The combination with a heat exchanger of the type comprising a bundle of spaced apart tubes extending in parallel relationship and end plates between which the tubes are supported, the heat exchange being effected between fluid flowing through the tubes and iiuid ilowing through the space surrounding the tubes: of a number of rods extending between the plates in parallel relationship with and spaced from each other and from the heat-exchanger tubes and having no heat exchange function, the rods being loosely held between the end plates permitting movement in response to the internal conditions of the heat exchanger and longitudinally slidable, for a predetermined distance, within the tube bundle, the rods having each an end element to which is attachable the end of a cleaning tube having a multiplicity of perforations in its wall'and adapted to receive cleaning fluid and discharge it through the perforations, each of said rods, when so attached to a,

cleaning tube, and moved for said distance longitudinally as aforesaid, pl cing the cleaning tube in the position theretofore occupied by the rod before such movement, to discharge cleaning fluid through the perforations toward the heat exchanger tubes of the bundle to eect removal therefrom of Jfouling material deposited thereon, the rodsk and attached cleaning tube, when the longitudinal movement of the rods is reversed, withdrawing the cleaning tube and restoring the rods to the tirst speciiied position to adapt the heat exchanger for normal heat exchange operation.

2. The combination with a heat exchanger of the type comprising a bundle of spaced apart tubes extending in parallel relationship and end plates between which the tubes are supported, the heat exchange being eliected between fluid owing through the tubes and fluid flowing through the space surrounding the tubes: or" a number of rods extending between the plates in parallel relationship with and spaced from each other and from the heat-exchanger tubes and having no heat exchange function, the rods being loosely held between the end plates permitting movement in response to the internal conditions of the heat exchanger and longitudinally slidable for a predetermined distance within the tube bundle, a cleaning tube having a multiplicity of perforations in its wall and adapted to receive cleaning iiuid and discharge it through the perforations, means to attach the end of said cleaning tube to an end of each rod, the cleaning tube being thus movable, when the slidable rod is moved as aforesaid, into the position theretofore occupied by the rod and thus into position to discharge cleaning iiuid through the perforations toward the heat exchange tubes of the bundle to effect removal therefrom of the fouling material deposited thereon, the rods, as they are successively attached to the cleaning tube, when the longitudinal movement of the rods and cleaning tube is reversed, withdrawing the cleaning tube from the tube bundle and restoring the rods to the first named position to adapt the heat exchanger to normal heat-exchange operation.

References Cited in the file of this patent UNTED STATES PATENTS 2,302,513 Abraham NOV. 17, 1942 2,538,70l Meyer lan. 16, 1951 2,634,164 Drake Apr. 7, 1953 FOREIGN PATENTS 367,147 Germany Nov. 6, 1919

Claims

1. THE COMBINATION WITH A HEAT EXCHANGER OF THE TYPE COMPRISING A BUNDLE OF SPACED APART TUBES EXTENDING IN PARALLEL RELATIONSHIP AND END PLATES BETWEEN WHICH THE TUBES ARE SUPPORTED, THE HEAT EXCHANGE BEING EFFECTED BETWEEN FLUID FLOWING THROUGH THE TUBES AND FLUID FLOWING THROUGH THE SPACE SURROUNDING THE TUBES: OF A NUMBER OF RODS EXTENDING BETWEEN THE PLATES IN PARALLEL RELATIONSHIP WITH AND SPACED FROM EACH OTHER AND FROM THE HEAT-EXCHANGER TUBES AND HAVING NO HEAT EXCHANGE FUNCTION, THE RODS BEING LOOSELY HELD BETWEEN THE END PLATES PERMITTING MOVEMENT IN RESPONSE TO THE INTERNAL CONDITIONS OF THE HEAT EXCHANGE AND LONGITUDINALLY SLIDABLE, FOR A PREDETERMINED DISTANCE, WITHIN THE TUBE BUNDLE, THE RODS HAVING EACH AN END ELEMENT TO WHICH IS ATTACHABLE THE END OF A CLEANING TUBE HAVING A MULTIPLICITY OF PERFORATIONS IN ITS WALL AND ADAPTED TO RECEIVE CLEANING FLUID AND DISCHARGE IT THROUGH THE PERFORATIONS, EACH OF SAID RODS, WHEN SO ATTACHED TO A CLEANING TUBE, AND MOVED FOR SAID DISTANCE LONGITUDINALLY AS AFORESAID, PLACING THE CLEANING TUBE IN THE POSITION THERETOFORE OCCUPIED BY THE ROD BEFORE SUCH MOVEMENT, TO DISCHARGE CLEANING FLUID THROUGH THE PERFORATIONS TOWARD THE HEAT EXCHANGER TUBES OF THE BUNDLE TO EFFECT REMOVAL THEREFROM OF FOULING MATERIAL DEPOSITED THEREON, THE RODS AND ATTACHED CLEANING TUBE, WHEN THE LONGITUDINAL MOVEMENT OF THE RODS IS REVERSED, WITHDRAWING THE CLEANING TUBE AND RESTORING THE RODS TO THE FIRST SPECIFIED POSITION TO ADAPT THE HEAT EXCHANGER FOR NORMAL HEAT EXCHANGE OPERATION.