US2893706A - Capsule type heat exchanger - Google Patents

Description

July 7, 1959 A. L. SMITH CAPSULE TYPE HEAT' EXCHANGER Filed NOV. 29. 1955 2 Sheets-Sheet 1 KIIIIIIII:IZTI+TIQIIIII I: 2

.1 a w e flk/kurl eroy Smifll F C fiTTOR/VEY July 7, 1959 A. L. SMITH CAPSULE TYPE HEAT EXCHANGER 2 Sheets-Sheet 2 Filed Nov 29. 1955 INVENTOR. flrikor Aeror 6m!!! BY 197' TOR/V5 Y United States Patent CAPSULE TYPE HEAT EXCHANGER Arthur Leroy Smith, Seattle, Wash. Application November 29, 1955, Serial No. 549,615

1 Claim. (Cl. 257-263) My invention relates to a capsule type heat exchangerand an object of my invention is to provide a heat exchanger which is a sealed and entirely self contained unit that will operate without any loss of the heat transferring medium contained therein.

Another object is to provide a heat exchange unit which is highly efiicient in transferring heat from heat generating means to a fluid to be heated.

Another object is'to provide a sealed heat exchanger which may contain a heat transfer fluid or substance which vaporizes at a higher temperature than water and is therefore capable of carrying or transferring more heat than will be transferred by an equal amount of water.

Another object is to provide a heat exchanger which is simple in construction, not expensive to manufacture, easy to incorporate into heating plants of the hot air, hot water and steam type and one which is compact in construction and can be made in diiferent sizes and used in multiples of any desired number.

Another object is to provide a heat exchange unit comprising three telescopically disposed concentric tubular members of different diameters supported in spaced apart relation and with the end portions of the two inner members sealed to each other thereby providing an outer annular passageway for ascending hot fluid and in axial passageway for descending cooled fluid and a closed and sealed heat insulating chamber between said two fluid passageways.

Other objects of my invention will be apparent from the following description taken in connection with the accompanying drawings.

Figure 1 is a longitudinal medial sectional view of a heat exchange unit constructed in accordance with my invention.

Fig. 2 is a cross section of the same taken substantially on broken line 22 of Fig. 1.

Fig. 3 is a detached elevation of a spacer member used in this heat exchange unit.

Fig. 4 is a fragmentary elevation showing longitudinal heat radiating fins provided on the exterior of this heat exchanger.

Fig. 5 is a view showing this heat exchange unit in elevation and showing in section a housing or jacket enclosing the upper end portion of said unit, facilitating quick generation of vapor.

Fig. 6 is a view partly in vertical section and partly in elevation showing a plurality of my heat exchange units incorporated into the construction of a hot water type furnace or boiler.

Fig. 7 is a view partly in vertical section and partly in elevation showing a plurality of my heat exchange units incorporated into the construction of a steam generating furnace or boiler.

Fig. 8 is a view partly in vertical section and partly in elevation showing a plurality of my heat exchange units incorporated into the construction of a hot air furnace.

Fig. 9 is a vertical sectional view, with parts in elevation, showing an adaptation of my heat exchange unit to a water heating tank.

Like reference numerals designate like parts throughout the'several views. 9

This heat exchange unit, Figs. 1 and 2, comprises an innermost tube 10 which forms an axial passageway 11 for descending cooled fluid, an intermediate tube 12 of larger cross sectional area than said innermost tube surroundingsaid innermost tube 10 in spaced relation therefrom and cooperating therewith to provide a heat insulating chamber 13 between the tubes 10 and 12 and an outermost tube 14 of larger cross sectional size than said intermediate tube surrounding said intermediate tube and cooperating with the intermediate tube 12 to provide an annular passageway 15 for ascending hot-fluid between said tubes 12 and 14.

Usually the tubes 10, 12 and 14 will be of circular cross section but it will be understood that their cross sectional shape can be varied without changing the mode of operation of the device and that the term tube, as used herein does not essentially mean a cylindrical tube.

The end portions 16 of the intermediate tube 12 are preferably spherically rounded and fit snugly against the outer walls of the innermost tube 10 at locations 17 and the two tubes are sealed together at the locations 17 by welding or brazing themor by similar processes. This seals oh the heat insulating chamber 13. This chamber 13 may be a dead air chamber or it may be a vacuum chamber or it may be filled with heat insulating material.

' The outermost tube '14 is preferably rounded and completely closed at both ends and this outermost tube 14 is longer than the tubes 10 and 12 so that it com" pletely encloses and envelops the tubes 10 and 12 with the passageway 15 extending around the ends of the tubes 10 and 12 and communicating freely with both ends of the passageway 11. The rounded end of the tube 14, shown uppermost in Fig. 1, preferably has a thickened wall portion 18 provided with an internally threaded opening which is adapted to be closed and sealed by a screw plug 19 after a correct amount of heat transferring material, which is usually a liquid at the operating temperatures of the device, has been in-- troduced.

Suitable spacer means is provided between the outermost tube 14 and the assembly formed by the other two tubes 12 and 10 in the process of construction of the device. This spacer means insures a co-axial relationship of the outermost tube 14 relative to the other two tubes 10 and 12 and keeps the area of the upright parts of the passageway 15 uniform. Also it maintains the spacing needed between the curved lower end portions of the outermost tube 14 and the intermediate tube 12. The spacing between the tubes preferably is wider at i the top end of the unit as hereinafter described.

A simple and efficient spacer member, one of which can be used at each end of the unit, is shown in Figs. 1 and 3. This spacer member consists of a single piece of wire bent to form a U shaped medial loop 26) and having two arms 21 extending obliquely in opposite directions from the open end of said loop 20. The loop 20 of each spacer member fits snugly within an end portion of the smaller tube 10 and has flattened or bent or deformed portions 22 which limit the distance the loop part can enter the tube 10. The outer ends or tips of the arms 21 of both the top and bottom spacer members contact the wall of the outermost tube and maintain a coaxial relationship of the outermost tube relative to the other tubes. Bends 23 at the location I where the spacer arms 21 join the loop parts 20 contact the lower curved end wall of the outermost tube 14 and maintain a proper spacing at the bottom ends of the tubes. Preferably the outermost tube 14 is sufficiently longer than-the other tubes so'that the space 15 is wider at: the upper ends of the tubes and the upper curved wall of the tube 14 is spaced a substantial distance above the bends 23 of the uppermost spacer member. This makes it possible to put enough of the heat transferring medium into the unit so that the level of this heat transferring medium can never drop below the top end of the innermost tube due to cooling and contraction of this medium. Circulation of this heat transferring medium is impaired if its uppermost level drops below the level of the upper'end of the innermost tube 10.

Preferably each unitis filled with a heat transferring medium which vaporizes at a higher temperature than water and is therefore capable of transferring more heat than water and operating at a higher temperature than water. Some heat transferring mediums having this characteristic and which can be usedin this unit are glycerine, sodium nitrate and sodium nitrite. The heat transferring medium is essentially liquid at the operating temperatures of the device but some of the mediums used may be crystaline in form when cold.

In filling or charging each unit care is taken that the unit is completely filled with heating medium and that the temperature of this heating medium has been raised to at least the maximum operating temperature of the unit so that all of the medium is fully expanded at the time the unit is sealed by applying the screw plug 19. This insures that there will be substantially no air left in the filled and sealedunit. As the heating medium cools and contracts the space left in the unit will be, as nearly as possible, a vacuum and thus when the heating medium later expands in the normal operation of the device it will not be expanding andv operating against increasing air pressure. When the unit is in use only the lower endportion of the same will be receiving heat and the upper end portion will be giving up heat so that the entire body of heat transferring medium will never all be heated to its maximum temperature at the same time during operation. Thus there will not be any danger of damaging the unit due to the building up of excess pressure caused by expansion of the heating medium. When the unit is cool 7, the heating medium may assume a level as indicated by the line 24 in Fig. 1..

The heat radiating efiiciency of this unit can be increased by providing heat radiating fins 27 see Fig. 4, on the exterior of the outermost tube 14 toward the upper end thereof. Preferably the fins 27 extend lengthwise of the unit.

To facilitate installation of these units I preferably provide an externally threaded collar 25 on each unit about half way between the two ends thereof. Each collar is fixedly attached to and sealed to the outermost tube 14, preferably by welding, and the end of each collar 25 toward the lower end of the unit is provided with preferably at least twonotches 26 of suitable shape and size to receive a tool by which the unit may be turned in threadedly engaging it with another member or may be held against rotation.

In the use of this heat exchange unit the lower end thereof, that is usually the part below the collar 25, is subjected to heat and the upper end portion or part above the collar 25 is positioned and arranged so that heat will be picked up or extracted therefrom. Thus when the lower end portion of one of the units is heated a continuous gravity circulation of the heat exchange medium therein will take place in the direction indicated by the arrows in Fig. 1. The heated medium moves upwardly in the passageway 15, giving up heat as it approaches the upper end of the unit and after thus giving up heat it flows downwardly through the innermost passageway 11 and returns to the lower end of the passageway 15. The insulation provided by the chamber 13 prevents the descending medium from receiving an appreciable amount of heat while it is moving downwardly in the tube 10 and thus helps materially in providing an efficient gravity circulation of the heat transfer medium.

Fig. 5 shows an instantaneous vapor generator using one of my heat exchange units. In said Fig. 5 a jacket 30 of larger size than the outermost tube 14 envelops the upper end portion of the tube 14 and has a base part 31 which is threaded into the collar 25. A plate 32 below the base part 31 supports the unit and the end portion of the unit below the plate 32 is subjected to heat. For instance it may be positioned within a heating chamber 33. Liquid is introduced into the upper end of the jacket 30 by pressure means", which may be an injector 34. This liquid is instantly converted into vapor and the vapor is led off through a conduit 35 and can be used in a power generator or for other purposes. The use, in my heat exchange unit, of a heat transfer medium which vaporizes at a higher temperature than water makes it possible to maintain the heat of the upper end portion of the heat exchange unit shown in Fig. 5 at a temperature substantially above the boiling point of water and thus makes it possible to produce high pressure superheated vapor instantly within the jacket 30 by introducing, through the pressure means 34, water or other liquid which vaporizes at a: different temperature than water.

Fig. 6 shows a plurality of these units used in ahot water type furnace. This furnace comprises a housing 36 having an upper water heating compartment 37 and a lower combustion chamber 38 separated from each other by a horizontal partition 39 which supports the heating units. The combustion chamber 38 preferably has a lining 40 of refractory material. An oil burner 41 is illustrative of means for heating the chamber 38 and a smoke, pipe 42 illustrates means for removing by-products of combustion. A water inlet pipe 43 is connected with the lower part of the water heating compartment 37 and a water outlet pipe communicates with compartment 37 at a higher elevation. In the disclosure of Fig. 6 each of the heating units operates independently of the others in picking up heat from the chamber 38 and transferring it to the water in chamber 37.

Fig. 7 shows a steam generating plant comprising a furnace 45 having a combustion chamber 46 lined with heat insulating material 47 and provided with an oil burner 48 and smoke pipe 49 all similar to the parts just hereinbefore described. Also the furnace 4-5 has a horizontal partition plate 50 carrying a plurality of my heat exchange units and has an upright partition 51 which divides the space above the horizontal plate 50 onto a water compartment 52 and a steam compartment 53. The two compartments 52 and 53 are in communication with each other by way of a narrow passageway 54 between the top edge of the upright partition 51 and the top of the furnace 45. The manner of forming the passageway 54 can be varied. The collars 25 are omitted from the heat exchange units shown in Fig. 7 and the units are welded directly into the horizontal plate 50. This does not change the operation of these units, however I prefer to use the collars 25. In operation of the embodiment shown in Fig. 7 water vapor formed in the chamber 52 passes through passageway 54 into the chamber 53 where it is further heated to form steam or superheated steam. This steam may then pass to radiators or to any steam consuming device. The supply of water in the chamber 52 can be replenished by way of an inlet conduit 56.

Fig. 8 shows a hot air heating plant comprising a furnace 57 having a combustion chamber 58 lined with heat insulating material 59 and provided with an oil burner 60 and smoke pipe 61. A horizontal partition plate 62 in the furnace 57 supports heat exchange units. A heat pick up chamber 63 is provided above the partition 62 and an air inlet conduit 64 and air outlet conduit 65 are connected with the chamber 63.

Fig. 9 shows a water heater or hot water tank using one of my heat exchange units. In said Fig. 9 numeral 66 indicates a tank, 67 a water compartment in the upper portion of said tank, 68 a bottom wall separating the water compartment 67 from a combustion chamber 69 and supporting this heat exchange unit. A heat generating device 70 is provided in the combustion chamber 69. A tubular jacket 71 of larger diameter than the outer shell of the heat exchange unit is supported from said heat exchange unit by a bracket 72 which rests on the top of the unit and by spacer members 73 within the lower portion of said jacket. The jacket 71 is open at both ends and is supported clear of the bottom wall 68. Water entering at the lower end of the jacket 71 and moving upwardly through the narrow space 74 between the jacket 71 and the heat exchange unit will be heated and delivered as hot water in the upper end of the water compartment 67. Said compartment 67 has a Water draw-off pipe 75 connected with its upper end portion and a water inlet pipe 76 connected with its lower end portion. This provides a water heater from which a limited amount of hot water can be drawn off within a very short time after heating of the combustion chamber is started. Thus in starting with cold water it is not necessary for all of the water in the tank to be heated before hot water can be drawn 011.

The foregoing description and accompanying drawings clearly disclose a preferred embodiment of my invention but it will be understood that this disclosure is merely illustrative and that changes may be made within the scope and spirit of the following claim.

I claim:

A heat exchange unit comprising an innermost tube forming an axial fluid passageway of uniform area from end to end thereof for descending cooled fluid; an intermediate tube of larger cross sectional size than said innermost tube disposed around said innermost tube in spaced relation therefrom and having inwardly curved end portions sealed to the end portions of said innermost tube providing a heat insulating chamber between said innermost tube and said intermediate tube; an outermost tube of larger cross sectional size and greater length than said intermediate tube disposed around and spaced from said intermediate tube and having tightly closed curved end portions extending over and around both ends of said two other tubes relatively close to but spaced from the ends of said two other tubes, said outermost tube being a closed shell completely enclosing said other two tubes and cooperating in forming an annular fluid passageway between said intermediate tube and said outermost tube, said annular passageway communicating at both ends with the axial passageway of the innermost tube providing a continuous sealed fluid circulation passageway entirely within said outermost tube; spacer members disposed between the end portions of said outermost tube and said two other tubes maintaining said outermost tube in longitudinal and transverse spaced relation from said intermediate tube; and heat exchange medium substantially filling the communicating passageways in said tubes, whereby when said unit is supported upright with its lower end portion in a heated area and its upper end portion in fluid to be heated heat exchange medium therein will first receive its heat and then give up its heat while it is moving upwardly in said annular passageway.

References Cited in the file of this patent UNITED STATES PATENTS 308,197 Rober Nov. 18, 1884 1,759,133 Nerad May 20, 1930 2,193,141 Price Mar. 12, 1940 2,388,587 Wilson July 18, 1944

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