US2775682A - Electric fluid heater - Google Patents

Description

4 Sheets-Sheet 1 Filed Aug. 1;, 1355 lll Dec. 25, 1956 P. HYYNES ELECTRIC FLUID HEATER 4 Sheets-Sheet 2 Filed Aug. 12, 1955 INVENTOR Lee K A yn/es Dec. 25, 1956 P. HYNES ELECTRIC 'FLUID HEATER 4 Sheets-Sheet 3 Filed Aug. 12, 1955 INVENTOR 4 ee /2 Agnes Dec. 25, 1956 1.. P. HYNES ELECTRIC FLUID HEATER 4 Sheets-Sheet 4 Filed Aug. 12, 1955 INVENTOR 14 ee H nes United States ELECTRIC FLUID HEATER Application August 12, 1955, Serial No. 527,919

10 Claims. (Cl. 219-38) The present invention relates to electric heaters for fluids, especially for liquids such as oil, chemicals, heat transfer media and the like.

A purpose of the invention is to simplify the construction of an electric heater for fluid and make it possible to produce the same in a wide variety of forms without maintaining a high inventory of components.

A further purpose is to secure more effective heat transfer in an electric heater without localized hot spots.

A further purpose is to reduce the pressure resisting requirements of the electric heater flow tubes so that a very simple construction can be employed.

A further purpose is to build up an electric heaterfrom units consisting of a heater tube and a flow tube, permitting a wide variety of combinations without substantial modification in the units themselves.

Further purposes appear in the specification and in the claims.

In the drawings I have chosen to illustrate a few only of the numerous embodiments in which my invention may appear, selecting the forms shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

Figure 1 is an end elevation of a heater tube and partition walls according to the preferred embodiment.

Figure la is a fragmentary perspective of the heater itself.

Figure 2 is a side elevation of the combination of heater tube and partitions of Figure 1 sectioned on the line 22.

Figure 3 is an end elevation of a combination of a flow tube, heater tube and partitions according to the invention.

Figure 4 is a longitudinal section on the line 44 of Figure 3.

Figure 5 is a fragmentary perspective of the end of the flow tube having the cross connection.

Figure 6 is a fragmentary perspective showing a stack of flow tubes and heater tubes, the heater tubes being broken away to simplify the illustration.

Figure 7 is an end elevation of the stack with its end headers and its longitudinal separating partition.

Figure 8 is a side elevation of the structure of Figure 7.

Figure 9 is a horizontal section through the structure of Figure 7 on the line 99.

Figure 10 is a side elevation of the completed heater provided with a jacket, the jacket being sectioned in central vertical section.

Figures 11 to illustrate a modified embodiment of the invention.

Figure 11 is a central longitudinal section of a modified combination of heater tube and flow tube.

Figure 12 is a section on the line 1212 of Figure 11.

Figure 13 is a section of the completed heater provided with its jacket, the section being taken on the line 13-13 of Figure 14.

Figure 14 is a transverse section of the completed atent 'ice heater of Figure 13, the section being taken on the line 14-14 of Figure 13.

Figure 15 is a plan section of the heater, the jacket being shown in central horizontal section and one end of the stack being broken away.

Figures 16 and 17 illustrate a further embodiment of the heater of the invention.

Figure 16 is a central longitudinal section on the line 1616 of Figure 17.

Figure 17 is a transverse section on the line 1717 of Figure 16.

Figures 18 to 20 illustrate a further modification.

Figure 18 is a longitudinal section on the line 18-18 of Figure 19.

Figure 19 is a transverse section through the heater of Figure 18.

Figure 20 is a central longitudinal section on the line 20*20 of Figure 19.

Figure 21 is a transverse section of a modified heater according to the invention.

Describing in illustration but not in limitation and referring to the drawings:

In the prior art electric heaters for liquids such as oil, heat transfer media and chemicals and also for other fluids such as gases have usually involved relatively compiicated and expensive structures requiring establishment of designs in particular sizes and maintenance of inventories of a large number of components. In the design of heaters of this character, each job or many of the jobs are likely to have different requirements, necessitating more or less heat input according to the particular conditions. The heater of the present invention is designed to permit construction of a wide variety of heaters from a few standard assemblies.

Furthermore most of the heater parts are not required to stand up under the pressure differential between the fluid heated and atmosphere, so that relatively light and inexpensive components can be used.

According to the invention also maintenance requirements are reduced to a minimum, so that maximum service life free from maintenance can be obtained.

Considering first the form of Figures 1 to 10, I there illustrate a circular heater tube which is closed at one end as by welded plug 31 and receives an electric heater of any well known type, preferably that of my patent application suitably consisting of metallic heating elements 32 extending through openings in insulators 33, the insulators being secured to a heater bar 34 as by clips 35. The electric heater elements are electrically connected in any suitable manner as well known. In order to simplify the illustration the electric heater is shown in Figure 1a but is omitted from the other views. it will be understood that it is present inside the heater tube in each case.

Secured radially at opposite positions to the outside of the heater tube as by welding, are partitions 35 which extend suitably from the rear of the heater tube part only of the distance forward as later explained.

The assembly of the heater, heater tube and partitions is placed in a flow tube 36 which in the form shown is rectangular and preferably square in cross section, being conveniently formed by bending a sheet and welding longitudinally at 37. The outer ends of the partitions 35 engage in the opposite corners 38 of the flow tube and desirably are tack welded at 40 at the forward end to maintain the proper relation shown in Figure 4. As here shown, the heater tube does not extend fully to the rear but leaves a space 41 unoccupied which provides a cross connection between the two heating passages 42 and 53 formed on opposite sides of the partitions 35. The partitions 35 extend fully to the front at 44 thus forming a barrier against cross flow which is not intended, as later explained.

Each of the flow tubes at the forward end is notched on two adjoining sides at 45 as shown in Figure 5 and the direction of the flow is established by predetermining the correct angular position of the flow tubes in the stack. Using Figure 6 as an example, which shows six units assembled in two vertical columns of 3, inlet flow takes place at 46 through the notch 46' in the flow tube 47, and flow is accomplished longitudinally in the passage 48 on one side of the partitions and then crosses at the rear to the return passage 50 in the same tube.

Flow then extends through the cooperating notches to the flow tube 51, and passes rearward through passage 52 and then returns through passage 53 on the opposite side of its partitions.

Flow then extends up through the cooperating notches to flow tube 54, travelling longitudinally through its passage 55 and then returning through passage 56 on the opposite side of its partitions. Flow then extends through the cooperating notches to flow tube 57 and passes longitudinally through passage 58 then across at the rear, and returns through its passage 60 and then flows up through the cooperating notches into flow tube 61. In flow tube 61 material being heated passes longitudinally through passage 62 and then across at the rear, returning through passage 63 and through the cooperating notches to flow tube 64. In flow tube 64 flow takes place through passage 65 longitudinally, then across at the back, and then returns by passage 66 and then out through the notch to outlet port 67.

The stack as shown in Figure 6 is assembled against a front header 68 which is welded to the various fiow tubes to hold them in place and a close-01f end flow, providing openings 70 through which the header tubes pass. The rear is closed by a header 71 which similarly is welded to the flow tubes. Bleed holes are provided at 71 in the headers.

The topmost flow tubes at the two sides connect With channel elements 72 which are adapted to prevent flow between the inlet and the outlet and engage the headers at the two ends.

In the completed structure as shown in Figure 10, a jacket 73 completely surrounds the stack and the headers, the headers supporting the stack from the jacket and the channel elements 72 sealing between an inlet space 74 which surrounds all of the flow tubes below the channel elements 72, and an outlet space 75 above the channel elements 72.

The heater tubes pass through the end of the jacket at 76, being sealed in a fluid-tight manner at that point, and connect as by welding into a junction box 77 which is provided with an electrical conduit connection 78 and a suitably tight cover 80.

It will be evident that a heater can be removed at any time for maintenance by simply removing the cover plate 80 and loosening the electrical connections.

The heating medium completely surrounds the flow tubes inside the jacket and the flow tubes are only subjected to the small difierential pressure between the inlet and the outlet and not to the pressure between the fluid medium and the atmosphere which must merely be borne by the jacket. Thus very light construction can be used for the flow tubes.

A flanged inlet connection to the jacket is shown at 81 and an outlet housing is provided at 82 connecting with the outlet space 75 through a port 83 and having a flanged fitting 84.

The form of Figures 13 to illustrates a modified construction in which flow takes place longitudinally in one direction through each flow tube.

In this form there are twelve units arranged in three columns of four.

Each heater tube is provided with spacer lugs which extend out into engagement with the interior of rectangular flow tubes 36. The heater tubes are tack welded in the flow tube to position the spacer lugs, the

closed end 31 of the heater tube being spaced at 41 from the end of the flow tube as previously explained. In this form cross connections are produced alternately by notches 36 on the front end of one tube at one side and the rear end at another side. Thus inlet takes place at 87 to flow tube 38 and extends longitudinally to the back on all sides of the heater tube, where it cross connects through notches 36 to flow tube 90. Flow then occurs longitudinally to the front and cross connects through notches 86 at the front to flow tube 91, then flow extends rearwardly through flow tube 91 and at the rear cross connects through the notches to flow tube 92 through which flow takes place forwardly to cross connect at the front to flow tube 93. Flow occurs rearwardly in flow tube 93 and this cross connects through the notches at the rear to flow tube 94. Flow occurs forwardly through flow tube 94 and at the front it cross connects through the notches to flow tube 95. Flow extends rearwardly through flow tube 95 and cross connects through the notches at the rear to flow tube 96. Flow occurs forwardly through flow tube 96 and cross connects through the notches at the front to flow tube 97. At the rear of flow tube 97 flow cross connects through the notches upwardly as shown at 100 in Figure 15 to fiow tube 98. Flow extends forwardly in flow tube 98 and cross connects through the notches at the front to flow tube 101. Flow then occurs rearwardly through flow tube 101 and cross connects through the notches 102 at the rear to flow tube 103. From flow tube 103 connection is made at the front to outlet tube 104.

The flow tubes are suitably united as a package by bands 105 and the stack is closed at the front by header 68 around the heater tubes and at the rear by header 71.

The entire structure is surrounded by a jacket 106 and the stack is supported from the jacket by spacers 107. The jacket passes the heater tubes which are welded therein as shown in Figure 10.

Inlet is accomplished to the jacket by a flanged inlet connection 108 and outlet is accomplished by the tube 104 which is welded into an outlet fitting 82 as already described.

In this form the inlet medium being heated completely surrounds all sides of the stack, thus reducing the pressure differential to which the flow tubes are exposed.

In some cases it is preferable to obtain tighter sealing by partitions running longitudinally of the flow tubes and this is shown in various forms in Figures l6 to 21.

Considering first the forms of Figures 16 and 17, a circular flow tube 110 is closed at one end 111 and at the other end provided with an inlet connection 112 and an outlet connection 113 in diametral positions.

The heater tube 30 passes through one end, the end being sealed by welding in a closure 114. The heater tube passes to a suitable junction box 77'.

Fins 115 radiate from the heater tube, and at opposite positions two of the fins carry (as by welded attachment) resilient metallic partitions 116 which are desirably curved in shape and formed of sheet metal having spring properties, tending to extend out and seal against the inside of the flow tube.

At the rear end the heater tube is provided with radially extending lugs 117 which space it from the flow tube.

In the form of Figures 16 and 17 the fluid passes rear ward through passage 118 on one side of the partitions and then crosses through space 120 behind the heater tube and then returns forward through passage 121 on the other side of the partitions and thence out through the outlet 113.

In some cases it is desirable to obtain more longitudinal passages in a given flow tube and this is shown in Figures 18 to 20. Here there are four resilient partitions 116 extending out and the partitions are notched away at the respective ends to provide cross connections. Thus entry occurs through the inlet 112 and then fiow takes place rearwardly through passage 122, and at the rear cross connection occurs through port 123 to passage 124 through which fiow occurs forwardly. Then flow passes upward through port 125 and returns rearward through passage 126 and then it takes place across port 127 and occurs forwardly through passage 128 to outlet 113.

In this case the end closure 117 suitably extends fully out to the flow tube all around the interior and the lugs 117 are omitted.

In some cases it is preferable to omit the heat transfer fins which extend radially part of the distance between the heater tube and the flow tube in the heating passage and in this case resilient metallic partitions 130 are conveniently anchored directly to the heater tube and extend out into resilient engagement with the flow tube to make a seal.

It will be evident that since the same medium is present on both sides of the partitions it will be sufficient if the partitions generally restrict flow, as they of course do not have to accomplish a hermetic seal.

In view of my invention and disclosure, variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and I, therefore, claim all such insofar as they fall within the reasonable spirit and scope of my claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In an electric heater, a heater tube of circular cross section, an electric heater therein, a flow tube of rectangular cross section surrounding a single heater tube in spaced relation thereto, partition walls extending out from the heater tube at circumferentially spaced positions and engaging the flow tube in opposite corners of the cross section thereof, and dividing the space between the heater tube and the flow tube into a plurality of heating passages, and a cross connection between the passages at an end of the tubes.

2. In an electric heater, a heater tube, an electric heater therein, a flow tube surrounding a single heater tube in spaced relation thereto, resilient partition walls extending out from the heater tube at circumferentially spaced positions and resiliently engaging the flow tube and dividing the space between the heater tube and the flow tube into a plurality of heating passages, and a cross connection between the passages at an end of the tubes.

3. In an electric heater, a heater tube, an electric heater therein, a flow tube surrounding a single heater tube in spaced relation thereto, at least four resilient partition walls extending out from the heater tube at circumferentially spaced positions and resiliently engaging the flow tube and subdividing the space between the heater tube and the flow tube into a plurality of heating passages, and cross connections between the heating passages.

4. In an electric heater, a heater tube, an electric heater therein, a flow tube surrounding a single heater tube in spaced relation thereto, partition walls extending out from the heater tube at circumferentially spaced positions and engaging the flow tube and dividing the space between heater tube and the flow tube into a plurality of heating passages, fins extending out from the heater tube and terminating in the space between the heater tube and the flow tube and a cross connection between the passages at one end of the tubes.

5. In an electric heater, a stack comprising a plurality of units, each unit comprising a heater tube, an electric heater therein, a flow tube of rectangular cross section surrounding a single heater tube in spaced relation thereto, partition walls extending out from the heater tube at circumferentially spaced positions and engaging a flow tube and dividing the space between the heater tube and the flow tube into a plurality of heating passages, and a cross connection between the passages at one end of the tubes, the stack of units being arranged with the rectangular walls of the flow tubes adjoining one another, in combination with cross connections between the respective fiow tubes at the ends communicating between individual heating passages.

6. In an electric heater, a heater tube of circular cross section, an electric heater therein, a flow tube of rectangular cross section surrounding a single heater tube in spaced relation thereto, partition walls extending out from each heater tube at circumferentially spaced positions and engaging the fiow tube at the corners of the rectangular cross section and dividing the space between the heater tube and the flow tube into a plurality of heating passages, there being a plurality of combinations of heater tubes, partitions and flow tubes arranged together in a stack with the flat surfaces of the flow tubes in juxtaposition, there being cross connections between the flow tubes connecting alternate heating passages.

7. An electric heater according to claim 6, in combination with a jacket surrounding the stack of flow tubes and having respective inlet and outlet connections to the same.

8. An electric heater comprising circular heater tubes, an electric heater within each heater tube, flow tubes of rectangular cross section, one surrounding each individual heater tube, spacers connecting the heater tubes to the flow tubes and maintaining the flow tubes in spaced relation within the heater tubes, the units including the flow tubes, heater tubes and heaters being arranged side by side with the straight side of the flow tubes in juxtaposition to form a stack, cross connections between alternate ends of the flow tubes to connect the units in series, and passing fluid longitudinally through the respective flow tubes, and inlet and outlet connections to the stack.

9. An electric heater according to claim 8, in combination with a jacket surrounding the stack.

10. An electric heater according to claim 8, in combination with a jacket surrounding the stack, the fluid undergoing heating completely filling the space around the stack inside the jacket.

References Cited in the file of this patent UNITED STATES PATENTS 1,766,068 De Lannoy June 24, 1930 1,927,959 Soloos Sept. 26, 1933 2,710,908 Doniak June 14, 1955

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