US1787801A - Electrically-heated container - Google Patents

Description

Jan 6, 1931.

Filed Sept. 22, 192 2 Sheets-Sheet 1 Fz' .1. 15 v 5] 11 7 5 10 5 7 ENVENTOFZ Mal 0 M 7AM m -w Jan 6, 1931.

H. o. SWOBODA ETAL ELECTRICALLY HEATED CONTAINER Filed Sept. 22, 192' 2 Sheets-Sheet 2 I l l i INVENTOR i ate'nted diam 6, 193i UNETED STATES ra'raar orsics HANS O. SWOBODA, F EDGEWOOD BORGUGH, ALLEGHENY COUNTY, AND WILLIAM F. METZGEB, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNORS TO B. 0. SWDBODA, INC., 013 PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA ELECTRICALLY-HEATED CONTAINER Application filed September 22,1927. Serial No. 221,222.

Our invention relates to electric heaters and particularly to a method and apparatus for heating containers of non-conducting material by utilizing commercial shapes of iron and steel as well as other metals and alloys for the electric heater.

in heating containers, such as boilers, tanks, vats and the like, when the temperature of a mass of material is to be maintained substanm tiaily uniform and must not be materially exceeded due to the danger of decomposing said material, the selection of the proper type of electric heater presents considerable dilliculty. It is also important to reduce the time that must elapse during the interval of dissemination of the thermal energy from the electric heater throughout the entire mass of material to a minimum. 7

In the past, gas, oil, steam and electricity as have been used for heating such containers. In the caseof steam coils, in order to keep the temperature of the same at or above the temperature desired in the material, it has been necessary to either provide a highenough,

2a steam pressure to insure that the steam traversing them is maintained above the predetermine temperature or super-heat the steam to permit a transfer of heat to the contents of the tank. Both the high enough steam pressure as well as the super-heating of the steam in the plants where such containers are used are very inconvenient to obtain, and have to r be provided especially for the container, causing thereby considerable expense. As an example, a heating coil for maintainin a nec- 'essaryfltemper'ature of 450 F. throug out its lengthfinay require an initial steam temperature of900 F.

Electric heaters which have been used for '40 this purpose usually consist of special alloys,

either pipe, tubing, angles, channels, rods, bars, grids or any other commercial shape of iron, steel, nickel or well-known alloys with a large cross-sectional. area. This results in extremely rugged heaters providing a large contact surface with the material, and permits a very low temperature gradient, so that the said pipe, tubing, etc., can be placed directly in engagement with the material without any further protection and insulation. It can readily be seen that the replacement of the expensive nickel chromium allo by a cheap commercial shape ofi iron or the like, and the omission of any electric insulation as well as any means to protect the material 5 against excessive heat, result in an equipment not only very inexpensive with regard to first cost, but also with regard to repairs and re newals. In reality, repairs and renewals are practically eliminated by the rugged construction and by the fact that repairs, if they should become necessary, can be made by the employees of the shop where the container is installed without the purchase of new expensive heating units.

Where pipe or tubing is utilized for the electric heater, it is possible to heat and cool the material by the same pipes. For heating, electric current is caused to traverse them, while for cooling, a cooling medium such as air or water is circulated therethrough. This construction eliminates, in a great many processes, the necessity for separate heating and cooling devices.

The electric heater for a container is usual- 5 1y made of several sections and each section is sub-divided into a number of heating units. Each heating unit is preferably composed. of a number of straight lengths of the resistor material connected by return bends or no equivalent connections. Special care has been exercised that all pipes and their fittings when exposed to the vibrations of alternating current are self-locking, so that they cannot come apart. This form of unit has been selected, because it is non-inductive and easily constructed. However, heaters in helical or any other form may be employed, so long as they are non-inductive and can be placed into the container. Each unit may rately, eit

be connected to an adjacent unit by a union or other form of coupling. If a number of these units are connected as a section, the ends of said sections are provided with electrical terminals. These terminals which extend above the surface of the material to be heated, are usually made of larger cross-sectional area than the resistor material itself to prevent the generation of heat in the same.

The heater units are supported by insulators carried by angle or channel irons about the walls of the container but not fastened to the same. Of course, they may also be installed in the center of the container in case this should become desirable in specific cases. Theupper ends of the units are secured in place by rods slidably movable through insulating bushings disposed 1n one of the iron shapes. These angles and channel irons are fastened to a common support in such a manner that the entire electric heater can be removed from the container for clean: ing and repairing without emptying said container.

The heater sections are connected through the terminals to a source of electric energy. Usually, they are arranged in several groups; each group being preferably controlled sepaier manually or automatically, for maintaining a predetermined uniform temperature. Different degrees of heat may be obtained in each one of the sections by supplying either different voltages from a transformer, or using a Y-delta switch, or both.

In the foregoing, the invention has been described for containers with non-conducting materials. However, it can also be applied to containers with materials which are conductors of electricity. In such cases, the heaters have to be separated from the material by a shield, and the space between the shield'and the container wall has to be filled with an insulating fluid such as oil.

The accompanying drawings present a container for the heating of non-conducting material such as asphaltum. It is heated by a heater comprising three sections, each section including a plurality of heating units disposed around the sides of the container. They are selectively connected to an autotransformer with a Y-delta switch as described above.

The equipment shown in the drawings was selected in order to be able to show specific details of construction. It is, however, understood that any other design of container or electric heater as described in the foregoing is claimed as our invention.

In the drawings Fig. 1 is a sectional elevation of a container embodying our invention.

Fig. 2 is a diagrammatical view of the electric heater.

Fig. 3 is a plan view of the heater unit, the upper guide being removed.

Fig. 4:.is an elevational view thereof.

Fig. 5 is a detail view, on an enlarged scale, and partly in section, showing the method of supporting and insulating the heater units.

Referring to Fig. 1, the container 1 is constituted by a wall 2, a jacket 3, a layer 4 of heat insulating material and a cover 5. The insulating material at is cut away near the top for defining space 6, in which electrical conductors 7 are disposed for connection to the heating units as hereinafter more fully described.

Conduits 8 extend through the jacket 3 into the space (S, for connection to an external sourceof electromotive force.

A steel framework or slieleton 9 is sus pended from wall 2 by a collar or flange 14). Eyebolts 11 are provided in the collar 10 for enabling the framework 9 and the supported heater units 12 to be bodily withdrawn from the container. The framework 9 comprises a shield 15 connected to flange 10 by angle irons 16 and which extends downwardly into the container a sufficient distance for protecting the upper heater units 12 from contact with the material lowered into the container. If desired, the shield 15 may be made solid without circulation holes and extend the entire length of the container for protecting the heater units from engagement with the liquid within the container. 1f the liquid to be heated is an electrical conductor, the space between the shield and wall may be filled with an insulating fluid such as oil. Where the nature of the material in the container permits of its direct engagement with the heater units, it is only necessary to extend the shield 15 down far enough to insure that objects lowered into the container shall be in alignment with the axis thereof. This feature is important where large pieces of material are lowered into the container.

Where the shield 15 extends downwardly into the container but a short distance, guard strips 17 are welded or riveted thereto. The guard strips 17 extend downwardly substantially the entire length of the container for supporting and protecting the heaterunits 12. The spaces between the guard strips permit the free circulation of the material in the container into engagement with the heater units 12. Iron shapes 18-19, 2021, 22 and 23 are supported on the outer surface of the shield 15 and guard strips 17 for supporting, guiding and separating the heater units into three distinct sections-A, l5 and C respectively. Iron shape 24 serves to guide terminals 32.

Referring to Figs. 3 to 5 inclusive, each of the heater units 12 comprises a plurality of lengths of heater pipe 2:3,connectcd at the upper and lower ends by return bends 26 and 27, respectively. The number of pipes 25 in each heater unit may be varied as desired. Insulators 28 are mounted on the pipes for preventing them from coming into engagement with each other in case of sired.

The outer pipes 25 in each section term1-' nate in a terminal pipe of larger cross sectional area than the pipe sections themselves, in order to prevent the vterminals from being heated to the same degree as are the pipes 25. Each terminal pipe 30 is surmounted by a T 31 opposite to space 6. As the heating sections A, B and C are disposed at different levels in the container 1, the terminal pipes 30 are of different lengths in accordance with the position of the heating sections controlled by them.

The top of the T 31 is provided with an electrical terminal 32 for connection to electrical conductors. As shown in Fig. 3, special care has been exercised that these terminals do not exceed in diameter the associated pipe 25 with its fittings 27 and 31, avoiding thereby any waste of space incident to the use of most electrical terminals. A pipe 34 is connected to the T through a set of insulating flanges and washers 35 and 36 in order that the pipe 34 shall not be charged with electric current while the pipes 25 are used as electric heaters. By this arrangement, the pipes 25 serve as heaters when elec trically ener ized, and as cooling coils when the cooling uid is passed through.

Each of the return bends 27 is deposited in a groove 37, in an insulating block 38. The insulating block may be of slate, porcelain, or any other suitable electrical insulating material. The blocks 38 are supported by the. lower iron shapes 18, 20 and 22 for the several heating sections A, B and C, respectively. The bends 26 are each provided with an upper projecting lu 39 that extends through an insulated bus ing 40, carried by one of the iron shapes 19, 21 or 23. By this construction, expansion and contraction of the individual pipes 25 causes the lugs 39 to move in the bushings 40 as shown in dotted line in Fig. 4. The terminal pipes 30 are provided with insulating bushings 41 for preventing electrical contactwith the iron shapes through which they extend.

The heater units are primarily supported by the iron shapes 18, 20 and 22. The upper iron shapes 19, 21 and 23 serve primarily to guide and space the heater units, permitting their expansion and contraction at the same time. While we have shown pipes 25 as the resistors in the present construction, it is to be understood that other commercial forms as bars, rods and the like may be used for the heater units. However, when such other forms are employed, it is impossible to use them for cooling the material. It is also to be understood that for certain purposes it may be desirable to mount the heater units in horizontal position or employ spiral shaped units instead. The method herein disclosed of subjecting spaced points in diiferent portions of a body of material to a substantially uniform heat transfer per unit of heating area is disclosed and claimed in our co-pending application Serial No. 483,008 filed September 19, 1930.

We claim 1. The combination with a container, of a plurality of heating sections disposed circumferentially thereof with the sections axially aligned, each of the heating sections constitnting a plurality of lengths of pipe, and means for connecting the pipes to a source of electromotive force, said lengths of pipe having means secured thereto and projecting therefrom for both guiding and positioning the pipe lengths.

2. The combination with a container, of a plurality of heating sections disposed circumferentially thereof, with the sections axially aligned, each of the heating sections constituting a plurality of lengths of pipe and means for connecting the pipes to a source of fluid, said lengths of pipe having means secured thereto and projecting therefrom for both guiding and positioning the pipe lengths.

3; The combination witha container, of a plurality of heating sections dispo'ed circumferentially thereof, with the sectionsaxially aligned, each or the heating sections con- ,stltuting a. plurality of lengths of pipe, and ,means for selectively connecting the pipes to a source of electrol'notive force or to a source of fluid, said lengths of pipe having means secured thereto and projecting therefrom for both guiding and positioning the pipe lengths.

4. The combination with a container, of a temperature control system comprising a plurality of circumferentially arranged heating sections providing an unobstructed space within the container and within the sections, each of said sections comprising a plurality of pipe members, and means for controlling the temperature of the several sections, said pipe members having positioning and guiding means directly carried thereby.

5. In an electricalheating unit, a plurality of heating elements constituted by exposed metallic members of commercial form and a terminal member of exposed metallic material having a cross sectional area in excefis of the cross sectional area of the heating elements, whereby the temperature of the ter-- metallic support therefor, comprising a lug, a

bracing member having an opening therein, said lug fitting loosely within said opening, and an electrical insulator separating the lug and bracing member while permitting longitudinal movement of the lug within the opening.

8. The combination with a container, of a heating unit disposed therein to provide a substantially unobstructed space within and surrounded by the unit, and guiding means cooperating with such unit intermediate the same and said space and effective 'for guiding material into the space within the container without injury to said unit.

9. The combination with a container, of a heating unit disposed therein to provide a substantially unobstructed space within and surrounded by the unit, and guiding means cooperating with such unit intermediate the same and said space and eiiective for guiding material into the space within the container without injury to said unit, said unit comprising a plurality of standard commercial shapes connected inend to end relationship.

10. The combination with a container, of a heating unit disposed therein to provide a substantially unobstructed space within and surrounded by the unit, and guiding means cooperating with such unit intermediate the same and said space and eflective 'for guiding material into the space Within the container without injury to said unit, said unit comprising a plurality of standard pipe fittings and lengths connected in end to end relationship. v

11. The combination with a container, of a heating unit disposed therein to provide a substantially unobstructed space within and surrounded by the unit, andguiding means cooperating with such unit intermediate the same and said space and effective for guiding material into the space within-the container without injury to said unit, said unit comprising a plurality of standard pipe fittings and lengths connected in end to end relationship, there being means carried by the pipe lengths for preventing contact between adjacent lengths.

12. The combination with a. container adapted to receive material to be treated, of a plurality of heating units positioned therein in groups adapted to actually contact with the material to be treated, each of said groups lying in a definite zone substantially normal to one of the axes of the container, and means for circulating a cooling medium through such units.

13. The combination with a container adapted to receive material to be treated, of a plurality of heating units positioned therein in groups adapted to actually contact with the material to be treated, each of said groups lying in a definite zone substantially normal to one of the axes of the container with adjacent zones in predetermined spaced relationship and means for circulating a cooling medium through such units.

14. The combination with a container adapted to receive material to be treated, of a plurality of heating units positioned therein in groups spaced axially of the container, each of said groups lying in a definite zone substantially normal to the axis of the container along which the groups are spaced, and means for individually controlling the temperature conditions in any of said zones, and connections enabling the bodily removal of all of said heating units.

15. The combination with a container having material therein to be heated, of an electrical heating unit submerged directly in said material and in direct contact therewith, said unit providing a substantially unobstructed space within the same and within the container, and connections enabling the bodily removal of said heating unit.

16. The combination with a container, of a heating unit comprising a plurality of hollow pipe sections secured in end to end relationship, said. container and pipe sections being constructed for the direct reception of and contact with the material to be heated, and connections enabling the bodily removal of said heating unit.

17. The combination with a container, of a heating unit removably supported therein and comprising a plurality of pipe lengths interconnected to provide a continuous flow path for the electric current, said container eing constructed for the reception of fluid material to be heated, either prior to or subsequently to the insertion of the heating unit in position therein, and connections for circulating a cooling medium through said pipe lengths.

18. The combination with a container, of a heating unit comprising a plurality of standard commercial shapes secured in end to end relationship, said container being constructed for the direct reception of the material to be heated, each of said heating units providing a plurality of separate heating zones, and means for controlling the temperature conditions at will in any of said zones, and conthrough said pipe lengths.

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nections for circulating a cooling medium 19. The combination with a container, of a heating unit removably supported therein and comprising a plurality of pipe lengths interconnected to provide a continuous flow path for the electric current, said container being constructed for the reception of fluid material to be heated, either prior to or subsequently to the insertion of the heating unit in position therein, each of said heating units providing a plurality of separate heating zones, and means for controlllng the temperature conditions at will in any of said zones. a

20. A heating unit, comprising a plurality of snbstantiaily vertically disposed conductors with adjacent conductors connected by U-shaped portions, insulating means engaging and supporting the tower U-shaped portions, and guiding and insulating means cooperating with the upper U shaped portions. V

21. A heating unit, comprising a plurality of substantially vertically disposed conductors with adjacent conductors connected by u shaped portions, insulating means engaging and supporting the lower U-shaped portions, and guiding and insuiating means cooperating with the upper iii-shaped portions, there being means intermediate the ends of said conductors for maintaining adjacent conductors out of e'iectrical contact one with the other.

22. A heating unit, comprising a plnraiity of snbstantiaily yerticaliy disposed condoctors with ad iacent conductors connected by U-shaped portions, inmiating means on gaging and wppotting the ion'er iii-shaped portions. and gniding and insniatingmeans cooperating with the upper thshaned portions, there being" means intermediate the. ends of said'condu-ctors to maintaining adjacent conductors out of eiectricai contact one with the other. said last mentioned means being carried by the conductors themselves.

Q3. in apparatus for electricaiiy treating bodies of material, means for confininethe materiai and maintaining it substantiaiiy quiescent, means for snh iect'ing said substantialiy quiescent body to iocaliaed hea ing at a pinrahty of spaced points in difierent portions of the body with a substentiaii v nniiorm heat transfer per unit oi heating area, and means "for subseouentiy subjecting the same points to iocalized cooling.

Q4. eipparatus for heating inateriai, 00m" prising means for confining a body oi" material to be heated, and means for alternately heating the material in a pln'raiity of spaced localised zones throughout the body thereoi with a snbstantiaiiy uniform heat transfer per unit heating zone, and thereafter cooling the some tones.

@5, for heating materiai,

means for confinin a body of material to be heated, means or heating the material in a plurality of spaced localized zones throughout the body thereof, and means for subsequently subjecting said zones to a cooling temperature.

- In testimony set our hands.

HANS O. SWOBODA. WILLIAM F. METZGER.

whereof we have hereunto

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