US2179781A - Electric boiler - Google Patents

Description

Nov. 14, 1939.

E. M. FRANKEL El' Al.

ELECTRIC BOILER File'd March 23, 1936 5 Sheets-Sheet 1 `AT`TORNEY Nov. 14, 1939. E M FRANKEL E1- AL 2,179,781

ELECTRIC vBOILER Filed March 23, 1956 5 Sheets-Sheet 2 CONTROL C/RCU/T 440 V POWER HRH/w? Pda/Wr.

BY 5 g/M/ ATTORNEY Nov, 14,1939. E. M. FRANKEL ET AL 2,179,781

ELECTRIC BOILER Filed March 25. 1936 5 She`ets-Sheefl 5 ATTORNEY Nef. 14, 1939. E, M FRANKEL ET AL 2,179,781

ELECTRI C BO ILER Filed March 23, 1936 5 Sheets-Sheet 5 INVENTORS @WH/Q0 /Z HMA/Kn BYW ATTORNEY Patented Nov. 14, 1939 p l UNITED sTA'rl-:s

momo norma y Edward M. mum .namur rousk. New York,

N. Y., assignors toWeat Virginia Pulp Paper Company, New York, N. Y., a corporation' of Delaware animation Mann z3, 193s. sel-laiv No. 'losas 'IClnlmL Our present invention relates to electric boilers especially adapted for use with diphenyl or other substances Boiling at high temperature, although other liquids, especially those which are non-con-v ducting may be heated or evaporated therein irrespective of their boiling point. Boilers of this type are useful in heating systems depending upon the supply of a heating vapor as for ex- 4 ample that of diphenyl, the vapor of which is circulated through various heating spaces and then returned as liquid to the boiler. Because of the nature of such use it is highly important that the vapor be furnished at a uniform temperature as otherwise the benefit of applying heat by l5 the utmost importance that proper circulation be had of the liquid undergoing evaporation since otherwise decomposition of the liquid will take place and the resulting deposition of carbon upon the heating elements will cause them to burn out by further obstructing circulation and removal of heat. To this end it is essential that the heating elements be kept immersed in the liquid.

One of the principal objects of our invention is, therefore, to devise such a boiler which will provide an even and positive circulation of the liquid to be evaporated, and making for disengagement of thevapor at a multiplicity of points within the heating space without exposing the electric resistance elements.

A further object is to mount the electric resistance elements in a manner which will promote circulation and avoid decomposition of the liquid at the places where the elements are supported.

Still further objects of the invention and various advantages thereof will be apparent as the description proceeds and the novel features will be pointed out in the appended claims.

According to our preferred embodiment, we provide a preferably cylindrical vessel in which is immersed a heating unit of special construction. This unit consists of a plurality, preferably three, of upwardly directed heating compartments, each containing a coiled electric resistance unit, all said compartments communicating with one another by means of a preferably centrally disposed down-take passage, the vapor formed leaving the compartments between the heating element and the sides of the vessel. In the manner described, a positive circulation is obtained of the iluid downwardly through the central passage and radially and upwardly through the various compartments.

The invention will be best understood by reference to the following detailed description taken with the annexed drawings,.in which Figure 1 is a view in central vertical section of a preferred embodiment of the boiler;

Figure 2 is a view in vertical elevation of the entire heating unit;

means of a vapor is largely lost. Also it is of Figure 3 is a diagram of the control circuitsfor the heating elements;

Figure 4 is a view 4taken on section 4-4 of Figure l;

' Figure 5, 5a and 5b are three views showing des tails of the baiiiing and supporting members used;

Figure 6 is a view on an venlarged scale of a lead-in for the current supplied to the boiler;

Figure '7 is a view taken on section 1-1 of Figure 6;

Figure 8 is a plan view lof a control device for said boiler; v

Figure 9 is a view on a larger scale of certain operating mechanisms oi' said control device; and

Figure 10 is a fragmentary view seen to the 15 left of Figure 9.

Referring to Figure 1, lll denotes the shell of the boiler which has a cover Il bolted thereto by means of bolts (not shown) which pass through flanges I2 and i3, respectively, of the cover and m shell. The vapor produced iswithdrawn through outlet I5. The condensate is returned to the boiler through pipe I6 which is preferably provided with an L-shaped pipe Il within the boiler, it being noted that the horizontal portion of this pipe is provided with' perforations il to prevent sucking up of the liquid should a vacuum develop in the system exterior to the boiler. An outlet 20 is provided for gauge fittings while an opening 2| is had for the purpose of draining the boiler for inspection and repairs.

Coming now toa description of the heating unit, which is shown in Figures v1, 2, 3 and 4, the framework thereof is composed conveniently of so-called channel iron and consists of a plurality of outer uprights 23 and a plurality of inner uprights 24 (which form a central hollow core for the unit), said inner and outer'uprights being respectively arranged in radial alignment, corresponding bars being joined by radial cross pieces 25 at the top and bottom thereof. It will be noted that the uprights 23 and 24 provide receiving channels into which may be secured vertically disposed members 2 6 for holding the individual heating units as will be described. It will further be observed that the uprights 23 are higher than uprights 24 so as to make the top 2l concave andthe bottom 28 convex. The unit is desirably divided into preferably three compartments denoted B, C, D by means of parallel partitions 3l of generally conical shape. Each compartment so formed is adapted to contain a heating unit as will be described.

The individual heating units are formed by rst securing in place the lowermost layer of partitions 26, which it will be noted are provided with spirally arranged notches 36l in which the electrict resistance metal preferably in the vform of a ribbon is wound. When the rst layer is thus wound, a second layer of partitions 2 6 having w registering notches is laid in place whereupon a second spir'al is wound, it being desirable that the coils thus formed are oi' dish shape as shown. In the embodiment illustrated, two coils are provided for each campartment, each pair of coils preferably being of one length of ribbon having a double band in the portion joining the coils at their inner ends. It being understood, however, that this number of coils per compartment is not essential and that a diiferent number can be employed if desired.

'Ihe supporting members on partition 26 which nt into the recesses of the channel members as best shown in Figures 4 and 5 may be of any suitable material. An example of material we have found satisfactory is a composition of Portland cement and asbestos sold under the name Transite. The notches 86 in the partitions 26 while securely retaining the metal ribbon, which is disposed edgewise therein, yet permit circulation of the liquid being heated whereby danger of the umts burning out due to imperfect heat transfer is eliminated. The free circulation of the liquid is further promoted by perforating the partition 28 as at 31, etc.

It will be noted that by virtue of the upward displacement of the compartments and of the spirals, the vapor as it is formed will rise and pass to the outer periphery of the unit and thence upward between the shell I8 and the unit, the liquid evaporated being replaced by liquid descending the central core of the .unit. The upward pitch of the compartments and of the spirals thus gives rise to a positive circulation which keeps the heating umts bathed in liquid whereby danger of the resistance units burning out for lack of suiiicient heat transfer is completely overcome.

The three units shown are preferably connected for three phase operation, the diagram of such connections being shown in Figure 3, whereas the actual connections are shown in Figure 2. The common connection of the three coils is had by means of the conductor 48, Figure 2; the connection for compartment B is made by conductor 4| which is held in place' by nonelectrical connections 42 and 43 and also electrical connection 44. Similarly, compartment C is connected by conductor 45 having non-electrical connection 48 and electrical connection 41. Compartment D is served by conductor 48 which has electrical connection 49 and non-electrical connection 58.

Conductors 4|, 45 and 48 are provided with lead-in connections 52, 53, 54, Figure 4, preferably of special construction as will be hereinafter described.

'I'he electrical conductors to the three coils QB, C, D are provided with various switches desirably of the electro-magnetic type. Magnetic switch 51 shown in Figure 3 operates all three conductors 68, 59, 68. Magnetic switch 51 is operated by circuit 82 provided with a manually actuated switch 63 and an automatic switch responsive to any desired variable in the external system, e. g. temperature, pressure. Conductor 68 is additionally provided with magnetic switch 65 operated by circuit 68 having a manual switch 61 and an automatic switch 68. Similarly, conductor 59 has a magnetic switch 18, circuit 1|, manual switch 12. It is a familiar law governing three-phase circuits that when one leg of the system, as for example the conductor 68, is interrupted, the power input is thereby halved. We have therefore found that the automatic control of such leg of the three-phase system affords ariane).

a control of means of great accuracy. To accomplish this we provide for periodic cutting in and cutting out of the coil B, advantage being taken of the large heat capacity of the boiler and contents to absorb the heat contributed by coil B during the heating period and distribute it during the non-heating period whereby the temperature-time curve in respect to the vapor furnished by the boiler is for all practical purposes a straight line.

To accomplish this control we have devised the following apparatus: 15, Figure 8, denotes a panel board having an operating wheel 18 attached to a shaft 11 journaled in a bracket 18 attached to the rear of said panel. A shaft 88 is also mounted in the rear of the panel in iournals 8|, 82 attached to brackets 88, 84, respectively. Loosely mounted on said shaft but keyed thereto is a cylinder 85 having a non-truncated portion 86 and a portion 81 truncated as by an obliquely vdisposed plane. Cylinder 85 has an end flange 88, engaging which are ngers 89, 89 attached to a slidable rack 98, said rack engaging a gear 9| attached to the shaft 11. When'the wheel 16 is turned, the rack 90, and consequently the cylinder`85, is moved back or forth along the shaft 88. Shaft 80 is driven by an electric motor 92 of constant speed type through shaft 93 and gear reduction box 94. Journaled in a support 98 is a lever 91 having a follower roller 98 which is adapted to follow the curved surface of the roll 85. Attached to the end of lever 91 is link 99 which connects with a switch denoted generally by |88. Switch |88, which is of conventional design, consists of a lever |8I carrying a mercury cell |02, said lever |0| engaging a shield |83 carried by a toggle spring |04. In order further to control the movement of lever |8|, the same is attached to compression spring |85, the tension of which is regulated by a screw |86. 'I'he operation of the control device will now be evident. When the follower 98 is in contact with the curved surface of the cylinder 85, the switch |88 is in the position shown in Figure 9 in which the mercury cell connects the leads |88 and |89, thereby actuating control circuit 66 to cut in the coil B. When, however, the cut-out portion of the cylinder 85 comes in contact with the follower 98, the spring |85 acts to tilt the lever |8| downwardly past the dead center of the toggle to the off position. When the cylinder is moved to the right of Figure 8 by turning the wheel 18, a greater proportion of the curved surface is presented to the follower 98 and the coil B is cut in for a-longer time. Should it be desired to keep the coil cut in for an indefinite period, the cylinder 85 is moved until the non-truncated portion 86 is in contact with the follower 98. When the cylinder 85 is moved to the extreme left, Figure 8, the coil B will be cut out for an indefinite period.

Claims to the control arrangement .above described involving the three-phase circuit which were divided out of this application have been made in our co-pending application Serial No. 185,120 flied January 15, 1938.

In order to bring the current into the boiler, it has been found desirable to employ lead-ins of special construction. This is shown best in Figures 6 and 7 wherein a short length of pipe or nipple is fitted within an opening in the boiler shell I8 and is welded to the shell as indicated in Figure 6. The pipe carries an inner bushing ||2 which may also be welded in place. Bushing ||2 provides a shoulder against which the leadin proper is secured. The latter consists of a metallic core I I3 of conducting metal, as for example steel, having a threaded recess Ill at one end and a similar recess ||5 at the other to receive the electric conduits H1, IIB, respectively. Core ||3 is provided preferably with an exterior screw thread I9 around which is molded a suitable plastic, as for example sc-called mycalex (a compositioncontainingmica-lead borate glassand capable of withstanding moderately high temperatures) to form a bushing |2| around an enlarged portion of which may be provided a sleeve |22 which is preferably threaded thereto in order to give a large contact area with the bushing. The bushing |2| and sleeve |22 thus oder a shoulder |23 to contact with the shoulder of bushing I I2. One of said contacting shoulders is roughened or given a so-called phonograph finish so as to give a tight contact. Next to the mycalex bushing 2| there may be inserted an insulating bushing |25 of ordinary material such as soapstone or transite, the same being secured on the conductor ||8 by means of the nut |26. To maintain the lead-in tightly in place, the following construction may be provided: A ange |28 is secured to the pipe preferably by welding. Disposed opposite the flange |28 is a flange |29 having preferably welded thereto a gland |30. The flanges |28 and |29 are brought together by means of screw bolts |32. By taln'ng up on these bolts the bushing |2| is brought rmly home against the bushing ||2 and a tight joint results.

Reverting to the boiler, the improved arrangement of parts gives a highly compact construction enabling the resistor to be operated at a low emission rate but with a high total output of electrical energy; for example, in a space 30 inches in diameter and 36 inches high We have been able to wind about 200 feet of one and one half inch resistance ribbon of Suilicient resistance to permit direct connection to a three phase 440 volt power line. At 60 kilowatt output, the emission per square inch of heating surface per hour is only 10 watts thus making for an extremely long life of the ribbon.

While we have described our improved embodiments in considerable detail, it is understood that we have done so by way of example only and that various changes will occur to those skilled in the art without either departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. In an electric boiler adapted for heating and/or evaporation of high boiling substances, a boiler shell, a plurality of vertically spaced heating units therein, said units being adapted to be completely covered by the liquid to be evaporated and arranged to afford separate uptake and downtake passages for circulation of liquid, bailles between horizontal layers of units, said bailles extending from one to the other of said passages whereby circulation is directed both upwardly and laterally and the flow of liquid is upwardly of one of said passages and downwardly of the other, said bailles preventing the liquid or its vapor from coming into contact with more than one unit.

2. In an electric boiler adapted for evaporation of high boiling substances, a boiler shell, a plurality of vertically spaced annular heating units of dish shape therein, said units being adapted to be completely covered by the liquid sage for downward circulation of liquid and a passage between said units and the wall of the shell for upward circulation, bailles between said units, said baffles directing circulation both upwardly and laterally, and preventing the liquid or its vapor from coming into contact with more than one unit.

3. The boiler according to claim 1 in which said units are constituted by coils of bare electrical 4 resistance metal.

4. In an electric boiler adapted for evaporation of high boiling substances, a boiler shell, heating units therein, said units being adapted to be completely covered by the liquid to be evaporated and arranged to afford a passage for circulation of liquid between said units and the wall of said shell and a passage interiorly of said units,` and baliles above and below a horizontal layer of said units, said bailles extending from one to the other of said passages and directing circulation both upwardly and laterally whereby the flow of liquid is upwardly of one of said passages and downwardly of the other, and said bailles preventing the liquid or its vapor from coming into contact with more than one unit.

5. In an electric boiler adapted for evaporation of high boiling substances, a boiler shell, a plurality of vertically spaced heating units therein, said units being adapted to be completely covered by the liquid to be evaporated and arranged to provide a passage for upward circulation of liquid between said units and the wall of said shell and a passage for downward circulation interiorly of said units, bailles between horizontal layers of units, said baiiles directing circulation both upwardly and laterally, said baffles preventing the liquid or its vapor from coming into contact with more than one unit.

6. In an electric boiler adapted for heating and/or evaporation of high boiling substances, a boiler shell, a plurality of vertically spaced heating units therein, said units being adapted to be completely covered by the liquid to be evaporated and arranged to afford separate uptake and downtake passages for circulation of lliquid, bailles between said units, said bailles extending from one to the other of said passages and whereby circulation is directed both upwardly and laterally and the flow of liquid is upwardly of one of said passages and downwardly of the other, said heating units having an emission rate per square inch on the order of ten watts.

7. In an electric boiler adapted for heating and/or evaporation of high boiling substances, a boiler shell, a plurality of vertically spaced heat ing units therein, said units being adapted to be completely covered by the liquid to be evaporated and arranged to afford separate uptake and downtake passages for circulation of liquid, baffles between horizontal layers of units, said bailles being inclined upwardly from and extending from one to the other of said passages and directing circulation both upwardly and laterally whereby the flow of liquid is upwardly of one of said passages and downwardly of the other, said battles preventing the liquid or its vapor from coming into contact with more than 70 one unit.

EDWARD M. FRANKEIL. ARTHUR POLLAK.

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