US2481760A - Vapor superheating system and apparatus - Google Patents

Description

Sept. 13, 1949. L. .1. LEHER VAPOR SUPERHEATING SYSTEM AND APPARATUS Filed Nov. 15. 1945 6 Sheets-Sheet l INVEI/TOR. '5 [Le/Jar fa bz4 x .286,

fi/Torneys Sept;o 133 1949., a... J. LEHER VAPOR SUPERHEATING SYSTEM AND APPARATUS 6 Sheets-Sheet 2 Filed NOV. 13, 1945 1 lllllllll '1 x Sept. 13, 1949. 1.. J. LEHER 2,431,750

VAPOR SUPERHEATING SYSTEM AND APPARATUS Filed Nov. 13, 1945 s Sheets-Sheet W INVENTOR.

34% x gkckb 9/70 F1"? eyJ Sept. 13, 1949. 2.. J. LEHER VAPOR SUPERHEATING SYSTEM AND APPARATUS 6 Sheets-Sheet 4 Filed Nov. 15, 1945 fiff rn eyu:

Sept. 13, 1949. L. J. LEHER VAPOR SUPERHEATING SYSTEM AND APPARATUS 6 Sheets-Sheet 5 Filed Nev. 15, 1945 I III lllll R E H E L Iw L VAPOR SUPERHEATING SYSTEM AND APPARATUS 6 Sheets-Sheet 6 Filed Nov. 13, 1945 INVENTOR. [cu/3 lie/7e Patented Sept. 13, 1949 VAPOR SUPERHEATING SYSTEM AND APPARATUS Louis J. Leher, New York, N. Y., assignor to Steam Torch Corporation, New York, N. Y.

Application November 13, 1945, Serial No. 628,108

4 Claims. 1

This invention relates to vapor generating devices, such as steam generators, and more particularly to methods and arrangements for superheating steam or other vapors.

Among the objects of the invention are novel methods and arrangements for supplying superheated steam or other vapor by conducting the steam or vapor over exposed electrically energized resistive conductors located in a duct space which is isolated from the vapor generating space, so as to cause the vapor passing over the exposed electrically heated conductors to absorb a maximum of heat energy radiated directly from the resistive conductors and to become highly superheated.

An important specific object of the invention is to provide a simple, fast, clean and inexpensive method of removing old paint or other coating by means of highly superheated steam.

The foregoing and other objects of the invention will be best understood from the following description of exemplifications thereof, reference being had to the accompanying drawings, wherein Fig. 1 is a finish removing equipment of the invention utilizing live steam from an available source;

Figs. 2 and 3 are auxiliary electric superheating devices to prevent condensation in very long steam hoses;

Figs. 4-6 are a cross-sectional side view and top and front plane views, respectively, of a pistollike superheating unit;

Fig. '7 is a rear elevational view of a wired multihole ceramic superheater body of Figs. 4-6;

Figs. 814 are views of interchangeable accessories of the finish remover;

Figs. and 16 are side and bottom views of a superheating unit having the shape of a combination steel brush and scraper;

Figs. 1'7 and 18 are cross-sectional side and rear views of a finish remover, which generates its own steam, the appliance being filled with water before operation;

Figs. 19 and 20 are similar sectional views of a vaporizing and superheating unit of the flash boiler type being used in connection with a water hose;

Fig. 21 is a ceramic vaporizing member of the water-fed steam pistols of Figs. 17 and 19, the sectional view being developed into a. plane to show the vapor canals leading from the outermost parts of the rectangular member to its inner canals containing the heating wire;

ganals of the ceramic vaporizing member of Fig.

Figs. 23 and 25 are cross-sectional front and rear views of the aforementioned member;

Figs. 24 and 26 are front and rear elevational views of said member after being closed by end plates;

Fig. 27 shows diagrammatically the water and steam flow through a flash-type generator used in the construction of Fig. 19;

Figs. 28 and 29 are fragmentary cross-sectional views of two different designs of vaporizing canals forming the perimetric part of said generator as indicated in Fig. 27;

Figs. 30 and 31 are fragmentary front and side views of another modification of the flash boiler construction of Fig. 19; and

Fig. 32 is a schematic outline of a power plant using a stationary electric radiant superheater of the invention.

The problem of removing paint in a simple.

clean way has long confronted the art. Blow torches are unfit for good-quality refinishing work. They are useful only on wide open surfaces where the character of the subsequent finish is of relatively small importance. Burned wood surfaces can'be hidden with cover paint, but not with translucent coatings. To burn off paint properly requires experience and is burdensome. Due to fire hazards and the fear of explosion, many people shy away from the use of blow torches for paint removing. Inside jobs require cleaning and sandpapering of the surface before repainting. When applied to windowsills, etc., blow torches are liable to crack the glass or do other damage.

Chemical paint removers have likewise many drawbacks. They too are a fire danger because of their highly volatile, inflammable character. The noxious exhalations, which they disseminate, are detrimental in small, badly ventilated Workshops, especially in winter, when the windows are closed. Chemical removers cause mush and they are corrosive. They easily spoil adjacent surfaces by running thereover or by droppings during application, scraping or brushing off. For this reason chemical removers can be used only in workshops provided with the necessary facilities. Various precautions must be taken. Every object that has been treated by a chemical remover must be washed off with naphtha-benzene, alcohol, lacquer thinner, soap water or sub-turps before it can be refinished. The thoroughly soaked material must then be allowed to dry overnight. Then it must be sandpapered down, because, if the re- Fig. 22 is a sectional top view of the inner mover has not already raised the grain of the wood, the subsequent washing with a neutralizing agent has surely made it stand up."

superheated steam oi 500-700 F., when being applied to a finished surface, instantly softens or melts the coating so that same can easily be removed with a scraper, steel brush, putty knife, spattle or the like. The highly superheated steam, which is only water vapor in gaseous condition, softens or melts any kind of paint, varnish, shellac, lacquer or enamel without doing injury to the surface underneath. If the object consists of a wood such as mahogany, it even cleans out the pores of the wood. Wherever a scraper can be used, the finish is quickly taken ofl strip by strip, leaving a clean surface without any remnants of the coating.

After the finish removing is completed, neither mechanical nor chemical treatment of the object is necessary. Refinishing can proceed immediately. The elimination of a final cleaning, washing off with a neutralizer, drying and sandpapering down, amounts to a great saving in time, labor and expense. Besides, superheated steam of adequate volume and superheat degree takes ofi any number of coats in one operation. It also takes off gold or aluminum finish, which are very hard to remove by chemicals.

The removed finish is dry and brittle and readily falls or breaks oil the brush or scraper. No care has to be exercised where the shavings or brushings may drop. They are dry, hard, without corrosive action, and are simply swept up after the completed operation. This enables a clean and quick job on any kind of surface. It makes paint removing on built-in vertical surfaces or the brushing out of grooves and carvings remarkably easy.

The equipment includes a variety of interchangeable nozzles, scrapers and wire brushes, which will fit any contingency that might arise in connection with diihcult removing jobs. For instance, it is impossible at present to refinish a radiator on location, because, for one reason, the commercially available steel brushes do not permit access to the narrow inner parts of these fixtures. The paint in such places, after treatment by blow torch or chemical remover, must now be removed by sand blowers in the factory. The finish remover of the invention will do such work on the spot. The steam for the superheating pistol may be supplied by the radiator, whose paint is to be removed. All it needs is to couple the steam hose to the outlet normally reserved for the vent valve of the radiator.

The capacity of instantly transforming ordinary low-pressure steam into a high-temperature gas is an outstanding feature of the portable superheating devices of the invention. They may be connected to any existing steam heating system.

Electrically superheated steam is easily controllable as to temperature and humidity best suited for the type of finish to be removed, the nature of the object and the working speed of the operator. The new technique is inherently a quick operation as the coating, promptly disintegrated by the superheated steam, must be removed while in a soft or melted condition.

To accomplish this in an efficient manner, special designs and working arrangements were devised, the essential features of which will be explained on hand of Figs. 1-31. similar reference characters refer to similar parts throughout these drawings.

According to the invention, the principles of electric superheating arrangements described above in connection with portable devices are also applied to steam generating systems in industrial establishments, one exemplification being shown in the diagrammatic view of Fig. 32.

Hand portable electric superheaters for paint removing Referring to Fig. l, a vapor generator 4| and an electric wall outlet 49 feed by means of steam hose 43 and cord 50 the superheating unit 40. The steam hose is coupled as at 42 and 44. The cord 50 may lead through the long, strong handle 5i to the resistance wires enclosed in the superheater 46. The electricity and steam supply are regulated by a multiheat switch 52 and a blow and throttling valve 45, respectively. The superheated steam is discharged through an exchangeable nozzle or vapor spreader 48, under which an exchangeable scraper 54 is firmly held by a clamp 53 to pick up the melted paint 55 during the process of steam application. It will be noted that the apparatus, when used with a scraper, is held at a slight angle.

Vapor generator 4| may be any available source of steam: a heating boiler. a radiator, steam pipe, pressure cooker, canner, etc. The equipment may be provided with a special hand portable evaporator, which, because of the very low pressure requirement, may be of the simplest design. It may be heated by gas, kerosene, alcohol or electricity. Such a miniature boiler, preferably of the electric type, can be placed near the working locality, can be suspended from a ladder, etc. For larger removing jobs a vapor generator on wheels, with pulleys, etc., can be used, which supplies a whole crew of operators with low-pressure steam. The portable boiler can be fully automatic and fed by a hose from a nearby city water line.

Steam hose 43 may be a rubber or flexible metal hose. A length of 6-8 feet will do for the average equipment. Rubber steam hoses are cheap and withstand temperatures up to 450-600 F. However, for the purpose in question, due to the great effectiveness of superheater 45, the hose is normally required to carry only vapor of low-pressure saturation temperature.

To secure reasonable dryness of the steam and to prevent possible condensation water from striking the exposed electric radiators inside the superheater, means such as described below may be provided.

The steam ,hose, especially when made of metal, will "be heavily insulated (5!, Fig. 3). At the beginning of operation, before steam is admitted into the superheating unit, the condensate formed during the initial heating of the hose, will be released through the blow valve 45. The steam inlet fixture 10 can be so designed as to block the entrance of water. Or the housing Ii of the steam pistol may provide some space for the entrapment and immediate evaporation of condensate. Or the steam will be conducted into a plurality of fine canals passing through the outermost parts of the superheater 4B, which arrangement will free the steam from possible water contents before it enters the conduits enclosing the exposed resistors. Besides, on account of the elevated position of the appliance with respect to the vapor generator, condensate has a tendency to gravitate into the low-pressure steam hose.

The steam flow in a hose of considerable length can be kept dry or adequately superheated by an intermediate superheater 56 such as shown in Fig. 3. The unit, which is coupled as at 51 and 58 between two hose extensions 43, may simply consist of a. heat insulated (59), metalclad double hole ceramic tubing 60 enclosing an exposed radiation element SI of nominal wattage. The element is energized by plug and socket contact 62, the cord 50 following closely the steam hose 43.

Another application of the invention, as exemplified in Figs. 1 and 2, is to provide a specially built steam hose, which through its whole length encloses exposed electric heating wire. The wire is secured at both ends of the hose (at one end to a socket for plug connection with the nearest wall outlet) and may be spaced and insulated by ceramic or other suitable means, which preserve the flexibility of the hose. Fig. 2 shows part of a rubber hose containing a wire 53, which is insulated by ceramic beads 64.

The valve 45, shown in Fig. 1, is a separate unit attached to the threaded pistol inlet 10 and may be a three-way valve to enable the operator not only to blow oif or throttle down the steam supply but to shut it on altogether without referring to the outlet of the vapor generator.

Figs. 47 show the basic design of a superheating unit being employed in connection with an available source of steam, according to Fig. l. Distinctive is the fiat, lengthy shape, the sturdy construction and ease of assembly of the implement. Its main part is the mutihole ceramic body of the superheater :36, contained in a strong metallic housing 86, which for wiring purposes can easily be taken apart by removing the screws 6?, 61a. To the rear part of the housing 56 is mounted thehandle and the multiheat switch 52 (by means of screws 51, $8). The clamp 53, whose operation is self-evident, is mounted to the front part of the housing by means of screws 69.

In the particular design of Figs. 4-6 the rectangular ceramic body of the superheater 46 has three rows of circular canals 7|, through which three separate resistance wires l'2l4'are threaded as indicated in Figs. 5-7. The loops of the wire coils are of triangular shape to permit a maximum of radiation inside the circular superheater canals. Connection with. the threeheat switch 52 and cord is effected as shown in Figs. 4 and 5. The wire ends are insulated by asbestos sleeves, beads or similar means.

According to Fig. 4, the steam delivered by hose d3 enters the device at 70 and circulates in a double counterfiow past the three exposed radiation coils l4, i2, it! inside the ceramic superheater t6 before it leaves through nozzle til. This arrangementachieves eflicient energy transfer and heat regulation. By'switching in only one,

or two or all three elements (first the inner wire coil i2, then coils l2, l3 and finally also the hot-- tom coil 14), the properties of the emerging steam in which case the nozzle 48 will'have the shape of a vapor spreader. The superheater canals may be square, in which case circular helical wire coils will be used. There may be only one row of canals, which can be so wired as to enable variable heat control of the steam passing ,there through. Of course, counterflow circulation of the steam within the superheating unit enables either a shorter design of said unit or a reduction of the operating temperature of the resistors, as the steam flows over a much larger area of exposed wire surface before it is discharged through the nozzle. I

There is also the possibility of employing a rodtype radiation element, the steam being conducted through an electrically energized multihole structure made from graphite, silicon carbide or similar non-metallic resistor material and appropriately mounted into the housing 66 of the superheating unit.

The outside. of housing 66 may be heat insulated.

Figs. 8-11 are indicative of the assortment of nozzles, scrapers and wire brushes planned to be part of the equipment. The nozzles, which will be of varying width, length and outlet design to fit different brushes and scrapers, may simply be attached to the protruding front end 75 of the superheater dd. (Figs. 4, 5.) It is a characteristic of the low-pressure superheating appliance that joints and connections do not have to be very tight to serve their purpose. The twoedged scrapers, one specimen being shown in Fig. 9, and the wire brushes, which have one or more slots to permit passage of the steam therethrough (side and top views of Figs. 10, 11), are firmly secured by the grip of clamp 53. Said tools, like the nozzles, are readily exchangeable. Stiff steel and soft brass wire brushes will be provided. Brushes of the type shown in Figs. l2-14 are secured by both the superheater front end 15 and theclamp 53.

Figs. l5 and 16 represent the tentative design of a superheating unit having the shape of a combination steel brush and scraper. The brush 76 and scraper 54 form a slidable unit held together by brackets F1 and guided by a resilient extension 78 resting in arecess 19 of the handle 5!. Extension i8 can be moved to a locked forward or backward position by means of knob 80. the protrusion 3| of which fits into either hole at or 83 of the handle recess 19. The superheating unit is constructed for vapor release through outlets in its top and bottom wall.

When the steel brush is in a backward position as shown in Fig. 15, the superheated steam will be discharged through the slots 85 of ihe steel brush. In said position the slots 85 communicate with the bottom outlets 84 of the uperheating unit, while its top outlet 86 is closed by the base 88 of the U-shaped scraper 54.

By turning the implement around and fixing knob in a forward position, the scraper comes into use as shown in Fig. 16. All the low-pressure steam escapes now through the slot 87, whichis in communication with the outlet 86 of the superheating unit, whose bottom outlets 84 are closed by the top surface of the brush.

Alternate steam release either through the brush or in front of the scraper may be also achieved by means of a valve, in which case the construction of the appliance is modified accordingly. 1 X

Other special designs of a superheating unit of the invention may include a thermostat, limit 7 fuse, bi-metallic thermometer, handle extension, etc. A motor-driven self-cleaning rotary steel brush, properly mounted to the superheating unit, may be useful on large, even surfaces such as ship hulls, house exteriors, etc.

For the average paint removing job only a small volume of vapor is needed. The superheating unit, therefore, can be built to be its own vapor generator, either as self-contained unit operating for a certain length of time without being refllled (Figs. 1'7, 18) or as a flash or semi-flash boilersuperheater combination being continuously or intermittently supplied with small quantities of water through the medium of a narrow gauge rubber hose (Figs. 19, 20).

The boiler-superheater unit of Figs. 17, 18 is of rather long and flat shape and may be wielded like a plane in shaving off the melted paint. The appliance is filled with, say, a cup of water, which at an adequate rate of evaporation enables over half an hour of continuous operation. Before being closed by cover 10a of the screw-on type, the apparatus is returned to a horizontal position in order to drain off through side inlet I all liquid in excess of the proper initial water level In. Then the device is connected by cord 50 to a convenient source of electricity and rested like a flat iron on the four small bottom protrusions 66b. Steaming will be quick as the relatively large heating surface of heater 8! will be completely submerged in the water. The steam passes through vapor inlet 90 into said heater 09, circulates therethrough as will be explained later, and emerges at a temperature of about 400 F. from the two heater outlets I03, I04 into a space I05, which is formed by the rear enclosure 60a aflixed to the shell 65. From said space I05 the steam passes through the outlet canals I01 of the upper heater I06, where it is highly superheated by the exposed resistance coils I09, III before it leaves the nozzle 08.

The construction employs two heating units, 00 and I06, one in the lower, the other in the upper part of shell 66, in order to insure proper evaporation and superheating in all possible op rating positions. There will always be an equal amount of heating surface in the water and in the steam space regardless of the angle at which the appliance is held. It can even be operated upside down without diminishing its efficiency. In that case the evaporating function is wholly taken over by the upper heater I06 while the radiation coil I00 enclosed in the lower heater 09 does a major part of the superheating.

Water cannot enter the heater 8! because of the location of vapor inlet 50 at or near the volumetric center of the vessel 60. If same has been filled with the proper amount of water, the horizontal and vertical level of the liquid will approximate the dash dot dot lines IIIa, IIIb, Illc in Fig. 17, leaving a water-free space around the vapor inlet 90 in all operating positions, also when the appliance is vigorously being shaken during the process of brushing. If for some inordinate reason a water slug should find access into the heater 8!, any possibility of the exposed electric wire contained therein being fused by liquid is precluded through the particular design of said heater 09.

The seemingly intricate but in reality simple design of the heating members 09 and HI of Figs. 17 and 19 has been made possible through the availability of absolutely shockproof ceramic materials and the ease of manufacturing thereof also complicated forms by the low-cost extrusion process. During the war ceramic bodies have been developed, which, even when in a white-hot state, do not crack upon contact with cold water. Some of these new ceramic materials are of diamond hardness and do not absorb water. Heating units extruded from such materials will be practically indestructible. They may be metalclad (00a, Ilia, Figs. 17, 18) or they may be without a metallic cover as shown in Figs. 19, 20.

The extrusion of the multihole ceramic member 00 follows a die pattern indicated by Figs. 23, 25. The cross-sectional views show a series of perimetrically located slot-like canals 00 and a number of quadratic holes I02 through the center part of the member. Each pair of said canals l0 and I02 has at either end a recess 00 and III, respectively (Figs. 21, 22), the recesses being so staggered in relation to each other that upon closing both ends of the member with a plate a continuous internal canal system is formed. The closing is effected by screwing a front and rear plate 98 and 98 to said member (Figs. 24, 26), heatproof gaskets 01 being inserted in between to make the canal system steamtight. The rear plate 09 of member 00 has two openings I08, I, through which the two ends of wire coil I00 protrude (Figs. 22, 26) for connection with the electric terminals of the apphance (Figs. 17, 19). Said heating coil I00 is threaded through the quadratic canals I02 before member 00 is closed. Operation is as follows:

The vapor inside shell 66 enters the heater 00 at ill, travels in a zig-zag manner clockand counterclockwise (Fig. 21) through the slot canals 95 along the sides 90, SI, 92 and 90, 03, 02, respectively, of said ceramic member and passes at its bottom side 92 from two directions into a cut-out I00, which links the recesses and II and therefore the canal systems 95 and I02 of the member as shown in Figs. 22, 23. From said junction the steam flows through the inner conduits I02, circulating past the radiation coil Ill (Fig. 22) before it takes the final discharge course already described. In case a water slug should happen to enter vapor inlet 00 the liquid will be entrapped by force of gravity at one or the other end of member 00, while the steam is able to escape into the inner outlet conduits I02 by way of the open section of the perimetric slot system 05. The water entrapped in the other part of said canal system 05 has no chance of reaching the exposed resistance wire I00, no matter how quickly the apparatus is tilted back and forth, because the liquid in the extremely hot, narrow slots will almost instantly be vaporized. This idea is further elaborated in the design or the ceramic flash steam generator I2I used for the paint removing equipment of Figs. 19, 20.

In said arrangement the source of liquid is a water container I I2 suspended on a nail or otherwise placed in an elevated position with respect to the hand portable appliance. The water flows by gravity through the rubber hose III into the lower part of handle SI, from where it is manually iniected into the apparatus by a suitable control device. The release mechanism Ill shown in Fig. 19 has a slideable flanged rod IIO, which is normally held in an upward, closed position through the spring I". When push button II! is pressed down with the thumb of the hand holding the apparatus, the elbow oriflce II! in the bottom end of rod '6 will communicate with the outlet Ill in the hollow handle part and discharge a flne jet of water through the inlet I20 into the flash generator I2l. To

facilitate immediate evaporation, warm or hot water may be used and the container H2 and supply hose H3 may be insulated, the latter perhaps by a surrounding rubber hose. If connection to a faucet is contemplated, the release mechanism must be in the form of a valve adapted to the higher pressure of the city water line.

Whereas the upper heating member I06 of Figs. 17, 18 simply contains a number of canals II accommodating resistance wires and steam outflow thereover, the flash steam generator I2I of Figs. 19, 20 is composed, in addition, of numerous very narrow slots I22, which are perimetrically arranged around said quadratic canals I01 and closed by end plates I24, I25 in a manner resembling the construction of heater 89, with the exception of the following differences.

The end plates I24, I25, which cover the recesses I23 at the front and rear end of the flash generator l2I, have a rectangular cut-out I21 (Fig. 20) to permit passage of the steam from rear space I through the inner outlet canals I0I of said member. As the wiring and rewiring of these canals is possible without removing the end plates I24, I25, same can be affixed permanently by cementing or other means. This eliminates the screws, gaskets and tapping necessary for the assembly of heating unit 09. It also permits that member I2I may be built as indicated in Figs. 30, 31, the end plates being inside the shell 66.

The vaporizing slots I22 of flash generator I2 I', diagrammatically illustrated in Fig. 2'7, spread in one zig-zag succession all around the four sides of the member, beginning at its top side with water inlet I20 and ending with steam outlet I26 nearby. As in extrusion the contours of a ceramic stock are of no import as to fabrication cost, said vaporizing slots I22 may be extremely narrow, their cross-section may have a U-shape or other form, two or more of the very flat canals may be superposed so as to be in parallel connection with the water inlet I20 and steam outlet I26 (Figs. 28, 30, 31). If round, a triple set of vaporizing canals may be aligned to each recess I23 as shown in Fig. 29.

The above features of ceramic member I2I assure instantaneous steam production and a maximum of generative power of said unit. The water, released by push button '5, descends by gravity into the extremely hot slots I22, is forced to rapidly circulate therethrough and is flashed into steam. The high velocity acquired by the water and steam keeps the narrow canals thoroughly free from scale deposits.

The steam, leaving the generator at I26, is collected in the shell 66, from where it is drawn off through the centrally located vapor inlet 94 by way of the radiant inner superheating canals of the lower and upper heating members 09 and I2I. Steam production is instantly stopped by releasing push button II5, which interrupts the water injection.

The superheating unit of Figs. 19, 20 may also be operated as a semi-flash generator. The heating elements I 09, H0 inside the generator I2 I' are temporarily switched off or to a lower wattage while water is being admitted into the shell 66. The water thus trapped will be evaporated by the lower heater 89, which gives the appliance additional generative capacity in conjunction with its flash generator I2I. Unrestrained manipulation of the apparatus, also when it contains some water, is possible because of the volumetric center position of vapor inlet 94.

For effective steam heat regulation, both constructions of Figs. 17 and 19 employ three radiation elements I08-I I0. The wire ends protruding from the upper and lower ceramic member are heat-proof insulated and connected in series or in parallel through the rear space I05 to a multiheat switch or plug and socket control unit as shown in Figs. 19 and 17, respectively. The resistance coils I09, H0 in the upper heating member may be distributed as indicated in Figs. 18, 20 or 30. Eventual rewiring is easily efiected by removing the nozzle 48, the end plates 98, 99 and the switch or socket, which covers the opening 660 of rear enclosure 06a.

The shell 66, rear cover 66a and the two heating members are assembled by forcefitting, cementing or other means.

The self-generating superheating devices of the invention may of course be also used in connection with a steam hose by attaching same to side inlet I0 shown in Fig. 18.

All the aforedescribed types of superheating devices are practical not only for paint removing but for many other specialized processes in trades and industries, where local steam heat application is required.

Fig. 32 shows in a schematic manner a steam generating system of a power plant exemplifying the principles of the invention. The system has a boiler 400, a steam main 40I, a turbine 406, an electric radiant superheater 403 with terminals M9, 420. power circuit 42I, control panel (rear view) 422, control circuits 423 and a hand-operated switch 424.

The superheater is connected with the steam main near the turbine. The steam flow can be detoured through pipe 405 by means of two valves 402, 404, which permits easy access to the superheater for maintenance work.

The superheater is also provided with a thermostat controller 425 and a temperature-limit fuse 421. The thermostat controller 425 is actuated by a Bourbon tube extending from the steam space of the superheater and operates a voltage regulator 426 which raises or lowers the voltage impressed on the heating elements so that the heat generated equals the heat absorbed by the steam flow. The temperature is thereby held within a desired value. In case of temporary derangement of the thermostat controller, protective means indicated by the temperature-limit fuse 421 will actuate a circuit breaker 428.

The superheater 403 itself can be constructed in various ways. One arrangement is to use a heavily insulated, strong metallic cylinder which is closed by steel heads having a flange suitable for coupling with the steam main.

The ceramic lining of the inner surfaces of the superheater is glazed and highly polished or specially coated so as to reflect most of the radiant energy for absorption by the steam flow.

The heavy resistor heating elements inside the superheater are spaced and separated from the tube by porcelain supports of varying design.

These supports may be bushings individually secured to the cylinder or perforated insulating bars held in place by strong bolts or other suitable means. The flat metal strips of the radiation elements are wound either helically or back and forth in a sinuous form through the holes of the insulating bars.

Still simpler is the mounting of a non-metallic,

rod-type radiation element. The rod element is clamped between strong terminal arms and is otherwise self-supporting. It may be pierced by a plurality of channels in order to enlarge the radiating surface. Uniform heat distribution is obtained by placing the element of! center into the superheater tube.

In order to achieve best results with a minimum of radiated ener y. the saturated steam entering an electric superheater of the invention should, of course, be as dry as possible. If the steam main is long and condensation excessive, a unit |0la (Fig. 32) designed to eliminate most of the water carried by the steam should precede the superheater. Such a unit may be any kind of water trap, drier or preheater. Much better, however, is to install somewhere between the end points of an extended pipe system an intermediate radiant superheater of the electric type just discussed having a wattage just suflicient to keep the steam flow dry until it reaches the main superheater near the engine.

The practical aspects of an electric superheater applying the principles of the invention on an industrial basis may be summarized as follows:

The initial cost will be very low due to the simple construction and small size of such a superheater. It needs practically no attention, is not subject to a large upkeep cost or depreciation and can be repaired without in any way interfering with the operation of the boiler.

An electric superheater of the invention can be ccnnect'Ld to any steam pipe system for drying and superheating the steam flow. It can be installed right at the point of steam utilization. It can be made direct part of any type of steam engine that transforms heat into work.

It permits instant and close heat regulation of the steam flow by means of an automatic or hand-operated switch arrangement. The attainable ultimate superheat degree is limited only by the operating temperature designed for the electric elements.

It is practically indestructible and can be built to withstand extreme conditions of heat or chemical reaction.

It can be disconnected at convenience without any danger of burning as is now the case with the large pipe layout of superheaters operated by the same products of combustion that keep the boiler under pressure.

It is a natural auxiliary to electric vapor generators of all types.

An electric superheater of the invention may easily be combined with non-electric boilers having no superheater or in place of or as addition to existing superheaters, particularly where lack of space requires an efllcient superheater of very small size or where temporarily, locally or for some special reason extreme superheat temperatures are required. It may also be used as an auxiliary to the heating boilers in buildings.

12 Itwillbeapparenttothoseskilledintheart that the novel principles of the invention disclosed herein in connection with specific exempliflcations thereof will suggest various other modifications and applications of the same. It is accordingly desired that in construing the breadth of the appended claims they shall not be limited to the specific exempliflcations of the invention described herein. I claim:

l. A vapor superheater having a vapor duct insulator block formed of ceramic material with multiple parallel passages, each duct passage closely confining a bare resistor heating element, means to control the passage of vapor in contact with the bare resistor elements and means isolating the vapor gas from back now to the source 01 vaporiaztion.

2. A vapor superheater having multiple duct ceramic insulators of the kind set forth in claim 1 each duct closely confining a bare resistor heating element, and means to control the heating and the passing of vapor in contact with the bare heating element.

3. A vapor superheater having a plurality oi vapor conducting ducts passing through a body of ceramic insulation, each duct having walls closely encompassing resistor heating elements of bare wire for direct contact with passing vapor, and multiple control means for said heating elements for series or parallel current supply through resistors in a plurality of the ducts.

4. A vapor superheater system having a source of vapor supply remote from a superheater means, a flexible hose connecting the vapor source and superheater means, heating wires in said hose, ceramic beads on said wires for mutual insulation, whereby the vapor is heated to prevent condensation.

LOUIS J. IEHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATE PATENTS Number Name Date 1,119,840 Kuhn Dec. 8, 1914 1,403,594 Duo Jan. 17, 1922 1,407,955 Smalley Feb. 28, 1922 1,598,811 Ferrin Sept. 7, 1926 1,642,933 McGrath Sept. 20, 1927 1,707,453 Winograd Apr. 2, 1929 1,727,995 Lechler Sept. 10, 1929 1,905,343 Carpenter Apr. 25, 1933 2,012,523 Thome et al. Aug. 27, 1935 2,043,002 Lechler June 2, 1936 FOREIGN PATENTS Number Country Date 104,997 Austria Dec. 10, 1926

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