US3267678A - Vapor-generating device - Google Patents

Description

Aug. 23, 1966 N. CAMP 3,267,678

. VAPOR-GENERATING DEVICE Filed May 6, 1964 Y' 2 Sheets-Sheet l Y hot water cold water N AT C AMP INVENTOR.

AGENT Aug. 23, 1966 N. cAMP i 3,267,678

VAPOR-GENERATING DEVI CE Filed May 6, 1964 2 Sheets-Sheet 2 NAT CAMP NVENTOR.

AGENI p 3,267,678 1Ce Patented August 23, 1966 3,267,678 VAPOR-GENERATING DEVICE Nat Camp, 1316 Langdon Lane, Mamaroneck, N.Y. Filed May 6, 1964, Ser. No. 370,750 7 Claims. (Cl. 1 -108) This application is a continuation-in-part of my copending application Ser. No. 94,611, iled March 9, 1961 and now abandoned.

My present invention relates to a vapor-generating device adapted to be used for the dispensing of various substances in vapor form, for 'humidication of the atmosphere of a room or the like, for distillation of sea water and other uids, for the operation of apparatus using vapor pressure as a source of motive power, and for related purposes.

A principal object of this invention is to provide a vapor generator adapted to operate in a highly economical and efficient manner by concentrating the output of an available heat source on a relatively small volume of liquid (generally water) to be vaporized.

A more particular object is to provide a source of lowpressure steam operating on a very limited caloric input and with a short warmup period.

Another specific object of the instant invention is to provide a portable steam generator capa-ble of being incorporated, for example, in a compact unit immersible in a large body of water in such manner as to vaporize -only a small fraction thereof at a time.

It is also an object of this linvention to provide effective means for both thermally and hydrostatically isolating a steam generator from a relatively large body of water from which this generator is continuously supplied.

4I have found, in accordance with the present invention, that the above objects can be realized through the use of one or more capillary tubes inserted in a uid path between a relatively large body of liquid, specically water, and a relatively small boiler chamber, the capillary tube or tubes serving the dual purpose of regulating the influx of liquid to the boiler chamber and preventing any backflow of hot water or steam from that chamber to the yreservoir which, of course, would constitute a loss of thermal energy. More particularly, I utilize the capillary tube or tubes as a means for creating a hydrostatic pressure differential Ap of such magnitude that a given input pressure p, is substantially balanced by the sum of Ap and a predetermined output pressure po, the latter term being represented at least in part by the hydrostatic head in the boiling chamber which is therefore maintained filled with water to a substantially constant level.

The insertion of a capillary tube between the reservoir and the boiler chamber, in accordance with my invention, thus establishes the relationship:

so that, for example, a partially filled boiling chamber may be disposed substantially below the level of its water supply if both the reservoir and the boiling chamber are substantially unrestrictedly open toward the atmosphere, as in the-case of a vaporizer. If, on the other hand, the steam generated in the boiling chamber is to drive a useful load, e.g. a turbine, a steam pressure equal to the load reaction will build up in the boiling chamber and will be superimposed on the hydrostatic head thereof to constitute the output pressure p0. In order to provide a commensurately increased input pressure p1, I may constitute the supply reservoir as a closed vessel whose internal pressure is'increased by the admission of highpressure uid, e.g. water or air delivered by a pump or compressor. Advantageously, in order to prevent a drainying of the boiling chamber toward the reservoir upon partial or complete failure of the input pressure (eg.

stoppage of the pump or compressor in the arrangement just described), the capillary tube or tubes should be so designed that po Ap.

As the cross-sectional area of the capillary tube is essentially determined by the viscosity of the liquid employed, little variation in that cross-sectional area is possible for the purpose of varying the rate of flow therethrough. To maintain a desired ow rate it will, therefore, often be convenient to connect two or more capillaries in parallel; this mode of connection does not materially alter the magnitude of the existing pressure drop which in the case of each tube is proportional to its length.

The boiling chamber may be designed in a variety of ways. A substantially cylindrical boiling chamber, horizontally disposed, has the advantage that a relatively small drop in liquid level will result in a relatively large decrease of the surface of the water bath and, therefore, in a commensurate reduction in the back pressure of the developing steam, if the latter is allowed to escape only through a .restricted outlet and/or by way of a load, once the bath level in the boiling chamber has fallen below its horizontal median plane. With an upright boiling chamber, on the other hand, an excess of rate of vaporization over rate of supply will result in a more rapid decrease of hydrostatic pressure in that chamber so that equilibrium will be more p-romptly restored independently of steam. pressure.

The heating of the boiling chamber may be effected lby various means disposed either within that chamber or externally thereof, an electrical heating element within the chamber being particularly advantageous in the case of immersible or other compact steam generators.

The invention and its advantages will be better understood from the following detailed description of certain embodiments, reference being made to the accompanying drawing in which:

FIG. l is an elevational view, partly in section, of a water tank equipped with a steam generator according to my invention;

FIG. 2 is a sectional view, on a larger scale, of the boiling chamber of the steam generator shown in FIG. 1;

FIG. 3 is an elevational view of a modified steam generator similar to the one illustrated in FIGS. 1 and 2 but designed as an immersible unit; and

FIG. 4 is a diagrammatic view, partly in section of still another embodiment.

In FIG. 1 I have illustrated a tank 10 supported on legs 11 and filled with water to a level 12. The bottom of the tank is formed with a drain 13 overlain by a strainer 14 to prevent any :clogging thereof by entrained solids. Drain 13 merges into a capillary tube 15, with an inner diameter of one or two millimeters, terminating at the underside of a cylindrical boiling chamber 16. The chamber is closed at one end by a cap 17 through which pass a pair of wires 18 for connecting a heater 19 (FIG. 2) in its interior to a source of electric current. Charnber 16 is also provided with a discharge tube 20 for generated steam, rising from its upper surface, and with a return pipe 21 for hot condensate, entering it from below.

A small sealed container 22, serving as a water separator, is shown suspended by the conduits 20, 21 within tank 10 above the liquid level 12. Tube 20 enters the container 22 from above to let any entrained on recondensed water ilow back at its bottom into the pipe 21. An outlet tube 23 for the nearly dry vapor extends upwardly from container 22 to a vessel 24 serving for the storage of a volatile substance 25, e.g. an inhalant to be entrained into the atmosphere by the vapor passing through an extension 26 of tube 23 terminating in an upwardly open thimble 27 having a depending spout for the return of any residual water to the tank 10.

The interior of chamber 16, visible in FIG. 2, also contains a thermostatic switch 28 connected in series with the resistance element of heater 19 acrossthe wires 18 to prevent overheating of the device. When switch 28 has been tripped open by an excessive rise in temperature, it may be manually reset by a button 29 after water has again been admitted to the boiling chamber. The discharge end of inlet tube 15 is shown provided with a shutoff valve 311 to stop the influx of water into the chamber 16 during periods of non-use, thereby reducing the time needed to start the gener-ation of steam when the device is put into operation.

In use, wires 1S are plugged into an electric outlet to energize the element 19 which heats the water in chamber 16. As steam begins to develop, it expels from tube 20 any water that may have risen therein and discharges it into container 22 whence it is returned to chamber 16 via pipe 21. The steam then passes out through thimble 27, entraining the substance 25 in vessel 24. Fresh water enters the chamber 16 through capillary 15 at a relatively slow rate which matches the rate of vaporization only after the pressure in the -chamber has dropped suiiiciently to accelerate the travel of the liquid through this tube. As a result, steam will evolve rapidly enough to dissipate the heat of element 19 at temperature close to the boiling point of water at atmospheric pressure. I have observed, for example, that a boiling chamber of 22 mm. inner diameter and liO cm. length, heated by a 250-watt element and supplied with water at 15 C. through a capillary of 1.5

mm. diameter and 33 cm. length, began to generate water at an appreciable rate only two or three minutes after the heater had been energized. The length of tube 15, While not critical, should be suliicient to afford thermal insulation between the boiling chamber 16 and the tank 10,

' in addition to providing the flow-retarding action necessary to prevent the escape of steam through drain 13 into the tank. The conduits 20 and 21, whose inner diameters and cross-sectional areas should of course be considerably larger than those of tube 15, could, if properly insulated to minimize heat losses, also be led through the interior of the tank, in the general manner illustrated in FIG. 3. Thirnble 27, which acts as a secondary liquid separator, may be omitted or replaced by some other outlet termination, if the device is to be used for purposes other than room humidification and the entrainment of small quantities of water by the steam is not objectionable.

In FIG. 3 I show a modified system generally similar to that described in connection with the preceding figures and comprising a tank filled with water; a unit 31, removably immersed therein, consists essentially of a boiling chamber 16' with thermally insulated walls and an insulated jacket 32 rising from this chamber to a height above the Water level 12. The jacket 32 contains the conduits 20', 21 along with the liquid separator 22 and a portion of the supply conductors 18". Outlet tube 23', extending upwardly from -container 22, again directs the developing steam through a vessel 24 for the purpose described in connection with FIG. 1; its extension 26 terminates in a thimble 27. An insulating sleeve 33 partly envelopes the tube Chamber 16', Whose internal construction is similar to v that of chamber 16 shown in FIG. 2 and which is also of operation, i.e. while the boiling chamber 16 or 16'` is substantially iilled and has not yet reached its state ofv equilibrium. Thus, either or both of these receptacles may be omitted in many instances.

In the embodiment shown in FIG. 4 a sealed storage tank 40 is provided with an air compressor 41 in a duct 51 and a water-inlet pipe 42 normally closed by a valve 50. The tank 4t) communicates with a somewhat smaller boiler 46 by means of a plurality of coiled capillary tubes 45, extending from the lower part of reservoir 40 `to the lower part of boiler 46. y

A source of Vheat shown diagrammatically as a gas heater 49, located at 'the base of boiler 46, is provided for the heating lof its contents.

The boiler 46 also communicates with a steam turbine 44 by means of a conduit 43. A pipe 47 leading from the turbine 44 to the atmosphere acts as an escape ductor therused steam. Thermal insulation 52 surrounds the wall of boiler 46.

In operation, water is introduced into the reservoir 40 via the inlet pipe 42 to the descent level whereupon the valve 5t) is closed. Thereupon, compressor 41 and heater 49 are actuated. Water from the reservoir 40 enters the boiler 46 through the capillary tubes 45 under the combined pressure of air from compressor 41 and the hydrostatic head in vessel 40, this combined pressure being balanced by the sum of the hydrostatic head in boiling chamber 46, the steam pressure in that chamber and the pressure drop across the three parallel-connected tubes 45. Because of the small size of the boiler 46, the water entering it is rapidly heated to produce steam which is piped through conduit 43 to the turbine 44, the steam driving the turbine 44 and being then released through the outlet pipe 47. Y

The system shown in FIG. 4 is intended for intermittentl operation of the turbine 44, with periodic replenishment of the contents of reservoir 40 to maintain the Water level thereof nearly constant. Under these circumstances the Water level in boiling chamber 46 will also be sufbjec't to but little fluctuation if the back pressure of the turbine is regarded as substantially constant. The tubes 45 constitute a restricted passage of predetermined hydrostatic resistance, and the principle `of operation will be substantially the same as in the aforedescribed instances. desirable to establish such a relationship between the various pressure components referred to above that a substantial amount of liquid is chamber 46.

For sustained operation, the system of FIG. 4 could be readily modiiied to admit water continuously under suitable pressure, with use of -a feeding pump or a pressureregulated water supply, if necessary, through pipe 42 so as to maintain the tank 40 always iilled to the top, lthe compressor 41 being then replaced by an airtight seal for duct 51.

As will be apparent from the preceding explanation of the principles underlying my invention, the embodiments described hereinabove may be moditied in various ways, e.g. by a substitution of a boiling c'hamber as shown in FIG. 2 for the boiler 46 of FIG. 4 or by utilization of different types of heating means. My invention is, accordingly, not limited to the specific arrangements herein disclosed but is capable of numerous variations and adaptations without departing from the spirit and scope of the appended cla-ims.

I claim:

1. A vaporagenerating device comprising a boiling chamber, a reservoir containing a body of liquid substantially larger than the volume of said chamber, said body of liquid being under a substantially constant downward pressure of an overlying body of air, capillary-tube means forming a restricted passage of predetermined hydrostatic resistance between said reservoir and said chamber, and heating means for boiling a liquid in said chamber, said capillary-tube means being so dimens-ioned as to develop thereacross an appreciable pressure differential Ap maintaining the liquid in said chamber at a substantially constant level with development of a substantially constant It is present at all time-s in boiling output pressure po at the chamber end of said capillarytube means in the presence of a substantially constant input pressure pi at the reservoir end of said capillarytube means, with PiPo-l-Ap.

2. A vapor-generating device as `defined in claim 1 wherein said reservoir is open toward the atmosphere, said boiling Chamber being entirely disposed below the level of said body of liquid.

3. A vapor-generating device as defined in claim 1, further comprising turbine means connected to said boiling chamber for operation by vapor developed therein, and a source of pressure lluid connected to said reservoir.

4. A vapor-generating device as `defined in claim 1 wherein said capillary tube means comprises a plurality of capillary tubes connected in parallel.

5. A vapor-generating device comprising, in combination with an upwardly open vessel containing a relatively large body of Water, a boiling chamber of relatively small volume disposed below the level of said body of water; a capillary inlet tube entering said chamber substantially at its bottom and opening into said body of Water, said reservoir being closed at its (bottom except for the inlet of said capillary tube; an outlet tube of substantially larger cross-sectional area than said inlet tube extending into the atmosphere from a location near the top of said chamber but below said level; and heating means at said chamber for boiling water admitted to said chamber from said vessel by way of said inlet tube, the latter being suficiently restricted to retard the .influx of water into said chamber upon operation of said heating means so that said influx matches the rate of evaporation of Water from said chamber in a partly lilled condition thereof whereby the water level in said chamber lies below the level of said body of water despite equal atmospheric pressures upon said lbody of water through the open top of said vessel and upon the Water in said chamber through said outlet tube.

6. A vapor-generating device comprising, in combination with a vessel containing a relatively large body of water, an elongated boiling chamber of relatively small volume disposed substantially 'horizontally below the level of said body of Water; a capillary inlet tube entering said chamber substantially `at its bottom and opening into said body of water; an outlet tube of substantially larger cross-sectional area than said inlet tube extending into the atmosphere from a location near the top of said chamber but below said level; and an elongated heating element extending in axial Adirection in `said chamber along the bottom thereof for boiling water admitted to said chamber from said vessel by way of said inlet tube, the latter being suiciently restricted to retard the influx of water into said chamber upon operation of said heating element so that said influx matches the rate of evaporation of water from said chamber only in a partly lled condition of said chamber.

7. A vapor-generating device comprising, in combination with an open-topped reservoir containing a relatively large body oli-water, an elongated, `substantially cylindrical and horizontal boiling chamber of relatively small volume disposed entirely below the level of said body of water; a capillary inlet tube having one end connected to said chamber substantially at its lbottom `and having another end connected to said reservoir adjacent the bottom thereof; an outlet tube of substantially larger cross-sectional area than sa-id capillary inlet `tube extending into the atmosphere from `a location near t'he top of the chamber but below said level; and an elongated electrical heating element extending in axial direction in said chamber along the bottom thereof for boiling water admitted to said chamber from said vessel by Way of said inlet tube, the latter being suiciently restricted to retard the influx of water into said chamber upon operation of said heating element so that said influx matches the rate of evaporation of water from said chamber only in a partly lled condition of said chamber.

References Cited by the Examiner UNITED STATES PATENTS 2,280,894 4/ 1942 Cushman 122-27 X 2,453,455 11/1948 Persak 21-119 3,006,147 10/1961 Geary 60-108 X MARTIN P. SCHWADRON, Primary Examiner.

ROBERT R. BUNEVICH, SAMUEL LEVINE,

Assistant Examiners.

Claims (1)

1. A VAPOR-GENERATING DEVICE COMPRISING A BOILING CHAMBER, A RESERVOIR CONTAINING A BODY OF LIQUID SUBSTANTIALLY LARGER THAN THE VOLUME OF SAID CHAMBER, SAID BODY OF LIQUID BEING UNDER A SUBSTANTIALLY CONSTANT DOWNWARD PRESSURE OF AN OVERLYING BODY OF AIR, CAPILLARY-TUBE MEANS FORMING A RESTRICTED PASSAGE OF PREDETERMINED HYDROSTATIC RESISTANCE BETWEEN SAID RESERVOIR AND SAID CHAMBER, AND HEATING MEANS FOR BOILING A LIQUID IN SAID CHAMBER, SAID CAPILLARY-TUBE MEANS BEING SO DIMENSIONED AS TO DEVELOP THEREACROSS AN APPRECIABLE PRESSURE DIFFERENTIAL $P MAINTAINING THE LIQUID IN SAID CHAMBER AT A SUBSTANTIALLY CONSTANT LEVEL WITH DEVELOPMENT OF A SUBSTANTIALLY CONSTANT OUTPUT PRESSURE PO AT THE CHAMBER END OF SAID CAPILLARYTUBE MEANS IN THE PRESENCE OF A SUBSTANTIALLY CONSTANT INPUT PRESSURE PI AT THE RESERVOIR END OF SAID CAPILLARYTUBE MEANS, WITH PI$PO+$P.

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