Abstract:
The steam generating system utilizing a first container having a liquid chamber. The first container is surrounded by a conducting coil for generating a field and producing eddy currents on the container. Steam produced in the first container is sent to a second container which is similarly heated by an induced eddy current. Steam in the second container is superheated for use.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a novel and useful steam generating system. 
     Steam is currently generated from liquid water by the use of oil, gas, coal, or other fuel in pressurized heat exchanged vessels. The pressure within such vessels normally runs 20 to 60 atmospheres. These prior steam generators are systems typically found on ocean going vessels and are quite large and cumbersome. 
     Natural gas fired or resistance electric heater systems have also been devised to produce superheated steam. Such systems are generally slow and inefficient. 
     In the past, induction heaters have been employed in furnaces to heat a metallic charge within a refractory crucible. Such furnaces are surrounded by a water cooled copper coil which receives power in the form of alternating current varying from 60 hertz to 500,000 hertz, or even higher frequencies which are derived from oscillators. Essentially, the molten charge within such induction furnace is heated by the interaction of eddy currents produced by a high frequency field. Moreover, the molten charge is considered to be the secondary of a transformer. 
     Unfortunately, the past systems have either required extensive and expensive equipment to produce superheated steam at very high pressures. 
     A steam generating system which produces superheated steam at or near atmospheric pressure would be a notable advance in the industrial arts. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention a novel and useful steam generating system is herein provided. 
     The steam generating system includes a first container which is provided with a first chamber for a liquid to be converted into steam. Such liquid may be water, ammonia, and the like. The chamber includes an inlet and an outlet. A reservoir of water communicates with the inlet of the first container such that liquid is provided therein at a steady rate, commensurate with the generation of steam within the container. The container also includes a tank wall portion or shell which is capable of being heated by electrically induced eddy currents. In most cases, the wall portion may be a metallic member such as copper, silver, aluminum, and the like. However, other materials may be employed which are capable of performing this function. In certain cases, metallic shells having a mask of other metallic materials may be employed. For example, a combination of a copper shell and an iron mask suffices, in this regard. 
     The system of the present invention also includes a first coil which at least partially surrounds the first container. The first coil may be a metallic member or one which is composed of a material which conducts electricity and is capable of producing a field around the container. The first coil may also be cooled by the passage of liquid therethrough. In this respect, such cooling helps maintain the strength of the electromagnetic field produced by the coil, which will be discussed hereinafter. 
     An insulation layer may also be found, in the present invention, sandwiched between the first coil and the wall portion of the first container. Such insulation layer is also cooled by the coil which is normally heated by heat radiating from the container. In essence, eddy currents created within the metallic tank by the electro-magnetic field produced by the coil heats the tank through the Joule effect. Radiated heat from the tank travels inwardly and heats upon the liquid within the chamber into steam. The steam is raised to a desired temperature for use. In certain cases, steam may be superheated within the first container. 
     First electric means generates a magnetic field at the first coil and an eddy current at the first container tank wall portion. The first electric means in the form of a high frequency AC power source produces a frequency which may be typically 250,000   25 kilohertz. However, any high frequency can be utilized in the power source of the present invention. 
     A second container is also employed in one of the embodiments of the present invention. Again, the second container is similarly constructed to the first container. That is, the second container includes a chamber, an inlet, and outlet, and a tank wall portion capable of being heated by an induction eddy current. A second coil surrounds the second chamber and is connected to second electric means for generating a field in the second coil and an eddy current at the second container. Conduit means transports steam from the first container outlet to the second container inlet. The induction heating accomplished in the second container superheats steam at approximately atmospheric pressure. Thus, superheated steam passes from the second container and may be employed to heat any item such as foodstuffs, metals, and the like. 
     It may be apparent that a novel and useful steam generating system has been described. 
     It is therefore an object of the present invention to produce a steam generating system which capable of producing superheated steam at or about atmospheric pressure. 
     Another object of the present invention is to provide a steam generating system which employs induction heating and avoids the expense and bulk of equipment used in prior superheated steam generating systems. 
     Another object of the present invention is to provide a steam generating system which is compact and may be easily used in confined spaces. 
     A further advantage of the present invention is to provide a steam generating system which is highly efficient and uses an induction and heating element having a high frequency power source. 
     Another object of the present invention is to provide a steam generating system which eliminates fire hazards, since the outer surfaces of the equipment employed in the present invention are normally cool to the touch. 
     The invention possesses other objects and advantages especially as concerns particular characteristics and features thereof which will become apparent as the specification continues. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view showing an overall arrangement of the steam generating system of present invention with the supporting conduits depicted in schematic rendition. 
     FIG. 2 is a sectional view taken along line  2 — 2  of FIG.  1 . 
     FIG. 3 is a schematic overlay of the high frequency alternating current system for generating electromagnetic field in the tandem containers of the present invention. 
     FIG. 4 is a sectional view depicting a typical steam chamber being fed by the outlet of the second container. 
    
    
     For a better understanding of the invention reference is made to the following detailed description of the preferred embodiments thereof which should be taken in conjunction with the prior described drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Various aspects of the present invention will evolve from the following detailed description of the preferred embodiments which should be referenced to the hereinabove delineated drawings. 
     The invention as a whole is depicted in the drawings by reference character  10 . The steam generating system  10  includes as one of its elements a first container  12 . The first container  12  is formed with a chamber  14  which contains liquid charge  16  that is converted into steam  18 . Liquid charge  16  may be water, ammonia, freon, and other known compositions which are typically used in industrial sectors. First container  12  includes a tank  20  which may be composed of metallic material such as copper, silver, aluminum, and the like. With reference to FIG. 2, it may be observed that tank  20  is a metallic member having a mask layer  22  of powdered metallic material such as iron. It should be noted, that other materials may be employed for tank  20  as long as they are capable of being heated by an induction eddy current, which will be discussed hereinafter. Also, insulation layer  24  is shown in the drawings as surrounding tank  20  and mask layer  22 . Insulation layer  24  helps to contain the heat within first container  12 , specifically tank  20 , and reduces fire and safety hazards since the outer surface of container  12  is generally cool to the touch. Insulation layer  24  may be composed of any suitable material, commensurate with the characteristics of tank wall portion  20  and mask  22 . 
     The present invention also entails a first coil  26  which at least partially surrounds first container  12 . As depicted in FIGS. 1 and 2, first coil  26  spirals around container  12  and is capable of carrying a cooling fluid therewithin. Directional arrows  28  and  30 , FIG. 1 as well as directional arrow  31  of FIG. 2 depicts the flow pattern through the first coil  26 . First coil  26  is also composed of a material which is capable of conducting electrical currents such as copper, steel, and the like. Coil  26  also helps to cool insulation layer  24  adjacent tank wall portion  20 . 
     First electric means  28  generates an electromagnetic field in first coil  26 , FIG.  3 . First coil  26  is suitably connected to first electric means  28 , i.e., by crimping. First electric means comprises a high frequency AC power source having a frequency of approximately 250,000   25 KHz. However, any high frequency may be employed in this regard. When high frequency power is supplied by first electric means  28 , to coil  26 , eddy currents  30  are generated in the wall portion of metallic tank  20 . Through the Joule effect, the temperature of tank  20  is raised to a certain degree. At this point, heat is radiated from tank  20 , represented by rays  32 , into chamber  14  of first container  12 . As may be observed in FIG. 1, water body  16  is then turned into steam  18  by this expedient. 
     Turning again to FIG. 1, it should be apparent that a second container  34  is also found in the present invention. Second container includes a tank wall portion  36  of metallic material, essentially similar to that found in first container  12 . Thus, the structure of first container  12  found in FIG.  1  and herein before described, also applies to second container  34 . Second coil  38  spirals around second container  34  and is connected to AC power source  28  as depicted in FIG.  3 . Radiation rays  40  represent the radiation of heat from tank wall portion  36  by the induction heating process described with respect to container  12 . 
     Turning again to FIG. 1, it may be observed that containers  12  and  34  include temperature monitors  42  and  44 , respectively. Such temperature monitors may produce a temperature signal which is processed in a conventional controller (not shown). 
     Reservoir  46  is also found in the present invention for providing liquid  48  therewithin to the inlet  50  of container  12 . Pump  52  may be controlled by a level controller  54  of conventional configuration. Level controller  54  obtains a level signal from level meter  56  having a probe  58  within chamber  60  of reservoir  46 . Valves  62  permits water to pass from tank  20  to inlet  50  of container  12 . Of course, such liquid feed may be through gravity, pumps, and the like. FIG. 1 represents this movement through a conduit  64  in a schematic manner. Valve  66  permits the entrance of liquid  48  into container  12  through inlet  50  thereof. Container  12  includes an outlet  68  which permits steam to exit chamber  14  of container  12  and to enter inlet  70  of container  34 . Such steam is generally superheated by the induction heating mechanism associated with container  34 . Outlet  72  of container  34  passes superheated steam to the ultimate use for such steam, which may be a steam chamber  74 . 
     FIG. 4 represents steam chamber  74  as a typical ultimate use for the superheated steam  76  exiting container  34 . However, superheated steam  76  may find multiple uses. Steam chamber  74  includes a housing  78 . Conduit  80  from outlet  72  of container  34  feeds nozzles or spargers  80  and  82  which extend into the interior chamber  84  of housing  78 . A conveyor  86  moves according to directional arrow  88  and carries foodstuffs  90  through chamber  84  and into contact with superheated steam  76  therewithin. Foodstuffs  90  exit chamber  84  and are used or packaged as desired. 
     In operation, liquid  48  within reservoir  46  is fed to inlet  50  of container  12 . First coil  26  is connected to electric means in the form of a high frequency AC power source produces an electromagnetic field around tank  20 . Through the Joule effect, tank  20  is heated and radiates heat inwardly to chamber  14  of container  12 . Water body  16  within chamber  14  is heated into steam  18 . Steam  18  passes from container  12  through conduit  92  and into inlet  70  of second container  34 . A like heating effect takes place through the electrical energizing of coil  38 , which turns saturated steam  18  from first container  12  into superheated steam  76 . Superheated steam  76  passes through outlet  72  of second container  34  for use, represented by steam chamber  74 . First and second coils  26  and  38  are cooled by water or other fluids passing therethrough. Also, containers  12  and  34  include insulation layers, such as insulation layer  24  with respect to container  12 , to contain the heat within containers  12  and  34 . 
     While in the foregoing, embodiments of the present invention have been set forth in considerable detail for the purposes of making a complete disclosure of the invention, it may be apparent to those of skill in the art that numerous changes may be made in such detail without departing from the spirit and principles of the invention.