Abstract:
An improved superheated vapor generator for generating superheated vapor comprises a vapor generating volume for receiving liquid and including a vaporization member having a portion defining a plurality of holes for vaporizing contact with the liquid. The widths and/or depths of the holes may vary substantially randomly. The vaporization member may define grooves and ridges of substantially randomly varying height and depth and may further include intersecting grooves and ridges, intersecting the first-mentioned ridges and grooves, these ridges and grooves varying substantially randomly in height and depth. Two or more vapor generators may be arranged such that the vapor generated thereby and vapor pressure are additive. A method for fabricating an improved vapor generator comprises the steps of providing two thermally conductive parts with hollow interiors including at least one vaporization member defining a plurality of holes and welding the two parts together; the vapor generator may be composed of aluminum, stainless steel or other thermally conductive material.

Description:
FIELD OF THE INVENTION 
     The invention pertains to an improved generator for rapid generation of superheated vapor such as superheated steam and further relates to a method for fabricating means for generating superheated vapor. 
     DESCRIPTION OF THE PRIOR ART 
     Prior patents include U.S. Pat. No. 4,414,037, owned by the inventor and applicant herein, co-pending U.S. patent application Ser. No. 08/093,071 owned by the inventor and applicant herein for Superheated Vapor Generator and Control System and Method (incorporated by reference herein), references cited in connection with aforesaid U.S. Pat. No. 4,414,037 including U.S. Pat. Nos. 2,505,656; 2,753,212; 2,861,838; 2,983,450; 3,039,454; 3,218,741; 3,718,805; and 3,721,802, and patents cited in connection with said co-pending U.S. Pat. Nos. 3,721,802, 2,652,645, 3,436,852, 377,228, 3,119,004, 3,869,815, 4,255,646. 3,508,354, 3,823,497, 2,576,976. 
     The aforesaid patents in the main refer to apparatus for generating steam from liquid drawn from a reservoir. 
     U.S. Pat. No. 4,414,037 (the &#39;037 Patent) to the inventor herein discloses apparatus for generating superheated steam or other vapor from water drawn from a self-contained reservoir and includes means in the form of a nozzle for directing superheated steam to desired objects. The apparatus disclosed and claimed in the aforesaid patent is directed to a system for accomplishing, among other things, cleaning and sterilization, the mixture drawn from the reservoir in particular applications being a cleaning solution or a disinfectant. The device of the &#39;037 patent employs a nozzle positioned adjacent the cover of the device for directing the spray of superheated vapor, under the control of a foot switch whereby the intake and output of steam is regulated. The steam chamber comprises walls having point-like irregularities etched into the surface thereof by etching solution, as a result of which the production of vapor from input fluid is expedited as opposed to steam generation from a smooth-walled chamber. The chamber could be fabricated only of aluminum, due to the chemical process employed in etching the irregularities into the chamber walls. In addition, the device of the &#39;037 patent delivers a uniformly relatively dry mixture of superheated vapor, which was advantageous in a number of applications. 
     The device of the &#39;037 patent has been highly successful in numerous applications, including cleaning and sterilization of numerous objects such as large and small machinery and medical equipment. However, it was found that improved results and more general applicability could be achieved through a superheated vapor generator and control system which would produce superheated vapor such as steam even more rapidly than the existing device and would in addition afford the capability of greater convenience and mobility, and more precise control in terms of regulating and directing the flow of superheated fluid. In addition, it has been found in particular applications that regulation of moisture (i.e. liquid) content of the superheated vapor is of moment. The invention in the co-pending application includes an improved structure and method regarding the vapor generator chamber and configuration of the walls thereof as well as a method for fabricating such improved structure, and further refers to an improved control system for controlling and directing the stream of superheated vapor. 
     It has been found that further improved results can be obtained by means of a superheated vapor generator capable of generating superheated vapor such as steam more efficiently and rapidly and efficiently than the generator in the &#39;437 patent and in the co-pending application, and that in particular applications such increased rapidity and efficiency of vaporization is preferable. Thus, there has been a felt but unfulfilled need for a high-efficiency superheated vapor generator and method of fabrication thereof. 
     SUMMARY OF THE INVENTION 
     A superheated vapor generator for generating superheated vapor comprising a vapor generating volume for entry thereinto of liquid for vaporization, the vapor generating volume including at least one vaporization member including a portion defining a plurality of holes for vaporizing contact with the liquid. The widths and/or depths of the holes may vary substantially randomly. 
     The vaporization member may comprise a wall of such vaporization chamber or a thermally conductive member within the vaporization chamber, among other configurations in accordance with the invention. 
     The vaporization member may define a plurality of ridges and grooves of substantially randomly varying depths and heights. Transverse ridges and grooves intersecting the first-mentioned ridges and grooves may be employed, with the transverse ridges and grooves varying substantially randomly in height and depth. 
     Two or more superheated vapor generators in accordance with the invention may be connected such that the vapor and vapor pressure generated thereby are substantially additive. 
     A method for fabricating a superheated vapor generator comprises the steps of providing two thermally conductive parts with hollow interiors including at least one vaporization member defining a plurality of holes, and welding the two parts together. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a superheated vapor generator in accordance with the inventions depicting said generator in two parts; 
     FIG. 2 is a perspective view of the superheated vapor generator in accordance with the invention depicted in FIG. 1, depicted assembled; 
     FIG. 3 is a section of the vapor generator in accordance with the invention depicted in FIG. 1, taken along the line  3 — 3  of FIG. 1; 
     FIG. 4 is a sectional view of an alternative embodiment of the invention; 
     FIG. 5 is a sectional view, somewhat simplified, of a further alternative embodiment of the invention; 
     FIG. 6 schematically depicts a combination of a plurality of vapor generators in accordance with the invention; and 
     FIG. 7 is a schematic diagram of a method for fabricating a superheated vapor generator in accordance with the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1-3, inclusive, a superheated vapor generator  10  comprises a pair of metal castings in two sections  12 ,  14 , nestable with one another and welded together at weld  16 . The welded-together generator  10  is of generally cylindrical exterior configuration though, of course, in accordance with the invention other shapes may be employed in particular applications. 
     Vapor generator  10  comprises a body or housing  17  which defines centrally therein a vaporization chamber  18 . Chamber  18  as depicted is substantially spherical; however, in particular applications, other configurations may be employed in accordance with the invention. In the depicted spherical configuration, the periphery  20  of vaporization space  18  comprises a single wall. In other configurations in accordance with the invention, such periphery may comprise more than one wall or may be in sections, as for example, in a rectangular or polyhedral configuration. In the depicted embodiment, the wall  20  functions as a vaporization member or surface; in other embodiments of the invention (see FIG.  5 ), the vaporization surface or surfaces may be disposed within chamber  18  and may not comprise a wall but may for example, constitute a heatable member thermally coupled to the housing  17  or wall  20 , or both. In particular applications, such internal vaporization member may comprise a tetrahedral configuration (having as depicted a substantially rectangular contour) and may be employed in addition to or as an alternative to other configurations and locations of vaporization members, including the depicted wall configuration and location. 
     Wall surface  20  of chamber  18  defines a plurality of holes  22 . Holes  22  are of randomly varying depth and diameter, as best seen in FIG.  3 . 
     In particular applications of the invention, the depth of holes  22  varies substantially randomly between substantially 0.200 inch and 0.312 inch, while the diameters vary from substantially {fraction (5/32)} inch to {fraction (5/16)} inch. Other depth and diameter ranges may be employed in accordance with the invention. 
     It has been discovered that such variation in the diameters and depths of the holes  22  defined by the vaporization member in the form of inner wall  20  of chamber  18  produces highly efficient and rapid vapor generation upon introduction of a liquid to be vaporized into chamber  18 . In this context, efficiency refers to the degree of completeness of vaporization i.e. the less liquid remains unvaporized in the exudate, the greater the efficiency. It has further been discovered that the aforesaid highly rapid and efficient results are increased when the holes  22  vary substantially randomly in both depth and diameter; however, these dimensional variations are employable independently of one another and need not be employed concurrently. In particular applications of the invention, rapid and efficient vaporization has been achieved by variation of the depth alone or the diameter alone. Random distribution of hole sizes with respect to location has been found to promote rapidity and efficiency of operation. 
     In many respects, vapor generator  10  is similar to the vapor generator described, depicted and claimed in the aforesaid pending patent application Ser. No. 08/093,071. Thus, the description of the remaining features of the vapor generator  10  will be stated briefly and with reference to the aforesaid pending patent application, which is incorporated by reference herein. 
     A weld identifier marker slot  26  is defined in the periphery of body  17  of vapor generator  10 . Defined in generator body  17  are inlet aperture  28  in a weld area  30  on wall  20 , and outlet aperture  32 . Slot  26  is provided for the purpose of enabling, during welding, lining up of slot  26  with its counterpart (not shown) on part  12  of vapor generator  10  in the unassembled state in order to orient the respective sections properly. Such proper orientation entails the desired placement of inlet aperture  28  within weld area  30  and location of outlet aperture  32 . Inlet  28  is connectable to a source (not shown) of liquid, such as water, and outlet  32  is connectable to means (not shown) for directing expelled vapor. The connection of inlet aperture  28  to a source of liquid and outlet aperture  32  to vapor control means may in particular applications be as disclosed in the aforesaid co-pending patent application. 
     A thermostat  34  is affixed to a receptacle  36  in body  17 , whose function as described in said pending patent application is to control temperature of the vapor generator  10 . Other temperature control means, such as thermocouples, may be employed in accordance with the invention. As also described in the co-pending application, the heating of vapor generator  10  is accomplished by a heating cartridge (not shown), preferably electrically-powered, disposed in a receptacle (not shown) in body  10 . 
     As best seen in FIG. 1, parts  12 , 14  include mating flanges  38 ,  40  such that, in the depicted embodiment, the flange  40  of part  14  is fittable into flange  38  of part  12 . In this manner, when welding takes place, the weld is secure and engagement is tightened as a result of the engagement of the flanges  38 ,  40 . 
     Referring now to FIG. 4, an alternative embodiment of the invention is shown comprising a sectional view of a vapor generator  42  depicting the interior thereof. As depicted in FIG. 5, vapor generator  42  defines an internal volume in the form of a vaporization chamber  44  as in the embodiment of FIGS. 1-4, the vapor generator  42  being formed from two generally cylindrical parts, of which one, corresponding to part  12 , and designated with reference numeral  46  herein, is depicted. Vaporization chamber  44  includes a peripheral wall  48 . In wall  48  are defined a plurality of ridges and grooves  50 ,  52 , respectively. The heights of the ridges  50  and the depths of the grooves  52  vary substantially randomly 0.030-0.050 inch, and the ridges and grooves  50 ,  52  are generally circumferential. 
     As depicted, defined in wall  48  of chamber  46  are a plurality of transverse ridges and grooves  54 ,  56  substantially radially directed from the center of chamber  44 . As depicted, cross-grain ridges and grooves  54 ,  56  comprise a plurality; however, in particular applications there may be only one such cross-grain ridge and groove. Cross-grain ridges and grooves  54 ,  56  are, like ridges and grooves  50 ,  52 , of substantially random and irregular dimensions. Ridges and grooves  54 ,  56  vary substantially randomly between 0.020 and 0.050 inch. A plurality of holes  58  are defined in wall  48 . Holes  58  vary substantially randomly in depth and width in the same manner as holes  22  in the embodiment of FIGS. 1-3, inclusive. 
     It has been found that the presence of the ridges and grooves  50 ,  52  augments efficiency and rapidity of vaporization and that the presence of the transverse ridges and grooves  54 ,  56  has a similar effect. 
     Thus, in particular applications, the efficiency of a vapor generator employing holes may be increased by the presence of ridges and grooves  50 ,  52  and/or transverse ridges and grooves  54 ,  56 . 
     Referring now to FIG. 5, a further alternative embodiment of the invention is depicted therein. A vapor generator  60  includes a body  62  and vaporization chamber  64  in the same manner as in the above-referred embodiments. 
     Disposed in vaporization chamber  64  is vaporization member  66 . Member  66  has a generally rectangular cross-section as depicted, though in particular applications alternative configurations may be employed. Member  66  includes thermally conductive connector members  68 ,  70  thermally connecting member  66  to a wall  72  of chamber  64 . 
     Member  66  defines a plurality of holes  74 . Like the holes depicted in vaporization members in the above-discussed embodiments, holes  74  vary substantially randomly in dimensions and distribution of dimensions. 
     Defined in vaporization member  66  are a plurality of ridges and grooves  76 , 78 . Ridges and grooves  76 ,  78  like their counterparts in the embodiments described above vary substantially randomly in height and depth. Also defined in vaporization member  66  is a plurality of transverse ridges grooves  80 ,  82  substantially transverse to ridges and grooves  76 ,  78 ; these also vary substantially randomly in height and depth, like their counterparts discussed hereinabove. 
     As in the embodiments discussed above, grooves and ridges  76 ,  78  and transverse grooves and ridges  80 ,  82  may be employed separately or together with or without holes  74  for efficiency and rapidity of vaporization. 
     Referring now to FIG. 6, depicted schematically therein are vapor generators  90 ,  92  connected by inlet conduits  94 ,  96  respectively, to sources of liquid (not shown). Outlet conduits  98 ,  100  emanate from vapor generators  90 ,  92 , respectively. Outlet conduits  98 ,  100  accommodate vapor expelled from generators  90 ,  92  and intersect a common outlet conduit  102  connectable, for example, to output location such as vapor control means (not shown). In this manner, vapor and vapor pressure such as steam pressure, issuing from individual vapor generators are rendered substantially cumulative. In this manner, by employing vapor generators in combination, volume and pressure of vapor can be controlled, expanded and reduced as desired, rendering applications requiring relatively large volumes and pressures, such as power stations, feasible. 
     Vapor generators in accordance with the invention may be used in a wide variety of applications wherein there is need for apparatus for producing superheated vapor very rapidly and efficiently from liquid. A particular application is disclosed in detail in the aforesaid pending patent application for Superheated Vapor Generator and Control System and Method, and operation of such system is described in detail therein; thus, the description herein will be brief. As disclosed in the aforesaid patent application, a vapor generator in accordance with the invention is connectable to control means and couplable to a reservoir of fluid to be vaporized. The vapor generator is heated to a preset and controlled superheated temperature e.g. 500° F., and superheated vapor generator in accordance with the present invention may be employed in the system of the earlier-filed patent application. In operation, control means cause liquid from a reservoir (not shown) to be drawn into inlet  28  of vapor generator  10 ; in vapor generator  10  the liquid is very rapidly and efficiently converted to vapor. 
     Vapor is expelled through outlet  32  and may be directed to a desired location by a nozzle as described in said pending patent application or by other means. 
     It has been found that liquid on vaporization surfaces configured in accordance with the invention does not exhibit “beading” activity to the extent this occurs on superheated surfaces lacking surface configuration in accordance with the invention, such “beading” activity comprising the well-known phenomenon of a droplet of fluid on a heated surface appearing to “bounce” from place to place on the surface. 
     Liquid employed in connection with the invention may be of a wide variety. For cleaning, water may be employed, and superheated steam generated in accordance with the invention may be used to loosen or dissolve dirt on, for example, machine surfaces, circuit boards, or in living or work areas. Additives stable at operating temperatures of vapor generators in accordance with the invention, such as detergents or disinfectants, may be employed. The solution may contain vaporizers, emulsifiers, degreasers, oxidants, alkalis, deodorizers, antiseptics, germicides or the like. Other components of the solution may comprise humidifiers, fresheners, and other reagents to be injected into the air or onto a surface or object. Proportions of additives and solvent may be adjusted in particular applications. 
     Particular applications comprise cleaning of equipment, circuit boards and/or surfaces and spaces such as rooms in connection with maintenance or janitorial work. 
     Superheated vapor generators in accordance with the invention may be employed in connection with burnishing or cleaning of small parts such as timepiece apparatus, in connection with metal plating, printing and photo-engraving, lapidary and stonecutting activity, manufacture and/or repair of electronic components, removal of such things as wallpaper, labels and the like, in connection with dry-cleaning, sanitizing and sterilizing of eating implements, in connection with optical and optometric laboratory and office work, with jewelry, dental and medical offices and operating theatres,miniature instrument manufacture and repair, and biological and analytic laboratories, among many other applications. 
     A particularly useful application of the invention is in connection with cleaning and maintenance of military equipment, including weapons and related items. This has become timely in view of the current emphasis on repair and maintenance as opposed to acquisition of new items. 
     Superheated vapor may issue at approximately 150 PSI from a vapor generator in accordance with the invention. The superheated vapor impinges upon, and into such relatively hard-to-reach spaces as portholes, crevices, and the like. Application of heat causes contaminants to soften, liquify, and generally decompose or disengage from the surfaces on which they are disposed. This applies to such normally hard-to-clean substances as grease, oil, grime, paste, glue, and carbon. A burst of superheated vapor, such as steam used in cleaning, lasting 5-10 seconds, is sufficient for many cleaning purposes. In particular applications, bursts of superheated vapor produced by the system  10  will last approximately 15-30 seconds. When vapor generators are combined as described in connection with FIG. 6, exudate of vapor/steam may be at such pressures as may be necessary for cleaning or other applications For removal of tenacious contaminants, heat applied by the invention initiates cleaning after which a cleaner or emulsifier may be applied, at which point a further application of superheated vapor from the invention completes removal of the contaminant. 
     Other applications for the invention are, among others, lubrication, particularly of relatively inaccessible and small parts. Lubrication applied in this manner is effective hot lubrication, the surface having been first cleaned by use of the invention in a cleaning mode, and lubricant being applicable by disposing lubricant on the now clean, heated parts by conventional means the part then being subjected to a stream of superheated vapor, causing the lubricant to be dispersed evenly throughout and upon the object to be lubricated. 
     A method for fabricating a superheated vapor generator in accordance with the invention is depicted FIG.  7 . Two separate, preferably semicylindrical, bodies in the form of castings are provided. The castings will have been fabricated to define the holes (and ridges and grooves, if desired) described hereinabove. The parts are then welded together, forming a superheated vapor generator in accordance with the invention. The parts and therefore the vapor generator may be composed of aluminum or stainless steel or other heat-conductive material. Alternatively, the bodies may be machined, as opposed to being castings. 
     As described above, an improved superheated vapor generator and a method for fabrication thereof, have been provided. Though particular embodiments are described and depicted herein, the invention and the scope thereof are defined by the appended claims interpreted in light of the specification and drawings.