Abstract:
A device for continuous heating of fluids, using steam, includes a first tubular circuit, having one inlet and one outlet, in which to fluid or mixture of liquids with gases to be heated is circulated, and a second tubular circuit in which the heating steam is circulated. The first tubular circuit comprises a section that is helically wound around a section of the axial length of a hollow first cylindrical body, closed at both ends. The device further comprises a hollow second hollow cylindrical body in which said first cylindrical body and said helically wound section are coaxially housed. The second cylindrical body is closed at both ends and has radial passageways communicating between the cavity of said first cylindrical body and the cavity of said second cylindrical body. The first cylindrical body, second cylindrical body and radial passageways forming part of said second tubular circuit.

Description:
BACKGROUND 
     Technical Field 
       [0001]    The present disclosure relates to a device for continuous heating of fluids, or mixtures of liquids with gases, using steam, comprising a first tubular circuit, having one inlet and one outlet, in which the fluid or mixture of liquids with gases to be heated is circulated, and a second tubular circuit in which the heating steam is circulated. 
         [0002]    Particularly, the liquid to be heated may be milk or chocolate and the mixture with gases is preferably milk frothed with air. 
       Description of the Related Art 
       [0003]    As used herein, the term continuous heating is intended to designate heating that is carried out while the two fluids, the fluid to be heated and the heating fluid, flow co-currently or counter-currently through the device, each in its own circuit. 
         [0004]    In the prior art, for instance as disclosed in EP 0485350, the circuit, in the form of a tubular conduit, in which the fluid to be heated is circulated, is placed within the circuit, also in the form of a tubular conduit, in which steam is circulated and heat exchange occurs by convection and mainly by conduction between the walls of the tubular elements that form the circuits with the fluids flowing therein. 
         [0005]    Nevertheless, this technical solution has the functional drawback that the steam condensate formed along the conduit cannot be easily removed from the steam flow because such flow, in this technical solution, forces the condensate to move along the outer perimeter of the conduit in which the liquid to be heated flows, and will likely cause it to build up toward the upper portion of the conduit. 
         [0006]    The presence of condensate creates a heat-insulating effect which reduces heat exchange, and cannot ensure that liquid maintains a constant temperature during heating. 
         [0007]    Furthermore, as condensate is dropped by gravity, the steam flow inlet may be blocked, and cause the flow to be irregular. 
         [0008]    A different arrangement, which nevertheless requires part of the heating fluid, i.e. steam, to be introduced into the fluid to be heated, is disclosed in US 2014/0299001 A1. According to this arrangement, the tubular conduit for the flow of steam is concentrically placed within the tubular conduit for the flow of fluid to be heated, and a plurality of radial holes, arranged along the axial extent thereof and opening into the conduit of the fluid to be heated, are disposed in the wall of the steam conduit. 
         [0009]    This known technical heating arrangement involves the drawback that water is added into the liquid to be heated, thereby diluting it. 
         [0010]    This drawback is particularly significant if the liquid being heated is milk or a mixture of milk and air to provide frothed milk. 
         [0011]    In fact, the impact of steam, though throttled, against the milk and air stream during heating, is deemed to be a cause of the impossibility of achieving highly compact foams, as is typical in cold frothing, due to the kinetic effect of steam molecules on the air molecules in the milk and air mixture. 
         [0012]    Furthermore, the dilution of the protein contents in milk decreases the ability thereof to form foam. 
       BRIEF SUMMARY 
       [0013]    The object of the present disclosure is to provide a device for continuous heating of fluids using steam without allowing it to be mixed with the fluid to be heated, thereby avoiding the kinetic effect associated with the water molecules in steam and the consequences of such effect on the milk and air mixture. 
         [0014]    A further object is to allow removal of the condensed liquid without disassembling the device, thereby facilitating cleaning of the parts of the device and ensuring efficient and regular heating. 
         [0015]    Also, according to an alternative embodiment of the device, a further object of the disclosure is to allow heating intensity to be adjusted as needed and according to the flow rate of the fluid to be heated as well as the nature and composition of the fluid itself. 
         [0016]    These and other objects, as better explained hereafter, are fulfilled by the continuous heating device of the disclosure, as defined in the accompanying claim  1 . 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0017]    The disclosure will be now described in greater detail with reference to certain preferred embodiments thereof as shown in the annexed drawings, given by way of illustration and without limitation, in which: 
           [0018]      FIG. 1  shows a perspective view of the outer structure of the heating device; 
           [0019]      FIG. 2  shows a longitudinal sectional view of the device of  FIG. 1 ; 
           [0020]      FIG. 3  schematically shows an alternative embodiment of the portion of the heating fluid conduit within the device that allows adjustment of the heating fluid flow; 
           [0021]      FIG. 4  schematically shows a further embodiment of the portion of the heating fluid conduit within the device that allows adjustment of the heating fluid flow. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Referring to the above figures, the heating device, according to its embodiment as shown in the longitudinal section of  FIG. 2 , comprises a first hollow cylindrical body  1  and a tubular section  2 , which is helically would around at least one section of the axial length of said first hollow cylindrical body. 
         [0023]    Preferably, the helically wound section consists of a steel or copper tube whose outside diameter ranges from 2.4 mm to 4.0 mm and whose inside diameter ranges from 2.0 mm to 3.6 mm. 
         [0024]    The section that is wound into a cylindrical helix is part of the first tubular circuit for the flow of the heating fluid, particularly milk with or without the addition of air and extends, preferably but without limitation, to a length ranging from 700 mm to 1700 mm. 
         [0025]    Preferably, the cylindrical shape that defines the section  2  wound around the first hollow cylindrical body  1  has an inside diameter that is greater than the outside diameter of said first hollow cylindrical body  1  and forms a gap  2   a  therewith. 
         [0026]    The device further comprises a second hollow cylindrical body, referenced  3 , which is part of the tubular circuit for the flow of the heating fluid, particularly steam. Said second cylindrical body  3  coaxially houses both said first hollow cylindrical body  1  and said helically wound section  2 . The end  4  of the hollow body  1  is equipped with a flange-like closing wall  5  with a hole  6  connected to the connection  7  with a steam source, not shown and known per se. 
         [0027]    The end  8 , which is rigidly joined to the hollow cylindrical body  3 , encloses the flange-like wall  5  and the end  4  of the hollow body  1 , with a seal  9  interposed therebetween. Such flange-like wall  5  is fastened to the end  8  by screws  10  which engage, by means of respective washers  11 , above the edge  12  of the flange-like wall  5  of the cylindrical body  1 . 
         [0028]    The screws, like the one referenced  10  in  FIGS. 1 and 2 , are arranged around the edge  12  and engage in corresponding holes  10   a  formed on the end  8  of the cylindrical body  3 . 
         [0029]    The opposite end  13  of the cylindrical body  1  is closed by a shank  14  which axially fits into the cavity of the cylindrical body  1  with the interposition of an annular seal  15 . 
         [0030]    The shank  15  is rigidly joined to a flange  16  which closes the end  18  of the second hollow cylindrical body  3 , with the interposition of an annular seal  17 . 
         [0031]    The flange  16  has an opening  19  with which the connection  20  is sealingly connected to allow the heating fluid and, as more clearly explained below, the condensate, to flow out of it and into the cavity of the second cylindrical body  3  through a plurality of radial passageways  21  formed in the wall of the first cylindrical body  1 . 
         [0032]    Preferably, these radial passageways consist of circular holes with a diameter ranging from 0.5 mm to 2.0 mm, which are axially and circumferentially arranged in the wall of the cylindrical body  1 , and whose number depends on the heating requirements to be met by the device and, as a result, on the amount of steam to be dispensed. 
         [0033]    The flange  16  also has a further passageway  22  through which the end  24  of the helically wound tubular section  2  sealingly fits, by means of a seal  23 , the other end  25  coming out of the cylindrical body  3  through the opening  26 , with a seal  27 , formed in the end  8 . 
         [0034]    The end  24  and the end  25  respectively form the inlet and the outlet or conversely the outlet and the inlet of the first tubular circuit for the flow of fluid to be heated, particularly milk, which may or may not be frothed with air, and which comes from a source and is directed to a point of use thereof, not shown in the drawings. 
         [0035]    Said first hollow cylindrical body  1 , said second hollow cylindrical body  3  and said radial passageways  21  form part of said second tubular circuit. 
         [0036]    According to the disclosure, the wall of the hollow cylindrical body  1  also has a through hole  28  that opens into the second hollow cylindrical body  3  external to the section  2  that is wound into a cylindrical helix and hence proximate to the opening  19  connected to the outlet connection  20  of the steam flow. 
         [0037]    The through hole  28  has a diameter equal to or smaller than the diameter of the passageways  21  and has the purpose of discharging the condensate formed along the wall of the cylindrical body  1  and collected both by gravity and by pressure difference between the portions upstream and downstream from the heating fluid circuit. 
         [0038]    The discharge occurs within said body  1  level with the outlet connection  20 , and the condensate formed around the helically wound tubular conduit  2  also flows proximate thereto, after being removed by the steam flow that comes from the passageways  21  and radially impinges upon the walls of such helically wound conduit  2 . 
         [0039]    The walls, with their surfaces free of condensate, increase their heat exchange efficiency. 
         [0040]    The flow rate of the heating fluid, particularly steam, may be adjusted in various manners. 
         [0041]    One of these manners consists in the provision of an electrically controlled proportional variable-flow or a shape-memory valve, which is inserted, as is known in the art, in the steam feed conduit and is managed by a conventional control processing unit (CPU). 
         [0042]    As an alternative to the use of the variable-flow valve, the flow of the heating steam may be adjusted by mechanically changing the number of passageways  21  that will be kept opened between the cylindrical body  1  and the cylindrical body  3 . 
         [0043]    Referring to  FIG. 3 , which schematically shows an alternative embodiment of the portion of the heating fluid conduit within the device, for adjustment of the flow of the heating fluid, it may be noted that the hollow cylindrical body  1  has means for closing at least one group of said radial passageways  21  and obviously leaving the remaining passageways open. 
         [0044]    Still referring to  FIG. 3 , the device comprises a third hollow cylindrical body  29  penetrating the first hollow cylindrical body  1  through its end closed by the plate  8 . 
         [0045]    Said third cylindrical body  29  in turn comprises a closed end  30  thereof located outside said first hollow cylindrical body  1  and an opposite open end  31  located inside said first cylindrical body  1  and communicating with the cavity thereof. 
         [0046]    Said third cylindrical body  29  is mounted in telescopically sliding fashion, as shown by the double arrow F, with a radial sealing effect relative to the cavity of said first cylindrical body  1 , provided, for instance, by an O-ring  32 , and can be axially locked in a given position according to the number of said radial passageways  21  to be kept closed, referenced  21   a,  between said radial seal  32  and the closed end of the flange  5  of the cylindrical body  1 , 
         [0047]    Obviously, the connection  7  with the steam source shall be deemed to be mounted to the closed end  30  of the third hollow cylindrical body  29  and to open into it, possibly with a flexible element interposed therebetween, to allow axial movement of said third cylindrical body  29 . 
         [0048]    A further embodiment of the portion of the heating fluid conduit within the device that allows adjustment of the heating fluid flow is schematically shown in  FIG. 4 . 
         [0049]    Referring to this figure, it shall be noted that the wall of the hollow cylindrical body  1  has groups  21   b   1 ,  21   b   2 ,  21   b   3  and  21   b   4  of radial openings, separate from each other and disposed in respective helical arrangements, referenced A, B, C and D in  FIG. 4 , in the wall of the body  1 . A different third cylindrical tubular body  33  is designed to be coaxially accommodated within the body  1 . 
         [0050]    Steam is conveyed to the body  33  at its end  34  via a flexible connection element, not shown. Said cylindrical body  33 , whose bottom  34   a  is closed, has a series of windows  35   b   1   35   b   2 ,  35   b   3  and  35   b   4  formed therein, which have a 90° angular offset from each other and are axially spaced to correspond to as many helical sequences A, B, C and D of passageways  21   b.  As the cylindrical body  3  is angularly displaced, each of the windows  35   b   1 ,  35   b   2 ,  35   b   3  and  35   b   4  progressively opens the holes of the sequences of holes  21   b   1 ,  21   b   2 ,  21   b   3  and  21   b   4 , thereby allowing a homogeneous distribution of steam in both radial and axial directions toward the conduit  2  for the flow of the fluid to be heated. 
         [0051]    Each incremental adjustment interval corresponds, for each window, to an increasing and equal number of open passageways  21   b.    
         [0052]    As a result, the flow of steam is only conveyed to the passageways that communicate with their respective facing window, whereas all the other passageways are closed. 
         [0053]    For easier selection of the angular position of the windows  35   b   1 ,  35   b   2 ,  35   b   3  and  35   b   4  and hence of steam diffusion within the body  1 , a numbered ring nut  36  is provided on the end  34  of the tubular body  33 . The angular displacement of the body  33  may be obtained manually or, alternatively, also by means of a motor, the amount of displacement being selected by programmed control of the CPU. 
         [0054]    It will be appreciated from the above that the heating device of the present disclosure can provide programmed heating of the fluid to be heated and also achieves the purpose of effectively removing the condensate using the flow of steam itself, which flows along the the conduit for the fluid to be heated thereby ensuring high functionality of the device. 
         [0055]    The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.