Abstract:
A method for producing a spray jet from a liquid/gas mixture with a two-component nozzle having a nozzle housing, including the steps of blending a supplied liquid and a supplied gas and producing a spray jet consisting of gas and liquid drops, producing a gas jet and mixing of gas jet with the spray jet.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This claims priority from German Application No. 10 2015 200 236.5, filed on Jan. 12, 2015, the disclosure of which is hereby incorporated by reference in its entirety into this application. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a method for producing a spray jet from a liquid/gas mixture with a two-component nozzle having a nozzle housing, with the steps of blending a supplied liquid and a supplied gas and producing a spray jet consisting of gas and liquid drops. The invention also relates to a two-component nozzle for spraying a liquid/gas mixture with a nozzle housing, wherein the nozzle housing has at least one liquid inlet, at least one gas inlet and at least one outlet opening, and wherein, during operation of the nozzle, a spray jet consisting of gas and liquid drops is present downstream of the at least one outlet opening. 
       BACKGROUND OF THE INVENTION 
       [0003]    Two-component nozzles with an inner mixing chamber have a spray jet which has a core jet and an outer jet surrounding the core jet. The core jet and the outer jet can entirely merge together; as a rule, the core jet is distinct in the case of two-component nozzles. If such a spray jet enters a process surroundings, the drops in the core jet enter into the heat and substance exchange with the process surroundings only with a delay. As a result, evaporation distances are extended. Above all, it can be observed in the case of conventional two-component nozzles with an inner mixing chamber that large drops form in the core jet of the spray jet after exiting from the nozzle housing. 
       SUMMARY OF THE INVENTION 
       [0004]    With the invention, a method for producing a spray jet and a two-component nozzle are intended to be improved in respect of avoiding large drops in the core jet of the spray jet. 
         [0005]    In the case of a method according to the invention for producing a spray jet from a liquid/gas mixture with a two-component nozzle having a nozzle housing, with the steps of blending a supplied liquid and a supplied gas and producing a spray jet consisting of gas and liquid drops, the producing of at least one gas jet and mixing of the gas jet with the spray jet is provided. 
         [0006]    Therefore, by a gas jet being mixed with the spray jet, the liquid drops present in the spray jet can be additionally atomised by the gas jet. As a result, the formation of large drops in the spray jet can be prevented. 
         [0007]    In a development of the invention, the spray jet has a core jet and an outer jet surrounding the core jet, wherein the gas jet is first of all mixed with the core jet of the spray jet. 
         [0008]    Since large drops may occur specifically in the core jet of the spray jet of a two-component nozzle, the mixing of the gas jet first of all with the core jet of the spray jet is particularly advantageous. This is because the gas jet then reliably provides further atomisation or division of the large drops in the core jet. Although the gas jet has already lost kinetic energy before passing into the region of the outer jet, this is non-critical, since the large drops located in the outer jet can be prevented, for example, by providing an annular nozzle surrounding the nozzle housing and therefore by using annular air. 
         [0009]    In a development of the invention, the blending of the liquid and the gas within a mixing chamber of the nozzle housing and the mixing of the gas jet with the spray jet downstream of the mixing chamber are provided. 
         [0010]    In a development of the invention, the mixing of the gas jet with the spray jet takes place within the nozzle housing. 
         [0011]    Alternatively, the mixing of the gas jet with the spray jet can take place outside the nozzle housing. 
         [0012]    The mixing of the gas jet can take place within or outside the nozzle housing depending on the existing space conditions and depending on the respectively applicable requirements regarding the drop size. 
         [0013]    In a development of the invention, introducing the gas jet into a core jet of the spray jet in the form of a plurality of partial flows is provided, wherein the plurality of partial flows have a main movement component which is directed radially outwards with respect to a central longitudinal axis of the spray jet. 
         [0014]    A division of the gas jet into a plurality of partial flows which are each directed radially outwards provides complete division of possible large drops in the core jet into finer drops. 
         [0015]    In a development of the invention, the dividing of a gas, which is supplied to the two-component nozzle, within the nozzle housing into a first gas flow and a second gas flow is provided, wherein the first gas flow is provided for producing the spray jet, and the second gas flow is provided for producing the gas jet which is mixed with the spray jet. 
         [0016]    The two-component nozzle therefore merely has to be supplied with gas of uniform pressure. The division into two gas flows then takes place within the nozzle housing. 
         [0017]    In the case of a two-component nozzle according to the invention for spraying a liquid/gas mixture with a nozzle housing, wherein the nozzle housing has at least one liquid inlet, at least one gas inlet and at least one outlet opening, and wherein, during operation of the nozzle, a spray jet consisting of gas and liquid drops is present downstream of the at least one outlet opening, at least one further gas outlet opening is provided for producing a gas jet, wherein the further gas outlet opening is designed and arranged in a manner so as to mix the gas jet with the spray jet. 
         [0018]    By provision of at least one further gas outlet opening, the gas jet can be mixed with the spray jet, and the production of large drops within the spray jet can be reliably prevented by the additional atomisation of the drops in the spray jet by means of the gas jet. 
         [0019]    In a development of the invention, the nozzle housing has a mixing chamber, wherein the liquid inlet and the gas inlet lead into the mixing chamber, and wherein the at least one further gas outlet opening is arranged downstream of the mixing chamber and concentrically with respect to the mixing chamber. 
         [0020]    By means of such an arrangement of the at least one further gas outlet opening, the gas jet can be mixed with the core jet of the spray jet. 
         [0021]    In a development of the invention, the nozzle housing has an outlet opening for the spray jet, wherein the at least one further gas outlet opening is arranged downstream of the outlet opening. 
         [0022]    In a development of the invention, the at least one further gas outlet opening is arranged upstream of the outlet opening. 
         [0023]    Alternatively, the at least one further gas outlet opening is arranged downstream of the outlet opening. 
         [0024]    Depending on the existing space conditions and the requirements regarding the drop size in the spray jet, the at least one further gas outlet opening can be arranged within the nozzle housing, i.e. upstream of the outlet opening, or outside the nozzle housing, i.e. downstream of the outlet opening. 
         [0025]    In a development of the invention, the at least one further gas outlet opening is arranged in the region of the free end of a tube which is fastened to the nozzle housing concentrically with respect to the outlet opening. 
         [0026]    By means of a simple tube arranged concentrically with respect to the outlet opening, the at least one further gas outlet opening can be realised in a simple manner and placed centrally with respect to the core jet. 
         [0027]    In a development of the invention, the tube is provided at the free end thereof with a deflecting plate or a deflecting body and with a plurality of outflow openings directly upstream of the deflecting plate or the deflecting body. 
         [0028]    In this way, it is possible to produce a plurality of gas jets which are directed with a main component radially outwards and can then bring about atomisation of large drops within the spray jet. A cone expanding in the flow direction can be used, for example, as deflecting body. The direction of the emerging gas jets can be varied via the cone angle. 
         [0029]    In a development of the invention, a plurality of outflow openings open radially outwards with respect to a central longitudinal axis of the tube. 
         [0030]    As a result, the plurality of gas jets first of all obtain a radially outwardly directed movement, but are carried along by the spray jet during operation of the two-component nozzle, wherein the main component of the gas jets still remains directed radially outwards. 
         [0031]    In a development of the invention, an annular gap surrounding the outlet opening is provided. 
         [0032]    By means of an annular gap, the spray jet can still be shielded in relation to the process surroundings immediately after exiting from the outlet opening if enveloping air exits from the annular gap. However, the annular gap can also be used, for example, to prevent the formation of drops in a region surrounding the outlet opening. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    Further features and advantages of the invention emerge from the claims and the description below in conjunction with the drawings. Individual features of the various embodiments explained in the description with reference to the drawings can be combined with one another in any manner without exceeding the scope of the invention. In the drawings: 
           [0034]      FIG. 1  shows a side view of a two-component nozzle according to the invention, 
           [0035]      FIG. 2  shows a sectional view of the plane II-II in  FIG. 1 . 
           [0036]      FIG. 3  shows a sectional view of the plane in  FIG. 1 . 
           [0037]      FIG. 4  shows the enlarged view of a detail of the two-component nozzle of  FIG. 1 . 
           [0038]      FIG. 5  shows a sectional view of a two-component nozzle according to the invention in accordance with a second embodiment of the invention. 
           [0039]      FIG. 6  shows a sectional view of a two-component nozzle according to the invention in accordance with a third embodiment, and 
           [0040]      FIG. 7  shows a sectional view of a two-component nozzle according to the invention in accordance with a fourth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0041]    The illustration of  FIG. 1  shows a two-component nozzle  10  according to the invention with a nozzle housing  12 . The nozzle housing  12  has an outlet opening  14  from which a spray jet of liquid drops and gas emerges during operation of the two-component nozzle  10 . Liquid to be atomised is supplied to the two-component nozzle  10  via a liquid inlet  16 , wherein the liquid is conducted downstream of the liquid inlet  16  into a mixing chamber and atomised there. The liquid inlet  16  is provided with an external thread for the connection of a liquid supply line. 
         [0042]    The liquid inlet  16  is provided with an annular gas inlet  18  through which gas, for example compressed air or water vapour, is supplied to the nozzle housing  12 . The nozzle housing is provided with an internal thread on the outer wall of the gas inlet in order to be able to connect a gas supply line. 
         [0043]    The nozzle housing  12  is of two-part design and has an outer shell  20  and an insert  22 . The insert  22 , at the left end thereof in  FIG. 1 , has the liquid inlet  16  and is inserted into the outer shell  20 . The annular gas inlet  18  is formed between the insert  22  and the outer shell  20 . 
         [0044]    As can be seen in  FIG. 1 , immediately before the beginning of the outer shell  20 , the insert  22  is provided with a total of eight gas channels  24  which are directed radially inwards. A gas flow is branched off by means of the gas channels  24 , the gas flow then exiting again from a plurality of outflow openings  26  downstream of the outlet opening  14  and forming a plurality of gas jets which then mix with the spray jet emerging from the outlet opening  14 . For this purpose, the gas channels  24  lead into a tube  30  which is arranged concentrically with respect to a central longitudinal axis  28  and at the free end of which a deflecting plate  32  is arranged. The plurality of outflow openings  26  are arranged directly upstream of the deflecting plate  32 . 
         [0045]    The illustration of  FIG. 2  shows a view of the section plane II-II in  FIG. 1 . The two-part construction of the nozzle housing  12  from the outer shell  20  and the insert  22  inserted into the outer shell  20  can be seen. The annular gas inlet  18  and the liquid inlet  16  can readily be seen. The gas channels  24  lie outside the section plane II-II, and therefore they cannot be seen in the view of  FIG. 2 . However, the gas channels  24  lead into an annular channel  26  which is provided in a stopper  38  which, in turn, is screwed into the insert  22  concentrically with respect to the central longitudinal axis. From the annular channel  36 , the gas flow branched off by means of the gas channels  24  passes into the interior space of the tube  30  and thereby passes to the outflow openings  26  at the free end of the tube  30 . As has already been explained, a substantially radially directed gas jet emerges from each of the outflow openings  26  at the end of the tube  30 . During operation of the two-component nozzle  10 , said plurality of gas jets then cross the spray jet which emerges from the outlet opening  14 . 
         [0046]    During operation of the nozzle, the spray jet is produced by blending gas and liquid in a mixing chamber  40 , through which the tube  30  passes. The gas inlet  18  leads into an annular space  42  from which a plurality of gas inlets  44  lead into the mixing chamber. The gas inlets lead radially into the mixing chamber  40 , which has a shape widening in a circular-conical-shaped manner. As a result, gas flows emerging from the gas inlets  44  are directed radially inwards and substantially at right angles cross a liquid flow entering the mixing chamber  40 . 
         [0047]    The stopper  38  is provided with a plurality of liquid inlets  46  which are arranged concentrically around the tube  30 . This can be seen in the view of  FIG. 3  which shows a view of the section plane in  FIG. 1 . 
         [0048]    From the total of eight liquid inlets  46 , a respective liquid flow therefore enters the mixing chamber  40  parallel to the longitudinal axis  28 . Gas flows from the gas inlets  44  impinge on the plurality of liquid flows at right angles and produce a gas/drop mixture within the mixing chamber  40 . The mixing chamber is tapered at the end thereof located downstream, wherein said tapering is brought about by a circular-conical-shaped section  48 . The circular-conical-shaped section  48  is substantially shorter than the mixing chamber  40 . In the embodiment illustrated, the length of the tapering  48  is less than one tenth of the length of the mixing chamber  40 . The tapering  48  is adjoined by a cylindrical section  50  which forms a narrowest cross section within the nozzle housing  12 . The length of the cylindrical section  50  is approximately one third of the length of the mixing chamber  40 . The cylindrical section  50  is adjoined by a section  52  which widens conically and ends at the outlet opening  14 . The length of the section  52  is approximately three to four times the length of the cylindrical section  50  and, in the embodiment illustrated, corresponds approximately to the length of the mixing chamber  40 . 
         [0049]    The outlet opening  14  is surrounded by a groove  54  which is triangular in cross section and is intended to prevent drops from adhering to the housing  12  in the region surrounding the outlet opening  14 . 
         [0050]    In the illustration of  FIG. 3 , the annular space  42  between the insert  22  and the outer shell  20  of the nozzle housing  12  can be seen. Gas is introduced into said annular space  42 . As has been explained, a gas flow is branched off from said annular space  42  by means of the total of eight gas channels  24  which are provided in the insert  22  and extend radially inwards. The gas channels  24  lead into the annular channel  36  which is formed in the stopper  38 . The stopper  38  is inserted, see  FIG. 2 , into the insert  22 . Starting from the annular channel  36 , four further gas channels  56  are provided in the stopper  38 , said gas channels being directed radially inwards and leading into the interior space of the tube  30 . Gas therefore passes from the annular space  42  through the gas channels  24 , into the annular channel  36 , into the gas channels  56  and into the interior space of the tube  30 . As has already been explained, the gas then emerges substantially radially at the free end of the tube  30  through the plurality of outflow openings  26 . 
         [0051]    As has been explained, a gas/liquid drop mixture is produced within the mixing chamber  40  and then passes through the cylindrical section  50  and the conical widening  52  as far as the outlet opening  14  and emerges there as a spray jet. The spray jet of the two-component nozzle  10  has a core jet and an outer jet surrounding the core jet. Large drops may occur here in the core jet of the spray jet; above all, it is possible for large drops again to form in the core jet of the spray jet after emerging from the outlet opening  14 . Such large drops in the core jet of the spray jet are split again into smaller drops by the gas jets which emerge substantially radially outwards from the outflow openings  26 . The gas jets emerging from the outlet openings  26  therefore cross the spray jet in order to prevent the formation of large drops within the spray jet or to reverse the formation thereof. Owing to the arrangement of the tube  30  on the central longitudinal axis of the two-component nozzle  10 , the gas jets emerging from the outflow openings  26  first of all cross the core jet of the spray jet and subsequently the outer jet thereof. 
         [0052]    The illustration of  FIG. 4  shows an enlarged detail of the two-component nozzle  10  of  FIG. 1 . Specifically, the free end of the tube  30  with the deflecting plate  32  and the plurality of radially outwardly directed outflow openings  26  is illustrated in detail. The deflecting plate  32  is provided, see  FIG. 2 , with an extension which is pushed into the free end of the tube  30  and is anchored there. The outflow openings  26  are also provided on said insert. The tube  30  can therefore be constructed in a very simple manner structurally. The insert is pushed into the free end of the tube, as a result of which the deflecting plate  32  and the outflow openings  26  are placed on the free end of the tube  30 . 
         [0053]    The illustration of  FIG. 5  shows a two-component nozzle  60  according to a second embodiment of the invention. The two-component nozzle  60  differs from the two-component nozzle  10  of  FIG. 1  only in that the free end of the tube  30  with the deflecting plate  32  and the outflow openings  26  is arranged upstream of the outlet opening  14 . The free end of the tube  30  and the outflow openings  26  are therefore still arranged within the outer shell  20  of the nozzle housing  12 . The gas jets emerging from the outflow openings  26  therefore cross the spray jet, which is present in the conically widening section  52  of the nozzle housing  12 , still within the nozzle housing  12 . 
         [0054]    Otherwise, however, the two-component nozzle  60  is constructed identically to the two-component nozzle  10  of  FIG. 1 . The individual components and the manner of operation of the two-component nozzle  60  are therefore not explained again. 
         [0055]    The illustration of  FIG. 6  shows a sectional view of a two-component nozzle  70  according to a third embodiment of the invention. The two-component nozzle  70  differs from the two-component nozzle  10  of  FIG. 1  only by the presence of an annular gap cap  72  which, with the nozzle housing  76 , forms an annular gap  74  surrounding the outlet opening  14 . The annular gap  74  is fed with enveloping air. The spray jet emerging from the outlet opening  14  can thereby be shielded directly downstream of the outlet opening  14  in relation to process surroundings. Furthermore, it is also possible by means of enveloping air emerging from the annular gap  74  to atomise drops forming on that region of the nozzle housing  76  which surrounds the outlet opening  14  into fine drops. The nozzle housing  76  is formed with significantly thinner walls in the region thereof surrounding the outlet opening  14  than the nozzle housing  12  of the two-component nozzle  10 . The annular gap cap  76  extends for a distance, as seen in the flow direction, beyond the end of the nozzle housing  76 . As a result, the atomising of drops which accumulate on the nozzle housing  12  in the region surrounding the outlet opening  14  is facilitated and the outer edge of the nozzle housing  76  is protected against mechanical damage. 
         [0056]    Otherwise, the two-component nozzle  70  is formed identically to the two-component nozzle  10  of  FIG. 1 , and the individual components of the two-component nozzle  10  and the function thereof are not explained again. 
         [0057]      FIG. 7  shows a two-component nozzle  80  according to the invention in accordance with a fourth embodiment of the invention. In contrast to the two-component nozzle  70  of  FIG. 6 , the free end of the tube  30  is arranged within the nozzle housing  76 . The gas jets emerging from the outflow openings  26  at the free end of the tube  30  therefore cross the spray jet still within the nozzle housing  76 , as has already been explained with reference to the two-component nozzle  60  of  FIG. 5 . Also in the case of the two-component nozzle  80 , the provision of the annular gap  74  between the annular gap cap  72  and the nozzle housing  76  ensures that liquid drops accumulating in that region of the nozzle housing  76  which surrounds the outlet opening  14  can be split and therefore atomised into small drops. Otherwise, the individual components and the function of the two-component nozzle  80  are identical to the two-component nozzle  10  of  FIG. 1  and are therefore not explained again.