Abstract:
A nozzle assembly provides a high pressure dispersion of water particles in a misting process. The nozzle includes multiple arrayed discharge outlets into a single mixing zone wherein the discharge outlets are concentrically arranged alternating between water and gas streams. The mist from the novel arrangement is highly dispersed, providing excellent gas cooling operation with minimal maintenance.

Description:
The present invention relates generally to the design of two-phase nozzles and, more particularly, nozzles for developing a finely divided mist of water using air as a propellant. 
     BACKGROUND OF THE INVENTION 
     Brief Description of the Prior Art 
     Due to enormous number of diverse applications, nozzle design is a fairly mature area of development with a wide variety of arrangements that have evolved over the years. Recently, sophisticated design techniques employing the latest test equipment and arcane mathematical algorithms for fluid dynamic modeling have imparted a new approach to nozzle design. Notwithstanding this design approach, the complexity of the system defies effective mathematical modeling and the design of nozzles remains more art than science--with heavy reliance on trial and error for advancing and fine tuning any given approach. Often the expected successful design fails while inexplicably simple variations thereof succeed. 
     Nozzles are used in different ways for different purposes; but all have in common the release of a high pressure fluid into a lower pressure environment. Of particular interest in the present discussion is the use of nozzles to provide a finely divided mist of water, i.e., in droplet form where the individual droplets are very small and uniform. The use of finely divided water droplets are of significant commercial value in gas cooling towers where a high temperature gas (2000° Fahrenheit) must be rapidly cooled to approximately 200°. Introducing a finely divided mist of water droplets into the gas stream causes the water to evaporate--almost instantaneously--soaking up heat energy via the phase change in the process and reducing the gas stream temperature dramatically. 
     However, gas cooling with a water droplet stream that comprises relatively large droplets creates secondary problems. The large droplets take significantly longer to evaporate and many simply don&#39;t. These residual droplets collect dust and other particulate matter in the gas stream and coalesce on the tower wall or floor, creating deposits that require separate cleaning and disposal. This maintenance can become a significant expense in the overall economics of the cooling process. 
     Most misting nozzles for gas cooling employ air as a propellant to the water, to increase discharge velocity and provide for enhanced disbursement of the individual droplets as formed. Air is supplied at about the same pressure as the water, and thus, must be pressurized via air compressors or similar--equipment that is both capital intensive per unit capacity and energy intensive. This leads to fairly high operating costs per unit capacity. Air is otherwise not an important component of the system, and thus, it is often a critical design criteria for nozzle designers to develop systems that minimize the amount of air required without diminished performance. 
     Another important aspect of the use of nozzles in gas cooling relates to their expected lifespan. Many gas cooling towers exist in a highly abrasive and/or corrosive environment as sulfuric acid and other corrosive gases invariably come in contact with the nozzles. To extend the life of the nozzles, the materials of construction will include specialized metals (e.g., hastalloys) or ceramics. These materials extend life and thus reduce maintenance, but are difficult to precisely machine. Moreover, the nozzles themselves must be disconnected, inspected and reinstalled to insure good long term performance. This inspection work is done in a nasty plant environment by semi-skilled personnel, with the potential for faulty reinstallation of the nozzle and ancillary equipment. Nozzle design, therefore, must consider the limitations associated in machining certain materials implicated by such environments and further provide a design that is easy to install without error or misconnection. 
     It was with the above understanding that the present invention was made. 
     OBJECTS AND SUMMARY OF THE PRESENT INVENTION 
     It is an object of the present invention to provide a nozzle system that provides a finely divided mist spray with a low volume of propellant. 
     It is another object of the present invention to provide a nozzle system that provides interchangeable fluid inlet connections without disturbing the performance of the nozzle in its intended application. 
     It is a further object of the present invention to provide a nozzle design that is manufactured in a reduced amount of time and with a reduced number of machining steps. 
     It is a further object of the present invention to provide a nozzle design that is machinable out of difficult to machine materials of construction. 
     The above and other objects of the present invention are realized in a nozzle design that provides two interchangeable inlet lines, one for the propellant air and the other for the liquid phase--water. The inlet lines separately feed a distributed angled array of turbulent zone feeders with the array of feeders alternating in feed stream source between water and air. The turbulent zone extends forward towards an extended constriction zone, which is followed by an outlet flair and an impact dispersing plate. Air and water are concurrently fed to the inlet lines at about the same line pressure. The distributed array of inlets introduce the air and water into the turbulent mixing zone in a controlled alternating vortex creating a homogenized two-phase fluid stream. The two-phase stream travels outward through the constriction zone, out the nozzle exit and against the dispersion plate, causing the intermixed stream to rapidly accelerate and break up into a finely divided mist of droplets having a narrow particle size distribution and a mean diameter in the micron size range. 
     In accordance with the varying aspects of the present invention, the nozzle is manufactured by the separate and enhanced construction of five individual subcomponents. The selected arrangement of subcomponents allows flexibility in the selection of materials of construction, including the use of materials that are amenable to precision surface machining while exhibiting a long operative lifespan. 
    
    
     The foregoing invention can be more completely appreciated in the context of a specific illustrative example presented in conjunction with the following detailed drawings of which: 
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a first isometric presentation of the five key components comprising the inventive nozzle; 
     FIG. 2 is a second isometric presentation of the five key components comprising the inventive nozzle structure; 
     FIG. 3 is an assembly drawing for the five components of FIGS. 1 and 2; 
     FIG. 4A is a cross-sectional view of the nozzle housing; 
     FIG. 4B is a frontal view of the nozzle housing; 
     FIG. 5A is a frontal view of the mixing disc; 
     FIG. 5B is a cross-sectional view of the mixing disc; 
     FIG. 5C is a back-end view of the mixing disc; 
     FIG. 6A is a cross-sectional view of the nozzle orifice; 
     FIG. 6B is a frontal view of the nozzle housing; 
     FIG. 7 is a cross-sectional view of the pintel; 
     FIG. 8A is a cross-sectional view of the cap nut; and 
     FIG. 8B is a back-end view of the cap nut. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First briefly in overview, the present invention is directed to a unique nozzle design that provides for controlled angled infusion of a gas and water stream, followed by rapid acceleration in a constriction zone and then pressure drop and release against the impact disc. The foregoing two-phase stream and its specific path through the several arteries of the nozzle provide a highly dispersed mist of water droplets in a controlled manner. Moreover, the arrangement of the stream path within the specific subcomponents provides for an arrangement of parts that can be economically machined or cast as determined by the materials needed for the application. 
     With the above brief overview in mind, attention is first directed to FIG. 1 presenting all five elements of the present nozzle invention in an &#34;exploded&#34; view to give appreciation to their in seratum spatial relationship. Going left to right (nozzle outlet to inlet), nozzle cap 10 encloses nozzle orifice 20. Pintel 30 extends through the orifice 20 and mixing disc 40. Mixing disc 40 is contained by nozzle housing 50 which has threaded connection to cap 10 to complete the enclosure. In a manner that will be explained in more detail below, mixing disc 40 provides an array of angled outlets for alternating gas 43 and water 44 infusion into the constriction zone defined by orifice 20 and the sloped surface of pintel 30. 
     FIG. 2 provides essentially the same presentation of FIG. 1, differing only in the vantage of the view. In FIG. 2, the inlet to the mixing disc 40 is shown as two concentric rings of openings--and specifically outer openings 41 and inner openings 42. These openings represent the inlets for both the gas and water phase, feeding the alternating angled outlets depicted in FIG. 1. 
     Turning now to FIG. 3, the separate subcomponents of the previous figures are depicted in assembled relationship. Going from right to left, housing 50 includes concentric inlets 53 and 54 for the gas and water stream connections. Importantly, there is no system requirements regarding whether the gas stream is connected to the inner openings 54 or the outer openings 53. This removes the very critical potential area for operator error found in prior art nozzle designs, as the operator can connect the water and gas lines to either 53 or 54. 
     Continuing with FIG. 3, mixing disc 40 precisely sits in housing 50 bringing the inlets 54 in communication with openings 42 and inlets 53 in communication with openings 41, respectively. As can be seen in this cross-section, cutaway view, openings 41 connect to a first series of angled outlets 43, while the openings 42 lead to the second series of angled outlets 44. Angled outlets 43 and 44 are arranged in a planer circular alternating array feeding a first mixing zone 48, defined by pintel 30 having an inclined cylindrical surface 31 and the orifice 20 having a first inner surface 23 defining a fairly steep incline to form a first constriction zone, followed by a flat surface 22, and then extending into an expanded nozzle opening zone defined by orifice inner surface 23; the nozzle opening terminates with impact plate 32. The angled outlets are preferably angled off center to about 25°. The subcomponents are held in position by cap 10 with threaded engagement with housing 50. 
     The housing 50 is depicted in end and side views in FIGS. 4A and 4B. Inlets 53 and 54, respectively, are provided in outer and inner concentric rings of housing 50, which further provides a threaded outer region 57 for connection to cap 10. 
     Turning now to FIGS. 5A, 5B and 5C, the mixing disc is depicted in front, back and cross-sectional views. Beginning with the center cross-section view (FIG. 5B), the mixing disc includes a central core. This core comprises the first inlet chamber 46 and a pintel lock opening 45. As can be seen with the assembly FIG. 3, the pintel is inserted into the first inlet chamber and slides into a locked position with its proximal end lock fitted into the pintel lock opening 45. The proximal end surface of the pintel 30 defines the inlet chamber 46 in communication with openings 42 to feed the second series of angled outlets 44. A concentric ring barrier 47 separates the inlet chamber 46 from the perimeter inlets 41. The inlets 41 feed the first angled outlets 43. Sets of outlets 43 and 44 alternatively form an array of outlets as shown in the left side of FIG. 5 and alternatively pass high pressure water and air into the mixing zone 48 to create the vortex two-phase stream. 
     Turning now to FIG. 6A, the orifice is shown in cross-sectional view, highlighting the constriction formed from the incline 23 to flat section 22 and finally expansion opening 21. The arrangement of the angled surfaces in the orifice provide for the acceleration of the water/gas from the mixing chamber to the impact plate on pintel 30. The angled surfaces (in the two dimensional figure) are actually conical surfaces (in 3D) as reflected in the end view (FIG. 6B). In this arrangement, the upstream side of the constriction is less steep than the down stream side, and both inclines are below 45°. 
     The pintel is shown in FIG. 7, and comprises an elongated single piece structure having a proximal end for locking into the mixing disc 40 and a distal end with the impact plate 32. Pintel 30 has a first cylindrical portion 35 that snugly fits into mixing chamber 40 engaging locking rim 36 with lock opening 45. Inclined surface 31 has an angle less than 45°. Flat surface 33 terminates with the impact plate 32 at the distal end, with the flat surface positioned to correspond with the constriction in the orifice 20. 
     The nozzle cap 10 is shown in FIGS. 8A and 8B and is constructed to thread onto nozzle housing 50 to provide a complete enclosure for the operative elements of the nozzle. 
     Having presented the preferred arrangement for the above nozzle invention, many modifications and adaptations thereof may be made without, however, departing from the spirit and scope of the present invention.