Abstract:
A nozzle design for diffusing high pressure steam into by flowing process fluid of substantially lower pressure while reducing the noise intensity generated. The injection nozzles include an opening having a first diameter to receive steam and a second diameter to inject the steam into a flow of liquid. The diameters of the first and second openings can vary relative to each other to enhance the flow characteristics of the steam or other gas being injected into a flow of liquid. The outer surface of a diffuser tube is coated with an insulating material, such as plastic. In alternate embodiments, the orientation of the injection holes can be angled either upstream or downstream to further enhance mixing characteristics of the steam.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is based on and claims priority to U.S. Provisional Patent Application Ser. No. 61/637,104 filed Apr. 23, 2012. 
    
    
     BACKGROUND 
     The present disclosure generally relates to direct contact steam injection heater diffusers. More specifically, the present invention relates to a steam injection heater diffuser in which steam is diffused into by flowing process fluid through a plurality of holes having a multi-diameter interior to reduce noise. 
     In diffusers described in previous direct contact steam injection heater patents, such as U.S. Pat. Nos. 6,361,025 and 7,152,851, steam flows through a plurality of straight walled cylindrical orifices or nozzles having sharp edges. The steam is expelled from the diffuser at high velocity into a process fluid flowing past the diffuser perpendicular to the axis of the orifice or nozzle. Under numerous working conditions, these simple nozzles and orifices work sufficiently well in transferring heat energy from the steam to the process fluid while remaining stable and at a decibel level that is comfortable to the human ear. Under certain conditions, however, instability may develop in the jet of exiting steam, which leads to undesirable high frequency, high decibel noise. 
     SUMMARY 
     The present disclosure is to be used in different types of direct contact steam injection type heaters such as those described in U.S. Pat. Nos. 6,361,025 and 7,152,851. The present disclosure is an improvement to a steam diffuser, containing a multiplicity of improved nozzles with the purpose of diffusing steam into by flowing process fluid. The improved diffuser design is comprised of one or more cluster(s) or zones of precisely shaped nozzles. Each cluster or zone is separated vertically by a solid band that is void of nozzles. In addition, each of the individual nozzles in the spaced zones is characterized by uniquely shaped cross sections designed to increase stability in the steam jet across the diffuser. 
     The injection type heater includes a diffuser tube that has an outer wall that defines an open interior that receives the heated gas. The outer wall of the diffuser tube includes an inner surface and an outer surface. The diffuser tube includes a plurality of nozzles that are spaced along the outer wall of the diffuser tube to direct the heated gas out of the open interior and into the fluid stream that is passing over the outer surface of the outer wall. Each of the nozzles includes an inlet opening in communication with the open interior at the inner surface and an outlet opening in communication with the outer surface of the diffuser tube. The flow of heated gas passes through each of the nozzles to heat the fluid stream. 
     In one embodiment of the disclosure, each of the nozzles includes a first cylinder having a constant first diameter and a second cylinder having a constant second diameter. The first and second cylinders are joined to each other by a conical transition zone. The first and second cylinders define a first diameter for the inlet opening and a second diameter for the outlet opening where the second diameter is greater than the first diameter. This configuration for the nozzle decreases the noise created by the flow of heated gas through the nozzles. 
     In a second embodiment of the nozzle design, each nozzle includes a constant diameter first cylinder that defines the inlet opening and has a first diameter. The first cylinder is joined to a conical section that extends from the first cylinder to the outer surface to define the outlet opening. The outlet opening has a second diameter that is greater than the first diameter. 
     In yet another alternate embodiment of the nozzle design, the nozzle extends between a first diameter inlet opening and a second diameter outlet opening. The nozzle is defined by a nozzle wall that has a constant taper from the inlet opening to the outlet opening. 
     In a contemplated embodiment of the disclosure, the outer wall of the diffuser tube includes a layer of insulating material. The layer of insulating material applied to the outer surface of the outer wall of the diffuser tube reduces the temperature of the surface over which the fluid being heated passes. The reduced temperature of the outer surface reduces scaling and extends the service life of the injection heater. 
     For each of the nozzle designs, the individual nozzles can be formed such that the injection axis of the nozzle is angled either upstream or downstream relative to the flow axis of the liquid flowing through the injection heater. Angling the individual nozzles either upstream or downstream can increase the efficiency of the injection heater depending upon the type of fluid being heated. 
     The individual injection nozzles ferried on the diffuser tube can be positioned in a series of separated injection zones. By separating the nozzle into injection zones, the injection heater can increase the precision of the heated gas injected into the fluid being heated. 
     Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate the best mode presently contemplated of carrying out the disclosure. In the drawings: 
         FIG. 1  is a cross sectional view of one possible direct contact steam injection heater in which the nozzles of the present disclosure may be used; 
         FIG. 2  is a section view of the diffuser design of  FIG. 1 ; 
         FIG. 3  is a sectional view of an alternate possible diffuser design; 
         FIG. 4  is a section view of one nozzle design; 
         FIG. 5  is a section view of an alternate nozzle design; 
         FIG. 6  is a section view of another alternate nozzle design; 
         FIG. 7  is a section view of another alternate nozzle design; 
         FIG. 8  is a section view illustrating a layer of plastic material attached to the outer surface of the diffuser; 
         FIG. 9  is a section view of another alternate nozzle design; 
         FIG. 10  is a section view illustrating a nozzle angled in a downstream direction; 
         FIG. 11  is a section view illustrating a nozzle angled in an upstream direction; and 
         FIG. 12  is an exploded view of another type of direct contact steam injection heater that can utilize the nozzle of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a section view of a direct steam injection type heater  1 . A diffuser  2  is positioned in the heater  1  such that a process fluid flowing generally axially past the diffuser  2  absorbs heat energy from steam jets exiting the series of nozzles  3 . Although the injection heater is described as being useful for injecting steam into a flow of liquid to heat the liquid, other heated gasses other than steam could be used while operating within the scope of the present disclosure. Steam will be utilized in the present disclosure with the understanding that other types of gasses could also be used when applied as a fluid mixing device. 
     As illustrated in  FIG. 1 , the heater  1  includes a regulating member  30  that is movable within a diffuser tube  32 . In the embodiment illustrated, the regulating member  30  includes a series of seals that expose a variable number of the individual nozzles  3  to control the amount of steam flowing from the open interior  34  of the diffuser tube  32  into the flow of processed fluid contained within the interior  36  of the heater body  38 . In the embodiment illustrated in  FIG. 1 , the series of individual nozzles  3  are contained within a single zone  40 . However, in accordance with the present disclosure, as will be described in much greater detail below, the individual nozzles  3  can be grouped differently depending upon the configuration of the diffuser tube  32 . 
       FIG. 2  illustrates a generally cylindrical steam diffuser  4  with a single cluster of nozzles  5  located radially on the outer wall  6 .  FIG. 2  shows one nozzle configuration of many possible such configurations to be described below. Steam enters through one large steam inlet  7  located at the top of the diffuser tube  32  and flows through the open interior  34 . The diffuser tube  32  contains a flange  8  concentric to the main chamber  9  of the diffuser. The purpose of the flange  8  is to locate the diffuser  4  axially inside the fluid body  10  of the heater  1  using mounting holes  11 . After entering the diffuser  4 , the steam enters an open interior  42  of the regulating member  30 . When the regulating member  30  is moved to expose the nozzles  5 , the steam exits through the exposed nozzles  5  at substantially higher velocity into the flowing process fluid. Although a pair of seals  43  are shown in the embodiment of  FIG. 2  to help control the steam flow, it should be understood that the seals could be eliminated while operating within the scope of the present disclosure. 
       FIG. 3  illustrates yet another alternate embodiment of a steam diffuser  12 . In the alternate embodiments shown in  FIG. 3 , the series of individual nozzles  5  are formed in the outer wall  6  of the diffuser tube  12 . The individual nozzles  5  are organized in a pair of zones  14  and  15 . The first zone  15  is formed near the bottom end  44  of the diffuser tube  12 . The first zone  15  includes a series of individual nozzles positioned in a regular array. The first zone  15  terminates at an upper end. A solid separating wall  47  extends above the first zone  15 . The solid wall  47  does not include any nozzles and thus does not allow steam to flow through this portion of the diffuser tube  12 . 
     A second zone  14  is located axially above the solid wall  47  and includes a similar series of nozzles  5 . Thus, based upon the movement of the regulating member  46 , the individual nozzles contained within the first and second zones  14 ,  15  are selectively exposed to the flow of steam. 
     In the embodiment shown in  FIG. 3 , the regulating member includes an open interior  48  that receives the flow of steam from the heater. The open interior  48  is defined by an outer wall  50  of the regulating member. As illustrated in  FIG. 3 , the outer wall  50  of the regulating member  46  includes an intermediate steam opening  52 . The intermediate steam opening  52  allows steam to flow radially outward from the regulating member and eventually through the exposed nozzles of the second zone  14 . The flow regulating member  46  includes an open bottom end  54  that allows an additional portion of the flow of steam to exit the regulating member  46 . When the regulating member  46  is moved from the closed condition shown in  FIG. 3 , a portion of the flow of steam exits through the open end  54  and flows through the exposed nozzles  5  of the first zone  15 . At the same time, a portion of the flow of steam exists through the intermediate opening  52  and flows through the exposed nozzles  5  of the second zone  14 . 
     In the embodiment shown in  FIG. 3 , the regulating member  46  includes a first sealing member  56  and a second sealing member  58  that are spaced from each other. Each of the sealing members  56 ,  58  are preferably a resilient member retained within a groove  60  formed in an outer surface of the wall  50  defining the open interior  48  of the regulating member  46 . As illustrated in  FIG. 3 , the first and second sealing members  56 ,  58  are spaced from each other by the height of the first zone  15 . As the regulating member  46  moves upward, the first sealing member  56  exposes an increasing number of the nozzles  5  to allow additional steam to pass through the outer wall  6  of the regulating member  46  and into the flow of material passing by the diffuser tube  12 . The second sealing member  58  prevents steam from flowing past the second sealing member  58  to aid in controlling the amount of steam discharged from the diffuser tube  12 . 
     A third sealing member  62  and a fourth sealing member  64  are also each contained within corresponding grooves formed in the regulating member  46 . The third and fourth sealing members  62 ,  64  are spaced from each other by the general width of the second zone  14  of nozzles  5 . The third sealing member  62  moves along the inner surface  66  of the outer wall  50  of the diffuser tube  12  to selectively expose an increasing number of nozzle openings  5 . The fourth sealing member  64  prevents the flow of steam contained within the open interior  68  from reaching the series of nozzles  5 . 
     Although the four sealing members  56 ,  58 ,  62  and  64  are shown in the embodiment of  FIG. 3 , it is contemplated that the sealing members could be eliminated from the regulating member  46 . In such an embodiment, the close spacing between the outer wall of the regulating member  46  and the inner wall of the diffuser tube  12  would limit the flow of steam or other gas. Although the use of the multiple sealing members is considered more preferred, the sealing members could be eliminated while operating within the scope of the present disclosure. 
     As described above, when the regulating member  46  moves upward, the steam flowing through the intermediate steam opening  52  flows into the gap  70  formed between the inner surface  66  of the diffuser tube and a recess  72  created within the outer wall  50  of the regulating member  46 . 
     The pair of zones  14 ,  15  allows for steam to be discharged from the diffuser tube  12  at different locations. The configuration of each of the zones  14 ,  15  could be modified depending upon the desired heating characteristics for the diffuser tube  12 . Additionally, the spacing of the individual nozzles  5  could be varied depending upon the desired amount of control needed for the diffuser tube  12 . As an illustrative example, the individual nozzles  5  could be created having various different sizes and configurations as well as being spaced from each other by varying amounts to control the flow of steam out of the diffuser tube  12 . Further, although two zones  14 ,  15  are shown in the embodiment of  FIG. 3 , it is contemplated that additional zones could be utilized while operating within the scope of the present disclosure. One distinct advantage of separating the nozzles into multiple zones is to separate and space the flow of steam from the nozzles, along the length of the diffuser tube  12 . The spacing between the zones will aid to increase the capacity of the diffuser and to increase its effectiveness by separating the heating capacity of each of the nozzles. When the nozzles are separated into multiple zones as shown in  FIG. 3 , the flow of steam from each of the nozzles does not impinge on each other, thereby increasing condensation effectiveness. 
     Although various different types of steam diffusers are shown in  FIGS. 1-3  that include some type of internal modulation, it is contemplated that the individual nozzle designs to be described below could be utilized in different types of heaters or mixers. As an example, the nozzle designs to be described below could be used with various different types of steam injection heaters that do not include any type of modulation but rather utilize steam pressure modulation to control the amount of heating. In a direct steam injection heater that does not include internal modulation, the amount of steam injected into the liquid being heated is controlled by the pressure and supply of steam into an injection tube. The nozzle designs of the present disclosure can be utilized as part of the injection tube to further improve the introduction of heated gas into the liquid flow. 
     Throughout the present disclosure, the injection of a heated gas into a flow of an unheated liquid is commonly referred to as the injection of steam. However, it should be understood that other types of gases could be injected into the fluid stream. As an example, heated ozone, nitrous, air or other gases could be utilized while operating within the scope of the present disclosure. 
       FIG. 4  illustrates one possible nozzle design with the purpose of stabilizing the steam jet under conditions which may cause instability in the standard straight walled nozzle. This design is characterized by two coaxial cylinders. The first is a small cylinder  17  open to the inner surface  104  of the outer wall  6  with diameter D1 and the second is a large cylinder  18  open to the outer surface  98  of the outer wall  6  with diameter D2 and a truncated cone  19  that defines a transition zone connecting the cylinders. Diameter D1 should be between 0.030 inches to 0.25 inches. The ratio of the large diameter to the small diameter should be no less than 1.25 and should not be greater than 3.0. The ratio of the hole length  20  and the diameter of the small cylinder  17  should be no less than 2.0 and no more than 5.0. In addition, the ratio of the hole length Z to the diameter D1 should be less than 1.25. 
       FIG. 5  illustrates an alternate nozzle design  23  with the purpose of stabilizing the steam jet. This nozzle  23  is characterized by one or more spiral grooves  21  in the wall  22  of the generally cylindrically nozzle  23 . The spiral groove  21  gives the steam a spiraling momentum which increases the stability of the steam as it exits the diffuser  12 . 
       FIG. 6  illustrates another alternate nozzle design with the purpose of stabilizing the steam jet. The nozzle shown in  FIG. 6  is characterized by a small cylinder  94  having a constant diameter D1. The small cylinder  94  transitions into a cone  96  which extends from the small cylinder  94  to the outer surface  98 . The cone  96  has an outlet diameter D2 that is greater than the inlet diameter D1. 
       FIG. 7  illustrates yet another alternate nozzle design. In the alternate nozzle design shown in  FIG. 7 , the nozzle  100  is characterized by a nozzle wall  102  that tapers from the inner surface  104  to the outer surface  98 . The relative angle of the nozzle wall  100  can be varied depending upon the desired flow characteristics. However, the inlet diameter D1 is less than the outlet diameter D2. 
       FIG. 8  illustrates an additional configuration for the diffuser tube  12 . In the embodiment illustrated in  FIG. 8 , a layer of insulating material  106  is applied to the outer surface  98  of the diffuser tube. The layer of insulating material  106  is formed on the outer surface  98  of the diffuser tube  12  before the individual nozzles  5  are formed in the tube  12 . After the layer of insulating material  106  is formed, each of the nozzles  5  is formed by drilling. The drilling process creates a hole  108  in the insulating material aligned with the nozzle  5  formed in the diffuser tube  12 . The layer of insulating, material is utilized as a layer of insulation between the flow of material to the exterior of the diffuser tube, as shown by reference numeral  110 , and the flow of steam in the area indicated by reference numeral  112 . In the contemplated embodiment of the disclosure, the layer of insulating material  106  is plastic, although other materials are contemplated. The insulative properties of the layer of plastic  106  reduce the temperature of the outer surface  114  of the insulative material  106 , which minimizes the effect of scale or mineral buildup, especially in hard water applications. In embodiments not including the layer of insulative material  106 , scale tends to build up across the nozzle opening, which can dramatically affect the flow of the steam or other liquid being introduced through the series of nozzles  5 . The specific material selected for the layer of insulative material  106  can vary depending upon whether greater insulation is needed or whether the material needs to have increased durability. The level of durability needed will depend upon the type of liquid passing over the exterior of the diffuser tube. The hardness of the plastic material can be selected based upon the type of liquid passing over the diffuser tube to enhance durability. 
     Although not shown in  FIG. 8 , it is also contemplated that instead of utilizing the layer of plastic material  107 , the outer surface  98  of the diffuser tube  12  can include a highly polished surface. The highly polished surface also acts to minimize the scaled minerals since attachment to the outside surface of the highly polished diffuser tube will be more difficult than an unpolished surface. 
       FIG. 9  illustrates another alternate nozzle design. In the embodiment shown in  FIG. 9 , the nozzle  120  is characterized as having, a smooth entry and exit region with a contraction therebetween. In the embodiment shown in  FIG. 9 , the entry diameter  122  is at least two times the contraction diameter  124  and can be larger to provide smooth entry. The exit diameter  126  must be larger than the contraction diameter  124 . The maximum angle between the contraction diameter  124  and the exit diameter  126  must be no larger than 70° to prevent flow from detaching. 
     In the embodiment shown in the Figures for the various different nozzle designs, each of the nozzles is positioned along an injection axis that is generally perpendicular to the longitudinal axis of the diffuser tube. In an embodiment in which the flow axis of the liquid being heated is parallel to the longitudinal axis of the diffuser tube, the injection axis is perpendicular to the flow axis of the liquid passing through the injection heater. 
       FIG. 10  illustrates an embodiment in which the injection axis  130  of the nozzle  5  is positioned at an angle relative to the longitudinal axis  132  of the outer wall  6 . The longitudinal axis  136  of the outer wall  6  is generally parallel to the flow axis  138  of the fluid being heated. The angle A directs the flow of heated gas from the nozzle  5  in a downstream direction. The angle A can be varied depending upon the desired mixing characteristics as well as the types of liquid being heated. 
       FIG. 11  illustrates a similar embodiment in which the nozzle  5  is angled to direct the heated gas in an upstream direction. Once again, the angle A can be varied depending upon the mixing requirements and the types of liquid being heated. 
     Although one of the specific nozzle designs is shown in the embodiment of  FIGS. 10 and 11 , it should be understood that each of the nozzle designs shown in the drawing Figures could be angled either in an upstream or downstream direction, as illustrated in  FIGS. 10 and 11 . 
       FIG. 12  illustrates one of many other types of steam injection heaters  80  that can utilize the nozzle design described above. In the embodiment shown in  FIG. 9 , the steam injection heater includes a diffuser assembly  82  that includes a cover  84  and a regulating member  86 . Steam flows into the regulating member  86  and is allowed to exit the regulating member through one of a pair of openings  88 . The opening  88  is surrounded by a sealing member  90 . As the regulating member  86  rotate within the cover  84 , the sealing member  90  exposes an increasing number of nozzles  92  formed in the outer surface of the cover  84 . Each of the individual nozzles can be configured as shown in  FIGS. 4-5 . Additionally, the configuration of the individual nozzles  92  within the cover  84  can be selected based upon the desired amount of steam discharged from the steam injection heater  80 . 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.