Abstract:
A steam dispersion apparatus configured to humidify a flow of air passing by the steam dispersion apparatus includes a steam dispersion tube configured to emit water in a vapor phase. The steam dispersion tube includes a longitudinal axis extending generally parallel to the direction of the air flow passing by the steam dispersion apparatus. The steam dispersion tube includes a steam exit. A turbulence inducing structure is located upstream of the steam dispersion tube with respect to the air flow, the turbulence inducing structure being configured to increase a velocity of the air that passes through the turbulence inducing structure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/823,575, filed on Aug. 25, 2006, which application is incorporated herein by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     The principles disclosed herein relate generally to the field of steam dispersion humidification. More particularly, the disclosure relates to a steam dispersion apparatus that uses air turbulence to mix steam into moving air.  
       BACKGROUND  
       [0003]     In the humidification process, steam is normally discharged from a steam source as a dry gas or vapor. As steam mixes with cooler duct air, some condensation takes place in the form of water particles. Within a certain distance, the water particles are absorbed by the air stream within the duct. The distance wherein water particles are completely absorbed by the air stream is called absorption distance. Another term that may be used is a non-wetting distance. This is the distance wherein water particles or droplets no longer form on duct equipment (except high efficiency air filters, e.g.). Past the non-wetting distance, visible wisps of steam (water droplets) may still be visible, for example, saturating high efficiency air filters. However, other structures will not become wet past this distance. Absorption distance is typically longer than the non-wetting distance and occurs when visible wisps have all disappeared and the water vapor passes through high efficiency filters without wetting them. Before the water particles are absorbed into the air within the non-wetting distance and ultimately the absorption distance, the water particles collecting on duct equipment may adversely affect the life of such equipment. Thus, a short non-wetting or absorption distance is desirable.  
         [0004]     Some of the current steam dispersion humidification designs use closely spaced tubes with hundreds, even thousands, of nozzles to achieve a short non-wetting or absorption distance. Such designs undesirably heat the duct air and create significant amounts of unwanted condensate. An increased number of tubes and/or nozzles also adds significant cost and weight to the duct systems. However, if the number of tubes and/or nozzles is decreased, although the heat gain and condensate is reduced significantly, the non-wetting and absorption distances are increased dramatically.  
         [0005]     What is needed in the art is a steam dispersion apparatus that will lead to both short non-wetting and absorption distances and minimal heat gain and condensation.  
       SUMMARY  
       [0006]     The principles disclosed herein relate to an apparatus that uses air turbulence to efficiently mix steam with moving air.  
         [0007]     In one particular aspect, the disclosure is directed to a turbulence inducing steam dispersion apparatus that uses blades, vanes, baffles or other turbulence-inducing structures to create air turbulence and to disperse discharged steam into the moving air within a short distance.  
         [0008]     In another particular aspect, the disclosure is directed to a steam dispersion apparatus that includes a steam tube with steam discharge nozzles located at a downstream end of the turbulence-inducing structure.  
         [0009]     A variety of additional inventive aspects will be set forth in the description that follows. The inventive aspects can relate to individual features and combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a perspective view of a steam dispersion apparatus having features that are examples of inventive aspects in accordance with the principles of the present disclosure, the steam dispersion apparatus shown mounted within an air duct, the air duct shown with a portion thereof broken away to expose the steam dispersion apparatus therein;  
         [0011]      FIG. 2  is a perspective view of the steam dispersion apparatus of  FIG. 1 ;  
         [0012]      FIG. 3  is a right side view of the steam dispersion apparatus of  FIG. 2 ;  
         [0013]      FIG. 4  is a front view of the steam dispersion apparatus of  FIG. 2 ; and  
         [0014]      FIG. 5  illustrates another embodiment of a steam dispersion apparatus having features that are examples of inventive aspects in accordance with the principles of the present disclosure;  
         [0015]      FIG. 6  illustrates yet another embodiment of a steam dispersion apparatus having features that are examples of inventive aspects in accordance with the principles of the present disclosure;  
         [0016]      FIG. 7  illustrates yet another embodiment of a steam dispersion apparatus having features that are examples of inventive aspects in accordance with the principles of the present disclosure; and  
         [0017]      FIG. 8  illustrates yet another embodiment of a steam dispersion apparatus having features that are examples of inventive aspects in accordance with the principles of the present disclosure. 
     
    
     DETAILED DESCRIPTION  
       [0018]     The principles disclosed herein relate generally to the field of steam dispersion humidification. In one particular aspect, the disclosure is directed to a steam dispersion apparatus that uses blades, vanes, baffles, or other turbulence-inducing structures to induce air turbulence and to disperse discharged steam into the moving air within a short distance.  
         [0019]     An embodiment of a steam dispersion apparatus having features that are examples of inventive aspects in accordance with the principles of the present disclosure is shown in  FIGS. 1-4 , designated generally at  20 .  
         [0020]     In  FIG. 1 , the steam dispersion apparatus  20  is shown positioned within an air duct  10 . The air duct  10  may be part of a heating, ventilating and air conditioning (HVAC) system. In a conventional HVAC system, the air may be forced to flow through the air duct  10  by a fan. Arrows  12  represent the direction of airflow through the duct  10 . The steam dispersion apparatus  20  may be placed within the duct  10  of the HVAC system for the purpose of humidifying the moving air.  
         [0021]     Since configurations and operations of HVAC systems are well known in the art, further details thereof will not be provided herein, it being understood that those skilled in the art clearly understand the nature and variety of such systems. It should also be noted that the steam dispersion apparatus  20  may be used in a number of different environments, an HVAC system being one non-limiting example. As used herein, the term “steam” is defined as the invisible vapor into which water is converted to when heated to the boiling point of water. Another definition of “steam” as used herein is water in vapor phase.  
         [0022]     In  FIGS. 2-4 , the steam dispersion apparatus  20  is shown outside of the air duct  10 . The steam dispersion apparatus  20  includes a steam tube  22  positioned in the center of a turbulence-inducing structure  24 . In the depicted embodiment, the turbulence-inducing structure  24  is designed to cause air vortices  26  (see  FIG. 4 ) in the moving air to maximize effective mixing without causing a significant drop in pressure. In other embodiments, other structures that can cause different air flow patterns may be used.  
         [0023]     The turbulence-inducing structure  24  includes an inner frame  28  and a concentrically positioned outer frame  30 . As shown in  FIGS. 1-4 , each of the inner and the outer frames  28 ,  30  includes a hexagonal shape formed by six rectangular panels  32  joined together. The panels  32  are preferably manufactured out of sheet metal. The panels  32  could also be made of plastic or other types of sheet type stock. The inner and outer frames  28 ,  30  can also include other shapes such as octagonal, circular or other polygonal shapes. A hexagonal or octagonal shape is preferred for rectangular ductwork installations.  
         [0024]     A first plurality vanes  34  radially extend outwardly from the steam tube  22  and terminate at the panels  32  of the inner frame  28 . Within the inner frame  28 , there are provided six vanes  34 , one corresponding to each panel  32  of the inner frame  28 . However, it shall be understood that the number of vanes  34 , just as in the number of panels  32 , can be modified to provide the desired air mixing result. The vanes  34  within the inner frame  28  are uniformly spaced and are each curved in the same direction with respect to the air flow to impart either a clockwise or counterclockwise rotation to the air passing through the turbulence-inducing structure  24 . Each of the first plurality of vanes  34  includes a leading edge  36 , a trailing edge  38 , and a curved portion  40  interconnecting the leading edge  36  to the trailing edge  38 .  
         [0025]     A second plurality of vanes  42  is located between the inner frame  28  and the outer frame  30 . Each of the vanes  42  extends radially outwardly from the panels  32  of the inner frame  28  to the panels  32  of the outer frame  30 . In the depicted embodiment, each side of the hexagon includes two vanes  42  extending between the inner frame  28  and the outer frame  30 . Other numbers are contemplated. The vanes  42  of the second plurality have approximately the same cross-sectional shape as the first plurality of vanes  34 . The second plurality of vanes  42 , however, are curved with respect to the airflow in the duct  10 , oppositely to the curvature of the first plurality of vanes  34  so as to impart an opposite directional rotation to the air passing by the second plurality of vanes  42 . As a result, the particular vane arrangement provides the vortice patterns illustrated in  FIG. 4 , resulting in efficient mixing of airstreams at a downstream end  25  of the turbulence-inducing structure  24 .  
         [0026]     Although in  FIGS. 1-4 , the turbulence-inducing structure  24  is depicted as including vanes, in other embodiments, the turbulence-inducing structure  24  may include blades, baffles, etc. In one preferred embodiment, the turbulence-inducing structure  24  may be a static air mixer available from Blender Products, Inc., which is described in further detail in U.S. Pat. Nos. 6,878,056 and 5,645,481, the disclosures of which are incorporated herein by reference in their entirety. Another turbulence-inducing structure is disclosed in U.S. Pat. No. 4,495,858, the disclosure of which is incorporated herein by reference in its entirety.  
         [0027]      FIG. 4  is a front elevational view of the steam dispersion apparatus  20  of the present invention, illustrating the turbulence-inducing structure  24  from a downstream end view. The directional arrows denote some of the various vortices  26  which are created by the two pluralities of vanes  34 ,  42  of the turbulence-inducing structure  24 . For the purposes of this disclosure, vortices are those discrete air patterns which are created in the airstreams as the airstreams pass through the turbulence-inducing structure  24 . As the air streams pass through the steam dispersion apparatus  20 , the cross-sectional flow area is reduced from the cross-sectional area A D  of the duct  10  to the open area AO defined between the vanes. As the air streams pass through the steam dispersion apparatus  20 , because of the reduction in the cross-sectional flow area, the velocity of the air increases. As the air streams move past the turbulence-inducing structure  24  and move farther downstream, the vortice patterns  26  become more divergent and the air streams obtain slower velocities. The steam dispersion tube  22 , by being positioned at the immediate downstream end  25  of the turbulence-inducing structure  24 , is, located at a preferred location for efficiently mixing the steam into the moving air.  
         [0028]     Referring now to  FIGS. 2-4 , in the embodiment depicted, the steam tube  22  extends longitudinally along the center of the turbulence-inducing structure  24 . In the depicted embodiment, the steam tube  22  of the steam dispersion apparatus  20  includes a plurality of radially arranged steam nozzles  44  for dispersing the steam radially outwardly from the steam tube  22 . The steam nozzles  44  are located adjacent the downstream end  25  of the turbulence-inducing structure  24 , wherein steam is emitted into the created air vortices  26  to provide efficient absorption of the steam into the air stream and to provide for shorter absorption distances. The nozzles  44  emit steam in a generally perpendicular direction to the direction of the air flow  12 . Please see  FIG. 1 . In one embodiment, the steam tube  22  includes twenty-four radially arranged nozzles  44 . Other sizes or numbers are certainly possible depending upon the desired humidification needs.  
         [0029]     It should be understood that, although in the depicted embodiment, the nozzles  44  are arranged radially around the steam tube  22  and emit steam in a generally perpendicular direction to the airflow  12 , in other embodiments, the steam nozzles  44  may be configured such that they emit steam into the airflow  12  at angles of less than 90 degrees. In yet certain other embodiments, the nozzles  44  or a single nozzle  44  can be placed axially at the downstream end of the steam tube  22  and emit steam in a direction generally parallel to the direction of the airflow  12 .  
         [0030]     The nozzles  44  are preferably spaced evenly around a perimeter  23  of the steam tube  22 . The nozzles  44  may be affixed in the steam tube  22  by any conventional means. Although the nozzles  44  in the depicted embodiment are configured to cover generally a majority of the surface area of the steam tube, in other embodiments, the nozzles  44  may be located at discrete locations or at a single location, such as the downstream end of the steam tube  22 . In such an embodiment, the steam tube  22  may still extend longitudinally from the center of the turbulence-inducing structure  24  and carry the steam therewithin until the steam exits out of the nozzles, which may be axially positioned or radially positioned along the steam tube  22 .  
         [0031]     In one preferred embodiment, the steam tube  22  is between about 4 inches and 12 inches in length L T . More preferably, the steam tube  22  is between about 6 inches and 9 inches in length L T . Most preferably, the steam tube  22  is about 7 inches in length L T .  
         [0032]     It should be noted, however, that the length of the steam tube  22  can vary depending upon the width W D  and height H D  of the duct  10 . The larger the cross-sectional area A D  of the duct  10 , the longer the steam tube  22  can be. In an embodiment wherein the nozzles  44  are not provided along a majority of the length of the steam tube  22 , the larger the cross-sectional area A D  of the duct  10 , the farther down along the steam tube  22  the steam nozzles  44  can be located. For example, in an embodiment wherein the duct has a height H D  of 2 feet and width W D  of 2 feet, the length L T  of the steam tube  22  can go up to 2 feet or the location of the steam nozzles  44  can be up to 2 feet from the turbulence inducing structure  24 . In another embodiment wherein the duct has a height H D  of 6 feet and width W D  of 6 feet, the length L T  of the steam tube  22  can go up to 6 feet or the location of the steam nozzles  44  can be up to 6 feet from the turbulence inducing structure  24 .  
         [0033]     In one preferred embodiment, the steam tube  22  is between about 0.5 and 4.5 inches in diameter. More preferably, the steam tube  22  is between about 1 and 3.5 inches in diameter. Most preferably, the steam tube  22  is about 3 inches in diameter.  
         [0034]     The steam in the steam tube  22  may be supplied by conventional means, e.g., a boiler (not shown). In the depicted embodiment, the steam is received under pressure from the boiler and is forced radially outwardly through the steam nozzles  44 . In other embodiments, the velocity or the amount of the steam may be regulated via certain control mechanisms based on certain variables. In certain embodiments, devices such as pressure regulators, valves, humidistat, thermostats, etc., may be used to regulate the amount or velocity of the steam based on certain variables.  
         [0035]     Still referring to  FIGS. 1-4 , the steam dispersion apparatus  20  includes a mounting flange  46  surrounding the turbulence-inducing structure  24 . The mounting flange  46  may be used to mount the steam dispersion apparatus  20  to the walls  11  of the air duct  10 . The mounting flange  46  is also used to seal the duct  10  such that air streams are forced to go through the turbulence-inducing structure  24 . The mounting flange  46  may be shaped and sized according to the cross-section of the duct  10 . The steam dispersion apparatus  24  may be mounted to the walls  11  of the duct  10  by any means generally known in the art, e.g., fasteners, welding, etc.  
         [0036]     In operation, when the blown air flows through the turbulence-inducing structure  24 , the inner and outer vanes  34 ,  42  deflect the flowing air and cause counter rotating air vortices  26 , respectively. As the air flows through the vanes  34 ,  42 , because of the reduction in the cross-sectional flow area, the velocity of the air increases. The steam supplied via a conventional boiler exits the steam tube  22  through the nozzles  44  at the downstream end  25  of the turbulence-inducing apparatus  24 . Due to the increased velocity of the air through the steam-inducing structure  24  and the changes in the flow characteristics of the air adjacent the steam nozzles  44 , steam is more efficiently dispersed into the air in the duct  10 . The more air per unit of time that can be moved past each nozzle  44 , the greater amount of steam that can be absorbed within a given distance.  
         [0037]     In one experimental test, an embodiment of the steam dispersion apparatus that used a steam tube with a 7-inch length and a 3-inch diameter and having twenty-four radially arranged nozzles in combination with a steam-inducing structure provided a shorter absorption distance and 80% less condensate and heat gain than a steam dispersion unit using sixteen 3-inch center-to-center tubes, each one being 34 inches long and 1.5 inches in diameter, with a total of six hundred and sixty nozzles, keeping all the other variables the same.  
         [0038]     The turbulence caused by a structure such as the steam-inducing structure  24  allows the reduction of the number of tubes and the condensate within the system. Without the use of turbulence, short non-wetting or absorption distances may be accomplished by forcing steam into contact with air using a large number (hundreds to thousands) of steam discharge points. With turbulence, short non-wetting or absorption distances may be accomplished with a reduced number of steam discharge points.  
         [0039]     It should be noted that, although in  FIGS. 1-4 , only a single steam dispersion apparatus is shown to be mounted within an air duct, in other embodiments, a plurality of the steam dispersion apparatuses with a plurality of turbulence-inducing structures and steam tubes can be used within an air duct (please see  FIG. 8 , for example). Such apparatuses can be sized and shaped accordingly to cover the cross-section of a particular duct.  
         [0040]     Another embodiment of a steam dispersion apparatus having features that are examples of inventive aspects in accordance with the principles of the present disclosure is shown in  FIG. 5 , designated generally at  120 . The steam dispersion apparatus  120  depicted in  FIG. 5  is similar to the steam dispersion apparatus  20  of  FIGS. 1-4 , except that it includes a plurality of steam dispersion tubes  122  located on the turbulence inducing structure  124 . The steam tubes  122  are shown as being positioned between the first plurality of vanes  134  and the second plurality of vanes  142 . Each steam tube  122  may include any combination of the features discussed with respect to steam tube  22  of  FIGS. 1-4 . The steam nozzles  144  may be located at a variety of different locations around each steam dispersion tube  122 .  
         [0041]     The turbulence-inducing structure  124  may be similar to the turbulence-inducing structure  24  of  FIGS. 1-4  and may have any of the characteristics discussed with respect thereto. For example, although the turbulence-inducing structure  124  is depicted as including vanes, in other embodiments, it may include blades, baffles, etc. The turbulence-inducing structure  124  may also include shapes other than which is disclosed in  FIG. 5 .  
         [0042]     Referring to  FIG. 6 , there is illustrated another embodiment of a steam dispersion apparatus having features that are examples of inventive aspects in accordance with the principles of the present disclosure, designated generally at  220 . In the embodiment of the steam dispersion apparatus  220 , a plurality of steam tubes  222  are provided generally across the turbulence-inducing structure  224 , rather than along a direction of the airflow as depicted in  FIGS. 1-5 . As shown in  FIG. 6 , the tubes are positioned at a downstream location  225  of a turbulence-inducing structure  224 . Each steam tube  222  includes a plurality of steam nozzles  244  that discharge steam at a generally perpendicular direction to the direction of the airflow. It should be noted that the positioning of the steam nozzles  244  and the number of nozzles  244  can be changed according to desired mixing results.  
         [0043]     Still referring to  FIG. 6 , although the steam tubes  222  are depicted as extending vertically in front of the turbulence-inducing structure  224 , they can also be arranged horizontally across the duct  10 . In other embodiments, the tubes  222  may be arranged at other angles relative to the turbulence-inducing structure  224 .  
         [0044]     The number of steam tubes  222 , and, as discussed above, the number of steam dispersion nozzles  244  may certainly be changed. For example, in one embodiment, there may be a single, larger, steam dispersion tube  222  that extends in front of the turbulence-inducing structure  224 , at any angle relative to the turbulence-inducing structure  224 , instead of a plurality of tubes.  
         [0045]     In the embodiment of the steam dispersion apparatus  220  shown in  FIG. 6 , the steam dispersion tubes  222  are depicted as being integrally formed with the turbulence-inducing structure  224 . The turbulence-inducing structure  224  includes a mounting frame  229  that includes forwardly-extending flanges  231 ,  233 , at top and bottom sides, respectively, of the frame  229 . The flanges  231 ,  233  support and position the steam dispersion tubes  222  at the downstream end  225  of the turbulence-inducing structure  224 . In the depicted embodiment, the dispersion tubes  222  extend from a steam header  205 . In other embodiments, the tubes  222  may be provided separately from the turbulence-inducing structure  224  and may be supported in their own frame structure.  
         [0046]     In  FIG. 7 , yet another embodiment of a steam dispersion apparatus having features that are examples of inventive concepts in accordance with the disclosure is shown. The embodiment shown in  FIG. 7  includes a steam tube  322  with a plurality of turbulence-inducing structures  324  directly attached thereto. In certain embodiments, the turbulence-inducing structures  324  may be formed integrally with the steam tubes  322 . In  FIG. 7 , the turbulence-inducing structures  324  are depicted as vanes  334  that are formed integrally with the tube  322 , but may be other structures such as blades, baffles, etc. In certain other embodiments, the turbulence-inducing structures may be attached to the steam tube  322  by any means known in the art such by welding, with fasteners, etc.  
         [0047]     In the embodiment of  FIG. 7 , the turbulence-inducing structures  324  are positioned between the steam nozzles  344 . The turbulence-inducing structures  324  may induce multiple vortices into which steam is mixed, reducing the non-wetting or the absorption distance. A steam tube such as the tube  322  shown in  FIG. 7  may be used with or without an additional turbulence-inducing structure such as the one shown in  FIGS. 1-6 . In a steam dispersion system, one such steam dispersion tube  322  or a plurality of the steam dispersion tubes  322  may be used depending upon the desired mixing characteristics.  
         [0048]     As a further variation of the embodiment of  FIG. 7 , turbulence-inducing structures may be attached directly to or formed integrally with the walls of the air duct  10 .  
         [0049]      FIG. 8  illustrates yet another embodiment of a steam dispersion apparatus  420  having features that are examples of inventive concepts in accordance with the disclosure. The embodiment of  FIG. 8  generally includes a plurality of the steam dispersion apparatuses shown in  FIGS. 1-4  in a stacked arrangement. The number of the steam dispersion apparatuses and the arrangement can certainly vary depending upon the shape and the size of the duct. Each steam dispersion apparatus that makes up the embodiment of  FIG. 8  may have any combination of the features discussed above with respect to those embodiments discussed with reference to  FIGS. 1-7 , such as single or multiple steam dispersion tubes, angled at a variety of different angles, with single or multiple steam discharge nozzles arranged in various positions around the steam dispersion tubes, etc.  
         [0050]     The above specification, examples and data provide a complete description of the disclosure. Many embodiments of the inventive aspects can be made without departing from the spirit and scope of the disclosure.