Abstract:
A mixing manifold is provided. The manifold includes: a body; a first converging passageway in the body; a first diverging passageway in the body in-line and in fluid communication with the first converging passageway to form a first venturi; a first obstruction in a throat of the first venturi configured to move between two positions, a blocking position that blocks, at least in part, flow through the first venturi and an open position; a second converging passageway in the body; a second diverging passageway in the body in-line and in fluid communication with the second converging passageway to form a second venturi; and a second obstruction in the second venturi configured to move between two positions, a blocking position that blocks, at least in part, flow through the second venturi and an open position. A method of providing fluid flow through a manifold is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/955,438, filed Mar. 19, 2014, the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present disclosure relates generally to a mixing system and method for controlling an amount of air that flows through a manifold. More particularly, the present disclosure relates to a manifold that has at least two venturis that can be at least partially blocked to control an amount of fluid that flows through the manifold. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many combustion systems mix fuel and air prior to the fuel air mixture being provided to the combustion chamber. Many of these premixed combustion systems use a venturi device to regulate the air fuel ratio. The basic principle is that air for combustion is pulled (or pushed) through a venturi-shaped pathway. The venturi pathway reduces the cross-sectional area at the venturi throat which causes an increase of flow velocity thus reducing pressure. It is this low pressure which induces fuel flow from a fuel source which is at a higher pressure than the low pressure found at the venturi throat into the air stream from a separate port. This pneumatic coupling is useful since these combustion systems can maintain an air fuel ratio even when the airflow changes whether intentionally or accidentally. 
         [0004]    Reducing the airflow from its maximum and through its minimum, and vice versa, is often done with a variable speed blower. This adjustment allows the system to operate at different input rates. The ratio between the maximum flow and the minimum flow is referred to as a turndown ratio. These systems often only work within a certain operating range because as the venturi throat becomes oversized at lower flow rates and does not increase the velocity enough to lower pressure sufficiently to properly induce required fuel flow. 
         [0005]    Accordingly, it is desirable to provide a system and method which allows an apparatus to operate with broader operating parameters. In other words, a system and method may operate along a broader turndown ratio. 
       SUMMARY OF THE INVENTION 
       [0006]    The foregoing needs are met to a great extent by the present invention, wherein, in some embodiments allows a system and/or a method to operate with broader operating parameters. In other words, a system and method may operate along a broader turndown ratio. 
         [0007]    In accordance with one embodiment of the present invention, a mixing manifold is provided. The manifold includes: a body; a first converging passageway in the body; a first diverging passageway in the body in-line and in fluid communication with the first converging passageway to form a first venturi; a first obstruction in a throat of the first venturi configured to move between two positions, a blocking position that blocks, at least in part, flow through the first venturi and an open position; a second converging passageway in the body; a second diverging passageway in the body in-line and in fluid communication with the second converging passageway to form a second venturi; and a second obstruction in the second venturi configured to move between two positions, a blocking position that blocks, at least in part, flow through the second venturi and an open position. 
         [0008]    In accordance with another embodiment of the present invention, a method of providing fluid flow through a manifold is provided. The method includes: providing multiple venturi passageways in a body; installing an obstruction in a throat of the venturi passageways; configuring the obstruction to move between a blocking position and an open position. 
         [0009]    In accordance with yet another embodiment of the present invention, a mixing manifold is provided. The manifold includes: a body; a first converging passageway in the body; a first diverging passageway in the body in-line and in fluid communication with the first converging passageway to form a first venturi; a first means for obstructing located in a throat in the first venturi configured to move between two positions, a blocking position that blocks, at least in part, flow through the first venturi and an open position; a second converging passageway in the body; a second diverging passageway in the body in-line and in fluid communication with the second converging passageway to form a second venturi; and a second means for obstructing in the second venturi configured to move between two positions, a blocking position that blocks, at least in part, flow through the second venturi and an open position. 
         [0010]    There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
         [0011]    In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
         [0012]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a side view illustrating an air-fuel mixing and combustion system according to an embodiment in accordance with this disclosure. 
           [0014]      FIG. 2  is a perspective view of a manifold according to an embodiment of the disclosure. 
           [0015]      FIG. 3  is a partial cross-sectional view of a manifold showing the venturi passageways. 
           [0016]      FIGS. 4-7  are partial cross-sectional views of manifolds showing venturi passageways of different dimensions and flaps being in different positions and weights. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present disclosure provides a method and apparatus that allows the amount of air that flows into the manifold to be scaled up or down. A manifold having a plurality of inlets can allow air coming into the inlet to flow through all or some of the inlets and the adjustment, opening, or closing of a throttling valve in the inlets is accomplished by the airflow itself. 
         [0018]    An embodiment of the present inventive apparatus is illustrated in  FIG. 1 .  FIG. 1  illustrates a combustion system  10 . The combustion system  10  includes a venturi manifold  12 . The venturi manifold  12  includes intake cowlings  14 . The venturi manifold  12  is connected by a manifold flange  16  to a conduit flange  17 . The connection between the manifold flange  16  and the conduit flange  17  connects the venturi manifold  12  to a conduit  18 . The manifold flange  16  and conduit flange  17  may be connected via bolts  20  and nuts  21 . In other embodiments, the manifold flange  16  may be connected to the conduit  18  in any suitable manner which may or may not include bolts  20  and nuts  21  or flanges  16  and  17 . 
         [0019]    The conduit  18  connects the intake manifold  12  to a blower  22 . The blower  22  is connected to a conduit  24  which provides a fluid connection between the blower  22  and the combustion device  26 . A conduit  28  is connected to the combustion device  26  to provide a fluid connection to an exhaust system for exhausting combustion products out of the combustion device  26 . 
         [0020]    The combustion device  26  may be any household or commercial combustion device  26 . Examples may include, but are not limited to, boilers, furnaces, hot water heaters, gas dryers or any other type of combustion device. In the system  10  shown in  FIG. 1 , air is drawn through the intake cowlings  14  into the manifold  12 . As will be described and illustrated in more detail later with respect to other figures, fuel may be mixed with the air in the manifold  12 . The air/fuel mixture moves through the conduit  18  into the blower  22  due to the suction or pulling action of the blower  22 . 
         [0021]    The air/fuel mixture moves through the conduit  24  into the combustion device  26 . The air fuel mixture is burned within the combustion device  26 , creating heat. The combustion products or exhaust is vented out the conduit  28  into an exhaust system and may be vented outside or wherever exhaust is desired to be vented. 
         [0022]    While the system shown in  FIG. 1  is an example, it will be appreciated by one of ordinary skill in the art that various components of the system  10  may be moved. For example, the blower  22  may blow air rather than pull air through the manifold  12 . In such systems, the manifold  12  may be located between the blower  22  and the combustion device  26 . The various conduits  18 ,  24 , and  28  may be modified, absent, or added to as needed for a particular system or installation. One of ordinary skill in the art, after reviewing this disclosure, will understand how to modify and arrange the various components of a combustion system  10  in order to achieve desired results. 
         [0023]    The manifold  12  may add fuel to the air using a venturi system. As described above, various systems  10  may have turndown ratios which may result in relatively low airflow through the manifold  12 . If the airflow through the manifold  12  becomes too low, then a venturi system will have difficulty adding an appropriate amount of fuel. As a result, the present disclosure is directed to modify a manifold  12  to have various parallel venturis in order to scale up or down according to an airflow need an amount of venturis in order to provide a desired amount of air and fuel to the combustion system  10 . 
         [0024]      FIG. 2  is a perspective view of a manifold  12  in accordance with an embodiment of the present disclosure. The manifold  12  includes intake cowlings  14 . The manifold  12  is also equipped with a manifold flange  16  having bolt holes  30  which allow the bolts  20  as shown in  FIG. 1  to attach the manifold  12  to a conduit  18  as previously shown and described. 
         [0025]    Pivot shafts  32  are located in the manifold  12 . In some embodiments, and as shown, the air intakes  34  are surrounded by intake cowlings  14 . The intake cowlings  14  are optional and may not be present in all embodiments. The pivot shaft  32  supports and allows a flap  36  to move between an open and closed position within the air intakes  34 . 
         [0026]      FIG. 3  is a partial cross-sectional view of a venturi manifold  12  in accordance with the present disclosure. Fuel supplies  38  are equipped with fuel supply gaps  40  allow fuel coming from a fuel reservoir to flow through the fuel supply  38  through the fuel supply gap  40  into the fuel inlet  42 . In some embodiments, the fuel inlet  42  is located within the venturi  44  to allow fuel to mix with air flowing through the venturi  44 . In the embodiment shown herein, the venturi manifold  12  has at least two venturis  44 . 
         [0027]    The venturi  44  consists of a converging nozzle  46  and a diverging nozzle  48 . The converging nozzle  46  includes converging walls  50  and the diverging nozzle  48  includes diverging walls  52 . The narrowest point of the converging walls  50  are illustrated by arrows A. The narrowest point is referred to as the throat  53 . In some embodiments as shown, the fuel inlets  42  are located at the throat  53  denoted by the arrows A. In accordance with well understood principles regarding a venturi, as air flows through the converging nozzle  46 , the air will speed up thereby creating a lower pressure. This lower pressure will create a suction force to draw fuel from the fuel inlet  42  into the air stream. The fuel and air mixture will then flow through the diverging nozzle  48 . 
         [0028]      FIGS. 4-7  will now be described showing flaps (described as a first flap  54  and a second flap  56 ) having various dimensions, weights, and orientations according to various conditions shown and described with respect to the various FIGS. While the term “flap” is used, it is to be understood and any movable obstruction may be used. 
         [0029]    In  FIG. 4 , the flaps  54  and  56  are shown in a closed position. The flaps  54  and  56  are weighted the same. Arrows F the note a direction of air flowing through the venturi  44 . The amount of air flowing through the venturis does not have enough velocity to cause the flaps  54  and  56  to pivot on the pivot shafts  32 . Gravity is keeping the flaps  54  and  56  in a closed position. In the closed position, fuel from the fuel inlets  42  located below the flaps  54  and  56  does not enter the air stream within the venturi. However, fuel does flow through the fuel inlet  42  located above the flaps  54  and  56 . Thus, some fuel does enter the air stream along the upper diverging wall  52 . Arrows B show the minimum size of the venturis  44  when the flaps  54  and  56  are closed. 
         [0030]    It should be understood that the flaps or obstructions  36 ,  54 , and  56  may be moved not only with air/fluid movement through the venturi but also by pressure. For example, in an initial condition, no fluid may be moving through a venturi but the flap  36 ,  54  and  56  may move to an open position as pressure increases due to the blower  22  starting from an off condition. 
         [0031]    In embodiments where the flaps  54  and  56  are located in the throat  53  as shown, the actuation of the flaps  54  and  56  block not only airflow through the venturi  44  but fuel flow coming out of a fuel inlet  42  located in the throat  53  near the cutoff airflow. For example, in such an embodiment as shown in  FIG. 4 , flap  56  is in the closed position, thus blocking airflow from below the pivot shaft  32  and fuel flow from the fuel inlet  42  located below the pivot shaft  32  in the venturi  44  in which flap  56  is located. Thus, the flaps  54  and  56  can be used to block flows to both the airflow and a fuel flow. 
         [0032]      FIG. 5  shows a venturi manifold  12  similar to that shown in  FIG. 4 . Arrows F show the direction of airflow flowing into the venturis  44 . In  FIG. 4 , the airflow is sufficient to cause the flaps  54  and  56  to pivot on the pivot shafts  32  to an open position. Now more air flows through the venturis  44  as the minimum size of the venturi as illustrated by arrows C is much larger. In addition, additional fuel is supplied from the fuel supply  38  as fuel is now flowing through all of the fuel inlets  42  both the fuel inlets  42  located above the flaps  54  and  56  and below the flaps  54  and  56 . 
         [0033]      FIG. 6  illustrates a venturi manifold  12  where the flap  54  is lighter than the flap  56 . In  FIG. 6 , air flows as denoted by direction arrow F into the venturi  44  with enough velocity to pivot flap  54  on the pivot shaft  32  to an open position but not with enough velocity to pivot flap  56  on the pivot shaft  32  to an open position. Under such conditions, the venturi  44  having flap  54  has a minimum cross-sectional area shown by arrow D to be larger than the minimum cross-section area as shown by arrow E of the venturi  44  equipped with flap  56 . Under such conditions, the top of venturi  44  having a cross-section area denoted by arrow D has more air and more fuel as fuel is flowing from both fuel inlets  42  located above and below the flap  54  in the open position whereas the lower venturi  44  has less air and fuel only flowing through the upper fuel inlet  42  located above the flap  56 . If the airflow was increased to overcome through the weight of the heavier flap  56 , then the flap  56  would move to an open position and would be as described and shown with respect to  FIG. 5 . 
         [0034]      FIG. 7 , illustrates yet another embodiment in accordance with the present disclosure. In  FIG. 7 , the two venturis  44  have different geometries. The lower venturi  44  has a larger minimum cross-sectional area than that minimum cross-sectional area of the upper venturi  44 . These are illustrated by arrows G and H. The minimum cross-sectional areas of the various venturis  44  may be selected according to fuel and air needs for a specific system  10  in the embodiment shown in  FIG. 7 . The flaps  54  and  56  have different weights. As air flows into the venturis  44  as shown in the direction illustrated by arrows F, the flap  54  is lighter than the flap  56 . The flap  54  will move from the closed position to an open position at a lower air velocity than the flap  56 . Thus, under certain conditions, the flap  54  is in an open position and the flap  56  may be in a closed position. Fuel will flow through the fuel inlets  42  into the air stream from both above and below the flaps  54  and  56  depending upon whether the flaps  54  and  56  are open or closed as described above. As discussed above, if the airflow is increased, then both flaps  54  and  56  may move to the open position as shown in  FIG. 5 . 
         [0035]    While the flaps  54  and  56  are shown in  FIG. 7  and the other FIGS. to pivot on pivot shafts  32 , the flaps, in other embodiments, may move from an open position to a closed position and vice versa in other ways besides pivoting. For example, the flaps  54  and  56  may slide between open and closed positions or move in other suitable ways. 
         [0036]    The various arrows A, B, C, D, E, G, and H, the note minimum cross-sectional areas of the venturis  44  when flaps  54  and  56  are in open or closed positions. While the terms “open” and “closed” are used, it should be understood that “open” may also refer to a partially open position as well as a fully open position. The various geometries for the minimum cross-sectional area of the venturis  44  may be selected according to desired needs of fuel and air for the various combustion systems  10 . In some embodiments, the flaps  36 ,  54 , and  56  cut off about half of the airflow that can flow through a venturi  44  when the flaps  36 ,  54 , and  56  are in the closed position. In other embodiments, the amount of airflow that may be blocked can be selected by one of ordinary skill in the art to satisfy a particular installation. Furthermore, various geometries and sizes of venturis  44  may be selected according to various needs by one of ordinary skill in the art after reviewing this disclosure. In some embodiments, air may flow through the venturi manifold  12  if all, some, or none of the flaps  54  and  56  are in an open position. In other embodiments, no air can flow through the venturi  44  if the flaps  54  and  56  are in a closed position. 
         [0037]    In some embodiments, the venturi manifolds  12  may have two, three, four or more venturis  44 . The venturis  44  may have the same or different sizes according to the needs of the various systems. The flaps  36 ,  54 , and  56  may be weighted the same or different according to the needs of an individual system. In addition to having different weights, other ways of causing the flaps  36 ,  54 , and  56  to open at different airflow conditions may be to use springs or friction devices to inhibit the ability of the flaps  36 ,  54 , and  56  to open unless air velocity reaches a certain point. The flaps  36 ,  54 , and  56  may also be operated by a controller and have an actuator to move the flaps  36 ,  54 , and  56 . 
         [0038]    Certain embodiments, in accordance with the present disclosure, permit airflow through a combustion system  10  to be scaled along a much larger range then traditional systems. If only a small amount of air and fuel is required then all or only one of the flaps  36 ,  54 , and  56  may close permitting only a small amount of air and fuel as needed to flow through the combustion system  10 . If more air is desired more flaps  36 ,  54 , or  56  may be moved to the open position thereby allowing an appropriate amount of air and also fuel to flow through the system  10 . 
         [0039]    The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Furthermore, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.