Abstract:
A flow meter for measuring fluid flow in a tubular that includes an obstruction suspended in a path of the fluid flow, and where the obstruction has a conical shape. The obstruction can be conically shaped on its upstream and downstream ends, or can be conically shaped only on its upstream end. When only the upstream end is conically shaped, the downstream end can be substantially planar or shaped like a hemisphere. Optionally, the aspect ratio of the obstruction can be changed by manipulating supports that suspend the obstruction within the flow meter.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present disclosure relates to a flow meter having a cone shaped flow element. The present disclosure also relates to a flow meter having a flow element with dimensions that are selectively changeable. 
     2. Description of Prior Art 
     Facilities that handle fluids, such as refineries, chemical processing plants, terminals for loading and offloading fluids, transmission pipelines, and the like, typically employ flow meters within flow lines for measuring fluid flowrates through the flow lines. While some flow meters monitor flow external to a flow line, most flow meters have components within the flow line that interact with the fluid to obtain a measure of the flowrate. Some flow meters include rotating, elements, such as spinners or propellers that rotate in response to the fluid flowing past the flow meter. These flow meters monitor the rotational velocity of the rotating element and correlate it to the fluid velocity. 
     Other types of flow meters introduce a temporary restriction in the cross sectional area of the fluid stream and monitor a pressure differential created by flowing the fluid across the restriction. One type of restriction is an orifice plate, which as the name implies, is a plate set transverse to the flow with an orifice through axially formed through its mid portion. Another restrictive flow meter incorporates a Venturi tube with a reduced diameter throat through which the fluid flow being monitored is directed. Additional examples of flow meters restrict the cross sectional area of flow by suspending an obstruction in the path of the fluid flowing through the flow meter. 
     SUMMARY OF THE INVENTION 
     Disclosed herein is an example of a flow meter for measuring a flow of fluid that includes a housing, an obstacle suspended in the flow of fluid that is selectively changeable between configurations that occupy different percentages of a cross sectional area of the flow of fluid, and a pressure sensor in communication with the flow of fluid and that is selectively monitors pressure in the flow of fluid. The pressure sensor can be made up of an upstream pressure sensor that is disposed upstream of the obstacle; here the flow meter includes a downstream pressure sensor that is disposed downstream of the obstacle. Further in this example, the upstream pressure sensor can include an upstream pressure tap formed through a sidewall of a tubular in which the flow of fluid is directed, and wherein the downstream pressure sensor includes a downstream pressure tap formed through the sidewall of the tubular. The flow meter can further include a differential pressure sensor that is in communication with the upstream and downstream pressure sensors. In an example, the obstacle has an upstream end that is conically shaped and that has an outer surface that converges to a point, wherein a downstream end of the obstacle is conically shaped and has an outer surface that converges to a downstream point that is oriented in a direction away from the upstream point, and wherein the upstream and downstream ends are directly adjacent one another to define a ridge that circumscribes a mid-portion of the obstacle. The flow meter can include struts mounted to the upstream and downstream ends of the obstacle and that suspend the obstacle in the flow of fluid. In an embodiment, the obstacle has a downstream end with a shape that can include a planar surface or a hemispherical surface. A support may be included that mounts to the obstacle and which can selectively exert a radial force onto the obstacle for changing configurations of the obstacle. The obstacle can include a flexible frame. Optionally included is a cover over the frame that is substantially fluid impermeable. The support can be an upper support that includes a connecting rod that couples to the obstacle and a stud that extends from the connecting rod through a sidewall of the housing. The flow meter can further include a lower support that includes a connecting rod coupled to the obstacle and a stud that extends from the connecting rod through a sidewall of the housing. In one example, the flow meter includes spring coupled between the upstream end of the obstacle and a strut. 
     Also described herein is an example of a flow meter for measuring a flow of fluid and which includes a tubular housing intersected by the flow of fluid, and that is set inline in a flow line that handles the flow of fluid, an obstacle suspended in the tubular housing and in the path of the flow of fluid that is selectively changeable into multiple configurations that have varying diameters, and pressure taps formed through a sidewall of the tubular housing that are in communication with the flow of fluid. A differential pressure sensor can optionally be included that is in communication with the pressure taps. Changing the obstacle into different configurations changes a cross sectional percentage that the obstacle occupies in the flow of fluid. A support can be included that connects to the obstacle for selectively changing the obstacle into different configurations. In one example, the support includes a connecting rod having an end coupled with the obstacle, a stud having an end connected to an end of the connecting rod distal from the obstacle, and wherein an end of the stud projects radially through a sidewall of the tubular housing. The obstacle configuration can be changed manually or automatically. In one example of manually changing the configuration, threaded adjustment members couple to the obstacle, so that rotating the adjustment member alters obstacle diameter. An example of automatic changing includes sensing differential pressure across the obstacle, and making adjustments based on the sensed pressure. 
     An example of a method of measuring a flow of fluid is described herein and which includes monitoring a flow of fluid across a conically shaped obstacle, changing a configuration of the obstacle to change a percentage of the cross sectional area of the flow of fluid occupied by the obstacle, and sensing a pressure in the flow of fluid proximate the obstacle. The step of changing a configuration of the obstacle can be based on a value of pressure sensed in the flow of fluid. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a side partial sectional view of an example of a flow meter having a flow element of varying configurations. 
         FIG. 2  is a side partial sectional view of an alternate embodiment of a flow meter having a flow element of varying configurations. 
         FIG. 3  is a schematic representation of a process circuit having flow meters that can be one or more of the types of  FIGS. 1 and 2 . 
     
    
    
     While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF INVENTION 
     The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. In an embodiment, usage of the term “about” includes +/− 5% of the cited magnitude. In an embodiment, usage of the term “substantially” includes +/− 5% of the cited magnitude. 
     It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. 
       FIG. 1  shows in a side partial sectional view an example of a flow meter  10  that is set between upstream and downstream portions  12 ,  14  of a fluid flow line. Flow meter  10  includes an annular housing  16  with an upstream flange  18  on its upstream end and downstream flange  20  on its downstream end. Upstream and downstream flanges  18 ,  20  respectively connect to flanges  22 ,  24  on the upstream and downstream portions  12 ,  14 . Shown suspended within housing  16  is a flow element  25  with upstream and downstream ends  26 ,  27 . In the illustrated example, upstream end  26  has a generally conical in shape, and converges to a point distal from downstream end  27  and directed into a flow of fluid F. Downstream end  27  has a generally domelike shape with an apex that is substantially coaxial with upstream end  26  and on a side of downstream end  27  distal from upstream end  26 . The base portion of each of the upstream and downstream ends  26 ,  27  meet at a middle portion of the flow element  25 . Struts  29 ,  30  are shown mounted in the inner surface of the housing  16  and respectively couple with the upstream and downstream ends  26 ,  27  to provide anchoring supports for the flow element  25 . 
     An upstream pressure tap  32  is shown formed through a sidewall of the housing  16  and upstream of strut  29 . A downstream tap  34  extends through a sidewall of housing  16  and downstream of strut  30 . Embodiments exist wherein the taps  32 ,  34  are adjacent to struts  29 ,  30 , or on the opposite side thereof. Lengths of tubing  36 ,  38  have ends that connect respectively to the upstream and downstream pressure taps  32 ,  34 . On ends opposite to their connection to the taps  32 ,  34 , the lengths of tubing  36 ,  38  communicate with a differential pressure sensor  40 . Thus, when the flow of fluid F makes its way through the upstream portion  12  and into the flow meter  10 , the cross-sectional area of the flow of fluid F is reduced by the presence of the flow element  25 , thereby introducing a pressure drop within flow meter  16 . By sensing pressures of the flow of fluid F at the pressure taps  32 ,  34 , and comparing the sensed pressures with the differential pressure sensor  40 , a pressure drop due to the presence of the flow element  25  can be measured. Further, applying Bernoulli&#39;s theorem to the measured pressure drop along with physical parameters of the flow element  25  and the fluid F, a value for a fluid flow rate can then be calculated. 
     The flow element  25  of  FIG. 1  is selectively changeable into different configurations; winch in turn can selectively change the diameter of the flow element  25  to one or more designated values. Embodiments exist where the changing configurations also changes the percentage of the cross-sectional area of the flow of fluid F that is occupied by the flow element  25 . In this example, the flow element  25  includes a frame  44  made of elongate structural elements that form the general outline of the flow element  25 . Arranged over the frame  44  is a rib array  46 , where rib array  46  is a collection of elongate elements, which in one example is greater than the number of elongate elements making up frame  44 . The application of the rib array  46  over frame  44  helps to give the outer surface of the flow element  25  a more uniform and continuous shape and to resemble a solid member. Over the rib array  46  and frame  44  is a membrane like cover  48  that is formed from a material that is generally impermeable by fluid. In an embodiment, cover  48  is pliable and generally conforms to the outer surface of the rib array  46  and frame  44 . Sample materials for cover  48  include polymers, elastomers, composites, metals, and combinations thereof. 
     Further included in the embodiment of the flow meter  10  of  FIG. 1  are springs  50 ,  52  which mount respectfully on the upstream and downstream ends  26 ,  27  of flow element  25 . On ends opposite to their connection to flow element  25 , springs  50 ,  52  couple with the struts  29 ,  30  to thereby exert a stabilizing force on the flow element  25 . Further illustrated is that the cover  48  couples to spring  52  on the downstream end of flow element  25 . Sleeves  53  are provided over each of springs  50 ,  52  that provide a protective covering and shield the springs  50 ,  52  from debris. Optional push rods  54 ,  56  are shown on the upstream and downstream ends  26 ,  27  that insert into the struts  29 ,  30  and which provide support of the flow element  25  within housing  16  as well as radially centering flow element  25  within the housing  16 . 
     Still referring to  FIG. 1 , a lower support  58  is shown that contributes to radially propping the flow element  25  within housing  16 . Lower support  58  includes a lower connecting rod  59  shown attached to flow element  25 , and could be connected to the frame  44 , rib array  46 , or both. A stud  60  that is at least partially threaded on its outer surface has an end connected to an end of lower connecting rod  59  distal from flow element  25 . A bellows  62  is included within lower support  58  which is axially resilient, and circumscribes a portion of stud  60  within housing  16 . Stud  60  projects through a bore  64  formed in a sidewall of housing  16 . Nuts  66 ,  68  coaxially thread onto the lower end of the stud  60  for securing the lower support  58  to housing  16 . Bellows  62  can optionally be welded to the lower connecting rod  59  and to the inner surface of housing  16 . A seal (not shown) lines bore  64  to prevent fluid leakage across the lower support  58  and to the outside of housing  16 . An upper support  69  provides attachment of the flow element  25  to housing  16 , and includes an upper connecting rod  70  shown connected to frame  44  of flow element  25  on an end that is distal from where flow element  25  attaches to lower support  58 . Connecting rod  70  can be connected to the flow element  25  in the same manner lower connecting rod  59  connects to flow element  25 . A stud  71  has an end that attaches to an end of upper connecting rod  70  distal from flow element  25 . A bellows  72  circumscribes a portion of stud  71  disposed within housing  16 , and opposing ends of the bellows  72  can be welded to the upper connecting rod  70  and inner surface of housing  16 . An end of stud  71  projects through a bore  74  formed radially in the housing  16 . Portions of the outer surface of stud  71  are threaded. Nuts  76 ,  78  threadingly mount onto the end of stud  71  outside of housing  16 . A seal (not shown) provides sealing around bore  74  to prevent fluid from leaking therethrough. It should be pointed out that bores  64 ,  74  can be on opposite sides of the housing  16  (i.e. 180° apart around the axis of the housing  16 ), or angularly spaced apart at less than 180° from one another. Further, the bores  64 ,  74  can be at the same or different axial locations along the housing  16 . 
     In one example of operation, selectively loosening or tightening nuts  76 ,  78  radially displaces the actuation rod  70  with respect to the sidewall housing  16 ; which in turn pulls or pushes against the rib array  46  and frame  44  and changes their respective diameters. As the diameters of the rib array  46  and frame  44  change, so do the diameters of the cover  48  and flow element  25 . As the bellows  62 ,  72  connect between the connecting rods  59 ,  70  and inner surface of housing  16 , the bellows  62 ,  72  will expand or compress with changing diameter of the flow element  25 . Providing sealing interfaces between the bellows  62 ,  72  and connecting rods  59 ,  70 , and bellows  62 ,  72  and housing  16  forms a flow barrier between the inside of the housing  16  and bores  64 ,  74 . Altering the configuration of flow element  25  modifies the cross-sectional area occupied by the flow element  25  in the overall flow of fluid F. As such, reconfiguring the flow element  25  can selectively affect a pressure reading(s) taken by the differential pressure sensor  40 . In this example, springs  50 ,  52  may elongate to allow for the radial expansion of the flow element  25 . Changing the physical dimensions of the flow element  25  during use allows flow meter  10  to readily adapt to changes in the fluid flow, such as variations in the fluid flow rate due to different process scenarios or upset conditions. In one embodiment, a flow rate of the fluid F is based on a pressure sensed in the flow meter  10 . The pressure sensed can be pressure at taps  32 ,  34 , or a difference between the pressure at taps  32 ,  34 , such as that measured by differential pressure sensor  40 . 
     One or more forms of the Bernoulli equation can be used to estimate a flow rate of the fluid F based on the sensed pressure(s). It is within the capabilities of one skilled in the art to correlate the sensed pressures to a rate of the flow of fluid F. Moreover, factors relating to the changing shape and/or configuration of the flow element can be determined without undue experimentation. In one alternate embodiment, the configuration of the flow element  25  can be changed in response to pressure sensed upstream of the flow element  25 , downstream of the flow element  25 , across the flow element  25 , or combinations thereof. A controller (not shown) can be included that is in communication with the pressure taps and automatically alters the configuration of the flow element  25  based on comparing a sensed pressure with a designated pressure. 
     Shown in  FIG. 2  is another example of a flow meter  10 A, which has a flow element  25 A, like the flow element  25  of  FIG. 1 , has an outer diameter that can be selectively changed via manipulation of an actuation rod  70 A. Unlike the flow element  25 A of  FIG. 1 , however, flow element  25 A has a downstream end  27 A that has a generally conical shape and whose outer surface converges to a point proximate its coupling with spring  52 A and adjacent strut  30 A. Similarly, the flow element  25 A includes a frame  46 A with elongate elements that give the general shape of the double-ended cone, and an overlay of the rib array  46 A which provides a better approximation of a continuous outer surface of the flow element  25 A. Also included in the example of  FIG. 2 , is a cover  48 A which spans the outer surface of frame  44 A and rib array  46 A, and made from a material that is generally impermeable to fluid, thereby giving characteristics of the flow element  25 A to be that of a substantially solid element. Also, similar to the embodiment of  FIG. 1  is that the :flow meter  10 A of  FIG. 2 . includes upper and lower supports  69 A,  58 A that respectfully include connecting rods  70 A,  59 A, bellows  72 A,  62 A, and studs  71 A,  60 A. The percentage of the cross sectional area of the flow of fluid F occupied by the flow elements  25 ,  25 A is (D FE   2 /D F   2 )*100, where D FE  is diameter of the flow elements, and D F  is the diameter of the flow of fluid F. 
       FIG. 3  is a schematic representation of an example of a process circuit  80  in which the flow elements described herein may be employed. In the example, a column  82  is shown having a bottoms line  84  which corrects fluid within column  82  to a pump  86  for pressurization. Downstream of pump  86  is one example of an application of a flow meter  88  and where flow meter  88  is positioned just upstream of a control valve  90 . In this example, flow information is forwarded from the flow meter  88  to the control valve  90 . A reflux line  92  routes fluid exiting control valve  90  back into column  82 . A gravity line  94  is shown branching from bottoms line  84  and upstream of pump  86  which delivers fluid in bottoms line  84  to a destination vessel  96 . A flow meter  98 , which can be any of the other flow meters described herein, is shown provided in gravity line  94 . As such, flow meters  88 ,  98  can provide information about the flow of fluid flowing within lines  92 ,  94  respectively. 
     The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. for example, the fluid being monitored by the flow meters described herein can be liquid, vapor, or multi-phase flow. Additionally, pressures at each of the pressure taps  32 ,  32 A,  34 ,  34 A can be monitored and recorded in addition to monitoring a pressure differential between axially spaced apart taps. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.