Patent Publication Number: US-2007114480-A1

Title: Vorticity generators for use with fluid control systems

Description:
FIELD OF THE DISCLOSURE  
      This disclosure relates generally to fluid control systems and, more particularly, to methods and apparatus to generate fluid vortices in stagnation areas in fluid control systems.  
     BACKGROUND  
      Typically, it is necessary to control process fluids in industrial processes, such as oil and gas pipeline distribution systems, chemical processing plants, and sanitary processes such as, for example, food and beverage processes, pharmaceutical processes, cosmetics production processes, etc. Generally, process conditions, such as pressure, temperature, and process fluid characteristics dictate the type of valves and valve components that may be used to implement a fluid control system. Valves typically have a fluid passageway, including an inlet and an outlet, which passes through the valve body. Other valve components, such as a bonnet, a valve stem or a flow control element may extend into the passageway. Often, the configuration of these components in the passageway results in fluid stagnation areas, which are particularly problematic in fluid control systems that require sanitary conditions. In the stagnation areas, the flow of fluid is reduced, air pockets may form and, as a result, microorganisms and other contaminants may accumulate within the valve and/or other areas along the path of fluid flow.  
       FIG. 1  is a cross-sectional view of an example of a known sliding stem plug valve  100 . The example valve  100  includes a valve body  102  that connects to a fluid pipeline (not shown) and receives an inlet fluid at an inlet passageway  104  which couples to an outlet passageway  106  through a valve seat  108 . A bonnet  110 , which is mounted to the valve body  102 , guides a valve stem  114 , an end of which is coupled to a flow control element or plug  112 . The plug  112  is configured to releasably engage the seat  108  to control or modulate the flow of the fluid through the passageway  104 ,  106 .  
      When the plug  112  is in the position shown in  FIG. 1 , the valve  100  is open and fluid travels in the direction of the arrows past the seat  108 . Fluid also flows into stagnation areas  116  and may not be adequately washed out during successive openings and closings of the plug  112 . Thus, the stagnation areas  116 , which are commonly referred to as dead space or dead legs, may accumulate fluid, air, microorganisms, and/or other contaminants and, consequently, contaminate the process fluid.  
      In the food processing, cosmetic and bio-technical industries, it is common to employ valves, pipes and other fluid control components that promote sanitary conditions by, for example, preventing the accumulation of contaminants within the fluid control components. One such example is shown in  FIG. 2  in which a single-seat angle valve  200  has a valve body  202  for connection to a fluid pipeline and receives an inlet fluid at an inlet passageway  204  under pressure for coupling to an outlet passageway  206  through a valve seat  208 . A bonnet  210  is mounted to the valve body  202  and guides a valve stem  214  that is coupled to a plug  212 . As the valve stem  214  slides within the bonnet  210 , the plug  212  releasably engages the seat  208 . Stem seal  216  and bonnet seal  218  seal the bonnet  210  to the stem  214  and valve body  202 , respectively.  
      In the design of  FIG. 2 , the bonnet seal  218  and the stem seal  216  are relatively close to the seat  208  and substantially flush with the side of the valve body  202  at the inlet passageway  204 . In this manner, the valve  200  provides a fluid flow path with reduced or minimal stagnation areas, thereby enabling the valve  200  to be used in fluid control applications that require sanitary conditions. However, the design shown in  FIG. 2  is relatively complex and expensive.  
     SUMMARY  
      In accordance with one example, a valve includes a valve body and a fluid passage therethrough. The fluid passage includes an inlet, an outlet and a stagnation area. The valve includes a control element within the fluid passage to control a flow of fluid through the passage and a vortex generating structure to direct a fluid within the fluid passage into the stagnation area.  
      In accordance with another example, a vortex generating apparatus includes a fluid communication element, a fluid stagnation area proximate to the fluid communication element, and a vortex generator coupled to the fluid communication element. The vortex generator is adapted to generate at least one vortex in the fluid stagnation area.  
      In accordance with yet another example, a fluid communication device includes a passage for communicating fluid through the fluid communication device, a stagnation area within the passage, and a diverting structure within the passage. The diverting structure is configured to divert fluid into the stagnation area. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a cross-sectional view of a known sliding stem valve.  
       FIG. 2  is a cross-sectional view of a known angle body sliding stem valve design that may be used in sanitary fluid control systems.  
       FIG. 3  is a cross-sectional view of an example angle body sliding stem valve including an example vortex generator.  
       FIG. 4  is a cross-sectional view of an alternative example angle body sliding stem valve with an alternative example vortex generator.  
       FIG. 5  is a partial cross-sectional view of another alternative example angle body sliding stem valve with another alternative example vortex generator. 
    
    
     DETAILED DESCRIPTION  
      In general, the example fluid control valves described herein include a valve body through which fluid may flow via a fluid passage having an inlet and an outlet. The fluid passage may have one or more stagnation areas in which fluids and/or contaminants may accumulate. To minimize and/or prevent the adverse effects of the stagnation area(s) (e.g., bacteria growth), the example fluid control valves described herein include a vortex generating structure configured to direct fluid into the stagnation area(s).  
      Some known fluid control valves incorporate fluid passage designs that are substantially void of stagnation areas. However, such fluid passage designs typically increase the complexity and manufacturing cost of a fluid valve. In contrast, the example fluid control valves described herein include a vortex generating structure that enables the use of relatively easy-to-manufacture (i.e., lower cost) valve designs while eliminating or minimizing the adverse effects of stagnation areas.  
      In one example, a fluid control valve includes a vortex generating structure integral with a valve bonnet and/or includes a vortex generating structure upstream and proximate to any stagnation area(s) within the valve. In another example, a fluid control valve employs a vortex generating structure in a section of pipe proximate to an inlet of the valve to impart adequate fluid turbulence to incoming fluid to facilitate the flushing of any stagnation area(s) within the valve.  
       FIG. 3  is a cross-sectional view of a known angle body sliding stem valve  300  including an example vortex generator  301 . As shown in  FIG. 3 , the example valve  300  includes a valve body  302  for connection to a fluid pipeline, or similar fluid communication element, and receiving an inlet fluid at an inlet passageway  304  under pressure for coupling to an outlet passageway  306  through a valve seat  308 . A bonnet  310  is mounted to the valve body  302  and includes an extension  312  that extends into the passageway  304  and terminates in a flange-shaped structure  314  that circumfuses the bottom of the extension  312 . In the example of  FIG. 3 , the flange-shaped structure  314  has a ramp-shaped cross-section. However, the flange-shaped structure  314  could alternatively have a curved cross-section.  
      A valve stem  316  extends through a center portion of the bonnet  310  and has one end that is configured to be operatively coupled to an actuator (not shown) and another end coupled to a plug  318  or other fluid control element adapted to allow and/or block fluid flow through the valve  300 . The stem  316  is axially slidable within the bonnet  310  and sealed to the bonnet  310  via a stem seal  320 . The bonnet  310  is further sealed to the valve body  302  via a bonnet seal  322 . The seals  320  and  322  may be O-rings or other suitable sealing structures that surround the stem  316  and the bonnet  310 , respectively, to prevent process fluid from leaking or seeping out of the valve  300 .  
      The plug  318  is adapted to axially engage the valve seat  308  and control the flow of fluid through the valve  300  via the passageways  304  and  306 . In the position shown in  FIG. 3 , the plug  318  is in contact with the valve seat  308  and the valve  300  is closed, i.e., process fluid will not flow through the valve  300  from the inlet passageway  304  to the outlet passageway  306 . When the valve stem  316  is raised, the plug  318  is lifted from the seat  308  to enable fluid to flow past the valve seat  308  and toward the outlet passageway  306 , i.e., the valve  300  is open.  
      In the open position or the closed position, process fluid including liquids and gases, may accumulate in a dead leg or stagnation area  324 , which is an area of fluid stagnation around the bonnet  310  near an upper portion of the extension  312 . However, the flange  314  alters the flow of the fluid in the passageways  304  and  306  as shown by example fluid flow arrows  350 . In particular, fluid flowing through the inlet passageway  304  strikes the flange  314 , which diverts or directs some of the fluid into the stagnation area  324  to create vortices or eddies therein. In other words, the flange  314  functions as a downstream flow impediment that creates a hydraulic jump, which dissipates energy as turbulence or vorticies. The turbulence or vortices clear out the stagnation area  324  by making them less stagnate, which breaks up or removes air pockets and cleans out microorganisms, fluids, and/or any other contaminants that have accumulated therein.  
      Generally, it is undesirable to create vortices, eddies, or other turbulence in process fluid systems because such turbulence is considered inefficient (i.e., vortices, eddies, turbulence, etc. tend to increase flow resistance). As is known, a straight-sided bonnet is relatively efficient and provides a relatively low flow coefficient or flow resistance. However, such straight-sided bonnets do not promote sanitary conditions for valves having a dead leg or stagnation area.  
      As described above in connection with the example valve  300 , the flange  314  functions as a vorticity generator, which creates vorticies, eddies, or turbulence in the stagnation area  324  and drives out gasses (e.g., air) or other stagnant fluids and creates a fluid velocity that prevents the accumulation and attachment of organisms, such as, for example, bacteria or other contaminants. Thus, the flange  314  causes at least some of the fluid passing through the valve  300  via the passageways  304  and  306  to be diverted or directed in a manner that cleans the stagnation area  324 .  
      The vortex generator  301  may be used to facilitate and/or improve clean-in-place (CIP), hot-water-in-place (HWIP), steam-in-place (SIP) and/or other well-known cleaning processes. For example, the vortex generator  301  may be used to direct cleaning chemicals, hot water, and/or steam into the stagnation area  324  as described above. When used with CIP systems, the vortex generator  301  increases efficiency of the cleaning process by requiring less rinse water after cleaning agents clean an inside surface of the valve  300 . Alternatively or additionally, the cleaning process can be performed using only hot water or a caustic material followed by hot water instead of a caustic material followed by steam. In any case, the vortex generator  301  of  FIG. 3  simplifies cleaning processes by requiring fewer steps and/or less cleaning material and, as a result, can significantly reduce the costs associated with cleaning a fluid control system.  
      In the example valve of  FIG. 3 , the flange  314  has an angled or ramp-shaped cross-section. However other shapes or configurations could be utilized to generate vortices in the stagnation area  324 . For example, the flange  314  could be implemented as a curved structure integrally formed with the extension  312  and/or the bonnet  310 . Alternatively or additionally, the flange  314  or other vortex generating structure may be a separate component that is coupled to the extension  312  and/or the bonnet  310 .  
      Furthermore, the vortex generator  301  may be used on other components in a fluid control system. For example, the example vortex generator  301  may be used in connection with T-mounted sensors in the process stream such as, for example, a temperature probe. A temperature probe mounted on the top of a pipeline may create dead legs in the adjacent area of the process stream. Coupling the sensor with a vortex generator such as the example vortex generator  301  would reduce the stagnation in the dead legs and promote sanitary conditions in a manner similar to that described above.  
      In an alternative embodiment shown in  FIG. 4 , a sliding stem valve  400  has neither an extension nor a flange as described in connection with the example valve of  FIG. 3 . In the embodiment of  FIG. 4 , the vortex generating structure includes a static propeller  455  coupled to a pipe  460  adjacent to an inlet passageway  404 . The propeller  455  has a central hub  456  to which blades  458  are coupled. The hub  456  is supported by a hoop structure  459  that allows coupling of the static propeller  455  to the pipe  460 . In alternative embodiments, the propeller  455  may also be coupled as a separate or modular device that is mounted between pipe flanges or sanitary fittings.  
      In the example of  FIG. 4 , the propeller  455  is fixed so that it does not spin or otherwise rotate relative to the pipe  460 . As streamlines or stream tubes of water pass through the propeller  455 , the shape of the blades  458  causes the fluid to form vortices as shown by the arrows  450 . The propeller  455  may be particularly useful in long pipelines in which a full laminar boundary layer has formed at the pipe wall. The vortices induced by the propeller  455  reduce the boundary layer that builds up near the walls of the pipe  460  and clean out a stagnation area  424  and/or other contaminants. Although the propeller  455  of the present example has four blades  458 , the propeller  455  may have any other number of blades.  
      Instead of, or in addition to the propeller  455 , individual blades may be attached to the pipe  460  interior without the hub  456 . Such individual blades, attached to the pipe  460  and separated by a longitudinal distance, impart a vortex in the fluid while minimizing fluid flow resistance. The number and placement of the individual blades permit a tradeoff between fluid flow resistance while causing fluid to spin with respect to the axis of the pipe  460 , thereby directing fluid into the stagnation area  424 . As with the flange  314  of the example shown in  FIG. 3 , the propeller  455  or individual blades of the present example facilitate or improve cleaning of the stagnation area  424  by preventing the accumulation of contaminants under normal operation with process fluids. Furthermore, the present example diverts cleaning fluids and/or hot water into the stagnation area  424 , thereby improving efficiency of the CIP, HWIP, SIP, and/or other cleaning processes.  
      In addition, the example propeller  455  may also be used in other areas of a fluid control system. For example, in a fluid control system such as, for example, a sanitary system, laminar boundary layers may form in a long straight run of a pipe. In that boundary layer the shear due to velocity is low enough that contaminants such as, for example, bacteria growth, may accumulate. Positioning a propeller  455 , or other vortex generating structure, in the straight run would generate swirling turbulence throughout the stream, even along the pipe walls, which helps disintegrate the boundary layer and, thus, clear out the contaminants. Not only would this configuration enable effective cleaning at low velocities, the vortex generating structure may clean the pipes better than current line velocities.  
      In an alternative embodiment shown in  FIG. 5 , a sliding stem valve  500  has a bonnet  510  including a vortex generating spiral structure, such as spiral grooves  565 . The grooves  565  may be integrally formed on a portion of the bonnet  510  that extends into the passageways  504  and  506  and extends around the lower portion of the bonnet  510  to divert fluid flow into a stagnation area  524 . At least some of the fluid flowing through the valve  500  impinges on the bonnet  510  and engages the spiral grooves  565  to cause the fluid to rotate about the bonnet  510 , which causes at least some of the fluid to be directed into the stagnation area  524  as shown by arrows  550 . Additionally, the spiral grooves  565  may extend along the full length of the bonnet  510  or only portion thereof. Also, the geometry of the spiral grooves  565  may contain full and/or partial twists. As described above with the other example vorticity generators and fluid diverting structures, the spiral grooves  565  may be used to facilitate CIP, HWIP, SIP and/or any other cleaning process.  
      In yet another alternative embodiment, the spiral structure includes a spiral ridge instead of the spiral grooves  565  of  FIG. 5 . Such a spiral ridge, formed around an outer portion of a bonnet, may further include a sloped, curved, and/or ramp-shaped cross-section. Fluids striking the ridge are diverted into the stagnation area  524 .  
      The example vortex generating structures could be used to reduce the need for cleaning processes to be performed in fluid communication systems due to a reduction and/or prevention of the stagnation of fluid in a dead leg or other stagnation area(s). Such a reduction and/or prevention of fluid stagnation promotes sanitary conditions and decreases the presence of contaminants in the process fluid. For example, increased turbulence in fluid stagnation areas reduces or eliminates conditions favorable to bacterial growth, thereby decreasing the frequency at which cleaning processes must be performed on a fluid distribution or control system. This decreased need for cleaning reduces cleaning costs including the costs associated with downtime of the fluid processing system.  
      Further, the example vortex generating structures enable cleaning processes (e.g., CIP, HWIP, SIP, etc.) to operate more efficiently by directing or diverting cleaning chemicals, steam, and/or hot water into stagnation areas. The increased efficiency of cleaning operations may decrease the amount of chemicals and/or energy needed to perform the cleaning processes.  
      Still further, the example vortex generating structures could be coupled to or formed within other structures or components of a valve, pipeline or other fluid or material communication element or device. For example, a temperature or other sensor in a valve or a pipe may be fitted with a ramp-shaped, curved or spiral structure, such as the example described above with respect to  FIG. 3 , to direct fluid into stagnation areas. In addition, the example vortex generating structures described herein may be used at T-junctions, Y-junctions and/or inlets and outlets of pipelines or tanks.  
      Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.