Patent Publication Number: US-2023137451-A1

Title: Heavy cradle for replaceable coriolis flow sensors

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No. 63/274,841, filed Nov. 2, 2021. The subject matter of all of the foregoing is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     This disclosure relates generally to Coriolis flow sensors. 
     2. Description of Related Art 
     Many applications require the controlled flow of fluids. A flow process system usually includes a number of flow sensors to measure the flow rate of fluids. Coriolis flow sensors measure the flow rate of fluids based on vibrations caused by the Coriolis effect of fluid flowing through the sensor. Cross-talk or destructive interference is a phenomenon where two or more flow sensors may interfere with each other. The cross-talk can include electrical cross-talk, mechanical cross-talk, and/or fluid pulsation based cross-talk. The cross-talk can cause inaccurate measurement by the flow sensors. A flow process system can also include pumps. Operation of the pumps can also interfere with vibration within the flow sensors, which also causes inaccurate measurement by the flow sensors. Vibrations from other devices either external to the flow process system (but in close proximity) or on the flow process system such as solenoid valves, pinch control valves and other electromechanical devices can also cause electrical interference or mechanical interference to the proper functioning of these Coriolis flow sensors 
     In order to reduce these unwanted effects, a flow sensor may be permanently attached to a large mass. For example, a flow sensor may be welded to a large metal structure. However, these metal masses can be expensive and are not suitable for single use/disposable applications. Also, sterilization of flow sensors having metal enclosures is typically implemented by using chemicals, which is not as effective and can cause malfunction of the flow sensors. Thus, improved technologies for mitigating cross-talk and pump and other external interference are needed. 
     SUMMARY 
     Embodiments relate to a flow process system comprising a cradle and a locking mechanism. The cradle has a mounting structure for a Coriolis flow sensor, and the cradle has significantly more mass than the Coriolis flow sensor. The locking mechanism is used to lock and unlock Coriolis flow sensors in place on the mounting structure. The locking mechanism produces sufficient locking force when locked that the Coriolis flow sensor and cradle vibrate as a unitary body. In this way, the Coriolis flow sensor has effectively more mass when used as part of the flow process system, but Coriolis flow sensors may be easily replaced by unlocking the locking mechanism, removing the current Coriolis flow sensor and replacing it with another. This replacement of sensors after completing a process batch is critical to single use manufacturing of bio-pharmaceuticals and vaccines such as the Covid-19 vaccine. 
     Other aspects include components, devices, systems, improvements, methods, processes, applications, and other technologies related to any of the above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure have other advantages and features which will be more readily apparent from the following detailed description and the appended claims, when taken in conjunction with the examples in the accompanying drawings, in which: 
         FIG.  1 A  shows a perspective view of a Coriolis flow sensor and a corresponding cradle. 
         FIG.  1 B  shows a cross section view of the Coriolis flow sensor. 
         FIG.  1 C  shows a perspective view of the Coriolis flow sensor locked into the cradle. 
         FIG.  1 D  shows top, front and side views of the Coriolis flow sensor locked into the cradle. 
         FIGS.  2 A and  2 B  show top perspective and bottom perspective views of the cradle. 
         FIG.  3    shows the cradle attached to a skid. 
         FIGS.  4 A and  4 B  show perspective views of another embodiment of a Coriolis flow sensor and corresponding cradle. 
         FIGS.  5 A and  5 B  show perspective views of yet another embodiment of a Coriolis flow sensor and corresponding cradle. 
         FIGS.  6 A and  6 B  show perspective views of yet another embodiment of a Coriolis flow sensor and corresponding cradle. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The figures and the following description relate to preferred embodiments by way of illustration only. It should be noted that from the following discussion, alternative embodiments of the structures and methods disclosed herein will be readily recognized as viable alternatives that may be employed without departing from the principles of what is claimed. 
     Reference is first made to  FIGS.  1 - 2   , which show different views of an example embodiments of a Coriolis flow sensor  150  and corresponding cradle  100 .  FIG.  1    shows both the Coriolis flow sensor  150  and the cradle  100 , where  FIG.  1 A  is an exploded view,  FIG.  1 B  shows just the flow sensor,  FIG.  1 C  shows the assembled system, and  FIG.  1 D  shows top, front and side views of the assembled system.  FIG.  2    shows just the cradle  100  and locking mechanism  140 , where  FIGS.  2 A and  2 B  are perspective views. 
     The Coriolis flow sensor  150  is a device that measures the flow rate of a fluid based on vibrations caused by the Coriolis effect of the fluid flowing through the sensor. The flow sensor  150  can be seen in cross section in  FIG.  1 B . The flow sensor  150  includes an inlet  152 , a flow tube  154  (or two flow tubes in some designs) and an outlet  156 . This provide a flow path for a fluid through the flow sensor  150 . The flow tubes  154  can vibrate, for example as driven by magnets and coils. As the fluid flows through the flow tubes  154 , Coriolis forces produce a twisting vibration of the flow tubes, resulting in a phase shift in the vibration of the flow tubes. The fluid flow also changes the resonant frequency of the flow tubes. The flow sensor  150  includes transducers that generate electrical signals that are sensitive to the phase shift and/or change in resonant frequency. These signals may be processed to determine the mass fluid flow rate and/or density of the fluid. 
     The figures show examples of Coriolis flow sensors, but it should be understood that other types of Coriolis flow sensors may also be used. The number and shapes of tubes, the material and construction of the tubes and flow sensor, and the arrangement of the inlet and outlet may all be changed depending on the specific design of the Coriolis flow sensor. Typically, Coriolis flow sensors are sized with connections from 1/16″ to 1″ hose barbs or tri-clamp fittings. Other types of fittings may also be used on Coriolis flow sensors. Typical flow ranges of these flow sensors range from 0.05 gm/min to 0.5 gm/min for the smallest ( 1/16″ hose barb connections) size to 10 kg/min to 100 kg/min for the largest (1″) size. Typical accuracies range from 0.1% to 1.00% of actual reading. 
     Because Coriolis flow sensors operate based on changes in the vibration of the flow tubes, vibration effects that are caused by sources other than the fluid flow may introduce inaccuracies. For example, if the flow sensor and other devices are mounted on a common support structure, then vibrations from pumps and other devices may mechanically couple to the flow sensor through the supporting structure. The vibration of the flow tubes may also be distorted or otherwise changed through resonant coupling to the surrounding support structure. 
     Zero drift is one such effect. Coriolis flow sensors are electrically powered on, even when they are not measuring flow. So when there is no flow being pumped or flowing through the Coriolis Flow tubes, the tubes continue to vibrate. Sometimes these tubes are empty and sometimes there is liquid in these tubes. Zero drift is a phenomenon which shows some minimal flow rate occurring when there is no real actual flow. One instance of zero drift is when there is dormant fluid left in the Coriolis flow tubes and a certain amount of sloshing occurs. This minimal flow rate is very small and is usually a very small percentage of the minimum flow rate of each Coriolis flow sensor. In addition, vibrations from external mechanical devices such as pumps and valves also cause zero drift by interfering with the analog or digital output signal from a Coriolis flow sensor by contributing to it. 
     One way to reduce zero drift is to increase the mass of the flow sensor. More mass dampens out external mechanical vibrating interferences and also the sloshing of dormant liquid will be subdued due to heavier mass. 
     However, in some applications, the Coriolis flow sensors are not permanent. They are intended to be replaced fairly regularly. They may even be single use or considered to be disposable. Single use or disposable Coriolis flow sensors are used in the bio-pharmaceutical and pharmaceutical industries to manufacture vaccines including vaccines for Covid-19, active pharmaceutical ingredients for cell and gene therapy and nuclear medicine manufacturing. These kinds of single use or disposable Coriolis flow sensors can also be used in specialty fine chemical manufacturing processes where the chemical may corrode away metal Coriolis flow sensors very quickly. 
     In these cases, it is desirable to make the Coriolis flow sensor as lightweight and inexpensive as possible, so making a large and massive Coriolis flow sensor is not desirable. In addition, some applications may also require the sterilization of flow sensors. Metal is more difficult to sterilize, so making Coriolis flow sensors with metal flow tubes or with large chunks of added metal mass also is not desirable. In these cases, the flow tubes  154  and much of the rest of the Coriolis flow sensor may be made from non-metal materials such as polymer materials, including Polyetheretherketone (PEEK), Perfluoroalkoxy polymers (PFAs), polyvinylidene difluoride (PVDF), Polytetrafluoroethylene (PTFE), and Fluorinated ethylene propylene (FEP). For further examples, see U.S. patent application Ser. No. 16/837,635 “Polymer-Based Coriolis Mass Flow Sensor Fabricated Through Casting,” which is incorporated by reference in its entirety. Gamma irradiation may be used to sterilize the flow sensor, in which case the flow sensor is constructed from materials that are gamma irradiatable, for example up to a minimum of 50 kGy which may be the irradiation levels used for sterilization in certain bio-pharma applications. 
     In the examples shown herein, the effective mass of the Coriolis flow sensor  150  is increased by locking it to a heavy cradle  100  when it is in use. The cradle  100  has a mass that preferably is at least 10 to 30 times the mass of the Coriolis flow sensor. For example, typical Coriolis flow sensors may have masses in the range of 0.2 kg˜3 kg and typical mass for the heavy cradle may then be 5 kg˜80 kg. 
     The cradle  100  has a mounting structure  114  (see  FIG.  2 A ) for the Coriolis flow sensor  100 , and a locking mechanism  140  is used to lock and unlock the Coriolis flow sensor in place on the mounting structure. The locking mechanism produces sufficient locking force when locked that the Coriolis flow sensor  150  and cradle  100  (as shown in  FIG.  1 A ) vibrate together as a unitary body. 
     In the example of  FIGS.  1 - 2   , the cradle  100  includes a rectangular metal collar  110  which accounts for a significant amount of the mass of the cradle. The collar  110  has a rectangular aperture with an interior lip  114 , which is most visible in  FIG.  2   . The lip is also rectangular and annular in shape. The flow sensor  150  includes a plastic housing with a ridge  158 . The ridge  158  fits into the aperture of the metal collar  110  and presses against the lip  114 . The locking mechanism  140  applies force to the ridge  158  to hold the ridge rigidly against the lip  114 . The flow tubes  154  protrude through the annular opening in the lip  114 . 
     In this example, the locking mechanism  140  uses thumb screws  142  to create the force. When tightened, the thumb screws  142  apply pressure to tongues  144 , which in turn press the ridge  158  against the interior lip  114  of the metal collar  110 . The thumb screws are designed to apply a specific amount of force. In the example shown, the force is applied at four locking points arranged in a rectangular shape, although other arrangements are also possible. The applied force should be large enough to adequately reduce vibration of the flow sensor  150  relative to the collar  110 . As a result, the flow sensor  150  and cradle  100  will vibrate as a unitary body and the cradle  100  will effectively increase the mass of the flow sensor  150 , rather than the two vibrating relative to each other. For example, each of the thumb screws  142  may apply 3 Newton-meters (Nm) of force or more, to hold the flow sensor  150  and cradle  100  rigidly relative to each other. This is an aggregate force of 12 Nm or more for all of the thumb screws. In other designs, lower locking forces may be acceptable, for example 10 Nm or more, or 5 Nm or more. 
     Applying uniform force is also important. Applying the same force at the four locking points allows for the pressure to be balanced. If the forces at the different locking points were not the same, the sensor would be imbalanced and the zero drift and resulting inaccuracy would be higher. In  FIGS.  1 - 2   , the same amount of force should be applied to each locking point. For example, the force applied at each of the locking points may be within 15% of each other, or more preferably within 10%, within 5% or even within 1% of each other. 
     One advantage of using thumb screws  142  is that the locking mechanism may be operated manually. The thumb screws  142  may be loosened, the tongues  144  rotated or swiveled away to release the flow sensor  150 , and the flow sensor removed and replaced with another flow sensor. This facilitates the replacement of flow sensors, including disposable and single use flow sensors. In some single use or disposable applications, the flow sensors may be removed and replaced in one minute or less. 
     The cradle  100  also includes enclosure  120 , which encloses the rest of the Coriolis flow sensor. The enclosure also adds mass. The enclosure shown in  FIGS.  1 - 2    includes a cable hole  122  (see  FIG.  2 B ) to allow power and data connections to the flow sensor. 
       FIG.  3    shows the cradle  100  attached to a skid  370 . A skid is a mechanical framework on which equipment may be mounted. In this example, the cradle  100  is attached to a metal plate or panel  375 , which is attached to the skid  370 . A vibration dampening gasket  380  is positioned between the cradle  100  and the plate  375 . In the vertical direction, the cradle  100  is supported by cross members  377 A (an L bracket) and  377 B (a cross beam of the skid). Vibration dampening gaskets  387 A and  387 B are positioned between the cradle  100  and the cross members  377 A and  377 B. 
     Note that the heavy cradle  100  does not make direct contact with any part of the skid  370 . It is always separated by vibration gaskets  380 ,  387 . The gaskets  380 ,  387  provide vibration isolation between the cradle  100  and the skid  370  (and other components mounted on the skid). For example, the vibration gaskets may significantly dampen low frequency vibrations. 
     The heavy cradle  100  adds mass to the Coriolis flow sensor  150 , and the vibration gaskets  380 ,  387  isolate the cradle and flow sensor from the rest of the flow process system. As a result, zero drift is reduced. For example, for smaller size sensors (e.g., tubing of ½ inch and less), zero drift was reduced from 100 g/min to 2.5 g/min. Typical minimum flow rate for these sensors is 500 g/min, so the zero drift is reduced to less than 1% of the minimum flow rate. For larger sensors (e.g., ¾ and 1 inch tubing), zero drift was reduced from 200 g/min to 25 g/min. A typical minimum flow rate for these sensors is 6 kg/min, so the zero drift is reduced to less than 1% of the minimum flow rate. 
       FIGS.  1 - 3    show one example. Other variations will be apparent.  FIGS.  4 - 6    show perspective views of additional embodiments of a Coriolis flow sensor  450 ,  550 ,  650  and corresponding cradle  400 ,  500 ,  600 . In  FIG.  4   , the flow sensor  450  has a vertical configuration, whereas the flow sensors in previous figures are in-line configurations. In an in-line configuration (see  FIG.  1   ), the inlet  152  and outlet  156  are in line with each other, but the flow typically is diverted in order to flow through the flow tubes. In a vertical configuration of  FIG.  4   , the inlet  452  and outlet  456  are not aligned with each other, but the flow is more in line with the flow tubes. The cradle and mounting structure may be designed to accommodate multiple different flow sensors, including both in-line Coriolis flow sensors and vertical Coriolis flow sensors. In addition, in  FIG.  4   , the locking points  440  are on the corners rather than along the sides. 
     In  FIG.  5   , the cradle  500  includes the collar  510  but does not have an enclosure. The flow sensor  550  protrudes through the collar  510  and is visible below the collar, as shown in  FIG.  5 B . 
     In  FIG.  6   , the Coriolis flow sensor has an in-line configuration with inlet  652  and outlet  656 . It also includes an integrated dampener  662  and integrated pressure sensor  664 . The dampener  662  is located on the inlet side of the flow sensor. The integrated dampener reduces vibrations in the fluid flow itself, for example as may be caused by a pulsating pump. Example dampeners are described in U.S. patent application Ser. No. 16/994,611 “Flow Dampener in Flow Measurement System,” which is incorporated by reference in its entirety. Integrating the dampener and pressure sensor reduces the overall size and space requirement, compared to free-standing dampeners and pressure sensors that are connected to tubing on the inlet or outlet. It also reduces the amount of tubing required, which in turn reduces the amount of dead volume. Dead volume is the volume of fluid contained in tubing, sensors and other components, as this volume is lost and not converted to usable product when the system is flushed between batches. Reducing dead volume is important in pharmaceutical manufacturing, because dead volume is wasted product, which can be very valuable. The integrated pressure sensor can also produce more accurate pressure readings for calibrating the Coriolis flow sensor, since it is measuring pressure closer to the actual flow tubes. 
     Although the detailed description contains many specifics, these should not be construed as limiting the scope of the invention but merely as illustrating different examples. It should be appreciated that the scope of the disclosure includes other embodiments not discussed in detail above. Various other modifications, changes and variations which will be apparent to those skilled in the art may be made in the arrangement, operation and details of the method and apparatus disclosed herein without departing from the spirit and scope as defined in the appended claims. Therefore, the scope of the invention should be determined by the appended claims and their legal equivalents.