MXPA01006653A - Coriolis flowmeter for large mass flows with reduced dimensions - Google Patents

Abstract

A Coriolis flowmeter sensor (5) capable of handling large mass flow rates and having a reduced flag dimension. In order to have a reduced flag dimension, the flow tubes (103A-103B) are formed to have a substantially semicircular arc (150) between an inlet and an outlet. Brace bars (120-121) connected to the flow tube proximate, the inlet and outlet, separate the frequencies of vibration in the flow tubes. Pick-off sensors (105-105') are positioned upon the substantially semicircular arc (150) of the flow tube at a position that allow the sensors to maximize detection of low amplitude, high frequency vibrations of the flow tubes (103A-103B)required to have a reduced flag dimension.

Description

CORIOLIS EFFECT FLUJOMETER FOR LARGE MASK FLOWS WITH REDUCED DIMENSIONS Field of the Invention This invention relates to Coriolis effect flowmeters. More particularly, this invention relates to reducing an indicator dimension of a flow meter by Coriolis effect using flow tubes having a substantially semicircular arc and a set of reinforcing bars. Still more particularly, this invention relates to a configuration of components that maintain zero stability and reduce the amplitude of the vibrating flow tubes to reduce the stress applied to the reinforcing bars.

Background of the Invention It is known that Coriolis mass flow meters measure the mass flow and other information of materials flowing through a pipeline, as described in U.S. Patent Nos. 4,491,025, issued to J.E.

Smith, et al. on January 1, 1985 and Re. (130771) 31,450 to J.E. Smith on February 11, 1982. These flow meters have one or more flow tubes of a curved configuration. Each flow tube configuration in a mass flowmeter by Coriolis effect has a series of natural vibration modes, which can be of a simple bending torsion, or of a coupled type. Each flow tube is driven to oscillate in resonance in one of these natural modes. The natural modes of vibration of the system filled with material are defined in part by the combined mass of the flow tubes and the material within the flow tubes. The material flows inside the flow meter from a connected pipe on the side of the flowmeter inlet. The material is subsequently routed through the flow tube or flow tubes and out of the flow meter into a connected pipe on the outlet side. An exciter circuit applies a force to the flow tube to cause the flow tubes to oscillate in a desired mode of vibration. Typically, the desired mode of vibration is a first output of the phase bending mode. When there is no material flowing through the flowmeter, all points along a flow tube oscillate with an identical phase. When the material begins to flow, accelerations by the Coriolis effect cause each point along the flow tube to have a different phase with respect to other points along the flow tube. The phase on the inlet side of the flow tube delays the driver circuit, while the phase on the output side advances the driver circuit. The sensors are placed on the flow tube to produce sinusoidal signals representative of the movement of the flow tube. The phase difference between the two sensor signals is proportional to the mass flow rate of the material flowing through the flow tube or flow tubes. The electronic components connected to the sensor then use the phase difference and signal frequencies for a given mass flow rate and for other material properties. An advantage that Coriolis effect flowmeters have over other devices that measure mass flow is that flow meters typically have less than 0.1% error in calculated mass flow rates of a material. Other conventional types of devices that measure mass flow, such as by orifice, turbine and vortex flowmeters, typically have 0.5% or larger errors in flow velocity measurements. Although Coriolis mass flow meters have superior accuracy than other types of devices for mass flow rates, Coriolis effect flowmeters are also more expensive to produce. The users of the flowmeters often choose the types of less expensive flowmeters since they prefer to save cost than to have precision. Therefore, the manufacturers of Coriolis flowmeters want a Coriolis effect flowmeter that is less expensive to manufacture and that determines the mass flow with an accuracy that is within 0.5 _ of the actual mass flow rate, in order to produce a product that is competitive with other mechanisms that measure the mass flow rate. One reason why Coriolis meters are more expensive than other devices is the need for components that reduce the number of unwanted vibrations applied to the flow tubes. Such a component is a distributor, which joins the flow tubes to a pipe. In a double tube Coriolis effect flowmeter, the distributor also divides the material flow that is received from a pipe into two separate flows and conducts the flows to separate flow tubes. To reduce the vibrations caused by external sources, such as a pump, which are connected to the pipe, a distributor must have a stiffness that is sufficient enough to absorb the vibrations. The more conventional distributors are made of molded metal to have a suitable mass. In addition, there is a spacer between the distributors that maintains the spacing between the output and input distributors. This spacer is also made of a metal or other solid material in order to prevent external forces coming from the vibration of the flow tubes. The large amount of metal used to create these molded parts increases the cost of the flowmeter. However, the elimination of unwanted vibrations greatly increases the accuracy of the flow meters. A second problem for those skilled in the art of the Coriolis effect flow meter is that the flow meters can have an indicator dimension that is too large to be used in certain applications. For purposes of this discussion, the indicator dimension is the length that a curve of the flow tube extends outside of a pipe. There are environments where space is narrow or difficult to achieve. A flowmeter that has a typical indicator dimension will not fit into these confined areas. This is a particular problem to reduce the indicator dimension of the flow tubes in a Coriolis effect flow meter that handles large flow rates. For purposes of this discussion, large flow rates are 5.29 kg / sec (700 pounds / minute) or higher. The reason for reducing the indicator dimension is a problem in the flow meter that handles large flow rates, since the flow tubes must have large diameters. The large diameter of the flow tubes has larger handling frequencies than with smaller diameter flow tubes, and are more difficult to design when the indicator dimension is reduced. The larger diameter of the flow tube also causes zero stability problems when a smaller indicator dimension is created. For these reasons, it is a particular problem to create a flow meter by Coriolis effect of double flow tube capable of handling large flow rates.

Brief description of the invention The above problems and other problems will be solved, and in the present invention one skilled in the art is made of the provision of a Coriolis effect flowmeter having a reduced indicator dimension. The Coriolis effect flowmeter of the present invention has flow tubes that are capable of handling large mass flow rates. The Coriolis effect flowmeter of the present invention does not have a conventional spacer and distributor. Instead, the spacer substantially surrounds the distributors. This configuration reduces the cost of the flowmeter. The Coriolis effect flowmeter of the present invention also has a reduced indicator dimension, which allows the Coriolis effect flowmeter of the present invention to be used in areas where space is difficult to achieve, and which would be impossible to use a conventional Coriolis effect flow meter that have a conventional indicator dimension. The indicator dimension of the flow tube is reduced by forming the flow tubes in a substantially semicircular arc between the inlet ends and outlet ends of the flow tubes. The semicircular arc reduces the elevation of the flow tube to reduce the indicator height. In order to increase the accuracy of the flowmeter, the total length of the semicircular arc should vibrate. An exciter circuit is attached to the flow tubes at a position along the semicircular arc of each flow tube, which is substantially perpendicular to a plane containing the inlet end and the outlet end of the flow tube. The exciter circuit is placed at this point to maximize the amount of energy applied to the flow tubes by the driver circuit to cause the flow tubes to oscillate. The excitation signals are applied to the driver circuit to cause the excitation to oscillate the flow tubes at a low amplitude to reduce the stress that is applied to the reinforcing bars that are attached to the flow tubes. The exciter circuit must also excite the flow tubes to vibrate at a frequency that is higher than with conventional flow tubes. To separate the vibration modes in the flow tube while the flow tube is oscillating, a first reinforcing bar is attached to the flow tubes near the inlet ends and a second reinforcing bar is attached to the flow tubes together the output ends. The reinforcing bars are metallic components that are attached to each of the flow tubes substantially in the same location along the flow tubes. In order to perceive the Coriolis effect in the oscillating flow tubes, the transducer sensors have to be attached to the flow tubes in a position that allows the sensors to detect the greatest amount of Coriolis force in a low amplitude vibration. This allows a vibration of lower amplitude that is used to reduce the tension applied to the reinforcing bar. An inlet distributor and an outlet manifold can be attached to the inlet and outlet ends of the flow tube to connect the flow tubes to a pipe. Each distributor is a separate component that is molded in a separate way to reduce the cost of the material. Each distributor can have a flow path that doubles substantially 90 degrees to connect the inlet and outlet ends of the semicircular arc to a pipe. A spacer joins each of the distributors to maintain the distance between the distributors. The spacer is a structure that has four sides with opposite ends that join the inlet and outlet distributors. The spacer encloses a hollow cavity. This reduces the amount of material used in the molding of both the distributor and the spacer. The openings in the upper side of the spacer allow the distributor to connect to the semicircular arc of the flow tubes protruding out of the spacer. A box (protective cover) can be attached to the upper side of the spacer to enclose the flow tubes. It is a problem that the box can resonate (enter resonance) at a frequency that is close to the frequency of the vibrating flow tubes. This can cause inaccuracies in the readings of the properties of the material flowing through the flow tube. To change the resonant frequency of the case, a mass can adhere to the box to change the resonant frequency of the case.

BRIEF DESCRIPTION OF THE DRAWINGS The above features and other features can be understood from the following detailed description and the following drawings: FIGURE 1 illustrates a Coriolis effect flowmeter having a reduced indicator dimension. FIGURE 2 illustrates a Coriolis effect flowmeter of this invention attached to a spacer; and FIGURE 3 illustrates a Coriolis effect flowmeter attached to a spacer and enclosed in a box.

Detailed Description Flowmeter by Coriolis effect in General - Figure 1 FIGURE 1 illustrates a Coriolis 5 flowmeter, comprising a flowmeter sensor 10 and an electronic meter 20. The electronic meter 20 is connected to the meter sensor 10 via connection 100 to provide density, mass flow rate, volumetric flow rate , totalized mass flow, temperature, and other information by way of the route 26. This should be apparent to those skilled in the art that the present invention can be used for any type of flowmeter by Coriolis effect 5, without taking into account the numbers of exciter circuits, the number of transducer sensors, the operation of the vibration mode. In addition, the present invention can be used in any system that vibrates the two flow tubes 103A-103B to measure Coriolis effects when a material flows through the flow tube, and that subsequently uses the Coriolis effect to measure a property of the material. The flowmeter sensor 10 includes a pair of flanges 101 and 101 '; distributors 102-102 '; flow tubes 103A and 103B; reinforcing bars 120-121; exciter circuit 104; and transducers 105 and 105 '. The flanges 101-101 'are attached to the distributors 102-102'. The distributors 102-102 'are joined to the opposite ends of the flow tubes 103A-103B. The reinforcing bars 120-121 are attached to the flow tubes 103A-103B as described below. The exciter circuit 104 is attached to the flow tubes 103A-103B at the position where the driver circuit can vibrate the flow tubes 103A-103B in opposition to one another. The transducers 105-105 'are joined to the flow tubes 103A-103B at the opposite ends to detect the phase difference in the vibrations at the opposite ends of the flow tubes 103A-103B. The flanges 101 and 101 'are attached to the distributors 102-102r and connect the flow tubes 103A and 103B to a pipeline. (not shown). When the flowmeter sensor 10 is inserted into a pipe system (not shown) that transports the material to be measured, the material enters the flowmeter sensor 10 through the inlet flange 101, and the total amount of material is divided into two streams by means of the input distributor 102, and is equally directed to enter the flow tubes 103A and 103B. The material subsequently flows through the flow tubes 103A and 103B to return to the outlet manifold 102 ', which joins the separate flows. The material subsequently flows through the outlet flange 101 ', where it exits the measuring sensor 10. The distributors 102 and 102' are made of a minimum amount of material. The flow tubes 103A and 103B are appropriately selected and mounted to the inlet manifold 102 and the outlet manifold 102 ', to have substantially the same mass distribution, the moments of inertia and the moduli of elasticity around the bending axes WW and W'-W 'respectively. The flow tubes extend outwardly from the distributors in an essentially parallel fashion. The flow tubes 103A-B are excited by the driving circuit 104 in phase opposition around their respective bending axes W and W ', and in which the first output of the base bending mode of the flowmeter is qualified. The driver circuit 104 may comprise one of many known arrangements, such as a magnet mounted to the flow tube 103A and an opposite coil mounted to the flow tube 103B. An alternating current is passed through the opposite coil to cause both flow tubes 103A-B to oscillate. An appropriate excitation signal is applied by means of the electronic meter 20, via connection 110 to exciter circuit 104. The description of Figure 1 is provided merely as an example of the operation of a Coriolis effect flow meter, and is not intended to limit the teaching of the present invention. The electronic meter 20 respectively receives the speed signals of the right and left that appear in the connections 111 and 111 '. The electronic meter 20 also produces the excitation signal at the connection 110, which causes the driver circuit 104 to oscillate the flow tubes 103A and 103B. The present invention as described, can produce multiple excitation signals for multiple driver circuits. The electronic meter 20 processes the signals of the right and left speed to compute the mass flow rate. Route 26 provides an outlet and entry means that allows electronic meter 20 to connect with an operator. The internal components of the electronic meter 20 are conventional. Therefore, a complete description of the electronic meter 20 is omitted for brevity. The configuration of the Coriolis effect flowmeter sensor 10 allows the flow tubes 103A-103B to have a smaller indicator dimension, while maintaining the accuracy of the readings within. of 0.5% of the actual mass flow rate. The indicator dimension is the length that a curve in a flow tube projects out of a plane that is perpendicular to the curve, and that contains the connected pipe. A second advantage of the Coriolis 10 flowmeter sensor configuration is that a less expensive distributor and spacer can be used. In order to have a reduced indicator dimension, the flow tubes 103A-103B have a substantially semicircular arc 150-150 'between an inlet end 151-151' and an outlet end 152-152 '. The substantially semicircular arc 150-150 'reduces the indicator dimension since it creates a continuous curve in the flow tubes 103A-103B. The substantially semicircular arc 150 should be used to allow the flow tubes 103A-103B to be of sufficient diameter to facilitate large flow rates of material flowing through the flowmeter through the Coriolis 5 effect. To connect the flow tubes 103A-103B In series in a pipe, the inlet manifold 102 and the outlet manifold 102 'may have a substantially 90 degree angle in a flow path to direct the flow from the pipe to the substantially semicircular arc 150-150'. To acquire the stability of zero and to separate the vibrating modes from the flow tubes 103A-103B, a first reinforcing bar 120 and a second reinforcing bar 121 are attached to the flow tubes 103A and 103B. The first reinforcing bar 120 is attached to the flow tubes 130A-103B adjacent the inlet end 151 to connect the flow tubes 130A and 103B and to control the oscillations of the flow tubes 103A-103B. The second reinforcing bar 121 is attached to the flow tubes 103A-103B adjacent the outlet end 152 to connect the flow tubes 103A and 103B and to control the oscillations of the flow tubes 103A-103B. In a preferred exemplary embodiment, the first reinforcing bar 120 and the second reinforcing bar 121 are joined to the flow tubes 103A-103B substantially 180 degrees apart from each other on the substantially semicircular arc 150. The driver circuit 104 is attached to the flow tube 103A and 103B in a position on the semicircular arc 150 which is substantially midway between the inlet 151 and the outlet 152 of the flow tubes 103A-103B. This position allows the driver circuit 104 to apply the greatest amount of force to the flow tubes 103A-103B using the least amount of power. The driver circuit 104 receives the signals from the electronic meter 20 via the route 110 which causes the driver circuit 104 to oscillate at a desired amplitude and frequency. In a preferred exemplary embodiment, the frequency of a vibration is substantially equal to a first output of the flexure mode of the flow tubes 103A-103B, which is a higher frequency than conventional Coriolis effect flowmeters. To reduce the voltage coming from a higher frequency, in the preferred exemplary mode it is desired to maintain a low vibration amplitude. In order to vibrate the flow tubes 103A-103B at a high frequency and low amplitude. The transducer sensors 105-105 'should be attached to the flow tubes 103A-103B at the position where the largest amount of vibration can be sensed in the flow tubes 103A-103B. This allows the transducer sensors 105-105 'to detect the greatest amount of effect of Coriolis forces caused by the material flowing. In a preferred embodiment, the transducer sensors are placed in a position that is substantially 30 degrees from the axes W-W '. However, the transducer sensors can be placed in any position that is between 25 and 50 degrees from the W-W 'axes when conventional electronic components are used to excite the flowmeter.

A Spacer attached to a Distributor 102 and 102 '-FIGURE 2 FIGURE 2 illustrates a spacer 200 attached to the flow meter sensor 10, the space 200 maintains a constant distance between the inlet manifold 102 and the outlet manifold 102 '. Unlike conventional spacers in Coriolis effect flowmeters, spacer 200 is made from a minimum of material. Spacer 200 has right-angled ends 190-191 on opposite sides. In a preferred exemplary embodiment. The right-angled ends 190-191 are molded as square plates in the distributors 102-102 '. The four walls represented by the walls 201-202 connect each edge of the square bases 190-191 to form a cover. The openings 210 substantially allow the semicircular arcs 150-150 'of the flow tube 103A-103B to protrude from the spacer 200.

One Box (protective cover) for Flow Pipes 103A-103B - FIGURE 3 FIGURE 3 illustrates a box 300 for enclosing the flow tube 103A-103B (Shown in FIGURE 1). The box 300 is a structure having a hollow interior that fits above the flow tubes 103A-103B and joins the spacer 200 in such a way that it can be by welding, or with nuts and bolts. The box 300 prevents the atmosphere from entering the cover. The box 300 may resonate at a frequency that is substantially equal to the frequency of the desired mode of vibration of the flow tubes 103A-103B. If this is the case, it is desired to change the resonant frequency of the box 300 to prevent reading errors of the vibrations of the flow tubes 103A-103B. One solution is to adhere dough 301 to a substantially planar portion 302 of box 300. One skilled in the art will recognize that the dough can be added as part of box 300. The foregoing is a description of a Coriolis effect flow meter, which has a minimum indicator dimension. It is expected that those skilled in the art can and design other flow meters by Coriolis effect usurping this invention, as set forth in the following claims either literally or through the Doctrine of Equivalents.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Claims (11)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. A Coriolis effect flow meter having a reduced indicator dimension, characterized in that it comprises: a first flow tube; a second flow tube; a substantially semicircular arc, between an inlet end and an outlet end of each of the first flow tube and the second flow tube; an exciter circuit connected to the first flow tube and to the second flow tube, at a point on the substantially semicircular arc, which is substantially perpendicular to the bending axes of the first and second flow tubes, wherein the driver circuit oscillates the first flow tube and the second flow tube in opposition to each other; a first reinforcing bar attached to the first flow tube and to the second flow tube adjacent to the outlet end. A second reinforcing bar attached to the first flow tube and to the second flow tube adjacent to the outlet end; And transducer sensors attached to the first flow tube and to the second flow tube, in a position that allows the transducer sensors to detect the greatest amount of Coriolis force at a low amplitude vibration.
2. 2. The Coriolis effect flowmeter of claim 1, characterized in that it additionally comprises: an inlet manifold attached to the inlet ends of the first flow tube and the second flow tube to join the first flow tube and the second flow tube. flow to a pipe.
3. 3. The Coriolis effect flowmeter of claim 2, characterized in that it additionally comprises: a substantially 90 degree curve in a flow path through the inlet manifold.
4. The Coriolis effect flowmeter of claim 1, characterized in that it additionally comprises: an outlet manifold attached to the outlet ends of the first flow tube and the second flow tube for connecting the first flow tube and the second flow tube. flow to pipe.
5. 5. The Coriolis effect flowmeter of claim 4, characterized in that it additionally comprises: a curve substantially of 90 degrees in a flow path through the outlet distributor.
6. The Coriolis effect flowmeter of claim 1, characterized in that it additionally comprises: an inlet manifold attached to the inlet ends of the first flow tube and the second flow tube to join the first flow tube and the second flow tube. flow to a pipe; an outlet manifold attached to the outlet ends of the first flow tube and the second flow tube for connecting the first flow tube and the second flow tube to a pipe; and a spacer attached to the inlet manifold and the outlet manifold to maintain a fixed distance between the inlet manifold and the outlet manifold.
7. 7. The flowmeter by Coriolis effect of the claim 6, characterized in that the spacer comprises: an inlet end connected to the inlet distributor; an outlet end attached to the outlet distributor; an upper side, a lower side, a front side, and a rear side between the entry and exit ends; and openings through the upper side of the spacer, through which the first flow tube and the second flow tube are joined to the inlet and outlet manifold.
8. 8. The flowmeter by Coriolis effect of the claim 7, characterized in that it additionally comprises: a box enclosing the first flow tube and the second flow tube attached to the upper side of the spacer.
9. 9. The Coriolis effect flowmeter of claim 8, characterized in that the box comprises: a front side wall; , i a rear side wall; and [i a mass adhered to the front side wall and the rear side wall to change the vibration modes of the box.
10. The Coriolis effect flowmeter of claim 1, characterized in that the position of the transducer sensors is substantially 25-50 degrees from the bending axes of the first and second flow tubes.
11. 11. The Coriolis effect flowmeter of claim 10, characterized in that the position of the transducer sensors is 30 degrees from the bending axes of the first and second flow tubes. ' WITH REDUCED DIMENSIONS SUMMARY OF THE INVENTION The present invention relates to a Coriolis effect flowmeter sensor (5) capable of handling large mass flow rates having a reduced indicator dimension. In order to have a reduced indicator dimension, the flow tubes (103A-103B) are formed to have a substantially semicircular arc (150) between an inlet and an outlet. The reinforcing bars (120-121) are connected to the flow tube near the inlet and outlet, separating the vibration frequencies in the flow tubes. The transducer sensors (105-105 ') are placed in the substantially semicircular arc (150) of the flow tube in a position that allows the sensors to maximize the detection of high frequency vibrations and low amplitude of the flow tubes (103A- 103B) that are required to have a reduced indicator dimension.