MXPA01001626A - High temperature drive system for a coriolis mass flowmeter - Google Patents

Abstract

A drive system (104) for use in a high temperature environment. The drive system (104) is made of materials that can withstand high temperatures without degrading. There are no plastics or epoxy adhesives used in this drive system (104). The drive system is also made more efficient by placing the drive system on a flow tube outside of a loop in the flow tube between the inlet and the outlet.

Description

HIGH TEMPERATURE DRIVE SYSTEM FOR A CORIOLIS MASS FLOWMETER FIELD OF THE INVENTION This invention relates to a drive system designed to operate in a high temperature environment where the temperature can reach 345 degrees Celsius (650 degrees Fahrenheit). More particularly, this invention relates to a drive system for a Coriolis flowmeter that operates in a high temperature environment. The present invention also relates to placing a drive system of a Coriolis flow meter on the upper, external side of the flow tube bends to maximize the efficiency of the drive system.

Problem It is known to use Coriolis effect mass flowmeters to measure the flow velocity of the mass and other information of the materials flowing through a pipeline as described in US Patent No. 4,491,025 issued by J.E. Sith, and collaborators, on January 1, 1985 and Re. 31,450 by J.E. Smith on February 11, 1982. These flow meters REF. DO NOT. 127106 have one or more flow tubes of a curved configuration. Each flow tube configuration in a Coriolis mass flow meter has a group of natural vibration modes, which can be of a coupled, torsional, radial or single fold type. Each flow tube is driven to oscillate in resonance in one of these natural modes. The natural vibration modes of the vibrating material filling systems are defined in part by the combined mass of the flow tubes and the material within the flow tubes. The material flows in the flowmeter of a pipeline are connected on the input side of the flow meter. The material is then directed through the flow tube or flow tubes and outlets of the flow meter to a connected pipe on the outlet side. An actuator applies a force that causes oscillation to the flow tube. When there is no material flowing through the flowmeter, all points along a flow tube oscillate with an identical phase. When a material begins to flow through the flow tube, the Coriolis accelerations 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 actuator, while the phase on the output side leads to the actuator. The detectors are placed at two different points in the flow tube to produce the sinusoidal signals representative of the movement of the flow tube at the two points. A phase difference of the two signals received from the detectors is calculated in units of time. The phase difference between the two detector signals is proportional to the mass flow rate of the material flowing through the flow tube or flow tubes. The mass flow rate of the material is determined by multiplying the phase difference by a flow calibration factor. This flow calibration factor is determined by the properties of the material and the cross-sectional properties of the flow tube. One type of actuator normally used in a Coriolis flowmeter is an electromagnetic actuator. A common electromagnetic actuator has a magnet that has a first surface opposite a coil. The magnet is fixed to a first flow tube and the coil is fixed to a second flow tube. The magnet and the coil are counterbalanced to facilitate oscillation. In a preferred embodiment, the magnet has a magnetic pole attached to the end of the magnet opposite the coil for spreading the magnet. An alternating electric current is applied to the coil which causes the magnetic pole and the coil to alternately attract and repel each other. This causes the flow tubes to oscillate. A magnet armor encloses the magnet to direct the magnetic flux in the windings of the coil. Plastic sleeves are normally used to align the magnet, the magnetic pole, the magnet armature and the coil. The magnetic poles, the magnet and the armature of the magnet are usually fixed to each other with an epoxy adhesive or other type of glue. It is a problem to incorporate a conventional electromagnetic actuator into a Coriolis flowmeter that operates in a high temperature environment where the temperature can reach 345 degrees Celsius (650 degrees Fahrenheit). At these high temperatures, the plastics and adhesives used to align and fix the actuator components will degrade which causes the mechanical failures in the actuator. There is a need for an actuator that does not contain materials that degrade in a high temperature environment. An actuator system is described in European Patent Application 0 364 054 A2. A second problem with Coriolis flowmeter drive systems is the need for efficiency in the actuator. The efficiency of the actuator is especially a problem in the medium-sized flowmeter commonly used to measure flow through a 7.62 cm (3 inch) pipe. In small flow meters, efficiency is not a problem because the amount of energy applied to the actuator by a transmitter is enough to provide enough force to oscillate the flow tubes. In a larger flowmeter, efficiency is not normally a problem for an actuator because an amplifier is normally added to the drive circuitry to increase the amount of energy applied to the coil. This ensures that the actuator can apply sufficient force to oscillate the larger flow tubes. The amplifiers added to the actuators of the large flow meters are expensive and considerably increase the cost of the design and production of a flow meter. The energy applied to the actuator by the transmitter is normally enough to drive the flow tubes in a medium-sized flow meter. However, the actuator has to be extremely effective because there is not a large margin between the amount of energy available and the energy it needs to drive the flow tubes. There is a need for more efficient flow tube actuators especially in these medium size flow meters.

Solution The above and other problems are solved and an improvement in the technique is made by the provision of a high temperature actuator. The high temperature actuator is constructed of material that will not degrade at high temperatures. All components of the high temperature actuator are made of material having equal coefficients of thermal expansion to allow the material to expand and contract at the same speed to prevent damage to the actuator due to the high temperature. The high temperature actuator has a coil assembly attached to a first flow tube and a fixed magnet assembly to a second flow tube. The magnet assembly of the actuator is configured in the following manner to avoid the use of plastics and adhesives to fix or align the components. A first surface at a first end of a magnet is juxtaposed to a first end of a coil. A magnetic pole is a metallic member fixed to the first surface of the magnet between the magnet and the coil with a first surface facing the coil. The magnetic pole is alternately attracted to and repelled from the coil when an alternating current is applied to the coil. The magnetic pole is fixed to the first surface of the magnet by a groove formed in a second surface of the pole receiving a first end of the magnet and the covers on the first surface of the magnet. Magnetic attraction holds the magnetic pole in place on the magnet. A second end of the magnet is pressed into a magnet sleeve. The magnet sleeve is welded with brass or welded to a surface of a magnet frame. The magnet's armor is a platform that is the basis for a magnet assembly. The walls on opposite sides of the magnet armature substantially enclose the magnet to direct the magnetic flux of the magnet in the windings of the coil. The limitation of the magnetic field maintains the alignment between the magnet and the coil. The mounting brackets are fixed to a second surface of the magnet frame and welded to the second flow tube by fixing the assembly from magnet to the flow tubes. A coil assembly is configured in the following manner to eliminate the use of plastics and adhesives in the actuator. The coil is attached to a spool of the coil which is fixed to a first surface of a coil spacer. The coil spacer is of a sufficient mass to act as a counterweight to the magnet assembly. The mounted brackets are fixed to a second surface of the coil spacer to secure the coil assembly to the first flow tube. The high temperature actuator is also made more efficient in a Coriolis flow meter by fixing the actuator in the flow tubes outside the flow tubes on the surface of the pipe curves. The position on the outside of the curves is where the amplitude of the oscillations of the tube is greater which generates a greater amount of electromotive support force (EMF) in the actuator. The position of the actuator also increases the distance between the actuator and the clamp bars in the flow tubes that give the actuator a greater mechanical advantage or influence to oscillate the flow tubes. The next, are aspects of this invention as indicated later in the claims. A first aspect of this invention is a drive system for a Coriolis flow meter capable of operating in a medium at high temperature having a magnet and a coil mounted in opposition to a first end of the magnet. The drive system includes: a magnet frame having a first surface and a second surface. A medium resistant to a high temperature attached to a second end of the magnet to the first surface of the magnet frame. The high temperature resistant means for joining includes a magnet sleeve having a second end of the magnetic pressure fitted in the magnet sleeve and the magnet sleeve welded to the magnet frame. The drive system also includes a means for attaching the armature of the magnet to a flow tube and means for attaching the coil to a flow tube. In another aspect of the invention the drive system further includes walls that extend outwardly from the first surface of the magnet frame and at least partially enclose the magnet to direct the magnetic flux to the magnet to optimize the oscillation of the magnet and the magnet. coil. In another aspect of the invention the drive system operates in a high temperature environment that reaches 345 degrees Celsius (650 degrees Fahrenheit). In another aspect of the invention, the drive system is composed of materials having balanced coefficients of thermal expansion. In another aspect of the invention, the drive system includes a coil spacer having a first surface attached to a second end of the coil and having a mass sufficient to provide a counterweight to the magnet. In another aspect of the invention, the means for attaching the armature of the magnet to the flow tube is a first group of mounting brackets fixed to the second surface of the armature of the magnet. In another aspect of the invention, the means for attaching the coil to the flow tube is a second group of mounting brackets fixed to a second surface of the coil separator. In another aspect of this invention, the first group of mounting brackets is fixed to one side of the surface of a first flow tube and the second group of mounting brackets is fixed to one side of the surface of a second flow tube . In another aspect of the invention, each of the first and second set of mounting brackets includes a base for attaching to the drive system, a fin extending substantially perpendicular from the base, and a curved edge at a first end of the fin. that is fixedly attached to the flow tube. In another aspect of the invention the drive system also includes a machined magnetic pole for covering a first end of the magnet and held in place by magnetic attraction to the magnet.

DESCRIPTION OF THE DRAWINGS The above and other advantages of the high temperature actuators can be understood from the reading of the detailed description below and the following drawings: Figure 1 illustrates a Coriolis flow meter; Figure 2 illustrates a high-temperature drive system of a first side: and Figure 3 illustrates the high-temperature drive system of a second side.

Detailed Description Coriolis Flowmeter in General - Figure 1 Figure 1 illustrates a Coriolis flow meter 5 comprising a flowmeter assembly 10 and an electronic meter 20. The electronic meter 20 is connected to the meter assembly 10 by the conductors 100 to provide the density , mass flow velocity, volume flow rate, total mass flow and other information on the path 26. It should be clear to the person skilled in the art that the present invention can be used for any type of Coriolis flow meter without having counts the number of actuators or the number of detectors selected. The flowmeter assembly 10 includes a pair of flanges 101 and 101 ', a distributor 102 and flow tubes 103A and 103B. The selected detectors 105 and 105 'and the actuator 104 are connected to the flow tubes 103 A and 103 B. The clamp rods 106 and 106' serve to define the axes and W where each flow tube 103A and 103B oscillate. When the flow meter assembly 10 is inserted into a pipe system (not shown) carrying the measured material, the material enters the flow meter assembly 10 through the flange 101, passing through the distributor 102 where the material is directs to enter the flow tubes 103A and 103B, flowing through the flow tubes 103A and 103B and returning to the distributor 102 where it exits the measurement assembly 10 through the flange 101 '. The flow tubes 103A and 103B are appropriately selected and mounted to the distributor 102 to have substantially the same mass distribution, the moments of inertia, and the elastic modules are on the fold axes W-W and W'-W respectively. The flow tubes extend outwardly from the distributor in an essentially parallel fashion.

The flow tubes 103A-B are driven by the high temperature actuator 104 in opposite directions on their respective bending axes W and W and where the first outer part of the bending fold of the flow meter terminates. The high temperature actuator 104 is a drive system comprising a magnet mounted to the flow tube 103A and an opposite coil mounted in the flow tube 103B. A drive signal which is an alternating current is applied by the electronic meter 20, via the conductor 110 to the actuator 104 and causes the drive 104 to oscillate the flow tubes 103A-B. To maximize the efficiency of the high temperature actuator 104, the actuator 104 is mounted on the outside of the curves formed by the flow tubes 103A and 103B. The high temperature actuator 104 is positioned outside the curves because it is where the amplitude of the oscillations of the flow tube is greatest. As the amplitude of the oscillations increases, the support EMF generated between the coil and the magnet increases. The increase in the supporting EMF increases the efficiency of the actuator 104. The increase in the supporting EMF represents the greater amplitude of movement between the coil and the magnet in the actuator 104. The following equation determines the amount of support EMF produced by the actuator 104. Support EMF = (B * V *) * L (1) where: B = magnetic flux density; V = speed of the coil with respect to the magnet; and L = length of coil wire. From the above, the equation V, can be determined by the following equation: V = 2 * A * G) (2) where the equation is multiplied by 2 since the magnet and the coil oscillate; A = amplitude of the displacement between the coil and the magnet; Y ? = angular velocity of the coil with respect to the magnet. It is known that where F = tube frequency. The substitution equations (2) and (3) in equation (1) produce the following equation: Support EMF = B * 4 * A * I "I * F * L (4) It can be assumed that B and L remain constant in Therefore, only A or F can be increased to increase the support EMF.In order to increase the amplitude (amplitude), the magnet and coil must be placed in the position in the flow tubes that moves at the longest distance. The second advantage of the mounting actuator 104 apart from the curves of the flow tube is that the distance increases between the clamp bars 106-106 'and the actuator 104. Increasing the distance creates a greater mechanical advantage or influence on the axes w- 'of the actuator 104 to oscillate the flow tubes 103A-B The greater mechanical advantage also increases the efficiency of the actuator 104. The following is proof that the position of the actuator 104 on the The surface of the flow tubes increases the efficiency of the actuator 104. It is known that F is the force required to move a bracket when a flow tube is expressed in the following equation: F = (-3 * and * E * I) / L3 (5) where: y = the deflection of the flow tube; E = the modulus of elasticity; I = the moment of inertia; and L = the length of the bracket which is the distance or f of the actuator from the clamp bars or the flow meter of the flow meter. As the length increases, the force required to oscillate the flow tubes decreases. This assumes that all and remains constant. When the force required to oscillate the flow meters increases, the energy required to oscillate the flow tubes decreases. The decrease in the required energy is provided by the following equations: work = 2. { (F * A) - (F * -A)} (6) where A = the distance where the tubes oscillate. Energy = work / time (7) The substitution equation (6) in equation (7) produces the following equation: Energy = 2 * ((F * A) - (F * -A).}. / Time (8 ) Rearrangement of equation (8) that produces: Energy * time = 2 * (F * A) 2 (9) From equation (9), it can be seen how the F decreases the energy needed to oscillate the flow tubes by the unit time decays. From equation (6), it can be seen that the force decreases as the length of the mechanical bracket increases. Therefore, the actuator 104 is positioned on the upper side of the curve which reduces the energy needed to drive the flow tubes by increasing the length of the bracket. The electronic meter 20 receives the right and left speed signals that appear on the conductors 111 and 111 ', respectively. The electronic meter 20 produces the drive signal in the conductor 110 which causes the actuator 104 to oscillate the flow tubes 103A and 103B. The electronic meter 20 processes the right and left speed signals to calculate the mass flow velocity and other properties of the material flowing through the flow tube. The path 26 provides an input and output means that allow the electronic meter 20 to interconnect with an operator.

High Temperature Actuator System 104 Figures 2 and 3. The High Temperature Actuator 104 is illustrated in Figures 2 and 3. For the purposes of discussing the relationship between the components of the high temperature actuator 104, Figures 2 and 3 will refer to intermittently in the discussion later. The high temperature actuator 104 does not have any plastic component that will degrade it in a high temperature environment where the temperature is significantly higher than the ambient temperature and can reach 345 degrees Celsius (650 degrees Fahrenheit). Epoxy adhesives and other adhesives that are normally used to fix the components together in the prior art actuators are not used in the high temperature actuator 104 because the adhesives tend to degrade in the environment at high temperature. The inventive aspect of this invention is the use of a device that is resistant to high temperature to join the magnet 230 to a magnet armature. In the preferred exemplary embodiment described in Figures 2 and 3 the device joining the magnet to the armature of the magnet 210 is the magnet sleeve 230. However, it is envisaged that another method including but not limited to a fixation device, a screw and a threaded opening, or an inlet cavity with the magnet pressed in the cavity used to attach the magnet 230 to the armature of the magnet 210. The components of the high temperature actuator 104 are made of materials having substantially equal coefficients of thermal expansion (CTE). Substantially equal CTEs allow materials to expand and contract at equal speeds due to temperature changes without damaging the high temperature actuator 104. The high temperature actuator has the magnet assembly 201 and the coil assembly 202. The magnet 230 and the coil 250 are opposed to each other to provide oscillation of the actuator 104. The base of the magnet assembly 201 is the armature of the magnet 210. The armature of the magnet 210 has a substantially elliptical platform. 211 with a first surface 212 and a second surface 312. The walls 213 and 214 extend out of the substantially circular ends of the first surface 212. Each wall 213 and 214 has a flange extending towards the center of the end 217 of the walls. walls The walls 213 and 214 control the size and direction of the magnetic field of the magnet 230 to keep the magnet 230 and the coil 250 aligned. The brackets of the assembly 281 are fixed to a second end 311 of the armature of the magnet 210. The mounting brackets 281 have a base and fins 283 extending perpendicularly from the base. The fin has a lower edge that is curved to be coupled with a flow tube. The curved edges of the fins 283 are welded with brass or welded to the flow tube to secure the magnetic assembly 201 to the flow tubes. The screws 282 are screwed through the washers 284, the openings 285 of the brackets of the assembly 281, and the openings 313 of the armature of the magnet 210 to fix the brackets of the assembly 281 to the armature of the magnet 210. The magnet 230 is a substantially cylindrical magnet having a first end 231 and a second end 232. The magnet 230 is pressed to fit into the magnet sleeve 220. The magnet sleeve 220 is made of metal material that can be welded with brass or welded to the first surface 212 of the magnet frame to secure the magnet. magnet 230 to magnet assembly 201. In the preferred exemplary embodiment, Magnet Sleeve 220 is a steel carbon ring having an opening 221 that is adjusted to have a radius that is substantially the same size as the radius of magnet 230. The magnetic pole 240 is made of a magnetic material and is fixed to the first end 231 of the magnet 230. The magnetic pole 240 is attracted and repelled by the coil 250 to cause the oscillation of the action. High temperature 104. Magnetic pole 240 has a cavity 341 defined by a wall 343 extending outside the edge of the surface 342. The cavity 341 receives the first end 231 of the magnet 230 to form a cover over the magnet 230. The magnetic attraction between the magnetic pole 240 and the magnet 230 keeps the magnetic pole 240 in place.

The coil 250 acts as an electromagnet. When an alternating current is applied to the coil 250 the polarity of the coil 250 changes. The change in polarity in the coil 250 causes the magnetic pole 240 to be attracted and repelled alternately from the coil 250. When the magnetic pole 240 is repelled from the coil 250, the magnet assembly 201 is pushed out of the coil assembly 202. When the magnetic pole 240 is attracted to the coil 250, the assembly of the magnet 201 is pulled towards the coil assembly 202. The coil 250 is wound around the coil reel 260. The coil reel 260 is an insulated coil which acts as a coil. a support for the coil 250. In the preferred embodiment, the coil spool 260 is a platform 261 having an opening 262. The electrical lines (not shown) supply the electrical current to the coil 250. The screws 294 are inserted through of the openings 271 of the spool separator 270 and the openings 262 of the spool spool 260 for fixing the spool spool 260 to the spool separator 270. The spool separator 270 is the base of the spool assembly 202 The magnet assembly 201 and the coil assembly 202 must be of the same mass to cause oscillation of the actuator 104 as the current applied to the coil 150 alternates. The coil separator 270 is of a mass sufficient to act as a counterweight for the magnet assembly 201. A counterweight must be added to the coil assembly 202 because the magnet 230 and the other components of the magnet assembly 201 have a larger mass that of the coil assembly 202. The spacers 272 extend out of the first end 372 of the coil spacer 270. The spacers 272 are attached to the coil bobbin 270 and add the amplitude to the coil assembly 202. The additional amplitude is needed for placing the coil 250 in a position proximate the magnetic pole 240. The mounting brackets 291 are attached to a second end 272 of the coil spacer 270. The mounting brackets 291 have a base and a fin 293 that extend substantially perpendicularly. from the base. The fins 293 are formed with a curved bottom edge that engage the curvature of the flow tube. The curved lower edge is welded with brass or welded to the flow tube. The coil assembly 202 is supported by the screws 294 extending through the openings 292, 271, and 262. The nuts 295 and the washers 296 are screwed into the end of the screw 294 projecting through the opening 262 for securing the screw 294. It should be noted that one skilled in the art will recognize that it is possible to fix the components of the coil assembly 202 using another method such as soldering with brass or soldering the components. The above is an exemplary embodiment of a high temperature actuator fixed to an upper side of one of the curves in a Coriolis flow meter. It is desired that those skilled in the art can and design alternative high-temperature actuators that infringe on the drive system as described below or literally through the Equivalent Doctrine.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers. Having described the invention as above, property is claimed as contained in the following:

Claims (6)

1. A drive system for a Coriolis flow meter capable of operating in a high temperature environment having a magnet and a coil mounted against a first end of the magnet, the drive system characterized in that it comprises: a magnet made of a first material that has a first coefficient of thermal expansion; a coil mounted against a first end of the magnet wherein the coil is made of a material having a coefficient of thermal expansion substantially equal to the first coefficient of thermal expansion; a magnet armature having a first surface and a second surface where the magnet armature is made of a material having a coefficient of thermal expansion that is substantially equal to the first coefficient of thermal expansion and has a second end of the magnet fixed to the first surface of the magnet's armature wherein a magnet sleeve on the first surface of the magnet's armature has the second end of the pressed magnet fitted to the magnet sleeve, welded to the magnet's armature, and made of material that has a coefficient of thermal expansion that is substantially equal to the first coefficient of thermal expansion; a first group of fixed mounting brackets to the second surface of the magnet frame to join the magnet frame to an upper side of the flow tube means in the Coriolis flow meter where the mounting brackets are made of a material that has a coefficient of thermal expansion that is substantially equal to; and a second group of mounting brackets attached to the coil to fix the coil to an upper side of the flow tube means of the Coriolis flow meter.

2. The drive system according to claim 1, characterized in that it additionally comprises: the walls that extend externally from the first surface to the armature of the magnet and at least partially include the magnet to direct the magnetic flux of the magnet to optimize the oscillation of magnet and coil.

3. The drive system according to claim 2, characterized in that the environment at high temperature reaches 345 degrees Celsius.

4. The drive system according to claim 1, characterized in that it additionally comprises: a coil spacer having a first surface fixedly attached to a second end of the coil and having a mass sufficient to provide a counterweight to the magnet and which is made of material having a coefficient of thermal expansion that is substantially equal to the first coefficient of thermal expansion.

5. The drive system according to claim 1, wherein each of the first and second group of mounting brackets is characterized in that it comprises: a base for attaching to the drive system; a fin extending substantially perpendicular from the base; and a curved edge at a first fin end that is fixedly attached to the flow tube.

6. The drive system according to claim 1, characterized in that it additionally comprises: a magnetic pole machined to cover a first end of the magnet and hold it in place by magnetic attraction to the magnet and which is made of a material having a coefficient of expansion thermal which is substantially equal to the first coefficient of thermal expansion.