Patent Description:
Vibrating sensors, such as for example, vibrating densitometers and Coriolis flowmeters are generally known, and are used to measure mass flow and other information for materials flowing through a conduit in the flowmeter. Exemplary Coriolis flowmeters are disclosed in <CIT>, <CIT>, and <CIT> These flowmeters have one or more conduits of a straight or curved configuration. Each conduit configuration in a Coriolis mass flowmeter, for example, has a set of natural vibration modes, which may be of simple bending, torsional, or coupled type. Each conduit can be driven to oscillate at a preferred mode.

Material flows into the flowmeter from a connected pipeline on the inlet side of the flowmeter, is directed through the conduit(s), and exits the flowmeter through the outlet side of the flowmeter. The natural vibration modes of the vibrating system are defined in part by the combined mass of the conduits and the material flowing within the conduits.

When there is no-flow through the flowmeter, a driving force applied to the conduit(s) causes all points along the conduit(s) to oscillate with identical phase or a small "zero offset", which is a time delay measured at zero flow. As material begins to flow through the flowmeter, Coriolis forces cause each point along the conduit(s) to have a different phase. For example, the phase at the inlet end of the flowmeter lags the phase at the centralized driver position, while the phase at the outlet leads the phase at the centralized driver position. Pickoffs on the conduit(s) produce sinusoidal signals representative of the motion of the conduit(s). Signals output from the pickoffs are processed to determine the time delay between the pickoffs. The time delay between the two or more pickoffs is proportional to the mass flow rate of material flowing through the conduit(s).

Meter electronics connected to the driver generate a drive signal to operate the driver and determine a mass flow rate and other properties of a material from signals received from the pickoffs. The driver may comprise one of many well-known arrangements; however, a magnet and an opposing drive coil have received great success in the flowmeter industry. An alternating current is passed to the drive coil for vibrating the conduit(s) at a desired flow tube amplitude and frequency. It is also known in the art to provide the pickoffs as a magnet and coil arrangement very similar to the driver arrangement. However, while the driver receives a current which induces a motion, the pickoffs can use the motion provided by the driver to induce a voltage. The magnitude of the time delay measured by the pickoffs is very small; often measured in nanoseconds. Therefore, it is necessary to have the transducer output be very accurate.

However, unclean conditions in the vibratory meter can affect the accuracy of the transducer. For example, a coating in the vibratory meter may cause the time delay between the pickoffs to change. As a result, the properties measured by the flowmeter may be inaccurate. In addition, if the coating is not detected and a cleaning process is not performed, then the inaccurate measurements by the flowmeter may likewise be undetected. Furthermore, when a cleaning process is performed, the flowmeter may be offline, thereby causing downtime in a system in which it is employed. This downtime may be unnecessarily long due to a requirement for manual intervention; such as a user being required to stop the cleaning process. Therefore, there is a need for cleaning and detecting a clean condition in the vibratory meter.

<CIT> discloses a deposit detection device and a cleaning device that detect the amount of deposit on the inner wall surface of the pipe of the measurement unit of a vibratory mass flow meter, when the measurement unit is cleaned at the end of measurement. The density of fresh water is calculated from the vibration of a bent pipe when fresh water is supplied, and compared with the density of fresh water stored in advance, detecting the deposits on the inner wall surface of the pipe and the degree of cleaning of the inner wall surface of the pipe.

<CIT> discloses a meter electronics and a method for detecting a residual material in a flow meter assembly of a vibratory meter.

A meter electronics configured to automate cleaning of a conduit in a vibratory meter is provided. According to an embodiment, the meter electronics comprises an interface configured to provide a drive signal to a meter assembly communicatively coupled to the meter electronics and receive one or more pick-off signals from the meter assembly, and a processing system communicatively coupled to the interface. According to the embodiment, the processing system is configured to determine a parameter from the drive signal and/or the one or more received pick-off signals, and, based on the parameter, detect an unclean condition of the meter assembly and enter into a cleaning mode, and detect a clean condition of the meter assembly and enter into a non-cleaning mode.

A method of automating a cleaning of a conduit in a vibratory meter is provided. According to an embodiment, the method comprises providing a drive signal to a meter assembly, receiving one or more sensor signals from the meter assembly, and determining a parameter of the drive signal and/or the one or more received pick-off signals using a processing system. According to the embodiment, the method also includes, based on the parameter, detecting an unclean condition of the meter assembly and placing the processing system into a cleaning mode, and detecting a clean condition of the meter assembly and placing the processing system into a non-cleaning mode.

According to an aspect, a meter electronics (<NUM>) is configured to automate a cleaning of a conduit in a vibratory meter (<NUM>) comprises an interface (<NUM>) configured to provide a drive signal to a meter assembly (<NUM>) communicatively coupled to the meter electronics (<NUM>) and receive one or more pick-off signals from the meter assembly (<NUM>), and a processing system (<NUM>) communicatively coupled to the interface (<NUM>). The processing system (<NUM>) is configured to determine a parameter from the drive signal and/or the throne or more received pick-off signals. The processing system (<NUM>) is further configured to, based on the parameter, detect an unclean condition of the meter assembly (<NUM>) and enter into a cleaning mode, and detect a clean condition of the meter assembly (<NUM>) and enter into a non-cleaning mode.

Preferably, the processing system (<NUM>) is further configured to detect the unclean condition if a value of the parameter substantially deviates from a baseline value of the parameter, and detect the clean condition if the value of the parameter substantially equals the baseline value of the parameter. The baseline value is associated with a previously determined clean condition of the vibratory meter (<NUM>).

Preferably, the cleaning mode of the processing system (<NUM>) comprises the processing system (<NUM>) being configured to execute a cleaning routine. The cleaning routine comprises iteratively and repeatedly determining a value of the parameter of the provided drive signal and/or the received one or more pick-off signals, comparing the value of the parameter to a baseline value of the parameter, and detecting the unclean condition based on the comparison.

Preferably, the processing system (<NUM>) is further configured to detect the clean condition of the meter assembly (<NUM>) while the meter electronics (<NUM>) is in the cleaning mode, and, if the clean condition is detected, enter into a non-cleaning mode.

Preferably, the processing system (<NUM>) being configured to enter into the cleaning mode comprises the processing system (<NUM>) being configured to send a cleaning mode signal over path (<NUM>) indicating the cleaning mode of the processing system (<NUM>).

Preferably, the drive signal comprises a resonant component and at least one non-resonant component, the one or more pick-off signals comprises at least one component, the at least one component corresponding to the at least one non-resonant component of the drive signal, the parameter is determined from the at least one non-resonant component of the drive signal and the at least one component corresponding to the at least one non-resonant component of the drive signal, and the parameter is one of a stiffness, a mass, and a damping of a conduit (<NUM>, <NUM>') of the meter assembly (<NUM>).

Preferably, the one or more received pick-off signals is comprised of at least one of a right pick-off signal and a left pick-off signal, and the parameter is associated with one of the right pick-off signal and the left pick-off signal.

Preferably, the parameter determined from the drive signal and/or the one or more pick-off signals comprises one of a drive gain of the one or more pick-off signals and a resonant frequency of the meter assembly.

According to an aspect, a method of automating a cleaning of a conduit in a vibratory meter comprises providing a drive signal to a meter assembly, receiving one or more pick-off signals from the meter assembly, and determining a parameter of the drive signal and/ or the one or more received pick-off signals using a processing system. The method also comprises, based on the parameter, detecting an unclean condition of the meter assembly and placing the processing system into a cleaning mode, and detecting a clean condition of the meter assembly and placing the processing system into a non-cleaning mode.

Preferably, the unclean condition is detected if a value of the parameter substantially deviates from a baseline value of the parameter, and the clean condition is detected if the value of the parameter substantially equals the baseline value of the parameter. The baseline value is associated with a previously determined clean condition of the vibratory meter.

Preferably, the cleaning mode comprises a cleaning routine comprising iteratively and repeatedly determining a value of the parameter of the drive signal and/ or the received one or more pick-off signals, comparing the value of the parameter to a baseline value of the parameter, and detecting the unclean condition based on the comparison.

Preferably, the method further comprises detecting the clean condition of the meter assembly while in the cleaning mode, and, if the clean condition is detected, entering into a non-cleaning mode.

Preferably, placing the processing system into the cleaning mode comprises the processing system sending a signal over path indicating the cleaning mode of the processing system.

Preferably, the drive signal comprises a resonant component and at least one non-resonant component, the one or more pick-off signals comprises at least one component, the at least one component corresponding to the at least one non-resonant component of the drive signal, the parameter is determined from the at least one non-resonant component of the drive signal and the at least one component corresponding to the at least one non-resonant component of the drive signal, and the parameter is one of a stiffness, a mass, and a damping of a conduit of the meter assembly.

Preferably, the parameter determined from the drive signal and/or the one or more pick-off signals comprises a drive gain of the one or more pick-off signals and a resonant frequency of the meter assembly.

<FIG> and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of embodiments of cleaning and detecting a clean condition in a vibratory meter. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the present description. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of cleaning and detecting the clean condition of the vibratory meter. As a result, the embodiments described below are not limited to the specific examples described below, but only by the claims.

<FIG> shows a vibratory meter <NUM>. As shown in <FIG>, the vibratory meter <NUM> comprises a meter assembly <NUM> and meter electronics <NUM>. The meter assembly <NUM> responds to mass flow rate and density of a process material. The meter electronics <NUM> is connected to the meter assembly <NUM> via sensor signals <NUM> to provide density, mass flow rate, temperature information over path <NUM>, and/or other information.

The meter assembly <NUM> includes a pair of manifolds <NUM> and <NUM>', flanges <NUM> and <NUM>' having flange necks <NUM> and <NUM>', a pair of parallel conduits <NUM> and <NUM>', driver <NUM>, resistive temperature detector (RTD) <NUM>, and a pair of pick-off sensors <NUM> and 170r. Conduits <NUM> and <NUM>' have two essentially straight inlet legs <NUM>, <NUM>' and outlet legs <NUM>, <NUM>', which converge towards each other at conduit mounting blocks <NUM> and <NUM>'. The conduits <NUM>, <NUM>' bend at two symmetrical locations along their length and are essentially parallel throughout their length. Brace bars <NUM> and <NUM>' serve to define the axis W and W' about which each conduit <NUM>, <NUM>' oscillates. The legs <NUM>, <NUM>' and <NUM>, <NUM>' of the conduits <NUM>, <NUM>' are fixedly attached to conduit mounting blocks <NUM> and <NUM>' and these blocks, in turn, are fixedly attached to manifolds <NUM> and <NUM>'. This provides a continuous closed material path through meter assembly <NUM>.

When flanges <NUM> and <NUM>', having holes <NUM> and <NUM>' are connected, via inlet end <NUM> and outlet end <NUM>' into a process line (not shown) which carries the process material that is being measured, material enters inlet end <NUM> of the meter through an orifice <NUM> in the flange <NUM> and is conducted through the manifold <NUM> to the conduit mounting block <NUM> having a surface <NUM>. Within the manifold <NUM> the material is divided and routed through the conduits <NUM>, <NUM>'. Upon exiting the conduits <NUM>, <NUM>', the process material is recombined in a single stream within the block <NUM>' having a surface <NUM>' and the manifold <NUM>' and is thereafter routed to outlet end <NUM>' connected by the flange <NUM>' having holes <NUM>' to the process line (not shown).

The conduits <NUM>, <NUM>' are selected and appropriately mounted to the conduit mounting blocks <NUM>, <NUM>' so as to have substantially the same mass distribution, moments of inertia and Young's modulus about bending axes W--W and W'--W', respectively. These bending axes go through the brace bars <NUM>, <NUM>'. Inasmuch as the Young's modulus of the conduits change with temperature, and this change affects the calculation of flow and density, RTD <NUM> is mounted to conduit <NUM>' to continuously measure the temperature of the conduit <NUM>'. The temperature of the conduit <NUM>' and hence the voltage appearing across the RTD <NUM> for a given current passing therethrough is governed by the temperature of the material passing through the conduit <NUM>'. The temperature dependent voltage appearing across the RTD <NUM> is used in a well-known method by the meter electronics <NUM> to compensate for the change in elastic modulus of the conduits <NUM>, <NUM>' due to any changes in conduit temperature. The RTD <NUM> is connected to the meter electronics <NUM> by lead <NUM>.

Both of the conduits <NUM>, <NUM>' are driven by driver <NUM> in opposite directions about their respective bending axes W and W' and at what is termed the first out-of-phase bending mode of the flow meter. This driver <NUM> may comprise any one of many well-known arrangements, such as a magnet mounted to the conduit <NUM>' and an opposing coil mounted to the conduit <NUM> and through which an alternating current is passed for vibrating both conduits <NUM>, <NUM>'. A suitable drive signal is applied by the meter electronics <NUM>, via lead <NUM>, to the driver <NUM>.

The meter electronics <NUM> receives the RTD temperature signal on lead <NUM>, and the left and right sensor signals appearing on sensor signals <NUM> carrying the left and right sensor signals <NUM>, 165r, respectively. The meter electronics <NUM> produces the drive signal appearing on lead <NUM> to driver <NUM> and vibrate conduits <NUM>, <NUM>'. The meter electronics <NUM> processes the left and right sensor signals and the RTD signal to compute the mass flow rate and the density of the material passing through meter assembly <NUM>. This information, along with other information, is applied by meter electronics <NUM> over path <NUM> as a signal.

A mass flow rate measurement ṁ can be generated according to the equation: <MAT> The Δt term comprises an operationally-derived (i.e., measured) time delay value comprising the time delay existing between the pick-off sensor signals, such as where the time delay is due to Coriolis effects related to mass flow rate through the vibratory meter <NUM>. The measured Δt term ultimately determines the mass flow rate of the flow material as it flows through the vibratory meter <NUM>. The Δt<NUM> term comprises a time delay at zero flow calibration constant. The Δt<NUM> term is typically determined at the factory and programmed into the vibratory meter <NUM>. The time delay at zero flow Δt<NUM> term will not change, even where flow conditions are changing. The flow calibration factor FCF is proportional to the stiffness of the flow meter.

It is a problem that the conduits may change with time, wherein an initial factory calibration may change over time as the conduits <NUM>, <NUM>' are corroded, eroded, or otherwise changed. As a consequence, the conduits' <NUM>, <NUM>' stiffness may change from an initial representative stiffness value (or original measured stiffness value) over the life of the vibratory meter <NUM>. Meter verification can detect such changes in the conduits' <NUM>, <NUM>' stiffness, as is explained below.

<FIG> shows the meter electronics <NUM> for cleaning and detecting a clean condition in a vibratory meter. The meter electronics <NUM> can include an interface <NUM> and a processing system <NUM>. The meter electronics <NUM> receives a vibrational response, such as from the meter assembly <NUM>, for example. The meter electronics <NUM> processes the vibrational response in order to obtain flow characteristics of the flow material flowing through the meter assembly <NUM>.

As previously discussed, the flow calibration factor FCF reflects the material properties and cross-sectional properties of the flow tube. A mass flow rate of flow material flowing through the flow meter is determined by multiplying a measured time delay (or phase difference/frequency) by the flow calibration factor FCF. The flow calibration factor FCF can be related to a stiffness characteristic of the meter assembly. If the stiffness characteristic of the meter assembly changes, then the flow calibration factor FCF will also change. Changes in the stiffness of the flow meter therefore will affect the accuracy of the flow measurements generated by the flow meter.

The interface <NUM> receives the vibrational response from one of the pick-off sensors <NUM>, 170r via the sensor signals <NUM> of <FIG>. The interface <NUM> can perform any necessary or desired signal conditioning, such as any manner of formatting, amplification, buffering, etc. Alternatively, some or all of the signal conditioning can be performed in the processing system <NUM>. In addition, the interface <NUM> can enable communications between the meter electronics <NUM> and external devices. The interface <NUM> can be capable of any manner of electronic, optical, or wireless communication. The interface <NUM> can provide information based on the vibrational response.

The interface <NUM> in one embodiment is coupled with a digitizer (not shown), wherein the sensor signal comprises an analog sensor signal. The digitizer samples and digitizes an analog vibrational response and produces the digital vibrational response.

The processing system <NUM> conducts operations of the meter electronics <NUM> and processes flow measurements from the meter assembly <NUM>. The processing system <NUM> executes one or more processing routines and thereby processes the flow measurements in order to produce one or more flow characteristics. The processing system <NUM> is communicatively coupled to and is configured to receive the information from the interface <NUM>.

The processing system <NUM> can comprise a general purpose computer, a micro-processing system, a logic circuit, or some other general purpose or customized processing device. Additionally or alternatively, the processing system <NUM> can be distributed among multiple processing devices. The processing system <NUM> can also include any manner of integral or independent electronic storage medium, such as the storage system <NUM>.

The storage system <NUM> can store parameters, such as meter verification parameters, and data, software routines, constant values, and variable values. The stored values may be measured values, baseline value, or the like. The baseline values may be a value determined prior to the measured value, such as during a factory calibration routine, or the like. However, any suitable baseline value may be employed. In one embodiment, the storage system <NUM> includes routines that are executed by the processing system <NUM>, such as the operational routine <NUM> and verification <NUM> of the vibratory meter <NUM>. The verification <NUM> of the vibratory meter <NUM> may include comparing the measured value with the baseline value. The verification <NUM> may detect a clean and/or an unclean condition of a conduit in the vibratory meter <NUM>. The storage system can also store statistical values, such as a standard deviation, confidence intervals, or the like.

As discussed above, the verification <NUM> may include comparing the measured value of a parameter and the baseline value of the parameter. For example, if the measured value substantially deviates from the baseline value then a fault condition, such as an unclean condition in the vibratory meter, may be detected. If the measured value substantially equals the baseline value of the parameter, then a non-fault condition, such as a clean condition, may be detected. If the baseline value is associated with a previously determined clean condition, then the detected fault condition may be an unclean condition and the detected non-fault condition may be a clean condition. The parameter may be anything that can be used during the verification <NUM>.

For example, additional or alternative to the parameters shown in <FIG>, the parameter may be a drive gain employed during the verification <NUM>. The drive gain measures the amount of voltage needed to vibrate one or more conduits to a desired amplitude so as to accurately measure a Coriolis force. A "clean" vibratory meter may have a stable and relatively low drive gain value when operating (e.g., under <NUM>%). A coating of the tubes may create an imbalance that requires more voltage, or drive gain, to maintain the desired amplitude. Once a meter has been properly cleaned the drive gain may return to the stabilized and pre-coated value. The verification <NUM> may or may not employ a baseline drive gain and a measured drive gain alone or with other parameters, such as, for example, those shown in <FIG>, which are discussed in more detail in the following.

The storage system <NUM> can store a baseline meter stiffness <NUM>. The baseline meter stiffness <NUM> may be determined during manufacturing or calibration of the vibratory meter <NUM>, or during a prior recalibration. For example, the baseline meter stiffness <NUM> can be determined by the verification <NUM> before the vibratory meter <NUM> is installed in the field. The baseline meter stiffness <NUM> is representative of the stiffness of the conduits <NUM>, <NUM>' before any changes have occurred, such as erosion/corrosion, damage (e.g., freezing, over-pressurization, etc.), coatings, etc. The baseline meter stiffness <NUM> may be a mean of a plurality of baseline meter stiffness measurements. As such, the baseline meter stiffness <NUM> may have an associated dispersion characteristic, as will be discussed in more detail below, where the baseline meter stiffness measurements may vary. The more the baseline meter stiffness measurements vary, the greater the dispersion.

The storage system <NUM> can store a meter stiffness <NUM>. The meter stiffness <NUM> comprises a stiffness value that is determined from vibrational responses generated during operation of the vibratory meter <NUM>. The meter stiffness <NUM> may be generated in order to verify proper operation of the vibratory meter <NUM>. The meter stiffness <NUM> may be generated for a verification process, wherein the meter stiffness <NUM> serves the purpose of verifying proper and accurate operation of the vibratory meter <NUM>. Similar to the baseline meter stiffness <NUM>, the meter stiffness <NUM> may be a mean of a plurality of meter stiffness measurements. As such, the meter stiffness <NUM> may have an associated dispersion characteristic, where the meter stiffness measurements may vary. The more the meter stiffness measurements vary, the greater the dispersion characteristic.

The storage system <NUM> can store a stiffness change <NUM>. The stiffness change <NUM> can be a value that is determined by comparing the baseline meter stiffness <NUM> and the meter stiffness <NUM>. For example, the stiffness change <NUM> can be a difference between the baseline meter stiffness <NUM> and the meter stiffness <NUM>. In this example, a negative number may indicate that the stiffness of the conduits <NUM>, <NUM>' increased since being installed in the field. A positive number may indicate that the physical stiffness of the conduits <NUM>, <NUM>' decreased since the baseline meter stiffness <NUM> was determined.

As can be appreciated, the comparison may be performed in various ways. For example, the stiffness change <NUM> may be a difference between the meter stiffness <NUM> and the baseline meter stiffness <NUM>. Accordingly, an increase in stiffness will result in a positive number and a decrease in stiffness will result in a negative number. Additionally or alternatively, values derived from or related to the baseline meter stiffness <NUM> and/or the meter stiffness <NUM> can be employed, such as ratios that employ other values, such as conduit geometry, dimensions, or the like.

If the meter stiffness <NUM> is substantially the same as the baseline meter stiffness <NUM>, then it can be determined that the vibratory meter <NUM>, or more specifically, the conduits <NUM>, <NUM>', may be relatively unchanged from when it was manufactured, calibrated, or when the vibratory meter <NUM> was last re-calibrated. Alternatively, where the meter stiffness <NUM> significantly differs from the baseline meter stiffness <NUM>, then it can be determined that the conduits <NUM>, <NUM>' have degraded and may not be operating accurately and reliably, such as where the conduits <NUM>, <NUM>' have changed due to erosion, corrosion, damage (e.g., freezing, over-pressurization, etc.), coating, or other condition.

As discussed above, the baseline meter stiffness <NUM> and the meter stiffness <NUM> are determined for both the left and right pick-off sensors <NUM>, 170r. That is, the baseline meter stiffness <NUM> and the meter stiffness <NUM> are proportional to the stiffness of the conduits <NUM>, <NUM>' between the left and right pick-off sensors <NUM>, 170r. As a result, different conditions of the conduits <NUM>, <NUM>' can cause similar stiffness changes <NUM>. For example, erosion, corrosion, and/or damage to the conduits <NUM>, <NUM>' can result in similar decreases in physical stiffness, which may be indicated by a negative or "low" stiffness change <NUM>. Accordingly, when only relying on the stiffness change <NUM>, the specific condition of the conduits <NUM>, <NUM>' may not be ascertainable.

However, the left pick-off sensor <NUM> and the right pick-off sensor 170r can each have their own associated stiffness value. More specifically, as discussed above, the driver <NUM> applies a force to the conduits <NUM>, <NUM>' and the pick-off sensors <NUM>, 170r measure a resulting deflection. The amount of deflection of the conduits <NUM>, <NUM>' at the location of the pick-off sensors <NUM>, 170r is proportional to the stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the pick-off sensors <NUM>, 170r.

Accordingly, the stiffness associated with the left pick-off sensor <NUM> is proportional to the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the left pick-off sensor <NUM> and the stiffness associated with the right pick-off sensor 170r is proportional to the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the right pick-off sensor 170r. Therefore, if there is erosion, corrosion, damage, coating, or the like, between the driver <NUM> and, for example, the right pick-off sensor 170r, then the stiffness associated with the right pick-off sensor 170r may decrease whereas the stiffness associated with the left pick-off sensor <NUM> may not change. To track the changes, the storage system <NUM> may also include stiffness values associated with the left and right pick-off sensors <NUM>, 170r.

For example, as shown in <FIG>, the storage system <NUM> includes a baseline LPO stiffness <NUM>, which is proportional to the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the location of the left pick-off sensor <NUM> on the conduits <NUM>, <NUM>'. Similarly, the storage system <NUM> also includes a baseline RPO stiffness <NUM>, which is proportional to the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the location of the right pick-off sensor 170r on the conduits <NUM>, <NUM>'. The baseline LPO and RPO stiffness <NUM>, <NUM> may be determined by the verification <NUM> before the vibratory meter <NUM> is installed in the field, such as, for example, during manufacture or calibration of the vibratory meter <NUM>, or during a prior recalibration.

The storage system <NUM> also includes an LPO stiffness <NUM> and an RPO stiffness <NUM>. The LPO stiffness <NUM> is proportional to the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the location of the left pick-off sensor <NUM>, but after the baseline LPO stiffness <NUM> is determined. Similarly, the RPO stiffness <NUM> is proportional to the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the location of the right pick-off sensor 170r, but after the baseline RPO stiffness <NUM> is determined.

Also as shown in <FIG>, the storage system <NUM> further includes an LPO stiffness change <NUM> and an RPO stiffness change <NUM>. The LPO and RPO stiffness change <NUM>, <NUM> are proportional to a difference between the baseline LPO, RPO stiffness <NUM>, <NUM> and the LPO, RPO stiffness <NUM>, <NUM>. For example, a negative LPO stiffness change <NUM> may indicate that the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the left pick-off sensor <NUM> has increased. A positive LPO stiffness change <NUM> may indicate that the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the left pick-off sensor <NUM> decreased since the baseline LPO stiffness <NUM> was determined. Alternatively, the LPO and RPO stiffness change <NUM>, <NUM> may be a difference between the LPO and RPO stiffness <NUM>, <NUM> and the baseline LPO and RPO stiffness <NUM>, <NUM>. Accordingly, for example, a positive LPO stiffness change <NUM> can indicate that the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the left pick-off sensor <NUM> increased since the baseline LPO stiffness <NUM> was determined. Although the LPO and RPO stiffness change <NUM>, <NUM> are described as being determined from a difference, any values derived from or related to the baseline LPO and RPO stiffness <NUM>, <NUM> and the LPO and RPO stiffness <NUM>, <NUM> can be employed, such as a ratio of a stiffness value and other values, such as a conduit geometry, dimensions, or the like. The LPO and RPO stiffness change <NUM>, <NUM> can be expressed in any suitable units, such as whole numbers, ratios, percentages etc..

An increase or decrease in the physical stiffness associated with the left and right pick-off sensors <NUM>, 170r can indicate an unclean condition of the conduit <NUM>, <NUM>' that is causing the physical stiffness change. For example, a coating of an inner wall of the conduits <NUM>, <NUM>' may increase the physical stiffness of the conduits <NUM>, <NUM>'. In particular, coating, for example, of the inner wall of the conduits <NUM>, <NUM>' between the left pick-off sensor <NUM> and the driver <NUM> may cause the physical stiffness of the conduits <NUM>, <NUM>' between the left pick-off sensor <NUM> and the driver <NUM> to increase.

Additionally, the relative increase or decrease of the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the left pick-off sensor <NUM> and the physical stiffness of the conduits <NUM>, <NUM>' between the driver <NUM> and the right pick-off sensor 170r can further indicate the underlying condition of the conduits <NUM>, <NUM>' causing the physical stiffness change. This relative increase or decrease in the physical stiffness may be indicated by a stiffness symmetry <NUM> in the storage system <NUM>.

The stiffness symmetry <NUM> can be any suitable value or values that indicate the relative values of, for example, the LPO stiffness change <NUM> and the RPO stiffness change <NUM>. For example, the LPO stiffness change <NUM> and the RPO stiffness change <NUM> may indicate that the physical stiffness of the conduits <NUM>, <NUM>' associated with the left and right pick-off sensors <NUM>, 170r both increased, but that, for example, the physical stiffness associated with the left pick-off sensor <NUM> increased more than the physical stiffness associated with the right pick-off sensor 170r. In one example, the stiffness symmetry <NUM> can be expressed in percentages and be determined by: <MAT> where:.

Although the above discussion pertained to meter stiffness, other meter verification parameters may be employed, additionally or alternatively. For example, a residual flexibility may be compared to a baseline residual flexibility. Residual flexibility can be defined as a portion of a frequency response associated with one vibration mode that is at a resonant frequency of another vibration mode. For example, a frequency response of various vibration modes (e.g., bend, twist, etc.) may be characterized as a frequency response function (e.g., magnitude response relative to frequency). The frequency response function is typically centered at a resonant frequency of a given vibration mode with a sloping decrease in magnitude in proportion to the distance from the resonant frequency. For example, a first order bend mode (e.g., main out-of-phase bend mode) with two nodes located at brace bars, may have a first order bend mode resonant frequency ω<NUM>. A second order bend mode with four nodes may have a second order bend mode resonant frequency ω<NUM> that is greater than the first order bend mode resonant frequency ω<NUM>. The frequency response function of the second order bend mode can overlap the first order bend mode resonant frequency ω<NUM>. Accordingly, the residual flexibility of the first order bend mode caused by the second order bend mode is the portion of the frequency response function of the second order bend mode that lies at the first order bend mode resonant frequency ω<NUM>. As can be appreciated, when erosion, corrosion, damage, coating, or the like occurs, this residual flexibility value of a given mode may change because the frequency response of each vibration mode will change. Accordingly, the residual flexibility can also be used to identify a change in the vibratory meter.

Damping can also be employed. For example, the meter verification can compare a measured damping value to a baseline damping value. Damping can be useful in detecting coating because damping may not be affected by erosion or corrosion.

Similarly, a mass associated with the left or right pick-off sensors <NUM>, 170r can be compared to a baseline mass associated with the left or right pick-off sensors <NUM>, 170r. In one example, an expected mass may be employed. In an example, an expected mass based on the calibrated air and water mass values and the measured or known density of the process fluid may be calculated using the below equation: <MAT> where:.

The expected mass mexpected can be used to calculate a normalized mass deviation expressed as a percent via the following equation: <MAT> where:.

As can be appreciated, erosion, corrosion, damage, coating, or the like, can affect the mass of the conduits in the vibratory meter. Accordingly, the expected mass can be used to detect a change in the vibratory meter by comparing a measured mass to the expected mass.

As discussed above, conduit geometries may also be considered when determining the condition of the conduit. For example, U-shaped tubes may be more prone to erosion than corrosion at certain locations in the conduit compared to, for example, a straight tube. Additionally or alternatively, some process/conduit combinations may be more prone to certain conditions. For example, the conduits <NUM>, <NUM>' may be more prone to damage in cryogenic processes that employ nitrogen compared to high temperature processes that employ a corrosive material. Accordingly, the LPO stiffness change <NUM>, RPO stiffness change <NUM>, and stiffness symmetry <NUM>, or the methods that use these values, can include, for example, other values, such as factors related to conduit geometry, construction, dimensions, process variables, etc..

As can also be seen in <FIG>, the storage system <NUM> can also store a stiffness standard deviation <NUM>, an LPO stiffness standard deviation <NUM>, and an RPO stiffness standard deviation <NUM>. These values can be determined from the meter stiffness measurements that, for example, comprise the baseline meter stiffness <NUM> and the meter stiffness <NUM>. For example, the stiffness standard deviation <NUM> may be a pooled standard deviation. Accordingly, the stiffness standard deviation <NUM> is a measure of how much the meter stiffness <NUM> varied, including the meter stiffness measurements that comprise the baseline meter stiffness <NUM>. The LPO stiffness standard deviation <NUM> and the RPO stiffness standard deviation <NUM> may also be pooled standard deviations.

Although the example shown in <FIG> utilizes stiffness standard deviation, other measures of variation and dispersion in a meter verification parameter data may be employed. For example, a variance may be employed instead of a standard deviation. That is, the stiffness standard deviation <NUM>, LPO stiffness standard deviation <NUM>, and RPO stiffness standard deviation <NUM> are dispersion values of an exemplary meter verification parameter. Additionally or alternatively, other measures of central tendency can be employed instead of a mean value that may be employed for the baseline meter stiffness <NUM> and the meter stiffness <NUM>. Accordingly, the baseline meter stiffness <NUM> and meter stiffness <NUM> are central tendency values of an exemplary meter verification parameter.

The storage can also store other statistical values, such as a confidence interval <NUM>. As will be explained in more detail below, the confidence interval <NUM> can be calculated based on a t-value <NUM>, a significance level <NUM>, and a degree-of-freedom <NUM>. The significance level <NUM> may be a scalar value that is set, for example, by the verification <NUM>. The significance level <NUM> can be defined as the probability of rejecting a null hypothesis when the hypothesis is actually true (e.g., detecting a change when a change has not occurred in the vibratory meter) and is typically a small value, such as <NUM>% or <NUM>. The degree-of-freedom <NUM> is calculated from the number of samples used to determine, for example, the stiffness standard deviation <NUM>. Also shown is a bias dead band <NUM>, which is a scalar value that may also be set by the verification <NUM> to ensure that biases in the vibratory meter does not induce false flags.

The confidence interval <NUM> can detect small changes in the physical stiffness of the vibratory meter <NUM> while also reducing the number of false alarms compared to, for example, the predetermined limits previously used in meter verification. Additionally, the confidence interval <NUM> can be calculated using relatively simple mathematical operations, thereby allowing the processing system <NUM> to employ robust statistical techniques using a verification <NUM> that employs relatively simple embedded code.

The storage system <NUM> may also store a cleaning routine <NUM>. The cleaning routine <NUM> may include various steps, such as, for example, sending a cleaning mode signal via the interface <NUM> and/or the path <NUM>. The cleaning mode signal may be used by devices external of the meter electronics <NUM> and/or the vibratory meter <NUM> to, for example, provide a cleaning solution to the vibratory meter. Additionally or alternatively, the interface <NUM> may receive a cleaning solution signal that may, for example, signal that a cleaning solution is being provided to the vibratory meter <NUM>. The cleaning solution signal may indicate that the solution is being provided, a composition, including concentration, density, temperature, or the like, of the cleaning solution, and/or other data pertaining to the cleaning solution. Accordingly, the cleaning of the vibratory meter <NUM> may be fully automated. The cleaning routine may also include performing the verification <NUM>, which can verify a clean and/or an unclean condition of the meter assembly <NUM>, as the following discussion illustrates.

<FIG> shows a graph <NUM> showing a detection of an unclean condition in a vibratory meter. As shown in <FIG>, the graph <NUM> includes a meter verification counter axis <NUM> and a percent change axis <NUM>. The meter verification counter axis <NUM> ranges from <NUM> to about <NUM> and the percent change axis <NUM> ranges from about -<NUM> % to about <NUM>%. The graph <NUM> also shows an outlet stiffness plot 330a and an inlet stiffness plot 330b. The outlet and inlet stiffness plots 330a, 330b may respectively be associated with the left pick-off sensor <NUM> and the right pick-off sensor 170r. Accordingly, the outlet and inlet stiffness plots 330a, 330b may respectively correspond to the LPO stiffness change <NUM> and the RPO stiffness change <NUM> described with reference to <FIG>.

As can be seen in <FIG>, the outlet and inlet stiffness plots 330a, 330b diverge at a verification count of about <NUM>. As can be appreciated, the outlet stiffness plot 330a increased, indicating that the stiffness around the outlet of the meter assembly <NUM> may have increased. The inlet stiffness plot 330b decreased, indicating that the stiffness around the inlet of the meter assembly <NUM> may have decreased. As discussed above, this may be interpreted to mean an unclean condition, such as a coating, may be present in the meter assembly <NUM>. As discussed above, the meter electronics <NUM> may enter into a cleaning mode where a cleaning routine <NUM> can perform steps, such as sending a cleaning mode signal, receiving a cleaning solution signal, and/or performing the verification <NUM>.

<FIG> shows a method <NUM> of detecting a clean condition in a vibratory meter. As shown in <FIG>, the method <NUM> includes providing a drive signal in step <NUM>. The drive signal may be provided, for example, by the meter electronics <NUM> to the meter assembly <NUM> shown in <FIG>. In step <NUM>, the method <NUM> may receive one or more sensor signals from the meter assembly. The received sensor signals may be the sensor signals <NUM> described above with reference to <FIG>. For example, the received sensor signals may include the left and right sensor signals <NUM>, 165r. In step <NUM>, the method <NUM> determines a parameter of the one or more received sensor signals using a processing system. The parameter may include the meter stiffness <NUM>, the stiffness change <NUM>, the LPO stiffness <NUM>, the LPO stiffness change <NUM>, the RPO stiffness <NUM>, and/or the RPO stiffness change <NUM>. As can be appreciated, the parameter may also include other values, such as the values shown in <FIG>. Additionally or alternatively, the parameter may be a drive gain, such as the drive gain described above. In step <NUM>, the method <NUM>, based on the parameter, detects a clean condition of the meter assembly and places the processing system into a non-cleaning mode. The non-cleaning mode may include, for example, executing the operational routine <NUM> described above with reference to <FIG>. As can be appreciated, the operational routine <NUM> may include executing the verification <NUM> to detect an unclean condition in the meter assembly <NUM> so as to clean the vibratory meter.

<FIG> shows a method <NUM> of cleaning a vibratory meter. As shown in <FIG>, the method <NUM> provides a drive signal to a meter assembly in step <NUM>. The drive signal may be provided, for example, by the meter electronics <NUM> to the meter assembly <NUM> shown in <FIG>. In step <NUM>, the method <NUM> may receive one or more sensor signals from the meter assembly. The received sensor signals may be the sensor signals <NUM> described above with reference to <FIG>. For example, the received sensor signals may include the left and right sensor signals <NUM>, 165r. In step <NUM>, the method <NUM> determines a parameter of the one or more received sensor signals using a processing system. The parameter may include the meter stiffness <NUM>, the stiffness change <NUM>, the LPO stiffness <NUM>, the LPO stiffness change <NUM>, the RPO stiffness <NUM>, and/or the RPO stiffness change <NUM>. As can be appreciated, the parameter may also include other values, such as the values shown in <FIG>. In step <NUM>, the method <NUM>, based on the parameter, detects an unclean condition of the meter assembly and places the processing system into a cleaning mode. The cleaning mode may include, for example, executing the cleaning routine <NUM> described above with reference to <FIG>. As can be appreciated, the cleaning routine <NUM> may include executing the verification <NUM> to detect a clean condition in the meter assembly <NUM>.

As can be appreciated, the methods <NUM>, <NUM> can detect the unclean condition if a value of the parameter substantially deviates from a baseline value of the parameter and/or detect the clean condition if the value of the parameter substantially equals the baseline value of the parameter. As discussed above, the baseline value may be associated with a previously determined clean condition of the vibratory meter. The cleaning mode of the processing system <NUM> comprises the processing system <NUM> being configured to execute a cleaning routine. The cleaning routine may comprise iteratively and repeatedly determining a value of the parameter of the received one or more pick-off signals, comparing the value of the parameter to a baseline value of the parameter, and detect the unclean condition based on the comparison.

As can be appreciated, the drive signal may comprise a resonant component and at least one non-resonant component. The one or more sensor signals may comprise at least one component, the at least one component corresponding to the at least one non-resonant component of the drive signal. Accordingly, the parameter may be determined from the at least one non-resonant component of the drive signal and the at least one component corresponding to the at least one non-resonant component of the drive signal. Additionally or alternatively, the parameter determined from the one or more sensor signals may comprise one of a drive gain of the one or more sensor signals and a resonant frequency of the meter assembly. The parameter may, for example, be one of a stiffness, a mass, and a damping of a conduit of the meter assembly, although any suitable parameter may be employed.

The above describes the vibratory meter <NUM>, in particular the meter electronics <NUM>, as being configured to clean and detect a clean condition of the meter assembly <NUM>. Accordingly, the meter electronics <NUM> or the processing system <NUM> may enter into a cleaning mode wherein the cleaning routine <NUM> may, for example, send the cleaning mode signal and/or receive the cleaning solution signal. The cleaning routine <NUM> may therefore automate some or all of the cleaning of the vibratory meter <NUM>. That is, user interaction and/or intervention with the vibratory meter <NUM> may be reduced or eliminated, leading to more efficient utilization of the vibratory meter <NUM> and a system in which the vibratory meter <NUM> may be employed.

The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the present description. Indeed, persons skilled in the art will recognize that certain elements of the above-described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the present description. It will also be apparent to those of ordinary skill in the art that the above-described embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the present description.

Claim 1:
A meter electronics (<NUM>) configured to automate a cleaning of a conduit in a vibratory meter (<NUM>), the meter electronics (<NUM>) comprising:
an interface (<NUM>) configured to provide a drive signal to a meter assembly (<NUM>) communicatively coupled to the meter electronics (<NUM>) and receive one or more pick-off signals from the meter assembly (<NUM>); and
a processing system (<NUM>) communicatively coupled to the interface (<NUM>), the processing system (<NUM>) being configured to:
determine a parameter from the drive signal and/or the one or more received pick-off signals; and
characterized by:
based on the parameter:
detect an unclean condition of the meter assembly (<NUM>) and enter into a cleaning mode; and
detect a clean condition of the meter assembly (<NUM>) and enter into a non-cleaning mode.