HK1237409A1 - Differential flowmeter tool - Google Patents

Description

Differential flow meter tool

Technical Field

The present invention relates to flow meters, and more particularly to tools for determining optimal operating parameters for differential flow meter systems.

Background

Vibrating sensors, such as, for example, vibrating densitometers and coriolis flowmeters, are well known and are used to measure mass flow and other information of a material flowing through a conduit in the flowmeter. Exemplary coriolis flowmeters are disclosed in U.S. patent 4,109,524, U.S. patent 4,491,025, and re31,450, all to j.e. Smith et al. These flow meters have one or more conduits of straight or curved configuration. For example, each conduit configuration in a coriolis mass flowmeter has a set of natural vibration modes, which may be of the simple bending, torsional, or coupled type. Each conduit may be driven to oscillate in a preferred mode.

Some types of mass flow meters, particularly coriolis flow meters, can operate in a manner that performs a direct measurement of density to provide volumetric information by a quotient of mass to density. See, for example, U.S. patent No. 4,872,351 to Ruesch for a clean oil computer that uses a coriolis flowmeter to measure the density of an unknown multi-phase fluid. U.S. patent No. 5,687,100 to butterer et al teaches a coriolis effect densitometer that corrects density readings for the effect of mass flow rate in a mass flow meter operating as a vibrating tube densitometer.

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

When there is no flow through the flow meter, the driving force applied to the conduit(s) causes all points along the conduit(s) to oscillate with the same phase or small "zero offset" (which is the time delay measured at zero flow). As the material begins to flow through the flowmeter, coriolis forces cause various points along the conduit(s) to have different phases. For example, the phase at the inlet end of the flow meter lags the phase at the concentrated drive location, while the phase at the outlet precedes the phase at the concentrated drive location. The sensing elements on the catheter(s) generate sinusoidal signals representative of the motion of the catheter(s). The signal output from the pickoffs is processed to determine the time delay between the pickoffs. The time delay between two or more sensing elements is proportional to the mass flow rate of the material flowing through the conduit(s).

Meter electronics connected to the driver generates drive signals to operate the driver and determines the mass flow rate and other properties of the material from the signals received from the sensing elements. The driver may comprise one of many well-known arrangements; however, magnets and opposing drive coils have met with great success in the flowmeter industry. An alternating current is passed to the drive coil for vibrating the conduit(s) at the desired conduit amplitude and frequency. It is also known in the art to provide the sensitive element as a magnet and coil arrangement very similar to the driver arrangement. However, although the driver receives a current that causes motion, the sensitive element may use the motion provided by the driver to cause a voltage. The magnitude of the time delay measured by the sensor is very small; typically in nanoseconds. Therefore, it is necessary to make the converter output very accurate.

In some cases, it is desirable to incorporate multiple flow meters into a single system. In one such multiple flow meter example, two flow meters may be used in a large engine fuel system. Such systems are typically found in large marine vessels. For such vessels, proper fuel management is critical for efficient engine system operation. To accurately measure fuel consumption, a flow meter is placed upstream of the engine and another flow meter is placed downstream of the engine. The difference reading between the two flow meters is used to calculate the mass of fuel consumed.

A flow meter of a given size requires a range of fluid flow to maintain accuracy. On the other hand, a given system may have a range of fluid flow requirements, and therefore a flow meter is needed that does not unduly restrict the operation of the system. Thus, an optimal flow meter for a particular system is one that accurately measures flow and related parameters without restricting flow or introducing burdensome pressure drops. Flow constraints and accuracy issues are magnified when two flowmeters are in a single system. For example, a pair of flowmeters with 0.1% accuracy error may not simply add up to 0.2% error when placed in series, but may be much larger. Temperature differences and zero stability differences between two or more flow meters also help to reduce system accuracy.

Therefore, what is needed in the art is a method and related system to calculate the most appropriate size and type of flow meter in a multiple flow meter system based on a given set of operating constraints. There is a need for a method and related system to determine multi-flow meter system accuracy. A need exists for a method and related system to determine a particular flow meter model from a set of candidate flow meters in view of project requirements. The present invention overcomes these and other problems and advances in the art are achieved.

Disclosure of Invention

A method for determining system accuracy is provided according to an embodiment. An embodiment comprises the steps of: hardware specifications for a supply flow meter are input into the computing device, and hardware specifications for a return flow meter are input into the computing device. The system parameters are input into a computing device. System accuracy is calculated with system logic that receives inputs based on hardware specifications on the supply flow meter, hardware specifications on the return flow meter, and system parameters. The calculated system accuracy is stored in a computer readable storage medium and the calculated system accuracy is output.

A system for configuring a metering system is provided according to an embodiment. According to an embodiment, a system includes at least two flow meters, and a computing device configured to receive at least one input and generate at least one output, wherein the at least one input includes at least one flow meter hardware specification and at least one system parameter. The system also includes system logic configured with respect to the computing device to calculate at least one output, wherein the at least one output includes at least one of system accuracy and temperature corrected system accuracy.

Aspect(s)

According to an aspect, a method for determining system accuracy, comprising the steps of: inputting hardware specifications for a supply flow meter into a computing device; inputting hardware specifications for a return flow meter into a computing device; inputting system parameters into a computing device; calculating system accuracy with system logic, wherein the system logic receives inputs based on hardware specifications for the supply flow meter, hardware specifications for the return flow meter, and system parameters; storing the calculated system accuracy in a computer-readable storage medium; and outputting the calculated system accuracy.

Preferably, the hardware specifications for both the supply flow meter and the return flow meter include a base accuracy value.

Preferably, the hardware specifications for both the supply and return flowmeters include a zero offset value.

Preferably, the hardware specifications for both the supply flow meter and the return flow meter include a temperature drift value.

Preferably, the hardware specifications for both the supply flow meter and the return flow meter include a maximum flow rate value.

Preferably, the system parameter comprises a zero calibration temperature value.

Preferably, the system parameter comprises fluid density.

Preferably, the system parameters include an inlet temperature and an outlet temperature.

Preferably, the step of calculating with the system logic the system accuracy comprises the steps of:

calculating supply flowmeter uncertainty U_SWhereinWherein

To supply the temperature drift of the flow meter;

is the maximum supply flow meter flow rate;

is the inlet temperature;

calibrating the temperature for zero;

zero offset to supply flow meter;

to supply the basic accuracy of the flow meter; and

converting a factor for the supply flow rate;

calculating return flowmeter uncertainty U_RWhereinWherein:

is the temperature drift of the return flow meter;

is the maximum return flow meter flow rate;

is the outlet temperature;

calibrating the temperature for zero;

zero offset for return flow meter;

to return to the basic accuracy of the flowmeter; and

the return flow rate conversion factor.

Preferably, the step of calculating system accuracy with system logic comprises calculating total differential measurement accuracyWherein (c) is。

Preferably, the step of calculating system accuracy with the system logic comprises calculating process temperature correction system accuracyWherein (c) isAnd whereinA fuel consumption conversion factor.

Preferably, the method for determining system accuracy includes the step of providing a notification if at least one of the system parameters and the hardware specifications is incompatible with at least one predetermined rule.

Preferably, the method for determining the accuracy of the system comprises the steps of: generating a recommended hardware specification for the supply flow meter from the input system parameters; and generating a recommended hardware specification for the return flow meter from the input system parameters.

According to an aspect, a system for configuring a metering system is provided. A system for configuring a metering system includes at least two flow meters. The system also includes a computing device configured to receive at least one input and generate at least one output, wherein the at least one input includes at least one flow meter hardware specification and at least one system parameter. The system logic with respect to the computing device is configured to calculate at least one output, wherein the at least one output includes at least one of system accuracy and temperature corrected system accuracy.

Preferably, the at least one hardware specification includes a basic accuracy value.

Preferably, the at least one hardware specification includes a zero offset value.

Preferably, the at least one hardware specification includes a temperature drift value.

Preferably, the at least one hardware specification comprises a maximum flow rate value.

Preferably, the at least one system parameter comprises a zero calibration temperature value.

Preferably, the at least one system parameter comprises fluid density.

Preferably, the at least one system parameter comprises an inlet temperature and an outlet temperature.

Preferably, the at least one fuel system accuracy measure includes system accuracy.

Preferably, the system accuracy includesWhereinAnd wherein:

；

to supply the temperature drift of the flow meter;

is the maximum supply flow meter flow rate;

is the inlet temperature;

calibrating the temperature for zero;

zero offset to supply flow meter;

to supply the basic accuracy of the flow meter;

converting a factor for the supply flow rate;

；

is the temperature drift of the return flow meter;

is the maximum return flow meter flow rate;

is the outlet temperature;

calibrating the temperature for zero;

zero offset for return flow meter;

to return to the basic accuracy of the flowmeter; and

the return flow rate conversion factor.

Preferably, the temperature calibration system accuracy comprisesWhereinAnd wherein:

zero offset to supply flow meter;

to supply the basic accuracy of the flow meter;

converting a factor for the supply flow rate;

zero offset for return flow meter;

to return to the basic accuracy of the flowmeter;

converting a factor for the return flow rate; and

a fuel consumption conversion factor.

Drawings

FIG. 1 illustrates a prior art vibration sensor assembly;

FIG. 2 illustrates a prior art fuel system;

FIG. 3 illustrates a computing device according to an embodiment of the invention;

FIG. 4 shows a system for configuring a fluid consuming system according to an embodiment of the present invention;

FIG. 5 illustrates hardware specifications according to an embodiment of the invention;

FIG. 6 illustrates system parameters according to an embodiment of the invention; and

FIG. 7 is a flow chart describing a method for configuring a fluid consuming system in accordance with an embodiment of the present invention.

Detailed Description

Fig. 1-7 and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will recognize variations of these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. Accordingly, the present invention is not limited to the specific examples described below, but only by the claims and their equivalents.

Fig. 1 shows an example of a prior art flow meter 5 in the form of a coriolis flow meter including a sensor assembly 10 and one or more meter electronics 20. One or more meter electronics 20 are connected to the sensor assembly 10 to measure characteristics of the flowing material, such as, for example, density, mass flow rate, volumetric flow rate, total mass flow, temperature, and other information.

The sensor assembly 10 includes a pair of flanges 101 and 101', manifolds 102 and 102', and conduits 103 and 103 '. Manifolds 102,102 'are attached to opposite ends of conduits 103, 103'. The flanges 101 and 101 'of the present example are attached to manifolds 102 and 102'. Manifolds 102 and 102' of the present example are attached to opposite ends of spacer 106. Spacers 106 maintain the spacing between manifolds 102 and 102 'in this example to prevent undesired vibration in conduits 103 and 103'. The conduits 103 and 103' extend outwardly from the manifold in a substantially parallel manner. When the sensor assembly 10 is inserted into a pipeline system (not shown) that carries flowing material, the material enters the sensor assembly 10 through the flange 101, passes through the inlet manifold 102, wherein the total amount of material is directed into the conduits 103 and 103', flows through the conduits 103 and 103' and back into the outlet manifold 102', wherein it exits the sensor assembly 10 through the flange 101'.

The sensor assembly 10 includes a driver 104. The driver 104 is attached to the conduits 103 and 103 'at a position where the driver 104 can vibrate the conduits 103,103' in the drive mode. More specifically, the driver 104 includes a first driver member (not shown) attached to the catheter 103 and a second driver member (not shown) attached to the catheter 103'. The driver 104 may comprise one of many well-known arrangements, such as a magnet mounted to the conduit 103 and an opposing coil mounted to the conduit 103'.

In this example, the drive mode is the first out of phase bending mode, and conduits 103 and 103 'are preferably selected and suitably mounted to inlet and outlet manifolds 102 and 102' so as to provide a balanced system having substantially the same mass distribution, moment of inertia, and modulus of elasticity about bending axes W-W and W '-W', respectively. In the present example, where the drive mode is the first out of phase bending mode, conduits 103 and 103' are driven in opposite directions about their respective bending axes W-W and W ' -W ' by driver 104. The drive signal in the form of an alternating current may be provided by one or more meter electronics 20, as for example via a passage 110, and through a coil to cause the two conduits 103,103' to oscillate. Those skilled in the art will recognize that other drive modes may be used within the scope of the present invention.

The illustrated sensor assembly 10 includes a pair of pickoffs 105,105 'attached to the conduits 103, 103'. More specifically, a first sensitive member (not shown) is located on the conduit 103 and a second sensitive member (not shown) is located on the conduit 103'. In the depicted embodiment, the pickoffs 105,105 'may be electromagnetic detectors, such as pickoff magnets and pickoff coils, that generate pickoff signals representative of the velocity and position of the conduits 103, 103'. For example, the pickoffs 105,105 'may supply pickoff signals to one or more meter electronics 20 via paths 111, 111'. Those skilled in the art will recognize that the motion of the conduits 103,103 'is proportional to certain characteristics of the flowing material, such as the mass flow rate and density of the material flowing through the conduits 103, 103'.

It should be appreciated that while the above-described sensor assembly 10 includes a dual flow conduit flow meter, it is well within the scope of the present invention to implement a single conduit flow meter. Further, while the flow conduits 103,103' are shown as comprising a curved flow conduit configuration, the present invention may be practiced with flow meters comprising a straight flow conduit configuration. It should also be appreciated that the sensing elements 105,105' may include strain gauges, optical sensors, laser sensors, or any other sensor type known in the art. Thus, the particular embodiment of the sensor assembly 10 described above is merely one example, and should in no way limit the scope of the invention.

In the example shown in FIG. 1, one or more meter electronics 20 receive pickoff signals from pickoffs 105, 105'. Path 26 provides input and output means that allow one or more meter electronics 20 to interface with an operator. One or more meter electronics 20 measures characteristics of the flowing material such as, for example, phase difference, frequency, time delay, density, mass flow rate, volume flow rate, total mass flow, temperature, meter verification, and other information. More specifically, one or more meter electronics 20 receive one or more signals, for example, from the sensing elements 105,105' and one or more temperature sensors 107, such as Resistance Temperature Devices (RTDs), and use this information to measure characteristics of the flowing material.

Fig. 2 shows a prior art fuel system 200. The fuel system 200 is shown as a typical marine fuel system. This is merely an example of a multiple flow meter system and should not be used to limit the claims or specification. Fuel is stored in the main tanks 202, 204. In one example of an embodiment, Heavy Fuel Oil (HFO) is stored in a first main tank 202 and Marine Diesel Oil (MDO) is stored in a second main tank 204. The main tanks 202,204 are fed into the day tank 206 through fuel lines 203 and 205, respectively. This is merely an example and it should be clear that more than two main tanks may be present or that only one main tank may be present. The day tank 206 is typically sized to store a limited amount of fuel for safety and contamination purposes. The day tank 206 prevents excess fuel from being stored in areas such as the engine compartment of a watercraft in order to minimize the risk of fire or explosion. If a fire is present, limited fuel availability helps to reduce the severity of the fire-related incident. Further, the day tank 206 receives fuel given to the engine 208, but is not utilized thereby, so the return fuel is sent back to the day tank 206 through the return fuel line 207. It should be appreciated that although the fuel system 200 shows only one fuel outlet 222 and two flow meters 214,216, in some embodiments, there will be multiple fuel outlets and more than two flow meters.

During operation, fuel is typically recirculated from the day tank 206 to the engine 208 or other fuel consuming device, and any fuel not consumed flows back to the day tank 206 in the closed loop 218. If day tank 206 becomes low on fuel, the fuel from main tanks 202,204 refills day tank 206. The pump 210 provides the required action to pump fuel from the day tank 206 to the engine 208 and back. The inline preheater 212 heats the fuel to a temperature that is ideal for the fuel utilized by the engine 208. For example, the operating temperature of HFO is generally between 120 ℃ and 150 ℃, while MDO is desirably about 30 ℃ to 50 ℃. The appropriate temperature for a particular fuel allows the viscosity of the fuel to be controlled and maintained within a desired range. The kinematic viscosity of a fuel is a measure of the fluidity at a certain temperature. Since the viscosity of the fuel decreases with increasing temperature, the viscosity at the moment the fuel leaves the fuel injectors (not shown) of the engine must be within the range dictated by the engine manufacturer in order to produce the optimum fuel spray pattern. Off-specification stickiness results in substandard combustion, power loss, and potential deposit formation. The preheater 212 allows for the optimum viscosity to be obtained when set correctly for the particular fuel being used.

To measure a flow parameter, such as mass flow rate or density, for example, an in-line flow meter is utilized. The supply-side flow meter 214 is located upstream of the engine 208, while the return-side flow meter 216 is located downstream of the engine 208. Since the engine 208 does not use all of the fuel provided to the engines in the common fuel rail system (not shown), excess fuel is recirculated through the day tank 206 and the closed loop 218. Thus, a single flow meter will not provide accurate flow measurement results (particularly with respect to engine fuel consumption), thus requiring both the supply flow meter 214 and the return flow meter 216 (upstream and downstream of the engine 208, respectively). The difference in the flow rates measured by the flow meters 214,216 is approximately equal to the flow rate of fuel consumed by the engine 208. Thus, the difference in measured flow rate between the flow meters 214,216 is a primary value of interest in most applications similar to the configuration shown in FIG. 2. It should be noted that the common rail fuel system is used as an example only and does not limit the scope of the claimed invention. Other fuel systems are contemplated in which fuel is returned and/or recirculated.

When operating large engines, knowing the inlet and outlet status of the system is critical to efficiency and performance. Most engine systems, such as the one shown in FIG. 2, have a fuel conditioning system for preparing the fuel to a particular viscosity, temperature, and consistency before it enters the engine, such as the preheater 212. Having the correct fuel condition can strongly affect the performance of the engine. A viscometer 213 downstream of the preheater 212 measures the fuel viscosity and, in some embodiments, may communicate with the preheater 212 to adjust the preheater temperature so that the fuel remains within a predetermined viscosity range.

Meter electronics 20 may include interfaces, digitizers, processing systems, internal memory, external memory, and storage systems. Meter electronics 20 may generate a drive signal and supply the drive signal to driver 104. Further, the meter electronics 20 may receive sensor signals from the flow meters 214,216, such as pickoff/velocity sensor signals, strain signals, optical signals, temperature signals, or any other signals known in the art. In some embodiments, the sensor signal may be received from the sensing elements 105, 105'. The meter electronics 20 may operate as a densitometer or as a mass flow meter, including as a coriolis flow meter. It should be appreciated that meter electronics 20 may also operate as some other type of sensor assembly, and the particular examples provided should not limit the scope of the present invention. The meter electronics 20 may process the sensor signals to obtain flow characteristics of the material flowing through the flow conduits 103, 103'. In some embodiments, meter electronics 20 may receive temperature signals from, for example, one or more RTD sensors or other temperature sensors 107.

The meter electronics 20 may receive sensor signals from the driver 104 or the pickoffs 105,105 'via leads 110,111,111'. The meter electronics 20 may perform any necessary or desired signal conditioning, such as any manner of formatting, amplifying, buffering, etc. Alternatively, some or all of the signal conditioning may be performed in the processing system. Further, the interface 220 may enable communication between the meter electronics 20 and external devices and additional meter electronics 20. The interface may be capable of any manner of electronic, optical, or wireless communication.

The meter electronics 20 may include a digitizer in one embodiment, wherein the sensor signal comprises an analog sensor signal. The digitizer may sample and digitize the analog sensor signal and generate a digital sensor signal. The digitizer may also perform any required sampling in which the digital sensor signal is sampled in order to reduce the amount of signal processing required and reduce processing time.

The meter electronics 20 may include a processing system that may perform the operations of the meter electronics 20 and process the flow measurements from the sensor assembly 10. The processing system may execute one or more processing routines, such as, for example, a zero consumption acquisition routine, a difference zero determination routine, a general operation routine, and a fuel type signal routine, and process the flow measurements accordingly to generate one or more flow measurements.

The processing system may comprise a general purpose computer, a micro-processing system, a logic circuit, or some other general purpose or custom processing device. The processing system may be distributed among a plurality of processing devices. The processing system may include any manner of integrated or stand-alone electronic storage media. The processing system processes the sensor signals to generate, among other things, drive signals. The drive signal is supplied to the driver 104 in order to vibrate the associated conduit(s), such as conduits 103,103' of fig. 1.

It should be understood that meter electronics 20 may include various other components and functions as are well known in the art. These additional features are omitted from the description and drawings for the sake of brevity. Therefore, the invention should not be limited to the particular embodiments shown and discussed.

As the processing system generates various flow characteristics, such as, for example, mass flow rate or volumetric flow rate, errors may be associated with the generated flow rate due to changes or drifts in the zero offset of the vibratory flow meter and, more particularly, the zero offset of the vibratory flow meter. The zero offset may drift away from the originally calculated value due to a number of factors including one or more operating conditions, particularly changes in the temperature of the vibrating flow meter. The change in temperature may be due to a change in fluid temperature, ambient temperature, or both. In the fuel system 200, the preheater 212 is primarily responsible for the temperature of the fluid experienced by the flow meters 214, 216. During the determination of the initial zero offset, the change in temperature will likely deviate from the reference or calibration temperature of the sensor. According to an embodiment, meter electronics 20 may correct for such drift.

As described in detail below, embodiments of a system and method for calculating optimal differential flowmeter system accuracy according to embodiments of the present invention are particularly suited for implementation in connection with computing device 300. FIG. 3 is a diagram of a computing device 300 for processing information, according to an embodiment of the invention. This diagram is merely an example, which should not limit the scope of the claims herein. Numerous other variations, modifications, and alternatives will occur to those skilled in the art. Embodiments in accordance with the invention can be implemented in a single application, such as a browser, or as multiple programs in a distributed computing environment, such as a workstation, personal computer, or remote terminal in a client server/relationship. Embodiments may also be implemented as standalone devices such as, without limitation, laptops, tablet computing devices, smart phones, dedicated computing hardware, and meter electronics 20, for example.

Fig. 3 shows a computing device 300 that includes a display device 302, a keyboard 304, and a trackpad 306. Trackpad 306 and keyboard 304 are representative examples of input devices and may be any input device, such as a touch screen, mouse, roller ball, bar code scanner, microphone, and the like. The trackpad 306 has adjacent buttons 308 for selecting items on a graphical user interface device (GUI), which are displayed on the display device 302. FIG. 3 is representative of one type of system for practicing the present invention. It will be readily apparent to those skilled in the art that many system types and configurations are suitable for use in conjunction with the present invention. In one embodiment, the computing system includes an operating system, such as Windows, Mac OS, BSD, UNIX, Linux, Android, iOS, or the like. However, the device is readily modified by those skilled in the art into other operating systems and architectures without departing from the scope of the present invention.

The computing device may include a housing 310 that houses computer components such as a central processing unit, co-processors, video processors, input/output (I/O) interfaces, network and communication interfaces, disk drives, storage devices, and the like. Storage devices include, but are not limited to, optical drives/media, magnetic drives/media, solid state memory, volatile memory, network storage, cloud storage, and the like. The I/O interface includes a serial port, a parallel port, a USB port, an IEEE1394 port, and the like. The I/O interface communicates with peripheral devices such as printers, scanners, modems, local area networks, wide area networks, virtual private networks, external storage and memory, attached computing devices 300, flow meters 5, and the like. Other variations, modifications, and alternatives will occur to those skilled in the art.

The above system components may communicate with each other and control the execution of instructions from the system memory or storage device, and the exchange of information between computer subsystems. Other arrangements of subsystems and interconnections can be readily implemented by those skilled in the art.

FIG. 4 is an overview of an embodiment of a computer-based system 400 for determining optimal operating parameters for a differential flow meter system according to an embodiment. Some embodiments of the system 400 may process inputs 402 in the form of data including hardware specifications 404 and system parameters 406. The inputs 402 are processed by the system logic 408 to produce outputs 410, which include, for example, system accuracy 412 and system accuracy 414 for temperature correction.

The system logic 408 processes the inputs 402, but before processing occurs, any number of compatibility rules 407 may exist that are used to constrain the inputs so that the appropriate inputs are received and the appropriate outputs are generated. When system parameters 406 and hardware specifications 404 are input into the computing device, compatibility rules 407 verify that input 402 is compatible with the predetermined rules. This ensures that the hardware selected for a particular fuel system 200 will function properly/effectively and not create any dangerous or inherently inaccurate fuel system configuration. Other rules include constraints on the size of the associated flow meter. For example, in an embodiment, the return flow meter 216 may be no larger than the supply flow meter 214. In an embodiment, the return flow rate may not be a value greater than the supply flow rate. In an embodiment, in the case of the fuel system 200, the inlet temperature 604 may not be higher than the outlet temperature 606. In an embodiment, the fluid density 602 may not exceed the density of the fluid allowed by the selected flow meter. There are only examples of rules that may be used, and other rules are contemplated as being within the scope of the present specification and claims. In embodiments, some rules are used to provide flags or warnings to indicate potential, but not absolute, problems. These rules may simply alert of potential incompatibilities, but will still allow the system 400 to process such inputs 402.

The system logic 408 processes the input 402 and, in an embodiment, any associated factors. The associated factors include other sources of data in machine-readable form about the input, which may be generated during or after processing of the input, constants, intermediate values, and the like. The system logic 408 performs a series of steps, algorithms, and/or equations using the inputs 402 and any associated factors. In one embodiment, code residing on a computer-readable storage medium may instruct a processor to receive input 402 and generate output 410. As indicated in FIG. 4, the code may instruct the processor to process the inputs 402 through the system logic 408 and compute the outputs 410, as in embodiments of system accuracy 412, 414.

Fig. 5 is a diagram illustrating a hardware specification 404 that serves as an input 402 to the system 400. The hardware specification 404 is a factor/variable related to the flow meter used in a particular system. In the example provided, two flow meters are utilized, so the hardware specification 404 includes a supply flow meter factor 500 and a return flow meter factor 502. Such factors include model 504, the basic accuracy 506 of each meter, the zero offset 508 of each meter, the temperature drift of each meter 510, and the maximum flow rate 512 of each meter. Note that neither of these factors need be the same or different between the supply flow meter 214 and the return flow meter 216. Model 504 is an identification of a particular flow meter having a particular set of associated properties. For example, and without limitation, the "MicroMotion F025" flow meter is a coriolis mass flow meter that can accept line sizes of 1/4 "to 1/2" and can receive a fluid flow of 100 lb/min. By way of example, other characteristics associated with this ad hoc mode are shown in table 1:

the basic accuracy 506 of the flow meters 214,216 is the error rate associated with the particular flow meter used in the application. The base accuracy 506 is typically a specified user selection and may range, for example, from approximately 0.05% to 0.5% error in flow rate depending on the particular fluid passing through the meter, the particular flow measurement being measured, and the level of accuracy inherent in the flow meter.

The zero-offset 508 or zero-stability is a measure preferably measured in lb/min to indicate the flow recorded by the flow meter when there is zero flow through the conduit 103, 103'. In general, the flow meter 5 is initially calibrated at the factory to generate a zero offset map. In use, the flow calibration factor is typically multiplied by the time delay measured by the sensing element minus the zero offset 508 to generate the mass flow rate. In most cases, the flow meter 5 is initially calibrated and assumed to provide accurate measurements without the need for subsequent calibrations. While this initially determined zero offset 508 may adequately correct the measurement in a number of situations, the zero offset 508 may change over time due to changes in various operating conditions, including temperature, resulting in only a partial correction. However, other operating conditions may also affect the zero offset 508, including pressure, fluid density, sensor mounting conditions, and the like. Further, the zero offset 508 may vary at different rates from one meter to another. This may be of particular interest in situations where more than one meter is connected in series such that each of the meters will read the same value (if measuring the same fluid flow). In an embodiment, the zero offset 508 is a fixed value. In another embodiment, a plurality of zero offsets 508 are stored in memory, and suitable zero offsets 508 are applied to the calculations based on process temperature, temperature difference between the flow meters 214,216, pressure, fluid density, and/or sensor mounting conditions.

Temperature drift 510 is a known rate of accuracy drift that occurs when the flow meter deviates away from the temperature at which factory zero calibration occurs. The temperature drift 510 is measured as a percentage of the maximum flow rate 512 for a particular flow meter. The maximum flow rate 512 is simply the maximum flow rate that a particular flow meter can accurately measure.

Fig. 6 is a diagram illustrating system parameters 406 used as inputs 402 to the system 400. The system parameters 406 are factors/variables for the system 400 into which the flow meter is to be integrated. In the example provided, two flow meters are utilized, one referred to as a supply flow meter 214, which is located upstream of the engine 208, and a return flow meter 216, which is located downstream of the engine 208. The zero calibration temperature 600 is a temperature calibrated by the end user or at the factory for each flow meter 214, 216. The fluid density 602 is the density (preferably measured in g/cc) of the fluid utilized by the fuel system 200. In an embodiment, simply entering the type of fuel utilized and the process temperature will calculate the fluid density 602 by accessing a lookup table containing relevant fuel data. In an embodiment, a user may manually input the fluid density 602. The inlet temperature 604 is the known temperature of the fluid immediately prior to entering the supply flow meter 214, while the outlet temperature 606 is the temperature of the fluid immediately prior to entering the return flow meter 216. These temperatures may correspond to, for example, a flow meter temperature or a meter electronics temperature. Finally, the conversion factor 608 refers to any factor or constant utilized by the equations or algorithms of the system 400. Some examples of conversion factors 608 include, without limitation, constants that convert or modify the metric values to U.S. customary units and/or vice versa.

The system logic 408 utilizes the inputs 402 and any associated factors to calculate any series of steps, algorithms, and/or equations and execute the executable file (executable) to generate outputs 410, such as system accuracy 412, 414. In an embodiment, the system logic 408 calculates a supply flow meter uncertainty. The supply flow meter uncertainty according to an embodiment is calculated according to equation (1):

(1)

wherein:

= supply flow meter uncertainty

= supply flow meter temperature drift

= maximum supply flow rate

= inlet temperature

= zero calibration temperature

= zero offset of supply flowmeter

= basic accuracy of supply flow meter

= supply flow conversion factor

As mentioned above, the temperature drift 510, the maximum supply flow meter flow rate 512, the supply flow meter zero offset 508, and the supply flow meter base accuracy 506 are the supply flow meter factor 500 input into the system 400. The inlet temperature 604 is the system parameter 406 input into the system 400. The supply flow rate conversion factor is conversion factor 608.

Similarly, the return flow meter uncertainty is calculated in the embodiment in the system logic 408 according to equation (2):

(2)

wherein:

= return flow meter uncertainty

= return flow meter temperature drift

= maximum return flow meter flow rate

= outlet temperature

= zero calibration temperature

= zero offset of return flowmeter

= basic accuracy of return flowmeter

= return flow conversion factor

According to an embodiment, system accuracy 412 is calculated in system logic 408 according to equation (3). This embodiment reflects the uncertainty in the total differential measurement by means of factory zero.

(3)

Wherein:

= total differential measurement accuracy calculated as factory zero

According to an embodiment, the system accuracy 414 of the temperature correction is calculated in the system logic 408 according to equation (4). This embodiment reflects the uncertainty in the total differential measurement by virtue of the zero-point determination at the process temperature.

(4)

Wherein:

= total differential measurement accuracy calculated at process temperature

= zero point stability of supply flowmeter

= basic accuracy of supply flow meter

= supply flow conversion factor

= zero offset of return flowmeter

= basic accuracy of return flowmeter

= return flow conversion factor

= fuel consumption conversion factor

Equations (3) and (4) are merely used as examples for calculating the accuracy of a multiple flow meter system having two flow meters in series, and should not limit the claims or the specification in any way. Alternative equations and algorithms are contemplated. One such alternative example is implemented by equation (5), where the differential meter accuracy is determined by the system logic 408 using a square root analysis of the sum:

(5)

wherein:

accuracy of square root of sum =

= flow rate before engine

= flow rate after engine

= basic accuracy of supply flow meter

= basic accuracy of return flowmeter

FIG. 7 is a flow chart illustrating an embodiment of a method of configuring a fluid consumption system having at least two flow meters designed to provide a differential measurement, such as, for example, fluid consumption. The first step includes inputting data into the computing device 300. Specifically, the hardware specifications 404 for the supply flow meter 214 are input into the computing device 300 in step 700. Similarly, the hardware specification 404 for the return flow meter 216 is input into the computing device 300 in step 702. As mentioned above, the hardware specifications may include at least such factors as the model 504, the basic accuracy 506 of each meter, the zero offset 508 of each meter, the temperature drift of each meter 510, and the maximum flow rate 512 of each meter. Other specifications may also be entered in steps 700 and 702, and those listed are merely examples of potential specifications and are not limiting.

In step 704, system parameters 406 are input into computing device 300. Such parameters include a zero calibration temperature 600, a fluid density 602, an inlet temperature 604, which is the temperature of the fluid immediately prior to entering the return flow meter 216, an outlet temperature 606, and any conversion factors 608. Other system parameters 406 may also be entered in step 704, and those listed are merely examples of potential inputs, not limitations. In an embodiment, the computing arrangement 300 calculates and recommends a particular flow meter model or specification based on the system parameter inputs in step 704. In this embodiment, step 704 is performed before steps 700 and 702, and the flow meter hardware specification 404 is generated and suggested by the computing device. In one embodiment, these proposed hardware specifications 404 are automatically entered into the computing device 300.

A number of rules may exist with respect to the system, stored in, for example, memory or a computer readable medium. Such rules are used to constrain the inputs and outputs such that appropriate inputs are received and appropriate outputs are generated. For example, a fuel system 200 having a maximum mass flow of fluid into the supply flow meter 214 of 200lb/min will not be compatible with a supply flow meter 214 having a maximum flow rate of only 100 lb/min. Thus, when the system parameters 406 and hardware specifications 404 are entered into the computing device in steps 700,702, and 704, the next step (step 706) is to verify that the input 402 is consistent with the predetermined rules. Thus, in the above example, the fuel system 200 has a flow that exceeds the capability of the selected supply flow meter 214, so a notification is generated in step 707. After generating the notification, the system 400 prompts the user to re-enter compatible input. These steps 706,707 ensure that the hardware selected for a particular fuel system 200 will function properly/efficiently and not create any dangerous or inherently inaccurate fuel system configuration. Other rules include constraints on relative flow meter size. In an embodiment, the return flow meter 216 may be no larger than the supply flow meter 214. In an embodiment, the return flow rate may not be a value greater than the supply flow rate. In an embodiment, in the case of the fuel system 200, the inlet temperature 604 may not be higher than the outlet temperature 606. In an embodiment, the fluid density 602 may not exceed the density of the fluid allowed by the selected flow meter. These are merely examples of rules that are checked in step 706, and other rules are contemplated as being within the scope of the present description and claims. In embodiments, some rules are used to provide flags or warnings to indicate potential, but not absolute, problems. These rules may simply alert of potential incompatibilities, but will still allow the system 400 to process such inputs 402.

In step 708, if the inputs 402 are compatible with each other and any other constraints, the system logic 408 computes an output 410, such as system accuracy 412, 414. In this step, system logic 408 may use any inputs, stored information, and/or constants to calculate any number of intermediate or final output values. An example of an intermediate value is supply flow meter uncertainty. In an embodiment, the supply flow meter uncertainty is calculated according to equation (1):. Another example of an intermediate value is the return flow meter uncertainty. Outputs such as system accuracy 412, system accuracy of temperature correction 414, and accuracy of the square root of the sum are also calculated by the system logic 408 in this step. In an embodiment, the system accuracy 412, the system accuracy of the temperature correction 414, and the accuracy of the square root of the sum are calculated using equations (3), (4), and (5), respectively.

In step 710, the system accuracy 412,414 is stored in memory or computer readable storage medium along with any other output 410. These values may then be output in step 712. For example, outputting generally means informing the user of the calculated value via the display device 302, or printing the calculated value by a peripheral device such as a printer, or emailing the calculated value to the user.

The present invention as described above provides various methods to calculate accuracy in a multi-vibratory flow meter system using a meter, such as a coriolis flow meter. While the various embodiments described above are directed to flow meters, and in particular coriolis flow meters, it should be appreciated that the present invention should not be limited to coriolis flow meters, but rather that the methods described herein may be utilized with other types of flow meters, or other vibration sensors that lack some of the measurement capabilities of coriolis flow meters.

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

Thus, while specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. The teachings provided herein are applicable to other vibration sensors and not just to the embodiments described above and shown in the drawings. Accordingly, the scope of the invention should be determined from the following claims.

Claims (24)

1. A method for determining system accuracy, comprising the steps of:

inputting hardware specifications for a supply flow meter into a computing device;

inputting hardware specifications for a return flow meter into the computing device;

inputting system parameters into the computing device;

calculating a system accuracy with a system logic, wherein the system logic receives the inputs based on hardware specifications for the supply flow meter, the hardware specifications for the return flow meter, and the system parameters;

storing the calculated system accuracy in a computer-readable storage medium; and

outputting the calculated system accuracy.

2. The method for determining system accuracy of claim 1, wherein the hardware specifications for the supply flowmeter and the return flowmeter each comprise a base accuracy value.

3. The method for determining system accuracy of claim 1, wherein the hardware specifications for the supply flowmeter and the return flowmeter each include a zero offset value.

4. The method for determining system accuracy of claim 1, wherein the hardware specifications for the supply flowmeter and the return flowmeter each comprise a temperature drift value.

5. The method for determining system accuracy of claim 1, wherein the hardware specifications for the supply flowmeter and the return flowmeter each comprise a maximum flow rate value.

6. The method for determining system accuracy of claim 1, wherein the system parameter comprises a zero calibration temperature value.

7. The method for determining system accuracy of claim 1, wherein the system parameter comprises fluid density.

8. The method for determining system accuracy of claim 1, wherein the system parameters comprise an inlet temperature and an outlet temperature.

9. The method for determining system accuracy of claim 1, wherein said step of calculating system accuracy in system logic comprises the steps of:

calculating supply flowmeter uncertainty U_SWhereinWherein:

to supply the temperature drift of the flow meter;

is the maximum supply flow meter flow rate;

is the inlet temperature;

calibrating the temperature for zero;

zero offset to supply flow meter;

to supply the basic accuracy of the flow meter; and

converting a factor for the supply flow rate;

calculating return flowmeter uncertainty U_RWhereinWherein:

is the temperature drift of the return flow meter;

is the maximum return flow meter flow rate;

is the outlet temperature;

calibrating the temperature for zero;

zero offset for return flow meter;

to return to the basic accuracy of the flowmeter; and

the return flow rate conversion factor.

10. The method for determining system accuracy of claim 9, wherein said step of calculating system accuracy in system logic comprises calculating total differential measurement accuracy a_{Factory Zero}Wherein A is_{Factory Zero=}。

11. The method for determining system accuracy of claim 9, wherein said step of calculating system accuracy in system logic comprises calculating process temperature correction system accuracy a_ProcessWherein A is_Process=And wherein C_FCA fuel consumption conversion factor.

12. The method for determining system accuracy of claim 1, comprising the step of providing a notification if at least one of a system parameter and a hardware specification is incompatible with at least one predetermined rule.

13. The method for determining system accuracy of claim 1, comprising the steps of:

generating a recommended hardware specification for the supply flowmeter from the input system parameters; and

generating a recommended hardware specification for the return flow meter from the input system parameters.

14. A system (400) for configuring a metering system, comprising:

at least two flow meters (214, 216);

a computing device (300) configured to receive at least one input (402) and generate at least one output (410), wherein the at least one input (402) comprises at least one flow meter hardware specification (404) and at least one system parameter (406); and

system logic (408) configured with respect to the computing device (300) to compute the at least one output (410), wherein the at least one output (410) comprises at least one of a system accuracy (412) and a temperature corrected system accuracy (414).

15. The system (400) for configuring a metering system of claim 14, wherein the at least one hardware specification (404) comprises a base accuracy value (506).

16. The system (400) for configuring a metering system of claim 14, wherein the at least one hardware specification (404) comprises a zero offset value (508).

17. The system (400) for configuring a metering system of claim 14, wherein the at least one hardware specification (404) comprises a temperature drift value (510).

18. The system (400) for configuring a metering system of claim 14, wherein the at least one hardware specification (404) comprises a maximum flow rate value (512).

19. The system (400) for configuring a metrology system of claim 14, wherein the at least one system parameter (406) comprises a zero calibration temperature value (600).

20. The system (400) for configuring a metering system of claim 14, wherein the at least one system parameter (406) comprises a fluid density (602).

21. The system (400) for configuring a metering system of claim 14, wherein the at least one system parameter (406) comprises an inlet temperature (604) and an outlet temperature (606).

22. The system (400) for configuring a metering system of claim 14, wherein the at least one fuel system (200) accuracy metric (412,414) comprises a system accuracy (412).

23. The system (400) for configuring a metering system of claim 14, wherein the system accuracy (412) comprises a_{Factory Zero}Wherein A is_{Factory Zero}=And wherein:

；

to supply the temperature drift of the flow meter;

is the maximum supply flow meter flow rate;

is the inlet temperature;

calibrating the temperature for zero;

zero offset to supply flow meter;

for supplying flow metersBasic accuracy;

converting a factor for the supply flow rate;

；

is the temperature drift of the return flow meter;

is the maximum return flow meter flow rate;

is the outlet temperature;

calibrating the temperature for zero;

zero offset for return flow meter;

to return to the basic accuracy of the flowmeter; and

the return flow rate conversion factor.

24. The system (400) for configuring a metering system of claim 14Wherein the system accuracy (414) of the temperature correction comprises A_processWherein A is_process=And wherein:

zero offset to supply flow meter;

to supply the basic accuracy of the flow meter;

converting a factor for the supply flow rate;

zero offset for return flow meter;

to return to the basic accuracy of the flowmeter;

converting a factor for the return flow rate; and

a fuel consumption conversion factor.