HK1117591B

HK1117591B - A method and apparatus for directing the use of a coriolis flow meter

Info

Publication number: HK1117591B
Application number: HK08107706.2A
Authority: HK
Inventors: Craig B. Mcanally; Andrew T. Patten; Charles P. Stack; Jeffrey S. Walker; Neal B. Gronlie
Original assignee: Micro Motion, Inc.
Filing date: 2004-12-30
Publication date: 2012-12-07

Description

Method and apparatus for directing use of a coriolis flowmeter

Technical Field

The present invention relates to the field of flow meters, and in particular, Coriolis (Coriolis) flow meters.

Background

Because coriolis flowmeters do not have any internal moving parts, there is no place to wear or break. Thus, in clean fluids, it is desirable that the flow meter not change its measurement characteristics over time. Unfortunately, certain fluids may cause corrosion or erosion of the conduits inside the flow meter. Another problem that may arise with respect to fluids is that they may deposit coatings along the inner diameter of the conduits in a coriolis flowmeter. Both types of activity (removal of material or deposition of material) can cause changes in the flow meter measurement characteristics. One way to detect and correct these problems is to test (prove) the meter to recalibrate the meter's measurement characteristics. Verification is a field calibration method in which a known volume (volume) is flowed through a flow meter and compared to the flow rate measured by the flow meter. The tester may be fixed, e.g. permanently mounted next to the meter, or may be removably mounted (such that the tester can calibrate a plurality of meters). A typical prover is a device having a pipe (104) with a known inner diameter. The ball or piston (102) slides inside the pipe (104) and passes through two sensors (S1, S2) or detectors. The first sensor (S1) sends a signal to the computer of the prover to begin counting pulses from the flow meter being calibrated. The pulses are typically proportional to the volumetric flow rate. The second sensor (S2) sends a signal to the prover to stop counting pulses from the flow meter under calibration. The volume inside the pipe between the two detectors is known and is usually compensated for pressure and temperature. The total volume between the two detectors is compared to the number of pulses from the flow meter and a meter factor is determined. The meter factor is simply a correction factor applied to the output of the meter. The measurement time for a known volume flow through the flow meter may be from 0.5 to 60 seconds, depending on the volume of the prover and the flow rate used. The checker typically has a length of tubing through which the ball or piston passes before passing through the first detector. This length of tubing is typically referred to as a "pre-test". The pretest length is equivalent to a fixed volume. The pre-run time depends on the flow rate. At high flow rates, the pre-run time can be very short.

Another way in which the measured characteristics of the meter can be verified is by measuring the density of a material having a known density. The measurement characteristics of the meter are also accurate when the density measurement from the flow meter matches a known density. See, for example, U.S. Pat. No. 5,409, "System for identification of a Coriolis flowmeter", published 25/7/2000, the entire teachings of which are incorporated herein by reference. Unfortunately, verifying the measured characteristics of a flow meter by measuring density or by inspection requires an operator who is familiar with the operation and setup of the coriolis flow meter. It is not always possible to find a skilled operator verifying the measurement characteristics of the meter.

What is needed is a system and method for guiding a user through the steps of using a meter to accomplish a predetermined task.

Disclosure of Invention

A method and apparatus for guiding a user through a sequence of steps is disclosed that enables the user to use a flow meter to accomplish a predetermined task. The method comprises the following steps: selecting a predetermined task; displaying a sequence of steps that guides a user through a process that uses the coriolis flowmeter to accomplish a predetermined task; and operating the coriolis flowmeter in response to the sequence of steps to accomplish the predetermined task.

Aspect(s)

One aspect of the invention includes a method comprising:

selecting a predetermined task to be accomplished using the coriolis flow meter;

displaying sequence steps for completing the predetermined task using the coriolis flow meter;

receiving a user response to the sequence step;

the coriolis flowmeter is operated based on the user response to accomplish the predetermined task.

Preferably, the method further comprises: selecting the predetermined task is accomplished by launching a gulu module corresponding to the predetermined task.

Preferably, the method further comprises: selecting the predetermined task is accomplished by selecting the predetermined task from a plurality of predetermined tasks in the guru module.

Preferably, the method further comprises: the predetermined task selected is to validate a flow calibration factor for the coriolis flowmeter.

Preferably, the method further comprises:

prompting a user to select a material having a known density;

prompting the user to select a desired accuracy for the coriolis flowmeter;

determining a density deviation from the known density corresponding to the desired accuracy;

directing the user to introduce the material into the coriolis flowmeter;

measuring a density of the material using the coriolis flowmeter;

comparing the measured density to the known density;

alerting the user of an error condition when the measured density differs from the known density by more than the density deviation.

Preferably, the method further comprises: the density of the material was measured for at least 5 minutes.

Preferably, the method further comprises: the user is prompted to select a material having a known density from the plurality of displayed materials.

Preferably, the method further comprises: wherein water is one of the plurality of displayed materials.

Preferably, the method further comprises: wherein the relation between the required accuracy (RC) and the Density Deviation (DD) is

Preferably, the method further comprises: wherein the measured density is stored using a non-volatile medium.

Preferably, the method further comprises:

the density measurement of the material of known density is periodically repeated and the results of the new measurement are compared to the stored density measurement.

Preferably, the method further comprises:

the stability of at least one parameter used by the coriolis flowmeter over a given period of time is measured before beginning a density measurement of the material having a known density.

Preferably, the method further comprises: wherein the at least one parameter is selected from the group consisting of: density, live zero, temperature, drive gain, and flow.

Preferably, the method further comprises: the predetermined task is to verify the coriolis flow meter using a verifier.

Preferably, the method further comprises the steps of:

prompting the user to input inspection operation information;

the coriolis flow meter is configured for a test run using the test run information input.

Preferably, the method further comprises:

the operation of the coriolis flow meter is coordinated during the test run.

Preferably, the method further comprises: the test run information includes flow rate, test volume, pre-test volume, and flow rate unit.

Preferably, the method further comprises: the coriolis flow meter parameter configuration includes a frequency output, a damping rate, and a signal processing speed.

Preferably, the method further comprises: the predetermined task is to linearize the coriolis flow meter using information from two test runs at two different flow rates.

Preferably, the method further comprises the steps of:

prompting the user to enter data from the two inspection runs;

calculating a new Coriolis Flow Calibration (CFC) and a new zero offset using data from the two test runs;

the coriolis flow meter CFC and the zero point offset are updated.

Preferably, the method further comprises the steps of:

adjusting the test of the meter using a tester at two different flow rates;

the coriolis flow meter CFC and the zero point offset are updated.

Another aspect of the invention comprises:

a coriolis flowmeter;

a computer system coupled to the coriolis flowmeter, comprising a display;

a coriolis control module running on the computer system, wherein the coriolis control module is configured to control the coriolis flow meter;

a Coriolis Guru module operating on the computer system and configured to communicate with the Coriolis control module;

the coriolis guru module is configured to display a sequence of steps that direct the user to use the coriolis flowmeter to complete the predetermined task.

Preferably, the method further comprises the sequence steps of:

prompting the user to input inspection operation information;

configuring the coriolis flow meter for a test run using the input test run information;

the operation of the coriolis flow meter is adjusted during the test run.

Preferably, the method further comprises the sequence steps of:

prompting a user to input data from two test runs, wherein the two test runs use different flow rates;

the coriolis flow meter CFC and the zero point offset are updated.

Preferably, the method further comprises the sequence steps of:

prompting a user to select a material having a known density;

directing the user to flow the material through the coriolis flowmeter;

measuring a density of the material using the coriolis flowmeter;

comparing the measured density to the known density;

alerting the user that an error condition exists when the measured density differs from the known density by more than a predetermined amount.

Preferably, the method further comprises:

prompting a user to select a desired accuracy for the coriolis flowmeter;

setting the predetermined amount equal to the density deviation.

Preferably, the method further comprises:

the stability of at least one parameter used by the coriolis flowmeter is measured over a given time period before beginning a density measurement of the material having a known density.

Another aspect of the invention includes a computer product comprising:

computer code stored on a computer readable medium which when executed by a computer performs a sequence of steps comprising:

prompting the user to select a predetermined task to be completed using the coriolis flowmeter;

displaying a sequence of steps that direct the user through a process that uses the coriolis flowmeter to accomplish the predetermined task;

the coriolis flowmeter is operated in response to the sequence of steps to accomplish the predetermined task.

Preferably, the method further comprises: the predetermined task selected is to verify the coriolis flow meter using a prover.

Preferably, the method further comprises: the predetermined task selected is to linearize the coriolis flow meter using information from two test runs at two different flow rates.

Another aspect of the invention includes a coriolis flow meter system comprising:

a coriolis flowmeter;

a computer system coupled to the coriolis flowmeter, comprising a display;

means for instructing the user to perform a sequence of steps that instructs the user to perform a process that uses the coriolis flowmeter to accomplish the predetermined task.

Drawings

FIG. 1A is a block diagram of a checker at the beginning of a measurement cycle;

FIG. 1B is a block diagram of the checker at time T1 in the measurement cycle;

FIG. 1C is a block diagram of the checker at time T2 in the measurement cycle;

FIG. 2 is a block diagram of a system in an exemplary embodiment of the invention;

FIG. 3 is a flow chart illustrating the steps of verifying the meter calibration factor using a fluid having a known density in an exemplary embodiment of the invention;

FIG. 4 is a flow chart illustrating steps for establishing all parameters for a proving operation in the Coriolis flowmeter using a Gulu module in an exemplary embodiment of the present invention;

FIG. 5 is a graph of indicated flow rate versus actual flow rate for two different test runs.

Detailed Description

Fig. 2-5 and the following description illustrate specific examples to teach those skilled in the art how to make and use the best mode of the invention. Certain conventional aspects have been simplified or omitted for purposes of illustrating the inventive principles. Those skilled in the art will recognize from these examples variations 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 invention is not limited to the specific examples described below, but is defined by the claims and their equivalents.

Fig. 2 is a block diagram of a system 200 in an exemplary embodiment of the invention. The system 200 has a flow meter 204, a flow meter control module 202, a flow meter guru module 208, persistent storage 210, and a display 212. In one embodiment, the flow meter is a coriolis flow meter. The flow meter control module 202 is coupled to the flow meter 204 via a link 206. The flow meter control module 202 is configured to communicate with a flow meter guru module 208, persistent storage 210, and a display 212. The flow meter control module 202 may be implemented as a hardware/software combination or may be implemented as software running on a computer, for example, running on a PC. The flow meter guru module 208 is configured to communicate with the display 212, the flow meter control module 202, and the persistent storage 210. The flowmeter gulu module 208 may be implemented as a hardware/software combination or may be implemented as software running on a computer. The flow meter guru module 208 and the flow meter control module 202 may run on the same computer or may operate on two separate computers configured to communicate with each other. When the flow meter guru module 208 and the flow meter control module 202 operate on the same computer, they may be two separate programs, or they may be two modules of the same program.

In operation, the flow meter control module 202 monitors and controls the flow meter 204. The flow meter control module 202 has access to and can set various operating parameters of the flow meter 204, such as vibration modes, damping factors, user output signal types, calibration factors, and the like. Typically, setting the operating parameters in the flow meter control module for proper operation of the flow meter 204 requires some familiarity with the operation of the flow meter. Requiring an unskilled user to operate a flow meter using the flow meter control module 202 to perform calibration verification may confuse the user and result in a calibration that does not properly verify the meter. The flow meter guru module 208 communicates with the flow meter control module 202 and can operate in accordance with its startup. The flow meter guru module 208 is configured to guide a user through a sequence of steps that enables the user to use the flow meter to complete a task. In an exemplary embodiment of the invention, there is a flow meter guru module for each task. The user may select the corresponding flow meter guru module for the task the user wishes to accomplish. Once selected, the flowmeter gulu module guides the user through the steps required to perform the task. In another embodiment, there may be only one flow meter guru module that enables the user to select one task from a plurality of valid tasks. One of the effective tasks of using the meter guru module is to validate the meter calibration factor using materials with well known densities.

FIG. 3 is a flow chart illustrating the steps of using a fluid verification meter calibration factor having a known density in an exemplary embodiment of the invention. At step 302, the user is prompted to select a material having a known density. Once the user has selected the material, the user is prompted to select the desired accuracy at step 304. The density deviation amount (DD) is calculated in step 306. At step 308, the user is instructed to begin flowing a material having a known density through the flow meter. At step 310, the flow meter will measure the density of the material flowing through the meter. Once the density has been measured, an incremental difference, Δ D, between the measured density and the known density is calculated (312). This Δ D is compared to the Density Deviation (DD). When the Δ D is greater than or equal to DD, the user is then alerted that an error condition exists (314). When the Δ D is less than DD, the test data is stored and the user is informed of the successful verification of the meter calibration factor (316). In an alternative embodiment, the user is instructed at step 308 to simply fill the flow meter with material for measurement, rather than flow the material through the flow meter during the measurement.

In one embodiment of the invention, the user may select a material from a list of possible materials presented to the user. The presentation of the list of materials may be accomplished using any known User Interface (UI) technique, such as a drop down menu, a list of radio buttons, and the like. In one embodiment, the list of materials includes water, Liquefied Natural Gas (LNG), and Compressed Natural Gas (CNG). In another embodiment, the user may enter the name of the material to be used, or may enter the density of the material. In some cases, when the user chooses to use a gas as the fluid material, the density of the gas will be limited to between 0.0 and 0.60 g/cc. When a gas has been selected, the user may be prompted to enter the operating temperature and pressure to be used during the flow.

In one exemplary embodiment of the invention, the user will be prompted to select a percentage accuracy of the worst case limit of mass flow measurement through the flow meter. The selection may be done according to a number of options or may be entered by the user. Some coriolis flowmeters exhibit a 0.06% change in mass flow measurement for every 0.001g/cc change between the known density and the measured density. Using this relationship between flow measurement and density measurement, the user-selected accuracy can be translated into a control point for density measurement. For example, assume that the meter needs to be verified to be better than 0.3% for flow measurement. The user would select 0.3%. The allowable difference between the measured density and the known density is the density deviation (dd). The density deviation is calculated according to equation 1:

equation 1

Where dd is the density deviation and RA is the required accuracy. For the above example requiring 0.3% accuracy, the density deviation would be plus or minus 0.005 g/cc.

Once the preliminary information has been entered into the system, the user will be instructed to begin flowing material through the flow meter. In one embodiment of the invention, once material flow is initiated, a predetermined time stability check may be performed on the primary variables used in the calibration verification. In one exemplary embodiment, variables are tracked during a 1 minute window to ensure that they stabilize within 2 sigma confidence levels. Variables and their stability windows may include: density within ± 0.001g/cc, charged null within 2 × zero stability of the meter, temperature within ± 0.25 degrees celsius, drive gain within 5%, flow within 5%, etc.

If any of the primary variables are outside their stability range, the user should be notified, for example, by a graphical display. In one exemplary embodiment, the verification check is not started until after the stability check has been successfully completed.

The next step is the measurement phase. In an exemplary embodiment of the invention, the measurement of the flow meter is performed for a period of time, for example 5 minutes. At this stage, a progress indicator may be displayed to update the status of the measurement to the user. During this measurement phase, a number of parameters from the flow meter will be monitored. The measurement results may be stored in a non-volatile storage area, such as a hard disk. The monitored parameters may include: flow rate, indicated density, temperature, drive gain, pressure (if useful), tube frequency, etc. Once the measurement phase has been completed, the user may be instructed to stop flowing the material through the flow meter.

An incremental difference between the known density of the material and the density measured by the flow meter is calculated. The incremental difference is compared to the density deviation (dd). If the delta difference is greater than or equal to the density deviation, the meter calibration verification fails and the user is notified of the error condition. If the delta difference is less than the density deviation, then the calibration factor for the flow meter has been validated. In one embodiment of the invention, the test data may be stored to a non-volatile storage device for later use.

In an exemplary embodiment of the invention, the measurement data will be used to track the calibration of the flow meter over time. The first time the calibration factor of the flow meter is checked, this data is used as a baseline for the flow meter. This means that if the meter passes the validation check, the delta difference will be stored and used in subsequent tests to normalize the new delta difference. By storing the data from each validation test, the performance of the flow meter can be tracked over time.

In another exemplary embodiment of the invention, the selected task will assist the user in using the tester to test the meter. Fig. 4 is a flow chart illustrating steps for establishing all parameters for a proving operation in the coriolis flow meter using a guru module in an exemplary embodiment of the invention. The user is prompted at step 402 to enter information about the test runs to be performed, such as the type of tester used, the volume of each test run, the flow rate to be used, the pre-test volume, the flow rate cell (mass or volume), etc. At step 404, the guru module uses this information in a coriolis flowmeter configured for the pretest operation. The pre-test volume and the test volume are used in conjunction with the flow rate to determine the pre-test time and the test time. These times are then used to help determine frequency output, damping rate, signal processing speed, etc. For example, a signal processing delay (one component of damping) must be set such that it is a fraction of the pre-test time so that the flow measurement becomes stable before the test begins. The processor speed must be set fast enough so that signal processing delays and communication delays are part of the pre-test time and the verification run time. Setting processor speed is also a compromise between the steady state response of the meter and the transient response of the meter. The meter response time must also be set as part of the pre-test time so that the meter measurements have stabilized during the pre-test time. The processor speed will be set at the lowest possible speed that still meets the delay criteria and response time criteria. The frequency output must be set so that the output does not go out of range for high flow rates and has sufficient resolution at low flow rates.

Once the meter parameters have been set, the guru unit may optionally adjust/initiate the test run and update the meter calibration factor with the results from the test run at step 406. During the inspection run, the guru module works in coordination with the flow meter control module and can perform flow and signal stability checks. For example, the guru module tracks the measured flow rate during the pre-test time and between the start and end signals of the test run. The maximum and minimum flow rates and the mean and standard deviation will be determined. The results may be compared to API criteria and the user notified if the criteria are not met.

Once the verification run has been completed, the guru module can be used to check the repeatability of the meter calibration factor. In one exemplary embodiment, this repeatable step is an additional optional step included in the guru module of fig. 4. In another exemplary embodiment, the repeatability check may be a separate independent task. For this repeatable task, the guru module receives results from the inspection run (this flow error). The user may enter the results, or the guru module may receive the results directly from the prover or from the flow meter control module. The desired accuracy can also be input into the google module. Using this information, the guru module will determine the number of inspection runs that must be completed for the desired repeatability. The google module may optionally adjust/initiate the inspection run and monitor the results of the run to confirm that the desired repeatability has been achieved.

In another exemplary embodiment of the invention, the selected task is to linearize the coriolis flow meter using results from at least two test runs at different flow rates. In one embodiment, the test results from two or more inspection runs are input by a userThe data of the line is either loaded from a permanent memory, e.g. from a file. In another embodiment, the guru module helps the user to set up and perform different inspection runs. When building the verification run, the linearized guru module may call the verification guru module described above, or may incorporate verification module coding into the linearized guru module. The coriolis Flow Calibration Factor (FCF) and the zero offset of the meter can be determined using a comparison of the indicated flow rate to the actual flow rate for two or more different test runs at two different flow rates. FIG. 5 is a graph of indicated flow rate versus actual flow rate for two different test runs. For the first run, the indicated flow rate was 10 lb/min, with an actual flow rate of 8.70 lb/min. The second run had an indicated flow rate of 100 lb/min and an actual flow rate of 96.15 lb/min. The meter used an initial FCF of 47.4 with a zero offset of 5 ns. The new FCF is the slope of the original FCF divided by the line drawn, or FCF_n＝FCF_oSlope of the signal. The new Zero offset is equal to the Zero intercept of the plot divided by the initial FCF plus the initial Zero offset, or Zero_nArbitrary ratio (intercept/FCF)_o)+Zer_o. The table intercept has units of lb/min and the FCF has units of grams/sec/μ sec, thus including some unit conversions. Using the two flow rates plotted in fig. 5, the new FCF was 46.06132 ═ 47.4/1.0290631. The new zero offset is 172.724ns ═ (1.0516252/47.4) (7559.872 units transition) + 5.

Claims

1. A method for using a coriolis flow meter system, comprising:

selecting a predetermined task to be accomplished using a coriolis flow meter, wherein the predetermined task is a verification of a flow calibration factor of the coriolis flow meter;

it is characterized in that the preparation method is characterized in that,

prompting a user to select a material having a known density (302);

prompting a user to select a desired accuracy for the coriolis flowmeter (304);

determining a density deviation from the known density corresponding to the desired accuracy (306);

directing a user to introduce the material into the coriolis flowmeter (308);

measuring a density of the material using the coriolis flowmeter (310);

comparing the measured density to a known density; and

when the measured density differs from the known density by more than the density deviation, the user is alerted that an error condition exists.

2. The method of claim 1, wherein selecting the predetermined task is accomplished by initiating a boot module (208) corresponding to the predetermined task.

3. The method of claim 1, wherein selecting the predetermined task is accomplished by selecting the predetermined task from a plurality of predetermined tasks in a guidance module (208).

4. The method of claim 1, wherein the density of the material is measured for at least 5 minutes.

5. The method of claim 1, wherein the user is prompted to select a material having a known density from a plurality of displayed materials.

6. The method of claim 5, wherein water is one of the plurality of displayed materials.

7. The method of claim 1, wherein the relationship between the desired accuracy and the density deviation is

Wherein: DD is a deviation of the density,

RA is the required precision.

8. The method of claim 1, wherein the measured density is stored using a non-volatile medium.

9. The method of claim 8, further comprising:

periodically repeating the density measurement of the material of known density and comparing the results of the new measurement to the stored density measurement data.

10. The method of claim 1, further comprising:

the stability of at least one parameter used by the coriolis flowmeter is measured over a given time period before beginning a density measurement on a material having a known density.

11. The method of claim 10, wherein the at least one parameter is selected from the group consisting of: density, charged null, temperature, drive gain, and flow.

12. A method for using a coriolis flow meter system comprising the steps of:

selecting a predetermined task to be accomplished using a coriolis flow meter, wherein the predetermined task is linearizing the coriolis flow meter using information from two test runs at two different flow rates;

prompting the user to input data from two inspection runs;

calculating a new coriolis flow calibration and a new zero offset using data from the two test runs; and

the coriolis flow calibration and the zero point offset are updated.

13. The method of claim 12, further comprising the step of:

adjusting the test of the meter using a tester at two different flow rates;

calculating a new coriolis flow calibration and a new zero offset using data from the two test runs;

the coriolis flow calibration and the zero point offset are updated.

14. A coriolis flow meter system comprising:

a coriolis flow meter (204);

a computer system coupled to the coriolis flowmeter, comprising a display;

a coriolis control module (202) running on the computer system, wherein the coriolis control module is configured to control the coriolis flow meter;

a coriolis guidance module (208) running on the computer system configured to communicate with the coriolis control module; and

the coriolis guidance module is configured to display a sequence of steps that guide a user through a process that uses the coriolis flow meter to accomplish a predetermined task.

15. The coriolis flow meter system of claim 14 wherein said sequence of steps comprises:

prompting a user to input inspection operation information;

configuring the coriolis flow meter for a test run using the input test run information; and

the operation of the coriolis flow meter is adjusted during the test run.

16. The coriolis flowmeter system of claim 14 wherein the series of steps comprises:

the coriolis flow calibration and the zero point offset are updated.

17. The coriolis flow meter system of claim 14 wherein said sequence of steps comprises:

prompting a user to select a material having a known density;

directing the user to flow the material through a coriolis flow meter;

measuring a density of the material using the coriolis flowmeter;

comparing the measured density to a known density; and

18. The coriolis flow meter system of claim 17 wherein said steps further comprise:

prompting a user to select a desired accuracy for the coriolis flowmeter;

determining a density deviation from a known density corresponding to the desired accuracy; and

setting the predetermined amount equal to the density deviation.

19. The coriolis flowmeter system of claim 18 wherein said relationship between said desired accuracy and said density deviation is

Wherein: DD is the density variation,

RA is the required precision.

20. The coriolis flow meter system of claim 17 wherein said steps further comprise:

stability of at least one parameter used by a coriolis flowmeter is measured over a given time period before beginning a density measurement on a material having a known density.

21. The coriolis flow meter system of claim 20 wherein said at least one parameter is selected from the group consisting of: density, charged null, temperature, drive gain, and flow.