Method of correcting flow meter variable

Abstract

A method of correcting a flow variable (509) based on an internal pressure within a Coriolis flowmeter (202) includes the steps of receiving a first external pressure (503) measured with a first pressure sensor (204) located in a first process conduit (208a) positioned at a first end (212a) of the Coriolis flowmeter (202); determining a second external pressure (505) in a second process conduit (208b) positioned at a second end (212b) of the Coriolis flowmeter (202) opposite the first end (212a); determining an estimated internal flowmeter pressure (507) based on the first external pressure (503) and the second external pressure (505); receiving the flow variable (509); and generating a corrected flow variable (512) based on the estimated internal flowmeter pressure (507), a pressure compensation factor (510), and the flow variable (509).

Description

TECHNICAL FIELD

[0001] The implementations described below relate to methods of correcting measured Coriolis flowmeter variables, and more specifically, to correcting measured Coriolis flowmeter variables for effects on the measurements caused by changes in internal pressure. BACKGROUND

[0002] Coriolis flowmeters can be used to measure mass flow rate, density, volume flow rate, and other information of a process fluid.

[0003] Figure 1 An example Coriolis flowmeter 100 is depicted that includes a meter assembly 10 and meter electronics 20. The meter assembly 10 responds to changes in process fluid flow. The meter electronics 20 are connected to the meter assembly 10 via leads 102 and provide density, volume flow rate, and mass flow rate information, among other information, to an operator through a meter electronics interface 26.

[0004] The meter assembly 10 includes manifolds 150 and 150', flanges 103 and 103', parallel flow tubes 130 and 130', a driver 180, and velocity pickoff sensors 170L and 170R. The flow tubes 130 and 130' are curved at two symmetric locations along their lengths and are substantially parallel throughout their lengths. Struts 140 and 140' serve to define the axis about which each flow tube oscillates.

[0005] When the flanges 103 and 103' are connected to process piping (not shown) via inlet and outlet ends 104 and 104', process fluid enters the inlet end 104 of the meter through the flange 103 and is directed through the manifold 150. The manifold 150 divides and routes the process fluid through the flow tubes 130 and 130'. Upon exiting the flow tubes 130 and 130', the process fluid is recombined into a single stream by the manifold 150' and routed to the outlet end 104' connected to process piping (not shown) via the flange 103'.

[0006] Both flow tubes 130 and 130' are driven in opposite directions by the driver 180 in a first out-of-phase bending mode of the flowmeter. The driver 180 can include any of a number of well-known arrangements, for example, a magnet is mounted to the flow tube 130' and a reaction coil is mounted to the flow tube 130, and an alternating current is passed through the reaction coil to vibrate the flow tubes. The meter electronics 20 apply the appropriate drive voltage to the driver 180.

[0007] The meter electronics 20 provide drive signals to the driver 180 through leads 102 to vibrate the flow tubes 130 and 130'. The meter electronics 20 receive left and right velocity signals from the velocity pick-off sensors 170L and 170R through leads 102 to calculate mass flow rate, volume flow rate, and / or density information of the flow through the meter assembly 10.

[0008] In some flow meter applications, such as in oil and gas production, high accuracy of the meter is required. However, different internal line pressures can correspond to different flow tube stiffnesses, and flow tube stiffness affects the sensitivity to Coriolis forces as well as the natural frequency of the flow meter flow tubes. Thus, some Coriolis meter designs exhibit bias in flow and / or density measurements due to the effect of internal line pressure on the vibration characteristics of the meter flow tubes.

[0009] Because the walls of the flow tubes are often thin to achieve the required sensitivity for flow and density measurements, it is not feasible to include pressure taps to measure the pressure within the flow tubes. Therefore, some operators of prior art meters provide pressure measurement taps external to the flow meter to measure the pressure of the process fluid in the connected process conduit. Typically, the operators position these pressure taps upstream of the flow meter to avoid viscous drag. Alternatively, some operators assume a fixed line pressure based on reasonable experience and knowledge of the process control, as it will affect the line pressure in the system.

[0010] With the measured upstream line pressure or the assumed line pressure, prior art meters apply a pressure compensation factor to the flow meter measurements based on the externally measured pressure to correct for changes in meter stiffness. The pressure compensation factor is determined via type testing at the factory, which represents the ratio of line pressure to the required measurement correction for stiffness changes due to pressure. Typically, the pressure compensation factor is either a specific factor for the particular model of flow meter or a general factor determined for all meters having similar sizes and designs.

[0011] However, there can be a significant difference in pressure outside the flow meter and inside the flow tube of the flow meter. Even if the pressure difference between the external pressure tap and the flow tube is precisely known at one point in time, additional uncertainty in the pressure difference can occur, resulting in additional flow variable measurement error. For example, Bernoulli effects on the fluid can cause the pressure inside the flow tube of the flow meter to increase or decrease relative to the pressure outside the flow meter if the cross-sectional area and velocity inside the flow tube and outside the flow tube in the process conduit are different. The pressure difference between the external pressure tap and the flow tube of the flow meter can also change after a type test, for example, due to the buildup of coating inside the flow meter. Increasing the flow through the flow meter can cause additional pressure loss between the pressure tap and the inside of the flow tube. Increasing the viscosity of the process fluid in the test can cause additional pressure loss between the pressure tap and the inside of the flow tube. These pressure differences between the inside of the flow tube and outside of the flow meter can introduce error in the flow meter measurement.

[0012] In some cases, the installation conditions do not allow the pressure tap to be installed on the same side of the meter as the pressure tap position during the calibration type test (i.e., upstream or downstream). In this case, there will be additional uncertainty in the flow meter measurement because the pressure used to correct for changes in flow tube stiffness will not be as precisely known. This problem also applies to bidirectional flow installations where the position of the pressure tap alternates upstream or downstream as the flow direction alternates forward and backward through the flow meter.

[0013] There is a need for a more precise way to correct flow meter measurements for stiffness changes resulting from internal pressure changes. SUMMARY

[0014] In a first embodiment, a method of correcting a flow variable based on internal pressure within a Coriolis flow meter is provided. The method includes a step of receiving a first external pressure measured with a first pressure sensor located in a first process conduit positioned at a first end of the Coriolis flow meter. The method also includes a step of determining a second external pressure in a second process conduit positioned at a second end of the Coriolis flow meter opposite the first end. The method also includes a step of determining an estimated internal flow meter pressure based on the first external pressure and the second external pressure. The method also includes a step of receiving a flow variable. The method also includes a step of generating a corrected flow variable based on the estimated internal flow meter pressure, a pressure compensation factor, and the flow variable.

[0015] In a second embodiment, an electronic device for correcting a flow variable based on an internal pressure within a Coriolis flowmeter is provided. The electronic device includes an interface to receive a first external pressure from a first pressure sensor and a processing system in communication with the interface, wherein the processing system is configured to: receive a first external pressure measured with a first pressure sensor positioned in a first process conduit positioned at a first end of the Coriolis flowmeter; determine a second external pressure in a second process conduit positioned at a second end of the Coriolis flowmeter opposite the first end; determine an estimated internal flowmeter pressure based on the first external pressure and the second external pressure; receive a flow variable; and generate a corrected flow variable based on the estimated internal flowmeter pressure, a pressure compensation factor, and the flow variable.

[0016] In a third embodiment, a flowmeter correction system configured to correct a flow variable based on an internal pressure within a Coriolis flowmeter. The system includes a first pressure receiving module configured to receive a first external pressure from a first pressure sensor positioned in a first process conduit positioned at a first end of the Coriolis flowmeter; a second pressure receiving module to determine a second external pressure in a second process conduit positioned at a second end of the Coriolis flowmeter opposite the first end; an internal flowmeter pressure estimation module configured to determine an estimated internal flowmeter pressure based on the first external pressure and the second external pressure; a flow variable receiving module configured to receive a flow variable; and a flow variable correction module configured to generate a corrected flow variable based on the estimated internal flowmeter pressure, a pressure compensation factor, and the flow variable.

[0017] Various aspects

[0018] According to another aspect, the second external pressure can be determined based on a pressure loss coefficient, a fluid velocity, a fluid viscosity, and a density.

[0019] According to another aspect, determining the second external pressure can further include receiving a second external pressure measurement from a second pressure sensor positioned in the second process conduit.

[0020] According to another aspect, determining the estimated internal flowmeter pressure based on the first external pressure and the second external pressure can further include averaging the first external pressure and the second external pressure.

[0021] According to another aspect, the estimated internal pressure can be determined further based on a cross-sectional area of the process conduit, a diameter of the process conduit, a cross-sectional area of a flow tube of the Coriolis flowmeter, a measured density p, and a measured flow rate M.

[0022] According to another aspect, the pressure compensation factor can be related to a pressure inside the flow tube.

[0023] According to another aspect, the flow variable can be at least one of: mass flow, volume flow, or density.

[0024] According to another aspect, the estimated internal flow meter pressure can also be determined based on a flow meter orientation.

[0025] According to another aspect, the processing system can also be configured to determine the second external pressure based on a pressure loss coefficient, a fluid velocity, a fluid viscosity, and a density.

[0026] According to another aspect, the processing system can also be configured to determine the second external pressure by receiving a second external pressure measurement from a second pressure sensor located in a second process conduit.

[0027] According to another aspect, the processing system can also be configured to determine the estimated internal flow meter pressure based on the first external pressure and the second external pressure by averaging the first external pressure and the second external pressure.

[0028] According to another aspect, the processing system can also be configured to determine the estimated internal pressure based on a cross-sectional area of the process conduit, a diameter of the process conduit, a cross-sectional area of a flow tube of the Coriolis flow meter, a measured density p, and a measured flow rate M.

[0029] According to another aspect, the pressure compensation factor can be related to a pressure inside the flow tube.

[0030] According to another aspect, the flow variable can be at least one of: mass flow, volume flow, or density.

[0031] According to another aspect, the estimated internal flow meter pressure can also be determined based on a flow meter orientation.

[0032] According to another aspect, the second pressure receiving module can also be configured to determine the second external pressure based on a pressure loss coefficient, a fluid velocity, a fluid viscosity, and a density.

[0033] According to another aspect, the second pressure receiving module can also be configured to receive a second external pressure measurement from a second pressure sensor located in a second process conduit.

[0034] According to another aspect, the internal flow meter pressure estimation module can also be configured to average the first external pressure and the second external pressure.

[0035] According to another aspect, the internal flow meter pressure estimation module can also be configured to determine the estimated internal pressure based on a cross-sectional area of the process conduit, a diameter of the process conduit, a cross-sectional area of a flow tube of the Coriolis flow meter, a measured density p, and a measured flow rate M.

[0036] According to another aspect, the pressure compensation factor can be related to a pressure inside the flow tube.

[0037] According to another aspect, the flow variable can be at least one of: a mass flow, a volume flow, or a density.

[0038] According to another aspect, the internal flow meter pressure estimation module can be further configured to determine the estimated internal flow meter pressure based on a flow meter orientation. BRIEF DESCRIPTION OF DRAWINGS

[0039] In all of the drawings, like reference numerals refer to like elements throughout. It is understood that the drawings are not necessarily drawn to scale.

[0040] Figure 1 A flow meter 100 according to an embodiment is depicted;

[0041] Figure 2 A flow meter system 200 according to an embodiment is depicted;

[0042] Figure 3 A method 300 according to an embodiment is depicted;

[0043] Figure 4 An electronic device 400 according to an embodiment is depicted; and

[0044] Figure 5 A system 500 according to an embodiment is depicted. DETAILED DESCRIPTION

[0045] Figures 2 to 5 The following description describes specific examples to teach those skilled in the art how to make and use the best mode of the application. The examples can have been simplified for the sake of educational purposes. The skilled artisan will appreciate variations from these examples that fall within the scope of the present application. Those skilled in the art will appreciate that the features described below can be combined in various ways to form many of the various modifications of the application. As a result, the application is not limited to the specific examples described below, but only by the claims and their equivalents.

[0046] Figure 2 A flow meter system 200 according to an embodiment is depicted. The flow meter system 200 can be used to correct a flow variable based on an internal pressure within a Coriolis flow meter. The flow meter system 200 can include a Coriolis flow meter 202, a first pressure sensor 204, a first process conduit 208a, a second process conduit 208b, and an electronic device 210.

[0047] In embodiments, the Coriolis flowmeter 202 can be similar to the Coriolis flowmeter sensor 100. However, in further embodiments, the Coriolis flowmeter 202 sensor can include different configurations. For example, as will be appreciated by those skilled in the art, the Coriolis flowmeter 202 can include one or more straight or curved flow tubes.

[0048] In Figure 2 embodiments, the process fluid enters the Coriolis flowmeter 202 via a first process conduit 208a and exits the Coriolis flowmeter 202 via a second process conduit 208b. In the depicted embodiment, the first process conduit 208a is associated with a fluid inlet at a first end 212a of the Coriolis flowmeter 202 and the second process conduit 208b is associated with a fluid outlet at a second end 212b of the Coriolis flowmeter 202. However, this is not intended to be limiting. In embodiments, the second process conduit 208b and the second end 212b can be associated with an inlet. In further embodiments, the flowmeter system 200 can be bidirectional, which means that each of the first end 212a and the second end 212b can alternately be used as an inlet or an outlet.

[0049] In embodiments, the first pressure sensor 204 can include any type of sensor, including but not limited to a resistive, capacitive, piezoelectric, optical, or MEMS pressure sensor or transducer.

[0050] In embodiments, the flowmeter system 200 can also include an electronics device 210. The electronics device 210 can be used to correct a flow variable based on the internal pressure within the Coriolis flowmeter 202. In embodiments, the electronics device 210 can provide the corrected flow variable to an operator.

[0051] The electronics device 210 is in communication with the first pressure sensor 204 and the meter electronics 20 or meter assembly 10 associated with the Coriolis flowmeter 202. In further embodiments, the electronics device 210 can also be in communication with the second pressure sensor 206. In embodiments, the electronics device 210 can provide an additional interface to provide the corrected flow variable information to an operator.

[0052] In embodiments, the flowmeter system 200 can include both the electronics device 210 and the meter electronics 20 associated with the Coriolis flowmeter 202. Alternatively, the electronics device 210 can include the only electronics device for the flowmeter system 200, which means that the electronics device 210 also provides the functionality described above with respect to the meter electronics 20 for the Coriolis flowmeter 202.

[0053] In further embodiments, the flow meter system 200 can include a second pressure sensor 206. The second pressure sensor 206 can be the same type as the first pressure sensor 204, or a different type than the first pressure sensor 204.

[0054] Figure 3 A method 300 according to embodiments is depicted. The method 300 can be used to correct a flow variable based on an internal pressure within a Coriolis flow meter. In embodiments, the method 300 can be performed by the electronic device 210. In embodiments, the flow variable can include at least one of a mass flow, a volume flow, or a density measurement.

[0055] The method 300 begins at step 302. In step 302, a first external pressure measured with a first pressure sensor positioned in a first process conduit positioned at a first end of a Coriolis flow meter is received. For example, a signal indicative of a pressure of a process fluid in the first process conduit 208a positioned at the first end 212a can be received from the first pressure sensor 204.

[0056] The method 300 continues with step 304. In step 304, a second external pressure in a second process conduit positioned at a second end of the Coriolis flow meter opposite the first end is determined.

[0057] In embodiments, the second external pressure can be determined based on one or more pressure loss coefficients characteristic of the meter in addition to fluid velocity, density, and viscosity. The physical reasons for the pressure drop experienced by a viscous fluid as it passes through a length of conduit are described in several classic introductions to fluid mechanics textbooks. The one or more pressure loss coefficients characterize the pressure loss through at least a portion of the Coriolis flow meter, such as the Coriolis flow meter 202. In embodiments, the one or more pressure loss coefficients can include one or more predetermined values measured at the factory or determined based on a computational model. In embodiments, the one or more pressure loss coefficients can represent losses due to pipe friction and / or physical features of the flow meter, such as the manifolds 150, 150', the flanges 103, 103', bends in the flow tubes 130, 130', or any other physical features known to one of skill in the art. The fluid velocity can be determined based on the mass flow rate and the density measured with the Coriolis flow meter 202 and the cross-sectional area of the flow tubes 130, 130'. With the pressure loss coefficients and the fluid velocity, the second external pressure can be determined using the Darcy-Weisbach equation or any other method known to one of skill in the art.

[0058] In implementations, the fluid viscosity can be measured externally to the flowmeter system 200 and communicated to the electronics 210, or the fluid viscosity can be input by an operator based on a known process fluid. The density can be measured by the Coriolis flowmeter 202.

[0059] In further implementations, determining the second external pressure can include receiving a second external pressure measurement located in the second process conduit. For example, in implementations of the flowmeter system 200 including the second pressure sensor 206, the second pressure sensor 206 can be used to determine the second external pressure.

[0060] The method 300 continues with step 306. In step 306, an estimated internal flowmeter pressure is determined based on the first external pressure and the second external pressure.

[0061] In implementations, determining the estimated internal flowmeter pressure includes averaging the first external pressure and the second external pressure. For example, the estimated internal flowmeter pressure P inner_1A :

[0062]

[0063] In Equation 1A, P upstream may include the first external pressure, and P downstream may include the second external pressure. Δp represents a pressure loss between the first external pressure and the second external pressure, which in implementations can include a pressure loss across the Coriolis flowmeter 202 or a pressure loss across the Coriolis flowmeter 202 and a portion of the first process conduit 208a and the second process conduit 208b.

[0064] In further implementations, determining the estimated internal flowmeter pressure based on the first external pressure and the second external pressure can further include accounting for Bernoulli effects in the estimated internal flowmeter pressure. Accounting for Bernoulli effects in the estimated internal flowmeter pressure can further include determining the estimated internal pressure based on a cross-sectional area of the process conduit, a diameter of the process conduit, a cross-sectional area of a flow tube of the Coriolis flowmeter, a measured density p, and a measured mass flow rate M.

[0065] In implementations, the estimated internal flowmeter pressure P inner_1 may include the estimated internal flowmeter pressure P inner_1A described in Equation 1A, or the estimated internal flowmeter pressure P inner_1B described in Equation 1B below, can be further corrected using Equation 2 to provide a further estimated internal flowmeter pressure P inner_2 :

[0066]

[0067] In Equation 2, P inner_2 represents the estimated pressure in flow tube 130, 130' after correction for Bernoulli effects, p represents the density of the process fluid as measured by Coriolis flowmeter 202, v pipe represents the velocity of the process fluid in first process conduit 208a where first pressure sensor 204 is located, and v meter represents the velocity of the process fluid in flow tube 130, 130'. Equation 3 provides the velocity v pipe

[0068]

[0069] In Equation 3, M is the mass flow rate as measured by Coriolis flowmeter 202, A pipe is the cross-sectional area of first process conduit 208a, and d is the diameter of first process conduit 208a. Equation 4 provides the velocity v meter

[0070]

[0071] In Equation 4, A meter is the combined cross-sectional area of flow tubes 130, 130' of Coriolis flowmeter 202.

[0072] In embodiments, estimated internal flowmeter pressure P inner_1 and further estimated internal flowmeter pressure P inner_2 may enable more accurate correction of flowmeter variables for changes in meter stiffness.

[0073] In embodiments of flowmeter system 200, Coriolis flowmeter 202 can support installation of both: second pressure sensor 206 downstream in second process conduit 208b; and meter for bidirectional flow measurement, such that pressure sensors 204 and / or 206 will alternate being upstream or downstream as the flow direction alternates between forward and reverse. Thus, estimated internal flowmeter pressure can also be determined based on flowmeter direction. In further embodiments of step 306, P upstream may include pressure inside second process conduit 208b, and P downstream may include pressure inside first process conduit 208a. In such embodiments where only one pressure transmitter is available and that pressure transmitter is located in the downstream position only, Equation 1A can take an alternative form:​​

[0074]

[0075] Method 300 continues with step 308. In step 308, a flow variable is received. In embodiments, the flow variable can include a density, mass flow, or volume flow of the process fluid measured with the Coriolis flowmeter 202. In embodiments, the flow variable can be received from the meter electronics 20 associated with the Coriolis flowmeter 202, can be read from an electronic storage device of the electronics 210, or can be determined using raw pickoff sensor data received from the meter assembly 10 of the Coriolis flowmeter 202.

[0076] Method 300 continues with step 310. In step 310, a corrected flow variable is generated based on the estimated internal flowmeter pressure, the pressure compensation factor, and the flow variable. The corrected flow variable represents the measured flow variable corrected for pressure variations in the flow tube.

[0077] The pressure compensation factor relates the pressure within the flowmeter to a measurement correction for flow tube stiffness variations. In embodiments, the pressure compensation factor can be determined during type testing at the flowmeter factory. The pressure compensation factor can be related to a particular model of flowmeter, a series of flowmeter models including similar sizes and designs, or an individual flowmeter.

[0078] In embodiments, the corrected flow variable can be determined by multiplying the internal flowmeter pressure by the pressure compensation factor. For example, Equation 5 can be used:

[0079] X corrected = X measured + (P inner - P baseline ) * K, (Equation 5)

[0080] where X corrected is the corrected flow variable, X measured is the measured flow variable, P inner is the estimated internal flowmeter pressure, corresponding to P inner_1 or P inner_2 described above, P baselie is the pressure recorded as the internal pressure at the last calibration of the flowmeter according to a reference standard, and K is the pressure compensation factor.

[0081] In embodiments, the pressure compensation factor K can be related to the pressure inside the flow tube during type testing. This can provide improved correction for pressure on the flow variable compared to prior art methods that use a pressure compensation factor K related to the location of the first pressure sensor 204.

[0082] Figure 4 An electronic device 400 according to an embodiment is depicted. The electronic device 400 includes a processing system 402, a storage system 404, and an interface 406. The electronic device 400 can be used to correct a flow variable based on an internal pressure within a Coriolis flowmeter.

[0083] The processing system 402 can be configured to execute computer instructions that, when executed on the electronic device 400, perform some or all of the methods described with respect to Figure 3 and Figure 5 In an embodiment, the processing system 402 can include a single or any number of processors as would be understood by one skilled in the art.

[0084] The storage system 404 can be an electronically or computer readable medium configured to store computer program instructions. In an example, the storage system 404 can include a non-transitory medium. The stored computer program instructions, when executed on the processing system 402, can perform some or all of the methods described with respect to Figure 3 and Figure 5

[0085] In an example, the processing system 402 and the storage system 404 can be incorporated into a custom chipset, such as a system on a chip.

[0086] In an example, some of the methods described with respect to Figure 3 and Figure 5 may be stored or executed externally to the electronic device 400. For example, some of the methods described with respect to Figures 3 to 5 may be stored or executed on a combination of servers and cloud storage facilities via the internet.

[0087] The interface 406 can be configured to communicate with devices external to the electronic device 400. Through the interface 406, the electronic device 400 can communicate with the first pressure sensor 204. The interface 406 can also communicate with the meter electronics 20 internal to the Coriolis flowmeter 202 or an external control room computer.

[0088] In an embodiment, the electronic device 400 can include the meter electronics 20. However, in further embodiments, the electronic device 400 can include a separate electronic device that communicates with the meter electronics 20.

[0089] Figure 5 A flowmeter correction system 500 according to an embodiment is depicted. The flowmeter correction system 500 can be used to correct a flow variable based on an internal pressure within a Coriolis flowmeter 202 within a flowmeter system 200.

[0090] ​The flow meter correction system 500 includes a first pressure receiving module 502. The first pressure receiving module 502 is configured to receive a first external pressure 503 from the first pressure sensor 204 positioned in the first process conduit 208a at the first end 212a of the Coriolis flow meter 202. In embodiments, the pressure receiving module 502 can perform step 302 of the method 300 as described above.

[0091] The flow meter correction system 500 also includes a second pressure receiving module 504. The second pressure receiving module 504 is configured to determine a second external pressure 505 in the second process conduit 208b positioned at the second end 212b of the Coriolis flow meter 202 opposite the first end 212a. In embodiments, the second pressure receiving module 504 can perform step 304 of the method 300 as described above.

[0092] The flow meter correction system 500 also includes an internal flow meter pressure estimation module 506. The internal flow meter pressure estimation module 506 is configured to determine an estimated internal flow meter pressure 507 based on the first external pressure 503 and the second external pressure 505. In embodiments, the internal flow meter pressure estimation module 506 can perform step 306 of the method 300 or any of the above described variations thereof.

[0093] The flow meter correction system 500 also includes a flow variable receiving module 508. The flow variable receiving module 508 is configured to receive a flow variable 509. In embodiments, the flow variable receiving module 508 can perform step 308 of the method 300 as described above.

[0094] The flow meter correction system 500 also includes a flow variable correction module 511. The flow variable correction module 511 is configured to generate a corrected flow variable 512 based on the estimated internal flow meter pressure 507, the pressure compensation factor 510, and the flow variable 509. In embodiments, the flow variable correction module 511 can perform step 310 as described above.

[0095] The detailed description of the above implementation is not a comprehensive description of all implementations that are contemplated by the inventors. Rather, certain elements of the above implementation can be used differently, or eliminated entirely, to create additional implementations that fall within the scope and teachings of the specification. As such, the scope of the above-described implementation should be determined by the appended claims.

Claims

1. A method of correcting a flow variable (509) based on an internal pressure within a Coriolis flowmeter (202), the method comprising: receiving a first external pressure (503) measured with a first pressure sensor (204) located in a first process conduit (208a) positioned at a first end (212a) of the Coriolis flowmeter (202); determining a second external pressure (505) in a second process conduit (208b) positioned at a second end (212b) of the Coriolis flowmeter (202) opposite the first end (212a); determining an estimated internal flowmeter pressure (507) based on the first external pressure (503) and the second external pressure (505); receiving the flow variable (509); and generating a corrected flow variable (512) based on the estimated internal flowmeter pressure (507), a pressure compensation factor (510), and the flow variable (509), wherein the pressure compensation factor relates to a pressure within the Coriolis flowmeter during a type test of the Coriolis flowmeter such that the pressure compensation factor is independent of a location of the first pressure sensor.

2. The method of claim 1, wherein, Determining the second external pressure (505) is based on a pressure loss coefficient, a fluid velocity, a fluid viscosity, and a density.

3. The method of claim 1, wherein, Determining the second external pressure (505) further comprises receiving a second external pressure measurement from a second pressure sensor (206) located in the second process conduit (208b).

4. The method of any one of claims 1 to 3, wherein, Determining the estimated internal flowmeter pressure (507) based on the first external pressure (503) and the second external pressure (505) further comprises averaging the first external pressure (503) and the second external pressure (505).

5. The method of any one of claims 1 to 3, wherein, Determining the estimated internal flowmeter pressure is further based on a cross-sectional area of a process conduit, a diameter of the process conduit, a cross-sectional area of a flow tube of the Coriolis flowmeter (202), a measured density p, and a measured flow rate M.

6. The method of any one of claims 1 to 3, wherein, The flow variable (509) is at least one of: a mass flow, a volume flow, or a density.

7. The method of any one of claims 1 to 3, wherein, Determining the estimated internal flowmeter pressure (507) is further based on a flowmeter orientation.

8. An electronic device for correcting a flow variable (509) based on an internal pressure within a Coriolis flowmeter (202), the electronic device comprising an interface for receiving a first external pressure (503) from a first pressure sensor (204) and a processing system in communication with the interface, wherein, The processing system is configured to: receive a first external pressure (503) measured with a first pressure sensor (204) located in a first process conduit (208a) positioned at a first end (212a) of the Coriolis flowmeter (202); determine a second external pressure (505) in a second process conduit (208b) positioned at a second end (212b) of the Coriolis flowmeter (202) opposite the first end (212a); determine an estimated internal flowmeter pressure (507) based on the first external pressure (503) and the second external pressure (505); receive the flow variable (509); and generate a corrected flow variable (512) based on the estimated internal flowmeter pressure (507), a pressure compensation factor (510), and the flow variable (509), wherein the pressure compensation factor relates to a pressure within the Coriolis flowmeter during a type test of the Coriolis flowmeter such that the pressure compensation factor is independent of a location of the first pressure sensor. generate a corrected flow variable (512) based on the estimated internal flow meter pressure (507), a pressure compensation factor (510), and the flow variable (509), wherein the pressure compensation factor is related to a pressure within the Coriolis flow meter during a type test of the Coriolis flow meter such that the pressure compensation factor is independent of a location of the first pressure sensor.

9. The electronic device of claim 8, wherein, The processing system is further configured to determine the second external pressure (505) based on a pressure loss coefficient, a fluid velocity, a fluid viscosity, and a density.

10. The electronic device of claim 8, wherein, The processing system is further configured to determine the second external pressure (505) by receiving a second external pressure measurement from a second pressure sensor (206) located in a second process conduit (208b).

11. The electronic device of any of claims 8 to 10, wherein, The processing system is further configured to determine the estimated internal flow meter pressure (507) based on the first external pressure (503) and the second external pressure (505) by averaging the first external pressure (503) and the second external pressure (505).

12. The electronic device of any of claims 8-10, wherein, The processing system is further configured to determine the estimated internal flow meter pressure based on a cross-sectional area of a process conduit, a diameter of the process conduit, a cross-sectional area of a flow tube of the Coriolis flow meter, a measured density p, and a measured flow rate M.

13. The electronic device of any of claims 8-10, wherein, The flow variable (509) is at least one of: a mass flow, a volume flow, or a density.

14. The electronic device of any of claims 8-10, wherein, The estimated internal flow meter pressure (507) is further determined based on a flow meter orientation.

15. A flow meter correction system configured to correct a flow variable (509) based on an internal pressure within a Coriolis flow meter (202), the flow meter correction system comprising: a first pressure receiving module configured to receive a first external pressure (503) from a first pressure sensor (204) located in a first process conduit (208a) positioned at a first end (212a) of the Coriolis flow meter (202); a second pressure receiving module for determining a second external pressure (505) in a second process conduit (208b) positioned at a second end (212b) of the Coriolis flow meter (202) opposite the first end (212a); an internal flow meter pressure estimation module configured to determine an estimated internal flow meter pressure (507) based on the first external pressure (503) and the second external pressure (505); a flow variable receiving module configured to receive a flow variable (509); and a flow variable correction module configured to generate a corrected flow variable (512) based on the estimated internal flow meter pressure (507), a pressure compensation factor (510), and the flow variable (509), wherein the pressure compensation factor is related to a pressure within the Coriolis flow meter during a type test of the Coriolis flow meter such that the pressure compensation factor is independent of a location of the first pressure sensor.

16. The flow meter correction system of claim 15, wherein, The second pressure receiving module is further configured to determine the second external pressure based on a pressure loss coefficient, a fluid velocity, a fluid viscosity, and a density (505).

17. The flow meter correction system of claim 15, wherein, The second pressure receiving module is further configured to receive a second external pressure measurement from a second pressure sensor (206) located in the second process conduit (208b).

18. The flow meter correction system of any one of claims 15-17, wherein, The internal flow meter pressure estimation module is further configured to average the first external pressure (503) and the second external pressure (505).

19. The flow meter correction system of any one of claims 15-17, wherein, The internal flow meter pressure estimation module is further configured to determine the estimated internal flow meter pressure based on a cross-sectional area of a process conduit, a diameter of the process conduit, a cross-sectional area of a flow tube of the Coriolis flow meter (202), a measured density p, and a measured flow rate M.

20. The flow meter correction system of any one of claims 15-17, wherein, The flow variable (509) is at least one of: a mass flow, a volume flow, or a density.

21. The flow meter correction system of any one of claims 15-17, wherein, The internal flow meter pressure estimation module is further configured to determine the estimated internal flow meter pressure based on a flow meter orientation (507). The internal flow meter pressure estimation module is further configured to determine the estimated internal flow meter pressure based on a flow meter orientation (507).

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