阅读说明：本技术 确定计量仪组件中的流体的蒸汽压力 (Determining vapor pressure of fluid in meter assembly ) 是由 霍埃尔·魏因施泰因 大卫·马丁内斯·莫雷特 于 2019-04-03 设计创作，主要内容包括：提供了用于确定流体的蒸汽压力的振动计量仪(5)。振动计量仪(5)包括：具有流体的计量仪组件(10)；以及可通信地耦接至计量仪组件(10)的计量仪电子装置(20)。振动计量仪(5)被配置成基于计量仪组件(10)中的流体的静态压力来确定计量仪组件(10)中的流体的蒸汽压力。(A vibrating meter (5) for determining the vapour pressure of a fluid is provided. The vibrating meter (5) includes: a meter assembly (10) having a fluid; and meter electronics (20) communicatively coupled to the meter assembly (10). The vibrating meter (5) is configured to determine a vapor pressure of the fluid in the meter assembly (10) based on a static pressure of the fluid in the meter assembly (10).)

1. A vibrating meter (5) for determining a vapor pressure of a fluid, the vibrating meter (5) comprising:

a meter assembly (10) having a fluid; and

meter electronics (20) communicatively coupled to the meter assembly (10), the meter electronics (20) configured to:

determining a vapor pressure of the fluid in the meter assembly (10) based on a static pressure of the fluid in the meter assembly (10).

2. The vibrating meter (5) of claim 1, wherein the meter electronics (20) being configured to determine the vapor pressure of fluid in the meter assembly (10) based on the static pressure of fluid in the meter assembly (10) comprises: the meter electronics (20) is configured to:

changing the static pressure of fluid in the meter assembly (10) until a fluid phase change is detected; and is

Determining the static pressure of fluid in the meter assembly (10).

3. The vibrating meter (5) of claim 2, wherein the static pressure of fluid in the meter assembly (10) changes due to at least one of a change in height and a change in fluid velocity of fluid in the meter assembly (10).

4. The vibrating meter (5) according to any one of the preceding claims 1 to 3, wherein:

the meter assembly (10) is configured to vibrate and provide a sensor signal resulting from the vibration; and is

The meter electronics (20) is also configured to detect vapor in the meter assembly (10) based on the sensor signal.

5. The vibrating meter (5) of any of the preceding claims 1-4, wherein the meter electronics (20) is further configured to determine the vapor pressure of the fluid in the meter assembly (10) based on a phase change of the fluid in the meter assembly (10) being detected.

6. The vibrating meter (5) according to any of the preceding claims 1-5, wherein the static pressure of fluid in the meter assembly (10) is determined based on at least one of an inlet pressure and an outlet pressure of fluid.

7. The vibrating meter (5) according to any of the preceding claims 1-6, wherein the static pressure of the fluid in the meter assembly (10) is determined by calculating a static pressure change of the meter assembly (10) based on a cross-sectional area change of the meter assembly (10).

8. The vibrating meter (5) of any of the preceding claims 1-7, wherein the meter electronics (20) is further configured to communicate with one or more of a pump (510) and a flow control device (540) to change the static pressure of fluid in the meter assembly (10).

9. The vibrating meter (5) of any of the preceding claims 1-8, wherein the meter electronics (20) is further configured to communicate with at least one of an inlet pressure sensor (520) and an outlet pressure sensor (530) to determine the static pressure of fluid in the meter assembly (10).

10. A method for determining a vapor pressure of a fluid, the method comprising:

providing a fluid to a meter assembly; and

determining a vapor pressure of the fluid in the meter assembly based on a static pressure of the fluid in the meter assembly.

11. The method of claim 10, wherein determining the vapor pressure of fluid in the meter assembly based on the static pressure of fluid in the meter assembly comprises:

changing the static pressure of fluid in the meter assembly until a fluid phase change is detected; and

determining the static pressure of fluid in the meter assembly.

12. The method of claim 11, wherein the static pressure of fluid in the meter assembly is varied by at least one of varying a height of fluid in the meter assembly and varying a fluid velocity.

13. The method of any preceding claim 10 to 12, further comprising:

vibrating a portion of the meter assembly and providing a sensor signal resulting from the vibration; and

detecting steam in the meter assembly based on the sensor signal.

14. The method of any preceding claim 10 to 13, further comprising: determining the vapor pressure of the fluid in the meter assembly based on the phase change of the fluid in the meter assembly being detected.

15. The method of any preceding claim 10 to 14, wherein the static pressure of fluid in the meter assembly is determined based on at least one of an inlet pressure and an outlet pressure of fluid.

16. The method of any preceding claim 10 to 15, wherein determining the static pressure of fluid in the meter assembly comprises: calculating a static pressure change of the meter component based on a change in cross-sectional area of the meter component.

17. The method of any preceding claim 10 to 16, further comprising: meter electronics are used to communicate with one or more of a pump and a flow control device to change the static pressure of fluid in the meter assembly.

18. The method of any of the preceding claims 10-17, further using meter electronics to communicate with at least one of an inlet pressure sensor and an outlet pressure sensor to determine the static pressure of fluid in the meter assembly.

Technical Field

The embodiments described below relate to determining vapor pressure, and more particularly, vapor pressure of a fluid in a meter assembly.

Background

Vibrating sensors, such as vibrating densitometers and coriolis flow meters, are generally known and are used to measure mass flow and other information of a material flowing through a conduit in the flow meter. Exemplary coriolis flow meters are disclosed in U.S. patent 4,109,524, U.S. patent 4,491,025, and Re 31,450 (all owned by j.e. smith et al). These flow meters have one or more conduits in a straight or curved configuration. Each conduit configuration in a coriolis mass flowmeter, for example, has a set of natural vibration modes, which may be simple bending, torsional, or coupled types. Each conduit may be driven to oscillate in a preferred mode.

The material flows into the flow meter from a connecting conduit on the inlet side of the flow meter, is directed through a conduit, 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 no flow is passing through the flowmeter, the driving force applied to the conduit causes all points along the conduit to oscillate with the same phase or a small "zero offset" (which is a time delay measured at zero flow). As material begins to flow through the meter, coriolis forces cause each point along the conduit to have a different phase. For example, the phase at the inlet end of the flow meter lags the phase at the centralized driver location, while the phase at the outlet leads the phase at the centralized driver location. The pick-up on the conduit produces a sinusoidal signal representative of the motion of the conduit. The signals output from the pickups are processed to determine the time delay between pickups. The time delay between two or more pickups is proportional to the mass flow rate of material flowing through the conduit.

Meter electronics connected to the driver generates drive signals for operating the driver and determines the mass flow rate and other properties of the material from the signals received from the pickups. 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 delivered to the drive coil for vibrating the conduit at a desired flow tube amplitude and frequency. It is also known in the art to provide the pick-up as a magnet and coil arrangement very similar to the driver arrangement. However, when the driver receives a current that causes motion, the pickup may use the motion provided by the driver to induce a voltage.

Vapor pressure is an important characteristic in applications dealing with the flow and storage of volatile fluids (e.g., gasoline, natural gas liquids, and liquefied petroleum gases). Vapor pressure provides an indication of how the volatile fluid may behave during processing and further indicates conditions under which bubbles may form and pressure may build. Thus, the measurement of the vapor pressure of the volatile fluid improves safety and prevents damage to the transport vessel and infrastructure. For example, if the vapor pressure of the fluid is too high, cavitation may occur during pumping and delivery operations. In addition, vessel or process line steam pressures may exceed safe levels due to temperature variations. Therefore, it is often required to know the steam pressure before storage and transportation.

Typically, vapor pressure is determined by capturing a sample and transferring it to a laboratory for testing to determine the value of the sample. This presents challenges to the implementation of regulatory fuel quality standards due to delays in obtaining end results, the cost of maintaining the laboratory, and security and legal evidence leaks associated with sample processing. Accordingly, there is a need for an in-line device or system that can continuously determine the vapor pressure of the fluid in the meter assembly in real time under process conditions. This is provided by the present embodiment and an advance in the art is achieved. The field measurement is more reliable because it avoids the need for periodic sampling and completely eliminates the risk of fluid property changes between the time of sample collection and laboratory analysis. Furthermore, security is increased by making real-time measurements, since unsafe conditions can be corrected immediately. Furthermore, money is saved because regulatory enforcement can be done by simple on-site inspection, where inspection and enforcement decisions can be made with little delay or process stoppage.

Disclosure of Invention

A vibrating meter for determining the vapor pressure of a fluid is provided. According to an embodiment, a vibratory meter comprises: a meter assembly having a fluid; and meter electronics communicably coupled to the meter assembly. The meter electronics is configured to determine a vapor pressure of the fluid in the meter assembly based on a static pressure of the fluid in the meter assembly.

A method for determining a vapor pressure of a fluid is provided. According to an embodiment, the method comprises: the method includes providing a fluid to a meter assembly, and determining a vapor pressure of the fluid in the meter assembly based on a static pressure of the fluid in the meter assembly.

Aspect(s)

According to one aspect, a vibrating meter (5) for determining a vapor pressure of a fluid comprises: a meter assembly (10) having a fluid; and meter electronics (20) communicatively coupled to the meter assembly (10), the meter electronics (20) configured to determine a vapor pressure of the fluid in the meter assembly (10) based on a static pressure of the fluid in the meter assembly (10).

Preferably, the meter electronics (20) being configured to determine the vapor pressure of the fluid in the meter assembly (10) based on the static pressure of the fluid in the meter assembly (10) comprises: the meter electronics (20) is configured to: the static pressure of the fluid in the meter assembly (10) is changed until a fluid level change is detected, and the static pressure of the fluid in the meter assembly (10) is determined.

Preferably, the static pressure of the fluid in the meter set (10) changes due to at least one of a change in the height of the fluid in the meter assembly (10) and a change in the velocity of the fluid.

Preferably, the meter assembly (10) is configured to vibrate and provide a sensor signal resulting from the vibration, and the meter electronics (20) is further configured to detect vapor in the meter assembly (10) based on the sensor signal.

Preferably, the meter electronics (20) is further configured to detect a change in phase of the fluid in the meter assembly (10) to determine the vapor pressure of the fluid in the meter assembly (10).

Preferably, the static pressure of the fluid in the meter assembly (10) is determined based on at least one of the inlet pressure and the outlet pressure of the fluid.

Preferably, the static pressure of the fluid in the meter assembly (10) is determined by calculating a change in the static pressure of the meter assembly (10) based on a change in the cross-sectional area of the meter assembly (10).

Preferably, the meter electronics (20) is further configured to communicate with one or more of the pump (510) and the flow control device (540) to change the static pressure of the fluid in the meter assembly (10).

Preferably, the meter electronics (20) is further configured to communicate with at least one of the inlet pressure sensor (520) and the outlet pressure sensor (530) to determine a static pressure of the fluid in the meter assembly (10).

According to one aspect, a method for determining a vapor pressure of a fluid comprises: the method includes providing a fluid to a meter assembly, and determining a vapor pressure of the fluid in the meter assembly based on a static pressure of the fluid in the meter assembly.

Preferably wherein determining the vapour pressure of the fluid in the meter assembly based on the static pressure of the fluid in the meter assembly comprises: the method includes varying a static pressure of the fluid in the meter assembly until a fluid phase change is detected, and determining the static pressure of the fluid in the meter assembly.

Preferably, the static pressure of the fluid in the meter assembly is varied by at least one of varying the height of the fluid in the meter assembly and varying the velocity of the fluid.

Preferably, the method further comprises: a portion of the meter assembly is vibrated and a sensor signal generated by the vibration is provided, and vapor in the meter assembly is detected based on the sensor signal.

Preferably, the method further comprises: a vapor pressure of the fluid in the meter assembly is determined based on the detected phase change of the fluid in the meter assembly.

Preferably wherein the static pressure of the fluid in the meter assembly is based on at least one of the inlet pressure and the outlet pressure of the fluid.

Preferably, determining the static pressure of the fluid in the meter assembly comprises: the static pressure change of the gauge assembly is calculated based on the change in the cross-sectional area of the gauge assembly.

Preferably, the method further comprises: meter electronics are used to communicate with one or more of the pump and the flow control device to change the static pressure of the fluid in the meter assembly.

Preferably, the method further comprises: meter electronics are used to communicate with at least one of the inlet pressure sensor and the outlet pressure sensor to determine a static pressure of the fluid in the meter assembly.

Drawings

Like reference symbols in the various drawings indicate like elements. It should be understood that the drawings are not necessarily to scale.

Fig. 1 shows a vibrating meter 5.

Fig. 2 is a block diagram of meter electronics 20 of the vibrating meter 5.

FIG. 3 shows a graph 300, graph 300 showing a relationship illustrating drive gain versus gas-liquid ratio that may be used to determine vapor pressure using a vapor pressure gauge factor.

Fig. 4 shows a graph 400, the graph 400 showing how the static pressure of the fluid in the vibrating meter may be used to determine the vapor pressure.

Fig. 5 shows a system 500 for determining the vapor pressure of a fluid.

Fig. 6 illustrates a method 600 of determining a vapor pressure of a fluid.

Detailed Description

Fig. 1-6 and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of implementation of determining the vapor pressure of a fluid in a meter assembly. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the specification. Those skilled in the art will appreciate variations from these examples that fall within the scope of the description. Those skilled in the art will appreciate that the features described below may be combined in various ways to form multiple variations in determining the vapor pressure of a fluid in a meter assembly. Accordingly, the embodiments described below are not limited to the specific examples described below, but only by the claims and their equivalents.

Fig. 1 shows a vibrating meter 5. As shown in fig. 1, the vibrating meter 5 includes a meter assembly 10 and meter electronics 20. The meter assembly 10 is responsive to the mass flow rate and density of the process material. The meter electronics 20 is connected to the meter assembly 10 via a wire 100 to provide density, mass flow rate, temperature information, and/or other information through the path 26.

The meter assembly 10 includes a pair of manifolds 150 and 150', flanges 103 and 103' having flange necks 110 and 110', a pair of parallel conduits 130 and 130', a driver 180, a Resistance Temperature Detector (RTD)190, and a pair of pickoff sensors 170l and 170 r. The conduits 130 and 130 'have two substantially straight inlet legs 131, 131' and outlet legs 134, 134', the inlet legs 131, 131' and outlet legs 134, 134 'converging towards each other at the conduit mounting blocks 120 and 120'. The conduits 130, 130' are curved at two symmetrical locations along their length and are substantially parallel throughout their length. Struts 140 and 140' serve to define axes W and W ' about which each conduit 130, 130' oscillates. The branches 131, 131' and 134, 134' of the conduits 130, 130' are fixedly attached to the conduit mounting blocks 120 and 120', and these mounting blocks are in turn fixedly attached to the manifolds 150 and 150 '. This provides a continuous closed material path through the meter assembly 10.

When flanges 103 and 103' having holes 102 and 102' are connected via inlet end 104 and outlet end 104' into a process line (not shown) carrying a process material being measured, the material enters the inlet end 104 of the meter through an aperture 101 in flange 103 and is directed through manifold 150 to a conduit mounting block 120 having a surface 121. Within the manifold 150, the material is separated and transported through the conduits 130, 130'. Upon exiting the conduits 130, 130', the process material is recombined into a single stream within the block 120' having the surface 121' and the manifold 150' and thereafter delivered to an outlet end 104' connected to a process line (not shown) by a flange 103' having holes 102 '.

The conduits 130, 130' are selected and suitably mounted to the conduit mounting blocks 120, 120' to have substantially the same mass distribution, moment of inertia, and young's modulus about the bending axes W-W and W ' -W ', respectively. These bending axes pass through the struts 140, 140'. Since the young's modulus of the conduit changes with temperature, and this change affects the calculation of flow and density, the RTD 190 is mounted to the conduit 130' to continuously measure the temperature of the conduit 130 '. The temperature of the conduit 130 'and thus the voltage that appears across the RTD 190 for a given current through the RTD 190 is controlled by the temperature of the material through the conduit 130'. The temperature dependent voltage appearing across the RTD 190 is used in a known manner by the meter electronics 20 to compensate for changes in the modulus of elasticity of the conduit 130, 130' due to any changes in the conduit temperature. The RTD 190 is connected to meter electronics 20 by lead 195.

Both conduits 130, 130 'are driven in opposite directions by the driver 180 about their respective bending axes W and W' and are driven in a first out of phase bending mode known as a flow meter. The driver 180 may comprise any one of a number of known arrangements, such as a magnet mounted to the guide tube 130 'and an opposing coil mounted to the guide tube 130, and through which an alternating current is passed to vibrate both guide tubes 130, 130'. Appropriate drive signals are applied by meter electronics 20 to driver 180 via wires 185.

Meter electronics 20 receives the RTD temperature signal on lead 195 and the left and right sensor signals present on lead 100 carrying left and right sensor signals 165l and 165r, respectively. The meter electronics 20 generates a drive signal that appears on the lead 185 to the driver 180 and vibrates the conduits 130, 130'. The meter electronics 20 processes the left sensor signal, the right sensor signal, and the RTD signal to calculate the mass flow rate and density of the material through the meter assembly 10. This information, along with other information, is applied as a signal by meter electronics 20 on path 26.

Mass flow rate measurements may be generated according to the following formula

The Δ t term includes an operationally derived (i.e., measured) time delay value that includes the time delay that exists between pick-off sensor signals, for example where the time delay is due to the Coriolis effect associated with the mass flow rate through the vibrating meter 5. The measured Δ t term ultimately determines the mass flow rate of the flowing material as it flows through the vibrating meter 5.Δ t₀The term includes the time delay at zero flow calibration constant. Δ t₀The items are typically determined at the factory and programmed into the vibrating meter 5. Zero flow Δ t even when the flow conditions are changing₀The time delay at the entry will not change. The flow calibration factor FCF is proportional to the stiffness of the vibrating meter 5.

Pressure in a fluid in a vibrating meter

Assuming an incompressible liquid under steady conditions, the rate of mass entering a controlled volume (e.g., a pipe) at the inletEqual to the rate at which it exits at the outletInlet mass flow rateMust equal the outlet mass flow rateIs represented by the following formula [2]]Shown. Moving from the inlet to the outlet, the mass flow rate is conserved at every point along the tube. However, the mid-section flow area between the inlet and outlet may decrease. This reduction in flow area requires an increase in the velocity of the fluid (v ≠ g) to maintain the same mass flow rateAnd obey the principle of conservation of mass.

Wherein the content of the first and second substances,

is the mass flow rate of the fluid;

v is the average fluid velocity;

ρ is the density of the fluid;

a is the total cross-sectional area;

subscript 1 represents the inlet;

subscript 3 denotes the outlet; and

the index 2 indicates the middle section between the inlet and the outlet.

Furthermore, the total pressure in the flow system is equal to the sum of both the dynamic pressure and the static pressure:

P_{general assembly}＝P_{Static state}+P_{Dynamic state}· [3]

Dynamic pressure P_{Dynamic state}Can be defined as:

wherein the terms ρ and v are defined above with respect to equation [2 ].

Assuming stable, incompressible, inviscid, no swirl, the bernoulli equation gives:

where P refers to static pressure and the term ρ gz represents the hydrostatic head due to elevation changes. More specifically, g is a gravitational constant, and z is a height. The viscous part of the pressure drop can be treated with a single loss term in the bernoulli equation.

Wherein;

f is the coefficient of friction;

l is the length of the pipe; and is

D is the diameter of the pipe.

Equation [7] below is a version of Bernoulli's equation that accounts for frictional losses associated with passing through a pipe. As the fluid passes through the pipe, the fluid dissipates energy and the pressure drops across a given length of pipe. This loss of pressure is not recoverable because the energy from the fluid has been dissipated through frictional losses. Therefore, the following equation can account for this loss:

this relationship can be applied to the above reference equation [2]]Exemplary conduits are described. As the fluid moves from the inlet to the midsection between the inlet and the outlet, the velocity changes to maintain the mass flow rate. Therefore, equation [7] is maintained]In the relation shown, the dynamic pressure ρ v²The/2 increases, resulting in a decrease in static pressure. Static pressure is restored by the same principle as fluid moves from mid-way between the inlet and outlet to the outlet. That is, moving from the middle between the inlet and the outlet to the outlet, the flow area increases; thus, the fluid velocity is reduced, resulting in a dynamic pressure reduction while restoring part of the initial static pressure. However, the static pressure at the outlet may decrease due to unrecoverable viscous losses.

This may cause the static pressure at the inlet and outlet to be greater than the vapor pressure of the fluid and the static pressure between the inlet and outlet to be less than the vapor pressure of the fluid. Thus, although the static pressure at the inlet and outlet is greater than the vapor pressure of the fluid, flashing or degassing phenomena may still occur in the piping. Further, a vibrating meter, such as a coriolis meter, may be inserted into a conduit having a diameter different from the diameter of one or more conduits in the vibrating meter. Thus, when outgassing is detected in the vibratory meter, the pressure measured in the conduit may not be the vapor pressure of the fluid in the vibratory meter.

Meter electronics-drive gain

Fig. 2 is a block diagram of meter electronics 20 of the vibrating meter 5. In operation, the vibratory meter 5 provides various measurements that can be output, including one or more of mass flow rate, volume flow rate, individual flow component mass and volume flow rate, and a measurement or average of total flow rate, including for example both volume and mass flow of individual flow components.

The vibrating meter 5 generates a vibratory response. The vibrational response is received and processed by meter electronics 20 to generate one or more fluid measurements. The value may be monitored, recorded, saved, summed, and/or output. The meter electronics 20 includes an interface 201, a processing system 203 in communication with the interface 201, and a storage system 204 in communication with the processing system 203. While these components are shown as distinct blocks, it should be understood that the meter electronics 20 can include various combinations of integrated and/or discrete components.

The interface 201 is configured to communicate with the meter assembly 10 of the vibrating meter 5. Interface 201 may be configured to couple to lead 100 (see fig. 1) and exchange signals with driver 180, pickoff sensors 170l and 170r, and RTD 190, for example. The interface 201 may also be configured to communicate with external devices, for example, via the communication path 26.

The processing system 203 may comprise any manner of processing system. The processing system 203 is configured to retrieve and execute stored routines in order to operate the vibrating meter 5. The storage system 204 may store routines including a flow meter routine 205, a valve control routine 211, a drive gain routine 213, and a steam pressure routine 215. The storage system 204 may store measured values, received values, operating values, and other information. In some embodiments, the storage system stores mass flow (m)221, density (ρ)225, density threshold 226, viscosity (μ)223, temperature (T)224, pressure 209, drive gain 306, drive gain threshold 302, gas entrainment threshold 244, gas entrainment fraction 248, and any other variable known in the art. Routines 205, 211, 213, 215 may include any noted signals and those other variables known in the art. Other measurement/processing routines are contemplated and are within the scope of the description and claims.

It is understood that more or fewer values may be stored in the storage system 204. For example, the steam pressure may be determined without using the viscosity 223. For example, the viscosity is estimated based on the pressure drop or a function related to friction as a function of flow rate. However, the viscosity 223 may be used to calculate a reynolds number, which may then be used to determine the friction factor. The reynolds number and friction factor may be employed to determine the viscous pressure drop in a conduit (e.g., conduits 130, 130' described above with reference to fig. 1). It will be appreciated that reynolds numbers may not necessarily be employed.

The flow meter routine 205 may generate and store fluid quantification and flow measurements. These values may comprise substantially instantaneous measurements, or may comprise a total or cumulative value. For example, the flow meter routine 205 may generate and store a mass flow measurement in, for example, the mass flow 221 memory of the storage system 204. The flow meter routine 205 may generate and store a density 225 measurement in, for example, a density 225 memory. As previously discussed and as is known in the art, the mass flow 221 value and the density 225 value are determined from the vibrational response. The mass flow rate and other measurements may include substantially instantaneous values, may include samples, may include averages over time intervals, or may include accumulated values over time intervals. The time interval may be selected to correspond to a period of time during which certain fluid conditions are detected, such as a fluid state of only liquid or alternatively a fluid state including liquid and entrained gas. Additionally, other mass and volumetric flows and related quantitative values are contemplated and are within the scope of the present description and claims.

The drive gain threshold 302 may be used to distinguish periods of flow, no flow, single/dual phase boundary (where a fluid phase change occurs), and gas entrained/mixed phase flow. Similarly, the density threshold 226 applied to the density reading 225 may also be used, alone or in conjunction with the drive gain 306, to differentiate gas entrained/mixed phase flow. The drive gain 306 may be used as a measure of, but is not limited to, the sensitivity of conduit vibrations of the vibrating meter 5 to the presence of fluids of different densities (e.g., liquid and gas phases).

As used herein, the term drive gain refers to a measure of the amount of power required to drive a flow tube to a specified amplitude, but any suitable definition may be employed. For example, in some embodiments, the term drive gain may refer to a current, a pickup voltage, or any measured or derived signal that drives a current indicative of the amount of power required to drive the flow conduits 130, 130' at a particular magnitude. The drive gain may be used to detect the multiphase flow by detecting the multiphase flow using characteristics of the drive gain such as noise level, standard deviation of the signal, measurements related to damping, and any other means known in the art. These metrics may be compared across the pickoff sensors 170l and 170r to detect mixed phase flow.

Detecting phase change of fluid

FIG. 3 shows a graph 300, graph 300 showing drive gain versus gas-liquid ratio that may be used to determine vapor pressure using a vapor pressure gauge factor. As shown in fig. 3, the graph 300 includes an average void fraction axis 310 and a drive gain axis 320. The average void fraction axis 310 and the drive gain axis 320 are incremented by a percentage, but any suitable units and/or ratios may be employed.

Graph 300 includes a curve 330, curve 330 being the relationship between drive gain and gas-liquid ratio for various flow rates. As shown, the gas-to-liquid ratio is the average void fraction value of curve 330, but any suitable gas-to-liquid ratio may be employed, such as gas volume fraction ("GVF") or gas entrainment fraction, and may be based on volume, cross-sectional area, or the like. It will be appreciated that the curves 330 are similar, although associated with different flow rates. Also shown is a drive gain threshold line 340 that intersects the curve 330 at about a 0.20% average void fraction, which may be a reference average void fraction 330a corresponding to 40% drive gain. Also shown is the true steam pressure drive gain 332, which is about 10%. True vapor pressure drive gain 332 corresponds to a fluid in the meter assembly having a static pressure at which a change in fluid phase occurs and a gas-to-liquid ratio of zero.

It can be seen that curve 330 varies from a drive gain of about 10% to a drive gain of about 100% over a range of average void fractions from 0.00% to about 0.60%. It will be appreciated that relatively small variations in the average void fraction result in significant variations in the drive gain. This relatively small variation may ensure that the start of steam formation may be accurately detected using the drive gain.

Although a drive gain of 40% is shown to correspond to an average void fraction of 0.20%, this correspondence may be process specific. For example, a drive gain of 40% may correspond to other average void fractions in other process fluids and conditions. Different fluids may have different vapor pressures and thus the onset of vapor formation of the fluid may occur at different flow rates. That is, a fluid having a relatively low vapor pressure will evaporate at a higher flow rate, while a fluid having a relatively high vapor pressure may evaporate at a lower flow rate.

It will also be appreciated that the drive gain threshold line 340 may be at alternative/other drive gains. However, it may be beneficial to have the drive gain at 40% to eliminate false detection of entrainment/mixing phase flow while also ensuring that the onset of steam formation is correctly detected.

Further, curve 330 employs drive gain, but other signals such as measured density, etc. may be used. The measured density may increase or decrease due to the presence of voids in the fluid. For example, the measured density may increase counterintuitively due to a relatively high frequency vibrating void in the meter due to sound speed effects. In relatively low frequency meters, the measured density may decrease because the density of the voids is less than the density of the fluid. These and other signals may be used alone or in combination to detect the presence of steam in the meter assembly.

As discussed above, the 0.20% average void fraction value may be the reference average void fraction 330a corresponding to the 40% drive gain value, which may be where the drive gain threshold line 340 intersects the drive gain axis 320. Thus, when the measured drive gain is at 40% for a fluid in a meter assembly (e.g., the meter assembly 10 described above), then the average void fraction of the fluid may be about 0.20%. A void fraction of about 0.20% may correspond to the pressure of the fluid due to the gases present in the fluid. For example, a void fraction of about 0.20% may correspond to, for example, a static pressure value.

The vapor pressure value may be associated with a vapor pressure gauge factor due to a previously determined relationship between drive gain or other signal (e.g., density) and a reference average void fraction 330a (which may be a reference gas-liquid ratio). For example, the meter assembly may be vibrated while increasing or decreasing the static pressure until a fluid phase change is detected. The steam pressure value may then be determined from the static pressure, as will be described in more detail below with reference to fig. 4. The determined steam pressure value may correspond to, for example, the static pressure at the drive gain threshold line 340. The determined steam pressure value may be adjusted by the steam pressure gauge factor to correspond to the true steam pressure drive gain 332, where the true steam pressure drive gain 332 is phased or meets a single/dual phase boundary. Thus, although the presence of gas in the fluid may be detected at a static pressure different from the true vapour pressure of the fluid, the true vapour pressure value may still be determined.

Using the reference average void fraction 330a as an example, the static pressure in the meter assembly may be reduced until the drive gain reaches 40%, indicating that the fluid in the meter assembly has an average void fraction of 0.20%. A processing system, such as processing system 203 described above, may determine that the fluid begins to vaporize at a static pressure, for example, proportionally higher than a static pressure corresponding to a 40% drive gain. For example, a true vapor pressure value may be associated with a drive gain of about 10%. It will be appreciated that due to the uncertainties involved in calculating the static pressure (e.g., errors from pressure sensors, flow rate measurement errors, etc.), the true steam pressure may be proportionally lower than the calculated static pressure associated with the 40% drive gain. In any event, the true vapor pressure corresponds to the static pressure of the fluid at which a change in fluid phase occurs but the gas-liquid ratio is zero.

Thus, the measured drive gain can be used to detect gas, but still produce a highly accurate true vapor pressure value. More specifically, at the instant when the air bleeding first occurs, the drive gain may not increase beyond the drive gain threshold line 340 for detection due to the presence of a few micro-bubbles. The dynamic pressure may be increased, for example, by a pump that continues to increase the flow rate until the static pressure drops such that the drive gain passes through the drive gain threshold line 340. Depending on the application, this calculated static pressure (e.g., uncorrected steam pressure) may be corrected (e.g., adjusted-decreased or increased) by a steam pressure gauge factor (e.g., of 1 psi) to account for delays in detecting fluid phase changes. That is, a vapor pressure gauge factor may be determined from the gain and applied to the uncorrected vapor pressure measurement to account for the difference in drive gain when gas is detected from the true vapor pressure to detect minute amounts of gas.

Referring to FIG. 3, as an example, a measured drive gain of 40% may correspond to a static pressure of the fluid in the meter assembly, i.e., for example, 1psi less than a static pressure corresponding to a drive gain associated with a true steam pressure. Thus, the vibration meter 5 or meter electronics 20 or any suitable electronics may determine the steam pressure meter factor to be 1psi and add that value to the static pressure associated with the 40% drive gain. Therefore, the vibration meter 5 can accurately detect the phase change of the fluid, and thus also accurately determine the vapor pressure of the fluid using the drive gain.

However, other means of detecting the phase change without using the driving gain may be employed. For example, the phase change may be detected by acoustic measurements, x-ray based measurements, optical measurements, and the like. Further, combinations of the above implementations are contemplated. For example, a bypass line running vertically in the circuit with acoustic and/or optical measurements for determining the vertical distribution of the location at which the gas first outgases. This height will then provide the input required to calculate the vapour pressure of the fluid in the vibrating meter 5, as explained below.

Pressure drop in a vibrating meter

Fig. 4 shows a graph 400, the graph 400 showing how the static pressure of the fluid in the vibrating meter may be used to determine the vapor pressure. As shown in fig. 4, the graph 400 includes a position axis 410 and a static pressure axis 420. The position axis 410 is not shown with any particular unit of length, but may be in inches, although any suitable unit may be used. The static pressure axis 420 is in units of pounds per square inch (psi), however any suitable unit may be used. The position axis 410 ranges from an inlet ("IN") to an outlet ("OUT") of the vibrating meter.

Thus, the position from IN to OUT may correspond to the fluid IN the meter assembly 10 shown IN FIG. 1, for example. IN this example, the region from IN to approximately a may correspond to the portion between the flange 103 to the conduit mounting block 120 IN the meter assembly 10. The region from approximately a to approximately G may correspond to the conduit 130, 130 'between the mounting blocks 120, 120'. The region from G to OUT may correspond to the portion of the meter assembly 10 from the mounting block 120 'to the flange 103'. Thus, the fluid IN the meter assembly 10 (e.g., IN locations ranging from IN to OUT) may not include, for example, fluid IN a pipe IN which the meter assembly 10 is inserted. The fluid in the meter assembly 10 may be the fluid in the conduits 130, 130'.

The graph 400 also includes a zero dynamic pressure map 430 and a dynamic pressure change map 440. The zero dynamic pressure graph 430 shows no change in dynamic pressure — assuming a linear decrease in pressure from the inlet to the outlet of the vibrating meter. The dynamic pressure variation graph 440 may represent the actual pressure in a vibrating meter inserted into a pipe, where the diameter of one or more pipes of the vibrating meter is less than the diameter of the pipe. An exemplary vibrating meter 5 is shown in fig. 1, but any suitable vibrating meter may be employed. Thus, a fluid in a meter assembly, such as the meter assembly 10 described above, may have a reduced static pressure due to an increase in dynamic pressure. Also shown is a steam pressure line 450, which steam pressure line 450 represents the steam pressure of the fluid in the vibrating meter.

The dynamic pressure variation graph 440 includes a static pressure drop section 440a, a viscous loss section 440b, and a static pressure increase section 440 c. The dynamic pressure variation graph 440 also includes a minimum static pressure 440 d. The static pressure drop section 440a may cause a corresponding increase in the dynamic pressure of that section of the vibrating meter due to the increase in fluid velocity. The viscous loss section 440b can correspond to a constant diameter portion of one or more conduits in the vibrating meter. Thus, the viscosity loss section 440b may not reflect an increase in fluid velocity, and thus may not reflect an increase in dynamic pressure. The static pressure increasing section 440c may be due to a decrease in fluid velocity, and thus the static pressure decrease during the static pressure decreasing section 440a may be recovered. The static pressure drop section 440a and the static pressure increase section 440c may be static pressure changes of the meter assembly.

The portion of the dynamic pressure variation graph 440 that is below the steam pressure line 450 (which includes the minimum static pressure 440d) may correspond to a location (e.g., from near position E to slightly after position G) where a fluid phase variation occurs in a fluid in a meter assembly, such as the meter assembly 10 described above. As can be seen in fig. 4, the minimum static pressure 440d is below the steam pressure line 450. This indicates that the dynamic pressure change map 440 may be moved upward by increasing the static pressure of the fluid in the meter assembly. However, if the static pressure increases by approximately 5psi to move the dynamic pressure variation graph 440 upward until the minimum static pressure 440d is located on the steam pressure line 450, a fluid phase change may be detected. As the static pressure increases, the gas or vapor in the fluid in the meter assembly may become liquid. Conversely, if the dynamic pressure variation map 440 is above the steam pressure line 450 and the static pressure of the fluid in the meter assembly decreases until the minimum static pressure 440d is located on the steam pressure line, the fluid phase change may be the formation of gas or steam in the fluid.

As can be seen in FIG. 4, the viscous loss section 440b decreases from a static pressure of about 68psi at position A to a static pressure of about 55psi at position G. It will be appreciated that the static pressure at location G of about 55psi is less than the steam pressure line 450, and that the steam pressure line 450 is about 58 psi. Thus, even if the static pressure at the inlet and outlet is greater than the steam pressure line 450, the fluid in the vibrating meter may still flash or out-gas.

Thus, the static pressure at the inlet and outlet does not directly correspond to the vapor pressure of the fluid. In other words, the vapor pressure of the fluid cannot be determined directly from the static pressure of the fluid in the pipe or outside the meter assembly. The static pressure in the meter assembly 10, or more particularly the conduits 130, 130', can be accurately determined, for example, by using pressure measurements at the inlet and outlet and inputting the dimensions of the vibrating meter 5 (e.g., the diameter and length of the conduits 130, 130'). However, in order to accurately determine the vapour pressure, it may be necessary to cause a phase change of the fluid in the vibrating meter 5, which may be caused by changing the static pressure of the fluid in the vibrating meter 5.

Changing the static pressure of a fluid

Fig. 5 shows a system 500 for determining the vapor pressure of a fluid. As shown in fig. 5, the system 500 is a bypass that includes a bypass inlet and a bypass outlet coupled to a conduit 501. The system 500 includes a pump 510 in fluid communication with an outlet of the vibrating meter 5 and a bypass outlet, the vibrating meter 5 being shown as a coriolis meter. The inlet pressure sensor 520 is in fluid communication with the inlet of the vibrating meter 5 and the bypass inlet. The outlet pressure sensor 530 is disposed between the outlet of the vibrating meter 5 and the pump 510, and is configured to measure the static pressure of the fluid at the outlet of the vibrating meter 5. A flow control device 540 (shown as a valve) is disposed between the bypass inlet and the inlet pressure sensor 520.

The pump 510 may be, for example, any suitable pump that can increase the velocity of the fluid in the vibrating meter 5. The pump 510 may, for example, comprise a variable frequency drive. The variable frequency drive may allow the pump 510 to control the fluid velocity of the fluid in the system 500. For example, the variable frequency drive may increase the fluid velocity of the fluid passing through the vibrating meter 5, but the fluid velocity may be increased by any suitable pump. By increasing the fluid velocity, the pump 510 may increase the dynamic pressure of the fluid in the vibrating meter 5 by increasing the fluid velocity.

Therefore, the static pressure of the fluid in the vibrating meter 5 may be reduced. As an illustration, referring to fig. 4, the pump 510 may move the dynamic pressure variation graph 440 downward. Thus, although not shown in fig. 4, the dynamic pressure variation line 440 should be higher than the steam pressure line 450, and the pump 510 may cause flashing or degassing by moving the dynamic pressure variation line 440 downward. Similarly, by moving the dynamic pressure variation diagram 440 up to or above the vapor pressure line 450, the gas or vapor in the fluid may become liquid.

Inlet pressure sensor 520 and outlet pressure sensor 530 may be any suitable pressure sensors configured to measure any pressure of a fluid. For example, the inlet pressure sensor 520 and the outlet pressure sensor 530 may measure the static pressure of the fluid in the system 500. Additionally or alternatively, inlet pressure sensor 520 and outlet pressure sensor 530 may measure the total pressure of the fluid in system 500. In one example, the dynamic pressure of the fluid may be determined by taking the difference between the total pressure and the static pressure of the fluid in the system 500 according to equation [3] above. For example, the inlet pressure sensor 520 may measure the total pressure and static pressure of the fluid near or at the inlet of the vibrating meter 5. The inlet pressure sensor 520 and/or meter electronics 20 in the vibrating meter may determine the dynamic pressure at the inlet of the vibrating meter 5.

The flow control device 540 may increase the fluid velocity of the fluid in the system 500 as the position of the flow control device 540 moves from the partially closed position to the fully open position. For example, by reducing the flow restriction of the system 500 at the inlet of the vibrating meter 5, the velocity of the fluid may be increased according to equation [2] above. This may move the dynamic pressure profile 440 downward to cause flashing or degassing. Conversely, the flow control device 540 may decrease the fluid velocity of the fluid in the system 500, thereby moving the dynamic pressure variation graph 440 upward, causing the gas or vapor to condense.

When the flow control device 540 is open, the fluid velocity will increase, but the static pressure at the inlet of the vibrating meter 5 will also increase, and vice versa. The combination of flow control device 540 and pump 510 may provide preferred processing conditions to achieve the desired lower static pressure and higher speed by partially closing flow control device 540 (e.g., to limit flow and reduce pressure downstream of flow control device 540) and increasing pump speed (e.g., increasing flow rate).

Although the static pressure of the fluid in the vibratory meter 5, or more specifically the meter assembly 10 in the vibratory meter 5, may be varied by using the pump 510 or the flow control device 540, or a combination of both, as described above, other methods of varying the static pressure may be employed. For example, the height z of the vibrating meter 5 may be changed. To reduce the static pressure of the fluid in the vibrating meter 5, the height z may be increased. To increase the static pressure of the fluid in the vibrating meter 5, the height z may be reduced. The height z of the vibrating meter 5 may be varied by any suitable means, such as a motorized lift between the vibrating meter 5 and the pipe 501 and a bellows between the vibrating meter 5, such as the flow control device 540, and the pump 510. Other devices may be employed, as well as combinations of various devices (e.g., pump 510, flow control device 540, and/or motorized lift).

For example, if the flow through the bypass is sufficient, a pump may not necessarily be employed. Only the flow control device 540 may be used. The flow control device 540 may be mounted at other locations, such as downstream of the vibrating meter 5. Alternatively, flow control device 540 may not be employed, for example, where pump 510 and/or a motorized lift are used. In another alternative example, the meter may be installed in the main line rather than the bypass. Additionally or alternatively, only a single pressure sensor may be employed. For example, only the outlet pressure sensor 530 may be employed. The inlet and/or outlet pressure sensors 520, 530 may be located at alternative locations. The outlet pressure sensor 530 and its location may be beneficial because the static pressure at the location of the outlet pressure sensor 530 may be substantially stable with respect to the fluid velocity once the fluid in the meter assembly 10 is under vapor pressure. That is, any additional increase in fluid velocity may not result in a substantial decrease in the static pressure measured by the outlet pressure sensor 530.

Determining the vapor pressure of a fluid

Fig. 6 illustrates a method 600 of determining a vapor pressure of a fluid. As shown in fig. 6, in step 610, the method 600 provides fluid to a meter assembly, such as the meter assembly 10 described above with reference to fig. 1. In step 620, the method 600 determines a vapor pressure of the fluid based on a static pressure of the fluid in the meter assembly.

During step 610, fluid may be provided to the meter assembly 10 via, for example, a branch on a pipe, such as the system 500 shown in fig. 5. As shown in fig. 5, the branch is a loop that returns fluid to the pipe 501. Alternatively, fluid may be provided to the meter assembly 10 via a check branch. For example, the bifurcation from conduit 501 shown in fig. 5 may drain into a reservoir or tank rather than returning to conduit 501. The fluid may or may not include a vapor or gas.

Step 620 may determine the vapor pressure of the fluid by, for example, varying the total or static pressure of the fluid in meter assembly 10 until a change in fluid phase is detected. For example, the static pressure of the fluid may be increased until steam is no longer detected. Instead, the static pressure may be reduced until steam is detected. The fluid phase change may be detected by any suitable means (e.g., based on a sensor signal, e.g., detecting a change in drive gain or drive signal as discussed above with reference to fig. 3).

When a change in fluid phase is detected, such as when a change in drive gain is detected, the vibrating meter 5 or electronics coupled to the vibrating meter 5 may determine the pressure at the inlet and/or outlet of the meter assembly 10. For example, referring to fig. 5, the inlet pressure sensor 520 may measure the static pressure of the fluid at the inlet of the meter assembly 10, and the outlet pressure sensor 530 may measure the static pressure of the fluid at the outlet of the meter assembly 10. Thus. The inlet static pressure and/or the outlet static pressure may be associated with a fluid phase change.

The inlet static pressure and the outlet static pressure can be used for the above equation [7]]To determine the static pressure in the gauge assembly. For example, the outlet pressure may be P₁And P is₂May be the pressure of the fluid in the meter assembly. The height-related term ρ gz may be used₁And ρ gz₂To account for variations in fluid level in a meter assembly, for example due to conduit geometry. For example, arcuate conduits such as those of the meter assembly 10 described above may have variations in height. The dynamic velocity term can be similarly solved by measuring the density and flow rate of the fluid and knowing the dimensions of the conduit and the pipes coupled to the inlet and outlet of the conduitSimilarly, a viscous pressure drop term may also be determined

Thus, the method 600 may determine the vapor pressure of the fluid in the meter assembly 10 based on the detection of the vapor. That is, the static pressure may be changed until a phase change is detected, and then the associated static pressure may be determined based on, for example, the outlet pressure. Thus, the static pressure may be a steam pressure. It will be appreciated that the change in pressure in the gauge assembly may be based on a change in cross-sectional area in the gauge assembly.

The above describes a vibrating meter 5, and in particular meter electronics 20, and a method 600 of determining a vapor pressure of a fluid in meter assembly 10 based on a static pressure of the fluid in meter assembly 10. Since the static pressure is the pressure of the fluid in the meter assembly 10, and not the static pressure of the fluid in, for example, a pipe into which the meter assembly is inserted, the determined vapor pressure may be more accurate. As a result, the operation of the vibrating meter 5 and meter electronics 20 is improved because the values provided by the vibrating meter 5 and meter electronics 20 are more accurate. More accurate measurements in the field of vapor pressure measurement techniques may improve other technical fields, such as fluid process control, etc.

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

Thus, although specific embodiments have been described herein for illustrative purposes, various equivalent modifications are possible within the scope of the specification, as those skilled in the relevant art will recognize. The teachings provided herein may be applied to other methods, apparatuses, electronics, systems, etc. for determining vapor pressure of a fluid, not just to the embodiments described above and shown in the figures. Accordingly, the scope of the above-described embodiments should be determined by the appended claims.