Determination of vapor pressure of fluid in measuring instrument assembly

Abstract

To provide a vibration-type measuring instrument for determining a vapor pressure of a fluid.SOLUTION: A vibration type measuring instrument 5 includes: a measuring instrument assembly 10 having a fluid; and a measuring instrument electronic apparatus 20 communicatively coupled to the measuring instrument assembly 10. The vibration-type measuring instrument 5 is configured to determine a vapor pressure of the fluid in the measuring instrument assembly 10 in accordance with a static pressure of the fluid in the measuring instrument assembly 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiments described below relate to determining vapor pressure, and more particularly, to determining the vapor pressure of a fluid within a meter assembly. [Background technology]

[0002] Vibratory sensors, such as vibratory densitometers and Coriolis flow meters, are commonly known and are used to measure mass flow rate and other information of materials flowing through a conduit of a flow meter. Exemplary Coriolis flow meters are disclosed in U.S. Pat. Nos. 4,109,524, 4,491,025, and Reissue Pat. No. 31,450, all to J.E. Smith et al. These flow meters have one or more conduits in a straight or curved configuration. For example, each conduit configuration in a Coriolis mass flowmeter has a set of natural vibration modes that may be simple bending, torsional, or coupled. Each conduit can be driven to vibrate in a preferred mode.

[0003] Material enters the flow meter through a connected pipeline at the inlet side of the meter, is conducted through a conduit, and exits the meter through the outlet side of the meter. The natural vibration modes of the vibrating system are determined, in part, by the combined mass of the conduit and the material flowing within the conduit.

[0004] When there is no flow through the flow meter, a driving force applied to the conduit causes all points along the conduit to oscillate with the same phase, or with a small "zero offset," which is the time delay measured when flow is zero. When material begins to flow through the flow 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 center driver position, while the phase at the outlet leads the phase at the center driver position. Pickoffs on the conduit generate sinusoidal signals that represent the motion of the conduit. The signals output from the pickoffs are processed to determine the time delay between the pickoffs. The time delay between two or more pickoffs determines the time delay between the points flowing through the conduit. It is proportional to the mass flow rate of the substance.

[0005] Meter electronics connected to the driver generate drive signals to operate the driver and determine mass flow rate and other properties of the material from signals received from the pickoffs. The driver can have one of many well-known configurations, but typically includes a magnet and opposing drive. Coils have found great success in the flow meter industry. An alternating current is passed through a drive coil to vibrate the conduit at the desired flow line amplitude and frequency. It is also known in the art to provide a pickoff as a magnet and coil configuration very similar to the driver configuration. However, while the driver receives the current that causes the motion, the pickoff can use the motion provided by the driver to generate a voltage.

[0006] Vapor pressure is an important property in applications involving the flow and storage of volatile fluids, such as gasoline, liquid natural gas, and liquid petroleum gas. Vapor pressure provides an indication of how a volatile fluid may behave during handling and further indicates conditions under which bubbles are likely to form and pressure buildup is likely. Therefore, measuring the vapor pressure of a volatile fluid increases safety and prevents damage to transport vessels and infrastructure. For example, if the fluid's vapor pressure is too high, cavitation may occur during pumping and transfer operations. Furthermore, the vapor pressure of a vessel or process line may increase above safe levels due to temperature changes. Therefore, knowing the vapor pressure before storage and transportation is often required.

[0007] Typically, vapor pressure is determined by capturing a sample and transporting it to a laboratory for testing to determine a value from the sample. This poses challenges for enforcing regulatory fuel quality standards due to delays in obtaining final results, laboratory maintenance costs, and safety and legal vulnerabilities associated with handling the sample. Therefore, a need exists for an in-line device or system that can determine the vapor pressure of a fluid in an instrument assembly in a continuous, real-time manner under process conditions. This is provided by the present embodiments, achieving a technological advance. On-site measurements are more reliable because they eliminate the need for periodic sampling and completely eliminate the risk of fluid properties changing between the time of sampling and the time of laboratory assay. Furthermore, real-time measurements improve safety because unsafe conditions can be immediately corrected. Furthermore, regulatory enforcement can be performed via a simple on-site inspection, saving costs and allowing investigations and enforcement decisions to be made with only minor delays or process shutdowns. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 4,109,524 [Patent Document 2] U.S. Patent No. 4,491,025 [Patent Document 3] Reissued Patent No. 31,450 Summary of the Invention

[0009] A vibratory meter for determining the vapor pressure of a fluid is provided. According to one embodiment, the vibratory meter includes a meter assembly having a fluid and meter electronics communicatively coupled to the meter assembly. The meter electronics is configured to determine the vapor pressure of the fluid in the meter assembly based on the static pressure of the fluid in the meter assembly.

[0010] A method for determining the vapor pressure of a fluid is provided, according to one embodiment, the method includes supplying the fluid to a meter assembly and determining the vapor pressure of the fluid in the meter assembly based on the static pressure of the fluid in the meter assembly. [Aspect] According to one embodiment, a vibratory meter (5) for determining the vapor pressure of a fluid comprises a meter having a fluid. The system includes a meter assembly (10) and meter electronics (20) communicatively coupled to the meter assembly (10), the meter electronics (20) configured to determine the vapor pressure of the fluid within the meter assembly (10) based on the static pressure of the fluid within the meter assembly (10).

[0011] Preferably, the meter electronics (20) 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 meter electronics (20) configured to vary the static pressure of the fluid in the meter assembly (10) until a phase change of the fluid is detected, and determine the static pressure of the fluid in the meter assembly (10).

[0012] Preferably, the static pressure of the fluid within the meter assembly (10) changes due to at least one of a change in fluid height and a change in fluid velocity within the meter assembly (10).

[0013] 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 within the meter assembly (10) based on the sensor signal.

[0014] Preferably, the meter electronics (20) is further configured to determine the vapor pressure of the fluid within the meter assembly (10) based on detecting a phase change of the fluid within the meter assembly (10).

[0015] Preferably, the static pressure of the fluid within the meter assembly (10) is equal to the ratio of the inlet pressure to the outlet pressure of the fluid. The decision is based on at least one of the following:

[0016] Preferably, the static pressure of the fluid within the meter assembly (10) is determined by calculating the change in static pressure within the meter assembly (10) based on the change in cross-sectional area within the meter assembly (10).

[0017] Preferably, the meter electronics (20) is in communication with one or more of the pump (510) and the flow control device (540) to vary the static pressure of the fluid within the meter assembly (10). It is composed of:

[0018] Preferably, the meter electronics (20) includes at least one of an inlet pressure sensor (520) and an outlet pressure sensor (530) to determine the static pressure of the fluid within the meter assembly (10). The device is further configured to communicate.

[0019] According to one aspect, a method for determining the vapor pressure of a fluid includes supplying the fluid to a meter assembly and determining the vapor pressure of the fluid in the meter assembly based on the static pressure of the fluid in the meter assembly.

[0020] Preferably, the step of determining the vapor pressure of the fluid in the meter assembly based on the static pressure of the fluid in the meter assembly includes the steps of varying the static pressure of the fluid in the meter assembly until a phase change of the fluid is detected, and determining the static pressure of the fluid in the meter assembly.

[0021] Preferably, the static pressure of the fluid within the meter assembly is varied by at least one of a change in height of the fluid within the meter assembly and a change in fluid velocity.

[0022] Preferably, the method further includes the steps of vibrating a portion of the meter assembly and providing a sensor signal resulting from the vibration, and detecting vapor within the meter assembly based on the sensor signal.

[0023] Preferably, the method further comprises determining the vapor pressure of the fluid in the meter assembly based on detecting a phase change of the fluid in the meter assembly.

[0024] Preferably, the static pressure of the fluid within the meter assembly is based on at least one of an inlet pressure and an outlet pressure of the fluid.

[0025] Preferably, determining the static pressure of the fluid within the meter assembly includes calculating a change in static pressure within the meter assembly based on a change in cross-sectional area within the meter assembly.

[0026] Preferably, the method further includes communicating with one or more of the pump and the flow controller using the meter electronics to vary the static pressure of the fluid within the meter assembly. nothing.

[0027] Preferably, the method further includes the step of communicating with at least one of the inlet pressure sensor and the outlet pressure sensor using the meter electronics to determine the static pressure of the fluid within the meter assembly. [Brief explanation of the drawings]

[0028] The same reference numbers refer to the same elements in all figures. It should be understood that the drawings are not necessarily to scale. [Figure 1] FIG. 2 is a diagram showing a vibration type meter 5. [Figure 2] FIG. 2 is a block diagram of the meter electronics 20 of the vibration meter 5. [Figure 3] 3 is a graph 300 illustrating the relationship between drive gain and gas-to-liquid ratio, which can be used to determine vapor pressure using a vapor pressure meter coefficient. [Figure 4] 4 is a graph 400 illustrating how the static pressure of a fluid in a vibratory instrument can be used to determine vapor pressure. [Figure 5] FIG. 5 illustrates a system 500 for determining the vapor pressure of a fluid. [Figure 6] FIG. 6 illustrates a method 600 for determining the vapor pressure of a fluid. DETAILED DESCRIPTION OF THE INVENTION

[0029] 1-6 and the following description provide specific examples to teach those skilled in the art how to make and use the best mode of embodiments for determining the vapor pressure of a fluid in a meter assembly. For the purpose of teaching the principles of the invention, some conventional aspects have been simplified or omitted. Those skilled in the art will recognize variations from these examples that are within the scope of the present disclosure. Those skilled in the art will recognize that the features described below can be combined in various ways to form numerous variations for determining the vapor pressure of a fluid in a meter assembly. Consequently, the embodiments described below are not limited to the specific examples described below, but are limited only by the claims and their equivalents.

[0030] FIGURE 1 illustrates a vibratory meter 5. As shown in FIGURE 1, the vibratory meter 5 includes a meter assembly 10 and meter electronics 20. The meter assembly 10 responds to the mass flow rate and density of a process material. The meter electronics 20 is connected to the meter assembly 10 by leads 100 to provide density, mass flow rate, and temperature information and / or other information via path 26.

[0031] 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 170r. Conduits 130 and 130' have two essentially straight inlet legs 131, 131' and outlet legs 134, 134' that converge toward each other at conduit mounting blocks 120 and 120'. The conduits 130, 130' are bent at two symmetrical locations along their length, The legs 131 of the conduits 130, 130' are essentially parallel throughout their lengths. Reinforcing bars 140 and 140' function to define the central axes W and W' of vibration of each conduit 130, 130'. , 131' and 134, 134' are rigidly attached to the conduit mounting blocks 120 and 120'. These blocks are then rigidly attached to manifolds 150 and 150'. This provides a continuous, closed material path through meter assembly 10.

[0032] When flanges 103 and 103', having holes 102 and 102', are connected via inlet end 104 and outlet end 104' to process piping (not shown) carrying the process material to be measured, the material enters the inlet end 104 of the instrument through orifice 101 in flange 103, passes through manifold 150, and is directed to conduit mounting block 120, having surface 121. At manifold 150, the material is split and directed through conduits 130, 130'. Exiting conduits 130, 130' The process material is then guided through a mounting block 120' having a surface 121' and a manifold 150. ', where they recombine into a single stream which is then directed to an outlet end 104' which is connected to process piping (not shown) by a flange 103' with holes 102'.

[0033] The conduits 130, 130' are selected and appropriately mounted in the conduit mounting blocks 120, 120' so as to have substantially the same mass distribution, moment of inertia, and Young's modulus about their respective bending axes W-W and W'-W', which pass through the reinforcing bars 140, 140'. Because the Young's modulus of the conduit changes with temperature and this change affects flow rate and density calculations, an RTD 190 is attached to the conduit 130' to continuously measure the temperature of the conduit 130'. The temperature of the conduit 130', and therefore the voltage appearing across the RTD 190 for a given current passing through the RTD 190, is is governed by the temperature of the material passing through the conduit 130'. The differential voltage is used in a known manner by meter electronics 20 to compensate for changes in the modulus of elasticity of conduits 130, 130' due to changes in the temperature of the conduits. and connected to the meter electronics 20.

[0034] Both conduits 130, 130 are rotated by driver 180 about their respective bending axes W and W'. The flowmeter is driven in the opposite direction, in the so-called first antiphase bending mode. The rotor 180 may be of any of a number of well-known configurations, such as a magnet attached to the conduit 130' and opposing coils attached to the conduit 130 through which an alternating current is passed to vibrate both conduits 130, 130'. The appropriate drive signal is provided by the meter electronics 20 to: It is applied to the driver 180 via lead 185 .

[0035] Meter electronics 20 receives the RTD temperature signal on lead 195 and the left and right sensor signals appearing on lead 100, which carry left and right sensor signals 165l and 165r, respectively. The meter electronics 20 processes the left and right sensor signals and the RTD signal and transmits them through the meter assembly 10. The mass flow rate and density of the material being measured are calculated. This information, along with other information, is applied by meter electronics 20 as a signal via path 26.

[0036] The measured mass flow rate m' is calculated using the formula

number

[0037] The Δt term includes an operationally derived (i.e., measured) time delay value that includes a time delay that exists between pickoff sensor signals, such as when the time delay is due to the Coriolis effect associated with mass flow rate through the vibrating meter 5. The measured Δt term ultimately determines the mass flow rate of the flow material as it flows through the vibrating meter 5. The Δt term includes a time delay at zero flow calibration constant. The Δt term is typically determined at the factory and programmed into the vibrating meter 5. The time delay term Δt0 at zero flow does not change even under changing flow conditions. The flow calibration factor FCF is proportional to the stiffness of the vibratory instrument 5.

[0038] [Fluid pressure in vibration meters] Assuming an incompressible liquid under steady-state conditions, the mass flow rate (m'1) entering a control volume (e.g., a pipe) at the inlet is equal to the mass flow rate (m'3) leaving at the outlet. This principle that the mass flow rate at the inlet (m'1) must equal the mass flow rate at the outlet (m'3) is shown by the following equation [2]: When moving from the inlet to the outlet, the mass flow Volume is conserved at each point along the pipe. However, along the way between the inlet and outlet, there may be a decrease in flow area. This decrease in flow area requires an increase in fluid velocity (vup) to maintain the same mass flow rate and obey the principle of conservation of mass.

[0039]

number

[0040] Furthermore, the total pressure in a flow system is equal to the sum of both the dynamic and static pressures.

number

[0041] Dynamic pressure P dynamic of,

number

[0042] Assuming steady, incompressible, inviscid, and irrotational flow, the Bernoulli equation states that

number

[0043]

number

[0044] The following equation [7] is the Bernoulli equation that compensates for the friction losses associated with movement through the tube: As a fluid moves through a pipe, it loses energy and pressure drops over a given length of the pipe. This loss of pressure is not recoverable because energy from the fluid has been dissipated by friction losses. Therefore, this loss is taken into account in the following equation: It is possible.

number

[0045] This relationship can be applied to the example pipe described above with respect to equation [2]. As the flow moves from the inlet to halfway between the inlet and outlet, the velocity changes to maintain the mass flow rate. Therefore, in maintaining the relationship shown in equation [7], the dynamic pressure ρv 2 / 2 rises As the fluid moves from the inlet to the outlet, the static pressure is restored by the same principle. That is, as the fluid moves from the inlet to the outlet, the flow area increases, thus slowing the fluid velocity and reducing the dynamic pressure, while some of the initial static pressure is restored. However, the static pressure at the outlet is lower due to irrecoverable viscous losses.

[0046] This can result in static pressures at the inlet and outlet that are greater than the vapor pressure of the fluid, but static pressures between the inlet and outlet that are less than the vapor pressure of the fluid. As a result, flashing or degassing can still occur within the pipe even though the static pressures at the inlet and outlet are both greater than the vapor pressure of the fluid. Furthermore, vibratory instruments such as Coriolis instruments may be used with pipes that have a diameter different from the diameter of one or more conduits in the vibratory instrument. As a result, when degassing is detected in the vibrating meter, the pressure measured in the pipeline may not be the vapor pressure of the fluid in the vibrating meter.

[0047] [Instrument Electronics - Drive Gain] 2 is a block diagram of the meter electronics 20 of the vibratory meter 5. In operation, the vibratory meter 5 measures mass flow, volumetric flow, the mass and volumetric flow rates of individual flow components, and other parameters such as It provides a variety of measurements that can be output, such as one or more of a measured or averaged total flow rate, including both volumetric and mass flow rates of the individual flow components.

[0048] The vibratory meter 5 produces a vibration response that is received and analyzed by the meter electronics 20. The values ​​are monitored, recorded, stored, summed, and processed to produce one or more fluid measurements. The meter electronics 20 includes an interface 201 and a 2, a processing system 203 in communication with the interface 201, and a storage device 202 in communication with the processing system 203. These components are shown as separate blocks. However, it should be understood that meter electronics 20 can be constructed from various combinations of integrated and / or separate components.

[0049] Interface 201 is configured to communicate with meter assembly 10 of vibratory meter 5. Interface 201 can be coupled to lead 100 (see FIG. 1 ), for example, and configured to exchange signals with driver 180, pickoff sensors 170l and 170r, and RTD 190. Additionally, interface 201 can be configured to communicate with external devices, etc., via communication path 26. The system can be configured to:

[0050] The processing system 203 may comprise any type of processing system. The processing system 203 may be configured to retrieve and execute stored routines to operate the vibratory instrument 5. The storage system 204 includes a flow meter routine 205, a valve control routine 211, a drive Routines including a dynamic gain routine 213, and a vapor pressure routine 215. The storage system 204 can store measurements, received values, working values, and other information. In some embodiments, the storage system stores mass flow rate (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 rate 248, and any other variables known in the art. Routines 205, 211, 213, and 215 can include any of the signals described above and other variables known in the art. Other measurement / processing routines are contemplated and are within the scope of this specification and the claims.

[0051] As can be appreciated, more or fewer values ​​may be stored in storage system 204. For example, the vapor pressure may be calculated without using the viscosity 223. For example, the pressure drop or estimates viscosity based on a function of friction as a function of flow rate. However, viscosity 223 can be used to calculate the Reynolds number, which can then be used to calculate friction. Using the Reynolds number and the friction coefficient, the friction coefficient can be determined by referring to Figure 1. can be used to determine the viscous pressure drop in a conduit, such as conduits 130, 130' described above. As can be appreciated, it is not necessary to use the Reynolds number.

[0052] The flow meter routine 205 can generate and store fluid quantification and flow rate measurements. These values ​​may include substantially instantaneous measurements, or may include summed or accumulated values. For example, the flow meter routines 205 may generate mass flow measurements, For example, the flow meter routine 205 may generate and store a density 225 measurement in the density 225 storage. The mass flow rate 221 and density 225 values ​​may be determined from the vibration response as previously described and known in the art. The mass flow rate and other measurements may include substantially instantaneous values, may include samples, may include average values ​​over a time interval, or may include accumulated values ​​over a time interval. The time interval may be selected to correspond to a block of time during which a particular fluid state is detected, such as, for example, a liquid-only fluid state or a fluid state including liquid and entrained gas. Additionally, other mass flow rates and volumetric flow rates and related quantifications are contemplated and are within the scope of this specification and claims.

[0053] The drive gain threshold 302 is used to distinguish between periods of flow, no flow, and monophasic / biphasic Periods of boundary (where a change of fluid phase occurs) can be distinguished from periods of gas-entrained / mixed phase flow. Similarly, a density threshold 226 applied to density readings 225 can be used separately or in conjunction with drive gain 306 to distinguish between gas-entrained / mixed phase flow. Drive gain 306 can be selected from, for example, but not limited to, Sensitivity of vibrations in conduits of vibration gauges to the presence of fluids of different densities, such as liquid and gas phases. It can be used as a measure of the degree of

[0054] As used herein, the term drive gain refers to a measure of the amount of power required to drive a flow conduit to a specified amplitude, although any suitable definition can be used. For example, in some embodiments, the term drive gain can refer to drive current, pickoff voltage, or any measured or derived signal that represents the amount of power required to drive the conduit 130, 130′ at a particular amplitude. Drive gain can be used to detect multiphase flow by utilizing characteristics of the drive gain, such as noise level, signal standard deviation, attenuation-related measurements, and any other means known in the art for detecting mixed-phase flow. These metrics can be compared between pickoff sensors 170l and 170r to detect mixed-phase flow.

[0055] [Detecting fluid phase changes] Figure 3 shows the vapor pressure meter coefficients that can be used to determine vapor pressure. 3 shows a graph 300 illustrating the relationship between gain and gas-to-liquid ratio. 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 inscribed in percentages, but may be expressed in any suitable units and / or or ratios can be used.

[0056] Graph 300 is a plot of the relationship between drive gain and gas-to-liquid ratio at various flow rates. As shown, the gas-to-liquid ratio is the average void fraction value of plot 330, although any suitable gas-to-liquid ratio, such as gas volume fraction ("GVF") or gas entrainment fraction, may be used. It can be based on size, volume, cross-sectional area, etc. As can be appreciated, plot 330 can be based on different Also, the plot 330 intersects with the reference mean void fraction 330a at about 0.20 percent, which may be the reference mean void fraction 330a corresponding to a 40% drive gain. Also shown is the threshold drive gain line 340, which is approximately 10% of the true vapor pressure drive. Also shown is gain 332. The true vapor pressure driven gain 332 corresponds to the fluid in the meter assembly having a static pressure at which the fluid phase change occurs and a gas-to-liquid ratio of zero.

[0057] As can be seen, plot 330 ranges from 0.00 percent to approximately 0.60 percent. Over a range of average void fractions, from about 10 percent drive gain to about 100 percent As can be seen, a relatively small change in the average void fraction results in a significant change in the drive gain. This relatively small change can ensure that the onset of steam formation can be accurately detected by the drive gain.

[0058] Although a 40% drive gain is shown to correspond to a 0.20 percent average void fraction, this correspondence may be process specific. For example, a 40% drive gain may correspond to other average void fractions for other process fluids and conditions. Different fluids may have different vapor pressures, and therefore the onset of vapor formation in a fluid may occur at different flow rates. That is, fluids with relatively low vapor pressures are likely to vaporize at higher flow rates, while fluids with relatively high vapor pressures may vaporize at lower flow rates.

[0059] As can also be seen, the drive gain threshold line 340 may be located at different / other drive gains. However, it may be beneficial to have a 40% drive gain to ensure that the onset of steam formation is accurately detected while eliminating false detection of entrained / mixed phase flow.

[0060] Also, plot 330 uses drive gain, but other signals such as measured density 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 counterintuitively increase due to voids in relatively high frequency vibratory meters due to sonic effects. In relatively low frequency meters, the measured density may decrease because the voids have a lower density than the fluid. These and other signals can be used alone or in combination to detect the presence of vapor in the meter assembly.

[0061] As discussed above, the average void fraction value of 0.20 percent may be the reference average void fraction 330a corresponding to a drive gain value of 40 percent, which may be where the drive gain threshold line 340 intersects the drive gain axis 320. Thus, when the drive gain measured for a fluid in an instrument assembly, such as the instrument assembly 10 described above, is 40 percent, the average void fraction of the fluid may be approximately 0.20 percent. A void fraction of approximately 0.20 percent may correspond to pressure on the fluid due to gas present in the fluid. For example, a void fraction of approximately 0.20 percent may correspond to, for example, a static pressure value.

[0062] A predetermined relationship between the drive gain or other signal, such as density, and the reference mean void fraction 330a, which may be a reference gas-to-liquid ratio, allows the vapor pressure value to be related to the vapor pressure meter coefficient. For example, the meter coefficient may be increased or decreased while the static pressure is increased until a liquid phase change is detected. The assembly can then be vibrated, as described in more detail below with reference to FIG. A vapor pressure value can be determined from the static pressure, such that the determined vapor pressure value corresponds to the static pressure at the drive gain threshold line 340, for example. The pressure value can be adjusted by the vapor pressure meter coefficient to correspond to the true vapor pressure driving gain 332, where a phase change occurs or where the single-phase / two-phase boundary is encountered. Thus, the presence of gas in a fluid may be detected at a static pressure that is different from the true vapor pressure of the fluid, yet still allow a true vapor pressure value to be determined.

[0063] Using the reference average void fraction 330a as an example, the static pressure within the meter assembly may be reduced until a drive gain of 40 percent indicates that the fluid within the meter assembly has an average void fraction of 0.20 percent. The system may determine that the fluid begins to vaporize at a static pressure proportionally higher than the static pressure corresponding to, for example, a 40 percent drive gain. For example, a true vapor pressure value may be associated with a drive gain of approximately 10%. As can be appreciated, due to uncertainties in the calculation of the static pressure (e.g., errors from the pressure sensor, flow measurement errors, etc.), the true vapor pressure may be proportionally lower than the calculated static pressure associated with a 40% drive gain. Nevertheless, the true vapor pressure corresponds to the static pressure of the fluid at which a phase change of the fluid occurs, but the vapor-to-liquid ratio is zero.

[0064] Thus, the measured drive gain can be used to detect gas and still provide a highly accurate true vapor pressure value. More specifically, at the moment when degassing first occurs and a small number of small bubbles are present, the drive gain may not increase beyond the drive gain threshold line 340 for detection. The pump continues to increase the flow rate until the static pressure drops past the threshold line 340. Depending on the application, this calculated static pressure (e.g., uncorrected vapor pressure) can be corrected (e.g., adjusted, i.e., decreased or increased) by a vapor pressure meter coefficient, e.g., 1 psi, to compensate for delays in detecting fluid phase changes. That is, a vapor pressure meter coefficient can be determined and applied to the uncorrected vapor pressure measurement as a function of drive gain to compensate for differences between the drive gain at which gas is detected and the true vapor pressure, allowing trace gases to be detected.

[0065] Referring to Figure 3 for example, a measured drive gain of 40 percent is equivalent to, for example, a true steam The static pressure of the fluid within the meter assembly may correspond to 1 psi less than the static pressure corresponding to the pressure-related drive gain. The electronics can determine that the vapor pressure meter coefficient is 1 psi and add this value to the static pressure associated with the 40 percent drive gain. As a result, the vibratory meter 5 measures the phase change of the fluid. can be accurately detected and therefore the drive gain can be used to accurately determine the vapor pressure of the fluid as well.

[0066] However, other means of detecting phase changes that do not use drive gain may be employed. For example, phase changes may be detected by acoustic measurements, X-ray-based measurements, optical measurements, etc. Combinations of the above embodiments are also conceivable. For example, in a bypass line running vertically in a loop, vertically distributed acoustic and / or optical measurements determine where the gas first degasses. This height is then measured in the vibratory instrument 5, as explained below. provides the input needed to calculate the vapor pressure of the fluid.

[0067] [Pressure drop in vibrating instruments] Figure 4 shows how the static pressure of a fluid in a vibratory instrument can be used to determine vapor pressure. As shown in FIG. 4, the graph 400 illustrates the position of The axis of position 410 and the axis of hydrostatic pressure 420 are not shown in any particular units of length. may be in inches, however any suitable units may be used. The static pressure axis 420 is in units of pounds per square inch (psi), although any suitable units may be used. The position axis 410 ranges from the inlet ("IN") to the outlet ("OUT") of the vibratory instrument.

[0068] Thus, the location from IN to OUT can correspond to the fluid in, for example, the meter assembly 10 shown in Figure 1. In this example, the area from IN to approximately A corresponds to the fluid in the meter assembly. The area from approximately A to approximately G may correspond to the portion of the meter assembly 10 between the flange 103 and the conduit mounting block 120. The area from approximately A to approximately G may correspond to the conduits 130, 130' between the mounting blocks 120, 120'. The area from G to OUT may correspond to the portion of the meter assembly 10 from the mounting block 120' to the flange 103'. Thus, fluid within the meter assembly 10 (e.g., at a location ranging from IN to OUT) may flow through, for example, the meter assembly 10. The fluid in the meter assembly 10 may not include the fluid in the pipeline into which the assembly 10 is inserted. The fluid in the meter assembly 10 may be the fluid in the conduits 130, 130'.

[0069] Additionally, graph 400 includes a plot 430 of zero dynamic pressure and a plot 440 of dynamic pressure change. The zero dynamic pressure plot 430 shows no change in dynamic pressure; pressure remains constant from the inlet to the outlet of the vibratory instrument. The dynamic pressure change plot 440 is assumed to decrease linearly. The line 450 may represent the actual pressure in the vibrating meter, where the diameter of the conduit in the vibrating meter is smaller than the diameter of the pipeline. While an exemplary vibrating meter 5 is shown in FIG. 1 , any suitable vibrating meter may be used. Thus, the 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 vapor pressure line 450 representing the vapor pressure of the fluid in the vibrating meter.

[0070] The dynamic pressure change plot 440 includes a static pressure drop portion 440a, a viscous loss portion 440b, and a static pressure increase portion 440c. Additionally, the dynamic pressure change plot 440 also includes a minimum static pressure 440d. The static pressure drop portion 440a is The viscous loss portion 440b may be due to an increase in fluid velocity, causing a corresponding increase in dynamic pressure in this portion of the vibrating meter. The viscous loss portion 440b may correspond to a constant diameter portion of the conduit in the vibrating meter. Therefore, the viscous loss portion 440b may not reflect an increase in fluid velocity, and therefore may not reflect an increase in dynamic pressure. The static pressure increase portion 440c may be due to a decrease in fluid velocity, and thus may restore the static pressure drop in the static pressure drop portion 440a. The static pressure drop portion 440a and the static pressure increase portion 440c may be static pressure changes in the meter assembly.

[0071] The portion of dynamic pressure change plot 440 that is below vapor pressure line 450, including minimum static pressure 440d, can correspond to the location where a fluid phase change occurs in a fluid within a meter assembly, such as meter assembly 10 described above (e.g., from approximately position E to slightly after position G). As can be seen in FIG. 4, minimum static pressure 440d is below vapor pressure line 450. This is because dynamic pressure change plot 440 shifts upward by increasing the static pressure of the fluid within the meter assembly. However, the minimum static pressure 440d is located on the vapor pressure line 450. If the static pressure is increased by about 5 psi, which shifts the dynamic pressure change plot 440 upward, the fluid A phase change can be detected. Because static pressure increases, a gas or vapor in the fluid within the meter assembly may become a liquid. Conversely, if the dynamic pressure change plot 440 is above the vapor pressure line 450 and the static pressure of the fluid within the meter assembly decreases until the minimum static pressure 440d is located on the vapor pressure line, the fluid phase change may be the formation of a gas or vapor in the fluid.

[0072] 4, viscous loss section 440b drops from a static pressure of about 68 psi at location A to a static pressure of about 55 psi at location G. As can be seen, the static pressure of about 55 psi at location G is This is less than the vapor pressure line 450, which is about 58 psi. As a result, even if the static pressure at the inlet and outlet is greater than the vapor pressure line 450, the fluid in the vibrating meter will still flash or can be degassed.

[0073] Therefore, 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 may not be directly determined from the static pressure of the fluid in the pipeline or external to the meter assembly. The static pressure in the meter assembly 10, and more specifically in the conduits 130, 130′, can be determined using, for example, pressure measurements at the inlet and outlet of the vibratory meter 5. It can be accurately determined by inputting the dimensions (e.g., diameter and length of the conduits 130, 130'). However, in order to accurately determine the vapor pressure, It may be necessary to cause a phase change of the fluid, which may be caused by the static pressure of the fluid in the vibratory instrument 5. can be caused by changing

[0074] [Varying the static pressure of the fluid] FIG. 5 illustrates a system 500 for determining the vapor pressure of a fluid. As shown in FIG. In particular, system 500 is a bypass including a bypass inlet and a bypass outlet coupled to pipeline 501. System 500 includes a pump 510 in communication with the outlet and bypass outlet of vibratory instrument 5, shown as a Coriolis instrument. An inlet pressure sensor 520 measures the inlet pressure of vibratory instrument 5. The vibratory meter 5 is in fluid communication with the inlet and the bypass inlet. An outlet pressure sensor 530 is disposed between the outlet of the vibratory meter 5 and the pump 510 and is configured to measure the static pressure of the fluid at the outlet of the vibratory meter 5. A flow control device 540, shown as a valve, is disposed between the bypass inlet and the inlet pressure sensor 520.

[0075] Pump 510 may be, for example, any suitable pump capable of increasing the velocity of a fluid within vibratory instrument 5. Pump 510 may include, for example, a variable frequency drive. The variable frequency drive can allow the pump 510 to control the flow rate of the fluid in the system 500. For example, the variable frequency drive can be used to control the flow rate of the fluid through the vibratory instrument 5. The fluid velocity can be increased, which may be achieved by any suitable pump. Increasing the fluid velocity allows the pump 510 to increase the dynamic pressure of the fluid within the vibratory instrument 5 by increasing the fluid velocity.

[0076] Therefore, the static pressure of the fluid within the vibratory instrument 5 may decrease. By way of example, and referring to FIG. 4, the pump 510 may shift the dynamic pressure change plot 440 downward. Thus, although not shown in FIG. 4, if the dynamic pressure change plot 440 is above the vapor pressure line 450, In this case, pump 510 can cause flashing or degassing by shifting dynamic pressure change plot 440 downward. Similarly, the release of gases or vapors in the fluid can be achieved by shifting dynamic pressure change plot 440 up to or above vapor pressure line 450. Qi can become a liquid.

[0077] The inlet pressure sensor 520 and the outlet pressure sensor 530 may be any suitable pressure sensors configured to measure any pressure of a fluid. The pressure sensor 530 can measure the static pressure of the fluid within the system 500. Additionally or alternatively, the inlet pressure sensor 520 and the outlet pressure sensor 530 can measure the static pressure of the fluid within the system 500. The total pressure of the fluid may be measured. In one example, the dynamic pressure of the fluid may be calculated according to equation [3] above: It may be determined by taking the difference between the total pressure and the static pressure of the fluid in the system 500. For example, the inlet pressure sensor 520 can measure the total pressure and static pressure of the fluid near or at the inlet of the vibratory instrument 5. The inlet pressure sensor 520 and / or the meter electronics 20 of the vibratory instrument 5 can determine the dynamic pressure at the inlet of the vibratory instrument 5.

[0078] The flow control device 540 can increase the flow velocity of the fluid within the system 500 when the position of the flow control device 540 transitions from a partially closed position to a fully open position. By decreasing the flow restriction of the system 500 at the inlet of the meter 5, the velocity of the fluid can be increased according to equation [2] above. This can be done to induce flashing or degassing. Conversely, flow controller 540 can shift dynamic pressure change plot 440 upward by decreasing the fluid velocity of the fluid within system 500, causing the gas or vapor to condense.

[0079] When flow control device 540 is opened, the fluid velocity increases, but so does the static pressure at the inlet of vibratory instrument 5, and vice versa. The combination of flow control device 540 and pump 510 can achieve the desired low static pressure and high velocity by partially closing flow control device 540 (e.g., restricting flow and reducing pressure downstream of flow control device 540) and increasing the pump speed (e.g., increasing the flow rate) to provide favorable process conditions.

[0080] The static pressure of the fluid within the vibrating meter 5, and more specifically within the meter assembly 10 within the vibrating meter 5, can be varied by using the pump 510 or the flow control device 540 described above, or a combination of both, although other means for varying the static pressure may also be employed. For example, the height z of the vibrating meter 5 may be varied. To reduce the static pressure of the fluid within the vibrating meter 5, In order to increase the static pressure of the fluid in the vibratory meter 5, the height z can be increased. The height z can be decreased. The height z of the vibratory meter 5 can be adjusted by adjusting the distance between the vibratory meter 5 and the pipeline 501. and a vibrating meter 5, for example, a lift between the flow controller 540 and the pump 510. The change can be made by any suitable means, such as a pump 510, a flow controller 540, and / or a powered lift. Other means may be used, as may a combination of various means (e.g., pump 510, flow controller 540, and / or powered lift).

[0081] For example, if the flow rate through the bypass is sufficient, it is not necessary to use a pump. Only the flow control device 540 can be used. The flow control device 540 is located below the vibrating meter 5. Alternatively, the pump 510 and / or the powered lift may be installed in another location. In another alternative, the flow control device 540 may not be used, such as when used. The meter may be located in the main line rather than in the bypass. Additionally or alternatively, only one pressure sensor may be used. For example, only the outlet pressure sensor 530 may be used. The inlet and / or outlet pressure sensors 520, 530 may be located in different locations. The outlet pressure sensor 530 and its location may be determined by the presence of a pressure sensor that is located at the outlet once the fluid in the meter assembly 10 has vaporized. Once at atmospheric pressure, the static pressure at the outlet pressure sensor 530 is substantially stable with respect to fluid velocity. This can be beneficial because it is possible that a further increase in fluid velocity will not cause a substantial decrease in the static pressure measured by outlet pressure sensor 530.

[0082] [Determining the vapor pressure of a fluid] Figure 6 illustrates a method 600 for determining the vapor pressure of a fluid. As shown in Figure 6, the method 600, in step 610, supplies a fluid to a meter assembly, such as the meter assembly 10 described above with reference to Figure 1. In step 620, the method 600 determines the vapor pressure of the fluid based on the static pressure of the fluid within the meter assembly.

[0083] In step 610, the fluid is pumped through a pipeline, such as the system 500 shown in FIG. 5, the meter assembly 10 can be supplied via a branch A branch is a loop that returns fluid to the pipeline 501. Alternatively, a branch can return fluid to a non-returning 5. The meter assembly 10 may be supplied through a branch of the pipe shown in FIG. A branch from line 501 may empty into a reservoir or tank rather than returning to pipeline 501. The fluid may or may not contain vapor or gas.

[0084] Step 620 may, for example, measure the flow of fluid within the meter assembly 10 until a phase change of the fluid is detected. The vapor pressure of a fluid can be determined by varying the total pressure or static pressure. For example, the static pressure of a fluid can be increased until vapor is no longer detectable. The static pressure may be reduced until vapor is detected. The phase change of the fluid may be measured, for example, as shown in FIG. This can be detected by any suitable means, such as by detecting a change in the drive gain or drive signal as described above, or based on a sensor signal.

[0085] When a phase change of the fluid is detected, such as when a change in drive gain is detected, the vibratory meter 5, or electronics coupled to the vibratory meter 5, can determine the pressure at the inlet and / or outlet of the meter assembly 10. For example, with reference to FIG. 5, the inlet pressure sensor 520 can measure the static pressure of the fluid at the inlet of the meter assembly 10, and the outlet pressure sensor 530 can measure the static pressure of the fluid at the outlet of the meter assembly 10. However, Thus, the inlet static pressure and / or the outlet static pressure may be related to the phase change of the fluid.

[0086] Using the inlet and outlet static pressures in equation [7] above, we can calculate the static pressure in the instrument assembly. can be determined. For example, the outlet pressure may be P1 and P2 may be the pressure of the fluid in the meter assembly. The height terms ρgz1 and ρgz2 can be used to compensate for changes in height of the fluid in the meter assembly due to, for example, the shape of the conduit. For example, an arcuate conduit, such as the conduit in the meter assembly 10 described above, may have height variations. The dynamic velocity term ρv1 2 / 2, ρv2 2 / 2 can be solved similarly by measuring the density and flow rate of the fluid and knowing the dimensions of the conduit and the pipes connected to the inlet and outlet of the conduit. Similarly, the viscous pressure drop term (-ρv 2 / 2)×(fL / D) can also be determined.

[0087] Thus, the method 600 determines the vapor pressure of the fluid within the meter assembly 10 based on the detection of the vapor. That is, the static pressure can be varied until a phase change is detected, and then the associated static pressure can be determined, for example, based on the outlet pressure. Thus, the static pressure can be vapor pressure. As can be appreciated, the change in pressure within the meter assembly can be based on a change in cross-sectional area within the meter assembly.

[0088] The above describes the static behavior of the vibratory meter 5, particularly the meter electronics 20, and the fluid within the meter assembly 10. A method 600 for determining the vapor pressure of a fluid in a meter assembly 10 based on the pressure has been described. The determined vapor pressure may be more accurate because the static pressure is the static pressure of the fluid within the meter assembly 10, rather than, for example, the static pressure of the fluid in a pipeline into which the meter assembly is inserted. As a result, the values ​​provided by the vibrating meter 5 and the meter electronics 20 are more accurate. This improves the operation of the vibration meter 5 and the meter electronics 20. More accurate measurements in fluid processes can improve other technical fields, such as the control of fluid processes.

[0089] The detailed descriptions of the above embodiments are not intended to be exhaustive of all embodiments contemplated by the inventors of the present disclosure within the scope of the present disclosure. Indeed, those skilled in the art will recognize that certain elements of the above-described embodiments can be combined or removed in various ways to create additional embodiments that are within the scope and teachings of the present disclosure. It will also be apparent to those skilled in the art that the above-described embodiments can be combined in whole or in part to create additional embodiments within the scope and teachings of the present disclosure.

[0090] Thus, while specific embodiments have been described herein for illustrative purposes, those skilled in the art will recognize that various equivalent modifications are possible within the scope of the present disclosure. The teachings presented herein are applicable not only to the embodiments described above and illustrated in the accompanying drawings, but also to other methods, apparatus, electronic devices, systems, etc. for determining the vapor pressure of a fluid. Accordingly, the scope of the above-described embodiments should be determined from the following claims.

Claims

1. A vibratory instrument (5) for determining the vapor pressure of a fluid, comprising: a meter assembly (10) having a fluid; meter electronics (20) communicatively coupled to the meter assembly (10); It is equipped with The meter electronics (20) determining a vapor pressure of a fluid within the meter assembly (10) based on the static pressure of the fluid within the meter assembly (10); A vibratory instrument (5) configured as follows:

2. The meter electronics (20) configured to determine the vapor pressure of a fluid within the meter assembly (10) based on the static pressure of the fluid within the meter assembly (10) comprises: Varying the static pressure of the fluid within the meter assembly (10) until a phase change of the fluid is detected; Determining the static pressure of a fluid within said meter assembly (10) 2. The vibratory meter (5) of claim 1, comprising meter electronics (20) configured to:

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

4. the meter assembly (10) is configured to vibrate and provide a sensor signal resulting from the vibration; The vibratory meter (5) of any one of claims 1 to 3, wherein the meter electronics (20) is further configured to detect steam within the meter assembly (10) based on the sensor signal.

5. 5. The vibratory meter (5) of claim 1, wherein the meter electronics (20) is further configured to determine a vapor pressure of a fluid in the meter assembly (10) based on detecting a phase change of the fluid in the meter assembly (10).

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

7. 7. The vibratory meter (5) of claim 1, wherein the static pressure of the fluid within the meter assembly (10) is determined by calculating a change in static pressure within the meter assembly (10) based on a change in cross-sectional area within the meter assembly (10).

8. The meter electronics (20) is further configured to communicate with one or more of a pump (510) and a flow control device (540) to vary the static pressure of the fluid within the meter assembly (10). A vibratory meter (5) according to any one of claims 1 to 7, configured as follows:

9. 9. The vibratory meter (5) of claim 1, 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 a static pressure of a fluid within the meter assembly (10).

10. 1. A method for determining the vapor pressure of a fluid, comprising: supplying a fluid to a meter assembly; a vapor pressure of the fluid in the meter assembly based on the static pressure of the fluid in the meter assembly; determining A method comprising:

11. determining a vapor pressure of a fluid in the meter assembly based on a static pressure of the fluid in the meter assembly, varying the static pressure of the fluid within the meter assembly until a phase change of the fluid is detected; determining a static pressure of a fluid within the meter assembly; 11. The method of claim 10, comprising:

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

13. vibrating a portion of the meter assembly and providing a sensor signal resulting from the vibration; detecting vapor within the meter assembly based on the sensor signal; The method of any one of claims 10 to 12, further comprising:

14. The method of any one of claims 10 to 13, further comprising determining a vapor pressure of a fluid in the meter assembly based on detecting a phase change of the fluid in the meter assembly.

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

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

17. communicating with one or more of a pump and a flow controller using meter electronics to vary the static pressure of a fluid within the meter assembly; The method of any one of claims 10 to 16, further comprising:

18. communicating with at least one of an inlet pressure sensor and an outlet pressure sensor using meter electronics to determine a static pressure of a fluid within the meter assembly; The method of any one of claims 10 to 17, further comprising:

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