True steam pressure and flash vapor detection equipment and related methods

Abstract

A method for determining the vapor pressure of a fluid is provided. The method includes the following steps: providing a meter having meter electronics, wherein the meter includes at least one of a flow meter and a density meter; flowing a process fluid through the meter; providing a low-pressure location associated with the meter; adjusting the pressure of the process fluid until flash vaporization is detected at the low-pressure location; and calculating the true vapor pressure of the process fluid if flash vaporization is detected.

Description

Technical Field

[0001] The present invention relates to vibrating meters, and more particularly, to methods and apparatus for real-time steam pressure determination. Background Art

[0002] Reid Vapor Pressure (RVP) is one of the most widely recognized characteristics used to measure and enforce fuel quality standards. True vapor pressure is a critical characteristic in applications dealing with the flow and storage of volatile fluids such as gasoline, natural gas liquids, and liquefied petroleum gas. Vapor pressure provides an indication of how a volatile fluid may behave during handling and further indicates conditions where bubbles may form and pressure may build. Therefore, vapor pressure measurement of volatile fluids improves safety and prevents damage to shipping vessels and infrastructure.

[0003] If the vapor pressure of a fluid is too high, cavitation can occur during pumping and transfer operations. Additionally, container or process line vapor pressures can exceed safe levels due to temperature fluctuations. Therefore, it is often necessary to know the RVP before storage and transportation.

[0004] Typically, RVP is determined by capturing a sample and transferring it to a laboratory for testing to determine the sample's value. This presents challenges in enforcing regulatory fuel quality standards due to delays in obtaining final results, the cost of maintaining laboratories, and the safety and legal vulnerabilities associated with sample handling. True vapor pressure is typically determined by following this same process and then converting the RVP determined in the laboratory to true vapor pressure at flowing temperature by relying on lookup tables and databases based on empirical measurements.

[0005] Therefore, there is a need for an online device or system that can continuously and in real time measure true vapor pressure and / or RVP during processing. This is provided by the present embodiment and represents an advance in the art. On-site measurement is more reliable because it avoids the need for periodic sampling and completely eliminates the risk of fluid property changes between sample collection and laboratory analysis. Furthermore, real-time measurement improves safety because unsafe conditions can be corrected immediately. Furthermore, financial savings are achieved because regulatory enforcement can be performed through simple on-site inspections, where inspections and enforcement decisions can be made with minimal delay or processing downtime. Summary of the Invention

[0006] According to an embodiment, a method for determining the vapor pressure of a fluid is provided. The method includes providing a meter having meter electronics, wherein the meter includes at least one of a flow meter and a densitometer. A process fluid is flowed through the meter, and a low-pressure location associated with the meter is provided. The temperature of the process fluid is measured at the low-pressure location. The static pressure of the process fluid is adjusted until flash vaporization is detected at the low-pressure location. If flash vaporization is detected, the true vapor pressure of the process fluid is determined.

[0007] According to an embodiment, a system for determining the true vapor pressure of a process fluid is provided. The system includes a meter comprising at least one of a flow meter and a densitometer. A low-pressure location is associated with the meter. A pressure regulator is in fluid communication with the meter. A pressure sensor is in fluid communication with the process fluid. A temperature sensor is configured to measure the temperature at the low-pressure location. Meter electronics communicate with the meter and the pressure sensor, wherein the meter electronics is configured to control the pressure regulator to adjust the static pressure of the process fluid until flash vaporization is detected at the low-pressure location, and the meter electronics is configured to calculate the true vapor pressure of the process fluid if flash vaporization is detected.

[0008] All aspects

[0009] According to one aspect, a method for determining the vapor pressure of a fluid is provided. The method includes providing a meter having meter electronics, wherein the meter includes at least one of a flow meter and a densitometer. A process fluid is flowed through the meter, and a low-pressure location associated with the meter is provided. The temperature of the process fluid is measured at the low-pressure location. The static pressure of the process fluid is adjusted until flash vaporization is detected at the low-pressure location. If flash vaporization is detected, the true vapor pressure of the process fluid is determined.

[0010] Preferably, measuring the temperature comprises IR thermography.

[0011] Preferably, detecting the flash comprises optical analysis.

[0012] Preferably, the low pressure location comprises the flow meter manifold.

[0013] Preferably, the low pressure location comprises a differential pressure element.

[0014] Preferably, the method comprises the steps of measuring the temperature of the process fluid and calculating the Reid vapor pressure from the temperature and the true vapor pressure.

[0015] Preferably, the method comprises the steps of measuring the vapor-liquid ratio at the time point when the Reid vapor pressure is measured, and correlating the vapor-liquid ratio with the Reid vapor pressure at the time point when the Reid vapor pressure is measured.

[0016] According to one aspect, a system for determining the true vapor pressure of a process fluid is provided. The system includes a meter comprising at least one of a flow meter and a density meter. A low-pressure location is associated with the meter. A pressure regulator is in fluid communication with the meter. A pressure sensor is in fluid communication with the process fluid. A temperature sensor is configured to measure the temperature at the low-pressure location. Meter electronics communicate with the meter and the pressure sensor, wherein the meter electronics is configured to control the pressure regulator to adjust the static pressure of the process fluid until flash vaporization is detected at the low-pressure location, and the meter electronics is configured to calculate the true vapor pressure of the process fluid if flash vaporization is detected.

[0017] Preferably, the temperature sensor comprises an IR thermometer.

[0018] Preferably, the optical sensor is configured to detect flash evaporation.

[0019] Preferably, the low pressure location comprises the flow meter manifold.

[0020] Preferably, the low pressure location comprises a differential pressure element.

[0021] Preferably, the meter electronics are configured to measure the vapor-to-liquid ratio at the time the Reid vapor pressure is measured and to correlate the vapor-to-liquid ratio with the Reid vapor pressure at the time the Reid vapor pressure is measured.

[0022] Preferably, the meter includes: one or more conduits; at least one driver, at least one driver attached to the one or more conduits and configured to generate a vibration signal for the one or more conduits; and at least one detector, at least one detector attached to the one or more conduits and configured to receive the vibration signal from the one or more conduits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 illustrates a flow meter sensor assembly according to an embodiment;

[0024] Figure 2 illustrates meter electronics according to an embodiment;

[0025] Figure 3 illustrates a steam pressure determination system according to an embodiment;

[0026] Figure 4 illustrates a method of steam pressure determination according to an embodiment; and

[0027] Figure 5 Another method of steam pressure determination according to an embodiment is illustrated. DETAILED DESCRIPTION

[0028] Figures 1 to 5 The following description depicts specific examples to teach those skilled in the art how to make and use the best mode of the present invention. For the purpose of teaching the principles of the present invention, 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 present invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the present invention. Therefore, the present invention is not limited to the specific examples described below, but is limited only by the claims and their equivalents.

[0029] Vibration sensors, such as vibrating densitometers and Coriolis flowmeters, are generally known and are used to measure mass flow and other information related to material flowing through a conduit in a flowmeter or a conduit comprising a densitometer. Exemplary flowmeters are disclosed in U.S. Patents 4,109,524, 4,491,025, and Re. 31,450, all to J.E. Smith et al. These flowmeters have one or more conduits in straight or curved configurations. Each conduit configuration in a Coriolis mass flowmeter has a set of natural vibration modes, which can be simple bending, torsional, or coupled, for example. Each conduit can be driven to oscillate in a preferred mode.

[0030] Certain types of mass flow meters, particularly Coriolis flow meters, can operate in a manner that performs a direct measurement of density, providing volume information via the quotient of mass over density. See, for example, U.S. Patent No. 4,872,351 to Ruesch for a pure oil automatic meter that uses a Coriolis flow meter to measure the density of an unknown multiphase fluid. U.S. Patent No. 5,687,100 to Buttler et al. teaches a Coriolis effect densitometer that corrects density readings for mass flow rate effects in a mass flow meter used as a vibrating tube densitometer.

[0031] Material flowing into the flow meter from a connecting pipe on the inlet side of the flow meter is directed through the conduit and exits the flow meter through the outlet side of the flow meter. The natural vibration modes of the vibrating system are defined in part by the combined mass of the conduit and the material flowing within the conduit.

[0032] When there is no flow through the flowmeter, the 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 a real-time delay measured at zero flow. When material begins to flow through the flowmeter, the Coriolis force causes each point along the conduit to have a different phase. For example, the phase at the inlet end of the flowmeter lags the phase at the centralized drive location, while the phase at the outlet leads the phase at the centralized drive location. Detectors on the conduit produce sinusoidal signals that represent the motion of the conduit. The signals output from the detectors are processed to determine the time delay between the detectors. The time delay between two or more detectors is proportional to the mass flow rate of the material flowing through the conduit.

[0033] The meter electronics connected to the driver generates a drive signal to operate the driver and also determines the mass flow rate and / or other properties of the process material based on the signal received from the detector. The driver can include one of many well-known devices, however, a magnet and an opposing drive coil have achieved great success in the flow meter industry. Alternating current is delivered to the drive coil to cause the conduit to vibrate at the desired amplitude and frequency. It is also known in the art to configure the detector with a magnet and coil arrangement very similar to the driver device. However, when the driver receives a current that induces motion, the detector can use the motion provided by the driver to induce a voltage. The time delay measured by the detector is very small, typically measured in nanoseconds. Therefore, the transducer output must be very precise.

[0034] Figure 1 The flow meter 5 is shown, which can be, for example, but not limited to, any vibrating meter, such as a Coriolis flow meter or a densitometer. The flow meter 5 includes a sensor assembly 10 and a meter electronics 20. The sensor assembly 10 responds to the mass flow rate and density of the process material. The meter electronics 20 is connected to the sensor assembly 10 via a lead 100 to provide density, mass flow rate, and temperature information and other information on a path 26. The sensor assembly 10 includes flanges 101 and 101', a pair of manifolds 102 and 102', a pair of parallel conduits 103 (first conduit) and 103' (second conduit), a driver 104, a temperature sensor 106 such as a resistance temperature detector (RTD), and a pair of detectors 105 and 105' such as a magnet / coil detector, a strain gauge, an optical sensor, or any other detector known in the art. The conduits 103 and 103' have inlet legs 107 and 107' and outlet legs 108 and 108', respectively. The conduits 103 and 103' bend at at least one symmetrical location along the length of the conduits 103 and 103' and are substantially parallel throughout the length of the conduits 103 and 103'. Each conduit 103, 103' oscillates about an axis W and W', respectively.

[0035] The legs 107, 107', 108, 108' of the conduits 103, 103' are fixedly attached to conduit mounting blocks 109 and 109', and these blocks are in turn fixedly attached to the manifolds 102 and 102'. This provides a continuous, closed material path through the sensor assembly 10.

[0036] When flanges 101 and 101' are connected to a process line (not shown) carrying the process material to be measured, the material passes through the first hole in flange 101 (at Figure 1 103') enters the first end 110 of the flow meter 5 and is directed through the manifold 102 to the conduit mounting block 109. Within the manifold 102, the material is separated and routed through conduits 103 and 103'. Upon exiting conduits 103 and 103', the process material recombines as a single stream within the manifold 102' and is then routed out of the second end 112 connected to a process line (not shown) via flange 101'.

[0037] Conduits 103 and 103' are selected and appropriately mounted to conduit mounting blocks 109 and 109' so as to have approximately the same mass distribution, moment of inertia, and Young's modulus about bending axes WW and W'-W', respectively. Because the Young's modulus of conduits 103, 103' varies with temperature, and this variation affects flow and density calculations, a temperature sensor 106 is mounted on at least one of conduits 103, 103' to continuously measure the temperature of the conduit. The temperature of the conduit, and therefore the voltage appearing across temperature sensor 106 for a given current passing through the conduit, is primarily determined by the temperature of the material passing through the conduit. Meter electronics 20 uses the temperature-dependent voltage appearing across temperature sensor 106 in a well-known manner to compensate for changes in the elastic modulus of conduits 103, 103' due to any changes in the temperature of conduits 103, 103'. Temperature sensor 106 is connected to meter electronics 20.

[0038] The two conduits 103, 103' are driven by a driver 104 in opposite directions about their respective bending axes W and W' in what is known as the first, out-of-phase bending mode of the flow meter. The driver 104 can include any of a number of well-known devices, such as a magnet mounted to the conduit 103' and an opposing coil mounted to the conduit 103, through which an alternating current is passed to cause the two conduits to vibrate. The meter electronics 20 applies a suitable drive signal to the driver 104 via leads 113. It should be understood that while the discussion has been made with respect to two conduits 103, 103', in other embodiments, only a single conduit may be provided, or more than two conduits may be provided. It is also within the scope of the present invention to generate multiple drive signals for multiple drivers, and for drivers that drive the conduits in a mode other than the first, out-of-phase bending mode.

[0039] Meter electronics 20 receives the temperature signal on lead 114, and the left and right velocity signals appearing on leads 115 and 115', respectively. Meter electronics 20 causes the drive signal appearing on lead 113 to appear at driver 104 and cause conduits 103, 103' to vibrate. Meter electronics 20 processes the left and right velocity signals and the temperature signal to calculate the mass flow rate and density of the material passing through sensor assembly 10. This information, along with other information, is applied to the device of use via meter electronics 20 in path 26. A description of the circuitry of meter electronics 20 is not required to understand the present invention and has been omitted for the sake of brevity in this description. It should be understood that the present invention is provided in the following manner: Figure 1 The description is given only as an example of one possible vibration meter operation and Figure 1 The description is not intended to limit the teachings of the present invention.

[0040] A Coriolis flow meter configuration is described, but it will be apparent to those skilled in the art that the present invention may be implemented on a vibrating tube or fork densitometer without the additional measurement capability provided by a Coriolis mass flow meter.

[0041] Figure 2 is a block diagram of the meter electronics 20 of the flow meter 5 according to an embodiment. In operation, the flow 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 rates, and a measurement or average of an overall flow rate that includes, for example, both volumetric and mass flow rates of individual flow components.

[0042] The flow meter 5 generates a vibration response. The vibration response is received and processed by the meter electronics 20 to generate one or more fluid measurement values. The values ​​can be monitored, recorded, saved, totaled and / or output.

[0043] 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. Although these components are shown as distinct blocks, it should be understood that the meter electronics 20 may include various combinations of integrated and / or discrete components.

[0044] The interface 201 is configured to communicate with the sensor assembly 10 of the flow meter 5. The interface 201 can be configured to couple to the lead 100 (see Figure 1 ) and exchanges signals with the driver 104, the detection sensors 105 and 105', and the temperature sensor 106. The interface 201 may also be configured to communicate with an external device through the communication path 26, for example.

[0045] The processing system 203 may include any type of processing system. The processing system 203 is configured to retrieve and execute stored routines to operate the flow 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 other variables 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 within the scope of the specification and claims.

[0046] The flow meter routine 205 can generate and store fluid quantification and flow measurement values. These values ​​can include substantially instantaneous measurements or can include aggregated or cumulative values. For example, the flow meter routine 205 can generate a mass flow measurement and store it, for example, in a mass flow 221 memory in the storage system 204. The flow meter routine 205 can generate a density 225 measurement and store it, for example, in the storage system 204. As previously discussed and as is known in the art, the mass flow 221 and density 225 values ​​are determined based on the vibration response. The mass flow and other measurements can include substantially instantaneous values, samples, averages over a time interval, or cumulative values ​​over a time interval. The time interval can be selected to correspond to a period of time during which certain fluid states are detected, such as a liquid-only fluid state or, alternatively, a fluid state including liquid and entrained gas. Additionally, other mass and volume flow rates and associated quantification values ​​are contemplated and are within the scope of the present description and claims.

[0047] As described above, the drive gain 306 can be used as a signal to indicate a no flow / false total condition. The drive gain threshold 302 can be used to distinguish between periods of flow, no flow, single / two-phase fluid phase boundaries, and gas entrainment / mixed phase flow. Similarly, the density threshold 226 applied to the density reading 225 can also be used, alone or in conjunction with the drive gain 306, to distinguish between gas entrainment / mixed phase flow. The drive gain 306 can be used as a measure of the sensitivity of the conduit vibration of the flow meter 5 to the presence of fluids of different densities, such as, but not limited to, liquid and gas phase fluids. The combined effect of damping on the energy input and the resulting amplitude is called the extended drive gain, which represents an estimate of how much power is required to maintain the target vibration amplitude when the available power exceeds 100%:

[0048]

[0049] It should be noted that for the purposes of the embodiments provided herein, in some embodiments, the term drive gain can refer to a drive current, a pickoff voltage, or any measured or derived signal indicating the amount of power required to drive the flow conduits 103, 103' at a specific amplitude. In related embodiments, the term drive gain can be expanded to encompass any metric used to detect multiphase flow, such as noise level, standard deviation of the signal, measurements related to damping, and any other means known in the art for detecting mixed-phase flow. In embodiments, these metrics can be compared between pickoff sensors 105 and 105' to detect mixed-phase flow.

[0050] As long as all of the fluid in the tube is uniform in density, the vibrating conduit 103, 103' requires little energy to maintain vibration at its first resonant frequency. In the case where the fluid consists of two (or more) immiscible components of different densities, the vibration of the tube will cause a different amount of displacement of each of the components. This difference in displacement is called decoupling, and the magnitude of the decoupling has been shown to depend on the ratio of the densities of the components and the anti-Stokes number:

[0051]

[0052]

[0053] Where ω is the vibration frequency, ν is the kinematic viscosity of the fluid, and r is the radius of the particle. It should be noted that, as in the case of bubbles, the particle can have a lower density than the fluid.

[0054] The decoupling that occurs between the components results in damping in the vibration of the tube, requiring more energy to maintain the vibration or reducing the amplitude of the vibration for a fixed amount of energy input.

[0055] Go to Figure 3 According to an embodiment, a vapor pressure determination system 300 is provided. A process line 303 is provided having an inlet 304 and an outlet 307, wherein the process line 303 is configured to carry a process fluid that enters the process line 303 through the inlet 304. An upstream pressure regulator 308 is provided to control the flow of the fluid through the process line 303. A downstream pressure regulator 310 is provided to control the flow of the fluid through the process line 303. A flow meter 5 having meter electronics 20 is provided between the upstream pressure regulator 308 and the downstream pressure regulator 310 and is configured to receive the process fluid that passes through the upstream pressure regulator 308. A pressure sensor 312 and a temperature sensor 314 are also present in the system 300. Although the pressure sensor 312 and the temperature sensor 314 are shown as being located downstream of the flow meter 5, these sensors 312 and 314 may be located upstream of the flow meter 5 or incorporated into the flow meter 5.

[0056] Since the low pressure point is generally determined by frictional pressure loss and static pressure drop caused by velocity, as well as Bernoulli's principle, in embodiments, a velocity control system can control the pressure. In such embodiments, a variable speed pump and a pressure control valve can regulate the fluid velocity together. In this embodiment, the control valve can be located downstream of the meter, and the pump upstream of the meter, so that increasing the flow rate does not increase the static pressure in the meter. Therefore, the static pressure in the meter can be controlled by reducing the static pressure using both the upstream valve and the downstream pump. Increasing the velocity in the meter also reduces the static pressure. The pressure in the meter tube can be predicted by knowing the upstream and downstream pressures and flow rates. The pressure in the meter is reduced by increasing the pump speed or closing the valve until flashing is detected.

[0057] The meter electronics 20 communicates with the upstream pressure regulator 308, the downstream pressure regulator 310, the pressure sensor 312, and the temperature sensor 314. The meter electronics 20 can control the upstream pressure regulator 308 and the downstream pressure regulator 310. The meter electronics 20 receives pressure measurements from the pressure sensor 312 and temperature measurements from the temperature sensor 314. The meter electronics 20 is configured to monitor the pressure of the process fluid and reduce its pressure until the flow meter 5 detects the introduction of the second phase, which indicates that the vapor pressure has been reached. In an embodiment, only the pressure regulator 308 is present. Studies have shown that high-precision temperature measurements can detect early signs of flash / cavitation. In various embodiments, a very small drop in temperature is detected, which indicates a phase change (due to the latent heat of vaporization). Thus, flash is detected at the location and time of its first occurrence.

[0058] In various embodiments, the geometry of the vibrating tube sensor or specialized pressure drop element allows for accurate prediction of where flash will first occur. This allows the temperature measurement to be focused at that point. Thus, in various embodiments, as in Figure 4 As illustrated in method 350 of , a low pressure position is provided at 352 .

[0059] If the process fluid is single-phase under normal process conditions, the pressure can be reduced, for example, by partially closing the upstream pressure regulator 308, as shown in step 354. In an embodiment, high-resolution infrared (IR) thermography is used to detect temperature changes at the low-pressure location. In an embodiment, IR thermography is combined with optical sensors and analysis to detect the occurrence of flash vaporization. Although IR thermography is specifically mentioned, it is contemplated that other temperature measurement devices with sufficient sensitivity may be used, as the precise location of the first flash vaporization is known.

[0060] The low-pressure location, and therefore the point where flashing first occurs, is typically near the outlet manifold 102' on the vibrating tube sensor. Flashing actually occurs at this location before it can be detected by conventional methods. Therefore, at 356, temperature measurement at this location allows detection of the very beginning of flashing. At 358, flash detection allows identification of the single-phase / two-phase fluid phase boundary. The temperature associated with the flash is measured and recorded. At step 360, the true vapor pressure is calculated, taking into account the temperature at the point where the flash was detected.

[0061] In an embodiment, a temperature measuring device sensitive enough to detect such changes is positioned in the flow meter manifold.

[0062] In embodiments, the steam pressure measurement component may include specifying the vapor-to-liquid ratio at which the steam pressure is measured. This approach enables detection of flash vaporization at 0% vapor. Other measurements within the vibrating tube sensor may also be used to determine the vapor-to-liquid ratio as steam increases, allowing steam pressure to be measured at multiple vapor-to-liquid ratios, starting from 0%.

[0063] In an embodiment, if it is deemed unnecessary to measure the vapor pressure at a vapor-to-liquid ratio other than 0%, the differential pressure element can be set to exhibit the desired pressure drop. Temperature measurement or an infrared thermometer at this point is used for flash detection.

[0064] Go to Figure 5 , a flow chart 400 is provided that illustrates an example of a vapor pressure determination scheme employed by system 300. In step 402, the pressure of the process fluid in system 300 is measured. This is accomplished via pressure sensor 312. In step 403, the temperature of the process fluid in system 300 is measured. If the process fluid is single-phase under normal process conditions, the flow pressure can be reduced by partially closing upstream pressure regulator 308, as shown in step 404. In step 406, drive gain and / or density can be measured, and as described above, drive gain and / or density can be used to determine the presence of multiphase flow and also to determine single-phase / two-phase fluid phase boundaries. Since the process fluid pressure is measured at 402 and the process fluid pressure is reduced at 404, the introduction of a second phase is determined at 406 via the drive gain and / or density measurements, which in turn indicates that vapor pressure has been reached. In step 408, detection of the true vapor pressure is indicated by recording both the pressure and temperature at the point where the presence of the second phase is detected. In step 410, the RVP is calculated based on the measured true vapor pressure, taking into account the temperature at which the true vapor pressure was recorded.

[0065] It should be noted that if the process fluid already contains some vapor, this will be detected by measuring the drive gain and / or density, and the downstream pressure regulator 310 can be partially closed to increase the pressure for the purpose of determining the vapor pressure and temperature at the point when the second phase is no longer present. In either case, the single-phase / two-phase fluid phase boundary and the associated temperature / pressure of the process fluid at that boundary are used to indicate the true vapor pressure of the process fluid.

[0066] In other embodiments, if the upstream / downstream pressure regulator configuration does not provide sufficient pressure variation to achieve the vapor pressure, other pressure regulators and pressure control methods may be employed. In other embodiments, temperature measurement may also be included to provide the ability to convert between true vapor pressure (TVR) and vapor pressure at a standard temperature, such as Reid Vapor Pressure (RVP). TVP is the actual vapor pressure of the liquid product at the measurement temperature. TVP is difficult to measure directly and depends on the composition and temperature of the liquid in the measurement device. Once the TVP and temperature are known, the true vapor pressure and / or RVP at any other temperature can be calculated from empirical data stored in the meter electronics 20. The empirical data may include lookup tables, mathematical algorithms, and / or mathematical curves. Direct RVP measurement typically requires sending a sample for laboratory analysis.

[0067] In an embodiment, the system 300 is configured to measure only a sample of the main flow stream in a slipstream, thereby reducing the impact on material handling. Because RVP depends primarily on composition, slipstream sampling is effective when the composition is fairly uniform. This allows for a smaller, less expensive, and less obtrusive system.

[0068] The detailed description of the above embodiments is not an exhaustive description of all embodiments contemplated by the inventors to fall within the scope of the present invention. Indeed, those skilled in the art will recognize that certain elements of the above embodiments may be combined or removed in various ways to create other embodiments, and that these other embodiments fall within the scope and teachings of the present invention. It will also be apparent to those skilled in the art that the above embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the present invention.

[0069] Therefore, although specific embodiments and examples of the present invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the present invention, as those skilled in the relevant art will recognize. The teachings provided herein can be applied to other vibration systems, not just the embodiments described above and shown in the accompanying drawings. Therefore, the scope of the present invention should be determined by the appended claims.

Claims

1. A method for determining the vapor pressure of a fluid, the method comprising the following steps: Providing a meter having meter electronics, wherein the meter includes at least one of a flow meter and a density meter; flowing a process fluid through the meter; providing a low pressure location in an outlet manifold of said meter; measuring the temperature of the treatment fluid at the low pressure location using infrared thermal imaging; adjusting the static pressure of the process fluid until flashing can be detected at the low pressure location; In the event that flash vaporization can be detected, the true vapor pressure of the process fluid is determined.

2. The method of determining the vapor pressure of a fluid according to claim 1, wherein: Detecting the flash vaporization comprises optical analysis.

3. The method for determining the vapor pressure of a fluid according to claim 1, wherein: The low pressure location includes a differential pressure element.

4. The method of determining the vapor pressure of a fluid according to claim 1 , comprising the steps of: measuring the temperature of the process fluid; and The Reid vapor pressure is calculated based on the temperature and the true vapor pressure.

5. The method of determining the vapor pressure of a fluid according to claim 1 , comprising the steps of: Measuring the vapor-liquid ratio at the time point when the Reid vapor pressure is measured; as well as The vapor-to-liquid ratio is correlated to the Reid vapor pressure at the point in time when the Reid vapor pressure is measured.

6. A system (300) for determining a true vapor pressure of a process fluid, the system (300) comprising: A meter (5), the meter (5) comprising at least one of a flow meter and a density meter; an outlet manifold, the outlet manifold including a low pressure location; a pressure regulator (308), the pressure regulator (308) being in fluid communication with the meter (5); a pressure sensor (312) in fluid communication with the process fluid; an infrared thermal imaging temperature sensor, the temperature sensor being located in the outlet manifold and configured to measure the temperature at the low-pressure location; Meter electronics (20) in communication with the meter (5) and the pressure sensor (312), wherein the meter electronics (20) is configured to: controlling the pressure regulator (308) to adjust the static pressure of the process fluid until flashing is detected by the temperature sensor at the low pressure location; and In cases where flash vaporization can be detected, the true vapor pressure of the process fluid is calculated.

7. The system (300) of claim 6, wherein: The optical sensor is configured to detect flash vaporization.

8. The system (300) of claim 6, wherein: The low pressure location includes a differential pressure element.

9. The system (300) of claim 6, wherein: The meter electronics (20) is configured to: measuring the vapor-to-liquid ratio at the point in time when the Reid vapor pressure is measured; and The vapor-to-liquid ratio is correlated to the Reid vapor pressure at the point in time when the Reid vapor pressure is measured.

10. The system (300) of claim 6, wherein: The meter (5) comprises: one or more conduits (103, 103'); at least one driver (104) attached to the one or more conduits (103, 103') and configured to generate a vibration signal for the one or more conduits (103, 103'); and At least one detector (105, 105') is attached to the one or more conduits (103, 103') and is configured to receive a vibration signal from the one or more conduits (103, 103').

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