Vortex flowmeter providing extended flow rate measurement

Abstract

The present invention relates to a vortex flowmeter for measuring a flow rate of a fluid. The flowmeter comprises a flow tube, a bluff body and a vortex sensor. The bluff body, positioned in the flow tube, causes vortices in the fluid to shed as the fluid flows through the flow tube, and the vortex sensor detects the vortices and generates a vortex signal representative of the detected vortices. A pressure sensor arrangement is configured to detect a pressure difference in the fluid between a first location upstream of at least a portion of the bluff body and a second location downstream of at least a portion of the bluff body, and to generate a pressure difference signal representative of the pressure difference between the two locations. The flowmeter determines the flow rate of the fluid based on the pressure difference.

Description

Technical Field

[0001] This disclosure generally relates to a vortex flow meter for measuring the flow rate of a fluid, and more specifically, to a vortex flow meter with a sensor configured to detect the pressure difference between an upstream and downstream location of a blunt body. Background Technology

[0002] Flow meters measure the flow rate of fluids in pipes or other passages. The fluid can be, for example, a gas or liquid, and can be compressible or incompressible. One type of flow meter is the vortex flow meter, which measures flow rate based on the principle of vortex shedding. Vortex shedding refers to the natural process in which fluid passing through a bluff body (sometimes called a shedding device) causes a slowly moving boundary layer to form along the surface of the bluff body. A low-pressure region forms behind the bluff body, and this low-pressure region causes the boundary layer to roll upwards, which continuously generates vortices on the opposite side of the bluff body. Unfortunately, the operating principle of a vortex flow meter requires a minimum Reynolds number based on the velocity, density, and viscosity of the fluid being measured. This means that for a given fluid, the vortex flow meter has a minimum velocity limit to measure the flow rate. Summary of the Invention

[0003] It is recognized in all aspects of this disclosure that vortices cause pressure changes that can be sensed by a pressure sensor, and that under turbulent conditions, vortex shedding pressure changes have a frequency related to the flow rate. Therefore, by measuring the frequency of the pressure changes, the flow rate can be determined. Vortex flow meters embodying all aspects of this disclosure measure fluid flow rate by using the vortex shedding bar of the vortex flow meter as a pressure drop element. Thus, even at relatively low velocities lower than the conventional limits of vortex shedding, the β ratio (β) calculated for a given vortex shedding geometry can be used in conjunction with a pressure difference measurement to calculate the flow rate.

[0004] In one aspect, a vortex flow meter for measuring the flow rate of a fluid includes a flow tube, a bluff body, and a vortex sensor. The bluff body, positioned in the flow tube, causes vortices in the fluid to dislodge as the fluid flows through the flow tube, and the vortex sensor detects the vortices and generates a vortex signal representing the detected vortices. A pressure sensing device is configured to detect a pressure difference in the fluid between a first location upstream of at least a portion of the bluff body and a second location downstream of at least a portion of the bluff body, and generates a pressure difference signal representing the pressure difference.

[0005] In another embodiment, a vortex flowmeter for measuring the flow rate of a fluid includes a flow tube and a bluff body positioned within the flow tube. The flowmeter also includes one or more sensors configured to generate signals representing characteristics of the fluid as it flows through the flow tube past the bluff body. A measurement processor generates a flow rate output representing the flow rate of the fluid based on the signals from the one or more sensors when the fluid has a Reynolds number less than 2000.

[0006] In another aspect, a method for determining the total amount of fluid in a batch process includes: during the batch process, detecting vortices detached from the bluff body by the bluff body as fluid flows through it in a flow tube positioned in a vortex flowmeter; and during the batch process, detecting a pressure difference across the bluff body. The method further includes: determining a first fluid volume flowing through the bluff body during an initial portion of the batch process based on the detected pressure difference; determining a second fluid volume flowing through the bluff body during an intermediate portion of the batch process based on the detected vortices; and determining a third fluid volume flowing through the bluff body during a final portion of the batch process based on the detected pressure difference.

[0007] Other objects and features of the invention will be apparent in part and pointed out in part herein. Attached Figure Description

[0008] Figure 1 This is a perspective view of a vortex flow meter according to one embodiment;

[0009] Figure 2 This is a longitudinal section of a sub-assembly of a vortex flowmeter, including a flow tube and a bluff body, and schematically shows the pressure differential sensor of the vortex flowmeter; and

[0010] Figure 3 This is a flowchart illustrating an example process for using a vortex flowmeter to provide flow rate output.

[0011] In all the accompanying drawings, the corresponding reference numerals indicate the corresponding parts. Detailed Implementation

[0012] Now for reference Figure 1 and 2 An embodiment of a vortex flowmeter for measuring the flow rate of a fluid is generally designated as 101. The vortex flowmeter 101 includes a flow tube 103 through which fluid can flow. The flow tube 103 is suitably configured for installation in a fluid flow line (not shown). For example, the flow tube 103 includes processing connections 105 at opposite ends for connecting the inlet 107 of the flow tube (… Figure 2The outlet 109 connects to the end of the pipe in the conduit. In one or more embodiments, the processing connection 105 may be adapted for wafer connection, flange connection, threaded connection, NPT connection, or any other suitable type of connection. As described in detail below, the vortex flowmeter 101 provides vortex frequency data, which can be used in conjunction with a flow calibration factor to determine the velocity and volumetric flow rate of the fluid passing through the flowmeter. The mass flow rate can also be calculated using the input fluid density value. These measurements and other measurements can be transmitted to a control room or other receiver via a communication line (e.g., a standard two-wire 4-20 mA transmission line).

[0013] like Figure 2 As shown, in the illustrated embodiment, the flow tube 103 includes a main pipe member 103A formed from a single piece of material, and first and second end members 103B joined (e.g., welded) to the ends of the main pipe member. The flow tube 103 has an axis A, and the main pipe member 103A has a length L extending along the axis A of the flow tube. In the illustrated embodiment, a processing connector 105 is integrally formed with the end members 103B. Although the illustrated flow tube 103 is a three-piece construction, other flow tubes can be constructed from any suitable number or arrangement of components.

[0014] Still referencing Figure 2 A blunt body 121 (sometimes referred to in industry as a vortex shearer or shear bar) is positioned within the flow tube 103. The blunt body 121 is a structure positioned within the fluid flow, thus extending into the flow tube 103 to generate vortices in the fluid as it flows through the flow tube. Those skilled in the art will recognize that the size and shape of the blunt body can vary. In a general sense, the blunt body can have any construction, as long as it is capable of generating vortices in the fluid flow passing through it. When the fluid flows through the flow tube 103 under turbulent conditions, the frequency of the vortices is proportional to the fluid velocity. Assuming the cross-sectional flow area of ​​the flow tube 103 is constant, the frequency of the vortices is also proportional to the volumetric flow rate. Moreover, if the density of the fluid is known or measured, the mass flow rate can be derived from the volumetric flow rate.

[0015] like Figure 2As shown, the vortex flowmeter 101 includes a vortex sensor 131 positioned to detect vortices generated by a blunt body 121. As shown, the vortex sensor 131 is suitably positioned at the top of the blunt body 121. In this embodiment, the vortex sensor 131 is in direct contact with the fluid flowing through the flow tube 103. This allows the vortex sensor 131 to directly sense the vortices. However, it is contemplated that the vortex sensor could be positioned to sense vortices indirectly, for example, by detecting the movement of the blunt body or other structure designed to buckle or otherwise move in response to pressure fluctuations associated with vortices formed in the fluid. In the illustrated embodiment, the vortex sensor 131 is a pressure difference sensor that uses a piezoelectric transducer to sense the vortex. Suitably, the vortex sensor 131 is mounted in the blunt body 121 such that the sensor is exposed to the fluid at two lateral sides of the blunt body. In this way, the sensor can detect the pressure difference at opposite lateral sides of the blunt body 121. Therefore, when vortices are formed alternately on opposite lateral sides of the bluff body, sensor 131 records the fluctuation of the pressure difference between the lateral sides of the bluff body and generates an approximately sinusoidal vortex signal.

[0016] As those skilled in the art will understand, when the fluid flowing through the flow tube 103 is turbulent (e.g., having a Reynolds number greater than or equal to about 2900) or slightly turbulent (e.g., having a Reynolds number greater than or equal to about 2300), vortices will alternate at a frequency proportional to the flow rate. Therefore, as Figure 1 As shown, the flow meter 101 includes a transmitter 141, which includes a measurement processor 142 (shown schematically) operatively connected to a vortex sensor 131 to receive vortex signals. Typically, the measurement processor 142 is configured to determine the frequency of the vortex signal and use the determined frequency to calculate the flow rate of fluid flowing through the flow tube 103 (e.g., fluid flow velocity output, volumetric flow rate output, and / or mass flow rate output).

[0017] In one embodiment, transmitter 141 (which may be analog or digital) is configured to transmit or output the determined flow rate to a distributed control system (not shown) using protocols such as, but not limited to, 4-20mA output, HART, Foundation Fieldbus, and Modbus. Measurement processor 142 may include processor-readable medium storing code representing instructions that cause the processor to perform processing. Measurement processor 142 may be, for example, a commercially available microprocessor, application-specific integrated circuit (ASIC), or a combination of ASICs, designed to implement one or more specific functions (e.g., determining flow rate based on one or more sensor signals) or enable one or more specific devices (e.g., transmitter 141) or applications. In yet another embodiment, measurement processor 142 may be analog or digital circuitry, or a combination of multiple circuits. Measurement processor 142 may also include one or more memory components (not shown) for storing data in a form retrievable by the processor. For example, the memory may store processor-executable software executed by processor 142 to perform flow rate measurement processing.

[0018] In one or more embodiments, the measurement processor 142 is configured to perform flow rate measurement processing that activates a low-flow cutoff when the frequency of the vortex signal is less than a threshold low-flow cutoff frequency. When the fluid flowing through the flow tube 103 is non-turbulent, the frequency of the vortex signal will not be predictably related to the fluid flow rate; therefore, the low-flow cutoff frequency is selected as a lower bound at which the flow meter 101 will output a flow rate measurement based on the vortex signal. For example, in one or more embodiments, the low-flow cutoff frequency is selected to correspond substantially to the following flow rates of the fluid flowing through the flow tube 103, at which the fluid has a Reynolds number of approximately 2000 to 3000. When the frequency of the vortex signal is greater than the low-flow cutoff frequency, the measurement processor 142 outputs a flow rate signal based on the vortex signal. However, when the frequency of the vortex signal is less than the low-flow cutoff frequency, the measurement processor 142 does not output a flow rate signal based on the vortex signal.

[0019] The inventors have recognized that the low flow cutoff of vortex flow meters can lead to inaccuracies in flow measurement. At the baseline level, the flow meter will be unable to register any flow occurring at a rate low enough to trigger the low flow cutoff. The inability to register low flow rates can be particularly severe in fluid batch processes where the flow meter is used to provide an indication of the total flow rate of fluid in a batch process (which begins and ends with zero flow and must ramp up to and down from a flow rate exceeding the low flow cutoff during the finite duration of the batch). In batch processes, the vortex flow meter is completely unable to address the flow rate during the ramp-up and ramp-down intervals, which can lead to significant inaccuracies in total flow rate measurement during short, low-flow-rate batches.

[0020] Still referencing Figure 2 The flow meter 101 shown also includes a pressure sensor device 201 (schematically shown) configured to detect a pressure difference in the fluid between a first location L1 upstream of a portion of the bluff body and a second location L2 downstream of at least a portion of the bluff body. The inventors have recognized that this pressure difference across the bluff body can have a predictable relationship with the flow rate even when the fluid flowing through the flow tube 103 is entirely laminar (having a flow rate that would trigger a low flow cutoff). Therefore, in one or more embodiments, the pressure sensor device 201 is configured to generate a pressure difference signal representing the pressure difference between the upstream first location L1 and the downstream second location L2 and to provide the pressure difference signal to a measurement processor 142. As will be explained in further detail below, the measurement processor 142 is configured to use the pressure difference signal to output a flow rate measurement based on the pressure difference signal when the frequency of the vortex signal is less than the low flow cutoff frequency and / or is configured to verify that the vortex sensor 131 is providing an accurate representation of the flow rate.

[0021] In the illustrated embodiment, the pressure sensor device 201 includes a single differential pressure sensor unit 203 configured to directly measure the pressure difference between an upstream position L1 and a downstream position L2. The differential pressure sensor unit 203 includes a sensing diaphragm 205 having a first side and an opposing second side. A first channel 207 is configured to deliver pressure from the upstream position L1 to the first side of the sensing diaphragm 205, and a second channel 209 is configured to deliver pressure from the downstream position L2 to the second side of the sensing diaphragm. The pressure difference between the upstream position L1 and the downstream position L2 thus exerts an unbalanced force on the opposing sides of the sensing diaphragm 205. The sensing diaphragm is configured to deform in response to this unbalanced force, and a sensing element (e.g., a piezoelectric strain gauge; not shown) is configured to detect the deformation of the sensing diaphragm and thus generate a signal proportional to the pressure difference.

[0022] In the illustrated embodiment, a first channel 207 that transmits pressure from an upstream location L1 to a first side of the sensing diaphragm 205 includes a hole formed in a blunt body 121 at the upstream location L1 to form a pressure connector. The blunt body 121, along with additional holes in the flow tube 103 and other tubes, defines an open fluid passage extending from the pressure connector at the upstream location L1 to an isolation diaphragm 211 located on the first side of the pressure differential sensor unit 203. The first channel 207 further includes an isolation channel 213 that fluidly connects the isolation diaphragm 211 to the first side of the sensing diaphragm 205. Processing fluid in the flow tube 103 can flow through the pressure connector at the upstream location L1 into the open fluid passage, which delivers pressure from the upstream location L1 to the isolation diaphragm 211. The isolation diaphragm is configured to deform in response to pressure applied thereto by the processing fluid. The isolation channel 213 is filled with oil or other pressurized delivery fluid that delivers pressure to the first side of the sensing diaphragm 205 in response to the deformation of the isolation diaphragm 211.

[0023] A second channel 209, which transmits pressure from downstream position L2 to the second side of sensing diaphragm 205, includes an orifice formed in flow tube 103 at downstream position L2 to form a pressure connector. This orifice, together with additional tubing, defines an open fluid passage extending from the pressure connector at downstream position L2 to an isolation diaphragm 215 on the second side of pressure differential sensor unit 203. The second channel 209 further includes an isolation channel 217 fluidly connecting the isolation diaphragm 215 to the second side of sensing diaphragm 205. Processing fluid in flow tube 103 can flow through the pressure connector at downstream position L2 into the open fluid passage, which delivers pressure at the downstream position to isolation diaphragm 215. The isolation diaphragm is configured to deform in response to pressure applied thereto by the processing fluid. Isolation channel 217 is filled with oil or other pressurized delivery fluid that delivers pressure to the second side of sensing diaphragm 205 in response to deformation of isolation diaphragm 215.

[0024] Although the illustrated embodiment uses an open fluid passage formed through the blunt body 121 and the flow tube 103 to provide fluid communication between the pressure connector locations L1, L2 and the external isolation diaphragms 211, 215, it is conceivable that the differential pressure sensor unit may have other configurations. For example, in one or more embodiments, the flow meter includes isolation diaphragms immediately adjacent to the upstream and downstream pressure connector locations L1, L2, and the passages that deliver pressure from the upstream and downstream pressure connector locations to the sensing diaphragms are substantially completely filled with a pressure delivery fluid isolated from the processing fluid.

[0025] It will be understood that other pressure sensing devices besides a single differential pressure sensing unit may be used in one or more embodiments. For example, it is clearly envisioned that the pressure sensing device may include a first pipeline pressure sensor configured to detect a first pipeline pressure at an upstream pressure connector location; a second pipeline pressure sensor configured to detect a second pipeline pressure at a downstream pressure connector location; and a measurement loop configured to determine the difference between the first pipeline pressure and the second pipeline pressure.

[0026] As can be seen, the pressure sensor device 201 for detecting the pressure difference on the blunt body 121 has been directly integrated into the vortex flowmeter 101 via a pressure connector integrally formed with the flowmeter. In one or more embodiments, the pressure connectors are each located at corresponding positions L1, L2 along the length L of the same integral component 103A of the flow tube 103. Further, in the illustrated embodiment, the pressure sensor device 201 is permanently mounted on the flow tube 103 within an integrated housing 221. The pressure sensor device 201 cannot be removed from the illustrated flowmeter 101 without exposing the integrated pressure connector to direct fluid communication with the external environment (which effectively renders the flowmeter 101 inoperable).

[0027] Furthermore, the flow meter 101 shown, including the vortex sensor 131 and the pressure sensor device 201, forms an integrated flow rate measuring instrument that can be installed in a pipe and integrally connected to a distributed control system. For example, only the two processing connectors 105 at the end of the flow tube 103 need to be secured to the pipe to simultaneously operatively connect both the vortex sensor 131 and the pressure sensor device 201 to the pipe. Similarly, in one or more embodiments, only a set of hardwired contacts of the transmitter 141 is connected to the distributed control network (or a single-point wireless connection is made between the transmitter 141 and the distributed control network) to enable output based on the vortex sensor 131 and the pressure sensor device 201.

[0028] In the illustrated embodiment, the upstream pressure connector position L1 is located on the upstream end face 121A of the bluff body 121, and the downstream pressure connector position L2 is spaced apart from the upstream end face of the bluff body by a distance DD along the longitudinal axis A of the flow tube 103 in the downstream direction. It should also be understood that, instead of the upstream pressure connector position L1 on the upstream end face 121A of the bluff body 121, an upstream pressure connector position L1' spaced apart from the upstream end face of the bluff body by a distance UD can be used. Pressure connectors formed in the flow tube wall (e.g., at positions L1', L2) can be located in a circumferential region of the flow tube wall that is aligned with the bluff body or in a circumferential region of the flow tube wall that is circumferentially offset from the contact area between the bluff body and the flow tube wall. As demonstrated in the following examples, a pressure difference caused by the flow has been detected at either circumferential location.

[0029] Typically, the pressure difference caused by the processed fluid flowing through the bluff body 121 at a low flow rate is relatively small. Therefore, it may be desirable to position the upstream and downstream pressure connectors at the locations where the pressure difference is most significant, so that changes in pressure difference attributable to variations in flow rate can be detected more easily and reliably using a less sensitive and therefore less expensive pressure sensing device 201. It is thought that the pressure difference is greatest between the upstream position L1 on the upstream end face 121A of the bluff body 121 and the downstream position L2 of the bluff body spaced a specific distance from the upstream end face, said specific distance will vary with the application depending on factors such as pipe size, the inner diameter ID of the flow tube 103, the type of processed fluid, and the size and shape of the bluff body. However, in one or more exemplary embodiments, the distance DD between the upstream end face 121A of the bluff body 121 and the downstream pressure connector position L2 ranges from approximately 0.333 times to approximately 5.0 times the inner diameter ID of the flow tube (e.g., for a flow tube with a diameter of approximately 0.75 inches to approximately 5.0 inches).

[0030] Although forming an upstream pressure connector at location L1 on the upstream end face 121A of the blunt body 121 is considered to enable the detection of the maximum pressure differential, in some cases it may still be desirable to use an alternative upstream pressure connector location L1'. For example, when processing fluids containing paraffin or lipids, such materials may clog the upstream pressure connector when located at location L1 on the upstream end face 121A. Therefore, in one or more embodiments, an upstream pressure connector location L1' spaced apart from the upstream end face 121A by a distance UD is selected. In one or more embodiments, the distance UD encompasses a range from approximately 0.0 times to approximately 4.75 times the inner diameter ID of the flow tube (e.g., for a flow tube with a diameter of approximately 0.75 inches to approximately 5.0 inches).

[0031] Now for reference Figure 3An exemplary control logic is schematically illustrated at 301, which can be executed by measurement processor 142 to provide a flow rate output based on a vortex signal from vortex sensor 131 and a pressure difference signal from pressure difference sensing device 201. As explained above, during use, measurement processor 142 is operatively connected to vortex sensor 131 to receive the vortex signal and operatively connected to pressure difference sensing device 201 to receive the pressure difference signal. At initial step 303, measurement processor 142 determines the frequency of the vortex signal to compare the determined frequency with a threshold low flow cutoff frequency at step 305. If the vortex signal frequency is determined to be less than the low flow cutoff frequency, then at step 307, measurement processor 142 determines the flow rate based on the pressure difference signal from pressure difference sensor 203. Those skilled in the art will understand how mathematical equations for calculating flow rates based on pressure differences of fluid flowing through flow obstacles can be derived empirically. Measurement processor 142 can use any suitable mathematical equation that correlates the detected pressure difference with the flow rate in step 307. After determining the flow rate based on the pressure difference signal at step 307, the measurement processor 142 outputs a flow rate signal based on the pressure difference signal at step 309.

[0032] Although the illustrated embodiment evaluates the vortex signal frequency at step 305 to determine when to use the pressure differential signal to generate the flow rate output of the flow meter 101, other embodiments may use other characteristics of the vortex signal or the pressure differential signal to make the same determination. For example, in one embodiment (not shown), the measurement processor determines to use the pressure differential signal to generate the flow rate output when the pressure differential signal has a value less than a threshold (which corresponds to the flow rate when the processed fluid is laminar or near laminar).

[0033] Still referencing Figure 3 When it is determined at step 305 that the vortex signal frequency is greater than the low flow cutoff frequency, the measurement processor 142 determines the flow rate based on the vortex signal at step 311. The principle of using the frequency of the vortex signal to calculate the flow rate (e.g., flow velocity, volumetric flow rate, or mass flow rate) is well known to those skilled in the art.

[0034] In the illustrated embodiment, before outputting the flow rate measurement based on the vortex signal at step 313, the measurement processor 142 is configured to execute a verification subroutine 321. First, at 323, the measurement processor 142 determines whether the pressure difference detected by the sensor 203 is greater than the sensor's maximum pressure threshold. If the detected pressure is less than the sensor's maximum pressure threshold, the measurement processor 142 determines the fluid flow rate based on the pressure difference signal at 325. After determining the flow rate using both the vortex signal (at 311) and the pressure difference signal (at 325), the measurement processor 142 compares the two flow rate measurements at step 327. If the difference between the two flow rate measurements is less than a threshold amount at 328, the processor 142 then outputs the flow rate measurement based on the vortex signal at step 313. However, if the difference between the two flow rate measurements is greater than the threshold amount, the flow meter determines an error condition at 329 and outputs an alarm. It should be understood that the measurement processor 142 may be configured to execute the verification subroutine 321 periodically (e.g., whenever a flow rate measurement based on the vortex signal is determined n times at 311; after a predetermined time interval) or whenever a flow rate measurement based on the vortex signal is determined.

[0035] As can be seen, the flow meter 101 shown extends the measurement range of conventional vortex flow meters by providing an integrated differential pressure sensing device 201 for sensing pressure differentials (which can be used to determine the flow rate of the processed fluid when the dropout frequency is less than the low flow cutoff frequency). Therefore, broadly speaking, the vortex flow meter 101 includes: one or more sensors 131, 203, each configured to generate a signal representing fluid characteristics as fluid flows through the flow tube 103 via the blunt body 121; and a measurement processor 142 configured to use the signal to provide accurate flow rate measurements under various flow conditions. For example, in one or more embodiments, the vortex flowmeter is configured to generate a flow rate output representing the flow rate of the fluid entirely based on signals from the one or more sensors 131, 203, wherein the flow rate output is generated when the fluid has a Reynolds number less than or equal to about 2,000 (e.g., a Reynolds number of about 1,000, about 500, and / or about 250) and the flow rate output is fairly accurate (e.g., with an error percentage of less than 10%, or less than 5%, or less than 3%, or less than 2%).

[0036] In one exemplary embodiment, a vortex flow meter 101 is used in a fluid batching process. The fluid batching process involves discrete batch processing of fluid that flows continuously from a source to a destination. In this exemplary batching process, the flow meter 101 is used to determine the total amount of fluid flowing in each batch. Throughout the fluid batching process, a vortex sensor 131 detects vortices detached as the processed fluid flows past a blunt body 121, and a pressure sensor device 201 detects the pressure difference between upstream and downstream pressure connector locations L1, L2.

[0037] At the start of each batch, flow meter 101 uses a pressure differential signal from pressure sensor device 201 to determine the flow rate of the processed fluid during the initial ramp-up portion of the batch. The total volume of the processed fluid flow during the initial ramp-up portion of the process is calculated using the flow rate based on the pressure differential signal. The initial ramp-up portion of the batch ends when the frequency of the vortex signal exceeds the low flow cutoff frequency. After the initial ramp-up portion, during the intermediate portion of the batch, flow meter 101 uses a vortex signal from vortex sensor 131 to determine the flow rate of the processed fluid. The total volume of the processed fluid flow during the intermediate portion of the batch is calculated using the flow rate based on the vortex signal. In one embodiment, the intermediate portion of the batch ends when the frequency of the vortex signal drops below the low flow cutoff frequency. After the intermediate portion is completed, during the final ramp-down portion of the batch, flow meter 101 uses a pressure differential signal from pressure sensor device 201 to determine the flow rate of the processed fluid. The total volume of the processed fluid flow during the final ramp-down portion of the process is calculated using the flow rate based on the pressure differential signal. Although only three stages of flow rate measurement have been mentioned above, it should be understood that in some embodiments, the middle portion of the batch may be split into one or more additional stages with low process fluid flow, during which the amount of process fluid flow is determined using flow rate based on pressure differential signals.

[0038] In one embodiment of the batch processing process described above, the measurement processor 142 locally determines the amount of fluid flow during each of the initial ascending section, the intermediate section, and the final descending section, based on the determined flow rate based on the pressure differential signal and the flow rate based on the vortex signal, respectively. In another embodiment, the local measurement processor 142 outputs the flow rate based on the pressure differential signal and the flow rate based on the vortex signal to a remote processor during each section of the batch processing, and the remote processor determines the amount of fluid flow during each section of the batch processing. In either case, the total amount of processed fluid flow during the batch processing can be determined using the amount of fluid flow determined for each of the initial ascending section, the intermediate section, and the final descending section, based on the flow rate based on the pressure differential signal and the flow rate based on the vortex signal, respectively.

[0039] Example 1

[0040] To test the concept of using pressure differential across a bluff body to provide flow rate measurements, pressure connectors were formed in flow tubes 103 with diameters of 2 inches and 4 inches at two upstream locations L1, L1' and several downstream locations L2. During a set of tests (the results of which are described in Table 1 below), a pressure differential sensor was operatively connected to the 2-inch diameter flow tube 103 at an upstream pressure connector location L1' spaced approximately 0.59 inches UD from the upstream end face 121A of the bluff body 121 and at a downstream pressure connector location L2 spaced approximately 1.24 inches DD from the upstream end face 121A of the bluff body 121. The upstream connector locations L1' and L2 in the tests described in Table 1 are located in a circumferential region on the flow tube wall approximately perpendicular to the radial axis of the bluff body.

[0041] During another set of tests (the results of which are described in Table 2 below), the differential pressure sensor was operatively connected to a 2-inch diameter flow tube 103 at an upstream pressure connector location L1 on the upstream end face 121A of the blunt body 121 and at a downstream pressure connector location L2 spaced approximately 1.24 inches from the upstream end face 121A of the blunt body 121. The downstream connector location L2 in the tests described in Table 2 is located in a circumferential region on the flow tube wall that is approximately perpendicular to the radial axis of the blunt body.

[0042] The results of another set of tests are described in Table 3 below, in which the differential pressure sensor is operatively connected to a 4-inch diameter flow tube 103 at an upstream pressure connector location L1', spaced approximately 0.60 inches from the upstream end face 121A of the bluff body 121, and at a downstream pressure connector location L2, spaced approximately 1.88 inches from the upstream end face 121A of the bluff body 121. The upstream connector location L1' and the downstream connector location L2 in the tests described in Table 3 are located in a circumferential region on the flow tube wall approximately perpendicular to the radial axis of the bluff body.

[0043] During another set of tests (the results of which are described in Table 4 below), the differential pressure sensor was operatively connected to a 4-inch diameter flow tube 103 at an upstream pressure connector location L1 on the upstream end face 121A of the blunt body 121 and at a downstream pressure connector location L2 spaced approximately 1.88 inches DD from the upstream end face 121A of the blunt body 121. The downstream connector location L2 in the tests described in Table 4 is located in a circumferential region of the flow tube wall that is aligned with the blunt body.

[0044] Table 5 below describes the results of another set of tests in which the differential pressure sensor is operatively connected to a 4-inch diameter flow tube at an upstream pressure connector location L1', spaced approximately 0.60 inches from the upstream end face 121A of the blunt body 121, and at a downstream pressure connector location L2, spaced approximately 1.88 inches from the upstream end face 121A of the blunt body 121. The upstream connector location L1' and the downstream connector location L2 in the tests described in Table 5 are located in a circumferential region of the flow tube wall that is aligned with the blunt body.

[0045] During each test, a certain amount of water is directed through a flow meter into a calibration tank. The rate at which the calibration tank is filled is monitored to provide precise control measurements of the flow rate. For each test, the table below shows the weight of water supplied through the flow meter, the duration of water delivery through the flow meter, the median frequency of the vortex signal generated by the vortex sensor, the detected line pressure at the upstream pressure connector location, the measured line temperature, the controlled flow rate measurements (volume flow rate and flow velocity) determined using the control tank, the detected pressure difference between the two pressure connector locations, and the values ​​calculated for K and the discharge coefficient based on Equations 1 and 2 below.

[0046] Table 1: 2-inch flow tube; vertical pressure fittings at L1' and L2

[0047]

[0048]

[0049] Table 2: 2-inch flow tube; pressure fittings at L1 and vertical L2.

[0050]

[0051] Continued from Table 2

[0052] test 9 10 11 12 13 Total flow weight (lb) 201.306 155.31 151.178 151.102 132.864 Total flow time (sec) 139.78 132.236 180.331 318.36 517.667 Vortex frequency (Hz) 13.3 10.9 7.8 4.5 2.5 Upstream pipeline pressure (psig) 25.477 25.56 25.65 25.707 25.723 Pipeline temperature (F) 69.1 69.4 69.6 69.9 70 Controlling volumetric flow rate (GPM) 22.9 18.7 13.3 7.6 4.1 Control flow velocity (ft / sec) 2.5 2.0 1.5 0.82 0.44 DP (psi) 0.15 0.10 0.052 0.017 0.005 K 6.45 6.43 6.36 6.34 6.25 CoD 0.650 0.648 0.641 0.639 0.630

[0053] Table 3: 4-inch flow tube; vertical pressure fittings at L1' and L2

[0054]

[0055] Continued from Table 3

[0056]

[0057]

[0058] Table 4: 4-inch flow tube; pressure connector at L1, aligned with L2.

[0059]

[0060] Table 5: 4-inch flow tube; pressure connectors at L1' and L2 in a straight line.

[0061]

[0062] Continued from Table 5

[0063]

[0064]

[0065] Equation 1:

[0066]

[0067] in:

[0068] V = Flow velocity measured using a control tank;

[0069] DP = The measured pressure difference between pressure fittings

[0070] Equation 2:

[0071]

[0072] in:

[0073] A1 = Cross-sectional area of ​​the pipe;

[0074] A2 = Cross-sectional area of ​​the throat;

[0075]

[0076] gc = gravitational constant; ρ = density of the fluid.

[0077] When describing elements of the invention or its preferred embodiments (one or more) thereof, the articles “a,” “an,” “the,” and “the” are intended to mean that one or more elements are present. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that additional elements may be present in addition to those listed.

[0078] In view of the above, it can be seen that several objectives of the present invention have been achieved and other advantageous results have been obtained.

[0079] Since various changes can be made to the products and methods described above without departing from the scope of the invention, it is intended that all content contained in the above description should be interpreted as exemplary rather than restrictive.

Claims

1. A vortex flowmeter for measuring a flow rate of a fluid, the vortex flowmeter comprising: a flow tube; a bluff body positioned in the flow tube for shedding vortices in the fluid as the fluid flows through the flow tube; a vortex sensor configured to detect the vortices and generate a vortex signal representative of the detected vortices, the vortex sensor positioned on a portion of the bluff body; and a pressure sensor arrangement comprising one or more pressure sensors configured to detect a pressure differential in the fluid between a first location upstream of at least a portion of the bluff body and a second location downstream of the at least a portion of the bluff body and generate a pressure differential signal representative of the pressure differential.

2. The vortex flowmeter of claim 1, further comprising a measurement processor connected to the vortex sensor and the one or more pressure sensors to receive the vortex signal and the pressure differential signal, respectively, and wherein the measurement processor is configured to generate a flow rate signal representative of the flow rate of the fluid using at least one of the vortex signal and the pressure differential signal. the measurement processor is configured to compare a characteristic of at least one of the vortex signal and the pressure differential signal to a threshold value and selectively use the vortex signal to generate the flow rate signal when the determined characteristic is greater than the threshold value and use the pressure differential signal to generate the flow rate signal when the determined characteristic is less than the threshold value.

3. The vortex flowmeter of claim 2, wherein, the determined characteristic is a frequency of the vortex signal and the threshold value is a low flow cut-off frequency of the vortex flowmeter.

4. The vortex flowmeter of claim 3, wherein, the measurement processor is configured to determine a vortex signal-based measurement of the flow rate using the vortex signal and a pressure signal-based measurement of the flow rate using the pressure differential signal.

5. The vortex flowmeter of claim 4, wherein, the bluff body has an upstream end face and the flow tube has a longitudinal axis and an inner diameter, and wherein the first location is at least one of:

6. The vortex flowmeter of claim 1, wherein, a location on the upstream end face, and a location spaced a distance upstream along the longitudinal axis from the upstream end face, the distance inclusively ranging from about 0.0 times the inner diameter to about 4.75 times the inner diameter. the second location is spaced a distance downstream along the longitudinal axis from the upstream end face, the distance of the second location inclusively ranging from about 0.333 times the inner diameter to about 5.0 times the inner diameter.

7. The vortex flowmeter of claim 6, wherein, the pressure sensor arrangement comprises a differential pressure sensor unit including a sensing diaphragm having a first side and an opposing second side.

8. The vortex flowmeter of claim 1, wherein, a first passage configured to convey pressure from the first location to the first side of the sensing diaphragm; 9. The vortex flowmeter of claim 8, further comprising: and a second passage configured to convey pressure from the second location to the second side of the sensing diaphragm. the first passage comprises a hole formed in at least one of the flow tube and the bluff body, and the second passage comprises a hole formed in the flow tube.

10. The vortex flowmeter of claim 9, wherein, the flow tube comprises a single piece of material having a length, each of the first location and the second location positioned along the length.

11. The vortex flowmeter of claim 1, wherein, 12. The vortex flowmeter of claim 1, further comprising a measurement processor configured to generate a flow rate output representative of the flow rate of the fluid using at least one of the vortex signal and the pressure differential signal when the fluid has a Reynolds number less than 2000. ​ 13. A method of determining a total amount of fluid in a batch process, the method comprising: detecting, using a vortex sensor, vortices shed by a bluff body positioned in a flow tube of a vortex flow meter as the fluid flows past the bluff body during the batch process, wherein the vortex sensor is positioned on a portion of the bluff body; detecting a pressure differential across the bluff body during the batch process; determining a first amount of fluid that flowed past the bluff body during an initial portion of the batch process based on the detected pressure differential; determining a second amount of fluid that flowed past the bluff body during an intermediate portion of the batch process based on the detected vortices; and determining a third amount of fluid that flowed past the bluff body during a final portion of the batch process based on the detected pressure differential.

14. The method of claim 13, wherein, Detecting the pressure differential includes detecting a pressure differential in the fluid between a first location upstream of at least a portion of the bluff body and a second location downstream of the at least a portion of the bluff body.

15. The method of claim 13, further comprising defining the initial portion of the batch process as occurring when the fluid has a Reynolds number of less than 2000.

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