Showing papers on "Thermal mass flow meter published in 2004"

Method of mass flow control flow verification and calibration

Abstract: A method and apparatus for monitoring or calibrating a gas flow rate through a mass flow controller, for example, in a semiconductor fabrication process. A reference mass flow controller is disposed in a vent bypass loop for receiving gas flow from one of a plurality of mass flow controllers associated with a like plurality of supply gases. One of the gas supply mass flow controllers is selected and commanded to a specific gas flow rate. The gas flow through the selected mass flow controller also passes through the reference mass flow controller as the gas flows to a vent. Comparing the gas supply mass flow controller commanded flow rate with the actual flow rate as determined by the reference mass flow controller provides monitoring and calibration of the gas supply mass flow controller.

An apparatus and method for compensating a coriolis meter

Abstract: A flow measuring system is provided that provides at least one of a compensated mass flow rate measurement and a compensated density measurement. The flow measuring system includes a gas volume fraction meter in combination with a coriolis meter. The GVF meter measures acoustic pressures propagating through the fluids to measure the speed of sound αmix propagating through the fluid to calculate at least gas volume fraction of the fluid and/or the reduced natural frequency. For determining an improved density for the coriolis meter, the calculated gas volume fraction and/or reduced frequency is provided to a processing unit. The improved density is determined using analytically derived or empirically derived density calibration models (or formulas derived therefore), which is a function of the measured natural frequency and at least one of the determined GVF, reduced frequency and speed of sound, or any combination thereof. The gas volume fraction (GVF) meter may include a sensing device having a plurality of strain-­based or pressure sensors spaced axially along the pipe for measuring the acoustic pressures propagating through the flow.

Thermal characterisation of a direction dependent flow sensor

Abstract: A calorimetric sensor for detection of gas velocity and flow direction was constructed by sacrificial porous silicon micromachining technique. The sensing element contains four temperature sensing resistors arranged symmetrically around a central filament heater. Finite volume flow simulations (FVM) for velocity vector and temperature distribution around the system elements led to the conclusion that the laminar flow conditions, essential for accurate calorimetric sensing, can be maintained by adequate selection of device dimensions and channel depth. Predictions by the flow and thermal simulations were aimed at defining the optimum geometric design. The results of functional tests performed on the fabricated structure were interpreted in terms of changes of parameters in the thermal equivalent circuit of the device.

System to measure density, specific gravity, and flow rate of fluids, meter, and related methods

Abstract: A system (30) to measure fluid flow characteristics in a pipeline, meter, and methods includes a pipeline (3 1) having a passageway (3 7) to transport flowing fluid (4 1) therethrough, a process density meter (33) including at least portions thereof positioned within the pipeline (3 1) to provide flowing fluid characteristics including volumetric flow rate, fluid density, and mass flow rate of the flowing fluid (41), and a fluid characteristic display (35) to display the fluid characteristics. A process density meter (33) includes a vortex-shedding body (63) positioned within the pipeline (3 1) to form vortices and a vortex meter (65) having a vortex frequency sensor (103) to measure the frequency of the vortices and to determine the volumetric flow rate. The process density meter (33) further includes a differential pressure meter (84) positioned adjacent the vortex-shedding body (63) to produce a differential pressure meter flow rate signal indicative of the density of fluid (40) when flowing through the pipeline (3 1). The process density meter (89) also includes a thermal flow meter (43) positioned adjacent the vortex-shedding body (63) to produce a mass flow rate signal indicative of the mass flow rate of fluid (41) when flowing through the pipeline (3 1). The process density meter (89) produces an output of a volumetric flow rate, a flowing fluid density, and a mass flow rate to be displayed by the fluid characteristic display (35).

Method and flow meter for determining the flow rate of a multiphase fluid

Abstract: Method and apparatus for determining the flow rates and/or composition of a fluid comprising a multi-component mixture of a gas and at least one liquid in a pipe. Electromagnetic loss and phase measurements are performed in at least two directions of the pipe; the degree of annular flow is determined based on these measurements; the permittivity of the flow mixture is calculated, including corrections for the degree of annular flow; the mixture density is measured and compensated for the degree of annular flow; the temperature and pressure are obtained; the velocity of liquid and gas are determined, and based on the knowledge of densities and permittivities of the components of the fluid mixture, and the result from the above steps, the volume and mass flow rates of the gas and liquid(s) of the fluid mixture are calculated.

Self-tuning ultrasonic meter

Abstract: A method and related ultrasonic meter identify and correct for transit time errors such as peak switch errors. The method includes calculating values for a set of diagnostics from measurements of the fluid flow, including transit time measurements. Based on the values for the diagnostics, and whether and how they fall outside of their respective ranges, the meter can identify a variety of problems with the meter or fluid flow, such as whether there has been an intermittent peak switch, a permanent peak switch, or the presence of noise, velocity pulsation in the fluid flow, temperature stratification, or other problem. In the event there is a problem with the meter, the meter self-tunes in order to minimize the chances of the problem happening again.

Differential pressure means for a gas meter arrangement, comprising an improved flow geometry

Abstract: A differential pressure system and a gas meter arrangement for precisely measuring a gas consumption by a gas meter is provided. A previously known gas meter is disposed in a bypass comprising a differential pressure system in the gas pipe for measuring a volumetric flow rate inside the gas pipe. The differential pressure system includes flow ducts having decreasing diameters as the radial position increases starting from a central axis of the differential pressure system. Examples of execution include inlet ports and/or outlet ports of the flow ducts which are provided with a specific countersink angle (α), and an equidistant, concentric arrangement of flow ducts on the cross-sectional area of the differential pressure system. This has the advantage of increasing the differential pressure at a low volume flow rate, reducing the differential pressure at a high volume flow rate, and generally creating an improved linearity across the entire measurement range between the volume flow rate in the bypass and the volume flow rate in the gas pipe, among other advantages.

Coriolis mass flow, density and temperature sensing with a single vaccum sealed mems chip

Abstract: A new microfluidic system for measuring the mass flow rate, dose, chemical concentration, fluid density, specific gravity and temperature has been developed. Vacuum packaged, resonating silicon microtubes are employed to form both a Coriolis mass flow and density sensor. The micro Coriolis mass flow sensor has 10 times the resolution of the best commercially available macro Coriolis mass flow sensors. An onchip temperature sensor (RTD) has been added to the microchip, enabling accurate fluid temperature monitoring. At constant temperature the density resolution/or output stability approaches 1 over 1 million (6 digits) in the new system. Also a new method of chip-level gettering was developed to achieve the milliTorr pressures needed for adequate resonator signal quality for the vacuum packaged microsensors. Applications for both mass flow measurements and density sensing are discussed.

Method and system for a mass flow controller with reduced pressure sensitivity

Abstract: Systems and methods for mass flow controllers which minimize false flow conditions and display a reduced sensitivity to pressure transients are disclosed. Pressure gradients that exist within the volume of a mass flow controller fluid path are minimized in order to limit the potential energy contained in compressed or pressurized process gas. Additionally, process gas pressure may be monitored using a pressure sensor. This pressure signal is utilized in conjunction with a control algorithm to cancel the detrimental effect of certain flow components. These mass flow controllers may be used as drop in replacements for legacy mass flow controllers and reduce the cost of gas sticks due to elimination of discrete components such as pressure regulators, gas filters, pressure transducers, local pressure displays, isolation valves, seals, etc.

Method and apparatus for determining flow pressure using density information

Abstract: A method and apparatus is disclosed that determines the density of a material flowing through a Coriolis flow meter. The density is used to infer the pressure of the flowing material. The inferred pressure may be used to correct for the secondary pressure effect in the Coriolis flow meter or may be reported to an external device.

Vibrating tube mass flow meter

Abstract: A vibrating tube meter (10) measures the density, mass flow rate or viscosity of a fluid material including a vibration section. An exciter (30b) induces vibrations in the tube (12) vibration section at a resonance frequency. A motion sensor detects motion of the tube from the induced vibrations. A helical coil spring (20) has opposing ends coupled to the tube with the tube positioned within the interior of the coil spring. An external housing is rigidly coupled to the tube inlet end and outlet end and has a mass selected to provide a suitable nodal mass for the tube vibration section and spring element. Temperature sensors (40a, 40b, 40c) are coupled to the tube, the spring element and the external housing (24). A pressure sensor (42) is coupled to the tube. A processor (38) includes a drive amplifier and a novel adaptive filter and processes signals form the sensors. A novel viscosity integrator (36) processes signals from the motion sensors, temperature sensors and the pressure sensor to accurately calculate density, mass flow rate and viscosity of the fluid material as well as percent concentration of a solute in the fluid material.

Gas flow meter for application in medical equipment for respiratory control: study of the housing

Abstract: The study of the housing of a gas flow meter for use in medical equipment for respiratory control will be presented in this paper. The sensor is of the thermal type with dimensions 1.4 mm ×0.9 mm. The housing is developed so as to assure conditions of laminar flow in a flow range from −200 to +200 standard liters per minute (SLPM). An analytical approach is first used to determine the main housing configuration. The type and the position of a bypass tube, which is fixed to the main flow tube, are studied in detail. Extensive simulations of the flow in different housing configurations and different conditions at the inlet and outlet of the housing were performed, using the finite element analysis (FEA) software package ANSYS. The optimum housing was finally fabricated and evaluated in oxygen flow. Excellent agreement of experimental results with simulation was obtained.

Flow monitoring using flow control device

Abstract: A method for determining the flow rate of a fluid, having a liquid fraction and a gas fraction, having the steps of: measuring the pressure and temperature of the fluid at a flow control device through which said cyrogenic fluid passes; inputting the measured pressure and C v into an algorithm; and performing a single or multi-step iteration to determine a fluid mass flow rate of the fluid through the flow control device using the algorithm that relates the mass flow rate of the fluid to the C v , and mass densities of the liquid fraction and the gas fraction of the fluid which are a function of the measured pressure, and temperature. A system is also provided.

Development and testing of a novel single-wire sensor for wide range flow velocity measurements

Abstract: Thermal flow sensors with a wide dynamic range, e.g. 1:1000 and more, are currently not available in spite of the great demand for such sensors in practical fluid flow measurements. The present paper introduces a sensor of this kind. The new sensor is mechanically the same as the 'sending' wire of the two-wire thermal flow sensor described by Durst et al, but it is excited by discrete, widely separated, square waves of electrical current rather than a continuous sinusoidal current. The nominal 'output' of the new sensor is the increase in wire temperature so that an integral of the resistance over the pulse length can be used for measurements. This 'output' is a function of the time constant ('thermal inertia') of the heated wire and thus also of the velocity of flow. The time constant decreases as the flow velocity increases, while the heat transfer increases. At very low flow velocities the response is determined almost entirely by the time constant of the wire while at high velocities the device acts almost like a 'constant current' hot-wire anemometer. That is, the effect of thermal inertia augments the output signal of the basic hot wire, thus increasing the flow rate range/sensitivity of the device, especially at the low-velocity end, above than that of a simple hot-wire flowmeter. The sensor described here was developed for slowly changing unidirectional flows, and uses one wire of 12.5 µm diameter. It is excited at 30 Hz frequency and its usable flow velocity range is 0.01–25 m s−1.

Fluid flow measurement unit, e.g. for HVAC applications, has a bypass line with a flow sensor and a main line which incorporates a flow former in order to ensure a linear relationship between pressure drop and flow rate

Abstract: Flow measurement unit for a measuring a fluid flow rate has a bypass line (3) from a main flow line along in which there is a flow sensor (9) that derives the flow rate from the measured pressure drop. A flow former (20, 22, 23, 26) is incorporated in the main line to form the flow in the area of the bypass. The seqential zones within the area of the bypass line has a flow shape such that there is an almost linear relationship between the pressure drop over the length of the bypass line and the flow rate in the main line (2).

Compensation method and apparatus for a coriolis flow meter

Abstract: Method and apparatus (121) for providing temperature flow rate compensation for a Coriolis flow meter. The described compensation compensates both flow calibration factor and the nominal time delay, commonly called 'zero' in the art. After a Coriolis flow meter is installed into a process, whether for calibration or for actual process use, it need only be zeroed once over its lifetime following its installation. This is a significant improvement over prior Coriolis flow meters that may need to be re-zeroed after minor changes in pressure, temperature, or installation.

Engine suction air flow rate measuring device

Abstract: The present invention embodies an engine intake air flow meter measuring a mass flow rate based on measured pressures in an intake pipe, such as a pressure difference between two points and a pressure at a point. Operations for integration and double integration of the pressure difference are performed, and both values of integration and double integration are corrected at a moment when an air flow rate is detected reaching a zero based on a value of a time derivative of the pressure. Then a mass flow rate and an amount of air are calculated by the value of integration and the value of double integration respectively.

Deployable mandrel for downhole measurements

Abstract: The disclosed apparatus comprises a phase fraction meter and a compliant mandrel deployable within a production pipe, and may further comprise a flow velocity meter. The mandrel allows the determination of the phase fraction for a fluid comprising three phases by providing an additional cross sectional compliance within the conduit, thereby allowing the density of the fluid to be determined. The mandrel also provides a specified blockage through the flow velocity meter, thereby increasing flow velocity through the meter. This allows flow rate measurements in conditions under which flow velocity in the under-restricted cross-sectional area of the pipe would normally be very low. Further, the mandrel can provide a specified restriction in the pipe, i.e., a venturi. By measuring the differential pressure across the venturi and utilizing the measured fluid velocity from the flow velocity meter, the density of the fluid mixture can be calculated. This calculated density can be used in conjunction with other measurements to determine phase fractions or to double check or to calibrate the phase fraction meter. The mandrel can be deployed without removing the meter from the conduit, allowing for easy adaptation to changing flow parameters and fluid compositions.

How a Coriolis mass flow meter can operate in two phase (gas/liquid) flow

Abstract: It has been well documented over many years that Coriolis mass flow meters are unable to perform well when presented with two-phase (gas/liquid) flow. There are two aspects to the problem: it can be difficult to maintain flowtube oscillation at higher levels of two-phase flow (typically 2-20% of gas by volume), and even at low levels of gas entrainment, where the flowtube continues to resonate, mass flow errors can be severe. This paper provides an overview of how to provide good Coriolis mass flow and density measurements in two-phase flow, and explains the central role of the flowtube drive control system. Two classes of application having widespread industrial significance are addressed: the problem of batching to or from an empty Coriolis flowtube, and dealing with continuous two-phase flow.

Attitude error self-correction for thermal sensors of mass flow meters and controllers

Abstract: A system for and method of compensating for attitude sensitivity of at least two thermal sensor coils mounted on a tube through which a fluid flows along a common axis of flow for use in generating a flow measurement signal representative of the flow of fluid through the tube is disclosed. One of the coils is adapted in provide thermal energy to the fluid flowing through the tube at an upstream location so as to establish and measure the upstream temperature of the fluid at the upstream location, and one of the coils is adapted to measure the downstream temperature of the fluid at a downstream location. The flow measurement signal is a function of the difference between the measured upstream and downstream temperatures. The system includes structure for, and the method includes the steps of measuring the force of gravity in the direction of the common axis; and modifying the flow measurement signal as a function of the measured force of gravity.

Application of Sonar-Based, Clamp-on Flow Meter in Oilsand Processing

Abstract: Data is presented demonstrating the applicability of sonar-based, clamp-on flow measurement to several, longstanding flow measurement challenges within the oilsands industry, including hydrotransport, coarse tailings, and bitumen froth flow lines. Sonar-based flow measurement technology was developed and field proven in the oil and gas production industry over the last five years and provides robust, accurate volumetric flow rate measurement for a broad range of process fluids, slurries, pipes sizes and flow conditions. Sonar-based flow metering technology utilizes an array of sensors to listen to, and interpret, unsteady pressure fields within process flow lines. The methodology is implemented using strain-based sensors which clamp-on to existing process piping. Sonar-based flow monitoring systems determine volumetric flow rate by measuring the speed at which self-generated, coherent flow structures convect past the sensor array. Using similar sonar-based array processing techniques as those used for volumetric flow, sonar-based flow meters can also determine entrained air (or any other gas) levels by measuring the speed at which sound propagates within the process flow lines. The speed of sound in the process flow lines provides an accurate and robust, clamp-on method for determining entrained air levels in aerated liquids. Data is presented showing entrained air levels on a 16-inch diameter froth line exiting a steam-driven deaerator.

Laminar flow meter or controller

Abstract: Volumetric flow meters, volumetric flow controllers, mass flow meters, and mass flow controllers using a transverse laminar flow assembly are described. The flow assembly may be constructed from a plurality of open and/or closed slices or layers stacked upon one another and held together in compression by through bolts or another means. Meter or flow controller accuracy may be aided by use of flow conditioning features preceding an axial bore of the transverse flow assembly including one or more of a deflector, filter and nozzle.

Mass flow meter with symmetrical sensors

Abstract: A mass flow meter employs discrete chip-type temperature sensors to sense a fluid flow rate. The sensor can be a semiconductor chip such as SiC or silicon, or thin film tungsten on an AlN substrate. The sensors can be distributed symmetrically with respect to the conduit through which the fluid flows, and can be connected in a four-sensor bridge circuit for accurate flow rate monitoring. An output from the mass flow meter can be used to control the fluid flow.

A method and apparatus for proving flow meters

Abstract: A method and apparatus is disclosed that determines the time delay (202) between the actual flow and the measured flow in a flow meter. The time delay is used to shift the flow measured by the flow meter to correspond to the actual flow measured by a prover or calibration system. In this way an accurate comparison is made between the flow measured by the flow meter and the flow provided by the prover.

Mass flow meter

Abstract: The invention relates to a mass flow meter for flowing media, which operates according to the Coriolis principle. At least one oscillator and at lest one sensor that detects Coriolis forces and/or oscillations based on Coriolis forces are mounted on a Coriolis measuring tube. As evaluation unit determines a measured flow valve from the measurement signal of the sensor. Means are provided which make it possible to detect zero flow in the measuring tube regardless of the detection of Coriolis forces and/or oscillations based on Coriolis forces and generate a corresponding measurement signal. Said means can comprise a sensor for measuring a flow according to a magnetic-inductive measuring method, the method for measuring the difference in propagation time or the Doppler method with the aid of noise signals, a differential pressure method, a calorimetric method, and/or a float-type measuring method, for example, whereby the problem or a measuring error caused by zero displacement is resolved in mass flow meters operating according to the Coriolis principle.

Gas Supply Facility Of A Chamber And A Fethod For An Internal Pressure Control Of The Chamber For Which The Facility Is Employed

Abstract: The present invention makes it possible to prevent substantial reduction of flow rate control accuracy in a small flow quantity range, to achieve an accurate flow rate control over the entire range of a flow rate control, and also to allow control of a wide pressure range of a chamber with an accurate flow rate control. Namely, with a gas supply facility having a plurality of pressure type flow controllers connected in parallel and a controller to control operation of pressure type flow controllers to supply a desired gas exhausted by a vacuum pump to a chamber while controlling its flow rate, one pressure type flow controller is made to be a controller to control a gas flow rate range up to 10% of the maximum flow rate to be supplied to a chamber, while the remaining pressure type flow controllers are made to be ones to control the rest of the gas flow rate range.

Inferential densometer and mass flowmeter

Abstract: A system for measuring the density and mass flow rate of a fluid stream. The system generally comprises a volumetric flow device, a momentum device, and a data processing device. The present invention also provides methods for using such system.