Showing papers on "Volumetric flow rate published in 1980"

Validity of Cubic Law for fluid flow in a deformable rock fracture

Abstract: The validity of the cubic law for laminar flow of fluids through open fractures consisting of parallel planar plates has been established by others over a wide range of conditions with apertures ranging down to a minimum of 0.2 µm. The law may be given in simplified form by Q/Δh = C(2b)3, where Q is the flow rate, Δh is the difference in hydraulic head, C is a constant that depends on the flow geometry and fluid properties, and 2b is the fracture aperture. The validity of this law for flow in a closed fracture where the surfaces are in contact and the aperture is being decreased under stress has been investigated at room temperature by using homogeneous samples of granite, basalt, and marble. Tension fractures were artificially induced, and the laboratory setup used radial as well as straight flow geometries. Apertures ranged from 250 down to 4µm, which was the minimum size that could be attained under a normal stress of 20 MPa. The cubic law was found to be valid whether the fracture surfaces were held open or were being closed under stress, and the results are not dependent on rock type. Permeability was uniquely defined by fracture aperture and was independent of the stress history used in these investigations. The effects of deviations from the ideal parallel plate concept only cause an apparent reduction in flow and may be incorporated into the cubic law by replacing C by C/ƒ. The factor ƒ varied from 1.04 to 1.65 in these investigations. The model of a fracture that is being closed under normal stress is visualized as being controlled by the strength of the asperities that are in contact. These contact areas are able to withstand significant stresses while maintaining space for fluids to continue to flow as the fracture aperture decreases. The controlling factor is the magnitude of the aperture, and since flow depends on (2b)3, a slight change in aperture evidently can easily dominate any other change in the geometry of the flow field. Thus one does not see any noticeable shift in the correlations of our experimental results in passing from a condition where the fracture surfaces were held open to one where the surfaces were being closed under stress.

Isothermal flow of viscous liquids in corotating twin screw devices

Abstract: A mathematical model is derived for isothermal flow of a Newtonian liquid through corotating twin screw equipment. Two different flow regimes are studied. In the first, channels of twin screw equipment are completely filled with liquid, generate a pressure gradient, and provide a discharge pressure at the end of the pump. Equations are given for drag flow rate, pressure backflow rate, and flow rate through the nip zone. It is shown how the analysis of single screw pumps can be modified for twin-screw pumps. In the second regime channels are partly full, which is the case with extraction equipment. Equations show how the degree of fill in the equipment changes with flow rate, speed, and dimensions.

Calibratable system for measuring fluid flow

Abstract: A pair of mass flow sensors are used to separately monitor the mass flow rates of a carrier gas and of a mixture of carrier gas and source vapor formed a mixing station. The rates are compared, for example by substracting the carrier gas flow rate from the mixture flow rate, to generate a signal representing the mass flow rate of the source vapor. Flow of the carrier gas to the mixing station is modulated in accordance with the difference between this signal and a command signal representing a predetermined flow rate. The system can be calibrated by flowing the carrier gas alone through both sensors, by passing the mixing station, and adjusting the signal for one or both sensors so that the signals from both sensors are equalized.

Bulk solids: storage, flow and handling

Abstract: Chapters in this book discuss: storage and flow of bulk solids; determination of flow properties of bulk solids; determination of hopper geometry; analytical solutions for parameters used in bin design; wall loads in mass-flow bins; the Jenike method for predicting bin wall loads; flow rate of bulk solids from mass-flow bins; segregation and blending; estimating feeder loads; and flow of solids through transfer chutes.

Control system and apparatus for producing compatible mixtures of fuel gases

Abstract: In a fuel gas distribution system, at least one fuel gas stream is mixed with air to achieve a heating value equivalency which is the same as that of another fuel gas having a different heating value and specific gravity. The heating value equivalency is defined as the heating value of a fuel gas in heat units per unit of volume divided by the square root of the specific gravity of the gas. A control system is employed to measure the specific gravity, pressure, temperature and flow rate of the first gas in a first gas stream, and the pressure, temperature and flow rate of air in a second stream, and to control the flow rate of the gas from the first stream and air from the second stream such that the resulting mixture from the two streams has the same heating value equivalency as that of a third gas which was used to adjust the gas burners for use in that system.

Effects of Column Length, Particle Size, Flow Rate, and Pressure Programming Rate on Resolution in Pressure-Programmed Supercritical Fluid Chromatography

Abstract: In pressure-programmed supercritical fluid chromatography, particle diameters in the range of 122 ..mu..m to 205 ..mu..m were found to yield maximum resolution of oligomers of 800 molecular weight polystyrene when 5% isopropanol in pentane was employed as a mobile phase at 240/sup 0/C. The ability of a given column to achieve maximum resolution was found to depend on the ratio of the pressure-programming rate to the average flow rate of the mobile phase. Resolution could be increased while analysis time decreased, when a fast pressure-programming rate was used in conjunction with a high flow rate. In addition, due to the unusual thermophysical properties of the super-critical mobile phase, operation at linear velocities that are generally considered to be in the region of turbulent flow were found to be necessary for maximum resolution.

Device of integrating a small amount of flow of fluid for leak detection

Abstract: A leak detection device for integrating a small amount of flow of fluid having a measuring unit capable of generating a series of pulses, a space between the pulses being varied in inverse proportion to the measured flow rate of fluid, a timer arranged to generate periodic timing signals for a deciding unit time interval for taking a measurement, a first integrating unit, a leakage decision unit and a second integrating unit. The first integrating unit is connected to receive and count the series of pulses from the flow measuring unit and to be reset by the respective timing signals from the timer. The leakage decision unit compares the corresponding value of the measured flow rate from the first integrating unit with a predetermined reference value, and the second integrating unit is connected for integrating the corresponding value of the measured flow rate from the first integrating unit in response to the leakage detection signals.

Method of automated fluid flow measurement

Abstract: An automated fluid flow measurement system employs two temperature sensitive silicon resistors having tracking temperature coefficients. The resistors have equal impurity concentration but different values of resistance. The first temperature sensitive resistor is employed to measure the temperature of a flowing fluid. The second temperature sensitive resistor is electrically heated to a temperature at a predetermined amount greater than the measured temperature of the fluid. Because the rate of heat transfer from the heated temperature sensitive resistor to the fluid depends upon the rate at which the fluid passes this temperature sensitive resistor, the power required in order to maintain the predetermined temperature difference in the second temperature sensitive resistor is a measure of the flow rate of the fluid. The automated fluid flow measurement system also includes an active self-balancing Wheatstone bridge circuit which automatically applies the required amount of power to the second temperature sensitive resistor in order to maintain the temperature difference and further automatically supplies a signal proportional to this applied power and therefore proportional to the flow rate.

Slurry producing apparatus

Abstract: Apparatus and method for producing a slurry. The apparatus includes a slurry reservoir, a closed circuit and a pump for circulating slurry from the reservoir through the closed circuit and back to the reservoir. Means are provided for introducing both particulate and liquid materials into the closed circuit for forming the slurry. A first control circuit provides a particulate flow rate signal indicating the rate of flow of particulate material into the closed circuit. A flow meter provides a liquid flow rate signal indicative of the actual flow rate of liquid material into the closed circuit. A density measuring and control circuit measures the density of slurry flowing within the closed circuit and provides a density signal indicative of the difference between the measured density of slurry and a desired desity based upon data inputted to the density measuring and control circuit. A ratio circuit, receiving the particulate flow rate signal and density signal generates a desired rate of flow signal indicative of a desired flow rate for the introduction of the liquid material into the closed circuit. This desired rate of flow is a function of desired slurry density, actual density and the particulate flow rate. A liquid control circuit receives the desired rate of flow signal from the ratio circuit and the liquid flow rate signal from the flow meter and generates a feedback signal for controlling the actual rate of flow of liquid material into the closed circuit to maintain precise control over the actual density of slurry in order to achieve the desired slurry density.

Method and apparatus for treating fluent materials

Abstract: A process for heating fluids to a relatively high temperature, such as sterilization temperature, in which the fluid, such as a liquid, is heated by direct contact with steam while it is in the form of a very thin, free-falling film or a continuous falling stream so that heating of the fluid is accomplished without the fluid coming into contact with any surface and particularly metal surfaces which are hotter than the fluid product being heated and with minimum agitation and turbulence of the fluid product. This procedure enables maximum and uniform heat penetration in a minimum time interval with the film or stream being maintained as thin as possible and unbroken by introducing steam at a relatively low velocity in a large volume vessel. A flow control is incorporated into the apparatus to maintain a constant flow rate of fluid and to maintain a constant and critical fluid level in the bottom portion of the large volume vessel with the flow characteristics of the apparatus and the internal forces produced by the apparatus serving to counterbalance each other to provide a relatively simple but yet accurate flow rate and liquid level controls for the fluid being heated.

Capillary flow of linear polyethylene melt: sudden increase of flow rate

Abstract: During the oscillatory flow of linear polyethylene (HDPE) melt through a capillary, the shape of the extrudate varies periodically with time: sharkskin, plug and rough. This paper deals with the transition between increasing and decreasing pressure. At that transition, the flow rate through the tube is suddenly and intensively increased. We present a theoretical analysis which is in good agreement with experiment. The “slip” at the wall is held to be a consequence of and not the cause of phenomenon. The radial profile of the shear rate is described by means of Dirac's delta function.

Method and apparatus providing uniform resin distribution in a coextruded product

Abstract: Disclosed is a method and apparatus for ensuring uniform distribution of higher and lower viscosity or flow rate resins in a product produced by a coextrusion process. A flow restriction is provided in the flow path of the lower viscosity or flow rate resin to increase the pressure drop of this resin as it passes through a coextrusion die. The increased pressure drop introduced by the flow restriction causes the lower viscosity or flow rate resin to be more uniformly distributed in the extruded product. A specific die construction providing a uniform resin flow channel within the die is also described.

Process and apparatus for the combustionless measurement and/or control of the amount of heat fed to gas consumption devices

Abstract: A process and apparatus for the combustion-less measurement and/or regulation of the feeding of quantities of heat to gas combustion devices, particularly natural-gas combustion devices. A fuel gas or a partial stream of the fuel gas is fed through a fuel gas line containing at least one flow resistor which produces a laminar flow and a pressure drop. The gas volume flow and/or the pressure drop over at least one flow resistor is measured by a volume flow metering device and a difference pressure regulator, respectively, the pressure drops and/or volume flows which are not measured being maintained constant. A device compensates for the influence of temperature on the system is compensated. The measured value(s) in accordance with the formula described in the specification f (H)= a+b·n.sup.c ·ρ.sup.d is a measure of the heat content of the flowing gas and results in a signal which serves for measurement and/or regulation.

Methods of measuring fluid viscosity and flow rate

Abstract: A method of measuring the flow rate of a fluid through a conduit by means of a sonic flow meter employing the steps of measuring the speed of sound transmission through the fluid from an upstream point in the conduit to an opposed downstream point, measuring the speed of sound transmission through the fluid from the downstream point to the upstream point, subtracting the two measurements to obtain a liquid flow rate indication, adding the two measurements to obtain the fluid sound velocity, measuring the temperature of the fluid in the conduit, determining a measurement of the fluid viscosity from the fluid speed of sound transmission and the temperature, and correcting the determined fluid velocity utilizing the detected fluid viscosity.

Flow rate measuring apparatus having vortex-generating element and hot wire element

Abstract: Apparatus for measuring the velocity of the rate of flow of a flowing fluid, comprising a vortex-generating element (20) disposed in a flow tube to create a Karman vortex street in the fluid flow, a hot wire element (22,22') disposed in the flow tube, transducer means (22,22',30,50,62) for producing first flow rate signal based on the frequency of shedding of Karman vortices from the vortex-generating element (20) and second flow rate signal (30,40,64) based on the cooling effect of the flowing fluid on the hot wire element (22,22') and signal selection means (68,70) for selectively putting out the first signal under steady flow conditions and the second signal under pulsating flow conditions. Preferably the hot wire element (22,22') is made to serve also as the probe element for detection of the vortex generation frequency, and the first signal under steady flow conditions is utilized alsoto calibrate the second signal.

Method and apparatus for measuring and controlling fluid flow rates

Abstract: To measure the flow rate of a fluid in a pipe, a heat pulse is injected into the fluid by a heat pulse generator, and the time of flight of the pulse between the generator and a sensor is measured. Arrival of the pulse at the sensor is determined by detecting a selected temperature level of the ascending flank of the pulse, and a predetermined temperature level of the descending flank is then detected to initiate generation of the next subsequent pulse. Since the temperature of the descending flank generally represents the temperature of the fluid between the heat pulse generator and sensor, the technique ensures that the accuracy of each successive flow rate measurement is not affected by residual heat from the preceding measurement, and yet enables measurements to be obtained at maximum frequencies. In one embodiment the measurements are used to control the flow rate of the measured fluid, and in another the flow rate of fluid in one or more additional pipes.

An Experimental Study on the Dynamic Response of a Vertical Cantilever Pipe Conveying Fluid

Abstract: Transverse vibrations of elastic pipes conveying a fluid have been observed in pipelines and heat exchangers. These fluid-induced vibrations can be a serious problem and in some incidents have caused structural failure resulting in environmental damage and economic loss. For offshore applications such as marine risers, the Ocean Thermal Energy Conversion Plant and deep ocean mining vacuums, the problem is compounded by the existence of vortex shedding, wave excitations, currents, and platform motions. An experimental study was conducted to investigate the effects of internal flow rate and the depth of immersion on the dynamic response of a vertical cantilever pipe discharging a fluid. It was found that the internal flow rate and the surrounding fluid have a significant effect on the natural frequencies of the system. Specifically it was found, that depending on the relative value of the forcing frequency, in comparison to the system natural frequencies, an increase in flow rate may not necessarily result in a larger system response. Conversely, an increase in the length of pipe immersion does not necessarily decrease the response of the system. It is also observed that with increasing flow rate, an auspicious increase in the response of the higher harmonics is noted, indicating an increase fluid coupling of the system. System natural frequencies were observed to decrease with increasing flow rate.

Method and apparatus for monitoring fluid flow

Abstract: A method and apparatus for monitoring conditions in a fluid flow path so that the composition and operation of the flow path can be determined is disclosed. The apparatus includes a fluid flow detector, such as a gas flow logging tool, which detects the velocity at which a fluid, such as a gas, flows along the fluid flow path, such as a gas injection conduit used in a gas lift program for extracting oil from a well. The monitoring apparatus also includes a pressure detector and a temperature detector. Each of these detectors provides a respective electrical signal to a recorder unit, such as a strip chart recorder, for creation thereby of respective logs. The logs generated by the recorder unit permit qualitative and quantitative analyses of identifiable fluid flow path phenomena, such as the locations of valves and the volumetric flow of the fluid, to be made.

Signal generator for electromagnetic flowmeter

Abstract: A signal generator for reducing the influence of fluctuations in flow rate distribution in a fluid passing through the flow tube of an electromagnetic flowmeter, which fluid intercepts a magnetic field therein to induce an emf which is transferred to the meter electrodes, thereby yielding a signal as a function of flow rate. To this end, the tube is provided with auxiliary electrodes disposed at arbitrary positions at which the potentials developed thereon are equal to each other when the existing flow rate distribution is symmetrical with respect to the flow tube axis, the auxiliary electrodes being interconnected.

Mass flow meter with reduced attitude sensitivity

Abstract: There is shown and described a mass flow measuring system for measuring the flow rate of a fluid in a sensing tube over a wide ambient temperature range and with low sensitivity to attitude change. The improvement is directed to the insulating material which is used with the system and the means for producing an isothermal plane around the system.

Apparatus and method for determining flow characteristics of a fluid

Abstract: A method and apparatus for determining the flow rate and other flow characteristics of a polyphase fluid or a turbulent single-phase fluid flowing in a conduit are disclosed. Two differential pressure sensors are provided, each having two pressure ports sensitive to local pressure variation in the fluid. The pressure ports are maintained in a predetermined spatial relationship and in a predetermined orientation relative to the general direction of the flow. The detection signals from the respective sensors are correlated to obtain the flow rate. Additionally, a selected one of the detection signals is processed to obtain other flow characteristics. One of these other flow characteristics, the type of flow, is useful in facilitating the determination of the flow rate.

Flow rate sensor

Abstract: A flowmeter for measuring the flow rate of fluids, having a range from a very low to a very high value. An impeller is located in a pipe for rotation with the flow of fluid. Metallic vanes of the impeller pass through the field of an inductor which is in a series circuit with a capacitor. An oscillator applies a signal at the series resonant frequency of the capacitor and inductor. The envelope of the resulting high voltage signal across the inductor is detected, filtered, and the resulting output pulses in excess of a minimum threshold can be applied to a counting apparatus for establishing the flow rate with high sensitivity. Since the spacing between the impeller and pickup is not critical, a meter is provided which does not clog with magnetic or non magnetic particles suspended in the fluid to be measured. The meter pickup can also be used to sense the rotation rate of wheels or the like having metallic discontinuities, whereby the speed of a vehicle, the rotation rate of a shaft, etc. can be determined.

Chemical conversion of C 2 F 6 and uniformity of etching SiO 2 in a radial flow plasma reactor

Abstract: Plasma etching of SiO2} with C2}F6} in a radial flow reactor was investigated to determine relationships between chemical aspects of the discharge, operating parameters such as power and flow rates, and uniformity of etching over a large area. The chemical conversion of C2}F6} in the discharge was monitored by infrared spectrometry of the exhaust gases, as a function of discharge power and gas flow rate. The input gas was found to be transformed mainly to CF2} and a polymeric material, and at sufficiently long residence times (∼1 sec) a "steady state " was achieved. At the steady state condition C2}F6} was found to be ∼60% converted. The amount of conversion was not influenced by the presence of SiO2} being etched, however, the production of CF4} was reduced by the presence of SiO2}. For a known flow rate and reactor dimensions the concentrations of species as a function of radial position in the reactor were calculated. It was demonstrated that the etch rate of SiO2} was dependent on this radial concentration profile. Uniform etching was obtained if the etching zone lay entirely within the "steady state" region of the discharge. Reduced etch rates or polymerization on the substrates was observed if large concentration gradients (rich in C2}F6}existed in the etching zone. It was concluded that the etch rate of SiO2} is dependent then on the local gas composition in the discharge, and can be manipulated by means of adjusting power and gas flow rates.

An automated controlled-flow air infiltration measurement system

Abstract: A description is presented of an automated, controlled flow air infiltration measurement system. This system measures total air flow, a volume per unit time, due to infiltration in a test space. Data analysis is discussedand the mixing problem is analyzed. Different modes of operating the system are considered: (a) concentration decay, (b) continuous flow in a single chamber, and (c) continuous flow in a multichamber enclosure. Problems associated with the use of nitrous oxide as a tracer gas are described.

Liquid metering unit responsive to the weight of the metered liquid

Abstract: A process and apparatus are disclosed for the accurate measurement and control of liquid flow at low flow rates. The invention is particularly applicable to the measurement and control of continuous liquid blending operations, e.g. gasoline blending, in which a liquid additive, e.g. tetraethyl lead, is fed into a continuously flowing liquid stream, the additive being added in precisely controlled amounts requiring precise control of liquid flow at very low flow rates. According to the invention the additive is fed from a stock tank 1 alternately into one or the other of two reservoirs 6, 7 connected in parallel between the inlet line 3 from the stock tank and an outlet line 20. As the one reservoir is being charged, the other is being discharged through the four-way valve 5 to the outlet. Flow through the outlet line 20 is controlled by a valve 22. In accordance with the invention, the mass of liquid is continuously monitored by means in each reservoir sensitive to the weight of liquid in the reservoir which emits a signal proportional to the mass of liquid in the reservoir. This signal is passed to a differentiator for conversion into a flow signal proportional to the mass flow rate. The flow rate signal is fed to a ratio controller 36 for comparison with a demand signal fed via line 39 representing the desired flow rate. Depending on the difference, if any, between the flow signal and the demand signal, a control signal is sent via line 35 to automatically adjust the setting of the valve 22 and bring the flow rate to the desired value.