Showing papers on "Pressure drop published in 1983"

Simulation of Naturally Fractured Reservoirs

Abstract: A three-dimensional, three-phase reservoir simulator was developed to study the behavior of fully or partially fractured reservoirs It is also demonstrated, that when a fractured reservoir is subject to a relatively large rate of pressure drop and/or it composed of relatively large blocks, the pseudo steady-state pressure concept gives large errors as compared with transient fromulation In addition, when gravity drainage and imbibitum processes, which is the most important mechanism in the fractured reservoirs, are represented by a ''lumped parameter'' even larger errors can be produced in exchange flow between matrix and fractures For these reasons, the matrix blocks are gridded and the transfer between matrix and fractures are calculated using pressure and diffusion transient concept In this way the gravity drainage is also calculated accurately As the matrix-fracture exchange flow depends on the location of each matrix grid relative to the GOC and/or WOC in fracture, the exchange flow equation are derived and given for each possible case The differential equation describing the flow of water, oil, and gas within the matrix and fracture system, each of which may contain six unknowns, are presented The two sets of equations are solved implicitly for pressure water, and gas stauration inmore » both matrix and fractures The first twenty two years of the history of Haft Kel field was successfully matched with this model and the results are included« less

New pressure drop correlation for sieve tray distillation columns

Abstract: Pressure drop data for distillation sieve trays have been obtained with experimental trays with small outlet weir heights, including zero, and for trays with small perforations which exhibit large pressure drops due to surface tension. These data have been added to literature data to form a large composite data base with extensive variations in fluid and gas properties, flow rates, and tray designs. A new pressure drop correlation has been developed which retains the use of the dry tray pressure drop, but provides new procedures for estimating liquid inventory and the resistance to vapor flow due to surface tension forces. This correlation gives a mean absolute error of 6.0% and an average error of −0.6%. These errors are significantly less than the errors between measurements and predictions from two other correlations using the same composite data base.

The Effects of Mechanical Degradation and Viscoelastic Behavior on Injectivity of Polyacrylamide Solutions

Abstract: Results of recent experiments that clarify the effects of mechanical degradation and viscoelastic behavior on the flow of partially hydrolyzed polyacrylamide solutions through porous media are presented. From these results, a simple model that may be used to predict injectivity of polyacrylamide solutions is developed. Injection pressures for linear corefloods are shown to be separable into two components: an initial pressure drop associated with the entrance of polymer into the sandstone and a constant pressure gradient throughout the remainder of the core. Entrance pressure drop is zero until the polymer solution flux increases to the rate where mechanical degradation takes place. Thereafter, entrance pressure drop and the degree of polymer mechanical degradation increase with increasing flux. These observations suggest that the entrance pressure drop is associated closely with the process of polymer mechanical degradation. A new correlation is developed that may be used to determine entrance pressure drop and the level of mechanical degradation directly as a function of sandface flux, permeability, and porosity. This correlation is more convenient to apply and less dependent on flow geometry than previous correlations. Based on these observations, a model is developed that may be used to estimate injectivity of polyacrylamide solutions in linearmore » or radial flow geometries.« less

Flow control valve

Abstract: The invention relates to a flow control valve, with a control orifice of the longitudinal slide type which can be adjusted in its longitudinal direction against a restoring force by an electromagnetic lifting magnet, and with a differential pressure balance which sets the pressure drop at the control orifice, in which arrangement pressure fluid flows in particular around the armature of the lifting magnet in a pressure-relieving manner The invention provides for the opening cross-section of the control orifice (orifice openings 48) to be distributed along the axis of the orifice slide (44), and for the lifting magnet a to be provided with a multi-stage, at least three-stage, or continuous flow-setting device, the settings of which have allocated to them various effective opening cross-sections of the control orifice

Polymer melt rheology with a slit die

Abstract: A piston driven high pressure slit die rheometer with three pressure holes along the die and one in the barrel was used to investigate viscosity, entrance and exit pressure losses, and pressure coefficient of viscosity of a LDPE melt. Hydrostatic calibration of melt pressure transducers can be performed in the rheometer. The slit die results are compared with measurements on circular dies assuming linear and parabolic pressure profiles in both cases. A simplified conversion from apparent to true viscosity, applicable for single point measurements, has been used. In spite of the different symmetries the Bagley correction from the linear pressure profile of circular dies was found to be equal to the sum of exit and entrance pressure losses in the slit. The magnitude and sign of the exit pressure loss depend on the type of pressure profile used. The influence of a pressure dependent viscosity and a temperature gradient along the die on the curvature of the pressure profile is discussed. To directly investigate the effect of pressure the pressure level at constant flow rate was increased stepwise by means of a valve attached to the exit of the slit die.

Gas separation by permeators with high-flux asymmetric membranes

Abstract: The permeation behavior of the high-flux asymmetric membrane differs from that of the conventional symmetric membrane. A calculation method for predicting the gas separation performance of a permeator with asymmetric membrane is presented. The model takes into account the permeate pressure drop and is applicable to both hollow-fiber and spiral-wound modules. The effect of permeate-feed flow pattern on module performance is analyzed. It is shown that for the high-flux asymmetric membrane, the countercurrent flow pattern is not necessarily always the preferred operating mode. The mathematical model is verified by large-scale field pilot-plant experiments for helium recovery from natural gas using large hollow-fiber modules (220 m2/unit).

The creeping motion of immiscible drops through a converging;diverging tube

Abstract: Results of experiments on the low-Reynolds-number flow of liquid drops through a horizontal circular tube with a diameter that varies sinusoidally with axial position are reported. Measurements of the contribution of the drop to the local pressure gradient and the relative velocity of the drop are correlated with the time-dependent drop shape. Both Newtonian and viscoelastic suspending fluids are considered. The viscosity ratio, volumetric flow rate and drop size are varied in the experiment, and both neutrally buoyant and non-neutrally buoyant drops are studied. Comparison with previous results for a straight-wall tube shows that the influence of the tube boundary geometry on the drop shape is substantial, but the qualitative effect of the tube shape depends strongly on the relative importance of viscous forces compared to interfacial tension for the particular experiment. For Newtonian fluids, two modes of drop breakup, which are distinguished by the magnitude of the viscosity ratio, are observed. When the suspending fluid is viscoelastic, both shear-thinning and time-dependent rheological effects are present.

Hydrodynamics of two-phase cocurrent downflow through packed beds. Part I. Macroscopic model

Abstract: Pressure drop and liquid saturation are two important design parameters in cocurrent gas-liquid downflow through packed beds. A macroscopic model based on momentum balance is formulated for the condition of no radial pressure gradients. The model includes the effect of bubble formation on the pressure drop and holdup and is compared with the experimental data of the earlier investigators and of the present study. The model provides a functional form for correlating pressure drop and liquid saturation but some parameters have to be determined by fitting the experimental data.

The high‐current vacuum arc in an axial magnetic field: An experimental investigation

Abstract: A spectroscopic study of the plasma parameters of a high‐current vacuum arc in an axial magnetic field shows that the interaction of the particles in the arc is collisional. A previously suggested pressure drop is found to exist. The pressure buildup in the arc may be influenced significantly by ion‐neutral friction.

Transient Behavior of a Rock-Bed Thermal Storage System Subjected to Variable Inlet Air Temperatures: Analysis and Experimentation

Abstract: An analytical solution to the transient thermal behavior of a rock-bed thermal storage system subjected to varying air inlet temperature is presented. The solution is obtained in terms of infinite double series which are based on Schumann's solution, derived for a step change in air inlet temperature. In the present study, bed and fluid temperatures in response to arbitrary fluid inlet temperatures are calculated by means of Duhamel's theorem. Results of this study were verified experimentally and compared to a numerical solution. Agreement in both these cases was very good. Pressure drop data were compared to values predicted by two previously published correlations. These correlations were found to underpredict the measured data by factors in the range 1.5-5. Reasons for this discrepancy are mainly due to the differences in the type and particularly the shapes of rocks used in the different studies.

Method and apparatus for sensing clogged nozzle

Abstract: A method and apparatus for sensing and signalling a clogged nozzle condition in a spray gun of the type which includes a valve located adjacent the nozzle. The gun includes a restrictor (25) located in the liquid flow path upstream of the valve (14) and a pressure transducer (31) located between the restrictor (25) and the valve (14) for measuring pressure drop when the valve of the gun is opened. A pressure drop of less than a predetermined amount is indicative of a clogged nozzle condition.

How dust in gas affects cyclone pressure drop

Abstract: This article reports on a series of simple experiments on a cyclone which were performed to visually demonstrate the vortex length, to confirm its independence of inlet velocity over the normal ranges of operation, and to differentiate between length theoretically predicted, length based on cone erosion and length based on particle to barrel adherence. Simultaneously, the effect on pressure drop of a minor amount of solids in the gas stream was dramatically demonstrated. Concludes that when dealing with non-sticky solids minimum cyclone length is preferably based on the constant surface cylindrical vortex; when dealing with ''sticky'' particles, maximum cyclone length is preferably based on the criterion of 1.6 times the cyclone cylindrical section (or less than the natural vortex length); and the pressure drop equations in API publication 931, based on 3.8-cm (1 1/2-in.) to 3.66-m (12-ft) diameter cyclones operating with pressure drops of 1.3 kPa (5 in. of water) to 137.9 kPa (20 psi), are in agreement with operation under load and result in lower pressure drop than when operated with gas only.

Interfacial drag for two-phase flow through high permeability porous beds

Abstract: Pressure drop and void fraction measurements in two-phase (air-water) flow through porous beds of randomly packed spheres have been used to determine the interfacial gas-liquid drag and the gas-solid drag for the case of zero net liquid flux through the bed. The results, presented for beds of 3.18, 6.35, and 12.7 mm spheres, show that the interfacial gas-liquid drag term is of the same order as the gas-solid drag term when the particle size is greater than 6 mm.

Method and apparatus for monitoring a respirator usable with an endotracheal tube

Abstract: A method of safety monitoring a respirator which is connected to a patient through an endotracheal tube which has a respiratory gas jet nozzle delivering respiratory gas thereto and a measuring tube opening into the tube, comprising supplying at least one jet nozzle with a respiratory gas discharging into the tube, directing a fluid through the measuring tube at a substantially constant flow rate so that the variations in the pressure in the endotracheal tube will vary the pressure in the measuring tube, sensing the pressure in the measuring tube and controlling the flow through the jet nozzle in accordance with the pressure in the measuring tube, and wherein the flow of fluid in the measuring tube is set sufficiently low that in the event of a negligible pressure drop in the tube the pressure measured in the connection of the measuring tube at least approximately corresponds to the ambient pressure in the opening of the measuring tube.

Method and apparatus for measuring relative permeability and water saturation of a core

Abstract: A method of determining the oil and water relative permeabilities and the water saturation of a core of earthen material which includes providing two types of liquids to the core in a manner so that the liquids mix to form a two phase liquid which moves through the core. The core is irradiated with microwave energy while the liquid is in the core. A received energy signal is generated in accordance with the microwave energy that has passed through the core. A liquid pressure drop along a predetermined length of the core is sensed and a representative pressure drop signal is provided. The oil and water relative permeabilities and the water saturation of the core are derived in accordance with the flow rate of the liquid, the received energy signal and the pressure drop signal. The liquid flow rate may be either sensed or the liquid may be provided at a predetermined flow rate.

Catalytic Combustion of Propane/Air Mixtures on Platinum

Abstract: A honeycomb catalyst of platinum (4.2 kg/cu m loading) over cordierite, with gamma-alumina washcoat, a cross section of 2.4 x 2.4 sq cm, a length of 7.6 cm, and a characteristic channel diameter of 1.4 mm is used as a steady flow reactor. Measurements are made with C3H8/air mixtures at 650 to 800 K inlet temperatures, 110 KPa pressure, 10 to 40 m/s inlet velocity, 0.19 to 0.32 equivalence ratios, and approximately 1.5 mole percent water content. The measured quantities are the substrate tempeature at ten axial locations, the exhaust gas temperature, the exhaust concentrations of CO, CO2, O2, and total hydrocarbons, and the pressure drop across the monolith. The measured quantities are compared with those computed with a two-dimensional steady-state model for axial and radial convection and diffusion of mass, momentum, energy and homogeneous (three overall reactions) and heterogeneous (infinitely fast) reactions. It is found that, under the tested conditions, most of the fuel is converted to CO2 and H2O at the surface. Gas-phase reactions tend rapidly to become more important as the temperature and equivalence ratio are increased and the flow velocity is decreased. Surface fuel conversion is much more rapid than fuel diffusion, resulting in diffusion-controlled oxidation.

Laminar flow element

Abstract: A laminar flow element for use in a cylindrical fluid flow passage for restricting the flow of fluid through that passage to a constant volume flow rate. The element comprises a body portion having a cylindrical peripheral surface of predetermined length and predetermined diameter, with the surface defining with the passage an annular, tubular fluid passageway. Locating portions are provided extending from the element for engagement with at least one surface in the cylindrical passage for maintaining the peripheral surface concentrically disposed within the cylindrical passage. The length and diameter of the element are dimensioned so that the flow is laminar under all operating conditions, and therefore the volume rate of flow of fluid through the passage is linearly proportional to the pressure drop along the annular passage.

Processes for carrying out catalytic exothermic and endothermic high-pressure gas reactions

Abstract: Processes for carrying out catalytic exothermic and endothermic high-pressure gas reactions with a single-walled pressure vessel or shell containing cross-flow (eg, radial flow) heat transfer exchangers, a continuous catalytic bed having at least two stages, and means for effecting "cross-over" material flows from "outside" to "inside" (for exothermic reactions) and vice versa (for endothermic reactions), whereby conditions of: maximum gas temperature always being in the core of said vessel or shell, minimal pressure drop, and minimal compression of catalyst particles are achieved, along with significant economic savings in cost of the pressure vessel or shell and catalyst (through extension of catalyst life)

Aerodynamic performance of a Wells air turbine

Abstract: Experiments were performed in a unidirectional flow rig to assess the performance of the Wells self-rectifying air turbine. Results indicated that the efficiency of the turbine was very sensitive to the Reynolds number based on blade chord. Increase in Reynolds number by a factor of three resulted in an increase in peak efficiency from 37 to 60%. Increases in the solidity of the blade produced increases in pressure drop and power output but decreases in efficiency. The hub-to-tip ratio had only a weak influence on the turbine performance but is critical for starting conditions. It is concluded that a hub-to-tip ratio of 0.6 and a solidity of 0.6 are are the most favorable values, taking into consideration both the starting and running performances.

Influence of wall permeability on turbulent boundary-layer properties

Abstract: Experimental boundary-layer studies of a series of low pressure drop, permeable surfaces have been conducted to characterize their surface interaction with a turbulent boundary layer. The models were flat and tested at nominally zero pressure gradient in low speed air. The surfaces were thin metal sheets with discrete perforations. Direct drag balance measurements of skin friction indicate that the general effect of surface permeability is to increase drag above that of a smooth plate reference level. Heuristic arguments are presented to show that this type of behavior is to be expected. Other boundary-layer data are also presented including mean velocity profiles and conditionally sampled streamwise velocity fluctuations (hot wire) for selected models.