Pressure Drop In Pipes Research Articles

Viscosity measurement in a pipe flow using a numeric recursion approach for in-line quality control

The use of a pipe as a sensor for measuring viscosity and shear rate would require a separated flow rate instrument and would result in a more complicated mechanism for in-line quality control. In this study, a method of applying numeric recursion to the pipe pressure drop to directly calculate the viscosity and the shear rate is proposed. This viscosity sensor was verified by using it to measure the viscosity and shear rate for low-density polyethylene. The viscosity and shear rate obtained by this approach differ little from those obtained by using a standard off-line capillary rheometer. Therefore, this viscosity measurement method is applicable for in-line quality control.

Calculation of pressure drop in the tube flow of sewage sludges with the aid of flow curves

The layout of pumps for the transport of sewage sludges in sewage plants is of great importance. The understanding of pressure drop plays a decisive role. In this paper, a method, existing in the literature, which was developed within the framework of treating the frictional behaviour of viscoelastic fluids, will be presented for the calculation of the pressure drop in pipes. Sewage sludges belong to the class of non-Newtonian fluids. They exhibit intrinsically viscous behaviour and elastic properties. Due to the variation of the viscosity across the cross-section of flow, a representative Reynolds number at the operating point of the flow is defined with the aid of a representative viscosity, in order to determine the type of flow. Exact statements about the pipe friction coefficient in laminar flow are facilitated knowing the correlations for Newtonian fluids. For the case of the turbulent region, a modified formula for Newtonian fluids is taken as a basis. The validity of the method of calculation for sewage sludge flow is compared and discussed with and with respect to numerous experiments in research plants and actual sewage plants.

Calculation of pressure drop in the tube flow of sewage sludges with the aid of flow curves

The layout of pumps for the transport of sewage sludges in sewage plants is of great importance. The understanding of pressure drop plays a decisive role. In this paper, a method, existing in the literature, which was developed within the framework of treating the frictional behaviour of viscoelastic fluids, will be presented for the calculation of the pressure drop in pipes. Sewage sludges belong to the class of nonNewtonian fluids. They exhibit intrinsically viscous behaviour and elastic properties. Due to the variation of the viscosity across the cross-section of flow, a representative Reynolds number at the operating point of the flow is defined with the aid of a representative viscosity, in order to determine the type of flow. Exact statements about the pipe friction coefficient in laminar flow are facilitated knowing the correlations for Newtonian fluids. For the case of the turbulent region, a modified formula for Newtonian fluids is taken as a basis. The validity of the method of calculation for sewage sludge flow is compared and discussed with and with respect to numerous experiments in research plants and actual sewage plants.

Protection of storage tanks from two‐phase flow due to fire exposure

AbstractVarious approaches are presented to protect storage tanks from fire exposure. Design techniques for emergency relief devices flowing vapor or two‐phase vapor‐liquid flow are discussed. The effects of maximum design pressure versus emergency relief device set pressure, fire exposure insulation and water spray protection, fire exposure duration, relief device flow characterization and inlet pipe pressure drop and discharge pipe back pressure must all be considered when designing to protect storage tanks.This paper discusses some aspects of pressure relief design for low pressure storage tanks. The concepts and techniques discussed here can be modified to include design guidance/recommended design parameters from specific standards. Even if not used for pressure relief design, the concepts/calculations presented should be useful for Process Hazard Analysis studies to determine the relative ranking of credible scenarios.The reader is cautioned that no attempt was made to cover every design situation or conform to any design standard/recommended practice. There are too many specific scenarios and too many (unnecessary) conflicts between standards/recommended practices. Instead, the reader is cautioned to ensure that all prescribed federal, state and local as well as company design standards are followed when mandated.

Hydraulic transport of solids in pipes: a simple method for the prediction of pressure drop

Suspensions such as grouting slurries, concrete and dredge muds exhibit a complex flow behaviour in pipes which is not fully understood. This flow in cement systems is often complicated by the time-dependent behaviour of the material and the apparent slippage at the wall of the pipe. Most of the methods which have been developed to predict the flow behaviour of thick suspensions are very complex and are frequently inaccurate. In this paper a simple method is discussed which can be used to predict the pressure drop in pipes for time-dependent or time-independent materials with a yield stress. The method is based on the assumption that the sheared layer in the pipe can be simulated by a similar layer in the coasial cylinder viscometer, and the properties of the layer are only dependent on plug speed in both systems. The implication of this assumption is that the shear stresses at the surface of the pipe and at the surface of the inner cylinder of the coaxial viscometer are independent of the pipe diameter and the diameter of the cylinders. The method was tested against the authors’ own data and by other data from the literature.

Evaluation of flush mounted hot-film sensors for skin friction reduction measurements in viscoelastic polymer solutions

The purpose of this investigation was to evaluate the performance of flush mounted hot-film sensors for mean wall shear stress measurement in turbulent flows of dilute drag reducing polymer solution. A series of pipe flow expriments were conducted over a range of Reynolds numbers and polymer solution concentrations to compare the level of skin friction drag reduction measured by hot-film sensors with values calculated from pipe pressure drop. It is shown that water calibrated hot-film sensors consistently underestimate the wall shear stress suggesting that Reynolds analogy is not valid in dilute polymer solutions. The Newtonian form of the relationship between the wall shear stress and the heat transfer remains valid in dilute polymer solutions. However, multiplicative and additive factors in the relationship are shown to increase linearly with the logarithm of the polymer concentration.

Energy losses and particle—wall interactions on rough surfaces

The development of coal combustion and gasification units, in which gas—solid phases are present, has created the necessity for refractory materials resistant to particle impact. Refractory concretes appear as promising materials for pipe and vessel linings, since they meet cost and construction criteria. The design and modeling of conveying lines in these units requires data on materials degradation and particles energy losses upon impact. An erosion study was performed in a commercial-scale pneumatic test facility, in which the erosion rates of different refractory concretes were measured at high temperatures under various operating conditions. River sand, coal slag and tabular alumina were used as eroding materials. The effects of gas velocity and solids concentration were measured. The erosion process generated extremely rough surfaces, whose topology is determined by the concrete microstructure and projectile characteristics. The mechanisms of erosion were identified and the resulting surfaces were characterized using fractal analysis. The effect of this high roughness on the pressure drop in pipes was determined at high temperatures. Particle energy losses upon impact on eroded surfaces were determined in a different set-up, using high-speed photography. As a result, rebounding angles and velocities were correlated for the different materials and surface conditions.

The flow properties of foam

The rheological behaviour of foam, prepared from an aqueous solution with lauryl sulphate as surfactant, has been measured with a viscometer as a function of the blow ratio, bubble diameter distribution and concentration of the thickener used. The influence of wall slip and of hysteresis effects on the rheological behaviour have been determined. Calculations and measurements pertaining to the pressure drop in pipes have been performed, in which the foam was considered as a compressible pseudoplastic whose rheology depended on blow ratio. The distribution of the foam passing through a closed distribution unit has been studied. This distribution unit consisted of a pipe and a cross‐head distribution slit. Complementary measurements of the flow of foam through narrow slits have been made. The design of a closed foam distribution unit is discussed. The consequences of the choice of several design parameters are examined.

フライアッシュスラリーの流送に関する研究 (第2報)

The purposes of this investigation are to measure the pipe pressure drop of fly ash slurry containing coarse particles and to measure the torque of a rotating cylinder in the packed coarse particles submerged with the fine slurry.In order to make a comparison between flow pressure drop of the fly ash slurry and that of the fly ash slurry with coarse particles in pipes, some experiments were carried out in horizontal 2B and 4B pipe lines.The result shows that under the same total volumetric concentration of solids the pressure drop decreases by adding coarse particles, especially at higher velocity and at higher conventration of coarse particles.It is well known that some of fine particles as an additive to settling slurry bring the reduction of the pressure loss. Experimental results are also analyzed from this point of view.The same result was obtained throughout the concentration of fly ash from 10 vol.% to 40 vol.% at low velocity, however, the most effective reduction of the pressure drop was achieved at lower fly ash concentration and at higher coarse particle concentration.One the assumption that the reduction is due to the lubricant effect of fine particle, the torque of the rotating cylinder in the packed coarse particles mixed with fine slurry was measured.The reduction of torque was very similar to the decrease of the pressure drop in pipes presented by several researchers.

Flow of Mud During Drilling Operations

Summary The development of rotary rock bits with jet nozzles required means of estimating pressure losses in the drilling fluid flowing throughout the well being drilled and through the associated equipment. The initial tabulations were based on Newtonian fluids. Subsequent authors developed descriptions of drilling fluids based on Bingham or power law non-Newtonian fluid models. Because optimum-hydraulics theories dictate that hydraulic horsepower, impact, or impact force must be maximized, we made the difficult decision to determine these pressure losses by actual tests. A total of 119 water-base drilling fluids were pumped through capillary tubes up to 2 in, in diameter and through six standard sizes of drillpipe tool joint combinations. Drilling fluids were flowed through jet bit nozzles and were flowed up two annulus-size combinations as well as an annulus with hole enlargements. The annular tests included cuttings, which aided in determining flow patterns. This paper includes development of friction factors and empirical corrections for current theories to model flow of highly non-Newtonian fluids more reasonably. Procedures and equations arc offered to help estimate pressure losses in a drilling operation, even with very limited fluid property information typical of our industry. Introduction Field tests of flocculants and other polymers added to water or clay water drilling fluids resulted in lower pump pressures and higher pump speeds than predicted with available tables. In some cases, these pressure reductions were dramatic and resulted in loss of rig time inspecting for equipment failure. Field pressure measurements showed that the pressure losses for actual muds were significantly different from those calculated by available methods. A laboratory test facility was constructed to measure the exact pressure losses for various types of drilling fluids in actual drillpipes and annuli. The initial concept was to develop more comprehensive tables for various types of muds in the range of pipes used. After initial tests it became apparent that the number of tables required would make their use unattractive. Because this work was to assist field personnel in calculating pressure losses so that hydraulics could be optimized, it had to be based on flow property measurements available in the field. The best available field data are often the Fann plastic-viscosity and yield point measurements based on the 600- and 300-rpm readings. Dodge and Metzner indicate that the powerlaw fluid model can be used to describe the flow of drilling fluid in pipes; therefore, these fluids were treated as power-law fluids with suitable corrections to be applied where required. Equipment Flow properties and pressure drop in pipes were measured by pumping the test fluids through 10 pipes ranging in ID from 0.187 to 3.826 in. and in annuli from 5.044 × 2.5 to 12.715 × 5.0 in. Nominal 20 in. welded pipe and six types of drillpipe were manifolded into the full-scale test system. This system included a 20-bbl mud tank, a 100-hp electrically driven centrifugal pump, and automatic diaphragm valves for flow and bypass controlled by the flowmeter. Flow rates were measured by )- to 500- and 0- to 50-gal/min flowmeters that demonstrated better than 0.25% full-scale accuracy. Differential pressure along the test sections was measured with 0- to 100-psi, 0- to 400-in. water, 0- to 100-in, water, and 0- to 20-in. water differential-pressure cells. An automatic continuous flow of city water from the cell to the pressure taps was maintained at a rate of about 20 cm /min to prevent mud from entering the test lines. JPT P. 1414^

Some problems in space simulation chamber design

In presenting this paper the authors have emphasized the various factors which influence the design of space chambers and especially those which present particular problems and on which the success of the design depends. A discussion on vacuum requirements and the effect of outgassing from various materials introduces the reader to one of the more important design criteria. This is followed by an analysis of the absorption characteristics of a refrigerated coil and its relation to outer space conditions. The effect of frost layer on the absorptivity factor is demonstrated from experimental data and the advantages of cryopumping are outlined. An appraisal of factors influencing the design of the vessel and its geometry is made, particularly with regard to the mode of absorption coil and its attendant refrigeration system. The process of evaporation is explained together with factors which influence pressure drop in pipes, temperature gradients and distribution of refrigerant. A closed cycle refrigeration system is discussed in detail. The principles of achieving solar simulation are given and comparison between xenon arc and carbon arc sources. Various optical systems are explained.

Reduction of Friction Loss in Fracturing Operations

Abstract In modern fracturing treatments, friction loss in pipe often has been the limiting factor in obtaining high injection rates desired for maximum effectiveness. Additives now available can reduce the friction loss of water by 70 per cent, permitting horsepower savings or higher injection rates, and completion of wells with smaller-size casing. The additives are used at very low concentrations for reducing friction loss. Higher concentrations give even lower friction loss, even though these fluids are viscous enough to give effective viscosity control of fracture leak-off. The friction-loss reduction is attributed to viscoelasticity of the solutions, which partially suppresses turbulence. Introduction The major trends in hydraulic fracturing during recent years have been the use ofhigher injection rates,more efficient fluids andengineering methods in designing the treatments. These trends focus attention On the friction pressure-drop in pipe as a major factor in the operation. The cost of power used in overcoming friction does not contribute to increasing the fracture area achieved. A surface pressure limit, set by the strength of the pipe, often determines the maximum attainable injection rate. This rate may not be high enough to give the most efficient treatment in terms of fracture area per dollar spent. The use of chemical additives to reduce friction loss in pipe significantly improves efficiency in fracturing treatments. It is known that the soap-gelled crude oils used in fracturing have lower friction losses than the same crude oils without gelling agents. In fracturing with brine or fresh water, still larger reductions of friction losses have been attained by two types of materials: a natural gum polymer and, more recently, a synthetic water-soluble polymer. Besides reducing friction loss, both additives are used to thicken fresh water, and the natural polymer thickens brine. Such "gelled water" has a low sand-falling rate and good viscous control of leak-off from the fracture.

Effect of Roughness on the Friction Coefficient on a Closed Channel

THIS paper presents the results of one series of tests included in a comprehensive program of research on hydraulic friction and roughness being carried on at the University of California. An investigation was made of the friction coefficients of closed rectangular channels having the same absolute roughness. The walls of the channels were made of smooth brass artificially roughened by sixty degree V-grooves transverse to the direction of flow. The effect of relative roughness on skin friction is important in the extrapolation of experimental results on models to the prototype. At present Nikuradse's equation based on data of the pressure drop in pipes artificially roughened with sand is used for this purpose. The results of these tests provide data to justify this procedure. The friction coefficients of four channels having hydraulic radii ranging from 0.030 to 0.230 feet were determined for different rates of flow. The channels were constructed of two brass plates one-quarter inch by five and three-quarters inches by eight feet and spacers one-sixteenth, one-eighth, one-quarter, and one-half inch wide. Both plates and spacers were roughened their full length by the grooves machined 0.060 inches apart with an average depth of 0.0125 inches. Practically, the absolute roughness of the different channels was the same since the relative width of the plates, which were the same in all, was large compared to that of the spacers. The large aspect ratio of the channel also insured nearly two-dimensional flow. The plates were held in place by heavy iron castings running the full length of the channel. Fig. 1 is an end view of the assembled channel. Five piezometer holes were located nineteen and one-half inches apart along the center-line of one plate. Pressure drops were measured between adjacent holes with vertical or inclined, mercury or carbon-tetrachloride manometers. The results given are for the downstream pair of taps only, pressure drops farther upstream being appreciably affected by entrance conditions. Rates of flow were measured either by an orifice calibrated in place or by direct weighting. A second series of tests were made on the one-eighth, one-quarter, and onehalf inch set-ups after the original one had been dismantled, and the results checked with those of the first series. In the turbulent region where the friction coefficient for rough surfaces does not depend on Reynold's number, a function, containing two empirical constants, FIG. 1. End view of roughness channel showing brass roughness plates and cast iron supporting frame.