Required Pressure Drop Research Articles

Removal of Dissolved Aromatics from Water: Comparison of a High Intensity Contactor with a Packed Column

An experimental comparison of the performances of a new high intensity contactor and a conventional packed column in stripping dissolved aromatics from water is described. The contactor gives significantly lower values of HOL. These, combined with the much higher liquid fluxes, give volumetric mass transfer coefficients, KLa, several hundred times higher than those for the packed column and substantially higher than those in the literature for bubble columns. Performance is particularly good on saline water due to suppression of bubble coalescence. That characteristic would be beneficial in the removal of aromatics from produced water in oil and gas production. The contactor utilizes enhanced acceleration fields achieved by water injection and so should be insensitive to the marine motion and tilt experienced on offshore floating production systems, as well as being compact. At constant water rate, KLa ∝ Gn with n ranging from 0.50 to 0.92. Some preliminary results on the effects of liquid feed rate and initial bubble size are included, the latter confirming the importance of bubble size on performance. Pressure drop and consequent energy requirements are also considered.

Lubrication Oil Reservoir Mist Elimination

Visible emissions from lubrication oil reservoir vents on stationary internal combustion engines, compressors and turbines can be virtually eliminated through the use of properly engineered fiber beds. The fiber bed is more successful than other approaches at eliminating visible emissions because of the inherent low pressure drop, minimal or non-existent maintenance requirements, and proven collection efficiency. In fact, with fiber bed technology, visible emissions can be reduced to virtually zero percent opacity. This paper reviews the applicable emission standards, explores the nature of the lubrication oil vent (LOV) oil mist, describes some of the equipment that has previously been used to control LOV emissions, and details the application of fiber beds for this purpose.

Continuous cocurrent processes in the nonsteady state

Although continuous heat- and mass-transfer processes are usually conducted in countercurrent flow, there are certain cases in which the cocurrent flow can be used to some advantages from an operation point of view. For example, in the packed adsorption column, flooding due to high vapor or gas flow rate can be eliminated if cocurrent flow is employed. Use of cocurrent flow can also reduce the pressure drop requirement in the packed column. Reiss (1967) discussed several instances in which cocurrent mode operation may be favored over countercurrent flow. In the case of heat transfer, cocurrent flow is also suitable for some special situations. For instance, if it is necessary to limit the maximum temperature of cooler fluid or if it is important to change the temperature of at least one fluid rapidly (McCabe et al., 1985). The transient behaviors of both cocurrent and countercurrent processes are important in the startup and control of mass- and heat-transfer operations. Previously, numerical solutions based on a method of characteristics was used to study the transients of countercurrent processes (Tan and Spinner, 1984). Owing to the split boundary conditions, analytic solutions are difficult to obtain even for the linear system. For cocurrent flow, compact analytic solutions in terms of well-known tabulated function can be derived. The purpose of this note is to present the nonsteadystate behavior of continuous cocurrent flow of two contacting phases. The transient responses to the inlet disturbances are derived based on a simple mathematical model. This simplified model is equally applicable to either mass- or heat-transfer processes. Laplace transformation method is used to obtain compact analytic solutions. These solutions can be easily evaluated with the aid of the known tabulated mathematical functions or charts. Both the derivation and the final form of solutions are easier to apply in comparison to the work of Li (1986).

Analysis of flow, pressure drop, and power requirement in pulsed columns

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnalysis of flow, pressure drop, and power requirement in pulsed columnsT. L. Harikrishnan and Y. B. G. VarmaCite this: Ind. Eng. Chem. Res. 1992, 31, 5, 1352–1361Publication Date (Print):May 1, 1992Publication History Published online1 May 2002Published inissue 1 May 1992https://doi.org/10.1021/ie00005a015RIGHTS & PERMISSIONSArticle Views103Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Rheological behaviour of gelled, waxy North Sea crude oils

The design of subsea pipelines carrying waxy crude oil, especially in Northern and arctic areas, is largely controlled by start-up pressure drop requirements. The correct measurement of rheological parameters associated with start-up and line-clearing of gelled crude oil pipelines, is thus important for proper design of pumping capacity and pipeline dimensions. In Part 1, the yielding behaviour of some waxy North Sea crude oils was studied by means of different controlled stress experiments, using a controlled stress rheometer (CSR) with cone-and-plate geometry and a model pipeline. Strong dependence of yield stress on cooling rate and stress loading rate was observed. Reasonably good estimates of yield stress, as compared to model pipeline results, were obtained with the CSR. CSR measurements are thus considered to be a valuable supplement to model pipeline experiments, particularly for comparative purposes, such as flow improver screening. In Part 2, the time-dependent rheological properties of two waxy oils were studied under controlled stress and controlled shear rate conditions, mainly in the cone-and-plate geometry. Two different approaches for modelling of viscosity decay at constant shear stress, based on a first-order rate equation and the Bingham rheological equation of state respectively, reproduced experiments reasonably well. Equilibrium properties obtained in different instruments (controlled stress/ controlled shear) and geometries (cone-and-plate and concentric cylinder) agreed within about 15% for shear rates between 14 and 700 s −1. At constant temperature, the broken-down apparent viscosity recovered moderately at rest, whereas the breakdown of static yield stress was essentially irreversible. Slight temperature cycling (±1° C) induced rebuilding of a weak structure, but did not restore the original gel strength completely.

Heat transfer solutions in laminar co-current flow of immiscible liquids

Thermal entry region solutions are analytically determined for horizontal, co-current laminar flow of immiscible liquids in direct contact, inside circular tubes and parallel plate channels. The related eigenvalue problem for such a composite media is readily solved by extending the ideas in the recently advanced sign-count method. It is assumed a core-annular flow configuration for circular tubes and sheat-core flow for the parallel plates channel, without consideration of interface instabilities and stratified flow. First, the velocity problem is solved for fully developed flow and pumping power expressions established for different operating conditions. Then, the temperature problem is analytically handled to yield expressions for quantities of practical interest such as total heat exchange rates, along the duct length and, again, for different flow rates and pressure drop requirements. The analysis is illustrated through consideration of an application dealing with pumping of a very viscous oil with the addition of an external thin layer of a less viscous fluid (water). Pumping power and total heat exchange are then evaluated for both geometries and critically compared to the single fluid flow problem.

Rheology of Foams IV. Effect of Gas Volume Fraction

Structural models for foams having two‐dimensional cells with straight line segments and rounded corners are used to study the effect of gas volume fraction (φ) on small shearing deformations. A stress tensor expression is presented which is valid for all gas volume fractions between unity (dry foam) and φ=0.9069 (hexagonally close‐packed cells). Two models are studied. In the first, the linear foam films are considered infinitesimally thin with all liquid in the foam confined to the Plateau borders. In the second model, the films have a finite thickness; the distribution of liquid between the Plateau borders and films varies with strain and is determined from an equal pressure drop requirement across all gas‐liquid interfaces. Identical results are obtained for the two models studied. The stress‐strain relation is a strong function of the gas volume fraction and, in general, the yield or minimum (negative) stress decreases with decreasing gas fraction. Unlike the dry foam model, initial cell orientation influences the stress‐strain relation significantly. For certain orientations and gas fractions, limit points and multiple solutions are observed, thus indicating possibilities of preferential cell orientation. Positive stresses are also observed in the stress‐strain cycle in many cases as the energy of the system passes through a maximum when the cells are deformed.

FLOW BEHAVIOR AND FUNCTIONAL PROPERTIES OF MALT EXTRACT CONCENTRATES

Flow characteristics and functional properties of malt extract concentrates were investigated. Flow behavior was studied using a coaxial viscometer over shear rates of 0.6–145.8 s‐1. The shear rate‐shear stress data followed the power law, Casson, Herschel‐Bulkley and Bingham plastic models. Herschel‐Bulkley values for flow behavior index which ranged from 0.73–0.94, and presence of yield stress indicated the Bingham plastic nature of malt extract concentrates. The activation energy of flow for various concentrates was in the range of 14.8–17.7 kcal/gmole. Magnitudes of Reynold numbers (0.0–49.9) for all concentrates were lower than 2100. Temperature, yield stress and plastic viscosity considerably influenced the flow of concentrates in straight pipes. The pressure drop and power requirements for flow of concentrates in pipes at 50°–60°C were lower than those at 30°C, but negligibly different from those at 80°C. Coefficients of correlation between the Bingham plastic values for pressure drop and yield stress (r = 0.86, P < 0.01), and plastic viscosity (r = 0.97, P < 0.01) were highly significant. Hulled barley and corn concentrates containing high amounts of reducing sugars, showed low viscosities and yield stresses, and required desirably low power for flow in pipes at 50°–60°C. The high protein concentrates of wheat and triticale malts showed high whip volume and good foam stability. Wheat concentrate was superior in fermentability. Hulless barley and finger millet malts produced concentrates with high viscosities which might facilitate their utilization in gums, candies and other such products.

OMVPE conditions for GaInAs/InP heterointerfaces and superlattices

This paper reports OMVPE growth conditions and evaluation of GaInAs/InP superlattices. In order to improve the heterointerface properties, transient responses of the mole flow rate caused by gas switching have been analyzed quantitatively. The required pressure drop just after the bubbler for stable supply of metalorganic sources was confirmed experimentally. Furthermore, it is pointed out that a compensating flow to maintain reactor atmosphere is also effective. GaInAs/InP superlattices grown by using these analytical results showed definite satellite peaks in the X-ray diffraction characteristics, definite steps in the absorption spectrum and a photoluminescence peak as narrow as 13 meV at 77 K.

The Fluid Mechanics of Capsule Pipelines : 1st Report, Analysis of the Required Pressure Drop for Hydraulic and Pneumatic Capsules

This paper presents a study on the flow characteristics of capsule transportation. Especially, a method is presented for predicting the pressure drop required to move cylindrical solid capsules steadily and to suspend them freely in pipeline. For this prediction, an analytical method based on a study of multi-phase mixtures is proposed and it is confirmed that the present method is very useful for both hydraulic and pneumatic capsules. During the experimental and theoretical work, we can derive a general formula of the required pressure drop which has an inherent value for each of various conditions of capsule pipelining. In this paper, a detailed comparison of capsule transport with hydraulic transport of solids is also made.

Comparison of Commercial Column Types in Liquid Chromatography

Abstract Several commercially available liquid chromatographic column types have been experimentally evaluated. A conventionally-sized column containing 5 μm packing, a microbore column containing 10 μm packing, a column containing 3 μm packing, and two short, wide-bore columns containing 5 μm packing were compared at optimum velocity (van Deemter minimum) and at twice the optimum velocity where possible. All columns contained reversed-phase media of the C-18 type. Attention was focused on establishing advantages and limitations of each column with regard to maximum available plate count, minimum separation time, and required pressure drop. A van Deemter plot was constructed for each column type and the number of plates generated per unit length, time, and pressure was determined. In addition reduced parameters, separation impedance, peak capacities, and analysis times at a given k' were calculated. Calculations indicated the highest possible plate counts should be obtained with coupled microbore columns. Small particle (3 μm) columns provided the best performance for high speed, moderate plate count separations. Conventional-sized columns containing 5 μm packing material appeared to be a good compromise between high speed and high total plate count.

Fluid flow around and through a screen

A mathematical model is proposed for steady two-dimensional flow around a submerged screen. The general problem analysed is the flow in a parallel-sided channel partially spanned by a screen, and the fluid is considered to be inviscid except at the screen, where the flow has the required pressure drop. The model is constructed by first replacing the screen with a distribution of sources and then manipulating the stream function for this flow so that the mass and momentum balances across the screen are satisfied. Consequently the model predicts a flow field which is realistic except for the expected discontinuity in velocity between the wake and external flow. In general, the governing equations must be solved numerically, but for the important case of a plane screen oriented normal or roughly normal to the approaching flow, an approximate analytical solution is possible. The accuracy of the model was ascertained by conducting wind-tunnel tests on screens of various solidities and orientations, and comparing the measured downstream velocity distributions with those predicted by the numerical and analytical solutions of the model. Overall, the theoretical results agree well with the experimental data, showing that the model is valid for screens of low and high solidity, in fact, for pressure drop coefficients up to 10. Comparisons with the work of others show that the proposed model is also accurate for the special cases of a screen submerged in an infinite flow field and of a screen spanning the full width of the channel.

An experimental study of electrodialysis hydrodynamics

The role of hydrodynamics in electrodialysis is discussed. It will be shown that screens or mixing promoters do improve electrodialysis performance, especially at high flow rates ( N Rc > 180). The best spacer screens for electrodialysis are listed and criteria to evaluate screens are provided. Tests, characterizing each spacer with respect to porosity, dead flow area capability, drag coefficient and its influence on cell compartment resistance, are described. In-situ electrodialysis batch tests for eight of the best spacers were run to determine how current efficiency, stack pressure drop and total power requirements vary with flow rate. These results are discussed. Also, sheet flow and plug flow (tortuous path) designs are compared.

Filtration CharacteristicsOf Fly Ash from a Pulverized Coal-Fired Power Plant

The operating characteristics of a pilot baghouse and the filtering characteristics of fly ash filtered from the flue gas of a pulverized coal-fired power plant were studied by techniques developed in the engineering research laboratories of the National Center for Air Pollution Control in Cincinnati. The permeability of the dust cake varied with the operating conditions of the baghouse in a way that significantly affects the pressure drop and power requirements of the system.

Cable Pressurizing Systems

Techniques for maintaining pressure on oil-impregnated paper insulation in high-voltage cable are discussed, with emphasis on the design and application of fluid pressure systems and components. Methods for quantitative determination of pressure drop, oil demand, and oil requirement, about which there has been much written, are omitted here. An aim of this paper is to establish a pumping plant design which has the broadest application, and to classify the significant variations from this base.

Pressure drop and power requirements in a stirred fluidized bed

AbstractThe paper reports fundamental observations on the effect which stirring of fluidized solids has on the pressure drop. Typical power requirements are also given.The experimental pilot unit was of 6‐in. diameter and 12 in. high. A special blade or paddle type of stirrer had been built which permitted the evaluation of the effects of blade positioning, blade spacing relative to sense of rotation, as well as the effect of stirrer immersion and rotational speed.The observations disclosed that blade positioning relative to sense of rotation had a very profound effect on pressure drop as well as on power requirements. When the solids circulation pattern as normally induced by the stirrer was of the same general character as that ordinarily encountered in a dense phase fluidized charge, the resulting pressure drop was always considerably lower than the conventional unstirred fluidized bed pressure drop. Furthermore for this type of stirrer the power requirements were also lowest. For other stirrer designs and other induced solids convection patterns the pressure drop was less influenced and the power requirements were much greater.The solids used for the study were a relatively coarse silica sand for which both pressure drop as well as power requirement data were reported. Power requirement data were also obtained for a much finer alumina powder. When one emphasized the effect which particle properties, especially surface characteristics may have the level of the power data was much lower, although the data were of the same character as the characteristic values pertaining to the sand.

Cooling Requirement Charts for Electronic Equipment

Efficient installation of airborne electronic equipment requires adequate data to design a heat removal system for the airplane. For many years aircraft generators have been supplied with rating charts to define their cooling requirements: electronic equipment now requires similar treatment. The form of the chart depends on the nature of the equipment, but consists, essentially, of a nomograph showing required cooling airflow and pressure drop vs air temperature. When pertinent, it should also include such factors as life, output, surrounding wall temperature, etc. Such charts make it convenient to design and compare performance of ram and fan driven cooling systems, and to compare different equipment designs in terms of their flow and pressure drop requirements. Examples of several different types of charts, their preparation and their use, are presented.