Showing papers in "Chemical Engineering Science in 1990"

TL;DR: In this article, the authors discuss past theoretical works on fluid-solid reactions in a porous medium and discuss the fundamental role of connectivity of the porous medium in such phenomena, and compare two different modelling approaches to reactions accompanied by structural changes.

TL;DR: In this paper, the dusty gas diffusion model was applied for the description of intra-particle diffusion limitations in methanol synthesis over a commercial Cu-Zn-Al catalyst.

TL;DR: In this paper, a generalized Maxwell-Stefan (GMS) formulation of irreversible thermodynamics is used to describe surface diffusion of n sorbed species using the GMS formulation of reversible thermodynamics.

TL;DR: In this paper, the authors propose a two-stage synthesis procedure that employs one minimum allowable composition difference for all possible rich-lean stream pairs and a mixed-integer linear program is used to yield minimum-utility cost networks in which the number of mass-exchanger units is minimized.

TL;DR: In this article, the chemical equilibria of the methanol reaction and the water-gas shift reaction, starting from carbon monoxide, carbon dioxide and hydrogen, were studied in a fixed-bed catalytic reactor at P = 10-80 bar and T = 200-270°C.

TL;DR: In this article, a noninvasive Computer Automated Radioactive Particle Tracking (CARPT) facility is used for the investigation of liquid recirculation and turbulence in a bubble column.

TL;DR: In this paper, the microkinetics for the liquid phase synthesis of methyl tertiary butyl ether (MTBE) from methanol and isobutene using a macroporous sulfonic acid ion exchange resin as catalyst (Amberlyst 15, CVT resin) were determined experimentally in a continuous stirred tank reactor in the temperature range 323-363 K at 2.1 MPa.

TL;DR: In this article, the influence of viscosity on the strength of an axially, periodically strained pendular bridge was investigated where bridge strength is defined as the maximum interparticle force developed during one complete sphere oscillation.

TL;DR: In this article, a case study for the production of 3600 t/d hydrocarbons starting from wood is evaluated, where six HydroThermal Upgrading (HTU) units convert wood into biocrude containing 10 %w oxygen.

TL;DR: In this paper, the synthesis problem of complex nonisothermal reaction networks is addressed, where the authors focus on developing a superstructure of alternatives for the non-isothermal reactor system, and subsequently formulate and solve the problem according to the proposed general structure.

TL;DR: There is increasing interest in high-velocity fluidized bed reactors operated in the turbulent and fast fluidization regimes, and there are prospects for applications beyond those practiced in industry at this time as mentioned in this paper.

TL;DR: In this article, a modified version of the Sander model for predicting salt effects on vapor-liquid equilibria (VLE) has been proposed, which combines a Debye-Huckel term with a modified UNIQUAC equation with concentration-dependent parameters.

TL;DR: In this paper, the authors derived geometrically based constructive necessary conditions for variables which obey linear mixing laws, using these necessary conditions, global optimization problems with algebraic objective functions of the basis variables may be solved generating both optimal reactor configurations and operating parameters.

TL;DR: In this article, the non-square relative gain array (NRG) is defined as the ratio of the open-loop gain, when all loops are without any control, to the closed-loop gains, where all loops other than the loop explored are under perfect control in the least square sense.

TL;DR: In this paper, the influence of both pressure and gas molecular weight on bubble size and gas hold-up in a bubble column was studied and it was determined that gas holdup increases whereas the bubble size decreases with increasing gas density at a constant superficial gas velocity.

TL;DR: In this article, a dynamic two-phase model incorporating a k-e turbulence model, compressible gas phase and axisymmetry is presented, based on a first principles approach where the parameters are fundamental in nature and as far as possible, obtainable from general fluid dynamics literature.

TL;DR: In this paper, a simple algebraic method for calculating the minimum flows for non-ideal multicomponent distillation columns has been developed, which is based on an analysis of the geometry of the composition profiles in the state space, and applies to ideal, nonideal and azeotropic mixtures.

TL;DR: In this article, a finite-element model has been developed to study the ohmic heating of foods, and the equations solved by the model are described, and it is shown that the model predicts the behaviour of real systems.

TL;DR: In this paper, it was shown that for small values of the molecular Peclet number no resistance at the rigid wall exists, and that the effect of lateral maldistribution of fluid velocity and/or thermal conductivity, of axial dispersion of heat, and of small, systematic errors in measurement is investigated.

TL;DR: In this paper, a similarity solution for the convective-diffusion equation governing the steady-state concentration of the boundary layer in crossflow microfiltration of the particles, under conditions where a thin stagnant layer of particles deposited on the microporous membrane surface provides the controlling resistance to filtration, is presented.

TL;DR: In this paper, a theoretical model of crossflow microfiltration which includes the time-dependent decline of permeate flux due to particle layer buildup is presented, based on the shear-induced hydrodynamic diffusion mechanism of particle motion within a concentrated flowing layer near to the membrane surface, balancing the convectively-driven flux of particles toward the surface.

TL;DR: In this paper, the phase transition of the microstructure and its effects on the observed bulk densities, discharge rates, and size segregation were investigated using a mass-flow hopper and a funnel.

TL;DR: In this paper, experimental heat transfer measurements for the flow of a lubricating oil on the tube side of a shell and tube heat exchanger are reported for the case where there is a steady net flow through the smooth walled tube and where periodically spaced baffles have been inserted.

TL;DR: In this paper, the rheological properties of fermentation broths of filamentous microorganisms were investigated using three different types of viscometers: (1) three online pipeline sensors (5.8, 11.6 and 15.4 mm i.d.), (2) two rotating cylinder sensors (Haake model RV12, MV2 and MV3 sensors), and (3) helical ribbon and turbine impeller viscometer sensors.

TL;DR: In this article, a methodology for identifying stoichiometric models for complex reaction systems is developed, which is useful for deriving simple, approximate stochastic models of complex systems, or testing possible stoichiometries and thereby investigating reaction pathways.

TL;DR: In this article, a Fischer-Tropsch conversion was used for the synthesis of carbon monoxide and hydrogen from the catalytic partial oxidation of natural gas with air, and two packed beds were placed in the reactor above and below the catalyst bed.

TL;DR: In this paper, the velocity of sound us in fluidised beds of particles, at or near incipient fluidisation, was measured by two methods: (1) by observing the damped pressure fluctuations immediately after giving the bed a sudden vertical impulse; (2) by cross-correlating the signals from two pressure probes, one above the other in an incipiently fluidised bed, the signals originating from a bubbling section of the bed immediately above the infinited section.

TL;DR: In this paper, the elasticity modulus of the bed structure as a consequence of interparticle forces has been investigated for homogeneous fluidized beds and shown to correlate bed expansion and bubble size during heterogeneous fluidization.

TL;DR: In this article, the authors derived a correlation for the liquid hold-up in a trickle-bed reactor, derived from fundamental considerations and a wide-ranging data base of some 5000 hydrodynamic experimental results.

TL;DR: In this paper, it is shown that some terms associated with the pressure calculations have been overlooked, which are essential for consistent calculation of the overall pressure drop independent of the choice of a control volume over which the pressure drop is computed.