bluuebunny/crossref_metadata_2025_split huggingface dataset:
Noncatalytic conversion of residuum in two‐stage coal liquefaction
Authors: Stiegel G. J. , Lett R. G. , Cillo D. L. , Tischer R. E. , Narain N. K. 
Published: March 2009

AbstractAn experimental investigation was conducted to ascertain the contribution of thermal reactions in the hydroprocessing reactor of two‐stage liquefaction processes. Various solvent/residuum feedstocks were reacted in the absence of a catalyst at temperatures ranging from 655K to 728K. Detailed characterization of the composite and fractionated feedstock and product samples was performed to ascertain the extent of residuum conversion, heteroatom removal, and hydrogen rearrangement. The results showed that hydrogenation of the solvent portion of the feedstock neither enhances residuum conversion nor results in the transfer of hydrogen from the solvent to the residuum. Higher reaction temperatures also had little effect on the reactions involved. These results suggest that the conversion of residuum in the hydroprocessing reactor of two‐stage liquefaction processes must occur catalytically rather than thermally.
Gas hold‐up and mass transfer in a bubble column with viscoelastic fluids
Authors: Moo‐Young M. , Kawase Y. 
Published: March 2009

AbstractThe influence of viscoelasticity on gas hold‐up and the volumetric mass transfer coefficient in a bubble column is discussed and examined experimentally. It was found that the gas hold‐up increased due to an increase in the number of entrapped very small bubbles formed because of the elasticity of the liquid. On the other hand, a decrease in volumetric mass transfer coefficient due to the fluid elasticity was observed. Qualitative effects of an antifoam agent and a draft tube on the performance of the bubble column with viscoelastic fluids were also examined.
The solubility of sulfur dioxide and hydrogen sulfide in associating solvents
Authors: Hayduk W. , Pahlevanzadeh H. 
Published: March 2009

AbstractThe solubilities of SO2 are reported in the solvents N, N‐dimethyl acetamide (DMA), N, N‐dimethyl formamide (DMF), ethyl acetate, acetonitrile, chlorobenzene, methanol, (1,2‐ethanediol) ethylene glycol and acetone for atmospheric pressure and for temperatures ranging from 268 K to 333 K (‐5°C to 60°C). Solubilities of H2S are also reported for the first five of the above‐mentioned solvents and for hexane for similar conditions. These gases and solvents exhibit extreme molecular interactions which are reflected in unusual solubility behavior. This paper is a continuing attempt in providing data and analyses for improving the understanding of gas solubilities in complex gas‐solvent systems. Solubilities expressed as hydrogen‐bonding factors have been found useful in systematically relating gas solubilities in one associating or reacting solvent to another chemically similar solvent. Thus, with a limited amount of data for gas solubilities, it is often possible to predict solubilities even in highly associated or reacting gas‐solvent solutions.
A comparison of the reactivity of various metal oxides with SO3
Authors: Steward F. R. , Karman D. , Kocaefe D. 
Published: March 2009

AbstractVarious metal oxides were reacted with SO3 to compare their reactivity as potential adsorbents of sulfur oxides from flue gas. ZnO was found to be the most reactive of the eleven studied, including two mixtures, a fly ash and a calcined oil shale.It was found that a scanning electron microscope can be used to assess the reactivity of the oxide based on a rough estimation of internal pore structure from the micrograph of the particles.
Particle effects on free jet entrainment
Authors: Tatterson D. F. , Marker T. L. , Forgac J. M. 
Published: March 2009

AbstractThe effect of particles on entrainment into free jets has been reexamined. As previously reported, particles can increase, decrease or have no effect on jet entrainment. This study suggests that the effect correlates with the ratio of particle stopping distance to nozzle diameter. For values of this ratio less than 3 entrainment increases due to the presence of particles. For values of the ratio between 3 and 65, entrainment is decreased. For values greater than 65, the presence of particles in the jet has no effect on entrainment. If the suggested correlation proves to be correct, it will assist the design engineer who wishes to rapidly mix particles with surrounding gas in a free jet. In particular, the region where a decrease in entrainment is observed should be avoided as there will be a corresponding decrease in mass and heat transfer.
The redistribution of trace and minor elements during coal liquefaction
Authors: Pringle T. G. , Jervis R. E. 
Published: March 2009

AbstractRadioactivation analysis of four sets of coal liquefaction feed and product materials provided information on the concentrations of forty trace and minor elements. Coal‐derived oil was found to have low levels of most elements, comparable to crude petroleum. Aqueous process effluents were shown to have potentially troublesome levels, especially of Cr and Ba. The concentration data derived in this study and relevant process data were combined to construct elemental mass balances around the liquefaction process; these varied widely between about 80 and 140%, depending mostly on analytical errors. Enrichment of chromium and other transition metals in the conversion residues indicated a possible source through equipment erosion while consistent depletion of barium suggested a loss to aqueous stream particulate matter or possible reactor deposits.
Numerical simulation of a pressure swing air separation systemndasha comparative study of finite difference and collocation methods
Authors: Raghavan N. S. , Hassan M. M. , Ruthven D. M. 
Published: March 2009

AbstractThe efficiency of three different numerical methods (single and double collocation and 3‐point central finite difference) is compared for the solution of the set of partial differential equations describing the performance of a pressure swing adsorption (PSA) system for air separation on a carbon molecular sieve. It is shown that in terms of computer time there is little difference between single and double collocation methods but for comparable accuracy both these methods are very much faster than the finite difference method.
Fischer‐tropsch synthesis in a stirred tank slurry reactorndashreaction rates
Authors: Bukur Dragomir B. , Brown Russell F. 
Published: March 2009

AbstractThe effect of process variables (temperature, pressure, space velocity, and H2/CO feed ratio) on the Fischer‐Tropsch synthesis on a promoted fused iron catalyst was studied in a slurry phase stirred tank reactor (STR). Operating conditions were chosen such that some of the data could be compared with previously reported results, but experiments were also performed at more extreme conditions (temperatures up to 280°C and pressures up to 2.86 MPa) than previously studied in a slurry phase STR. The catalyst activity compares well with previous studies at an H2/CO feed ratio of 1.0 and 1.8, but the activity is lower than previously reported values in the 0.64‐0.72 range of H2/CO feed ratios. Spacetime‐yield increases with pressure, and reactor productivity is best increased by increasing pressure at a constant pressure to space velocity ratio. The water‐gas‐shift reaction is near equilibrium at high conversions, and always proceeds at a slower rate than the Fischer‐Tropsch synthesis in a STR.
Pyrolysis of 1,3‐butanediol as a model reaction for wood liquefaction in supercritical water
Authors: West Mary Ann B. , Gray Murray R. 
Published: March 2009

Abstract1, 3‐Butanediol was pyrolyzed at 425°C in a batch reactor as a model system for liquefaction of lignocellulosic materials such as wood. The observed gas and liquid products were consistent with fragmentation, dehydration, and condensation/polymerization reaction pathways. Reaction in supercritical water altered the selectivity of the reactions to give mainly propene and formaldehyde. Dehydration and the formation of two‐carbon products were suppressed by water. The conversion of 1, 3‐butanediol in dilute aqueous solutions increased three to four fold when the reaction density was increased by 33%. Trace oxygen was an important inhibitor, particularly in the dilute solution, but had only a minor effect on the reaction selectivity.
The phenomenon of thermal channelling in countercurrent gas‐solid heat exchangers
Authors: Wonchala E. P. , Wynnyckyj J. R. 
Published: March 2009

AbstractMaldistributed flow in moving‐bed reactors and heat exchangers is recognized to be a serious problem. Heat exchanger equations do not provide a clue to the cause. In this paper it is shown that maldistributed flow can occur even in perfectly homogeneous packed beds and that this arises because of inherent temperature non‐uniformities. The term thermal channelling is introduced to describe this effect.It is shown that simultaneous consideration of both the heat and the mechanical energy (the Ergun equation) balances predicts that the gas, in cooling a hot bed, divides into a multiplicity of stable channels with significantly differing mass velocities. This does not, however, occur for the inverse case of heating the bed. Further, it is shown that the system conditions where a multiplicity of states is stable can be defined in terms of an integral mean temperature and two dimensionless variables, NTU and the bed Reynolds number. In general tall beds with large temperature differences are most prone to thermal channelling.
Kinetic modelling of a fluidized bed claus plant
Authors: Birkholz Robert K. O. , Behie Leo A. , Lana Ivo G. Dalla 
Published: March 2009

AbstractA kinetic model of a fluidized bed Claus reactor was developed using the Modified Bubble Assemblage Model (MBAM) to establish the practical implications of fluid bed technology for this new application. Simulations predicted that a two stage sub‐dewpoint fluidized bed Claus plant is capable of achieving a recovery efficiency of 97.1%, which is comparable to a conventional three stage fixed bed plant, but considerably less than the overall equilibrium conversion of 99.5%. Conversion is limited by gas‐bypassing, particularly in the downstream sub‐dewpoint reactor. In the fluidized bed process, about half the catalyst is required and the pressure drop is significantly lower compared with a conventional plant of equivalent capacity. Moreover, the capital cost estimate for a two reactor fluid bed Claus plant (200 t/d sulphur) was estimated to be $20 million (Can) which is within 10% of a conventional plant.
The influence of geometrical factors and feedstock on gasification in a high temperature fluidised bed
Authors: Tomeczek J. , Kudzia W. , Gradonń B. , Remarczyk L. 
Published: March 2009

AbstractResults are presented for gasification of coal and char by means of air or air‐steam mixtures in fluidised bed reactors of three different volumes. Two sizes of coal feedstock particles, 0.5‐1.0 mm and 1.0‐1.5 mm, and one size of char particles, 0.5‐1.5 mm, were used. The calorific value of generated gas and the carbon conversion are presented as a function of particle residence time. For coal gasification higher carbon conversion has been obtained at the same particle residence time than for char gasification. For the steam gasification, a lower gas heating value of about 4 MJ/m3 (S.T.P.) was obtained.
Application of parametric control concepts to decoupler design and heating control design for a batch reactor
Authors: Jutan Arthur , Rodriguez E. S. 
Published: March 2009

AbstractParametric control involves expressing the manipulated variables of a process in terms of a new set of variables, called parametric variables. The control engineer can choose the functional relationships between the two sets of variables to provide added flexibility in control loop design. The design of a static decoupler and the linearization of a batch reactor heating system are provided as examples.
Development of a procedure for selecting the optimum adsorbent for abs removal
Authors: Chiang P. C. , Lou J. C. , Tseng S. K. 
Published: March 2009

AbstractThe objective of this paper is to demonstrate the capability of some commercially available adsorbents (XAD‐2, XAD‐8, Activated Carbon) to treat waste water containing ABS (Alkyl Benzene Sulfonate). Laboratory experiments were performed to determine the adsorption capacity, effective diffusion coefficient and activation energy for each adsorbent. As a result, the AC‐B and XAD‐2 adsorbents were selected as potential adsorbents to run column tests i.e., service and regeneration cycles. Based on the results of treatability studies the optimum adsorbent was chosen. The most effective regenerant (CH3OH) was found on the basis of the extraction (distillation) efficiency and unit price associated with each organic solvent.
Kinetics of and catalyst decay accompanying the gas phase rearrangement of cyclohexanone‐oxime over a hy ultrastable zeolite
Authors: Burguet M. C. , Aucejo A. , Corma A. 
Published: March 2009

AbstractThe kinetics of the rearrangement of cyclohexanone‐oxime has been studied in a fixed bed, glass tubular reactor at atmospheric pressure and temperatures of 240, 270, 300 and 335°C, using ultrastable HY zeolite catalyst. Several kinetic models, including the Langmuir‐Hinshelwood type, have been derived and the best statistical fit has been obtained with a pseudo‐first order kinetic equation. The rate constants and activation energies for the formation of the products caprolactam, cyclohexanone and 5‐cyanopent‐l‐ene have been calculated. Based on the evolution of the selectivity with temperature, and the I.R. spectra of the poisoned catalyst, different decay models have been deduced and discussed.
Rising velocity of a swarm of spherical bubbles in a power law non‐newtonian liquid
Authors: Gummalam S. , Chhabra R. P. 
Published: March 2009

AbstractPrevious work on the rise of a swarm of bubbles in non‐Newtonian media has been reviewed. Variational principles have been combined with the Happel free surface cell model to obtain upper and lower bounds on the swarm velocities of bubbles rising slowly through power law liquids. The predictions presented herein encompass wide ranges of gas holdup and shear‐thinning behaviour.
Heat transfer coefficients in coiled stirred‐tank systems
Authors: Aksan Devlet , Borak Fahir , Ilsen önsan Z. 
Published: March 2009

AbstractSteady‐state and transient heat transfer coefficients were determined in coiled, stirred‐tank systems with single‐tank and two‐tanks‐in‐series arrangements, using flat‐blade turbine impellers and water. Flowrates, hot water temperature and agitator speed were varied for Re between 19,000 and 77,000 for the agitated side, covering the Re = 20,000–40,000 range for which published data are not available.
Dispersing behaviour of droplets in suspension polymerization of styrene in a loop reactor
Authors: Tanaka Masato , O'Shima Eiji 
Published: March 2009

AbstractSuspension polymerization of styrene was performed using a loop reactor. The dispersing behaviour of the droplets in the course of the reaction was observed. The mean droplet diameter was determined by the energy level at the impeller region. Moreover, the final particle size distribution and mean particle size were also determined after an elapsed time of 1‐2 hrs.An expression which correlated the final mean particle size with the operating conditions, such as the mixing conditions at the impeller region and the initial physical properties of the suspension system, was derived. The deposition of polymers on the reactor wall was found to be prevented due to the high fluid velocity.
Mixed convection heat transfer in porous media in the non‐darcy regime
Authors: Islam Rafiqul M. , Nandakumar K. 
Published: March 2009

AbstractIn this study mixed convection heat transfer in a homogeneous porous duct of square cross section in a horizontal orientation is examined. Results from a generalized Forchheimer model are compared with that from the Darcy model. The heat transfer rate and the flow behavior depend on the following parameters: Grashof number, Gr = Q'gβKa/kv2, an axial flow pressure drop parameter, ζ = (aK/vμ)dp'/dz', an inertial parameter ξ = mK/a, appearing in the Forccheimer model and the Prandtl number, Pr = Cpμ/k. In the Darcy limit, ξ → 0, the role of the axial flow parameter, λ is reduced to a mere scale factor and the flow behavior is determined by a single parameter, λ = Gr · Pr. Both the Darcy and the Forchheimer models exhibit dual solutions and a hysteresis behavior over a certain range of Gr. Such parametric dependence can be used as an additional tool along with carefully designed experiments to determine the importance of inertial and Prandtl number effects on convective heat transfer in porous media.
Oxygen transfer into newtonian and non‐newtonian fluids in mechanically agitated vessels
Authors: Ogut Ali , Hatch Randolph T. 
Published: March 2009

AbstractOxygen transfer into Newtonian and non‐Newtonian fluids was studied in stirred tank vessels of 0.0018, 0.006 and 0.036 m3 operating volumes. Emphasis was given to the rheological effects of the pseudoplastic medium on the volumetric oxygen transfer coefficient, KLa. Results indicate that KLa is a strong function of gassed power input per unit volume (Pg/V) for the Newtonian fluid, but a weak function of Pg/V for the non‐Newtonian fluid, and a strong function of superficial gas velocity (Vs) for both fluids for paddle‐type impellers. KLa is found to decrease rapidly with an increase in apparent viscosity for values of μa greater than 2.0 Pa · s. In addition to various correlations, a dimen‐sionless correlation including the impeller Reynolds number, impeller Weber number, and the aeration number is presented for the prediction of KLa in a gas‐liquid non‐Newtonian system.
A scanning electron microscope study of structural changes during the liquefaction of poplar sticks by rapid aqueous thermolysis
Authors: Boocock David G. B. , Kosiak L. 
Published: March 2009

AbstractScanning electron microscopy shows that the liquefaction of poplar sticks (6.35 mm square cross section) by aqueous pyrolysis first involves the surface disruption of the middle lamella. The latter and cell walls then fuse, and the flowing matrix then engulfs the cells. At surface temperatures of 280°C spherical structures appear within the stick, particularly on vessel walls. Flowing matrix fills irregular cavities within the stick and gas or vapour bubbles are formed. The spherical structures are insoluble in ether, which dissolves monomeric material, but are disrupted by chloroform which dissolves oligomers. Acetone which dissolves higher molecular weight material, removes the spheres.
Suboptimal control through model reduction
Authors: Gupta Y. P. 
Published: March 2009

AbstractThere has been a growing interest in control strategies that optimize a given performance criterion to improve process efficiencies. Optimal control techniques, such as LQP, have been available but did not find much acceptance in process industries because of certain problems that are involved in their application. In this paper an approach is presented which alleviates these problems. Simulation results show that the proposed approach works well for servo and regulatory control problems.
Gas‐solid contacting in a two‐dimensional fluidized bed containing mobile internals: Non‐reactive tracer studies
Authors: Gbordzoe E. A. M. , Littman H. , Bergougnou M. A. 
Published: March 2009

AbstractThe effect of 50.8 mm diameter disc shaped mobile internals (MIs) on gas‐solid contacting was studied in a large two‐dimensional fluidized bed by means of non‐reactive tracers. MIs were found to improve substantially the mass transfer coefficient between the bubble and dense phases. However, they also increased the gas dispersion in the dense phase.
Modified oil agglomeration process for coal beneficiation. I. Mineral matter liberation by fine grinding with the szego mill
Authors: Bajor Oliver , Trass Olev 
Published: March 2009

AbstractThe spherical oil agglomeration technique developed at the National Research Council of Canada (NRC) is an excellent method for cleaning and recovering very small coal particles. The finely ground coal, dispersed in water, is contacted with oil by intensive mixing. The hydrophobic coal particles collect onto the oil droplets to form the agglomerates which are then separated from the aqueous phase by screening.A Szego Mill was used to wet grind Minto (New Brunswick) coal which was then subjected to laboratory agglomeration by the NRC procedure. A comparison with coal ground in a ball mill indicated superior ash rejection. The improved performance is attributed to better mineral liberation which is enhanced by the more flaky particles produced in the Szego Mill.
Kinetics of the methanation of carbon dioxide over a supported Ni‐La2O3 catalyst
Authors: Kai Takami , Takahashi Takeshige , Furusaki Shintaro 
Published: March 2009

AbstractThe kinetics of the methanation of carbon dioxide was investigated using an alumina supported Ni‐La2O2 catalyst in a differential and integral reactor. In the differential reactor the molar ratio of H2 to CO2 was varied from 0.6 to 30. In the integral reactor the rates were measured with up to 90% conversion. Both reactor tests were carried out at temperatures between 513 and 593 K. The experimental results were described by a Langmuir‐Hinshelwood type equation. The kinetics can be explained by assuming equilibrium of dissociative carbon dioxide and hydrogen adsorption, and assuming hydrogenation of surface carbon as the rate determining step.
The effect of surfactants on peat dewatering
Authors: Cooper D. G. , Eccles E. R. A. , Sheppard J. D. 
Published: March 2009

AbstractThe effect of cationic, anionic and neutral surfactants on the mechanical dewatering of a highly decomposed fuelgrade peat has been examined. Surfactant adsorption and zeta potential of the peat particles correlated with dewatering of peat samples. The cationic surfactants had large positive effects on dewatering, the anionic surfactants had a negative effect while the neutral surfactant had no effect. The effects of the surfactants could be explained by charge neutralization and double layer suppression. The cationic surfactants were superior to analogous organic salts because of enhanced interaction by the hydrophobic effect.
Regeneration of cracking catalyst influence of the homogeneous CO postcombustion reaction
Authors: Morley K. , De Lasa H. I. 
Published: March 2009

AbstractAccompanying the fast burning of coke on a cracking catalyst is the oxidation of the coke burning product, carbon monoxide. This carbon monoxide combustion involves a homogeneous and a catalytic reaction. The homogeneous reaction was isolated by injecting pulses of CO, CO2 and O2 into a laboratory scale reactor at controlled temperature and pressure. The coke burning and catalytic CO combustion reactions were studied by oxidizing coke deposited on a zeolitic catalyst in the same microcatalytic reactor. The role of homogeneous CO oxidation during coke combustion under these conditions was determined.
Use of nonlinear transformations and a self‐tuning regulator to develop an algorithm for catalytic reactor temperature control
Authors: Onderwater D. , Macgregor J. F. , Wright J. D. 
Published: March 2009

AbstractPrior to developing a multivariable control scheme for conversion and production rates in a packed bed tubular reactor carrying out highly exothermic reactions, it was important to stabilize the reactor temperature. In this paper we illustrate the use of a self‐tuning regulator to develop an inner loop controller that satisfies some necessary conditions on temperature response, and that is capable of controlling the reactor over a wide range of operating conditions. The importance of using a nonlinear transformation of the reactor hot‐spot temperature is demonstrated. Varying the input constraining parameter in the “one‐step optimal” self‐tuning controller is shown to be a very effective way of achieving a controller with the desired properties for response smoothness.