摘要:

AbstractA new synthetic regenerable sorbent was developed as an alternative to limestone and dolomite for regenerative sulfur capture in fluidized bed combustion (FBCof coal. The sorbent consists of CaO (8‐9 wt%) on a spherical 3 mm diameter γ‐Al2O3support. A shrinking unreacted core model (SURE2) is proposed to describe the sulfation process. Experiments have been carried out in a 12 mm internal diameter fixed bed reactor, a 0.05 mIDfluidized bed reactor and a thermobalance. The results obtained for all three reactors are in good agreement with the predictions of theSURE2 m

ISSN:0008-4034    

DOI:10.1002/cjce.5450710112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effects of ratio of draft tube to reactor diameter (Dd/D), liquid nozzle diameter (dN), aeration tube diameter (dG) and immersion height of the two‐fluid nozzle into the draft tube (HN) on overall and annulus gas holdups for the air‐water system were evaluated experimentally in a reversed flow jet loop reactor over wide ranges of gas and liquid flow rates. Both the gas holdups increased with increasing gas and liquid flow rates and with decreasingdNandHN. The influence ofdGon gas holdups is found to vary with gas flow rates. Correlations are proposed to predict gas hold

ISSN:0008-4034    

DOI:10.1002/cjce.5450710113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA preliminary study of xanthan production byXanthomonas campestriswas performed in an external‐circulation‐loop airlift (ECL‐AL) fermenter. An average of 25 g/L xanthan of good viscosity characteristics was obtained in a total fermentation time of 49 hours. Oxygen limitation was observed after 36 hours of fermentation time. It is conclusively demonstrated that the ECL‐AL fermenter can be used to economically produce xanthan. The key operating and design features are the liquid height, downcomer‐to‐riser cross‐sectional area ratio (AD/AR) and the orfice diameter of th

ISSN:0008-4034    

DOI:10.1002/cjce.5450710114

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractAn organosolv (ethylene glycol) hardwood lignin has been thermally treated in the presence of tetralin, a hydrogen donor solvent. The effects of reaction temperature and time on product distribution were studied as a function of a seventy index,Xc= ℓn (RωwithRω= Δtt× exp [(Tr‐ Tb)/ω] where Δt= time,Tr= reaction temperature,Tb= base temperature, and ω = characteristic parameter. Under the conditions used, up to 60% of the lignin can be converted to liquid and gaseous products. Syringols, guaiacols, aromatic aldehydes and ketones predominate at low treatment severities whilst phenol, catechol and their methyl and ethyl derivatives are the main monomers at high severities. Comparison of our data with parallel works is shown to be effectively done through the severit

ISSN:0008-4034    

DOI:10.1002/cjce.5450710115

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA prototype hardwoodPopulus deltoidshas been fractionated in kg quantities into its primary constitutive polymers, namely, cellulose, hemicelluloses, and lignin, under optimal recovery conditions for each fraction.Our approach is targeted at processing sawdust or finally divided wood (dp≤ 0.5 mm) and involves a thermomechano‐solvolytic treatment of medium consistency suspensions in two process development units operated sequentially. Firstly, the hemicellulose fraction is removed from the initial wood by a aqueous‐steam pretreatment (auto‐hydrolysis) at conditions where nearly 90% of the hemicelluloses are solubilized. Secondly, the treated wood (lignocellulose) is separated into cellulose and lignin rich fractions by subjecting it to an organosolvolytic treatment using ethylene glycol as solvent. An experimental unit which can be operated in semi‐continuous or continuous modes is described and was employed for this step. The recovery of each fraction via appropriate mass balances is presented.Also, a comparative characterization of the lignins isolated via (a) the direct solvolysis route and (b) the sequential aqueous‐steam pretreatment followed by solvolysis approach is made using solvent fractionation, molar mass distribution, and13C NMR spectrosc

ISSN:0008-4034    

DOI:10.1002/cjce.5450710116

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractKinematic viscosity data (ν) are presented for ethane‐1,2‐diol, for N, N‐dimethylformamide and for nine binary mixtures in the ‐ 10°C to 80°C temperature range. The experimental data were fitted by several empirical relations such as Grunberg‐Nissan (1949), McAllister (1960), Heric (1966), Lobe (1973), Auslander (1964) and polynomial equations. Some considerations regarding the meaning of the obtained adjustment parameters are made. Furthermore, a new best fit equation is proposed and its validity has been compared to that of the other relations on the basis of the reproducibility of the exper

ISSN:0008-4034    

DOI:10.1002/cjce.5450710117

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper deals with the application of continuous thermodynamics to light and heavy oil systems using the Peng‐ Robinson equation of state. The composition of the high molar mass components in a reservoir oil is described by a continuous distribution function of some characterizing quantity, e.g. molar mass or boiling temperature. Numerical Gaussian quadrature methods are used to generate pseudo‐components and their mole fractions from distribution data. Several examples are presented for phase equilibria of solvent/crude oil systems. The results showed that semi‐infinite distribution functions, such as the Γ function, cannot be applied to all cases, e.g. dew point calculations. The Gauss‐ Legendre quadrature method coupled with spline fitting worked best for heavy oil

ISSN:0008-4034    

DOI:10.1002/cjce.5450710118

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractBinary and ternary solubility data were measured for the NaCl‐KCl‐H2O system in the temperature range 293‐360 K using a standard visual method. The solid‐liquid phase diagram of the ternary system was calculated from the binary data and from the activity coefficients of the electrolytes evaluated by the Pitzer model. Some empirical functions of temperature were used to describe the virial coefficients. The calculated ternary solubilities were compared with the experimental values yielding a very good agreement. Therefore, it was possible to conclude that, in the range of concentration and temperature studied, the Pitzer model provides an excellent representation of the activity coefficients, thus allowing the accurate prediction of solubilities in the ternary

ISSN:0008-4034    

DOI:10.1002/cjce.5450710119

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe flow of viscoplastic materials through extrusion dies has been studied numerically using the finite element method. Rheological data for viscoplastic doughs have been fitted by the Herschel‐Bulkley model, which incorporates a yield stress into the power‐law model. Non‐isothermal simulations show the extent and shape of yielded/unyielded regions and the development of temperature field assuming different modes of heat transfer at the boundaries. The results reveal that viscous dissipation causes appreciable temperature rises in the extrudate in agreement with measured values at the extruded material surface. The extrudate swell results show a maximum for a certain range of apparent shear rates also observed experimentally. However, the inelastic simulations based on the Herschel‐Bulkley model always under‐predict the experimental swelling values. A heuristic approach is also used to determine the level of elasticity required to produce the experiment

ISSN:0008-4034    

DOI:10.1002/cjce.5450710120

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of Reynolds number upon the extrusion of a Newtonian fluid exiting a square die is examined. It is shown that the extrudate swells at low Reynolds number but contracts at high ones. At zero Reynolds number, the maximum die swell ratio of 1.2 occurs. A swell ratio of one occurs at a Reynolds number of about 24. At large Reynolds numbers, the extrudate contracts to a circular cross‐section with a swell ratio of 0.961

ISSN:0008-4034    

DOI:10.1002/cjce.5450710121

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY