The densities, viscosities and ultrasonic velocities of binary liquid mixtures of Isopropyl alcohol with acetophenone and methyl isobutyl ketone (MIBK) have been measured at temperatures 298.15 and 308.15 K over the entire range of mole fraction. From these data, acoustical parameters such as adiabatic compressibility (β), free volume (V f ) and free length (L f ) have been estimated using the standard relations. The results are interpreted in terms of molecular interactions present in the mixtures.

The development of the semi-theoretical correlation in Hadzisdmajlovic et al. (1983) for predicting the maximum spoutable height in a spout-fluid bed, is observed to involve certain discrepancies. Based on their experimental data, a new correlation is proposed. he concept of spout-fluidization was first introduced by T Chatterjee (1970) and since then several publications have appeared on this subject. Sutanto et al. (1984) observe that the term spout-fluid bed means different things to different authors and that Littman et al. (1976) and Vukovic et al. (1982) refer it to a condition in which normal spouting is accompanied by additional aeration, but not fluidization of the annulus and hence it is more appropriate to call it "Spouting with aeration". The present paper deals with the prediction of the maximum spoutable height in such spoutfluid beds.Littman et al.(1 976) reported that the maximum spoutable height in a spout-fluid bed (HmSf) is the same as that for a spouted bed (H,) for a given system. However, the work of Hadzisdmajlovic (1980) has shown that Hmsf 5 H,, the equality applying only for the case of zero fluid feed into the annulus. The realization that the maximum spoutable height of a spout-fluid bed and a spouted bed are not the same has led Hadzisdmajlovic et al. (1983) to redevelop the equation for predicting minimum spout-fluid flowrate presented earlier by Littman et al. (1976). Since H,, is a parameter in those equations and its knowledge essential for predicting minimum spout-fluid flowrate, Hadzisdmajlovic et al.( 1 983) developed a semi-theoretical correlation for it. Semitheoretical correlation of Hadzisdmajlovic et al., for HmdFor developing the correlation Hadzisdmajlovic et al. (1983) assumed that the radial pressure-gradient at the spout-annulus interface is proportional to the radial velocity u,, and has a maximum value equal to that for minimum fluidization. This assumption gives the following relations On a observk que le dkveloppement de la corrklation semi-thkorique de Hadzisdmajlovic et al. (1983), permettant la prCdiction de la hauteur maximale "spoutable" dans un lit fluidisk "spoutC", impliquait certaines contradictions. On propose une nouvelle corrklation baske sur leurs rksultats expkrimentaux.

Silica gel 83.0 0.0006 to 0.0018 0.55 to 0.80

u 5 p u = yAo/W$ 7 41, 4 2 = variables defined by Equations ( 4 ) and ( 5 ) W, ws, W, = mass fraction of component undergoing transfer, mass fraction at surface, mass fraction far from surface = kinematic viscosity, (length) 2/time = scaled tangential distance, Equation (6) = density, mass/ ( length)3 = shear stress at surface, force/ (length) Combined reactors in which the mixed reactor is followed by a tubular reactor can be optimal for a large number of simple adiabatic exothermal reactions. In the present paper, optimality criteria defined earlier for simple reactions involving a single reactant species have been extended to reactions involving two reactant species and for a system of consecutive reactions. Vol. 16, No. 2 AlChE Journal H z Mi + M2 Since QI ( 1 -Xm) -CA = CAO (1 -X) AlChE Journal Page 275 VoL 16, No. 2The value of 17.3 given in reference 3 is wrongly printed, and a suitable erratum will appear soon.

397PT = recuperator pipeline air temperature in G8 measured by thermocouples in Table I1 and Figure 4 (circled points), K q1 = N / 0 2 = 4 for air and 0 for oxygen/steam in eq 10, mol/mol of O2 q5 = H20/Oz = steam/oxygen ratio in eq 9-11, mol/mol of 0 2 c 4 i = 41 + q 5 S = surface area of sample base (base of cuboid or cylinder), cm2 TC = calculated temperature, an intermediate between CZTand link zone temperature, K V = volume of coal sample, cm3 VIa, Vza = volatile matter in coal sample before and after gasification, respectively, w/o W (E or C) = water content in product gas, v/o Wla, WZa = water content in coal before and after gasification, z = amount of fixed carbon reacting with 1 mol of 02, in eq respectively, w/o 8 and 11, mol/mol of O2 Registry No. H2, 1333-74-0. Literature Cited Barrer, R. M. Zeolites and Clay Minerals as Sorbents and Molecular Sieves; Academic: London, 1978.