Kinetics of coal liquefaction under supercritical conditions

Abstract

Ind. Eng. Chem. Process Des. Dev. 1986, 25, 705-710 705 computational efficiency. Thus far, even though the program has been found to converge in 2 or 3 iterations, each iteration takes about 11 cpu min on a VAX 11/750 minicomputer, using 50 packing increments in the finite difference grid. AcknowledgmentWe gratefully acknowledge support of this research effort by the Environmental Protection Agency under Cooperative Agreement No. CR-809317. Nomenclature a = interfacial are per unit volume of packing, area/volume CGi = heat capacity of i in gas phase, energy/(time-area-de-capacity of i in liquid phase, energy/(time-areagi = molar flow rate of i in gas phase, moles/(time-area) G = total molar flow rate of gas phase, moles/(time-area) hi* = partial molar enthalpy of component i in the liquid at hG' = gas-phase heat-transfer coefficient corrected for mass hL = liquid-phase heat-transfer coefficient, energy/ (time-Hi* = partial molar enthalpy of component i in the gas at HG = enthalpy of the gas phase, energy/mole HL = enthalpy of the liquid phase, energy/mole AHsi = heat of solution of i, energy/mole in solution Ki = Henry's law constant kXi = mass-transfer coefficient for component i in liquid phase, kYi = mass-transfer coefficient for component i in gas phase, li = molar flow rate of i in liquid phase, moles/(time-area) L = total molar flow rate of liquid phase, moles/(time-area) Ni = molar flux of i across the gas/liquid interface, moles/ gree) degree) concentration xi* and temperature T* transfer, energy/ (time-area-degree) area-degree) concentration yi* and temperature T* moles/ (time-interfacial area) moles/ (time-interfacial area) (time-interfacial area) nc = number of components in system TG = bulk temperature of gas phase, degrees TL = bulk temperature of liquid phase, degrees To = reference temperature, degrees T* = interfacial temperature, degrees xi = mole fraction of i in liquid phase xi* = mole fraction of i in liquid-phase interface yi = mole fraction of i in gas phase yi* = mole fraction of i in gas-phase interface z = position in column, length hi = latent heat of vaporization of i, energy/mole Literature Cited Ackerman, 0. Forschungsheff 1837, 382, 1. Bllllngsley, D. S.; Chirachavala, A. AIChE J . 1981, 2 7 , 966. Felntuch, H. M.; Treybai, R. E. Ind. Eng. Chem. Process Des. Dev. 1978, Finlayson, B. A. "Nonllnear Analysis in Chemical Engineering", 1st ed.; Holland, C. D.; Lapls, A. I. "Computer Methods for Sohrlng Dynamic Separa-Kelly, R. M. Ph.D. Thesis, North Carolina State University, Raleigh, 1981. Kelly, R. M.; Rousseau. R. W.; Ferret J. K. Ind. Eng. Chem. Process Des. Klng, C. J. "Separation Processes", 2nd ed.; McGraw-Hill: New York, 1980; "Landolt-Ei5rnstein. Zahlenwarte und Funktionen 6. Auflage IV. Band Technik, 4. Teil Warmetechnik Bestandtell C1, Absorption in Flussigkelten mlt niedrigem Dampfruck"; Springer-Verlag: Berlin-Heldelberg-New York, 1976. LazabCrabtree, H.; Breedveld, 0. J. F.; Prausnitz, J. M. AIChE J . 1980, 2 6 , 462. McDaniel, R.; Holland, C. D. Chem. Eng. Sci. 1970, ...

Reactions at supercritical conditions: Applications and fundamentals

“…For instance, at 375"C, 0.3 g/cm3 water density, and a 15 min residence time, introducing the coal directly into SC water produced 75% THF solubles, whereas mixing water and coal at ambient conditions and then heating them together to supercritical conditions produced only 60% THF solubles. Similar trends for the variation in the yield of THF solubles with solvent density were also reported when SC toluene was the solvent (Deshpande et al, 1986). This group formulated a kinetic model based on the hypothesis that a part of coal dissolved instantaneously in the SCF and underwent liquefaction reactions that formed oils, asphaltenes, gases, and char.…”

Modeling of desorption at supercritical conditions

“…In the past years it has been realized that density plays an important role at supercritical conditions (Paulaitis et al, 1983;Funazukuri et al, 1985;McHugh and Krukonis, 1986;Deshpande et al, 1986). It may therefore be more suitable to calculate the apparent desorption activation energies at fixed densities, than at fixed pressures.…”

Catalytic Thermochemical Processes for Biomass Conversion to Biofuels and Chemicals

“…Pressure increases the density of solvent to facilitate solvent penetration into molecules of biomass components, which results in enhanced decomposition and extraction (Deshande et al, 1987). According to Le Chatelier's principle, one would expect that the higher the pressure during liquefaction, the less liquid components are gasified.…”