Substantiating the selection of recirculation circuits in technology for synthesizing liquid hydrocarbons from natural gas

Process flow schemes of the production of liquid hydrocarbons from natural gas were considered. Based on the proposed flow schemes, a mathematical model of the process was constructed. The overall material balances and energetic characteristics of the process were calculated. The application of recirculation circuits was shown to have high target product yields per unit feedstock gas.     

ADSORPTION OF TOLUENE ON BENTONITES MODIFIED BY DODECYLTRIMETHYLAMMONIUM BROMIDE

The adsorption of toluene was studied by using various types of adsorbents (Na⁺- and Al³⁺-bentonite) modified by dodecyltrimethylammonium bromide (DTAB). The characterization of these new sorbing matrices by XRD and IR indicates that DTAB tallow interacted with bentonite and increased the interlayer spacing of the clay with double-layered formation. Adsorption of toluene on modified bentonites was characterized by linear isotherms with no limitation of adsorption within the concentration range studied, thus indicating a mechanism of adsorption due to partition. Adsorption was fast and favored by a slightly acid medium. Pseudo-first-order, pseudo-second-order, the Elovich equation, and intra-particle diffusion models were used to fit the experimental data. The adsorption kinetic of toluene was described by the pseudo-first order onto DTAB-Na-bent, and pseudo-second order onto DTAB-Al-bent. The intra-particle diffusion process was identified as the main mechanism controlling the rate of toluene adsorption. Thermodynamic parameters such as standard free energy change (ΔG ⁰), the standard enthalpy change (ΔH ⁰), and the standard entropy (ΔS ⁰) were also evaluated. The variation of adsorption energy versus the types of adsorbent suggested a physical adsorption mechanism.     

FLOW OF LIQUID FILM ALONG CYLINDRICAL SURFACE. Part I. Theoretical Considerations

The calculation of the profile of a liquid film flowing along an inclined cylindrical surface, that is not completely wetted, is presented. Surface tension and contact angle are taken into consideration, and wave motion is neglected. The situation is described by a second order non-linear differential equation. A general solution, represented by a set of elliptical integrals, is given in dimensionless form

The case of liquid film hanging from and flowing along a wire of circular cross-section is discussed in detail. For selected values of wire diameter and contact angle a set of profiles was obtained numerically. The liquid hold-up as well as the corresponding interfacial area of gas-liquid contact were obtained. Further, the method enables us to calculate the gas-liquid interfacial area from the liquid hold-up. In the case of a laminar flow, it is possible to carry out a complete analysis of the problem, including no empirical parameter, on solving the Navier-Stokes equation.     

Thermal explosion of a mechanically activated 3Ni-Al mixture

Results of studying the thermal explosion of 3Ni-Al mixtures after their preliminary mechanical activation in a planetary ball mill are described. Reduction of the initiation temperature and effective energy of activation of interaction between the reagents to anomalously low values is found. Results of an x-ray diffraction analysis and an electron-microscope study of the thermal explosion products and initial mixtures with different times of mechanical activation are given.