Vor zehn Jahren wurde uber Gegenstromextraktionsapparaturen berichtet [l], in denen die beiden nicht mischbaren fliissigen Phasen durch kommunizierende, horizontal angeordnete Kammern fliessen. In jeder Kammer sorgt eine intensive Flussigkeitsbewegung fur eine rasche Einstellung des Verteilungsgleichgewichtes der Komponenten des zu zerlegenden Gemisches, ohne eine Aufteilung der Phasen ineinander in Form von Tropfen zu bewirken. Hiezu wird entweder das zylindrische Kammeraggregat um seine Achse gedreht oder es befindet sich in jeder ruhenden Kammer eine in beide Fliissigkeiten eintauchende Ruhrscheibe. Bei diesen Apparaten kann die Zahl der Kammern nicht uber etwa 30 gesteigert werden, da die Offnungen in den Kammerwanden klein gehalten werden miissen und hiedurch ein geringer Flussigkeitsaufstau von Kammer zu Kammer unvermeidlich ist.Im folgenden wird iiber Apparate berichtet, die nach demselben Prinzip der Einstellung des Verteilungsgleichgewichtes in jeder Kammer ohne Dispergierung arbeiten, bei denen die Kammerzahl aber sehr hoch getrieben werden kann. Es wird hiebei allerdings auf die Bewegung der beiden Phasen gegeneinander verzichtet und nur die leichte uber die in jeder Kammer verbleibende, also stationare schwere bewegt, so dass die Apparatur rnit einmaliger Gemischzufuhr am oberen Ende wie eine Chromatographiesaule arbeitet. Im weiteren ist das Kammeraggregat nicht horizontal, sondern mit einer Neigung von etwa 45" angeordnet.A pparatur und A rbeitsweise. Fig. 1
The mechanism of the iron-hydrogen sulfide reaction was studied in the 500~176 temperature range for a total gas pressure of 1 arm. The rate of attack was essentially constant (linear law), and the corrosion scale was composed of two layers: a thin dense layer adjacent to the metal and a porous layer with a coarse crystalline structure. These two features which differentiate this reaction from. the iron-sulfur vapor reaction are interpreted on the basis of two main effects: (a) partial blocking of reaction sites by hydrogen produced during attack, and occurrence of a reaction at a constant number of reaction sites; and (b) continuous recrystallization of the dense scale into a porous scale offering no barrier to transport of reactants. This mechanism is selfregulating.The following evidence is presented: (a) linear Arrhenius plots were obtained; (b) essentially the same rate of attack was observed for hydrogen-hydrogen sulfide and helium-hydrogen sulfide mixtures having the same partial pressure of hydrogen sulfide; and the dependence of rate on hydrogen sulfide pressure was accounted for; (c) the attack rate was not affected by the coating of specimens with a dense layer of varying thickness obtained by preliminary attack in sulfur vapor; (d) the iron-sulfur reaction, which obeys the parabolic law of attack, was inhibited by hydrogen diffusing from the back of the specimen surface; (e) recrystallization of the dense layer into the porous one was observed for specimens aged in helium; and (f) aging of iron sulfide with a fine crystalline structure (prepared by sulfur attack) in the corresponding hydrogen-hydrogen sulfide equilibrium mixture caused the scale structure to become somewhat coarse.Discussion of experimental methods covers the following points: (a) measurements of the rate of attack with a quartz spring balance in hydrogen-hydrogen sulfide and helium-hydrogen sulfide mixtures; (b) techniques for attack in sulfur vapor followed by hydrogen sulfide attack; (c) use of a mild steel cartridge containing lithium aluminum hydride in the hydrogen diffusion studies; and (d) scale thickness studies.The iron-hydrogen sulfide reaction at elevated temperatures has two unusual features which distinguish it from most other metal-gas reactions with solid scale formation: (a) the rate of attack becomes constant after a short time (a few minutes above 500~i.e., the attack follows a linear law; and (b) a scale composed of two layers is formed, the layer adjacent to the metal having a fine crystalline structure and the outer layer being of a porous and coarse structure. [See review of previous work in the recent paper of Dravnieks and Samans (1).] In contrast, the iron-sulfur reaction, according to Hauffe and Rahmel (2), follows the normal parabolic law of attack (corresponding to a diffusion controlled process) with formation of a single homogeneous scale having a fine crystalline structure. The same Postdoctoral fellow, 1957Postdoctoral fellow, -1958. Present address: product of attack, iron sulfide, is obtained in bot...
The total vapor pressures and the heats of mixing of the water‐tetrahydrofuran and water‐diethyl ether systems were measured at 25°. Density, index of refraction, and KARL‐FISCHER‐titration were used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, entropy functions, and excess volumes were calculated.
Im Kahmen von Untersuchungen uber organische Mischphasen [l] wurden dieTotaldampfdrucke P und die Mischungswarmen gE der Systeme Tetrahydrofuran (THF)-Diathylather (A) und Methanol (M)-Tetrahydrofuran bei 25" gemessen und die Partialdrucke, Aktivitatskoeffizienten, freien Zusatzenthalpien (GE) und Entropieterme (7' . S") bei dieser Temperatur daraus berechnet.
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