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1.
Measuring techniques for characterizing gas/liquid reactors . The article considers measuring techniques for the characterization of the phases in gas/liquid reactors. These include the velocity profile and turbulence in the continuous phase as well as holdup, size, and velocity of the dispersed phase. Also, methods for the determination of the specific interfacial area and the volumetric mass transfer coefficients are discussed. Measuring methods have made enormous advances in recent years. In spite of this, there is a lack of reliable methods, especially for use during reactions without disturbing the state of the reactor. It is suspected that probe technique will gradually fall into disuse and more and more attention will be focussed on contractless methods. This calls for further development of ultrasonic methods and methods relying on emission of light. 相似文献
2.
H. Schilingmann K. Wittmann D. Wippern H. Helmrich K. Schügerl 《Computers & Chemical Engineering》1979,3(1-4):53-58
In a bench-scale, stainless steel reactor, experiments were carried out to investigate fluidized bed behavior by means of on-line process control. The non-catalytic thermal decomposition of sodium hydrogen carbonate to sodium carbonate, carbon dioxide and water was used a model reaction. The experimental equipment was provided with control systems and reulating units which were connected to a PDP 11/40 computer by means of suitable analogue and digital input/output interfaces. The operating conditions are highly influenced by the chemical reaction as well as by the fluid-dynamical behavior of the reactor. Several experiments were carried out to evaluate the kinetics of the model reaction. The fluid-dynamics was investigated by means of on-line experiments with and without chemical reaction. Based on the experimental results, a model was developed to describe the whole process so that model simulations should yield information on the process itself. With this model, strategies are tested before they are applied to the process computer for on-line process control. 相似文献
3.
Following properties of short bubble columns employing CMC solutions (1.0, 1.4 and 2.0%) and perforated plates (0.5, 1.0 and 3.0 mm hole diameters) were determined: relative mean gas hold up, EG, bubble size distribution, Sauter bubble diameter, ds, and the specific geometrical bubble surface areas, a' and a' due to the “intermediate to large bubbles.” The a' values were compared with the corresponding volumetric mass transfer coefficients, kLa's and the mass transfer coefficients, kL, were estimated. The properties of these systems were investigated as function of the superficial gas velocity, WSG, CMC concentration and aerator type. 相似文献
4.
5.
The transverse mixing of quartz sand (mean particle sizes 157, 323, 794 and 1038 μm) and sodium carbonate (soda) (mean particle size 137 μm) has been investigated in a laboratory rotary drum reactor of 300 mm length and 310 mm diam. Solid movement in the drum was observed by means of colored tracers and successive exposures as well as by means of hot tracers and recording the local temperature in the bulk of particles. Three different types of the particles and bulk behaviour could be observed for stickly particles. The time constant of the mixing was estimated as a function of the rotational speed of the drum. The “cooling-down” curves of the bulk of particles were measured in a laboratory oven of 250 mm diam. and 600 mm length. The temperature variation as a function of the time can be described by the Newtonian cooling law, from which the heat transfer coefficient at the wall αw was estimated.The absolute value of αw's and their dependence on the contact time and particle diameter cannot be calculated by the heat penetration model, which disregards the film resistance at the bulk/wall contact. By taking into account this resistance a good quality of fitting can be achieved. 相似文献
6.
Caroline Schulten Hans M. Tensi Johann Högerl 《JOM Journal of the Minerals, Metals and Materials Society》1996,48(5):57-59
Chinese TLV-bronze mirrors dating to the Han dynasty (206 B.C.-220 A.D.) were popular objects of everyday life as well as highly esteemed works of art. The decorated back of the mirror characterizes the culture of this period as well as the excellent early Chinese casting techniques. 相似文献
7.
Axial concentration profiles of O2, CO2 and SO2 have been measured at different radial positions in a coal-fired fluidized bed combustor. The profiles show some spatial inhomogeneity in the bed, the degree of which depends on fluidizing velocity and amount of excess air. Comparison of SO2- with CO2-concentration profiles reveals that SO2 is formed in proportion to CO2 only with anthracite as fuel. With bituminous coals, SO2 is preferentially formed near the coal feed point. These results are discussed with regard to characteristic times of mixing and chemical reaction in fluidized beds, and SO2-formation characteristics of the employed coals obtained in a thermobalance. 相似文献
8.
The removal of azo dyes from water by ion pair extraction is investigated. Mathematical relationships are derived from batch data and applied to the continuous extraction in a reciprocating plate extraction column. 相似文献
9.
10.
The instantaneons concentration of dioxane in freely suspended single toluene droplets was measured for an extremely wide range of droplet ages (0—600 sec) by means of a modified scintillation technique and the age dependence of the overall coefficients of mass transfer was evaluated. With increasing droplet age four consecutive exchange processes dominate with different decay constants for the concentration of solute which have very high, high, low, and very low exchange rates due to interfacial disturbances, turbulent internal mixing, transient internal mixing and desorption from the interface respectively.The decay constants of the first two processes decrease and the last two remain constant with increasing concentration of surface active agents. The overall decay constant decreases, goes through a minimum, increases, passes a maximum and finally decreases with increasing concentration of surface active agents. An explanation for this behaviour is given. 相似文献