Impinging stream contactor

The efforts to search for approaches to raising relative velocity between phases has led to the development and/or application of impinging stream contactors, and also some other devices. 

Starting with the elements necessarily included, the concept of impinging streams can be extended to include various flow configurations. Tamir el al. [5] investigated a number of impinging stream contactors with different flow configurations and the... 

Figure 2 Impinging stream contactors of various configurations [51. (a) Coaxial-horizontal two impinging streams (b) Horizontal three impinging streams (c) Coaxial-vertical two impinging streams (d) Curvilinear two impinging streams (e) Curvilinear four impinging streams (f) Four impinging streams. A—air P-—particles W water.

Wu and Wu [50, 51] studied the residence time distribution of particles in a typical co-axial horizontal gas-solid impinging stream contactor (ISC). The structure of the experimental impinging stream device is shown in Fig. 3.1. The body of the contactor is made of plexiglass. The horizontal cross section of the upper chamber is a square of 0.4x0.4 m, and the bottom is tapered sharply in order to avoid the solid material heaping up. This equipment essentially meets the requirements stated above. 

An impinging stream contactor usually contains several flow spaces of different natures, which exhibit not only different flow characteristics but also different contributions to the residence time distribution. 

In the impinging stream contactor shown in Fig. 3.1 the particles pass through the four sub-spaccs in series described above, and the overall residence time distribution... 

This is the model for the overall residence time distribution of the particles in the impinging stream contactor under consideration. The model contains several parameters related to equipment structure and operating conditions, i.e. the mean residence times in the four sub-spaces, 7ac, 7im, 7fai and cs. Among the four parameters, the mean residence time in the impingement zone, t m, and that in the collision-slipping region, fcs, are symmetrical parameters, which have the same influence on the overall residence time distribution. It can be seen from Eq. (3.27) or... 

The flow of the particles inside the impinging stream contactor has the characteristics of perfect mixing—plug flow in series ... 

Combining the results above, the overall resistance of the impinging stream contactor to the streams can be obtained as... 

Figure 4.1 Horizontal two-impinging stream contactor for study on the hydraulic resistance.

The pressure drops between Points A and C, between Points A and C, between Points A and B, and between Points A and B , denoted by -ApAC, -ApA C, -ApAB, and -A/Evb, respectively, are measured with inclined U-shape tubes filled with colored kerosene. The average of -ApAB and -ApA B- is taken as the pressure drop through the accelerating pipes, while that of -Ap v and -ApA c as the overall pressure drop across the impinging stream contactor, -ApT. Consequently, there should be... 

As described in Section 4.2, the sub-pressure drop measured between Points B and C or between Points B and C, -ApBC or -APb o is the sum of the pressure drop across the impingement zone, —Apim, and the structural resistance -A/ ds, but not any individual one of them. Such a measuring arrangement is not only because the pressure fluctuation frequently occurs round the impingement zone, making accurate measurement difficult, but also because both sub-pressure drops are too small (< 10 Pa) to be measured separately. To obtain the values for these sub-pressure drops, Eq. (4.17) can be specified for the impinging stream contactor studied here as... 

Combining the results of the theoretical analysis and the experimental investigation above, the overall pressure drop across the whole impinging stream contactor can be represented by... 

A comparison between the data measured for the overall pressure drop across the impinging stream contactor and the corresponding values calculated with Eq. (4.25) is illustrated in Fig. 4.6. Good agreement between the results measured and calculated can be observed clearly, suggesting that the total pressure drop model established is reasonable and feasible for application. In addition, it has the advantages of universal applicability and convenience in calculation. 

On the resistance constitution of the equipment system, the major conclusions that can be drawn from the investigation are (1) Where millets or rapeseeds are the material to be processed, the power for the operation of the impinging stream contactor is mainly (>80%) consumed in the acceleration of particles (2) The pressure loss due to the impingement between the opposing streams is independent of the presence of solid particles. 

Type of equipment Impinging stream contactor Flash dryer... 

In the primary design, following that of the solid-gas impinging stream contactor used in earlier investigations on RTD and hydraulic resistance etc., the two nozzles are placed in the middle of the gas conduits (Point A, represented by the solid lines in Fig. 

Wu, Gao an and Wu, Yuan (1997). RTD of particles in an impinging stream contactor of two horizontal jets—(I) A theoretical analysis. Proc. 2nd Joint China/USA Chem. Eng. Conf. 459-462, Beijing. 

Tamir, A. and Glizenstien. A. (1992). Modeling and application of a Semibatch coaxial two-impinging -stream contactor for dissolution of solids. The Canadian J. Chem. Eng., 70 104-114. 

Cocalia, V. A., Jensen, M. P., Holbrey, J. D., Spear, S. K., Stepinski, D. C. Rogers, R. D. (2005). Identical extraction behavior and coordination of trivalent or hexavalent f-element cations using ionic liquid and molecular solvents. Dalton Transactions, 2005, 1966-1971. de Menech, M., Garstecki, P., Jousse, F., Stone, H. (2008). Transition from squeezing to dripping in a microfluidic T-shaped junction. Journal of Fluid Mechanics, 595, 141-161. Dehkordi, A. M. (2001). Novel type of impinging streams contactor for liquid-liquid extraction. 

Dehkordi, A.M. (2001) Novel type of impinging streams contactor for liquid- 73. liquid extraction. Ind. Eng. Chem. Res.,... 

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