Mixing and Attainability

It is possible to cause phase transition without the addition or removal of heat and without any pressure change by bringing together streams with distinct compositions. The process of mixing and attaining equilibrium may involve the transition of certain components from one phase to the other. As this takes place, temperature changes are expected due to heat of condensation or vaporization. Example 1.16 illustrates these effects. 

Figure 5.29. Models of feed tray (a) first mixing then attain equilibrium, and (b) mixing and attain equilibrium simultaneously.

Interstage Mixing Efficiencies Mixing or stage efficiencies rarely achieve the ideal 100 percent, in which solute concentrations in overflow and underflow hquor from each thickener are identical. Part of the deficiency is due to insufficient blending of the two streams, and attaining equilibrium will be hampered further bv heavily flocculated sohds. In systems in which flocculants are used, interstage effi-... 

To attain adequate surface contact between the reacting solids it is necessary to use the ingredients in fine condition and to bring them into contact by pressure. To maintain both solid contact and thermal conductivity correct, the density of the column is controlled at a uniform value. The manufacture of satisfactory delay compositions, therefore, entails the provision of suitably sized ingredients followed by adequate mixing and accurate pressing. 

Like many other reservoirs in the temperate regions, Mequinensa is monomictic. The thermal stratification begins in spring, intensifies and attains its maximum in summer. In the autumn the water column mixes and water temperature is uniform in the vertical dimension in winter. The summer stratification is more intense close to the dam [39]. In this area, during the stratification period the surface temperatures can attain 24-27°C, while at the bottom remain around 14—16°C [36-39]. 

Higher expansion is attained in cement-rich mixes and this decreases as the cement content is lowered. In general, a minimum cement content of 280 kg m 3 is required to obtain desired expansion values [78, 80],... 

For each series of measurements about 50 g of solvent was transferred quantitatively in the dry box to the cell by pouring it into the dilution bulb this was the minimum amount required to fill the cell bulb. The cell was removed from the dry box, placed in the oil bath, and connected to the bridge. Time was allowed for the attainment of thermal equilibrium then at least three resistance measurements were made at five-min intervals, and the average value was calculated. The cell was removed from the bath and returned to the dry box. Dilute stock solution was quantitatively added to the cell by means of a weighing buret. The contents of the cell were carefully mixed, and the resistance of the solution was measured as before. The procedure just described was repeated several times with the dilute stock solution and then with the concentrated stock solution. About ten concentrations with a hundredfold range were obtained. A portion of the final solution in the cell (the most concentrated solution) was removed, and the infrared spectrum taken no absorption band indicative of traces of water was observed at 3600 cm-1. It was necessary to obtain the densities of... 

In a process for preparation of 2-methoxy-5-nitroaniline the anisidine salt was added to stirred sulfuric acid. An accidental deficiency of the latter prevented proper mixing and dissipation of the heat of solution, and local decomposition spread through the entire content of the 2000 1 vessel, attaining red heat. 

Glasser D, Hildebrandt D, Godorr S. The attainable region for segregated maximum mixed and other reactor models. Ind Eng Chem Res 1994 33 1136. 

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