Dispersion operating line

The NTU values that characterise the concentration profile can be graphically determined if the operation line is parallel to the equilibrium curve in the loading diagram. In this case NTUp, = NTUg and reflects the theoretical stage number n,. A deviation of the ideal plug flow in the continuous and dispersed phase occurs for the following reasons ... 

In recent years the in-line static mixer has been adopted for a large number of blending and dispersing operations. Many in-line mixers are now commercially available. The geometrical details of these devices differ greatly but the principles of operation are basically the same in each case. 

For mixing operations which require the continuous production of finely dispersed solids, emulsions, stable foams, etc., the in-line dynamic mixer in one of its several forms could be used. These usually consist of a rotor which spins at high speed inside a casing and the feed materials are pumped continuously to the unit. Inside the casing the fluid is subjected to extremely high shear forces which are required for the dispersing operation, see Figure 7.10. 

Figure 6.4.8. (a) Mixer - a well-mixed vessel with one phase dispersed in the other, (b) Settler-the two phases have settled into two separate layers, (c) Equilibrium diagram, operating line and stage efficiencies in solvent extraction, (d) Well-mixed continuous mixer-settler. 

To develop a better understanding of how the stream compositions change with respect to each other along the countercurrent device length in the absence of dispersion and axial diffusion, equations (8.1.5) or (8.1.8) are frequently used. However, instead of a differential equation, algebraic equations relating Cu to Cj2 or x,i to x,-2 are developed. The lines represented by such equations are usually called operating lines sometimes the relationship is linear. 

Figure 8.1.16. Countercurrent gas absorption/stripping column with axial dispersion/diffitsion. (a) Operating lines and equilibrium curve, (b) Concentration profiles of gas and liquid phases along the tower length for gas absorption/stripping with (solid lines) or without...

It was claimed that the maximum continuous operating temperature in most chemical environments was 120°C and even 140-150°C in some instances. The major chemical applications were in the form of pipe and tank linings and injection moulded valve and pump parts. Coatings could be applied to metals by means of fluidised bed, water suspension and organic dispersion techniques. 

There are generally three types of peaks pure 2D absorption peaks, pure negative 2D dispersion peaks, and phase-twisted absorption-dispersion peaks. Since the prime purpose of apodization is to enhance resolution and optimize sensitivity, it is necessary to know the peak shape on which apodization is planned. For example, absorption-mode lines, which display protruding ridges from top to bottom, can be dealt with by applying Lorentz-Gauss window functions, while phase-twisted absorption-dispersion peaks will need some special apodization operations, such as muliplication by sine-bell or phase-shifted sine-bell functions. 

The photocatalytic decomposition of water was carried out in a closed gas circulation system connected to a high-vacuum line. About 200 mg of a powdered catalyst was dispersed in pure distilled water and irradiated through a water filter with an Xe lamp operated at 400 W. Hydrogen and oxygen evolved in the gas phase were analyzed by a gas chromatograph which was directly connected to the reaction system. 

In the formulation of the boundary conditions, it is presumed that there is no dispersion in the feed line and that the entering fluid is uniform in temperature and composition. In addition to the above boundary conditions, it is also necessary to formulate appropriate equations to express the energy transfer constraints imposed on the system (e.g., adiabatic, isothermal, or nonisothermal-nonadiabatic operation). For the one-dimensional models, boundary conditions 12.7.34 and 12.7.35 hold for all R, and not just at R = 0. 

This non-destructive technique is a very suitable tool for rapid in-line analysis of inorganic additives in food products (Price and Major, 1990 Anon, 1995). It can be readily used by non-skilled operators, and dry materials can be pressed into a pellet or simply poured into a sample cup. The principles of this technique related to food analysis are described by Pomeranz and Meloan (1994). A useful Internet site is http //www.xraysite.com, which includes information about different XRF instruments from various companies. Wavelength dispersive X-ray fluorescence (WD-XRF) or bench-top energy dispersive (ED-XRF) instruments are available. XRF is a comparative technique, thus a calibration curve needs to be established using food products of the same type as those to be... 

---