Multistage Absorption

When it is desired to compute, with rigorous methods, actual rather than equilibrium stages, Eqs. (13-69) and (13-94) can be modified to include the Murphree vapor-phase efficiency T ij, defined by Eq. (13-29). This is particularly desirable for multistage operations involving feeds containing components of a wide range ol volatility and/or concentration, in which only a rectification (absorption) or stripping action is provided and all components are not sharply separated. In those cases, the use of a different Murphree efficiency for each component and each tray may be necessary to compute recovery accurately. 

It is important to note that quite often the actual compression ratios for the individual cylinders of a multistage machine will not be balanced exacdy. This condition arises as a result of the limiting horsepower absorption for certain cylinder sizes and designs of the manufacturer. In final selection these will be adjusted to give compression ratios to use standard designs as much as possible. 

Dynantics of Heat Exchangers, Simple Batch Extraction, Multi-Solute Batch Extraction, Multistage Countercurrent Ctiscade, Extraction Cascade with Backmixing, Countercurrent Extraction Cascade with Reaction, Absorption with Chemical Reaction, Membrane Transfer Processes... 

This chapter covers the design of separating columns. Though the emphasis is on distillation processes, the basic construction features, and many of the design methods, also apply to other multistage processes such as stripping, absorption and extraction. 

Smith and Brinkley developed a method for determining the distribution of components in multicomponent separation processes. Their method is based on the solution of the finite-difference equations that can be written for multistage separation processes, and can be used for extraction and absorption processes, as well as distillation. Only the equations for distillation will be given here. The derivation of the equations is given by Smith and Brinkley (1960) and Smith (1963). For any component i (suffix i omitted in the equation for clarity)... 

The addition of a filler changes the kinetics of the water absorption by an epoxy binder, water absorption becoming a multistage process (Fig. 12). Crank and Park150) have given the equation for the kinetics of water sorption by a thin plate, as well as a solution of the Fickian diffusion differential Equation as ... 

The data in Fig. 13 show that the glass transition temperatures of all materials is reduced by the absorption of water. This seems to be due to the plasticizing effect of the water on the binder. There is a marked difference between the elastic states of the dressed and undressed foams, the latter becoming much more plastic after immersion in water. Increased plasticity is due to the loss of adhesion between the binder and the filler, indicating that water absorption by syntactic foams is multistaged. 

Many chemical and biological systems include multistage processes rather than only continuous contact ones. The most common multistage systems are absorption and distillation columns. Most of these systems involve more than one phase and they therefore fall under the category of heterogeneous multistage systems. Multistage systems can be cocurrent or countercurrent. 

Absorption is another gas-liquid process with two phases. Packed bed absorbers have three phases when also taking the solid packing of the column into consideration. Both continuous, i.e., packed bed, and multistage absorption are common in the chemical and biological industry. 

Many chemical and biological processes are multistage. Multistage processes include absorption towers, distillation columns, and batteries of continuous stirred tank reactors (CSTRs). These processes may be either cocurrent or countercurrent. The steady state of a multistage process is usually described by a set of linear equations that can be treated via matrices. On the other hand, the unsteady-state dynamic behavior of a multistage process is usually described by a set of ordinary differential equations that gives rise to a matrix differential equation. 

Multistage Absorption with a Nonlinear Equilibrium Relation... 

In this chapter we have presented multistage systems with special emphasis on absorption processes. We have studied multitray countercurrent absorption towers with equilibrium trays for both cases when the equilibrium relation is linear and when it is nonlinear. This study was accompanied by MATLAB codes that can solve either of the cases numerically. We have also introduced cases where the trays are not efficient enough to be treated as equilibrium stages. Using the rate of mass transfer RMT in this case, we have shown how the equilibrium case is the limit of the nonequilibrium cases when the rate of mass transfer becomes high. Both the linear and the nonlinear equilibrium relation were used to investigate the nonequi-librium case. We have developed MATLAB programs for the nonequilibrium cases as well. 

Choose a multistage absorption tower problem from industry. Collect all the necessary data, develop the model and the MATLAB code to simulate the industrial situation. Show how you can improve the performance of the chosen industrial unit. 

Another multistage method included in the program is the absorption and stripping factor method of Edmister (25). ASFPH, as it is called, can simulate simple and reboiled absorbers and also fractionators. The method used does not have very good convergence characteristics however, it is of value in studying plant performance data. 

Abstract. The synthesis, isolation and multistage chromatographic separation of the Y2 C84, Ce2 C78 n M C82 (M = Y, La, Ce, Gd) was carried out. All these newly synthesized metallofullerenes are characterized by S8-MALDI mass spectrometry and UV-vis-NIR absorption spectroscopy. 

It may be noted that the cascade arrangement of Figure 19.7, if suitably disentangled, will correspond to a multistage operation as encountered in absorption, stripping, and distillation practices. 

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