Splitting/separation unit

When a mixture in a reactor effluent contains components with a wide range of volatilities, then a partial condensation from the vapor phase or a partial vaporization from the liquid phase followed by a simple phase split often can produce a good separation. If the vapor from such a phase split is difficult to condense, then further separation needs to be carried out in a vapor separation unit such as a membrane. 

Separation of toluene from the other components can be by solvent extraction or extractive distillation, just as described in the benzene chapter. The boiling points of benzene and toluene are far enough apart that the feed to separation unit of choice can be split (fractionated) rather easily into benzene concentrate and a toluene concentrate. Alternatively, the separation unit can be thought of as aromatics recovery unit. Then an aromatics concentrate stream is fed to the solvent extraction unit, and, the aromatics outturn can be split into benzene and toluene streams by fractionation. Both schemes are popular. 

The product from this reactor is cooled from its output temperature to a temperature Tc and is then introduced into a separation unit in which the unreacted A is separated from the product B. The feed of the separation unit is split into two equal parts top product and bottom product. Here the bottom product from the separation unit contains 95% of the unreacted A in the effluent of the reactor and... 

The gas feed stream is split, recycle CO2 is added to each stream and the combined streams are fed to each of the two gasification trains. Oxygen from the Air Separation Unit (ASU) is preheated by steam, split and fed to the two gasification trains. Partial oxidation and reforming reactions take place in the Gasifiers. 

In this configuration, the hydrogen and the methane from the demethanizer column are spUt into their component streams. The hydrogen is for use in various downstream processes and the methane is used as a fuel-gas stream. Bottoms from the de-ethaniser are further split into C3 and C4. stream. The C3 is treated similarly to the C2 to produce polymer grade propylene. After removing the C4 fraction, which is passed to downstream separation units, the heavy components form pyrolysis-gasoUne. The latter may be further separated to produce benzene, toluene and xylene. 

By means of sodium dodecyl sulphate polyacrylamide separation it is possible to split the ChE in the snail brain down into 4 separate units (Fig. 15). These have molecular weights of 37,800,46,000,70,000 and 92,000, giving an aggregate total molecular weight for the whole enzyme of approximately 200,000. Molecular weight estimations... 

The theory of trajectory bundles described in Chapters 5 and 6 ensures the possi-bihty of identification of all feasible splits of multicomponent azeotropic mixtures. The software for synthesis of separation units for multicomponent azeotropic mixtures should include, besides the module of identification of feasible splits, a module of preliminary selection of these splits (i.e., choice of the most interesting splits, a module of determination of necessary recycle flow rates, a module of choice of entrainers, and also modules entering into the system of synthesis for zeotropic mixtures). 

Distillation Theory and Its Application to Optimal Design of Separation Units presents a clear, multidimensional, geometric representation of distillation theory that is vahd for all types of distillation columns for all splits, column types, and mixtures. This representation answers such fundamental questions as ... 

Food service areas are normally based upon the free flow principle where numbers in excess of 200 are served. The system splits the normal straight line counter into a number of separate units, each serving a different dish, to divide demand and minimize potential lines. 

To avoid the constraint of having all parts in one package, the evaporator set may be split from the condenser, the compressor going with either (see Figure 13.4). The unit will be designed as a complete system but the two parts are located separately and connected on site. On some small units, flexible refrigerant piping may be provided. 

The usual split package air-conditioner comprises one condensing unit connected by pipes to one evaporator unit (Figure 13.4). Twin condensing units are made to save on outdoor casings and reduce the number of pieces on a roof or wall. Such twins will be connected in the usual way to two separate indoor units. 

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