Continuous column

In a normally pressured reservoir, the pressure is transmitted through a continuous column of water from the surface down to the reservoir. At the datum level at surface the pressure is one atmosphere. The datum level for an offshore location is the mean sea level (msl), and for a onshore location, the ground water level. 

The dominance of distiHation-based methods for the separation of Hquid mixtures makes a number of points about RCM and DRD significant. Residue curves trace the Hquid-phase composition of a simple single-stage batch stiHpot as a function of time. Residue curves also approximate the Hquid composition profiles in continuous staged or packed distillation columns operating at infinite reflux and reboil ratios, and are also indicative of many aspects of the behavior of continuous columns operating at practical reflux ratios (12). 

For stable foam drilling operations, much less volumetric rate of air flow is needed (i.e., usually less than 500 actual cfm). Also, the compressor should be capable of variable volumetric rate of flow and variable output pressure. The back pressure must be continuously adjusted to maintain a continuous column of stable foam in the annulus. This continuous adjustment of back pressure requires, therefore, continuous adjustment of input volumetric rate of airflow and output pressure (also, water and surfactant must be adjusted). 

Stable Foam. When a well is drilled with stable foam as the drilling fluid, there is a back pressure valve at the blooey line. The back pressure valve allows for a continuous column of foam in the annulus while drilling operations are under way. Thus, while drilling, this foam column can have significant bottom-hole pressure. This bottomhole pressure can be sufficient to counter formation pore pressure and thus control potential production fluid flow into the well annulus. 

Figure El2.2a illustrates a typical steady-state continuous column. The model and the objective function are formulated as follows.

The pressure at level a in the manometer is (Pi + pAzmg) in arm 1 and (P2 + pmkzmg) in arm 2 where p and pm are the densities of the flowing fluid and immiscible liquid respectively. These two pressures are equal since the two arms of the manometer are connected by a continuous column of stationary liquid. Therefore... 

Fig. 2. Schematic diagram of the continuous column-leaching test experiment...

Fields, S. M. (1996). Silica xerogel as continuous column support for high performance liquid chromatography. Anal. Chem. 68, 2709-2712. 

Ethyl acetate is a product of yeasts and a normal component of wine. Its level can be increased by Acetobacter contamination, although most wines showing excess volatile (acetic) acid do not necessarily contain excess ethyl ester initially. It is quite possible to obtain brandy of normal composition and quality by continuous distillation of newly fermented wine containing excess acetic acid, e.g., 0.1%. On the other hand, ethyl acetate can be formed in continuous columns, particularly if the distillation conditions provide for a relatively high ethanol concentration on the feed tray or immediately below. Since acetic acid is weakly yolatile in all mixtures of ethanol and water, it does not appreciably distill upward. Therefore there is no opportunity for acetic acid to combine wtih ethanol in tray liquids normally of high ethanol concentration. 

Ethyl acetate is the major low-boiling impurity of heads fractions from continuous columns if bisulfites are absent in the distilling material. A heads fraction from a typical brandy column usually contains less than 1% of these volatile impurities, although the concentrated heads from an aldehyde-concentrating column may contain as much as 10-15% aldehydes. In either case, ethyl alcohol is the major component of the heads cut, and its recovery in usable form has been a troublesome processing problem. 

Guymon (21) reported the composition of tray liquids for brandy distilled in continuous column, respectively, at 130°, 170°, and 181° proof. The maximum level of fusel oil occurred on the tray nearest in proof to about 130°. This is the second tray below the product tray for the customary 170° proof of distillation of the product. 

The number of continuous columns required is one less than the number of components or fractions to be separated. Operating conditions of a typical batch distillation making five cuts on an 8-hr cycle are in Figure 13.11. 

As an alternative to multistage batch crystallization processes with their attendant problems of material handling and losses, several types of continuous column crystallizers have been developed, in which the product crystals are washed with their own melts in countercurrent flow. Those illustrated in Figures 16.14-16.17 will be described. Capacities of column purifiers as high as 500gal/(hr) (sqft) have been reported but they can be less than one-tenth as much. Lengths of laboratory size purifiers usually are less than three feet. 

Because of the long, narrow configuration, the equipment appears to function in countercurrent mode. Other data of experiments with gas permeators as continuous columns appear in Figures 19.6(b) and (c) the original paper has data on other binary and some complex mixtures. 

Figure 19.6. Gas permeation equipment and performance, (a) Cutaway of a Monsanto Prism hollow fiber module for gas separation by permeation, (b) Flowsketch of a continuous column membrane gas separator, (c) Composition profiles of a mixture of C02 and Oz in a column 5 m long operated at total reflux [Thorman and Hwang in ( Turbak, Ed.), Synthetic Membranes II, American Chemical Society, Washington DC, 1981, pp. 259-279],...

Some types of work, notably seismic prospecting, require a means of joining dynamite cartridges together to make a continuous column for loading into boreholes. The coupling devices are known as cartridge couplers and the type manufd by the DuPont Co is called Fast-Coupler (Ref 3,p 56)... 

For a multicomponent liquid mixture with nc number of components, usually (nc-l) number of continuous columns will be necessary to separate all the components from the mixture. For a mixture with only 4 components and 3 distillation columns there can be 5 alternative sequences of operations to separate all the components (Figure 1.4). For a mixture with only 5 components, 4 distillation columns can be sequenced in 14 different ways. The number of alternative operations grows exponentially with the number of components in the mixture. These alternative operations do not take into account the production of off-specification materials or provision for side streams (this would further increase dramatically the number of columns and or operational sequences). 

Attarwala and Abrams (1974) considered the batch separation task operating in a single continuous column sequentially. The essential features of this type of column (Figure 2.4) are ... 

Figure 2.4. Batch Distillation Using Continuous Column...

Attarwala and Abrams (1974) and Mujtaba (1997) used the above model for batch distillation task using a continuous column (see section 2.2.4). 

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