Columns reciprocating

Flo. 1. Correlation between the reciprocal of INH-plasma level and specific activity of liver N-acetyltransferase in ten rhesus monkeys with varying enzyme activity. White columns specific activity of N-acetyltransferase. Black columns reciprocal of INH level in plasma 135 min after intramuscular injection of 20 mg INH/kg body weight (After Goedde, H. W Schloot, W. and Valesky, A., Arzneim. Forsch.,... 

In this equation, represents the rate of energy dissipation per unit mass of fluid. In pulsed and reciprocating plate columns the dimensionless proportionahty constant K in equation 38 is on the order of 0.3. In stirred tanks, the proportionaUty constant has been reported as 0.024(1 + 2.5 h) in the holdup range 0 to 0.35 (67). The increase of drop si2e with holdup is attributed to the increasing tendency for coalescence between drops as the concentration of drops increases. A detailed survey of drop si2e correlations is given by the Hterature (65). 

The nonuniformity of drop dispersions can often be important in extraction. This nonuniformity can lead to axial variation of holdup in a column even though the flow rates and other conditions are held constant. For example, there is a tendency for the smallest drops to remain in a column longer than the larger ones, and thereby to accumulate and lead to a locali2ed increase in holdup. This phenomenon has been studied in reciprocating-plate columns (74). In the process of drop breakup, extremely small secondary drops are often formed (64). These drops, which may be only a few micrometers in diameter, can become entrained in the continuous phase when leaving the contactor. Entrainment can occur weU below the flooding point. 

Fig. 15. Mechanically agitated columns (a) Scheibel column (b) rotating-disk contactor (RDC) (c) asymmetric rotating-disk (ARD) contactor (d) Oldshue-Rushton multiple-mixer column (e) Kuhni column and (f) reciprocating-plate column.

Other types of RPC have been proposed but are not in industrial use as of this writing. These include a reciprocated wire-mesh packing (188), a reciprocating screen-plate (205), and the multistage vibrating disk column (MVE)C) developed in Japan (189,206,207). These types of RPC may be useful for gas—hquid contact as well as Hquid-Hquid contact. 

Fractional extraction has been used in many processes for the purification and isolation of antibiotics from antibiotic complexes or isomers. A 2-propanol—chloroform mixture and an aqueous disodium phosphate buffet solution are the solvents (243). A reciprocating-plate column is employed for the extraction process (154). 

Note that the absorption factor is the reciprocal of the expression given in Eq. (14-4) for packed columns. 

FIG. 15-49 Schematic arrangement of the 900-mm (36-in) reciprocating-plate column, (Coutiesy of Glitsch Process Systems Inc.)... 

TABLE 15-10 Summary of Minimum HETS Values and Volumetric Efficiencies for a Reciprocating-Plate Column ... 

Z9 = plate stack height in scaled-up column df = diameter of pilot column df9 = diameter of scaled up column SPM = reciprocating speed of pilot column SPMo = reciprocating speed of scaled-up column... 

The column was operated in the normal phase mode using mixtures of n-hexane and ethanol as the mobile phase. Equation (13) is validated by the curves relating the corrected retention volume to the reciprocal of the volume fraction of ethanol in Figure 19. It is seen that an excellent linear relationship is obtained between the corrected retention volume and the reciprocal of the volume fraction of ethanol. 

Figure 5, Graph of the Variance per Unit Length of the Column (H). against the Reciprocal of the Diffusivity...

The minimum recommended saturated suction temperature on single-stage reciprocating applications, column (J), is based on a compression ratio of about 9 to 1. The refrigerants 114, 11 (soon to be replaced by R-123), and 113 are not included due to the large cfm/ton. 

The minimum recommended saturated suction temperature on series multistage reciprocating-centrifugal applications, column (K), represents an approximate reasonable limit on suction temperature. The temperatures shown correspond to suction pressures below atmospheric. 

Refractive index detectors. These bulk property detectors are based on the change of refractive index of the eluant from the column with respect to pure mobile phase. Although they are widely used, the refractive index detectors suffer from several disadvantages — lack of high sensitivity, lack of suitability for gradient elution, and the need for strict temperature control ( + 0.001 °C) to operate at their highest sensitivity. A pulseless pump, or a reciprocating pump equipped with a pulse dampener, must also be employed. The effect of these limitations may to some extent be overcome by the use of differential systems in which the column eluant is compared with a reference flow of pure mobile phase. The two chief types of RI detector are as follows. 

Height equivalent to a theoretical plate (HETP) A measure of the efficiency of a column usually expressed in millimeters. HETP — LIN, where L is the length of a column and N is the number of theoretical plates. The reciprocal of HETP is also used to describe efficiency and is often expressed by the terms plates per meter. 

Here we must regard and as forming one-column matrices. Note that the square matrices (.gk h,y and are mutually reciprocal, and that their product is the identity matrix ... 

The left-hand side of equation 10.157 is the rate of change of concentration with height for unit driving force, and is therefore a measure of the efficiency of the column and, in this way. a high value of (hD aCT)/G is associated with a high efficiency. The reciprocal of this quantity is G /(ho aCT) which has linear dimensions and is known as the height of the transfer unit Ht (HTU). 

Transform) the content of a given column ( vector) can be mathematically modified in various ways, the result being deposited in the (N + 1) column. The available operators are addition of and multiplication with a constant, square and square root, reciprocal, log(w), Infn), 10 , exp(M), clipping of digits, adding Gaussian noise, normalization of the column, and transposition of the table. More complicated data work-up is best done in a spreadsheet and then imported. 

For stirred tanks with hold-ups up to 0.35 the constant K = 0.024 ( 1For reciprocating-plate extraction columns K = 0.I8, while for pulsed perforated-plate columns AT = 0.18 Kirk-Othmer Encyclopedia of Technology, 1978-1984). 

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