Pulsed columns

The pulsed-plate column is typically fitted with hori2ontal perforated plates or sieve plates which occupy the entire cross section of the column. The total free area of the plate is about 20—25%. The columns ate generally operated at frequencies of 1.5 to 4 H2 with ampHtudes 0.63 to 2.5 cm. The energy dissipated by the pulsations increases both the turbulence and the interfacial areas and greatly improves the mass-transfer efficiency compared to that of an unpulsed column. Pulsed-plate columns in diameters of up to 1.0 m or mote ate widely used in the nuclear industry (139,140). 

Equipment type Pulsed plate column Pulsed plate column... 

Pulse-packed columns Pulse sieve-plate columns... 

Several reactors are presently used for studying gas-solid reactions. These reactors should, in principle, be useful for studying gas-liquid-solid catalytic reactions. The reactors are the ball-mill reactor (Fig. 5-10), a fluidized-bed reactor with an agitator (Fig. 5-11), a stirred reactor with catalyst impregnated on the reactor walls or placed in an annular basket (Fig. 5-12), a reactor with catalyst placed in a stationary cylindrical basket (Fig. 5-13), an internal recirculation reactor (Fig. 5-14), microreactors (Fig. 5-16), a single-pellet pulse reactor (Fig. 5-17), and a chromatographic-column pulse reactor (Fig. 5-18). The key features of these reactors are listed in Tables 5-3 through 5-9. The pertinent references for these reactors are listed at the end of the chapter. 

Table 5-10 Key features of a chromatographic-column pulse reactor...

Mechanical reciprocation Karr Column Pulsed Packed Column Pulsed Perforated Plate Column... 

The procedure for the scale-up of an expanded-bed-adsorption process is relatively straightforward and the principles are similar to those used for a packed-bed process. It is important that the length of the laboratory column be equal to the pilot-plant column. If the pilot-plant equipment is not specifically designed for expanded-bed-adsorption procedures, it should be modified as described in the previous section on laboratory equipment. To verify that the expanded-bed flow patterns are similar for the lab and pilot-plant columns, pulse tests using NaCl solution should be carried out. The adsorbent used, whole-broth-solvent ratio, bed height, and linear velocity, should not be changed on scale-up. The volumetric flow should be increased m proportion to the mcrease in the cross-sectional area of the two columns. Thus, the superficial velocity will be maintained and the adsorption and the fluidization properties will be constant. 

Add 300 pi of Purification Buffer to the column, pulse the centrifuge for 10 s and discard the flow-through. Repeat this wash twice. Place the bottom caps on the columns. 

Extraction apparatus with continuous phase contact Spray column Packed column Pulsed packed column Rotating disc contactor, Oldshue-Rushton column, Graesser-Contactor, Kuhni column Podbiehiiak- Extractor, Luigi-Westfalia- Extractor, De Laval-Extractor... 

Stagewise contact with controlled coalescence redispersion cycles Tray column Pulsed sieve column. Pulsed Mixer-Settler-cascade, Extraction tower with controlled cycle Scheibel column, ARD-Extractor, Leisibach column, Mixer-Settler cascade ... 

Yun et al. [502] separated 11 cephalosporin antibiotics (cefsulodin, cefadroxil, cefuroxime, cefoxitin, cefotaxime, cefazolin, cefaclor, cephalexin, cephradine, cephaloglycin, cephalothin) on a Cig column (pulsed amperometric detector). A complex 50-min 87/11/287/2/11 water (lOmM acetate buffer at pH 4.7)/ methanol/acetonitrile gradient was used. Detection limits were reported as 30ppb. 

Thirteen free and conjugated bile acids (e.g., cholic, taurocholic, deoxycholic, lithocholic, taurolithocholic, glycodeoxycholic acids) were baseline resolved on a 35 C PLRP-S column (pulsed amperometric detector at +0.03V vs. Ag/AgCl). A 55-min 20/60/30-> 29/51/20 acetonitrile/water/water (0.5 M NaOH) gradient was used [1066]. The presence of 0.1 M hydroxide is essential for the amperometric detection of the hydroxyl fimctional group on the bile acids. However, the authors... 

The principle of matrix addressing is shown in Fig. 4.18 [94]. The rows of the matrix are subsequently addressed in equal time subintervals (T/3) by pulses of the amplitude C/s- In each time subinterval all the columns of the matrix display are addressed simultaneously with pulses of the amplitude C/d. The sign of the column pulse depends on whether an element of the matrix display (pixel) should be in the off or on state. Sometimes on and off states of the pixel are called selected and nonselected states. Figure 4.18 demonstrates that the effective (root mean square) voltages on... 

Liquid crystal cell 4 Positive column pulse generator... 

While solvent extraction is often done on a small scale by synthetic lab chemists using a separatory funnel or Craig apparatus, it is normally done on the industrial scale using machines that bring the two liquid phases into contact with each other. Such machines include centrifugal contactors, thin layer extractors, spray columns, pulsed columns, and mixer-settlers. 

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