Number of stages per meter

Figure 13.45. Number of stages per meter (reciprocal of HETP), pressure loss per meter and pressure loss per theoretical stage in a 500 mm dia column filled with metal pall rings. Other charts in the original show the effects of packing height and column diameter, as well as similar data for Raschig rings (Billet, 1979). (a) Methanol/ethanol at 760Torr and total reflux in a column 500 mm dia. (b) Ethylbenzene/styrene at 100 Torr and total reflux in a column 500 mm dia.

Assume an initial value for the number of stages per meter (NSTM). 

An alternative parameter popular in Europe is the NTSM (number of theoretical stages per meter) which is simply the reciprocal of the HETP. 

FIG. 14-60 Effect of structured packing surface areas, loads, and inclination angle on packing efficiency. Efficiency expressed as number of theoretical stages per meter, the reciprocal of HETP. Sulzer data, chlorobenzene-ethylbenzene, 100 mbar, at total reflux 250-mm-diameter test column. (Reprinted courtesy of Sulzer... 

The last element in analysis is the number of theoretical stages per meter, NTSM. Laboratory experiments indicate a value of 3 for Katapack-SP [11], with 3 to 6 for Multipack-II [9]. On the other hand, NTSM of two seems more appropriate from the industrial viewpoint. 

Fig.13 Theoretical stages per meter packings as a fraction of the Bodenstein number for near-critical extraction of monoglycerides from a mixture of mono-, di-, and triglycerides at 12 MPa and 313 K in the droplet regime.

Fig. 7.19 Comparison of the pressure drop and mass-transfer performance of 1 in. Raschig rings with catalytic bales a) pressure drop against F-Factor at constant maximum liquid load b) number of theoretical stages per meter against F-fac-tor. The liquid load is kept constant at a value of 0.05 m s. Calculations of Baur and Krishna [48]...

Figure 7. Vertical sections of temperature (0.2 °C intervals) and chlorophyll (1.0-mg/m intervals) and abundance of Stage 1 mackerel eggs (number per square meter) from UOR tows along two transects in the Celtic Sea in May 1981 (F.R.V. Cirolana). The inset shows the cruise track.

The packing material under consideration consists of 2.5 cm Pall rings. The estimated HETP is 45 cm and the packing factor, F= 170 m per cubic meter of packing (Vital et al., 1984 Eckert, 1975). The equivalent number of equilibrium stages, including the condenser and reboiler, is... 

CEC is a hybrid separation technique that combines capillary HPLC (50-pm capillary diameter) with capillary zone electrophoresis, and its main advantage is the enormous number of theoretical plates that can be achieved. This is a result of the uniform, plug-like flow that electro-endoosmosis generates and the fact that this allows the use of very small particles (3 pm diameter). The technology is at an early stage of development (as there are problems inherent in packing columns of such small particle size f9J), but has already resulted in efficiency values of up to 387,000 theoretical plates per meter (10). 

A number of technical and cost issues face polymer electrolyte fuel cells at the present stage of development (35, 38, 39, 40, 41). These concern the cell membrane, cathode performance, and cell heating limits. The membranes used in present cells are expensive, and available only in limited ranges of thickness and specific ionic conductivity. Lower-cost membranes that exhibit low resistivity are needed. This is particularly important for transportation applications characterized by high current density operation. Less expensive membranes promote lower-cost PEFCs, and thinner membranes with lower resistivities could contribute to power density improvement (41). It is estimated that the present cost of membranes could fall (by a factor of 5) if market demand increased significantly (to millions of square meters per year) (33). 

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