Separation nozzle process separative capacity

In some isotope separation processes it is impractical to operate a stage at a cut of for mechanical or hydraulic reasons, and in others the separative capacity of the stage is higher at a cut substantially different from In the Becker separation nozzle process described in Chap. 14, the separative capacity of a stage producing a heads stream at a given rate is substantially hi er at a cut of than at a cut of j. 

Figure 14.23 Separation factor and power consumption per unit separative capacity in nozzle process. 4 m/o UF in hydrogen, cut = 5.

Figure 14.28 Power per unit separative capacity for nozzle process with UFj-hydrogen mixtures expanded through critical pressure ratio. Cut = 3.

The heavy fraction containing 0.105 mole fraction UF would start to condense at a pressure of 3.8 bar at 313 K. Hence the pressure of the heavy stream must be below this value and the feed pressure, p, must be below (1.12X3.8) = 4.3 bar. This pressure is much hi er than the subatmospheric pressures reported for the nozzle process and would result in much lower volumetric flow rates in a UCOR plant than in a nozzle plant of the same separative capacity. 

A typical non-condensible blowdown drum and its associated equipment and headers are illustrated in Figure 1. A single blowdown drum may be used for more than one process unit, if economically attractive. However, when this is done, all units served by it must be shut down in order to take the drum out of service, unless cross connections are made to another system of adequate capacity. Normally all closed safety valve discharges are combined into one header entering the drum, although separate headers and inlet nozzles are acceptable if economically advantageous. The following releases are also normally routed into the safety valve header ... 

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