Separation nozzle process pressures

In the UCOR process, unlike the separation nozzle process, the depleted stream is recompressed through a smaller pressure ratio (1.12) than the enriched stream (1.5). Hence, to evaluate the energy used in compression it is necessary to know the hydrogen cut 8, the fraction of hydrogen fed that leaves in the enriched stream, and the composition of the enriched stream represented by the mole fraction /i of UF in it. A development analogous to the one that led to Eq. (14.271) for the Up6 cut results in Eq. (14.296) for the hydrogen cut ... 

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. 

Cavities of different sizes and geometries can be incorporated into one mould, sometimes referred to as gang moulds or family moulds. This is possible because the moulding pressure in the cavities is produced by the gas pressure of the blowing agent within the melt and each i cavity is therefore effectively an independent entity. Separate nozzles, each with their own flow control valves, are used for each cavity. Alternatively, several moulds may be used instead of a family mould. Family moulds have been unsatisfactory for the component injection moulding process because of the difficulty of ensuring even flow to all cavities. However, recently... 

The processes use an inert gas that is usually nitrogen with pressures up to 20 to 30 MPa (2,900 to 4,400 psi). Within the mold cavity the gas in the melt forms channels. Gas pressure is maintained through the cooling cycle. In effect the gas packs the plastic against the cavity wall. Gas can be injected through the center of the IMM nozzle as the melt travels to the cavity or it can be injected separately into the mold cavity. 

In all three processes the reaction is performed in an empty pressure vessel lined with alumina. The reactants (oil and oxygen, along with a small amount of steam) are introduced through a nozzle at the top of the generator vessel. The nozzle consists of concentric pipes so that the reactants are fed separately and react only after mixing at the burner tip or in the space below. The temperature in the generator is between 1200... 

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