Nozzle process

Jamerson SC, HG Fisher. Using constant slip ratios to model non-flashing (frozen) two-phase flow through nozzles. Process Safety Prog 18(2) 89-98, 1999. 

L-D [Linz, Austria and either Dusenverfahren (nozzle process), or Donawitz, the other Austrian town where it was developed] A basic steelmaking process in which oxygen is used instead of air to remove most of the carbon from the molten pig iron. Developed in Austria by the Vereinigte Osterreichisch Eisen und Stahlwerke of Linz, and Osterreichisch Alpine of Donawitz, in the 1930s and 40s commercialized in 1952, and now widely adopted. The furnace is essentially a Bessemer converter, modified with a water-cooled oxygen injector. See also Bessemer. 

With c sensitive to the combustion process and cF sensitive to the nozzle process, a defective specific impulse may be more readily located by not only measuring F and w, but pc and At as well. Since the chamber pressure is always measured and the throat area known, but generally checked before and after operation, information to calculate Igp, cF and c is always on hand. 

Certain crude approaches are available to predict overall results, that is, nonequilibrium compositions. More refined techniques are available for the analysis of simplified models. Solution of the reaction kinetics of homogeneous gas phase combustion is possible through numerical solution of the rate equations. With the exception of the role of an overall highly exothermic reaction, the procedures are similar to those described in the preceding section on nozzle processes. The solution of the droplet burning problem including the role of chemical reaction rates, while not particularly tractable, is feasible. 

Enrichment of the Sy-isotope from the 0.711% in natural uranium to ca. 4% can proceed by gas diffusion, with a gas centrifuge and with separation nozzles. The separation nozzle process is no longer important. Pure uranium(VI) fluoride is utilized. 

On the process side, techniques like the fluid bed method, extrusion, coacervation, the submerged nozzle process and molecular inclusion have gained importance within the last 10-15 years [1-3, 7]. 

This principle is shown together with the submerged nozzle process in Fig. 2.60. 

Gelatin capsules with enclosed flavour droplets can be produced by either coacerva-tion or the submerged nozzle process. 

As stated above, the development of the LIGA process began at the Research Center in Karlsruhe (FZK), Germany, in the 70s as a rather inexpensive method of producing very small slotted nozzles of any lateral shape for uranium-isotope separation by the nozzle process. Its usage is now wide spread globally as well as to a much... 

Separation nozzle process Process demonstrated on large pilot-plant scale at Karlsruhe, Germany semiconunerdal plant being built in Brazil... 

Figure 12.5 Cross section of slit used in Becker separation nozzle process.

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. 

Thus, in a process like the Becker nozzle process, in which it is desirable to design stages for a cut of 5, the cascade mi t advantageously be of the two-up, one-down type shown in Fig. 

For close isotope separation processes that depend on differences in molecular weight, such as gaseous diffusion or the Becker nozzle process. 

Table 14.18 Comparison of operating conditions and petfonnance indices of two foims of nozzle process and gaseous diffuaon process...

Figure 14.22 Comparison of hipest reported separation factors in nozzle process with calculated values for equilibrium in centrifugal field.

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

Figure 14.24 Tubular separation element for nozzle process. (Courtesy of Dr. E. W. Becker.)...

Hence, in the nozzle process at high speed, the separation factor at cut B is IIEmEb times as great as in gaseous diffusion at cut 1 —6. 

The temperature T and peripheral speed wa = u occurring in the definition of A, Eq. (14.270), are for the mixture of UFe and hydrogen after expansion to speed v. The nozzle process ordinarily is operated at a known constant temperature T before expansion. T, T, and V are related by the enthalpy balance... 

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

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 ... 

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. 

The calculated separation factor of 1.0272 is in the range 1.025 to 1.03 dted by Roux and Grant and is higher than optimum in the nozzle process. 

The specific power of 1.80 MWh/kg SWU, with no allowance for process inefficiencies, is equivdent to 0.205 kW/(kg SWU/year). This may be compared with 0.168 for gaseous diffusion (Table 14.9), and 0.31 for the nozzle process (Fig. 14.23). The higher value for the nozzle process may be due to its expanding the heavy stream through the full pressure ratio. 

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