Separation work

Separators working at unsteady conditions produce intermediates with compositions which do not allow them to be recycled. Alternatively, if the intermediate can be recycled, a nonoptimal recycle might produce (additional) unwanted byproducts in the reactor. 

Separators working at unsteady conditions produce products which do not meet the required sales specification. 

A separate works have been carried out in order to develop AUGUR 4 2 procedure for expert ISI of primary circuit piping welds. 

When this is combined with the definition of minimum separation work, an approximation for distillation efficiency for an ideal binary can be obtained ... 

It can be assumed that P,Jp, and for the cascade have been specified, and that the cost of feed and the cost per unit of separative work, the product of separative capacity and time, are known. The basic assumption is that the unit cost of separative work remains essentially constant for small changes ia the total plant size. The cost of the operation can then be expressed as the sum of the feed cost and cost of separative work ... 

The second term in brackets in equation 36 is the separative work produced per unit time, called the separative capacity of the cascade. It is a function only of the rates and concentrations of the separation task being performed, and its value can be calculated quite easily from a value balance about the cascade. The separative capacity, sometimes called the separative power, is a defined mathematical quantity. Its usefulness arises from the fact that it is directly proportional to the total flow in the cascade and, therefore, directly proportional to the amount of equipment required for the cascade, the power requirement of the cascade, and the cost of the cascade. The separative capacity can be calculated using either molar flows and mol fractions or mass flows and weight fractions. The common unit for measuring separative work is the separative work unit (SWU) which is obtained when the flows are measured in kilograms of uranium and the concentrations in weight fractions. 

Plant Operation and Costs. The operation and economics of the three United States gaseous diffusion plants miming ia 1972 is discussed ia References 29 and 30. These plants were operated as a single gaseous diffusion complex such that iaterplant shipments occurred so as to optimize the overall system. Independent operation of the plants would have resulted ia about a 1% loss ia separative work. 

In 1985, owiag to the declining demand by the nuclear power industry for enriched uranium, the Oak Ridge gaseous diffusion plant was taken out of operation and, subsequently, was shut down. The U.S. gaseous diffusion plants at Portsmouth, Ohio and Paducah, Kentucky remain ia operation and have a separative capacity of 19.6 million SWU (separative work unit) per year which as of this writing is not fully utilized. 

The cost of enriched material from a gaseous diffusion plant depends both on the cost of separative work and of feed material. It can be seen from equation 15 that if the optimum tails concentration from a gaseous diffusion plant is 0.25%, the ratio of the cost of a kg of normal uranium to the cost of a kg of separative work equal to 0.80 is impfled. Because the cost of separative work in new gaseous diffusion plants is expected to be about 100/SWU, equation 16 gives the cost per kg of uranium containing 4% as about 1,240. 

Maximum Separative Capaeity and the Separative Effieieney. The separative efficiency of a gas centrifuge used for isotope separation is best defined in terms of separative work. Thus, the separative efficiency E is defined by... 

Records of Tests. Either of two methods may be used for recording routine test results. In the first, measurements and calculations are recorded in the individual worker s notebook and then transferred to the main record book. In the second method, a separate work book is kept for each routinely performed test. Whoever does the testing enters the results in the book and initials it. The pages should be lined with columns to suit each test s requirements. 

The silicone membrane separator works on the principle of differential eability for the transmission of organic solutes compared to carrier gas molecules (38). The amount of sample... 

Figure 223. Types of chemical heat pump (a) reaction phase change batch type, (b) reaction reaction batch type, (c) reaction separation work continuous type...

Ion chromatography has become available and is used for sugar analysis. In this system a high-performance anion exchange column is used at high pH. This separation works because neutral saccharides behave as weak acids. Table 1 shows some pKa values. 

Separate roles. Make separate context models for the system as used by different groups of collaborators. In general the separation works best by considering the abstract collaborations, rather than individual collaborators. 

The evaporation of citrus juices at temperatures up to 328 K, or of pharmaceutical products at even lower temperatures, has led to the development of an evaporator incorporating a heat-pump cycle using a separate working fluid. The use of the heat pump cycle, with ammonia as the working fluid is shown in Figure 14.13. In this arrangement, ammonia... 

Further Discussion of Gaseous Diffusion Separative Work... 

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