General Design Considerations

Before proceeding any further with the development of a proeess design and its associated economies, it will be desirable to eonsider an overall view of the various functions involved in a complete plant design. Particular emphasis in this discussion will be placed on important health, safety, loss prevention, and environmental eonsiderations. Other items that will be noted briefly inelude plant loeation, plant layout, plant operation and eontrol, utilities, struetural design, storage, materials handling, patents, and legal restrietions. 

The potential health hazard to an individual by a material used in any ehemieal proeess is a function of the inherent toxicity of the material and the frequeney and duration of exposure. It is common practice to distinguish between the short-term and long-term effects of a materiaf. A highly toxic material that eauses immediate injuiy is classified as a safety hazard while a material whose 

With the uncertainties involved in the designation of occupational exposure standards and the variability of the occupational environment, it would be unreasonable to interpret occupational limits as rigidly as one might interpret an engineering standard or specification. Fortunately, there has been a recent effort to make these rather subjective judgements more scientific and uniform by the application of statistics. The latter makes it possible to develop decisionmaking strategies that can prescribe how many samples to take, where and when to take them in the workplace, and how to interpret the results. 

The main objective of health-hazard control is to limit the chemical dosage of a chemical by minimizing or preventing exposure. It is not practical to measure or control the chemical dosage directly rather, exposure is measured and limits are set for the control of such exposure. 

The most common and most significant source of workplace exposure to chemicals and also the most difficult to control is inhalation. Workers become exposed when the contaminant is picked up by the air they breathe. Thus, an 

In a linear equilibrium system adsorption and desorption are symmetrically equivalent processes so the restriction to equal times for the adsorption and desorption cycles in a two-bed system does not limit the efficiency with which the adsorbent may be used. However, most cyclic adsorption separation processes operate under conditions such that the isotherm for the. more strongly adsorbed species is of favorable (type I) form. Under these conditions 

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In this chapter, we first cite examples of catalyzed two-phase reactions. We then consider types of reactors from the point of view of modes of operation and general design considerations. Following introduction of general aspects of reactor models, we focus on the simplest of these for pseudohomogeneous and heterogeneous reactor models, and conclude with a brief discussion of one-dimensional and two-dimensional models. 

General design considerations for mechanically agitated gas-liquid and gas-liquid-solid mechanically agitated reactors described earlier in Sections II and III are applicable here. In this section, however, we evaluate additional design considerations that are specific to bioreactors. Novel reactors to overcome specific needs of biological processes are also evaluated in this section. The characteristics of the bioreactors and other chemical/ petrochemical gas-liquid and slurry reactors are compared in Table XX. 

The equipment for curium-americium oxide production (illustrated schematically in Fig. 2) is located on a rack within a master-slave manipulator-equipped hot cell in the TRU cell bank. The feed adjustment and raffinate collection vessels are located in a tank pit in another part of the cell bank. General design considerations and operating philosophies for chemical process operations at TRU have been described previously (4) Only equipment items that are unique to the curium-americium oxide production are discussed below. 

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