Plant Design Aspects

In particular, special problems caused by specific site characteristics should be described and discussed. Similarly, possible plant design aspects should be described which have not yet been satisfactorily solved, together with the possible research and development programmes aimed at the identification of a satisfactory solution. 

In addition to utiHty patents, some countries pubHsh patent documents under different or less stringent standards for patentabiHty and with shorter patent terms. For example, plant patents cover asexually reproduced plants. Design patents cover the decorative aspects of a product. UtiHty models and petty patents cover products with differences from the prior art that need not meet the nonobviousness standards set for utiHty patents. 

At the heart of a leaching plant design at any level—conceptual, pre-liminaiy, firm engineering, or whatever—is unit-operations and process design of the extraction unit or hne. The major aspects that are particular for the leaching operation are the selection of process and operating conditions and the sizing of the extrac tion equipment. 

Often in the field, designs must be done quickly, for example, during an unexpected plant shutdown. For such cases, shortcut design methods are invaluable. The field invariably has the best perspective on how designs will perform for startup, shutdown, upset, or offload conditions. Experience factors come into play for field review of these design aspects. 

One way in which the material can be used is illustrated by the practice at the University of Toronto. Chapters 1-8 (sections 8.1-8.4) on chemical kinetics are used for a 40-lecture (3 per week) course in the fall term of the third year of a four-year program the lectures are accompanied by weekly 2-hour tutorial (problem-solving) sessions. Chapters on CRE (11-15,17,18, and 21) together with particle-transport kinetics from section 8.5 are used for a similarly organized course in the spring term. There is more material than can be adequately treated in the two terms. In particular, it is not the practice to deal with all the aspects of nonideal flow and multiphase systems that are described. This approach allows both flexibility in choice of topics from year to year, and material for an elective fourth-year course (in support of our plant design course), drawn primarily from Chapters 9,19,20, and 22-24. 

Detailed descriptions of the practical aspects of atomizer performance, plant design, and operation for powder productionthrough atomization of liquid metals have been given by Yule and Dunkley... 

Engineering Aspects of Process Scale-Up and Pilot Plant Design... 

In a chemical plant the capital investment in process piping is in the range of 25-40% of the total plant investment, and the power consumption for pumping, which depends on the line size, is a substantial fraction of the total cost of utilities. Accordingly, economic optimization of pipe size is a necessary aspect of plant design. As the diameter of a line increases, its cost goes up but is accompanied by decreases in consumption of utilities and costs of pumps and drivers because of reduced friction. Somewhere there is an optimum balance between operating cost and annual capital cost. 

Many aspects of the design of biochemical reactors are like those of ordinary chemical reactors. The information needed for design are the kinetic data and the dependence of enzyme activity on time and temperature. Many such data are available in the literature, but usually a plant design is based on laboratory data obtained with small fermenters. Standard sizes of such units range from 50 to 1000 L capacity. 

Because more than one kind of equipment often is suitable for particular applications and may be available from several manufacturers, comparisons of equipment and typical applications are cited liberally. Some features of industrial equipment are largely arbitrary and may be standardized for convenience in particular industries or individual plants. Such aspects of equipment design are noted when feasible. 

Recommendation 2-6. The end points for plant closure of the Aberdeen and Newport facilities should be identified (e.g., allowable residual contamination thresholds and possible future uses of the facilities). Plans for plant design, construction, and operation should include plans for facility closure, and reviews of plant designs should include preliminary plans for closure. Public involvement in determining this aspect of plant design should be encouraged. 

Although not mentioned so far in this section, the process control and instrumentation requirements (see Section 8.2.2) must be considered when selecting the process route. The ability to provide suitable operational control over the process and the availability and cost of necessary instrumentation are major considerations. If these aspects are ignored at this stage, it could well be that the detailed plant design is at... 

Process control and the associated instrumentation were mentioned in relation to the process selection (Section 3.1). To reiterate those comments, these aspects of plant design must be considered during the process selection stage and at other subsequent stages in the design of the plant. Do not assume that any item of equipment or an entire plant that can be designed can also be operated and controlled efficiently. It should be established early in the design that the control and instrumentation aspects are not only feasible but that the cost is within acceptable limits. 

Factors relating to the safety of a chemical plant have so far been ignored. This is mainly because it is impossible to discuss all the aspects of plant design initially in a set of notes. The designer will obviously design items of equipment, and perform other tasks in process design, in... 

New ideas for a process A product and a chemical route are defined. This is the phase in which the core of the process is determined. This means that it is already very important to think about the consequences that selecting a certain pathway has on the future final plant and on the plant costs. Choosing a non-optimal pathway may result in a much more expensive final plant design than if another pathway (or, e.g., another solvent or catalyst) were to be chosen. This is the phase in which it is still relatively easy and cheap to make changes that produce the most intensified process. To be able to know the effect of a chemical route on the final plant requires a multidisciplinary team to be involved at this phase, not just chemists, because more aspects play a role than chemistry. This multidisciplinary team should consist of at least chemists and technologists. 

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