Operation and Design Practices

Plant operations personnel generally purchase cooling towers rather than construct them themselves. The philosophy behind this policy is that it makes available to operators a wealth of practical knowledge directly applicable in the field. The operator must specify the amount of water and the temperature range required to handle a specific set of process conditions. It is the fabricator s responsibility to propose a system that will meet the operator-furnished conditions for the 5% wet-bulb in the plant locality. This also means that the fan power with which the operation will be accomplished will be guaranteed. 

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In support of the development of graphite moderated reactors, an enormous amount of research has been conducted on the effects of neutron irradiation and radiolytic oxidation on the structure and properties of graphites. The essential mechanisms of these phenomena are understood and the years of research have translated into engineering codes and design practices for the safe design, construction and operation of gas-cooled reactors. 

An H RA involves a review of the process design and its control, operation, and maintenance practices. The review is conducted by a multidisciplinary team with expertise in the design and operation of the process unit. The team uses a systematic screening process to determine how deviations from normal operation lead to process hazards. The H RA identifies areas where the process risk is too high, requiring the implementation of safety functions. The team s objective is to reduce the risk to below the owner/operator s risk criteria. 

In this section we provide four illustrations of optimization in practice. that is, optimization of process operations and design. These examples will help illustrate the general features of optimization problems, a topic treated in more, detail in Section 1.5. 

The results obtained were checked for parametric sensitivity. It was found that under all practical conditions and for Sp > 0.5 Op > 0.5 runaway can not occur if the selectivity or yield criteria are adhered to. This means that the maintaining of a required selectivity or yield requires more stringent operating and design... 

Current practice requires engineers to have more than a feel for load heating patterns (time-temperature profiles). They must acquire an ability to determine the effects of many operating and design variables on various loads time-temperature curves. The Shannon Method, which enables one to calculate specific time-temperature curves, is discussed briefly several places in this book and then detailed in chapter 8. The reader is encouraged to adapt the Shannon Method for processes other than the steel reheat and forging cases illustrated here. 

To develop the risk-management strategy, start with a process hazards analysis (PHA) and review the process design and its control, operation, and maintenance practices. Select a multidisciplinary team with expertise in these areas, and use an accepted hazard-evaluation procedure, such as a hazard and operability (HAZOP), what-if, or checklist analysis, to determine how process deviations from intended... 

ANSI/ISA 84.01-1996 also establishes specific requirements for the design, installation, operation, and maintenance of SISs. Well-documented technical information are necessary to develop the cases for mitigating risks and to demonstrate that the SIS was designed to meet those requirements, and to show that the operation and maintenance practices are established to maintain the SIS. Ctetailed discussion on these will appear in Chapter VI. 

As described above. Chapters 2 through 4 deal with the fundamentals of adsorption phenomena which are necessary to understand the operation and design of basic adsorption operations introduced in Chapters S to 7. Chapters 8 and 9 are fundamental topics specific to adsorption operations and Chapters 10, 11 and 12 introduce basic ideas on the practical and rather new applications of adsorption phenomena. The reader can start from any chapter of interest and refer to the fundamentals if necessary. 

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