Process equipment knowledge

The separation of components by liquid-liquid extraction depends primarily on the thermodynamic equilibrium partition of those components between the two liquid phases. Knowledge of these partition relationships is essential for selecting the ratio or extraction solvent to feed that enters an extraction process and for evaluating the mass-transfer rates or theoretical stage efficiencies achieved in process equipment. Since two liquid phases that are immiscible are used, the thermodynamic equilibrium involves considerable evaluation of nonideal solutions. In the simplest case a feed solvent F contains a solute that is to be transferred into an extraction solvent S. 

Persons familiar with the operation of the facility if the facility has no operating history, then operators from similar facilities may be included on the team. Frontline personnel are preferable, as they usually have the most accurate knowledge of the process equipment and procedures used during day-to-day operation, and are highly motivated to identify and eliminate hazards. 

Other avenues for increasing process safety knowledge exist. Previously unrecognized potential hazards and latent properties of materials are written about in industry and technical journals. Peer-reviewed research work in the area of process safety is published in several international scientific journals. Manufacturers and suppliers of process equipment often publicize previously unrecognized failure modes. Additional information on case histories can be found in Chapter 15. 

This safety audit is used for identifying inputs and material flows, processes and intermediates, and final products - but with special attention paid to human-material/process/equipment interactions that could result in (a) sudden and accidental releases/spills, (b) mechanical failure-based injuries, and (c) physical injuries - cuts, abrasions, and so on, as well as ergonomic hazards. Additional sources of adverse effects/safety problem areas are records/ knowledge of in-plant accidents/near misses, equipment failures, customer complaints, inadequate secondary prevention/safety procedures and equipment (including components that can be rendered non-operable upon unanticipated events), and inadequacies in suppliers of material and equipment or maintenance services. 

But in this book, we have gone back to the very simplest basis for understanding process equipment. In every chapter we have said, Here is how the equipment behaves in the field, and this is why. We have shown how to do simple technical calculations. The guiding idea of our book is that it is better to have a working knowledge of a few simple ideas, than a superficial knowledge of many complex theoretical subjects. 

Incidentally, if a bird builds its nest on top of one our roof toilet vents, we find the toilet will no longer flush properly. The experienced plumber states that the toilet won t flush because it is suffering from vapor lock and this is true. A working knowledge of process equipment fundamentals often comes in quite handy around the home. 

I rather like this problem. It illustrates how knowledge of one type of process equipment (a distillation tower) can help us understand problems in a piece of equipment that is superficially quite a bit different. 

The general knowledge as to how process equipment really functions, is disappearing from the process industries. This is not only my opinion, but the general view of senior technical managers, in many large corporations. 

This information would be determined by measuring the heat and airflow at various points of the chamber and then calculating the variability of these conditions in it. Since this kind of information on heat distribution provides assurance that the process equipment is properly designed for the required process, it will be the focus of future QA audits. Furthermore, this knowledge is also essential when a very specific drying temperature is needed for thermally labile materials. The qualification thus not only becomes an integral part of the validation program, but also demonstrates how the information may be used. 

It is noteworthy that the principles and concerns have not changed very much in the last 22 years. To my knowledge, this is also the first general treatise discussing qualification of process equipment and support systems. 

In all the just-mentioned examples, quantitative prediction and design require the detailed knowledge of the residence time distribution functions. Moreover, in normal operation, the time needed to purge a system, or to switch materials, is also determined by the nature of this function. Therefore the calculation and measurement of RTD functions in processing equipment have an important role in design and operation. 

In spite of the enormous use of vacuum processes, detailed knowledge of vacuum technology is often lacking. Design calculations are often attempted with incomplete or inadequately-interpreted data and, even with well-designed systems, operators may lack the confidence to use them optimally and often struggle to solve relatively small problems when they arise. In both cases, at some cost and delay, there is complete reliance on vacuum equipment manufacturers appraisal. 

The continuous development of the modem process industries has made it increasingly important to have information about the properties of materials, including many new chemical substances whose physical properties have never been measured experimentally. This is especially true of polymeric substances. The design of manufacturing and processing equipment requires considerable knowledge of the processed materials and related compounds. Also for the application and final use of these materials this knowledge is essential. 

In general, it is safer to totally contain, or nearly totally contain, hazardous and flammable materials in chemical processes, if it is reasonably practical to do so, than to allow these materials to escape into the environment. In many cases, this can be accomplished by designing the processing equipment to withstand the maximum pressure that can be expected from runaway polymerizations or other reactions or explosions. This requires detailed knowledge of the process and the possible overpressure that could result. This knowledge can best be obtained from experimental data combined with a theoretical analysis. 

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