Unit operations foundations

The chemical industry represents a 455-billion-dollar-a-year business, with products ranging from cosmetics, to fuel products, to plastics, to pharmaceuticals, health care products, food additives, and many others. It is diverse and dynamic, with market sectors rapidly expanding, and in turmoil in many parts of the world. Across these varied industry sectors, basic unit operations and equipment are applied on a daily basis, and indeed although there have been major technological innovations to processes, many pieces of equipment are based upon a foundation of engineering principles developed more than 50 years ago. 

What you don t have, can t leak." Small inventories of hazardous materials reduce the consequencies of leaks. Inventories can often be reduced in almost all unit operations as well as storage. This also brings reductions in cost, while less material needs smaller vessels, structures and foundations. 

Despite its present stage of relative infancy, the history of chemical engineering already harbors a number of important themes. One of them is that chemical engineering, as this word is now used in the United States and a number of other countries, refers to a disciplinary and professional structure which saw its original cognitive foundations based on a new notion - that of unit operations. This point has been developed elsewhere (1) but it will be useful to summarize some of the main elements of this story to provide a suitable backdrop for the present paper. 

On the basis of the investigations supported by the National Natural Science Foundation of China, the author of the present book has developed several technical devices for various unit operation processes based on the use of impinging streams, some of which have been discussed in the relevant chapters, while some LIS equipment is introduced below. 

Thermodynamics and kinetics can surely be counted—along with transport phenomena, chemistry, unit operations, and advanced mathematics—as subjects that form the foundation of Chemical Engineering education and practice. Thermodynamics is of course a very old subject. For example, it was the same Rudolf Clausius, who in 1865 coined two immortal sentences (1) "The energy of the universe is constant" and (2) "The entropy of the universe tends to a maximum," that developed the famous Clausius-Clapeyron equation, one of the most basic physico-chemical relationships. Classical thermodynamics was largely complete in the 19th century, before even the basic structure of the atom was understood. 

Fourcroy introduced a significant innovation in the French didactic tradition by fleshing out the operational foundation of theoretical chemistry. His definition of chemistry as a science which tries to discern the intimate reciprocal action of all the bodies of nature on one another was completely new, indicating his emphasis on operations and affinities rather than on principles. He also discussed analysis and synthesis only as the means of chemistry. True or simple analysis produced unaltered principles false or complicated analysis altered them. Synthesis or combination united different bodies by utilizing a force a tendency that existed between them. Although analysis and synthesis were often found united in the operations of chemistry, true analysis was quite... 

SCIENTIFIC FOUNDATIONS OF UNIT OPERATIONS. A number of scientific principles and techniques are basic to the treatment of the unit operations. Some are elementary physical and chemical laws such as the conservation of mass and... 

The behavior of fluids is important to process engineering generally and constitutes one of the foundations for the study of the unit operations. An understanding of fluids is essential, not only for accurately treating problems on the movement of fluids through pipes, pumps, and all kinds of process equipment but also for the study of heat flow and the many separation operations that depend on diffusion and mass transfer. 

His experience, which was far wider than common for chemists (industrial or otherwise) at that time, together with the two characteristics just outlined, undoubtedly combined to produce his profound concept of the unit operation. It was this idea which codified an immense quantity of previously unsystematized knowledge and laid the foundation for chemical engineering as a major subject in its own right. 

Mixing, to a greater extent than any other of the chemical unit operations, retains its status as an art, for it still has very little scientific foundation. On this account, a great number of types of mixers have been B. W. Gamson, Chem. Eng. Progr., 47(1) 19 (1951). 

For this purpose a number of commercial simulation programs are available, such as ASPEN PLUS, PROSIM or CHEMCAD. The calculation of the unit operations is based on the usual foundations for the design of thermal /2.11,2.12, 2.13/, chemical /2.14, 2.15, 2.16, 2.17/, biological /2.18, 2.19, 2.20/ and mechanical processes 12.22, 2.21/. Furthermore, the calculation of the unit operations usually requires comprehensive data on chemical media. Since sufficiently precise data on chemical media are often not available or simplified assumptions have to be made, one will usually not rely only on the results of the simulation calculation. Principally, the reversed way of proceeding is also possible The simulation calculation is preceded and then completed by experimental analyses. 

Unterberger, S., C. Lopez, and K.R.G. Hein. 2001. EU-Project Prediction of Ash and Deposit Formation for Biomass Pulverized Fuel Co-Combustion. Proc. Power Production in the 21 Century Impacts of Fuel Quality and Operations. United Engineering Foundation Advanced Combustion Engineering Research Center. Snowbird, UT. Oct 28 - Nov 2. 

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