Process evolution manufacturing

Silverstein, J. L. et al., Loss Prev., 1981,14, 78 Nitrobenzene was washed with dilute (5%) sulfuric acid to remove amines, and became contaminated with some tarry emulsion that had formed. After distillation, the hot tarry acidic residue attacked the iron vessel with hydrogen evolution, and an explosion eventually occurred. It was later found that addition of the nitrobenzene to the diluted acid did not give emulsions, while the reversed addition did. A final wash with sodium carbonate solution was added to the process [1]. During hazard evaluation of a continuous adiabatic process for manufacture of nitrobenzene, it was found that the latter with 85% sulfuric acid gave a violent exotherm above 200° C, and with 69% acid a mild exotherm at 150- 170°C [2],... 

Lees (1980) describes reduction in process inventory in the evolution of the processes for manufacturing nitroglycerine. The first is a batch process with a... 

Lithographic modeling and simulation have found wide applications, spanning research, process development, manufacturing process optimization and control, and even education within the semiconductor industry. A few notable examples of these applications and their roles in shaping the evolution of lithography are outlined helow. 

During the past three decades, manufacturing underwent many transformations. The primary process evolutions were total quality management (TQM), theory of constraints (TOC), Lean and the Toyota production system (TPS), and Six Sigma, ft will change even further as companies implement the new processes for digital manufacturing (covered in Chapter 6). 

What was the answer for Cisco The company built strong horizontal processes to coimect sales and operations planning (S OP) to contract manufacturing. Based on this process evolution, it was one of the first companies to sense the economic downturn of December 2008. It weathered the storm of the recession with no write-offs. 

Over the last 35 years, the process for manufacturing PC has undergone significant modernization and evolution. Early process attempts at melt transesteriflcation and solution polymerization with pyridine were both deemphasized based on equipment limitations and economics, respectively. Both batch and continuous processes are practiced today. Solution polymerization in methylene chloride in contact with aqueous sodium hydroxide has become the preferred process by some major producers. Melt polymerization has also regained attention, facilitated by improvements in polymerization equipment. Melt polymerization also addresses recent concerns with potential release of volatile organic compounds into the environment. 

The fact that most of these tetrazole side chain elements for Cephalosporins since years are now produced worldwide at a volume of several 100 t/a demonstrates that azide chemistry - whose evolution to commercial scale was originally a source for concern -has come of age. It is now also offered as a standard production process by manufacturers that have specialized on the safe handling of the risk potential, also in custom synthesis. The safety risks associated with the handling of azides should not be underestimated, however. Its toxicity and the latent hazard of formation of highly explosive hydrazoic acid intermediates require expertise and plants with specific safety features for the safe handling of azides. 

Manufacturing History. As pointed out in Sec. 6.1.4, because of the high viscosity and high volatility of silica (SiOj) at the temperatures needed to melt its crystalline phases, specialized techniques are required to prepare silica glass products. Some key highlights in process evolution include ... 

Air-Based Direct Oxidation Process. A schematic flow diagram of the air-based ethylene oxide process is shown in Figure 2. Pubhshed information on the detailed evolution of commercial ethylene oxide processes is very scanty, and Figure 2 does not necessarily correspond to the actual equipment or process employed in any modem ethylene oxide plant. Precise information regarding process technology is proprietary. However, Figure 2 does illustrate all the saUent concepts involved in the manufacturing process. The process can be conveniently divided into three primary sections reaction system, oxide recovery, and oxide purification. 

Cooler Absorbers When the absorption of a gas is accompanied by the evolution of heat, an important function of the absorption equipment is the removal of the heat generated. This may be accomplished by using a number of towers in series, the liquid from each tower being circulated through an external cooler. There are different types of cooler-absorbers in which processes of this type can be carried out in a single unit. The materials of which these cooler-absorbers are constructed should be of high thermal conductivity and resistant to corrosion by the substances used in the process. As an example, in the manufacture of hydrochloric acid of the... 

Fermentation An anaerobic bioprocess. An enzymatic transformation of organic substrates, especially carbohydrates, generally accompanied by the evolution of gas as a byproduct. Fermentation is used in various industrial processes for the manufacture of products (e.g., alcohols, organic acids, solvents, and cheese) by the addition of yeasts, moulds, and bacteria. 

A process involving water electrolysis is the production of heavy water. During cathodic polarization the relative rates of deuterium discharge and evolution are lower than those of the normal hydrogen isotope. Hence, during electrolysis the solution is enriched in heavy water. When the process is performed repeatedly, water with a D2O content of up to 99.7% can be produced. Electrochemical methods are also used widely in the manufacture of a variety of other inorganic and organic substances. 

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