Production technology

In general, methods for the large-scale production of advanced materials by combustion synthesis consist of three main steps (1) preparation of the green mixture, (2) high-temperature synthesis, and (3) postsynthesis treatment. A schematic diagram of these steps is presented in Fig. 4. The first step is similar to 

The main production technologies of combustion synthesis are presented in the second block of Fig. 4. Following Merzhanov (1990a), they may be classified into several major types powder production and sintering, densification, and casting and coating. 

The volume combustion synthesis mode is used primarily for the synthesis of weakly exothermic systems. Various types of heaters, mostly commercially available furnaces, in addition to spiral coil and foil heaters, are used to preheat the sample up to the ignition point. To date, VCS synthesized materials have been produced only in laboratories, and no industrial or pilot production by this mode of synthesis has been reported. 

The third main step of combustion synthesis technologies is postsynthesis treatment. This step is optional, since not all products require additional processing after synthesis. Powder milling and sieving are used to yield powders with a desired particle size distribution. Annealing at elevated temperatures (800-1200°C) removes residual thermal stress in brittle products. The synthesized materials and articles may also be machined into specified shapes and surface finishes. 

The design of a typical commercial reactor for large-scale production of materials is similar to the laboratory setup, except that the capacity of the former is larger, up to 30 liters. Since the synthesis of materials produced commercially is well understood, most reactors are not equipped with optical windows to monitor the process. A schematic diagram of such a reactor is shown in Fig. 5. Typically, it is a thick-walled stainless steel cylinder that can be water cooled (Borovinskaya et al., 1991). The green mixture or pressed compacts are loaded inside the vessel, which is then sealed and evacuated by a vacuum pump. After this, the reactor is filled with inert or reactive gas (Ar, He, Nj, O2, CO, C02). Alternatively, a constant flow of gas can also be supplied at a rate such that it permeates the porous reactant mixture. The inner surface of the reactor is lined with an inert material to 

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At present time, our company is running a development project on the production technology of the MCB type X-ray tubes. The goals of this project are the improvement of the existing technology and making available new tube designs in the near future. 

The propylene-based process developed by Sohio was able to displace all other commercial production technologies because of its substantial advantage in overall production costs, primarily due to lower raw material costs. Raw material costs less by-product credits account for about 60% of the total acrylonitrile production cost for a world-scale plant. The process has remained economically advantaged over other process technologies since the first commercial plant in 1960 because of the higher acrylonitrile yields resulting from the introduction of improved commercial catalysts. Reported per-pass conversions of propylene to acrylonitrile have increased from about 65% to over 80% (28,68—70). 

Production Technology. A moderately high (33.5% 2 5 BPL) grade of phosphate rock is required for the production of a product that contains 20% available P2 5 Significant process variables in the manufacture of NSP are Hsted in Table 5. 

Production Technology. Processes for extraction of P2O3 from phosphate rock by sulfuric acid vary widely, but all produce a phosphoric acid—calcium sulfate slurry that requires soHds-Hquid separation (usually by filtration (qv)), countercurrent washing of the soHds to improve P2O3 recovery, and concentration of the acid. Volatilized fluorine compounds are scmbbed and calcium sulfate is disposed of in a variety of ways. 

Even though form amide was synthesized as early as 1863 by W. A. Hoffmann from ethyl formate [109-94-4] and ammonia, it only became accessible on a large scale, and thus iadustrially important, after development of high pressure production technology. In the 1990s, form amide is mainly manufactured either by direct synthesis from carbon monoxide and ammonia, or more importandy ia a two-stage process by reaction of methyl formate (from carbon monoxide and methanol) with ammonia. 

J. Levins, in Glass Production Technology International, Sterling PubHcations Limited, London, 1992, pp. 47—50. 

A process based on saponification of ethylene—acrylate ester copolymers has been practiced commercially in Japan (29). The saponification naturally produces fully neutralized polymer, and it is then necessary to acidify in order to obtain a pardy neutralized, melt-processible product. Technology is described to convert the sodium ionomer produced by this process to the zinc type by soaking pellets in zinc acetate solution, followed by drying (29). 

As with nearly all other polymers, HDPE resin is a collection of polymer chains of different lengths, varying from short, with molecular weights of 500—1000, to very long, with molecular weights of over 10 million. Relative contents of chains with different lengths (ie, the shape and width of MWD) depend mostly on production technology and on the type of catalyst used for polymerization. The MWD width of HDPE resins can be tailored to specific apphcations. 

X 10 m (585 x 10 bbl) of conventional petroleum is estimated to be undiscovered in the world. This estimate is of undiscovered petroleum resources that are economic to produce by means of normal production technology. 

Another consideration of petroleum assessment analysts is whether, and to what degree, the vast resources of unconventional petroleum in the world can be captured by advances in petroleum production technologies, thereby converting them into conventional sources of petroleum. It is a simple fact that the ia-place resources of petroleum in tar sands, heavy oils, and oil shale can guarantee the future supply of petroleum for hundreds of years at the current rate of consumption, provided they can be produced at competitive costs. 

Since the development of the Spansule brand (Smith Kline Beech am) of coated beads and granules in the late 1960s, various dmg product technologies have been developed and patented to achieve extended durations of therapeutic effects. Each of these does so by various mechanisms of control of dmg release from adrninistered dosage forms. Each method has its advantages and disadvantages, a discussion of which is available in the pharmaceutical hterature (see Drug delivery systems) (21). 

The most effective phosphoms production technology uses a submerged arc furnace. The submerged arc furnace performs three functions chemical reactor, heat-exchanger, and gas—soHd filter, respectively, each of which requires a significant amount of preparation for the soHd furnace feed materials. 

J. A. Radley, ed.. Starch Production Technology, AppHed Science PubHshers, Ltd., London, 1976. 

Styrene manufacture by dehydrogenation of ethylbenzene is simple ia concept and has the virtue of beiag a siagle-product technology, an important consideration for a product of such enormous volume. This route is used for nearly 90% of the worldwide styrene production. The rest is obtained from the coproduction of propylene oxide (PO) and styrene (SM). The PO—SM route is complex and capital-iatensive ia comparison to dehydrogenation of ethylbenzene, but it stiU can be very attractive. However, its use is limited by the mismatch between the demands for styrene and propylene oxides (qv). 

Extraction. Traditionally tea leaf is extracted with hot water either in columns or ketdes (88,89), although continuous Hquid soHd-type extractors have also been employed. To maintain a relatively low water-to-leaf ratio and achieve full extraction (35—45%), a countercurrent system is commonly used. The volatile aroma components are vacuum-stripped from the extract (90) or steam-distilled from the leaf before extraction (91). The diluted aroma (volatile constituents) is typically concentrated by distillation and retained for davoring products. Technology has been developed to employ enzymatic treatments prior to extraction to increase the yield of soHds (92) and induce cold water solubiUty (93,94). 

C. L. ManteU, Tin Its Mining, Production, Technology, and Applications, 2nd ed., Reiohold Publishing Corp., New York, 1949. 

J. L. Henry and co-workers. Bureau of Mines Development of Titanium Production Technology, Bulletin 690, Washington, D.C., 1984. 

The ethylene-based, balanced vinyl chloride process, which accounts for nearly all capacity worldwide, has been practiced by a variety of vinyl chloride producers since the mid-1950s. The technology is mature, so that the probabiUty of significant changes is low. New developments in production technology will likely be based on incremental improvements in raw material and energy efficiency, environmental impact, safety, and process reUabiUty. 

More than one process is available for some of the vitamins. Further, manufacturers have developed variants of the classical syntheses during Optimization. Whereas some of this information is available, as described in the individual sections on vitamins, much is closely held as trade secrets. Judging from the more recent patent Hterature, the assessment can be made that vitamin production technologies are in general mature. However, the economic value of these products drives continuing research aimed at breakthrough processes. Annual production of vitamins varies gready, from ca 10 metric tons of vitamin B 2 to ca 50,000 metric tons of vitamin C. 

Recombinant DNA technology has already provided several products of therapeutic interest from mammalian cells. Table 2 gives examples of products from mammalian cells, the use, and the technology used for production. Technology development for these products has centered around the differences in characteristics of mammalian versus microbial cells, notably, the shear sensitivity and susceptibiUty to contamination of the mammalian lines. 

Soybean-based ice cream products, technologically feasible, are generally not in use because of flavor problems. An acceptable ice cream has been made by replacing 50% of the nonfat milk soHds with a dried soy protein isolate made up of cheese whey (21). Chocolate flavor has been widely used to mask the flavor of soybean proteins in ice cream (see Flavors and spices). 

Product Technology Basically, this encompasses the product technology, such as how to mix certain molecules to make other molecules. This technology ultimately determines the chemical and physical properties of the nnal product. The product recipe is the principal source for the product technology. 

Contains all of the product technology required to make a produc t... 

A processing operation consists of one or more phases. Ideally, only product technology is contained in a processing operation. 

It is not our intention here to give a comprehensive survey of the forming processes listed in Fig. 14.1. This would itself take up a whole book, and details can be found in the many books on production technology. Instead, we look at the underlying principles, and relate them to the characteristics of the materials that we are dealing with. 

The next major commodity plastic worth discussing is polypropylene. Polypropylene is a thermoplastic, crystalline resin. Its production technology is based on Ziegler s discovery in 1953 of metal alkyl-transition metal halide olefin polymerization catalysts. These are heterogeneous coordination systems that produce resin by stereo specific polymerization of propylene. Stereoregular polymers characteristically have monomeric units arranged in orderly periodic steric configuration. 

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