Chemical distribution systems

J. P. Bare, B. Johl, and T. A. Lemke, Comparison of Vacuum-Pressure vs. Pump Dispense Engines for CMP Slurry Distribution, Proceedings of SEMlCONtWesl Contamination in Liquid Chemical Distribution Systems Workshop (July, 1998). 

Bare J, Johl B, Lemke T. Comparison of vacuum-pressure vs. pump dispense engines for CMP slurry distributionProceedings of SEMICON/West Contamination in Liquid Chemical Distribution Systems Workshop 1998 July. 

Hiac ChemQual on line sampler is designed to provide a solution for the connection of a particle sensor to bulk chemical distribution systems and distribution valve boxes for pre-hookup qualification. A built-in air pump eliminates the need for an external gas supply for enclosure and line purging. For continuous monitoring applications, the sampler is also compatible with Particle Vision Online facility monitoring software. The light source is a laser diode with count display at 4 channels 0.1, 0.2, 0.3, 0.5 pm at a flow rate of 100 ml min f... 

Water Transportation. Because of the chemical industry s requirements for high volume, low cost transportation, water plays a significant role in the chemical distribution systems both in the United States and internationally. This role should continue and expand in the 1970 s as U.S.-based chemical companies burgeon to global organizations. The chemical giants of the 1970 s will place a heavy reliance on water transportation to effect their worldwide raw material gathering and product distribution networks. 

Different procedures have been reported for decontamination of chemical distribution systems. One such method described a 0.49% by weight aqueous hydrofluoric acid solution that had been successfully tested for the (purity) qualification of a chemical distribution system comprised of PFA tubing and other components.F Both ion removal and particle count can be efficiently accomplished by 48-hour static extraction with the acid solution followed by six hours of water flush. 

SEMI Draft Doc. 2840C (or F57), Provisional Specifications for Polymer Components Used in Ultra-pure Water and Liquid Chemical Distribution Systems, Semiconductor Equipment and Material International, Mountain View, CA, May 1998. 

SEMI (2001) Provisional Specification for Pol3mer Components used in UltraPure Water and Liquid Chemical Distribution Systems, SEMI F57-0301, SEMI, San Jose. 

Chilcote, D., Grant, D., Tan, S., and Carrieri, D. (1998) The extraction of surface and bulk trace metal impurities from typical fluoropolymers. Presented at the 1998 SEMI Workshop on Contamination in Liquid Chemical Distribution Systems, San Francisco, CA, USA. 

In tills chapter we shall examine how such temporal and spatial stmctures arise in far-from-equilibrium chemical systems. We first examine spatially unifonn systems and develop tlie tlieoretical tools needed to analyse tlie behaviour of systems driven far from chemical equilibrium. We focus especially on tlie nature of chemical chaos, its characterization and the mechanisms for its onset. We tlien turn to spatially distributed systems and describe how regular and chaotic chemical patterns can fonn as a result of tlie interjilay between reaction and diffusion. 

Our understanding of the development of oscillations, multi-stability and chaos in well stirred chemical systems and pattern fonnation in spatially distributed systems has increased significantly since the early observations of these phenomena. Most of this development has taken place relatively recently, largely driven by development of experimental probes of the dynamics of such systems. In spite of this progress our knowledge of these systems is still rather limited, especially for spatially distributed systems. 

Other Energy Systems. Chemical plants usually require cooling water, compressed air, and fuel distribution systems. Sometimes also included are refrigeration, pressurized hot water, or specialized heat-transfer fluids such as Therrninol Hquid or condensing vapor. Each of these systems serves the process and reflabiUty is the most important characteristic. Thus a project in any of them that achieves a 10% reduction in energy cost at the expense of a 1% loss of rehabihty loses money for the operation. 

An important issue is howto solve large problems that occur in distributed systems. The optimization of distributed systems is discussed in Refs. 52, 120, 244, and 285. For further reading on optimization, readers are directed to Refs. 120 and 244 as well as introductory texts on optimization applied to chemical engineering (Refs. 99 and 225). The material in this section is part of a more advanced treatment (Ref. 295). 

At present, chlorine dioxide is primarily used as a bleaching chemical in the pulp and paper industry. It is also used in large amounts by the textile industry, as well as for the aching of flour, fats, oils, and waxes. In treating drinking water, chlorine dioxide is used in this country for taste and odor control, decolorization, disinfection, provision of residual disinfectant in water distribution systems, and oxidation of iron, manganese, and organics. The principal use of chlorine dioxide in the United States is for the removal of taste and odor caused by phenolic compounds in raw water supplies. 

Murphy, J. R., Air Products-HRI, The Development of Feed and Air Distribution Systems in Fluid Catalytic Cracking, presented at the 1984 Akzo Chemicals Symposium, Amsterdam, The Netherlands... 

The vast majority of modem liquid chromatography systems involve the use of silica gel or a derivative of silica gel, such as a bonded phase, as a stationary phase. Thus, it would appear that most LC separations are carried out by liquid-solid chromatography. Owing to the adsorption of solvent on the surface of both silica and bonded phases, however, the physical chemical characteristics of the separation are more akin to a liquid-liquid distribution system than that of a liquid-solid system. As a consequence, although most modern stationary phases are in fact solids, solute distribution is usually treated theoretically as a liquid-liquid system. 

Chemical treatment is apphcable usually to raw, mains and softened water, but is also used to treat the storage and distribution systems of distilled and deionized water and of water produced by reverse osmosis (seetion 3.5). 

Respiratory Effects. One study suggested increased respiratory disorders (asthma, bronchitis, pneumonia) in children with chronic exposure to a solvent-contaminated water supply (Byers et al. 1988). Two municipal wells in eastern Woburn, Massachusetts, were found to contain several solvents including trichloroethylene (267 ppb) and tetrachloroethylene (21 ppb). The increased susceptibility to infection may be secondary to effects on the immune system. Accurate chemical-specific exposure levels for individuals could not be determined because the water distribution system was designed to use water from different wells at different rates and times. Other limitations of this study are described in Section 2.2.2.8. 

The fourth example, the use of chemical processing on Mars for producing a propellant, is presented in Section 1.9.7 [106]. The fifth and last example describes the use of distributed systems for global carbon dioxide management, aiming at reducing the greenhouse effect [106]. The main issue here is the installation of gas-absorption equipment for CO2 capture at central, fossil-fuel power plants. 

SPRESI database, distributed by Daylight Chemical Information Systems Inc., Mission Viejo, CA, USA, http //www. daylight.com. 

A detailed account of the factors to be considered when designing electrical distribution systems for chemical process plants, and the equipment used (transformers, switch gear and cables), is given by Silverman (1964). 

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