This approach to synthesis is one of making a series of best local decisions. Equipment is added only if it can be justified economically on the basis of the information available, albeit an incomplete picture. This keeps the structure irreducible, and features which are technically or economically redundant are not included.  [c.8]

The shaded areas in Fig. 6.24, known as pockets, represent areas of additional process-to-process heat transfer. Remember that the profile of the grand composite curve represents residual heating and cooling demands after recovering heat within the shifted temperature intervals in the problem table algorithm. In these pockets in Fig. 6.24, a local surplus of heat in the process is used at temperature differences in excess of AT ,in to satisfy a local deficit.  [c.186]

Local and Global Tradeoffs  [c.239]

Two broad classes of tradeoffs can be identified when optimizing a given flowsheet structure. Local tradeoffs, when carried out around an operation, do not affect other operations in the flowsheet. Global tradeoffs cause changes throughout the flowsheet. Caution should be exercised in judging whether an optimization is local if it involves the use of energy. If an operation uses energy, this might be supplied from an external utility or by heat integration. The apparently local tradeoff between reflux and plates in a distillation column might well turn out to have features of a global tradeoff if the reboiler and/or condenser are heat integrated with the rest of the process. If this is the case, then changing the reflux ratio affects the overall heat integration problem.  [c.252]

Local and global emissions. When considering utility waste, it is tempting to consider only the local emissions from the process and its utility system (Fig. 10.8a). However, this only gives part of the picture. The emissions generated from central power generation are just as much part of the process as those emissions generated on-site (Fig. 10.86). These emissions should be included in the assessment of utility waste. Thus global emissions are defined to be °  [c.291]

Assessing only the local efiects of combined heat and power is misleading. Combined heat and power generation increases the local utility emissions because, besides the fuel burnt to supply the heating demand, additional fuel must be burnt to generate the power. It is only when the emissions are viewed on a global basis, and the emissions from central power generation included, that the true picture is obtained. Once these are included, on-site combined heat and power generation can make major reductions in global utility waste. The reason for this is that even the most modem central power stations have a poor efficiency of power generation compared with a combined heat and power generation system. Once the other inefficiencies associated with centralized power generation are taken into account, such as distribution losses, the gap between the efficiency of combined heat and power systems and centralized power generation widens.  [c.292]

Biological treatment. In secondary, nr biological treatment, a concentrated mass of microorganisms is used to break down organic matter into stabilized wastes. Large chemical factories might require their own biological treatment processes. Smaller sites might rely on local municipal treatment processes which treat a mixture of industrial and domestic effluent.,  [c.313]

Steam costs vary with the price of fuel. If steam is only generated at low pressure and not used for power generation in steam turbines, then the cost can be estimated from local fuel costs assuming a boiler efficiency of around 75 percent (but can be significantly higher) and distribution losses of perhaps another 10 percent, giving an overall efficiency of around 65 percent.  [c.408]

C. It is secreted along with noradrenaline by the adrenal medulla, from which it may be obtained. It may be synthesized from catechol. It is used as the acid tartrate in the treatment of allergic reactions and circulatory collapse. It is included in some local anaesthetic injections in order to constrict blood vessels locally and slow the disappearance of anaesthetic from the site of injection. Ultimately it induces cellular activation of phosphorylase which promotes catabolism of glycogen to glucose.  [c.16]

White crystals, m.p. 90-9 rC. Prepared fromp-nitrotoluene by way of p-aminobenzoic acid. It is used as a local anaesthetic on mucous surfaces internally and by injection, and is taken internally to relieve gastric pain.  [c.56]

Cocaine is the oldest of the local anaesthetics. It is a central nervous system stimulant and is habit-forming. See ecgonine.  [c.105]

This invaluable French-English, English-French dictionary includes both the literary and dated vocabulary needed by students, and the up-to-date slang and specialized vocabulary (scientific, legal, sporting, etc) needed in everyday life. As a passport to the French language, it is second to none.  [c.439]

However, before extrapolating the arguments from the gross patterns through the reactor for homogeneous reactions to solid-catalyzed reactions, it must be recognized that in catalytic reactions the fluid in the interior of catalyst pellets may diSer from the main body of fluid. The local inhomogeneities caused by lowered reactant concentration within the catalyst pellets result in a product distribution different from that which would otherwise be observed.  [c.48]

As the amount of temperature cross increases, however, problems are encountered, as illustrated in Fig. 7i8c. Local reversal of heat flow may be encountered, which is wasteful in heat transfer area. The design may even become infeasible.  [c.223]

Consider again the simple process shown in Fig. 4.4d in which FEED is reacted to PRODUCT. If the process usbs a distillation column as separator, there is a tradeofi" between refiux ratio and the number of plates if the feed and products to the distillation column are fixed, as discussed in Chap. 3 (Fig. 3.7). This, of course, assumes that the reboiler and/or condenser are not heat integrated. If the reboiler and/or condenser are heat integrated, the, tradeoff is quite different from that shown in Fig. 3.7, but we shall return to this point later in Chap. 14. The important thing to note for now is that if the reboiler and condenser are using external utilities, then the tradeoff between reflux ratio and the number of plates does not affect other operations in the flowsheet. It is a local tradeoff.  [c.239]

Heterogeneous catalysts are more common. However, they degrade and need replacement. If contaminants in the feed material or recycle shorten catalyst life, then extra separation to remove these contaminants before the feed enters the reactor might be justified. If the cataylst is sensitive to extreme conditions, such as high temperature, then some measures can help to avoid local hot spots and extend catalyst life  [c.279]

When utility waste was considered, it was found that to obtain a true picture of the flue gas emissions associated with a process, both the local on-site emissions and those generated by centralized power generation corresponding to the amount of power imported (or exported) need to be included. In the limit, this basic idea can be extended to consider the total emissions (process and utility) associated with the manufacture of a given product in a life-cycle analysisf In life-cycle analysis, a cradle-to-grave view of a particular product is taken. We start with the extraction of the initial raw materials from natural resources. The various transformations of the raw materials are followed through to the manufacture of the final consumer product, the distribution and use of the consumer product, recycling of the product, if this is possible, and finally, its eventual disposal. Each step in the life cycle creates waste. Waste generated by transportation and the manufacture and maintenance of processing equipment also should be included.  [c.295]

McGraw-Hill books are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. For more information, please write to the Director of Special Sales, McGraw-Hill, Inc., 11 West 19th Street, New York, N.Y. 10011. Or contact your local bookstore.  [c.464]

Me2NCH2) C2H5)(Me)C-OOC Ph-HCI. Colourless crystalline powder with a bitter taste, m.p. 177-179"C. Prepared by the action of ethyl magnesium bromide on dimethyl-aminoaceione. It is a local anaesthetic, mainly used to produce spinal anaesthesia.  [c.33]

See pages that mention the term Local : [c.11]    [c.49]    [c.241]    [c.292]    [c.292]    [c.293]    [c.406]    [c.27]    [c.33]    [c.70]    [c.75]    [c.167]    [c.169]    [c.170]    [c.209]    [c.235]    [c.241]    [c.241]    [c.241]    [c.244]    [c.286]    [c.304]    [c.304]    [c.327]    [c.328]    [c.369]    [c.416]   
Encyclopedia of materials characterization (1992) -- [ c.0 ]

Advanced control engineering (2001) -- [ c.0 ]