Pollution prevention reactors

In order to perform waste reduction and pollution prevention in reactor design, studying the effects of reaction... 

Lakshmanan A, Biegler LT. Reactor network targeting for waste minimization. In El-Halwagi M, Petrides D, eds. Pollution Prevention via Process and Product Modifications AIChE Symposium Series 90. New York AIChE 128, 1994. 

Dionysou DD, Balasubramanian G, Suidan MT, Baudin I, Laine JM. Thin film photocatalytic reactor for the destruction of organic contaminants in industrial wastewater and drinking water. In Abraham MA, Hesketh RP, eds. Reaction Engineering for Pollution Prevention. Amsterdam Elsevier, 2000 137-153. 

Section I provides an introduction to green chemistry and green engineering. Section II provides examples of pollution prevention heuristics for chemical processes. Heuristics of the two most important unit operations, reactors and separators, are covered. Section III introduces readers to the concept of environmental fate and transport and prediction of environmental fate properties. Understanding of environmental fate and transport is important for exposure assessment and also is essential for evaluating environmental performance of processes and products during process development and design. 

Pollution Prevention Technologies Practices Batch operations Equipment parts cleaning Reactor design operation High-value waste Water usage Organic solvents pH control... 

Krishna has worked for the Shell Oil Cbmpany for many years his chapter on the selection of multiphase reactors carries the knowledge of a skilled practitioner, which complements his theoretical teachings as a professor at the University of Amsterdam. Allen is one of the early pioneers in the application of engineering design to pollution prevention, and his chapter deals with macro-, meso-, and microscales. Seinfeld et al. write on tropospheric chemistry, the arena where a great many of our air pollution problems reside. 

One of the most obvious methods is to maximize the selectivity for styrene in the reactor. The ethylbenzene is already being recycled however, minimizing the amount of ethylbenzene in the benzene/toluene effluent stream is both sound economics and pollution prevention. The fate of the benzene/toluene stream is also important. Because ethylbenzene is made from benzene, the benzene can be separated and returned to the ethylbenzene plant, which is almost always at the same facility. This is sound pollution prevention, although it might not qualify as pollution prevention according to the Pollution Prevention Act, because it does not constitute in-process recycle. 

J.A. Dyer, K.L. Mulholland, Prevent pollution via better reactor design and operation, Chem. Eng. Prog. 94 (2) (1998) 61-66. 

Ohmic heating of catalyst is often used as a simple method of igniting the chemical reaction during reactor startup, for instance, in the oxidation of ammonia on platinum-rhodium gauze catalysts. Another application is the prevention of cold-start emissions from automotive catalysts responsible for much of the residual pollution still produced from this source (21). The startup times needed for the catalyst to attain its operating temperature can be cut by a factor of 5 or more by installing an electrically heated catalyst element with a metallic support upstream of the main catalyst unit. Direct electrical catalyst heating permits facile temperature control but requires a well-defined catalyst structure to function effectively. 

Encapsulation in containment vessels allows near zero emission rates to be reached in miniplants, e.g. by purging the reactor with an inert gas sent to a scrubber. This embedding of the miniplant should also dramatically reduce the risk of explosion or environmental contamination in case of an accident Even if modules of the miniplant are damaged or break, the robust encasement will be mechanically and chemically stable enough to prevent pollution. 

Wastewater treatment systems can be classified, in addition to pretreatment, as preliminary, primary, secondary, and tertiary (advanced) treatments. Pretreatment of industrial wastewater is required to prevent adverse effects on the municipal wastewater treatment plants. Preliminary treatment is considered as any physical or chemical process that precedes primary treatment. The preliminary treatment processes may consist of influent screening and grit removal. Its function is mainly to protect subsequent treatment units and to minimize operational problems. Primary treatment is defined as the physical or chemical treatment for the removal of settleable and floatable materials. The screened, degritted raw wastewater from preliminary treatment flows to the primary clarification tanks, which are part of the primary treatment facilities. Secondary wastewater treatment is the process that uses biological and chemical treatment to accomplish substantial removal of dissolved organics and colloidal materials. The secondary treatment facilities may be comprised of biological reactor and secondary clarification basins. Tertiary (advanced) wastewater treatment is used to achieve pollutant reductions by methods other than those used in primary and secondary treatments. The objective of tertiary wastewater treatment is to improve the overall removal of suspended solids, organic matter, dissolved solids, toxic substances, and nutrients. 

Hydrogenolysis of C-S bonds is followed by hydrogenation. Petroleum fractions are desulfurized for many reasons to protect catalysts, to improve product quality, and to prevent environmental pollution. Feedstocks vary from light naphthas to heavy residua and require reactors of increasing... 

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