Conventional process description

This work focuses on the reactor section of the styrene production process because it is the most promising part for the implementation of membranes. The reactor section of this process is shown in Fig. 14.9 [50]. 

The process uses two radial reactors in series with one preheater and one interstage heater. Steam is used as an energy carrier (adiabatic reactor) and diluent [43,50,51]. Reactor temperatures and pressures are 570-630°C and 1.5 bar, respectively. Total hydrocarbon mass flow (96 wt% ethylbenzene) is 95,000 kg/h. The steam/hydrocarbon ratio is 2. Typical conversion, selectivity and yield numbers are 71, 92 and 66%, respectively. Definitions are given in the appendix. Reaction equations and kinetics are taken from literature [43,51]. 

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Although most injection molding processes are covered by the conventional process description discussed earlier in this chapter, there are several important molding variations including ... 

These definitions are used to abstract the underlying process representation. As shown in Fig. 2, MODEL.LA. allows us to construct an abstract representation utilizing these definitions for our specific application from a conventional process description. This abstract representation has access to any utility, tool, or component that constitutes the base representation. 

The products of reactions generating double bonds can exhibit positional isomerism, as rotation of the moieties, given before the reaction, is now prevented. This is usually referred to as cis/trans or, as a complementary description, Z/E isomerism. There are first hints that cis/trans or ZjE ratios of the products with micro-reactor processing differ from the corresponding data for conventional processing. 

Our discussion of these processes will necessarily be qualitative and primarily descriptive. We will describe raw materials, products, process conditions, reactor configurations, catalysts, etc., for what are now the conventional processes for producing these products. We will expect the student to show basic familiarity with these processes by answering simple and qualitative questions about them on exams. This will necessarily require some memorization of facts, but these processes are sufficiently important to all of chemical technology that we believe all chemical engineers should be literate in their principles. 

The types of information on hydrocarbons from petroleum and natural gas vary widely. The patent literature on manufacture and separation of the hydrocarbons is voluminous. Articles in chemical, engineering, and oil journals include reviews, descriptions of processes, descriptions of entire plants, discussions of construction materials for these plants, discussions of the adaptation of conventional facilities for production of specific hydrocarbons, discussions of utilization, enumeration of plants operating, analyses of present requirements, and predictions of future demands. Many of these journals also publish news items announcing the availability of new hydrocarbons and the construction of new plants. Recently a number of journals have established the practice of publishing staff reports on a specific product or group of products. These give the present status... 

The most conventional kinetic scheme of FRP includes initiation, propagation, and bimolecular termination reaction steps. Additional reactions such as chain transfer are introduced to improve the process description. Free radicals are highly reactive chemical species produced by the homolytic dissociation of covalent bonds. Such species are produced through physical (thermoexcitation, radiation) or chemical methods (oxidation-reduction, addition, etc.). Generally, their survival time is less than a second, except for those radicals highly stabilized by specific chemical groups the hybridization state is sp. ... 

Our aim in this section is to consider some unusual thermodynamic properties of chemical systems that could reveal themselves by decreasing the system dimensions. For this purpose we will analyze a simple model simulating the chemical reaction PQ P -h Q within a small volume conflned by a closed vesicle. We will see that small dimensions of vesicles under certain circumstances can impose limitations on the conventional thermodynamic description of chemical reactions based on the mass action law. The model considered may help to simulate chemical processes in the interior of small energy-transducing organelles. 

Process Description. Amoco has numerous configurations for the CBA process (Berman. 1992). involving from two to four total catalytic converters. The total number of converters utilized and their split between conventional Claus operation and sub-dewpoint operation is... 

We have found that display of nuclear trajectories and the simultaneous evolution of charge distributions to yield insightful details of complicated processes. Such descriptions also map more readily to the actual experimental conditions than do the more conventional time-independent scattering matrix descriptions. 

Unlike most conventional materials, there is a very close relation between the manufacture of a composite material and its end use. The manufacture of the material is often actually part of the fabrication process for the structural element or even the complete structure. Thus, a complete description of the manufacturing process is not possible nor is it even desirable. The discussion of manufacturing of laminated fiber-reinforced composite materials is restricted in this section to how the fibers and matrix materials are assembled to make a lamina and how, subsequently, laminae are assembled and cured to make a laminate. 

It seems probable that a fruitful approach to a simplified, general description of gas-liquid-particle operation can be based upon the film (or boundary-resistance) theory of transport processes in combination with theories of backmixing or axial diffusion. Most previously described models of gas-liquid-particle operation are of this type, and practically all experimental data reported in the literature are correlated in terms of such conventional chemical engineering concepts. In view of the so far rather limited success of more advanced concepts (such as those based on turbulence theory) for even the description of single-phase and two-phase chemical engineering systems, it appears unlikely that they should, in the near future, become of great practical importance in the description of the considerably more complex three-phase systems that are the subject of the present review. 

Student drawings and descriptions of their conceptions of structures and processes at the molecular level often reveal misconceptions not detectable in conventional equation-writing questions (p. 155). 

Needless to say, all conclusions drawn in Sections 1.1.1-1.1.7 are ideal-case considerations of an abstract nature aimed at showing the maximum potential of chemical micro processing, and the ideas behind. In reality, a performance less than ideal (but often better than conventional) may be found, at least initially, e.g. for reasons of imperfect exhibition of flow patterns or due to limits of micro flow compared with existing technology. This reality description is given in Chapters 3-5. 

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