Showing papers in "Advances in Chemical Engineering in 1998"

Combustion Synthesis of Advanced Materials: Principles and Applications

Abstract: Combustion synthesis is an attractive technique to synthesize a wide variety of advanced materials including powders and near-net shape products of ceramics, intermetallics, composites, and functionally graded materials. This method was discovered in the former Soviet Union by Merzhanov et al. (1971). The development of this technique by Merzhanov and coworkers led to the appearance of a new scientijc direction that incorporates both aspects of combustion and materials science. At about the same time, some work concerning the combustion aspects of this method was also done in the United States (Booth, 1953; Walton and Poulos, 1959; Hardt and Phung, 1973). However, the full potential of combustion synthesis in the production of advanced materials was not utilized. The scientijc and technological activity in thejeld picked up in the United States during the 1980s. The signijcant results of combustion synthesis have been described in a number of review articles (e.g., Munir and Anselmi-Tamburini, 1989; Merzhanov, I990a; Holt and Dunmead, 1991; Rice, 1991; Varma and Lebrat, 1992; Merzhanov, 1993b; Moore and Feng, 1995). At the present time, scientists and engineers in many other countries are also involved in research and further development of combustion synthesis, and interesting theoretical, experimental, and technological results have been reported from various parts of the world (see SHS Bibliography, 1996). This review article summarizes the state of the art in combustion synthesis, from both the scientijc and technological points of view. In this context, we discuss wide-ranging topics including theory, phenomenology, and mechanisms of product structure formation, as well as types and properties of product synthesized, and methods for large-scale materials production by combustion synthesis technique.

Computational fluid dynamics applied to chemical reaction engineering

Abstract: Publisher Summary This chapter presents a new emerging tool that is a combination of fluid dynamics (CFD) and numerical mathematics backed up by the immense growth of computer power: computational fluid dynamics. CFD offers great potential for the chemical engineer and that this rapidly emerging new hybrid science of mathematics and mechanics at present already has a profound impact on chemical reaction engineering. It is expected that the role of CFD in the future design of chemical reactors will increase substantially and that CFD can reduce the experimental effort required to develop industrial reactors. A well-known traditional approach adopted in chemical engineering to circumvent the intrinsic difficulties in obtaining the “complete velocity distribution map” is the characterization of nonideal flow patterns by means of residence time distribution (RTD) experiments where typically the response of a piece of process equipment is measured due to a disturbance of the inlet concentration of a tracer. Applications of CFD may be divided into broad categories—those involving single-phase systems and those involving multiphase systems. Within single-phase systems, a further distinction can be made between systems involving laminar flows, turbulent flows, flows with complex rheology, and fast chemical reactions. In many processes encountered in industrial practice, multiphase flows are encountered and, it can be stated that, because of the inherent complexity of such flows, general applicable models and related CFD codes are nonexistent.

Kinetics and Thermodynamics in Multicomponent Mixtures

Abstract: This article reviews the kinetic and thermodynamic behavior of multicomponent mixtures containing a very large number of components, A flurry of activity can be envisaged in recent literature; however; although the needs for lumping in this area have been clearly identfied, it is not always easy to catch the links and the relationships among different works. We review various techniques and results showing the logical status of the latter and how they can be applied to specijic problems. Overall (or global) quantities of interest are identijied with reference to industrial problems, and chemical reaction engineering of systems, where one is interested only in the overall kinetics, are presented. Mathematical techniques through which results are obtained can ofen be cumbersome, and they rely primarily on jhctional analysis. Such techniques are reviewed in the final section of the article.

Using Relative Risk Analysis to Set Priorities For Pollution Prevention At A Petroleum Refinery

Abstract: Publisher Summary This chapter outlines the development of a detailed refinery release inventory that identifies sources and quantities of releases. It identifies options for preventing releases and minimizing health and environmental risks and discusses a system for evaluating and ranking the options in light of cost, risk, regulatory requirements, and other factors. The chapter also describes the methods of evaluating the incentives and obstacles to implementing the pollution prevention options. The chapter highlights the progress that can occur in identifying creative, cost-effective options for pollution prevention when government, industry, and the public establish partnerships rather than operate as adversaries. Pollution prevention cannot be adequately implemented or monitored for effectiveness unless facility operators and regulators know what is being released from the facility and its origin. Government regulatory systems—such as those established by the Clean Water Act or Resource Conservation and Recovery Act (RCRA)—require refineries and other facilities to monitor and measure releases from a few specific points, such as the end of a discharge pipe, or in specific media, such as groundwater. To bridge the gaps in existing data, a multimedia sample collection and analysis effort needs to be undertaken.