Abstract:Edgewise and stringer accumulations of shells may be formed by current as well as wave activity, but the results can be distinguished by particular criteria. This distinction will be important for the recognition of wave-generated storm coquinas. Extending on earlier studies about current orientations of isolated shells, the occurrence of a 2nd stable position is referred to higher current velocities.
Exergy analysis and assessment of process plants with flow-sheeting systems. Mass and enthalpy balances are necessary for the calculation and assessment of process plants. The economic and ecological results cannot be optimal because the different value of energy according to the Second Law of Thermodynamics and the influence of the environment are not included. This is accomplished by exergetic analysis and assessment. The aim is to obtain an exergy analysis and assessment of any procesSplant through combination with a flowsheeting system. Because the exergy is dependent on the choice of a reference state, an environmental model is proposed which is suitable in regard to the above-mentioned aim.
Flowsheeting systems for process simulation. Simulation of process plants with flowsheeting systems has been state of the art in chemical plant design and in the chemical industry for many years. Modern computers now permit steady state simulation of complex chemical plants with sufficient accuracy. This paper outlines the different approaches to steady state process simulation, names the advantages and disadvantages, and gives an outlook on further developments. Process optimization, process integration, and process synthesis will be discussed. The integration of different programs, e.g. the connection between flowsheeting systems and computer‐aided design (CAD) will be described. An advance in user friendliness will be reached by latest developments in the field of personal computers and workstations and by database management systems.
Computer-aided exergy optimization of chemical engineering processes. Methods of exergy evaluation as the basis of energy and material analysis of chemical processes have been used for some years to evaluate these processes from the view point of the First and Second Law of Thermodynamics and with regard to their influence on the environment. This paper introduces a tool for computer-aided exergy analysis and optimization of complex process plants. This tool is based on a flowsheeting program that is extended to calculate the exergy of material, heat, and work flows. The optimization problem of process plants is solved in a two level approach by parameter optimization and structural optimization. The parameter optimization is realized automatically by the extended flowsheeting program.The structural optimization is based on heuristic rules and experiences of the process engineer.
The optimal layout of a chemical plant is determined by both economic and environmental aspects. The mathematical approach to this problem is given by representing the process through a superstructure, including any foreseeable process topology. It is described by integer variables, whereas real variables arise from the unit models and the thermodynamic calculations. By including process constraints and an objective function, a Mixed Integer Nonlinear Programming (MINLP) optimization problem is postulated. In this paper MINLP algorithms are combined with a technique for the exergy analysis of chemical processes for the preliminary screening of process alternatives. The exergy analysis as a screening technique is advantageous due to a significantly smaller amount of required data and computing time, compared with true optimization, including cost estimation at an earlier stage of process synthesis and analysis. Thus, a broader solution space can be examined. The subsequent cost analysis has then only to be focused on a reduced set of parameters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.