Economic optimization references

This chapter includes a discussion of how to formulate objective functions involved in economic analysis, an explanation of the important concept of the time value of money, and an examination of the various ways of carrying out a profitability analysis. In Appendix B we cover, in more detail, ways of estimating the capital and operating costs in the process industries, components that are included in the objective function. For examples of objective functions other than economic ones, refer to the applications of optimization in Chapters 11 to 16. 

Gaensslen, H., "Thermal Efficiency and Economic Optimization in Chemical Plants," In reference 18, p. 281 (1981). 

Economic optimization. The selection of parameters for a reference design must be based upon economics. An economic optimization was accomplished by computing relative energy costs based on those variable costs which depend upon the parameters selected. The costs which are dependent upon the nuclear parameters are (1) bismuth inventory, (2) fuel inventory, (3) fuel burnup, (4) thorium inventory, (5) thorium burnup, (6) reactor core and vessel, and (7) chemical processing costs. 

Plant Operation and Costs. The operation and economics of the three United States gaseous diffusion plants miming ia 1972 is discussed ia References 29 and 30. These plants were operated as a single gaseous diffusion complex such that iaterplant shipments occurred so as to optimize the overall system. Independent operation of the plants would have resulted ia about a 1% loss ia separative work. 

Extensive design and optimization studies have been carried out for this sequence (108). The principal optimization variables, ie, the design variables that have the largest impact on the economics of the process, are the redux ratio in the azeo-column the position of the tie-line for the mixture in the decanter, determined by the temperature and overall composition of the mixture in the decanter the position of the decanter composition on the decanter tie-line (see Reference 104 for a discussion of the importance of these variables) and the distillate composition from the entrainer recovery column. 

In order to generate a candidate EAR, one should consider potential raw materials and by-products, satisfaction of stoichiometric conditions, assurance of thermodynamic feasibility, and fulfillment of environmental requirements. These issues can be addressed by employing an optimization formulation to identify an overall reaction that yields the desired product at maximum economic potential while satisfying stoichiometric, thermodynamic, and environmental constraints. For a more detailed description of this optimization program, the reader is referred to Crabtree and El-Halwagi (1994). 

Optimization techniques are procedures to make something better. Some criteria must be established to determine whether something is better. The single criterion that determines the best among a number of alternatives is referred to as the performance index or the objective function. Economically, this is the expected profit for a plant design. It may be expressed as the net present value of the project. 

How can one proceed economically in fields of research which can only be explored empirically This is possible by designing experiments so that a maximum of new information is obtained, i.e. by optimizing the information-expense ratio. For the medicinal chemist, the term experiment signifies in this context test compounds and the information refers to structure-activity information. At this point two main problems arise, i.e. 

We have at our disposal a large number of parameters known both from reference literature or experience. We should define a unique response or optimization parameter, and in case this does not work we should make an attempt with a general response. Since extraction refers to processes of separating phases, they are defined by several parameters-technologically, thermodynamically, economically, statistically, etc. Important and essential properties of the separation process are degree of separation of the required component, economy per finished product and quality of product. Growth of any of these parameters brings about a fall in others. 

For the establishment of the realistic limit, one has to take account of the rates of processes in which mass, heat, momentum, and chemical energy are transferred. In this so-called finite-time, finite-size thermodynamics, it is usually possible to establish optimal conditions for operating the process, namely, with a minimum, but nonzero, entropy generation and loss of work. Such optima seem to be characterized by a universal principle equiparti-tioning of the process s driving forces in time and space. The optima may eventually be shifted by including economic and environmental parameters such as fixed and variable costs and emissions. For this aspect, we refer to Chapter 13. 

From the "physico-economic" standpoint convergence of the chosen method can be explained by the fact that it naturally represents the tendency of an open system with fixed conditions of interaction with the environment to equilibrium, which corresponds to minimum production of both physical and economic entropy. Optimization for the obtained "technico-economic mechanism" determines flow distribution corresponding to the minimum energy consumption, i.e., a physical mechanism. Thus, in this case the model of equilibrium thermodynamics—MEIS solves the problem of self-organization, ordering of the "physico-economic" system that is referred as a rule to the area of applications of nonequilibrium thermodynamics or synergetics. 

The need for novel catalytic processes is clear and, as discussed in Chapter 9, combining catalytic steps into cascade processes, thus obviating the need for isolation of intermediate products, results in a further optimization of both the economics and the environmental footprint of the process. In vivo this amounts to metabolic pathway engineering [20] of the host microorganism (see Chapter 8) and in vitro it constitutes a combination of chemo- and/or biocatalytic steps in series and is referred to as cascade catalysis (see Chapter 9). Metabolic engineering involves, by necessity, renewable raw materials and is a vital component of the future development of renewable feedstocks for fuels and chemicals. 

Reference Benzene reduction in motor gasoline—obligation or opportunity , Hydrocarbon Processing Process Optimization Conference, April 1997. Improve BTX processing economics, Hydrocarbon Processing, March 1998. 

Land use is a geographical concept that refers to the ways in which parcels of land are utilized by people and society. Land-use planning is an activity that examines the factors that influence the nature and dynamics of land usage and develops ways to optimize those variables to achieve larger social, economic, and ecological benefits. 

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