Practical Approach to Exergy and Thermoeconomic Analyses of Industrial Processes

Abstract

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Exergetic and Economic Assessment of Distillation Hybrid Configurations for Bioethanol Refining

“…The hybrid units were simulated as follows: The simulated THIDC column was replicated in a new Aspen Plus® simulation environment and a third component entrainer (ethylene-glycol) was added in the components list specified for the system. The choice of this entrainer was based on its low cost, good capacity and selectivity [21]. THIDC rectification distillate (67.9 kmol/h containing 95.5 wt% ethanol) was connected as the feed stream to extractive columns of configurations 1 and 3 (Figuren1 and 3.…”

Off-Design Modeling of Natural Gas Combined Cycle Power Plants: An Order Reduction by Means of Thermoeconomic Input–Output Analysis

“…Exergy can be defined as "the amount of useful work extractable from a generic system when it is brought to equilibrium with its reference environment through a series of reversible processes in which the system can only interact with such environment" [12]. All the exergy flows can be classified according to their economic purpose, through the so-called Resource-Product-Losses (RPL) criterion [22]: this practice allows the analyst to distinguish among productive components, whose main purpose is to generate a useful product, and dissipative components, that do not generate any final product, but are responsible for disposing of the residues created during production (condensers, filters, scrubbers, stacks, etc. ).…”

“…Apart from the specific exergy cost of plant products, the standard exergy cost evaluation formalized here leads to the definition of a set of parameters which allow the so-called iterative design evaluation and optimization process, as described by [17,19,22]:…”

“…In the most general case, a number of exogenous or endogenous parameters can be considered. Assuming a number of possible values for each ith parameter, a total number of plant simulations must be performed according to relation Equation (11), Apart from the specific exergy cost of plant products, the standard exergy cost evaluation formalized here leads to the definition of a set of parameters which allow the so-called iterative design evaluation and optimization process, as described by [17,19,22]:…”

“…Both the on-and off-design model computed temperature, pressure and mass flow rate of each stream at different operating conditions. From such values, the related exergy rates are derived according to literature [12,22,28], and exergy balances for each plant component are derived according to relation Equation (1). The fundamental matrices and vectors presented in Figure 1 are then derived for each on-and off-design configuration of the system, as described in Subsection 2.1.…”