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Coal fly ash (CFA), an industrial by-product of high-temperature combustion of coal in coal-fired power plants, is one of the most complex and largest amounts of industrial solid wastes generated in China. It is widely recognized that CFA should be considered as a potential alumina resource to substitute bauxite. In this review, the features of high-alumina fly ash and aluminum recovery technologies are first described. Later, the merits and drawbacks of alumina extraction technologies in recovering more valuable materials are compared in terms of extraction mechanisms and equipment requirements. It is shown that "predesilicating-sodium carbonate (Na2CO3) activation-acid leaching" is currently a promising method in achieving multimetal synergistic extraction. Finally, the hydrochloric acid and sulfuric acid combination process is proposed as a sustainable development of the predesilicating-Na2CO3 activation-acid leaching process. The findings of this review provide theoretical guidance for novel developments and applications of aluminum extraction technologies. [ABSTRACT FROM AUTHOR]

The separation of ternary nonideal systems with multi‐azeotrope is very important because they are often found in the waste of chemical and pharmaceutical industries, which is much more difficult due to the formation of multi‐azeotrope and distillation boundary. We propose a systematic procedure for design and control of a triple‐column pressure‐swing distillation for separating ternary systems with three binary minimum azeotropes. This procedure involves thermodynamic insights, a two‐step optimization method, and effective control strategy. The separation of tetrahydrofuran (THF)/ethanol/water is used to illustrate the capability of the proposed procedure. It is found that the pressure limits in columns can be determined through the analysis of residue curve maps, distillation boundary, and isovolatility curves. The optimal triple‐column pressure‐swing distillation is generated with the minimum total annual cost (TAC) of $2.181 × 106 in sequence A. The operating conditions are well controlled approaching their desired specifications in an acceptable time when disturbances occur. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1281–1293, 2019 [ABSTRACT FROM AUTHOR]

In an effort to reduce costs, a systematic optimization approach is proposed to address the energy consumption of dividing-wall columns (DWCs). This iterative optimization procedure begins by minimizing the overall heat duty using an innovative objective function within a constrained design space. A sensitivity analysis is then carried out on the manipulated variables to obtain their optimal ranges. Optimal operating parameters are obtained through the evaluation of the total annualized cost (TAC). For the separation process of benzene/toluene/ o-xylene, the optimal DWC flow sheet exhibits a significant decrease in TAC when compared to conventional flow sheet optimum designs. The applied optimization method and sensitivity analysis have proven to produce results at the global optimum. This method is both practical and easily applied to other systems, even to systems with more than three components. [ABSTRACT FROM AUTHOR]

A multicriteria decision-making methodology for the sustainability prioritization of industrial systems is proposed. The methodology incorporates a fuzzy Analytic Hierarchy Process method that allows the users to assess the soft criteria using linguistic terms. A fuzzy Analytic Network Process method is used to calculate the weights of each criterion, which can tackle the interdependencies and interactions among the criteria. The Preference Ranking Organization Method for Enrichment Evaluation approach is used to prioritize the sustainability sequence of the alternative systems. Moreover, a sensitivity analysis method was developed to investigate the most critical and sensitive criteria. The developed methodology was illustrated by a case study to rank the sustainability of five alternative hydrogen production technologies. The advantages of the developed methodology over the previous approaches were demonstrated by comparing the results determined by the proposed framework with those determined using the pervious approaches. [ABSTRACT FROM AUTHOR]

Extractive distillation is one of the most attractive approaches for separating azeotropic mixtures. Few contributions have been reported to design an extractive distillation for separating maximum-boiling azeotropes and no systematic approaches for entrainer screening have been presented. A systematic approach to design of two-column extractive distillation for separating azeotropes with heavy entrainers has been proposed. A thermodynamic feasibility analysis for azeotropes with potential heavy entrainers was first conducted. Then, five important properties are selected for entrainer evaluation. Fuzzy logic and develop membership functions to calculate attribute values of selected properties have been used. An overall indicator for entrainer evaluation is proposed and a ranking list is generated. Finally, the top five entrainers from the ranking list have been selected and use process optimization techniques to further evaluate selected entrainers and generate an optimal design. The capability of the proposed method is illustrated using the separation of acetone-chloroform azeotropes with five potential entrainers. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3898-3910, 2015 [ABSTRACT FROM AUTHOR]

The Martin-Hou (MH) equation is a widely used equation of state in chemical engineering, mechanical engineering, and refrigeration technology design. It has pronounced advantages in calculations of liquid volume and enthalpy-entropy of high pressure gases and polar liquids. However, the determination of parameter B4 of the MH equation by using the conventional method is very time- and computation-consuming, which significantly restricts the application of the MH equation in engineering calculations. This article proposes an empirical equation to conveniently calculate B4 at different temperatures according to B4(0.7) (B4 at reduced temperature = 0.7). The accuracy of the MH equation to calculate volume of pure liquids by using the proposed equation was verified by comparing tcalculated data with literature data. The proposed equation can remarkably decrease the time to determine parameter B4, which would boost the application of the MH equation in engineering calculations. [ABSTRACT FROM AUTHOR]

Abstract: Isobaric vapor–liquid equilibrium (VLE) data for water+n-propanol+n-butanol ternary system have been extensively measured at 99.2kPa using a recirculating still. The experimental data were then correlated using the extended UNIQUAC model, in which the binary interaction energy parameters between the three components were obtained through a simplex fitting method. The results showed that the calculated data by the extended UNIQUAC model using the same interaction energy parameters agree well with both the experimental data and the literature data. It demonstrated that the experimental data are very consistent with the literature data; and the extended UNIQUAC model is reliable to predict the VLE of the ternary system using the obtained interaction energy parameters. [ABSTRACT FROM AUTHOR]

Abstract The design of the diethyl carbonate (DEC) production process has received much attention due to its key role as the oxygenated gasoline additive with much fewer environmental and health issues than methyl tert -butyl ether. In this study, two configurations including vapor recompression heat pump (VRHP)-reactive dividing wall column (RDWC) with or without the splitting top stream are investigated for DEC production to screen out the best VRHP sequence. Furthermore, a novel alternative approach of different pressure thermally coupled-RDWC (DPTC-RDWC) is comparatively proposed to achieve less capital and energy cost. The effects of pressure within stripping section of the RDWC on total annualized cost (TAC) and the temperature difference between the condenser and reboiler are studied. The results illustrate that the proposed optimum process produces DEC production with the purity of 99.8 mol% and significant reduction of TAC is achieved by 20.52% with 10 years payback period. Apart from that, carbon dioxide emission of the process is decreased by 33.74% compared to that through conventional RDWC. Highlights • VRHP-RDWC with or without a splitting top stream is explored for DEC synthesis. • A novel DPTC-RDWC is proposed to achieve the less capital and energy cost. • TAC of the proposed DPTC-RDWC is reduced by 20.52% compared to the RDWC process. • CO 2 emissions of the proposed DPTC-RDWC are reduced by 33.74% compared to the RDWC. [ABSTRACT FROM AUTHOR]

An intensified scheme for the separation of ternary azeotropic system is explored to reduce the energy consumption and recycle important organic solvents. Herein, a novel double-thermally coupled ternary extractive distillation (DTCTED) for separating azeotropic system benzene/toluene/cyclohexane (denoted as B/T/CH) is proposed to achieve energy-saving and emissions reduction. Thermodynamic feasible insights of the B/T/CH using dimethyl formamide as entrainer are firstly analyzed via residue curve maps to find separation constraints. Following that, the proposed intensified scheme is optimized via the in-house multi-objective genetic algorithm software while using total annual cost and CO 2 emissions as objective functions. The results show that the total annual cost and CO 2 emissions of the proposed intensified DTCTED scheme are significantly reduced by 18.60% and 20.22% compared with the existing single-thermally coupled ternary extractive distillation process. Furthermore, exergy loss and relative volatility are introduced to explore the essence of energy-saving in the proposed DTCTED scheme. • An intensified double-thermally coupled ternary extractive distillation is proposed. • The proposed scheme is optimized based on the multi-objective genetic algorithm. • Proposed scheme can save 18.60% and 20.22% of total annual cost and CO 2 emissions. • Essence of the energy-saving is explored by exergy loss and relative volatility. [ABSTRACT FROM AUTHOR]