Exergy analysis of eco-industrial systems reflects the thermodynamic characteristics of resource utilization by studying complicated material flow patterns to an industrial system. Different indicators based on exergy analysis are presented, such as system exergy depletion index, cycling ratio of material exergy, etc. which can be used to evaluate the efficiency of resource utilization and the environmental potential effect. The interrelations of these exergy indicators and their interpretation on industrial ecology are further discussed. Finally, the result of case study suggests effectiveness of exergy analysis methods and practicability of these exergy estimate indices.

A systematic methodology is presented for refinery modeling and optimization on the basis of much more detailed molecular information than is used in conventional lumped methods. The novelty of this work is that it incorporates models based on microscopic understanding into optimization to achieve macroscopic improvements. A molecular matrix based on a homologous series of hydrocarbon compounds is used to characterize refining streams. A transformation method is developed for obtaining molecular compositions from stream bulk properties. Molecular models are then built for several processes. Molecular modeling and optimization are finally integrated into an overall refinery optimization framework. Results show that molecular information can provide much better understanding and new insights into refining operation. Consequently optimization based on molecular modeling can greatly improve total profit while making quality products that satisfy environmental regulations.

A systematic methodology is presented for refinery modelling and optimisation on the basis of much more detail molecular information than conventional lumped methods. The novelty of this work is to incorporate models based on microscopic understanding into optimisation to achieve macroscopic im- provement. A molecular matrix based on homologous series of hydrocarbon compounds (B. Peng, Ph.D. Thesis, UMIST, 1999, pp. 22-41) is used to characterise refining streams. A transformation method is developed for obtaining molecular compositions from stream bulk properties. Molecular models are then built for several processes. Molecular modelling and optimisation are finally integrated into an overall refinery optimisation framework. Results show that molecular information can provide much better un-derstanding and new insights into refining operation. Consequently optimisation based on molecular modelling can greatly improve total profit while making quality products satisfying environmental regu-lations.

In this paper, a hierarchical optimization procedure for reaction path synthesis is presented in which the overall reaction is not necessarily desirable with respect to the thermodynamics or mechanism of reaction. According to the specified raw materials, desired product, and probable yproducts, the overall reactions are determined through the generation method of simple stoichiometric reactions and evaluated by economic potential and other criteria such as thermodynamic feasibility and kinetic desirability. For an overall reaction that is unachievable thermodynamically or kinetically while potentially desirable with respect to profit, a novel procedure for overall reaction decomposition by adding intermediate chemicals is proposed to realize it by several thermodynamically feasible division reactions. When this method is used, the optimal solution of reaction path synthesis can be either an overall reaction or several division reactions. A case study is described to illustrate the proposed procedure.

With more and more severe problems of environmental pollution, the chemical industry entails the consideration of minimum environmental impact when synthesizing reaction path. In this paper, a systematic method for reaction path synthesis is described in which undesirable chemicals are cycled to realize zero avoidable pollution. A novel concept of simple stoichiometric reactions (SSRs) is introduced to determine simple stoichiometries between raw materials, probable intermediate chemicals and co-products and to form a reaction path network. Promising reactions are identified by an optimization program from this network. Case studies are discussed to illustrate the proposed method.