Optimal design of distillation column using three dimensional exergy analysis curves

This paper presents two main contributions. Firstly, a new exergy graphical method is proposed for optimaldesign of distillationcolumn with minimum exergy lost. The method is applicable to both grass-root and retrofit cases, respectively. The effect of design and operating parameters of a distillationcolumn on the exergy lost is graphically visualized by threedimensionalexergyanalysiscurves. The curve shows the correlations between exergy lost, design and operating parameters of a distillationcolumn. This technique can be used as an effective method to reduce the simulation effort to search for the optimum design and operating parameters of a distillationcolumn at minimum exergy lost. Besides, visualization also enhances the engineers’ understanding of the column performance. The other contribution is a four-level idealization concept, which is based on threedimensional graphical exergyanalysiscurves. The concept defines the effect of transport rate and configuration on exergy lost of distillationcolumn. The effectiveness of the method has been demonstrated on a xylene column, which suggested that an implementation of feed pre-heater yields a significant reduction in exergy lost by up to 15.5%

Application of an environmentally optimum cooling water system design to water and energy conservation

Recirculating cooling water systems are consist of a cooling tower and heat-exchanger network which conventionally have a parallel configuration. However, reuse of water between different cooling duties enables cooling water networks to be designed with series arrangements. This will result in performance improvement and increased cooling tower capacity. Research on recirculating cooling water systems has mostly focused on the individual components. However, a particular design method represented by Kim and Smith accounts for the whole system interactions. In this study, the Kim and Smith design method is expanded and a comprehensive simulation model of recirculating cooling system was developed to account for the interaction between the cooling tower performance and the heat-exchanger network configuration. Regarding this model and considering cycle water quality through introducing ozone treatment technology, a modern methodology of recirculating cooling water system design was established and developed. This technique, called the integrated ozone treatment cooling system design, is a superior designed tool based on pinch analysis and mathematical programing. It also ensures maximum water and energy conservation, minimum cost and environmental impacts. Related coding in MATLAB version 7.3 was used for the illustrative example to get optimal values in cooling water design method computations. The result of the recently introduced design methodology was compared with the Kim and Smith design method

New Method for Designing an Optimum Distributed Cooling System for Effluent Thermal Treatment

Temperature restrictions on aqueous effluents dictate that streams with a temperature higher than the permitted level needed to pass through cooling systems to reduce the effluent temperature before discharge. In this study, by considering the grouping design rules based on pinch technology, an optimum design for a distributed effluent cooling system, has been developed. A counter-flow wet cooling tower, with a mechanical air draft, is also assumed as an effluent thermal treatment facility in predicting the exit water and air conditions of the tower in the system. In this new design method, an optimum inlet flow rate to cooling tower has been achieved by exploring the feasible region. Also, the evaporation loss effect, flexible design variables, and physical properties have been incorporated in targeting the optimal conditions for the cooling tower. A case study is presented to illustrate the design methodology and the optimization model of cooling systems