Ming Pan

Novel MILP-based iterative method for the retrofit of heat exchanger networks with intensified heat transfer

Abstract Heat transfer intensification is an effective technique for improving energy recovery in heat exchanger networks (HEN) by enhancing heat transfer without any network topology modifications. In this paper, a novel optimization method has been developed for the synthesis of intensified heat exchanger networks with a simple mixed integer linear programming (MILP) model under retrofit scenario, and a robust solution strategy based on two iteration loops has been proposed. The new method has distinctive advantages over existing design methods, as the new MILP model can effectively and significantly reduce computational difficulties associated with nonlinear formulation in existing HEN retrofit formulations. Three cases have been tested to demonstrate the validity and efficiency of the proposed approach, which requires very short computational times to obtain optimal solutions when energy saving or profit is to be maximised through retrofit.

Novel optimization method for retrofitting heat exchanger networks with intensified heat transfer

Abstract Enhancing heat transfer in an existing heat exchanger has received great attentions from process industries recently, as its implementation in heat exchanger networks is relatively simple, which only require very minor structural modifications in heat exchangers without modifying basic configuration of exchanger networks. In this study, a novel optimization approach is proposed for the retrofitting of heat exchanger networks with intensified heat transfer. The optimization framework has been developed to systematically identify the most appropriate location for the introduction of heat transfer enhancement and its optimal level in the retrofit scenarios. Iterative optimization of a simple MILP-based model has been proposed to deal with computational difficulties associated with non-linear terms in the optimization more effectively. A case study based on a literature example [1] has been carried out to demonstrate the validity and soundness of the proposed approach.

Improving energy recovery in heat exchanger network with intensified tube-side heat transfer

Implementing tube-inserts, namely tube-side enhancement, is an efficient way to increase the heat transfer coefficients of shell and tube heat exchangers, which can achieve substantial energy saving in heat exchanger network (HEN) if suitable retrofit strategies are used (Pan et al., 2011). In this paper, a new optimization method is proposed to consider more details of tube-side enhancement for HEN retrofitting, such as multiple tube passes, logarithmic mean temperature difference (LMTD), LMTD correction factor (FT). Even though LMTD and FT will lead to complex nonlinear terms in mathematical programming, the proposed approach can deal with the relevant computational difficulties efficiently. The validity of new optimization approach is illustrated with solving a literature example (Li and Chang, 2010). Copyright ? 2011, AIDIC Servizi S.r.l.

Modeling and Optimization for Scheduling of Chemical Batch Processes

Chemical batch processes have become significant in chemical manufacturing. In these processes, large numbers of chemical products are produced to satisfy human demands in daily life. Recently, economy globalization has resulted in growing worldwide competitions in traditional chemical process industry. In order to keep competitive in the global marketplace, each company must optimize its production management and set up a reactive system for market fluctuation. Scheduling is the core of production management in chemical processes. The goal of this paper is to review the recent developments in this challenging area. Classifications of batch scheduling problems and optimization methods are introduced. A comparison of six typical models is shown in a general benchmark example from the literature. Finally, challenges and applications in future research are discussed.

Novel MILP-based optimization method for retrofitting heat exchanger networks

Abstract This paper presents a novel optimization method for retrofitting heat exchanger networks (HENs). The optimization framework is developed based on the iterative optimization of a relatively simple mixed integer linear programming (MILP), which can effectively deal with the computational difficulties associated with nonlinearity, and facilitate the automated design of HEN retrofit with rigorous consideration of economic trade-off. A case study based on literature example has been carried out to demonstrate the validity and soundness of the proposed approach.

Retrofit Procedure for Intensifying Heat Transfer in Heat Exchanger Networks prone to Fouling Deposition

This paper presents a novel optimization method of addressing fouling effects in heat exchanger network (HEN) retrofit with intensified heat transfer. In the new approach, the fouling deposition in each heat exchanger is taken into account when heat transfer intensification is regarded as a retrofit option in HENs, and the optimization procedure proposed by Pan et al. (2012b) is developed to solve the addressed problems efficiently. A practical industrial process is carried out to show that with the consideration of fouling influence. The benefit that can be derived from implementing intensified technologies is not only increasing heat recovery but also extending exchanger operating times with the mitigation of fouling deposition.

Heat Transfer Intensified Techniques for Retrofitting Heat Exchanger Networks in Practical Implementation

This paper addresses the implementation of heat transfer intensified techniques in practical heat exchanger networks (HENs). The issues considered in this paper not previously addressed include heat transfer intensification, changes in multiple tube passes and shell passes and temperature dependence of stream heat capacity (CP). These must be formulated into a new complex nonlinear model not reported previously in the existing literature. To solve such retrofit problems, an MILP-based iterative method has developed based on the work proposed by Pan et al. (2012a). A large scale example is presented to demonstrate the validity and efficiency of the proposed approach.

Novel MILP-based optimization method for heat exchanger network retrofit considering stream splitting

Abstract This paper presents a novel optimization method for heat exchanger network (HEN) retrofit including stream splitting. A simple mixed integer linear programming (MILP) model and two iterative loops have been developed to effectively deal with the nonlinear computational difficulties associated with logarithmic mean temperature difference (LMTD) and retrofit costs for HEN retrofit problems. In case study, comparison with the existing methods illustrates the validity of the proposed approach.

Intensifying heat transfer for retrofitting heat exchanger networks with topology modifications

Abstract This paper presents a novel MILP-based iteration method for intensifying heat transfer to improve energy recovery in heat exchange networks (HENs) with topology modifications. A new optimization framework has been proposed to deal with the nonlinear computational difficulties due to the combination of conventional HEN retrofit (topology modifications) with heat transfer intensification. An industrial scale case study is carried out to demonstrate the validity and soundness of the proposed approach.

Control Scheme of Novel Pressurized Stripper and the Industrial Implementation

A novel pressurized stripper with side-draw has been implemented successfully in coal-gasification industry and oil-refining industry. In this complex stripping process, ammonia and sour gas can be removed effectively from wastewater with ammonia and sour gas. However, compared to simple strippers, the complex pressurized strippers have rarely been considered for dynamic optimization before. In this paper, the dynamic simulation and optimal control of the novel stripper are proposed to improve the overall cost-effectiveness of the whole process. First of all, sensitivity analysis is proposed to find the sensitive plates in stripper with steady state simulation. Based on the sensitivity analysis, two control schemes are built up. And then, the rejecting disturbance capabilities of the two control schemes are compared and testified by using dynamic simulation. Finally, the optimal control scheme is implemented in industry with distributed control system (DCS). A real industrial application demonstrates that relies on the installed control system, the new stripping process can run steadily, consume less energy and satisfy the product quality requirements even though an uncertain disturbance occurs.