Exploiting Tube Inserts to Intensify Heat Transfer for the Retrofit of Heat Exchanger Networks Considering Fouling Mitigation

Abstract

Recent studies on heat-transfer intensification have shown that the use of tube inserts is an effective way of enhancing heat transfer while mitigating fouling deposition in shell-and-tube exchangers. Thus, this intensification technique has been used for the retrofit of heat exchanger networks (HENs) in the process industry. Unlike most existing research assuming constant fouling resistance in HEN retrofit procedures, this article presents a novel optimization method to address fouling effects for HEN retrofit problems. In the new approach, tube inserts (tube-side intensification) can be implemented to increase the heat-transfer coefficients of intensified exchangers, and an actual detailed tube-side fouling model is applied to calculate the tube-side fouling resistance in each heat exchanger. However, this usually leads to very large complex computational problems because of the combination of the HEN retrofit model and the exchanger fouling model. To reduce the resulting nonlinear computational difficulties, the optimization procedures proposed by Pan et al. (Comput. Chem. Eng.201242263276; 10.1016/j.applthermaleng. 2012.04.038Appl. Therm. Eng.) were developed and updated based on retrofit scenarios. In a case study, the retrofit of a practical industrial process was studied to demonstrate the validity and soundness of the proposed approach, showing that the benefit derived from implementing tube inserts is not only increased heat recovery but also prolonged exchanger operating times through the mitigation of fouling deposition.

Heat transfer intensification for retrofitting heat exchanger networks with considering exchanger detailed performances

“…Some iteration approaches have been proposed by Pan et al to solve the HEN retrofit problems in certain situations, such as implementation of heat transfer intensification, network topology modification, and fouling and pressure drop restrictions . In this work, the reported iteration approaches are developed to address more complex HEN retrofit scenarios, which include temperature dependence of stream CPs, stream and exchanger geometry dependence of heat‐transfer coefficients and pressure drops, and LMTD correction factor ( F T ) associated with multiple tube passes and shell passes.…”

“…Nguyen et al presented a new MILP method for HEN synthesis and retrofit, which can easily provide suboptimal solutions by identifying intermediate feasible solutions or excluding the current optimal solution . Pan et al proposed a novel iterative MILP‐based method for HEN retrofit with heat transfer intensification . Their automated design method was proposed to systematically consider heat transfer enhancement for retrofitting HENs.…”

Dynamic Optimization of the Flow Rate Distribution in Heat Exchanger Networks for Fouling Mitigation

“…, , (16) where SCC is the subset of countercurrent heat exchangers and SMP is the subset of multipass heat exchangers (HE = SCC ∪ SMP).…”

Recent developments in Process Integration

“…Pan et al (2011) studied the improvement of energy recovery within HENs using intensified tube-side heat transfer. Pan et al (2012) presented a MILP based iterative method for the retrofit of HENs with intensified heat transfer and most recently Pan et al (2013)-optimisation for the retrofit of large scale HENs with different intensified heattransfers. Heat transfer can be intensified in shell-and-tube heat exchangers for improved heat transfer performance.…”