Simultaneous optimization approach for integrated water-allocation and heat-exchange networks

A simultaneous optimization approach for the design of wastewater and heat exchange networks based on cost estimation

Synthesis of heat exchanger network considering pressure drop and layout of equipment exchanging heat

Optimal design for heat-integrated water-using and wastewater treatment networks

On-line cleaning of heat exchangers operating in a heat exchanger network (HEN) is aimed at preventing unnecessary losses of energy that can be recovered in HEN. If time behaviour of fouling in each heat exchanger can be estimated on the basis of past experience, then the optimal schedule of cleaning interventions can be determined by maximizing the objective function expressing the economic value of avoidable reduction in the energy recovery [1]. The crucial assumption for the presented paper is that on-line measurements of the mass flow and inlet and outlet temperature are available for each process stream. That made possible to evaluate fouling-induced reduction in the recovered energy flow using neural network model of HEN based on the measurements. The neural network (NN) model of HEN was applied in diagnostics of deposits influence on heat recovery in HEN by taking into account the time behaviour of fouling approximated by NN. The application of a neural network to the evaluation of changes in the energy flow recovered in a HEN has been tested using a simulated heat exchanger network as a reference. The simulation of HEN (implemented in MATLAB software) was based on a dynamic HEN model employing heat exchanger decomposition into interconnected cells whose overall dynamic behaviour is described by an array of lumped-parameter models. Computational aspects of the approach outlined above were studied on the example of a HEN featuring 26 process streams and 31 heat exchangers, operating in a crude distillation unit of 440 t/h processing capacity. A diagnostics of deposits influence on heat recovery in HEN makes it possible to attain a saving of about 5% of recoverable energy with the annual value of about 0,86 million USD.

An extended superstructure modeling method for simultaneous synthesis of direct work exchanger networks

A derivative based method for cost optimal area allocation in heat exchanger networks

The petrochemical industry is an energy-intensive process. Heat exchanger network (HEN) is widely applied in existing petrochemical plants used to save energy. However, there is still some amount of low-grade heat wasted. No mathematical model can directly tackle the problems with majority of phase-changing process streams. Therefore, this study aims to optimise an extended low-grade heat recovery model for the petrochemical plant by integrating the organic Rankine cycle (ORC) with HEN. A mixed-integer nonlinear programming steady-state model was first developed. Then, the ORC operation conditions were optimised simultaneously. Finally, the thermodynamics (energy and exergy) and economic analysis were performed to evaluate the system performance, with 41 MW more heat recovered, 2.01% higher exergy efficiency and 3219 k$/year less total annual cost, compared with HEN only. Furthermore, the optimisation results indicate that the proposed energy system performs with 386 MW of recovered heat from the process streams, 82.13% of the overall exergy efficiency, 3.94 MW of net power generated from ORC, and 4416 k$/year of electricity profit. Research presented in this paper hopes to shed light on design and operation of the petrochemical industry for energy savings and cost reduction.

Simultaneous synthesis of a biogas process and heat exchanger network

Conservation of energy usage is essential in chemical process plants due to the expanded energy users and demands alongside the carry-on hike of energy prices. This study analyzed the performance of energy savings in a heat exchanger network (HEN). It is based on decreasing utility usage while increasing process-to-process heat exchange in HEN using a path combination approach at different heat recovery approach temperatures (HRATs). The approach generates different combined path options for heat shifting from utilities to exchangers in a HEN. In terms of cost targeting, the optimal HRAT in a HEN is determined for each path’s combination option. The study focused on the HEN of crude oil preheat trains. Shifting heat load between utilities implies adding and subtracting loads to and from exchangers in a HEN. Therefore, a minor retrofit to compensate for the heat transfer area is required for some HEN exchangers. The optimum HRAT corresponding to the lowest total cost was determined for each option and ranged between 8 °C and 14 °C. Moreover, two out of five options in HEN with low capital investment and a short payback period were found to be promising.

Systematic optimization methodology for heat exchanger network and simultaneous process design

The Evaluation of Combined Heat and Mass Exchanger Network Synthesis using Novel Stage-Wise Superstructure

Total annualized cost optimality properties of state space models for mass and heat exchanger networks

Incorporating Process Safety into Heat Exchanger Network Synthesis and Operation

Heat exchanger network optimisation considering different shell-side flow arrangements

Costs and environmental impacts multi-objective heat exchanger networks synthesis using a meta-heuristic approach