[en] Graphical abstract: Efficient scheduling of hydrogen pipeline network operation. - Highlights: • An MPEC strategy is presented for efficient scheduling of hydrogen network. • Detailed pipeline model is incorporated into the hydrogen scheduling model. • Both pressure and concentration of demand points are calculated by dynamic model. • Segmented pricing strategy is adopted for the hydrogen producing. - Abstract: Hydrogen pipeline network operation is important for balancing the hydrogen producing and consuming unit onsite. To make the operation efficient and stable, this article presents a mathematical program which incorporates equilibrium constraints (MPECs) for scheduling of hydrogen pipeline network between hydrogen producing and consuming units within a refinery. The developed model not only handles the multi-component and non-ideal nature of the hydrogen pipeline network, but also allows flow reversals and flow transitions inside the pipeline. A real refinery case study shows that the optimal schedule of pipeline storage could stabilize the hydrogen production, which improves the efficiency of the system. Operating safety is also ensured by the pressure constraints

[en] Highlights: • Complementary formulations are introduced to scheduling model of fuel gas system. • Physical constraints of the pipes are covered by incorporating detailed pipe model. • Dynamic multi-component feature of fuel gas system is considered in the model. • Both the heat value and pressure of demand points are calculated by dynamic model. • More practical and preferable result is obtained by applying the proposed method. - Abstract: The production of regular clean fuels is faced with a problem of declining profit under more strict and costly environmental regulations. To satisfy the desire for higher profit and the firm requirements of environmental protection, it is imperative to improve the efficiency of energy systems within refineries. Over the past decade numerous attempts were made to enhance the energy system, addressing the steam power system and hydrogen system in particular. However, the fuel gas system, which serves as the dominant energy source of refineries, has drawn little attention in the research community. Industrial practices indicate that the energy efficiency of the fuel gas systems can be improved remarkably by optimizing the operation schedules. This paper presents a multi-period optimizing model for the scheduling of fuel gas system within refineries. Modeling of the pipeline system is considered important, which was usually ignored in the former studies. Flow reversal and flow transition in the pipe segments are taken into consideration. Pipelines with branching structure and loop structure can be easily modeled and solved with rational computation effort. Complementarity formulations are utilized in modeling of discrete decisions instead of the commonly used binary variables. Application of this method is illustrated with a case study

[en] Highlights: • A new transshipment type model for inter-plant heat exchanger network is proposed. • New constraints are used to identify three inter-plant heat integration schemes. • A model with linear constraints is developed, allowing non-isothermal mixing. • Better results with lower total annual cost can be obtained by the proposed model.