An exergy-based approach for hydrogen network integration

Increasingly strict environmental and product-quality regulations coupled with the change of crude oil to high-sulfur and heavier oil have increased refineries' hydrogen demand. Various HNI (hydrogen network integration) methods have been used to achieve efficient use of hydrogen by refineries, leading to reduced energy consumption and cost. However, to minimize the energy consumption of a hydrogen network, not only the hydrogen utility consumption but also the energy consumption of the whole network should be taken into account. In this paper, the superstructure and mathematical model for integration of a hydrogen network with purification are established, in which all purification processes are expressed by the same modular. The total exergy consumption is used as the objective function for optimization, which encompasses fresh hydrogen consumption, compression work and energy consumption of purification processes. The energy consumption of a purification process is expressed in terms of its minimum separation work. A case study is used to illustrate the exergy-based optimization approach. (C) 2015 Elsevier Ltd. All rights reserved.