Synthesis of refinery hydrogen network integrated with hydrogen turbines for power recovery

Hydrogen compressors are widely utilized to raise the pressure of hydrogen-rich streams in refineries to satisfy the operating pressure requirements of various hydrogenation units. Pressure relief valves are also placed to reduce the pressure of the hydrogen streams but this leads to a waste of energy. Alternatively, hydrogen turbines may be used in place of pressure relief valves to recover energy. This paper proposes a novel superstructure of a refinery hydrogen network involving hydrogen turbines to recover the expansion work. Such a configuration can be termed a hydrogen/work exchange network. Sequential mathematical models are developed with objective functions including the minimization of the flowrate of hydrogen utility, compression work, total power consumption and total annualized cost. A modified literature case study with five scenarios is solved. Results show that the total power consumption and the total annualized cost can be further reduced by 3.9% and 0.6% by recovering the expansion work of hydrogen-rich streams using hydrogen turbines.