Effect of the purified concentration changes on the consumption of fresh hydrogen and the flowrate of the purified stream in hydrogen networks

Abstract

The need to produce cleaner fuels under the constraints of stricter environmental regulations, heavier and sour crude oils, and petroleum market needs has resulted in increased hydrogen demand in oil refineries. These demands are usually served by hydrogen networks, which collect hydrogen-containing streams from refinery processes and, after potential processing, redistribute the hydrogen content to recipient processes within the same site. Often, pure hydrogen is also necessary in order to satisfy the final demand. The introduction of one or more purification units into a hydrogen network is an economical way to reduce fresh hydrogen consumption. In the design and optimization of a hydrogen system, it is often important to find the target values (optimal lower bounds) for the fresh hydrogen consumption and the flowrate of the purified stream. However, the procedure for obtaining these targets becomes very complex when purification units are added, compared to that for a hydrogen network involving reuse only. This article presents a simple method for predicting the target values based on the balances of mass and flowrate and the features of the purification units. The proposed method not only can simplify the targeting procedure but can also provide valuable insights for the analysis and optimization of single-impurity hydrogen networks with purification units.