Thermodynamic Principle-Based Hydrogen Partial Pressure Correction for Optimization of Refinery Hydrogen Networks

Abstract

The cost of hydrogen consumption takes up a high percentage of the total crude oil refining cost. Fresh hydrogen and compression work are main operating cost to be minimized in hydrogen networks. In hydroprocessing reactions, hydrogen partial pressure is a key index to hydrogen demand and compression work. However, such a decisive factor is estimated by Dalton’s law which is not suitable to real gas especially in higher pressure case. To cope with such an issue, thermodynamic principles including the theorem of corresponding states and compressibility factor are employed to quantify hydrogen partial pressure accurately. Based on relative concentration and hydrogen partial pressure properties for hydrogen streams, this paper establishes a nonlinear programming (NLP) model for the minimization of total exergy including fresh hydrogen and compression work. Case studies show that hydrogen partial pressure calculated by Dolton’s law is larger than the requirement and thermodynamic principles are not only more accurate but are also able to save compression work.