Balancing between risk and profit in refinery hydrogen networks: A Worst-Case Conditional Value-at-Risk approach

The optimization of refinery hydrogen systems has become a significant issue with the tendency of heavier crude oils and stricter environmental regulations. The fluctuations in the concentration of hydrogen is a considerable problem that can affect the quality of refinery products and increase operating costs. The hydrogen deficit caused by concentration fluctuation is eliminated by excess supply of hydrogen utility in reality. More hydrogen utility consumption leads to lower product quality risk and higher operating cost. Therefore, it is necessary to strike a balance between risk and cost. To solve this problem, the Worst Case Conditional Value-at-Risk (WCVaR) concept is applied to represent the minimum value of total pure hydrogen flowrate in hydrogen networks. The robustness of hydrogen supply is enhanced by maximizing of WCVaR associated with uncertainty distribution. Both adjustable and non-adjustable cases for hydrogen production are considered. The robustness of the obtained network structure is verified by Monte Carlo simulation. The results of this work indicate that optimizing WCVaR can improve the network robustness. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.