HAZOP analysis based on sensitivity evaluation

Hazard and operability (HAZOP) analysis approach based on sensitivity evaluation is presented in this paper to ensure production safety in complex and large-scale chemical plants. In this approach, the sensitivity evaluation is introduced into HAZOP deviation analysis to measure the effect degree caused by each cause on the corresponding deviation. A quantitative sensitivity evaluation model of deviation cause is first established, in which the departure degree, time duration to reach the maximum deviation, and stability degree of the target process variable are determined as evaluation factors. The sensitivity evaluation of each deviation cause is performed based on the dynamic process simulation. The multiple deviation causes that correspond to the deviation are ranked based on sensitivity index, thereby identifying the significant effect causes on deviation from multiple causes; this identification will assist plant operators and safety management staff on their on-line process monitoring and fault diagnosis. Finally, the proposed approach is applied to the depropanization unit in a gas fractionation plant. The sensitivity evaluation was carried out for 10 deviation causes that correspond to the deviation “higher overhead pressure”, in which three and seven sensitive and non-sensitive causes were identified, respectively. The result of the case study demonstrates that the proposed approach can improve the readability and guidance of conventional HAZOP report, which is consistent with the actual production conditions.