Comprehensive Risk And Emergency Response Analysis Of The MTBE Unit By HAZOP/LOPA/FTA Methods

Risk identification and control is of vital importance for chemical process safety management.As with a MTBE unit newly-built by a petrochemical company,the unit plan and process flow were completely different from that of the original unit.Also,the process materials included the following flammables and explosives such as C₄,methanol and MTBE.Therefore,it was very critical to perform risk analysis and put forward optimizing recommendation as per analysis result.After comparative analysis to several safety analysis methodologies that are widely applied in the industry,a comprehensive analysis system in combining HAZOP,LOPA with FTA was employed to carry out risk assessment for MTBE unit.Tanks regarding C₄,methanol and MTBE were considered as analytical target for HAZOP study,with specific reference to risk matrix,the consequence with relatively higher severity would be listed,while the rational recommendations would be provided accordingly.Meanwhile,LOPA study was utilized as well to verify the reliability of all recommendations,determine if the failure frequency could be actually reduced,and avoid overprotection.The above analysis result showed that the recommendation in this paper could effectively reduce failure frequency of the tanks and achieve the objective of being in safe and controllable state.With the use of FTA,the explosion of tanks regarding C₄,methanol and MTBE was considered as top event.The logic relationship between intermediate event and basic event could be depicted with‘and gate’and‘or gate’.According to FTA result,the rational recommendations could be made in terms of routine safety production and maintenance activity management.For emergency response,taking C₄ feed tank as an example,the diffusion status after leak was simulated with FLACS software.The diffusion extent and concentration change curve at monitoring point could be applied for the purpose of defining accident influencing scope,determining the significantly-affected area,strengthening the prevention and control,revising the integrated emergency response plan in a timely way,improving the efficiency of emergency response,and reducing casualties of personnel.