Research On Operational Risk Assessment Technology Of Sulfur Recovery Unit In Natural Gas Purification Plant

The petrochemical industry has witnessed a growth in the construction of sulfur recovery units as to deal with the increasing amount of natural gas containing sulfur. As a result, whether the sulfur recovery unit functions in a safe, stable and excellent state directly affects the environmental protection and economic benefits of the whole purification plant, thus ensuring its safe operation is becoming more and more important. Though faults occurred in the operation of sulfur recovery unit, may not cause fires and explosions, if not handled properly and promptly, can be evolved into a serious accident. Taking into account of these factors, this thesis applies the concept of operational risk assessment to the sulfur recovery unit, which can ensure the safe operation of sulfur recovery unit by setting the time back to the point before accidents happen.Firstly, according to the analysis of purification plant sulfur recovery process and fault modes, four kinds of faults are obtained, respectively for excessive exhaust emissions, substandard quality of sulfur, emergent shutdown and potential safety hazards lied within the process. Besides, the fault tree analysis was used to identify the risk factors of the 4 typical fault types, which in turn, helps the establishment of the evaluation index system considering the operation conditions.Secondly, determined the attribute space matrix and performedthe ordered segmentation. Based on the calculated attribute measure and the confidence criterion, the fault pattern as well as the probability level of each fault occurrence is identified and obtained separately. In addition, in order to overcome the one-sided nature of the single-weighting method, weights of ANP method considering objective weighting method and the subjective weighting method are used to optimize the results.On the basis of analyzing and summarizing the fault types, the severity index system for the operation of the sulfur recovery unit is formed, what's more, the triangle whitening weight function based on the center point is used to analyze the consequence, as a result, the severity grade of the consequences of the 4 types of faults are obtained.Finally, by assessing the sulfur recovery unit in a natural gas purification plant in Sichuan province, the practicality of risk assessment method was affirmed. It turns out the evaluation results accord with the current status of sulfur recovery unit.In an effort to reduce the risk level of sulfur recovery unit, this thesis studied the risk control method of sulfur recovery unit in natural gas purification plant. Focused on technical means, human factors and management level of risk control methods,this thesis puts forward specific measures to alleviate the risk so as to ensure the safe operation of sulfur recovery.