Research On Functional Safety Management Of Safety Instrumented System In Key Parts Of Coal Direct Liquefaction Process

In order to solve the increasingly tense problem of China’s petroleum resources,China began the researches on coal-to-liquid technology and regarded it as an important direction for national energy development strategies.Because of the large number of flammable,explosive,toxic and highly corrosive substances involved in the coal-to-liquids process and the strict process condition,which makes coal-to-liquids enterprises face great safety problems.With the improvement of automation,safety instrumented systems have been introduced into the coalto-liquids industry to reduce the probability of accidents,to protect the safety of personnel,to avoid environmental pollution and to reduce economic losses.However,the short development time and the insufficient risk analysis of coal-to-liquids technology in China,which leads to the lack of safety instrumented system in design and management.In this paper,based on the ‘Shenhua Ordos Coal-to-Oil Branch SIL evaluation engineering project’,the functional safety management research on coal direct liquefaction equipment is carried out from three aspects: hazard analysis,functional safety assessment and safety requirements specification.In the hazard analysis,the HAZOP analysis method is used to divide the coal direct liquefaction process into 12 process nodes for initial risk assessment.Through the comparison with the common petroleum refining process,the unique hazardous scenarios of the coal direct liquefaction process are analyzed.The safety instrumented function distribution is carried out in the high-risk scenarios,and the safety instrumented functions of40 key process points are obtained.Safety integrity level grading of designed safety instrumented functions are performed by LOPA analysis.In the safety instrumented function loop design part,the ex SILentia software is used to complete PFDavg and STR calculation under different redundant structures and different proof test interval.Then the optimal loop matching of SIF is determined under the three constraints of PFDSIF,enterprise maintenance cycle and SIS safety benefit.In the extended analysis,through the analysis of total cost,PFDavg,safety benefit and risk reduction capability,it can be obtained that improving the on-site subsystem is more meaningful to improve the SIS performance.Finally,based on hazard analysis and safety instrumented function loop design,the contents of the safety requirements specification are described and safety function requirements cards are generated.