Research And Application Of SIL Control System For Gas Station

Gas station as the hub of natural gas pipeline system is the key part to ensure the normal operation of the whole gas transmission system. Safety Integrity Level(SIL) as an important part of integrity management is one of the effective measures to ensure the gas station’s safe and reliable operation. In the SIL practical application, there is a major problem that whether reasonable setting for safety instrumented system (SIS) is reached or not. For the development of SIL in China is in the initial stage, there is no safety instrumented function application system or even overall assessment method or corresponding verification software for the gas station.Aiming at the above problems, the paper researched the methods of SIL grading and SIL verification, established SIL evaluation process for the gas station, edited assisting software for SIL verification in order to provide theoretical and technological supporting for the SIL assessment for the gas station, based on functional safety influence factors and China’s actual situation of gas station.The specific research achievements are as follows:(1) Analyze the affecting factors for functional safety such as failure modes, redundant configuration, common cause failure, self-diagnostic coverage, repair mode, periodicity functional test, structural constraints, and failure data and clarify the possible great impact of failure rate, repair mode, common cause failure and structural constraints on SIL assessment for China’s gas station.(2) Research SIL grading method. Determine the high precision coating method as SIL grading method by comparing three methods that are matrix method, the risk graph method and coating method and construct the SIL grading process for SIS of the gas station.4SIFs are SIL2and1is SIL1resulting from layer of protection analysis (LOPA) grading of the Chengjia gas station by adopting PHA-Pro8software, and there is no other requirement.(3) Research SIL verification model. Common cause failure model is established by applying redundant configuration factor to the β factor model aiming at common cause failure problem based on the analysis of the factors affecting functional safety. Markov model of D-S testimony theory is introduced to solve the problem of the failure rate as constant. Non-ideal maintenance model, Markov model, is established to solve the problem of the maintenance is ideal taking1oo2frame as an example.(4) Construct the SIL verification process of the gas station. D-S Markov model under the frame of1oo1、1oo2、2oo3、2oo2and1oo1D and the SIL verification process of frame constrain are built in allusion to the redundant configuration SIS for the gas station. Only5SIFs can reach SIL1of which4SIFs are not satisfied by SIL verification of SIS for Chengjia gas station.(5) Edit SIL verification software. On the basis of the research from above (1) to (4), SIL verification software is edited by VB6.0program language including1oo1、1oo2、2oo3、2oo2、 1oo1D redundant configuration. Markov model, D-S Markov Model, β factor model and common cause failure model can be selected to verify the SIL grade and give support for the SIL verification of the gas station.