The SIS improvement in hydrogen furnace based on SIL

According to IEC61511, the assessing process of safety integrity level (SIL) is summarized. It takes the furnace of the hydrogenation reactor in a petrochemical enterprise for example, where the interlock circuit and safety instrumented function (SIF) are quantitatively analyzed on the basis of the assessing process. The assessment results show that the actual SIL of overall system basically satisfies the required SIL and some recommendations are presented. It provides helpful references for other equipments in refinery factories.