22 September 2020
Moore Industries Refinery Methane Analyzer Differential Safety Trip
A Refinery required a third-party certified SIL 1 Solution to calculate the differential between two Analysers that measure the Methane content on the Inlet and Outlet of a Reactor that breaks down the Hydrocarbons levels in the process stream. The methane level is always higher on the Outlet side of the reactor, however should the Differential with the Input exceed the setpoint these higher Methane levels could reach flashpoint with a sharp trend that could lead to an explosion.
After a Hazard and Operability Analysis (HAZOP) of the existing installation it was determined the Refinery needed to mitigate the risk and install an independent SIL1 trip solution. Moore industries designed the Differential Trip Safety Instrumented Function (SIF) and provided their client with an Independent Safety Integrity Level (SIL) Verification Report.
The two independent Methane Analyser measurements are sent to the SST Signal Splitters where one output is used for the Differential Calculation and the other is transmitted to the Distributed Control System.
The Methane Differential is calculated by the STZ Transmitter and sent to the STA Logic Solver where a Differential between Inlet and Outlet the Analysers exceeding 10% MOL will trip the setpoint. In addition, the STA Logic Solver retransmits the calculated Methane Differential to the Distributed Control System.
- exida certified SIL2/3 capable Logic Solver
- Signal Splitters provide independence from Basic Process Control System
- Standard Off the Shelf hardware, user customisable for SIS Solutions