Application of combustion analyzers in safety instrumented systems
The combustion process has always been considered having the potential for a hazardous event which could lead to personnel injury or loss of production. To mitigate this risk, the process industry is now implementing Safety Instrumented Systems which can identify hazardous operating conditions and correctly respond in such a way to bring the combustion process back to a safe operating condition or implement an automatically controlled shutdown sequence to reduce the risk of operator error causing a catastrophic event. Oxygen and combustible flue gas analyzers are now being utilized in these combustion Safety Instrumented Systems (SIS) to identify hazardous operating conditions and automatically return the process to a safe state. The standards of IEC 61511 and API RP 556 will be reviewed as they apply to flue gas analyzers, as well as the process variables of the oxygen and combustible analyzer available for implementation into the SIS system for combustion monitoring, and the resultant actions required to return the process to a safe condition.