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Programmable Safety Systems for Burner Management on ... - ICEWeb

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Temperature protecti<strong>on</strong> (Fig. 2) c<strong>on</strong>sists of a number of start up and c<strong>on</strong>tinuous teststhroughout the turbines operati<strong>on</strong>. Primary protecti<strong>on</strong> is provided by two sets ofthermocouples mounted in the exhaust case of the turbine. The thermocouples arem<strong>on</strong>itored by the SPC and PLC. The critical stages of the process that can cause overtemperature, being the correct burning process are m<strong>on</strong>itored by the PSS inc<strong>on</strong>juncti<strong>on</strong> with the other c<strong>on</strong>trol systems.1. PurgeOnce the valve leak test has completed successfully a Purge Step commences. Aminimum turbine speed of 1500 RPM must be maintained <str<strong>on</strong>g>for</str<strong>on</strong>g> 30 sec<strong>on</strong>ds to evacuateany unburnt fuel from previous runs.2. Light OffAfter the Purge, SOV 1 and 2 open and the modulating valve allows gas to flow. Aspark ignites the gas. A successful Light Off has occurred if the Turbine speed isdriven up by the exhaust gases to a set speed of 2300 RPM in 10 sec<strong>on</strong>ds. The PLCand SPC also detect light off by comparing temperature rise over time providing threeindependent and diverse proofs.Fig 3. Modulating Valve M<strong>on</strong>itoring.

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