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PROJECT: Combined Cycle Power Plant Steam Drain System Improvement Project

This facility was a 147 MW combined cycle generation unit using two gas turbines each with their own Heat Recovery Steam Generators (HRSG's) and one steam turbine/generator unit. At the time of this project, the plant had been recently commissioned within the last two years and was still ironing out some of the left over operational design issues.

The typical loading schedule for the plant was nightly shutdowns with a subsequent restart the following morning. The plant had incorporated many design features for this type of loading schedule. One of these designs was the method by which the high and low pressure main steam piping utilized a drain system to prevent the accumiliation of condensate during the warm up process. This was necessary to prevent the condensate from flashing resulting in potential piping hammering or water induction to the steam turbine.

The plant had a history of compliants registered from the nearby residential neighborhoods resulting from the noise created by the warm up steam releases even though the design of the warm up steam drain system used a flashtank with a very large silencer.

The engineering service was able to conduct a thorough evaluation of the system, used extensive compressible multi-phase steam flow modelling, and redesign the piping, valves, exhaust system sizes, and control logic to completely eliminate all steam drain system noise.

RESULTS


• Successfully completed loop testing of all control system modifications for the steam drain system controls. The loop testing scope included from the operator graphics all the way out to the final field devices.