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PROJECT: Gas Turbine Water Injection Control Improvement Feasibility Study

A California large electrical generation utility required contract engineering services for support in plant operations and maintenance improvement projects. Out of this contract, one major improvement study was requested that involved their 10 MW GE LM1500 turbine/generator unit.

The GE LM1500 unit was diesel fueled and fell under the jurisdiction of the local air pollution control district (APCD). As such, their operating permit issued by the APCD required operation of a "wet-Nox" water injection system. Previous emission source testing had concluded that a fixed ratio of 0.55 for the mass flow of water to the mass flow of fuel generated the lowest production of Nox.

The monitoring and operator display of this compliance variable was programmed into the installed Woodward Governor NetCon 5000 control system. Unfortunately, the control of the water injection was performed by a stand-alone Bailey SLC Controller and only used the turbine compressor discharge pressure transmitter as its process variable assuming that this value was always directly proportional to fuel flow.

Deliverables were provided consisting of alternatives with accompanied cost estimates for the improvement of this control system into one integrated and well controlled package. Unfortunately, this project was never pursued beyond this deliverable due to the plant being decommissioned within the following 5 years.

RESULTS


• Researched and completely understood the existing installed Wet-Nox system. Outlined the cause of operational and maintenance issues arising from the existing design. Provided alternatives for a control system improvement with associated estimated costs.