| Abstract |
This paper describes two utility boiler conversions adding natural gas firing capabilities to #6 oil fired boilers. Units 5 and 6 at PREPA's South Coast Generating Station are tangentially-fired steam boilers with electrical generating capacities of 410 MW each. In 2011, both boilers were modified to fire natural gas only or combinations of natural gas and fuel oil. The boilers previously fired only fuel oil. Coen Company, Inc. (Coen) was contracted by LT Automation on behalf of Puerto Rico Electric Power Authority (PREPA) to supply necessary engineering services, equipment and commissioning for the gas conversion. Coen engineering services included CFD modeling to optimize air flow distribution and predict flame patterns in the furnace. A simulation code was written to predict fuel and air flows to all corners and elevation zones. A complete thermodynamic study was performed to evaluate the boiler heat absorption impact due to the gas conversion. Coen equipment included gas burners, local burner safety shut-off valves, boiler header skids, a main gas pressure regulating skid, and local control panels for the gas burners. The gas conversions on Units 5 and 6 were commissioned in April-May 2011. During commissioning, extensive field data was obtained and will be presented including settings for optimal emissions on both fuels. Data on the convective section of the boiler, due to predicted changes in boiler heat absorption profiles when firing gas will be presented including tube temperatures. |
