Case Studies

Marietta Cogeneration Plant

Project Specifications:

Based on a concept design developed by Fosdick & Hilmer, this new third party combined heat and power plant replaced the existing coal fired heating only plant. The new facility is based upon a natural gas turbine generator with heat recovery steam generation.

Project included engineering and design of pipe trestles for the 300 psig steam distribution and condensate return heating system. Power generated in the new facility was routed to the existing distribution switchgear located at the local utility connection.
  • Fosdick & Hilmer and DTE Energy prepared the Ohio EPA air permit applications for systems under this project.
  • Fosdick & Hilmer developed the O&M manuals, provided operator training, start-up assistance, and commissioning assistance for all systems designed.
  • Project was completed on schedule and within the allowable budget.


Key Features
  • Prepared specifications for Owner purchase of large mechanical and electrical equipment.
  • One 7900 ISO kW, 13.8 kV natural gas turbine generator.
  • One 150,000 lb./hr., heat recovery steam generator with supplemental duct firing.
  • Two 80,000 lb/hr, 300 psig, low NOx, packaged boiler.
  • 3,000 foot extension of 100 psig natural gas pipeline to power plant.
  • Natural gas compressor, 350 psig discharge.
  • Distributed control system (DCS) for entire plant.
  • Electrical switchgear, motor control centers for heating plant and cogeneration including synchronization gear for interconnecting to existing utility power distribution system.
  • 1500 feet of new pipe trestle including major highway crossing.
  • 8000 feet of new steam distribution and condensate return piping on new and existing pipe trestle. This included development of a 3-D model in Revit of the existing trestle structure and piping systems.
  • 3700 feet of 13.8 kV aerial power distribution including major highway crossing.