520-MW Steam Turbine Repowering

Location: Grand Tower, Ill.

Client: Ameren Services Inc.

Completion Date: 2000

The project consisted of repowering the existing Grand Tower Power Station’s Unit 3 and 4 steam turbines with two Siemens/Westinghouse 501F combustion turbines. The gas turbine and heat recovery steam generator (HRSG) associated with Unit 3 steam turbine were designated Unit 1. The gas turbine and heat recovery steam generator associated with Unit 4 steam turbine are now designated Unit 2.

  • Planning, estimating and scheduling
  • Existing plant equipment and systems assessment
  • Detailed design and field services
  • Preliminary engineering

The existing Grand Tower plant consisted of two coal-fired steam-electric units. One unit is a non-reheat 112-MW unit and the other is a 90-MW non-reheat unit. Burns & McDonnell was retained to provide preliminary engineering to assist Ameren in the feasibility analysis of repowering the two steam turbines with gas-fired combustion turbines and heat recovery steam generators (HRSG). The preliminary engineering work included conducting an assessment of the existing plant equipment and systems. This included reviewing operating and maintenance records, recent outage logs, interviewing plant maintenance personnel and inspecting equipment and systems. In working with plant maintenance personnel, a plan for replacing or rehabilitating plant equipment and systems was developed.

Each gas turbine is rated approximately 176-MW at ISO conditions of 59 degrees F. After the repowering, Unit 3 and 4 steam turbines will be rated at approximately 90 MW and 112 MW net generating capability, respectively.

The units are now suitable for single fuel (natural gas) operation and are provided with facilities to support operation on gas. The generating units were designed for intermediate duty service and have on-site operations and maintenance staff.

  • Duct-firing and thermal cycle enhancements
  • Distributed control system (DCS) and turbine controls upgrade
  • Added plant DCS
  • Congested site
  • Reduced air emissions
  • 90-MW and 112-MW net generating capability