PROJECT
Cooperative Energy selected a repower strategy that added a natural gas-fired combustion turbine and heat recovery steam generator (HRSG) to repower the existing steam turbine. The 1x1 combined-cycle unit was equipped with a Siemens 9000HL advanced-class combustion turbine technology paired with the existing steam turbine. The advanced-class gas turbine technology and HRSG increased the existing unit’s power capacity from 204 MW to 572 MW, launching as the most efficient repowered unit in North America.
The heat recovery repower strategy utilizes the thermal power from a new gas turbine in the existing plant thermal systems. This strategy is the most cost-efficient means of coal-to-gas conversions in North America. Utilizing the heat recovery repower strategy, Plant Morrow achieves the efficiency of new combined-cycle plants, while reducing its previous carbon footprint by half.
As the EPCM contractor, our team installed a triple-pressure, reheat HRSG, which includes a selective catalytic reduction (SCR) system to reduce levels of nitrogen oxide (NOx) and carbon dioxide (CO2). The repowered unit reuses the existing cooling tower to reject heat from the existing condenser. The new gas turbine and HRSG are unenclosed, and electrical output from the new turbine was stepped up to 230-kV and interconnected with an expanded site substation.
Client
Cooperative Energy
Location
Purvis, Mississippi
Region
Southeast
Services
Industry
Our team assisted with all phases of repowering of the station, one that had opened in 1978 with Burns & McDonnell as original designer. We worked with Cooperative Energy to evaluate all options for developing new gas generation within the co-op’s fleet, developing a project definition report that incorporated preliminary general arrangements, heat balances, P&IDs, one-line drawings, control system architecture, a list of major equipment, a project schedule and estimates for total installed cost.
We also developed specifications and received firm quotations for a gas turbine generator and heat recovery steam generator (HRSG) in support of the project estimate. We also provided engineering services for demolition of two existing coal boilers and emissions control equipment.
Our team assisted with permitting and environmental modeling. We submitted a Prevention of Significant Deterioration (PSD) air permit application for repowering of steam turbines (and removal of coal) with new combined-cycle combustion turbines. The project included netting of emissions from the coal-fired boilers that were retired and demolished, along with the addition of the new turbines. The project was subject to PSD for CO2 and greenhouse gases, so air dispersion modeling and Best Available Control Technology (BACT) analyses were conducted.
Cooperative Energy prioritized retention of existing plant staff. Repowering the facility allowed the co-op to leverage existing employees to play an active role in the project, giving the operating and maintenance staff in-depth knowledge of the facility. The construction team achieved more than 1.5 million work hours without a recordable incident. Despite pandemic labor challenges, the project was completed on schedule and on budget.