The new CHP system included a nominally rated 14 MW natural gas fired combustion turbine generator, with the exhaust from the turbine routed to a Heat Recovery Steam Generator (HRSG) to produce steam from the hot exhaust gases discharged from the turbine. A duct burner was installed in the exhaust duct between the combustion turbine and the HRSG to fire additional natural gas to increase the steam production from the HRSG. The HRSG can produce approximately 200,000 lb/hr of saturated steam at 200 psig when firing additional natural gas in the duct burner at the maximum heat input rate.

A diverter damper, bypass stack, isolation damper, and fresh air fan are installed between the discharge of the turbine and the duct burner. This allows operation of the combustion turbine generator to produce electricity independent of the HRSG when the HRSG is out of service, and allows operation of the duct burner, fresh air fan and HRSG to produce steam independently of the combustion turbine when the combustion turbine is out of service.

• The new auxiliary systems include a deaerator with boiler feedwater pumps installed in the existing boiler building; a blow down system for the surface blow down from the HRSG; and a natural gas conditioning system to treat the fuel to the combustion turbine. In, addition, the system is designed to facilitate the addition of a black-start diesel engine driven generator in the future, for starting the system in the event of a power outage from the utility. The Owner coordinated the removal of the existing coal fired boiler designated as Boiler No. 2 to provide space for the new deaerator, and the addition of a new opening in the building to facilitate moving the deaerator into the building.

The CHP system is housed in a new building located near the existing boiler plant, adjacent to the coal unloading area and substation in an area that currently has two abandoned oil tanks.

The CHP building is approximately 52’-0” wide by 177’-0” long, and includes an electrical room for the 480V switchgear, motor control centers, battery system, and other auxiliary equipment. The CHP building is conventional steel frame construction with insulated metal walls and an insulated metal deck roof.

Sustainability:

• The condensate systems and water treatment systems in the existing boiler plant were utilized to serve the new CHP system.

Project Highlights:

• A new pipe bridge was installed between the CHP building and the existing boiler plant for steam, boiler feed water, condensate, blow down, city water, compressed air, and electrical connections between the new CHP system and the existing boiler plant. Natural gas was routed in new piping from the existing natural gas metering station for the site to the CHP Building.