Combined-cycle power plant
Sewaren 7 is a combined-cycle power plant in Woodbridge, New Jersey, US. PSEG Power’s subsidiary PSEG Fossil developed the 538MW highly efficient power project that produces electricity for 500,000 homes.
With the estimated cost of over $600m, the new plant replaced units 1, 2, 3 and 4 of PSEG’s existing Sewaren coal-fired power plant on the same site. The units were shut down after approximately 70 years of operation.
PSEG invested in the project due to lower gas prices and also to reduce power plant emissions. Construction of the Sewaren 7 plant commenced in June 2016 and was commissioned in June 2018.
The project generated significant tax revenue for the local economy and economic benefits during the construction phase by creating approximately 350 jobs. It also generated another 28 full-time operational jobs after commissioning.
The project replaced the existing less efficient generating units with a dual-fuel combined-cycle power plant. It is equipped with a high-efficiency GE’s 7HA.02 (H-class) gas turbine and A650 steam turbine in a turbine building.
The plant includes a 3,800t modular, C-frame heat recovery steam generator (HRSG), a modular air-cooled condenser, a fuel gas heating station, an emergency diesel generator, an auxiliary electrical building, a main stack, and an auxiliary boiler stack.
The air-cooled condenser is 125ft-tall and has 20 discrete heat transfer cells, covering an area of 40,500ft². It recycles water continuously for cooling purposes, reducing the need for cooling water. The condenser also decreases the plant’s dependence on the Arthur Kill tidal strait for cooling water.
Additional facilities include fuel oil forwarding pump house, fuel oil tank, emissions monitoring building, hydrogen and ammonia storage and fire-water storage tanks. The plant is also equipped with a 230kV step-up transformer, an auxiliary cooling tower, a warehouse, and a service water pump house.
The combined-cycle power plant uses gas and steam to generate power from the same amount of fuel. Natural gas is fired in the gas turbine generator to produce electricity. Waste heat from the gas turbine is diverted towards the HRSG to generate steam, which drives the steam turbine to produce additional electricity.
The 7HA.02 plant gas turbines are highly efficient and can produce the same amount of power from half the quantity of fuel as compared to the older steam generators.
The plant operates on two types of fuel, including natural gas and ultra-low sulphur distillate (ULSD) fuel oil. The dual-fuel capability enables the use of ULSD in the event of a shortfall in natural gas supply, increasing the plant’s dependability and reliability.
The natural gas required for the plant is supplied through the Texas Eastern and Transco pipelines.
The technology used in the HA gas turbines reduces the emission rates at the new plant to approximately half as that of the older plant. The emissions reduced by the technology are equivalent to taking more than 150,000 cars off the road.
The plant features a combination of low nitrogen oxide combustors and a selective catalytic reduction system to reduce nitrogen emissions. An oxidation catalyst also cuts carbon monoxide emissions.
Black & Veatch won the engineering, procurement services and construction management contract for the project.
GE supplied the gas turbines, while Holtec International provided the air-cooled condenser for the plant.
Matrix Service Company carried out above-ground electrical construction work in April 2017.
Stonebridge Steel Erection used 1,500t of steel for constructing seven buildings of the plant, including the turbine hall, as well as fuel and gas building.
JMS Naval Architects performed the engineering review of the barge transport of the HRSG in August 2017. Mammoet Global Engineering performed load-out operation of the machinery on and off-the-barge.
VistaEnergy provided the construction management, project execution planning and development services, while Durr Mechanical Construction was the mechanical contractor for the project.
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