Repowering reheat units with gas turbines: Final report. [Adding gas turbines and heat recovery to present units]

Technical Report · Fri May 01 04:00:00 EDT 1987

OSTI ID:6558562

Rives, J D; Catina, J

Although conventional repowering on nonreheat units replaces existing boilers with gas turbines and heat recovery steam generators, options investigated by Virginia Power use gas turbine waste heat to supplement, rather than replace, the output of existing steam generators. Virginia Power's experience in considering feedwater heater repowering (FHR) and hot windbox repowering (HWR) as repowering options is described here. Studying five plants identified as potential repowering candidates, investigators first evaluated FHR, which uses a gas turbine generator set equipped with an economizer to heat boiler feedwater. This reduces the steam turbine extraction flow and increases the steam turbine capacity. HWR, the second method investigated, routes the hot, relatively oxygen-rich exhaust flow from a gas turbine into the boiler windbox, eliminating the need for an air preheater. A boiler stack gas cooler then heats feedwater, again increasing turbine capacity by reducing extraction steam flow requirements for feedwater heating. FHR provided the lowest installed cost, especially at Mount Storm unit 3, a coal-fired minemouth plant. Use of a gas turbine to heat feedwater at this plant resulted in a $523/kW (1985) installed cost and 124-MWe unit capacity increase at a design incremental heat rate of 8600 Btu/kWh. FHR at Mount Storm units 1, 2, and 3 cost less overall than installation and operation of a new combined cycle. Although the findings and conclusions in this series of repowering reports are largely unique to the individual plants, units, and applications studied, other utilities performing repowering studies can draw on the types of consideration entertained, alternatives examined, and factors and rationale leading to rejection or acceptance of a given repowering approach. 12 figs., 12 tabs.

• Research Organization: Virginia Power Co., Richmond (USA); Coe Corp., Sunnyvale, CA (USA); Electric Power Research Inst., Palo Alto, CA (USA)
• OSTI ID: 6558562
• Report Number(s): EPRI-AP-5216; ON: TI87920440
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
200102* -- Fossil-Fueled Power Plants-- Power Cycles
AIR HEATERS
BLOWERS
BOILERS
COMBINED-CYCLE POWER PLANTS
DESIGN
ECONOMIC ANALYSIS
ECONOMICS
FEASIBILITY STUDIES
FEEDWATER HEATERS
FOSSIL-FUEL POWER PLANTS
GAS TURBINES
HEAT RATE
HEATERS
MACHINERY
MODIFICATIONS
POWER PLANTS
RECOMMENDATIONS
THERMAL POWER PLANTS
TURBINES
TURBOMACHINERY
WASTE HEAT UTILIZATION
WASTE PRODUCT UTILIZATION