Coal, Combined Cycle

Coal units convertto gas-fired combined cycle

Issue 5 and Volume 100.

Coal units convertto gas-fired combined cycle

When it was time to replace two of its older coal-fired units at Chesterfield Station, Virginia Power chose GE MS7001 F combustion turbines running on natural gas or distillate oil and Henry Vogt unfired, natural circulation boilers with integral deaerators for heat recovery.

The two units supply almost 400 MW of capacity, and although they were designed as intermediate duty units, they have performed so well that Virginia Power has been using them as base load units.

Reliability and availability have been “outstanding,” according to a report by the American Gas Association. Unit 7 had a reliability of 99.2 percent and availability of 91.2 percent in 1992 and Unit 8 has had availability of 91.2 percent and efficiency of 45 percent to date, according to Charles Taylor, Virginia Power spokesman. Heat rate for both units is 7,550 Btu/kWh.

The units have passed all environmental tests and perform below permitted levels for NOx, SO2 and other regulated pollutants. NOx control for both units is via steam injection.

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