About this lesson
A gas turbine drives a generator and its hot exhaust passes through a heat recovery steam generator (HRSG) that raises steam at three pressures. The steam drives HP, IP and LP turbines on one shaft and is condensed and pumped back. This is full-load operation with every bypass valve closed.
How it works
- Air is compressed, fuel is burned in the combustor and the hot gas expands through the gas turbine, driving its generator.
- The diverter damper sends the exhaust into the HRSG, where it meets the hottest HPSH 2 module first and leaves cool at the LP economiser.
- The BFP pumps feedwater through the economisers to the drums; evaporators make saturated steam and superheaters dry it.
- HP steam expands in the HP turbine; its exhaust (cold reheat) is joined by IP steam and reheated in RH 1 and RH 2.
- Hot reheat steam drives the IP turbine; its exhaust joins LP steam at the LP turbine inlet and expands to condenser vacuum.
- The condenser turns the exhaust back to water; the CEP returns it to the LP economiser and the cycle repeats.