Sliding-pressure operation

Sliding-pressure operation is a boiler and steam-turbine control mode in which steam pressure is allowed to vary with load instead of being held constant by throttling, so the boiler runs at a lower pressure at part load. The turbine governor valves stay near wide open and the firing rate sets the pressure, which cuts throttling losses, reduces thermal stress from large pressure swings, and improves part-load efficiency. Marine and power-plant boilers use it to follow load smoothly; the trade-off is slower pressure response, so a hybrid throttle-then-slide scheme is common at the top of the load range.