Feed water control system for steam generator - has temp. sensor and takes account of water level change time lag

摘要

The system regulates the water supply to the base of a steam generator in a nuclear power station. Feed water and steam flow are measured, also water level in the generator, the respective signals being fed to a unit emitting a control signal to the valve opening mechanism. the feed water temperature is also measured and a corresponding signal fed to the unit to effect a change in its behaviour. The change takes account of a time lag or delay in the level alteration as the water feed rate is varied. There can be a small capacity valve parallel to a large one, only the small one being adjusted for small variations, while the large one is adjusted after the small one is fully open.