Interaction, Decoupling and Safety

In this control system, when the LPS header pressure rises, the PC output rises, and therefore, the PY-1 output drops and the supply valve closes. At the same time, the increase in the PC output increases the output of PY-2, which opens the extraction valve. When the LPS header pressure drops, the opposite is the response the supply valve opens and the extraction valve closes. If the control model is properly tuned and the gains of the summers PY-1 and PY-2 are properly set, there will be no interaction between speed 

Post-Oil Energy Technology After the Age of Fossil Fuels 

The turbine has to be protected against overspeeding, its critical operating parameters have to be monitored, and if a condition exists that could cause equipment damage, the turbine has to be stopped by closing the steam supply valve. 

This condition can be detected by a variety of devices, such as centrifugal switches, electronic tachometers, or strain-detecting devices installed on or near such components of the machine that are affected by the overspeed condition. 

Steam turbines provide opportunities for process improvements and energy savings. There usually are four separate and redundant process controller packages that perform operator automatic control (OAC), thermal 

---