Load rejection operation in conventional power plants in ENEL-Italy

A description of the experience gained in establishing a procedure which trips all fuel input to the boiler and maintains house load operating the turbine on mass and energy stored in the boiler is presented. This procedure was qualified a few years ago and since then has been used in the 320 MW units in operation (the main bulk of ENEL´s thermal capacity) whether equipped with subcritical once-through boilers or with assisted circulation drum boilers. A series of tests carried out on supercritical 660 MW units shows that by adopting the same procedure these large units can also sustain successfully the run back to house load. The procedure has been used in many other thermal units of size ranging between 70 MW to 240 MW and can be performed in most of ENEL´s thermal power plants