Expanding implementation of intermittent renewable energy sources has already
started to change the role of thermal power plants in energy systems across
Europe. Traditionally base load plants are now forced to operate as peaking
plants. A familiar transition in upcoming years is expected in Croatia and
coal power plant operators are preparing accordingly. To evaluate cycling
capabilities and control system operation for flexible operation of selected
210 MW coal plant, series of tests with different load gradients were
performed and results were thoroughly analyzed. Two possible ?bottlenecks?
are identified, thermal stress in superheater header, and achievable ramping
rate considering operational limitations of coal feeders, firing system and
evaporator dynamics. Several unexpected readings were observed, usually
caused by malfunctioning sensors and equipment, resulting in unexpected
oscillations of superheated steam temperature. Based on superheater geometry
and experimental data, maximal steam temperature gradient during ramping was
evaluated. Since thermal stress was well inside the safety margins, the
simulation model of the whole boiler was used to evaluate achievable ramping
on electric side.
Designing a control system for the output superheater of the once-through boiler at the coal power plant
