Energy recovery of blast-furnace gas coke. The importance of a correct regulation system

The present work deals with the regulation system of a plant recovering the energy of blast-furnace gas coke residual pressure. Such plant is provided by a turbogenerator which produces electric energy expanding the gas coke up to the mill pipe network pressure vallue. Before intervention the regulation apparatus consisted of an automatic vane orientation system of a turbine stator and a throttle valve. Once the system has become operative, the regulation set seemed to be inadequate showing a significant reduction in energy recovery due to the variation of the gas coke characteristics, compared to the original engineering specifications. A mathematical model for the plant simulation has been developed throughly the regulation system static and dynamic responses. This simulation together with a series of experimental tests indicated the causes of the operation problems in the original regulation system. On the base of the response times of the old regulation system, a valve with reduced intervention inertia has been introduced. The regulation logic was also modified: the valve interventions were directly linked to the pressure variations recorded at the blast furnace top, and no longer to the opening variation of the turbine automatic system. A more rational use of the plant components and its control system, together with and increase of the electric energy production have been the final results.