Efficiency of operation of 300 MW condensing thermal power blocks with supercritical steam parameters in sliding pressure mode

The previous research of the application of sliding pressure has shown certain advantages in the operation of high-power condensing blocks with supercritical steam parameters in sliding pressure mode in comparison to the one with constant pressure. The maintenance of stable temperature regime and thermal expansion of turbine elements, prolongation of service life of materials of steam pipes and heating surfaces of the boiler due to the decrease in pressure of the working medium are only some of those advantages. On the other hand, the operation mode of a condensing block with sliding pressure is characterized by the change in cost-effectiveness. The result of this change is mainly due to the de-crease of steam throttling in the turbine's balancing valves and the increase of its internal action in a high pressure turbine, then also due to reduced steam consumption of the feed turbo pump just like a drop in the feed water pressure at the steam boiler inlet. A model has been developed within the framework of this study that follows such changes and their graphical interpretation is provided. The analysis results show that switching 300 MW blocks from the constant to the sliding pressure regime in the 30-60% load range increases the block efficiency respectively by 6.70-1.05%.