Method of improving the power cycle efficiency of a steam turbine for supercritical steam conditions

摘要

A method for improving the efficiency of a power cycle in a steam turbine for initial supercritical steam conditions in which the working fluid is expanded from the initial supercritical steam conditions to a lower pressure which is, however, higher than the critical pressure. The working fluid is divided into two streams, one of which is cooled down in a high temperature regenerative heat exchanger for yielding its heat to feed water already previously heated in regenerative feed heaters. The other stream is expanded in the turbine in a conventional manner, and thereafter the two streams are mixed before entering the high temperature regenerative heat exchanger and boiler. The high temperature regenerative heat exchanger is sub-divided into a number of sections, and the mass flow rate of the heating medium in predetermined sections is changed in a step manner by directing a part of the working fluid from a predetermined point of the power cycle to a predetermined section of the high temperature regenerative heat exchanger.