Influence of the remote block of nozzle steam distribution on the efficiency of steam turbines

Abstract

The existing two systems of steam distribution in steam turbines - throttle and nozzle significantly affect the efficiency of high-pressure cylinders of powerful power turbines. When the turbine industry operates under conditions of varying steam consumption, the advantages, as well as when the turbo generation is in operation under conditions of the regime, has an absolute advantage on the side of the nozzle steam distribution. However, in modern steam turbines, the constructive implementation of concomitant steam distribution in order to ensure the need for the flow path of the turbine with the help of special control stages necessary for settling a chamber with an adjustable height. It has been shown that a chamber with an adjustable stage operates with very low efficiency at reduced loads. What is, in fact, with the existing design of coupled steam distribution, the process of the main throttling of steam was transferred from the area of control valves in the controlled stage of the turbine. As a result, the real advantage of concomitant steam distribution (as follows from recent publications) begins only when the steam flow through the turbine is reduced by 30-35%, which is an advantage with the HPC efficiency relative to throttling steam distribution when the load is reduced by 50%, and not by 3-5 % with a general decrease in HPC efficiency by 15-20%. A number of measures to improve the adjustable stages and leveling the velocity fields in the chamber of the adjustable stage did not lead to serious changes in the existing situation. In this regard, a fundamentally different constructive implementation of coupled steam distribution, providing for the creation of an autonomous (connected to the turbine only pipeline) valve block with a bypass chamber adjacent. As a result, it was possible to eliminate almost all the disadvantages of the accompanying steam distribution and to increase the efficiency for the design mode by 2-4% and increase this indicator by 10-12% while reducing the turbine load by 50%.