THE IMPROVEMENT OF THE OPERATIONAL EFFICIENCY OF A TWO-STAGE EJECTOR UNIT FOR STEAM-TURBINE CONDENSER VACUUMING SYSTEMS

Liquid-gas ejectors are widely used in the systems of vacuumization of steam turbine condensers of power units of state district power plants in Russia and the CIS countries. Such a wide distribution of these jet devices is due to the simplicity of the design, due to which they are technologically advanced and cheap to manufacture, and during operation they practically do not require significant maintenance. However, the development and implementation of liquid-gas ejectors are associated with the need to optimize the schemes of use, complex calculations of the geometric and operating parameters of the ejector and the vacuum system for the initial data of each specific project. In addition, for ejectors operating continuously and with a high consumption of active water, energy efficiency is one of the key design requirements. This article proposes a set of technical measures that allow reducing the power expended on vacuumization of the steam space of a steam turbine. The proposed set of measures includes: the use of a two-stage unit with a first-stage liquid-gas ejector and a second-stage ejector, in which the active medium is water and the passive medium is a liquid-gas mixture; an improved hydraulic circuit diagram for feeding the unit with one pump; calculation of the optimal pressure at the first-stage outlet corresponding to the maximum efficiency of the unit. To calculate the optimal pressure at the second-stage inlet, an equation was obtained for the dependence of the consumed power of a two-stage vacuum unit on the suction pressure of the second stage. It was shown that the obtained dependence has an extremum, which corresponds to the value of the suction pressure of the second stage, ensuring the minimum consumed power.