CRITERIA AND CONDITIONS OF THE INTER-CIRCUIT THERMODYNAMIC INSTABILITY OF THE NPP’S MODERNIZED TURBINE SYSTEM

Abstract

The original method of determining the criteria and conditions of inter-circuit thermodynamic instability in the modernized system "steam turbine - regeneration system with absorption heat pumps" is presented. This was developed through a thermodynamic analysis of the effect of independent fluctuating deviations from equilibrium in both the wet vapor flow at the absorption heat pump inlet and the measured pressure in the absorption heat pump/low pressure mixing heaters. Unlike known approaches to modeling thermodynamic processes, the thermodynamic model of the developed method takes into account the influence of fluctuating deviations from the equilibrium state of thermodynamic parameters, which determine the criteria and conditions of interloop thermodynamic instability. Based on the analysis of the received criteria and conditions, it was established that the main cause of inter-circuit thermodynamic instability in the modernized system "steam turbine unit — a regeneration system with absorption heat pumps" is determined by the incompleteness (inertia) of heat-mass exchange and hydrodynamic processes during fluctuating deviations from the equilibrium state of thermodynamic parameters. Prevention of the conditions for inter-loop thermodynamic instability in the modernized system "steam turbine unit — a regeneration system with absorption heat pumps" can be ensured by installing flow controllers in the wet steam supply circuits from the high-pressure cylinder of the turbine to the absorption heat pumps, and absorption heat pumps in mixing heaters low pressure to maintain a constant pressure in absorption heat pumps and low pressure mixing heaters. It is also necessary to consider that the modernization of the "steam turbine unit — a regeneration system with absorption heat pumps" system can affect the performance and conditions of inter-loop thermodynamic instability of "neighboring" systems. These issues determine the need for further analysis of the validity of the modernization of the "steam turbine unit — a regeneration system with absorption heat pumps" systems.