Numerical Simulation of Non-Stationary Processes in the Gas Turbine Circuit of the Sstar Lead-Cooled Reactor

Abstract

The problem of mathematical and numerical modeling of non-stationary processes in a closed gas turbine installation as part of an energy conversion unit of a lead-cooled reactor is considered. The problem is solved in a fairly General formulation, in which the gas circuit can include an arbitrary number of turbines with gas preheating, an arbitrary number of compressors with gas pre-cooling, as well as a heat exchanger for regenerative gas heating. Variants of both single-shaft and two-shaft gas turbine installations are considered. Point idealization is used when modeling the flow part of the turbine and compressor. Heat and mass transfer in the circuits of lead and gas coolants is described in a one-dimensional approximation. The possibility of mutual phase transformations of a melt-solid phase in the lead coolant is taken into account. Calculation of heat and mass transfer in the circuits is carried out within the single approach, in which the circulation circuit is represented as a set of interconnected heat-hydraulic elements (channels). Integration of the system of heat and mass transfer equations in the contour is performed using a fast scalar sweeping algorithm. The calculation algorithm provides the ability to take into account the sources of impulse and mass at arbitrary nodal points of the contour. This makes it possible to “end-to-end” computation when integrating the system of equations of gas dynamics along a closed loop, taking into account changes in adiabatic pressure drops at the points of turbines and compressors at each time step. The possibility of using the integral form of the momentum equation for modeling heat and mass transfer in a gas circuit is considered. For the SSTAR-type reactor with a lead coolant and a gas-turbine energy conversion cycle, the calculation of an emergency process with a rupture of a hot gas pipeline was performed. It was found that, in contrast to a reactor with a steam-turbine cycle of energy conversion of the BREST type, lead solidification in gas heaters does not occur in this accident. The study results can be used in elaborating the designs of lead cooled reactors and high-temperature gas reactors.