Large eddy simulation of a 660 MW utility boiler under variable load conditions

Large eddy simulation(LES) has become a promising tool for pulverized coal combustion with the development of computational fluid dynamics(CFD)technologies in recent years. LES can better capture the unsteady features and turbulent structures of coal jet flame than Reynolds averaged Navier Stokes(RANS). The coalfired power plants in China are now required to be operated in a wide load range and quickly respond to the electric grid. The boiler performance of variable loads should be evaluated in terms of flow, heat transfer, and combustion processes. In this paper, LES was applied to simulate a 660MW ultra-supercritical boiler under BMCR(boiler maximum continue rate), 75%THA-100, and 50%THA-100conditions. The predicted gas velocities agree well with the thermal calculation and the temperature error is less than130 K. The simulation results show that the operation load has significant effects on the boiler performance. It is also proved that LES can provide guidance for the design and operation of advanced coal-fired boilers.