Dynamic modeling, validation and analysis of direct air-cooling condenser with integration to the coal-fired power plant for flexible operation

Abstract

Coal-fired power plants with direct air-cooling condensers (DACC-CFPPs) have been widely used in areas rich in coal but short of water since they can significantly reduce water consumption. Despite its water-saving advantages, direct air-cooling condensers have inherent defects such as environmental and load sensitivity, higher costs and poor cooling performance, which deteriorate the economics and flexibility of the integrated system. For safe, efficient and flexible operation, this paper presents the development of a direct air-cooling condenser dynamic model integrated with a 600 MWe coal-fired power plant to study the interactions between heat and power within the entire DACC-CFPP under various load and ambient conditions. The condenser is modeled in a one-dimensional multi-section manner to reflect the impacts of crosswind and ambient temperature disturbances. A detailed turbine-feedwater heater system model is also developed to link the direct air-cooling condenser and power plant together. Steady-state and dynamic validations under various operating conditions are conducted, which demonstrate the high fidelity of the developed model. Simulation studies are then carried out to investigate the dynamic interactions between boiler-turbine, condenser and environmental conditions. We find that manipulating the fan array speed controls the condenser pressure effectively in terms of environmental disturbance rejection and load ramping. Motivated by this finding, a novel variable condenser pressure operating mode is proposed to coordinate the direct air-cooling condenser and coal-fired power plant operation, which can significantly improve the load tracking performance of the integrated plant.