Simulation of a circulating fluidized bed power plant integrated with a thermal energy storage system during transient operation

Abstract

In the current work, a transient/dynamic 1-dimensional model has been developed in the commercial software APROS for the 300 MWth circulating fluidized bed power plant of Sumitomo SHI FW. The operation of the plant is simulated under steady-state at two boiler loads: 100% and 60%, and the results for the distribution of temperature, pressure, mass and heat flow of the water/steam as well as for the flue gas composition and its thermodynamic properties are compared against performance data provided by the company, showing good agreement. Following this, the validated model is utilized to investigate the effectiveness of a thermal energy storage concept, which utilizes a bubbling fluidized bed to store particles during ramp down operation and return them to the fluidized bed during ramp up. Three dynamic scenarios are simulated for the load transition 100%-60%-100%: (a) a case without the use of thermal energy storage, (b) a case with thermal energy storage removing 20% of the solid inventory of the fluidized bed, and (c) a case with thermal energy storage removing 40% of the solid mass of the bed. The results of the three simulations are compared between them and the achieved ramp down/up rates (calculated based on the 90% method) are equal to: (a) 5.09/5.06%/min, (b) 5.64/5.73%/min and (c) 6.19/6.12%/min, respectively. These rates are higher than the current state-of-the-art rates of circulating fluidized bed power plants. The highest rates were achieved with the 3rd simulation scenario, in which, however, the live steam pressure fluctuations exceeded the technical limits of ±10 bar.