Analysis of the possibility of reducing the heating time of thick-walled cylindrical components with holes

Thermal power plants, both fossil-fuel-fired and nuclear power plants operating in a modern energy system with a high share of renewable energy sources, should be characterised by high flexibility, i.e. operate safely over a wide range of load variations as having short start-up and shutdown times. Many years of experience in power plants and stress calculations in power plant components have shown that thick-walled pressure parts with complex shapes or holes in the walls determine the maximum allowable raising or lowering of the working fluid temperature. A new method for determining the optimum fluid temperature variations in a cylindrical component with openings was developed. The optimum fluid temperature variation was determined from the condition that the sum of the circumferential stresses from thermal and pressure load is equal to the allowable stress at the edge of the opening. The optimum fluid temperature variation over time was determined at constant pressure and with a linear change in pressure over time using the Heat Balance Integral Method (HBIM). HBIM is preferred over other numerical and analytical methods because it can accurately determine temperature distribution at the beginning of optimum heating for very short times.