Three-Dimensional Thermal Stress Distribution of Opposed Firing Boiler: Numerical Study and Experimental Verification

Abstract

By coupling fluid dynamics and solid mechanics, a numerical framework has been developed to investigate the temperature distribution and stress field on the boiler walls and to propose useful advice on reducing the thermal stress and improving the mechanical reliability. Simulation of a laboratory scale, gas fuel opposed firing boiler has been conducted, including the combustion and heat transfer process, as well as the thermal stress distribution by finite-element analysis. The results have been verified by a previous parallel experiment. The results show that heat load and the symmetry of flame can obviously affect the mean temperature of the boiler. In the upper furnace, the amount of fuel is the major factor affecting temperature profile, while the temperature in the burner zone is mainly determined by the distribution of the flame. The temperature is extremely high (about 520 K) at the wall connections. Stress distribution is of great relevance to temperature and asymmetric combustion, which causes extremely strong stress (more than 630 kPa). The study is of great significance for providing guidance for the design, manufacture, installation, and operation of boilers.