Experimental Study of Deformation Risk and Interpolation Analysis of Temperature for Water Walls under Flexible Low-Load Conditions

With the development of renewable energy in power generation, a large number of thermal power plants operate under flexible working conditions. To study water wall deformation risk under flexible low-load conditions, a lab-scale opposed firing boiler was built to measure and analyze the temperature and thermal stress of the water wall under low-load flexible operating conditions with several nontypical burner arrangements. The results showed that flame radiation and flue gas convection heat transfer induced a high-temperature zone. Thermal stress was mainly caused by thermal expansion of the metal and expansion or extrusion deformation of other areas. Also, local thermal stress fluctuations and excessive values appeared under variable conditions. In addition, the burners' symmetrical arrangement in the center effectively reduced thermal stress fluctuations and overall thermal stress under flexible working conditions. Finally, based on the limited temperature measurement points in this experiment, the optimal power parameter α for the inverse distance weighted (IDW) method and the shape parameter ϵ for the radial basis function (RBF) method were found to make a reasonable interpolation prediction of the temperature distribution of the water wall. This study highlights the recommended burner arrangements under flexible low-load conditions and the optimal parameters of the IDW and the RBF methods for estimating temperature in guiding safe operation of the water wall.