Phase change heat storage refractory castables for CDQ tank linings: Preparation, properties and simulation design

Frequent temperature fluctuations in coke dry quenching (CDQ) systems increase thermal stress and shorten the service life of refractory linings. This work aimed to develop a phase change heat storage refractory castable (PCHSRC) by incorporating micro- and macro-encapsulated Al–Si alloy to improve thermal regulation performance of linings. The effects of metal microcapsule addition on the microstructure, mechanical properties, and thermophysical behavior of the castables were systematically investigated, and the thermal-regulating performance of the proposed material in a CDQ tank lining was further evaluated by transient numerical simulation. Experimental results showed that the introduction of microcapsules promoted the in-situ formation of mullite whiskers and alumina hollow shells in the matrix. Among the investigated compositions, the castable containing 6 wt% microcapsules exhibited the best overall performance, with a high temperature flexural strength of 7.1 MPa, about 92% higher than that of the reference castable. Its thermal conductivity at 1000 °C increased from 1.16 to 1.63 W m−1 K−1. Based on this optimized matrix, PCHSRC was constructed using large-particle macrocapsules as aggregate. Numerical simulation showed that the PCHSRC-based composite lining increased the minimum hot-face temperature by 48.0%, reduced the hot-face temperature fluctuation amplitude by 22.8%, and lowered the maximum shell temperature by 17.7% compared with a conventional high-alumina refractory lining. These results demonstrated the potential of PCHSRC for thermal regulation of furnace linings in high temperature industrial applications.