Fluid dynamics and thermal aspects of the dewatering of high-alumina refractory castables: Removal of physically absorbed water

This article reports on an experimental investigation of the dewatering pro cess of cement-free high-alumina refractory castables. Simultaneous fluid d ynamic, thermal, and mass loss effects were investigated during the removal of physically absorbed water at temperatures of 250 to 700 degreesC. The r elease of steam was decisively affected by the castable's permeability leve l and the heating rate applied. The analysis of fluid dynamics revealed tha t at 1 degreesC/min, the main bulk of physical water was released as steam under saturated conditions at 100 degreesC. However, at 5 degreesC/min, ste am was trapped within the pores, and water loss was chaotically released an d shifted to higher temperatures. Thermal analysis showed that the endother mic boiling of water may result in a critical thermal shock in the castable 's structure. Both steam entrapment and thermal shock were more severe with the reduction in the castable's permeability level.