Temperature effect on thermal conductivity of oxidised coal associated with its predictive model during coal pyrolysis

Abstract

To explore the heat transfer characteristics of oxidised coal, four kinds of bituminous coal from Shilawusu coalmine (SLWS), Huangling coalmine (HL), Ewirgol coalmine (AWEG), and Sangshuping coalmine (SSP) respectively, were collected and oxidised at 80, 120, 150, and 200 °C in air. The thermal conductivity of each coal were measured by laser flash apparatus with 30–300 °C. Main proximate analysis indexes influencing the thermal conductivity of oxidised coal were received by grey correlation method. A predictive model was established to forecast the thermal conductivity of oxidised coal. The results indicated that, when the temperature enhanced from 30 to 300 °C, the thermal conductivity of each coal gradually increased, the thermal conductivity for SLWS, HL, AWEG, and SSP increased by 12.0–12.6%, 9.2–10.9%, 7.0–9.6%, and 7.6–8.7%. At fixed temperature, the thermal conductivity of each coal increased linearly, which was markedly affected by the change of fixed carbon, ash, and volatiles in coal. Furthermore, a predictive model was established to forecast accurately the thermal conductivity of oxidised coal with a low relative error. Such findings can deepen the understanding of heat transfer in oxidised coal, and provide a theoretical basis in the prevention and intervention of coal fires.