This study investigates the influence of crucible configuration on temperature uniformity and energy efficiency in a Lengthwise Graphitization Furnace (LWG) . The conventional LWG generally employ cylindrical 9-hole crucibles, with only two crucibles accommodated in a single furnace. However, the circular geometry inevitably creates large gaps between adjacent crucibles, leading to inefficient utilization of the furnace interior space. In this study, a novel square 4-hole crucible configuration is proposed to achieve a more compact crucible arrangement. Compared with the conventional design, this configuration significantly improves the spatial utilization efficiency of the furnace. Two crucible designs—a square 4-hole graphite crucible and a conventional cylindrical 9-hole crucible—were compared through industrial-scale experiments and three-dimensional electrothermal coupled simulations. In the experiments, 61 t of calcined petroleum coke (CPC) powder was used for the 4-hole configuration, while 23.6 t was used for the 9-hole configuration. The numerical model was validated against industrial measurements, with deviations within ±5%. Thermal uniformity in the crucible holes was quantitatively evaluated using key indicators, including the temperature difference coefficient and the coefficient of variation. Results show that the 4-hole configuration achieves a more compact layout, reducing inter-crucible voids and resistance material usage. Although the 9-hole design exhibits slightly better single-hole uniformity at certain positions, the 4-hole design increases batch productivity by 2.6 times and lowers specific energy consumption by 33% (7,500 vs. 11,200 kWh/t). Energy allocation analysis indicates that at peak product temperature, 21.9% of the total enthalpy is stored in the CPC powder region for the 4-hole configuration, compared to 14.9% for the 9-hole, while the latter retains 44.5% of energy in non-productive furnace structures. Although the 4-hole configuration results in a slight reduction in temperature uniformity, the substantial improvements in productivity and energy efficiency make it more suitable for large-scale industrial production.
Li et al. (2026) studied this question.