Thermal Performance Analysis of Materials and Configurations for Cylindrical Sidewalls of Charcoal Kilns

Abstract

Most of the charcoal in the world comes from small and medium-sized producers, using rudimentary carbonization kilns that require significant time or energy during the heating and cooling stages of the process. Despite advances in improving the performance, the influence of materials used in the sidewalls of these kilns has been scarcely studied. Therefore, based on numerical simulations, the present study analyses the thermal performance of cylindrical sidewalls composed of combinations of metallic materials, ceramic materials, and insulating blankets grouped in three configurations: configuration I (sidewall with just one material), configuration II (sidewall with two materials assembled in series), and configuration III (pivoting sidewall). Results were encouraging, especially when comparing kiln configuration I with the novel configuration III. Simulations suggested that the proposed configuration III could reduce the heating time by 62%, the cooling time by 91%, the heat supplied to sidewalls by 80%, and the heat loss to the external environment by 99.7%. The save of wood charged into the charcoal kiln grew up to 7.3 times, varying the thickness of the inner layer of the sidewall.

The Effect of Clay Insulator Use on Corn Cob Carbonization Reactor Heat Loss

“…Meanwhile, heat absorption effectiveness reached 11.67% (for reactors without insulators) and 13.87% (for reactors with insulators), as shown in Figure 7. Valentim et al [10] confirmed the effectiveness of using insulators in carbonization reactors by demonstrating significant reductions in heating time. These reductions ranged from 66.0% to 99.7% when using different configurations of insulators in the reactors.…”

“…The presence of a moderate temperature difference ranging from 15 to 19℃ suggests that the clay insulators used to line the outer wall of the reactor may not be optimal because the water contained in the clay insulator evaporates due to heat transmission during the carbonization process from the walls to the insulator. This condition leads to the formation of cracks in the insulator, which facilitates the escape of heat into the ambient environment and consequently impacts heat loss [10].…”

“…The reactor heat loss is measured in the carbonization process by calculating the energy loss in the outer walls during the combustion process. Valentim et al [10] investigated the thermal performance of cylindrical sidewalls of charcoal kilns made from various materials and configurations. They discovered that implementing the new configuration significantly reduced the duration of heating and cooling, the amount of heat supplied to the sidewalls, and heat loss to the ambient.…”

Comparison of Technical and Operational Conditions of Traditional and Modern Charcoal Kilns: A Case Study in Italy

“…The natural cooling of the product requires a long time, drastically reducing productivity [1,22,24,25]. Given that the qualitative characteristics of the charcoal are not affected by cooling, this must take place as quickly as possible [25,92]. In the literature, several solutions are presented to accelerate the cooling process.…”