Insight into reaction performance and product formation in a novel coal pyrolyzer of pilot-scale test

Abstract

The pyrolysis behavior of coal in a pilot-scale moving bed with internals is modeled through computational fluid dynamics (CFD) simulations. The temperature field, reaction field, volatile flow paths inside the reactor, and effects of the internal design and operating parameters on the tar yield are systematically investigated. The simulation results show that the central gas channel allows the majority of generated volatiles to laterally pass through the low-temperature bed layer. This not only enhanced the primary volatile generation reaction but also significantly reduced the secondary cracking of tar. However, the placement of the heat transfer plates had a dual effect. While the plates significantly enhanced heat transfer, thereby promoting primary reactions, they could cause the volatiles to bend towards the high-temperature zone near the plates, resulting in the partial loss of tar. The tar yield may decrease with an increase in the number or area of heat transfer plates. Furthermore, investigations into the operational parameters revealed that increasing the furnace temperature appropriately and reducing the mass flux of coal were favorable for the heat transfer and yield increase in tar.