Numerical investigation on the scale-up and optimization of coal-supercritical water fluidized bed gasification reactors for hydrogen production

Abstract

The supercritical water fluidized bed (SCWFB) is an ideal reactor for the industrial application of the technology of coal gasification in supercritical water (SCW) for hydrogen production. To address the lack of scale-up theory for SCWFB reactors, this study develops a new coal-SCW particulate flow reaction model and performs systematic numerical investigations on the effects of reactor size scale-up (2-, 5-, and 10-fold) and operating parameters scale-up. Results demonstrate that as the reactor size increases, the high-quality fluidization characteristic of SCWFB get maintained, while coal gasification efficiency (CE) gets enhanced. At the 10-fold scale-up level, CE increases by more than 4 % compared to the original reactor, and efficient gasification can be achieved for high-concentration coal slurries (60 wt %) with the CE of 93.98 %. Moreover, through optimization of feedstock injection velocity and multi-nozzle configurations, the temperature distribution homogeneity and CE get further enhancement in scaled-up SCWFB reactors.