Modeling of air gasification of dark fermentation digestate in a downdraft gasifier

The paper presents the results of numerical simulation of the gasification process in a downdraft gasifier to produce syngas with high hydrogen content. For the first time, the possibility of using dark fermentation digestate as a feedstock for thermochemical con -version using air as an oxidizer at equivalence ratio (ER) of 0.45, 0.55 and 0.65 was inves-tigated. Modeling of the gasification process was carried out in the software package Comsol Multiphysics. As a result of numerical studies, the concentrations of the main components of the syngas were obtained. The syngas yield at air gasification was 1.8 m3/kg. At the same time, the combustion heat of the generated gas varied from 3.1 to 3.9 MJ/m3 with the molar ratio (MR) being in the range from 3.1 to 3.9. The maximum content of hydrogen (26.94%) in syngas was achieved at an ER of 0.45. The hydrogen production efficiency HPE ranged from 23.8 to 27.3%. The thermal power that can be obtained from the syngas ranges from 47 to 59 kW. Carbon conversion efficiency coefficient (CCE) was 23.6-28.8%. Based on the design calculation, the main geometric parameters of a downdraft gasifier for the production of syngas from anaerobic digestates were obtained.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.