The effect of a submerged partition plate on improving the gas-solid flow robustness and stability in a three-dimensional spout-fluid bed with multiple inter-connected chambers is numerically investigated by means of computational fluid dynamics coupled with discrete element method (CFD-DEM). Notably, multiple-chamber beds are necessary in scaling up the spout-fluid bed. The influence of plate height on gas-solid distribution, spout-annulus interaction and chamber interaction are also studied to optimize the design. The results demonstrate that inserting a partition plate with height above a certain threshold can effectively improve the stability of spouting and uniformly re-distribute the flux load in each chamber, giving rise to parallel fountains and lower circulation flux of the solid phase. Results indicate that the plate height should be at least 80% of the packed bed height investigated, with the most optimal being about 92% based on steady spouting, and the maximum solid and gas exchanging fluxes between the chambers. (c) 2016 American Institute of Chemical Engineers AIChE J, 63: 485-500, 2017