Bed not being fluidized at high inlet N2 temperatures

Grettings everyone,
As some of you may know, i Am performing a ligno-cellulosic 2D pyrolysis.

Im getting trouble sometimes because the fluid does not fluidized and remains static.The VTK shows no movement of the bed.
Ive been removing variables for the past few days, trying to look into the source of the problem. Removing the chemestry and the biomass entrance to the chamber leaves us just with just the hydrodynamics of the simulation, and the problem remains.
After a couple of days, i’ve notice that if i reduce the inlet temperature of the fluidizing gas (It is just N2) the VTK shows the corresponding movement.
Any insight would be apreciated.