Gas-solid fluidized beds are widely used in processes for energy. In all these processes the short-range (van der Waals forces) and medium-range (electrostatic) particle-particle interaction forces may have a strong influence and reduce the operation energetic efficiency. In these processes electrostatic charge generation is undesired and needs to be minimized as much as possible. Due to the very nature of gas-solid fluidization, which involves significant particle-particle and particle-reactor wall interactions the occurrence of electrostatic charge generation, is almost unavoidable. The overall process upsets associated with this phenomenon includes particle agglomeration, reactor wall fouling generated by particle-wall adhesion, defluidization and electrostatic discharge. Generation of high-voltage electrical fields could cause electrical interference, adversely affecting process instrumentation, physical shocks to operating personal and, most significantly, fires, explosions and therefore be a major hazard. The excess accumulation of electrostatic charges can have a severe impact on fluidized-bed dynamics, particle mixing, and fines elutriation which is a major cause of inefficiency. For particles the van der Waals forces can have an effect, as it is known for the cohesive powders (very fine particles), combined electrostatic charges. In that case, the short-range interactions lead to attractive forces between the particles and consequently modify the bubble size and thus the macroscopic behavior of a fluidized-bed reactor. Depending on the process requirements, the particle size of the solid material ranges from several microns to few millimeters. The objective of this project is twofold: to develop a new experimental technique to characterize the coupling between hydrodynamics of the gas-solid suspension and inter-particle short and medium-range action forces in fluidized bed reactor and to develop CFD models through a multi-scale approach to take into account these forces to simulate pilot plant reactor in order to design, to control the process and to optimize industrial fluidized bed reactors. In this project, multi-scale numerical and experimental approaches are coupled. Mathematical models to represent inter-particle forces at micro-scale will be implemented in the Euler-Euler formalism at macro-scale scale according to the kinetic theory of granular material. Euler-Euler simulations will be carried out and the results will be compared to the hydrodynamic measurements realized on a fluidized bed mock-up submitted to inter-particle short and medium-range action forces. The hydrodynamics measurements will be carried out according to a new technique never applied, to our knowledge, to fluidized bed in Europe. This technique, called Electrical Capacitance Volume Tomography (ECVT), provides 3D non-intrusive measurements of the flow structure. This technique will be coupled to measurements of electrostatic charge of the particles and the wall. When the Euler-Euler simulations are validated, numerical simulations on industrial scale will be carried out. This project involves the LGC and the IMFT, which have strong complementary approaches and skills on the fluidized bed. It allows the coordinator to develop a real autonomy and his own research activity. The originality of this project lies in several points: 1-Experimental measurements on particles with different electrostatic charges from particles of different size and different materials. 2-Local non-intrusive measurements of gas-particle suspension hydrodynamics by ECVT. 3-ECVT system applied to fluidized bed submitted to electrostatic and van der Walls forces. 4-Three dimensional numerical simulations of dense fluidized bed influenced by inter-particle forces. 5-Coupled experimental, theoretical and numerical approaches to study inter-particle short and medium-range action forces in fluidized bed coupled in the same project