The inertial separator, developed for fluidized beds, is a key component for optimizing large installations that separate solids from gases. Despite industrial interest and numerous patents, few studies have been conducted on this subject. In this paper, the geometric arrangement conditions were studied and evaluated. The efficiency of separating solids from gas depends on several factors, such as the granulometry, density, particle size distribution, velocity, humidity, and temperature of the system. For the mid-range of fluidized bed boilers (1–20 MWth), the experimental study selected all data to be in the same condition as the industrial technology. The global performance of the system can be increased by 15% by selecting a better combination of the U-beam. Three rows of U-beams are a good compromise between performance and cost for high Reynolds numbers, while only two rows seem to be enough for lower Reynolds numbers.