Pneumatic conveying is an important operation used in many industries to transport granular materials from one place to another. In recent years, the combined approach of the discrete element method (DEM) and computational fluid dynamics (CFD) has been widely used to understand and quantify this flow system but considering mainly specific short pipelines. This paper presents a CFD-DEM model that can be used to simulate large-scale conveying systems. The model also considers the effect of air compressibility related to long-distance transportation. The validity of the model has been verified by comparing the predicted and measured pressure drop of a dilute-phase conveying system at different solid and gas flow rates. The system consists of seven horizontal pipes, two vertical pipes, and eight bends, the total length of which is 102 m. The predictability of the model is also demonstrated in capturing different roping phenomena within different bend configurations.