The authors conducted pressure drop numerical simulations of multiphase gas-solid flow characteristics, within a fly ash pneumatic conveying system, in 620 MW thermal power plant. The objective of this study is to verify the OpenFOAM model by comparing the numerical results with pressure measurements taken along the considered pipeline. The numerical model is developed on the base of extensive experimental research of high-capacity long-distance pneumatic conveying system for Kolubara lignite fly ash. The numerical simulations of pneumatic conveying were performed using the Euler-Euler approach in OpenFOAM, that is twoPhaseEulerFoam solver, for the air mass flow rate of 5500 Nm3/h, the fly ash mass flow rate 77 t/h. The calculation input air pressure at the pipeline outlet was assumed to be as measured approximately 234 kPa, the air-ash mixture temperature was 373,15K, the mean ash particle diameter of 0.128 μm, and physical density of ash 2100 kg/m3. Numerical mesh is generated as an O-grid for the first two pipeline sections, first with a length of 90 m, a diameter of 0.2604 m, and an inclination of 1.885 degree, and the second with a length of 102 m, a diameter of 0.3097 m, and an inclination of 2.163 degree, while every mesh cell is substantially larger than the diameter of the ash particle. The applied Euler-Euler approach enables a comprehensive investigation of the complex dynamics involved in pneumatic conveying, considering the two-phase nature of the system and providing valuable insights into the particle behavior, pressure drop, and other key parameters. The comparison of the experimental and numerical model simulations data show good agreement regarding pressure drop. Although Euler-Euler model is complex in terms of necessary closure models, it might prove itself as reliable for simulated conditions in future studies.