## 3 Results
### Determination of the Minimum Velocity of Bubbling Regime
Figure 9: Gas velocity contour at the outlet of the simulated cell of the distribution device (yellow face in Figure 3. The general view of the gas velocity contour practically would not change with time, but the velocity in the red region varies within a range of 1.1 to 1.2 m/s). Figure 11: Visualization of the obtained solution for a gas velocity of 3 m/s at \(t=0\) and \(t=0.15\) s, respectively. Figure 12: Visualization of the obtained solution for a gas velocity of 3 m/s at \(t=0.39\) and \(t=0.45\) s, respectively. Figure 13: Visualization of the obtained solution for a gas velocity of 3 m/s at \(t=0.54\) and \(t=0.57\) s, respectively; particles highlighted by a red circle are located at a distance of under 1.5 cm from the support grid. Determination of the Effect of the Fluidization Regime on Particle Heating and the Effect of High Gas Temperature on the Fluidization Regime Itself  
Further, simulation of particle heating at a temperature of 923 K, which is the average value of the temperature range of the high-temperature catalytic combustion of exhaust gases, was carried out [68]. The gas velocity was assumed to be equal to the minimum fluidization velocity (1 m/s), which would allow for a visual comparison of heating of the stationary and bubbling layer. The approximate heating time of the entire particle layer was about 72 s. Figures 14-19 shows the results of simulating the process at certain times from the beginning of the simulation, namely 0, 5.85, 24, 36, 48, and 72 s respectively. Figure 16: Dynamics of particle heating (**left**) and gas temperature (**right**) at \(t=24\) s. The gas temperature at the inlet to the cell is 923 K at a gas velocity of 1 m/s. Figure 9.0 Dynamics of particle heating (**left**) and gas temperature (**right**) at \(t=0\) s. The gas temperature at the inlet of the cell is 923 K at a gas velocity of 1 m/s. Figure 9.1 Dynamics of particle heating (**left**) and gas temperature (**right**) at \(t=5.85\) s. The gas temperature at the inlet of the cell is 923 K at a gas velocity of 1 m/s. According to Figures 14-19, it can be seen that at the middle of the process, almost half of the solid phase has been heated up to the required temperature. As the particles heat up, the temperature difference between them and the gas decreases, and at the same time the driving force of the heat transfer decreases, which leads to a significant increase in the heating process time for this layer. From about 24 s of the process, the gas flow would not transfer all its heat to the particles (i.e., at the outlet of the particle layer, the gas had a higher temperature than the particles in the upper part of the layer, which is noticeable on the gas temperature contour starting from Figure 15). This heat rises with the flow to the next layer of particles and is spent on heating the layer. Thus, if 72 s are spent on heating the first layer of particles from the beginning of the process, then it requires less than 144 s to heat the two layers  
Figure 9.2 Dynamics of particle heating (**left**) and gas temperature (**right**) at \(t=72\) s. The gas temperature at the inlet of the cell is 923 K at a gas velocity of 1 m/s. Figure 9.3 Dynamics of particle heating (**left**) and gas temperature (**right**) at \(t=36\) s. The gas temperature at the inlet of the cell is 923 K at a gas velocity of 1 m/s. of particles (two times 72 s). Based on this, we believe that the heating time of all particle layers under current conditions will be less than 288 s (four times 72 s). The process can be accelerated by carrying it out in a bubbling regime. The greater gas consumption, its active mixing with particles, and their uniform heating will ensure a higher temperature difference between the gas and the particles (i.e., the driving force of the heat transfer process increases), despite the reduced contact time caused by the increased gas velocity. Further simulation was carried out under the same conditions as the previous one, except for the gas velocity, which was increased to 3 m/s.