## 1 Introduction
Distribution devices make it possible to structure the bed, to get rid of the formation of particularly large bubbles that negatively affect the process, and to further intensify mixing [54; 55; 56; 57; 58; 60]. The effect on the hydrodynamics of several types of distribution device designs was studied experimentally and by simulation in [54; 55; 56; 57; 59; 60]. In these works, the effect of various perforated plates and louver baffles on the behavior of the fluidized bed was studied. However there are few studies of the effect of internal devices in the form of vertical baffles of various configurations on the hydrodynamics of a fluidized bed. At the same time, vertical baffles are less susceptible to erosion than perforated plates and have less effect on the abrasion of particles, and also allow for controlling the operating regime of each layer independently of each other in the presence of several separated layers of particles in one reactor if it is possible to control the flow of the medium using a distribution device [54; 55; 56]. In addition, the variety of distribution devices, the properties of the media and solid particles make it necessary to select the parameters of the model when simulating new equipment and check the adequacy of the description. An example of a reactor with vertical baffles is shown in Figure 2. This is a reactor with a fluidized bed of a spherical polydisperse catalyst. The distribution internal device is a grid consisting of vertical baffles forming cells with a 90 \(\times\) 90 mm base and 60 mm high. This design is similar to the grid design presented in the patent [61]. It considers a polymerization reactor with a fluidized catalyst bed [61]. The liquefying agent is a carrier gas with liquid hydrocarbons dispersed in it [61]. The distribution device is located under the support grid of the fluidized bed and is used as a gas distribution device, which is designed for the uniform distribution of gas across the section of the fluidized bed and prevents the accumulation of liquid hydrocarbons at the walls of the reactor [61]. However, such a design has a number of disadvantages inherent to unarranged fluidized beds: the possibility of the formation of large gas bubbles and gas-solid back mixing, disrupting the reactor operation; while in the presence of inhomogeneity of the gas velocity field, the solid phase will be accumulated in areas with a lower velocity, which also disrupts the reactor operation regime. To solve these problems, this work proposes to \"relocate\" the grid and use it to arrange the bed, i.e., switch over from the design presented in the patent [61] (Figure 2a) to the design proposed in this work (Figure 2b). However, in case of placing the particle bed in a single grid stretched along the reactor, it will be possible to achieve only two regimes of operation: either pneumatic conveyance or slugging (Figure 1). To avoid this, it was proposed in this work to divide the particle layer into four horizontal layers (Figure 2c). To do this, each layer of particles must be located in a separate section of the distribution device consisting of vertical baffles. The experimental determination of the hydrodynamic properties of fluidized beds is reduced to determining the porosity, velocity, and trajectory of particles at a certain point of the laboratory unit area. For dense fluidized beds, the key factor affecting these parameters is not the medium-particle interaction, but the particle-particle interaction. For this reason, the DEM was applied in this work, which allows one to more accurately, in comparison with the TFM, take into account the interactions of particles with each other, as well as the walls of the reactor and the distribution device, to avoid large computational costs.