چكيده به لاتين
Fluidized bed reactors have many uses in the industry. One of the disadvantages of these reactors is that after ashort time of reaction time, the catalysts that accelerates the reaction is lost. For this reason, commonly used to solve this problem, two reactors are used together: one for the reaction, and another for the catalyst to be restored and returned to the reactor. By developing a two-zone fluidized bed reactor, this problem has been resolved, and in addition to releasing the extra space resulting from the use of two reactors, the speed of the reaction process and the recovery is further increased. The reactor upper zone, the reaction zone and the lower region of the reactor are the catalytic recovery region. Therefore, the catalyst particles should be continuously displaced between the two reactor regions. Hence, the particle mixing in this type of new reactor is very important. To understand the degree of mixing performance of particles in a fluidized bed reactor, a criterion called the mixing index is used. Various mixing indices have been presented so far, the most famous of which are the Lacy mixing index, the nearest neighbor and the nearest distance. This is a numerical benchmark between zero and one, which is closer to one, mixing quality is better and more. In this study, the nearest closure method was used to examine the mixing of particles in a two-zone fluidized bed reactor. For this purpose, the computational fluid dynamics simulation method has been used with the Eulerian- Euleran approach and has been investigated by processing the data obtained from the simulation of the mixing of particles in the reactor. Among the other issues examined in this paper is the study of the residence time distribution in each region and their particle tracking. In order to prevent the presence of large particles in the bed, the bed entry speed must be high and the number of particles in the bed will cause better particle displacement and optimize their residence time in each area of the bed.
