چكيده به لاتين
The Methanol to olefin (MTO) process has been considered due to the consumer market of ethylene and propylene and the use of non-petroleum raw materials. Accordingly, a full understanding of the reaction mechanism and transfer phenomena in this process is necessary for its industrial implementation. In the present study, MTO process in the pilot scale Dalian Institute of China reactor, has been numerically simulated using the Eulerian- Eulerian approach along with the particle kinetic theory. The simulation of this multiphase system has been performed in two parts of hydrodynamics and MTO reaction, isothermally. The accuracy of the numerical model developed for the hydrodynamics and reaction has been confirmed by comparing the results with laboratory studies of other researchers in this field. Due to the importance of proper gas flow distribution in this catalytic reaction, in the hydrodynamic simulation section, the effect of two types of distributors on the hydrodynamic distributions of gas and solids in the dense bed region, which is the main reaction zone, are investigated. After hydrodynamic simulation, the gas flow pattern inside the reactor is investigated by injecting and tracking a gas tracer and the methanol conversion in the reactor is estimated using the gas residence time distribution information. Based on the results, the porous distributor, compared to the perforated plate distributor, causes a more uniform distribution of gas and solids and produces smaller bubbles in the bed. According to the results of the gas residence time distribution in the bed, the gas flow pattern in the current fluidized bed reactor greatly deviates from the ideal flow patterns, and both plug and mixed flow patterns can be observed in the reactor. The mean gas residence time was calculated using the gas residence time distribution data within the dense region of reactor is 2.95 s, which is very different from the theoretical value of 1.315 for the ideal gas flow in the mixed flow reactor. The reason for this discrepancy can be due to not considering the effect of solid phase on gas phase, for example, the resistance that solid phase creates against gas motion or back mixing of gas, in calculating the average residence time of gas using the theoretical relation. The conversion calculated using the gas residence time distribution data is 100%, which is higher than the value reported by Lu et al. (98.3126%), that could be due to the deviation of the gas flow inside the reactor from the completely mixed flow.
