Effect of an axial-radial plate reactor modifications on a mega methanol plant production

Axial-radial flow plate reactors have been recently considered as efficient and practical types of reactors for methanol synthesis. Generally, an axial–radial reactor (AR) consists of two main parts namely the axial section and the radial section and the vast majority of the feed enters the radial section. Moreover, the structure of AR has a space above the axial part, which can add an adiabatic bed in the system. In this study, the performance of two novels AR configurations is investigated to improve the effectiveness of the axial–radial plate reactor. In the first configuration, the optimum length of the adiabatic bed is calculated and the adiabatic bed is located above the axial section inside the AR and is named IAAR. Therefore, in IAAR the feed of the axial section just enters the adiabatic bed and warms up. On the other configuration, the adiabatic bed with the optimum length is placed outside the reactor and is named OAAR. Therefore, in OAAR the total feed passes through the adiabatic bed, highly warms up, then cools to the optimum temperature in a heat exchanger, and finally enters AR. Two-dimensional mathematical modeling via orthogonal collocation on the finite element method is developed to compare the performance of two configurations. The results show that the maximum proportion of methanol produces in IAAR, which is approximately 3.8% higher than that produced in conventional AR due to utilizing an adiabatic bed inside the AR and superior gas distribution in the process. Momentum, mass, and heat equations are calculated and molar flow rates, mole fractions and temperatures are depicted along the radius and the length of the three configurations.

Dehydration of Methylbutenes to Isoprene. Part 3: Comparative Mathematical Analysis of Methylbutene Dehydrogenation in Axial and Radial Reactors

A mathematical model of the process of dehydrogenation of methylbutenes to isoprene was used for comparative analysis of energetic efficiency of two versions of modernization: (1) a system of consecutively connected two axial reactors with a fixed catalyst beds, and (2) adiabatic radial reactor with fixed catalyst bed. The purpose was to determine the dependence of yield (Y) and selectivity (S) to the target product on the heat energyQsupplied with vapor. In the two-reactor system, the best parameters (Y= 53.1 % andS= 82.9 %) were achieved atQ= 9.0 MJ/kg and contact time t = 0.8 s. At the same time, in the radial reactor the best performance (Y= 42.0 % andS= 86.1 %) was observed atQ= 7.8 MJ/kg andt= 0.8 s. Hence, the radial reactor consumes less heat energy (by 13.0 %) than the radial reactor for methylbutene dehydrogenation.