An investigation on the effect of the start-up condition on reverse-flow monolith reactor for production of sysgas by partial oxidation of methane

• Main Author: Cam Tuan, Huy Phan
• Format: text
• Language: English
• Published: Animo Repository 2008
• Subjects: Synthesis gas; Syngas; Oxidation; Methane; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/3732; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=10570&context=etd_masteral
• Institution: De La Salle University

Reverse-flow operation has been recognized as suitable for weakly exothermic reactions, such as partial oxidation of methane (POM) to produce syngas. Many studies on reverse-flow reactor have been conducted. However, not many investigations have been extensively done on the effect of start-up conditions and procedures on the reverse-flow reactor. This study, therefore, aims to understand the behavior of the catalytic reverse-flow reactor in start-up stage. Reverse-flow operation has been presented since the 70s as a means to carry out reactions in a fixed-bed of catalyst. The cost of production could be considerably decreased by employing a reverse-flow system. In some recent decades, the reverse-low reactor has been paid much attention. However, the operation, especially the start-up procedure and initial conditions were only reported sparsely in few studies. Although, it is proved that the start-up procedure and initial conditions have the very important effect to determine the final state in other kind of the reactor. By analyzing the modeling of reverse-flow reactor, the start-up procedure and initial conditions were recognized that they also affects to final state of reactor. Therefore the experiment on reverse-flow reactor which focused on the start-up procedure and initial conditions was done to obtain the similar effects to the modeling. The catalyst used for the reverse-flow reactor was Ni/MgO/ -Al2O3 catalyst which was coated on the structure monolith surface by wash-coating. The effects of initial temperature (500, 600, 650, 700, 800oC), start-up procedures and operating parameters (flow rate, ratio of methane and oxygen, switching time) on the start-up behavior of reverse-flow reactor was investigated. The reactor temperature was measured by the thermocouple at two positions: at the center and at the boundary of the catalyst, which were recorded by a data logger. The concentration of the product (outlet gas) was analyzed by gas chromatography (GC). Based on the recorded temperature and GC results, the cyclic steady state was determined. The results showed that the initial temperature profile had a significant effect on the ignition of the reactor and the final state of the reverse-flow reactor. It also affect on the transition to cyclic steady state. At the lower flowrate, the effect was obvious: the number of half cycles necessary to approach cyclic steady state increased with increasing initial temperature. The effect of the procedure by which the feed gases were introduced into the reactor was also investigated. The results did not indicate any obvious difference for the final cyclic steady state when changing the start-up procedure.