Hydrodynamics and OCM reaction performance in a bubbling fluidized bed reactor and a riser reactor

Abstract

The reasonable reactor design is of great importance for increasing the C2 yield (C2H4 and C2H6) of the oxidative coupling of methane (OCM), and the OCM reactor should remove the heat released in reactions quickly and efficiently and minimize the consecutive reaction of ethylene to carbon oxides. The fluidized bed reactor is characterized by excellent heat transfer, superior mass transport, and large handling capacity, while fewer studies focused on large-scale fluidized bed reactors for the OCM reaction. Therefore, large cold-model experiments and computational fluid dynamics simulations were conducted to investigate hydrodynamics and the OCM reaction performance in a large-scale bubbling fluidized bed (BFB) and a large-scale riser. In the BFB reactor, consecutive reactions of ethylene are acute because of the strong gas back-mixing, high solids holdup, and non-uniform solids distribution. While the consecutive reactions of ethylene are negligible due to the plug flow structure and low solids holdup in the riser reactor. Further, both reactors can achieve isothermal operation for the OCM process. The C2 selectivity of 45.4% and C2 yield of 21.1% are obtained in the riser reactor, increasing by 20.3% and 5.8% individually than that in the BFB reactor. This study provides useful information and reference to the OCM reactor design and commercialization.