TRANSIENT EXPERIMENTS AND MODELING OF THE CATALYTIC COMBUSTION OF METHANE IN A MONOLITH REACTOR

The combustion of methane with an excess of oxygen was examined under transient conditions in a catalytic monolith reactor, The reaction exh ibited a sharp light off in the inlet region of the reactor, and essen tially complete combustion was attained. The experimental reactor was modeled using a comprehensive two-dimensional finite element simulator previously developed. Theoretical and observed temperatures were well matched in the reactor following complete combustion. The simulator p redicted a response of the order of 1-2 s faster than that observed ne ar the inlet to the reactor where the reaction was occurring. Similar agreement was found for startup and shutdown of the reactor, as well a s for a situation where the supply of methane to the reactor was inter rupted for a period of 16 s. Analysis of the temperature profiles duri ng startup operation showed that the reactor exhibited light off near the entrance, with the heat wave being propagated toward the reactor e xit. The Nusselt number exhibited a steady state value of the order of 4, with different values obtained during transient operation. The rea ction does not become completely mass transfer controlled in spite of the rapid rise of temperature in the ignition region.