Flow rate response in passive production of synthesis gas from liquid methanol using a combined packed bed

Abstract

Passive production of synthesis gas from liquid methanol was investigated using a combined packed bed reactor. Small porous particles were packed into the lower part of a reactor tube to draw liquid due to capillary action, while large porous particles were packed into the upper part to reduce the flow resistance of the reacting gas. When the packed tube was heated from the side surface, a liquid region, two-phase region, and dry region were formed along the tube axis. Upward liquid-vapor flow was induced by enhancement of the capillary pressure due to evaporation. The mass flow rate in the steady state increased in proportion to the heating rate and was as much 2.3 times the vapor production rate that corresponded to the heating rate of the two-phase region. Such a large flow rate was presumed to be due to the heat conducted from the dry region to the two-phase region as the result of a large temperature gradient produced in the dry region. The process in the packed tube was analyzed using a one-dimensional model based on the mass, force, and energy balances for each phase, where the heat conduction in the axial direction was accounted for. The calculated temperature profile and the methanol conversion agreed with those measured experimentally. A significant portion of the heat supplied to the drying region was distributed to produce vapor, the ratio of which was dependent on the magnitude of the conduction factor, ΣA_ik_i. The effects of the axial heat flow on the mass flow rate (vapor production rate), methanol conversion and the gas production rate are discussed.