Abstract: An improved system (10) conveys comminuted material from a source (12) to a vessel (14), especially for continuously conveying chopped poly(ethyleneterephthalate), or PET, into a methanolysis recovery reactor without entrainment of air into the reactor and without frequent jamming of the apparatus. A single rotary vane valve (36) is provided in the conveyance path at an inlet (38) to the vessel. The valve has clearances between the vanes (44) and the housing (48) larger than the smallest dimension of the comminuted material to prevent jamming of the rotor by PET flakes. The internal spaces (52, 47) in the valve are continuously purged with nitrogen at sufficient volume and pressure such that gases and fumes in the vessel are substantially prevented from passing upward through the valve. Nitrogen also flows from the valve countercurrently through the supply ducts (26, 30) to strip entrained air from the incoming material.