Abstract: A method and apparatus for melting thermoplastic material is disclosed utilizing, in a preferred embodiment, a vessel having a bottom wall and upstanding sidewalls. A protective liner for the vessel is provided, being formed of corrosion resistant material. The furnace may include both through-the-batch and floor electrodes, and also hot spot fining to a conductive outlet channel.A method is set forth for operating the furnace described herein utilizing symmetrical, below the batch heat dissipation for accelerated melting. In order to protect the liner, which in some instances may be fabricated from an oxidizable refractory metal, start-up burners are operated under a reduced oxygen supply.
Abstract: An apparatus comprising a number of rotatable vanes, situated around the periphery of an annular duct, which can be opened and closed so as to control the flow of gas entering the duct. The axis of rotation of the vanes is parallel with the axis of the duct. The vanes are divided into groups, each vane of a group being connected to another vane of that group and each group of vanes being connected to a common drive means so that rotation of the drive means causes the vanes to open or close in unison.