Infrared furnace with muffle

摘要

An infrared furnace has a firing chamber in which a source of infrared energy is disposed and an elongated envelope transparent to the infrared energy extending through the firing chamber. The envelope has first and second open ends outside the firing chamber. First and second baffle chambers surround the respective first and second ends of the envelope. A product conveyor travels through the furnace via the baffle chambers and the envelope. Gas flow is prevented from the exterior of the furnace into the baffle chambers and from the firing chamber into the baffle chambers. Non-atmospheric gas is supplied to the baffle chambers so as to create therein a superatmospheric pressure which prevents gas flow into the baffle chambers from the exterior of the furnace. The non-atmospheric gas is exhausted from one of the baffle chambers, thereby inducing flow of the non-atmospheric gas from the other baffle chamber through the envelope. A seal chamber is disposed between each baffle chamber and the firing chamber such that gas leakage from the seal chamber to the baffle chamber and to firing chamber occurs around the periphery of the envelope. A packing is compressed against the periphery of the envelope and the walls of the seal chamber to minimize such leakage and the seal chamber is pressurized with non-atmospheric gas to prevent gas flow from the firing chamber to the baffle chamber.