COOLING METHOD IN TWO-CHAMBER BOX-TYPE ANNEALING FURNACE

摘要

PURPOSE:To increase the pressure in a cooling chamber and to use effectively the recovered gas for purging to the other furnace by introducing a liquefied gas into the chamber to increase the cooling rate when the cooling rate by the cooling gas under circulation decreases down to a prescribed rate or below and recovering the liquefied gas to the outside of the chamber. CONSTITUTION:The cooling gas such as gaseous N2 purged into a cooling chamber with a two-chamber box type annealing furnace is passed through a coil X to cool the coil and is thereafter led through a plenum chamber 2 to the outside of the cooling chamber. The gas is again introduced 5 into the cooling chamber after cooling 4. When the cooling rate of the coil X decreases down to a prescribed rate or below, liquid N2 12 is injected 10 into the cooling chamber to cool the coil X. The N2 evaporated by such injection increases the pressure in the cooling chamber by expanding in volume and therefore a part of the gaseous N2 is recovered to the outside of the chamber and the pressure in the chamber is maintained under a specified pressure. The recovered gaseous N2 is stored in a storage tank 16, etc. and is used for purging to the other cooling chamber which is emptied upon ending of cooling.