Method and apparatus for controlling the metallurgical processes in an oxygen-containing atmosphaere

摘要

1,225,690. Automatic control of gaseous atmospheres containing oxygen. GENERAL ELECTRIC CO. Sept.30, 1968 [Oct. 18, 1967], No. 46226/68. Heading G3R. The oxygen content of the atmosphere of a processing vessel 11 is detected and used to control the supply of gas to the vessel to optimise the process. In an annealing furnace Fig. 2 gas is supplied by a generator 14 and the oxygen partial pressure is detected, by a cell 15, at various points through the furnace. The output of cell 15 is applied to a controller 12 which may be a digital computer with suitable analogue/digital converters. The flow of gas to the furnace is detected and controlled by a device 16 in accordance with an output signal from the controller 12. The controller also controls the generation of gas e.g. the air/fuel mixture supplied to the generator 14 and is responsive to temperatures within the furnace. The controller maintains the oxygen partial pressure below that necessary to oxydize the metal. In an application to a reduction process Fig. 4 (not shown) in which the oxide to be reduced passes continuously through the reduction vessel and reducing gas flows in the opposite direction and is recirculated, the oxygen partial pressure is detected at the inlet and outlet of the vessel and the computer responds to the partial pressures, the temperature and also the rate at which the oxide passes through the furnace. It controls the gas supply as before, as well as the proportion of recirculated gas. In application to a sintering furnace the controller maintains the oxygen partial pressure above a value at which one oxide is produced and below a value at which a different oxide would be produced. In application to a carburizing furnace Fig. 6 (not shown) the computer controls each individual stage in production of the carburizing atmosphere. The oxygen measuring cell is of the type comprising a calcium stabilized zirconium -oxide electrolyte having electrodes attached to opposite surfaces respectively exposed to a reference gas such as air and the gas to be analysed.