Abstract In an air separation apparatus which comprises a reversing heat exchanger, an air liquefier, a single column rectifier provided with a condenser-evaporator and a cold generation device and wherein air is cooled in the reversing heat exchanger and liquefied in the air liquefier, the liquefied air is rectified in the single column rectifier to separate into liquid air abundantly containing oxygen and highly pure nitrogen gas, the liquid air being subjected to heat exchange in the condenserevaporator, the resulting gasified air being subjected to heat exchange in the air liquefier and sent through the reversing heat exchanger to the cold generation device and the resultant liquefied air being sent through the air liquefier and the reversing heat exchanger to release, a process for controlling the generation of cold which is characterized in that a by-pass channel is provided for communicating a position on a passage between the condenser-evaporator and the air liquefier and a position on a passage between the cold generation device and the air liquefier, a control valve is provided on the by-pass channel and the opening degree of the control valve is automatically controlled so as to regulate appropriately the flow volume of the gaseous air passing through the by-pass channel whereby the level of the liquid air in the condenser-evaporator is kept constant and the rectification of the liquefied air in the single column rectifier is carried out under stable conditions.
The improvement as claimed in claim 1, wherein the control means stops the control valve at the time when the pressure on the evaporation side of the condenser-evaporator has varied to a certain extent from a set value so as to control the time lag during recovery of the liquid level.
Claim 2
Independent Claim
177 words
A method for automatic control of an air separation apparatus having a single column rectifier provided with a condenser-evaporator which comprises flowing vaporized air from the evaporator side of said condenser-evaporator through an air liquifier, a heat exchanger and an expansion type cold generation device and then back through said air liquifier, by-passing a portion of the vaporized air through a control valve from the evaporator condenser to the output side of the cold generation device, changing the degree of opening of the control valve in response to the level of liquid air on the evaporation side of the condenser-evaporator for controlling the flow of the bypassed part of the vaporized air to adjust the flow ratio of said part relative to that of the other part of said vaporized air which is passed through a cold generating device and fixing the amount of opening of the control valve when the pressure on the evaporation side has varied to a predetermined extent from the pressure existing before the change of the degree of opening of the valve.