Abstract: A method of and apparatus for optimizing the rate of material air supply to an air separation plant, for preserving a stable operation of the plant, through stabilizing heat balance and material balance in the plant irrespective of variation in the flow rate of a gas through an expansion turbine incorporated in the plant and the flow rate of product gases so as to optimize the purity and amount of produced gas. The control for the optimization is performed making a ratio of the difference between the flow rate of the material air and the flow rate of the gas through the expansion turbine to the flow rate of the product gases, as an essential factor for the control.

Abstract: Disclosed is a new and improved method for automatically balancing the temperature of a plurality of reversing heat exchanger units provided in parallel relation with each other. The balancing method comprises the steps of: detecting the temperature in portions of each core of the reversing heat exchangers whenever the flow paths of a feed stream and a heat medium stream are changed over, calculating a mean temperature of each core from the said detected values during the most recent certain changeover period from the current time point, calculating a mean temperature for all exchangers from the said calculated mean temperatures of each core, calculating deviation and deviation trend in temperature of respective exchangers depending on a difference between the mean temperature of each core and the mean temperature of all exchangers, feeding back a system deviation in dependence on the said deviation and deviation trend to control valves for balancing the temperature of reversing heat exchangers.