| 摘要 |
PROBLEM TO BE SOLVED: To provide a control method for an apparatus for liquefying and separating air capable of following up drastic and frequent increasing/decreasing operation manipulation in a short time with a small error within an allowance without using additional equipment such as gas holder, gasifying force feed equipment or the like. SOLUTION: Operation of the apparatus for liquefying and separating air is controlled through basic control loops such as flow rate control of raw material air AIR, crude argon gas RAr, product oxygen gas GO2, low pressure product nitrogen gas GN2, intermediate pressure product nitrogen gas MGN2, reflux liquid nitrogen gas RLN2 to an upper column 9, liquid air LAIR1, liquid air for argon condenser LAIR2, liquid oxygen LO2 and the like, pressure control of a lower column 4 and the upper column 9, liquid level control in the lower column 4 and the upper column 9, or the like. A product concentration control of a model prediction control is also employed, particularly, the argon concentration in feed argon FAr and the oxygen concentration in the crude argon RAr are directly fed back to perform operation by an optimum control action based on its predicted value. Thus, load fluctuation is promptly followed up so that the product concentration is kept within the allowance.
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