Air separation system

Abstract

The air separation system can include: a process control unit 201 for controlling components constituting the air separation system; an oxygen concentration estimating unit 202 for estimating, by calculation, the oxygen concentration of oxygen-enriched liquid that accumulates in a column bottom portion of the higher-pressure column; a flow rate estimating unit for estimating, by calculation, the flow rate of oxygen-enriched liquid that has been discharged from the column bottom portion of the higher-pressure column and that is to be introduced into a distillation portion of the lower-pressure column; and a target temperature calculating unit for calculating a target temperature of an argon extraction portion on the basis of the flow rate of feed air that has passed through at least a portion of the main heat exchanger 1 and that is to be sent to an expansion turbine, the oxygen concentration of the oxygen-enriched liquid, and the flow rate of the oxygen-enriched liquid.

What is claimed is: 
     
         1 . An air separation system comprising:
 a main heat exchanger;   a higher-pressure column into which feed air that has passed through the main heat exchanger is introduced,   a first condensing unit for condensing gas discharged from a column top portion of the higher-pressure column,   a lower-pressure column into which oxygen-enriched liquid discharged from a column bottom portion of the higher-pressure column is introduced, and   a crude argon column into which an argon-containing oxygen-enriched gas-liquid substance discharged from an argon extraction portion, which is an intermediate stage of a distillation portion of the lower-pressure column, is introduced, and also provided with:   a process control unit for controlling components constituting the air separation system;   an oxygen concentration estimating unit for estimating, by calculation, the oxygen concentration of the oxygen-enriched liquid that accumulates in the column bottom portion of the higher-pressure column;   a flow rate estimating unit for estimating, by calculation, the flow rate of the oxygen-enriched liquid that has been discharged from the column bottom portion of the higher-pressure column and that is to be introduced into the distillation portion of the lower-pressure column; and   a target temperature calculating unit for calculating a target temperature of the argon extraction portion on the basis of the flow rate of the feed air that has passed through at least a portion of the main heat exchanger and that is to be sent to the expansion turbine, the oxygen concentration of the oxygen-enriched liquid, and the flow rate of the oxygen-enriched liquid.   
     
     
         2 . The air separation system according to  claim 1 , wherein the process control unit is configured to control a replenishment amount flow rate of liquid nitrogen, and/or the flow rate of reflux liquid, such that the measured temperature of the argon extraction portion reaches the target temperature.