Method and device for producing gaseous compressed oxygen having variable power consumption

Abstract

Variable production of compressed oxygen by means of low-temperature separation of air in a distillation column system having a high-pressure column and a low-pressure column. In a first operating mode, a first total air quantity is cooled in the main heat exchanger, and a first turbine amount is fed to the expansion to perform work. In a second operating mode, a second oxygen stream from an external source outside the distillation column system is introduced into the low-pressure column in a liquid state. There is less total air cooled in the main heat exchanger, and less air is fed to the expansion to perform work than in the first, operating mode.

1 . A method for producing gaseous compressed oxygen having variable power consumption by low temperature separation of air in a distillation column system that has a high-pressure column and a low-pressure column, in which
 feed air in the form of a total air stream is cooled in a main heat exchanger,   at least a part, of the cooled feed air is introduced into the high-pressure column,   a first oxygen stream from the low-pressure column is pressurized in the liquid state,   the pressurized first oxygen stream is vaporized or pseudo-vaporized and warmed in the main heat exchanger,   the warmed first oxygen stream is obtained as a gaseous compressed oxygen product,   a first substream of the feed air, before entry thereof into the main heat exchanger, is brought to a first high pressure which is at least 4 bar higher than the operating pressure of the high-pressure column,   the first substream is liquefied or pseudo-liquefied at the first high pressure in the main heat exchanger and subsequently introduced into the distillation column system,   a second substream of the feed air is brought to a second high pressure that is at least 4 bar higher than the operating pressure of the high-pressure column,   the second substream is cooled in the main heat exchanger only to an intermediate temperature,   the second substream that is cooled to the intermediate temperature is work-producingly expanded and subsequently introduced into the distillation column system,   wherein, in a first mode of operation
 a first total air amount is cooled in the main beat exchanger, 
 a first turbine amount, as first substream, is fed to the work-producing expansion, 
   and, wherein in a second mode of operation
 a second total air amount is cooled in the main beat exchanger, which second total air amount is less than the first total air amount of, 
 a second turbine amount is fed as second substream to the work-producing expansion which second turbine amount is less than the first turbine amount characterised in that 
   in the second mode of operation, a second oxygen stream is introduced from an external source outside the distillation column system into the low-pressure column in the liquid state and   in the first mode of operation, the first and second substreams are together boosted in a pair of parallel-connected boosters.   
     
     
         2 . The method as claimed in  claim 1 , characterized in that at least, one of the following conditions is met:
 the second total air amount is at least 5 mol % lower than the first total air amount,   a second turbine amount is at least 10 mol % lower than the first turbine amount.   
     
     
         3 . The method as claimed in  claim 1 , characterized in that
 in the first mode of operation, a third oxygen stream is taken off as liquid product from the low-pressure column in the scope of a first liquid oxygen amount and   in the second mode of operation, the third oxygen stream is taken off as liquid product in the scope of a second liquid oxygen amount which is lower than the first liquid oxygen amount,   wherein the second liquid oxygen amount is lower than the first liquid oxygen amount.   
     
     
         4 . The method as claimed in  claim 1 , characterized in that, in the second mode of operation, none of the process streams of the distillation column system is subjected to a cold compression. 
     
     
         5 . The method as claimed in  claim 1 , characterized in that the second turbine amount is zero. 
     
     
         6 . The method as claimed in  claim 1 , characterized in that the two boosters have a shared aftercooler or have an aftercooler each. 
     
     
         7 . The method as claimed in  claim 1 , characterized in that the total air stream consists of a first part and a second part wherein the second part consists of the first substream and the second substream, and in particular wherein the first part is fed without turbine expansion substantially in the gaseous state into the distillation column system. 
     
     
         8 . A device for producing gaseous compressed oxygen having variable energy consumption by low-temperature separation of air
 having a distillation column system that has a high-pressure column and a low-pressure column,   having a main heat exchanger for cooling feed air in the form of a total air stream,   having means for introducing at least a pan of the cooled feed air into the high-pressure column,   having means for pressurizing a first oxygen stream from, the low-pressure column in the liquid state,   having means for vaporizing or pseudo-vaporizing and warming in the main heat exchanger the pressurized first oxygen stream,   having means for producing the warmed first oxygen stream as a gaseous compressed oxygen product,   having means for bringing a first substream of the feed air, before entry thereof into the main heat exchanger, to a first high pressure which is at least 4 bar higher than the operating pressure of the high-pressure column,   having means for liquefying or pseudo-liquefying the first substream liquefied or pseudo-liquefied at the first high pressure in the main heat exchanger,   having means for introducing the (pseudo-)liquefied first substream into the distillation column system introduced,   having means for bringing a second substream of the feed air to a second high pressure which is at least 4 bar higher than the operating pressure of the high-pressure column,   having means for withdrawing the second substream in the main heat exchanger at an intermediate temperature,   having means for the work-producing expansion of the second substream that is cooled to the intermediate temperature,   having means for introducing the work-producingly expanded first substream into the distillation column system introduced   characterized by   means for introducing a second oxygen stream in the liquid state from an external source outside the distillation column system into the low-pressure column and by   a control device, by which the following process parameters are set:   in a first mode of operation
 a first total air amount which is cooled in the main heat exchanger, 
 a first turbine amount which is fed as first substream to the work-producing expansion, that in a second mode of operation 
   and in a second mode of operation
 a second total air amount, is cooled in the main heat exchanger which is less than the first total air amount, 
 a second turbine amount is fed as first substream to the work-producing expansion, which second turbine amount is less than the first turbine amount 
   an amount of the second oxygen stream which is fed to the low-pressure column in the liquid state, which amount is greater than the amount in the first mode of operation.   
     
     
         9 . A method for retrofitting a low-temperature air separation plant for producing gaseous compressed oxygen having variable power consumption by Low temperature separation of air in a distillation column system that has a high-pressure Column and a low pressure column in which
 feed air in the form of a total air stream is cooled in a main heat exchanger,   at least a part of the cooled feed air is introduced into the high pressure column,   a first oxygen stream from the low pressure column is pressurized in the liquid state,   The pressurized first oxygen stream is vaporized or pseudo-vaporized and warmed in the main heat exchanger,   the warmed first oxygen stream is obtained as a gaseous compressed oxygen product,   a first substream of the feed air before entry thereof into the main heat exchanger, is brought to a first pressure which is at least 4 bar higher than the operating pressure of the high-pressure column,   the first substream is liquefied or pseudo-liquefied at the first high pressure in the main heat exchanger and subsequently introduced into the distillation column system,   a second substream of the feed air is brought to a second high pressure that is at least 4 bar higher than the operating pressure of the high pressure column,   the second substream is cooled in the main heat exchanger only to an intermediate temperature,   the second substream that is cooled to the intermediate temperature is work-producingly expanded and subsequently introduced into the distillation column system,   wherein in a first mode of operation
 a first total air amount is cooled in the main heat exchanger, 
 a first turbine amount as first substream is fed to the work-producing expansion, 
   and, wherein, in a second mode of operation
 a second total air amount is cooled in the main heat exchanger, which second total air amount is less than the first total air amount of, 
 a second turbine amount is fed as second substream to the work-producing expansion which second turbine amount is less than the first turbine amount; 
   wherein   in the second mode of operation, a second oxygen stream is introduced from an external source outside the distillation column system into the low-pressure column in the liquid state and   in the first mode of operation, the first and second substreams are together boosted in a pair of parallel-connected boosters;   the retrofitting method characterized in that means are added for introducing the second oxygen stream into the low-pressure column.   
     
     
         10 . The method as claimed in  claim 9 , characterized in that a further booster is connected in parallel to an existing booster. 
     
     
         11 . The method as claimed in  claim 9 , characterized in that, apart from the means for introducing the second oxygen stream into the low-pressure column and optionally apart from the further booster, no, or substantially no, changes to the device are made. 
     
     
         12 . The method as claimed in  claim 2 , wherein the second turbine amount is at least 30 mol % lower, than the first turbine amount. 
     
     
         13 . The method as claimed in  claim 3 , wherein the second liquid oxygen amount is at least 50 mol % lower than the first liquid oxygen amount. 
     
     
         14 . The method as claimed in  claim 3 , wherein the second liquid oxygen amount is 100 mol % lower than the first liquid oxygen amount. 
     
     
         15 . The method as claimed in  claim 7 , wherein the first part is fed without turbine expansion substantially in the gaseous state into the high pressure column.