Air liquefaction separation method and apparatus

Abstract

Disclosed is an air liquefaction separation method and apparatus by which the apparatus cost can be reduced when liquid products are collected, the method including: a feed air compression step in which the whole amount of a feed air is a pressurized feed air having a first set pressure which is higher than the operating pressure of the intermediate pressure column; an adsorption and purification step in which impurities are adsorbed and removed from the pressurized feed air to obtain a pressurized purified air; a combining step for a circulating air in which the pressurized purified air and the below-described pressurized returned air are combined to obtain a circulating air; a cooling step in which a first branch air stream of the two divided circulating air is cooled at a first set temperature to obtain an air to be introduced into the intermediate pressure column, and a second branch air stream is cooled at a second set temperature which is higher than the first set temperature to obtain an air for expansion; an expansion step in which the air for expansion is adiabatically expanded at a second set pressure which is lower than the first set pressure to obtain a low-temperature air; a step for introducing a part of the low-temperature air into the intermediate pressure column; a warming step in which the temperature of the remainder of the low-temperature air is recovered to obtain a returned air; a circulating compression step in which the returned air is pressurized to obtain the pressurized returned air; and a step for introducing an air to be introduced into the intermediate pressure column into the intermediate pressure column.

1 . An air liquefaction separation method in which at least liquid oxygen is collected as a product by a cryogenic distillation of a compressed, purified and cooled feed air in an intermediate pressure column and in a low pressure column, the method including:
 a feed air compression step in which the whole amount of a feed air is pressurized up to a first set pressure which is higher than the operating pressure of the intermediate pressure column to obtain a pressurized feed air;   an adsorption and purification step in which impurities are adsorbed and removed from the pressurized feed air to obtain a pressurized purified air;   a combining step for a circulating air in which the pressurized purified air and the below-described pressurized returned air are combined to obtain a circulating air;   a cooling step in which a first branch air stream of the two divided circulating air is cooled at a first set temperature to obtain an air to be introduced into the intermediate pressure column, and a second branch air stream is cooled at a second set temperature which is higher than the first set temperature to obtain an air for expansion;   an expansion step in which the air for expansion is adiabatically expanded at a second set pressure which is lower than the first set pressure to obtain a low-temperature air;   a step for introducing a part of the low-temperature air into the intermediate pressure column;   a warming step in which the temperature of the remainder of the low-temperature air is recovered to obtain a returned air;   a circulating compression step in which the returned air is pressurized to obtain the pressurized returned air; and   a step for introducing an air to be introduced into the intermediate pressure column into the intermediate pressure column.   
     
     
         2 . An air liquefaction separation method in which at least liquid oxygen is collected as a product by a cryogenic distillation of a compressed, purified and cooled feed air in an intermediate pressure column and in a low pressure column, the method including:
 a feed air compression step in which the whole amount of a feed air is pressurized up to a first set pressure which is higher than the operating pressure of the intermediate pressure column to obtain a pressurized feed air;   an adsorption and purification step in which impurities are adsorbed and removed from the pressurized feed air to obtain a pressurized purified air;   a combining step for a circulating air in which the pressurized purified air and the below-described pressurized returned air are combined to obtain a circulating air;   a cooling step in which a first branch air stream of the three divided circulating air is cooled at a first set temperature to obtain an air to be introduced into the intermediate pressure column, a second branch air stream is cooled at a second set temperature which is higher than the first set temperature to obtain an air for cold expansion, and further, a third branch air stream is cooled at a third set temperature which is higher than the second set temperature to obtain an air for warm expansion;   a first expansion step in which the air for cold expansion is adiabatically expanded at a second set pressure which is lower than the first set pressure to obtain a first low-temperature air;   a second expansion step in which the air for warm expansion is adiabatically expanded at the second set pressure to obtain a second low-temperature air whose temperature is higher than the first set temperature;   a step for introducing a part of the first low-temperature air into the intermediate pressure column;   a warming step in which the temperatures of the remainder of the first low-temperature air and the second low-temperature air are recovered to obtain a returned air;   a circulating compression step in which the returned air is pressurized to obtain the pressurized returned air; and   a step for introducing an air to be introduced into the intermediate pressure column into the intermediate pressure column.   
     
     
         3 . The air liquefaction separation method according to  claim 1 , including a circulating air pressurizing step in which the circulating air is pressurized at a pressure which is higher than the first set pressure. 
     
     
         4 . An air liquefaction separation apparatus in which at least liquid oxygen is collected as a product by a cryogenic distillation of a compressed, purified and cooled feed air in an intermediate pressure column and in a low pressure column, the apparatus including:
 a feed air compressor in which the whole amount of a feed air is pressurized up to a first set pressure which is higher than the operating pressure of the intermediate pressure column to obtain a pressurized feed air;   an adsorption apparatus in which impurities are adsorbed and removed from the pressurized feed air to obtain a pressurized purified air;   a combining pipeline for a circulating air in which the pressurized purified air and the below-described pressurized returned air are combined to obtain a circulating air;   a main heat exchanger in which a first branch air stream of the two divided circulating air is cooled at a first set temperature to obtain an air to be introduced into the intermediate pressure column, and a second branch air stream is cooled at a second set temperature which is higher than the first set temperature to obtain an air for expansion;   an expansion turbine in which the air for expansion is adiabatically expanded at a second set pressure which is lower than the first set pressure to obtain a low-temperature air;   a pipeline for introducing a part of the low-temperature air into the intermediate pressure column;   a circulating compressor in which the temperature of the remainder of the low-temperature air is recovered by the main heat exchanger to obtain a returned air and the returned air is pressurized to obtain the pressurized returned air; and   a pipeline for introducing an air to be introduced into the intermediate pressure column into the intermediate pressure column.   
     
     
         5 . An air liquefaction separation apparatus in which at least liquid oxygen is collected as a product by a cryogenic distillation of a compressed, purified and cooled feed air in an intermediate pressure column and in a low pressure column, the apparatus including:
 a feed air compressor in which the whole amount of a feed air is pressurized up to a first set pressure which is higher than the operating pressure of the intermediate pressure column to obtain a pressurized feed air;   an adsorption apparatus in which impurities are adsorbed and removed from the pressurized feed air to obtain a pressurized purified air;   a combining pipeline for a circulating air in which the pressurized purified air and the below-described pressurized returned air are combined to obtain a circulating air;   a main heat exchanger in which a first branch air stream of the three divided circulating air is cooled at a first set temperature to obtain an air to be introduced into the intermediate pressure column, a second branch air stream is cooled at a second set temperature which is higher than the first set temperature to obtain an air for cold expansion, and further, a third branch air stream is cooled at a third set temperature which is higher than the second set temperature to obtain an air for warm expansion;   a cold expansion turbine in which the air for cold expansion is adiabatically expanded at a second set pressure which is lower than the first set pressure to obtain a first low-temperature air;   a warm expansion turbine in which the air for warm expansion is adiabatically expanded at the second set pressure to obtain a second low-temperature air;   a pipeline for introducing a part of the first low-temperature air into the intermediate pressure column;   a circulating compressor in which the temperatures of the remainder of the first low-temperature air and the second low-temperature air are recovered by the main heat exchanger to obtain a returned air, and the returned air is pressurized to obtain the pressurized returned air; and   a pipeline for introducing an air to be introduced into the intermediate pressure column into the intermediate pressure column.   
     
     
         6 . The air liquefaction separation apparatus according to  claim 4 , including a circulating air compressor in which the circulating air is pressurized at a pressure higher than the first set pressure. 
     
     
         7 . The air liquefaction separation apparatus according to  claim 6 , wherein the circulating air compressor is a brake blower for an expansion turbine set up on the expansion turbine. 
     
     
         8 . The air liquefaction separation apparatus according to  claim 4 , wherein braking of the expansion turbine is carried out by a blower, a generator or an oil-hydraulic pump. 
     
     
         9 . The air liquefaction separation method according to  claim 2 , including a circulating air pressurizing step in which the circulating air is pressurized at a pressure which is higher than the first set pressure. 
     
     
         10 . The air liquefaction separation apparatus according to  claim 5 , including a circulating air compressor in which the circulating air is pressurized at a pressure higher than the first set pressure. 
     
     
         11 . The air liquefaction separation apparatus according to  claim 10 , wherein the circulating air compressor is a brake blower for an expansion turbine set up on the expansion turbine. 
     
     
         12 . The air liquefaction separation apparatus according to  claim 5 , wherein braking of the expansion turbine is carried out by a blower, a generator or an oil-hydraulic pump. 
     
     
         13 . The air liquefaction separation apparatus according to  claim 6 , wherein braking of the expansion turbine is carried out by a blower, a generator or an oil-hydraulic pump. 
     
     
         14 . The air liquefaction separation apparatus according to  claim 10 , wherein braking of the expansion turbine is carried out by a blower, a generator or an oil-hydraulic pump.