Oxygen liquefaction process

Abstract

An oxygen liquefaction apparatus may include a heat exchanger that allows oxygen gas to be cooled and condensed with liquid nitrogen. The oxygen liquefaction apparatus may include: a differential pressure gauge that measures the difference in pressure between the hot and cold ends of an oxygen flow path; and an oxygen control unit that calculates the level of oxygen inside the heat exchanger based on the differential pressure gauge reading, that controls an oxygen control valve to adjust the level, and that controls the heat transfer area to control the condensation of the oxygen.

1 . A liquefaction apparatus comprising:
 a heat exchanger configured to cool and condense a gas using a refrigerant to form a liquefied product, wherein the gas flows through a first path of the heat exchanger, the first path having a cold end and a hot end, wherein the refrigerant flows through a refrigerant flow path having a cold end and a hot end;   a first differential pressure gauge configured to measure a difference in pressure between the hot end and the cold end; and   a liquefied product control unit configured to calculate a level of the liquefied product inside the heat exchanger based on the differential pressure gauge reading,   wherein the liquefied product control unit is further configured to control a liquefied product control valve to adjust the level of the liquefied product, and   wherein the liquefied product control unit is further configured to control the heat transfer area to control the condensation of the gas.   
     
     
         2 . The liquefaction apparatus according to  claim 1 , further comprising a second differential pressure gauge configured to measure a difference in pressure between the hot end and the cold end of the refrigerant flow path, wherein the liquefied product control unit is configured to calculate a level of the refrigerant, to control the liquefied product control valve to adjust the level of the refrigerant, and to control the heat transfer area, which allows the liquefied product control unit to control the condensation of the substance that is to be treated. 
     
     
         3 . The liquefaction apparatus according to  claim 1 , further comprising a second differential pressure gauge configured to measure a difference in pressure between the hot end and the cold end of the refrigerant flow path, wherein the liquefied product control unit is configured to control the liquefied product control valve based on the level of the refrigerant and the level of the liquefied product of the gas to adjust the levels of the refrigerant and the liquefied product, and to control the heat transfer area to control the condensation of the gas. 
     
     
         4 . The liquefaction apparatus according to  claim 1 , comprising:
 a liquefied product discharge line through which the liquefied product is discharged from the cold end of the heat exchanger, and   a liquefied product bypass line that is configured to discharge the liquefied product from a part of the liquefied product flow path inside the heat exchanger that is lower than the level of the liquefied product and that merges with the liquefied product discharge line through which the product is discharged from the cold end of the heat exchanger.   
     
     
         5 . The liquefaction apparatus according to  claim 4 , comprising a bypass control unit that controls the opening and closing of a bypass control valve disposed on the liquefied product bypass line so that the temperature of the liquefied product is at a specified value. 
     
     
         6 . A liquefied product production method comprising the steps of:
 providing the liquefaction apparatus of  claim 1 ;   introducing the gas into the hot end of the first path of the heat exchanger;   introducing the refrigerant the cold end of the refrigerant path of the heat exchanger, wherein the gas is cooled and condensed within the first path of the heat exchanger by exchanging heat with the refrigerant flowing within the refrigerant path, thereby forming the liquefied product;   discharging the liquefied product from the cold end of the first path; and   controlling an amount of the liquefied product discharged from the cold end of the first path based on the level of liquefied product within the heat exchanger.   
     
     
         7 . The liquefied product production method according to  claim 6 , further comprising controlling the amount of the liquefied product discharged from the cold end of the first path based on the level of the refrigerant9098 within the heat exchanger. 
     
     
         8 . The liquefied product production method according to  claim 6 , further comprising adjusting a temperature within the heat exchanger by discharging a portion of the liquefied product from a part of the heat exchanger that is lower than the level of the liquefied product, and merging with liquefied product that is taken out as the final product, so as to adjust the temperature of the liquefied product. 
     
     
         9 . The liquefied product production method according to  claim 6 , further comprising subcooling the liquefied product using a combination of a primary refrigerant, that primarily effects cooling and condensation, as well as a second refrigerant, that has a lower pressure than the first refrigerant.