Hydrogen liquefaction system and hydrogen liquefaction method

Abstract

The present disclosure relates to a hydrogen liquefaction system and hydrogen liquefaction method capable of increasing a hydrogen liquefaction amount through a pre-cooling process, and may comprise a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end; a pre-cooling device formed between the front end of the hydrogen pipe and the heat exchange section, pre-cooling gaseous hydrogen; and a cooling cycle device, which is in thermal contact with the heat exchange section of the hydrogen pipe so as to perform heat exchange with the heat exchange section of the hydrogen pipe such that pre-cooled gaseous hydrogen can be liquefied into liquid hydrogen.

What is claimed is: 
     
         1 . A hydrogen liquefaction system, comprising:
 a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end;   a pre-cooling device formed between the front end of the hydrogen pipe and the heat exchange section, pre-cooling gaseous hydrogen; and   a cooling cycle device, which is in thermal contact with the heat exchange section of the hydrogen pipe so as to perform heat exchange with the heat exchange section of the hydrogen pipe such that pre-cooled gaseous hydrogen can be liquefied into liquid hydrogen.   
     
     
         2 . The hydrogen liquefaction system according to  claim 1 ,
 wherein the pre-cooling device uses low-temperature liquid nitrogen or latent heat that is generated when liquid nitrogen is vaporized into gaseous nitrogen to pre-cool gaseous hydrogen.   
     
     
         3 . The hydrogen liquefaction system according to  claim 2 ,
 wherein the pre-cooling device is in thermal contact with the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, having a liquid nitrogen supply pipe on one side and a gaseous nitrogen discharge pipe on other side.   
     
     
         4 . The hydrogen liquefaction system according to  claim 2 ,
 wherein the pre-cooling device includes:   a heat exchange tank formed to surround the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, being formed with an accommodating space therein so as to accommodate liquid nitrogen;   a liquid nitrogen supply pipe formed in a lower part of the heat exchange tank, supplying liquid nitrogen to the heat exchange tank; and   a gaseous nitrogen discharge pipe formed in an upper part of the heat exchange tank, discharging gaseous nitrogen that is vaporized from liquid nitrogen which has been accommodated in the heat exchange tank.   
     
     
         5 . The hydrogen liquefaction system according to  claim 4 ,
 wherein the heat exchange tank includes:   an internal tank formed therein;   an external tank formed to surround the internal tank so as to be spaced apart from the internal tank; and   an insulating material formed between the internal tank and the external tank.   
     
     
         6 . The hydrogen liquefaction system according to  claim 4 ,
 wherein the hydrogen pipe is formed with a bent part that is at least partially bent to increase a thermal contact area that is in contact with liquid nitrogen.   
     
     
         7 . The hydrogen liquefaction system according to  claim 4 ,
 wherein the pre-cooling device further includes:   a first valve formed in the liquid nitrogen supply pipe so as to regulate a supply amount of liquid nitrogen; and   a second valve formed in the gaseous nitrogen discharge pipe so as to regulate a discharge amount of gaseous nitrogen.   
     
     
         8 . The hydrogen liquefaction system according to  claim 7 ,
 wherein the pre-cooling device further includes:   a level detecting sensor that detects a level of liquid nitrogen that is accommodated in the heat exchange tank; and   a controller that receives a level signal from the level detecting sensor and applies a control signal to the first valve or the second valve.   
     
     
         9 . The hydrogen liquefaction system according to  claim 8 ,
 wherein the pre-cooling device further includes a temperature sensor that measures temperature of the heat exchange tank; and   the controller receives a temperature signal from the temperature sensor and applies a control signal to the first valve or the second valve.   
     
     
         10 . The hydrogen liquefaction system according to  claim 4 ,
 wherein the gaseous nitrogen discharge pipe is formed to surround at least a portion of the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, being formed in a double pipe shape together with the hydrogen pipe.   
     
     
         11 . The hydrogen liquefaction system according to  claim 4 ,
 wherein the pre-cooling device further includes a pressure regulator that regulates internal pressure of the heat exchange tank.   
     
     
         12 . The hydrogen liquefaction system according to  claim 11 ,
 wherein the pressure regulator is a vacuum pressure forming device that regulates an internal vacuum level of the heat exchange tank so as to regulate temperature of saturated nitrogen inside the heat exchange tank.   
     
     
         13 . The hydrogen liquefaction system according to  claim 12 ,
 wherein the vacuum pressure forming device includes:   a vacuum line formed in an upper part of the heat exchange tank; and   a vacuum pump formed in the vacuum line.   
     
     
         14 . The hydrogen liquefaction system according to  claim 13 ,
 wherein the vacuum pressure forming device further includes:   a vacuum pressure measuring sensor that measures vacuum pressure of the heat exchange tank;   a vacuum pressure regulation valve formed in the vacuum line; and   a vacuum pressure regulation controller that receives a vacuum pressure signal from the vacuum pressure measuring sensor and applies a control signal to the vacuum pressure regulation valve.   
     
     
         15 . The hydrogen liquefaction system according to  claim 1 ,
 wherein the cooling cycle device includes:   a circulating line in which helium circulates in a reverse-Brayton cycle;   a compressor formed in the circulating line, compressing helium;   an aftercooler formed in the circulating line, cooling compressed helium and releasing heat; and   a first expander formed in the circulating line, expanding compressed helium such that temperature of helium is firstly lowered.   
     
     
         16 . The hydrogen liquefaction system according to  claim 15 ,
 wherein the cooling cycle device includes:   a second expander formed in the circulating line, expanding compressed helium such that temperature of helium is secondly lowered;   a first heat exchanger formed between the aftercooler and the first expander, performing heat exchange with the circulating line that enters the compressor;   a second heat exchanger formed between the first expander and the second expander, performing heat exchange with the hydrogen pipe; and   a third heat exchanger formed between the second expander and the second heat exchanger, performing heat exchange with the hydrogen pipe.   
     
     
         17 . The hydrogen liquefaction system according to  claim 16 ,
 wherein the cooling cycle device further includes:   a fourth heat exchanger formed between the first heat exchanger and the first expander, performing heat exchange with the hydrogen pipe.   
     
     
         18 . A hydrogen liquefaction method, comprising:
 (a) preparing a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end;   (b) pre-cooling gaseous hydrogen between the front end of the hydrogen pipe and the heat exchange section by using a pre-cooling device; and   (c) liquefying gaseous pre-cooled hydrogen, which is pre-cooled by performing heat exchange with the heat exchange section of the hydrogen pipe by using a cooling cycle device that is in thermal contact with the heat exchange section of the hydrogen pipe, into liquid hydrogen.   
     
     
         19 . The hydrogen liquefaction method according to  claim 18 ,
 wherein (b) includes regulating an internal vacuum level of the pre-cooling device so as to regulate temperature of saturated nitrogen inside the pre-cooling device, or regulating internal temperature or a level of liquid nitrogen of the pre-cooling device by using a valve.   
     
     
         20 . A hydrogen liquefaction system, comprising:
 a hydrogen pipe, where gaseous hydrogen is introduced at a front end, heat exchange occurs in a heat exchange section leading to liquefaction of gaseous hydrogen into liquid hydrogen, and liquefied liquid hydrogen can be discharged at a rear end;   a pre-cooling device formed between the front end of the hydrogen pipe and the heat exchange section, pre-cooling gaseous hydrogen; and   a cooling cycle device, which is in thermal contact with the heat exchange section of the hydrogen pipe so as to perform heat exchange with the heat exchange section of the hydrogen pipe such that pre-cooled gaseous hydrogen can be liquefied into liquid hydrogen,   wherein the pre-cooling device includes:   a heat exchange tank formed to surround the hydrogen pipe so as to perform heat exchange with the hydrogen pipe, being formed with an accommodating space therein so as to accommodate liquid nitrogen;   a liquid nitrogen supply pipe formed in a lower part of the heat exchange tank, supplying liquid nitrogen to the heat exchange tank;   a gaseous nitrogen discharge pipe formed in an upper part of the heat exchange tank, discharging gaseous nitrogen that is vaporized from liquid nitrogen which has been accommodated in the heat exchange tank;   a first valve formed in the liquid nitrogen supply pipe so as to regulate a supply amount of liquid nitrogen; and   a second valve formed in the gaseous nitrogen discharge pipe so as to regulate a discharge amount of gaseous nitrogen,   and the cooling cycle device includes:   a circulating line in which helium circulates in a reverse-Brayton cycle;   a compressor formed in the circulating line, compressing helium;   an aftercooler formed in the circulating line, cooling compressed helium to release heat;   a first expander formed in the circulating line, expanding compressed helium such that temperature of helium is firstly lowered;   a second expander formed in the circulating line, expanding compressed helium such that temperature of helium is secondly lowered;   a first heat exchanger formed between the aftercooler and the first expander, performing heat exchange with the circulating line that enters the compressor;   a second heat exchanger formed between the first expander and the second expander, performing heat exchange with the hydrogen pipe; and   a third heat exchanger formed between the second expander and the second heat exchanger, performing heat exchange with the hydrogen pipe.