Method and apparatus for regeneration water

Abstract

Ice condensed in a portion in a case in which a cryogenic refrigerator is installed, which is cooled by the cryogenic refrigerator, is melted by increasing a temperature of the ice to a melting point of the ice or higher. Then, while the temperature of the melted ice and a pressure thereof are kept to be equal to or higher than a freezing point of water, the pressure is reduced by rough evacuation so as to vaporize water. At a time at which the water is discharged, the pressure is further reduced so as to discharge water vapor. In this manner, regeneration of water is performed in accordance with a state of the water (i.e., a solid state, a liquid state, and a gas state), thereby shortening a regeneration time.

1 . A water regeneration method for discharging ice condensed in a portion cooled by a cryogenic refrigerator comprising:
 a temperature increasing step for melting the ice into water at approximately atmospheric pressure and at a melting temperature of at least 273 K;   a first roughing step performed between the approximate atmospheric pressure and a first reduced pressure being less than the atmospheric pressure but higher than and yet close to a water-freezing pressure that causes the water to freeze;   and   a second roughing step performed between a second reduced pressure and a third reduced pressure, the second and third reduced pressures being less than the first reduced pressure and the second reduced pressure being greater than the third reduced pressure,   wherein each one of the first roughing step and the second roughing step occurs at the melting temperature of at least 273 K.   
     
     
         2 . The water regeneration method according to  claim 1 , comprising a reducing step of reducing a pressure and a temperature in the portion after the second roughing step. 
     
     
         3 . The water regeneration method according to  claim 2 , wherein the reducing step is performed when the pressure increase does not occur within a predetermined time during the second roughing step. 
     
     
         4 . The water regeneration method according to  claim 2 , comprising a step of starting a cryopump after the reducing step. 
     
     
         5 . The water regeneration method according to  claim 4 , a dry pump is operated during the reducing step to reduce the pressure, and the dry pump is stopped before the cryopump is started. 
     
     
         6 . The water regeneration method according to  claim 1 , wherein the second roughing step includes a buildup determination. 
     
     
         7 . The water regeneration method according to  claim 6 , wherein the buildup determination is performed by measuring a pressure increase while an evacuation is stopped, and is determined when the pressure increase is smaller than a predetermined value. 
     
     
         8 . The water regeneration method according to  claim 1 , wherein the first reduced pressure is set to approximately 100 Pa. 
     
     
         9 . The water regeneration method according to  claim 1 , wherein the third reduced pressure is set to approximately 10 Pa. 
     
     
         10 . A water regeneration apparatus for discharging ice condensed in a portion cooled by a cryogenic refrigerator comprising:
 temperature increasing means for melting the ice into water at approximately atmospheric pressure and at a melting temperature of at least 273 K;   vaporizing means for vaporizing the water by performing a first roughing step between the approximate atmospheric pressure and a first reduced pressure being less than the atmospheric pressure but higher than and yet close to a water-freezing pressure that causes the water to freeze;   and   water vapor discharging means for discharging water vapor by performing a second roughing step between a second reduced pressure and a third reduced pressure, the second and third reduced pressures being less than the first reduced pressure and the second reduced pressure being greater than the third reduced pressure,   wherein each one of the roughing steps occurs at the melting temperature of at least 273 K.   
     
     
         11 . The water regeneration apparatus according to  claim 10 , wherein pressure and temperature in the portion are reduced to less than the second reduced pressure and less than 273 K respectively, after the second roughing step. 
     
     
         12 . The water regeneration apparatus according to  claim 11 , wherein the pressure and temperature in the portion are reduced when a pressure increase does not occur within a predetermined time during the second roughing step. 
     
     
         13 . The water regeneration apparatus according to  claim 11 , wherein a cryopump is operated when the pressure or the temperature in the portion is a predetermined pressure or a predetermined temperature. 
     
     
         14 . The water regeneration apparatus according to  claim 13 , a dry pump is operated during the pressure in the portion is reduced, and the dry pump is stopped before the cryopump is started. 
     
     
         15 . The water regeneration apparatus according to  claim 10 , the first or second roughing step is performed by a dry pump. 
     
     
         16 . The water regeneration apparatus according to  claim 10 , the apparatus further comprising means for buildup determination. 
     
     
         17 . The water regeneration apparatus according to  claim 16 , wherein the means for buildup determination comprising means for measuring a pressure increase while an evacuation is stopped, the means for buildup determination determines when the pressure increase is smaller than a predetermined value. 
     
     
         18 . The water regeneration apparatus according to  claim 16 , wherein the means for buildup determination determines during the second roughing step that pressure and temperature in the portion are to be reduced to less than the third reduced pressure and less than  273  K respectively.