Method And Installation For The Emergency Back-Up Supply Of A Gas Under Pressure

Abstract

In a method for the emergency back-up supply of a gas under pressure by vaporization of a pressurized liquid, this gas normally being supplied by vaporization of liquid ( 33 ) in a first exchanger ( 1 ) of a pumped air separation unit, during the step of operating a second exchanger ( 2 ) in order to produce the make-up gas, pressurized liquid ( 33 ) and high-pressure air ( 8 ) continue to be sent to the first exchanger.

1 - 12 . (canceled) 
     
     
         13 . A method for the emergency back-up supply of a gas under pressure, by vaporization of a pressurized liquid in which:
 i) during a first step:
 a) a first stream of air is compressed by means of a compressor ( 3 ) and purified in a purification unit ( 5 ); 
 b) at least one portion of the air is compressed to a high pressure, which allows vaporization of the pressurized liquid; 
 c) at least one portion of the air at the high pressure is sent to a first exchanger ( 1 ); 
 d) at least one portion of the air cooled in the first exchanger is sent to a system of distillation columns ( 15 ,  17 ); and 
 e) at least one liquid ( 27 ) is withdrawn from one of the columns of the system, the liquid is pressurized and sent to the first exchanger, where it vaporizes to form a gas under pressure; 
   ii) during a second step a stream of the said liquid is sent to a second exchanger ( 2 ) where it vaporizes to form a make-up stream of the gas under pressure,   
       characterized in that, during the second step, at least initially, air at the high pressure and pressurized liquid coming from one column of the system are sent to the first exchanger and then the stream of high-pressure air sent to the first exchanger is reduced, possibly to zero, and the stream of pressurized liquid sent to the first exchanger is reduced, possibly to zero. 
     
     
         14 . The method of  claim 13 , in which, during at least part of the second step, air is sent from a gaseous air storage tank ( 5 ,  9 ) to the first exchanger and then to the system of columns and, optionally during the first step, supercharged air is sent to the air storage tank where it is stored in gaseous form. 
     
     
         15 . The method of  claim 14 , in which all the air is compressed to the high pressure and then purified in the purification unit ( 5 ), the purification unit constituting the air storage tank. 
     
     
         16 . The method of  claim 15 , in which, as high-pressure air passages, only passages of the first exchanger ( 1 ) dedicated to high-pressure air are used, these passages being closest to the passages for vaporizing the said liquid, this being achieved by separation of the liquid air output boxes at the cold end of the main exchanger and by the addition of a liquid air valve per additional liquid air output box, which makes it possible to expand this liquid into the columns. 
     
     
         17 . The method of  claim 13 , in which all the liquid to be pressurized is stored in a second storage tank ( 19 ). 
     
     
         18 . The method of  claim 13 , in which, during the first step, a stream of the said liquid, smaller than the stream sent during the second step, is sent to the second exchanger ( 2 ) where it vaporizes to form gas under pressure. 
     
     
         19 . The method of  claim 13 , in which at least one of the liquids ( 27 ) to be pressurized is rich in oxygen, argon, nitrogen, hydrogen, helium, methane or carbon monoxide. 
     
     
         20 . The method of  claim 13 , in which the liquid is pressurized by means of at least one pump ( 39 ). 
     
     
         21 . The method of  claim 13 , in which, during the second step, air is sent directly from the first storage tank ( 5 ,  9 ) to the first exchanger ( 1 ). 
     
     
         22 . The method of  claim 13 , in which, during a third step, pressurized liquid is sent only to the second exchanger ( 2 ) and air is no longer sent to the first exchanger ( 1 ). 
     
     
         23 . The method of  claim 13 , in which, during the second step, at least some of the heat needed to vaporize the liquid comes from the thermal inertia of the first exchanger ( 1 ). 
     
     
         24 . An installation for the emergency back-up supply of a gas under pressure, by vaporization of a pressurized liquid, comprising:
 i) a first storage tank ( 5 ,  9 );   ii) a pump ( 39 );   iii) a first exchanger ( 1 );   iv) a second exchanger ( 2 );   v) a compressor ( 3 );   vi) a purification unit ( 5 );   vii) a supercharger ( 7 );   viii) means for sending air to the compressor, means for sending compressed air to the purification unit and means for sending at least one portion of the purified air to the supercharger;   ix) means for sending air to a column of a system of columns ( 17 ,  19 );   x) means for withdrawing at least one liquid ( 27 ) from the system of columns optionally after having stored it in a storage tank;   xi) means for sending the liquid to the pump in order to pressurize it;   xii) means for sending the pressurized liquid to the first exchanger;   xiii) means for withdrawing the vaporized liquid from the first exchanger;   xiv) means for sending the pressurized liquid to the second exchanger; and   xv) a tank ( 9 ) for storing gaseous air under pressure, the tank being connected to the outlet of the air supercharger,   
       characterized in that the storage tank ( 9 ) is connected to the outlet of the air supercharger via an expansion valve.