Process and apparatus for supplying a backup gas under pressure

Abstract

The present invention relates to a process and a system for supplying a backup gas at a higher pressure from a source gas at a lower pressure. The backup gas at the lower pressure is at least partially condensed against a backup liquid at a higher pressure in a reprocessing heat exchanger and as a result, the backup liquid is at least partially vaporized. The backup liquid at the higher pressure is formed from boosting liquefied backup gas at the lower pressure. A backup vaporizer is disposed downstream of the reprocessing heat exchanger to completely vaporize the backup liquid at a higher pressure before it was delivered to the customer. The present invention eliminates the use of costly gas compressor and mitigates associated safety risks, in particular when the backup gas is oxygen.

1 - 14 . (canceled) 
     
     
         15 . A process for supplying a backup gas at an elevated pressure, comprising:
 a) providing a source of backup gas at a first pressure;   b) providing at least a reprocessing heat exchanger, a backup vaporizer and a liquid pump;   c) heat-exchange between the backup gas at the first pressure and a backup liquid at a second pressure in the reprocessing heat exchanger to produce the at least partially liquefied backup gas at the first pressure and the at least partially vaporized backup liquid at the second pressure;   d) warming up the at least partially vaporized backup liquid at the second pressure in the backup vaporizer to produce the backup gas at an elevated pressure; and wherein   the second pressure is higher than the first pressure, and the backup liquid at the second pressure is obtained from elevating the pressure of the liquefied backup gas to the second pressure with the liquid pump.   
     
     
         16 . The process as claimed in  claim 15 , further comprising an expansion valve and a liquid storage tank, wherein the at least partially liquefied back-up gas at the first pressure is expanded through the expansion valve before entering the liquid storage tank. 
     
     
         17 . The process as claimed in  claim 15 , further comprising:by-passing part of the back-up liquid at the second pressure from the reprocessing heat exchanger through a by-pass circuit. 
     
     
         18 . The process as claimed in  claim 15 , wherein the pressure ratio of the second pressure to the first pressure is in the range of 1 to 3 bar(a). 
     
     
         19 . The process as claimed in  claim 18 , wherein the pressure ratio of the second pressure to the first pressure is in the range of 1.2 to 2.5 bar(a). 
     
     
         20 . The process as claimed in  claim 15 , wherein the back-up gas and the back-up liquid comprise oxygen. 
     
     
         21 . A system for supplying a back-up gas at an elevated pressure, comprising:
 a) a reprocessing heat exchanger, a back-up vaporizer and a liquid pump;   b) a first conduit for delivering a back-up gas at a first pressure into a warm end of the reprocessing heat exchanger and a second conduit for transporting an at least partially liquefied back-up gas at a first pressure from the cold end of the reprocessing heat exchanger into the liquid pump;   c) a third conduit for delivering a back-up liquid at a second pressure from the outlet of the liquid pump into a cold end of the reprocessing heat exchanger;   d) a fourth conduit for transporting an at least partially vaporized back-up liquid at a second pressure from a warm end of the reprocessing heat exchanger to the back-up vaporizer;   e) a fifth conduit for supplying the back-up gas at an elevated pressure from the back-up vaporizer, and wherein the second pressure is higher than the first pressure.   
     
     
         22 . The system as claimed in  claim 21 , wherein an expansion valve and a liquid storage tank are in fluid communication with the second conduit. 
     
     
         23 . The system as claimed in  claim 21 , the reprocessing heat exchanger having separate flow channels for the back-up gas at the first pressure and the back-up liquid at the second pressure, further comprising a by-pass circuit, with one end connecting to the flow channel for the back-up liquid at the second pressure inside the reprocessing heat exchanger and one end connecting to the fourth conduit. 
     
     
         24 . The system as claimed in  claim 23 , further comprising a flow-control valve disposed on the by-pass circuit. 
     
     
         25 . The system as claimed in  claim 23 , the reprocessing heat exchanger comprises aluminum plate fin exchanger or printed plate exchanger. 
     
     
         26 . The system as claimed in  claim 21 , wherein a pressure ratio of the second pressure to the first pressure is in the range of 1 to 3 bar(a). 
     
     
         27 . The system as claimed in  claim 26 , wherein a pressure ratio of the second pressure to the first pressure is in the range of 1.2 to 2.5 bar(a). 
     
     
         28 . The system as claimed in  claim 21 , wherein the back-up gas and the back-up liquid comprise oxygen.