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

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• e) at least one liquid (27) is withdrawn from one of the columns of the system, the liquid is pressurized and sent to the first exchanger, where it vaporizes to form a gas under pressure;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.

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.