Method for packaging no/n2 mixtures, with prior purging and rinsing steps

Abstract

The method for packaging a gaseous NO/N 2 mixture into at least one container, characterized in that, prior to admitting the said NO/N 2 mixture, said at least one container is subjected to at least a purging step during which the internal volume of the container is placed in fluidic communication with the ambient atmosphere, an evacuating step during which the internal volume of the container is placed under depression, and a gas rinsing step during which an inert gas is admitted to said at least one container. For preference, the final gaseous NO/N 2 mixture contains an NO content less than or equal to 1200 ppm by volume for a pressure of between P1 and 800 bar.

1 . A method for packaging a gaseous NO/N 2  mixture into at least one container, wherein, prior to admitting said NO/N 2  mixture into the container, said at least one container is subjected to at least:
 a) a purging step during which the internal volume of the container is placed in fluidic communication with the ambient atmosphere,   b) an evacuating step during which the internal volume of the container is placed under depressurization, and   c) a gas rinsing step during which an inert gas is admitted to said at least one container.   
     
     
         2 . The method of  claim 1 , wherein said at least one container is subjected to steps a) and c) several times in succession prior to said NO/N 2  mixture being admitted to said at least one container. 
     
     
         3 . The method of  claim 1 , wherein at least two successive sequences of steps a) and c) are separated by a sequence of steps a), b) and c). 
     
     
         4 . The method of  claim 1 , wherein a sequence of steps a), b) and c) is immediately followed by a sequence of steps a) and c) or by a sequence of steps a), c) and a). 
     
     
         5 . The method of  claim 1 , wherein, during steps c), the inert gas used to perform the gas rinsing is nitrogen. 
     
     
         6 . The method of  claim 1 , wherein several gas containers are subjected simultaneously to steps a) to c). 
     
     
         7 . The method of  claim 1 , wherein, after at least two sequences of steps a) and c) have been carried out, a gaseous mixture made of NO and N 2  is admitted to the container or containers. 
     
     
         8 . The method of  claim 1 , wherein, after at least two sequences of steps a) and c) have been carried out, the following are admitted in succession to the container or containers:
 i) a gaseous premix made of NO and N 2  containing an NO content less than 10% by volume until a first pressure P1 is reached where P1>1 bar absolute;   ii) gaseous nitrogen until, through mixing of the nitrogen with the said NO/N 2  premix, a final gaseous NO/N 2  mixture containing an NO content less than or equal to 1200 ppm by volume and a second pressure P2 of between P1 and 800 bar are achieved.   
     
     
         9 . The method  claim 1 , wherein the gas rinsing step c) involves admitting gaseous nitrogen into the container or containers until a rinsing pressure of between 2 and 20 bar, preferably of between 2 and 12 bar, is reached within said container or containers. 
     
     
         10 . The method of  claim 1 , wherein during the purging step a), the internal volume of the container is kept in fluidic communication with the atmosphere as long as the internal pressure inside the container is higher than a minimal purge pressure (Pmin) such that 3.5 bar>Pmin>1 bar. 
     
     
         11 . The method of  claim 10 , wherein Pmin is between about 1.1 and about 3 bar. 
     
     
         12 . The method of  claim 1 , wherein during at least one evacuating step b), the internal volume of the container is placed under depressurization until a pressure level below 0.5 bar is reached. 
     
     
         13 . The method of  claim 12 , wherein the depressurization pressure level is below 0.2 bar 
     
     
         14 . The method of  claim 1 , wherein it comprises, prior to step a), a step d) of evacuating and a step e) of purging at least one flexible hose connecting the filling system to a gas container. 
     
     
         15 . The method of  claim 1 , wherein the final gaseous NO/N 2  mixture contains an NO content less than or equal to 1000 ppm by volume. 
     
     
         16 . The method of  claim 15 , wherein the final gaseous NO/N 2  mixture contains an NO content of between 200 and 800 ppm by volume. 
     
     
         17 . The method of  claim 1 , wherein during the gas rinsing step c), the admission of inert gas to said at least one container is halted when the pressure in said at least one container reaches a value of between 2 and 20 bar. 
     
     
         18 . The method of  claim 17 , wherein the value is between 3 and 10 bar. 
     
     
         19 . The method of  claim 1 , wherein fluidic communication with the ambient atmosphere during purging step a) is halted when the pressure in the internal volume of the container reaches a value of between 1 and 1.5 bar.