Method for packaging an no/n2 gaseous mixture

Abstract

The invention pertains to a method for packaging a gaseous NO/N 2 mixture into a container comprising the steps of introducing into a container a gaseous premix formed of NO and of N 2 containing an NO content of less than 10% by volume so as to reach a first pressure P1 with P1>1 bar, then introducing into the container containing the NO/N 2 premix at the first pressure P1, gaseous nitrogen so as to obtain a final gaseous NO/N 2 mix containing an NO content of less than or equal to 1200 ppm by volume and a second pressure P2 lying between P1 and 800 bar. The final NO/N 2 gaseous mixture contains an NO content of less than or equal to 1000 ppm by volume.

1 . A method for packaging a gaseous NO/N 2  mixture into a container comprising the steps of:
 a) introducing into a container a gaseous premix formed of NO and of N 2  containing an NO content of less than 10% by volume so as to reach a first pressure P 1  with P 1 >1 bar,   b) introducing into the container containing the NO/N 2  premix at the first pressure P 1 , a gaseous nitrogen so as to obtain a final gaseous NO/N 2  mix containing an NO content of less than or equal to 1200 ppm by volume and a second pressure P 2  lying between P 1  and 800 bar.   
     
     
         2 . The method of  claim 1 , wherein the first pressure P 1  lies between 2 and 10 bar. 
     
     
         3 . The method of  claim 1 , wherein the first pressure P 1  lies between 2 and 5 bar. 
     
     
         4 . The method of  claim 1 , wherein the second pressure lies between 100 and 700 bar. 
     
     
         5 . The method of  claim 1 , wherein the second pressure lies between 200 and 700 bar. 
     
     
         6 . The method of  claim 1 , wherein the gaseous premix formed of NO and N 2  contains an NO content of less than or equal to 8% by volume. 
     
     
         7 . The method of  claim 1 , wherein the gaseous premix formed of NO and N 2  contains an NO content of less than or equal to 5% by volume. 
     
     
         8 . The method of  claim 1 , wherein the gaseous premix formed of NO and N 2  contains an NO content of 4% by volume and the first pressure P 1  is 4 bar. 
     
     
         9 . The method of  claim 1 , wherein step a) is preceded by at least one step chosen from:
 a step d) of gaseous rinsing during which the nitrogen is introduced into the container,   a step c) of purging during which the internal volume of the container is placed in fluidic communication with the ambient atmosphere, and   a step e) of evacuation during which the internal volume of the container is placed under depressurization at less than  1  standard atmosphere pressure.   
     
     
         10 . The method of  claim 1 , wherein step a) is preceded by several successive and cyclic steps of gaseous rinsing d) and of purging c). 
     
     
         11 . The method of  claim 9 , wherein the gas rinsing step or steps d) involve admitting gaseous nitrogen into the container until a rinsing pressure of between 2 and 20 bar. 
     
     
         12 . The method of  claim 11 , wherein the rinsing pressure is between 2 and 12 bar. 
     
     
         13 . The method of  claim 1 , wherein during the purging step or steps c), the internal volume of the container is 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. 
     
     
         14 . The method of  claim 13 , wherein the minimal purge pressure (Pmin) is between around 1.1 and 3 bar. 
     
     
         15 . The method of  claim 9 , wherein during at least one evacuating step e), the internal volume of the container is placed under depressurization until a depressurization pressure of below 0.5 bar is attained. 
     
     
         16 . The method of  claim 15 , wherein the depressurization pressure is below 0.2 bar. 
     
     
         17 . 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, 
     
     
         18 . The method of  claim 1 , wherein the final gaseous NO/N 2  mixture contains an NO content of between 200 and 800 ppm by volume. 
     
     
         19 . The method of  claim 1 , wherein the steps are implemented by a filling system ( 14 ) adapted for filling gas containers, the filling system comprising connecting elements adapted so that filling system ( 14 ) is capable of filling several containers at once. 
     
     
         20 . The method of  claim 1 , wherein the container is a gas cylinder ( 11 ,  12 ,  13 ), with a body made of steel, aluminum or an alloy of aluminum.