Membrane gas generator in association with bulk storage for increased flexibility and productivity

A membrane nitrogen generator adapted to deliver a flow rate of nitrogen gas having a purity which is at least equal to P.sub.0, comprising:

• (a) a source of compressed nitrogen-containing gas having a purity lower than P.sub.0, said source having a maximum flow rate Fm.sub.1 ;
• (b) varying means in fluid connection with said source of compressed nitrogen-containing gas which is adapted to vary the flow rate of said source between Fm.sub.1 and zero;
• (c) a nitrogen membrane in fluid connection with said source of compressed nitrogen-containing gas and which is capable of delivering a low purity nitrogen gas which is enriched in nitrogen compared to said source and a nitrogen-depleted gas which is depleted in nitrogen compared to said source, said low purity nitrogen gas having a purity P.sub.1 which increases when the flow rate of said nitrogen containing gas source feeding the membrane decreases, said purity P.sub.1 being lower than P.sub.0 at said maximum flow rate Fm.sub.1 ;
• (d) a source of high purity compressed nitrogen gas having a purity which is greater than P.sub.0 delivering a high purity nitrogen gas having flow rate control means to control its flow rate from zero to a maximum flow rate value Fm.sub.2 ;
• (e) mixing means adapted to mix said low purity nitrogen gas and said high purity nitrogen gas and delivering a nitrogen gas mixture;
• and
• (f) purity control means adapted to measure the purity of the nitrogen gas mixture and to generate a signal to the flow rate control means to increase the flow rate of the high purity nitrogen gas when the measured purity of said nitrogen gas mixture is smaller than or equal to P.sub.0 and to decrease the flow rate of the high purity nitrogen gas when the measured purity of said nitrogen gas mixture is greater than P.sub.0.