Membrane/deoxo control method and system

Claim 1

An improved system for the production of high purity nitrogen comprising: (a) a membrane or pressure swing adsorption system capable of separating air into a partially purified nitrogen stream containing residual oxygen and an oxygen-rich discharge stream; (b) means for supplying feed air to such membrane or pressure swing adsorption system for separation therein; (c) a catalytic combustion system adapted for the reaction of the residual oxygen present in said partially purified nitrogen stream with a hydrogen stream; (d) means for passing a hydrogen stream to said catalytic combustion system; (e) means for passing the partially purified nitrogen stream from said membrane or pressure swing adsorption system to said catalytic combustion system; (f) oxygen analyzer means capable of continuously determining the oxygen purity of said partially purified nitrogen stream and of providing an input process variable signal proportional thereto; (g) flow meter means capable of determining the flow rate of said partially purified nitrogen stream and of providing an input process variable signal proportional thereto; (h) computer control means adapted for the sending of corresponding output control signals for control of the partially purified nitrogen stream flow rate in response to such input process variable signals, said computer control means also being adapted for sending of output control signals for control of the flow rate of said hydrogen stream so as to maintain the hydrogen flow corresponding to that required for reaction with the oxygen in the partially purified nitrogen stream with a minimal excess hydrogen content; (i) flow meter means capable of determining the flow rate of said hydrogen stream passing to said catalytic combustion system and of providing an input process variable signal to said computer control means proportional thereto; (j) control valve means for separately controlling the flow of partially purified nitrogen and of hydrogen to said catalytic combustion system, said valve means controlled in response to output signals from said computer control means; (k) conduit means for passing refined nitrogen product gas from said catalytic combustion system for downstream application; (l) analyzer means for determining the hydrogen content of said refined nitrogen product gas and for providing an input process variable signal proportional thereto to said computer control means for control of the hydrogen flow rate to said catalytic combustion means; whereby high purity nitrogen product can advantageously be produced with the hydrogen content of the refined nitrogen stream being minimized as a result of fast response to changing conditions in the overall system.