Pressure swing adsorption product purity control method and apparatus

A process for controlling the level of impurity in a gas product stream from a pressure swing adsorption process including a cocurrent depressurization step, comprising:

• sensing a characteristic of the effluent from said cocurrent depressurization step;
• taking a corrective action responsive to the sensed characteristic, said action being effective to vary the impurity concentration in the product gas in the direction necessary to obtain desired product purity;
• sensing a physical characteristic of the product gas stream;
• comparing the sensed physical characteristic of the product gas stream to a reference value;
• and
• establishing a target value for the sensed characteristic of the cocurrent depressurization effluent in response to the comparison of the sensed value of impurity in the product gas stream to the reference value.

An apparatus for controlling the level of impurity in a gas product stream from a pressure swing adsorption process including a cocurrent depressurization step, comprising:

• means for sensing a characteristic of the effluent from said cocurrent depressurization step;
• means for taking a corrective action responsive to the sensed characteristic, said action being effective to vary the impurity concentration in the product gas in the direction necessary to obtain desired product purity;
• means for sensing a physical characteristic of the product gas stream;
• means for comparing the sensed physical characteristic of the product gas stream to a reference value;
• and
• means for establishing a target value for the sensed characteristic of the cocurrent depressurization effluent in response to the comparison of the sensed value of impurity in the product gas stream to the reference value.