Liquid phase thermal swing chemical air separation

A continuous process for producing oxygen from cleaned and dried air and a liquid oxygen acceptor consisting essentially of a mixture of alkali metal nitrate and nitrite salt, comprising the steps of:

• (a) countercurrently contacting the air at a pressure between 1 and 25 ATA in an adiabatic absorber with the acceptor which has been cooled to below about 540.degree. C., thereby oxidizing the acceptor;
• (b) heating the oxidized acceptor to at least about 580.degree. C. by sensible heat exchange with oxygen depleted acceptor of step (e);
• (c) further heating the oxidized acceptor to at least about 620.degree. C. from a source of heat consisting of less than 80 kcal per mole of O.sub.2 produced;
• (d) separating product oxygen from the heated acceptor, whereby oxygen depleted acceptor is obtained;
• (e) cooling the oxygen depleted acceptor to below about 580.degree. C. by sensible heat exchange with the oxidized accept of step (b);
• (f) further cooling the oxygen depleted acceptor to below about 540.degree. C. by external heat rejection;
• (g) recycling the cooled acceptor to step (a) by pumping to elevated pressure;
• (h) maintaining the absolute absorber pressure at greater than one to no more than four times the absolute pressure of the step (d) desorption;
• and
• (i) recovering at least 80% of the oxygen in the supply air as product.