Co2 capture processes using rotary wheel configurations

A method for enhanced control, separation, and/or purification of CO2 gas from one or more sources having a mixture of gases, the method comprising:

• providing a solid monolithic sorbent material having a thickness and a selectivity for CO2 sorption in a continuous or semi-continuous sorption-desorption process comprising a CO2 sorption step and a CO2 desorption step, but not comprising either a drying step or a separate cooling step;
• providing one or more mixed gas sources containing CO2 gas at a feed temperature, such that the mixed gas source(s) collectively exhibit not more than 70% water vapor saturation;
• adding liquid phase water droplets to the mixed gas source(s) to form a dual phase sorption feedstream containing CO2 and H2O at approximately the feed temperature, the amount of liquid phase water being sufficient to cause the dual phase sorption feedstream to have at least 99% water vapor saturation at a desorption temperature, which is higher than the feed temperature, and to have at least gas phase CO2 and H2O and liquid phase H2O components at the desorption temperature;
• in the CO2 sorption step, exposing the dual phase sorption feedstream at approximately the feed temperature to the solid monolithic sorbent, which is at the desorption temperature, across the thickness of the sorbent under conditions sufficient for the solid monolithic sorbent to selectively sorb the desired CO2 gas, thus forming a selectively CO2-sorbed solid monolithic sorbent and a selectively CO2-depleted product stream;
• in the CO2 desorption step, exposing the selectively CO2-sorbed solid monolithic sorbent to a stripping stream, which contains moisture and which is at a stripping temperature that is at least about 20° C. higher than the inlet temperature, across the thickness of the sorbent, thus forming a CO2-desorbed monolithic sorbent, and a stripped product stream containing desorbed CO2 and a lower moisture content than in the at least partially stripped product stream;
• and
• in the at most partially cooling step, cooling only a portion of the thickness of the CO2-desorbed monolithic sorbent by exposing the sorbent to a co-current cooling stream for a time and under conditions sufficient to cool only the portion of the thickness of the solid monolithic sorbent to approximately the feed temperature, wherein the portion of the thickness of the solid monolithic sorbent is less than one half the thickness of the solid monolithic sorbent,
• wherein the CO2 sorption step is exothermic and selectively sorptive for CO2, such that the exposing of the dual phase sorption feedstream to the solid monolithic sorbent results in a thermal wave, having a leading edge, passing across the thickness of the sorbent and simultaneously in a CO2 sorption wave, having a leading edge, passing across the thickness of the sorbent;
• wherein the at most partial cooling step causes the leading edge of the thermal wave to start at a position within the thickness of the sorbent corresponding to the portion of the thickness of the sorbent that was cooled;
• wherein the thermal wave passes across the thickness of the sorbent only as fast as, or slower than, the CO2 sorption wave, and yet wherein, due to the partial cooling step, the leading edge of the thermal wave still passes across the thickness of the sorbent in a position downstream from the leading edge of the CO2 sorption wave;
• and wherein the liquid phase water in the dual phase sorption feed sorbs heat resulting from the desorption temperature being greater than the feed temperature by changing to gas phase water vapor to simultaneously partially cool the sorbent during the sorption step, thus allowing the separate cooling step to be partially eliminated in the continuous or semi-continuous sorption-desorption process.