Super Cycles: Coupling Pressure Swing Adsorption to Other Regeneration Techniques

Purdue University, West Lafayette IN

Investigators

Abstract

CBET-0754906 Wankat This NSF award by the Chemical and Biological Separations program supports work by Professor Phillip C. Wankat at Purdue University to develop a new gas phase adsorption separation process called "super cycles" that will allow coupling of Pressure Swing Adsorption (PSA) with other regeneration methods. PSA is a well-known gas separation method commonly used in industry that uses a low pressure purge to regenerate the adsorption bed. PSA has the advantage of high productivity and thus is often relatively inexpensive. However, because the recovery (or yield) of the desired compounds becomes quite low when the adsorption is very strong, PSA cannot be used for compounds that adsorb strongly. Alternate regeneration methods such as thermal, steam or high-vacuum desorption have much better recoveries of strongly adsorbed compounds than PSA, but have significantly lower productivities. This research will develop a novel method for coupling PSA with thermal, steam or high-vacuum desorption for strongly adsorbed compounds. The new process retains most of the productivity advantage of PSA while using the ability of the thermal, steam or high-vacuum desorption to regenerate the adsorption bed. The practical significance of this research is that PSA is not commercially economical for strongly adsorbed compounds such as recovery of Volatile Organic Compounds (VOC) or for the separation of medium and high molecular weight straight chain hydrocarbons (used to produce biodegradable detergents) from branched chain hydrocarbons. Since PSA is not applicable for these separations, more expensive lower productivity methods are used. Development of super cycles will significantly reduce both the capital and operating cost of separating these compounds, which will help keep the environment clean while reducing energy requirements. In addition, a teaching method that incorporates scheduled, tutored computer laboratory sessions where students learn to use a commercial simulator as part of a lecture course will be further developed. This teaching method has been shown to help chemical engineers develop a better understanding of liquid separation processes. In this work this teaching method is extended to gas adsorption separations.