(36a) Regeneration Peak Profiles of Temperature Swing Adsorption Processes

Temperature Swing Adsorption (TSA) processes have been widely used for natural gas processing for removing water, sulfur, CO2, heavy hydrocarbon, etc. In a TSA process, a feed gas first enters an adsorber to adsorb the contaminants. The adsorber is regenerated by raising the temperature of the adsorbent typically by purging the bed with a preheated gas. The hot regeneration effluent gas, after cooling, is further processed to remove the contaminants before this spent regeneration gas can be reused, recycled or disposed. Due to the dynamic nature of the TSA process, the compositions in the effluent regeneration stream tend to vary with time, generating a peak concentration, several orders of magnitude higher than its average. The downstream unit to process the spent regeneration gas needs to be sized based on the peak, which results in a significant increase of the equipment size. The fluctuation of stream compositions can also result in unstable operation for the downstream units, especially if combustion or incineration is involved in these downstream processing units.

In this presentation, we will show that if the spent regeneration gas is to be recycled to the front end of a TSA unit, the TSA unit does not need to account for the peak and fluctuation of the inlet compositions. If the spent regeneration gas is to be processed in a solvent-based absorption unit, a fixed-bed adsorber can be used to dampen the peak concentration profile from the spent regeneration gas. The benefit of this solution will be demonstrated using an example from a Middle East natural gas complex, where UOP’s Amine Guard^TM FS, Molecular Sieve, and Selexol^TM processes are used for pretreatment.