Concentration swing adsorption

Three generic adsorptive process schemes have been commercialized to serve most of the applications shown in Table 1. They include 1) temperature swing adsorption (TSA) 2) pressure swing adsorption (PSA) and 3) concentration swing adsorption (CSA).P The fluid mixture (feed) to be separated is passed over a regenerated adsorbent (contained in an adsorber vessel) to produce a stream enriched in the less strongly adsorbed components of the mixture. 

Concentration swing adsorption (CSA) and concentration-thermal swing adsorption (CTSA) processes for drying bulk liquid mixtures... 

One further development in adsorption technology which holds some promise, is a cyclic process applicable to the separation of liquids. The separation method depends on concentration changes and is referred to as concentration swing adsorption (Rao and Sircar 1992). Separation of a binary mixture, such as ethanol-water, occurs by the selective liquid phase adsorption of ethanol (the more strongly adsorbed component) onto the surface of a porous adsorbent. The cycle consists of four steps ... 

During the first part of the concentration swing adsorption cycle, effluent from the column is pure water. This first step is continued until the whole column is saturated with the ethanol-water feed mixture. 

The sulphur-free syngas has a high C02 concentration and an elevated pressure (2-7 MPa), thus making physical absorption highly recommended for C02 separation, although adsorption process such as pressure swing adsorption (PSA) is also utilised. 

A pressure-swing adsorption (PSA) process cycle is one in which desorption takes place at a pressure much lower than adsorption. Reduction of pressure is used to shift the adsorption equilibrium and affect regeneration of the adsorbent. Figure 16-39 depicts a simplified pressure-swing cycle. Feed fluid containing an adsorbate at a molar concentration of y i = pi /Pi is passed through an adsorbent at conditions... 

MOLPSA-nitrogen [Molecular sieve pressure swing adsorption] A version of the PSA process for separating nitrogen from air, developed by Kobe Steel. Most PSA processes for nitrogen use molecular sieve carbon as the adsorbent, but this one uses zeolite X. Water and carbon dioxide are first removed in a two-bed PSA system, and then the nitrogen is concentrated and purified in a three-bed system. 

Kikkinides, E.S. Yang, R.T. Cho, S.H. (1993). Concentration and recovery of carbon dioxide from flue gas by pressure swing adsorption. Industrial Engineering Chemistry Research, 32 (11), 2714-2720. 

---