Adsorption regeneration pressure-swing

The second CO2 removal is conducted using the same solvent employed in the first step. This allows a common regeneration stripper to be used for the two absorbers. The gases leaving the second absorption step stiU contain some 0.25—0.4% CO and 0.01—0.1% CO2 and so must be methanated as discussed earlier. The CO, CO2, and possibly small amounts of CH, N2, and Ar can also be removed by pressure-swing adsorption if desired. 

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... 

While adsorption equiUbrium considerations do justify the possibility to regenerate an adsorbent bed completely and to uniform levels, this is rarely achieved in practice in either thermal swing adsorption and is almost never the case in pressure swing adsorption. Some residual sorbate is always left on the sorbent and in general, except for TSA with only one or two sorbates, the residual loadings are almost always found as a non-uniformly distributed profile across the length of the bed. 

PSA refers to the process of regeneration. It means pressure swing adsorption. 

N diffuses into the structural pores of clinoptilolite 10 to 10 times faster than does CH4. Thus internal surfaces are kinetically selective for adsorption. Some clino samples are more effective at N2/CH4 separation than others and this property was correlated with the zeolite surface cation population. An incompletely exchanged clino containing doubly charged cations appears to be the most selective for N2. Using a computer-controlled pressure swing adsorption apparatus, several process variables were studied in multiple cycle experiments. These included feed composition and rates, and adsorber temperature, pressure and regeneration conditions. N2 diffusive flux reverses after about 60 seconds, but CH4 adsorption continues. This causes a decay in the observed N2/CH4 separation. Therefore, optimum process conditions include rapid adsorber pressurization and short adsorption/desorp-tion/regeneration cycles. 

After further heat recovery, final cooling and condensate separation (6), the gas is sent to the pressure swing adsorption (PSA) unit (7). Loaded adsorbers are regenerated isothermally using a controlled sequence of depressurization and purging steps. 

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. 

Cyclic adsorption processes Two examples (a) thermal swing adsorption -maximization of total adsorption efficiency and minimization of consumption rate of regeneration energy, and (b) rapid pressure swing adsorption -maximization of both purity and recovery of the desired product for RPSA. Modified Sum of Weighted Objective Function (SWOF) method Modified SWOF method is superior to the conventional SWOF as it was able to find the non-convex part of the Pareto-optimal set. Ko and Moon (2002)... 

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