Figure3. Comparison between experimental data and model for (a) diethyl ether and (b) ethanol for feed flow rate of 333 kmol/h
Figure 4a also shows that outlet concentration of diethyl ether exceeds its inlet concentration due to its partial replacement by ethanol. This phenomenon which is called “Roll-up” refers to the humps on the diethyl ether breakthrough curve where its concentration exceeds the feed condition. 18 According to the Yang book18, the “Roll-up” happens due to displacement of weaker adsorbate (diethyl ether) by a strong one (ethanol). In the beginning of adsorption, both diethyl ether and ethanol are adsorbed on activated carbon surfaces since there are enough empty adsorption site on the adsorbent. Figure 4b shows an interval of bed when surface of activated bed is covered by ethanol and diethyl ether, further adsorption of ethanol would replace the adsorbed diethyl ether so, desorption of diethyl ether happens and competitive adsorption behaviors exists in the bed intervals. Figure 4c shows that temperature of gas stream is increased due to the nature of exothermic adsorption process till bed saturation and then no more heat is released in which gas temperature reaches to the feed temperature.