PDF Publication Title:
Text from PDF Page: 070
5 Validation of the mathematical model 57 on the fixed bed. Consequently, as the purge flow rate is decreased in the process simulation, the minimum required gas velocity could perhaps not be achieved for the proper adsorbent regeneration since the mathematical model does not account for any grade of gas channelling, which is evident and inevitable in every experimental PSA set-up. Accordingly, the accuracy of performance prediction increases with a purge flow rate in the system. 5.2.3 Cutting time The cutting step is a supplementary cycle design element implemented at the end of the PSA cycle terminating the blow-down and purge steps before finishing the adsorption step in the adjacent column. Cutting can be adapted in order to improve the PSA process performance of kinetic-based separation since the difference in the sorption rates of molecules in the feed gas mixture can be exploited. Whereas the duration of the blow-down step is reduced, the desorption of gases from the CMS adsorbent could still progress while the adsorber column is not opened to the ambient, as shown in Fig. 5.2.3-1. The effect is more pronounced for components with slow mass transfer kinetics due to insufficient time provided for its complete desorption from the adsorbent surface. Since in this work nitrogen is the component with slow kinetics, it is expected that losses of adsorbed nitrogen to the wasted tail-gas can be avoided. However, the effect is highly dependent on the utilised CMS-type. Besides, analogously to the previous case of changing the purge stream flow rate, the implementation of a cutting step also impacts the oxygen mass transfer zone along the adsorber during production and regeneration; thus, its adoption greatly depends on the process conditions. Hence, the influence of the cutting time on the PSA performance indicators is investigated in the range of 0 – 15 s. During experiments, the purge proportionality factor equals 40 %. The results are presented in Tab. 5.2.3-1–2 and Fig. 5.2.3-2. Fig. 5.2.3-1 Experimental and simulated pressure profiles during the blow-down step at product purity of 1000 ppm O2 at different cutting times: (a) 5 s, (b) 10 s, (c) 15s Tab. 5.2.3-1–2 show that the model predicts the influence of the cutting time on PIs very sufficiently regardless of the cutting time and purity level. This finding confirms that the implemented kinetic model represents the existing mass transfer conditions quite realistically; since any imprecision in the description of kinetics would overthrow the correctness of the mathematical model, particularly during the simulation of PIs as a function of this parameter.PDF Image | Modelling and Simulation of Twin-Bed Pressure Swing Adsorption Plants
PDF Search Title:
Modelling and Simulation of Twin-Bed Pressure Swing Adsorption PlantsOriginal File Name Searched:
dissertation_marcinek.pdfDIY PDF Search: Google It | Yahoo | Bing
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
Heat Pumps CO2 ORC Heat Pump System Platform More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)